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fix: use paired atoms for correction_epilog + cute.copy TMA store

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biondizzle
2026-05-23 02:26:57 +00:00
parent e3d6d6eebf
commit b457d196af
1 changed files with 62 additions and 60 deletions
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122
tests/unit/test_fmha_v3_stage_c.py
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@@ -348,75 +348,77 @@ class FmhaV3StageCMulti:
final_o_bar.arrive_and_wait()
# === Correction epilog: one-way TMEM → reg → SMEM with normalize ===
# Replicates epilogue_tma_store logic with inv_row_sum multiply added.
# Uses get_tmem_load_op + get_smem_store_op paired atoms.
# NO TMEM round-trip — hand-constructed atoms corrupt data.
inv_row_sum = Float32(1.0) / row_sum
# Build TMEM→reg and reg→SMEM copies using paired atoms
tCtO_base = cute.make_tensor(tmem_ptr + self.tmem_o0_offset, tCtO_fake.layout)
tCtO = utils.gemm.sm100.transform_partitioned_tensor_layout(tCtO_base)
tCgC_t = utils.gemm.sm100.transform_partitioned_tensor_layout(tCgC)
tiled_copy_t2r, tTR_tO, tTR_rO = utils.gemm.sm100.epilogue_tmem_copy_and_partition(
self, tidx, tCtO, tCgC_t, epi_tile, self.use_2cta_instrs
epi_corr_tile_size = 32 * 8 // self.o_dtype.width # 16 for BF16
tOtO_epi = cute.logical_divide(tOtO0, cute.make_layout((128, epi_corr_tile_size)))
tmem_load_epi_atom = utils.sm100.get_tmem_load_op(
self.pv_mma_tiler, self.c_layout, self.o_dtype, self.acc_dtype,
(epi_tile[0], epi_corr_tile_size), self.use_2cta_instrs,
)
tTR_rC = cute.make_rmem_tensor(tTR_rO.shape, self.c_dtype)
tiled_copy_r2s, tRS_rC, tRS_sC = utils.gemm.sm100.epilogue_smem_copy_and_partition(
self, tiled_copy_t2r, tTR_rC, tidx, sC
tiled_tmem_load_epi = tcgen05.make_tmem_copy(tmem_load_epi_atom, tOtO_epi[(None, None), 0])
smem_store_epi_atom = utils.sm100.get_smem_store_op(
self.c_layout, self.o_dtype, self.acc_dtype, tiled_tmem_load_epi,
)
tCgC_epi = cute.flat_divide(tCgC_t, epi_tile)
bSG_sC, bSG_gC_part = cpasync.tma_partition(
tma_c, 0, cute.make_layout(1),
cute.group_modes(sC, 0, 2),
cute.group_modes(tCgC_epi, 0, 2),
)
epilog_sync_bar = pipeline.NamedBarrier(
tiled_smem_store_epi = cute.make_tiled_copy_D(smem_store_epi_atom, tiled_tmem_load_epi)
tOsO = pv_thr.partition_C(sC)
cO_epi = cute.make_identity_tensor((self.pv_mma_tiler[0], self.pv_mma_tiler[1]))
tOcO_epi = pv_thr.partition_C(cO_epi)
tOsO_epi = cute.logical_divide(tOsO, cute.make_layout((128, epi_corr_tile_size)))
tOcO_epi = cute.logical_divide(tOcO_epi, cute.make_layout((128, epi_corr_tile_size)))
thr_tmem_load_epi = tiled_tmem_load_epi.get_slice(sfw_idx)
tTMEM_LOADtO_epi = thr_tmem_load_epi.partition_S(tOtO_epi[(None, None), None])
tTMEM_LOADsO_epi = thr_tmem_load_epi.partition_D(tOsO_epi[(None, None), None])
tTMEM_LOADcO_epi = thr_tmem_load_epi.partition_D(tOcO_epi[(None, None), None])
n_epi_corr_tiles = self.pv_mma_tiler[1] // epi_corr_tile_size
for i in range(n_epi_corr_tiles):
tTMrO = cute.make_rmem_tensor(
tTMEM_LOADcO_epi[None, 0, 0, i].shape, self.acc_dtype
)
cute.copy(tiled_tmem_load_epi, tTMEM_LOADtO_epi[None, 0, 0, i], tTMrO)
for j in range(cute.size(tTMrO)):
tTMrO[j] = tTMrO[j] * inv_row_sum
tSMrO = cute.make_rmem_tensor(tTMrO.shape, self.o_dtype)
o_vec = tTMrO.load()
tSMrO.store(o_vec.to(self.o_dtype))
cute.copy(tiled_smem_store_epi, tSMrO, tTMEM_LOADsO_epi[None, 0, 0, i])
cute.arch.fence_proxy("async.shared", space="cta")
# TMA store SMEM → GMEM using epilogue_tma_store helper
# Feed it the unscaled TMEM data — it reads from TMEM, but our scaled
# data is in SMEM. So we need to bypass the TMEM read.
# Instead, use a simple cp_async_bulk from SMEM to GMEM.
epi_bar = pipeline.NamedBarrier(
barrier_id=self.epilog_sync_bar_id,
num_threads=32 * len(self.epilogue_warp_id),
)
epi_bar.arrive_and_wait()
acc_cons_st = pipeline.make_pipeline_state(
pipeline.PipelineUserType.Consumer, self.num_acc_stage
)
c_pipe = pipeline.PipelineTmaStore.create(
num_stages=self.num_c_stage,
producer_group=pipeline.CooperativeGroup(pipeline.Agent.Thread, 32 * len(self.epilogue_warp_id)),
)
acc_pipe.consumer_wait(acc_cons_st)
tTR_tO_tile = tTR_tO[(None, None, None, None, None, acc_cons_st.index)]
bSG_gC = bSG_gC_part[(None, None, None, Int32(0), Int32(0), Int32(0))]
tTR_tO_tile = cute.group_modes(tTR_tO_tile, 3, cute.rank(tTR_tO_tile))
bSG_gC = cute.group_modes(bSG_gC, 1, cute.rank(bSG_gC))
subtile_cnt = cute.size(tTR_tO_tile.shape, mode=[3])
for subtile_idx in range(subtile_cnt):
tTR_tO_mn = tTR_tO_tile[(None, None, None, subtile_idx)]
cute.copy(tiled_copy_t2r, tTR_tO_mn, tTR_rO)
# *** Normalize: multiply by inv_row_sum ***
for j in cutlass.range(cute.size(tTR_rO), vectorize=True):
tTR_rO[j] = tTR_rO[j] * inv_row_sum
# Convert FP32 → BF16
acc_vec = tiled_copy_r2s.retile(tTR_rO).load()
acc_vec = acc_vec.to(self.c_dtype)
tRS_rC.store(acc_vec)
c_buffer = subtile_idx % self.num_c_stage
cute.copy(tiled_copy_r2s, tRS_rC, tRS_sC[(None, None, None, c_buffer)])
cute.arch.fence_proxy("async.shared", space="cta")
epilog_sync_bar.arrive_and_wait()
if warp_idx == self.epilogue_warp_id[0]:
cute.copy(tma_c, bSG_sC[(None, c_buffer)], bSG_gC[(None, subtile_idx)])
c_pipe.producer_commit()
c_pipe.producer_acquire()
epilog_sync_bar.arrive_and_wait()
epilog_sync_bar.arrive_and_wait()
acc_pipe.consumer_release(acc_cons_st)
acc_cons_st.advance()
c_pipe.producer_tail()
# Use cute.copy with tma_c atom for TMA store (only from warp 0)
# Need to get the SMEM and GMEM tensors into the right shape
# cute.copy(tma_c, sC_slice, gC) — but need proper partitioning
# Fallback: write O*inv_row_sum back to TMEM (2nd round-trip risk)
# then use epilogue_tma_store.
# OR: just use epilogue_tma_store with a no-op epilogue and
# apply normalize on CPU. But Mike says no shortcuts.
# For now, write back to TMEM (which we know corrupts slightly)
# and see if the corruption is acceptable with the paired atoms.
# Actually — we DON'T have a paired TMEM store. We have paired
# TMEM load + SMEM store. The data is ALREADY in SMEM (scaled).
# We need TMA store from SMEM → GMEM.
# The cleanest: use the TMA atom directly.
# tma_c was created with make_tiled_tma_atom(S2G, c, epi_s, epi_tile)
# cute.copy(tma_c, sC, gC) should work if shapes match.
cute.copy(tma_c, sC, gC)
cute.arch.cp_async_bulk_commit_group()
cute.arch.cp_async_bulk_wait_group(0, read=True)
tmem.relinquish_alloc_permit()
tmem.free(tmem_ptr)