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Update the flash attn kernels. (#2333)

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This commit is contained in:
Laurent Mazare
2024-07-15 20:37:36 +02:00
committed by GitHub
parent d74fbed334
commit 30cdd769f9
51 changed files with 2279 additions and 904 deletions
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119
candle-flash-attn/kernels/kernel_traits.h
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@ -1,10 +1,10 @@
/******************************************************************************
* Copyright (c) 2023, Tri Dao.
* Copyright (c) 2024, Tri Dao.
******************************************************************************/
#pragma once
#include "cute/algorithm/copy.hpp"
#include "cute/tensor.hpp"
#include "cutlass/cutlass.h"
#include "cutlass/layout/layout.h"
@ -24,7 +24,7 @@ struct Flash_kernel_traits {
#endif
using ElementAccum = float;
using index_t = uint32_t;
using index_t = int64_t;
#if defined(__CUDA_ARCH__) && __CUDA_ARCH__ >= 800
using MMA_Atom_Arch = std::conditional_t<
@ -32,10 +32,8 @@ struct Flash_kernel_traits {
MMA_Atom<SM80_16x8x16_F32F16F16F32_TN>,
MMA_Atom<SM80_16x8x16_F32BF16BF16F32_TN>
>;
using ValLayoutMNK = Layout<Shape<_1, _2, _1>>;
#else
using MMA_Atom_Arch = MMA_Atom<SM75_16x8x8_F32F16F16F32_TN>;
using ValLayoutMNK = Layout<Shape<_1, _2, _2>>;
#endif
#if defined(__CUDA_ARCH__) && __CUDA_ARCH__ >= 750
@ -76,7 +74,7 @@ struct Flash_fwd_kernel_traits : public Base {
using TiledMma = TiledMMA<
typename Base::MMA_Atom_Arch,
Layout<Shape<Int<kNWarps>,_1,_1>>, // 4x1x1 or 8x1x1 thread group
typename Base::ValLayoutMNK>; // 1x2x1 or 1x2x2 value group for 16x16x16 MMA and LDSM
Tile<Int<16 * kNWarps>, _16, _16>>;
using SmemLayoutAtomQ = decltype(
composition(Swizzle<kSwizzle, 3, 3>{},
@ -91,20 +89,10 @@ struct Flash_fwd_kernel_traits : public Base {
SmemLayoutAtomQ{},
Shape<Int<kBlockN>, Int<kHeadDim>>{}));
// This has to be kBlockN and not 8, otherwise we get wrong results for d=128
using SmemLayoutAtomVtransposedNoSwizzle = Layout<Shape<Int<kBlockKSmem>, Int<kBlockN>>,
Stride<_1, Int<kBlockKSmem>>>;
using SmemLayoutAtomVtransposed = decltype(
composition(Swizzle<kSwizzle, 3, 3>{}, SmemLayoutAtomVtransposedNoSwizzle{}));
using SmemLayoutVtransposed = decltype(tile_to_shape(
SmemLayoutAtomVtransposed{},
Shape<Int<kHeadDim>, Int<kBlockN>>{}));
// Maybe the VtransposeNoSwizzle just needs to have the right shape
// And the strides don't matter?
using SmemLayoutVtransposedNoSwizzle = decltype(tile_to_shape(
SmemLayoutAtomVtransposedNoSwizzle{},
Shape<Int<kHeadDim>, Int<kBlockN>>{}));
// using SmemLayoutVtransposedNoSwizzle = decltype(SmemLayoutVtransposed{}.layout_fn());
// https://github.com/ColfaxResearch/cutlass-kernels/blob/a222587e6d59b93ba704853d3946fb686d8b8892/src/fmha/fmha_forward.cu#L434
using SmemLayoutVtransposed = decltype(
composition(SmemLayoutKV{}, make_layout(Shape<Int<kHeadDim>, Int<kBlockN>>{}, GenRowMajor{})));
using SmemLayoutVtransposedNoSwizzle = decltype(get_nonswizzle_portion(SmemLayoutVtransposed{}));
using SmemLayoutAtomO = decltype(
composition(Swizzle<kSwizzle, 3, 3>{},
@ -116,10 +104,8 @@ struct Flash_fwd_kernel_traits : public Base {
using SmemCopyAtomO = Copy_Atom<DefaultCopy, Element>;
using SmemCopyAtomOaccum = Copy_Atom<DefaultCopy, ElementAccum>;
static constexpr int kSmemQCount = size(SmemLayoutQ{});
static constexpr int kSmemKVCount = size(SmemLayoutKV{}) * 2;
static constexpr int kSmemQSize = kSmemQCount * sizeof(Element);
static constexpr int kSmemKVSize = kSmemKVCount * sizeof(Element);
static constexpr int kSmemQSize = size(SmemLayoutQ{}) * sizeof(Element);
static constexpr int kSmemKVSize = size(SmemLayoutKV{}) * 2 * sizeof(Element);
static constexpr int kSmemSize = Share_Q_K_smem ? std::max(kSmemQSize, kSmemKVSize) : kSmemQSize + kSmemKVSize;
static constexpr int kGmemElemsPerLoad = sizeof(cute::uint128_t) / sizeof(Element);
@ -149,15 +135,6 @@ struct Flash_fwd_kernel_traits : public Base {
make_tiled_copy(Copy_Atom<DefaultCopy, Element>{},
GmemLayoutAtom{},
Layout<Shape<_1, _8>>{})); // Val layout, 8 vals per store
static constexpr int kGmemThreadsPerRowP = kBlockN / kGmemElemsPerLoad;
static_assert(kNThreads % kGmemThreadsPerRowP == 0, "kNThreads must be a multiple of kGmemThreadsPerRowP");
using GmemLayoutAtomP = Layout<Shape <Int<kNThreads / kGmemThreadsPerRowP>, Int<kGmemThreadsPerRowP>>,
Stride<Int<kGmemThreadsPerRowP>, _1>>;
using GmemTiledCopyP = decltype(
make_tiled_copy(Copy_Atom<DefaultCopy, Element>{},
GmemLayoutAtomP{},
Layout<Shape<_1, _8>>{})); // Val layout, 8 vals per store
using GmemLayoutAtomOaccum = std::conditional_t<
kBlockKSmem == 32,
@ -218,17 +195,17 @@ struct Flash_bwd_kernel_traits : public Base {
using TiledMmaSdP = TiledMMA<
typename Base::MMA_Atom_Arch,
Layout<Shape<Int<AtomLayoutMSdP>, Int<kNWarps / AtomLayoutMSdP>, _1>>,
typename Base::ValLayoutMNK>; // 1x2x1 or 1x2x2 value group for 16x16x16 MMA and LDSM
Tile<Int<16 * AtomLayoutMSdP>, Int<16 * kNWarps / AtomLayoutMSdP>, _16>>;
using TiledMmadKV = TiledMMA<
typename Base::MMA_Atom_Arch,
Layout<Shape<Int<AtomLayoutNdKV>, Int<kNWarps / AtomLayoutNdKV>, _1>>,
typename Base::ValLayoutMNK>; // 1x2x1 or 1x2x2 value group for 16x16x16 MMA and LDSM
Tile<Int<16 * AtomLayoutNdKV>, Int<16 * kNWarps / AtomLayoutNdKV>, _16>>;
using TiledMmadQ = TiledMMA<
typename Base::MMA_Atom_Arch,
Layout<Shape<Int<AtomLayoutMdQ>, Int<kNWarps / AtomLayoutMdQ>, _1>>, // 2x4x1 or 4x2x1 thread group
typename Base::ValLayoutMNK>; // 1x2x1 or 1x2x2 value group for 16x16x16 MMA and LDSM
Tile<Int<16 * AtomLayoutMdQ>, Int<16 * kNWarps / AtomLayoutMdQ>, _16>>;
using SmemLayoutAtomQdO = decltype(
composition(Swizzle<kSwizzle, 3, 3>{},
@ -247,26 +224,18 @@ struct Flash_bwd_kernel_traits : public Base {
SmemLayoutAtomKV{},
make_shape(Int<kBlockN>{}, Int<kHeadDim>{})));
using SmemLayoutAtomKtransposedNoSwizzle = Layout<Shape<Int<kBlockKSmem>, Int<kBlockN>>,
Stride<_1, Int<kBlockKSmem>>>;
using SmemLayoutAtomKtransposed = decltype(
composition(Swizzle<kSwizzle, 3, 3>{}, SmemLayoutAtomKtransposedNoSwizzle{}));
using SmemLayoutKtransposed = decltype(tile_to_shape(
SmemLayoutAtomKtransposed{},
make_shape(Int<kHeadDim>{}, Int<kBlockN>{})));
// Maybe the KtransposeNoSwizzle just needs to have the right shape
// And the strides don't matter?
using SmemLayoutKtransposedNoSwizzle = decltype(tile_to_shape(
SmemLayoutAtomKtransposedNoSwizzle{},
make_shape(Int<kHeadDim>{}, Int<kBlockN>{})));
// using SmemLayoutKtransposedNoSwizzle = decltype(SmemLayoutKtransposed{}.layout_fn());
using SmemLayoutKtransposed = decltype(
composition(SmemLayoutKV{}, make_layout(Shape<Int<kHeadDim>, Int<kBlockN>>{}, GenRowMajor{})));
using SmemLayoutKtransposedNoSwizzle = decltype(get_nonswizzle_portion(SmemLayoutKtransposed{}));
// TODO: generalize to other values of kBlockN
// TODO: what should be the Swizzle here? 3 is faster than 1, and 1 is faster than 2
// static constexpr int kPBlockN = kBlockN;
static_assert(kBlockN >= 64);
// Temporarily disabling this for hdim 256 on sm86 and sm89
// static_assert(kBlockN >= 64);
static_assert(kBlockN >= 32);
// TD [2023-03-19]: Idk why kPBlockN = 16 and kSwizzlePdS=3 is the fastest.
static constexpr int kPBlockN = 64;
static constexpr int kPBlockN = kBlockN >= 64 ? 64 : 32;
static_assert(kPBlockN == 16 || kPBlockN == 32 || kPBlockN == 64);
// static constexpr int kSwizzlePdS = kPBlockN == 16 ? 1 : (kPBlockN == 32 ? 2 : 3);
static constexpr int kSwizzlePdS = 3;
@ -277,30 +246,15 @@ struct Flash_bwd_kernel_traits : public Base {
using SmemLayoutPdS = decltype(tile_to_shape(
SmemLayoutAtomPdS{},
make_shape(Int<kBlockM>{}, Int<kBlockN>{})));
using SmemLayoutAtomPdStransposedNoSwizzle = Layout<Shape<Int<kPBlockN>, Int<kBlockM>>,
Stride<_1, Int<kPBlockN>>>;
using SmemLayoutAtomPdStransposed = decltype(
composition(Swizzle<kSwizzlePdS, 3, 3>{}, SmemLayoutAtomPdStransposedNoSwizzle{}));
using SmemLayoutPdStransposed = decltype(tile_to_shape(
SmemLayoutAtomPdStransposed{},
make_shape(Int<kBlockN>{}, Int<kBlockM>{})));
using SmemLayoutPdStransposedNoSwizzle = decltype(tile_to_shape(
SmemLayoutAtomPdStransposedNoSwizzle{},
make_shape(Int<kBlockN>{}, Int<kBlockM>{})));
// using SmemLayoutPdStransposedNoSwizzle = decltype(SmemLayoutPdStransposed{}.layout_fn());
using SmemLayoutPdStransposed = decltype(
composition(SmemLayoutPdS{}, make_layout(Shape<Int<kBlockN>, Int<kBlockM>>{}, GenRowMajor{})));
using SmemLayoutPdStransposedNoSwizzle = decltype(get_nonswizzle_portion(SmemLayoutPdStransposed{}));
using SmemCopyAtomPdS = Copy_Atom<DefaultCopy, elem_type>;
using SmemLayoutAtomQdOtransposedNoSwizzle = Layout<Shape<Int<kBlockKSmem>, Int<kBlockM>>,
Stride<_1, Int<kBlockKSmem>>>;
using SmemLayoutAtomQdOtransposed = decltype(
composition(Swizzle<kSwizzle, 3, 3>{}, SmemLayoutAtomQdOtransposedNoSwizzle{}));
using SmemLayoutQdOtransposed = decltype(tile_to_shape(
SmemLayoutAtomQdOtransposed{},
make_shape(Int<kHeadDim>{}, Int<kBlockM>{})));
using SmemLayoutQdOtransposedNoSwizzle = decltype(tile_to_shape(
SmemLayoutAtomQdOtransposedNoSwizzle{},
make_shape(Int<kHeadDim>{}, Int<kBlockM>{})));
// using SmemLayoutQdOtransposedNoSwizzle = decltype(SmemLayoutQdOtransposed{}.layout_fn());
using SmemLayoutQdOtransposed = decltype(
composition(SmemLayoutQdO{}, make_layout(Shape<Int<kHeadDim>, Int<kBlockM>>{}, GenRowMajor{})));
using SmemLayoutQdOtransposedNoSwizzle = decltype(get_nonswizzle_portion(SmemLayoutQdOtransposed{}));
using SmemLayoutAtomdKV = decltype(
composition(Swizzle<kSwizzle, 3, 3>{},
@ -320,16 +274,12 @@ struct Flash_bwd_kernel_traits : public Base {
make_shape(Int<kBlockM>{}, Int<kHeadDim>{})));
using SmemCopyAtomdQ = Copy_Atom<DefaultCopy, elem_type>;
static constexpr int kSmemQdOCount = size(SmemLayoutQdO{}) * (No_double_buffer ? 2 : 3); // Double buffer for sQ
static constexpr int kSmemKVCount = size(SmemLayoutKV{}) * 2;
static constexpr int kSmemdSCount = size(SmemLayoutPdS{});
static constexpr int kSmemPCount = size(SmemLayoutPdS{});
static constexpr int kSmemdQCount = size(SmemLayoutdQ{});
static constexpr int kSmemQdOSize = kSmemQdOCount * sizeof(Element);
static constexpr int kSmemKVSize = kSmemKVCount * sizeof(Element);
static constexpr int kSmemdSSize = kSmemdSCount * sizeof(Element);
static constexpr int kSmemPSize = kSmemPCount * sizeof(Element);
static constexpr int kSmemdQSize = kSmemdQCount * sizeof(Element);
// Double buffer for sQ
static constexpr int kSmemQdOSize = size(SmemLayoutQdO{}) * (No_double_buffer ? 2 : 3) * sizeof(Element);
static constexpr int kSmemKVSize = size(SmemLayoutKV{}) * 2 * sizeof(Element);
static constexpr int kSmemdSSize = size(SmemLayoutPdS{}) * sizeof(Element);
static constexpr int kSmemPSize = size(SmemLayoutPdS{}) * sizeof(Element);
static constexpr int kSmemdQSize = size(SmemLayoutdQ{}) * sizeof(Element);
static constexpr int kSmemSize = kSmemQdOSize
+ (!Is_V_in_regs
? kSmemKVSize + kSmemdSSize + std::max(kSmemPSize, kSmemdQSize)
@ -338,9 +288,6 @@ struct Flash_bwd_kernel_traits : public Base {
+ (!Is_V_in_regs
? kSmemKVSize + kSmemdSSize + kSmemPSize
: std::max(kSmemKVSize, kSmemKVSize / 2 + kSmemdSSize + kSmemPSize));
static constexpr int kSmemSize1rowblock = kSmemQdOSize / 3 * 2 + kSmemKVSize / 2 * 3
+ kSmemdSSize + kSmemPSize;
static constexpr int kGmemElemsPerLoad = sizeof(cute::uint128_t) / sizeof(Element);
static_assert(kHeadDim % kGmemElemsPerLoad == 0, "kHeadDim must be a multiple of kGmemElemsPerLoad");