submission 117026
revess · python · License unknown
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submission.py
curl "https://kernelindex.com/api/v1/implementations/kernelbot-nvfp4-gemm-117026?include=source"interfacepython
Compatibility
measured onNVIDIA B200
declared hardwareNVIDIA B200
architecturessm_100
dtypesfp8_e4m3, nvfp4
Benchmark evidence
1 measurement across 1 GPU, fastest first.
Operation / workload
Hardware
Latency
Rank
Observed
Reported · How evidence levels are derived →
Source and license
sourceavailable
revision digestsha256:d0c33b515c9ac8bf59de0b4c29e4b6caecceb637cbf87690956151ff2fbb1769
license declaredunknown
license concludedunknown
authorsrevess
imported2026-08-26
Techniques
Extracted from the mirrored source by pattern, never inferred. Each row cites its line.
mbarrier
tmem_alloc_barrier = pipeline.NamedBarrier(barrier_id=1, num_threads=threads_per_cta)shared-memory
a_smem_layout_staged: cute.ComposedLayout,tcgen05
sfa_tmem_ptr = cute.recast_ptr(acc_tmem_ptr + tcgen05.find_tmem_tensor_col_offset(tCtAcc), dtype=sf_dtype)warp-specialization
ab_pipeline_producer_group = pipeline.CooperativeGroup(pipeline.Agent.Thread)Kernel source
submission.py408 lines
from torch._higher_order_ops.torchbind import call_torchbind_fake
import cuda.bindings.driver as cuda
import torch
from task import input_t, output_t
import cutlass
import cutlass.cute as cute
import cutlass.utils as utils
import cutlass.pipeline as pipeline
from cutlass.cute.nvgpu import cpasync, tcgen05
import cutlass.torch as cutlass_torch
import cutlass.utils.blackwell_helpers as sm100_utils
import cutlass.utils.blockscaled_layout as blockscaled_utils
from cutlass.cute.runtime import make_ptr
# =============================================================================
# Kernel Configuration
# =============================================================================
# Tile sizes for M, N, K dimensions
mma_tiler_mnk = (128, 128, 256)
# Shape of the K dimension for the MMA instruction
mma_inst_shape_k = 64
# FP4 data type for A and B
ab_dtype = cutlass.Float4E2M1FN
# FP8 data type for scale factors
sf_dtype = cutlass.Float8E4M3FN
# FP16 output type
c_dtype = cutlass.Float16
# Scale factor block size (16 elements share one scale)
sf_vec_size = 16
# Number of threads per CUDA thread block
threads_per_cta = 128
# Optimization: Increase pipeline depth to 4 stages to hide DRAM latency
num_acc_stage = 1
num_ab_stage = 4
# Total number of columns in tmem
num_tmem_alloc_cols = 512
# =============================================================================
# Kernel Definition
# =============================================================================
@cute.kernel
def kernel(
tiled_mma: cute.TiledMma,
tma_atom_a: cute.CopyAtom,
mA_mkl: cute.Tensor,
tma_atom_b: cute.CopyAtom,
mB_nkl: cute.Tensor,
tma_atom_sfa: cute.CopyAtom,
mSFA_mkl: cute.Tensor,
tma_atom_sfb: cute.CopyAtom,
mSFB_nkl: cute.Tensor,
mC_mnl: cute.Tensor,
a_smem_layout_staged: cute.ComposedLayout,
b_smem_layout_staged: cute.ComposedLayout,
sfa_smem_layout_staged: cute.Layout,
sfb_smem_layout_staged: cute.Layout,
num_tma_load_bytes: cutlass.Constexpr[int],
):
"""
GPU device kernel performing the batched GEMM computation.
"""
warp_idx = cute.arch.warp_idx()
warp_idx = cute.arch.make_warp_uniform(warp_idx)
# Setup cta/thread coordinates
bidx, bidy, bidz = cute.arch.block_idx()
cta_coord = (bidx, bidy, bidz)
mma_tile_coord_mnl = (
cta_coord[0] // cute.size(tiled_mma.thr_id.shape),
cta_coord[1],
cta_coord[2],
)
tidx, _, _ = cute.arch.thread_idx()
# Define shared storage
@cute.struct
class SharedStorage:
ab_mbar_ptr: cute.struct.MemRange[cutlass.Int64, num_ab_stage * 2]
acc_mbar_ptr: cute.struct.MemRange[cutlass.Int64, num_acc_stage * 2]
tmem_holding_buf: cutlass.Int32
smem = utils.SmemAllocator()
storage = smem.allocate(SharedStorage)
# Allocate Shared Memory Buffers
sA = smem.allocate_tensor(
element_type=ab_dtype,
layout=a_smem_layout_staged.outer,
byte_alignment=128,
swizzle=a_smem_layout_staged.inner,
)
sB = smem.allocate_tensor(
element_type=ab_dtype,
layout=b_smem_layout_staged.outer,
byte_alignment=128,
swizzle=b_smem_layout_staged.inner,
)
sSFA = smem.allocate_tensor(
element_type=sf_dtype,
layout=sfa_smem_layout_staged,
byte_alignment=128,
)
sSFB = smem.allocate_tensor(
element_type=sf_dtype,
layout=sfb_smem_layout_staged,
byte_alignment=128,
)
# Initialize Pipelines
ab_pipeline_producer_group = pipeline.CooperativeGroup(pipeline.Agent.Thread)
ab_pipeline_consumer_group = pipeline.CooperativeGroup(pipeline.Agent.Thread, 1)
ab_producer, ab_consumer = pipeline.PipelineTmaUmma.create(
barrier_storage=storage.ab_mbar_ptr.data_ptr(),
num_stages=num_ab_stage,
producer_group=ab_pipeline_producer_group,
consumer_group=ab_pipeline_consumer_group,
tx_count=num_tma_load_bytes,
).make_participants()
acc_producer, acc_consumer = pipeline.PipelineUmmaAsync.create(
barrier_storage=storage.acc_mbar_ptr.data_ptr(),
num_stages=num_acc_stage,
producer_group=ab_pipeline_producer_group,
consumer_group=pipeline.CooperativeGroup(
pipeline.Agent.Thread,
threads_per_cta,
),
).make_participants()
# Local Tile Partitioning
gA_mkl = cute.local_tile(mA_mkl, cute.slice_(mma_tiler_mnk, (None, 0, None)), (None, None, None))
gB_nkl = cute.local_tile(mB_nkl, cute.slice_(mma_tiler_mnk, (0, None, None)), (None, None, None))
gSFA_mkl = cute.local_tile(mSFA_mkl, cute.slice_(mma_tiler_mnk, (None, 0, None)), (None, None, None))
gSFB_nkl = cute.local_tile(mSFB_nkl, cute.slice_(mma_tiler_mnk, (0, None, None)), (None, None, None))
gC_mnl = cute.local_tile(mC_mnl, cute.slice_(mma_tiler_mnk, (None, None, 0)), (None, None, None))
k_tile_cnt = cute.size(gA_mkl, mode=[3])
# Thread Partitioning
thr_mma = tiled_mma.get_slice(0)
tCgA = thr_mma.partition_A(gA_mkl)
tCgB = thr_mma.partition_B(gB_nkl)
tCgSFA = thr_mma.partition_A(gSFA_mkl)
tCgSFB = thr_mma.partition_B(gSFB_nkl)
tCgC = thr_mma.partition_C(gC_mnl)
# TMA Partitioning
tAsA, tAgA = cpasync.tma_partition(tma_atom_a, 0, cute.make_layout(1), cute.group_modes(sA, 0, 3), cute.group_modes(tCgA, 0, 3))
tBsB, tBgB = cpasync.tma_partition(tma_atom_b, 0, cute.make_layout(1), cute.group_modes(sB, 0, 3), cute.group_modes(tCgB, 0, 3))
tAsSFA, tAgSFA = cpasync.tma_partition(tma_atom_sfa, 0, cute.make_layout(1), cute.group_modes(sSFA, 0, 3), cute.group_modes(tCgSFA, 0, 3))
tBsSFB, tBgSFB = cpasync.tma_partition(tma_atom_sfb, 0, cute.make_layout(1), cute.group_modes(sSFB, 0, 3), cute.group_modes(tCgSFB, 0, 3))
tAsSFA = cute.filter_zeros(tAsSFA); tAgSFA = cute.filter_zeros(tAgSFA)
tBsSFB = cute.filter_zeros(tBsSFB); tBgSFB = cute.filter_zeros(tBgSFB)
# Fragments
tCrA = tiled_mma.make_fragment_A(sA)
tCrB = tiled_mma.make_fragment_B(sB)
acc_shape = tiled_mma.partition_shape_C(mma_tiler_mnk[:2])
tCtAcc_fake = tiled_mma.make_fragment_C(acc_shape)
# TMEM Allocation
tmem_alloc_barrier = pipeline.NamedBarrier(barrier_id=1, num_threads=threads_per_cta)
tmem = utils.TmemAllocator(storage.tmem_holding_buf, barrier_for_retrieve=tmem_alloc_barrier)
tmem.allocate(num_tmem_alloc_cols)
tmem.wait_for_alloc()
acc_tmem_ptr = tmem.retrieve_ptr(cutlass.Float32)
tCtAcc = cute.make_tensor(acc_tmem_ptr, tCtAcc_fake.layout)
# TMEM Layouts for Scales
sfa_tmem_ptr = cute.recast_ptr(acc_tmem_ptr + tcgen05.find_tmem_tensor_col_offset(tCtAcc), dtype=sf_dtype)
tCtSFA_layout = blockscaled_utils.make_tmem_layout_sfa(tiled_mma, mma_tiler_mnk, sf_vec_size, cute.slice_(sfa_smem_layout_staged, (None, None, None, 0)))
tCtSFA = cute.make_tensor(sfa_tmem_ptr, tCtSFA_layout)
sfb_tmem_ptr = cute.recast_ptr(acc_tmem_ptr + tcgen05.find_tmem_tensor_col_offset(tCtAcc) + tcgen05.find_tmem_tensor_col_offset(tCtSFA), dtype=sf_dtype)
tCtSFB_layout = blockscaled_utils.make_tmem_layout_sfb(tiled_mma, mma_tiler_mnk, sf_vec_size, cute.slice_(sfb_smem_layout_staged, (None, None, None, 0)))
tCtSFB = cute.make_tensor(sfb_tmem_ptr, tCtSFB_layout)
# Scale Copy Setup (Smem -> Tmem)
copy_atom_s2t = cute.make_copy_atom(tcgen05.Cp4x32x128bOp(tcgen05.CtaGroup.ONE), sf_dtype)
tCsSFA_compact = cute.filter_zeros(sSFA)
tCtSFA_compact = cute.filter_zeros(tCtSFA)
tiled_copy_s2t_sfa = tcgen05.make_s2t_copy(copy_atom_s2t, tCtSFA_compact)
thr_copy_s2t_sfa = tiled_copy_s2t_sfa.get_slice(0)
tCsSFA_compact_s2t_ = thr_copy_s2t_sfa.partition_S(tCsSFA_compact)
tCsSFA_compact_s2t = tcgen05.get_s2t_smem_desc_tensor(tiled_copy_s2t_sfa, tCsSFA_compact_s2t_)
tCtSFA_compact_s2t = thr_copy_s2t_sfa.partition_D(tCtSFA_compact)
tCsSFB_compact = cute.filter_zeros(sSFB)
tCtSFB_compact = cute.filter_zeros(tCtSFB)
tiled_copy_s2t_sfb = tcgen05.make_s2t_copy(copy_atom_s2t, tCtSFB_compact)
thr_copy_s2t_sfb = tiled_copy_s2t_sfb.get_slice(0)
tCsSFB_compact_s2t_ = thr_copy_s2t_sfb.partition_S(tCsSFB_compact)
tCsSFB_compact_s2t = tcgen05.get_s2t_smem_desc_tensor(tiled_copy_s2t_sfb, tCsSFB_compact_s2t_)
tCtSFB_compact_s2t = thr_copy_s2t_sfb.partition_D(tCtSFB_compact)
# Slice to per-MMA tile
tAgA = tAgA[(None, mma_tile_coord_mnl[0], None, mma_tile_coord_mnl[2])]
tBgB = tBgB[(None, mma_tile_coord_mnl[1], None, mma_tile_coord_mnl[2])]
tAgSFA = tAgSFA[(None, mma_tile_coord_mnl[0], None, mma_tile_coord_mnl[2])]
tBgSFB = tBgSFB[(None, mma_tile_coord_mnl[1], None, mma_tile_coord_mnl[2])]
# Main Loop (Software Pipelined)
if warp_idx == 0:
acc_empty = acc_producer.acquire_and_advance()
tiled_mma.set(tcgen05.Field.ACCUMULATE, False)
# Prologue: Issue loads for first N-1 stages
prologue_stages = min(num_ab_stage - 1, k_tile_cnt)
for k_prologue in range(prologue_stages):
prod_token = ab_producer.acquire_and_advance()
cute.copy(tma_atom_a, tAgA[(None, k_prologue)], tAsA[(None, prod_token.index)], tma_bar_ptr=prod_token.barrier)
cute.copy(tma_atom_b, tBgB[(None, k_prologue)], tBsB[(None, prod_token.index)], tma_bar_ptr=prod_token.barrier)
cute.copy(tma_atom_sfa, tAgSFA[(None, k_prologue)], tAsSFA[(None, prod_token.index)], tma_bar_ptr=prod_token.barrier)
cute.copy(tma_atom_sfb, tBgSFB[(None, k_prologue)], tBsSFB[(None, prod_token.index)], tma_bar_ptr=prod_token.barrier)
# Steady State Loop
for k_tile in range(k_tile_cnt):
# Issue Next Stage
next_load_k = k_tile + prologue_stages
if next_load_k < k_tile_cnt:
prod_token = ab_producer.acquire_and_advance()
cute.copy(tma_atom_a, tAgA[(None, next_load_k)], tAsA[(None, prod_token.index)], tma_bar_ptr=prod_token.barrier)
cute.copy(tma_atom_b, tBgB[(None, next_load_k)], tBsB[(None, prod_token.index)], tma_bar_ptr=prod_token.barrier)
cute.copy(tma_atom_sfa, tAgSFA[(None, next_load_k)], tAsSFA[(None, prod_token.index)], tma_bar_ptr=prod_token.barrier)
cute.copy(tma_atom_sfb, tBgSFB[(None, next_load_k)], tBsSFB[(None, prod_token.index)], tma_bar_ptr=prod_token.barrier)
# Wait for Current Stage
cons_token = ab_consumer.wait_and_advance()
# Copy Scales SMEM -> TMEM
s2t_stage_coord = (None, None, None, None, cons_token.index)
cute.copy(tiled_copy_s2t_sfa, tCsSFA_compact_s2t[s2t_stage_coord], tCtSFA_compact_s2t)
cute.copy(tiled_copy_s2t_sfb, tCsSFB_compact_s2t[s2t_stage_coord], tCtSFB_compact_s2t)
# GEMM Math
num_kblocks = cute.size(tCrA, mode=[2])
for kblock_idx in cutlass.range(num_kblocks, unroll_full=True):
kblock_coord = (None, None, kblock_idx, cons_token.index)
sf_coord = (None, None, kblock_idx)
tiled_mma.set(tcgen05.Field.SFA, tCtSFA[sf_coord].iterator)
tiled_mma.set(tcgen05.Field.SFB, tCtSFB[sf_coord].iterator)
cute.gemm(tiled_mma, tCtAcc, tCrA[kblock_coord], tCrB[kblock_coord], tCtAcc)
tiled_mma.set(tcgen05.Field.ACCUMULATE, True)
cons_token.release()
acc_empty.commit()
# Epilogue
op = tcgen05.Ld32x32bOp(tcgen05.Repetition.x128, tcgen05.Pack.NONE)
copy_atom_t2r = cute.make_copy_atom(op, cutlass.Float32)
tiled_copy_t2r = tcgen05.make_tmem_copy(copy_atom_t2r, tCtAcc)
thr_copy_t2r = tiled_copy_t2r.get_slice(tidx)
tTR_tAcc = thr_copy_t2r.partition_S(tCtAcc)
tTR_gC = thr_copy_t2r.partition_D(tCgC)
tTR_rAcc = cute.make_rmem_tensor(tTR_gC[None, None, None, None, 0, 0, 0].shape, cutlass.Float32)
tTR_rC = cute.make_rmem_tensor(tTR_gC[None, None, None, None, 0, 0, 0].shape, c_dtype)
simt_atom = cute.make_copy_atom(cute.nvgpu.CopyUniversalOp(), c_dtype)
tTR_gC = tTR_gC[(None, None, None, None, *mma_tile_coord_mnl)]
acc_full = acc_consumer.wait_and_advance()
cute.copy(tiled_copy_t2r, tTR_tAcc, tTR_rAcc)
acc_vec = tTR_rAcc.load().to(c_dtype)
tTR_rC.store(acc_vec)
cute.copy(simt_atom, tTR_rC, tTR_gC)
acc_full.release()
cute.arch.barrier()
tmem.free(acc_tmem_ptr)
return
# =============================================================================
# JIT Compilation
# =============================================================================
@cute.jit
def my_kernel(
a_ptr: cute.Pointer,
b_ptr: cute.Pointer,
sfa_ptr: cute.Pointer,
sfb_ptr: cute.Pointer,
c_ptr: cute.Pointer,
problem_size: tuple,
):
m, n, k, l = problem_size
a_tensor = cute.make_tensor(a_ptr, cute.make_layout((m, cute.assume(k, 32), l), stride=(cute.assume(k, 32), 1, cute.assume(m * k, 32))))
b_tensor = cute.make_tensor(b_ptr, cute.make_layout((n, cute.assume(k, 32), l), stride=(cute.assume(k, 32), 1, cute.assume(n * k, 32))))
c_tensor = cute.make_tensor(c_ptr, cute.make_layout((cute.assume(m, 32), n, l), stride=(n, 1, m * n)))
sfa_layout = blockscaled_utils.tile_atom_to_shape_SF(a_tensor.shape, sf_vec_size)
sfa_tensor = cute.make_tensor(sfa_ptr, sfa_layout)
sfb_layout = blockscaled_utils.tile_atom_to_shape_SF(b_tensor.shape, sf_vec_size)
sfb_tensor = cute.make_tensor(sfb_ptr, sfb_layout)
mma_op = tcgen05.MmaMXF4NVF4Op(
sf_dtype,
(mma_tiler_mnk[0], mma_tiler_mnk[1], mma_inst_shape_k),
tcgen05.CtaGroup.ONE,
tcgen05.OperandSource.SMEM,
)
tiled_mma = cute.make_tiled_mma(mma_op)
# Use default cluster layout (1,1,1) to ensure compilation stability
cluster_layout_vmnk = cute.tiled_divide(
cute.make_layout((1, 1, 1)),
(tiled_mma.thr_id.shape,),
)
a_smem_layout_staged = sm100_utils.make_smem_layout_a(tiled_mma, mma_tiler_mnk, ab_dtype, num_ab_stage)
b_smem_layout_staged = sm100_utils.make_smem_layout_b(tiled_mma, mma_tiler_mnk, ab_dtype, num_ab_stage)
sfa_smem_layout_staged = blockscaled_utils.make_smem_layout_sfa(tiled_mma, mma_tiler_mnk, sf_vec_size, num_ab_stage)
sfb_smem_layout_staged = blockscaled_utils.make_smem_layout_sfb(tiled_mma, mma_tiler_mnk, sf_vec_size, num_ab_stage)
atom_thr_size = cute.size(tiled_mma.thr_id.shape)
tma_atom_a, tma_tensor_a = cute.nvgpu.make_tiled_tma_atom_A(
cpasync.CopyBulkTensorTileG2SOp(tcgen05.CtaGroup.ONE),
a_tensor, cute.slice_(a_smem_layout_staged, (None, None, None, 0)),
mma_tiler_mnk, tiled_mma, cluster_layout_vmnk.shape
)
tma_atom_b, tma_tensor_b = cute.nvgpu.make_tiled_tma_atom_B(
cpasync.CopyBulkTensorTileG2SOp(tcgen05.CtaGroup.ONE),
b_tensor, cute.slice_(b_smem_layout_staged, (None, None, None, 0)),
mma_tiler_mnk, tiled_mma, cluster_layout_vmnk.shape
)
tma_atom_sfa, tma_tensor_sfa = cute.nvgpu.make_tiled_tma_atom_A(
cpasync.CopyBulkTensorTileG2SOp(tcgen05.CtaGroup.ONE),
sfa_tensor, cute.slice_(sfa_smem_layout_staged, (None, None, None, 0)),
mma_tiler_mnk, tiled_mma, cluster_layout_vmnk.shape, internal_type=cutlass.Int16
)
tma_atom_sfb, tma_tensor_sfb = cute.nvgpu.make_tiled_tma_atom_B(
cpasync.CopyBulkTensorTileG2SOp(tcgen05.CtaGroup.ONE),
sfb_tensor, cute.slice_(sfb_smem_layout_staged, (None, None, None, 0)),
mma_tiler_mnk, tiled_mma, cluster_layout_vmnk.shape, internal_type=cutlass.Int16
)
num_tma_load_bytes = (
cute.size_in_bytes(ab_dtype, cute.slice_(a_smem_layout_staged, (None, None, None, 0))) +
cute.size_in_bytes(ab_dtype, cute.slice_(b_smem_layout_staged, (None, None, None, 0))) +
cute.size_in_bytes(sf_dtype, cute.slice_(sfa_smem_layout_staged, (None, None, None, 0))) +
cute.size_in_bytes(sf_dtype, cute.slice_(sfb_smem_layout_staged, (None, None, None, 0)))
) * atom_thr_size
grid = (
cute.ceil_div(c_tensor.shape[0], mma_tiler_mnk[0]),
cute.ceil_div(c_tensor.shape[1], mma_tiler_mnk[1]),
c_tensor.shape[2],
)
kernel(
tiled_mma, tma_atom_a, tma_tensor_a, tma_atom_b, tma_tensor_b,
tma_atom_sfa, tma_tensor_sfa, tma_atom_sfb, tma_tensor_sfb, c_tensor,
a_smem_layout_staged, b_smem_layout_staged,
sfa_smem_layout_staged, sfb_smem_layout_staged, num_tma_load_bytes,
).launch(grid=grid, block=[threads_per_cta, 1, 1], cluster=(1, 1, 1))
return
# =============================================================================
# Python Entry Points
# =============================================================================
_compiled_kernel_cache = None
def compile_kernel():
global _compiled_kernel_cache
if _compiled_kernel_cache is not None: return _compiled_kernel_cache
a_ptr = make_ptr(ab_dtype, 0, cute.AddressSpace.gmem, assumed_align=16)
b_ptr = make_ptr(ab_dtype, 0, cute.AddressSpace.gmem, assumed_align=16)
c_ptr = make_ptr(c_dtype, 0, cute.AddressSpace.gmem, assumed_align=16)
sfa_ptr = make_ptr(sf_dtype, 0, cute.AddressSpace.gmem, assumed_align=32)
sfb_ptr = make_ptr(sf_dtype, 0, cute.AddressSpace.gmem, assumed_align=32)
_compiled_kernel_cache = cute.compile(my_kernel, a_ptr, b_ptr, sfa_ptr, sfb_ptr, c_ptr, (0, 0, 0, 0))
return _compiled_kernel_cache
def custom_kernel(data: input_t) -> output_t:
a, b, _, _, sfa_permuted, sfb_permuted, c = data
compiled_func = compile_kernel()
m, k, l = a.shape; n = b.shape[0]; k = k * 2
a_ptr = make_ptr(ab_dtype, a.data_ptr(), cute.AddressSpace.gmem, assumed_align=16)
b_ptr = make_ptr(ab_dtype, b.data_ptr(), cute.AddressSpace.gmem, assumed_align=16)
c_ptr = make_ptr(c_dtype, c.data_ptr(), cute.AddressSpace.gmem, assumed_align=16)
sfa_ptr = make_ptr(sf_dtype, sfa_permuted.data_ptr(), cute.AddressSpace.gmem, assumed_align=32)
sfb_ptr = make_ptr(sf_dtype, sfb_permuted.data_ptr(), cute.AddressSpace.gmem, assumed_align=32)
compiled_func(a_ptr, b_ptr, sfa_ptr, sfb_ptr, c_ptr, (m, n, k, l))
return cscrolls · 408 lines total
Source code from GPU Mode and the KernelBot dataset · June 9 Researcher Reciprocity License v1.0
Best evidence level for this revision: reported
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