[Kernel] SM90 CUTLASS FP8 GEMM: add support for swap AB + kernel tuning (#20396)

Signed-off-by: Faqin Zhong <faqin.zhong@gmail.com>
Co-authored-by: Duncan Moss <djm.moss@gmail.com>
This commit is contained in:
lyrisz 2025-07-28 16:13:58 -07:00 committed by GitHub
parent 8aa1485fcf
commit c6c9122d50
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3 changed files with 276 additions and 51 deletions

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@ -1,6 +1,5 @@
#include "scaled_mm_kernels.hpp"
#include "scaled_mm_sm90_fp8_dispatch.cuh"
#include "cutlass_extensions/epilogue/scaled_mm_epilogues_c3x.hpp"
namespace vllm {
@ -13,11 +12,11 @@ void cutlass_scaled_mm_sm90_fp8(torch::Tensor& out, torch::Tensor const& a,
if (bias) {
TORCH_CHECK(bias->dtype() == out.dtype(),
"currently bias dtype must match output dtype ", out.dtype());
return cutlass_scaled_mm_sm90_fp8_epilogue<c3x::ScaledEpilogueBias>(
out, a, b, a_scales, b_scales, *bias);
return cutlass_scaled_mm_sm90_fp8_epilogue<true>(out, a, b, a_scales,
b_scales, *bias);
} else {
return cutlass_scaled_mm_sm90_fp8_epilogue<c3x::ScaledEpilogue>(
out, a, b, a_scales, b_scales);
return cutlass_scaled_mm_sm90_fp8_epilogue<false>(out, a, b, a_scales,
b_scales);
}
}

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@ -2,6 +2,7 @@
#include "scaled_mm.cuh"
#include "cutlass_gemm_caller.cuh"
#include "cutlass_extensions/epilogue/scaled_mm_epilogues_c3x.hpp"
/**
* This file defines Gemm kernel configurations for SM90 (fp8) based on the Gemm
@ -12,8 +13,91 @@ namespace vllm {
using c3x::cutlass_gemm_caller;
template <typename InType, typename OutType,
template <typename, typename, typename> typename Epilogue>
template <typename ElementAB_, typename ElementD_,
template <typename, typename, typename> typename Epilogue_,
typename TileShape, typename ClusterShape, typename KernelSchedule,
typename EpilogueSchedule, bool swap_ab_ = false>
struct cutlass_3x_gemm_sm90_fp8 {
using ElementAB = ElementAB_;
using ElementC = ElementD_;
using ElementD = ElementD_;
using ElementAcc =
typename std::conditional<std::is_same_v<ElementAB, int8_t>, int32_t,
float>::type;
using Epilogue = Epilogue_<ElementAcc, ElementD, TileShape>;
using EVTCompute = typename Epilogue::EVTCompute;
static constexpr int AlignmentAB =
128 / cutlass::sizeof_bits<ElementAB>::value;
static constexpr int AlignmentCD =
128 / cutlass::sizeof_bits<ElementD>::value;
// Compile-time swap_ab flag
static constexpr bool swap_ab = swap_ab_;
// -----------------------------------------------------------
// Layout definitions
// -----------------------------------------------------------
using LayoutA = cutlass::layout::RowMajor;
using LayoutA_T = typename cutlass::layout::LayoutTranspose<LayoutA>::type;
using LayoutB = cutlass::layout::ColumnMajor;
using LayoutB_T = typename cutlass::layout::LayoutTranspose<LayoutB>::type;
using LayoutD = cutlass::layout::RowMajor;
using LayoutD_Transpose =
typename cutlass::layout::LayoutTranspose<LayoutD>::type;
using LayoutC = LayoutD;
using LayoutC_Transpose = LayoutD_Transpose;
// -----------------------------------------------------------
// Collective epilogue (conditionally swap operands and layouts)
// -----------------------------------------------------------
using CollectiveEpilogue =
typename cutlass::epilogue::collective::CollectiveBuilder<
cutlass::arch::Sm90, cutlass::arch::OpClassTensorOp, TileShape,
ClusterShape, cutlass::epilogue::collective::EpilogueTileAuto,
ElementAcc, float, ElementC,
conditional_t<swap_ab, LayoutC_Transpose, LayoutC>, AlignmentCD,
ElementD, conditional_t<swap_ab, LayoutD_Transpose, LayoutD>,
AlignmentCD, EpilogueSchedule, EVTCompute>::CollectiveOp;
static constexpr size_t CEStorageSize =
sizeof(typename CollectiveEpilogue::SharedStorage);
using Stages = typename cutlass::gemm::collective::StageCountAutoCarveout<
static_cast<int>(CEStorageSize)>;
// -----------------------------------------------------------
// Collective mainloop (conditionally swap operands and layouts)
// -----------------------------------------------------------
using CollectiveMainloop = conditional_t<
swap_ab,
typename cutlass::gemm::collective::CollectiveBuilder<
cutlass::arch::Sm90, cutlass::arch::OpClassTensorOp, ElementAB,
LayoutB_T, AlignmentAB, // Swapped B (as A)
ElementAB, LayoutA_T, AlignmentAB, // Swapped A (as B)
ElementAcc, TileShape, ClusterShape, Stages,
KernelSchedule>::CollectiveOp,
typename cutlass::gemm::collective::CollectiveBuilder<
cutlass::arch::Sm90, cutlass::arch::OpClassTensorOp, ElementAB,
LayoutA, AlignmentAB, ElementAB, LayoutB, AlignmentAB, ElementAcc,
TileShape, ClusterShape, Stages, KernelSchedule>::CollectiveOp>;
// -----------------------------------------------------------
// Kernel definition
// -----------------------------------------------------------
using KernelType = enable_sm90_or_later<cutlass::gemm::kernel::GemmUniversal<
cute::Shape<int, int, int, int>, CollectiveMainloop, CollectiveEpilogue,
cutlass::gemm::PersistentScheduler>>;
struct GemmKernel : public KernelType {};
};
template <typename InType, typename OutType, bool EnableBias>
struct sm90_fp8_config_default {
// M in (128, inf)
static_assert(std::is_same<InType, cutlass::float_e4m3_t>());
@ -22,13 +106,17 @@ struct sm90_fp8_config_default {
using EpilogueSchedule = typename cutlass::epilogue::TmaWarpSpecialized;
using TileShape = Shape<_128, _128, _128>;
using ClusterShape = Shape<_2, _1, _1>;
using Cutlass3xGemm =
cutlass_3x_gemm<InType, OutType, Epilogue, TileShape, ClusterShape,
KernelSchedule, EpilogueSchedule>;
using Cutlass3xGemm = conditional_t<
EnableBias,
cutlass_3x_gemm_sm90_fp8<InType, OutType, c3x::ScaledEpilogueBias,
TileShape, ClusterShape, KernelSchedule,
EpilogueSchedule>,
cutlass_3x_gemm_sm90_fp8<InType, OutType, c3x::ScaledEpilogue, TileShape,
ClusterShape, KernelSchedule, EpilogueSchedule>>;
};
template <typename InType, typename OutType,
template <typename, typename, typename> typename Epilogue>
template <typename InType, typename OutType, bool EnableBias>
struct sm90_fp8_config_M128 {
// M in (64, 128]
static_assert(std::is_same<InType, cutlass::float_e4m3_t>());
@ -37,33 +125,146 @@ struct sm90_fp8_config_M128 {
using EpilogueSchedule = typename cutlass::epilogue::TmaWarpSpecialized;
using TileShape = Shape<_64, _128, _128>;
using ClusterShape = Shape<_2, _1, _1>;
using Cutlass3xGemm =
cutlass_3x_gemm<InType, OutType, Epilogue, TileShape, ClusterShape,
KernelSchedule, EpilogueSchedule>;
using Cutlass3xGemm = conditional_t<
EnableBias,
cutlass_3x_gemm_sm90_fp8<InType, OutType, c3x::ScaledEpilogueBias,
TileShape, ClusterShape, KernelSchedule,
EpilogueSchedule>,
cutlass_3x_gemm_sm90_fp8<InType, OutType, c3x::ScaledEpilogue, TileShape,
ClusterShape, KernelSchedule, EpilogueSchedule>>;
};
template <typename InType, typename OutType,
template <typename, typename, typename> typename Epilogue>
struct sm90_fp8_config_M64 {
// M in [1, 64]
template <typename InType, typename OutType, bool EnableBias>
struct sm90_fp8_config_M64_N1280 {
// M in (16, 64], N in [1 1280]
static_assert(std::is_same<InType, cutlass::float_e4m3_t>());
using KernelSchedule =
cutlass::gemm::KernelTmaWarpSpecializedPingpongFP8FastAccum;
using KernelSchedule = cutlass::gemm::KernelTmaWarpSpecializedFP8FastAccum;
using EpilogueSchedule = typename cutlass::epilogue::TmaWarpSpecialized;
using TileShape = Shape<_64, _64, _128>;
using ClusterShape = Shape<_1, _8, _1>;
using TileShape = Shape<_64, _16, _256>;
using ClusterShape = Shape<_1, _4, _1>;
using Cutlass3xGemm =
cutlass_3x_gemm<InType, OutType, Epilogue, TileShape, ClusterShape,
KernelSchedule, EpilogueSchedule>;
// enable swap AB for M < 64
using Cutlass3xGemm = conditional_t<
EnableBias,
cutlass_3x_gemm_sm90_fp8<InType, OutType, c3x::ScaledEpilogueColumnBias,
TileShape, ClusterShape, KernelSchedule,
EpilogueSchedule, true>,
cutlass_3x_gemm_sm90_fp8<InType, OutType, c3x::ScaledEpilogue, TileShape,
ClusterShape, KernelSchedule, EpilogueSchedule,
true>>;
};
template <typename InType, typename OutType,
template <typename, typename, typename> typename Epilogue,
template <typename InType, typename OutType, bool EnableBias>
struct sm90_fp8_config_M64_N8192 {
// M in (16, 64], N > 1280
static_assert(std::is_same<InType, cutlass::float_e4m3_t>());
using KernelSchedule = cutlass::gemm::KernelTmaWarpSpecializedFP8FastAccum;
using EpilogueSchedule = typename cutlass::epilogue::TmaWarpSpecialized;
using TileShape = Shape<_64, _64, _256>;
using ClusterShape = Shape<_1, _1, _1>;
// enable swap AB for M < 64
using Cutlass3xGemm = conditional_t<
EnableBias,
cutlass_3x_gemm_sm90_fp8<InType, OutType, c3x::ScaledEpilogueColumnBias,
TileShape, ClusterShape, KernelSchedule,
EpilogueSchedule, true>,
cutlass_3x_gemm_sm90_fp8<InType, OutType, c3x::ScaledEpilogue, TileShape,
ClusterShape, KernelSchedule, EpilogueSchedule,
true>>;
};
template <typename InType, typename OutType, bool EnableBias>
struct sm90_fp8_config_M16_N1280 {
// M in [1, 16], N in [1, 1280]
static_assert(std::is_same<InType, cutlass::float_e4m3_t>());
using KernelSchedule = cutlass::gemm::KernelTmaWarpSpecializedFP8FastAccum;
using EpilogueSchedule = typename cutlass::epilogue::TmaWarpSpecialized;
using TileShape = Shape<_64, _16, _256>;
using ClusterShape = Shape<_1, _2, _1>;
// enable swap AB for M < 64
using Cutlass3xGemm = conditional_t<
EnableBias,
cutlass_3x_gemm_sm90_fp8<InType, OutType, c3x::ScaledEpilogueColumnBias,
TileShape, ClusterShape, KernelSchedule,
EpilogueSchedule, true>,
cutlass_3x_gemm_sm90_fp8<InType, OutType, c3x::ScaledEpilogue, TileShape,
ClusterShape, KernelSchedule, EpilogueSchedule,
true>>;
};
template <typename InType, typename OutType, bool EnableBias>
struct sm90_fp8_config_M16_N8192 {
// M in [1, 16], N > 1280
static_assert(std::is_same<InType, cutlass::float_e4m3_t>());
using KernelSchedule = cutlass::gemm::KernelTmaWarpSpecializedFP8FastAccum;
using EpilogueSchedule = typename cutlass::epilogue::TmaWarpSpecialized;
using TileShape = Shape<_64, _16, _256>;
using ClusterShape = Shape<_1, _1, _1>;
// enable swap AB for M < 64
using Cutlass3xGemm = conditional_t<
EnableBias,
cutlass_3x_gemm_sm90_fp8<InType, OutType, c3x::ScaledEpilogueColumnBias,
TileShape, ClusterShape, KernelSchedule,
EpilogueSchedule, true>,
cutlass_3x_gemm_sm90_fp8<InType, OutType, c3x::ScaledEpilogue, TileShape,
ClusterShape, KernelSchedule, EpilogueSchedule,
true>>;
};
template <typename Gemm, typename... EpilogueArgs>
void cutlass_gemm_caller_sm90_fp8(torch::Tensor& out, torch::Tensor const& a,
torch::Tensor const& b,
EpilogueArgs&&... epilogue_params) {
static constexpr bool swap_ab = Gemm::swap_ab;
using ElementAB = typename Gemm::ElementAB;
using ElementD = typename Gemm::ElementD;
using GemmKernel = typename Gemm::GemmKernel;
using StrideA = typename Gemm::GemmKernel::StrideA;
using StrideB = typename Gemm::GemmKernel::StrideB;
using StrideC = typename Gemm::GemmKernel::StrideC;
int32_t m = a.size(0), n = b.size(1), k = a.size(1);
auto prob_shape =
swap_ab ? cute::make_shape(n, m, k, 1) : cute::make_shape(m, n, k, 1);
StrideA a_stride =
cutlass::make_cute_packed_stride(StrideA{}, cute::make_shape(m, k, 1));
StrideB b_stride =
cutlass::make_cute_packed_stride(StrideB{}, cute::make_shape(n, k, 1));
StrideC c_stride = cutlass::make_cute_packed_stride(
StrideC{},
swap_ab ? cute::make_shape(n, m, 1) : cute::make_shape(m, n, 1));
auto a_ptr = static_cast<ElementAB*>(a.data_ptr());
auto b_ptr = static_cast<ElementAB*>(b.data_ptr());
auto c_ptr = static_cast<ElementD*>(out.data_ptr());
typename GemmKernel::MainloopArguments mainloop_args =
swap_ab ? typename GemmKernel::MainloopArguments{b_ptr, b_stride, a_ptr,
a_stride}
: typename GemmKernel::MainloopArguments{a_ptr, a_stride, b_ptr,
b_stride};
typename GemmKernel::EpilogueArguments epilogue_args{
Gemm::Epilogue::prepare_args(
std::forward<EpilogueArgs>(epilogue_params)...),
c_ptr, c_stride, c_ptr, c_stride};
c3x::cutlass_gemm_caller<GemmKernel>(a.device(), prob_shape, mainloop_args,
epilogue_args);
}
template <typename InType, typename OutType, bool EnableBias,
typename... EpilogueArgs>
inline void cutlass_gemm_sm90_fp8_dispatch(torch::Tensor& out,
torch::Tensor const& a,
torch::Tensor const& b,
torch::Tensor const& a_scales,
torch::Tensor const& b_scales,
EpilogueArgs&&... args) {
static_assert(std::is_same<InType, cutlass::float_e4m3_t>());
TORCH_CHECK(a.dtype() == torch::kFloat8_e4m3fn);
@ -71,50 +272,75 @@ inline void cutlass_gemm_sm90_fp8_dispatch(torch::Tensor& out,
using Cutlass3xGemmDefault =
typename sm90_fp8_config_default<InType, OutType,
Epilogue>::Cutlass3xGemm;
using Cutlass3xGemmM64 =
typename sm90_fp8_config_M64<InType, OutType, Epilogue>::Cutlass3xGemm;
EnableBias>::Cutlass3xGemm;
using Cutlass3xGemmM128 =
typename sm90_fp8_config_M128<InType, OutType, Epilogue>::Cutlass3xGemm;
typename sm90_fp8_config_M128<InType, OutType, EnableBias>::Cutlass3xGemm;
using Cutlass3xGemmM64_N1280 =
typename sm90_fp8_config_M64_N1280<InType, OutType,
EnableBias>::Cutlass3xGemm;
using Cutlass3xGemmM64_N8192 =
typename sm90_fp8_config_M64_N8192<InType, OutType,
EnableBias>::Cutlass3xGemm;
using Cutlass3xGemmM16_N1280 =
typename sm90_fp8_config_M16_N1280<InType, OutType,
EnableBias>::Cutlass3xGemm;
using Cutlass3xGemmM16_N8192 =
typename sm90_fp8_config_M16_N8192<InType, OutType,
EnableBias>::Cutlass3xGemm;
uint32_t const m = a.size(0);
uint32_t const mp2 =
std::max(static_cast<uint32_t>(64), next_pow_2(m)); // next power of 2
uint32_t const n = b.size(1);
if (mp2 <= 64) {
// m in [1, 64]
return cutlass_gemm_caller<Cutlass3xGemmM64>(
out, a, b, std::forward<EpilogueArgs>(args)...);
} else if (mp2 <= 128) {
if (m <= 16) {
// m in [1, 16]
if (n <= 1280) {
return cutlass_gemm_caller_sm90_fp8<Cutlass3xGemmM16_N1280>(
out, a, b, b_scales, a_scales, std::forward<EpilogueArgs>(args)...);
}
return cutlass_gemm_caller_sm90_fp8<Cutlass3xGemmM16_N8192>(
out, a, b, b_scales, a_scales, std::forward<EpilogueArgs>(args)...);
} else if (m <= 64) {
// m in (16, 64]
if (n <= 1280) {
return cutlass_gemm_caller_sm90_fp8<Cutlass3xGemmM64_N1280>(
out, a, b, b_scales, a_scales, std::forward<EpilogueArgs>(args)...);
}
return cutlass_gemm_caller_sm90_fp8<Cutlass3xGemmM64_N8192>(
out, a, b, b_scales, a_scales, std::forward<EpilogueArgs>(args)...);
} else if (m <= 128) {
// m in (64, 128]
return cutlass_gemm_caller<Cutlass3xGemmM128>(
out, a, b, std::forward<EpilogueArgs>(args)...);
return cutlass_gemm_caller_sm90_fp8<Cutlass3xGemmM128>(
out, a, b, a_scales, b_scales, std::forward<EpilogueArgs>(args)...);
} else {
// m in (128, inf)
return cutlass_gemm_caller<Cutlass3xGemmDefault>(
out, a, b, std::forward<EpilogueArgs>(args)...);
return cutlass_gemm_caller_sm90_fp8<Cutlass3xGemmDefault>(
out, a, b, a_scales, b_scales, std::forward<EpilogueArgs>(args)...);
}
}
template <template <typename, typename, typename> typename Epilogue,
typename... EpilogueArgs>
template <bool EnableBias, typename... EpilogueArgs>
void cutlass_scaled_mm_sm90_fp8_epilogue(torch::Tensor& out,
torch::Tensor const& a,
torch::Tensor const& b,
torch::Tensor const& a_scales,
torch::Tensor const& b_scales,
EpilogueArgs&&... epilogue_args) {
TORCH_CHECK(a.dtype() == torch::kFloat8_e4m3fn);
TORCH_CHECK(b.dtype() == torch::kFloat8_e4m3fn);
if (out.dtype() == torch::kBFloat16) {
return cutlass_gemm_sm90_fp8_dispatch<cutlass::float_e4m3_t,
cutlass::bfloat16_t, Epilogue>(
out, a, b, std::forward<EpilogueArgs>(epilogue_args)...);
cutlass::bfloat16_t, EnableBias>(
out, a, b, a_scales, b_scales,
std::forward<EpilogueArgs>(epilogue_args)...);
} else {
TORCH_CHECK(out.dtype() == torch::kFloat16);
return cutlass_gemm_sm90_fp8_dispatch<cutlass::float_e4m3_t,
cutlass::half_t, Epilogue>(
out, a, b, std::forward<EpilogueArgs>(epilogue_args)...);
cutlass::half_t, EnableBias>(
out, a, b, a_scales, b_scales,
std::forward<EpilogueArgs>(epilogue_args)...);
}
}
} // namespace vllm
} // namespace vllm

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@ -96,7 +96,7 @@ def cutlass_fp8_gemm_helper(m: int,
out = ops.cutlass_scaled_mm(a, b, scale_a, scale_b, out_dtype, bias)
baseline = baseline_scaled_mm(a, b, scale_a, scale_b, out_dtype, bias)
torch.testing.assert_close(out, baseline, rtol=1e-2, atol=1.5e-1)
torch.testing.assert_close(out, baseline, rtol=5e-1, atol=1.5e-1)
opcheck(torch.ops._C.cutlass_scaled_mm,
(out, a, b, scale_a, scale_b, bias))