Stage B: pipeline deadlock fixed, V MN-major applied, PV output garbage

Pipeline deadlock fixed:
- No cta_layout_vmnk on mma_si PipelineUmmaAsync
- TMA warp excluded from tmem.wait_for_alloc
- PipelineTmaStore (not TmaStorePipeline)

Bug 1 (V MN-major): fix applied
- PV MMA uses v_major=OperandMajorMode.MN
- V shaped (64,128) strides(1,64) via as_strided

Bug 2 (softmax packing): C-fragment composition store applied
- FP32 to BF16 packing works
- St32x32bOp uses Float32 (not BFloat16)

Bug 3 (PV garbage): investigating
- PV MMA cosine ~0.01 against reference
- Suspected TMEM layout mismatch between softmax P store and PV A-fragment read

Test results:
- test_mma_si_only: cosine 0.999999 PASS
- test_mma_si_pv: cosine 0.01 FAIL (pipeline works, PV output wrong)
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README.md
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CuTeDSL kernels for DeepSeek-V4 (Blackwell B200, SM100). All kernels use `cutlass.cute` (CuTeDSL) with Blackwell tensor cores.
## File Map
## Status (May 21, 2026 — 04:10 UTC)
```
cutedsl/
├── native_swa_decode.py # SWA decode attention — IN PROGRESS (v3 tcgen05 rewrite)
├── native_sparse_decode.py # Sparse (CSA/HCA) decode — NOT YET REWRITTEN
├── nvfp4_cutedsl.py # NVFP4 MoE runner (CuTeDSL) — WORKING
├── moe_pipeline.py # MoE fused SwiGLU pipeline — WORKING
├── blackwell_attention.py # vLLM bridge for Blackwell attention path
├── csa_attention.py # CSA/HCA sparse attention bridge
├── custom_ops.py # Custom CUDA ops registration
└── kernel/
└── blockscaled_gemm/
└── dense_blockscaled_gemm_persistent.py # REFERENCE: Blackwell TMEM/tcgen05 GEMM
tests/
├── test_stage_a_v2.py # ✅ Stage A: bare Q@K^T via tcgen05.mma → TMEM → GMEM
├── test_stage_b_v7.py # 🔨 Stage B: two MMAs + C-fragment softmax (runs, wrong output)
├── test_stage_b_afrag2.py # 🔨 Stage B: A-fragment store pattern (compiles, wrong output)
├── test_tmem_pure_fp32.py # ✅ FP32 ld→st roundtrip on C-fragment: cosine 0.999999
├── test_bf16_elemwise.py # ✅ FP32→BF16→FP32 elemwise + FP32 st: cosine 0.999999
├── test_recast_minimal.py # ✅ BF16 recast ld S0→st S1 via C-fragment: cosine 0.999999
├── test_bf16_recast_simple.py # ❌ BF16 recast ld/st same region (S0): zero (can't overwrite MMA output)
├── test_tmem_copy_roundtrip.py # ❌ BF16 recast + C→A mismatch: zero
├── test_stage_b_final.py # ❌ C-fragment st + A-fragment read: NaN (physical layout mismatch)
├── test_afrag_roundtrip.py # ❌ A-frag st corrupts S0 (overlapping TMEM region)
├── diag_tmem.py # Diagnostic: TMEM layout inspection
└── ...
```
## Current Status
### ✅ Stage A: Bare Q@K^T via tcgen05.mma — COMPLETE (May 20)
### ✅ Stage A: Bare Q@K^T via tcgen05.mma → TMEM → GMEM — COMPLETE
**File**: `tests/test_stage_a_v2.py`
**Result**: Q(128,128) @ K^T(128,128) → S(128,128), cosine 0.999999
Validates the full tcgen05.mma → TMEM → epilogue → GMEM path:
- tcgen05.mma with BF16 inputs, FP32 TMEM accumulator
- TMA load for A and B (cute.nvgpu.make_tiled_tma_atom_A/B)
- TMA store for C (cpasync.CopyBulkTensorTileS2GOp)
- Warp specialization: 4 epilogue warps + 1 MMA warp + 1 TMA warp = 192 threads
- PipelineTmaUmma for AB pipeline, PipelineUmmaAsync for acc pipeline
- TmemAllocator for TMEM allocation/deallocation
- utils.gemm.sm100.epilogue_tma_store for the TMEM→reg→SMEM→TMA→GMEM epilogue
### 🔨 Stage B: Two MMAs + Identity Softmax — IN PROGRESS
### 🔨 Stage B: Two MMAs + Identity Softmax — IN PROGRESS (May 20-21)
**Pipeline deadlock: FIXED. Kernel runs without deadlock.**
**Bug 1 (V MN-major): Fix applied.**
**Bug 2 (softmax packing): Fix applied, but PV output is garbage.**
**Core Problem**: The C-fragment (MMA accumulator) and A-fragment (MMA A-operand from TMEM) use **different physical TMEM address mappings** for the same logical (M,K) position. The softmax writes P via one mapping, but the PV MMA reads via the other. This produces garbage.
#### Bug 1: V B-Operand Must Be MN-Major — ✅ FIX APPLIED
#### What's Been Proven
V must be shaped (head_dim, seq) = (64, 128) with strides (1, 64) — MN-major.
PV MMA uses `v_major` (OperandMajorMode.MN) instead of `b_major` (K).
| Test | Pattern | Result | Why |
|------|---------|--------|-----|
| test_tmem_pure_fp32 | FP32 ld→st, same C-fragment layout | ✅ cos=0.999999 | C-fragment addresses self-consistent |
| test_bf16_elemwise | FP32→BF16→FP32 elemwise, C-fragment st | ✅ cos=0.999999 | BF16 conversion works, C-fragment st works |
| test_recast_minimal | BF16 recast ld S0→st S1, C-fragment | ✅ cos=0.999999 | Recast works when writing to different region |
| test_bf16_recast_simple | BF16 recast ld/st same region S0 | ❌ zero | Can't overwrite MMA output in same region |
| test_stage_b_final | C-fragment st → A-fragment read (S1) | ❌ NaN | C-layout ≠ A-layout physical addresses |
| test_stage_b_afrag2 | A-fragment st (backward FMHA pattern) | ❌ cos=-0.02 | Store + PV MMA layout compatible, but register data flow wrong |
V must use `as_strided` — default PyTorch (64,128) gives strides (128,1) which is K-major.
#### Root Cause: C-fragment vs A-fragment Physical TMEM Layout
#### Bug 2 (Packing): C-Fragment Composition Store — ✅ APPLIED, ❌ PV OUTPUT WRONG
From the CUTLASS source (`mma_traits_sm100.hpp`):
FP32→BF16 packing via C-fragment composition store (FMHA pattern) runs without error.
The softmax packing overwrites part of S in TMEM (P at tmem_p0_offset=32 overlaps S at offset 0).
This is intentional — S is no longer needed after softmax.
**C-fragment (MMA accumulator, FP32):**
- Layout: `((128,128),1,1):((65536,1),0,0)`**virtual** layout
- Physical TMEM addresses determined by the MMA hardware's accumulator write path
- St32x32bOp with C-fragment layout writes to C-fragment physical addresses
**FOOTGUN**: `St32x32bOp` MUST use Float32, NOT BFloat16.
⚠️ The recast view for P packing uses the LOAD layout (128 BF16 elements), not the store composition shape.
**A-fragment (MMA A-operand from TMEM, BF16, K-major, M=128):**
- Layout: `((128,16),1,4):((65536,1),0,16)`**physical** TMEM layout
- A[m, k_inner] → `tmem[dp=m, col=base + 16*mma_k + k_inner]`
- BK=64 = 4 K=16 MMA atoms, NOT one K=64 atom
- The 4D fragment partition order is NOT the physical TMEM order
#### Bug 3 (NEW): PV MMA Output Is Garbage — 🔨 INVESTIGATING
**The St32x32bOp with C-fragment composition writes to C-layout physical addresses. The PV MMA reads from A-layout physical addresses. These are different physical locations.**
#### Forward FMHA's Approach (FP16 Only!)
Forward FMHA uses a recast pattern to pack 2×FP16 into 1×FP32 register, then St32x32bOp writes to a C-fragment composition subview. **But forward FMHA explicitly rejects BF16:**
```python
if in_dtype not in {cutlass.Float8E4M3FN, cutlass.Float16}:
raise ValueError(in_dtype must be Float8E4M3FN or Float16)
```
The recast softmax path is validated for FP16, NOT BF16. Our BF16 use is outside the tested path.
#### Backward FMHA's Approach (BF16 Supported)
Backward FMHA writes dV to TMEM using the A-fragment layout:
1. `tdVrP_iter = cute.recast_ptr(tSTtST.iterator, dtype=self.element_dtype)` — recast C-fragment iterator to BF16
2. `tdVrP = cute.make_tensor(tdVrP_iter, tOrP.layout)` — A-fragment layout, C-fragment base
3. `tmem_store_atom = cute.make_copy_atom(St32x32bOp(Repetition(8)), self.element_dtype)` — BF16 store atom
4. Quantize via `make_rmem_tensor(input.shape, element_dtype)` + `.load()/.store(v.to(element_dtype))` — true BF16 register, NOT recast
5. Reshape: `cute.make_tensor(rBf16.iterator, cute.make_layout(tStcS.shape))` — match store partition shape
This compiles and runs for us (no crash), but the output is still wrong (cosine -0.02). The remaining issue is the **register layout mismatch**:
- Load partition (C-fragment): 128 FP32 values per thread (full 128×128 QK tile)
- Store partition (A-fragment): 64 BF16 values per thread (128×64 P tile for PV MMA K=64)
- The backward FMHA uses `quantize()` + reshape, but our element counts differ because the QK tile is 128×128 while P only needs 128×64
#### Next Steps for Stage B
1. **Fix the register data flow** — properly subselect the P-relevant 64 BF16 columns from the 128 FP32 load columns, or use the backward FMHA's PdO MMA tiler (M=128, N=64) instead of (M=128, N=128)
2. **Verify A-fragment store roundtrip** — write known BF16 values via A-fragment store, have PV MMA read them back via A-fragment, confirm the physical TMEM addresses match
3. **Once data flow is correct, add online softmax** (Stage C)
The PV MMA produces cosine ~0.01 against the reference. Suspected cause: TMEM layout mismatch between the softmax P store (C-fragment composition layout) and the PV MMA A-fragment read (`p_tmem_s` layout from `make_smem_layout_a`). These should alias the same physical TMEM columns by the sequential-flattening property, but the specific layout functions may compute different shapes/strides.
### 🔨 Stage C: Online Softmax — AFTER B
The hard part. Per the pseudocode:
- Epilogue warps tcgen05.ld scores from TMEM into register fragments
- Compute per-row: tile_max, new_max, rescale = exp(old_max - new_max)
- Apply rescale to tmem_output in place (tmem_output *= rescale)
- Compute exp(scores - new_max), tcgen05.st back to TMEM as P operand for MMA2
- Update row_sum = row_sum * rescale + new_tile_sum
**The register fragment layout from tcgen05.ld is NOT (row, col).** It's determined by the MMA instruction's partition of the accumulator. Need to figure out the mapping from fragment indices to logical (head, kv_pos) positions for per-row softmax operations. fmha.py uses `tTMEM_LOADrS.load().reduce(cute.ReductionOp.MAX, row_max, 0)` for the row max — a built-in reduction that handles the layout.
Per the pseudocode: epilogue warps compute per-row tile_max, rescale, exp, store P back to TMEM.
### 🔨 Stage D: FP8 Paged KV Gather — AFTER C
Replace BF16 TMA load of KV with:
- Indexed cp.async gather from paged KV cache (fp8)
- Per-position dequant scale (inv_scale) applied during or after gather
- Keep KV in fp8 in SMEM, let the MMA's per-row scale handle dequant (like blockscaled GEMM)
Replace BF16 TMA load with FP8 paged KV gather + per-position dequant.
### Architecture: Per-Tile Flow (from /root/fragile-kernel-example/README.md)
---
## Pipeline Deadlock — ✅ FIXED (May 21)
v20-v25 all deadlocked on GPU. Three root causes found and fixed:
### Fix 1: PipelineUmmaAsync for mma_si Must NOT Pass cta_layout_vmnk
FMHA's mma_s0/mma_s1 PipelineUmmaAsync calls do NOT pass cta_layout_vmnk. Removing it fixes the deadlock.
### Fix 2: TMA Warp Must NOT Call tmem.wait_for_alloc()
The tmem allocation barrier has `num_threads = 32 * (mma_warp + epilogue_warps)`. The TMA warp is NOT part of this barrier. Calling `wait_for_alloc()` from the TMA warp corrupts the barrier.
### Fix 3: PipelineTmaStore (not TmaStorePipeline)
`pipeline.TmaStorePipeline` does not exist. The correct name is `pipeline.PipelineTmaStore`.
---
## ⛔ DEAD TEST: test_stage_b_v21.py — DELETED, DO NOT RECREATE
v21 attempted both Bug 1 and Bug 2 fixes in a hand-rolled pipeline kernel. It deadlocks on GPU. Root cause: pipeline synchronization mismatch. **Do not recreate.** Write from scratch using fmha.py as the reference.
---
## ⛔ FOOTGUNS — CUTLASS CuTeDSL Landmines
### 1. St32x32bOp with 16-bit dtype → ILLEGAL MEMORY ACCESS
`St32x32bOp(Repetition(N), BFloat16)` crashes at runtime. You MUST use `St32x32bOp(Repetition(N), Float32)` and pack 2×16-bit values into 1×Float32 backing words via `cute.recast_ptr`. The 16-bit type only appears in the recast view, never in the store atom itself.
### 2. V B-Operand Major Mode ≠ K Major Mode
FMHA requires `v_major_mode == OperandMajorMode.MN`. Passing K's K-major mode for V is WRONG. V must be shaped (head_dim, seq) with strides (1, head_dim) to produce MN-major. Standard PyTorch row-major (seq, head_dim) gives K-major.
### 3. CuTe Nested Layout Modes Flatten Sequentially
A layout like `((128,16),1,(4,2)):((65536,1),0,(16,64))` looks "non-sequential" but flattens to `addr = m*65536 + k` when k = k0 + 16*k1 + 64*k2 (CuTe row-major order). Do NOT assume nested modes imply non-sequential physical addressing. The C-fragment composition and A-fragment alias the same TMEM columns.
### 4. PipelineUmmaAsync Consumer Group = Thread Count, NOT Warp Count
```python
# WRONG: consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 4)
# CORRECT: consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(warp_ids))
```
### 5. PipelineUmmaAsync for mma_si Must NOT Pass cta_layout_vmnk
Passing `cta_layout_vmnk` to the mma_si PipelineUmmaAsync causes deadlock. FMHA does not pass it. Remove it.
### 6. TMA Warp Must NOT Call tmem.wait_for_alloc()
The tmem allocation barrier only includes MMA + epilogue warps. The TMA warp is excluded. Calling `wait_for_alloc()` from the TMA warp corrupts the barrier.
---
## Architecture: Per-Tile Flow
```
For each KV tile:
@@ -138,107 +111,57 @@ For each KV tile:
a. tcgen05.ld scores from TMEM → register fragments
b. Compute tile_max, new_max, rescale = exp(old_max - new_max)
c. Apply rescale to tmem_output IN PLACE (tmem_output *= rescale)
d. tcgen05.st exp(scores - new_max) back to TMEM → now it's the P operand
d. tcgen05.st exp(scores - new_max) back to TMEM → P operand (via C-fragment composition)
e. Release mma_si (softmax_done — MMA warp can re-acquire and issue PV MMA)
4. MMA warp waits on mma_si acquire (softmax done), then MMA2: P @ sKV[stage] → tmem_output (accumulate=True)
4. MMA warp waits on mma_si acquire (softmax done), MMA2: P @ sV → tmem_output (accumulate=True)
5. Stage released, load warp can refill it
After all tiles: epilogue warps tcgen05.ld tmem_output, divide by row_sum, cast to BF16, store to GMEM
```
### ✅ NVFP4 MoE (CuTeDSL) — WORKING
- `nvfp4_cutedsl.py` + `moe_pipeline.py`
- CuTeDSL NVFP4 Linear (q_a, kv, q_b, o_b) — cosine 0.994+
- CuTeDSL NVFP4 MoE (L1 gate+up, SiLU, L2 down) — cosine 0.988
- Fused SwiGLU epilogue (granularity-8 weight interleave) — cosine 0.988
---
### ✅ FP8 KV Quantize/Dequant — WORKING
- FP8 KV: cosine 0.9997
- NVFP4 KV: cosine 0.9943 (2x smaller than FP8)
- Paged KV cache read/write: cosine 1.0
## Test Results
### ❌ Sparse Decode Attention — NOT YET REWRITTEN
`native_sparse_decode.py` still has the scalar FMA bug. Needs the same tcgen05.mma rewrite.
| File | Description | Cosine | Status |
|------|-------------|--------|--------|
| `test_stage_a_v2.py` | Q@K^T only | 0.999999 | ✅ PASS |
| `test_mma_si_only.py` | Q@K^T + mma_si pipeline (no PV) | 0.999999 | ✅ PASS |
| `test_softmax_only.py` | Q@K^T + softmax packing, output S | 0.52 | ❌ S overwritten by P (expected) |
| `test_mma_si_pv.py` | Q@K^T + softmax + P@V (V MN-major) | 0.01 | ❌ PV output garbage |
| `test_stage_b_v7.py` | Q@K^T + C-fragment softmax (V=K, wrong major) | -0.02 | ❌ wrong major + P packing |
| `test_stage_b_v20.py` | Q@K^T + softmax (V=K, PipelineTmaStore bug) | N/A | ❌ compile error |
### ✅ Full Attention Pipeline (standalone tests) — WORKING
- FP8 KV → full attention: cosine 0.9997
- CSA sparse attention (cr=4): works
- HCA sparse attention (cr=128): works
- Merged CSA+SWA attention: works
---
## Critical APIs & Lessons
### C-fragment ≠ A-fragment TMEM Physical Layout — THE MAY 20-21 FINDING
**The St32x32bOp with C-fragment composition writes to C-layout physical TMEM addresses. The PV MMA reads from A-layout physical TMEM addresses. These are DIFFERENT physical locations for the same logical (M,K) position.**
For the softmax to work, P must be written to TMEM using the A-fragment's physical layout, not the C-fragment's. The backward FMHA does this correctly by:
1. Creating the store destination with A-fragment layout + recast C-fragment iterator
2. Using a BF16 St32x32bOp atom
3. True BF16 register (not FP32 recast) via quantize() pattern
### Forward FMHA Recast Pattern — FP16 ONLY
The `cute.recast_ptr` + `.store(v.to(FP16))` pattern for packing 2×16-bit into 1×FP32 register is validated for FP16 only. BF16 is rejected in forward FMHA. The BF16 recast produces zero output when writing to the same TMEM region as the MMA output, and NaN when writing to a different region read via A-fragment.
### PipelineUmmaAsync consumer group size — thread count, NOT warp count
```python
# WRONG (caused CUDA_ERROR_LAUNCH_FAILED):
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 4) # warp count
# CORRECT (matches fmha.py):
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(softmax_warp_ids)) # thread count
```
### TMEM offset arithmetic
- `find_tmem_tensor_col_offset(fragment)` — returns physical TMEM column count
- QK accumulator: 128 TMEM columns
- A-fragment offset: `acc_dtype.width // q_dtype.width * tmem_p0_offset` (F32/BF16=2)
- `find_tmem_tensor_col_offset(fragment)` — returns physical TMEM column count (with 0x8000 tag for A-fragments)
- QK accumulator C fragment: 128 TMEM columns
- PV A-fragment: offset 0x8020 = tag(0x8000) + col(32) — the 0x8000 is a TMEM memory-space identifier
- `tOrP0 = cute.make_tensor(tOrP.iterator + acc_dtype.width // q_dtype.width * tmem_p0_offset, tOrP.layout)` — A-fragment offset scaled by dtype width ratio (F32/BF16 = 2)
### A-fragment iterator must use recast C-fragment pointer
When creating the P tensor for PV MMA's A-operand, the iterator must be the C-fragment's iterator recast to BF16:
### pv_mma_tiler — FMHA Convention
```python
tP_iter = cute.recast_ptr(tStS.iterator, dtype=self.q_dtype)
tP = cute.make_tensor(tP_iter, p_tmem_s.outer)
tOrP = pv_thr.make_fragment_A(tP)[None, None, None, 0]
```
Without the recast, the A-fragment addresses are computed from an FP32 pointer base, giving wrong physical TMEM addresses (illegal memory access crash).
### V SMEM aliasing (K and V share SMEM)
```python
v_smem_s = utils.sm100.make_smem_layout_b(pv_mma, pv_mma_tiler, b_dtype, 1)
sV_ptr = cute.recast_ptr(sB.iterator, v_smem_s.inner)
sV = cute.make_tensor(sV_ptr, v_smem_s.outer)
tCrV = pv_mma.make_fragment_B(sV)
pv_mma_tiler = (qk_mma_tiler[0], qk_mma_tiler[2], qk_mma_tiler[1])
# = (M, head_dim, QK_N) = (128, 64, 128) for head_dim=64
```
### `make_trivial_tiled_mma` has two overloads
### make_trivial_tiled_mma — Use New Overload
```python
# New (preferred):
make_trivial_tiled_mma(a_dtype, b_dtype, a_leading_mode, b_leading_mode,
acc_dtype, cta_group, mma_tiler_mn, a_source=SMEM)
# Deprecated (still works, used by Stage A):
make_trivial_tiled_mma(ab_dtype, a_leading_mode, b_leading_mode,
acc_dtype, cta_group, mma_tiler_mn, a_source=SMEM)
```
### Other APIs discovered from Stage A
### 3D tensors required
Tensors must be 3D (M, K, L) for `cute.local_tile` — add L=1 dimension.
1. **`cute.Tensor` API** — `cutlass_torch.from_dlpack(t).mark_layout_dynamic(leading_dim=...)`
2. **3D tensors** — Tensors must be 3D (M, K, L) for `cute.local_tile` — add L=1 dimension
3. **`PipelineTmaUmma.create(...).make_participants()`** — returns `(producer, consumer)` pair
4. **`utils.gemm.sm100.epilogue_tma_store`** — handles transform + partition/dcopy. DO NOT hand-roll.
5. **`get_num_tmem_alloc_cols`**correct TMEM allocation (accepts list of fragments, sums cols, rounds to power of 2)
6. **`smem.allocate_tensor()`**for SMEM tensors (not SharedStorage struct for A/B/C)
7. **`LayoutEnum.from_tensor(a).mma_major_mode()`** — major mode from cute tensor
8. **Minimum valid N tile for tcgen05.mma BF16**: 32 (step 32, range 32-256)
### Other APIs
1. `cutlass_torch.from_dlpack(t).mark_layout_dynamic(leading_dim=...)` — CuTe tensor from PyTorch
2. `PipelineTmaUmma.create(...).make_participants()` — returns (producer, consumer) pair
3. `utils.gemm.sm100.epilogue_tma_store` — handles transform + partition/dcopy. DO NOT hand-roll.
4. `smem.allocate_tensor()`for SMEM tensors
5. `LayoutEnum.from_tensor(a).mma_major_mode()`major mode from cute tensor
## Environment
@@ -247,15 +170,6 @@ make_trivial_tiled_mma(ab_dtype, a_leading_mode, b_leading_mode,
- **PYTHONPATH**: `/root/dsv4-nvfp4-workspace/kernel`
- **Model**: `/root/nvidia-meeting/DeepSeek-V4-Pro-NVFP4`
- **vLLM repo**: `/root/dsv4-nvfp4-workspace/vllm` (modified for Blackwell)
- **Pseudocode**: `/root/fragile-kernel-example/README.md` — authoritative per-tile attention flow
- **Pseudocode**: `/root/fragile-kernel-example/README.md`
- **fmha.py reference**: `/root/cutlass/examples/python/CuTeDSL/cute/blackwell/kernel/attention/fmha/fmha.py`
- **fmha_bwd.py reference**: `/root/cutlass/examples/python/CuTeDSL/cute/blackwell/kernel/attention/fmha/fmha_bwd.py`
## 4-Stage Build Plan
| Stage | Goal | Status |
|-------|------|--------|
| A | Bare Q@K^T via tcgen05.mma → TMEM → GMEM | ✅ COMPLETE |
| B | Two MMAs + identity softmax (validates TMEM A operand, shared KV, layout transform, barrier ordering) | 🔨 A-fragment store compiles, register data flow needs fixing |
| C | Online softmax between MMA1 and MMA2 (the hard part) | ⬜ TODO |
| D | FP8 paged KV gather + dequant (replace BF16 TMA load) | ⬜ TODO |

247
tests/test_mma_si_only.py Normal file
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@@ -0,0 +1,247 @@
"""
Minimal test: Stage A + mma_si pipeline (no PV, no V).
If this deadlocks, the mma_si pipeline is broken.
If this passes, the deadlock is caused by adding V/PV.
"""
import torch, cutlass, cutlass.cute as cute, cutlass.utils as utils, cutlass.pipeline as pipeline
from cutlass.cute.nvgpu import cpasync, tcgen05
from cutlass import Float32, BFloat16, Int32, Boolean, const_expr
from cutlass.utils import LayoutEnum
from cutlass.utils.tmem_allocator import find_tmem_tensor_col_offset
import cuda.bindings.driver as cuda
class MmaSiTest:
def __init__(self, mma_tiler_mn, use_2cta_instrs=False, use_tma_store=True):
self.acc_dtype = Float32; self.qk_acc_dtype = Float32
self.q_dtype = BFloat16; self.o_dtype = BFloat16; self.c_dtype = BFloat16
self.use_2cta_instrs = use_2cta_instrs; self.use_tma_store = use_tma_store
self.mma_tiler_mn = mma_tiler_mn; self.mma_tiler = (*mma_tiler_mn, 1)
self.cluster_shape_mn = (1, 1)
self.cta_group = tcgen05.CtaGroup.TWO if use_2cta_instrs else tcgen05.CtaGroup.ONE
self.epilogue_warp_id = (0, 1, 2, 3)
self.mma_warp_id = 4; self.tma_warp_id = 5
self.threads_per_cta = 192
self.epilog_sync_bar_id = 1; self.tmem_alloc_sync_bar_id = 2; self.tmem_dealloc_sync_bar_id = 3
self.num_c_stage = 2
def _setup(self, tiled_mma):
mma_inst_k = cute.size(tiled_mma.shape_mnk, mode=[2])
self.mma_tiler = (*self.mma_tiler_mn, mma_inst_k * 4)
self.cluster_layout_vmnk = cute.tiled_divide(cute.make_layout((1,1,1)), (tiled_mma.thr_id.shape,))
self.cta_tile_shape_mnk = (
self.mma_tiler[0] // cute.size(tiled_mma.thr_id.shape),
self.mma_tiler[1], self.mma_tiler[2])
self.epi_tile = utils.sm100.compute_epilogue_tile_shape(
self.cta_tile_shape_mnk, self.use_2cta_instrs, self.c_layout, self.o_dtype)
self.num_ab_stage = 1; self.num_acc_stage = 1
self.a_smem_s = utils.sm100.make_smem_layout_a(tiled_mma, self.mma_tiler, self.q_dtype, 1)
self.b_smem_s = utils.sm100.make_smem_layout_b(tiled_mma, self.mma_tiler, self.q_dtype, 1)
self.c_smem_s = utils.sm100.make_smem_layout_epi(self.o_dtype, self.c_layout, self.epi_tile, 2)
acc_shape = tiled_mma.partition_shape_C(self.mma_tiler[:2])
tCtAcc_fake = tiled_mma.make_fragment_C(cute.append(acc_shape, self.num_acc_stage))
self.num_tmem_alloc_cols = utils.get_num_tmem_alloc_cols(tCtAcc_fake, arch="sm_100")
a_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
b_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
self.num_tma_load_bytes = (
cute.size_in_bytes(self.q_dtype, a_smem) + cute.size_in_bytes(self.q_dtype, b_smem)
) * cute.size(tiled_mma.thr_id.shape)
@cute.jit
def __call__(self, a: cute.Tensor, b: cute.Tensor, c: cute.Tensor, stream: cuda.CUstream):
self.q_dtype = a.element_type; self.o_dtype = c.element_type; self.c_dtype = self.o_dtype
self.a_major = LayoutEnum.from_tensor(a).mma_major_mode()
self.b_major = LayoutEnum.from_tensor(b).mma_major_mode()
self.c_layout = LayoutEnum.from_tensor(c)
tiled_mma = utils.sm100.make_trivial_tiled_mma(
self.q_dtype, self.q_dtype, self.a_major, self.b_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.SMEM)
self._setup(tiled_mma)
a_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
b_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
tma_a, tma_ta = cute.nvgpu.make_tiled_tma_atom_A(
utils.sm100.cluster_shape_to_tma_atom_A(self.cluster_shape_mn, tiled_mma.thr_id),
a, a_smem, self.mma_tiler, tiled_mma, self.cluster_layout_vmnk.shape)
tma_b, tma_tb = cute.nvgpu.make_tiled_tma_atom_B(
utils.sm100.cluster_shape_to_tma_atom_B(self.cluster_shape_mn, tiled_mma.thr_id),
b, b_smem, self.mma_tiler, tiled_mma, self.cluster_layout_vmnk.shape)
epi_smem = cute.select(self.c_smem_s, mode=[0, 1])
tma_c, tma_tc = cpasync.make_tiled_tma_atom(cpasync.CopyBulkTensorTileS2GOp(), c, epi_smem, self.epi_tile)
self._kernel(tiled_mma, tma_a, tma_ta, tma_b, tma_tb, tma_c, tma_tc,
self.cluster_layout_vmnk, self.a_smem_s, self.b_smem_s, self.c_smem_s, self.epi_tile
).launch(grid=(1,1,1), block=[self.threads_per_cta,1,1], stream=stream)
@cute.kernel
def _kernel(self, tiled_mma, tma_a, mA, tma_b, mB, tma_c, mC, cl_vmnk, a_smem_s, b_smem_s, c_smem_s, epi_tile):
warp_idx = cute.arch.make_warp_uniform(cute.arch.warp_idx())
tidx, _, _ = cute.arch.thread_idx()
use_2cta = cute.size(tiled_mma.thr_id.shape) == 2
if warp_idx == self.tma_warp_id:
cpasync.prefetch_descriptor(tma_a); cpasync.prefetch_descriptor(tma_b); cpasync.prefetch_descriptor(tma_c)
@cute.struct
class SS:
ab_bar: cute.struct.MemRange[cutlass.Int64, self.num_ab_stage * 2]
mma_si_bar: cute.struct.MemRange[cutlass.Int64, 2] # ADDED: mma_si
acc_bar: cute.struct.MemRange[cutlass.Int64, self.num_acc_stage * 2]
tmem_dealloc: cutlass.Int64
holding: cutlass.Int32
smem = utils.SmemAllocator(); st = smem.allocate(SS)
ab_p, ab_c = pipeline.PipelineTmaUmma.create(
barrier_storage=st.ab_bar.data_ptr(), num_stages=self.num_ab_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 1),
tx_count=self.num_tma_load_bytes, cta_layout_vmnk=cl_vmnk, defer_sync=True
).make_participants()
# ADDED: mma_si pipeline (same as v27)
mma_si_prod, mma_si_cons = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.mma_si_bar.data_ptr(), num_stages=1,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id)),
).make_participants()
acc_pipe = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.acc_bar.data_ptr(), num_stages=self.num_acc_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(
pipeline.Agent.Thread, len(self.epilogue_warp_id) * (2 if use_2cta else 1)),
cta_layout_vmnk=cl_vmnk, defer_sync=True)
tmem_bar = pipeline.NamedBarrier(barrier_id=self.tmem_alloc_sync_bar_id,
num_threads=32 * len((self.mma_warp_id, *self.epilogue_warp_id)))
tmem = utils.TmemAllocator(st.holding.ptr, barrier_for_retrieve=tmem_bar,
allocator_warp_id=self.epilogue_warp_id[0], is_two_cta=use_2cta,
two_cta_tmem_dealloc_mbar_ptr=st.tmem_dealloc.ptr)
pipeline.pipeline_init_arrive(cluster_shape_mn=cl_vmnk, is_relaxed=True)
sA = smem.allocate_tensor(element_type=self.q_dtype, layout=a_smem_s.outer, byte_alignment=128, swizzle=a_smem_s.inner)
sB = smem.allocate_tensor(element_type=self.q_dtype, layout=b_smem_s.outer, byte_alignment=128, swizzle=b_smem_s.inner)
sC = smem.allocate_tensor(element_type=self.o_dtype, layout=c_smem_s.outer, byte_alignment=128, swizzle=c_smem_s.inner)
gA = cute.local_tile(mA, cute.slice_(self.mma_tiler, (None,0,None)), (None,None,None))
gB = cute.local_tile(mB, cute.slice_(self.mma_tiler, (0,None,None)), (None,None,None))
gC = cute.local_tile(mC, cute.slice_(self.mma_tiler, (None,None,0)), (None,None,None))
k_cnt = cute.size(gA, mode=[3])
thr_mma = tiled_mma.get_slice(0)
tCgA = thr_mma.partition_A(gA); tCgB = thr_mma.partition_B(gB); tCgC = thr_mma.partition_C(gC)
a_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,0,None,0)).shape)
tAsA, tAgA = cpasync.tma_partition(tma_a, 0, a_lay, cute.group_modes(sA,0,3), cute.group_modes(tCgA,0,3))
b_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,None,0,0)).shape)
tBsB, tBgB = cpasync.tma_partition(tma_b, 0, b_lay, cute.group_modes(sB,0,3), cute.group_modes(tCgB,0,3))
tAgA = tAgA[(None,0,None,0)]; tBgB = tBgB[(None,0,None,0)]
tCrA = tiled_mma.make_fragment_A(sA); tCrB = tiled_mma.make_fragment_B(sB)
acc_shape = thr_mma.partition_shape_C(self.mma_tiler[:2])
tCtAcc_fake = tiled_mma.make_fragment_C(cute.append(acc_shape, self.num_acc_stage))
pipeline.pipeline_init_wait(cluster_shape_mn=cl_vmnk)
# TMA WARP
if warp_idx == self.tma_warp_id:
ab_p.reset(); peek = ab_p.try_acquire()
for kt in cutlass.range(k_cnt, unroll=1):
h = ab_p.acquire_and_advance(peek)
cute.copy(tma_a, tAgA[(None,h.count)], tAsA[(None,h.index)], tma_bar_ptr=h.barrier)
cute.copy(tma_b, tBgB[(None,h.count)], tBsB[(None,h.index)], tma_bar_ptr=h.barrier)
peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_p.try_acquire()
ab_p.tail()
# MMA WARP — same as Stage A but with mma_si pipeline added (just acquire/commit, no PV)
if warp_idx == self.mma_warp_id:
tmem.wait_for_alloc()
tmem_ptr = tmem.retrieve_ptr(self.qk_acc_dtype)
tCtAcc_base = cute.make_tensor(tmem_ptr, tCtAcc_fake.layout)
tCtAcc = tCtAcc_base[(None, None, None, 0)]
ab_c.reset(); peek = ab_c.try_wait()
acc_prod_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Producer, self.num_acc_stage)
acc_pipe.producer_acquire(acc_prod_st)
tiled_mma.set(tcgen05.Field.ACCUMULATE, False)
# ADDED: mma_si acquire (just like v27)
s0_handle = mma_si_prod.acquire_and_advance()
for kt in range(k_cnt):
h = ab_c.wait_and_advance(peek)
nblk = cute.size(tCrA, mode=[2])
for kb in cutlass.range(nblk, unroll_full=True):
cute.gemm(tiled_mma, tCtAcc, tCrA[(None,None,kb,h.index)], tCrB[(None,None,kb,h.index)], tCtAcc)
tiled_mma.set(tcgen05.Field.ACCUMULATE, True)
h.release(); peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_c.try_wait()
cute.arch.fence_view_async_tmem_store()
# ADDED: mma_si commit + second acquire (like v27)
s0_handle.commit()
s0_handle = mma_si_prod.acquire_and_advance() # wait for "softmax"
# In real use, softmax would happen here. For this test, just release immediately.
# The epilogue will do mma_si_cons wait_and_advance then release.
# After the second acquire returns, continue to acc_pipe commit.
acc_pipe.producer_commit(acc_prod_st)
acc_prod_st.advance()
acc_pipe.producer_tail(acc_prod_st)
# EPILOGUE WARPS — same as Stage A but with mma_si wait+release added
if warp_idx < self.mma_warp_id:
tmem.allocate(self.num_tmem_alloc_cols)
tmem.wait_for_alloc()
tmem_ptr = tmem.retrieve_ptr(self.qk_acc_dtype)
tCtAcc_base = cute.make_tensor(tmem_ptr, tCtAcc_fake.layout)
# ADDED: mma_si wait + release (simulating softmax)
si_handle = mma_si_cons.wait_and_advance()
# (no actual softmax — just release immediately)
si_handle.release()
acc_cons_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Consumer, self.num_acc_stage)
c_grp = pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id))
c_pipe = pipeline.PipelineTmaStore.create(num_stages=self.num_c_stage, producer_group=c_grp)
acc_cons_st = utils.gemm.sm100.epilogue_tma_store(
self, tidx, warp_idx, tma_c, tCtAcc_base, sC, tCgC,
epi_tile, 0, const_expr(lambda x: x), (0,0,0), acc_cons_st, acc_pipe, c_pipe)
c_pipe.producer_tail()
tmem.relinquish_alloc_permit()
tmem.free(tmem_ptr)
def test():
torch.manual_seed(42)
m, n, k = 128, 128, 64
a = torch.randn(m, k, 1, dtype=torch.bfloat16, device='cuda')
b = torch.randn(n, k, 1, dtype=torch.bfloat16, device='cuda')
c = torch.zeros(m, n, 1, dtype=torch.bfloat16, device='cuda')
ref = a[:,:,0].float() @ b[:,:,0].float().T
import cutlass.torch as ct
mA = ct.from_dlpack(a).mark_layout_dynamic(leading_dim=ct.get_leading_dim(a))
mB = ct.from_dlpack(b).mark_layout_dynamic(leading_dim=ct.get_leading_dim(b))
mC = ct.from_dlpack(c).mark_layout_dynamic(leading_dim=ct.get_leading_dim(c))
stream = cuda.CUstream(torch.cuda.current_stream().cuda_stream)
kernel = MmaSiTest(mma_tiler_mn=(128, 128))
print('Compiling...', flush=True)
compiled = cute.compile(kernel, mA, mB, mC, stream)
print('Running...', flush=True)
compiled(mA, mB, mC, stream)
torch.cuda.synchronize()
out = c[:,:,0].float()
cos = torch.nn.functional.cosine_similarity(out.flatten().unsqueeze(0), ref.flatten().unsqueeze(0)).item()
print('MMA+mma_si only test: cosine {:.6f} {}'.format(cos, 'PASS' if cos >= 0.99 else 'FAIL'))
if __name__ == '__main__':
test()

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tests/test_mma_si_pv.py Normal file
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"""
Stage B test: MMA + mma_si + V TMA + PV MMA.
Built incrementally from working test_mma_si_only.
"""
import torch, cutlass, cutlass.cute as cute, cutlass.utils as utils, cutlass.pipeline as pipeline
from cutlass.cute.nvgpu import cpasync, tcgen05
from cutlass import Float32, BFloat16, Int32, Boolean, const_expr
from cutlass.utils import LayoutEnum
from cutlass.utils.tmem_allocator import find_tmem_tensor_col_offset
import cuda.bindings.driver as cuda
class MmaSiPvTest:
def __init__(self, mma_tiler_mn, use_2cta_instrs=False, use_tma_store=True):
self.acc_dtype = Float32; self.qk_acc_dtype = Float32
self.q_dtype = BFloat16; self.o_dtype = BFloat16; self.c_dtype = BFloat16
self.use_2cta_instrs = use_2cta_instrs; self.use_tma_store = use_tma_store
self.mma_tiler_mn = mma_tiler_mn; self.mma_tiler = (*mma_tiler_mn, 1)
self.cluster_shape_mn = (1, 1)
self.cta_group = tcgen05.CtaGroup.TWO if use_2cta_instrs else tcgen05.CtaGroup.ONE
self.epilogue_warp_id = (0, 1, 2, 3)
self.mma_warp_id = 4; self.tma_warp_id = 5
self.threads_per_cta = 192
self.epilog_sync_bar_id = 1; self.tmem_alloc_sync_bar_id = 2; self.tmem_dealloc_sync_bar_id = 3
self.num_c_stage = 2
def _setup(self, qk_mma, pv_mma):
qk_inst_k = cute.size(qk_mma.shape_mnk, mode=[2])
self.qk_mma_tiler = (*self.mma_tiler_mn, qk_inst_k * 4)
self.pv_mma_tiler = (self.qk_mma_tiler[0], self.qk_mma_tiler[2], self.qk_mma_tiler[1])
self.mma_tiler = self.qk_mma_tiler
self.cluster_layout_vmnk = cute.tiled_divide(cute.make_layout((1,1,1)), (qk_mma.thr_id.shape,))
self.cta_tile_shape_mnk = (
self.qk_mma_tiler[0] // cute.size(qk_mma.thr_id.shape),
self.qk_mma_tiler[1], self.qk_mma_tiler[2])
self.epi_tile = utils.sm100.compute_epilogue_tile_shape(
self.cta_tile_shape_mnk, self.use_2cta_instrs, self.c_layout, self.o_dtype)
self.num_ab_stage = 1; self.num_acc_stage = 1
self.a_smem_s = utils.sm100.make_smem_layout_a(qk_mma, self.mma_tiler, self.q_dtype, 1)
self.b_smem_s = utils.sm100.make_smem_layout_b(qk_mma, self.mma_tiler, self.q_dtype, 1)
self.v_smem_s = utils.sm100.make_smem_layout_b(pv_mma, self.pv_mma_tiler, self.q_dtype, 1)
self.p_tmem_s = utils.sm100.make_smem_layout_a(pv_mma, self.pv_mma_tiler, self.q_dtype, 1)
self.c_smem_s = utils.sm100.make_smem_layout_epi(self.o_dtype, self.c_layout, self.epi_tile, 2)
qk_thr = qk_mma.get_slice(0)
qk_acc_shape = qk_thr.partition_shape_C(self.qk_mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
s_cols = find_tmem_tensor_col_offset(tStS)
pv_thr = pv_mma.get_slice(0)
pv_acc_shape = pv_thr.partition_shape_C(self.pv_mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
o_cols = find_tmem_tensor_col_offset(tOtO)
self.tilePlikeFP32 = self.qk_mma_tiler[1] // Float32.width * self.o_dtype.width
self.tmem_s0_offset = 0
self.tmem_p0_offset = 32
self.tmem_o0_offset = s_cols
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, self.num_acc_stage))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, self.num_acc_stage))
self.num_tmem_alloc_cols = utils.get_num_tmem_alloc_cols([tCtS_fake, tCtO_fake], arch="sm_100")
a_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
b_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
v_smem = cute.slice_(self.v_smem_s, (None, None, None, 0))
self.num_tma_load_bytes = (
cute.size_in_bytes(self.q_dtype, a_smem) + cute.size_in_bytes(self.q_dtype, b_smem) +
cute.size_in_bytes(self.q_dtype, v_smem)
) * cute.size(qk_mma.thr_id.shape)
@cute.jit
def __call__(self, q: cute.Tensor, k: cute.Tensor, v: cute.Tensor, c: cute.Tensor, stream: cuda.CUstream):
self.q_dtype = q.element_type; self.o_dtype = c.element_type; self.c_dtype = self.o_dtype
self.a_major = LayoutEnum.from_tensor(q).mma_major_mode()
self.b_major = LayoutEnum.from_tensor(k).mma_major_mode()
self.v_major = LayoutEnum.from_tensor(v).mma_major_mode()
self.c_layout = LayoutEnum.from_tensor(c)
qk_mma = utils.sm100.make_trivial_tiled_mma(
self.q_dtype, self.q_dtype, self.a_major, self.b_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.SMEM)
pv_mma = utils.sm100.make_trivial_tiled_mma(
self.q_dtype, self.q_dtype, cute.nvgpu.OperandMajorMode.K, self.v_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.TMEM)
self._setup(qk_mma, pv_mma)
q_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
k_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
v_smem = cute.slice_(self.v_smem_s, (None, None, None, 0))
tma_q, tma_tq = cute.nvgpu.make_tiled_tma_atom_A(
utils.sm100.cluster_shape_to_tma_atom_A(self.cluster_shape_mn, qk_mma.thr_id),
q, q_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
tma_k, tma_tk = cute.nvgpu.make_tiled_tma_atom_B(
utils.sm100.cluster_shape_to_tma_atom_B(self.cluster_shape_mn, qk_mma.thr_id),
k, k_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
tma_v, tma_tv = cute.nvgpu.make_tiled_tma_atom_B(
utils.sm100.cluster_shape_to_tma_atom_B(self.cluster_shape_mn, pv_mma.thr_id),
v, v_smem, self.pv_mma_tiler, pv_mma, self.cluster_layout_vmnk.shape)
epi_smem = cute.select(self.c_smem_s, mode=[0, 1])
tma_c, tma_tc = cpasync.make_tiled_tma_atom(cpasync.CopyBulkTensorTileS2GOp(), c, epi_smem, self.epi_tile)
self._kernel(qk_mma, pv_mma, tma_q, tma_tq, tma_k, tma_tk, tma_v, tma_tv,
tma_c, tma_tc, self.cluster_layout_vmnk,
self.a_smem_s, self.b_smem_s, self.v_smem_s, self.p_tmem_s, self.c_smem_s, self.epi_tile
).launch(grid=(1,1,1), block=[self.threads_per_cta,1,1], stream=stream)
@cute.kernel
def _kernel(self, qk_mma, pv_mma, tma_q, mQ, tma_k, mK, tma_v, mV,
tma_c, mC, cl_vmnk, a_smem_s, b_smem_s, v_smem_s, p_tmem_s, c_smem_s, epi_tile):
warp_idx = cute.arch.make_warp_uniform(cute.arch.warp_idx())
tidx, _, _ = cute.arch.thread_idx()
use_2cta = cute.size(qk_mma.thr_id.shape) == 2
if warp_idx == self.tma_warp_id:
cpasync.prefetch_descriptor(tma_q); cpasync.prefetch_descriptor(tma_k)
cpasync.prefetch_descriptor(tma_v); cpasync.prefetch_descriptor(tma_c)
@cute.struct
class SS:
ab_bar: cute.struct.MemRange[cutlass.Int64, self.num_ab_stage * 2]
mma_si_bar: cute.struct.MemRange[cutlass.Int64, 2]
acc_bar: cute.struct.MemRange[cutlass.Int64, self.num_acc_stage * 2]
tmem_dealloc: cutlass.Int64
holding: cutlass.Int32
smem = utils.SmemAllocator(); st = smem.allocate(SS)
ab_p, ab_c = pipeline.PipelineTmaUmma.create(
barrier_storage=st.ab_bar.data_ptr(), num_stages=self.num_ab_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 1),
tx_count=self.num_tma_load_bytes, cta_layout_vmnk=cl_vmnk, defer_sync=True
).make_participants()
mma_si_prod, mma_si_cons = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.mma_si_bar.data_ptr(), num_stages=1,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id)),
).make_participants()
acc_pipe = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.acc_bar.data_ptr(), num_stages=self.num_acc_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(
pipeline.Agent.Thread, len(self.epilogue_warp_id) * (2 if use_2cta else 1)),
cta_layout_vmnk=cl_vmnk, defer_sync=True)
tmem_bar = pipeline.NamedBarrier(barrier_id=self.tmem_alloc_sync_bar_id,
num_threads=32 * len((self.mma_warp_id, *self.epilogue_warp_id)))
tmem = utils.TmemAllocator(st.holding.ptr, barrier_for_retrieve=tmem_bar,
allocator_warp_id=self.epilogue_warp_id[0], is_two_cta=use_2cta,
two_cta_tmem_dealloc_mbar_ptr=st.tmem_dealloc.ptr)
pipeline.pipeline_init_arrive(cluster_shape_mn=cl_vmnk, is_relaxed=True)
sQ = smem.allocate_tensor(element_type=self.q_dtype, layout=a_smem_s.outer, byte_alignment=128, swizzle=a_smem_s.inner)
sK = smem.allocate_tensor(element_type=self.q_dtype, layout=b_smem_s.outer, byte_alignment=128, swizzle=b_smem_s.inner)
sV = smem.allocate_tensor(element_type=self.q_dtype, layout=v_smem_s.outer, byte_alignment=128, swizzle=v_smem_s.inner)
sC = smem.allocate_tensor(element_type=self.o_dtype, layout=c_smem_s.outer, byte_alignment=128, swizzle=c_smem_s.inner)
gQ = cute.local_tile(mQ, cute.slice_(self.qk_mma_tiler, (None,0,None)), (None,None,None))
gK = cute.local_tile(mK, cute.slice_(self.qk_mma_tiler, (0,None,None)), (None,None,None))
gC = cute.local_tile(mC, cute.slice_(self.qk_mma_tiler, (None,None,0)), (None,None,None))
k_cnt = cute.size(gQ, mode=[3])
qk_thr = qk_mma.get_slice(0)
pv_thr = pv_mma.get_slice(0)
tCgQ = qk_thr.partition_A(gQ); tCgK = qk_thr.partition_B(gK); tCgC = qk_thr.partition_C(gC)
a_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,0,None,0)).shape)
tAsQ, tAgQ = cpasync.tma_partition(tma_q, 0, a_lay, cute.group_modes(sQ,0,3), cute.group_modes(tCgQ,0,3))
b_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,None,0,0)).shape)
tBsK, tBgK = cpasync.tma_partition(tma_k, 0, b_lay, cute.group_modes(sK,0,3), cute.group_modes(tCgK,0,3))
tAgQ = tAgQ[(None,0,None,0)]; tBgK = tBgK[(None,0,None,0)]
gV = cute.local_tile(mV, cute.slice_(self.pv_mma_tiler, (0,None,None)), (None,None,None))
tCgV = pv_thr.partition_B(gV)
tVsV, tVgV = cpasync.tma_partition(tma_v, 0, b_lay, cute.group_modes(sV,0,3), cute.group_modes(tCgV,0,3))
tVgV = tVgV[(None,0,None,0)]
tCrQ = qk_mma.make_fragment_A(sQ); tCrK = qk_mma.make_fragment_B(sK)
tCrV = pv_mma.make_fragment_B(sV)
qk_acc_shape = qk_thr.partition_shape_C(self.qk_mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
tStS0 = cute.make_tensor(tStS.iterator + self.tmem_s0_offset, tStS.layout)
pv_acc_shape = pv_thr.partition_shape_C(self.pv_mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
tOtO0 = cute.make_tensor(tOtO.iterator + self.tmem_o0_offset, tOtO.layout)
tP = cute.make_tensor(tStS.iterator, p_tmem_s.outer)
tOrP_base = pv_thr.make_fragment_A(tP)
tOrP = tOrP_base[(None, None, None, 0)]
tOrP0 = cute.make_tensor(
tOrP.iterator + self.qk_acc_dtype.width // self.q_dtype.width * self.tmem_p0_offset,
tOrP.layout)
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, self.num_acc_stage))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, self.num_acc_stage))
pipeline.pipeline_init_wait(cluster_shape_mn=cl_vmnk)
# ═══ TMA LOAD WARP ═══
if warp_idx == self.tma_warp_id:
ab_p.reset(); peek = ab_p.try_acquire()
for kt in cutlass.range(k_cnt, unroll=1):
h = ab_p.acquire_and_advance(peek)
cute.copy(tma_q, tAgQ[(None,h.count)], tAsQ[(None,h.index)], tma_bar_ptr=h.barrier)
cute.copy(tma_k, tBgK[(None,h.count)], tBsK[(None,h.index)], tma_bar_ptr=h.barrier)
cute.copy(tma_v, tVgV[(None,h.count)], tVsV[(None,h.index)], tma_bar_ptr=h.barrier)
peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_p.try_acquire()
ab_p.tail()
# ═══ MMA WARP ═══
if warp_idx == self.mma_warp_id:
tmem.wait_for_alloc()
ab_c.reset(); peek = ab_c.try_wait()
s0_handle = mma_si_prod.acquire_and_advance()
acc_prod_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Producer, self.num_acc_stage)
acc_pipe.producer_acquire(acc_prod_st)
qk_mma.set(tcgen05.Field.ACCUMULATE, False)
for kt in range(k_cnt):
h = ab_c.wait_and_advance(peek)
nblk = cute.size(tCrQ, mode=[2])
for kb in cutlass.range(nblk, unroll_full=True):
cute.gemm(qk_mma, tStS0, tCrQ[(None,None,kb,h.index)], tCrK[(None,None,kb,h.index)], tStS0)
qk_mma.set(tcgen05.Field.ACCUMULATE, True)
h.release(); peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_c.try_wait()
cute.arch.fence_view_async_tmem_store()
s0_handle.commit()
s0_handle = mma_si_prod.acquire_and_advance() # wait for softmax done
# PV MMA
pv_mma.set(tcgen05.Field.ACCUMULATE, True)
tCrV_s = tCrV[(None, None, None, 0)]
nblk_pv = cute.size(tOrP0, mode=[2])
for kb in cutlass.range(nblk_pv, unroll_full=True):
cute.gemm(pv_mma, tOtO0, tOrP0[(None,None,kb)], tCrV_s[(None,None,kb)], tOtO0)
acc_pipe.producer_commit(acc_prod_st)
acc_prod_st.advance()
acc_pipe.producer_tail(acc_prod_st)
# ═══ EPILOGUE WARPS ═══
if warp_idx < self.mma_warp_id:
tmem.allocate(self.num_tmem_alloc_cols)
tmem.wait_for_alloc()
tmem_ptr = tmem.retrieve_ptr(self.qk_acc_dtype)
sfw_idx = tidx % (32 * len(self.epilogue_warp_id))
# TMEM load/store setup for softmax packing
tmem_load_atom = cute.make_copy_atom(
tcgen05.copy.Ld32x32bOp(tcgen05.copy.Repetition(32)), self.qk_acc_dtype)
tiled_tmem_load = tcgen05.make_tmem_copy(tmem_load_atom, tStS0)
thr_load = tiled_tmem_load.get_slice(sfw_idx)
tTMEM_LOADtS = thr_load.partition_S(tStS0)
cS = cute.make_identity_tensor((self.qk_mma_tiler[0], self.qk_mma_tiler[1]))
tScS = qk_thr.partition_C(cS)
tTMEM_LOADcS = thr_load.partition_D(tScS)
tStS_P_layout = cute.composition(tStS.layout, cute.make_layout((128, self.tilePlikeFP32)))
tStS_P = cute.make_tensor(tStS.iterator + self.tmem_p0_offset, tStS_P_layout)
tmem_store_atom = cute.make_copy_atom(
tcgen05.copy.St32x32bOp(tcgen05.copy.Repetition(32)), self.qk_acc_dtype)
tiled_tmem_store = tcgen05.make_tmem_copy(tmem_store_atom, tStS_P)
thr_store = tiled_tmem_store.get_slice(sfw_idx)
tTMEM_STOREtS_x4 = thr_store.partition_D(tStS_P)
tScS_P_layout = cute.composition(tScS.layout, cute.make_layout((128, self.tilePlikeFP32)))
tScS_P = cute.make_tensor(tScS.iterator, tScS_P_layout)
tTMEM_STOREcS = thr_store.partition_S(tScS_P)
si_handle = mma_si_cons.wait_and_advance()
# FP32 → BF16 packing
tTMEM_LOADrS = cute.make_rmem_tensor(tTMEM_LOADcS.shape, self.qk_acc_dtype)
cute.copy(tiled_tmem_load, tTMEM_LOADtS, tTMEM_LOADrS)
tTMEM_STORErS_x4 = cute.make_rmem_tensor(tTMEM_STOREcS.shape, self.qk_acc_dtype)
tTMEM_STORErS_x4_e = cute.make_tensor(
cute.recast_ptr(tTMEM_STORErS_x4.iterator, dtype=self.q_dtype),
tTMEM_LOADrS.layout)
frg_cnt = 4
frg_tile = cute.size(tTMEM_LOADrS) // frg_cnt
tTMEM_LOADrS_frg = cute.logical_divide(tTMEM_LOADrS, cute.make_layout(frg_tile))
tTMEM_STORErS_x4_e_frg = cute.logical_divide(
tTMEM_STORErS_x4_e, cute.make_layout(frg_tile))
for j in range(frg_cnt):
s_vec = tTMEM_LOADrS_frg[None, j].load()
tTMEM_STORErS_x4_e_frg[None, j].store(s_vec.to(self.q_dtype))
cute.copy(tiled_tmem_store, tTMEM_STORErS_x4, tTMEM_STOREtS_x4)
cute.arch.fence_view_async_tmem_store()
si_handle.release()
# Output epilogue
tCtO_base = cute.make_tensor(tmem_ptr + self.tmem_o0_offset, tCtO_fake.layout)
acc_cons_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Consumer, self.num_acc_stage)
c_grp = pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id))
c_pipe = pipeline.PipelineTmaStore.create(num_stages=self.num_c_stage, producer_group=c_grp)
acc_cons_st = utils.gemm.sm100.epilogue_tma_store(
self, tidx, warp_idx, tma_c, tCtO_base, sC, tCgC,
epi_tile, 0, const_expr(lambda x: x), (0,0,0), acc_cons_st, acc_pipe, c_pipe)
c_pipe.producer_tail()
tmem.relinquish_alloc_permit()
tmem.free(tmem_ptr)
def test():
torch.manual_seed(42)
m, n, head_dim = 128, 128, 64
q = torch.randn(m, head_dim, 1, dtype=torch.bfloat16, device='cuda')
k = torch.randn(n, head_dim, 1, dtype=torch.bfloat16, device='cuda')
v_base = torch.randn(head_dim, n, dtype=torch.bfloat16, device='cuda')
v = v_base.as_strided((head_dim, n), (1, head_dim)).unsqueeze(-1)
c = torch.zeros(m, head_dim, 1, dtype=torch.bfloat16, device='cuda')
qf = q[:,:,0].float(); kf = k[:,:,0].float(); vf = v_base.float()
ref = qf @ kf.T @ vf.T
import cutlass.torch as ct
mQ = ct.from_dlpack(q).mark_layout_dynamic(leading_dim=ct.get_leading_dim(q))
mK = ct.from_dlpack(k).mark_layout_dynamic(leading_dim=ct.get_leading_dim(k))
mV = ct.from_dlpack(v).mark_layout_dynamic(leading_dim=ct.get_leading_dim(v))
mC = ct.from_dlpack(c).mark_layout_dynamic(leading_dim=ct.get_leading_dim(c))
stream = cuda.CUstream(torch.cuda.current_stream().cuda_stream)
kernel = MmaSiPvTest(mma_tiler_mn=(128, 128))
print('Compiling...', flush=True)
compiled = cute.compile(kernel, mQ, mK, mV, mC, stream)
print('Running...', flush=True)
compiled(mQ, mK, mV, mC, stream)
torch.cuda.synchronize()
out = c[:,:,0].float()
cos = torch.nn.functional.cosine_similarity(out.flatten().unsqueeze(0), ref.flatten().unsqueeze(0)).item()
max_err = (out - ref).abs().max().item()
print('MMA+mma_si+PV test (V MN-major): cosine {:.6f}, max_err {:.6f} {}'.format(cos, max_err, 'PASS' if cos >= 0.99 else 'FAIL'))
if __name__ == '__main__':
test()

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"""
Isolated test for Bug 1: PV MMA with V MN-major.
Only tests the PV MMA (P@V) with V as MN-major B-operand.
No QK MMA, no identity softmax, no pipeline complexity.
P comes from TMEM (a_source=TMEM), V comes from SMEM (b from TMA load).
Architecture:
- TMA load V into SMEM
- P pre-populated in TMEM (via small QK MMA or direct write)
- PV MMA: P @ V → O in TMEM
- Epilogue: TMEM → GMEM
For simplicity, P is computed via a QK MMA first (Q@K^T → P in TMEM),
then PV MMA uses P from TMEM. No softmax — identity pass-through.
"""
import torch, cutlass, cutlass.cute as cute, cutlass.utils as utils, cutlass.pipeline as pipeline
from cutlass.cute.nvgpu import cpasync, tcgen05
from cutlass import Float32, BFloat16, Int32, Boolean, const_expr
from cutlass.utils import LayoutEnum
from cutlass.utils.tmem_allocator import find_tmem_tensor_col_offset
import cuda.bindings.driver as cuda
class PvMmaTest:
def __init__(self, mma_tiler_mn, use_2cta_instrs=False, use_tma_store=True):
self.acc_dtype = Float32; self.qk_acc_dtype = Float32
self.q_dtype = BFloat16; self.o_dtype = BFloat16
self.use_2cta_instrs = use_2cta_instrs; self.use_tma_store = use_tma_store
self.mma_tiler_mn = mma_tiler_mn; self.mma_tiler = (*mma_tiler_mn, 1)
self.cluster_shape_mn = (1, 1)
self.cta_group = tcgen05.CtaGroup.TWO if use_2cta_instrs else tcgen05.CtaGroup.ONE
self.mma_warp_id = 0
self.tma_warp_id = 1
self.threads_per_cta = 64
self.num_c_stage = 2
def _setup(self, qk_mma, pv_mma):
qk_inst_k = cute.size(qk_mma.shape_mnk, mode=[2])
self.qk_mma_tiler = (*self.mma_tiler_mn, qk_inst_k * 4)
self.pv_mma_tiler = (self.qk_mma_tiler[0], self.qk_mma_tiler[2], self.qk_mma_tiler[1])
self.mma_tiler = self.qk_mma_tiler
print(f"[pv_test] qk_mma_tiler = {self.qk_mma_tiler}")
print(f"[pv_test] pv_mma_tiler = {self.pv_mma_tiler}")
self.cluster_layout_vmnk = cute.tiled_divide(cute.make_layout((1,1,1)), (qk_mma.thr_id.shape,))
# Compute epilogue tile from PV output (not QK)
cta_tile_shape_mnk = (
self.qk_mma_tiler[0] // cute.size(qk_mma.thr_id.shape),
self.qk_mma_tiler[1],
self.qk_mma_tiler[2],
)
self.epi_tile = utils.sm100.compute_epilogue_tile_shape(
cta_tile_shape_mnk, self.use_2cta_instrs, self.c_layout, self.o_dtype)
self.num_ab_stage = 1; self.num_acc_stage = 1
self.a_smem_s = utils.sm100.make_smem_layout_a(qk_mma, self.mma_tiler, self.a_dtype, 1)
self.b_smem_s = utils.sm100.make_smem_layout_b(qk_mma, self.mma_tiler, self.b_dtype, 1)
self.v_smem_s = utils.sm100.make_smem_layout_b(pv_mma, self.pv_mma_tiler, self.b_dtype, 1)
self.p_tmem_s = utils.sm100.make_smem_layout_a(pv_mma, self.pv_mma_tiler, self.q_dtype, 1)
self.c_smem_s = utils.sm100.make_smem_layout_epi(self.o_dtype, self.c_layout, self.epi_tile, 2)
qk_thr = qk_mma.get_slice(0)
qk_acc_shape = qk_thr.partition_shape_C(self.mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
s_cols = find_tmem_tensor_col_offset(tStS)
pv_thr = pv_mma.get_slice(0)
pv_acc_shape = pv_thr.partition_shape_C(self.pv_mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
o_cols = find_tmem_tensor_col_offset(tOtO)
self.tmem_s0_offset = 0
self.tmem_p0_offset = 0 # P = S (identity softmax, same TMEM)
self.tmem_o0_offset = s_cols
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, self.num_acc_stage))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, self.num_acc_stage))
self.tmem_alloc_cols = utils.get_num_tmem_alloc_cols([tCtS_fake, tCtO_fake], arch="sm_100")
a_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
b_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
self.num_tma_load_bytes = (
cute.size_in_bytes(self.a_dtype, a_smem) + cute.size_in_bytes(self.b_dtype, b_smem)
) * cute.size(qk_mma.thr_id.shape)
@cute.jit
def __call__(self, q: cute.Tensor, k: cute.Tensor, v: cute.Tensor, c: cute.Tensor, stream: cuda.CUstream):
self.a_dtype = q.element_type; self.b_dtype = k.element_type; self.c_dtype = c.element_type
self.a_major = LayoutEnum.from_tensor(q).mma_major_mode()
self.b_major = LayoutEnum.from_tensor(k).mma_major_mode()
self.v_major = LayoutEnum.from_tensor(v).mma_major_mode()
self.c_layout = LayoutEnum.from_tensor(c)
print(f"[pv_test] a_major (Q) = {self.a_major}")
print(f"[pv_test] b_major (K) = {self.b_major}")
print(f"[pv_test] v_major (V) = {self.v_major}")
qk_mma = utils.sm100.make_trivial_tiled_mma(
self.a_dtype, self.b_dtype, self.a_major, self.b_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.SMEM)
# BUG 1 FIX: PV MMA uses V's MN-major mode
pv_mma = utils.sm100.make_trivial_tiled_mma(
self.q_dtype, self.b_dtype, cute.nvgpu.OperandMajorMode.K, self.v_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.TMEM)
self._setup(qk_mma, pv_mma)
q_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
k_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
v_smem = cute.slice_(self.v_smem_s, (None, None, None, 0))
tma_q, tma_tq = cute.nvgpu.make_tiled_tma_atom_A(
utils.sm100.cluster_shape_to_tma_atom_A(self.cluster_shape_mn, qk_mma.thr_id),
q, q_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
tma_k, tma_tk = cute.nvgpu.make_tiled_tma_atom_B(
utils.sm100.cluster_shape_to_tma_atom_B(self.cluster_shape_mn, qk_mma.thr_id),
k, k_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
tma_v, tma_tv = cute.nvgpu.make_tiled_tma_atom_B(
utils.sm100.cluster_shape_to_tma_atom_B(self.cluster_shape_mn, pv_mma.thr_id),
v, v_smem, self.pv_mma_tiler, pv_mma, self.cluster_layout_vmnk.shape)
epi_smem = cute.select(self.c_smem_s, mode=[0, 1])
tma_c, tma_tc = cpasync.make_tiled_tma_atom(cpasync.CopyBulkTensorTileS2GOp(), c, epi_smem, self.epi_tile)
self._kernel(qk_mma, pv_mma, tma_q, tma_tq, tma_k, tma_tk, tma_v, tma_tv,
tma_c, tma_tc, self.cluster_layout_vmnk,
self.a_smem_s, self.b_smem_s, self.v_smem_s, self.c_smem_s, self.epi_tile
).launch(grid=(1,1,1), block=[self.threads_per_cta,1,1], stream=stream)
@cute.kernel
def _kernel(self, qk_mma, pv_mma, tma_q, mQ, tma_k, mK, tma_v, mV,
tma_c, mC, cl_vmnk, a_smem_s, b_smem_s, v_smem_s, c_smem_s, epi_tile):
warp_idx = cute.arch.make_warp_uniform(cute.arch.warp_idx())
tidx, _, _ = cute.arch.thread_idx()
@cute.struct
class SS:
ab_bar: cute.struct.MemRange[cutlass.Int64, 2]
acc_bar: cute.struct.MemRange[cutlass.Int64, 2]
tmem_dealloc: cutlass.Int64
holding: cutlass.Int32
smem = utils.SmemAllocator(); st = smem.allocate(SS)
ab_p, ab_c = pipeline.PipelineTmaUmma.create(
barrier_storage=st.ab_bar.data_ptr(), num_stages=1,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 32),
tx_count=self.num_tmama_load_bytes, cta_layout_vmnk=cl_vmnk, defer_sync=True
).make_participants()
acc_pipe = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.acc_bar.data_ptr(), num_stages=1,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 32),
cta_layout_vmnk=cl_vmnk, defer_sync=True)
tmem_bar = pipeline.NamedBarrier(barrier_id=2, num_threads=64)
tmem = utils.TmemAllocator(st.holding.ptr, barrier_for_retrieve=tmem_bar,
allocator_warp_id=0, is_two_cta=False,
two_cta_tmem_dealloc_mbar_ptr=st.tmem_dealloc.ptr)
pipeline.pipeline_init_arrive(cluster_shape_mn=cl_vmnk, is_relaxed=True)
sQ = smem.allocate_tensor(element_type=self.a_dtype, layout=a_smem_s.outer, byte_alignment=128, swizzle=a_smem_s.inner)
sK = smem.allocate_tensor(element_type=self.b_dtype, layout=b_smem_s.outer, byte_alignment=128, swizzle=b_smem_s.inner)
sV = smem.allocate_tensor(element_type=self.b_dtype, layout=v_smem_s.outer, byte_alignment=128, swizzle=v_smem_s.inner)
sC = smem.allocate_tensor(element_type=self.o_dtype, layout=c_smem_s.outer, byte_alignment=128, swizzle=c_smem_s.inner)
gQ = cute.local_tile(mQ, cute.slice_(self.mma_tiler, (None,0,None)), (None,None,None))
gK = cute.local_tile(mK, cute.slice_(self.mma_tiler, (0,None,None)), (None,None,None))
gC = cute.local_tile(mC, cute.slice_(self.mma_tiler, (None,None,0)), (None,None,None))
k_cnt = cute.size(gQ, mode=[3])
qk_thr = qk_mma.get_slice(0)
pv_thr = pv_mma.get_slice(0)
tCgQ = qk_thr.partition_A(gQ); tCgK = qk_thr.partition_B(gK); tCgC = qk_thr.partition_C(gC)
a_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,0,None,0)).shape)
tAsQ, tAgQ = cpasync.tma_partition(tma_q, 0, a_lay, cute.group_modes(sQ,0,3), cute.group_modes(tCgQ,0,3))
b_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,None,0,0)).shape)
tBsK, tBgK = cpasync.tma_partition(tma_k, 0, b_lay, cute.group_modes(sK,0,3), cute.group_modes(tCgK,0,3))
tAgQ = tAgQ[(None,0,None,0)]; tBgK = tBgK[(None,0,None,0)]
gV = cute.local_tile(mV, cute.slice_(self.pv_mma_tiler, (0,None,None)), (None,None,None))
tCgV = pv_thr.partition_B(gV)
tVsV, tVgV = cpasync.tma_partition(tma_v, 0, b_lay, cute.group_modes(sV,0,3), cute.group_modes(tCgV,0,3))
tVgV = tVgV[(None,0,None,0)]
tCrQ = qk_mma.make_fragment_A(sQ); tCrK = qk_mma.make_fragment_B(sK)
tCrV = pv_mma.make_fragment_B(sV)
qk_acc_shape = qk_thr.partition_shape_C(self.mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
tStS0 = cute.make_tensor(tStS.iterator + self.tmem_s0_offset, tStS.layout)
pv_acc_shape = pv_thr.partition_shape_C(self.pv_mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
tOtO0 = cute.make_tensor(tOtO.iterator + self.tmem_o0_offset, tOtO.layout)
# P from S TMEM — same location, MMA A-operand for PV
tP = cute.make_tensor(tStS.iterator, self.p_tmem_s.outer)
tOrP_base = pv_thr.make_fragment_A(tP)
tOrP = tOrP_base[(None, None, None, 0)]
tOrP0 = tOrP # P is at same TMEM offset as S (identity softmax)
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, self.num_acc_stage))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, self.num_acc_stage))
pipeline.pipeline_init_wait(cluster_shape_mn=cl_vmnk)
# WARP 1: TMA load
if warp_idx == self.tma_warp_id:
tmem.wait_for_alloc()
ab_p.reset(); peek = ab_p.try_acquire()
for kt in cutlass.range(k_cnt, unroll=1):
h = ab_p.acquire_and_advance(peek)
cute.copy(tma_q, tAgQ[(None,h.count)], tAsQ[(None,h.index)], tma_bar_ptr=h.barrier)
cute.copy(tma_k, tBgK[(None,h.count)], tBsK[(None,h.index)], tma_bar_ptr=h.barrier)
cute.copy(tma_v, tVgV[(None,h.count)], tVsV[(None,h.index)], tma_bar_ptr=h.barrier)
peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_p.try_acquire()
ab_p.tail()
# WARP 0: MMA (both QK and PV)
if warp_idx == self.mma_warp_id:
tmem.wait_for_alloc()
ab_c.reset(); peek = ab_c.try_wait()
acc_prod_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Producer, self.num_acc_stage)
acc_pipe.producer_acquire(acc_prod_st)
# QK MMA: Q @ K^T → S in TMEM
qk_mma.set(tcgen05.Field.ACCUMULATE, False)
for kt in range(k_cnt):
h = ab_c.wait_and_advance(peek)
nblk = cute.size(tCrQ, mode=[2])
for kb in cutlass.range(nblk, unroll_full=True):
cute.gemm(qk_mma, tStS0, tCrQ[(None,None,kb,h.index)], tCrK[(None,None,kb,h.index)], tStS0)
qk_mma.set(tcgen05.Field.ACCUMULATE, True)
h.release(); peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_c.try_wait()
cute.arch.fence_view_async_tmem_store()
# PV MMA: P @ V → O in TMEM (identity softmax: P = S)
pv_mma.set(tcgen05.Field.ACCUMULATE, True)
tCrV_s = tCrV[(None, None, None, 0)]
nblk_pv = cute.size(tOrP0, mode=[2])
for kb in cutlass.range(nblk_pv, unroll_full=True):
cute.gemm(pv_mma, tOtO0, tOrP0[(None,None,kb)], tCrV_s[(None,None,kb)], tOtO0)
acc_pipe.producer_commit(acc_prod_st)
acc_prod_st.advance()
acc_pipe.producer_tail(acc_prod_st)
def test():
torch.manual_seed(42)
m, n, head_dim = 128, 128, 64
q = torch.randn(m, head_dim, 1, dtype=torch.bfloat16, device='cuda')
k = torch.randn(n, head_dim, 1, dtype=torch.bfloat16, device='cuda')
# V: MN-major — (head_dim, seq) with strides (1, head_dim)
v_base = torch.randn(head_dim, n, dtype=torch.bfloat16, device='cuda')
v = v_base.as_strided((head_dim, n), (1, head_dim)).unsqueeze(-1)
c = torch.zeros(m, head_dim, 1, dtype=torch.bfloat16, device='cuda')
qf = q[:,:,0].float(); kf = k[:,:,0].float(); vf = v_base.float()
# Q@K^T = (128,128), then P@V: (128,128) @ (64,128).T = (128,64)
# Wait — with MN-major V, the MMA interprets V as (head_dim, seq) MN-major
# which means the MMA computes P @ V (not P @ V^T)
# So reference is: (Q @ K^T) @ V where V is (64, 128) row-major
# But V has strides (1, 64), so V is NOT row-major.
# The kernel sees V as MN-major B-operand, which means:
# PV MMA computes: P[m, k] * V[n, k] -> O[m, n]
# This is P @ V^T in matrix notation
# So reference: Q@K^T @ V^T where V^T is (128, 64)
ref = qf @ kf.T @ vf.T # (128,128) @ (128,64) = (128,64)
import cutlass.torch as ct
mQ = ct.from_dlpack(q).mark_layout_dynamic(leading_dim=ct.get_leading_dim(q))
mK = ct.from_dlpack(k).mark_layout_dynamic(leading_dim=ct.get_leading_dim(k))
mV = ct.from_dlpack(v).mark_layout_dynamic(leading_dim=ct.get_leading_dim(v))
mC = ct.from_dlpack(c).mark_layout_dynamic(leading_dim=ct.get_leading_dim(c))
stream = cuda.CUstream(torch.cuda.current_stream().cuda_stream)
kernel = PvMmaTest(mma_tiler_mn=(128, 128), use_2cta_instrs=False, use_tma_store=True)
print('Compiling...', flush=True)
compiled = cute.compile(kernel, mQ, mK, mV, mC, stream)
print('Running...', flush=True)
compiled(mQ, mK, mV, mC, stream)
torch.cuda.synchronize()
out = c[:,:,0].float()
cos = torch.nn.functional.cosine_similarity(out.flatten().unsqueeze(0), ref.flatten().unsqueeze(0)).item()
max_err = (out - ref).abs().max().item()
print('PV MMA test (V MN-major, no softmax):')
print(' Cosine: {:.6f}, Max error: {:.6f}'.format(cos, max_err))
print(' {}'.format('PASS' if cos >= 0.99 else 'FAIL'))
if __name__ == '__main__':
test()

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"""
Test: QK + softmax packing only (no PV).
Output is the softmax-packed P (BF16) stored to GMEM via epilogue.
This tests whether the FP32→BF16 packing in TMEM works correctly.
"""
import torch, cutlass, cutlass.cute as cute, cutlass.utils as utils, cutlass.pipeline as pipeline
from cutlass.cute.nvgpu import cpasync, tcgen05
from cutlass import Float32, BFloat16, Int32, Boolean, const_expr
from cutlass.utils import LayoutEnum
from cutlass.utils.tmem_allocator import find_tmem_tensor_col_offset
import cuda.bindings.driver as cuda
class SoftmaxOnlyKernel:
def __init__(self, mma_tiler_mn, use_2cta_instrs=False, use_tma_store=True):
self.acc_dtype = Float32; self.qk_acc_dtype = Float32
self.q_dtype = BFloat16; self.o_dtype = BFloat16; self.c_dtype = BFloat16
self.use_2cta_instrs = use_2cta_instrs; self.use_tma_store = use_tma_store
self.mma_tiler_mn = mma_tiler_mn; self.mma_tiler = (*mma_tiler_mn, 1)
self.cluster_shape_mn = (1, 1)
self.cta_group = tcgen05.CtaGroup.TWO if use_2cta_instrs else tcgen05.CtaGroup.ONE
self.epilogue_warp_id = (0, 1, 2, 3)
self.mma_warp_id = 4; self.tma_warp_id = 5
self.threads_per_cta = 192
self.epilog_sync_bar_id = 1; self.tmem_alloc_sync_bar_id = 2; self.tmem_dealloc_sync_bar_id = 3
self.num_c_stage = 2
def _setup(self, tiled_mma):
mma_inst_k = cute.size(tiled_mma.shape_mnk, mode=[2])
self.mma_tiler = (*self.mma_tiler_mn, mma_inst_k * 4)
self.cluster_layout_vmnk = cute.tiled_divide(cute.make_layout((1,1,1)), (tiled_mma.thr_id.shape,))
self.cta_tile_shape_mnk = (
self.mma_tiler[0] // cute.size(tiled_mma.thr_id.shape),
self.mma_tiler[1], self.mma_tiler[2])
self.epi_tile = utils.sm100.compute_epilogue_tile_shape(
self.cta_tile_shape_mnk, self.use_2cta_instrs, self.c_layout, self.o_dtype)
self.num_ab_stage = 1; self.num_acc_stage = 1
self.a_smem_s = utils.sm100.make_smem_layout_a(tiled_mma, self.mma_tiler, self.q_dtype, 1)
self.b_smem_s = utils.sm100.make_smem_layout_b(tiled_mma, self.mma_tiler, self.q_dtype, 1)
self.c_smem_s = utils.sm100.make_smem_layout_epi(self.o_dtype, self.c_layout, self.epi_tile, 2)
acc_shape = tiled_mma.partition_shape_C(self.mma_tiler[:2])
tCtAcc_fake = tiled_mma.make_fragment_C(cute.append(acc_shape, self.num_acc_stage))
self.num_tmem_alloc_cols = utils.get_num_tmem_alloc_cols(tCtAcc_fake, arch="sm_100")
self.tilePlikeFP32 = self.mma_tiler[1] // Float32.width * self.o_dtype.width
self.tmem_s0_offset = 0
self.tmem_p0_offset = 32 # BF16 P location in TMEM
a_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
b_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
self.num_tma_load_bytes = (
cute.size_in_bytes(self.q_dtype, a_smem) + cute.size_in_bytes(self.q_dtype, b_smem)
) * cute.size(tiled_mma.thr_id.shape)
@cute.jit
def __call__(self, a: cute.Tensor, b: cute.Tensor, c: cute.Tensor, stream: cuda.CUstream):
self.q_dtype = a.element_type; self.o_dtype = c.element_type; self.c_dtype = self.o_dtype
self.a_major = LayoutEnum.from_tensor(a).mma_major_mode()
self.b_major = LayoutEnum.from_tensor(b).mma_major_mode()
self.c_layout = LayoutEnum.from_tensor(c)
tiled_mma = utils.sm100.make_trivial_tiled_mma(
self.q_dtype, self.q_dtype, self.a_major, self.b_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.SMEM)
self._setup(tiled_mma)
a_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
b_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
tma_a, tma_ta = cute.nvgpu.make_tiled_tma_atom_A(
utils.sm100.cluster_shape_to_tma_atom_A(self.cluster_shape_mn, tiled_mma.thr_id),
a, a_smem, self.mma_tiler, tiled_mma, self.cluster_layout_vmnk.shape)
tma_b, tma_tb = cute.nvgpu.make_tiled_tma_atom_B(
utils.sm100.cluster_shape_to_tma_atom_B(self.cluster_shape_mn, tiled_mma.thr_id),
b, b_smem, self.mma_tiler, tiled_mma, self.cluster_layout_vmnk.shape)
epi_smem = cute.select(self.c_smem_s, mode=[0, 1])
tma_c, tma_tc = cpasync.make_tiled_tma_atom(cpasync.CopyBulkTensorTileS2GOp(), c, epi_smem, self.epi_tile)
self._kernel(tiled_mma, tma_a, tma_ta, tma_b, tma_tb, tma_c, tma_tc,
self.cluster_layout_vmnk, self.a_smem_s, self.b_smem_s, self.c_smem_s, self.epi_tile
).launch(grid=(1,1,1), block=[self.threads_per_cta,1,1], stream=stream)
@cute.kernel
def _kernel(self, tiled_mma, tma_a, mA, tma_b, mB, tma_c, mC, cl_vmnk, a_smem_s, b_smem_s, c_smem_s, epi_tile):
warp_idx = cute.arch.make_warp_uniform(cute.arch.warp_idx())
tidx, _, _ = cute.arch.thread_idx()
use_2cta = cute.size(tiled_mma.thr_id.shape) == 2
if warp_idx == self.tma_warp_id:
cpasync.prefetch_descriptor(tma_a); cpasync.prefetch_descriptor(tma_b); cpasync.prefetch_descriptor(tma_c)
@cute.struct
class SS:
ab_bar: cute.struct.MemRange[cutlass.Int64, self.num_ab_stage * 2]
mma_si_bar: cute.struct.MemRange[cutlass.Int64, 2]
acc_bar: cute.struct.MemRange[cutlass.Int64, self.num_acc_stage * 2]
tmem_dealloc: cutlass.Int64
holding: cutlass.Int32
smem = utils.SmemAllocator(); st = smem.allocate(SS)
ab_p, ab_c = pipeline.PipelineTmaUmma.create(
barrier_storage=st.ab_bar.data_ptr(), num_stages=self.num_ab_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 1),
tx_count=self.num_tma_load_bytes, cta_layout_vmnk=cl_vmnk, defer_sync=True
).make_participants()
mma_si_prod, mma_si_cons = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.mma_si_bar.data_ptr(), num_stages=1,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id)),
).make_participants()
acc_pipe = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.acc_bar.data_ptr(), num_stages=self.num_acc_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(
pipeline.Agent.Thread, len(self.epilogue_warp_id) * (2 if use_2cta else 1)),
cta_layout_vmnk=cl_vmnk, defer_sync=True)
tmem_bar = pipeline.NamedBarrier(barrier_id=self.tmem_alloc_sync_bar_id,
num_threads=32 * len((self.mma_warp_id, *self.epilogue_warp_id)))
tmem = utils.TmemAllocator(st.holding.ptr, barrier_for_retrieve=tmem_bar,
allocator_warp_id=self.epilogue_warp_id[0], is_two_cta=use_2cta,
two_cta_tmem_dealloc_mbar_ptr=st.tmem_dealloc.ptr)
pipeline.pipeline_init_arrive(cluster_shape_mn=cl_vmnk, is_relaxed=True)
sA = smem.allocate_tensor(element_type=self.q_dtype, layout=a_smem_s.outer, byte_alignment=128, swizzle=a_smem_s.inner)
sB = smem.allocate_tensor(element_type=self.q_dtype, layout=b_smem_s.outer, byte_alignment=128, swizzle=b_smem_s.inner)
sC = smem.allocate_tensor(element_type=self.o_dtype, layout=c_smem_s.outer, byte_alignment=128, swizzle=c_smem_s.inner)
gA = cute.local_tile(mA, cute.slice_(self.mma_tiler, (None,0,None)), (None,None,None))
gB = cute.local_tile(mB, cute.slice_(self.mma_tiler, (0,None,None)), (None,None,None))
gC = cute.local_tile(mC, cute.slice_(self.mma_tiler, (None,None,0)), (None,None,None))
k_cnt = cute.size(gA, mode=[3])
thr_mma = tiled_mma.get_slice(0)
tCgA = thr_mma.partition_A(gA); tCgB = thr_mma.partition_B(gB); tCgC = thr_mma.partition_C(gC)
a_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,0,None,0)).shape)
tAsA, tAgA = cpasync.tma_partition(tma_a, 0, a_lay, cute.group_modes(sA,0,3), cute.group_modes(tCgA,0,3))
b_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,None,0,0)).shape)
tBsB, tBgB = cpasync.tma_partition(tma_b, 0, b_lay, cute.group_modes(sB,0,3), cute.group_modes(tCgB,0,3))
tAgA = tAgA[(None,0,None,0)]; tBgB = tBgB[(None,0,None,0)]
tCrA = tiled_mma.make_fragment_A(sA); tCrB = tiled_mma.make_fragment_B(sB)
acc_shape = thr_mma.partition_shape_C(self.mma_tiler[:2])
tCtAcc_fake = tiled_mma.make_fragment_C(cute.append(acc_shape, self.num_acc_stage))
# S in TMEM
tStS = thr_mma.make_fragment_C(acc_shape)
tStS0 = cute.make_tensor(tStS.iterator + self.tmem_s0_offset, tStS.layout)
pipeline.pipeline_init_wait(cluster_shape_mn=cl_vmnk)
# TMA WARP
if warp_idx == self.tma_warp_id:
ab_p.reset(); peek = ab_p.try_acquire()
for kt in cutlass.range(k_cnt, unroll=1):
h = ab_p.acquire_and_advance(peek)
cute.copy(tma_a, tAgA[(None,h.count)], tAsA[(None,h.index)], tma_bar_ptr=h.barrier)
cute.copy(tma_b, tBgB[(None,h.count)], tBsB[(None,h.index)], tma_bar_ptr=h.barrier)
peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_p.try_acquire()
ab_p.tail()
# MMA WARP
if warp_idx == self.mma_warp_id:
tmem.wait_for_alloc()
ab_c.reset(); peek = ab_c.try_wait()
s0_handle = mma_si_prod.acquire_and_advance()
acc_prod_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Producer, self.num_acc_stage)
acc_pipe.producer_acquire(acc_prod_st)
tiled_mma.set(tcgen05.Field.ACCUMULATE, False)
for kt in range(k_cnt):
h = ab_c.wait_and_advance(peek)
nblk = cute.size(tCrA, mode=[2])
for kb in cutlass.range(nblk, unroll_full=True):
cute.gemm(tiled_mma, tStS0, tCrA[(None,None,kb,h.index)], tCrB[(None,None,kb,h.index)], tStS0)
tiled_mma.set(tcgen05.Field.ACCUMULATE, True)
h.release(); peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_c.try_wait()
cute.arch.fence_view_async_tmem_store()
s0_handle.commit()
# Don't wait for softmax — just commit acc_pipe directly
acc_pipe.producer_commit(acc_prod_st)
acc_prod_st.advance()
acc_pipe.producer_tail(acc_prod_st)
# EPILOGUE WARPS
if warp_idx < self.mma_warp_id:
tmem.allocate(self.num_tmem_alloc_cols)
tmem.wait_for_alloc()
tmem_ptr = tmem.retrieve_ptr(self.qk_acc_dtype)
sfw_idx = tidx % (32 * len(self.epilogue_warp_id))
# TMEM load/store setup for softmax packing
tmem_load_atom = cute.make_copy_atom(
tcgen05.copy.Ld32x32bOp(tcgen05.copy.Repetition(32)), self.qk_acc_dtype)
tiled_tmem_load = tcgen05.make_tmem_copy(tmem_load_atom, tStS0)
thr_load = tiled_tmem_load.get_slice(sfw_idx)
tTMEM_LOADtS = thr_load.partition_S(tStS0)
cS = cute.make_identity_tensor((self.mma_tiler[0], self.mma_tiler[1]))
tScS = thr_mma.partition_C(cS)
tTMEM_LOADcS = thr_load.partition_D(tScS)
tStS_P_layout = cute.composition(tStS.layout, cute.make_layout((128, self.tilePlikeFP32)))
tStS_P = cute.make_tensor(tStS.iterator + self.tmem_p0_offset, tStS_P_layout)
tmem_store_atom = cute.make_copy_atom(
tcgen05.copy.St32x32bOp(tcgen05.copy.Repetition(32)), self.qk_acc_dtype)
tiled_tmem_store = tcgen05.make_tmem_copy(tmem_store_atom, tStS_P)
thr_store = tiled_tmem_store.get_slice(sfw_idx)
tTMEM_STOREtS_x4 = thr_store.partition_D(tStS_P)
tScS_P_layout = cute.composition(tScS.layout, cute.make_layout((128, self.tilePlikeFP32)))
tScS_P = cute.make_tensor(tScS.iterator, tScS_P_layout)
tTMEM_STOREcS = thr_store.partition_S(tScS_P)
# Wait for S ready, then do softmax packing
si_handle = mma_si_cons.wait_and_advance()
tTMEM_LOADrS = cute.make_rmem_tensor(tTMEM_LOADcS.shape, self.qk_acc_dtype)
cute.copy(tiled_tmem_load, tTMEM_LOADtS, tTMEM_LOADrS)
tTMEM_STORErS_x4 = cute.make_rmem_tensor(tTMEM_STOREcS.shape, self.qk_acc_dtype)
tTMEM_STORErS_x4_e = cute.make_tensor(
cute.recast_ptr(tTMEM_STORErS_x4.iterator, dtype=self.q_dtype),
tTMEM_LOADrS.layout)
frg_cnt = 4
frg_tile = cute.size(tTMEM_LOADrS) // frg_cnt
tTMEM_LOADrS_frg = cute.logical_divide(tTMEM_LOADrS, cute.make_layout(frg_tile))
tTMEM_STORErS_x4_e_frg = cute.logical_divide(
tTMEM_STORErS_x4_e, cute.make_layout(frg_tile))
for j in range(frg_cnt):
s_vec = tTMEM_LOADrS_frg[None, j].load()
tTMEM_STORErS_x4_e_frg[None, j].store(s_vec.to(self.q_dtype))
cute.copy(tiled_tmem_store, tTMEM_STORErS_x4, tTMEM_STOREtS_x4)
cute.arch.fence_view_async_tmem_store()
si_handle.release()
# Output: read from the P location in TMEM, not S
# Use the acc_pipe to store the BF16 P to GMEM
# But acc_pipe is committed by MMA warp for S (not P)
# So we need to use the S data from the epilogue
# Actually, let's just output the softmax-packed result by reading P from TMEM
# and storing via a second TMA store. This is complex. Let's skip for now
# and just verify the QK output is correct.
# For now, just output S (the QK accumulator) — same as Stage A
tCtAcc_base = cute.make_tensor(tmem_ptr, tCtAcc_fake.layout)
acc_cons_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Consumer, self.num_acc_stage)
c_grp = pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id))
c_pipe = pipeline.PipelineTmaStore.create(num_stages=self.num_c_stage, producer_group=c_grp)
acc_cons_st = utils.gemm.sm100.epilogue_tma_store(
self, tidx, warp_idx, tma_c, tCtAcc_base, sC, tCgC,
epi_tile, 0, const_expr(lambda x: x), (0,0,0), acc_cons_st, acc_pipe, c_pipe)
c_pipe.producer_tail()
tmem.relinquish_alloc_permit()
tmem.free(tmem_ptr)
def test():
torch.manual_seed(42)
m, n, k = 128, 128, 64
a = torch.randn(m, k, 1, dtype=torch.bfloat16, device='cuda')
b = torch.randn(n, k, 1, dtype=torch.bfloat16, device='cuda')
c = torch.zeros(m, n, 1, dtype=torch.bfloat16, device='cuda')
ref = a[:,:,0].float() @ b[:,:,0].float().T
import cutlass.torch as ct
mA = ct.from_dlpack(a).mark_layout_dynamic(leading_dim=ct.get_leading_dim(a))
mB = ct.from_dlpack(b).mark_layout_dynamic(leading_dim=ct.get_leading_dim(b))
mC = ct.from_dlpack(c).mark_layout_dynamic(leading_dim=ct.get_leading_dim(c))
stream = cuda.CUstream(torch.cuda.current_stream().cuda_stream)
kernel = SoftmaxOnlyKernel(mma_tiler_mn=(128, 128))
print('Compiling...', flush=True)
compiled = cute.compile(kernel, mA, mB, mC, stream)
print('Running...', flush=True)
compiled(mA, mB, mC, stream)
torch.cuda.synchronize()
out = c[:,:,0].float()
cos = torch.nn.functional.cosine_similarity(out.flatten().unsqueeze(0), ref.flatten().unsqueeze(0)).item()
print('Softmax-only test (QK + packing, output S): cosine {:.6f} {}'.format(cos, 'PASS' if cos >= 0.99 else 'FAIL'))
if __name__ == '__main__':
test()

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tests/test_stage_b_v13.py Normal file
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"""
Stage B v13: Two MMAs + Identity Softmax using FMHA's C-fragment packing pattern.
The key insight: the C→A "transform" is NOT a reordering — it's a PACKING.
When you write 128 BF16 values packed into 64 FP32 words via the C-fragment
composition (128, tilePlikeFP32) with St32x32bOp as FP32, the physical TMEM
locations used are exactly the ones the PV MMA's A-fragment reads from.
FMHA pattern:
1. Load S from TMEM via C-fragment layout (FP32, 128×128)
2. Convert to BF16 and pack: FP32 backing tensor + BF16 recast view
3. Store packed FP32 backing to TMEM via C-fragment composition with St32x32bOp(FP32)
4. PV MMA reads from A-fragment TMEM — same physical locations as the packed BF16
Architecture:
MMA1: Q @ K^T → tmem_scores (a_source=SMEM, accumulate=False)
Identity softmax: tcgen05.ld C-layout → F32→BF16 packed → tcgen05.st C-fragment composition
MMA2: P @ V → tmem_output (a_source=TMEM, accumulate=True)
"""
import torch, cutlass, cutlass.cute as cute, cutlass.utils as utils, cutlass.pipeline as pipeline
from cutlass.cute.nvgpu import cpasync, tcgen05
from cutlass import Float32, BFloat16, Int32, Boolean, const_expr
from cutlass.utils import LayoutEnum
from cutlass.utils.tmem_allocator import find_tmem_tensor_col_offset
import cuda.bindings.driver as cuda
class StageBIdentitySoftmax:
def __init__(self, mma_tiler_mn, use_2cta_instrs=False, use_tma_store=True):
self.acc_dtype = Float32; self.qk_acc_dtype = Float32
self.q_dtype = BFloat16; self.o_dtype = BFloat16
self.use_2cta_instrs = use_2cta_instrs; self.use_tma_store = use_tma_store
self.mma_tiler_mn = mma_tiler_mn; self.mma_tiler = (*mma_tiler_mn, 1)
self.cluster_shape_mn = (1, 1)
self.cta_group = tcgen05.CtaGroup.TWO if use_2cta_instrs else tcgen05.CtaGroup.ONE
self.epilogue_warp_id = (0, 1, 2, 3)
self.mma_warp_id = 4; self.tma_warp_id = 5
self.threads_per_cta = 192
self.epilog_sync_bar_id = 1; self.tmem_alloc_sync_bar_id = 2; self.tmem_dealloc_sync_bar_id = 3
self.num_c_stage = 2
def _setup(self, qk_mma, pv_mma):
qk_inst_k = cute.size(qk_mma.shape_mnk, mode=[2])
self.qk_mma_tiler = (*self.mma_tiler_mn, qk_inst_k * 4)
# FMHA pattern: pv_mma_tiler = (M, QK_K, QK_N) — K=QK_N, N=head_dim
self.pv_mma_tiler = (self.qk_mma_tiler[0], self.qk_mma_tiler[2], self.qk_mma_tiler[1])
self.mma_tiler = self.qk_mma_tiler
print(f"[StageB] qk_mma.shape_mnk = {qk_mma.shape_mnk}")
print(f"[StageB] pv_mma.shape_mnk = {pv_mma.shape_mnk}")
print(f"[StageB] qk_mma_tiler = {self.qk_mma_tiler}")
print(f"[StageB] pv_mma_tiler = {self.pv_mma_tiler}")
self.cta_tile_shape_mnk = (
self.qk_mma_tiler[0] // cute.size(qk_mma.thr_id.shape),
self.qk_mma_tiler[1],
self.qk_mma_tiler[2],
)
self.cluster_layout_vmnk = cute.tiled_divide(cute.make_layout((1,1,1)), (qk_mma.thr_id.shape,))
self.epi_tile = utils.sm100.compute_epilogue_tile_shape(
self.cta_tile_shape_mnk, self.use_2cta_instrs, self.c_layout, self.o_dtype)
self.num_ab_stage = 1; self.num_acc_stage = 1
self.a_smem_s = utils.sm100.make_smem_layout_a(qk_mma, self.mma_tiler, self.a_dtype, 1)
self.b_smem_s = utils.sm100.make_smem_layout_b(qk_mma, self.mma_tiler, self.b_dtype, 1)
self.v_smem_s = utils.sm100.make_smem_layout_b(pv_mma, self.pv_mma_tiler, self.b_dtype, 1)
self.p_tmem_s = utils.sm100.make_smem_layout_a(pv_mma, self.pv_mma_tiler, self.q_dtype, 1)
self.c_smem_s = utils.sm100.make_smem_layout_epi(self.o_dtype, self.c_layout, self.epi_tile, 2)
# TMEM offsets (matching fmha.py)
qk_thr = qk_mma.get_slice(0)
qk_acc_shape = qk_thr.partition_shape_C(self.mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
s_cols = find_tmem_tensor_col_offset(tStS)
pv_thr = pv_mma.get_slice(0)
pv_acc_shape = pv_thr.partition_shape_C(self.pv_mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
o_cols = find_tmem_tensor_col_offset(tOtO)
self.tilePlikeFP32 = self.qk_mma_tiler[1] // Float32.width * self.o_dtype.width
print(f"[StageB] tilePlikeFP32 = {self.tilePlikeFP32}")
# FMHA TMEM layout: S0=0, P0=32, O0=256
self.tmem_s0_offset = 0
self.tmem_p0_offset = 32
self.tmem_o0_offset = s_cols
self.tmem_alloc_cols = s_cols + o_cols
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, self.num_acc_stage))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, self.num_acc_stage))
self.num_tmem_alloc_cols = utils.get_num_tmem_alloc_cols([tCtS_fake, tCtO_fake], arch="sm_100")
print(f"[StageB] s_cols = {s_cols}, o_cols = {o_cols}")
print(f"[StageB] tmem_alloc_cols = {self.tmem_alloc_cols}")
print(f"[StageB] num_tmem_alloc_cols = {self.num_tmem_alloc_cols}")
a_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
b_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
self.num_tma_load_bytes = (
cute.size_in_bytes(self.a_dtype, a_smem) + cute.size_in_bytes(self.b_dtype, b_smem)
) * cute.size(qk_mma.thr_id.shape)
@cute.jit
def __call__(self, a: cute.Tensor, b: cute.Tensor, c: cute.Tensor, stream: cuda.CUstream):
self.a_dtype = a.element_type; self.b_dtype = b.element_type; self.c_dtype = c.element_type
self.a_major = LayoutEnum.from_tensor(a).mma_major_mode()
self.b_major = LayoutEnum.from_tensor(b).mma_major_mode()
self.c_layout = LayoutEnum.from_tensor(c)
qk_mma = utils.sm100.make_trivial_tiled_mma(
self.a_dtype, self.b_dtype, self.a_major, self.b_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.SMEM)
pv_mma = utils.sm100.make_trivial_tiled_mma(
self.a_dtype, self.b_dtype, cute.nvgpu.OperandMajorMode.K, self.b_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.TMEM)
self._setup(qk_mma, pv_mma)
a_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
b_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
tma_a, tma_ta = cute.nvgpu.make_tiled_tma_atom_A(
utils.sm100.cluster_shape_to_tma_atom_A(self.cluster_shape_mn, qk_mma.thr_id),
a, a_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
tma_b, tma_tb = cute.nvgpu.make_tiled_tma_atom_B(
utils.sm100.cluster_shape_to_tma_atom_B(self.cluster_shape_mn, qk_mma.thr_id),
b, b_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
epi_smem = cute.select(self.c_smem_s, mode=[0, 1])
tma_c, tma_tc = cpasync.make_tiled_tma_atom(cpasync.CopyBulkTensorTileS2GOp(), c, epi_smem, self.epi_tile)
self._kernel(qk_mma, pv_mma, tma_a, tma_ta, tma_b, tma_tb, tma_c, tma_tc,
self.cluster_layout_vmnk, self.a_smem_s, self.b_smem_s, self.v_smem_s, self.p_tmem_s, self.c_smem_s, self.epi_tile
).launch(grid=(1,1,1), block=[self.threads_per_cta,1,1], stream=stream)
@cute.kernel
def _kernel(self, qk_mma, pv_mma, tma_a, mA, tma_b, mB, tma_c, mC, cl_vmnk,
a_smem_s, b_smem_s, v_smem_s, p_tmem_s, c_smem_s, epi_tile):
warp_idx = cute.arch.make_warp_uniform(cute.arch.warp_idx())
tidx, _, _ = cute.arch.thread_idx()
use_2cta = cute.size(qk_mma.thr_id.shape) == 2
if warp_idx == self.tma_warp_id:
cpasync.prefetch_descriptor(tma_a); cpasync.prefetch_descriptor(tma_b); cpasync.prefetch_descriptor(tma_c)
@cute.struct
class SS:
ab_bar: cute.struct.MemRange[cutlass.Int64, self.num_ab_stage * 2]
mma_si_bar: cute.struct.MemRange[cutlass.Int64, 2]
acc_bar: cute.struct.MemRange[cutlass.Int64, self.num_acc_stage * 2]
tmem_dealloc: cutlass.Int64
holding: cutlass.Int32
smem = utils.SmemAllocator(); st = smem.allocate(SS)
ab_p, ab_c = pipeline.PipelineTmaUmma.create(
barrier_storage=st.ab_bar.data_ptr(), num_stages=self.num_ab_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 1),
tx_count=self.num_tma_load_bytes, cta_layout_vmnk=cl_vmnk, defer_sync=True
).make_participants()
mma_si_prod, mma_si_cons = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.mma_si_bar.data_ptr(), num_stages=1,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id)),
cta_layout_vmnk=cl_vmnk, defer_sync=True
).make_participants()
acc_pipe = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.acc_bar.data_ptr(), num_stages=self.num_acc_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(
pipeline.Agent.Thread, len(self.epilogue_warp_id) * (2 if use_2cta else 1)),
cta_layout_vmnk=cl_vmnk, defer_sync=True)
tmem_bar = pipeline.NamedBarrier(barrier_id=self.tmem_alloc_sync_bar_id,
num_threads=32 * len((self.mma_warp_id, *self.epilogue_warp_id)))
tmem = utils.TmemAllocator(st.holding.ptr, barrier_for_retrieve=tmem_bar,
allocator_warp_id=self.epilogue_warp_id[0], is_two_cta=use_2cta,
two_cta_tmem_dealloc_mbar_ptr=st.tmem_dealloc.ptr)
pipeline.pipeline_init_arrive(cluster_shape_mn=cl_vmnk, is_relaxed=True)
sA = smem.allocate_tensor(element_type=self.a_dtype, layout=a_smem_s.outer, byte_alignment=128, swizzle=a_smem_s.inner)
sB = smem.allocate_tensor(element_type=self.b_dtype, layout=b_smem_s.outer, byte_alignment=128, swizzle=b_smem_s.inner)
# V shares SMEM with B (same data, different layout for PV MMA)
sV_ptr = cute.recast_ptr(sB.iterator, v_smem_s.inner)
sV = cute.make_tensor(sV_ptr, v_smem_s.outer)
sC = smem.allocate_tensor(element_type=self.o_dtype, layout=c_smem_s.outer, byte_alignment=128, swizzle=c_smem_s.inner)
gA = cute.local_tile(mA, cute.slice_(self.mma_tiler, (None,0,None)), (None,None,None))
gB = cute.local_tile(mB, cute.slice_(self.mma_tiler, (0,None,None)), (None,None,None))
gC = cute.local_tile(mC, cute.slice_(self.mma_tiler, (None,None,0)), (None,None,None))
k_cnt = cute.size(gA, mode=[3])
qk_thr = qk_mma.get_slice(0)
tCgA = qk_thr.partition_A(gA); tCgB = qk_thr.partition_B(gB); tCgC = qk_thr.partition_C(gC)
a_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,0,None,0)).shape)
tAsA, tAgA = cpasync.tma_partition(tma_a, 0, a_lay, cute.group_modes(sA,0,3), cute.group_modes(tCgA,0,3))
b_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,None,0,0)).shape)
tBsB, tBgB = cpasync.tma_partition(tma_b, 0, b_lay, cute.group_modes(sB,0,3), cute.group_modes(tCgB,0,3))
tAgA = tAgA[(None,0,None,0)]; tBgB = tBgB[(None,0,None,0)]
tCrA = qk_mma.make_fragment_A(sA); tCrB = qk_mma.make_fragment_B(sB)
tCrV = pv_mma.make_fragment_B(sV)
# ── TMEM tensors ──
qk_acc_shape = qk_thr.partition_shape_C(self.mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
tStS0 = cute.make_tensor(tStS.iterator + self.tmem_s0_offset, tStS.layout)
pv_thr = pv_mma.get_slice(0)
pv_acc_shape = pv_thr.partition_shape_C(self.pv_mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
tOtO0 = cute.make_tensor(tOtO.iterator + self.tmem_o0_offset, tOtO.layout)
# ── P A-fragment for PV MMA (matching fmha.py exactly) ──
# tP uses C-fragment iterator but A-fragment (p_tmem_s) layout
tP = cute.make_tensor(tStS.iterator, p_tmem_s.outer)
tOrP_base = pv_thr.make_fragment_A(tP)
tOrP = tOrP_base[(None, None, None, 0)]
tOrP0 = cute.make_tensor(
tOrP.iterator + self.qk_acc_dtype.width // self.q_dtype.width * self.tmem_p0_offset,
tOrP.layout)
# ── Softmax store uses C-fragment composition (FMHA pattern) ──
# tStS_P: C-fragment layout composed with (128, tilePlikeFP32)
# This is where we store the packed BF16 P values
tilePlikeFP32 = self.qk_mma_tiler[1] // Float32.width * self.o_dtype.width
tStS_P_layout = cute.composition(tStS.layout, cute.make_layout((128, tilePlikeFP32)))
tStS_P = cute.make_tensor(tStS.iterator + self.tmem_p0_offset, tStS_P_layout)
print(f'[DIAG] tStS.layout: {tStS.layout}')
print(f'[DIAG] tStS_P.layout: {tStS_P.layout}')
print(f'[DIAG] tP.layout: {tP.layout}')
print(f'[DIAG] tOrP.layout: {tOrP.layout}')
print(f'[DIAG] tOrP0.layout: {tOrP0.layout}')
print(f'[DIAG] tilePlikeFP32: {tilePlikeFP32}')
print(f'[DIAG] qk_mma_tiler: {self.qk_mma_tiler}')
print(f'[DIAG] pv_mma_tiler: {self.pv_mma_tiler}')
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, self.num_acc_stage))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, self.num_acc_stage))
pipeline.pipeline_init_wait(cluster_shape_mn=cl_vmnk)
# ── TMA WARP ──
if warp_idx == self.tma_warp_id:
ab_p.reset(); peek = ab_p.try_acquire()
for kt in cutlass.range(k_cnt, unroll=1):
h = ab_p.acquire_and_advance(peek)
cute.copy(tma_a, tAgA[(None,h.count)], tAsA[(None,h.index)], tma_bar_ptr=h.barrier)
cute.copy(tma_b, tBgB[(None,h.count)], tBsB[(None,h.index)], tma_bar_ptr=h.barrier)
peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_p.try_acquire()
ab_p.tail()
# ── MMA WARP ──
if warp_idx == self.mma_warp_id:
tmem.wait_for_alloc()
ab_c.reset(); peek = ab_c.try_wait()
s0_handle = mma_si_prod.acquire_and_advance()
acc_prod_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Producer, self.num_acc_stage)
acc_pipe.producer_acquire(acc_prod_st)
qk_mma.set(tcgen05.Field.ACCUMULATE, False)
for kt in range(k_cnt):
h = ab_c.wait_and_advance(peek)
nblk = cute.size(tCrA, mode=[2])
for kb in cutlass.range(nblk, unroll_full=True):
cute.gemm(qk_mma, tStS0, tCrA[(None,None,kb,h.index)], tCrB[(None,None,kb,h.index)], tStS0)
qk_mma.set(tcgen05.Field.ACCUMULATE, True)
h.release(); peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_c.try_wait()
cute.arch.fence_view_async_tmem_store()
s0_handle.commit()
# Wait for softmax to complete
s0_handle = mma_si_prod.acquire_and_advance()
pv_mma.set(tcgen05.Field.ACCUMULATE, True)
tCrV_s = tCrV[(None, None, None, 0)]
nblk_pv = cute.size(tOrP0, mode=[2])
for kb in cutlass.range(nblk_pv, unroll_full=True):
cute.gemm(pv_mma, tOtO0, tOrP0[(None,None,kb)], tCrV_s[(None,None,kb)], tOtO0)
acc_pipe.producer_commit(acc_prod_st)
acc_prod_st.advance()
acc_pipe.producer_tail(acc_prod_st)
# ── SOFTMAX / EPILOGUE WARPS ──
if warp_idx < self.mma_warp_id:
tmem.allocate(self.num_tmem_alloc_cols)
tmem.wait_for_alloc()
tmem_ptr = tmem.retrieve_ptr(self.qk_acc_dtype)
sfw_idx = tidx % (32 * len(self.epilogue_warp_id))
# ── 1. TMEM LOAD pipeline (C-fragment layout, FP32) ──
tmem_load_atom = cute.make_copy_atom(
tcgen05.copy.Ld32x32bOp(tcgen05.copy.Repetition(32)), self.qk_acc_dtype)
tiled_tmem_load = tcgen05.make_tmem_copy(tmem_load_atom, tStS0)
thr_load = tiled_tmem_load.get_slice(sfw_idx)
tTMEM_LOADtS = thr_load.partition_S(tStS0)
cS = cute.make_identity_tensor((self.qk_mma_tiler[0], self.qk_mma_tiler[1]))
tScS = qk_thr.partition_C(cS)
tTMEM_LOADcS = thr_load.partition_D(tScS)
# ── 2. TMEM STORE pipeline (C-fragment composition, FP32 St32x32bOp) ──
# FMHA: compose the coordinate tensor with (128, tilePlikeFP32) for the store
tScS_P_layout = cute.composition(tScS.layout, cute.make_layout((128, tilePlikeFP32)))
tScS_P = cute.make_tensor(tScS.iterator, tScS_P_layout)
tmem_store_atom = cute.make_copy_atom(
tcgen05.copy.St32x32bOp(tcgen05.copy.Repetition(32)), self.qk_acc_dtype)
tiled_tmem_store = tcgen05.make_tmem_copy(tmem_store_atom, tStS_P)
thr_store = tiled_tmem_store.get_slice(sfw_idx)
tTMEM_STOREtS_x4 = thr_store.partition_D(tStS_P)
tTMEM_STOREcS = thr_store.partition_S(tScS_P)
# Wait for QK scores
si_handle = mma_si_cons.wait_and_advance()
# ── 3. LOAD scores from TMEM ──
tTMEM_LOADrS = cute.make_rmem_tensor(tTMEM_LOADcS.shape, self.qk_acc_dtype)
cute.copy(tiled_tmem_load, tTMEM_LOADtS, tTMEM_LOADrS)
# ── 4. Identity softmax: convert FP32 → BF16 with packing ──
# FMHA pattern: FP32 backing tensor + BF16 recast view
# tTMEM_STORErS_x4: FP32 backing (store partition shape, 64 FP32 words)
# tTMEM_STORErS_x4_e: BF16 recast view (load partition shape, 128 BF16 elements)
tTMEM_STORErS_x4 = cute.make_rmem_tensor(tTMEM_STOREcS.shape, self.qk_acc_dtype)
tTMEM_STORErS_x4_e = cute.make_tensor(
cute.recast_ptr(tTMEM_STORErS_x4.iterator, dtype=self.q_dtype),
tTMEM_LOADrS.layout,
)
# Convert all 128 FP32 values → 128 BF16, packed into 64 FP32 backing slots
# The .load()/.store() on the recast view handles the packing automatically
frg_cnt = 4
frg_tile = cute.size(tTMEM_LOADrS) // frg_cnt
tTMEM_LOADrS_frg = cute.logical_divide(tTMEM_LOADrS, cute.make_layout(frg_tile))
tTMEM_STORErS_x4_e_frg = cute.logical_divide(tTMEM_STORErS_x4_e, cute.make_layout(frg_tile))
for j in range(frg_cnt):
for k in cutlass.range(cute.size(tTMEM_LOADrS_frg, mode=[0]), vectorize=True):
# Identity: keep the value, just convert F32→BF16
# (In real softmax, this is where exp(scores - row_max) happens)
tTMEM_LOADrS_frg[k, j] = tTMEM_LOADrS_frg[k, j] # identity (no-op, just for clarity)
s_vec = tTMEM_LOADrS_frg[None, j].load()
tTMEM_STORErS_x4_e_frg[None, j].store(s_vec.to(self.q_dtype))
# ── 5. STORE packed BF16 to TMEM via C-fragment composition ──
cute.copy(tiled_tmem_store, tTMEM_STORErS_x4, tTMEM_STOREtS_x4)
cute.arch.fence_view_async_tmem_store()
# Release back to MMA warp
si_handle.release()
# ── Epilogue ──
tCtO_base = cute.make_tensor(tmem_ptr + self.tmem_o0_offset, tCtO_fake.layout)
acc_cons_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Consumer, self.num_acc_stage)
c_grp = pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id))
c_pipe = pipeline.PipelineTmaStore.create(num_stages=self.num_c_stage, producer_group=c_grp)
acc_cons_st = utils.gemm.sm100.epilogue_tma_store(
self, tidx, warp_idx, tma_c, tCtO_base, sC, tCgC,
epi_tile, 0, const_expr(lambda x: x), (0,0,0), acc_cons_st, acc_pipe, c_pipe)
c_pipe.producer_tail()
tmem.relinquish_alloc_permit()
tmem.free(tmem_ptr)
def test():
torch.manual_seed(42)
m, n, k = 128, 128, 128
q = torch.randn(m, k, 1, dtype=torch.bfloat16, device='cuda')
kv = torch.randn(n, k, 1, dtype=torch.bfloat16, device='cuda')
c = torch.zeros(m, n, 1, dtype=torch.bfloat16, device='cuda')
qf = q[:,:,0].float(); kvf = kv[:,:,0].float()
# Identity softmax = just convert F32→BF16, so P = BF16(S) ≈ Q@K^T
# O = P @ V = (Q @ K^T) @ V (same as Q @ K^T @ K, since V=K in this test)
ref = qf @ kvf.T @ kvf
import cutlass.torch as ct
mQ = ct.from_dlpack(q).mark_layout_dynamic(leading_dim=ct.get_leading_dim(q))
mK = ct.from_dlpack(kv).mark_layout_dynamic(leading_dim=ct.get_leading_dim(kv))
mC = ct.from_dlpack(c).mark_layout_dynamic(leading_dim=ct.get_leading_dim(c))
stream = cuda.CUstream(torch.cuda.current_stream().cuda_stream)
kernel = StageBIdentitySoftmax(mma_tiler_mn=(128, 128), use_2cta_instrs=False, use_tma_store=True)
print('Compiling...', flush=True)
compiled = cute.compile(kernel, mQ, mK, mC, stream)
print('Running...', flush=True)
compiled(mQ, mK, mC, stream)
torch.cuda.synchronize()
out = c[:,:,0].float()
cos = torch.nn.functional.cosine_similarity(out.flatten().unsqueeze(0), ref.flatten().unsqueeze(0)).item()
max_err = (out - ref).abs().max().item()
print('Stage B v13: FMHA C-fragment packing pattern (identity softmax)')
print(' Cosine: {:.6f}, Max error: {:.6f}'.format(cos, max_err))
print(' {}'.format('PASS' if cos >= 0.99 else 'FAIL'))
if __name__ == '__main__':
test()

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tests/test_stage_b_v14.py Normal file
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"""
Stage B v14: Two MMAs + Identity Softmax using backward FMHA's A-fragment store pattern.
The backward FMHA writes P to TMEM using the A-fragment layout directly:
1. Load S from TMEM via C-fragment layout (FP32)
2. Quantize FP32 -> BF16 (make_rmem_tensor with BF16, load/store)
3. Reshape quantized to match store coordinate shape
4. Store via St32x32bOp(BF16) to A-fragment TMEM layout
5. PV MMA reads from the same A-fragment addresses
"""
import torch, cutlass, cutlass.cute as cute, cutlass.utils as utils, cutlass.pipeline as pipeline
from cutlass.cute.nvgpu import cpasync, tcgen05
from cutlass import Float32, BFloat16, Int32, Boolean, const_expr
from cutlass.utils import LayoutEnum
from cutlass.utils.tmem_allocator import find_tmem_tensor_col_offset
import cuda.bindings.driver as cuda
class StageBIdentitySoftmax:
def __init__(self, mma_tiler_mn, use_2cta_instrs=False, use_tma_store=True):
self.acc_dtype = Float32; self.qk_acc_dtype = Float32
self.q_dtype = BFloat16; self.o_dtype = BFloat16
self.use_2cta_instrs = use_2cta_instrs; self.use_tma_store = use_tma_store
self.mma_tiler_mn = mma_tiler_mn; self.mma_tiler = (*mma_tiler_mn, 1)
self.cluster_shape_mn = (1, 1)
self.cta_group = tcgen05.CtaGroup.TWO if use_2cta_instrs else tcgen05.CtaGroup.ONE
self.epilogue_warp_id = (0, 1, 2, 3)
self.mma_warp_id = 4; self.tma_warp_id = 5
self.threads_per_cta = 192
self.epilog_sync_bar_id = 1; self.tmem_alloc_sync_bar_id = 2; self.tmem_dealloc_sync_bar_id = 3
self.num_c_stage = 2
def _setup(self, qk_mma, pv_mma):
qk_inst_k = cute.size(qk_mma.shape_mnk, mode=[2])
self.qk_mma_tiler = (*self.mma_tiler_mn, qk_inst_k * 4)
self.pv_mma_tiler = (self.qk_mma_tiler[0], self.qk_mma_tiler[2], self.qk_mma_tiler[1])
self.mma_tiler = self.qk_mma_tiler
print(f"[StageB] qk_mma_tiler = {self.qk_mma_tiler}")
print(f"[StageB] pv_mma_tiler = {self.pv_mma_tiler}")
self.cta_tile_shape_mnk = (
self.qk_mma_tiler[0] // cute.size(qk_mma.thr_id.shape),
self.qk_mma_tiler[1],
self.qk_mma_tiler[2],
)
self.cluster_layout_vmnk = cute.tiled_divide(cute.make_layout((1,1,1)), (qk_mma.thr_id.shape,))
self.epi_tile = utils.sm100.compute_epilogue_tile_shape(
self.cta_tile_shape_mnk, self.use_2cta_instrs, self.c_layout, self.o_dtype)
self.num_ab_stage = 1; self.num_acc_stage = 1
self.a_smem_s = utils.sm100.make_smem_layout_a(qk_mma, self.mma_tiler, self.a_dtype, 1)
self.b_smem_s = utils.sm100.make_smem_layout_b(qk_mma, self.mma_tiler, self.b_dtype, 1)
self.v_smem_s = utils.sm100.make_smem_layout_b(pv_mma, self.pv_mma_tiler, self.b_dtype, 1)
self.p_tmem_s = utils.sm100.make_smem_layout_a(pv_mma, self.pv_mma_tiler, self.q_dtype, 1)
self.c_smem_s = utils.sm100.make_smem_layout_epi(self.o_dtype, self.c_layout, self.epi_tile, 2)
qk_thr = qk_mma.get_slice(0)
qk_acc_shape = qk_thr.partition_shape_C(self.mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
s_cols = find_tmem_tensor_col_offset(tStS)
pv_thr = pv_mma.get_slice(0)
pv_acc_shape = pv_thr.partition_shape_C(self.pv_mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
o_cols = find_tmem_tensor_col_offset(tOtO)
self.tmem_s0_offset = 0
self.tmem_p0_offset = 32
self.tmem_o0_offset = s_cols
self.tmem_alloc_cols = s_cols + o_cols
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, self.num_acc_stage))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, self.num_acc_stage))
self.num_tmem_alloc_cols = utils.get_num_tmem_alloc_cols([tCtS_fake, tCtO_fake], arch="sm_100")
a_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
b_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
self.num_tma_load_bytes = (
cute.size_in_bytes(self.a_dtype, a_smem) + cute.size_in_bytes(self.b_dtype, b_smem)
) * cute.size(qk_mma.thr_id.shape)
@cute.jit
def __call__(self, a: cute.Tensor, b: cute.Tensor, c: cute.Tensor, stream: cuda.CUstream):
self.a_dtype = a.element_type; self.b_dtype = b.element_type; self.c_dtype = c.element_type
self.a_major = LayoutEnum.from_tensor(a).mma_major_mode()
self.b_major = LayoutEnum.from_tensor(b).mma_major_mode()
self.c_layout = LayoutEnum.from_tensor(c)
qk_mma = utils.sm100.make_trivial_tiled_mma(
self.a_dtype, self.b_dtype, self.a_major, self.b_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.SMEM)
pv_mma = utils.sm100.make_trivial_tiled_mma(
self.a_dtype, self.b_dtype, cute.nvgpu.OperandMajorMode.K, self.b_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.TMEM)
self._setup(qk_mma, pv_mma)
a_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
b_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
tma_a, tma_ta = cute.nvgpu.make_tiled_tma_atom_A(
utils.sm100.cluster_shape_to_tma_atom_A(self.cluster_shape_mn, qk_mma.thr_id),
a, a_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
tma_b, tma_tb = cute.nvgpu.make_tiled_tma_atom_B(
utils.sm100.cluster_shape_to_tma_atom_B(self.cluster_shape_mn, qk_mma.thr_id),
b, b_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
epi_smem = cute.select(self.c_smem_s, mode=[0, 1])
tma_c, tma_tc = cpasync.make_tiled_tma_atom(cpasync.CopyBulkTensorTileS2GOp(), c, epi_smem, self.epi_tile)
self._kernel(qk_mma, pv_mma, tma_a, tma_ta, tma_b, tma_tb, tma_c, tma_tc,
self.cluster_layout_vmnk, self.a_smem_s, self.b_smem_s, self.v_smem_s, self.p_tmem_s, self.c_smem_s, self.epi_tile
).launch(grid=(1,1,1), block=[self.threads_per_cta,1,1], stream=stream)
@cute.kernel
def _kernel(self, qk_mma, pv_mma, tma_a, mA, tma_b, mB, tma_c, mC, cl_vmnk,
a_smem_s, b_smem_s, v_smem_s, p_tmem_s, c_smem_s, epi_tile):
warp_idx = cute.arch.make_warp_uniform(cute.arch.warp_idx())
tidx, _, _ = cute.arch.thread_idx()
use_2cta = cute.size(qk_mma.thr_id.shape) == 2
if warp_idx == self.tma_warp_id:
cpasync.prefetch_descriptor(tma_a); cpasync.prefetch_descriptor(tma_b); cpasync.prefetch_descriptor(tma_c)
@cute.struct
class SS:
ab_bar: cute.struct.MemRange[cutlass.Int64, self.num_ab_stage * 2]
mma_si_bar: cute.struct.MemRange[cutlass.Int64, 2]
acc_bar: cute.struct.MemRange[cutlass.Int64, self.num_acc_stage * 2]
tmem_dealloc: cutlass.Int64
holding: cutlass.Int32
smem = utils.SmemAllocator(); st = smem.allocate(SS)
ab_p, ab_c = pipeline.PipelineTmaUmma.create(
barrier_storage=st.ab_bar.data_ptr(), num_stages=self.num_ab_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 1),
tx_count=self.num_tma_load_bytes, cta_layout_vmnk=cl_vmnk, defer_sync=True
).make_participants()
mma_si_prod, mma_si_cons = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.mma_si_bar.data_ptr(), num_stages=1,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id)),
cta_layout_vmnk=cl_vmnk, defer_sync=True
).make_participants()
acc_pipe = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.acc_bar.data_ptr(), num_stages=self.num_acc_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(
pipeline.Agent.Thread, len(self.epilogue_warp_id) * (2 if use_2cta else 1)),
cta_layout_vmnk=cl_vmnk, defer_sync=True)
tmem_bar = pipeline.NamedBarrier(barrier_id=self.tmem_alloc_sync_bar_id,
num_threads=32 * len((self.mma_warp_id, *self.epilogue_warp_id)))
tmem = utils.TmemAllocator(st.holding.ptr, barrier_for_retrieve=tmem_bar,
allocator_warp_id=self.epilogue_warp_id[0], is_two_cta=use_2cta,
two_cta_tmem_dealloc_mbar_ptr=st.tmem_dealloc.ptr)
pipeline.pipeline_init_arrive(cluster_shape_mn=cl_vmnk, is_relaxed=True)
sA = smem.allocate_tensor(element_type=self.a_dtype, layout=a_smem_s.outer, byte_alignment=128, swizzle=a_smem_s.inner)
sB = smem.allocate_tensor(element_type=self.b_dtype, layout=b_smem_s.outer, byte_alignment=128, swizzle=b_smem_s.inner)
sV_ptr = cute.recast_ptr(sB.iterator, v_smem_s.inner)
sV = cute.make_tensor(sV_ptr, v_smem_s.outer)
sC = smem.allocate_tensor(element_type=self.o_dtype, layout=c_smem_s.outer, byte_alignment=128, swizzle=c_smem_s.inner)
gA = cute.local_tile(mA, cute.slice_(self.mma_tiler, (None,0,None)), (None,None,None))
gB = cute.local_tile(mB, cute.slice_(self.mma_tiler, (0,None,None)), (None,None,None))
gC = cute.local_tile(mC, cute.slice_(self.mma_tiler, (None,None,0)), (None,None,None))
k_cnt = cute.size(gA, mode=[3])
qk_thr = qk_mma.get_slice(0)
tCgA = qk_thr.partition_A(gA); tCgB = qk_thr.partition_B(gB); tCgC = qk_thr.partition_C(gC)
a_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,0,None,0)).shape)
tAsA, tAgA = cpasync.tma_partition(tma_a, 0, a_lay, cute.group_modes(sA,0,3), cute.group_modes(tCgA,0,3))
b_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,None,0,0)).shape)
tBsB, tBgB = cpasync.tma_partition(tma_b, 0, b_lay, cute.group_modes(sB,0,3), cute.group_modes(tCgB,0,3))
tAgA = tAgA[(None,0,None,0)]; tBgB = tBgB[(None,0,None,0)]
tCrA = qk_mma.make_fragment_A(sA); tCrB = qk_mma.make_fragment_B(sB)
tCrV = pv_mma.make_fragment_B(sV)
# TMEM tensors
qk_acc_shape = qk_thr.partition_shape_C(self.mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
tStS0 = cute.make_tensor(tStS.iterator + self.tmem_s0_offset, tStS.layout)
pv_thr = pv_mma.get_slice(0)
pv_acc_shape = pv_thr.partition_shape_C(self.pv_mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
tOtO0 = cute.make_tensor(tOtO.iterator + self.tmem_o0_offset, tOtO.layout)
# P A-fragment (backward FMHA pattern)
tP = cute.make_tensor(tStS.iterator, p_tmem_s.outer)
tdVrP_base = pv_thr.make_fragment_A(tP)
tdVrP = tdVrP_base[(None, None, None, 0)]
tdVrP_iter = cute.recast_ptr(tStS.iterator, dtype=self.q_dtype)
tdVrP = cute.make_tensor(tdVrP_iter, tdVrP.layout)
tdVrP0 = cute.make_tensor(
tdVrP.iterator + self.qk_acc_dtype.width // self.q_dtype.width * self.tmem_p0_offset,
tdVrP.layout)
print(f'[DIAG] tStS.layout: {tStS.layout}')
print(f'[DIAG] tdVrP.layout: {tdVrP.layout}')
print(f'[DIAG] tdVrP0.layout: {tdVrP0.layout}')
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, self.num_acc_stage))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, self.num_acc_stage))
pipeline.pipeline_init_wait(cluster_shape_mn=cl_vmnk)
# TMA WARP
if warp_idx == self.tma_warp_id:
ab_p.reset(); peek = ab_p.try_acquire()
for kt in cutlass.range(k_cnt, unroll=1):
h = ab_p.acquire_and_advance(peek)
cute.copy(tma_a, tAgA[(None,h.count)], tAsA[(None,h.index)], tma_bar_ptr=h.barrier)
cute.copy(tma_b, tBgB[(None,h.count)], tBsB[(None,h.index)], tma_bar_ptr=h.barrier)
peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_p.try_acquire()
ab_p.tail()
# MMA WARP
if warp_idx == self.mma_warp_id:
tmem.wait_for_alloc()
ab_c.reset(); peek = ab_c.try_wait()
s0_handle = mma_si_prod.acquire_and_advance()
acc_prod_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Producer, self.num_acc_stage)
acc_pipe.producer_acquire(acc_prod_st)
qk_mma.set(tcgen05.Field.ACCUMULATE, False)
for kt in range(k_cnt):
h = ab_c.wait_and_advance(peek)
nblk = cute.size(tCrA, mode=[2])
for kb in cutlass.range(nblk, unroll_full=True):
cute.gemm(qk_mma, tStS0, tCrA[(None,None,kb,h.index)], tCrB[(None,None,kb,h.index)], tStS0)
qk_mma.set(tcgen05.Field.ACCUMULATE, True)
h.release(); peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_c.try_wait()
cute.arch.fence_view_async_tmem_store()
s0_handle.commit()
s0_handle = mma_si_prod.acquire_and_advance()
pv_mma.set(tcgen05.Field.ACCUMULATE, True)
tCrV_s = tCrV[(None, None, None, 0)]
nblk_pv = cute.size(tdVrP0, mode=[2])
for kb in cutlass.range(nblk_pv, unroll_full=True):
cute.gemm(pv_mma, tOtO0, tdVrP0[(None,None,kb)], tCrV_s[(None,None,kb)], tOtO0)
acc_pipe.producer_commit(acc_prod_st)
acc_prod_st.advance()
acc_pipe.producer_tail(acc_prod_st)
# SOFTMAX / EPILOGUE WARPS
if warp_idx < self.mma_warp_id:
tmem.allocate(self.num_tmem_alloc_cols)
tmem.wait_for_alloc()
tmem_ptr = tmem.retrieve_ptr(self.qk_acc_dtype)
sfw_idx = tidx % (32 * len(self.epilogue_warp_id))
# 1. TMEM LOAD pipeline (C-fragment, FP32)
tmem_load_atom = cute.make_copy_atom(
tcgen05.copy.Ld32x32bOp(tcgen05.copy.Repetition(32)), self.qk_acc_dtype)
tiled_tmem_load = tcgen05.make_tmem_copy(tmem_load_atom, tStS0)
thr_load = tiled_tmem_load.get_slice(sfw_idx)
tTMEM_LOADtS = thr_load.partition_S(tStS0)
cS = cute.make_identity_tensor((self.qk_mma_tiler[0], self.qk_mma_tiler[1]))
tScS = qk_thr.partition_C(cS)
tTMEM_LOADcS = thr_load.partition_D(tScS)
# 2. TMEM STORE pipeline (A-fragment, BF16 St32x32bOp)
tmem_store_atom = cute.make_copy_atom(
tcgen05.copy.St32x32bOp(tcgen05.copy.Repetition(8)), self.q_dtype)
tiled_tmem_store = tcgen05.make_tmem_copy(tmem_store_atom, tdVrP0)
thr_store = tiled_tmem_store.get_slice(sfw_idx)
tRT_tP = thr_store.partition_D(tdVrP0)
cS_store = cute.make_identity_tensor((self.qk_mma_tiler[0], self.qk_mma_tiler[1]))
tdVcS = pv_thr.partition_A(cS_store)
tRT_cS = thr_store.partition_S(tdVcS)
# Wait for QK scores
si_handle = mma_si_cons.wait_and_advance()
# 3. LOAD scores from TMEM
tTR_rST = cute.make_rmem_tensor(tTMEM_LOADcS.shape, self.qk_acc_dtype)
cute.copy(tiled_tmem_load, tTMEM_LOADtS, tTR_rST)
# 4. Quantize FP32 -> BF16 (backward FMHA pattern)
tRT_rST_bf16 = cute.make_rmem_tensor(tTR_rST.shape, self.q_dtype)
frg_cnt = 4
frg_tile = cute.size(tTR_rST) // frg_cnt
tTR_rST_frg = cute.logical_divide(tTR_rST, cute.make_layout(frg_tile))
tRT_rST_bf16_frg = cute.make_tensor(tRT_rST_bf16.iterator, tTR_rST_frg.layout)
for j in range(frg_cnt):
frg_vec = tTR_rST_frg[None, j].load()
tRT_rST_bf16_frg[None, j].store(frg_vec.to(self.q_dtype))
# 5. Reshape to match store coordinate shape
tRT_rST_reshaped = cute.make_tensor(
tRT_rST_bf16.iterator, cute.make_layout(tRT_cS.shape))
# 6. STORE to A-fragment TMEM
cute.copy(tiled_tmem_store, tRT_rST_reshaped, tRT_tP)
cute.arch.fence_view_async_tmem_store()
si_handle.release()
# Epilogue
tCtO_base = cute.make_tensor(tmem_ptr + self.tmem_o0_offset, tCtO_fake.layout)
acc_cons_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Consumer, self.num_acc_stage)
c_grp = pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id))
c_pipe = pipeline.PipelineTmaStore.create(num_stages=self.num_c_stage, producer_group=c_grp)
acc_cons_st = utils.gemm.sm100.epilogue_tma_store(
self, tidx, warp_idx, tma_c, tCtO_base, sC, tCgC,
epi_tile, 0, const_expr(lambda x: x), (0,0,0), acc_cons_st, acc_pipe, c_pipe)
c_pipe.producer_tail()
tmem.relinquish_alloc_permit()
tmem.free(tmem_ptr)
def test():
torch.manual_seed(42)
m, n, k = 128, 128, 128
q = torch.randn(m, k, 1, dtype=torch.bfloat16, device='cuda')
kv = torch.randn(n, k, 1, dtype=torch.bfloat16, device='cuda')
c = torch.zeros(m, n, 1, dtype=torch.bfloat16, device='cuda')
qf = q[:,:,0].float(); kvf = kv[:,:,0].float()
ref = qf @ kvf.T @ kvf
import cutlass.torch as ct
mQ = ct.from_dlpack(q).mark_layout_dynamic(leading_dim=ct.get_leading_dim(q))
mK = ct.from_dlpack(kv).mark_layout_dynamic(leading_dim=ct.get_leading_dim(kv))
mC = ct.from_dlpack(c).mark_layout_dynamic(leading_dim=ct.get_leading_dim(c))
stream = cuda.CUstream(torch.cuda.current_stream().cuda_stream)
kernel = StageBIdentitySoftmax(mma_tiler_mn=(128, 128), use_2cta_instrs=False, use_tma_store=True)
print('Compiling...', flush=True)
compiled = cute.compile(kernel, mQ, mK, mC, stream)
print('Running...', flush=True)
compiled(mQ, mK, mC, stream)
torch.cuda.synchronize()
out = c[:,:,0].float()
cos = torch.nn.functional.cosine_similarity(out.flatten().unsqueeze(0), ref.flatten().unsqueeze(0)).item()
max_err = (out - ref).abs().max().item()
print('Stage B v14: backward FMHA A-fragment store pattern (identity softmax)')
print(' Cosine: {:.6f}, Max error: {:.6f}'.format(cos, max_err))
print(' {}'.format('PASS' if cos >= 0.99 else 'FAIL'))
if __name__ == '__main__':
test()

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tests/test_stage_b_v16.py Normal file
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"""
Stage B v7: Two MMAs + Identity Softmax with COMPUTED TMEM offsets.
Key fixes over v6:
- TMEM offsets computed via find_tmem_tensor_col_offset (same API as get_num_tmem_alloc_cols)
- P tensor constructed from p_tmem_s.outer (matching fmha.py pattern exactly)
- tilePlikeFP32 computed from qk_mma_tiler and dtype widths
- tmem_alloc_cols from get_num_tmem_alloc_cols with all fragments
- JIT-time diagnostic prints of all TMEM sizes
Architecture (matches fmha.py exactly):
MMA1: Q @ K^T → tmem_scores (a_source=SMEM, accumulate=False)
Identity softmax: tcgen05.ld C-layout → F32→BF16 → tcgen05.st A-layout
MMA2: P @ V → tmem_output (a_source=TMEM, accumulate=True)
"""
import torch, cutlass, cutlass.cute as cute, cutlass.utils as utils, cutlass.pipeline as pipeline
from cutlass.cute.nvgpu import cpasync, tcgen05
from cutlass import Float32, BFloat16, Int32, Boolean, const_expr
from cutlass.utils import LayoutEnum
from cutlass.utils.tmem_allocator import find_tmem_tensor_col_offset
import cuda.bindings.driver as cuda
class StageBIdentitySoftmax:
def __init__(self, mma_tiler_mn, use_2cta_instrs=False, use_tma_store=True):
self.acc_dtype = Float32; self.qk_acc_dtype = Float32
self.q_dtype = BFloat16; self.o_dtype = BFloat16
self.use_2cta_instrs = use_2cta_instrs; self.use_tma_store = use_tma_store
self.mma_tiler_mn = mma_tiler_mn; self.mma_tiler = (*mma_tiler_mn, 1)
self.cluster_shape_mn = (1, 1)
self.cta_group = tcgen05.CtaGroup.TWO if use_2cta_instrs else tcgen05.CtaGroup.ONE
self.epilogue_warp_id = (0, 1, 2, 3)
self.mma_warp_id = 4; self.tma_warp_id = 5
self.threads_per_cta = 192
self.epilog_sync_bar_id = 1; self.tmem_alloc_sync_bar_id = 2; self.tmem_dealloc_sync_bar_id = 3
self.num_c_stage = 2
def _setup(self, qk_mma, pv_mma):
qk_inst_k = cute.size(qk_mma.shape_mnk, mode=[2])
self.qk_mma_tiler = (*self.mma_tiler_mn, qk_inst_k * 4)
pv_inst_k = cute.size(pv_mma.shape_mnk, mode=[2])
self.pv_mma_tiler = (self.qk_mma_tiler[0], self.qk_mma_tiler[2], self.qk_mma_tiler[1])
self.mma_tiler = self.qk_mma_tiler
print(f"[StageB] qk_mma.shape_mnk = {qk_mma.shape_mnk}")
print(f"[StageB] pv_mma.shape_mnk = {pv_mma.shape_mnk}")
print(f"[StageB] qk_mma_tiler = {self.qk_mma_tiler}")
print(f"[StageB] pv_mma_tiler = {self.pv_mma_tiler}")
print(f"[StageB] qk_inst_k = {qk_inst_k}, pv_inst_k = {pv_inst_k}")
self.cta_tile_shape_mnk = (
self.qk_mma_tiler[0] // cute.size(qk_mma.thr_id.shape),
self.qk_mma_tiler[1],
self.qk_mma_tiler[2],
)
self.cluster_layout_vmnk = cute.tiled_divide(cute.make_layout((1,1,1)), (qk_mma.thr_id.shape,))
self.epi_tile = utils.sm100.compute_epilogue_tile_shape(
self.cta_tile_shape_mnk, self.use_2cta_instrs, self.c_layout, self.o_dtype)
self.num_ab_stage = 1; self.num_acc_stage = 1
self.a_smem_s = utils.sm100.make_smem_layout_a(qk_mma, self.mma_tiler, self.a_dtype, 1)
self.b_smem_s = utils.sm100.make_smem_layout_b(qk_mma, self.mma_tiler, self.b_dtype, 1)
self.v_smem_s = utils.sm100.make_smem_layout_b(pv_mma, self.pv_mma_tiler, self.b_dtype, 1)
self.p_tmem_s = utils.sm100.make_smem_layout_a(pv_mma, self.pv_mma_tiler, self.q_dtype, 1)
self.c_smem_s = utils.sm100.make_smem_layout_epi(self.o_dtype, self.c_layout, self.epi_tile, 2)
# ── COMPUTE TMEM OFFSETS USING find_tmem_tensor_col_offset ──
qk_thr = qk_mma.get_slice(0)
qk_acc_shape = qk_thr.partition_shape_C(self.mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
s_cols = find_tmem_tensor_col_offset(tStS)
pv_thr = pv_mma.get_slice(0)
pv_acc_shape = pv_thr.partition_shape_C(self.mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
o_cols = find_tmem_tensor_col_offset(tOtO)
# tilePlikeFP32 for the store-side composition
self.tilePlikeFP32 = self.qk_mma_tiler[1] * self.q_dtype.width // 32
# ── TMEM LAYOUT (matching fmha.py) ──
# P OVERLAPS S — after softmax, P (A-layout) is written on top of scores (C-layout)
# in the same TMEM region. The A-layout view starts partway through the S region.
# fmha.py: S0=0, P0=32, O0=256 (with S1=128, P1=160 double-buffered)
# The P offset of 32 means the A-layout starts at column 32 within the S region.
# This is because the C-layout and A-layout partition TMEM differently per-thread;
# the first 32 C-layout columns are "dead space" in the A-layout mapping.
#
self.tmem_s0_offset = 0
self.tmem_p0_offset = 32 # Original
self.tmem_o0_offset = s_cols # 128
self.tmem_alloc_cols = 512 # FMHA: allocate max TMEM
# Also compute via get_num_tmem_alloc_cols for the full allocation
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, 1))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, 1))
self.num_tmem_alloc_cols = utils.get_num_tmem_alloc_cols([tCtS_fake, tCtO_fake], arch="sm_100")
print(f"[StageB] s_cols (QK accumulator) = {s_cols}")
print(f"[StageB] o_cols (PV accumulator) = {o_cols}")
print(f"[StageB] tilePlikeFP32 = {self.tilePlikeFP32}")
print(f"[StageB] tmem_s0_offset = {self.tmem_s0_offset}")
print(f"[StageB] tmem_p0_offset = {self.tmem_p0_offset}")
print(f"[StageB] tmem_o0_offset = {self.tmem_o0_offset}")
print(f"[StageB] tmem_alloc_cols (computed) = {self.tmem_alloc_cols}")
print(f"[StageB] num_tmem_alloc_cols (via utils) = {self.num_tmem_alloc_cols}")
a_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
b_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
self.num_tma_load_bytes = (
cute.size_in_bytes(self.a_dtype, a_smem) + cute.size_in_bytes(self.b_dtype, b_smem)
) * cute.size(qk_mma.thr_id.shape)
@cute.jit
def __call__(self, a: cute.Tensor, b: cute.Tensor, c: cute.Tensor, stream: cuda.CUstream):
self.a_dtype = a.element_type; self.b_dtype = b.element_type; self.c_dtype = c.element_type
self.a_major = LayoutEnum.from_tensor(a).mma_major_mode()
self.b_major = LayoutEnum.from_tensor(b).mma_major_mode()
self.c_layout = LayoutEnum.from_tensor(c)
qk_mma = utils.sm100.make_trivial_tiled_mma(
self.a_dtype, self.b_dtype, self.a_major, self.b_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.SMEM)
pv_mma = utils.sm100.make_trivial_tiled_mma(
self.a_dtype, self.b_dtype, cute.nvgpu.OperandMajorMode.K, self.b_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.TMEM)
# Introspect PV MMA atom
print(f"[ATOM] PV MMA type: {type(pv_mma)}")
print(f"[ATOM] PV MMA op: {pv_mma.op if hasattr(pv_mma, "op") else "no op"}")
print(f"[ATOM] PV MMA trait: {pv_mma._trait if hasattr(pv_mma, "_trait") else "no trait"}")
print(f"[ATOM] PV MMA shape_mnk: {pv_mma.shape_mnk}")
print(f"[ATOM] QK MMA shape_mnk: {qk_mma.shape_mnk}")
# Check a_src
print(f"[ATOM] PV MMA op.a_src: {pv_mma.op.a_src}")
print(f"[ATOM] QK MMA op.a_src: {qk_mma.op.a_src}")
print(f"[ATOM] PV MMA op: {pv_mma.op}")
self._setup(qk_mma, pv_mma)
a_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
b_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
tma_a, tma_ta = cute.nvgpu.make_tiled_tma_atom_A(
utils.sm100.cluster_shape_to_tma_atom_A(self.cluster_shape_mn, qk_mma.thr_id),
a, a_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
tma_b, tma_tb = cute.nvgpu.make_tiled_tma_atom_B(
utils.sm100.cluster_shape_to_tma_atom_B(self.cluster_shape_mn, qk_mma.thr_id),
b, b_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
epi_smem = cute.select(self.c_smem_s, mode=[0, 1])
tma_c, tma_tc = cpasync.make_tiled_tma_atom(cpasync.CopyBulkTensorTileS2GOp(), c, epi_smem, self.epi_tile)
self._kernel(qk_mma, pv_mma, tma_a, tma_ta, tma_b, tma_tb, tma_c, tma_tc,
self.cluster_layout_vmnk, self.a_smem_s, self.b_smem_s, self.v_smem_s, self.p_tmem_s, self.c_smem_s, self.epi_tile
).launch(grid=(1,1,1), block=[self.threads_per_cta,1,1], stream=stream)
@cute.kernel
def _kernel(self, qk_mma, pv_mma, tma_a, mA, tma_b, mB, tma_c, mC, cl_vmnk,
a_smem_s, b_smem_s, v_smem_s, p_tmem_s, c_smem_s, epi_tile):
warp_idx = cute.arch.make_warp_uniform(cute.arch.warp_idx())
tidx, _, _ = cute.arch.thread_idx()
use_2cta = cute.size(qk_mma.thr_id.shape) == 2
if warp_idx == self.tma_warp_id:
cpasync.prefetch_descriptor(tma_a); cpasync.prefetch_descriptor(tma_b); cpasync.prefetch_descriptor(tma_c)
@cute.struct
class SS:
ab_bar: cute.struct.MemRange[cutlass.Int64, self.num_ab_stage * 2]
mma_si_bar: cute.struct.MemRange[cutlass.Int64, 2]
acc_bar: cute.struct.MemRange[cutlass.Int64, self.num_acc_stage * 2]
tmem_dealloc: cutlass.Int64
holding: cutlass.Int32
smem = utils.SmemAllocator(); st = smem.allocate(SS)
ab_p, ab_c = pipeline.PipelineTmaUmma.create(
barrier_storage=st.ab_bar.data_ptr(), num_stages=self.num_ab_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 1),
tx_count=self.num_tma_load_bytes, cta_layout_vmnk=cl_vmnk, defer_sync=True
).make_participants()
mma_si_prod, mma_si_cons = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.mma_si_bar.data_ptr(), num_stages=1,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id)),
cta_layout_vmnk=cl_vmnk, defer_sync=True
).make_participants()
acc_pipe = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.acc_bar.data_ptr(), num_stages=self.num_acc_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(
pipeline.Agent.Thread, len(self.epilogue_warp_id) * (2 if use_2cta else 1)),
cta_layout_vmnk=cl_vmnk, defer_sync=True)
tmem_bar = pipeline.NamedBarrier(barrier_id=self.tmem_alloc_sync_bar_id,
num_threads=32 * len((self.mma_warp_id, *self.epilogue_warp_id)))
tmem = utils.TmemAllocator(st.holding.ptr, barrier_for_retrieve=tmem_bar,
allocator_warp_id=self.epilogue_warp_id[0], is_two_cta=use_2cta,
two_cta_tmem_dealloc_mbar_ptr=st.tmem_dealloc.ptr)
pipeline.pipeline_init_arrive(cluster_shape_mn=cl_vmnk, is_relaxed=True)
sA = smem.allocate_tensor(element_type=self.a_dtype, layout=a_smem_s.outer, byte_alignment=128, swizzle=a_smem_s.inner)
sB = smem.allocate_tensor(element_type=self.b_dtype, layout=b_smem_s.outer, byte_alignment=128, swizzle=b_smem_s.inner)
# V shares the same SMEM as B (same data, different layout for PV MMA)
sV_ptr = cute.recast_ptr(sB.iterator, v_smem_s.inner)
sV = cute.make_tensor(sV_ptr, v_smem_s.outer)
sC = smem.allocate_tensor(element_type=self.o_dtype, layout=c_smem_s.outer, byte_alignment=128, swizzle=c_smem_s.inner)
gA = cute.local_tile(mA, cute.slice_(self.mma_tiler, (None,0,None)), (None,None,None))
gB = cute.local_tile(mB, cute.slice_(self.mma_tiler, (0,None,None)), (None,None,None))
gC = cute.local_tile(mC, cute.slice_(self.mma_tiler, (None,None,0)), (None,None,None))
k_cnt = cute.size(gA, mode=[3])
qk_thr = qk_mma.get_slice(0)
tCgA = qk_thr.partition_A(gA); tCgB = qk_thr.partition_B(gB); tCgC = qk_thr.partition_C(gC)
a_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,0,None,0)).shape)
tAsA, tAgA = cpasync.tma_partition(tma_a, 0, a_lay, cute.group_modes(sA,0,3), cute.group_modes(tCgA,0,3))
b_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,None,0,0)).shape)
tBsB, tBgB = cpasync.tma_partition(tma_b, 0, b_lay, cute.group_modes(sB,0,3), cute.group_modes(tCgB,0,3))
tAgA = tAgA[(None,0,None,0)]; tBgB = tBgB[(None,0,None,0)]
tCrA = qk_mma.make_fragment_A(sA); tCrB = qk_mma.make_fragment_B(sB)
tCrV = pv_mma.make_fragment_B(sV) # V fragment from V SMEM layout
print(f"[DIAG] tCrV.size = {cute.size(tCrV)}")
print(f"[DIAG] tCrA.size = {cute.size(tCrA)}")
print(f"[DIAG] tCrB.size = {cute.size(tCrB)}")
print(f"[DIAG] nblk_qk (tCrA mode 2) = {cute.size(tCrA, mode=[2])}")
# ── TMEM tensors with computed offsets (matching fmha.py pattern) ──
qk_acc_shape = qk_thr.partition_shape_C(self.mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
tStS0 = cute.make_tensor(tStS.iterator + self.tmem_s0_offset, tStS.layout)
pv_thr = pv_mma.get_slice(0)
pv_acc_shape = pv_thr.partition_shape_C(self.mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
tOtO0 = cute.make_tensor(tOtO.iterator + self.tmem_o0_offset, tOtO.layout)
# P fragment: construct from p_tmem_s layout (matching fmha.py exactly)
# fmha.py: tP = cute.make_tensor(tStS.iterator, p_tmem_layout_staged.outer)
# tOrP = pv_thr_mma.make_fragment_A(tP)[None, None, None, 0]
# tdVrP0 = cute.make_tensor(tdVrP.iterator + dtype_width_ratio * tmem_p0_offset, tdVrP.layout)
print(f'[TMEM] p_tmem_s: {p_tmem_s}')
print(f'[TMEM] p_tmem_s.outer: {p_tmem_s.outer}')
print(f'[TMEM] p_tmem_s.inner: {p_tmem_s.inner}')
tP = cute.make_tensor(tStS.iterator, p_tmem_s.outer)
print(f'[DIAG] tStS.layout: {tStS.layout}')
print(f'[DIAG] tStS.size: {cute.size(tStS)}')
print(f'[DIAG] p_tmem_s.outer: {p_tmem_s.outer}')
print(f'[DIAG] p_tmem_s.inner: {p_tmem_s.inner}')
tdVrP_base = pv_thr.make_fragment_A(tP)
tdVrP = tdVrP_base[(None, None, None, 0)]
tdVrP_iter = cute.recast_ptr(tStS.iterator, dtype=self.q_dtype)
tdVrP = cute.make_tensor(tdVrP_iter, tdVrP.layout)
tdVrP0 = cute.make_tensor(
tdVrP.iterator + self.qk_acc_dtype.width // self.q_dtype.width * self.tmem_p0_offset,
tdVrP.layout)
# Compute nblk_pv for diagnostics
nblk_pv = cute.size(tdVrP0, mode=[2])
nblk_qk = cute.size(tCrA, mode=[2])
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, self.num_acc_stage))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, self.num_acc_stage))
# COMPREHENSIVE LAYOUT DUMP
cS = cute.make_identity_tensor((self.qk_mma_tiler[0], self.qk_mma_tiler[1]))
tScS = qk_thr.partition_C(cS)
tilePlikeFP32 = self.qk_mma_tiler[1] * self.q_dtype.width // 32
tStS_P_layout = cute.composition(tStS.layout, cute.make_layout((128, tilePlikeFP32)))
tStS_P = cute.make_tensor(tStS.iterator + self.tmem_p0_offset, tStS_P_layout)
tScS_P_layout = cute.composition(tScS.layout, cute.make_layout((128, tilePlikeFP32)))
tScS_P = cute.make_tensor(tScS.iterator, tScS_P_layout)
print(f'[LAYOUT] QK C-fragment tStS.layout: {tStS.layout}')
print(f'[LAYOUT] QK C-fragment tStS cosize: {cute.cosize(tStS.layout)}')
print(f'[LAYOUT] QK C-fragment tStS.size: {cute.size(tStS)}')
print(f'[LAYOUT] QK C-fragment tScS.layout: {tScS.layout}')
print(f'[LAYOUT] QK C-fragment tScS cosize: {cute.cosize(tScS.layout)}')
print(f'[LAYOUT] PV A-fragment tdVrP.layout: {tdVrP.layout}')
print(f'[LAYOUT] PV A-fragment tdVrP cosize: {cute.cosize(tdVrP.layout)}')
print(f'[LAYOUT] PV A-fragment tdVrP.size: {cute.size(tdVrP)}')
print(f'[LAYOUT] PV A-fragment tdVrP0.layout: {tdVrP0.layout}')
print(f'[LAYOUT] PV A-fragment tdVrP0 cosize: {cute.cosize(tdVrP0.layout)}')
print(f'[LAYOUT] tP.layout: {tP.layout}')
print(f'[LAYOUT] tP cosize: {cute.cosize(tP.layout)}')
print(f'[LAYOUT] tStS_P (composed) layout: {tStS_P.layout}')
print(f'[LAYOUT] tStS_P (composed) cosize: {cute.cosize(tStS_P.layout)}')
print(f'[LAYOUT] tScS_P (composed) layout: {tScS_P.layout}')
print(f'[LAYOUT] tScS_P (composed) cosize: {cute.cosize(tScS_P.layout)}')
print(f'[LAYOUT] tOtO.layout: {tOtO.layout}')
print(f'[LAYOUT] tOtO cosize: {cute.cosize(tOtO.layout)}')
print(f'[LAYOUT] pv_mma_tiler: {self.pv_mma_tiler}')
print(f'[LAYOUT] qk_mma_tiler: {self.qk_mma_tiler}')
print(f'[LAYOUT] tilePlikeFP32: {tilePlikeFP32}')
# DIAGNOSTIC: Compare tP (A-layout) vs tStS_P (composition)
tilePlikeFP32 = self.qk_mma_tiler[1] * self.q_dtype.width // 32
tStS_P_layout = cute.composition(tStS.layout, cute.make_layout((128, tilePlikeFP32)))
tStS_P = cute.make_tensor(tStS.iterator + self.tmem_p0_offset, tStS_P_layout)
print(f'[DIAG] tP.layout: {tP.layout}')
print(f'[DIAG] tP.size: {cute.size(tP)}')
print(f'[DIAG] tP.element_type: {tP.element_type if hasattr(tP, 'element_type') else 'N/A'}')
print(f'[DIAG] tStS_P.layout: {tStS_P.layout}')
print(f'[DIAG] tStS_P.size: {cute.size(tStS_P)}')
print(f'[DIAG] tStS_P.element_type: {tStS_P.element_type if hasattr(tStS_P, 'element_type') else 'N/A'}')
print(f'[DIAG] tilePlikeFP32: {tilePlikeFP32}')
print(f'[DIAG] tP and tStS_P same iterator? {tP.iterator == tStS_P.iterator if hasattr(tP, 'iterator') else 'cant compare'}')
print(f'[DIAG] nblk_pv = {nblk_pv}, nblk_qk = {nblk_qk}')
print(f'[DIAG] tCrV.size = {cute.size(tCrV)}')
print(f'[DIAG] tdVrP0.size = {cute.size(tdVrP0)}')
pipeline.pipeline_init_wait(cluster_shape_mn=cl_vmnk)
# ── TMA WARP ──
if warp_idx == self.tma_warp_id:
ab_p.reset(); peek = ab_p.try_acquire()
for kt in cutlass.range(k_cnt, unroll=1):
h = ab_p.acquire_and_advance(peek)
cute.copy(tma_a, tAgA[(None,h.count)], tAsA[(None,h.index)], tma_bar_ptr=h.barrier)
cute.copy(tma_b, tBgB[(None,h.count)], tBsB[(None,h.index)], tma_bar_ptr=h.barrier)
peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_p.try_acquire()
ab_p.tail()
# ── MMA WARP ──
if warp_idx == self.mma_warp_id:
tmem.wait_for_alloc()
ab_c.reset(); peek = ab_c.try_wait()
s0_handle = mma_si_prod.acquire_and_advance()
acc_prod_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Producer, self.num_acc_stage)
acc_pipe.producer_acquire(acc_prod_st)
qk_mma.set(tcgen05.Field.ACCUMULATE, False)
for kt in range(k_cnt):
h = ab_c.wait_and_advance(peek)
nblk = cute.size(tCrA, mode=[2])
for kb in cutlass.range(nblk, unroll_full=True):
cute.gemm(qk_mma, tStS0, tCrA[(None,None,kb,h.index)], tCrB[(None,None,kb,h.index)], tStS0)
qk_mma.set(tcgen05.Field.ACCUMULATE, True)
h.release(); peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_c.try_wait()
cute.arch.fence_view_async_tmem_store()
s0_handle.commit()
s0_handle = mma_si_prod.acquire_and_advance()
pv_mma.set(tcgen05.Field.ACCUMULATE, True)
tCrV_s = tCrV[(None, None, None, 0)]
nblk_pv = cute.size(tdVrP0, mode=[2])
for kb in cutlass.range(nblk_pv, unroll_full=True):
cute.gemm(pv_mma, tOtO0, tdVrP0[(None,None,kb)], tCrV_s[(None,None,kb)], tOtO0)
acc_pipe.producer_commit(acc_prod_st)
acc_prod_st.advance()
acc_pipe.producer_tail(acc_prod_st)
# ── SOFTMAX / EPILOGUE WARPS ──
if warp_idx < self.mma_warp_id:
tmem.allocate(self.num_tmem_alloc_cols)
tmem.wait_for_alloc()
tmem_ptr = tmem.retrieve_ptr(self.qk_acc_dtype)
sfw_idx = tidx % (32 * len(self.epilogue_warp_id))
# ── Identity softmax: C-layout → A-layout transform ──
# 1. LOAD pipeline (reads scores from QK C-layout)
tmem_load_atom = cute.make_copy_atom(
tcgen05.copy.Ld32x32bOp(tcgen05.copy.Repetition(32)), self.qk_acc_dtype)
tiled_tmem_load = tcgen05.make_tmem_copy(tmem_load_atom, tStS0)
thr_load = tiled_tmem_load.get_slice(sfw_idx)
tTMEM_LOADtS = thr_load.partition_S(tStS0)
cS = cute.make_identity_tensor((self.qk_mma_tiler[0], self.qk_mma_tiler[1]))
tScS = qk_thr.partition_C(cS)
tTMEM_LOADcS = thr_load.partition_D(tScS)
# 2. STORE pipeline (backward FMHA: A-fragment, BF16 St32x32bOp)
tmem_store_atom = cute.make_copy_atom(
tcgen05.copy.St32x32bOp(tcgen05.copy.Repetition(8)), self.q_dtype)
tiled_tmem_store = tcgen05.make_tmem_copy(tmem_store_atom, tdVrP0)
thr_store = tiled_tmem_store.get_slice(sfw_idx)
tRT_tP = thr_store.partition_D(tdVrP0)
cS_store = cute.make_identity_tensor((self.qk_mma_tiler[0], self.qk_mma_tiler[1]))
tdVcS = pv_thr.partition_A(cS_store)
tRT_cS = thr_store.partition_S(tdVcS)
# 3. Wait for scores
si_handle = mma_si_cons.wait_and_advance()
# 4. Load from C-layout
tTMEM_LOADrS = cute.make_rmem_tensor(tTMEM_LOADcS.shape, self.qk_acc_dtype)
cute.copy(tiled_tmem_load, tTMEM_LOADtS, tTMEM_LOADrS)
cute.arch.fence_view_async_tmem_load()
# 5. Quantize FP32 -> BF16 (backward FMHA pattern)
tRT_rST_bf16 = cute.make_rmem_tensor(tTMEM_LOADrS.shape, self.q_dtype)
frg_cnt = 4
frg_tile = cute.size(tTMEM_LOADrS) // frg_cnt
tTR_rST_frg = cute.logical_divide(tTMEM_LOADrS, cute.make_layout(frg_tile))
tRT_rST_bf16_frg = cute.make_tensor(tRT_rST_bf16.iterator, tTR_rST_frg.layout)
for j in range(frg_cnt):
frg_vec = tTR_rST_frg[None, j].load()
tRT_rST_bf16_frg[None, j].store(frg_vec.to(self.q_dtype))
# 6. Reshape and store to A-fragment TMEM
tRT_rST_reshaped = cute.make_tensor(
tRT_rST_bf16.iterator, cute.make_layout(tRT_cS.shape))
cute.copy(tiled_tmem_store, tRT_rST_reshaped, tRT_tP)
cute.arch.fence_view_async_tmem_store()
# 7. Release back to MMA warp
si_handle.release()
# ── Epilogue ──
tCtO_base = cute.make_tensor(tmem_ptr + self.tmem_o0_offset, tCtO_fake.layout)
acc_cons_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Consumer, self.num_acc_stage)
c_grp = pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id))
c_pipe = pipeline.PipelineTmaStore.create(num_stages=self.num_c_stage, producer_group=c_grp)
acc_cons_st = utils.gemm.sm100.epilogue_tma_store(
self, tidx, warp_idx, tma_c, tCtO_base, sC, tCgC,
epi_tile, 0, const_expr(lambda x: x), (0,0,0), acc_cons_st, acc_pipe, c_pipe)
c_pipe.producer_tail()
tmem.relinquish_alloc_permit()
tmem.free(tmem_ptr)
def test():
torch.manual_seed(42)
m, n, k = 128, 128, 128
q = torch.randn(m, k, 1, dtype=torch.bfloat16, device='cuda')
kv = torch.randn(n, k, 1, dtype=torch.bfloat16, device='cuda')
c = torch.zeros(m, n, 1, dtype=torch.bfloat16, device='cuda')
qf = q[:,:,0].float(); kvf = kv[:,:,0].float()
ref = qf @ kvf.T @ kvf
import cutlass.torch as ct
mQ = ct.from_dlpack(q).mark_layout_dynamic(leading_dim=ct.get_leading_dim(q))
mK = ct.from_dlpack(kv).mark_layout_dynamic(leading_dim=ct.get_leading_dim(kv))
mC = ct.from_dlpack(c).mark_layout_dynamic(leading_dim=ct.get_leading_dim(c))
stream = cuda.CUstream(torch.cuda.current_stream().cuda_stream)
kernel = StageBIdentitySoftmax(mma_tiler_mn=(128, 128), use_2cta_instrs=False, use_tma_store=True)
print('Compiling...', flush=True)
compiled = cute.compile(kernel, mQ, mK, mC, stream)
print('Running...', flush=True)
compiled(mQ, mK, mC, stream)
torch.cuda.synchronize()
out = c[:,:,0].float()
cos = torch.nn.functional.cosine_similarity(out.flatten().unsqueeze(0), ref.flatten().unsqueeze(0)).item()
max_err = (out - ref).abs().max().item()
print('Stage B v7: (Q @ K^T) @ V with identity softmax (computed TMEM offsets)')
print(' Cosine: {:.6f}, Max error: {:.6f}'.format(cos, max_err))
print(' {}'.format('PASS' if cos >= 0.99 else 'FAIL'))
if __name__ == '__main__':
test()

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tests/test_stage_b_v17.py Normal file
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"""
Stage B v7: Two MMAs + Identity Softmax with COMPUTED TMEM offsets.
Key fixes over v6:
- TMEM offsets computed via find_tmem_tensor_col_offset (same API as get_num_tmem_alloc_cols)
- P tensor constructed from p_tmem_s.outer (matching fmha.py pattern exactly)
- tilePlikeFP32 computed from qk_mma_tiler and dtype widths
- tmem_alloc_cols from get_num_tmem_alloc_cols with all fragments
- JIT-time diagnostic prints of all TMEM sizes
Architecture (matches fmha.py exactly):
MMA1: Q @ K^T → tmem_scores (a_source=SMEM, accumulate=False)
Identity softmax: tcgen05.ld C-layout → F32→BF16 → tcgen05.st A-layout
MMA2: P @ V → tmem_output (a_source=TMEM, accumulate=True)
"""
import torch, cutlass, cutlass.cute as cute, cutlass.utils as utils, cutlass.pipeline as pipeline
from cutlass.cute.nvgpu import cpasync, tcgen05
from cutlass import Float32, BFloat16, Int32, Boolean, const_expr
from cutlass.utils import LayoutEnum
from cutlass.utils.tmem_allocator import find_tmem_tensor_col_offset
import cuda.bindings.driver as cuda
class StageBIdentitySoftmax:
def __init__(self, mma_tiler_mn, use_2cta_instrs=False, use_tma_store=True):
self.acc_dtype = Float32; self.qk_acc_dtype = Float32
self.q_dtype = BFloat16; self.o_dtype = BFloat16
self.use_2cta_instrs = use_2cta_instrs; self.use_tma_store = use_tma_store
self.mma_tiler_mn = mma_tiler_mn; self.mma_tiler = (*mma_tiler_mn, 1)
self.cluster_shape_mn = (1, 1)
self.cta_group = tcgen05.CtaGroup.TWO if use_2cta_instrs else tcgen05.CtaGroup.ONE
self.epilogue_warp_id = (0, 1, 2, 3)
self.mma_warp_id = 4; self.tma_warp_id = 5
self.threads_per_cta = 192
self.epilog_sync_bar_id = 1; self.tmem_alloc_sync_bar_id = 2; self.tmem_dealloc_sync_bar_id = 3
self.num_c_stage = 2
def _setup(self, qk_mma, pv_mma):
qk_inst_k = cute.size(qk_mma.shape_mnk, mode=[2])
self.qk_mma_tiler = (*self.mma_tiler_mn, qk_inst_k * 4)
pv_inst_k = cute.size(pv_mma.shape_mnk, mode=[2])
self.pv_mma_tiler = (self.qk_mma_tiler[0], self.qk_mma_tiler[2], self.qk_mma_tiler[1])
self.mma_tiler = self.qk_mma_tiler
print(f"[StageB] qk_mma.shape_mnk = {qk_mma.shape_mnk}")
print(f"[StageB] pv_mma.shape_mnk = {pv_mma.shape_mnk}")
print(f"[StageB] qk_mma_tiler = {self.qk_mma_tiler}")
print(f"[StageB] pv_mma_tiler = {self.pv_mma_tiler}")
print(f"[StageB] qk_inst_k = {qk_inst_k}, pv_inst_k = {pv_inst_k}")
self.cta_tile_shape_mnk = (
self.qk_mma_tiler[0] // cute.size(qk_mma.thr_id.shape),
self.qk_mma_tiler[1],
self.qk_mma_tiler[2],
)
self.cluster_layout_vmnk = cute.tiled_divide(cute.make_layout((1,1,1)), (qk_mma.thr_id.shape,))
self.epi_tile = utils.sm100.compute_epilogue_tile_shape(
self.cta_tile_shape_mnk, self.use_2cta_instrs, self.c_layout, self.o_dtype)
self.num_ab_stage = 1; self.num_acc_stage = 1
self.a_smem_s = utils.sm100.make_smem_layout_a(qk_mma, self.mma_tiler, self.a_dtype, 1)
self.b_smem_s = utils.sm100.make_smem_layout_b(qk_mma, self.mma_tiler, self.b_dtype, 1)
self.v_smem_s = utils.sm100.make_smem_layout_b(pv_mma, self.pv_mma_tiler, self.b_dtype, 1)
self.p_tmem_s = utils.sm100.make_smem_layout_a(pv_mma, self.pv_mma_tiler, self.q_dtype, 1)
self.c_smem_s = utils.sm100.make_smem_layout_epi(self.o_dtype, self.c_layout, self.epi_tile, 2)
# ── COMPUTE TMEM OFFSETS USING find_tmem_tensor_col_offset ──
qk_thr = qk_mma.get_slice(0)
qk_acc_shape = qk_thr.partition_shape_C(self.mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
s_cols = find_tmem_tensor_col_offset(tStS)
pv_thr = pv_mma.get_slice(0)
pv_acc_shape = pv_thr.partition_shape_C(self.mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
o_cols = find_tmem_tensor_col_offset(tOtO)
# tilePlikeFP32 for the store-side composition
self.tilePlikeFP32 = self.qk_mma_tiler[1] * self.q_dtype.width // 32
# ── TMEM LAYOUT (matching fmha.py) ──
# P OVERLAPS S — after softmax, P (A-layout) is written on top of scores (C-layout)
# in the same TMEM region. The A-layout view starts partway through the S region.
# fmha.py: S0=0, P0=32, O0=256 (with S1=128, P1=160 double-buffered)
# The P offset of 32 means the A-layout starts at column 32 within the S region.
# This is because the C-layout and A-layout partition TMEM differently per-thread;
# the first 32 C-layout columns are "dead space" in the A-layout mapping.
#
self.tmem_s0_offset = 0
self.tmem_p0_offset = 32 # Original
self.tmem_o0_offset = s_cols # 128
self.tmem_alloc_cols = s_cols + o_cols # 256
# Also compute via get_num_tmem_alloc_cols for the full allocation
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, 1))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, 1))
self.num_tmem_alloc_cols = utils.get_num_tmem_alloc_cols([tCtS_fake, tCtO_fake], arch="sm_100")
print(f"[StageB] s_cols (QK accumulator) = {s_cols}")
print(f"[StageB] o_cols (PV accumulator) = {o_cols}")
print(f"[StageB] tilePlikeFP32 = {self.tilePlikeFP32}")
print(f"[StageB] tmem_s0_offset = {self.tmem_s0_offset}")
print(f"[StageB] tmem_p0_offset = {self.tmem_p0_offset}")
print(f"[StageB] tmem_o0_offset = {self.tmem_o0_offset}")
print(f"[StageB] tmem_alloc_cols (computed) = {self.tmem_alloc_cols}")
print(f"[StageB] num_tmem_alloc_cols (via utils) = {self.num_tmem_alloc_cols}")
a_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
b_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
self.num_tma_load_bytes = (
cute.size_in_bytes(self.a_dtype, a_smem) + cute.size_in_bytes(self.b_dtype, b_smem)
) * cute.size(qk_mma.thr_id.shape)
@cute.jit
def __call__(self, a: cute.Tensor, b: cute.Tensor, c: cute.Tensor, stream: cuda.CUstream):
self.a_dtype = a.element_type; self.b_dtype = b.element_type; self.c_dtype = c.element_type
self.a_major = LayoutEnum.from_tensor(a).mma_major_mode()
self.b_major = LayoutEnum.from_tensor(b).mma_major_mode()
self.c_layout = LayoutEnum.from_tensor(c)
qk_mma = utils.sm100.make_trivial_tiled_mma(
self.a_dtype, self.b_dtype, self.a_major, self.b_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.SMEM)
pv_mma = utils.sm100.make_trivial_tiled_mma(
self.a_dtype, self.b_dtype, cute.nvgpu.OperandMajorMode.K, self.b_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.TMEM)
# Introspect PV MMA atom
print(f"[ATOM] PV MMA type: {type(pv_mma)}")
print(f"[ATOM] PV MMA op: {pv_mma.op if hasattr(pv_mma, "op") else "no op"}")
print(f"[ATOM] PV MMA trait: {pv_mma._trait if hasattr(pv_mma, "_trait") else "no trait"}")
print(f"[ATOM] PV MMA shape_mnk: {pv_mma.shape_mnk}")
print(f"[ATOM] QK MMA shape_mnk: {qk_mma.shape_mnk}")
# Check a_src
print(f"[ATOM] PV MMA op.a_src: {pv_mma.op.a_src}")
print(f"[ATOM] QK MMA op.a_src: {qk_mma.op.a_src}")
print(f"[ATOM] PV MMA op: {pv_mma.op}")
self._setup(qk_mma, pv_mma)
a_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
b_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
tma_a, tma_ta = cute.nvgpu.make_tiled_tma_atom_A(
utils.sm100.cluster_shape_to_tma_atom_A(self.cluster_shape_mn, qk_mma.thr_id),
a, a_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
tma_b, tma_tb = cute.nvgpu.make_tiled_tma_atom_B(
utils.sm100.cluster_shape_to_tma_atom_B(self.cluster_shape_mn, qk_mma.thr_id),
b, b_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
epi_smem = cute.select(self.c_smem_s, mode=[0, 1])
tma_c, tma_tc = cpasync.make_tiled_tma_atom(cpasync.CopyBulkTensorTileS2GOp(), c, epi_smem, self.epi_tile)
self._kernel(qk_mma, pv_mma, tma_a, tma_ta, tma_b, tma_tb, tma_c, tma_tc,
self.cluster_layout_vmnk, self.a_smem_s, self.b_smem_s, self.v_smem_s, self.p_tmem_s, self.c_smem_s, self.epi_tile
).launch(grid=(1,1,1), block=[self.threads_per_cta,1,1], stream=stream)
@cute.kernel
def _kernel(self, qk_mma, pv_mma, tma_a, mA, tma_b, mB, tma_c, mC, cl_vmnk,
a_smem_s, b_smem_s, v_smem_s, p_tmem_s, c_smem_s, epi_tile):
warp_idx = cute.arch.make_warp_uniform(cute.arch.warp_idx())
tidx, _, _ = cute.arch.thread_idx()
use_2cta = cute.size(qk_mma.thr_id.shape) == 2
if warp_idx == self.tma_warp_id:
cpasync.prefetch_descriptor(tma_a); cpasync.prefetch_descriptor(tma_b); cpasync.prefetch_descriptor(tma_c)
@cute.struct
class SS:
ab_bar: cute.struct.MemRange[cutlass.Int64, self.num_ab_stage * 2]
mma_si_bar: cute.struct.MemRange[cutlass.Int64, 2]
acc_bar: cute.struct.MemRange[cutlass.Int64, self.num_acc_stage * 2]
tmem_dealloc: cutlass.Int64
holding: cutlass.Int32
smem = utils.SmemAllocator(); st = smem.allocate(SS)
ab_p, ab_c = pipeline.PipelineTmaUmma.create(
barrier_storage=st.ab_bar.data_ptr(), num_stages=self.num_ab_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 1),
tx_count=self.num_tma_load_bytes, cta_layout_vmnk=cl_vmnk, defer_sync=True
).make_participants()
mma_si_prod, mma_si_cons = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.mma_si_bar.data_ptr(), num_stages=1,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id)),
cta_layout_vmnk=cl_vmnk, defer_sync=True
).make_participants()
acc_pipe = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.acc_bar.data_ptr(), num_stages=self.num_acc_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(
pipeline.Agent.Thread, len(self.epilogue_warp_id) * (2 if use_2cta else 1)),
cta_layout_vmnk=cl_vmnk, defer_sync=True)
tmem_bar = pipeline.NamedBarrier(barrier_id=self.tmem_alloc_sync_bar_id,
num_threads=32 * len((self.mma_warp_id, *self.epilogue_warp_id)))
tmem = utils.TmemAllocator(st.holding.ptr, barrier_for_retrieve=tmem_bar,
allocator_warp_id=self.epilogue_warp_id[0], is_two_cta=use_2cta,
two_cta_tmem_dealloc_mbar_ptr=st.tmem_dealloc.ptr)
pipeline.pipeline_init_arrive(cluster_shape_mn=cl_vmnk, is_relaxed=True)
sA = smem.allocate_tensor(element_type=self.a_dtype, layout=a_smem_s.outer, byte_alignment=128, swizzle=a_smem_s.inner)
sB = smem.allocate_tensor(element_type=self.b_dtype, layout=b_smem_s.outer, byte_alignment=128, swizzle=b_smem_s.inner)
# V shares the same SMEM as B (same data, different layout for PV MMA)
sV_ptr = cute.recast_ptr(sB.iterator, v_smem_s.inner)
sV = cute.make_tensor(sV_ptr, v_smem_s.outer)
sC = smem.allocate_tensor(element_type=self.o_dtype, layout=c_smem_s.outer, byte_alignment=128, swizzle=c_smem_s.inner)
gA = cute.local_tile(mA, cute.slice_(self.mma_tiler, (None,0,None)), (None,None,None))
gB = cute.local_tile(mB, cute.slice_(self.mma_tiler, (0,None,None)), (None,None,None))
gC = cute.local_tile(mC, cute.slice_(self.mma_tiler, (None,None,0)), (None,None,None))
k_cnt = cute.size(gA, mode=[3])
qk_thr = qk_mma.get_slice(0)
tCgA = qk_thr.partition_A(gA); tCgB = qk_thr.partition_B(gB); tCgC = qk_thr.partition_C(gC)
a_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,0,None,0)).shape)
tAsA, tAgA = cpasync.tma_partition(tma_a, 0, a_lay, cute.group_modes(sA,0,3), cute.group_modes(tCgA,0,3))
b_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,None,0,0)).shape)
tBsB, tBgB = cpasync.tma_partition(tma_b, 0, b_lay, cute.group_modes(sB,0,3), cute.group_modes(tCgB,0,3))
tAgA = tAgA[(None,0,None,0)]; tBgB = tBgB[(None,0,None,0)]
tCrA = qk_mma.make_fragment_A(sA); tCrB = qk_mma.make_fragment_B(sB)
tCrV = pv_mma.make_fragment_B(sV) # V fragment from V SMEM layout
print(f"[DIAG] tCrV.size = {cute.size(tCrV)}")
print(f"[DIAG] tCrA.size = {cute.size(tCrA)}")
print(f"[DIAG] tCrB.size = {cute.size(tCrB)}")
print(f"[DIAG] nblk_qk (tCrA mode 2) = {cute.size(tCrA, mode=[2])}")
# ── TMEM tensors with computed offsets (matching fmha.py pattern) ──
qk_acc_shape = qk_thr.partition_shape_C(self.mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
tStS0 = cute.make_tensor(tStS.iterator + self.tmem_s0_offset, tStS.layout)
pv_thr = pv_mma.get_slice(0)
pv_acc_shape = pv_thr.partition_shape_C(self.mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
tOtO0 = cute.make_tensor(tOtO.iterator + self.tmem_o0_offset, tOtO.layout)
# P fragment: construct from p_tmem_s layout (matching fmha.py exactly)
# fmha.py: tP = cute.make_tensor(tStS.iterator, p_tmem_layout_staged.outer)
# tOrP = pv_thr_mma.make_fragment_A(tP)[None, None, None, 0]
# tOrP0 = cute.make_tensor(tOrP.iterator + dtype_width_ratio * tmem_p0_offset, tOrP.layout)
print(f'[TMEM] p_tmem_s: {p_tmem_s}')
print(f'[TMEM] p_tmem_s.outer: {p_tmem_s.outer}')
print(f'[TMEM] p_tmem_s.inner: {p_tmem_s.inner}')
tP = cute.make_tensor(tStS.iterator, p_tmem_s.outer)
print(f'[DIAG] tStS.layout: {tStS.layout}')
print(f'[DIAG] tStS.size: {cute.size(tStS)}')
print(f'[DIAG] p_tmem_s.outer: {p_tmem_s.outer}')
print(f'[DIAG] p_tmem_s.inner: {p_tmem_s.inner}')
tOrP_base = pv_thr.make_fragment_A(tP)
tOrP = tOrP_base[(None, None, None, 0)]
tOrP0 = cute.make_tensor(
tOrP.iterator + self.qk_acc_dtype.width // self.q_dtype.width * self.tmem_p0_offset,
tOrP.layout)
# Compute nblk_pv for diagnostics
nblk_pv = cute.size(tOrP0, mode=[2])
nblk_qk = cute.size(tCrA, mode=[2])
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, self.num_acc_stage))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, self.num_acc_stage))
# COMPREHENSIVE LAYOUT DUMP
cS = cute.make_identity_tensor((self.qk_mma_tiler[0], self.qk_mma_tiler[1]))
tScS = qk_thr.partition_C(cS)
tilePlikeFP32 = self.qk_mma_tiler[1] * self.q_dtype.width // 32
tStS_P_layout = cute.composition(tStS.layout, cute.make_layout((128, tilePlikeFP32)))
tStS_P = cute.make_tensor(tStS.iterator + self.tmem_p0_offset, tStS_P_layout)
tScS_P_layout = cute.composition(tScS.layout, cute.make_layout((128, tilePlikeFP32)))
tScS_P = cute.make_tensor(tScS.iterator, tScS_P_layout)
print(f'[LAYOUT] QK C-fragment tStS.layout: {tStS.layout}')
print(f'[LAYOUT] QK C-fragment tStS cosize: {cute.cosize(tStS.layout)}')
print(f'[LAYOUT] QK C-fragment tStS.size: {cute.size(tStS)}')
print(f'[LAYOUT] QK C-fragment tScS.layout: {tScS.layout}')
print(f'[LAYOUT] QK C-fragment tScS cosize: {cute.cosize(tScS.layout)}')
print(f'[LAYOUT] PV A-fragment tOrP.layout: {tOrP.layout}')
print(f'[LAYOUT] PV A-fragment tOrP cosize: {cute.cosize(tOrP.layout)}')
print(f'[LAYOUT] PV A-fragment tOrP.size: {cute.size(tOrP)}')
print(f'[LAYOUT] PV A-fragment tOrP0.layout: {tOrP0.layout}')
print(f'[LAYOUT] PV A-fragment tOrP0 cosize: {cute.cosize(tOrP0.layout)}')
print(f'[LAYOUT] tP.layout: {tP.layout}')
print(f'[LAYOUT] tP cosize: {cute.cosize(tP.layout)}')
print(f'[LAYOUT] tStS_P (composed) layout: {tStS_P.layout}')
print(f'[LAYOUT] tStS_P (composed) cosize: {cute.cosize(tStS_P.layout)}')
print(f'[LAYOUT] tScS_P (composed) layout: {tScS_P.layout}')
print(f'[LAYOUT] tScS_P (composed) cosize: {cute.cosize(tScS_P.layout)}')
print(f'[LAYOUT] tOtO.layout: {tOtO.layout}')
print(f'[LAYOUT] tOtO cosize: {cute.cosize(tOtO.layout)}')
print(f'[LAYOUT] pv_mma_tiler: {self.pv_mma_tiler}')
print(f'[LAYOUT] qk_mma_tiler: {self.qk_mma_tiler}')
print(f'[LAYOUT] tilePlikeFP32: {tilePlikeFP32}')
# DIAGNOSTIC: Compare tP (A-layout) vs tStS_P (composition)
tilePlikeFP32 = self.qk_mma_tiler[1] * self.q_dtype.width // 32
tStS_P_layout = cute.composition(tStS.layout, cute.make_layout((128, tilePlikeFP32)))
tStS_P = cute.make_tensor(tStS.iterator + self.tmem_p0_offset, tStS_P_layout)
print(f'[DIAG] tP.layout: {tP.layout}')
print(f'[DIAG] tP.size: {cute.size(tP)}')
print(f'[DIAG] tP.element_type: {tP.element_type if hasattr(tP, 'element_type') else 'N/A'}')
print(f'[DIAG] tStS_P.layout: {tStS_P.layout}')
print(f'[DIAG] tStS_P.size: {cute.size(tStS_P)}')
print(f'[DIAG] tStS_P.element_type: {tStS_P.element_type if hasattr(tStS_P, 'element_type') else 'N/A'}')
print(f'[DIAG] tilePlikeFP32: {tilePlikeFP32}')
print(f'[DIAG] tP and tStS_P same iterator? {tP.iterator == tStS_P.iterator if hasattr(tP, 'iterator') else 'cant compare'}')
print(f'[DIAG] nblk_pv = {nblk_pv}, nblk_qk = {nblk_qk}')
print(f'[DIAG] tCrV.size = {cute.size(tCrV)}')
print(f'[DIAG] tOrP0.size = {cute.size(tOrP0)}')
pipeline.pipeline_init_wait(cluster_shape_mn=cl_vmnk)
# ── TMA WARP ──
if warp_idx == self.tma_warp_id:
ab_p.reset(); peek = ab_p.try_acquire()
for kt in cutlass.range(k_cnt, unroll=1):
h = ab_p.acquire_and_advance(peek)
cute.copy(tma_a, tAgA[(None,h.count)], tAsA[(None,h.index)], tma_bar_ptr=h.barrier)
cute.copy(tma_b, tBgB[(None,h.count)], tBsB[(None,h.index)], tma_bar_ptr=h.barrier)
peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_p.try_acquire()
ab_p.tail()
# ── MMA WARP ──
if warp_idx == self.mma_warp_id:
tmem.wait_for_alloc()
ab_c.reset(); peek = ab_c.try_wait()
s0_handle = mma_si_prod.acquire_and_advance()
acc_prod_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Producer, self.num_acc_stage)
acc_pipe.producer_acquire(acc_prod_st)
qk_mma.set(tcgen05.Field.ACCUMULATE, False)
for kt in range(k_cnt):
h = ab_c.wait_and_advance(peek)
nblk = cute.size(tCrA, mode=[2])
for kb in cutlass.range(nblk, unroll_full=True):
cute.gemm(qk_mma, tStS0, tCrA[(None,None,kb,h.index)], tCrB[(None,None,kb,h.index)], tStS0)
qk_mma.set(tcgen05.Field.ACCUMULATE, True)
h.release(); peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_c.try_wait()
cute.arch.fence_view_async_tmem_store()
s0_handle.commit()
s0_handle = mma_si_prod.acquire_and_advance()
pv_mma.set(tcgen05.Field.ACCUMULATE, True)
tCrV_s = tCrV[(None, None, None, 0)]
nblk_pv = cute.size(tOrP0, mode=[2])
for kb in cutlass.range(nblk_pv, unroll_full=True):
cute.gemm(pv_mma, tOtO0, tOrP0[(None,None,kb)], tCrV_s[(None,None,kb)], tOtO0)
acc_pipe.producer_commit(acc_prod_st)
acc_prod_st.advance()
acc_pipe.producer_tail(acc_prod_st)
# ── SOFTMAX / EPILOGUE WARPS ──
if warp_idx < self.mma_warp_id:
tmem.allocate(self.num_tmem_alloc_cols)
tmem.wait_for_alloc()
tmem_ptr = tmem.retrieve_ptr(self.qk_acc_dtype)
sfw_idx = tidx % (32 * len(self.epilogue_warp_id))
# ── Identity softmax: C-layout → A-layout transform ──
# 1. LOAD pipeline (reads scores from QK C-layout)
tmem_load_atom = cute.make_copy_atom(
tcgen05.copy.Ld32x32bOp(tcgen05.copy.Repetition(32)), self.qk_acc_dtype)
tiled_tmem_load = tcgen05.make_tmem_copy(tmem_load_atom, tStS0)
thr_load = tiled_tmem_load.get_slice(sfw_idx)
tTMEM_LOADtS = thr_load.partition_S(tStS0)
cS = cute.make_identity_tensor((self.qk_mma_tiler[0], self.qk_mma_tiler[1]))
tScS = qk_thr.partition_C(cS)
tTMEM_LOADcS = thr_load.partition_D(tScS)
# 2. STORE pipeline (writes P in A-layout — same as fmha.py softmax_step)
tStS_P_layout = cute.composition(tStS.layout, cute.make_layout((128, self.tilePlikeFP32)))
tStS_P = cute.make_tensor(tStS.iterator + self.tmem_p0_offset, tStS_P_layout)
tmem_store_atom = cute.make_copy_atom(
tcgen05.copy.St32x32bOp(tcgen05.copy.Repetition(32)), self.qk_acc_dtype)
tiled_tmem_store = tcgen05.make_tmem_copy(tmem_store_atom, tStS_P)
thr_store = tiled_tmem_store.get_slice(sfw_idx)
tTMEM_STOREtS_x4 = thr_store.partition_D(tStS_P)
tScS_P_layout = cute.composition(tScS.layout, cute.make_layout((128, self.tilePlikeFP32)))
tScS_P = cute.make_tensor(tScS.iterator, tScS_P_layout)
tTMEM_STOREcS = thr_store.partition_S(tScS_P)
# 3. Wait for scores
si_handle = mma_si_cons.wait_and_advance()
# 4. Load from C-layout
tTMEM_LOADrS = cute.make_rmem_tensor(tTMEM_LOADcS.shape, self.qk_acc_dtype)
cute.copy(tiled_tmem_load, tTMEM_LOADtS, tTMEM_LOADrS)
cute.arch.fence_view_async_tmem_load()
# 5. IDENTITY: F32 → BF16
tTMEM_STORErS_x4 = cute.make_rmem_tensor(tTMEM_STOREcS.shape, self.qk_acc_dtype)
tTMEM_STORErS_x4_e = cute.make_tensor(
cute.recast_ptr(tTMEM_STORErS_x4.iterator, dtype=self.q_dtype),
tTMEM_LOADrS.layout)
s_vec = tTMEM_LOADrS.load()
tTMEM_STORErS_x4_e.store(s_vec.to(self.q_dtype))
# 6. Store into A-layout
cute.copy(tiled_tmem_store, tTMEM_STORErS_x4, tTMEM_STOREtS_x4)
cute.arch.fence_view_async_tmem_store()
# 7. Release back to MMA warp
si_handle.release()
# ── Epilogue ──
tCtO_base = cute.make_tensor(tmem_ptr + self.tmem_o0_offset, tCtO_fake.layout)
acc_cons_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Consumer, self.num_acc_stage)
c_grp = pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id))
c_pipe = pipeline.PipelineTmaStore.create(num_stages=self.num_c_stage, producer_group=c_grp)
acc_cons_st = utils.gemm.sm100.epilogue_tma_store(
self, tidx, warp_idx, tma_c, tCtO_base, sC, tCgC,
epi_tile, 0, const_expr(lambda x: x), (0,0,0), acc_cons_st, acc_pipe, c_pipe)
c_pipe.producer_tail()
tmem.relinquish_alloc_permit()
tmem.free(tmem_ptr)
def test():
torch.manual_seed(42)
m, n, k = 128, 128, 128
q = torch.randn(m, k, 1, dtype=torch.bfloat16, device='cuda')
kv = torch.randn(n, k, 1, dtype=torch.bfloat16, device='cuda')
c = torch.zeros(m, n, 1, dtype=torch.bfloat16, device='cuda')
qf = q[:,:,0].float(); kvf = kv[:,:,0].float()
ref = qf @ kvf.T @ kvf
import cutlass.torch as ct
mQ = ct.from_dlpack(q).mark_layout_dynamic(leading_dim=ct.get_leading_dim(q))
mK = ct.from_dlpack(kv).mark_layout_dynamic(leading_dim=ct.get_leading_dim(kv))
mC = ct.from_dlpack(c).mark_layout_dynamic(leading_dim=ct.get_leading_dim(c))
stream = cuda.CUstream(torch.cuda.current_stream().cuda_stream)
kernel = StageBIdentitySoftmax(mma_tiler_mn=(128, 128), use_2cta_instrs=False, use_tma_store=True)
print('Compiling...', flush=True)
compiled = cute.compile(kernel, mQ, mK, mC, stream)
print('Running...', flush=True)
compiled(mQ, mK, mC, stream)
torch.cuda.synchronize()
out = c[:,:,0].float()
cos = torch.nn.functional.cosine_similarity(out.flatten().unsqueeze(0), ref.flatten().unsqueeze(0)).item()
max_err = (out - ref).abs().max().item()
print('Stage B v7: (Q @ K^T) @ V with identity softmax (computed TMEM offsets)')
print(' Cosine: {:.6f}, Max error: {:.6f}'.format(cos, max_err))
print(' {}'.format('PASS' if cos >= 0.99 else 'FAIL'))
if __name__ == '__main__':
test()

452
tests/test_stage_b_v18.py Normal file
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"""
Stage B v7: Two MMAs + Identity Softmax with COMPUTED TMEM offsets.
Key fixes over v6:
- TMEM offsets computed via find_tmem_tensor_col_offset (same API as get_num_tmem_alloc_cols)
- P tensor constructed from p_tmem_s.outer (matching fmha.py pattern exactly)
- tilePlikeFP32 computed from qk_mma_tiler and dtype widths
- tmem_alloc_cols from get_num_tmem_alloc_cols with all fragments
- JIT-time diagnostic prints of all TMEM sizes
Architecture (matches fmha.py exactly):
MMA1: Q @ K^T → tmem_scores (a_source=SMEM, accumulate=False)
Identity softmax: tcgen05.ld C-layout → F32→BF16 → tcgen05.st A-layout
MMA2: P @ V → tmem_output (a_source=TMEM, accumulate=True)
"""
import torch, cutlass, cutlass.cute as cute, cutlass.utils as utils, cutlass.pipeline as pipeline
from cutlass.cute.nvgpu import cpasync, tcgen05
from cutlass import Float32, BFloat16, Int32, Boolean, const_expr
from cutlass.utils import LayoutEnum
from cutlass.utils.tmem_allocator import find_tmem_tensor_col_offset
import cuda.bindings.driver as cuda
class StageBIdentitySoftmax:
def __init__(self, mma_tiler_mn, use_2cta_instrs=False, use_tma_store=True):
self.acc_dtype = Float32; self.qk_acc_dtype = Float32
self.q_dtype = BFloat16; self.o_dtype = BFloat16
self.use_2cta_instrs = use_2cta_instrs; self.use_tma_store = use_tma_store
self.mma_tiler_mn = mma_tiler_mn; self.mma_tiler = (*mma_tiler_mn, 1)
self.cluster_shape_mn = (1, 1)
self.cta_group = tcgen05.CtaGroup.TWO if use_2cta_instrs else tcgen05.CtaGroup.ONE
self.epilogue_warp_id = (0, 1, 2, 3)
self.mma_warp_id = 4; self.tma_warp_id = 5
self.threads_per_cta = 192
self.epilog_sync_bar_id = 1; self.tmem_alloc_sync_bar_id = 2; self.tmem_dealloc_sync_bar_id = 3
self.num_c_stage = 2
def _setup(self, qk_mma, pv_mma):
qk_inst_k = cute.size(qk_mma.shape_mnk, mode=[2])
self.qk_mma_tiler = (*self.mma_tiler_mn, qk_inst_k * 4)
pv_inst_k = cute.size(pv_mma.shape_mnk, mode=[2])
self.pv_mma_tiler = (self.qk_mma_tiler[0], self.qk_mma_tiler[2], self.qk_mma_tiler[1])
self.mma_tiler = self.qk_mma_tiler
print(f"[StageB] qk_mma.shape_mnk = {qk_mma.shape_mnk}")
print(f"[StageB] pv_mma.shape_mnk = {pv_mma.shape_mnk}")
print(f"[StageB] qk_mma_tiler = {self.qk_mma_tiler}")
print(f"[StageB] pv_mma_tiler = {self.pv_mma_tiler}")
print(f"[StageB] qk_inst_k = {qk_inst_k}, pv_inst_k = {pv_inst_k}")
self.cta_tile_shape_mnk = (
self.qk_mma_tiler[0] // cute.size(qk_mma.thr_id.shape),
self.qk_mma_tiler[1],
self.qk_mma_tiler[2],
)
self.cluster_layout_vmnk = cute.tiled_divide(cute.make_layout((1,1,1)), (qk_mma.thr_id.shape,))
self.epi_tile = utils.sm100.compute_epilogue_tile_shape(
self.cta_tile_shape_mnk, self.use_2cta_instrs, self.c_layout, self.o_dtype)
self.num_ab_stage = 1; self.num_acc_stage = 1
self.a_smem_s = utils.sm100.make_smem_layout_a(qk_mma, self.mma_tiler, self.a_dtype, 1)
self.b_smem_s = utils.sm100.make_smem_layout_b(qk_mma, self.mma_tiler, self.b_dtype, 1)
self.v_smem_s = utils.sm100.make_smem_layout_b(pv_mma, self.pv_mma_tiler, self.b_dtype, 1)
self.p_tmem_s = utils.sm100.make_smem_layout_a(pv_mma, self.pv_mma_tiler, self.q_dtype, 1)
self.c_smem_s = utils.sm100.make_smem_layout_epi(self.o_dtype, self.c_layout, self.epi_tile, 2)
# ── COMPUTE TMEM OFFSETS USING find_tmem_tensor_col_offset ──
qk_thr = qk_mma.get_slice(0)
qk_acc_shape = qk_thr.partition_shape_C(self.mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
s_cols = find_tmem_tensor_col_offset(tStS)
pv_thr = pv_mma.get_slice(0)
pv_acc_shape = pv_thr.partition_shape_C(self.mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
o_cols = find_tmem_tensor_col_offset(tOtO)
# tilePlikeFP32 for the store-side composition
self.tilePlikeFP32 = self.qk_mma_tiler[1] * self.q_dtype.width // 32
# ── TMEM LAYOUT (matching fmha.py) ──
# P OVERLAPS S — after softmax, P (A-layout) is written on top of scores (C-layout)
# in the same TMEM region. The A-layout view starts partway through the S region.
# fmha.py: S0=0, P0=32, O0=256 (with S1=128, P1=160 double-buffered)
# The P offset of 32 means the A-layout starts at column 32 within the S region.
# This is because the C-layout and A-layout partition TMEM differently per-thread;
# the first 32 C-layout columns are "dead space" in the A-layout mapping.
#
self.tmem_s0_offset = 0
self.tmem_p0_offset = 32 # Original
self.tmem_o0_offset = s_cols # 128
self.tmem_alloc_cols = 512 # FMHA-style: allocate max TMEM # 256
# Also compute via get_num_tmem_alloc_cols for the full allocation
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, 1))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, 1))
self.num_tmem_alloc_cols = utils.get_num_tmem_alloc_cols([tCtS_fake, tCtO_fake], arch="sm_100")
print(f"[StageB] s_cols (QK accumulator) = {s_cols}")
print(f"[StageB] o_cols (PV accumulator) = {o_cols}")
print(f"[StageB] tilePlikeFP32 = {self.tilePlikeFP32}")
print(f"[StageB] tmem_s0_offset = {self.tmem_s0_offset}")
print(f"[StageB] tmem_p0_offset = {self.tmem_p0_offset}")
print(f"[StageB] tmem_o0_offset = {self.tmem_o0_offset}")
print(f"[StageB] tmem_alloc_cols (computed) = {self.tmem_alloc_cols}")
print(f"[StageB] num_tmem_alloc_cols (via utils) = {self.num_tmem_alloc_cols}")
a_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
b_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
self.num_tma_load_bytes = (
cute.size_in_bytes(self.a_dtype, a_smem) + cute.size_in_bytes(self.b_dtype, b_smem)
) * cute.size(qk_mma.thr_id.shape)
@cute.jit
def __call__(self, a: cute.Tensor, b: cute.Tensor, c: cute.Tensor, stream: cuda.CUstream):
self.a_dtype = a.element_type; self.b_dtype = b.element_type; self.c_dtype = c.element_type
self.a_major = LayoutEnum.from_tensor(a).mma_major_mode()
self.b_major = LayoutEnum.from_tensor(b).mma_major_mode()
self.c_layout = LayoutEnum.from_tensor(c)
qk_mma = utils.sm100.make_trivial_tiled_mma(
self.a_dtype, self.b_dtype, self.a_major, self.b_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.SMEM)
pv_mma = utils.sm100.make_trivial_tiled_mma(
self.a_dtype, self.b_dtype, cute.nvgpu.OperandMajorMode.K, self.b_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.TMEM)
# Introspect PV MMA atom
print(f"[ATOM] PV MMA type: {type(pv_mma)}")
print(f"[ATOM] PV MMA op: {pv_mma.op if hasattr(pv_mma, "op") else "no op"}")
print(f"[ATOM] PV MMA trait: {pv_mma._trait if hasattr(pv_mma, "_trait") else "no trait"}")
print(f"[ATOM] PV MMA shape_mnk: {pv_mma.shape_mnk}")
print(f"[ATOM] QK MMA shape_mnk: {qk_mma.shape_mnk}")
# Check a_src
print(f"[ATOM] PV MMA op.a_src: {pv_mma.op.a_src}")
print(f"[ATOM] QK MMA op.a_src: {qk_mma.op.a_src}")
print(f"[ATOM] PV MMA op: {pv_mma.op}")
self._setup(qk_mma, pv_mma)
a_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
b_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
tma_a, tma_ta = cute.nvgpu.make_tiled_tma_atom_A(
utils.sm100.cluster_shape_to_tma_atom_A(self.cluster_shape_mn, qk_mma.thr_id),
a, a_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
tma_b, tma_tb = cute.nvgpu.make_tiled_tma_atom_B(
utils.sm100.cluster_shape_to_tma_atom_B(self.cluster_shape_mn, qk_mma.thr_id),
b, b_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
epi_smem = cute.select(self.c_smem_s, mode=[0, 1])
tma_c, tma_tc = cpasync.make_tiled_tma_atom(cpasync.CopyBulkTensorTileS2GOp(), c, epi_smem, self.epi_tile)
self._kernel(qk_mma, pv_mma, tma_a, tma_ta, tma_b, tma_tb, tma_c, tma_tc,
self.cluster_layout_vmnk, self.a_smem_s, self.b_smem_s, self.v_smem_s, self.p_tmem_s, self.c_smem_s, self.epi_tile
).launch(grid=(1,1,1), block=[self.threads_per_cta,1,1], stream=stream)
@cute.kernel
def _kernel(self, qk_mma, pv_mma, tma_a, mA, tma_b, mB, tma_c, mC, cl_vmnk,
a_smem_s, b_smem_s, v_smem_s, p_tmem_s, c_smem_s, epi_tile):
warp_idx = cute.arch.make_warp_uniform(cute.arch.warp_idx())
tidx, _, _ = cute.arch.thread_idx()
use_2cta = cute.size(qk_mma.thr_id.shape) == 2
if warp_idx == self.tma_warp_id:
cpasync.prefetch_descriptor(tma_a); cpasync.prefetch_descriptor(tma_b); cpasync.prefetch_descriptor(tma_c)
@cute.struct
class SS:
ab_bar: cute.struct.MemRange[cutlass.Int64, self.num_ab_stage * 2]
mma_si_bar: cute.struct.MemRange[cutlass.Int64, 2]
acc_bar: cute.struct.MemRange[cutlass.Int64, self.num_acc_stage * 2]
tmem_dealloc: cutlass.Int64
holding: cutlass.Int32
smem = utils.SmemAllocator(); st = smem.allocate(SS)
ab_p, ab_c = pipeline.PipelineTmaUmma.create(
barrier_storage=st.ab_bar.data_ptr(), num_stages=self.num_ab_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 1),
tx_count=self.num_tma_load_bytes, cta_layout_vmnk=cl_vmnk, defer_sync=True
).make_participants()
mma_si_prod, mma_si_cons = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.mma_si_bar.data_ptr(), num_stages=1,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id)),
cta_layout_vmnk=cl_vmnk, defer_sync=True
).make_participants()
acc_pipe = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.acc_bar.data_ptr(), num_stages=self.num_acc_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(
pipeline.Agent.Thread, len(self.epilogue_warp_id) * (2 if use_2cta else 1)),
cta_layout_vmnk=cl_vmnk, defer_sync=True)
tmem_bar = pipeline.NamedBarrier(barrier_id=self.tmem_alloc_sync_bar_id,
num_threads=32 * len((self.mma_warp_id, *self.epilogue_warp_id)))
tmem = utils.TmemAllocator(st.holding.ptr, barrier_for_retrieve=tmem_bar,
allocator_warp_id=self.epilogue_warp_id[0], is_two_cta=use_2cta,
two_cta_tmem_dealloc_mbar_ptr=st.tmem_dealloc.ptr)
pipeline.pipeline_init_arrive(cluster_shape_mn=cl_vmnk, is_relaxed=True)
sA = smem.allocate_tensor(element_type=self.a_dtype, layout=a_smem_s.outer, byte_alignment=128, swizzle=a_smem_s.inner)
sB = smem.allocate_tensor(element_type=self.b_dtype, layout=b_smem_s.outer, byte_alignment=128, swizzle=b_smem_s.inner)
# V shares the same SMEM as B (same data, different layout for PV MMA)
sV_ptr = cute.recast_ptr(sB.iterator, v_smem_s.inner)
sV = cute.make_tensor(sV_ptr, v_smem_s.outer)
sC = smem.allocate_tensor(element_type=self.o_dtype, layout=c_smem_s.outer, byte_alignment=128, swizzle=c_smem_s.inner)
gA = cute.local_tile(mA, cute.slice_(self.mma_tiler, (None,0,None)), (None,None,None))
gB = cute.local_tile(mB, cute.slice_(self.mma_tiler, (0,None,None)), (None,None,None))
gC = cute.local_tile(mC, cute.slice_(self.mma_tiler, (None,None,0)), (None,None,None))
k_cnt = cute.size(gA, mode=[3])
qk_thr = qk_mma.get_slice(0)
tCgA = qk_thr.partition_A(gA); tCgB = qk_thr.partition_B(gB); tCgC = qk_thr.partition_C(gC)
a_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,0,None,0)).shape)
tAsA, tAgA = cpasync.tma_partition(tma_a, 0, a_lay, cute.group_modes(sA,0,3), cute.group_modes(tCgA,0,3))
b_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,None,0,0)).shape)
tBsB, tBgB = cpasync.tma_partition(tma_b, 0, b_lay, cute.group_modes(sB,0,3), cute.group_modes(tCgB,0,3))
tAgA = tAgA[(None,0,None,0)]; tBgB = tBgB[(None,0,None,0)]
tCrA = qk_mma.make_fragment_A(sA); tCrB = qk_mma.make_fragment_B(sB)
tCrV = pv_mma.make_fragment_B(sV) # V fragment from V SMEM layout
print(f"[DIAG] tCrV.size = {cute.size(tCrV)}")
print(f"[DIAG] tCrA.size = {cute.size(tCrA)}")
print(f"[DIAG] tCrB.size = {cute.size(tCrB)}")
print(f"[DIAG] nblk_qk (tCrA mode 2) = {cute.size(tCrA, mode=[2])}")
# ── TMEM tensors with computed offsets (matching fmha.py pattern) ──
qk_acc_shape = qk_thr.partition_shape_C(self.mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
tStS0 = cute.make_tensor(tStS.iterator + self.tmem_s0_offset, tStS.layout)
pv_thr = pv_mma.get_slice(0)
pv_acc_shape = pv_thr.partition_shape_C(self.mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
tOtO0 = cute.make_tensor(tOtO.iterator + self.tmem_o0_offset, tOtO.layout)
# P fragment: construct from p_tmem_s layout (matching fmha.py exactly)
# fmha.py: tP = cute.make_tensor(tStS.iterator, p_tmem_layout_staged.outer)
# tOrP = pv_thr_mma.make_fragment_A(tP)[None, None, None, 0]
# tOrP0 = cute.make_tensor(tOrP.iterator + dtype_width_ratio * tmem_p0_offset, tOrP.layout)
print(f'[TMEM] p_tmem_s: {p_tmem_s}')
print(f'[TMEM] p_tmem_s.outer: {p_tmem_s.outer}')
print(f'[TMEM] p_tmem_s.inner: {p_tmem_s.inner}')
tP = cute.make_tensor(tStS.iterator, p_tmem_s.outer)
print(f'[DIAG] tStS.layout: {tStS.layout}')
print(f'[DIAG] tStS.size: {cute.size(tStS)}')
print(f'[DIAG] p_tmem_s.outer: {p_tmem_s.outer}')
print(f'[DIAG] p_tmem_s.inner: {p_tmem_s.inner}')
tOrP_base = pv_thr.make_fragment_A(tP)
tOrP = tOrP_base[(None, None, None, 0)]
tOrP0 = cute.make_tensor(
tOrP.iterator + self.qk_acc_dtype.width // self.q_dtype.width * self.tmem_p0_offset,
tOrP.layout)
# Compute nblk_pv for diagnostics
nblk_pv = cute.size(tOrP0, mode=[2])
nblk_qk = cute.size(tCrA, mode=[2])
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, self.num_acc_stage))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, self.num_acc_stage))
# COMPREHENSIVE LAYOUT DUMP
cS = cute.make_identity_tensor((self.qk_mma_tiler[0], self.qk_mma_tiler[1]))
tScS = qk_thr.partition_C(cS)
tilePlikeFP32 = self.qk_mma_tiler[1] * self.q_dtype.width // 32
tStS_P_layout = cute.composition(tStS.layout, cute.make_layout((128, tilePlikeFP32)))
tStS_P = cute.make_tensor(tStS.iterator + self.tmem_p0_offset, tStS_P_layout)
tScS_P_layout = cute.composition(tScS.layout, cute.make_layout((128, tilePlikeFP32)))
tScS_P = cute.make_tensor(tScS.iterator, tScS_P_layout)
print(f'[LAYOUT] QK C-fragment tStS.layout: {tStS.layout}')
print(f'[LAYOUT] QK C-fragment tStS cosize: {cute.cosize(tStS.layout)}')
print(f'[LAYOUT] QK C-fragment tStS.size: {cute.size(tStS)}')
print(f'[LAYOUT] QK C-fragment tScS.layout: {tScS.layout}')
print(f'[LAYOUT] QK C-fragment tScS cosize: {cute.cosize(tScS.layout)}')
print(f'[LAYOUT] PV A-fragment tOrP.layout: {tOrP.layout}')
print(f'[LAYOUT] PV A-fragment tOrP cosize: {cute.cosize(tOrP.layout)}')
print(f'[LAYOUT] PV A-fragment tOrP.size: {cute.size(tOrP)}')
print(f'[LAYOUT] PV A-fragment tOrP0.layout: {tOrP0.layout}')
print(f'[LAYOUT] PV A-fragment tOrP0 cosize: {cute.cosize(tOrP0.layout)}')
print(f'[LAYOUT] tP.layout: {tP.layout}')
print(f'[LAYOUT] tP cosize: {cute.cosize(tP.layout)}')
print(f'[LAYOUT] tStS_P (composed) layout: {tStS_P.layout}')
print(f'[LAYOUT] tStS_P (composed) cosize: {cute.cosize(tStS_P.layout)}')
print(f'[LAYOUT] tScS_P (composed) layout: {tScS_P.layout}')
print(f'[LAYOUT] tScS_P (composed) cosize: {cute.cosize(tScS_P.layout)}')
print(f'[LAYOUT] tOtO.layout: {tOtO.layout}')
print(f'[LAYOUT] tOtO cosize: {cute.cosize(tOtO.layout)}')
print(f'[LAYOUT] pv_mma_tiler: {self.pv_mma_tiler}')
print(f'[LAYOUT] qk_mma_tiler: {self.qk_mma_tiler}')
print(f'[LAYOUT] tilePlikeFP32: {tilePlikeFP32}')
# DIAGNOSTIC: Compare tP (A-layout) vs tStS_P (composition)
tilePlikeFP32 = self.qk_mma_tiler[1] * self.q_dtype.width // 32
tStS_P_layout = cute.composition(tStS.layout, cute.make_layout((128, tilePlikeFP32)))
tStS_P = cute.make_tensor(tStS.iterator + self.tmem_p0_offset, tStS_P_layout)
print(f'[DIAG] tP.layout: {tP.layout}')
print(f'[DIAG] tP.size: {cute.size(tP)}')
print(f'[DIAG] tP.element_type: {tP.element_type if hasattr(tP, 'element_type') else 'N/A'}')
print(f'[DIAG] tStS_P.layout: {tStS_P.layout}')
print(f'[DIAG] tStS_P.size: {cute.size(tStS_P)}')
print(f'[DIAG] tStS_P.element_type: {tStS_P.element_type if hasattr(tStS_P, 'element_type') else 'N/A'}')
print(f'[DIAG] tilePlikeFP32: {tilePlikeFP32}')
print(f'[DIAG] tP and tStS_P same iterator? {tP.iterator == tStS_P.iterator if hasattr(tP, 'iterator') else 'cant compare'}')
print(f'[DIAG] nblk_pv = {nblk_pv}, nblk_qk = {nblk_qk}')
print(f'[DIAG] tCrV.size = {cute.size(tCrV)}')
print(f'[DIAG] tOrP0.size = {cute.size(tOrP0)}')
pipeline.pipeline_init_wait(cluster_shape_mn=cl_vmnk)
# ── TMA WARP ──
if warp_idx == self.tma_warp_id:
ab_p.reset(); peek = ab_p.try_acquire()
for kt in cutlass.range(k_cnt, unroll=1):
h = ab_p.acquire_and_advance(peek)
cute.copy(tma_a, tAgA[(None,h.count)], tAsA[(None,h.index)], tma_bar_ptr=h.barrier)
cute.copy(tma_b, tBgB[(None,h.count)], tBsB[(None,h.index)], tma_bar_ptr=h.barrier)
peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_p.try_acquire()
ab_p.tail()
# ── MMA WARP ──
if warp_idx == self.mma_warp_id:
tmem.wait_for_alloc()
ab_c.reset(); peek = ab_c.try_wait()
s0_handle = mma_si_prod.acquire_and_advance()
acc_prod_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Producer, self.num_acc_stage)
acc_pipe.producer_acquire(acc_prod_st)
qk_mma.set(tcgen05.Field.ACCUMULATE, False)
for kt in range(k_cnt):
h = ab_c.wait_and_advance(peek)
nblk = cute.size(tCrA, mode=[2])
for kb in cutlass.range(nblk, unroll_full=True):
cute.gemm(qk_mma, tStS0, tCrA[(None,None,kb,h.index)], tCrB[(None,None,kb,h.index)], tStS0)
qk_mma.set(tcgen05.Field.ACCUMULATE, True)
h.release(); peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_c.try_wait()
cute.arch.fence_view_async_tmem_store()
s0_handle.commit()
s0_handle = mma_si_prod.acquire_and_advance()
pv_mma.set(tcgen05.Field.ACCUMULATE, True)
tCrV_s = tCrV[(None, None, None, 0)]
nblk_pv = cute.size(tOrP0, mode=[2])
for kb in cutlass.range(nblk_pv, unroll_full=True):
cute.gemm(pv_mma, tOtO0, tOrP0[(None,None,kb)], tCrV_s[(None,None,kb)], tOtO0)
acc_pipe.producer_commit(acc_prod_st)
acc_prod_st.advance()
acc_pipe.producer_tail(acc_prod_st)
# ── SOFTMAX / EPILOGUE WARPS ──
if warp_idx < self.mma_warp_id:
tmem.allocate(self.num_tmem_alloc_cols)
tmem.wait_for_alloc()
tmem_ptr = tmem.retrieve_ptr(self.qk_acc_dtype)
sfw_idx = tidx % (32 * len(self.epilogue_warp_id))
# ── Identity softmax: C-layout → A-layout transform ──
# 1. LOAD pipeline (reads scores from QK C-layout)
tmem_load_atom = cute.make_copy_atom(
tcgen05.copy.Ld32x32bOp(tcgen05.copy.Repetition(32)), self.qk_acc_dtype)
tiled_tmem_load = tcgen05.make_tmem_copy(tmem_load_atom, tStS0)
thr_load = tiled_tmem_load.get_slice(sfw_idx)
tTMEM_LOADtS = thr_load.partition_S(tStS0)
cS = cute.make_identity_tensor((self.qk_mma_tiler[0], self.qk_mma_tiler[1]))
tScS = qk_thr.partition_C(cS)
tTMEM_LOADcS = thr_load.partition_D(tScS)
# 2. STORE pipeline (A-fragment, BF16 St32x32bOp — no recast)
tmem_store_atom = cute.make_copy_atom(
tcgen05.copy.St32x32bOp(tcgen05.copy.Repetition(8)), self.q_dtype)
tiled_tmem_store = tcgen05.make_tmem_copy(tmem_store_atom, tOrP0)
thr_store = tiled_tmem_store.get_slice(sfw_idx)
tRT_tP = thr_store.partition_D(tOrP0)
cS_store = cute.make_identity_tensor((self.qk_mma_tiler[0], self.qk_mma_tiler[1]))
tAcS = pv_thr.partition_A(cS_store)
tRT_cS = thr_store.partition_S(tAcS)
# 3. Wait for scores
si_handle = mma_si_cons.wait_and_advance()
# 4. Load from C-layout
tTMEM_LOADrS = cute.make_rmem_tensor(tTMEM_LOADcS.shape, self.qk_acc_dtype)
cute.copy(tiled_tmem_load, tTMEM_LOADtS, tTMEM_LOADrS)
cute.arch.fence_view_async_tmem_load()
# 5. Quantize FP32 -> BF16 (backward FMHA pattern)
tRT_rST_bf16 = cute.make_rmem_tensor(tTMEM_LOADrS.shape, self.q_dtype)
frg_cnt = 4
frg_tile = cute.size(tTMEM_LOADrS) // frg_cnt
tTR_rST_frg = cute.logical_divide(tTMEM_LOADrS, cute.make_layout(frg_tile))
tRT_rST_bf16_frg = cute.make_tensor(tRT_rST_bf16.iterator, tTR_rST_frg.layout)
for j in range(frg_cnt):
frg_vec = tTR_rST_frg[None, j].load()
tRT_rST_bf16_frg[None, j].store(frg_vec.to(self.q_dtype))
# 6. Reshape and store to A-fragment TMEM
tRT_rST_reshaped = cute.make_tensor(
tRT_rST_bf16.iterator, cute.make_layout(tRT_cS.shape))
cute.copy(tiled_tmem_store, tRT_rST_reshaped, tRT_tP)
cute.arch.fence_view_async_tmem_store()
# 7. Release back to MMA warp
si_handle.release()
# ── Epilogue ──
tCtO_base = cute.make_tensor(tmem_ptr + self.tmem_o0_offset, tCtO_fake.layout)
acc_cons_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Consumer, self.num_acc_stage)
c_grp = pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id))
c_pipe = pipeline.PipelineTmaStore.create(num_stages=self.num_c_stage, producer_group=c_grp)
acc_cons_st = utils.gemm.sm100.epilogue_tma_store(
self, tidx, warp_idx, tma_c, tCtO_base, sC, tCgC,
epi_tile, 0, const_expr(lambda x: x), (0,0,0), acc_cons_st, acc_pipe, c_pipe)
c_pipe.producer_tail()
tmem.relinquish_alloc_permit()
tmem.free(tmem_ptr)
def test():
torch.manual_seed(42)
m, n, k = 128, 128, 128
q = torch.randn(m, k, 1, dtype=torch.bfloat16, device='cuda')
kv = torch.randn(n, k, 1, dtype=torch.bfloat16, device='cuda')
c = torch.zeros(m, n, 1, dtype=torch.bfloat16, device='cuda')
qf = q[:,:,0].float(); kvf = kv[:,:,0].float()
ref = qf @ kvf.T @ kvf
import cutlass.torch as ct
mQ = ct.from_dlpack(q).mark_layout_dynamic(leading_dim=ct.get_leading_dim(q))
mK = ct.from_dlpack(kv).mark_layout_dynamic(leading_dim=ct.get_leading_dim(kv))
mC = ct.from_dlpack(c).mark_layout_dynamic(leading_dim=ct.get_leading_dim(c))
stream = cuda.CUstream(torch.cuda.current_stream().cuda_stream)
kernel = StageBIdentitySoftmax(mma_tiler_mn=(128, 128), use_2cta_instrs=False, use_tma_store=True)
print('Compiling...', flush=True)
compiled = cute.compile(kernel, mQ, mK, mC, stream)
print('Running...', flush=True)
compiled(mQ, mK, mC, stream)
torch.cuda.synchronize()
out = c[:,:,0].float()
cos = torch.nn.functional.cosine_similarity(out.flatten().unsqueeze(0), ref.flatten().unsqueeze(0)).item()
max_err = (out - ref).abs().max().item()
print('Stage B v7: (Q @ K^T) @ V with identity softmax (computed TMEM offsets)')
print(' Cosine: {:.6f}, Max error: {:.6f}'.format(cos, max_err))
print(' {}'.format('PASS' if cos >= 0.99 else 'FAIL'))
if __name__ == '__main__':
test()

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tests/test_stage_b_v19.py Normal file
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"""
Stage B v7: Two MMAs + Identity Softmax with COMPUTED TMEM offsets.
Key fixes over v6:
- TMEM offsets computed via find_tmem_tensor_col_offset (same API as get_num_tmem_alloc_cols)
- P tensor constructed from p_tmem_s.outer (matching fmha.py pattern exactly)
- tilePlikeFP32 computed from qk_mma_tiler and dtype widths
- tmem_alloc_cols from get_num_tmem_alloc_cols with all fragments
- JIT-time diagnostic prints of all TMEM sizes
Architecture (matches fmha.py exactly):
MMA1: Q @ K^T → tmem_scores (a_source=SMEM, accumulate=False)
Identity softmax: tcgen05.ld C-layout → F32→BF16 → tcgen05.st A-layout
MMA2: P @ V → tmem_output (a_source=TMEM, accumulate=True)
"""
import torch, cutlass, cutlass.cute as cute, cutlass.utils as utils, cutlass.pipeline as pipeline
from cutlass.cute.nvgpu import cpasync, tcgen05
from cutlass import Float32, BFloat16, Int32, Boolean, const_expr
from cutlass.utils import LayoutEnum
from cutlass.utils.tmem_allocator import find_tmem_tensor_col_offset
import cuda.bindings.driver as cuda
class StageBIdentitySoftmax:
def __init__(self, mma_tiler_mn, use_2cta_instrs=False, use_tma_store=True):
self.acc_dtype = Float32; self.qk_acc_dtype = Float32
self.q_dtype = BFloat16; self.o_dtype = BFloat16
self.use_2cta_instrs = use_2cta_instrs; self.use_tma_store = use_tma_store
self.mma_tiler_mn = mma_tiler_mn; self.mma_tiler = (*mma_tiler_mn, 1)
self.cluster_shape_mn = (1, 1)
self.cta_group = tcgen05.CtaGroup.TWO if use_2cta_instrs else tcgen05.CtaGroup.ONE
self.epilogue_warp_id = (0, 1, 2, 3)
self.mma_warp_id = 4; self.tma_warp_id = 5
self.threads_per_cta = 192
self.epilog_sync_bar_id = 1; self.tmem_alloc_sync_bar_id = 2; self.tmem_dealloc_sync_bar_id = 3
self.num_c_stage = 2
def _setup(self, qk_mma, pv_mma):
qk_inst_k = cute.size(qk_mma.shape_mnk, mode=[2])
self.qk_mma_tiler = (*self.mma_tiler_mn, qk_inst_k * 4)
pv_inst_k = cute.size(pv_mma.shape_mnk, mode=[2])
self.pv_mma_tiler = (*self.mma_tiler_mn, pv_inst_k * 4)
self.mma_tiler = self.qk_mma_tiler
print(f"[StageB] qk_mma.shape_mnk = {qk_mma.shape_mnk}")
print(f"[StageB] pv_mma.shape_mnk = {pv_mma.shape_mnk}")
print(f"[StageB] qk_mma_tiler = {self.qk_mma_tiler}")
print(f"[StageB] pv_mma_tiler = {self.pv_mma_tiler}")
print(f"[StageB] qk_inst_k = {qk_inst_k}, pv_inst_k = {pv_inst_k}")
self.cta_tile_shape_mnk = (
self.qk_mma_tiler[0] // cute.size(qk_mma.thr_id.shape),
self.qk_mma_tiler[1],
self.qk_mma_tiler[2],
)
self.cluster_layout_vmnk = cute.tiled_divide(cute.make_layout((1,1,1)), (qk_mma.thr_id.shape,))
self.epi_tile = utils.sm100.compute_epilogue_tile_shape(
self.cta_tile_shape_mnk, self.use_2cta_instrs, self.c_layout, self.o_dtype)
self.num_ab_stage = 1; self.num_acc_stage = 1
self.a_smem_s = utils.sm100.make_smem_layout_a(qk_mma, self.mma_tiler, self.a_dtype, 1)
self.b_smem_s = utils.sm100.make_smem_layout_b(qk_mma, self.mma_tiler, self.b_dtype, 1)
self.v_smem_s = utils.sm100.make_smem_layout_b(pv_mma, self.pv_mma_tiler, self.b_dtype, 1)
self.p_tmem_s = utils.sm100.make_smem_layout_a(pv_mma, self.pv_mma_tiler, self.q_dtype, 1)
self.c_smem_s = utils.sm100.make_smem_layout_epi(self.o_dtype, self.c_layout, self.epi_tile, 2)
# ── COMPUTE TMEM OFFSETS USING find_tmem_tensor_col_offset ──
qk_thr = qk_mma.get_slice(0)
qk_acc_shape = qk_thr.partition_shape_C(self.mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
s_cols = find_tmem_tensor_col_offset(tStS)
pv_thr = pv_mma.get_slice(0)
pv_acc_shape = pv_thr.partition_shape_C(self.mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
o_cols = find_tmem_tensor_col_offset(tOtO)
# tilePlikeFP32 for the store-side composition
self.tilePlikeFP32 = self.qk_mma_tiler[1] * self.q_dtype.width // 32
# ── TMEM LAYOUT (matching fmha.py) ──
# P OVERLAPS S — after softmax, P (A-layout) is written on top of scores (C-layout)
# in the same TMEM region. The A-layout view starts partway through the S region.
# fmha.py: S0=0, P0=32, O0=256 (with S1=128, P1=160 double-buffered)
# The P offset of 32 means the A-layout starts at column 32 within the S region.
# This is because the C-layout and A-layout partition TMEM differently per-thread;
# the first 32 C-layout columns are "dead space" in the A-layout mapping.
#
self.tmem_s0_offset = 0
self.tmem_p0_offset = 32 # Original
self.tmem_o0_offset = s_cols # 128
self.tmem_alloc_cols = s_cols + o_cols # 256
# Also compute via get_num_tmem_alloc_cols for the full allocation
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, 1))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, 1))
self.num_tmem_alloc_cols = utils.get_num_tmem_alloc_cols([tCtS_fake, tCtO_fake], arch="sm_100")
print(f"[StageB] s_cols (QK accumulator) = {s_cols}")
print(f"[StageB] o_cols (PV accumulator) = {o_cols}")
print(f"[StageB] tilePlikeFP32 = {self.tilePlikeFP32}")
print(f"[StageB] tmem_s0_offset = {self.tmem_s0_offset}")
print(f"[StageB] tmem_p0_offset = {self.tmem_p0_offset}")
print(f"[StageB] tmem_o0_offset = {self.tmem_o0_offset}")
print(f"[StageB] tmem_alloc_cols (computed) = {self.tmem_alloc_cols}")
print(f"[StageB] num_tmem_alloc_cols (via utils) = {self.num_tmem_alloc_cols}")
a_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
b_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
self.num_tma_load_bytes = (
cute.size_in_bytes(self.a_dtype, a_smem) + cute.size_in_bytes(self.b_dtype, b_smem)
) * cute.size(qk_mma.thr_id.shape)
@cute.jit
def __call__(self, a: cute.Tensor, b: cute.Tensor, c: cute.Tensor, stream: cuda.CUstream):
self.a_dtype = a.element_type; self.b_dtype = b.element_type; self.c_dtype = c.element_type
self.a_major = LayoutEnum.from_tensor(a).mma_major_mode()
self.b_major = LayoutEnum.from_tensor(b).mma_major_mode()
self.c_layout = LayoutEnum.from_tensor(c)
qk_mma = utils.sm100.make_trivial_tiled_mma(
self.a_dtype, self.b_dtype, self.a_major, self.b_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.SMEM)
pv_mma = utils.sm100.make_trivial_tiled_mma(
self.a_dtype, self.b_dtype, cute.nvgpu.OperandMajorMode.K, self.b_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.TMEM)
# Introspect PV MMA atom
print(f"[ATOM] PV MMA type: {type(pv_mma)}")
print(f"[ATOM] PV MMA op: {pv_mma.op if hasattr(pv_mma, "op") else "no op"}")
print(f"[ATOM] PV MMA trait: {pv_mma._trait if hasattr(pv_mma, "_trait") else "no trait"}")
print(f"[ATOM] PV MMA shape_mnk: {pv_mma.shape_mnk}")
print(f"[ATOM] QK MMA shape_mnk: {qk_mma.shape_mnk}")
# Check a_src
print(f"[ATOM] PV MMA op.a_src: {pv_mma.op.a_src}")
print(f"[ATOM] QK MMA op.a_src: {qk_mma.op.a_src}")
print(f"[ATOM] PV MMA op: {pv_mma.op}")
self._setup(qk_mma, pv_mma)
a_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
b_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
tma_a, tma_ta = cute.nvgpu.make_tiled_tma_atom_A(
utils.sm100.cluster_shape_to_tma_atom_A(self.cluster_shape_mn, qk_mma.thr_id),
a, a_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
tma_b, tma_tb = cute.nvgpu.make_tiled_tma_atom_B(
utils.sm100.cluster_shape_to_tma_atom_B(self.cluster_shape_mn, qk_mma.thr_id),
b, b_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
epi_smem = cute.select(self.c_smem_s, mode=[0, 1])
tma_c, tma_tc = cpasync.make_tiled_tma_atom(cpasync.CopyBulkTensorTileS2GOp(), c, epi_smem, self.epi_tile)
self._kernel(qk_mma, pv_mma, tma_a, tma_ta, tma_b, tma_tb, tma_c, tma_tc,
self.cluster_layout_vmnk, self.a_smem_s, self.b_smem_s, self.v_smem_s, self.p_tmem_s, self.c_smem_s, self.epi_tile
).launch(grid=(1,1,1), block=[self.threads_per_cta,1,1], stream=stream)
@cute.kernel
def _kernel(self, qk_mma, pv_mma, tma_a, mA, tma_b, mB, tma_c, mC, cl_vmnk,
a_smem_s, b_smem_s, v_smem_s, p_tmem_s, c_smem_s, epi_tile):
warp_idx = cute.arch.make_warp_uniform(cute.arch.warp_idx())
tidx, _, _ = cute.arch.thread_idx()
use_2cta = cute.size(qk_mma.thr_id.shape) == 2
if warp_idx == self.tma_warp_id:
cpasync.prefetch_descriptor(tma_a); cpasync.prefetch_descriptor(tma_b); cpasync.prefetch_descriptor(tma_c)
@cute.struct
class SS:
ab_bar: cute.struct.MemRange[cutlass.Int64, self.num_ab_stage * 2]
mma_si_bar: cute.struct.MemRange[cutlass.Int64, 2]
acc_bar: cute.struct.MemRange[cutlass.Int64, self.num_acc_stage * 2]
tmem_dealloc: cutlass.Int64
holding: cutlass.Int32
smem = utils.SmemAllocator(); st = smem.allocate(SS)
ab_p, ab_c = pipeline.PipelineTmaUmma.create(
barrier_storage=st.ab_bar.data_ptr(), num_stages=self.num_ab_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 1),
tx_count=self.num_tma_load_bytes, cta_layout_vmnk=cl_vmnk, defer_sync=True
).make_participants()
mma_si_prod, mma_si_cons = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.mma_si_bar.data_ptr(), num_stages=1,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id)),
cta_layout_vmnk=cl_vmnk, defer_sync=True
).make_participants()
acc_pipe = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.acc_bar.data_ptr(), num_stages=self.num_acc_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(
pipeline.Agent.Thread, len(self.epilogue_warp_id) * (2 if use_2cta else 1)),
cta_layout_vmnk=cl_vmnk, defer_sync=True)
tmem_bar = pipeline.NamedBarrier(barrier_id=self.tmem_alloc_sync_bar_id,
num_threads=32 * len((self.mma_warp_id, *self.epilogue_warp_id)))
tmem = utils.TmemAllocator(st.holding.ptr, barrier_for_retrieve=tmem_bar,
allocator_warp_id=self.epilogue_warp_id[0], is_two_cta=use_2cta,
two_cta_tmem_dealloc_mbar_ptr=st.tmem_dealloc.ptr)
pipeline.pipeline_init_arrive(cluster_shape_mn=cl_vmnk, is_relaxed=True)
sA = smem.allocate_tensor(element_type=self.a_dtype, layout=a_smem_s.outer, byte_alignment=128, swizzle=a_smem_s.inner)
sB = smem.allocate_tensor(element_type=self.b_dtype, layout=b_smem_s.outer, byte_alignment=128, swizzle=b_smem_s.inner)
# V shares the same SMEM as B (same data, different layout for PV MMA)
sV_ptr = cute.recast_ptr(sB.iterator, v_smem_s.inner)
sV = cute.make_tensor(sV_ptr, v_smem_s.outer)
sC = smem.allocate_tensor(element_type=self.o_dtype, layout=c_smem_s.outer, byte_alignment=128, swizzle=c_smem_s.inner)
gA = cute.local_tile(mA, cute.slice_(self.mma_tiler, (None,0,None)), (None,None,None))
gB = cute.local_tile(mB, cute.slice_(self.mma_tiler, (0,None,None)), (None,None,None))
gC = cute.local_tile(mC, cute.slice_(self.mma_tiler, (None,None,0)), (None,None,None))
k_cnt = cute.size(gA, mode=[3])
qk_thr = qk_mma.get_slice(0)
tCgA = qk_thr.partition_A(gA); tCgB = qk_thr.partition_B(gB); tCgC = qk_thr.partition_C(gC)
a_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,0,None,0)).shape)
tAsA, tAgA = cpasync.tma_partition(tma_a, 0, a_lay, cute.group_modes(sA,0,3), cute.group_modes(tCgA,0,3))
b_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,None,0,0)).shape)
tBsB, tBgB = cpasync.tma_partition(tma_b, 0, b_lay, cute.group_modes(sB,0,3), cute.group_modes(tCgB,0,3))
tAgA = tAgA[(None,0,None,0)]; tBgB = tBgB[(None,0,None,0)]
tCrA = qk_mma.make_fragment_A(sA); tCrB = qk_mma.make_fragment_B(sB)
tCrV = pv_mma.make_fragment_B(sV) # V fragment from V SMEM layout
print(f"[DIAG] tCrV.size = {cute.size(tCrV)}")
print(f"[DIAG] tCrA.size = {cute.size(tCrA)}")
print(f"[DIAG] tCrB.size = {cute.size(tCrB)}")
print(f"[DIAG] nblk_qk (tCrA mode 2) = {cute.size(tCrA, mode=[2])}")
# ── TMEM tensors with computed offsets (matching fmha.py pattern) ──
qk_acc_shape = qk_thr.partition_shape_C(self.mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
tStS0 = cute.make_tensor(tStS.iterator + self.tmem_s0_offset, tStS.layout)
pv_thr = pv_mma.get_slice(0)
pv_acc_shape = pv_thr.partition_shape_C(self.mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
tOtO0 = cute.make_tensor(tOtO.iterator + self.tmem_o0_offset, tOtO.layout)
# P fragment: construct from p_tmem_s layout (matching fmha.py exactly)
# fmha.py: tP = cute.make_tensor(tStS.iterator, p_tmem_layout_staged.outer)
# tOrP = pv_thr_mma.make_fragment_A(tP)[None, None, None, 0]
# tOrP0 = cute.make_tensor(tOrP.iterator + dtype_width_ratio * tmem_p0_offset, tOrP.layout)
print(f'[TMEM] p_tmem_s: {p_tmem_s}')
print(f'[TMEM] p_tmem_s.outer: {p_tmem_s.outer}')
print(f'[TMEM] p_tmem_s.inner: {p_tmem_s.inner}')
tP = cute.make_tensor(tStS.iterator, p_tmem_s.outer)
print(f'[DIAG] tStS.layout: {tStS.layout}')
print(f'[DIAG] tStS.size: {cute.size(tStS)}')
print(f'[DIAG] p_tmem_s.outer: {p_tmem_s.outer}')
print(f'[DIAG] p_tmem_s.inner: {p_tmem_s.inner}')
tOrP_base = pv_thr.make_fragment_A(tP)
tOrP = tOrP_base[(None, None, None, 0)]
tOrP0 = cute.make_tensor(
tOrP.iterator + self.qk_acc_dtype.width // self.q_dtype.width * self.tmem_p0_offset,
tOrP.layout)
# Compute nblk_pv for diagnostics
nblk_pv = cute.size(tOrP0, mode=[2])
nblk_qk = cute.size(tCrA, mode=[2])
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, self.num_acc_stage))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, self.num_acc_stage))
# COMPREHENSIVE LAYOUT DUMP
cS = cute.make_identity_tensor((self.qk_mma_tiler[0], self.qk_mma_tiler[1]))
tScS = qk_thr.partition_C(cS)
tilePlikeFP32 = self.qk_mma_tiler[1] * self.q_dtype.width // 32
tStS_P_layout = cute.composition(tStS.layout, cute.make_layout((128, tilePlikeFP32)))
tStS_P = cute.make_tensor(tStS.iterator + self.tmem_p0_offset, tStS_P_layout)
tScS_P_layout = cute.composition(tScS.layout, cute.make_layout((128, tilePlikeFP32)))
tScS_P = cute.make_tensor(tScS.iterator, tScS_P_layout)
print(f'[LAYOUT] QK C-fragment tStS.layout: {tStS.layout}')
print(f'[LAYOUT] QK C-fragment tStS cosize: {cute.cosize(tStS.layout)}')
print(f'[LAYOUT] QK C-fragment tStS.size: {cute.size(tStS)}')
print(f'[LAYOUT] QK C-fragment tScS.layout: {tScS.layout}')
print(f'[LAYOUT] QK C-fragment tScS cosize: {cute.cosize(tScS.layout)}')
print(f'[LAYOUT] PV A-fragment tOrP.layout: {tOrP.layout}')
print(f'[LAYOUT] PV A-fragment tOrP cosize: {cute.cosize(tOrP.layout)}')
print(f'[LAYOUT] PV A-fragment tOrP.size: {cute.size(tOrP)}')
print(f'[LAYOUT] PV A-fragment tOrP0.layout: {tOrP0.layout}')
print(f'[LAYOUT] PV A-fragment tOrP0 cosize: {cute.cosize(tOrP0.layout)}')
print(f'[LAYOUT] tP.layout: {tP.layout}')
print(f'[LAYOUT] tP cosize: {cute.cosize(tP.layout)}')
print(f'[LAYOUT] tStS_P (composed) layout: {tStS_P.layout}')
print(f'[LAYOUT] tStS_P (composed) cosize: {cute.cosize(tStS_P.layout)}')
print(f'[LAYOUT] tScS_P (composed) layout: {tScS_P.layout}')
print(f'[LAYOUT] tScS_P (composed) cosize: {cute.cosize(tScS_P.layout)}')
print(f'[LAYOUT] tOtO.layout: {tOtO.layout}')
print(f'[LAYOUT] tOtO cosize: {cute.cosize(tOtO.layout)}')
print(f'[LAYOUT] pv_mma_tiler: {self.pv_mma_tiler}')
print(f'[LAYOUT] qk_mma_tiler: {self.qk_mma_tiler}')
print(f'[LAYOUT] tilePlikeFP32: {tilePlikeFP32}')
# DIAGNOSTIC: Compare tP (A-layout) vs tStS_P (composition)
tilePlikeFP32 = self.qk_mma_tiler[1] * self.q_dtype.width // 32
tStS_P_layout = cute.composition(tStS.layout, cute.make_layout((128, tilePlikeFP32)))
tStS_P = cute.make_tensor(tStS.iterator + self.tmem_p0_offset, tStS_P_layout)
print(f'[DIAG] tP.layout: {tP.layout}')
print(f'[DIAG] tP.size: {cute.size(tP)}')
print(f'[DIAG] tP.element_type: {tP.element_type if hasattr(tP, 'element_type') else 'N/A'}')
print(f'[DIAG] tStS_P.layout: {tStS_P.layout}')
print(f'[DIAG] tStS_P.size: {cute.size(tStS_P)}')
print(f'[DIAG] tStS_P.element_type: {tStS_P.element_type if hasattr(tStS_P, 'element_type') else 'N/A'}')
print(f'[DIAG] tilePlikeFP32: {tilePlikeFP32}')
print(f'[DIAG] tP and tStS_P same iterator? {tP.iterator == tStS_P.iterator if hasattr(tP, 'iterator') else 'cant compare'}')
print(f'[DIAG] nblk_pv = {nblk_pv}, nblk_qk = {nblk_qk}')
print(f'[DIAG] tCrV.size = {cute.size(tCrV)}')
print(f'[DIAG] tOrP0.size = {cute.size(tOrP0)}')
pipeline.pipeline_init_wait(cluster_shape_mn=cl_vmnk)
# ── TMA WARP ──
if warp_idx == self.tma_warp_id:
ab_p.reset(); peek = ab_p.try_acquire()
for kt in cutlass.range(k_cnt, unroll=1):
h = ab_p.acquire_and_advance(peek)
cute.copy(tma_a, tAgA[(None,h.count)], tAsA[(None,h.index)], tma_bar_ptr=h.barrier)
cute.copy(tma_b, tBgB[(None,h.count)], tBsB[(None,h.index)], tma_bar_ptr=h.barrier)
peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_p.try_acquire()
ab_p.tail()
# ── MMA WARP ──
if warp_idx == self.mma_warp_id:
tmem.wait_for_alloc()
ab_c.reset(); peek = ab_c.try_wait()
s0_handle = mma_si_prod.acquire_and_advance()
acc_prod_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Producer, self.num_acc_stage)
acc_pipe.producer_acquire(acc_prod_st)
qk_mma.set(tcgen05.Field.ACCUMULATE, False)
for kt in range(k_cnt):
h = ab_c.wait_and_advance(peek)
nblk = cute.size(tCrA, mode=[2])
for kb in cutlass.range(nblk, unroll_full=True):
cute.gemm(qk_mma, tStS0, tCrA[(None,None,kb,h.index)], tCrB[(None,None,kb,h.index)], tStS0)
qk_mma.set(tcgen05.Field.ACCUMULATE, True)
h.release(); peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_c.try_wait()
cute.arch.fence_view_async_tmem_store()
s0_handle.commit()
s0_handle = mma_si_prod.acquire_and_advance()
pv_mma.set(tcgen05.Field.ACCUMULATE, True)
tCrV_s = tCrV[(None, None, None, 0)]
nblk_pv = cute.size(tOrP0, mode=[2])
for kb in cutlass.range(nblk_pv, unroll_full=True):
cute.gemm(pv_mma, tOtO0, tOrP0[(None,None,kb)], tCrV_s[(None,None,kb)], tOtO0)
acc_pipe.producer_commit(acc_prod_st)
acc_prod_st.advance()
acc_pipe.producer_tail(acc_prod_st)
# ── SOFTMAX / EPILOGUE WARPS ──
if warp_idx < self.mma_warp_id:
tmem.allocate(self.num_tmem_alloc_cols)
tmem.wait_for_alloc()
tmem_ptr = tmem.retrieve_ptr(self.qk_acc_dtype)
sfw_idx = tidx % (32 * len(self.epilogue_warp_id))
# ── Identity softmax: C-layout → A-layout transform ──
# 1. LOAD pipeline (reads scores from QK C-layout)
tmem_load_atom = cute.make_copy_atom(
tcgen05.copy.Ld32x32bOp(tcgen05.copy.Repetition(32)), self.qk_acc_dtype)
tiled_tmem_load = tcgen05.make_tmem_copy(tmem_load_atom, tStS0)
thr_load = tiled_tmem_load.get_slice(sfw_idx)
tTMEM_LOADtS = thr_load.partition_S(tStS0)
cS = cute.make_identity_tensor((self.qk_mma_tiler[0], self.qk_mma_tiler[1]))
tScS = qk_thr.partition_C(cS)
tTMEM_LOADcS = thr_load.partition_D(tScS)
# 2. STORE pipeline (writes P in A-layout — same as fmha.py softmax_step)
tStS_P_layout = cute.composition(tStS.layout, cute.make_layout((128, self.tilePlikeFP32)))
tStS_P = cute.make_tensor(tStS.iterator + self.tmem_p0_offset, tStS_P_layout)
tmem_store_atom = cute.make_copy_atom(
tcgen05.copy.St32x32bOp(tcgen05.copy.Repetition(32)), self.qk_acc_dtype)
tiled_tmem_store = tcgen05.make_tmem_copy(tmem_store_atom, tStS_P)
thr_store = tiled_tmem_store.get_slice(sfw_idx)
tTMEM_STOREtS_x4 = thr_store.partition_D(tStS_P)
tScS_P_layout = cute.composition(tScS.layout, cute.make_layout((128, self.tilePlikeFP32)))
tScS_P = cute.make_tensor(tScS.iterator, tScS_P_layout)
tTMEM_STOREcS = thr_store.partition_S(tScS_P)
# 3. Wait for scores
si_handle = mma_si_cons.wait_and_advance()
# 4. Load from C-layout
tTMEM_LOADrS = cute.make_rmem_tensor(tTMEM_LOADcS.shape, self.qk_acc_dtype)
cute.copy(tiled_tmem_load, tTMEM_LOADtS, tTMEM_LOADrS)
cute.arch.fence_view_async_tmem_load()
# 5. IDENTITY: F32 → BF16
tTMEM_STORErS_x4 = cute.make_rmem_tensor(tTMEM_STOREcS.shape, self.qk_acc_dtype)
tTMEM_STORErS_x4_e = cute.make_tensor(
cute.recast_ptr(tTMEM_STORErS_x4.iterator, dtype=self.q_dtype),
tTMEM_LOADrS.layout)
s_vec = tTMEM_LOADrS.load()
tTMEM_STORErS_x4_e.store(s_vec.to(self.q_dtype))
# 6. Store into A-layout
cute.copy(tiled_tmem_store, tTMEM_STORErS_x4, tTMEM_STOREtS_x4)
cute.arch.fence_view_async_tmem_store()
# 7. Release back to MMA warp
si_handle.release()
# ── Epilogue ──
tCtO_base = cute.make_tensor(tmem_ptr + self.tmem_o0_offset, tCtO_fake.layout)
acc_cons_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Consumer, self.num_acc_stage)
c_grp = pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id))
c_pipe = pipeline.PipelineTmaStore.create(num_stages=self.num_c_stage, producer_group=c_grp)
acc_cons_st = utils.gemm.sm100.epilogue_tma_store(
self, tidx, warp_idx, tma_c, tCtO_base, sC, tCgC,
epi_tile, 0, const_expr(lambda x: x), (0,0,0), acc_cons_st, acc_pipe, c_pipe)
c_pipe.producer_tail()
tmem.relinquish_alloc_permit()
tmem.free(tmem_ptr)
def test():
torch.manual_seed(42)
m, n, k = 128, 128, 128
q = torch.randn(m, k, 1, dtype=torch.bfloat16, device='cuda')
kv = torch.randn(n, k, 1, dtype=torch.bfloat16, device='cuda')
c = torch.zeros(m, n, 1, dtype=torch.bfloat16, device='cuda')
qf = q[:,:,0].float(); kvf = kv[:,:,0].float()
ref = qf @ kvf.T @ kvf
import cutlass.torch as ct
mQ = ct.from_dlpack(q).mark_layout_dynamic(leading_dim=ct.get_leading_dim(q))
mK = ct.from_dlpack(kv).mark_layout_dynamic(leading_dim=ct.get_leading_dim(kv))
mC = ct.from_dlpack(c).mark_layout_dynamic(leading_dim=ct.get_leading_dim(c))
stream = cuda.CUstream(torch.cuda.current_stream().cuda_stream)
kernel = StageBIdentitySoftmax(mma_tiler_mn=(128, 128), use_2cta_instrs=False, use_tma_store=True)
print('Compiling...', flush=True)
compiled = cute.compile(kernel, mQ, mK, mC, stream)
print('Running...', flush=True)
compiled(mQ, mK, mC, stream)
torch.cuda.synchronize()
out = c[:,:,0].float()
cos = torch.nn.functional.cosine_similarity(out.flatten().unsqueeze(0), ref.flatten().unsqueeze(0)).item()
max_err = (out - ref).abs().max().item()
print('Stage B v7: (Q @ K^T) @ V with identity softmax (computed TMEM offsets)')
print(' Cosine: {:.6f}, Max error: {:.6f}'.format(cos, max_err))
print(' {}'.format('PASS' if cos >= 0.99 else 'FAIL'))
if __name__ == '__main__':
test()

362
tests/test_stage_b_v20.py Normal file
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"""
Stage B v20: FMHA-matching test with head_dim=64, proper V layout.
KEY INSIGHT: The A-fragment ((128,16),1,(4,2)):((65536,1),0,(16,64)) is SEQUENTIAL
when flattened in CuTe order: addr = m*65536 + k0 + 16*k1 + 64*k2 = m*65536 + k.
So the C-fragment composition store aliases the SAME TMEM as the A-fragment read.
Previous -0.02 cosine was caused by V dimension mismatch:
pv_mma_tiler=(128,64,128) expects V with N=64 (head_dim),
but the square 128x128 test had V=K (N=128).
This test: Q=(128,64), K=(128,64), V=(64,128), O=(128,64)
FOOTGUN: St32x32bOp MUST use Float32, NOT BFloat16!
The 16-bit values are packed via recast_ptr view.
St32x32bOp(BFloat16) causes ILLEGAL MEMORY ACCESS.
"""
import torch, cutlass, cutlass.cute as cute, cutlass.utils as utils, cutlass.pipeline as pipeline
from cutlass.cute.nvgpu import cpasync, tcgen05
from cutlass import Float32, BFloat16, Int32, Boolean, const_expr
from cutlass.utils import LayoutEnum
from cutlass.utils.tmem_allocator import find_tmem_tensor_col_offset
import cuda.bindings.driver as cuda
class StageBIdentitySoftmax:
def __init__(self, mma_tiler_mn, use_2cta_instrs=False, use_tma_store=True):
self.acc_dtype = Float32; self.qk_acc_dtype = Float32
self.q_dtype = BFloat16; self.o_dtype = BFloat16
self.use_2cta_instrs = use_2cta_instrs; self.use_tma_store = use_tma_store
self.mma_tiler_mn = mma_tiler_mn; self.mma_tiler = (*mma_tiler_mn, 1)
self.cluster_shape_mn = (1, 1)
self.cta_group = tcgen05.CtaGroup.TWO if use_2cta_instrs else tcgen05.CtaGroup.ONE
self.epilogue_warp_id = (0, 1, 2, 3)
self.mma_warp_id = 4; self.tma_warp_id = 5
self.threads_per_cta = 192
self.epilog_sync_bar_id = 1; self.tmem_alloc_sync_bar_id = 2; self.tmem_dealloc_sync_bar_id = 3
self.num_c_stage = 2
def _setup(self, qk_mma, pv_mma):
qk_inst_k = cute.size(qk_mma.shape_mnk, mode=[2])
self.qk_mma_tiler = (*self.mma_tiler_mn, qk_inst_k * 4)
self.pv_mma_tiler = (self.qk_mma_tiler[0], self.qk_mma_tiler[2], self.qk_mma_tiler[1])
self.mma_tiler = self.qk_mma_tiler
print(f"[v20] qk_mma_tiler = {self.qk_mma_tiler}")
print(f"[v20] pv_mma_tiler = {self.pv_mma_tiler}")
self.cta_tile_shape_mnk = (
self.qk_mma_tiler[0] // cute.size(qk_mma.thr_id.shape),
self.qk_mma_tiler[1],
self.qk_mma_tiler[2],
)
self.cluster_layout_vmnk = cute.tiled_divide(cute.make_layout((1,1,1)), (qk_mma.thr_id.shape,))
self.epi_tile = utils.sm100.compute_epilogue_tile_shape(
self.cta_tile_shape_mnk, self.use_2cta_instrs, self.c_layout, self.o_dtype)
self.num_ab_stage = 1; self.num_acc_stage = 1
self.a_smem_s = utils.sm100.make_smem_layout_a(qk_mma, self.mma_tiler, self.a_dtype, 1)
self.b_smem_s = utils.sm100.make_smem_layout_b(qk_mma, self.mma_tiler, self.b_dtype, 1)
self.v_smem_s = utils.sm100.make_smem_layout_b(pv_mma, self.pv_mma_tiler, self.b_dtype, 1)
self.p_tmem_s = utils.sm100.make_smem_layout_a(pv_mma, self.pv_mma_tiler, self.q_dtype, 1)
self.c_smem_s = utils.sm100.make_smem_layout_epi(self.o_dtype, self.c_layout, self.epi_tile, 2)
qk_thr = qk_mma.get_slice(0)
qk_acc_shape = qk_thr.partition_shape_C(self.mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
s_cols = find_tmem_tensor_col_offset(tStS)
pv_thr = pv_mma.get_slice(0)
pv_acc_shape = pv_thr.partition_shape_C(self.pv_mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
o_cols = find_tmem_tensor_col_offset(tOtO)
self.tilePlikeFP32 = self.qk_mma_tiler[1] // Float32.width * self.o_dtype.width
self.tmem_s0_offset = 0
self.tmem_p0_offset = 32
self.tmem_o0_offset = s_cols
self.tmem_alloc_cols = s_cols + o_cols
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, self.num_acc_stage))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, self.num_acc_stage))
self.num_tmem_alloc_cols = utils.get_num_tmem_alloc_cols([tCtS_fake, tCtO_fake], arch="sm_100")
a_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
b_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
self.num_tma_load_bytes = (
cute.size_in_bytes(self.a_dtype, a_smem) + cute.size_in_bytes(self.b_dtype, b_smem)
) * cute.size(qk_mma.thr_id.shape)
@cute.jit
def __call__(self, a: cute.Tensor, b: cute.Tensor, v: cute.Tensor, c: cute.Tensor, stream: cuda.CUstream):
self.a_dtype = a.element_type; self.b_dtype = b.element_type; self.c_dtype = c.element_type
self.a_major = LayoutEnum.from_tensor(a).mma_major_mode()
self.b_major = LayoutEnum.from_tensor(b).mma_major_mode()
self.c_layout = LayoutEnum.from_tensor(c)
qk_mma = utils.sm100.make_trivial_tiled_mma(
self.a_dtype, self.b_dtype, self.a_major, self.b_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.SMEM)
pv_mma = utils.sm100.make_trivial_tiled_mma(
self.q_dtype, self.b_dtype, cute.nvgpu.OperandMajorMode.K, self.b_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.TMEM)
self._setup(qk_mma, pv_mma)
a_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
b_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
v_smem = cute.slice_(self.v_smem_s, (None, None, None, 0))
tma_a, tma_ta = cute.nvgpu.make_tiled_tma_atom_A(
utils.sm100.cluster_shape_to_tma_atom_A(self.cluster_shape_mn, qk_mma.thr_id),
a, a_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
tma_b, tma_tb = cute.nvgpu.make_tiled_tma_atom_B(
utils.sm100.cluster_shape_to_tma_atom_B(self.cluster_shape_mn, qk_mma.thr_id),
b, b_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
# Separate TMA for V (uses pv_mma_tiler and v_smem layout)
tma_v, tma_tv = cute.nvgpu.make_tiled_tma_atom_B(
utils.sm100.cluster_shape_to_tma_atom_B(self.cluster_shape_mn, pv_mma.thr_id),
v, v_smem, self.pv_mma_tiler, pv_mma, self.cluster_layout_vmnk.shape)
epi_smem = cute.select(self.c_smem_s, mode=[0, 1])
tma_c, tma_tc = cpasync.make_tiled_tma_atom(cpasync.CopyBulkTensorTileS2GOp(), c, epi_smem, self.epi_tile)
self._kernel(qk_mma, pv_mma, tma_a, tma_ta, tma_b, tma_tb, tma_v, tma_tv, tma_c, tma_tc,
self.cluster_layout_vmnk, self.a_smem_s, self.b_smem_s, self.v_smem_s, self.p_tmem_s, self.c_smem_s, self.epi_tile
).launch(grid=(1,1,1), block=[self.threads_per_cta,1,1], stream=stream)
@cute.kernel
def _kernel(self, qk_mma, pv_mma, tma_a, mA, tma_b, mB, tma_v, mV, tma_c, mC, cl_vmnk,
a_smem_s, b_smem_s, v_smem_s, p_tmem_s, c_smem_s, epi_tile):
warp_idx = cute.arch.make_warp_uniform(cute.arch.warp_idx())
tidx, _, _ = cute.arch.thread_idx()
use_2cta = cute.size(qk_mma.thr_id.shape) == 2
if warp_idx == self.tma_warp_id:
cpasync.prefetch_descriptor(tma_a); cpasync.prefetch_descriptor(tma_b); cpasync.prefetch_descriptor(tma_v); cpasync.prefetch_descriptor(tma_c)
@cute.struct
class SS:
ab_bar: cute.struct.MemRange[cutlass.Int64, self.num_ab_stage * 2]
mma_si_bar: cute.struct.MemRange[cutlass.Int64, 2]
acc_bar: cute.struct.MemRange[cutlass.Int64, self.num_acc_stage * 2]
tmem_dealloc: cutlass.Int64
holding: cutlass.Int32
smem = utils.SmemAllocator(); st = smem.allocate(SS)
ab_p, ab_c = pipeline.PipelineTmaUmma.create(
barrier_storage=st.ab_bar.data_ptr(), num_stages=self.num_ab_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 1),
tx_count=self.num_tma_load_bytes, cta_layout_vmnk=cl_vmnk, defer_sync=True
).make_participants()
mma_si_prod, mma_si_cons = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.mma_si_bar.data_ptr(), num_stages=1,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id)),
cta_layout_vmnk=cl_vmnk, defer_sync=True
).make_participants()
acc_pipe = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.acc_bar.data_ptr(), num_stages=self.num_acc_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(
pipeline.Agent.Thread, len(self.epilogue_warp_id) * (2 if use_2cta else 1)),
cta_layout_vmnk=cl_vmnk, defer_sync=True)
tmem_bar = pipeline.NamedBarrier(barrier_id=self.tmem_alloc_sync_bar_id,
num_threads=32 * len((self.mma_warp_id, *self.epilogue_warp_id)))
tmem = utils.TmemAllocator(st.holding.ptr, barrier_for_retrieve=tmem_bar,
allocator_warp_id=self.epilogue_warp_id[0], is_two_cta=use_2cta,
two_cta_tmem_dealloc_mbar_ptr=st.tmem_dealloc.ptr)
pipeline.pipeline_init_arrive(cluster_shape_mn=cl_vmnk, is_relaxed=True)
sA = smem.allocate_tensor(element_type=self.a_dtype, layout=a_smem_s.outer, byte_alignment=128, swizzle=a_smem_s.inner)
sB = smem.allocate_tensor(element_type=self.b_dtype, layout=b_smem_s.outer, byte_alignment=128, swizzle=b_smem_s.inner)
sV = smem.allocate_tensor(element_type=self.b_dtype, layout=v_smem_s.outer, byte_alignment=128, swizzle=v_smem_s.inner)
sC = smem.allocate_tensor(element_type=self.o_dtype, layout=c_smem_s.outer, byte_alignment=128, swizzle=c_smem_s.inner)
gA = cute.local_tile(mA, cute.slice_(self.mma_tiler, (None,0,None)), (None,None,None))
gB = cute.local_tile(mB, cute.slice_(self.mma_tiler, (0,None,None)), (None,None,None))
gC = cute.local_tile(mC, cute.slice_(self.mma_tiler, (None,None,0)), (None,None,None))
k_cnt = cute.size(gA, mode=[3])
qk_thr = qk_mma.get_slice(0)
pv_thr = pv_mma.get_slice(0)
tCgA = qk_thr.partition_A(gA); tCgB = qk_thr.partition_B(gB); tCgC = qk_thr.partition_C(gC)
a_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,0,None,0)).shape)
tAsA, tAgA = cpasync.tma_partition(tma_a, 0, a_lay, cute.group_modes(sA,0,3), cute.group_modes(tCgA,0,3))
b_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,None,0,0)).shape)
tBsB, tBgB = cpasync.tma_partition(tma_b, 0, b_lay, cute.group_modes(sB,0,3), cute.group_modes(tCgB,0,3))
tAgA = tAgA[(None,0,None,0)]; tBgB = tBgB[(None,0,None,0)]
# V partition (from mV with pv_mma_tiler and tma_v)
gV = cute.local_tile(mV, cute.slice_(self.pv_mma_tiler, (0,None,None)), (None,None,None))
tCgV = pv_thr.partition_B(gV)
tVsV, tVgV = cpasync.tma_partition(tma_v, 0, b_lay, cute.group_modes(sV,0,3), cute.group_modes(tCgV,0,3))
tVgV = tVgV[(None,0,None,0)]
tCrA = qk_mma.make_fragment_A(sA); tCrB = qk_mma.make_fragment_B(sB)
tCrV = pv_mma.make_fragment_B(sV)
qk_acc_shape = qk_thr.partition_shape_C(self.mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
tStS0 = cute.make_tensor(tStS.iterator + self.tmem_s0_offset, tStS.layout)
pv_acc_shape = pv_thr.partition_shape_C(self.pv_mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
tOtO0 = cute.make_tensor(tOtO.iterator + self.tmem_o0_offset, tOtO.layout)
tP = cute.make_tensor(tStS.iterator, p_tmem_s.outer)
tOrP_base = pv_thr.make_fragment_A(tP)
tOrP = tOrP_base[(None, None, None, 0)]
tOrP0 = cute.make_tensor(
tOrP.iterator + self.qk_acc_dtype.width // self.q_dtype.width * self.tmem_p0_offset,
tOrP.layout)
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, self.num_acc_stage))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, self.num_acc_stage))
pipeline.pipeline_init_wait(cluster_shape_mn=cl_vmnk)
if warp_idx == self.tma_warp_id:
ab_p.reset(); peek = ab_p.try_acquire()
for kt in cutlass.range(k_cnt, unroll=1):
h = ab_p.acquire_and_advance(peek)
cute.copy(tma_a, tAgA[(None,h.count)], tAsA[(None,h.index)], tma_bar_ptr=h.barrier)
cute.copy(tma_b, tBgB[(None,h.count)], tBsB[(None,h.index)], tma_bar_ptr=h.barrier)
cute.copy(tma_b, tVgV[(None,h.count)], tVsV[(None,h.index)], tma_bar_ptr=h.barrier)
peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_p.try_acquire()
ab_p.tail()
if warp_idx == self.mma_warp_id:
tmem.wait_for_alloc()
ab_c.reset(); peek = ab_c.try_wait()
s0_handle = mma_si_prod.acquire_and_advance()
acc_prod_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Producer, self.num_acc_stage)
acc_pipe.producer_acquire(acc_prod_st)
qk_mma.set(tcgen05.Field.ACCUMULATE, False)
for kt in range(k_cnt):
h = ab_c.wait_and_advance(peek)
nblk = cute.size(tCrA, mode=[2])
for kb in cutlass.range(nblk, unroll_full=True):
cute.gemm(qk_mma, tStS0, tCrA[(None,None,kb,h.index)], tCrB[(None,None,kb,h.index)], tStS0)
qk_mma.set(tcgen05.Field.ACCUMULATE, True)
h.release(); peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_c.try_wait()
cute.arch.fence_view_async_tmem_store()
s0_handle.commit()
s0_handle = mma_si_prod.acquire_and_advance()
pv_mma.set(tcgen05.Field.ACCUMULATE, True)
tCrV_s = tCrV[(None, None, None, 0)]
nblk_pv = cute.size(tOrP0, mode=[2])
for kb in cutlass.range(nblk_pv, unroll_full=True):
cute.gemm(pv_mma, tOtO0, tOrP0[(None,None,kb)], tCrV_s[(None,None,kb)], tOtO0)
acc_pipe.producer_commit(acc_prod_st)
acc_prod_st.advance()
acc_pipe.producer_tail(acc_prod_st)
if warp_idx < self.mma_warp_id:
tmem.allocate(self.tmem_alloc_cols)
tmem.wait_for_alloc()
tmem_ptr = tmem.retrieve_ptr(self.qk_acc_dtype)
sfw_idx = tidx % (32 * len(self.epilogue_warp_id))
# 1. TMEM LOAD (C-fragment, FP32)
tmem_load_atom = cute.make_copy_atom(
tcgen05.copy.Ld32x32bOp(tcgen05.copy.Repetition(32)), self.qk_acc_dtype)
tiled_tmem_load = tcgen05.make_tmem_copy(tmem_load_atom, tStS0)
thr_load = tiled_tmem_load.get_slice(sfw_idx)
tTMEM_LOADtS = thr_load.partition_S(tStS0)
cS = cute.make_identity_tensor((self.qk_mma_tiler[0], self.qk_mma_tiler[1]))
tScS = qk_thr.partition_C(cS)
tTMEM_LOADcS = thr_load.partition_D(tScS)
# 2. TMEM STORE — FOOTGUN: Float32 atom, NOT BFloat16!
tStS_P_layout = cute.composition(tStS.layout, cute.make_layout((128, self.tilePlikeFP32)))
tStS_P = cute.make_tensor(tStS.iterator + self.tmem_p0_offset, tStS_P_layout)
tmem_store_atom = cute.make_copy_atom(
tcgen05.copy.St32x32bOp(tcgen05.copy.Repetition(32)), self.qk_acc_dtype)
tiled_tmem_store = tcgen05.make_tmem_copy(tmem_store_atom, tStS_P)
thr_store = tiled_tmem_store.get_slice(sfw_idx)
tTMEM_STOREtS_x4 = thr_store.partition_D(tStS_P)
tScS_P_layout = cute.composition(tScS.layout, cute.make_layout((128, self.tilePlikeFP32)))
tScS_P = cute.make_tensor(tScS.iterator, tScS_P_layout)
tTMEM_STOREcS = thr_store.partition_S(tScS_P)
si_handle = mma_si_cons.wait_and_advance()
# 4. Load
tTMEM_LOADrS = cute.make_rmem_tensor(tTMEM_LOADcS.shape, self.qk_acc_dtype)
cute.copy(tiled_tmem_load, tTMEM_LOADtS, tTMEM_LOADrS)
# 5. Identity softmax: FP32->BF16 packing (EXACT FMHA pattern)
tTMEM_STORErS_x4 = cute.make_rmem_tensor(tTMEM_STOREcS.shape, self.qk_acc_dtype)
tTMEM_STORErS_x4_e = cute.make_tensor(
cute.recast_ptr(tTMEM_STORErS_x4.iterator, dtype=self.q_dtype),
tTMEM_LOADrS.layout)
frg_cnt = 4
frg_tile = cute.size(tTMEM_LOADrS) // frg_cnt
tTMEM_LOADrS_frg = cute.logical_divide(tTMEM_LOADrS, cute.make_layout(frg_tile))
tTMEM_STORErS_x4_e_frg = cute.logical_divide(
tTMEM_STORErS_x4_e, cute.make_layout(frg_tile))
for j in range(frg_cnt):
s_vec = tTMEM_LOADrS_frg[None, j].load()
tTMEM_STORErS_x4_e_frg[None, j].store(s_vec.to(self.q_dtype))
cute.copy(tiled_tmem_store, tTMEM_STORErS_x4, tTMEM_STOREtS_x4)
cute.arch.fence_view_async_tmem_store()
si_handle.release()
tCtO_base = cute.make_tensor(tmem_ptr + self.tmem_o0_offset, tCtO_fake.layout)
acc_cons_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Consumer, self.num_acc_stage)
c_grp = pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id))
c_pipe = pipeline.TmaStorePipeline.create(num_stages=self.num_c_stage, producer_group=c_grp)
acc_cons_st = utils.gemm.sm100.epilogue_tma_store(
self, tidx, warp_idx, tma_c, tCtO_base, sC, tCgC,
epi_tile, 0, const_expr(lambda x: x), (0,0,0), acc_cons_st, acc_pipe, c_pipe)
c_pipe.producer_tail()
tmem.relinquish_alloc_permit()
tmem.free(tmem_ptr)
def test():
torch.manual_seed(42)
# FMHA-matching dimensions: head_dim=64, seq=128
# Q: (128, 64) K-major, K: (128, 64) K-major
# V: (64, 128) MN-major (transposed!) — FMHA requires v_major_mode=OperandMajorMode.MN
m, n, head_dim = 128, 128, 64
q = torch.randn(m, head_dim, 1, dtype=torch.bfloat16, device='cuda')
kv = torch.randn(n, head_dim, 1, dtype=torch.bfloat16, device='cuda')
v = torch.randn(head_dim, n, 1, dtype=torch.bfloat16, device='cuda') # Transposed!
c = torch.zeros(m, head_dim, 1, dtype=torch.bfloat16, device='cuda')
qf = q[:,:,0].float(); kvf = kv[:,:,0].float(); vf = v[:,:,0].float()
# Q@K^T = (128,128), P@V = (128,64)
ref = qf @ kvf.T @ vf
import cutlass.torch as ct
mQ = ct.from_dlpack(q).mark_layout_dynamic(leading_dim=ct.get_leading_dim(q))
mK = ct.from_dlpack(kv).mark_layout_dynamic(leading_dim=ct.get_leading_dim(kv))
mV = ct.from_dlpack(v).mark_layout_dynamic(leading_dim=ct.get_leading_dim(v))
mC = ct.from_dlpack(c).mark_layout_dynamic(leading_dim=ct.get_leading_dim(c))
stream = cuda.CUstream(torch.cuda.current_stream().cuda_stream)
kernel = StageBIdentitySoftmax(mma_tiler_mn=(128, 128), use_2cta_instrs=False, use_tma_store=True)
print('Compiling...', flush=True)
compiled = cute.compile(kernel, mQ, mK, mV, mC, stream)
print('Running...', flush=True)
compiled(mQ, mK, mV, mC, stream)
torch.cuda.synchronize()
out = c[:,:,0].float()
cos = torch.nn.functional.cosine_similarity(out.flatten().unsqueeze(0), ref.flatten().unsqueeze(0)).item()
max_err = (out - ref).abs().max().item()
print('Stage B v20: FMHA-matching head_dim=64, proper V layout')
print(' Cosine: {:.6f}, Max error: {:.6f}'.format(cos, max_err))
print(' {}'.format('PASS' if cos >= 0.99 else 'FAIL'))
if __name__ == '__main__':
test()

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"""
Stage B v22: Q@K^T → S in TMEM, P@V → O in TMEM (identity softmax = S used as P)
Based on working Stage A v2 pattern. Two MMAs on the MMA warp, no softmax pipeline.
P stays in TMEM between QK and PV — no copy, no packing, just use S directly as P.
Bug 1 fix: V is MN-major, PV MMA uses v_major (OperandMajorMode.MN).
The PV MMA's A-operand (P) comes from TMEM (same as S accumulator).
"""
import torch, cutlass, cutlass.cute as cute, cutlass.utils as utils, cutlass.pipeline as pipeline
from cutlass.cute.nvgpu import cpasync, tcgen05
from cutlass import Float32, BFloat16, Int32, Boolean, const_expr
from cutlass.utils import LayoutEnum
from cutlass.utils.tmem_allocator import find_tmem_tensor_col_offset
import cuda.bindings.driver as cuda
class StageBIdentityKernel:
def __init__(self, mma_tiler_mn, use_2cta_instrs=False, use_tma_store=True):
self.acc_dtype = Float32; self.qk_acc_dtype = Float32
self.q_dtype = BFloat16; self.o_dtype = BFloat16
self.c_dtype = self.o_dtype # alias for epilogue_tma_store
self.use_2cta_instrs = use_2cta_instrs; self.use_tma_store = use_tma_store
self.mma_tiler_mn = mma_tiler_mn; self.mma_tiler = (*mma_tiler_mn, 1)
self.cluster_shape_mn = (1, 1)
self.cta_group = tcgen05.CtaGroup.TWO if use_2cta_instrs else tcgen05.CtaGroup.ONE
self.epilogue_warp_id = (0, 1, 2, 3)
self.mma_warp_id = 4; self.tma_warp_id = 5
self.threads_per_cta = 192
self.epilog_sync_bar_id = 1; self.tmem_alloc_sync_bar_id = 2; self.tmem_dealloc_sync_bar_id = 3
self.num_c_stage = 2
def _setup(self, qk_mma, pv_mma):
qk_inst_k = cute.size(qk_mma.shape_mnk, mode=[2])
self.qk_mma_tiler = (*self.mma_tiler_mn, qk_inst_k * 4)
self.pv_mma_tiler = (self.qk_mma_tiler[0], self.qk_mma_tiler[2], self.qk_mma_tiler[1])
self.mma_tiler = self.qk_mma_tiler
print(f"[v22] qk_mma_tiler = {self.qk_mma_tiler}")
print(f"[v22] pv_mma_tiler = {self.pv_mma_tiler}")
self.cluster_layout_vmnk = cute.tiled_divide(cute.make_layout((1,1,1)), (qk_mma.thr_id.shape,))
self.cta_tile_shape_mnk = (
self.qk_mma_tiler[0] // cute.size(qk_mma.thr_id.shape),
self.qk_mma_tiler[1],
self.qk_mma_tiler[2],
)
self.epi_tile = utils.sm100.compute_epilogue_tile_shape(
self.cta_tile_shape_mnk, self.use_2cta_instrs, self.c_layout, self.o_dtype)
self.num_ab_stage = 1; self.num_acc_stage = 1
self.a_smem_s = utils.sm100.make_smem_layout_a(qk_mma, self.mma_tiler, self.q_dtype, 1)
self.b_smem_s = utils.sm100.make_smem_layout_b(qk_mma, self.mma_tiler, self.b_dtype, 1)
self.v_smem_s = utils.sm100.make_smem_layout_b(pv_mma, self.pv_mma_tiler, self.b_dtype, 1)
self.p_tmem_s = utils.sm100.make_smem_layout_a(pv_mma, self.pv_mma_tiler, self.q_dtype, 1)
self.c_smem_s = utils.sm100.make_smem_layout_epi(self.o_dtype, self.c_layout, self.epi_tile, 2)
qk_thr = qk_mma.get_slice(0)
qk_acc_shape = qk_thr.partition_shape_C(self.qk_mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
s_cols = find_tmem_tensor_col_offset(tStS)
pv_thr = pv_mma.get_slice(0)
pv_acc_shape = pv_thr.partition_shape_C(self.pv_mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
o_cols = find_tmem_tensor_col_offset(tOtO)
self.tmem_s0_offset = 0
self.tmem_o0_offset = s_cols
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, self.num_acc_stage))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, self.num_acc_stage))
self.num_tmem_alloc_cols = utils.get_num_tmem_alloc_cols([tCtS_fake, tCtO_fake], arch="sm_100")
a_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
b_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
v_smem = cute.slice_(self.v_smem_s, (None, None, None, 0))
self.num_tma_load_bytes = (
cute.size_in_bytes(self.q_dtype, a_smem) + cute.size_in_bytes(self.b_dtype, b_smem) + cute.size_in_bytes(self.b_dtype, v_smem)
) * cute.size(qk_mma.thr_id.shape)
@cute.jit
def __call__(self, q: cute.Tensor, k: cute.Tensor, v: cute.Tensor, c: cute.Tensor, stream: cuda.CUstream):
self.q_dtype = q.element_type; self.b_dtype = k.element_type; self.o_dtype = c.element_type; self.c_dtype = self.o_dtype
self.a_major = LayoutEnum.from_tensor(q).mma_major_mode()
self.b_major = LayoutEnum.from_tensor(k).mma_major_mode()
self.v_major = LayoutEnum.from_tensor(v).mma_major_mode()
self.c_layout = LayoutEnum.from_tensor(c)
print(f"[v22] a_major (Q) = {self.a_major}")
print(f"[v22] b_major (K) = {self.b_major}")
print(f"[v22] v_major (V) = {self.v_major}")
qk_mma = utils.sm100.make_trivial_tiled_mma(
self.q_dtype, self.b_dtype, self.a_major, self.b_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.SMEM)
# BUG 1 FIX: PV MMA b_leading_mode = v_major (MN), NOT b_major (K)
pv_mma = utils.sm100.make_trivial_tiled_mma(
self.q_dtype, self.b_dtype, cute.nvgpu.OperandMajorMode.K, self.v_major, # Bug 1 fix
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.TMEM)
self._setup(qk_mma, pv_mma)
q_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
k_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
v_smem = cute.slice_(self.v_smem_s, (None, None, None, 0))
tma_q, tma_tq = cute.nvgpu.make_tiled_tma_atom_A(
utils.sm100.cluster_shape_to_tma_atom_A(self.cluster_shape_mn, qk_mma.thr_id),
q, q_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
tma_k, tma_tk = cute.nvgpu.make_tiled_tma_atom_B(
utils.sm100.cluster_shape_to_tma_atom_B(self.cluster_shape_mn, qk_mma.thr_id),
k, k_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
tma_v, tma_tv = cute.nvgpu.make_tiled_tma_atom_B(
utils.sm100.cluster_shape_to_tma_atom_B(self.cluster_shape_mn, pv_mma.thr_id),
v, v_smem, self.pv_mma_tiler, pv_mma, self.cluster_layout_vmnk.shape)
epi_smem = cute.select(self.c_smem_s, mode=[0, 1])
tma_c, tma_tc = cpasync.make_tiled_tma_atom(cpasync.CopyBulkTensorTileS2GOp(), c, epi_smem, self.epi_tile)
self._kernel(qk_mma, pv_mma, tma_q, tma_tq, tma_k, tma_tk, tma_v, tma_tv,
tma_c, tma_tc, self.cluster_layout_vmnk,
self.a_smem_s, self.b_smem_s, self.v_smem_s, self.p_tmem_s, self.c_smem_s, self.epi_tile
).launch(grid=(1,1,1), block=[self.threads_per_cta,1,1], stream=stream)
@cute.kernel
def _kernel(self, qk_mma, pv_mma, tma_q, mQ, tma_k, mK, tma_v, mV,
tma_c, mC, cl_vmnk, a_smem_s, b_smem_s, v_smem_s, p_tmem_s, c_smem_s, epi_tile):
warp_idx = cute.arch.make_warp_uniform(cute.arch.warp_idx())
tidx, _, _ = cute.arch.thread_idx()
use_2cta = cute.size(qk_mma.thr_id.shape) == 2
if warp_idx == self.tma_warp_id:
cpasync.prefetch_descriptor(tma_q); cpasync.prefetch_descriptor(tma_k)
cpasync.prefetch_descriptor(tma_v); cpasync.prefetch_descriptor(tma_c)
@cute.struct
class SS:
ab_bar: cute.struct.MemRange[cutlass.Int64, self.num_ab_stage * 2]
acc_bar: cute.struct.MemRange[cutlass.Int64, self.num_acc_stage * 2]
tmem_dealloc: cutlass.Int64
holding: cutlass.Int32
smem = utils.SmemAllocator(); st = smem.allocate(SS)
ab_p, ab_c = pipeline.PipelineTmaUmma.create(
barrier_storage=st.ab_bar.data_ptr(), num_stages=self.num_ab_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 1),
tx_count=self.num_tma_load_bytes, cta_layout_vmnk=cl_vmnk, defer_sync=True
).make_participants()
acc_pipe = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.acc_bar.data_ptr(), num_stages=self.num_acc_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(
pipeline.Agent.Thread, len(self.epilogue_warp_id) * (2 if use_2cta else 1)),
cta_layout_vmnk=cl_vmnk, defer_sync=True)
tmem_bar = pipeline.NamedBarrier(barrier_id=self.tmem_alloc_sync_bar_id,
num_threads=32 * len((self.mma_warp_id, *self.epilogue_warp_id)))
tmem = utils.TmemAllocator(st.holding.ptr, barrier_for_retrieve=tmem_bar,
allocator_warp_id=self.epilogue_warp_id[0], is_two_cta=use_2cta,
two_cta_tmem_dealloc_mbar_ptr=st.tmem_dealloc.ptr)
pipeline.pipeline_init_arrive(cluster_shape_mn=cl_vmnk, is_relaxed=True)
sQ = smem.allocate_tensor(element_type=self.q_dtype, layout=a_smem_s.outer, byte_alignment=128, swizzle=a_smem_s.inner)
sK = smem.allocate_tensor(element_type=self.b_dtype, layout=b_smem_s.outer, byte_alignment=128, swizzle=b_smem_s.inner)
sV = smem.allocate_tensor(element_type=self.b_dtype, layout=v_smem_s.outer, byte_alignment=128, swizzle=v_smem_s.inner)
sC = smem.allocate_tensor(element_type=self.o_dtype, layout=c_smem_s.outer, byte_alignment=128, swizzle=c_smem_s.inner)
gQ = cute.local_tile(mQ, cute.slice_(self.qk_mma_tiler, (None,0,None)), (None,None,None))
gK = cute.local_tile(mK, cute.slice_(self.qk_mma_tiler, (0,None,None)), (None,None,None))
gC = cute.local_tile(mC, cute.slice_(self.qk_mma_tiler, (None,None,0)), (None,None,None))
k_cnt = cute.size(gQ, mode=[3])
qk_thr = qk_mma.get_slice(0)
pv_thr = pv_mma.get_slice(0)
tCgQ = qk_thr.partition_A(gQ); tCgK = qk_thr.partition_B(gK); tCgC = qk_thr.partition_C(gC)
a_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,0,None,0)).shape)
tAsQ, tAgQ = cpasync.tma_partition(tma_q, 0, a_lay, cute.group_modes(sQ,0,3), cute.group_modes(tCgQ,0,3))
b_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,None,0,0)).shape)
tBsK, tBgK = cpasync.tma_partition(tma_k, 0, b_lay, cute.group_modes(sK,0,3), cute.group_modes(tCgK,0,3))
tAgQ = tAgQ[(None,0,None,0)]; tBgK = tBgK[(None,0,None,0)]
# V partition — pv_mma with pv_mma_tiler
gV = cute.local_tile(mV, cute.slice_(self.pv_mma_tiler, (0,None,None)), (None,None,None))
tCgV = pv_thr.partition_B(gV)
tVsV, tVgV = cpasync.tma_partition(tma_v, 0, b_lay, cute.group_modes(sV,0,3), cute.group_modes(tCgV,0,3))
tVgV = tVgV[(None,0,None,0)]
tCrQ = qk_mma.make_fragment_A(sQ); tCrK = qk_mma.make_fragment_B(sK)
tCrV = pv_mma.make_fragment_B(sV)
# QK accumulator (S) in TMEM
qk_acc_shape = qk_thr.partition_shape_C(self.qk_mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
tStS0 = cute.make_tensor(tStS.iterator + self.tmem_s0_offset, tStS.layout)
# PV accumulator (O) in TMEM
pv_acc_shape = pv_thr.partition_shape_C(self.pv_mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
tOtO0 = cute.make_tensor(tOtO.iterator + self.tmem_o0_offset, tOtO.layout)
# P tensor for PV MMA A-operand (from TMEM, same as S)
tP = cute.make_tensor(tStS.iterator, p_tmem_s.outer)
tOrP_base = pv_thr.make_fragment_A(tP)
tOrP = tOrP_base[(None, None, None, 0)]
# P is at the same TMEM location as S (identity softmax: no copy/packing)
tOrP0 = tOrP
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, self.num_acc_stage))
pipeline.pipeline_init_wait(cluster_shape_mn=cl_vmnk)
# ═══ TMA LOAD WARP ═══
if warp_idx == self.tma_warp_id:
ab_p.reset(); peek = ab_p.try_acquire()
for kt in cutlass.range(k_cnt, unroll=1):
h = ab_p.acquire_and_advance(peek)
cute.copy(tma_q, tAgQ[(None,h.count)], tAsQ[(None,h.index)], tma_bar_ptr=h.barrier)
cute.copy(tma_k, tBgK[(None,h.count)], tBsK[(None,h.index)], tma_bar_ptr=h.barrier)
cute.copy(tma_v, tVgV[(None,h.count)], tVsV[(None,h.index)], tma_bar_ptr=h.barrier)
peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_p.try_acquire()
ab_p.tail()
# ═══ MMA WARP: QK then PV ═══
if warp_idx == self.mma_warp_id:
tmem.wait_for_alloc()
ab_c.reset(); peek = ab_c.try_wait()
acc_prod_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Producer, self.num_acc_stage)
acc_pipe.producer_acquire(acc_prod_st)
# --- QK MMA: Q @ K^T → S in TMEM ---
qk_mma.set(tcgen05.Field.ACCUMULATE, False)
for kt in range(k_cnt):
h = ab_c.wait_and_advance(peek)
nblk = cute.size(tCrQ, mode=[2])
for kb in cutlass.range(nblk, unroll_full=True):
cute.gemm(qk_mma, tStS0, tCrQ[(None,None,kb,h.index)], tCrK[(None,None,kb,h.index)], tStS0)
qk_mma.set(tcgen05.Field.ACCUMULATE, True)
h.release(); peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_c.try_wait()
cute.arch.fence_view_async_tmem_store()
# --- PV MMA: P @ V → O in TMEM ---
# Identity softmax: P = S (FP32 in TMEM, used directly as A-operand)
pv_mma.set(tcgen05.Field.ACCUMULATE, True)
tCrV_s = tCrV[(None, None, None, 0)]
nblk_pv = cute.size(tOrP0, mode=[2])
for kb in cutlass.range(nblk_pv, unroll_full=True):
cute.gemm(pv_mma, tOtO0, tOrP0[(None,None,kb)], tCrV_s[(None,None,kb)], tOtO0)
acc_pipe.producer_commit(acc_prod_st)
acc_prod_st.advance()
acc_pipe.producer_tail(acc_prod_st)
# ═══ EPILOGUE WARPS ═══
if warp_idx < self.mma_warp_id:
tmem.allocate(self.num_tmem_alloc_cols)
tmem.wait_for_alloc()
tmem_ptr = tmem.retrieve_ptr(self.qk_acc_dtype)
acc_cons_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Consumer, self.num_acc_stage)
c_grp = pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id))
c_pipe = pipeline.PipelineTmaStore.create(num_stages=self.num_c_stage, producer_group=c_grp)
tCtO_base = cute.make_tensor(tmem_ptr + self.tmem_o0_offset, tCtO_fake.layout)
acc_cons_st = utils.gemm.sm100.epilogue_tma_store(
self, tidx, warp_idx, tma_c, tCtO_base, sC, tCgC,
epi_tile, 0, const_expr(lambda x: x), (0,0,0), acc_cons_st, acc_pipe, c_pipe)
c_pipe.producer_tail()
tmem.relinquish_alloc_permit()
tmem.free(tmem_ptr)
def test():
torch.manual_seed(42)
m, n, head_dim = 128, 128, 64
q = torch.randn(m, head_dim, 1, dtype=torch.bfloat16, device='cuda')
k = torch.randn(n, head_dim, 1, dtype=torch.bfloat16, device='cuda')
# V: MN-major — (head_dim, seq) with strides (1, head_dim)
v_base = torch.randn(head_dim, n, dtype=torch.bfloat16, device='cuda')
v = v_base.as_strided((head_dim, n), (1, head_dim)).unsqueeze(-1)
c = torch.zeros(m, head_dim, 1, dtype=torch.bfloat16, device='cuda')
qf = q[:,:,0].float(); kf = k[:,:,0].float(); vf = v_base.float()
# Q@K^T = (128,128), then PV MMA: P(128,128) @ V(64,128) MN-major
# MN-major B-operand means the MMA interprets V as V[k,n] where k is contiguous
# So PV computes: P[m,k] * V[n,k] = O[m,n] = P @ V^T
ref = qf @ kf.T @ vf.T # (128,64)
import cutlass.torch as ct
mQ = ct.from_dlpack(q).mark_layout_dynamic(leading_dim=ct.get_leading_dim(q))
mK = ct.from_dlpack(k).mark_layout_dynamic(leading_dim=ct.get_leading_dim(k))
mV = ct.from_dlpack(v).mark_layout_dynamic(leading_dim=ct.get_leading_dim(v))
mC = ct.from_dlpack(c).mark_layout_dynamic(leading_dim=ct.get_leading_dim(c))
stream = cuda.CUstream(torch.cuda.current_stream().cuda_stream)
kernel = StageBIdentityKernel(mma_tiler_mn=(128, 128), use_2cta_instrs=False, use_tma_store=True)
print('Compiling...', flush=True)
compiled = cute.compile(kernel, mQ, mK, mV, mC, stream)
print('Running...', flush=True)
compiled(mQ, mK, mV, mC, stream)
torch.cuda.synchronize()
out = c[:,:,0].float()
cos = torch.nn.functional.cosine_similarity(out.flatten().unsqueeze(0), ref.flatten().unsqueeze(0)).item()
max_err = (out - ref).abs().max().item()
print('Stage B v22: Q@K^T + P@V (V MN-major, identity softmax)')
print(' Cosine: {:.6f}, Max error: {:.6f}'.format(cos, max_err))
print(' {}'.format('PASS' if cos >= 0.99 else 'FAIL'))
if __name__ == '__main__':
test()

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@@ -0,0 +1,364 @@
"""
Stage B v22: Bug 1 Fix — V B-Operand Must Be MN-Major
Fix over v20: PV MMA uses V's major mode (MN) instead of K's major mode (K).
V is shaped (head_dim, seq) = (64, 128) with strides (1, 64) → OperandMajorMode.MN.
K is shaped (seq, head_dim) = (128, 64) with strides (64, 1) → OperandMajorMode.K.
These are DIFFERENT. The PV MMA's b_leading_mode MUST come from V, not from K.
Also: separate TMA descriptor for V (already in v20), separate SMEM layout for V.
"""
import torch, cutlass, cutlass.cute as cute, cutlass.utils as utils, cutlass.pipeline as pipeline
from cutlass.cute.nvgpu import cpasync, tcgen05
from cutlass import Float32, BFloat16, Int32, Boolean, const_expr
from cutlass.utils import LayoutEnum
from cutlass.utils.tmem_allocator import find_tmem_tensor_col_offset
import cuda.bindings.driver as cuda
class StageBIdentitySoftmax:
def __init__(self, mma_tiler_mn, use_2cta_instrs=False, use_tma_store=True):
self.acc_dtype = Float32; self.qk_acc_dtype = Float32
self.q_dtype = BFloat16; self.o_dtype = BFloat16
self.use_2cta_instrs = use_2cta_instrs; self.use_tma_store = use_tma_store
self.mma_tiler_mn = mma_tiler_mn; self.mma_tiler = (*mma_tiler_mn, 1)
self.cluster_shape_mn = (1, 1)
self.cta_group = tcgen05.CtaGroup.TWO if use_2cta_instrs else tcgen05.CtaGroup.ONE
self.epilogue_warp_id = (0, 1, 2, 3)
self.mma_warp_id = 4; self.tma_warp_id = 5
self.threads_per_cta = 192
self.epilog_sync_bar_id = 1; self.tmem_alloc_sync_bar_id = 2; self.tmem_dealloc_sync_bar_id = 3
self.num_c_stage = 2
def _setup(self, qk_mma, pv_mma):
qk_inst_k = cute.size(qk_mma.shape_mnk, mode=[2])
self.qk_mma_tiler = (*self.mma_tiler_mn, qk_inst_k * 4)
self.pv_mma_tiler = (self.qk_mma_tiler[0], self.qk_mma_tiler[2], self.qk_mma_tiler[1])
self.mma_tiler = self.qk_mma_tiler
print(f"[v22] qk_mma_tiler = {self.qk_mma_tiler}")
print(f"[v22] pv_mma_tiler = {self.pv_mma_tiler}")
self.cta_tile_shape_mnk = (
self.qk_mma_tiler[0] // cute.size(qk_mma.thr_id.shape),
self.qk_mma_tiler[1],
self.qk_mma_tiler[2],
)
self.cluster_layout_vmnk = cute.tiled_divide(cute.make_layout((1,1,1)), (qk_mma.thr_id.shape,))
self.epi_tile = utils.sm100.compute_epilogue_tile_shape(
self.cta_tile_shape_mnk, self.use_2cta_instrs, self.c_layout, self.o_dtype)
self.num_ab_stage = 1; self.num_acc_stage = 1
self.a_smem_s = utils.sm100.make_smem_layout_a(qk_mma, self.mma_tiler, self.a_dtype, 1)
self.b_smem_s = utils.sm100.make_smem_layout_b(qk_mma, self.mma_tiler, self.b_dtype, 1)
# V uses pv_mma with MN-major B — its own SMEM layout
self.v_smem_s = utils.sm100.make_smem_layout_b(pv_mma, self.pv_mma_tiler, self.b_dtype, 1)
self.p_tmem_s = utils.sm100.make_smem_layout_a(pv_mma, self.pv_mma_tiler, self.q_dtype, 1)
self.c_smem_s = utils.sm100.make_smem_layout_epi(self.o_dtype, self.c_layout, self.epi_tile, 2)
qk_thr = qk_mma.get_slice(0)
qk_acc_shape = qk_thr.partition_shape_C(self.mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
s_cols = find_tmem_tensor_col_offset(tStS)
pv_thr = pv_mma.get_slice(0)
pv_acc_shape = pv_thr.partition_shape_C(self.pv_mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
o_cols = find_tmem_tensor_col_offset(tOtO)
self.tilePlikeFP32 = self.qk_mma_tiler[1] // Float32.width * self.o_dtype.width
self.tmem_s0_offset = 0
self.tmem_p0_offset = 32
self.tmem_o0_offset = s_cols
self.tmem_alloc_cols = s_cols + o_cols
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, self.num_acc_stage))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, self.num_acc_stage))
self.num_tmem_alloc_cols = utils.get_num_tmem_alloc_cols([tCtS_fake, tCtO_fake], arch="sm_100")
a_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
b_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
self.num_tma_load_bytes = (
cute.size_in_bytes(self.a_dtype, a_smem) + cute.size_in_bytes(self.b_dtype, b_smem)
) * cute.size(qk_mma.thr_id.shape)
@cute.jit
def __call__(self, a: cute.Tensor, b: cute.Tensor, v: cute.Tensor, c: cute.Tensor, stream: cuda.CUstream):
self.a_dtype = a.element_type; self.b_dtype = b.element_type; self.c_dtype = c.element_type
self.a_major = LayoutEnum.from_tensor(a).mma_major_mode()
self.b_major = LayoutEnum.from_tensor(b).mma_major_mode()
self.v_major = LayoutEnum.from_tensor(v).mma_major_mode() # V's major mode — MN!
self.c_layout = LayoutEnum.from_tensor(c)
print(f"[v22] a_major (Q) = {self.a_major}")
print(f"[v22] b_major (K) = {self.b_major}")
print(f"[v22] v_major (V) = {self.v_major}")
qk_mma = utils.sm100.make_trivial_tiled_mma(
self.a_dtype, self.b_dtype, self.a_major, self.b_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.SMEM)
# BUG 1 FIX: PV MMA uses V's major mode (MN), NOT K's major mode (K)
pv_mma = utils.sm100.make_trivial_tiled_mma(
self.q_dtype, self.b_dtype, cute.nvgpu.OperandMajorMode.K, self.v_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.TMEM)
self._setup(qk_mma, pv_mma)
a_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
b_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
v_smem = cute.slice_(self.v_smem_s, (None, None, None, 0))
tma_a, tma_ta = cute.nvgpu.make_tiled_tma_atom_A(
utils.sm100.cluster_shape_to_tma_atom_A(self.cluster_shape_mn, qk_mma.thr_id),
a, a_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
tma_b, tma_tb = cute.nvgpu.make_tiled_tma_atom_B(
utils.sm100.cluster_shape_to_tma_atom_B(self.cluster_shape_mn, qk_mma.thr_id),
b, b_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
# Separate TMA for V — uses pv_mma and pv_mma_tiler
tma_v, tma_tv = cute.nvgpu.make_tiled_tma_atom_B(
utils.sm100.cluster_shape_to_tma_atom_B(self.cluster_shape_mn, pv_mma.thr_id),
v, v_smem, self.pv_mma_tiler, pv_mma, self.cluster_layout_vmnk.shape)
epi_smem = cute.select(self.c_smem_s, mode=[0, 1])
tma_c, tma_tc = cpasync.make_tiled_tma_atom(cpasync.CopyBulkTensorTileS2GOp(), c, epi_smem, self.epi_tile)
self._kernel(qk_mma, pv_mma, tma_a, tma_ta, tma_b, tma_tb, tma_v, tma_tv, tma_c, tma_tc,
self.cluster_layout_vmnk, self.a_smem_s, self.b_smem_s, self.v_smem_s, self.p_tmem_s, self.c_smem_s, self.epi_tile
).launch(grid=(1,1,1), block=[self.threads_per_cta,1,1], stream=stream)
@cute.kernel
def _kernel(self, qk_mma, pv_mma, tma_a, mA, tma_b, mB, tma_v, mV, tma_c, mC, cl_vmnk,
a_smem_s, b_smem_s, v_smem_s, p_tmem_s, c_smem_s, epi_tile):
warp_idx = cute.arch.make_warp_uniform(cute.arch.warp_idx())
tidx, _, _ = cute.arch.thread_idx()
use_2cta = cute.size(qk_mma.thr_id.shape) == 2
if warp_idx == self.tma_warp_id:
cpasync.prefetch_descriptor(tma_a); cpasync.prefetch_descriptor(tma_b); cpasync.prefetch_descriptor(tma_v); cpasync.prefetch_descriptor(tma_c)
@cute.struct
class SS:
ab_bar: cute.struct.MemRange[cutlass.Int64, self.num_ab_stage * 2]
mma_si_bar: cute.struct.MemRange[cutlass.Int64, 2]
acc_bar: cute.struct.MemRange[cutlass.Int64, self.num_acc_stage * 2]
tmem_dealloc: cutlass.Int64
holding: cutlass.Int32
smem = utils.SmemAllocator(); st = smem.allocate(SS)
ab_p, ab_c = pipeline.PipelineTmaUmma.create(
barrier_storage=st.ab_bar.data_ptr(), num_stages=self.num_ab_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 1),
tx_count=self.num_tma_load_bytes, cta_layout_vmnk=cl_vmnk, defer_sync=True
).make_participants()
mma_si_prod, mma_si_cons = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.mma_si_bar.data_ptr(), num_stages=1,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id)),
cta_layout_vmnk=cl_vmnk, defer_sync=True
).make_participants()
acc_pipe = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.acc_bar.data_ptr(), num_stages=self.num_acc_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(
pipeline.Agent.Thread, len(self.epilogue_warp_id) * (2 if use_2cta else 1)),
cta_layout_vmnk=cl_vmnk, defer_sync=True)
tmem_bar = pipeline.NamedBarrier(barrier_id=self.tmem_alloc_sync_bar_id,
num_threads=32 * len((self.mma_warp_id, *self.epilogue_warp_id)))
tmem = utils.TmemAllocator(st.holding.ptr, barrier_for_retrieve=tmem_bar,
allocator_warp_id=self.epilogue_warp_id[0], is_two_cta=use_2cta,
two_cta_tmem_dealloc_mbar_ptr=st.tmem_dealloc.ptr)
pipeline.pipeline_init_arrive(cluster_shape_mn=cl_vmnk, is_relaxed=True)
sA = smem.allocate_tensor(element_type=self.a_dtype, layout=a_smem_s.outer, byte_alignment=128, swizzle=a_smem_s.inner)
sB = smem.allocate_tensor(element_type=self.b_dtype, layout=b_smem_s.outer, byte_alignment=128, swizzle=b_smem_s.inner)
sV = smem.allocate_tensor(element_type=self.b_dtype, layout=v_smem_s.outer, byte_alignment=128, swizzle=v_smem_s.inner)
sC = smem.allocate_tensor(element_type=self.o_dtype, layout=c_smem_s.outer, byte_alignment=128, swizzle=c_smem_s.inner)
gA = cute.local_tile(mA, cute.slice_(self.mma_tiler, (None,0,None)), (None,None,None))
gB = cute.local_tile(mB, cute.slice_(self.mma_tiler, (0,None,None)), (None,None,None))
gC = cute.local_tile(mC, cute.slice_(self.mma_tiler, (None,None,0)), (None,None,None))
k_cnt = cute.size(gA, mode=[3])
qk_thr = qk_mma.get_slice(0)
pv_thr = pv_mma.get_slice(0)
tCgA = qk_thr.partition_A(gA); tCgB = qk_thr.partition_B(gB); tCgC = qk_thr.partition_C(gC)
a_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,0,None,0)).shape)
tAsA, tAgA = cpasync.tma_partition(tma_a, 0, a_lay, cute.group_modes(sA,0,3), cute.group_modes(tCgA,0,3))
b_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,None,0,0)).shape)
tBsB, tBgB = cpasync.tma_partition(tma_b, 0, b_lay, cute.group_modes(sB,0,3), cute.group_modes(tCgB,0,3))
tAgA = tAgA[(None,0,None,0)]; tBgB = tBgB[(None,0,None,0)]
# V partition — uses pv_mma, pv_mma_tiler, and tma_v
gV = cute.local_tile(mV, cute.slice_(self.pv_mma_tiler, (0,None,None)), (None,None,None))
tCgV = pv_thr.partition_B(gV)
tVsV, tVgV = cpasync.tma_partition(tma_v, 0, b_lay, cute.group_modes(sV,0,3), cute.group_modes(tCgV,0,3))
tVgV = tVgV[(None,0,None,0)]
tCrA = qk_mma.make_fragment_A(sA); tCrB = qk_mma.make_fragment_B(sB)
tCrV = pv_mma.make_fragment_B(sV)
qk_acc_shape = qk_thr.partition_shape_C(self.mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
tStS0 = cute.make_tensor(tStS.iterator + self.tmem_s0_offset, tStS.layout)
pv_acc_shape = pv_thr.partition_shape_C(self.pv_mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
tOtO0 = cute.make_tensor(tOtO.iterator + self.tmem_o0_offset, tOtO.layout)
tP = cute.make_tensor(tStS.iterator, p_tmem_s.outer)
tOrP_base = pv_thr.make_fragment_A(tP)
tOrP = tOrP_base[(None, None, None, 0)]
tOrP0 = cute.make_tensor(
tOrP.iterator + self.qk_acc_dtype.width // self.q_dtype.width * self.tmem_p0_offset,
tOrP.layout)
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, self.num_acc_stage))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, self.num_acc_stage))
pipeline.pipeline_init_wait(cluster_shape_mn=cl_vmnk)
if warp_idx == self.tma_warp_id:
ab_p.reset(); peek = ab_p.try_acquire()
for kt in cutlass.range(k_cnt, unroll=1):
h = ab_p.acquire_and_advance(peek)
cute.copy(tma_a, tAgA[(None,h.count)], tAsA[(None,h.index)], tma_bar_ptr=h.barrier)
cute.copy(tma_b, tBgB[(None,h.count)], tBsB[(None,h.index)], tma_bar_ptr=h.barrier)
cute.copy(tma_v, tVgV[(None,h.count)], tVsV[(None,h.index)], tma_bar_ptr=h.barrier)
peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_p.try_acquire()
ab_p.tail()
if warp_idx == self.mma_warp_id:
tmem.wait_for_alloc()
ab_c.reset(); peek = ab_c.try_wait()
s0_handle = mma_si_prod.acquire_and_advance()
acc_prod_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Producer, self.num_acc_stage)
acc_pipe.producer_acquire(acc_prod_st)
qk_mma.set(tcgen05.Field.ACCUMULATE, False)
for kt in range(k_cnt):
h = ab_c.wait_and_advance(peek)
nblk = cute.size(tCrA, mode=[2])
for kb in cutlass.range(nblk, unroll_full=True):
cute.gemm(qk_mma, tStS0, tCrA[(None,None,kb,h.index)], tCrB[(None,None,kb,h.index)], tStS0)
qk_mma.set(tcgen05.Field.ACCUMULATE, True)
h.release(); peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_c.try_wait()
cute.arch.fence_view_async_tmem_store()
s0_handle.commit()
s0_handle = mma_si_prod.acquire_and_advance()
pv_mma.set(tcgen05.Field.ACCUMULATE, True)
tCrV_s = tCrV[(None, None, None, 0)]
nblk_pv = cute.size(tOrP0, mode=[2])
for kb in cutlass.range(nblk_pv, unroll_full=True):
cute.gemm(pv_mma, tOtO0, tOrP0[(None,None,kb)], tCrV_s[(None,None,kb)], tOtO0)
acc_pipe.producer_commit(acc_prod_st)
acc_prod_st.advance()
acc_pipe.producer_tail(acc_prod_st)
if warp_idx < self.mma_warp_id:
tmem.allocate(self.tmem_alloc_cols)
tmem.wait_for_alloc()
tmem_ptr = tmem.retrieve_ptr(self.qk_acc_dtype)
sfw_idx = tidx % (32 * len(self.epilogue_warp_id))
# 1. TMEM LOAD (C-fragment, FP32)
tmem_load_atom = cute.make_copy_atom(
tcgen05.copy.Ld32x32bOp(tcgen05.copy.Repetition(32)), self.qk_acc_dtype)
tiled_tmem_load = tcgen05.make_tmem_copy(tmem_load_atom, tStS0)
thr_load = tiled_tmem_load.get_slice(sfw_idx)
tTMEM_LOADtS = thr_load.partition_S(tStS0)
cS = cute.make_identity_tensor((self.qk_mma_tiler[0], self.qk_mma_tiler[1]))
tScS = qk_thr.partition_C(cS)
tTMEM_LOADcS = thr_load.partition_D(tScS)
# 2. TMEM STORE — FOOTGUN: Float32 atom, NOT BFloat16!
tStS_P_layout = cute.composition(tStS.layout, cute.make_layout((128, self.tilePlikeFP32)))
tStS_P = cute.make_tensor(tStS.iterator + self.tmem_p0_offset, tStS_P_layout)
tmem_store_atom = cute.make_copy_atom(
tcgen05.copy.St32x32bOp(tcgen05.copy.Repetition(32)), self.qk_acc_dtype)
tiled_tmem_store = tcgen05.make_tmem_copy(tmem_store_atom, tStS_P)
thr_store = tiled_tmem_store.get_slice(sfw_idx)
tTMEM_STOREtS_x4 = thr_store.partition_D(tStS_P)
tScS_P_layout = cute.composition(tScS.layout, cute.make_layout((128, self.tilePlikeFP32)))
tScS_P = cute.make_tensor(tScS.iterator, tScS_P_layout)
tTMEM_STOREcS = thr_store.partition_S(tScS_P)
si_handle = mma_si_cons.wait_and_advance()
# 4. Load
tTMEM_LOADrS = cute.make_rmem_tensor(tTMEM_LOADcS.shape, self.qk_acc_dtype)
cute.copy(tiled_tmem_load, tTMEM_LOADtS, tTMEM_LOADrS)
# 5. Identity softmax: FP32->BF16 packing (EXACT FMHA pattern)
tTMEM_STORErS_x4 = cute.make_rmem_tensor(tTMEM_STOREcS.shape, self.qk_acc_dtype)
tTMEM_STORErS_x4_e = cute.make_tensor(
cute.recast_ptr(tTMEM_STORErS_x4.iterator, dtype=self.q_dtype),
tTMEM_LOADrS.layout)
frg_cnt = 4
frg_tile = cute.size(tTMEM_LOADrS) // frg_cnt
tTMEM_LOADrS_frg = cute.logical_divide(tTMEM_LOADrS, cute.make_layout(frg_tile))
tTMEM_STORErS_x4_e_frg = cute.logical_divide(
tTMEM_STORErS_x4_e, cute.make_layout(frg_tile))
for j in range(frg_cnt):
s_vec = tTMEM_LOADrS_frg[None, j].load()
tTMEM_STORErS_x4_e_frg[None, j].store(s_vec.to(self.q_dtype))
cute.copy(tiled_tmem_store, tTMEM_STORErS_x4, tTMEM_STOREtS_x4)
cute.arch.fence_view_async_tmem_store()
si_handle.release()
tCtO_base = cute.make_tensor(tmem_ptr + self.tmem_o0_offset, tCtO_fake.layout)
acc_cons_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Consumer, self.num_acc_stage)
c_grp = pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id))
c_pipe = pipeline.PipelineTmaStore.create(num_stages=self.num_c_stage, producer_group=c_grp)
acc_cons_st = utils.gemm.sm100.epilogue_tma_store(
self, tidx, warp_idx, tma_c, tCtO_base, sC, tCgC,
epi_tile, 0, const_expr(lambda x: x), (0,0,0), acc_cons_st, acc_pipe, c_pipe)
c_pipe.producer_tail()
tmem.relinquish_alloc_permit()
tmem.free(tmem_ptr)
def test():
torch.manual_seed(42)
# FMHA-matching dimensions: head_dim=64, seq=128
# Q: (128, 64) K-major, K: (128, 64) K-major
# V: (64, 128) MN-major — FMHA requires v_major_mode=OperandMajorMode.MN
m, n, head_dim = 128, 128, 64
q = torch.randn(m, head_dim, 1, dtype=torch.bfloat16, device='cuda')
kv = torch.randn(n, head_dim, 1, dtype=torch.bfloat16, device='cuda')
v_base = torch.randn(head_dim, n, dtype=torch.bfloat16, device='cuda')
v = v_base.as_strided((head_dim, n), (1, head_dim)).unsqueeze(-1) # MN-major: strides (1, 64)
c = torch.zeros(m, head_dim, 1, dtype=torch.bfloat16, device='cuda')
qf = q[:,:,0].float(); kvf = kv[:,:,0].float(); vf = v[:,:,0].float()
# Q@K^T = (128,128), P@V = (128,64)
ref = qf @ kvf.T @ vf.T
import cutlass.torch as ct
mQ = ct.from_dlpack(q).mark_layout_dynamic(leading_dim=ct.get_leading_dim(q))
mK = ct.from_dlpack(kv).mark_layout_dynamic(leading_dim=ct.get_leading_dim(kv))
mV = ct.from_dlpack(v).mark_layout_dynamic(leading_dim=ct.get_leading_dim(v))
mC = ct.from_dlpack(c).mark_layout_dynamic(leading_dim=ct.get_leading_dim(c))
stream = cuda.CUstream(torch.cuda.current_stream().cuda_stream)
kernel = StageBIdentitySoftmax(mma_tiler_mn=(128, 128), use_2cta_instrs=False, use_tma_store=True)
print('Compiling...', flush=True)
compiled = cute.compile(kernel, mQ, mK, mV, mC, stream)
print('Running...', flush=True)
compiled(mQ, mK, mV, mC, stream)
torch.cuda.synchronize()
out = c[:,:,0].float()
cos = torch.nn.functional.cosine_similarity(out.flatten().unsqueeze(0), ref.flatten().unsqueeze(0)).item()
max_err = (out - ref).abs().max().item()
print('Stage B v22: Bug 1 fix — V MN-major')
print(' Cosine: {:.6f}, Max error: {:.6f}'.format(cos, max_err))
print(' {}'.format('PASS' if cos >= 0.99 else 'FAIL'))
if __name__ == '__main__':
test()

364
tests/test_stage_b_v23.py Normal file
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"""
Stage B v23: FMHA-matching test with head_dim=64, proper V layout.
KEY INSIGHT: The A-fragment ((128,16),1,(4,2)):((65536,1),0,(16,64)) is SEQUENTIAL
when flattened in CuTe order: addr = m*65536 + k0 + 16*k1 + 64*k2 = m*65536 + k.
So the C-fragment composition store aliases the SAME TMEM as the A-fragment read.
Previous -0.02 cosine was caused by V dimension mismatch:
pv_mma_tiler=(128,64,128) expects V with N=64 (head_dim),
but the square 128x128 test had V=K (N=128).
This test: Q=(128,64), K=(128,64), V=(64,128), O=(128,64)
FOOTGUN: St32x32bOp MUST use Float32, NOT BFloat16!
The 16-bit values are packed via recast_ptr view.
St32x32bOp(BFloat16) causes ILLEGAL MEMORY ACCESS.
"""
import torch, cutlass, cutlass.cute as cute, cutlass.utils as utils, cutlass.pipeline as pipeline
from cutlass.cute.nvgpu import cpasync, tcgen05
from cutlass import Float32, BFloat16, Int32, Boolean, const_expr
from cutlass.utils import LayoutEnum
from cutlass.utils.tmem_allocator import find_tmem_tensor_col_offset
import cuda.bindings.driver as cuda
class StageBIdentitySoftmax:
def __init__(self, mma_tiler_mn, use_2cta_instrs=False, use_tma_store=True):
self.acc_dtype = Float32; self.qk_acc_dtype = Float32
self.q_dtype = BFloat16; self.o_dtype = BFloat16
self.use_2cta_instrs = use_2cta_instrs; self.use_tma_store = use_tma_store
self.mma_tiler_mn = mma_tiler_mn; self.mma_tiler = (*mma_tiler_mn, 1)
self.cluster_shape_mn = (1, 1)
self.cta_group = tcgen05.CtaGroup.TWO if use_2cta_instrs else tcgen05.CtaGroup.ONE
self.epilogue_warp_id = (0, 1, 2, 3)
self.mma_warp_id = 4; self.tma_warp_id = 5
self.threads_per_cta = 192
self.epilog_sync_bar_id = 1; self.tmem_alloc_sync_bar_id = 2; self.tmem_dealloc_sync_bar_id = 3
self.num_c_stage = 2
def _setup(self, qk_mma, pv_mma):
qk_inst_k = cute.size(qk_mma.shape_mnk, mode=[2])
self.qk_mma_tiler = (*self.mma_tiler_mn, qk_inst_k * 4)
self.pv_mma_tiler = (self.qk_mma_tiler[0], self.qk_mma_tiler[2], self.qk_mma_tiler[1])
self.mma_tiler = self.qk_mma_tiler
print(f"[v23] qk_mma_tiler = {self.qk_mma_tiler}")
print(f"[v23] pv_mma_tiler = {self.pv_mma_tiler}")
self.cta_tile_shape_mnk = (
self.qk_mma_tiler[0] // cute.size(qk_mma.thr_id.shape),
self.qk_mma_tiler[1],
self.qk_mma_tiler[2],
)
self.cluster_layout_vmnk = cute.tiled_divide(cute.make_layout((1,1,1)), (qk_mma.thr_id.shape,))
self.epi_tile = utils.sm100.compute_epilogue_tile_shape(
self.cta_tile_shape_mnk, self.use_2cta_instrs, self.c_layout, self.o_dtype)
self.num_ab_stage = 1; self.num_acc_stage = 1
self.a_smem_s = utils.sm100.make_smem_layout_a(qk_mma, self.mma_tiler, self.a_dtype, 1)
self.b_smem_s = utils.sm100.make_smem_layout_b(qk_mma, self.mma_tiler, self.b_dtype, 1)
self.v_smem_s = utils.sm100.make_smem_layout_b(pv_mma, self.pv_mma_tiler, self.b_dtype, 1)
self.p_tmem_s = utils.sm100.make_smem_layout_a(pv_mma, self.pv_mma_tiler, self.q_dtype, 1)
self.c_smem_s = utils.sm100.make_smem_layout_epi(self.o_dtype, self.c_layout, self.epi_tile, 2)
qk_thr = qk_mma.get_slice(0)
qk_acc_shape = qk_thr.partition_shape_C(self.mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
s_cols = find_tmem_tensor_col_offset(tStS)
pv_thr = pv_mma.get_slice(0)
pv_acc_shape = pv_thr.partition_shape_C(self.pv_mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
o_cols = find_tmem_tensor_col_offset(tOtO)
self.tilePlikeFP32 = self.qk_mma_tiler[1] // Float32.width * self.o_dtype.width
self.tmem_s0_offset = 0
self.tmem_p0_offset = 32
self.tmem_o0_offset = s_cols
self.tmem_alloc_cols = s_cols + o_cols
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, self.num_acc_stage))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, self.num_acc_stage))
self.num_tmem_alloc_cols = utils.get_num_tmem_alloc_cols([tCtS_fake, tCtO_fake], arch="sm_100")
a_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
b_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
self.num_tma_load_bytes = (
cute.size_in_bytes(self.a_dtype, a_smem) + cute.size_in_bytes(self.b_dtype, b_smem)
) * cute.size(qk_mma.thr_id.shape)
@cute.jit
def __call__(self, a: cute.Tensor, b: cute.Tensor, v: cute.Tensor, c: cute.Tensor, stream: cuda.CUstream):
self.a_dtype = a.element_type; self.b_dtype = b.element_type; self.c_dtype = c.element_type
self.a_major = LayoutEnum.from_tensor(a).mma_major_mode()
self.b_major = LayoutEnum.from_tensor(b).mma_major_mode()
self.v_major = LayoutEnum.from_tensor(v).mma_major_mode() # Bug 1: V MN-major
self.c_layout = LayoutEnum.from_tensor(c)
qk_mma = utils.sm100.make_trivial_tiled_mma(
self.a_dtype, self.b_dtype, self.a_major, self.b_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.SMEM)
pv_mma = utils.sm100.make_trivial_tiled_mma(
self.q_dtype, self.b_dtype, cute.nvgpu.OperandMajorMode.K, self.v_major, # Bug 1 fix: V MN-major
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.TMEM)
self._setup(qk_mma, pv_mma)
a_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
b_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
v_smem = cute.slice_(self.v_smem_s, (None, None, None, 0))
tma_a, tma_ta = cute.nvgpu.make_tiled_tma_atom_A(
utils.sm100.cluster_shape_to_tma_atom_A(self.cluster_shape_mn, qk_mma.thr_id),
a, a_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
tma_b, tma_tb = cute.nvgpu.make_tiled_tma_atom_B(
utils.sm100.cluster_shape_to_tma_atom_B(self.cluster_shape_mn, qk_mma.thr_id),
b, b_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
# Separate TMA for V (uses pv_mma_tiler and v_smem layout)
tma_v, tma_tv = cute.nvgpu.make_tiled_tma_atom_B(
utils.sm100.cluster_shape_to_tma_atom_B(self.cluster_shape_mn, pv_mma.thr_id),
v, v_smem, self.pv_mma_tiler, pv_mma, self.cluster_layout_vmnk.shape)
epi_smem = cute.select(self.c_smem_s, mode=[0, 1])
tma_c, tma_tc = cpasync.make_tiled_tma_atom(cpasync.CopyBulkTensorTileS2GOp(), c, epi_smem, self.epi_tile)
self._kernel(qk_mma, pv_mma, tma_a, tma_ta, tma_b, tma_tb, tma_v, tma_tv, tma_c, tma_tc,
self.cluster_layout_vmnk, self.a_smem_s, self.b_smem_s, self.v_smem_s, self.p_tmem_s, self.c_smem_s, self.epi_tile
).launch(grid=(1,1,1), block=[self.threads_per_cta,1,1], stream=stream)
@cute.kernel
def _kernel(self, qk_mma, pv_mma, tma_a, mA, tma_b, mB, tma_v, mV, tma_c, mC, cl_vmnk,
a_smem_s, b_smem_s, v_smem_s, p_tmem_s, c_smem_s, epi_tile):
warp_idx = cute.arch.make_warp_uniform(cute.arch.warp_idx())
tidx, _, _ = cute.arch.thread_idx()
use_2cta = cute.size(qk_mma.thr_id.shape) == 2
if warp_idx == self.tma_warp_id:
cpasync.prefetch_descriptor(tma_a); cpasync.prefetch_descriptor(tma_b); cpasync.prefetch_descriptor(tma_v); cpasync.prefetch_descriptor(tma_c)
@cute.struct
class SS:
ab_bar: cute.struct.MemRange[cutlass.Int64, self.num_ab_stage * 2]
mma_si_bar: cute.struct.MemRange[cutlass.Int64, 2]
acc_bar: cute.struct.MemRange[cutlass.Int64, self.num_acc_stage * 2]
tmem_dealloc: cutlass.Int64
holding: cutlass.Int32
smem = utils.SmemAllocator(); st = smem.allocate(SS)
ab_p, ab_c = pipeline.PipelineTmaUmma.create(
barrier_storage=st.ab_bar.data_ptr(), num_stages=self.num_ab_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 1),
tx_count=self.num_tma_load_bytes, cta_layout_vmnk=cl_vmnk, defer_sync=True
).make_participants()
mma_si_prod, mma_si_cons = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.mma_si_bar.data_ptr(), num_stages=1,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id)),
cta_layout_vmnk=cl_vmnk, defer_sync=True
).make_participants()
acc_pipe = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.acc_bar.data_ptr(), num_stages=self.num_acc_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(
pipeline.Agent.Thread, len(self.epilogue_warp_id) * (2 if use_2cta else 1)),
cta_layout_vmnk=cl_vmnk, defer_sync=True)
tmem_bar = pipeline.NamedBarrier(barrier_id=self.tmem_alloc_sync_bar_id,
num_threads=32 * len((self.mma_warp_id, *self.epilogue_warp_id)))
tmem = utils.TmemAllocator(st.holding.ptr, barrier_for_retrieve=tmem_bar,
allocator_warp_id=self.epilogue_warp_id[0], is_two_cta=use_2cta,
two_cta_tmem_dealloc_mbar_ptr=st.tmem_dealloc.ptr)
pipeline.pipeline_init_arrive(cluster_shape_mn=cl_vmnk, is_relaxed=True)
sA = smem.allocate_tensor(element_type=self.a_dtype, layout=a_smem_s.outer, byte_alignment=128, swizzle=a_smem_s.inner)
sB = smem.allocate_tensor(element_type=self.b_dtype, layout=b_smem_s.outer, byte_alignment=128, swizzle=b_smem_s.inner)
sV = smem.allocate_tensor(element_type=self.b_dtype, layout=v_smem_s.outer, byte_alignment=128, swizzle=v_smem_s.inner)
sC = smem.allocate_tensor(element_type=self.o_dtype, layout=c_smem_s.outer, byte_alignment=128, swizzle=c_smem_s.inner)
gA = cute.local_tile(mA, cute.slice_(self.mma_tiler, (None,0,None)), (None,None,None))
gB = cute.local_tile(mB, cute.slice_(self.mma_tiler, (0,None,None)), (None,None,None))
gC = cute.local_tile(mC, cute.slice_(self.mma_tiler, (None,None,0)), (None,None,None))
k_cnt = cute.size(gA, mode=[3])
qk_thr = qk_mma.get_slice(0)
pv_thr = pv_mma.get_slice(0)
tCgA = qk_thr.partition_A(gA); tCgB = qk_thr.partition_B(gB); tCgC = qk_thr.partition_C(gC)
a_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,0,None,0)).shape)
tAsA, tAgA = cpasync.tma_partition(tma_a, 0, a_lay, cute.group_modes(sA,0,3), cute.group_modes(tCgA,0,3))
b_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,None,0,0)).shape)
tBsB, tBgB = cpasync.tma_partition(tma_b, 0, b_lay, cute.group_modes(sB,0,3), cute.group_modes(tCgB,0,3))
tAgA = tAgA[(None,0,None,0)]; tBgB = tBgB[(None,0,None,0)]
# V partition (from mV with pv_mma_tiler and tma_v)
gV = cute.local_tile(mV, cute.slice_(self.pv_mma_tiler, (0,None,None)), (None,None,None))
tCgV = pv_thr.partition_B(gV)
tVsV, tVgV = cpasync.tma_partition(tma_v, 0, b_lay, cute.group_modes(sV,0,3), cute.group_modes(tCgV,0,3))
tVgV = tVgV[(None,0,None,0)]
tCrA = qk_mma.make_fragment_A(sA); tCrB = qk_mma.make_fragment_B(sB)
tCrV = pv_mma.make_fragment_B(sV)
qk_acc_shape = qk_thr.partition_shape_C(self.mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
tStS0 = cute.make_tensor(tStS.iterator + self.tmem_s0_offset, tStS.layout)
pv_acc_shape = pv_thr.partition_shape_C(self.pv_mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
tOtO0 = cute.make_tensor(tOtO.iterator + self.tmem_o0_offset, tOtO.layout)
tP = cute.make_tensor(tStS.iterator, p_tmem_s.outer)
tOrP_base = pv_thr.make_fragment_A(tP)
tOrP = tOrP_base[(None, None, None, 0)]
tOrP0 = cute.make_tensor(
tOrP.iterator + self.qk_acc_dtype.width // self.q_dtype.width * self.tmem_p0_offset,
tOrP.layout)
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, self.num_acc_stage))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, self.num_acc_stage))
pipeline.pipeline_init_wait(cluster_shape_mn=cl_vmnk)
if warp_idx == self.tma_warp_id:
ab_p.reset(); peek = ab_p.try_acquire()
for kt in cutlass.range(k_cnt, unroll=1):
h = ab_p.acquire_and_advance(peek)
cute.copy(tma_a, tAgA[(None,h.count)], tAsA[(None,h.index)], tma_bar_ptr=h.barrier)
cute.copy(tma_b, tBgB[(None,h.count)], tBsB[(None,h.index)], tma_bar_ptr=h.barrier)
cute.copy(tma_b, tVgV[(None,h.count)], tVsV[(None,h.index)], tma_bar_ptr=h.barrier)
peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_p.try_acquire()
ab_p.tail()
if warp_idx == self.mma_warp_id:
tmem.wait_for_alloc()
ab_c.reset(); peek = ab_c.try_wait()
s0_handle = mma_si_prod.acquire_and_advance()
acc_prod_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Producer, self.num_acc_stage)
acc_pipe.producer_acquire(acc_prod_st)
qk_mma.set(tcgen05.Field.ACCUMULATE, False)
for kt in range(k_cnt):
h = ab_c.wait_and_advance(peek)
nblk = cute.size(tCrA, mode=[2])
for kb in cutlass.range(nblk, unroll_full=True):
cute.gemm(qk_mma, tStS0, tCrA[(None,None,kb,h.index)], tCrB[(None,None,kb,h.index)], tStS0)
qk_mma.set(tcgen05.Field.ACCUMULATE, True)
h.release(); peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_c.try_wait()
cute.arch.fence_view_async_tmem_store()
s0_handle.commit()
s0_handle = mma_si_prod.acquire_and_advance()
pv_mma.set(tcgen05.Field.ACCUMULATE, True)
tCrV_s = tCrV[(None, None, None, 0)]
nblk_pv = cute.size(tOrP0, mode=[2])
for kb in cutlass.range(nblk_pv, unroll_full=True):
cute.gemm(pv_mma, tOtO0, tOrP0[(None,None,kb)], tCrV_s[(None,None,kb)], tOtO0)
acc_pipe.producer_commit(acc_prod_st)
acc_prod_st.advance()
acc_pipe.producer_tail(acc_prod_st)
if warp_idx < self.mma_warp_id:
tmem.allocate(self.tmem_alloc_cols)
tmem.wait_for_alloc()
tmem_ptr = tmem.retrieve_ptr(self.qk_acc_dtype)
sfw_idx = tidx % (32 * len(self.epilogue_warp_id))
# 1. TMEM LOAD (C-fragment, FP32)
tmem_load_atom = cute.make_copy_atom(
tcgen05.copy.Ld32x32bOp(tcgen05.copy.Repetition(32)), self.qk_acc_dtype)
tiled_tmem_load = tcgen05.make_tmem_copy(tmem_load_atom, tStS0)
thr_load = tiled_tmem_load.get_slice(sfw_idx)
tTMEM_LOADtS = thr_load.partition_S(tStS0)
cS = cute.make_identity_tensor((self.qk_mma_tiler[0], self.qk_mma_tiler[1]))
tScS = qk_thr.partition_C(cS)
tTMEM_LOADcS = thr_load.partition_D(tScS)
# 2. TMEM STORE — FOOTGUN: Float32 atom, NOT BFloat16!
tStS_P_layout = cute.composition(tStS.layout, cute.make_layout((128, self.tilePlikeFP32)))
tStS_P = cute.make_tensor(tStS.iterator + self.tmem_p0_offset, tStS_P_layout)
tmem_store_atom = cute.make_copy_atom(
tcgen05.copy.St32x32bOp(tcgen05.copy.Repetition(32)), self.qk_acc_dtype)
tiled_tmem_store = tcgen05.make_tmem_copy(tmem_store_atom, tStS_P)
thr_store = tiled_tmem_store.get_slice(sfw_idx)
tTMEM_STOREtS_x4 = thr_store.partition_D(tStS_P)
tScS_P_layout = cute.composition(tScS.layout, cute.make_layout((128, self.tilePlikeFP32)))
tScS_P = cute.make_tensor(tScS.iterator, tScS_P_layout)
tTMEM_STOREcS = thr_store.partition_S(tScS_P)
si_handle = mma_si_cons.wait_and_advance()
# 4. Load
tTMEM_LOADrS = cute.make_rmem_tensor(tTMEM_LOADcS.shape, self.qk_acc_dtype)
cute.copy(tiled_tmem_load, tTMEM_LOADtS, tTMEM_LOADrS)
# 5. Identity softmax: FP32->BF16 packing (EXACT FMHA pattern)
tTMEM_STORErS_x4 = cute.make_rmem_tensor(tTMEM_STOREcS.shape, self.qk_acc_dtype)
tTMEM_STORErS_x4_e = cute.make_tensor(
cute.recast_ptr(tTMEM_STORErS_x4.iterator, dtype=self.q_dtype),
tTMEM_LOADrS.layout)
frg_cnt = 4
frg_tile = cute.size(tTMEM_LOADrS) // frg_cnt
tTMEM_LOADrS_frg = cute.logical_divide(tTMEM_LOADrS, cute.make_layout(frg_tile))
tTMEM_STORErS_x4_e_frg = cute.logical_divide(
tTMEM_STORErS_x4_e, cute.make_layout(frg_tile))
for j in range(frg_cnt):
s_vec = tTMEM_LOADrS_frg[None, j].load()
tTMEM_STORErS_x4_e_frg[None, j].store(s_vec.to(self.q_dtype))
cute.copy(tiled_tmem_store, tTMEM_STORErS_x4, tTMEM_STOREtS_x4)
cute.arch.fence_view_async_tmem_store()
si_handle.release()
tCtO_base = cute.make_tensor(tmem_ptr + self.tmem_o0_offset, tCtO_fake.layout)
acc_cons_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Consumer, self.num_acc_stage)
c_grp = pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id))
c_pipe = pipeline.PipelineTmaStore.create(num_stages=self.num_c_stage, producer_group=c_grp)
acc_cons_st = utils.gemm.sm100.epilogue_tma_store(
self, tidx, warp_idx, tma_c, tCtO_base, sC, tCgC,
epi_tile, 0, const_expr(lambda x: x), (0,0,0), acc_cons_st, acc_pipe, c_pipe)
c_pipe.producer_tail()
tmem.relinquish_alloc_permit()
tmem.free(tmem_ptr)
def test():
torch.manual_seed(42)
# FMHA-matching dimensions: head_dim=64, seq=128
# Q: (128, 64) K-major, K: (128, 64) K-major
# V: (64, 128) MN-major (transposed!) — FMHA requires v_major_mode=OperandMajorMode.MN
m, n, head_dim = 128, 128, 64
q = torch.randn(m, head_dim, 1, dtype=torch.bfloat16, device='cuda')
kv = torch.randn(n, head_dim, 1, dtype=torch.bfloat16, device='cuda')
v_base = torch.randn(head_dim, n, dtype=torch.bfloat16, device='cuda')
v = v_base.as_strided((head_dim, n), (1, head_dim)).unsqueeze(-1) # MN-major: strides (1, 64)
c = torch.zeros(m, head_dim, 1, dtype=torch.bfloat16, device='cuda')
qf = q[:,:,0].float(); kvf = kv[:,:,0].float(); vf = v_base.float()
# Q@K^T = (128,128), P@V = (128,64)
ref = qf @ kvf.T @ vf.T # P@V with V MN-major = Q@K^T @ V^T
import cutlass.torch as ct
mQ = ct.from_dlpack(q).mark_layout_dynamic(leading_dim=ct.get_leading_dim(q))
mK = ct.from_dlpack(kv).mark_layout_dynamic(leading_dim=ct.get_leading_dim(kv))
mV = ct.from_dlpack(v).mark_layout_dynamic(leading_dim=ct.get_leading_dim(v))
mC = ct.from_dlpack(c).mark_layout_dynamic(leading_dim=ct.get_leading_dim(c))
stream = cuda.CUstream(torch.cuda.current_stream().cuda_stream)
kernel = StageBIdentitySoftmax(mma_tiler_mn=(128, 128), use_2cta_instrs=False, use_tma_store=True)
print('Compiling...', flush=True)
compiled = cute.compile(kernel, mQ, mK, mV, mC, stream)
print('Running...', flush=True)
compiled(mQ, mK, mV, mC, stream)
torch.cuda.synchronize()
out = c[:,:,0].float()
cos = torch.nn.functional.cosine_similarity(out.flatten().unsqueeze(0), ref.flatten().unsqueeze(0)).item()
max_err = (out - ref).abs().max().item()
print('Stage B v23: FMHA-matching head_dim=64, proper V layout')
print(' Cosine: {:.6f}, Max error: {:.6f}'.format(cos, max_err))
print(' {}'.format('PASS' if cos >= 0.99 else 'FAIL'))
if __name__ == '__main__':
test()

377
tests/test_stage_b_v24.py Normal file
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"""
Stage B v24: Q@K^T + identity softmax P packing + P@V
Bug 1 fix: V MN-major
Bug 2 fix: FP32->BF16 P packing (C-fragment composition store)
Pipeline fix: Use NamedBarrier instead of PipelineUmmaAsync for mma_si sync
"""
import torch, cutlass, cutlass.cute as cute, cutlass.utils as utils, cutlass.pipeline as pipeline
from cutlass.cute.nvgpu import cpasync, tcgen05
from cutlass import Float32, BFloat16, Int32, Boolean, const_expr
from cutlass.utils import LayoutEnum
from cutlass.utils.tmem_allocator import find_tmem_tensor_col_offset
import cuda.bindings.driver as cuda
class StageBIdentityKernel:
def __init__(self, mma_tiler_mn, use_2cta_instrs=False, use_tma_store=True):
self.acc_dtype = Float32; self.qk_acc_dtype = Float32
self.q_dtype = BFloat16; self.o_dtype = BFloat16; self.c_dtype = BFloat16
self.use_2cta_instrs = use_2cta_instrs; self.use_tma_store = use_tma_store
self.mma_tiler_mn = mma_tiler_mn; self.mma_tiler = (*mma_tiler_mn, 1)
self.cluster_shape_mn = (1, 1)
self.cta_group = tcgen05.CtaGroup.TWO if use_2cta_instrs else tcgen05.CtaGroup.ONE
self.epilogue_warp_id = (0, 1, 2, 3)
self.mma_warp_id = 4; self.tma_warp_id = 5
self.threads_per_cta = 192
self.epilog_sync_bar_id = 1; self.tmem_alloc_sync_bar_id = 2; self.tmem_dealloc_sync_bar_id = 3
self.num_c_stage = 2
# Named barrier IDs for mma_si coordination
self.scores_ready_bar_id = 4 # MMA warp signals S ready
self.softmax_done_bar_id = 5 # Epilogue warps signal softmax done
def _setup(self, qk_mma, pv_mma):
qk_inst_k = cute.size(qk_mma.shape_mnk, mode=[2])
self.qk_mma_tiler = (*self.mma_tiler_mn, qk_inst_k * 4)
self.pv_mma_tiler = (self.qk_mma_tiler[0], self.qk_mma_tiler[2], self.qk_mma_tiler[1])
self.mma_tiler = self.qk_mma_tiler
print(f"[v24] qk_mma_tiler = {self.qk_mma_tiler}")
print(f"[v24] pv_mma_tiler = {self.pv_mma_tiler}")
self.cta_tile_shape_mnk = (
self.qk_mma_tiler[0] // cute.size(qk_mma.thr_id.shape),
self.qk_mma_tiler[1],
self.qk_mma_tiler[2],
)
self.cluster_layout_vmnk = cute.tiled_divide(cute.make_layout((1,1,1)), (qk_mma.thr_id.shape,))
self.epi_tile = utils.sm100.compute_epilogue_tile_shape(
self.cta_tile_shape_mnk, self.use_2cta_instrs, self.c_layout, self.o_dtype)
self.num_ab_stage = 1; self.num_acc_stage = 1
self.a_smem_s = utils.sm100.make_smem_layout_a(qk_mma, self.mma_tiler, self.q_dtype, 1)
self.b_smem_s = utils.sm100.make_smem_layout_b(qk_mma, self.mma_tiler, self.b_dtype, 1)
self.v_smem_s = utils.sm100.make_smem_layout_b(pv_mma, self.pv_mma_tiler, self.b_dtype, 1)
self.p_tmem_s = utils.sm100.make_smem_layout_a(pv_mma, self.pv_mma_tiler, self.q_dtype, 1)
self.c_smem_s = utils.sm100.make_smem_layout_epi(self.o_dtype, self.c_layout, self.epi_tile, 2)
qk_thr = qk_mma.get_slice(0)
qk_acc_shape = qk_thr.partition_shape_C(self.qk_mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
s_cols = find_tmem_tensor_col_offset(tStS)
pv_thr = pv_mma.get_slice(0)
pv_acc_shape = pv_thr.partition_shape_C(self.pv_mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
o_cols = find_tmem_tensor_col_offset(tOtO)
self.tilePlikeFP32 = self.qk_mma_tiler[1] // Float32.width * self.o_dtype.width
self.tmem_s0_offset = 0
self.tmem_p0_offset = 32 # P region in TMEM (for BF16 packing)
self.tmem_o0_offset = s_cols
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, self.num_acc_stage))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, self.num_acc_stage))
self.num_tmem_alloc_cols = utils.get_num_tmem_alloc_cols([tCtS_fake, tCtO_fake], arch="sm_100")
a_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
b_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
self.num_tma_load_bytes = (
cute.size_in_bytes(self.q_dtype, a_smem) + cute.size_in_bytes(self.b_dtype, b_smem)
) * cute.size(qk_mma.thr_id.shape)
@cute.jit
def __call__(self, q: cute.Tensor, k: cute.Tensor, v: cute.Tensor, c: cute.Tensor, stream: cuda.CUstream):
self.q_dtype = q.element_type; self.b_dtype = k.element_type
self.o_dtype = c.element_type; self.c_dtype = self.o_dtype
self.a_major = LayoutEnum.from_tensor(q).mma_major_mode()
self.b_major = LayoutEnum.from_tensor(k).mma_major_mode()
self.v_major = LayoutEnum.from_tensor(v).mma_major_mode()
self.c_layout = LayoutEnum.from_tensor(c)
print(f"[v24] a_major (Q) = {self.a_major}")
print(f"[v24] b_major (K) = {self.b_major}")
print(f"[v24] v_major (V) = {self.v_major}")
qk_mma = utils.sm100.make_trivial_tiled_mma(
self.q_dtype, self.b_dtype, self.a_major, self.b_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.SMEM)
pv_mma = utils.sm100.make_trivial_tiled_mma(
self.q_dtype, self.b_dtype, cute.nvgpu.OperandMajorMode.K, self.v_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.TMEM)
self._setup(qk_mma, pv_mma)
q_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
k_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
v_smem = cute.slice_(self.v_smem_s, (None, None, None, 0))
tma_q, tma_tq = cute.nvgpu.make_tiled_tma_atom_A(
utils.sm100.cluster_shape_to_tma_atom_A(self.cluster_shape_mn, qk_mma.thr_id),
q, q_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
tma_k, tma_tk = cute.nvgpu.make_tiled_tma_atom_B(
utils.sm100.cluster_shape_to_tma_atom_B(self.cluster_shape_mn, qk_mma.thr_id),
k, k_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
tma_v, tma_tv = cute.nvgpu.make_tiled_tma_atom_B(
utils.sm100.cluster_shape_to_tma_atom_B(self.cluster_shape_mn, pv_mma.thr_id),
v, v_smem, self.pv_mma_tiler, pv_mma, self.cluster_layout_vmnk.shape)
epi_smem = cute.select(self.c_smem_s, mode=[0, 1])
tma_c, tma_tc = cpasync.make_tiled_tma_atom(cpasync.CopyBulkTensorTileS2GOp(), c, epi_smem, self.epi_tile)
self._kernel(qk_mma, pv_mma, tma_q, tma_tq, tma_k, tma_tk, tma_v, tma_tv,
tma_c, tma_tc, self.cluster_layout_vmnk,
self.a_smem_s, self.b_smem_s, self.v_smem_s, self.p_tmem_s, self.c_smem_s, self.epi_tile
).launch(grid=(1,1,1), block=[self.threads_per_cta,1,1], stream=stream)
@cute.kernel
def _kernel(self, qk_mma, pv_mma, tma_q, mQ, tma_k, mK, tma_v, mV,
tma_c, mC, cl_vmnk, a_smem_s, b_smem_s, v_smem_s, p_tmem_s, c_smem_s, epi_tile):
warp_idx = cute.arch.make_warp_uniform(cute.arch.warp_idx())
tidx, _, _ = cute.arch.thread_idx()
use_2cta = cute.size(qk_mma.thr_id.shape) == 2
if warp_idx == self.tma_warp_id:
cpasync.prefetch_descriptor(tma_q); cpasync.prefetch_descriptor(tma_k)
cpasync.prefetch_descriptor(tma_v); cpasync.prefetch_descriptor(tma_c)
@cute.struct
class SS:
ab_bar: cute.struct.MemRange[cutlass.Int64, self.num_ab_stage * 2]
acc_bar: cute.struct.MemRange[cutlass.Int64, self.num_acc_stage * 2]
tmem_dealloc: cutlass.Int64
holding: cutlass.Int32
smem = utils.SmemAllocator(); st = smem.allocate(SS)
ab_p, ab_c = pipeline.PipelineTmaUmma.create(
barrier_storage=st.ab_bar.data_ptr(), num_stages=self.num_ab_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 1),
tx_count=self.num_tma_load_bytes, cta_layout_vmnk=cl_vmnk, defer_sync=True
).make_participants()
acc_pipe = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.acc_bar.data_ptr(), num_stages=self.num_acc_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(
pipeline.Agent.Thread, len(self.epilogue_warp_id) * (2 if use_2cta else 1)),
cta_layout_vmnk=cl_vmnk, defer_sync=True)
tmem_bar = pipeline.NamedBarrier(barrier_id=self.tmem_alloc_sync_bar_id,
num_threads=32 * len((self.mma_warp_id, *self.epilogue_warp_id)))
tmem = utils.TmemAllocator(st.holding.ptr, barrier_for_retrieve=tmem_bar,
allocator_warp_id=self.epilogue_warp_id[0], is_two_cta=use_2cta,
two_cta_tmem_dealloc_mbar_ptr=st.tmem_dealloc.ptr)
# Named barriers for MMA ↔ softmax coordination
scores_ready_bar = pipeline.NamedBarrier(
barrier_id=self.scores_ready_bar_id,
num_threads=32 * (1 + len(self.epilogue_warp_id))) # MMA warp + epilogue warps
softmax_done_bar = pipeline.NamedBarrier(
barrier_id=self.softmax_done_bar_id,
num_threads=32 * (1 + len(self.epilogue_warp_id))) # MMA warp + epilogue warps
pipeline.pipeline_init_arrive(cluster_shape_mn=cl_vmnk, is_relaxed=True)
sQ = smem.allocate_tensor(element_type=self.q_dtype, layout=a_smem_s.outer, byte_alignment=128, swizzle=a_smem_s.inner)
sK = smem.allocate_tensor(element_type=self.b_dtype, layout=b_smem_s.outer, byte_alignment=128, swizzle=b_smem_s.inner)
sV = smem.allocate_tensor(element_type=self.b_dtype, layout=v_smem_s.outer, byte_alignment=128, swizzle=v_smem_s.inner)
sC = smem.allocate_tensor(element_type=self.o_dtype, layout=c_smem_s.outer, byte_alignment=128, swizzle=c_smem_s.inner)
gQ = cute.local_tile(mQ, cute.slice_(self.qk_mma_tiler, (None,0,None)), (None,None,None))
gK = cute.local_tile(mK, cute.slice_(self.qk_mma_tiler, (0,None,None)), (None,None,None))
gC = cute.local_tile(mC, cute.slice_(self.qk_mma_tiler, (None,None,0)), (None,None,None))
k_cnt = cute.size(gQ, mode=[3])
qk_thr = qk_mma.get_slice(0)
pv_thr = pv_mma.get_slice(0)
tCgQ = qk_thr.partition_A(gQ); tCgK = qk_thr.partition_B(gK); tCgC = qk_thr.partition_C(gC)
a_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,0,None,0)).shape)
tAsQ, tAgQ = cpasync.tma_partition(tma_q, 0, a_lay, cute.group_modes(sQ,0,3), cute.group_modes(tCgQ,0,3))
b_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,None,0,0)).shape)
tBsK, tBgK = cpasync.tma_partition(tma_k, 0, b_lay, cute.group_modes(sK,0,3), cute.group_modes(tCgK,0,3))
tAgQ = tAgQ[(None,0,None,0)]; tBgK = tBgK[(None,0,None,0)]
gV = cute.local_tile(mV, cute.slice_(self.pv_mma_tiler, (0,None,None)), (None,None,None))
tCgV = pv_thr.partition_B(gV)
tVsV, tVgV = cpasync.tma_partition(tma_v, 0, b_lay, cute.group_modes(sV,0,3), cute.group_modes(tCgV,0,3))
tVgV = tVgV[(None,0,None,0)]
tCrQ = qk_mma.make_fragment_A(sQ); tCrK = qk_mma.make_fragment_B(sK)
tCrV = pv_mma.make_fragment_B(sV)
qk_acc_shape = qk_thr.partition_shape_C(self.qk_mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
tStS0 = cute.make_tensor(tStS.iterator + self.tmem_s0_offset, tStS.layout)
pv_acc_shape = pv_thr.partition_shape_C(self.pv_mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
tOtO0 = cute.make_tensor(tOtO.iterator + self.tmem_o0_offset, tOtO.layout)
# P from TMEM — at tmem_p0_offset, read by PV MMA as A-operand
tP = cute.make_tensor(tStS.iterator, p_tmem_s.outer)
tOrP_base = pv_thr.make_fragment_A(tP)
tOrP = tOrP_base[(None, None, None, 0)]
tOrP0 = cute.make_tensor(
tOrP.iterator + self.qk_acc_dtype.width // self.q_dtype.width * self.tmem_p0_offset,
tOrP.layout)
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, self.num_acc_stage))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, self.num_acc_stage))
pipeline.pipeline_init_wait(cluster_shape_mn=cl_vmnk)
# ═══ TMA LOAD WARP ═══
if warp_idx == self.tma_warp_id:
tmem.wait_for_alloc()
ab_p.reset(); peek = ab_p.try_acquire()
for kt in cutlass.range(k_cnt, unroll=1):
h = ab_p.acquire_and_advance(peek)
cute.copy(tma_q, tAgQ[(None,h.count)], tAsQ[(None,h.index)], tma_bar_ptr=h.barrier)
cute.copy(tma_k, tBgK[(None,h.count)], tBsK[(None,h.index)], tma_bar_ptr=h.barrier)
cute.copy(tma_v, tVgV[(None,h.count)], tVsV[(None,h.index)], tma_bar_ptr=h.barrier)
peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_p.try_acquire()
ab_p.tail()
# ═══ MMA WARP: QK → signal → wait → PV ═══
if warp_idx == self.mma_warp_id:
tmem.wait_for_alloc()
ab_c.reset(); peek = ab_c.try_wait()
acc_prod_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Producer, self.num_acc_stage)
acc_pipe.producer_acquire(acc_prod_st)
# --- QK MMA: Q @ K^T → FP32 S in TMEM ---
qk_mma.set(tcgen05.Field.ACCUMULATE, False)
for kt in range(k_cnt):
h = ab_c.wait_and_advance(peek)
nblk = cute.size(tCrQ, mode=[2])
for kb in cutlass.range(nblk, unroll_full=True):
cute.gemm(qk_mma, tStS0, tCrQ[(None,None,kb,h.index)], tCrK[(None,None,kb,h.index)], tStS0)
qk_mma.set(tcgen05.Field.ACCUMULATE, True)
h.release(); peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_c.try_wait()
cute.arch.fence_view_async_tmem_store()
# Signal: S is ready (MMA warp arrives, waits for epilogue warps)
scores_ready_bar.arrive_and_wait()
# Wait: softmax done (epilogue warps arrive, MMA warp waits)
softmax_done_bar.arrive_and_wait()
# --- PV MMA: BF16 P @ V → FP32 O in TMEM ---
pv_mma.set(tcgen05.Field.ACCUMULATE, True)
tCrV_s = tCrV[(None, None, None, 0)]
nblk_pv = cute.size(tOrP0, mode=[2])
for kb in cutlass.range(nblk_pv, unroll_full=True):
cute.gemm(pv_mma, tOtO0, tOrP0[(None,None,kb)], tCrV_s[(None,None,kb)], tOtO0)
acc_pipe.producer_commit(acc_prod_st)
acc_prod_st.advance()
acc_pipe.producer_tail(acc_prod_st)
# ═══ EPILOGUE WARPS: softmax packing + output store ═══
if warp_idx < self.mma_warp_id:
tmem.allocate(self.num_tmem_alloc_cols)
tmem.wait_for_alloc()
tmem_ptr = tmem.retrieve_ptr(self.qk_acc_dtype)
sfw_idx = tidx % (32 * len(self.epilogue_warp_id))
# --- TMEM LOAD (C-fragment, FP32) ---
tmem_load_atom = cute.make_copy_atom(
tcgen05.copy.Ld32x32bOp(tcgen05.copy.Repetition(32)), self.qk_acc_dtype)
tiled_tmem_load = tcgen05.make_tmem_copy(tmem_load_atom, tStS0)
thr_load = tiled_tmem_load.get_slice(sfw_idx)
tTMEM_LOADtS = thr_load.partition_S(tStS0)
cS = cute.make_identity_tensor((self.qk_mma_tiler[0], self.qk_mma_tiler[1]))
tScS = qk_thr.partition_C(cS)
tTMEM_LOADcS = thr_load.partition_D(tScS)
# --- TMEM STORE (C-fragment composition, FP32 atom with BF16 recast) ---
tStS_P_layout = cute.composition(tStS.layout, cute.make_layout((128, self.tilePlikeFP32)))
tStS_P = cute.make_tensor(tStS.iterator + self.tmem_p0_offset, tStS_P_layout)
tmem_store_atom = cute.make_copy_atom(
tcgen05.copy.St32x32bOp(tcgen05.copy.Repetition(32)), self.qk_acc_dtype)
tiled_tmem_store = tcgen05.make_tmem_copy(tmem_store_atom, tStS_P)
thr_store = tiled_tmem_store.get_slice(sfw_idx)
tTMEM_STOREtS_x4 = thr_store.partition_D(tStS_P)
tScS_P_layout = cute.composition(tScS.layout, cute.make_layout((128, self.tilePlikeFP32)))
tScS_P = cute.make_tensor(tScS.iterator, tScS_P_layout)
tTMEM_STOREcS = thr_store.partition_S(tScS_P)
# Wait for S ready
scores_ready_bar.arrive_and_wait()
# Load FP32 S from TMEM
tTMEM_LOADrS = cute.make_rmem_tensor(tTMEM_LOADcS.shape, self.qk_acc_dtype)
cute.copy(tiled_tmem_load, tTMEM_LOADtS, tTMEM_LOADrS)
# FP32→BF16 packing (C-fragment composition store pattern)
tTMEM_STORErS_x4 = cute.make_rmem_tensor(tTMEM_STOREcS.shape, self.qk_acc_dtype)
tTMEM_STORErS_x4_e = cute.make_tensor(
cute.recast_ptr(tTMEM_STORErS_x4.iterator, dtype=self.q_dtype),
tTMEM_LOADrS.layout)
frg_cnt = 4
frg_tile = cute.size(tTMEM_LOADrS) // frg_cnt
tTMEM_LOADrS_frg = cute.logical_divide(tTMEM_LOADrS, cute.make_layout(frg_tile))
tTMEM_STORErS_x4_e_frg = cute.logical_divide(
tTMEM_STORErS_x4_e, cute.make_layout(frg_tile))
for j in range(frg_cnt):
s_vec = tTMEM_LOADrS_frg[None, j].load()
tTMEM_STORErS_x4_e_frg[None, j].store(s_vec.to(self.q_dtype))
cute.copy(tiled_tmem_store, tTMEM_STORErS_x4, tTMEM_STOREtS_x4)
cute.arch.fence_view_async_tmem_store()
# Signal: softmax done
softmax_done_bar.arrive_and_wait()
# --- Output epilogue ---
tCtO_base = cute.make_tensor(tmem_ptr + self.tmem_o0_offset, tCtO_fake.layout)
acc_cons_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Consumer, self.num_acc_stage)
c_grp = pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id))
c_pipe = pipeline.PipelineTmaStore.create(num_stages=self.num_c_stage, producer_group=c_grp)
acc_cons_st = utils.gemm.sm100.epilogue_tma_store(
self, tidx, warp_idx, tma_c, tCtO_base, sC, tCgC,
epi_tile, 0, const_expr(lambda x: x), (0,0,0), acc_cons_st, acc_pipe, c_pipe)
c_pipe.producer_tail()
tmem.relinquish_alloc_permit()
tmem.free(tmem_ptr)
def test():
torch.manual_seed(42)
m, n, head_dim = 128, 128, 64
q = torch.randn(m, head_dim, 1, dtype=torch.bfloat16, device='cuda')
k = torch.randn(n, head_dim, 1, dtype=torch.bfloat16, device='cuda')
# V: MN-major — (head_dim, seq) with strides (1, head_dim)
v_base = torch.randn(head_dim, n, dtype=torch.bfloat16, device='cuda')
v = v_base.as_strided((head_dim, n), (1, head_dim)).unsqueeze(-1) # MN-major: strides (1, 64)
c = torch.zeros(m, head_dim, 1, dtype=torch.bfloat16, device='cuda')
qf = q[:,:,0].float(); kf = k[:,:,0].float(); vf = v_base.float()
# Q@K^T = (128,128), PV MMA: P(128,128) @ V(64,128) MN-major
# MN-major B = V[k,n] where k contiguous => MMA computes P @ V^T
ref = qf @ kf.T @ vf.T # (128,64)
import cutlass.torch as ct
mQ = ct.from_dlpack(q).mark_layout_dynamic(leading_dim=ct.get_leading_dim(q))
mK = ct.from_dlpack(k).mark_layout_dynamic(leading_dim=ct.get_leading_dim(k))
mV = ct.from_dlpack(v).mark_layout_dynamic(leading_dim=ct.get_leading_dim(v))
mC = ct.from_dlpack(c).mark_layout_dynamic(leading_dim=ct.get_leading_dim(c))
stream = cuda.CUstream(torch.cuda.current_stream().cuda_stream)
kernel = StageBIdentityKernel(mma_tiler_mn=(128, 128), use_2cta_instrs=False, use_tma_store=True)
print('Compiling...', flush=True)
compiled = cute.compile(kernel, mQ, mK, mV, mC, stream)
print('Running...', flush=True)
compiled(mQ, mK, mV, mC, stream)
torch.cuda.synchronize()
out = c[:,:,0].float()
cos = torch.nn.functional.cosine_similarity(out.flatten().unsqueeze(0), ref.flatten().unsqueeze(0)).item()
max_err = (out - ref).abs().max().item()
print('Stage B v24: Q@K^T + identity softmax (NamedBarrier) + P@V (V MN-major)')
print(' Cosine: {:.6f}, Max error: {:.6f}'.format(cos, max_err))
print(' {}'.format('PASS' if cos >= 0.99 else 'FAIL'))
if __name__ == '__main__':
test()

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tests/test_stage_b_v25.py Normal file
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"""
Stage B v25: Q@K^T + identity softmax P packing + P@V
Uses PipelineAsync (not Umma) for mma_si sync — two separate one-shot pipelines.
Bug 1 fix: V MN-major.
Bug 2 fix: FP32→BF16 P packing (C-fragment composition store).
"""
import torch, cutlass, cutlass.cute as cute, cutlass.utils as utils, cutlass.pipeline as pipeline
from cutlass.cute.nvgpu import cpasync, tcgen05
from cutlass import Float32, BFloat16, Int32, Boolean, const_expr
from cutlass.utils import LayoutEnum
from cutlass.utils.tmem_allocator import find_tmem_tensor_col_offset
import cuda.bindings.driver as cuda
class StageBIdentityKernel:
def __init__(self, mma_tiler_mn, use_2cta_instrs=False, use_tma_store=True):
self.acc_dtype = Float32; self.qk_acc_dtype = Float32
self.q_dtype = BFloat16; self.o_dtype = BFloat16; self.c_dtype = BFloat16
self.use_2cta_instrs = use_2cta_instrs; self.use_tma_store = use_tma_store
self.mma_tiler_mn = mma_tiler_mn; self.mma_tiler = (*mma_tiler_mn, 1)
self.cluster_shape_mn = (1, 1)
self.cta_group = tcgen05.CtaGroup.TWO if use_2cta_instrs else tcgen05.CtaGroup.ONE
self.epilogue_warp_id = (0, 1, 2, 3)
self.mma_warp_id = 4; self.tma_warp_id = 5
self.threads_per_cta = 192
self.epilog_sync_bar_id = 1; self.tmem_alloc_sync_bar_id = 2; self.tmem_dealloc_sync_bar_id = 3
self.num_c_stage = 2
def _setup(self, qk_mma, pv_mma):
qk_inst_k = cute.size(qk_mma.shape_mnk, mode=[2])
self.qk_mma_tiler = (*self.mma_tiler_mn, qk_inst_k * 4)
self.pv_mma_tiler = (self.qk_mma_tiler[0], self.qk_mma_tiler[2], self.qk_mma_tiler[1])
self.mma_tiler = self.qk_mma_tiler
print(f"[v25] qk_mma_tiler = {self.qk_mma_tiler}")
print(f"[v25] pv_mma_tiler = {self.pv_mma_tiler}")
self.cta_tile_shape_mnk = (
self.qk_mma_tiler[0] // cute.size(qk_mma.thr_id.shape),
self.qk_mma_tiler[1],
self.qk_mma_tiler[2],
)
self.cluster_layout_vmnk = cute.tiled_divide(cute.make_layout((1,1,1)), (qk_mma.thr_id.shape,))
self.epi_tile = utils.sm100.compute_epilogue_tile_shape(
self.cta_tile_shape_mnk, self.use_2cta_instrs, self.c_layout, self.o_dtype)
self.num_ab_stage = 1; self.num_acc_stage = 1
self.a_smem_s = utils.sm100.make_smem_layout_a(qk_mma, self.mma_tiler, self.q_dtype, 1)
self.b_smem_s = utils.sm100.make_smem_layout_b(qk_mma, self.mma_tiler, self.b_dtype, 1)
self.v_smem_s = utils.sm100.make_smem_layout_b(pv_mma, self.pv_mma_tiler, self.b_dtype, 1)
self.p_tmem_s = utils.sm100.make_smem_layout_a(pv_mma, self.pv_mma_tiler, self.q_dtype, 1)
self.c_smem_s = utils.sm100.make_smem_layout_epi(self.o_dtype, self.c_layout, self.epi_tile, 2)
qk_thr = qk_mma.get_slice(0)
qk_acc_shape = qk_thr.partition_shape_C(self.qk_mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
s_cols = find_tmem_tensor_col_offset(tStS)
pv_thr = pv_mma.get_slice(0)
pv_acc_shape = pv_thr.partition_shape_C(self.pv_mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
o_cols = find_tmem_tensor_col_offset(tOtO)
self.tilePlikeFP32 = self.qk_mma_tiler[1] // Float32.width * self.o_dtype.width
self.tmem_s0_offset = 0
self.tmem_p0_offset = 32
self.tmem_o0_offset = s_cols
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, self.num_acc_stage))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, self.num_acc_stage))
self.num_tmem_alloc_cols = utils.get_num_tmem_alloc_cols([tCtS_fake, tCtO_fake], arch="sm_100")
a_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
b_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
self.num_tma_load_bytes = (
cute.size_in_bytes(self.q_dtype, a_smem) + cute.size_in_bytes(self.b_dtype, b_smem)
) * cute.size(qk_mma.thr_id.shape)
@cute.jit
def __call__(self, q: cute.Tensor, k: cute.Tensor, v: cute.Tensor, c: cute.Tensor, stream: cuda.CUstream):
self.q_dtype = q.element_type; self.b_dtype = k.element_type
self.o_dtype = c.element_type; self.c_dtype = self.o_dtype
self.a_major = LayoutEnum.from_tensor(q).mma_major_mode()
self.b_major = LayoutEnum.from_tensor(k).mma_major_mode()
self.v_major = LayoutEnum.from_tensor(v).mma_major_mode()
self.c_layout = LayoutEnum.from_tensor(c)
print(f"[v25] a_major (Q) = {self.a_major}")
print(f"[v25] b_major (K) = {self.b_major}")
print(f"[v25] v_major (V) = {self.v_major}")
qk_mma = utils.sm100.make_trivial_tiled_mma(
self.q_dtype, self.b_dtype, self.a_major, self.b_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.SMEM)
pv_mma = utils.sm100.make_trivial_tiled_mma(
self.q_dtype, self.b_dtype, cute.nvgpu.OperandMajorMode.K, self.v_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.TMEM)
self._setup(qk_mma, pv_mma)
q_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
k_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
v_smem = cute.slice_(self.v_smem_s, (None, None, None, 0))
tma_q, tma_tq = cute.nvgpu.make_tiled_tma_atom_A(
utils.sm100.cluster_shape_to_tma_atom_A(self.cluster_shape_mn, qk_mma.thr_id),
q, q_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
tma_k, tma_tk = cute.nvgpu.make_tiled_tma_atom_B(
utils.sm100.cluster_shape_to_tma_atom_B(self.cluster_shape_mn, qk_mma.thr_id),
k, k_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
tma_v, tma_tv = cute.nvgpu.make_tiled_tma_atom_B(
utils.sm100.cluster_shape_to_tma_atom_B(self.cluster_shape_mn, pv_mma.thr_id),
v, v_smem, self.pv_mma_tiler, pv_mma, self.cluster_layout_vmnk.shape)
epi_smem = cute.select(self.c_smem_s, mode=[0, 1])
tma_c, tma_tc = cpasync.make_tiled_tma_atom(cpasync.CopyBulkTensorTileS2GOp(), c, epi_smem, self.epi_tile)
self._kernel(qk_mma, pv_mma, tma_q, tma_tq, tma_k, tma_tk, tma_v, tma_tv,
tma_c, tma_tc, self.cluster_layout_vmnk,
self.a_smem_s, self.b_smem_s, self.v_smem_s, self.p_tmem_s, self.c_smem_s, self.epi_tile
).launch(grid=(1,1,1), block=[self.threads_per_cta,1,1], stream=stream)
@cute.kernel
def _kernel(self, qk_mma, pv_mma, tma_q, mQ, tma_k, mK, tma_v, mV,
tma_c, mC, cl_vmnk, a_smem_s, b_smem_s, v_smem_s, p_tmem_s, c_smem_s, epi_tile):
warp_idx = cute.arch.make_warp_uniform(cute.arch.warp_idx())
tidx, _, _ = cute.arch.thread_idx()
use_2cta = cute.size(qk_mma.thr_id.shape) == 2
if warp_idx == self.tma_warp_id:
cpasync.prefetch_descriptor(tma_q); cpasync.prefetch_descriptor(tma_k)
cpasync.prefetch_descriptor(tma_v); cpasync.prefetch_descriptor(tma_c)
@cute.struct
class SS:
ab_bar: cute.struct.MemRange[cutlass.Int64, self.num_ab_stage * 2]
acc_bar: cute.struct.MemRange[cutlass.Int64, self.num_acc_stage * 2]
# Two separate mbarriers for mma→softmax and softmax→mma signaling
scores_ready_bar: cute.struct.MemRange[cutlass.Int64, 2] # MMA→softmax
softmax_done_bar: cute.struct.MemRange[cutlass.Int64, 2] # softmax→MMA
tmem_dealloc: cutlass.Int64
holding: cutlass.Int32
smem = utils.SmemAllocator(); st = smem.allocate(SS)
ab_p, ab_c = pipeline.PipelineTmaUmma.create(
barrier_storage=st.ab_bar.data_ptr(), num_stages=self.num_ab_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 1),
tx_count=self.num_tma_load_bytes, cta_layout_vmnk=cl_vmnk, defer_sync=True
).make_participants()
acc_pipe = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.acc_bar.data_ptr(), num_stages=self.num_acc_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(
pipeline.Agent.Thread, len(self.epilogue_warp_id) * (2 if use_2cta else 1)),
cta_layout_vmnk=cl_vmnk, defer_sync=True)
tmem_bar = pipeline.NamedBarrier(barrier_id=self.tmem_alloc_sync_bar_id,
num_threads=32 * len((self.mma_warp_id, *self.epilogue_warp_id)))
tmem = utils.TmemAllocator(st.holding.ptr, barrier_for_retrieve=tmem_bar,
allocator_warp_id=self.epilogue_warp_id[0], is_two_cta=use_2cta,
two_cta_tmem_dealloc_mbar_ptr=st.tmem_dealloc.ptr)
# PipelineAsync for scores_ready (MMA → softmax)
scores_ready_prod, scores_ready_cons = pipeline.PipelineAsync.create(
barrier_storage=st.scores_ready_bar.data_ptr(), num_stages=1,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id)),
).make_participants()
# PipelineAsync for softmax_done (softmax → MMA)
softmax_done_prod, softmax_done_cons = pipeline.PipelineAsync.create(
barrier_storage=st.softmax_done_bar.data_ptr(), num_stages=1,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id)),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
).make_participants()
pipeline.pipeline_init_arrive(cluster_shape_mn=cl_vmnk, is_relaxed=True)
sQ = smem.allocate_tensor(element_type=self.q_dtype, layout=a_smem_s.outer, byte_alignment=128, swizzle=a_smem_s.inner)
sK = smem.allocate_tensor(element_type=self.b_dtype, layout=b_smem_s.outer, byte_alignment=128, swizzle=b_smem_s.inner)
sV = smem.allocate_tensor(element_type=self.b_dtype, layout=v_smem_s.outer, byte_alignment=128, swizzle=v_smem_s.inner)
sC = smem.allocate_tensor(element_type=self.o_dtype, layout=c_smem_s.outer, byte_alignment=128, swizzle=c_smem_s.inner)
gQ = cute.local_tile(mQ, cute.slice_(self.qk_mma_tiler, (None,0,None)), (None,None,None))
gK = cute.local_tile(mK, cute.slice_(self.qk_mma_tiler, (0,None,None)), (None,None,None))
gC = cute.local_tile(mC, cute.slice_(self.qk_mma_tiler, (None,None,0)), (None,None,None))
k_cnt = cute.size(gQ, mode=[3])
qk_thr = qk_mma.get_slice(0)
pv_thr = pv_mma.get_slice(0)
tCgQ = qk_thr.partition_A(gQ); tCgK = qk_thr.partition_B(gK); tCgC = qk_thr.partition_C(gC)
a_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,0,None,0)).shape)
tAsQ, tAgQ = cpasync.tma_partition(tma_q, 0, a_lay, cute.group_modes(sQ,0,3), cute.group_modes(tCgQ,0,3))
b_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,None,0,0)).shape)
tBsK, tBgK = cpasync.tma_partition(tma_k, 0, b_lay, cute.group_modes(sK,0,3), cute.group_modes(tCgK,0,3))
tAgQ = tAgQ[(None,0,None,0)]; tBgK = tBgK[(None,0,None,0)]
gV = cute.local_tile(mV, cute.slice_(self.pv_mma_tiler, (0,None,None)), (None,None,None))
tCgV = pv_thr.partition_B(gV)
tVsV, tVgV = cpasync.tma_partition(tma_v, 0, b_lay, cute.group_modes(sV,0,3), cute.group_modes(tCgV,0,3))
tVgV = tVgV[(None,0,None,0)]
tCrQ = qk_mma.make_fragment_A(sQ); tCrK = qk_mma.make_fragment_B(sK)
tCrV = pv_mma.make_fragment_B(sV)
qk_acc_shape = qk_thr.partition_shape_C(self.qk_mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
tStS0 = cute.make_tensor(tStS.iterator + self.tmem_s0_offset, tStS.layout)
pv_acc_shape = pv_thr.partition_shape_C(self.pv_mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
tOtO0 = cute.make_tensor(tOtO.iterator + self.tmem_o0_offset, tOtO.layout)
tP = cute.make_tensor(tStS.iterator, p_tmem_s.outer)
tOrP_base = pv_thr.make_fragment_A(tP)
tOrP = tOrP_base[(None, None, None, 0)]
tOrP0 = cute.make_tensor(
tOrP.iterator + self.qk_acc_dtype.width // self.q_dtype.width * self.tmem_p0_offset,
tOrP.layout)
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, self.num_acc_stage))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, self.num_acc_stage))
pipeline.pipeline_init_wait(cluster_shape_mn=cl_vmnk)
# ═══ TMA LOAD WARP ═══
if warp_idx == self.tma_warp_id:
ab_p.reset(); peek = ab_p.try_acquire()
for kt in cutlass.range(k_cnt, unroll=1):
h = ab_p.acquire_and_advance(peek)
cute.copy(tma_q, tAgQ[(None,h.count)], tAsQ[(None,h.index)], tma_bar_ptr=h.barrier)
cute.copy(tma_k, tBgK[(None,h.count)], tBsK[(None,h.index)], tma_bar_ptr=h.barrier)
cute.copy(tma_v, tVgV[(None,h.count)], tVsV[(None,h.index)], tma_bar_ptr=h.barrier)
peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_p.try_acquire()
ab_p.tail()
# ═══ MMA WARP ═══
if warp_idx == self.mma_warp_id:
tmem.wait_for_alloc()
ab_c.reset(); peek = ab_c.try_wait()
acc_prod_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Producer, self.num_acc_stage)
acc_pipe.producer_acquire(acc_prod_st)
# QK MMA
qk_mma.set(tcgen05.Field.ACCUMULATE, False)
for kt in range(k_cnt):
h = ab_c.wait_and_advance(peek)
nblk = cute.size(tCrQ, mode=[2])
for kb in cutlass.range(nblk, unroll_full=True):
cute.gemm(qk_mma, tStS0, tCrQ[(None,None,kb,h.index)], tCrK[(None,None,kb,h.index)], tStS0)
qk_mma.set(tcgen05.Field.ACCUMULATE, True)
h.release(); peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_c.try_wait()
cute.arch.fence_view_async_tmem_store()
# Signal: S ready → epilogue warps can start softmax
scores_ready_prod.acquire_and_advance().commit()
scores_ready_prod.tail()
# Wait: softmax done → can start PV MMA
softmax_done_cons.reset()
softmax_done_cons.wait_and_advance().release()
# PV MMA
pv_mma.set(tcgen05.Field.ACCUMULATE, True)
tCrV_s = tCrV[(None, None, None, 0)]
nblk_pv = cute.size(tOrP0, mode=[2])
for kb in cutlass.range(nblk_pv, unroll_full=True):
cute.gemm(pv_mma, tOtO0, tOrP0[(None,None,kb)], tCrV_s[(None,None,kb)], tOtO0)
acc_pipe.producer_commit(acc_prod_st)
acc_prod_st.advance()
acc_pipe.producer_tail(acc_prod_st)
# ═══ EPILOGUE WARPS ═══
if warp_idx < self.mma_warp_id:
tmem.allocate(self.num_tmem_alloc_cols)
tmem.wait_for_alloc()
tmem_ptr = tmem.retrieve_ptr(self.qk_acc_dtype)
sfw_idx = tidx % (32 * len(self.epilogue_warp_id))
tmem_load_atom = cute.make_copy_atom(
tcgen05.copy.Ld32x32bOp(tcgen05.copy.Repetition(32)), self.qk_acc_dtype)
tiled_tmem_load = tcgen05.make_tmem_copy(tmem_load_atom, tStS0)
thr_load = tiled_tmem_load.get_slice(sfw_idx)
tTMEM_LOADtS = thr_load.partition_S(tStS0)
cS = cute.make_identity_tensor((self.qk_mma_tiler[0], self.qk_mma_tiler[1]))
tScS = qk_thr.partition_C(cS)
tTMEM_LOADcS = thr_load.partition_D(tScS)
tStS_P_layout = cute.composition(tStS.layout, cute.make_layout((128, self.tilePlikeFP32)))
tStS_P = cute.make_tensor(tStS.iterator + self.tmem_p0_offset, tStS_P_layout)
tmem_store_atom = cute.make_copy_atom(
tcgen05.copy.St32x32bOp(tcgen05.copy.Repetition(32)), self.qk_acc_dtype)
tiled_tmem_store = tcgen05.make_tmem_copy(tmem_store_atom, tStS_P)
thr_store = tiled_tmem_store.get_slice(sfw_idx)
tTMEM_STOREtS_x4 = thr_store.partition_D(tStS_P)
tScS_P_layout = cute.composition(tScS.layout, cute.make_layout((128, self.tilePlikeFP32)))
tScS_P = cute.make_tensor(tScS.iterator, tScS_P_layout)
tTMEM_STOREcS = thr_store.partition_S(tScS_P)
# Wait: S ready
scores_ready_cons.reset()
scores_ready_cons.wait_and_advance().release()
# Load FP32 S
tTMEM_LOADrS = cute.make_rmem_tensor(tTMEM_LOADcS.shape, self.qk_acc_dtype)
cute.copy(tiled_tmem_load, tTMEM_LOADtS, tTMEM_LOADrS)
# FP32→BF16 packing
tTMEM_STORErS_x4 = cute.make_rmem_tensor(tTMEM_STOREcS.shape, self.qk_acc_dtype)
tTMEM_STORErS_x4_e = cute.make_tensor(
cute.recast_ptr(tTMEM_STORErS_x4.iterator, dtype=self.q_dtype),
tTMEM_LOADrS.layout)
frg_cnt = 4
frg_tile = cute.size(tTMEM_LOADrS) // frg_cnt
tTMEM_LOADrS_frg = cute.logical_divide(tTMEM_LOADrS, cute.make_layout(frg_tile))
tTMEM_STORErS_x4_e_frg = cute.logical_divide(
tTMEM_STORErS_x4_e, cute.make_layout(frg_tile))
for j in range(frg_cnt):
s_vec = tTMEM_LOADrS_frg[None, j].load()
tTMEM_STORErS_x4_e_frg[None, j].store(s_vec.to(self.q_dtype))
cute.copy(tiled_tmem_store, tTMEM_STORErS_x4, tTMEM_STOREtS_x4)
cute.arch.fence_view_async_tmem_store()
# Signal: softmax done
softmax_done_prod.acquire_and_advance().commit()
softmax_done_prod.tail()
# Output epilogue
tCtO_base = cute.make_tensor(tmem_ptr + self.tmem_o0_offset, tCtO_fake.layout)
acc_cons_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Consumer, self.num_acc_stage)
c_grp = pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id))
c_pipe = pipeline.PipelineTmaStore.create(num_stages=self.num_c_stage, producer_group=c_grp)
acc_cons_st = utils.gemm.sm100.epilogue_tma_store(
self, tidx, warp_idx, tma_c, tCtO_base, sC, tCgC,
epi_tile, 0, const_expr(lambda x: x), (0,0,0), acc_cons_st, acc_pipe, c_pipe)
c_pipe.producer_tail()
tmem.relinquish_alloc_permit()
tmem.free(tmem_ptr)
def test():
torch.manual_seed(42)
m, n, head_dim = 128, 128, 64
q = torch.randn(m, head_dim, 1, dtype=torch.bfloat16, device='cuda')
k = torch.randn(n, head_dim, 1, dtype=torch.bfloat16, device='cuda')
v_base = torch.randn(head_dim, n, dtype=torch.bfloat16, device='cuda')
v = v_base.as_strided((head_dim, n), (1, head_dim)).unsqueeze(-1)
c = torch.zeros(m, head_dim, 1, dtype=torch.bfloat16, device='cuda')
qf = q[:,:,0].float(); kf = k[:,:,0].float(); vf = v_base.float()
ref = qf @ kf.T @ vf.T
import cutlass.torch as ct
mQ = ct.from_dlpack(q).mark_layout_dynamic(leading_dim=ct.get_leading_dim(q))
mK = ct.from_dlpack(k).mark_layout_dynamic(leading_dim=ct.get_leading_dim(k))
mV = ct.from_dlpack(v).mark_layout_dynamic(leading_dim=ct.get_leading_dim(v))
mC = ct.from_dlpack(c).mark_layout_dynamic(leading_dim=ct.get_leading_dim(c))
stream = cuda.CUstream(torch.cuda.current_stream().cuda_stream)
kernel = StageBIdentityKernel(mma_tiler_mn=(128, 128), use_2cta_instrs=False, use_tma_store=True)
print('Compiling...', flush=True)
compiled = cute.compile(kernel, mQ, mK, mV, mC, stream)
print('Running...', flush=True)
compiled(mQ, mK, mV, mC, stream)
torch.cuda.synchronize()
out = c[:,:,0].float()
cos = torch.nn.functional.cosine_similarity(out.flatten().unsqueeze(0), ref.flatten().unsqueeze(0)).item()
max_err = (out - ref).abs().max().item()
print('Stage B v25: PipelineAsync for mma↔softmax sync, V MN-major')
print(' Cosine: {:.6f}, Max error: {:.6f}'.format(cos, max_err))
print(' {}'.format('PASS' if cos >= 0.99 else 'FAIL'))
if __name__ == '__main__':
test()

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tests/test_stage_b_v26.py Normal file
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"""
Stage B v26: Q@K^T + identity softmax P packing + P@V
Uses SMEM spin-wait flags for mma↔softmax sync (no PipelineUmmaAsync).
Bug 1 fix: V MN-major.
Bug 2 fix: FP32→BF16 P packing (C-fragment composition store).
"""
import torch, cutlass, cutlass.cute as cute, cutlass.utils as utils, cutlass.pipeline as pipeline
from cutlass.cute.nvgpu import cpasync, tcgen05
from cutlass import Float32, BFloat16, Int32, Boolean, const_expr
from cutlass.utils import LayoutEnum
from cutlass.utils.tmem_allocator import find_tmem_tensor_col_offset
import cuda.bindings.driver as cuda
class StageBIdentityKernel:
def __init__(self, mma_tiler_mn, use_2cta_instrs=False, use_tma_store=True):
self.acc_dtype = Float32; self.qk_acc_dtype = Float32
self.q_dtype = BFloat16; self.o_dtype = BFloat16; self.c_dtype = BFloat16
self.use_2cta_instrs = use_2cta_instrs; self.use_tma_store = use_tma_store
self.mma_tiler_mn = mma_tiler_mn; self.mma_tiler = (*mma_tiler_mn, 1)
self.cluster_shape_mn = (1, 1)
self.cta_group = tcgen05.CtaGroup.TWO if use_2cta_instrs else tcgen05.CtaGroup.ONE
self.epilogue_warp_id = (0, 1, 2, 3)
self.mma_warp_id = 4; self.tma_warp_id = 5
self.threads_per_cta = 192
self.epilog_sync_bar_id = 1; self.tmem_alloc_sync_bar_id = 2; self.tmem_dealloc_sync_bar_id = 3
self.num_c_stage = 2
def _setup(self, qk_mma, pv_mma):
qk_inst_k = cute.size(qk_mma.shape_mnk, mode=[2])
self.qk_mma_tiler = (*self.mma_tiler_mn, qk_inst_k * 4)
self.pv_mma_tiler = (self.qk_mma_tiler[0], self.qk_mma_tiler[2], self.qk_mma_tiler[1])
self.mma_tiler = self.qk_mma_tiler
print(f"[v26] qk_mma_tiler = {self.qk_mma_tiler}")
print(f"[v26] pv_mma_tiler = {self.pv_mma_tiler}")
self.cta_tile_shape_mnk = (
self.qk_mma_tiler[0] // cute.size(qk_mma.thr_id.shape),
self.qk_mma_tiler[1],
self.qk_mma_tiler[2],
)
self.cluster_layout_vmnk = cute.tiled_divide(cute.make_layout((1,1,1)), (qk_mma.thr_id.shape,))
self.epi_tile = utils.sm100.compute_epilogue_tile_shape(
self.cta_tile_shape_mnk, self.use_2cta_instrs, self.c_layout, self.o_dtype)
self.num_ab_stage = 1; self.num_acc_stage = 1
self.a_smem_s = utils.sm100.make_smem_layout_a(qk_mma, self.mma_tiler, self.q_dtype, 1)
self.b_smem_s = utils.sm100.make_smem_layout_b(qk_mma, self.mma_tiler, self.b_dtype, 1)
self.v_smem_s = utils.sm100.make_smem_layout_b(pv_mma, self.pv_mma_tiler, self.b_dtype, 1)
self.p_tmem_s = utils.sm100.make_smem_layout_a(pv_mma, self.pv_mma_tiler, self.q_dtype, 1)
self.c_smem_s = utils.sm100.make_smem_layout_epi(self.o_dtype, self.c_layout, self.epi_tile, 2)
qk_thr = qk_mma.get_slice(0)
qk_acc_shape = qk_thr.partition_shape_C(self.qk_mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
s_cols = find_tmem_tensor_col_offset(tStS)
pv_thr = pv_mma.get_slice(0)
pv_acc_shape = pv_thr.partition_shape_C(self.pv_mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
o_cols = find_tmem_tensor_col_offset(tOtO)
self.tilePlikeFP32 = self.qk_mma_tiler[1] // Float32.width * self.o_dtype.width
self.tmem_s0_offset = 0
self.tmem_p0_offset = 32
self.tmem_o0_offset = s_cols
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, self.num_acc_stage))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, self.num_acc_stage))
self.num_tmem_alloc_cols = utils.get_num_tmem_alloc_cols([tCtS_fake, tCtO_fake], arch="sm_100")
a_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
b_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
self.num_tma_load_bytes = (
cute.size_in_bytes(self.q_dtype, a_smem) + cute.size_in_bytes(self.b_dtype, b_smem)
) * cute.size(qk_mma.thr_id.shape)
@cute.jit
def __call__(self, q: cute.Tensor, k: cute.Tensor, v: cute.Tensor, c: cute.Tensor, stream: cuda.CUstream):
self.q_dtype = q.element_type; self.b_dtype = k.element_type
self.o_dtype = c.element_type; self.c_dtype = self.o_dtype
self.a_major = LayoutEnum.from_tensor(q).mma_major_mode()
self.b_major = LayoutEnum.from_tensor(k).mma_major_mode()
self.v_major = LayoutEnum.from_tensor(v).mma_major_mode()
self.c_layout = LayoutEnum.from_tensor(c)
qk_mma = utils.sm100.make_trivial_tiled_mma(
self.q_dtype, self.b_dtype, self.a_major, self.b_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.SMEM)
pv_mma = utils.sm100.make_trivial_tiled_mma(
self.q_dtype, self.b_dtype, cute.nvgpu.OperandMajorMode.K, self.v_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.TMEM)
self._setup(qk_mma, pv_mma)
q_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
k_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
v_smem = cute.slice_(self.v_smem_s, (None, None, None, 0))
tma_q, tma_tq = cute.nvgpu.make_tiled_tma_atom_A(
utils.sm100.cluster_shape_to_tma_atom_A(self.cluster_shape_mn, qk_mma.thr_id),
q, q_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
tma_k, tma_tk = cute.nvgpu.make_tiled_tma_atom_B(
utils.sm100.cluster_shape_to_tma_atom_B(self.cluster_shape_mn, qk_mma.thr_id),
k, k_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
tma_v, tma_tv = cute.nvgpu.make_tiled_tma_atom_B(
utils.sm100.cluster_shape_to_tma_atom_B(self.cluster_shape_mn, pv_mma.thr_id),
v, v_smem, self.pv_mma_tiler, pv_mma, self.cluster_layout_vmnk.shape)
epi_smem = cute.select(self.c_smem_s, mode=[0, 1])
tma_c, tma_tc = cpasync.make_tiled_tma_atom(cpasync.CopyBulkTensorTileS2GOp(), c, epi_smem, self.epi_tile)
self._kernel(qk_mma, pv_mma, tma_q, tma_tq, tma_k, tma_tk, tma_v, tma_tv,
tma_c, tma_tc, self.cluster_layout_vmnk,
self.a_smem_s, self.b_smem_s, self.v_smem_s, self.p_tmem_s, self.c_smem_s, self.epi_tile
).launch(grid=(1,1,1), block=[self.threads_per_cta,1,1], stream=stream)
@cute.kernel
def _kernel(self, qk_mma, pv_mma, tma_q, mQ, tma_k, mK, tma_v, mV,
tma_c, mC, cl_vmnk, a_smem_s, b_smem_s, v_smem_s, p_tmem_s, c_smem_s, epi_tile):
warp_idx = cute.arch.make_warp_uniform(cute.arch.warp_idx())
tidx, _, _ = cute.arch.thread_idx()
use_2cta = cute.size(qk_mma.thr_id.shape) == 2
if warp_idx == self.tma_warp_id:
cpasync.prefetch_descriptor(tma_q); cpasync.prefetch_descriptor(tma_k)
cpasync.prefetch_descriptor(tma_v); cpasync.prefetch_descriptor(tma_c)
@cute.struct
class SS:
ab_bar: cute.struct.MemRange[cutlass.Int64, self.num_ab_stage * 2]
acc_bar: cute.struct.MemRange[cutlass.Int64, self.num_acc_stage * 2]
tmem_dealloc: cutlass.Int64
holding: cutlass.Int32
smem = utils.SmemAllocator(); st = smem.allocate(SS)
ab_p, ab_c = pipeline.PipelineTmaUmma.create(
barrier_storage=st.ab_bar.data_ptr(), num_stages=self.num_ab_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 1),
tx_count=self.num_tma_load_bytes, cta_layout_vmnk=cl_vmnk, defer_sync=True
).make_participants()
acc_pipe = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.acc_bar.data_ptr(), num_stages=self.num_acc_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(
pipeline.Agent.Thread, len(self.epilogue_warp_id) * (2 if use_2cta else 1)),
cta_layout_vmnk=cl_vmnk, defer_sync=True)
# Use acc_pipe's barrier for BOTH QK→softmax and PV→epilogue signaling
# The trick: re-acquire acc_pipe on the producer side after softmax
# This works because PipelineUmmaAsync with 1 stage blocks producer
# until consumer releases
tmem_bar = pipeline.NamedBarrier(barrier_id=self.tmem_alloc_sync_bar_id,
num_threads=32 * len((self.mma_warp_id, *self.epilogue_warp_id)))
tmem = utils.TmemAllocator(st.holding.ptr, barrier_for_retrieve=tmem_bar,
allocator_warp_id=self.epilogue_warp_id[0], is_two_cta=use_2cta,
two_cta_tmem_dealloc_mbar_ptr=st.tmem_dealloc.ptr)
pipeline.pipeline_init_arrive(cluster_shape_mn=cl_vmnk, is_relaxed=True)
sQ = smem.allocate_tensor(element_type=self.q_dtype, layout=a_smem_s.outer, byte_alignment=128, swizzle=a_smem_s.inner)
sK = smem.allocate_tensor(element_type=self.b_dtype, layout=b_smem_s.outer, byte_alignment=128, swizzle=b_smem_s.inner)
sV = smem.allocate_tensor(element_type=self.b_dtype, layout=v_smem_s.outer, byte_alignment=128, swizzle=v_smem_s.inner)
sC = smem.allocate_tensor(element_type=self.o_dtype, layout=c_smem_s.outer, byte_alignment=128, swizzle=c_smem_s.inner)
gQ = cute.local_tile(mQ, cute.slice_(self.qk_mma_tiler, (None,0,None)), (None,None,None))
gK = cute.local_tile(mK, cute.slice_(self.qk_mma_tiler, (0,None,None)), (None,None,None))
gC = cute.local_tile(mC, cute.slice_(self.qk_mma_tiler, (None,None,0)), (None,None,None))
k_cnt = cute.size(gQ, mode=[3])
qk_thr = qk_mma.get_slice(0)
pv_thr = pv_mma.get_slice(0)
tCgQ = qk_thr.partition_A(gQ); tCgK = qk_thr.partition_B(gK); tCgC = qk_thr.partition_C(gC)
a_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,0,None,0)).shape)
tAsQ, tAgQ = cpasync.tma_partition(tma_q, 0, a_lay, cute.group_modes(sQ,0,3), cute.group_modes(tCgQ,0,3))
b_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,None,0,0)).shape)
tBsK, tBgK = cpasync.tma_partition(tma_k, 0, b_lay, cute.group_modes(sK,0,3), cute.group_modes(tCgK,0,3))
tAgQ = tAgQ[(None,0,None,0)]; tBgK = tBgK[(None,0,None,0)]
gV = cute.local_tile(mV, cute.slice_(self.pv_mma_tiler, (0,None,None)), (None,None,None))
tCgV = pv_thr.partition_B(gV)
tVsV, tVgV = cpasync.tma_partition(tma_v, 0, b_lay, cute.group_modes(sV,0,3), cute.group_modes(tCgV,0,3))
tVgV = tVgV[(None,0,None,0)]
tCrQ = qk_mma.make_fragment_A(sQ); tCrK = qk_mma.make_fragment_B(sK)
tCrV = pv_mma.make_fragment_B(sV)
qk_acc_shape = qk_thr.partition_shape_C(self.qk_mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
tStS0 = cute.make_tensor(tStS.iterator + self.tmem_s0_offset, tStS.layout)
pv_acc_shape = pv_thr.partition_shape_C(self.pv_mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
tOtO0 = cute.make_tensor(tOtO.iterator + self.tmem_o0_offset, tOtO.layout)
tP = cute.make_tensor(tStS.iterator, p_tmem_s.outer)
tOrP_base = pv_thr.make_fragment_A(tP)
tOrP = tOrP_base[(None, None, None, 0)]
tOrP0 = cute.make_tensor(
tOrP.iterator + self.qk_acc_dtype.width // self.q_dtype.width * self.tmem_p0_offset,
tOrP.layout)
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, self.num_acc_stage))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, self.num_acc_stage))
pipeline.pipeline_init_wait(cluster_shape_mn=cl_vmnk)
# ═══ TMA LOAD WARP (no tmem.wait_for_alloc!) ═══
if warp_idx == self.tma_warp_id:
ab_p.reset(); peek = ab_p.try_acquire()
for kt in cutlass.range(k_cnt, unroll=1):
h = ab_p.acquire_and_advance(peek)
cute.copy(tma_q, tAgQ[(None,h.count)], tAsQ[(None,h.index)], tma_bar_ptr=h.barrier)
cute.copy(tma_k, tBgK[(None,h.count)], tBsK[(None,h.index)], tma_bar_ptr=h.barrier)
cute.copy(tma_v, tVgV[(None,h.count)], tVsV[(None,h.index)], tma_bar_ptr=h.barrier)
peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_p.try_acquire()
ab_p.tail()
# ═══ MMA WARP ═══
if warp_idx == self.mma_warp_id:
tmem.wait_for_alloc()
ab_c.reset(); peek = ab_c.try_wait()
# --- QK MMA ---
qk_mma.set(tcgen05.Field.ACCUMULATE, False)
for kt in range(k_cnt):
h = ab_c.wait_and_advance(peek)
nblk = cute.size(tCrQ, mode=[2])
for kb in cutlass.range(nblk, unroll_full=True):
cute.gemm(qk_mma, tStS0, tCrQ[(None,None,kb,h.index)], tCrK[(None,None,kb,h.index)], tStS0)
qk_mma.set(tcgen05.Field.ACCUMULATE, True)
h.release(); peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_c.try_wait()
cute.arch.fence_view_async_tmem_store()
# --- Signal acc_pipe: S ready (producer commit) ---
acc_prod_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Producer, self.num_acc_stage)
acc_pipe.producer_acquire(acc_prod_st)
acc_pipe.producer_commit(acc_prod_st)
acc_prod_st.advance()
# --- Wait for softmax done (producer re-acquire blocks until consumer releases) ---
acc_prod_st2 = pipeline.make_pipeline_state(pipeline.PipelineUserType.Producer, self.num_acc_stage)
acc_pipe.producer_acquire(acc_prod_st2)
# --- PV MMA ---
pv_mma.set(tcgen05.Field.ACCUMULATE, True)
tCrV_s = tCrV[(None, None, None, 0)]
nblk_pv = cute.size(tOrP0, mode=[2])
for kb in cutlass.range(nblk_pv, unroll_full=True):
cute.gemm(pv_mma, tOtO0, tOrP0[(None,None,kb)], tCrV_s[(None,None,kb)], tOtO0)
acc_pipe.producer_commit(acc_prod_st2)
acc_prod_st2.advance()
acc_pipe.producer_tail(acc_prod_st2)
# ═══ EPILOGUE WARPS ═══
if warp_idx < self.mma_warp_id:
tmem.allocate(self.num_tmem_alloc_cols)
tmem.wait_for_alloc()
tmem_ptr = tmem.retrieve_ptr(self.qk_acc_dtype)
sfw_idx = tidx % (32 * len(self.epilogue_warp_id))
# TMEM load/store setup
tmem_load_atom = cute.make_copy_atom(
tcgen05.copy.Ld32x32bOp(tcgen05.copy.Repetition(32)), self.qk_acc_dtype)
tiled_tmem_load = tcgen05.make_tmem_copy(tmem_load_atom, tStS0)
thr_load = tiled_tmem_load.get_slice(sfw_idx)
tTMEM_LOADtS = thr_load.partition_S(tStS0)
cS = cute.make_identity_tensor((self.qk_mma_tiler[0], self.qk_mma_tiler[1]))
tScS = qk_thr.partition_C(cS)
tTMEM_LOADcS = thr_load.partition_D(tScS)
tStS_P_layout = cute.composition(tStS.layout, cute.make_layout((128, self.tilePlikeFP32)))
tStS_P = cute.make_tensor(tStS.iterator + self.tmem_p0_offset, tStS_P_layout)
tmem_store_atom = cute.make_copy_atom(
tcgen05.copy.St32x32bOp(tcgen05.copy.Repetition(32)), self.qk_acc_dtype)
tiled_tmem_store = tcgen05.make_tmem_copy(tmem_store_atom, tStS_P)
thr_store = tiled_tmem_store.get_slice(sfw_idx)
tTMEM_STOREtS_x4 = thr_store.partition_D(tStS_P)
tScS_P_layout = cute.composition(tScS.layout, cute.make_layout((128, self.tilePlikeFP32)))
tScS_P = cute.make_tensor(tScS.iterator, tScS_P_layout)
tTMEM_STOREcS = thr_store.partition_S(tScS_P)
# --- Wait for S ready (consumer wait) ---
acc_cons_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Consumer, self.num_acc_stage)
acc_pipe.consumer_wait(acc_cons_st)
# --- Softmax: FP32→BF16 P packing ---
tTMEM_LOADrS = cute.make_rmem_tensor(tTMEM_LOADcS.shape, self.qk_acc_dtype)
cute.copy(tiled_tmem_load, tTMEM_LOADtS, tTMEM_LOADrS)
tTMEM_STORErS_x4 = cute.make_rmem_tensor(tTMEM_STOREcS.shape, self.qk_acc_dtype)
tTMEM_STORErS_x4_e = cute.make_tensor(
cute.recast_ptr(tTMEM_STORErS_x4.iterator, dtype=self.q_dtype),
tTMEM_LOADrS.layout)
frg_cnt = 4
frg_tile = cute.size(tTMEM_LOADrS) // frg_cnt
tTMEM_LOADrS_frg = cute.logical_divide(tTMEM_LOADrS, cute.make_layout(frg_tile))
tTMEM_STORErS_x4_e_frg = cute.logical_divide(
tTMEM_STORErS_x4_e, cute.make_layout(frg_tile))
for j in range(frg_cnt):
s_vec = tTMEM_LOADrS_frg[None, j].load()
tTMEM_STORErS_x4_e_frg[None, j].store(s_vec.to(self.q_dtype))
cute.copy(tiled_tmem_store, tTMEM_STORErS_x4, tTMEM_STOREtS_x4)
cute.arch.fence_view_async_tmem_store()
# --- Release acc_pipe: softmax done (consumer release) ---
acc_pipe.consumer_release(acc_cons_st)
acc_cons_st.advance()
# --- Wait for PV done (consumer wait on 2nd producer commit) ---
acc_cons_st2 = pipeline.make_pipeline_state(pipeline.PipelineUserType.Consumer, self.num_acc_stage)
acc_pipe.consumer_wait(acc_cons_st2)
# --- Output epilogue ---
tCtO_base = cute.make_tensor(tmem_ptr + self.tmem_o0_offset, tCtO_fake.layout)
c_grp = pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id))
c_pipe = pipeline.PipelineTmaStore.create(num_stages=self.num_c_stage, producer_group=c_grp)
acc_cons_st2 = utils.gemm.sm100.epilogue_tma_store(
self, tidx, warp_idx, tma_c, tCtO_base, sC, tCgC,
epi_tile, 0, const_expr(lambda x: x), (0,0,0), acc_cons_st2, acc_pipe, c_pipe)
c_pipe.producer_tail()
acc_pipe.consumer_release(acc_cons_st2)
tmem.relinquish_alloc_permit()
tmem.free(tmem_ptr)
def test():
torch.manual_seed(42)
m, n, head_dim = 128, 128, 64
q = torch.randn(m, head_dim, 1, dtype=torch.bfloat16, device='cuda')
k = torch.randn(n, head_dim, 1, dtype=torch.bfloat16, device='cuda')
v_base = torch.randn(head_dim, n, dtype=torch.bfloat16, device='cuda')
v = v_base.as_strided((head_dim, n), (1, head_dim)).unsqueeze(-1)
c = torch.zeros(m, head_dim, 1, dtype=torch.bfloat16, device='cuda')
qf = q[:,:,0].float(); kf = k[:,:,0].float(); vf = v_base.float()
ref = qf @ kf.T @ vf.T
import cutlass.torch as ct
mQ = ct.from_dlpack(q).mark_layout_dynamic(leading_dim=ct.get_leading_dim(q))
mK = ct.from_dlpack(k).mark_layout_dynamic(leading_dim=ct.get_leading_dim(k))
mV = ct.from_dlpack(v).mark_layout_dynamic(leading_dim=ct.get_leading_dim(v))
mC = ct.from_dlpack(c).mark_layout_dynamic(leading_dim=ct.get_leading_dim(c))
stream = cuda.CUstream(torch.cuda.current_stream().cuda_stream)
kernel = StageBIdentityKernel(mma_tiler_mn=(128, 128), use_2cta_instrs=False, use_tma_store=True)
print('Compiling...', flush=True)
compiled = cute.compile(kernel, mQ, mK, mV, mC, stream)
print('Running...', flush=True)
compiled(mQ, mK, mV, mC, stream)
torch.cuda.synchronize()
out = c[:,:,0].float()
cos = torch.nn.functional.cosine_similarity(out.flatten().unsqueeze(0), ref.flatten().unsqueeze(0)).item()
max_err = (out - ref).abs().max().item()
print('Stage B v26: Reuse acc_pipe for 2-phase sync, V MN-major')
print(' Cosine: {:.6f}, Max error: {:.6f}'.format(cos, max_err))
print(' {}'.format('PASS' if cos >= 0.99 else 'FAIL'))
if __name__ == '__main__':
test()

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tests/test_stage_b_v27.py Normal file
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"""
Stage B v27: Based on v20 with Bug 1 fix (V MN-major).
Fixes over v20:
1. V MN-major + pv_mma uses v_major
2. PipelineTmaStore (not TmaStorePipeline)
3. TMA warp does NOT call tmem.wait_for_alloc
4. mma_si PipelineUmmaAsync without cta_layout_vmnk (like FMHA)
"""
import torch, cutlass, cutlass.cute as cute, cutlass.utils as utils, cutlass.pipeline as pipeline
from cutlass.cute.nvgpu import cpasync, tcgen05
from cutlass import Float32, BFloat16, Int32, Boolean, const_expr
from cutlass.utils import LayoutEnum
from cutlass.utils.tmem_allocator import find_tmem_tensor_col_offset
import cuda.bindings.driver as cuda
class StageBIdentitySoftmax:
def __init__(self, mma_tiler_mn, use_2cta_instrs=False, use_tma_store=True):
self.acc_dtype = Float32; self.qk_acc_dtype = Float32
self.q_dtype = BFloat16; self.o_dtype = BFloat16; self.c_dtype = BFloat16
self.use_2cta_instrs = use_2cta_instrs; self.use_tma_store = use_tma_store
self.mma_tiler_mn = mma_tiler_mn; self.mma_tiler = (*mma_tiler_mn, 1)
self.cluster_shape_mn = (1, 1)
self.cta_group = tcgen05.CtaGroup.TWO if use_2cta_instrs else tcgen05.CtaGroup.ONE
self.epilogue_warp_id = (0, 1, 2, 3)
self.mma_warp_id = 4; self.tma_warp_id = 5
self.threads_per_cta = 192
self.epilog_sync_bar_id = 1; self.tmem_alloc_sync_bar_id = 2; self.tmem_dealloc_sync_bar_id = 3
self.num_c_stage = 2
def _setup(self, qk_mma, pv_mma):
qk_inst_k = cute.size(qk_mma.shape_mnk, mode=[2])
self.qk_mma_tiler = (*self.mma_tiler_mn, qk_inst_k * 4)
self.pv_mma_tiler = (self.qk_mma_tiler[0], self.qk_mma_tiler[2], self.qk_mma_tiler[1])
self.mma_tiler = self.qk_mma_tiler
print(f"[v27] qk_mma_tiler = {self.qk_mma_tiler}")
print(f"[v27] pv_mma_tiler = {self.pv_mma_tiler}")
self.cta_tile_shape_mnk = (
self.qk_mma_tiler[0] // cute.size(qk_mma.thr_id.shape),
self.qk_mma_tiler[1],
self.qk_mma_tiler[2],
)
self.cluster_layout_vmnk = cute.tiled_divide(cute.make_layout((1,1,1)), (qk_mma.thr_id.shape,))
self.epi_tile = utils.sm100.compute_epilogue_tile_shape(
self.cta_tile_shape_mnk, self.use_2cta_instrs, self.c_layout, self.o_dtype)
self.num_ab_stage = 1; self.num_acc_stage = 1
self.a_smem_s = utils.sm100.make_smem_layout_a(qk_mma, self.mma_tiler, self.q_dtype, 1)
self.b_smem_s = utils.sm100.make_smem_layout_b(qk_mma, self.mma_tiler, self.b_dtype, 1)
self.v_smem_s = utils.sm100.make_smem_layout_b(pv_mma, self.pv_mma_tiler, self.b_dtype, 1)
self.p_tmem_s = utils.sm100.make_smem_layout_a(pv_mma, self.pv_mma_tiler, self.q_dtype, 1)
self.c_smem_s = utils.sm100.make_smem_layout_epi(self.o_dtype, self.c_layout, self.epi_tile, 2)
qk_thr = qk_mma.get_slice(0)
qk_acc_shape = qk_thr.partition_shape_C(self.qk_mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
s_cols = find_tmem_tensor_col_offset(tStS)
pv_thr = pv_mma.get_slice(0)
pv_acc_shape = pv_thr.partition_shape_C(self.pv_mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
o_cols = find_tmem_tensor_col_offset(tOtO)
self.tilePlikeFP32 = self.qk_mma_tiler[1] // Float32.width * self.o_dtype.width
self.tmem_s0_offset = 0
self.tmem_p0_offset = 32
self.tmem_o0_offset = s_cols
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, self.num_acc_stage))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, self.num_acc_stage))
self.num_tmem_alloc_cols = utils.get_num_tmem_alloc_cols([tCtS_fake, tCtO_fake], arch="sm_100")
a_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
b_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
self.num_tma_load_bytes = (
cute.size_in_bytes(self.q_dtype, a_smem) + cute.size_in_bytes(self.b_dtype, b_smem)
) * cute.size(qk_mma.thr_id.shape)
@cute.jit
def __call__(self, q: cute.Tensor, k: cute.Tensor, v: cute.Tensor, c: cute.Tensor, stream: cuda.CUstream):
self.q_dtype = q.element_type; self.b_dtype = k.element_type
self.o_dtype = c.element_type; self.c_dtype = self.o_dtype
self.a_major = LayoutEnum.from_tensor(q).mma_major_mode()
self.b_major = LayoutEnum.from_tensor(k).mma_major_mode()
self.v_major = LayoutEnum.from_tensor(v).mma_major_mode()
self.c_layout = LayoutEnum.from_tensor(c)
print(f"[v27] a_major (Q) = {self.a_major}")
print(f"[v27] b_major (K) = {self.b_major}")
print(f"[v27] v_major (V) = {self.v_major}")
qk_mma = utils.sm100.make_trivial_tiled_mma(
self.q_dtype, self.b_dtype, self.a_major, self.b_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.SMEM)
pv_mma = utils.sm100.make_trivial_tiled_mma(
self.q_dtype, self.b_dtype, cute.nvgpu.OperandMajorMode.K, self.v_major,
self.qk_acc_dtype, self.cta_group, self.mma_tiler_mn, tcgen05.OperandSource.TMEM)
self._setup(qk_mma, pv_mma)
q_smem = cute.slice_(self.a_smem_s, (None, None, None, 0))
k_smem = cute.slice_(self.b_smem_s, (None, None, None, 0))
v_smem = cute.slice_(self.v_smem_s, (None, None, None, 0))
tma_q, tma_tq = cute.nvgpu.make_tiled_tma_atom_A(
utils.sm100.cluster_shape_to_tma_atom_A(self.cluster_shape_mn, qk_mma.thr_id),
q, q_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
tma_k, tma_tk = cute.nvgpu.make_tiled_tma_atom_B(
utils.sm100.cluster_shape_to_tma_atom_B(self.cluster_shape_mn, qk_mma.thr_id),
k, k_smem, self.mma_tiler, qk_mma, self.cluster_layout_vmnk.shape)
tma_v, tma_tv = cute.nvgpu.make_tiled_tma_atom_B(
utils.sm100.cluster_shape_to_tma_atom_B(self.cluster_shape_mn, pv_mma.thr_id),
v, v_smem, self.pv_mma_tiler, pv_mma, self.cluster_layout_vmnk.shape)
epi_smem = cute.select(self.c_smem_s, mode=[0, 1])
tma_c, tma_tc = cpasync.make_tiled_tma_atom(cpasync.CopyBulkTensorTileS2GOp(), c, epi_smem, self.epi_tile)
self._kernel(qk_mma, pv_mma, tma_q, tma_tq, tma_k, tma_tk, tma_v, tma_tv,
tma_c, tma_tc, self.cluster_layout_vmnk,
self.a_smem_s, self.b_smem_s, self.v_smem_s, self.p_tmem_s, self.c_smem_s, self.epi_tile
).launch(grid=(1,1,1), block=[self.threads_per_cta,1,1], stream=stream)
@cute.kernel
def _kernel(self, qk_mma, pv_mma, tma_q, mQ, tma_k, mK, tma_v, mV,
tma_c, mC, cl_vmnk, a_smem_s, b_smem_s, v_smem_s, p_tmem_s, c_smem_s, epi_tile):
warp_idx = cute.arch.make_warp_uniform(cute.arch.warp_idx())
tidx, _, _ = cute.arch.thread_idx()
use_2cta = cute.size(qk_mma.thr_id.shape) == 2
if warp_idx == self.tma_warp_id:
cpasync.prefetch_descriptor(tma_q); cpasync.prefetch_descriptor(tma_k)
cpasync.prefetch_descriptor(tma_v); cpasync.prefetch_descriptor(tma_c)
@cute.struct
class SS:
ab_bar: cute.struct.MemRange[cutlass.Int64, self.num_ab_stage * 2]
mma_si_bar: cute.struct.MemRange[cutlass.Int64, 2]
acc_bar: cute.struct.MemRange[cutlass.Int64, self.num_acc_stage * 2]
tmem_dealloc: cutlass.Int64
holding: cutlass.Int32
smem = utils.SmemAllocator(); st = smem.allocate(SS)
ab_p, ab_c = pipeline.PipelineTmaUmma.create(
barrier_storage=st.ab_bar.data_ptr(), num_stages=self.num_ab_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 1),
tx_count=self.num_tma_load_bytes, cta_layout_vmnk=cl_vmnk, defer_sync=True
).make_participants()
# mma_si pipeline — NO cta_layout_vmnk (matches FMHA)
mma_si_prod, mma_si_cons = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.mma_si_bar.data_ptr(), num_stages=1,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id)),
).make_participants()
acc_pipe = pipeline.PipelineUmmaAsync.create(
barrier_storage=st.acc_bar.data_ptr(), num_stages=self.num_acc_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread),
consumer_group=pipeline.CooperativeGroup(
pipeline.Agent.Thread, len(self.epilogue_warp_id) * (2 if use_2cta else 1)),
cta_layout_vmnk=cl_vmnk, defer_sync=True)
tmem_bar = pipeline.NamedBarrier(barrier_id=self.tmem_alloc_sync_bar_id,
num_threads=32 * len((self.mma_warp_id, *self.epilogue_warp_id)))
tmem = utils.TmemAllocator(st.holding.ptr, barrier_for_retrieve=tmem_bar,
allocator_warp_id=self.epilogue_warp_id[0], is_two_cta=use_2cta,
two_cta_tmem_dealloc_mbar_ptr=st.tmem_dealloc.ptr)
pipeline.pipeline_init_arrive(cluster_shape_mn=cl_vmnk, is_relaxed=True)
sQ = smem.allocate_tensor(element_type=self.q_dtype, layout=a_smem_s.outer, byte_alignment=128, swizzle=a_smem_s.inner)
sK = smem.allocate_tensor(element_type=self.b_dtype, layout=b_smem_s.outer, byte_alignment=128, swizzle=b_smem_s.inner)
sV = smem.allocate_tensor(element_type=self.b_dtype, layout=v_smem_s.outer, byte_alignment=128, swizzle=v_smem_s.inner)
sC = smem.allocate_tensor(element_type=self.o_dtype, layout=c_smem_s.outer, byte_alignment=128, swizzle=c_smem_s.inner)
gQ = cute.local_tile(mQ, cute.slice_(self.qk_mma_tiler, (None,0,None)), (None,None,None))
gK = cute.local_tile(mK, cute.slice_(self.qk_mma_tiler, (0,None,None)), (None,None,None))
gC = cute.local_tile(mC, cute.slice_(self.qk_mma_tiler, (None,None,0)), (None,None,None))
k_cnt = cute.size(gQ, mode=[3])
qk_thr = qk_mma.get_slice(0)
pv_thr = pv_mma.get_slice(0)
tCgQ = qk_thr.partition_A(gQ); tCgK = qk_thr.partition_B(gK); tCgC = qk_thr.partition_C(gC)
a_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,0,None,0)).shape)
tAsQ, tAgQ = cpasync.tma_partition(tma_q, 0, a_lay, cute.group_modes(sQ,0,3), cute.group_modes(tCgQ,0,3))
b_lay = cute.make_layout(cute.slice_(cl_vmnk, (0,None,0,0)).shape)
tBsK, tBgK = cpasync.tma_partition(tma_k, 0, b_lay, cute.group_modes(sK,0,3), cute.group_modes(tCgK,0,3))
tAgQ = tAgQ[(None,0,None,0)]; tBgK = tBgK[(None,0,None,0)]
gV = cute.local_tile(mV, cute.slice_(self.pv_mma_tiler, (0,None,None)), (None,None,None))
tCgV = pv_thr.partition_B(gV)
tVsV, tVgV = cpasync.tma_partition(tma_v, 0, b_lay, cute.group_modes(sV,0,3), cute.group_modes(tCgV,0,3))
tVgV = tVgV[(None,0,None,0)]
tCrQ = qk_mma.make_fragment_A(sQ); tCrK = qk_mma.make_fragment_B(sK)
tCrV = pv_mma.make_fragment_B(sV)
qk_acc_shape = qk_thr.partition_shape_C(self.qk_mma_tiler[:2])
tStS = qk_thr.make_fragment_C(qk_acc_shape)
tStS0 = cute.make_tensor(tStS.iterator + self.tmem_s0_offset, tStS.layout)
pv_acc_shape = pv_thr.partition_shape_C(self.pv_mma_tiler[:2])
tOtO = pv_thr.make_fragment_C(pv_acc_shape)
tOtO0 = cute.make_tensor(tOtO.iterator + self.tmem_o0_offset, tOtO.layout)
tP = cute.make_tensor(tStS.iterator, p_tmem_s.outer)
tOrP_base = pv_thr.make_fragment_A(tP)
tOrP = tOrP_base[(None, None, None, 0)]
tOrP0 = cute.make_tensor(
tOrP.iterator + self.qk_acc_dtype.width // self.q_dtype.width * self.tmem_p0_offset,
tOrP.layout)
tCtS_fake = qk_mma.make_fragment_C(cute.append(qk_acc_shape, self.num_acc_stage))
tCtO_fake = pv_mma.make_fragment_C(cute.append(pv_acc_shape, self.num_acc_stage))
pipeline.pipeline_init_wait(cluster_shape_mn=cl_vmnk)
# ═══ TMA LOAD WARP (no tmem.wait_for_alloc) ═══
if warp_idx == self.tma_warp_id:
ab_p.reset(); peek = ab_p.try_acquire()
for kt in cutlass.range(k_cnt, unroll=1):
h = ab_p.acquire_and_advance(peek)
cute.copy(tma_q, tAgQ[(None,h.count)], tAsQ[(None,h.index)], tma_bar_ptr=h.barrier)
cute.copy(tma_k, tBgK[(None,h.count)], tBsK[(None,h.index)], tma_bar_ptr=h.barrier)
cute.copy(tma_v, tVgV[(None,h.count)], tVsV[(None,h.index)], tma_bar_ptr=h.barrier)
peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_p.try_acquire()
ab_p.tail()
# ═══ MMA WARP ═══
if warp_idx == self.mma_warp_id:
if tidx == 128: print("[MMA] before tmem.wait_for_alloc")
tmem.wait_for_alloc()
if tidx == 128: print("[MMA] after tmem.wait_for_alloc")
ab_c.reset(); peek = ab_c.try_wait()
if tidx == 128: print("[MMA] before mma_si acquire 1")
s0_handle = mma_si_prod.acquire_and_advance()
if tidx == 128: print("[MMA] after mma_si_prod acquire 1")
if tidx == 128: print("[MMA] after mma_si_prod acquire 2 (wait for softmax)")
acc_prod_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Producer, self.num_acc_stage)
acc_pipe.producer_acquire(acc_prod_st)
qk_mma.set(tcgen05.Field.ACCUMULATE, False)
for kt in range(k_cnt):
h = ab_c.wait_and_advance(peek)
nblk = cute.size(tCrQ, mode=[2])
for kb in cutlass.range(nblk, unroll_full=True):
cute.gemm(qk_mma, tStS0, tCrQ[(None,None,kb,h.index)], tCrK[(None,None,kb,h.index)], tStS0)
qk_mma.set(tcgen05.Field.ACCUMULATE, True)
h.release(); peek = cutlass.Boolean(1)
if h.count+1<k_cnt: peek = ab_c.try_wait()
cute.arch.fence_view_async_tmem_store()
s0_handle.commit()
if tidx == 128: print("[MMA] after s0_handle commit")
if tidx == 128: print("[MMA] before mma_si acquire 1")
s0_handle = mma_si_prod.acquire_and_advance()
if tidx == 128: print("[MMA] after mma_si_prod acquire 1")
if tidx == 128: print("[MMA] after mma_si_prod acquire 2 (wait for softmax)")
pv_mma.set(tcgen05.Field.ACCUMULATE, True)
tCrV_s = tCrV[(None, None, None, 0)]
nblk_pv = cute.size(tOrP0, mode=[2])
for kb in cutlass.range(nblk_pv, unroll_full=True):
cute.gemm(pv_mma, tOtO0, tOrP0[(None,None,kb)], tCrV_s[(None,None,kb)], tOtO0)
acc_pipe.producer_commit(acc_prod_st)
acc_prod_st.advance()
acc_pipe.producer_tail(acc_prod_st)
# ═══ EPILOGUE WARPS ═══
if warp_idx < self.mma_warp_id:
tmem.allocate(self.num_tmem_alloc_cols)
tmem.wait_for_alloc()
if tidx == 128: print("[MMA] after tmem.wait_for_alloc")
tmem_ptr = tmem.retrieve_ptr(self.qk_acc_dtype)
sfw_idx = tidx % (32 * len(self.epilogue_warp_id))
tmem_load_atom = cute.make_copy_atom(
tcgen05.copy.Ld32x32bOp(tcgen05.copy.Repetition(32)), self.qk_acc_dtype)
tiled_tmem_load = tcgen05.make_tmem_copy(tmem_load_atom, tStS0)
thr_load = tiled_tmem_load.get_slice(sfw_idx)
tTMEM_LOADtS = thr_load.partition_S(tStS0)
cS = cute.make_identity_tensor((self.qk_mma_tiler[0], self.qk_mma_tiler[1]))
tScS = qk_thr.partition_C(cS)
tTMEM_LOADcS = thr_load.partition_D(tScS)
tStS_P_layout = cute.composition(tStS.layout, cute.make_layout((128, self.tilePlikeFP32)))
tStS_P = cute.make_tensor(tStS.iterator + self.tmem_p0_offset, tStS_P_layout)
tmem_store_atom = cute.make_copy_atom(
tcgen05.copy.St32x32bOp(tcgen05.copy.Repetition(32)), self.qk_acc_dtype)
tiled_tmem_store = tcgen05.make_tmem_copy(tmem_store_atom, tStS_P)
thr_store = tiled_tmem_store.get_slice(sfw_idx)
tTMEM_STOREtS_x4 = thr_store.partition_D(tStS_P)
tScS_P_layout = cute.composition(tScS.layout, cute.make_layout((128, self.tilePlikeFP32)))
tScS_P = cute.make_tensor(tScS.iterator, tScS_P_layout)
tTMEM_STOREcS = thr_store.partition_S(tScS_P)
if tidx == 0: print("[EPI] before mma_si_cons wait")
si_handle = mma_si_cons.wait_and_advance()
tTMEM_LOADrS = cute.make_rmem_tensor(tTMEM_LOADcS.shape, self.qk_acc_dtype)
cute.copy(tiled_tmem_load, tTMEM_LOADtS, tTMEM_LOADrS)
tTMEM_STORErS_x4 = cute.make_rmem_tensor(tTMEM_STOREcS.shape, self.qk_acc_dtype)
tTMEM_STORErS_x4_e = cute.make_tensor(
cute.recast_ptr(tTMEM_STORErS_x4.iterator, dtype=self.q_dtype),
tTMEM_LOADrS.layout)
frg_cnt = 4
frg_tile = cute.size(tTMEM_LOADrS) // frg_cnt
tTMEM_LOADrS_frg = cute.logical_divide(tTMEM_LOADrS, cute.make_layout(frg_tile))
tTMEM_STORErS_x4_e_frg = cute.logical_divide(
tTMEM_STORErS_x4_e, cute.make_layout(frg_tile))
for j in range(frg_cnt):
s_vec = tTMEM_LOADrS_frg[None, j].load()
tTMEM_STORErS_x4_e_frg[None, j].store(s_vec.to(self.q_dtype))
cute.copy(tiled_tmem_store, tTMEM_STORErS_x4, tTMEM_STOREtS_x4)
cute.arch.fence_view_async_tmem_store()
if tidx == 0: print("[EPI] before si release")
si_handle.release()
tCtO_base = cute.make_tensor(tmem_ptr + self.tmem_o0_offset, tCtO_fake.layout)
acc_cons_st = pipeline.make_pipeline_state(pipeline.PipelineUserType.Consumer, self.num_acc_stage)
c_grp = pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id))
c_pipe = pipeline.PipelineTmaStore.create(num_stages=self.num_c_stage, producer_group=c_grp)
acc_cons_st = utils.gemm.sm100.epilogue_tma_store(
self, tidx, warp_idx, tma_c, tCtO_base, sC, tCgC,
epi_tile, 0, const_expr(lambda x: x), (0,0,0), acc_cons_st, acc_pipe, c_pipe)
c_pipe.producer_tail()
tmem.relinquish_alloc_permit()
tmem.free(tmem_ptr)
def test():
torch.manual_seed(42)
m, n, head_dim = 128, 128, 64
q = torch.randn(m, head_dim, 1, dtype=torch.bfloat16, device='cuda')
k = torch.randn(n, head_dim, 1, dtype=torch.bfloat16, device='cuda')
v_base = torch.randn(head_dim, n, dtype=torch.bfloat16, device='cuda')
v = v_base.as_strided((head_dim, n), (1, head_dim)).unsqueeze(-1)
c = torch.zeros(m, head_dim, 1, dtype=torch.bfloat16, device='cuda')
qf = q[:,:,0].float(); kf = k[:,:,0].float(); vf = v_base.float()
ref = qf @ kf.T @ vf.T
import cutlass.torch as ct
mQ = ct.from_dlpack(q).mark_layout_dynamic(leading_dim=ct.get_leading_dim(q))
mK = ct.from_dlpack(k).mark_layout_dynamic(leading_dim=ct.get_leading_dim(k))
mV = ct.from_dlpack(v).mark_layout_dynamic(leading_dim=ct.get_leading_dim(v))
mC = ct.from_dlpack(c).mark_layout_dynamic(leading_dim=ct.get_leading_dim(c))
stream = cuda.CUstream(torch.cuda.current_stream().cuda_stream)
kernel = StageBIdentitySoftmax(mma_tiler_mn=(128, 128), use_2cta_instrs=False, use_tma_store=True)
print('Compiling...', flush=True)
compiled = cute.compile(kernel, mQ, mK, mV, mC, stream)
print('Running...', flush=True)
compiled(mQ, mK, mV, mC, stream)
torch.cuda.synchronize()
out = c[:,:,0].float()
cos = torch.nn.functional.cosine_similarity(out.flatten().unsqueeze(0), ref.flatten().unsqueeze(0)).item()
max_err = (out - ref).abs().max().item()
print('Stage B v27: V MN-major + no cta_layout on mma_si')
print(' Cosine: {:.6f}, Max error: {:.6f}'.format(cos, max_err))
print(' {}'.format('PASS' if cos >= 0.99 else 'FAIL'))
if __name__ == '__main__':
test()