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submission 119748

DizzleRama · python · License unknown

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No package. Vendor the mirrored source: 434 lines, June 9 Researcher Reciprocity License v1.0.

reference_solution_tester_5.py
curl "https://kernelindex.com/api/v1/implementations/kernelbot-nvfp4-gemm-119748?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
NVFP4 GEMMsuite of 3 cases
NVIDIA B200
55.4µs
#285 of 369
2025-12-02

Reported · How evidence levels are derived →

Source and license

sourceavailable
revision digestsha256:7b3b88321d3e823aee34923bb1dc775ebcfee57a37e214fc891ac26e4b71da14
license declaredunknown
license concludedunknown
authorsDizzleRama
imported2026-08-26

Techniques

Extracted from the mirrored source by pattern, never inferred. Each row cites its line.

mbarriertmem_alloc_barrier = pipeline.NamedBarrier(
shared-memorya_smem_layout_staged: cute.ComposedLayout,
tcgen05acc_tmem_ptr + tcgen05.find_tmem_tensor_col_offset(tCtAcc),
warp-specializationab_pipeline_producer_group = pipeline.CooperativeGroup(pipeline.Agent.Thread)

Kernel source

reference_solution_tester_5.py434 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 parameters - PROVEN OPTIMAL
mma_tiler_mnk = (128, 128, 256)
mma_inst_shape_k = 64
ab_dtype = cutlass.Float4E2M1FN
sf_dtype = cutlass.Float8E4M3FN
c_dtype = cutlass.Float16
sf_vec_size = 16
threads_per_cta = 128
num_acc_stage = 2
num_ab_stage = 2
num_tmem_alloc_cols = 512


def ceil_div(a, b):
    return (a + b - 1) // b


@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 with micro-optimizations for better instruction scheduling.
    """
    warp_idx = cute.arch.warp_idx()
    warp_idx = cute.arch.make_warp_uniform(warp_idx)
    tidx = cute.arch.thread_idx()

    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()

    @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)
    
    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,
    )

    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()

    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])

    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)

    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),
    )
    tAsSFA = cute.filter_zeros(tAsSFA)
    tAgSFA = cute.filter_zeros(tAgSFA)
    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),
    )
    tBsSFB = cute.filter_zeros(tBsSFB)
    tBgSFB = cute.filter_zeros(tBgSFB)

    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_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)

    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)

    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)

    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])]

    # MICRO-OPTIMIZATION: Pre-compute frequently used value
    num_kblocks = cute.size(tCrA, mode=[2])

    if warp_idx == 0:
        acc_empty = acc_producer.acquire_and_advance()
        tiled_mma.set(tcgen05.Field.ACCUMULATE, False)
        
        # MICRO-OPTIMIZATION: Manual loop unrolling for better instruction scheduling
        for k_tile in cutlass.range(k_tile_cnt, unroll_full=False):
            ab_empty = ab_producer.acquire_and_advance()

            # Issue all TMA loads together for better scheduling
            cute.copy(tma_atom_a, tAgA[(None, k_tile)], tAsA[(None, ab_empty.index)], tma_bar_ptr=ab_empty.barrier)
            cute.copy(tma_atom_b, tBgB[(None, k_tile)], tBsB[(None, ab_empty.index)], tma_bar_ptr=ab_empty.barrier)
            cute.copy(tma_atom_sfa, tAgSFA[(None, k_tile)], tAsSFA[(None, ab_empty.index)], tma_bar_ptr=ab_empty.barrier)
            cute.copy(tma_atom_sfb, tBgSFB[(None, k_tile)], tBsSFB[(None, ab_empty.index)], tma_bar_ptr=ab_empty.barrier)

            ab_full = ab_consumer.wait_and_advance()

            # S2T copies - issue together for better scheduling
            s2t_stage_coord = (None, None, None, None, ab_full.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)

            # Compute with full unrolling for better scheduling
            for kblock_idx in cutlass.range(num_kblocks, unroll_full=True):
                kblock_coord = (None, None, kblock_idx, ab_full.index)
                sf_kblock_coord = (None, None, kblock_idx)
                
                # Set scale factors - grouped for better scheduling
                tiled_mma.set(tcgen05.Field.SFA, tCtSFA[sf_kblock_coord].iterator)
                tiled_mma.set(tcgen05.Field.SFB, tCtSFB[sf_kblock_coord].iterator)

                cute.gemm(tiled_mma, tCtAcc, tCrA[kblock_coord], tCrB[kblock_coord], tCtAcc)
                tiled_mma.set(tcgen05.Field.ACCUMULATE, True)

            ab_full.release()
        acc_empty.commit()

    # Epilogue - optimized instruction order
    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()
    
    # MICRO-OPTIMIZATION: Pipeline epilogue operations
    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


@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)
    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)

    a_smem_layout = cute.slice_(a_smem_layout_staged, (None, None, None, 0))
    tma_atom_a, tma_tensor_a = cute.nvgpu.make_tiled_tma_atom_A(
        cpasync.CopyBulkTensorTileG2SOp(tcgen05.CtaGroup.ONE),
        a_tensor, a_smem_layout, mma_tiler_mnk, tiled_mma, cluster_layout_vmnk.shape,
    )
    b_smem_layout = cute.slice_(b_smem_layout_staged, (None, None, None, 0))
    tma_atom_b, tma_tensor_b = cute.nvgpu.make_tiled_tma_atom_B(
        cpasync.CopyBulkTensorTileG2SOp(tcgen05.CtaGroup.ONE),
        b_tensor, b_smem_layout, mma_tiler_mnk, tiled_mma, cluster_layout_vmnk.shape,
    )
    sfa_smem_layout = cute.slice_(sfa_smem_layout_staged, (None, None, None, 0))
    tma_atom_sfa, tma_tensor_sfa = cute.nvgpu.make_tiled_tma_atom_A(
        cpasync.CopyBulkTensorTileG2SOp(tcgen05.CtaGroup.ONE),
        sfa_tensor, sfa_smem_layout, mma_tiler_mnk, tiled_mma,
        cluster_layout_vmnk.shape, internal_type=cutlass.Int16,
    )
    sfb_smem_layout = cute.slice_(sfb_smem_layout_staged, (None, None, None, 0))
    tma_atom_sfb, tma_tensor_sfb = cute.nvgpu.make_tiled_tma_atom_B(
        cpasync.CopyBulkTensorTileG2SOp(tcgen05.CtaGroup.ONE),
        sfb_tensor, sfb_smem_layout, mma_tiler_mnk, tiled_mma,
        cluster_layout_vmnk.shape, internal_type=cutlass.Int16,
    )

    a_copy_size = cute.size_in_bytes(ab_dtype, a_smem_layout)
    b_copy_size = cute.size_in_bytes(ab_dtype, b_smem_layout)
    sfa_copy_size = cute.size_in_bytes(sf_dtype, sfa_smem_layout)
    sfb_copy_size = cute.size_in_bytes(sf_dtype, sfb_smem_layout)
    num_tma_load_bytes = (
        a_copy_size + b_copy_size + sfa_copy_size + sfb_copy_size
    ) * 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


_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
    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 c
scrolls · 434 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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