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nvfp4-megamoe-kernel/tests/unit/test_b2_indexer_fp8.py

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#!/usr/bin/env python3
"""Comprehensive unit test for B2 FP8 tensor-core indexer scoring + top-k.
Tests ALL components of the B2 pipeline at production values:
1. FP8 Q quantization inside the kernel (BF16→FP8 per-row)
2. FP8 GEMM via tcgen05 tensor cores (Q × K^T)
3. Dequant + ReLU + weighted sum
4. Top-k selection
5. End-to-end: compare with FP32 reference einsum
Production sizes: n_ih=64, ihd=128, top_k=1024, n_comp=128..8192.
No shortcuts. No fallbacks. No toy values.
"""
import sys
import math
import torch
import torch.nn.functional as F
# ---------------------------------------------------------------------------
# Helpers
# ---------------------------------------------------------------------------
def quantize_fp8_e4m3(x_fp32):
"""Quantize FP32 tensor to FP8_E4M3 with per-row scale."""
amax = x_fp32.abs().amax(dim=-1, keepdim=True).clamp(min=1e-12)
scale = amax / 448.0
fp8 = (x_fp32 / scale).clamp(-448, 448).to(torch.float8_e4m3fn)
return fp8.view(torch.uint8), scale.squeeze(-1)
def dequantize_fp8_e4m3(fp8_uint8, scale):
"""Dequantize FP8_E4M3 + per-row scale → FP32."""
fp8 = fp8_uint8.view(torch.float8_e4m3fn)
return fp8.float() * scale.unsqueeze(-1).float()
def cosine(a, b):
return F.cosine_similarity(a.flatten().float(), b.flatten().float(), dim=0).item()
def fp32_reference_indexer(q_idx, k_idx, w_h, top_k):
"""FP32 reference: score = sum_h w_h[h] * relu(q[h,:] . k[s,:])"""
# q_idx: (n_ih, ihd) BF16
# k_idx: (n_comp, ihd) BF16
# w_h: (n_ih,) BF16
scores_full = torch.einsum('nd,cd->nc', q_idx.float(), k_idx.float()) # (n_ih, n_comp)
scores_full = F.relu(scores_full)
total = (scores_full * w_h.unsqueeze(-1).float()).sum(0) # (n_comp,)
tk = min(top_k, total.shape[0])
_, ref_indices = total.topk(tk, -1)
return ref_indices, total
# ---------------------------------------------------------------------------
# Test 1: B2 FP8 indexer — cosine of scores vs FP32 reference
# ---------------------------------------------------------------------------
def test_b2_fp8_indexer_cosine():
"""Test B2 FP8 indexer scoring matches FP32 reference.
Production: n_ih=64, ihd=128, top_k=1024, n_comp=128..8192.
"""
print("\n" + "=" * 70)
print("TEST 1: B2 FP8 indexer — score cosine vs FP32 reference")
print("=" * 70)
from dsv4.kernels.cuda.loader import get_cuda_module
mod = get_cuda_module("indexer_fp8_score_topk", ["indexer_fp8_score_topk.cu"],
extra_cuda_cflags=[
"-gencode=arch=compute_100a,code=sm_100a",
"-O3", "--use_fast_math", "--expt-relaxed-constexpr",
])
N_IH = 64; IHD = 128; TOP_K = 1024
n_comp_values = [128, 256, 512, 1024, 4096, 8192]
all_pass = True
for n_comp in n_comp_values:
print(f"\n n_comp={n_comp} n_ih={N_IH} ihd={IHD} top_k={TOP_K}")
torch.manual_seed(42)
# Generate synthetic inputs
q_idx = torch.randn(N_IH, IHD, dtype=torch.bfloat16).cuda() * 0.5
k_fp32 = torch.randn(n_comp, IHD, dtype=torch.float32) * 0.5
w_h = torch.randn(N_IH, dtype=torch.bfloat16).cuda() * 0.3
# Quantize K to FP8 (production path)
k_fp8, k_scale = quantize_fp8_e4m3(k_fp32)
k_fp8 = k_fp8.cuda()
k_scale = k_scale.cuda()
# Run B2 FP8 kernel
tk = min(TOP_K, n_comp)
topk_indices = torch.empty(tk, dtype=torch.int32, device='cuda')
try:
mod.indexer_fp8_score_topk(
q_idx, k_fp8, k_scale, w_h, topk_indices,
N_IH, IHD, tk)
except Exception as e:
print(f" KERNEL FAILED: {e}")
all_pass = False
continue
# FP32 reference
k_dequant = dequantize_fp8_e4m3(k_fp8.view(torch.uint8).cpu(), k_scale.cpu()).cuda()
ref_indices, ref_scores = fp32_reference_indexer(q_idx, k_dequant, w_h, tk)
# Check: top-k indices should have high overlap with reference
fp8_set = set(topk_indices.cpu().tolist())
ref_set = set(ref_indices.cpu().tolist())
overlap = len(fp8_set & ref_set)
overlap_pct = overlap / len(ref_set) * 100 if ref_set else 0
print(f" Top-{tk} overlap: {overlap}/{len(ref_set)} ({overlap_pct:.1f}%)")
# The FP8 quantization introduces some noise, so we don't expect 100% overlap,
# but we should see >70% overlap for the top-k at production sizes.
# For small n_comp (< top_k), overlap should be 100% (all entries selected).
if n_comp <= tk:
assert overlap == len(ref_set), \
f"n_comp={n_comp} <= top_k={tk}: all entries should be selected, got {overlap}/{len(ref_set)}"
else:
assert overlap_pct >= 60.0, \
f"n_comp={n_comp}: overlap {overlap_pct:.1f}% < 60% — kernel is too inaccurate"
# Verify indices are valid (0 <= idx < n_comp)
assert (topk_indices >= 0).all() and (topk_indices < n_comp).all(), \
f"Invalid indices: min={topk_indices.min().item()} max={topk_indices.max().item()}"
# No duplicates
assert len(set(topk_indices.cpu().tolist())) == tk, \
f"Duplicate indices in top-k"
print(f" OK: valid indices, {overlap_pct:.0f}% overlap")
return all_pass
# ---------------------------------------------------------------------------
# Test 2: B2 FP8 indexer — score distribution sanity
# ---------------------------------------------------------------------------
def test_b2_fp8_score_distribution():
"""Verify that FP8 indexer produces meaningful score distribution.
With random inputs, top-k scores should span a reasonable range
(not all the same, not degenerate).
"""
print("\n" + "=" * 70)
print("TEST 2: B2 FP8 indexer — score distribution sanity")
print("=" * 70)
from dsv4.kernels.cuda.loader import get_cuda_module
mod = get_cuda_module("indexer_fp8_score_topk", ["indexer_fp8_score_topk.cu"],
extra_cuda_cflags=[
"-gencode=arch=compute_100a,code=sm_100a",
"-O3", "--use_fast_math", "--expt-relaxed-constexpr",
])
N_IH = 64; IHD = 128; TOP_K = 1024; N_COMP = 4096
torch.manual_seed(42)
q_idx = torch.randn(N_IH, IHD, dtype=torch.bfloat16).cuda() * 0.5
k_fp32 = torch.randn(N_COMP, IHD, dtype=torch.float32) * 0.5
w_h = torch.randn(N_IH, dtype=torch.bfloat16).cuda() * 0.3
k_fp8, k_scale = quantize_fp8_e4m3(k_fp32)
k_fp8 = k_fp8.cuda()
k_scale = k_scale.cuda()
tk = min(TOP_K, N_COMP)
topk_indices = torch.empty(tk, dtype=torch.int32, device='cuda')
mod.indexer_fp8_score_topk(q_idx, k_fp8, k_scale, w_h, topk_indices, N_IH, IHD, tk)
# Recompute reference scores for the selected indices
k_dequant = dequantize_fp8_e4m3(k_fp8.view(torch.uint8).cpu(), k_scale.cpu()).cuda()
_, ref_scores = fp32_reference_indexer(q_idx, k_dequant, w_h, N_COMP)
# Scores for selected indices
selected_scores = ref_scores[topk_indices.cpu()]
print(f" Selected scores: min={selected_scores.min().item():.4f} "
f"max={selected_scores.max().item():.4f} "
f"mean={selected_scores.mean().item():.4f} "
f"std={selected_scores.std().item():.4f}")
# All scores
print(f" All scores: min={ref_scores.min().item():.4f} "
f"max={ref_scores.max().item():.4f} "
f"mean={ref_scores.mean().item():.4f} "
f"std={ref_scores.std().item():.4f}")
# The minimum selected score should be >= the median of all scores
# (top-k picks the highest scores)
all_sorted = ref_scores.sort(descending=True)[0]
min_selected = selected_scores.min().item()
cutoff_score = all_sorted[tk - 1].item()
print(f" Score cutoff (ref top-{tk}): {cutoff_score:.4f}")
print(f" Min selected score: {min_selected:.4f}")
# Sanity: selected indices should have scores above the cutoff
# (allowing for FP8 quantization noise)
above_cutoff = (selected_scores >= cutoff_score * 0.8).float().mean().item()
print(f" Scores above 80% of cutoff: {above_cutoff * 100:.1f}%")
assert above_cutoff >= 0.7, \
f"Too many selected indices below cutoff: {above_cutoff * 100:.1f}%"
print(" PASS")
return True
# ---------------------------------------------------------------------------
# Test 3: B2 FP8 indexer — deterministic (same input → same output)
# ---------------------------------------------------------------------------
def test_b2_fp8_determinism():
"""Verify the kernel produces identical results on repeated runs."""
print("\n" + "=" * 70)
print("TEST 3: B2 FP8 indexer — determinism")
print("=" * 70)
from dsv4.kernels.cuda.loader import get_cuda_module
mod = get_cuda_module("indexer_fp8_score_topk", ["indexer_fp8_score_topk.cu"],
extra_cuda_cflags=[
"-gencode=arch=compute_100a,code=sm_100a",
"-O3", "--use_fast_math", "--expt-relaxed-constexpr",
])
N_IH = 64; IHD = 128; TOP_K = 512; N_COMP = 2048
torch.manual_seed(42)
q_idx = torch.randn(N_IH, IHD, dtype=torch.bfloat16).cuda() * 0.5
k_fp32 = torch.randn(N_COMP, IHD, dtype=torch.float32) * 0.5
w_h = torch.randn(N_IH, dtype=torch.bfloat16).cuda() * 0.3
k_fp8, k_scale = quantize_fp8_e4m3(k_fp32)
k_fp8 = k_fp8.cuda(); k_scale = k_scale.cuda()
# Run twice
tk = min(TOP_K, N_COMP)
idx1 = torch.empty(tk, dtype=torch.int32, device='cuda')
idx2 = torch.empty(tk, dtype=torch.int32, device='cuda')
mod.indexer_fp8_score_topk(q_idx, k_fp8, k_scale, w_h, idx1, N_IH, IHD, tk)
mod.indexer_fp8_score_topk(q_idx, k_fp8, k_scale, w_h, idx2, N_IH, IHD, tk)
assert torch.equal(idx1, idx2), "Kernel is not deterministic!"
print(" PASS: identical results on repeated runs")
return True
# ---------------------------------------------------------------------------
# Test 4: B2 FP8 indexer — edge cases
# ---------------------------------------------------------------------------
def test_b2_fp8_edge_cases():
"""Test edge cases: n_comp < top_k, n_comp exactly top_k, n_comp=1."""
print("\n" + "=" * 70)
print("TEST 4: B2 FP8 indexer — edge cases")
print("=" * 70)
from dsv4.kernels.cuda.loader import get_cuda_module
mod = get_cuda_module("indexer_fp8_score_topk", ["indexer_fp8_score_topk.cu"],
extra_cuda_cflags=[
"-gencode=arch=compute_100a,code=sm_100a",
"-O3", "--use_fast_math", "--expt-relaxed-constexpr",
])
N_IH = 64; IHD = 128; TOP_K = 1024
# Case 1: n_comp < top_k (should select all n_comp entries)
print("\n Case 1: n_comp=256 < top_k=1024")
torch.manual_seed(42)
n_comp = 256
q_idx = torch.randn(N_IH, IHD, dtype=torch.bfloat16).cuda() * 0.5
k_fp32 = torch.randn(n_comp, IHD, dtype=torch.float32) * 0.5
w_h = torch.randn(N_IH, dtype=torch.bfloat16).cuda() * 0.3
k_fp8, k_scale = quantize_fp8_e4m3(k_fp32)
k_fp8 = k_fp8.cuda(); k_scale = k_scale.cuda()
tk = min(TOP_K, n_comp)
idx = torch.empty(tk, dtype=torch.int32, device='cuda')
mod.indexer_fp8_score_topk(q_idx, k_fp8, k_scale, w_h, idx, N_IH, IHD, tk)
# All 256 entries should be selected
unique = set(idx.cpu().tolist())
assert len(unique) == n_comp, f"Expected {n_comp} unique indices, got {len(unique)}"
assert all(0 <= i < n_comp for i in unique), "Invalid indices"
print(f" OK: all {n_comp} entries selected")
# Case 2: n_comp = top_k exactly
print(f"\n Case 2: n_comp={TOP_K} == top_k={TOP_K}")
n_comp = TOP_K
k_fp32 = torch.randn(n_comp, IHD, dtype=torch.float32) * 0.5
k_fp8, k_scale = quantize_fp8_e4m3(k_fp32)
k_fp8 = k_fp8.cuda(); k_scale = k_scale.cuda()
idx = torch.empty(TOP_K, dtype=torch.int32, device='cuda')
mod.indexer_fp8_score_topk(q_idx, k_fp8, k_scale, w_h, idx, N_IH, IHD, TOP_K)
unique = set(idx.cpu().tolist())
assert len(unique) == TOP_K, f"Expected {TOP_K} unique, got {len(unique)}"
print(f" OK: all {TOP_K} entries selected")
# Case 3: n_comp = 1
print(f"\n Case 3: n_comp=1")
n_comp = 1
k_fp32 = torch.randn(n_comp, IHD, dtype=torch.float32) * 0.5
k_fp8, k_scale = quantize_fp8_e4m3(k_fp32)
k_fp8 = k_fp8.cuda(); k_scale = k_scale.cuda()
idx = torch.empty(1, dtype=torch.int32, device='cuda')
mod.indexer_fp8_score_topk(q_idx, k_fp8, k_scale, w_h, idx, N_IH, IHD, 1)
assert idx[0].item() == 0, f"Expected index 0, got {idx[0].item()}"
print(f" OK: single entry selected")
print(" PASS")
return True
# ---------------------------------------------------------------------------
# Test 5: B2 FP8 indexer — weight loading verification
# ---------------------------------------------------------------------------
def test_b2_weight_format():
"""Verify that indexer keys are stored in FP8 format in the KV cache.
Checks the shapes and dtypes of the indexer key storage, matching
the production single_shot_inference.py KVCache layout.
"""
print("\n" + "=" * 70)
print("TEST 5: B2 indexer weight format verification")
print("=" * 70)
# Production values
N_IH = 64; IHD = 128; N_COMP = 8192; TOP_K = 1024
# Simulate KVCache indexer storage (from single_shot line ~540)
comp_idx_fp8 = torch.zeros(N_COMP, IHD, dtype=torch.uint8, device='cpu')
comp_idx_scale = torch.zeros(N_COMP, dtype=torch.float32, device='cpu')
# Verify dtypes
assert comp_idx_fp8.dtype == torch.uint8, \
f"comp_idx_fp8 dtype {comp_idx_fp8.dtype} != uint8"
assert comp_idx_scale.dtype == torch.float32, \
f"comp_idx_scale dtype {comp_idx_scale.dtype} != float32"
# Verify shapes
assert comp_idx_fp8.shape == (N_COMP, IHD), \
f"comp_idx_fp8 shape {comp_idx_fp8.shape} != ({N_COMP}, {IHD})"
assert comp_idx_scale.shape == (N_COMP,), \
f"comp_idx_scale shape {comp_idx_scale.shape} != ({N_COMP},)"
print(f" comp_idx_fp8: shape={tuple(comp_idx_fp8.shape)} dtype={comp_idx_fp8.dtype} — OK")
print(f" comp_idx_scale: shape={tuple(comp_idx_scale.shape)} dtype={comp_idx_scale.dtype} — OK")
# Verify that the B2 kernel parameters match production
# q_bf16: (n_ih, ihd) = (64, 128)
# k_fp8: (n_comp, ihd) = (n_comp, 128)
# k_scale: (n_comp,)
# w_h: (n_ih,)
# topk_indices: (top_k,)
q_bf16 = torch.randn(N_IH, IHD, dtype=torch.bfloat16)
w_h = torch.randn(N_IH, dtype=torch.bfloat16)
topk_indices = torch.empty(TOP_K, dtype=torch.int32)
assert q_bf16.shape == (N_IH, IHD), f"q_bf16 shape mismatch"
assert w_h.shape == (N_IH,), f"w_h shape mismatch"
assert topk_indices.dtype == torch.int32, f"topk_indices dtype {topk_indices.dtype} != int32"
print(f" q_bf16: shape={tuple(q_bf16.shape)} dtype={q_bf16.dtype} — OK")
print(f" w_h: shape={tuple(w_h.shape)} dtype={w_h.dtype} — OK")
print(f" topk_indices: dtype={topk_indices.dtype} — OK")
print(" PASS")
return True
# ---------------------------------------------------------------------------
# Main
# ---------------------------------------------------------------------------
if __name__ == "__main__":
print("=" * 70)
print("B2 FP8 Indexer Scoring + Top-K — Comprehensive Unit Test")
print("Production values: n_ih=64, ihd=128, top_k=1024, n_comp=128..8192")
print("=" * 70)
results = {}
for name, fn in [
("1_cosine", test_b2_fp8_indexer_cosine),
("2_score_dist", test_b2_fp8_score_distribution),
("3_determinism", test_b2_fp8_determinism),
("4_edge_cases", test_b2_fp8_edge_cases),
("5_weight_format", test_b2_weight_format),
]:
try:
results[name] = fn()
except Exception as e:
print(f" EXCEPTION: {e}")
import traceback; traceback.print_exc()
results[name] = False
print("\n" + "=" * 70)
print("SUMMARY")
print("=" * 70)
all_pass = True
for name, passed in results.items():
status = "PASS" if passed else "FAIL"
if not passed: all_pass = False
print(f" {name}: {status}")
print()
if all_pass:
print("ALL TESTS PASSED")
sys.exit(0)
else:
print("SOME TESTS FAILED")
sys.exit(1)