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DeepGEMM/deep_gemm/include/deep_gemm/fp8_gemm.cuh
AcraeaTerpsicore 96b31fd6bb
fix typo
2025-02-26 18:37:22 +08:00

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#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wunknown-attributes"
#pragma once
#include <cutlass/arch/barrier.h>
#include <cutlass/arch/reg_reconfig.h>
#include <cute/arch/cluster_sm90.hpp>
#include <cute/arch/copy_sm90_desc.hpp>
#include <cute/arch/copy_sm90_tma.hpp>
#include "mma_utils.cuh"
#include "scheduler.cuh"
#include "tma_utils.cuh"
#include "utils.cuh"
namespace deep_gemm {
enum class Layout {
RowMajor,
ColMajor
};
template <uint32_t kNumTMAThreads, uint32_t kNumMathThreadsPerGroup>
__device__ __host__ constexpr int get_num_threads_per_sm(int block_m) {
DG_STATIC_ASSERT(kNumMathThreadsPerGroup == 128, "Only support 128 threads per math group");
return (block_m == 64 ? 1 : 2) * kNumMathThreadsPerGroup + kNumTMAThreads;
}
template <uint32_t SHAPE_N, uint32_t SHAPE_K,
uint32_t BLOCK_M, uint32_t BLOCK_N, uint32_t BLOCK_K,
uint32_t kNumGroups, uint32_t kNumStages,
uint32_t kNumTMAThreads, uint32_t kNumMathThreadsPerGroup,
uint32_t kNumTMAMulticast,
GemmType kGemmType>
__global__ void __launch_bounds__(get_num_threads_per_sm<kNumTMAThreads, kNumMathThreadsPerGroup>(BLOCK_M), 1)
fp8_gemm_kernel(__nv_bfloat16* gmem_d, float* scales_b, int* grouped_layout,
uint32_t shape_m,
const __grid_constant__ CUtensorMap tensor_map_a,
const __grid_constant__ CUtensorMap tensor_map_b,
const __grid_constant__ CUtensorMap tensor_map_scales_a,
const __grid_constant__ CUtensorMap tensor_map_d) {
#if (defined(__CUDA_ARCH__) and (__CUDA_ARCH__ >= 900)) or defined(__CLION_IDE__)
// Scaling checks
DG_STATIC_ASSERT(BLOCK_K == 128, "Only support per-128-channel FP8 scaling");
DG_STATIC_ASSERT(ceil_div(BLOCK_N, BLOCK_K) == 1, "Too much B scales in a single block");
// Types
using WGMMA = typename FP8MMASelector<BLOCK_N>::type;
using Barrier = cutlass::arch::ClusterTransactionBarrier;
// Shared memory
static constexpr uint32_t SMEM_D_SIZE = BLOCK_M * BLOCK_N * sizeof(__nv_bfloat16);
static constexpr uint32_t SMEM_A_SIZE_PER_STAGE = BLOCK_M * BLOCK_K * sizeof(__nv_fp8_e4m3);
static constexpr uint32_t SMEM_B_SIZE_PER_STAGE = BLOCK_N * BLOCK_K * sizeof(__nv_fp8_e4m3);
static constexpr uint32_t SMEM_SCALES_A_SIZE_PER_STAGE = BLOCK_M * sizeof(float);
static constexpr uint32_t SHAPE_K_SCALES = ceil_div(SHAPE_K, BLOCK_K);
static constexpr int kMustUseUniformedScaleB = (BLOCK_K % BLOCK_N == 0);
// Configs
constexpr uint32_t kFullKOfAllStages = kNumStages * BLOCK_K;
constexpr uint32_t kNumThreads = get_num_threads_per_sm<kNumTMAThreads, kNumMathThreadsPerGroup>(BLOCK_M);
constexpr uint32_t kNumMathThreads = kNumThreads - kNumTMAThreads;
constexpr uint32_t kNumIterations = ceil_div(SHAPE_K, kFullKOfAllStages);
const uint32_t warp_idx = __shfl_sync(0xffffffff, threadIdx.x / 32, 0);
const uint32_t lane_idx = get_lane_id();
// Prefetch TMA descriptors at very beginning
if (threadIdx.x == kNumMathThreads) {
cute::prefetch_tma_descriptor(reinterpret_cast<cute::TmaDescriptor const*>(&tensor_map_a));
cute::prefetch_tma_descriptor(reinterpret_cast<cute::TmaDescriptor const*>(&tensor_map_b));
cute::prefetch_tma_descriptor(reinterpret_cast<cute::TmaDescriptor const*>(&tensor_map_scales_a));
cute::prefetch_tma_descriptor(reinterpret_cast<cute::TmaDescriptor const*>(&tensor_map_d));
}
__syncwarp();
// Align to 1024 bytes for swizzle-128B
extern __shared__ __align__(1024) uint8_t smem_buffer[];
DG_STATIC_ASSERT(SMEM_D_SIZE % 1024 == 0, "Shared memory of A/B must be aligned to 1024 bytes");
// Data on shared memory
auto smem_d = reinterpret_cast<__nv_bfloat16*>(smem_buffer);
__nv_fp8_e4m3* smem_a[kNumStages];
__nv_fp8_e4m3* smem_b[kNumStages];
float* smem_scales_a[kNumStages];
float* smem_scales_b;
// TMA Barrier for both divisible and non-divisible cases
Barrier* full_barriers[kNumStages];
Barrier* empty_barriers[kNumStages];
// Fill shared memory pointers
#pragma unroll
for (int i = 0; i < kNumStages; ++ i) {
smem_a[i] = reinterpret_cast<__nv_fp8_e4m3*>(smem_buffer + SMEM_D_SIZE + i * SMEM_A_SIZE_PER_STAGE);
smem_b[i] = reinterpret_cast<__nv_fp8_e4m3*>(smem_buffer + SMEM_D_SIZE + kNumStages * SMEM_A_SIZE_PER_STAGE + i * SMEM_B_SIZE_PER_STAGE);
smem_scales_a[i] = reinterpret_cast<float*>(smem_buffer + SMEM_D_SIZE + kNumStages * (SMEM_A_SIZE_PER_STAGE + SMEM_B_SIZE_PER_STAGE) + i * SMEM_SCALES_A_SIZE_PER_STAGE);
}
smem_scales_b = reinterpret_cast<float*>(smem_buffer + SMEM_D_SIZE + kNumStages * (SMEM_A_SIZE_PER_STAGE + SMEM_B_SIZE_PER_STAGE + SMEM_SCALES_A_SIZE_PER_STAGE));
// Fill barriers
DG_STATIC_ASSERT(sizeof(Barrier) % sizeof(float) == 0, "Misaligned barriers");
DG_STATIC_ASSERT(not kMustUseUniformedScaleB or SHAPE_K_SCALES % (sizeof(Barrier) / sizeof(float)) == 0, "Misaligned barriers");
auto barrier_start_ptr = reinterpret_cast<Barrier*>(smem_scales_b + SHAPE_K_SCALES * (kMustUseUniformedScaleB ? 1 : 2));
#pragma unroll
for (int i = 0; i < kNumStages; ++ i) {
full_barriers[i] = barrier_start_ptr + i;
empty_barriers[i] = barrier_start_ptr + kNumStages + i;
}
// Initialize barriers
DG_STATIC_ASSERT(kNumTMAMulticast <= 32, "To many TMA multicast");
if (threadIdx.x == kNumMathThreads) {
#pragma unroll
for (int i = 0; i < kNumStages; ++ i) {
full_barriers[i]->init(1);
empty_barriers[i]->init(kNumTMAMulticast * kNumMathThreads / 32);
}
// Make initialized barrier visible in async proxy
cutlass::arch::fence_view_async_shared();
(kNumTMAMulticast > 1) ? cutlass::arch::fence_barrier_init() : void();
}
// Synchronize all threads to make barrier visible in normal memory model
(kNumTMAMulticast > 1) ? cute::cluster_sync() : __syncthreads();
// For pipeline unrolling
struct DivisibleK {};
struct NotDivisibleK {};
auto launch_k_iterations = [](const auto& func) {
if constexpr (SHAPE_K % kFullKOfAllStages == 0) {
for (int k_iter = 0; k_iter < kNumIterations; ++ k_iter)
func(k_iter, DivisibleK{});
} else {
for (int k_iter = 0; k_iter < kNumIterations - 1; ++ k_iter)
func(k_iter, DivisibleK{});
func(kNumIterations - 1, NotDivisibleK{});
}
};
// Register reconfigurations
constexpr int kNumTMARegisters = 40;
constexpr int kNumMathRegisters = 232;
// Block scheduler
uint32_t m_block_idx, n_block_idx;
auto scheduler = Scheduler<kGemmType, SHAPE_N, BLOCK_M, BLOCK_N, kNumGroups, kNumTMAMulticast>(shape_m, grouped_layout);
if (threadIdx.x >= kNumMathThreads) {
// TMA warp-group for loading data
cutlass::arch::warpgroup_reg_dealloc<kNumTMARegisters>();
// NOTES: only one thread (or warp) will be used
if (threadIdx.x == kNumMathThreads) {
// Persistently schedule over blocks
while (scheduler.get_next_block(m_block_idx, n_block_idx)) {
launch_k_iterations([&](int k_iter, auto type) {
constexpr bool kHasDivisibleStages = std::is_same_v<decltype(type), DivisibleK>;
constexpr int kNumInnerStages = kHasDivisibleStages ? kNumStages : (SHAPE_K % kFullKOfAllStages) / BLOCK_K;
DG_STATIC_ASSERT(kNumInnerStages != 0, "Invalid number of inner stages");
#pragma unroll
for (uint32_t s = 0; s < kNumInnerStages; ++ s) {
// Wait consumer release
empty_barriers[s]->wait((scheduler.current_iter * kNumIterations + k_iter + 1) & 1);
// Issue TMA A with broadcasting
auto& full_barrier = *full_barriers[s];
int k_idx = k_iter * kFullKOfAllStages + s * BLOCK_K;
tma_copy<kNumTMAMulticast>(&tensor_map_a, reinterpret_cast<uint64_t*>(&full_barrier),
smem_a[s], k_idx, scheduler.get_global_idx(shape_m, BLOCK_M, m_block_idx));
tma_copy<kNumTMAMulticast>(&tensor_map_scales_a, reinterpret_cast<uint64_t*>(&full_barrier),
smem_scales_a[s], m_block_idx * BLOCK_M,
scheduler.get_global_idx(SHAPE_K_SCALES, 1, k_idx / BLOCK_K));
// Issue TMA B without broadcasting
tma_copy(&tensor_map_b, reinterpret_cast<uint64_t*>(&full_barrier),
smem_b[s], k_idx, scheduler.get_global_idx<false>(SHAPE_N, BLOCK_N, n_block_idx, m_block_idx));
full_barrier.arrive_and_expect_tx(SMEM_A_SIZE_PER_STAGE + SMEM_B_SIZE_PER_STAGE + SMEM_SCALES_A_SIZE_PER_STAGE);
}
// Wait unaligned cases
#pragma unroll
for (uint32_t s = kNumInnerStages; s < kNumStages; ++ s) {
empty_barriers[s]->wait((scheduler.current_iter * kNumIterations + k_iter + 1) & 1);
full_barriers[s]->arrive();
}
});
}
// To safely deconstruct distributed shared barriers, we need another round of empty waits
if constexpr (kNumTMAMulticast > 1) {
#pragma unroll
for (uint32_t s = 0; s < kNumStages; ++ s)
empty_barriers[s]->wait((scheduler.current_iter * kNumIterations + 1) & 1);
}
}
} else {
// Math warp-groups for WGMMA
cutlass::arch::warpgroup_reg_alloc<kNumMathRegisters>();
// NOTES: use `__shfl_sync` to encourage NVCC to use unified registers
const auto math_wg_idx = __shfl_sync(0xffffffff, threadIdx.x / kNumMathThreadsPerGroup, 0);
const auto r_0 = warp_idx * 16 + lane_idx / 4, r_1 = r_0 + 8;
// Persistently schedule over blocks
while (scheduler.get_next_block(m_block_idx, n_block_idx)) {
// Decide the number of scales B to load
DG_STATIC_ASSERT(SHAPE_N % 8 == 0, "Invalid shape N");
uint32_t num_former_iters = BLOCK_N / 8, num_full_iters = num_former_iters;
if constexpr (not kMustUseUniformedScaleB) {
num_former_iters = min(BLOCK_N, BLOCK_K - n_block_idx * BLOCK_N % BLOCK_K) / 8;
num_full_iters = min(SHAPE_N - n_block_idx * BLOCK_N, BLOCK_N) / 8;
}
uint32_t num_scales_b = SHAPE_K_SCALES * (num_former_iters >= num_full_iters ? 1 : 2);
// Load B scales with math warp-groups
// NOTES: except the first warp, we want to overlap loading B scales with TMA stores between tasks
if (threadIdx.x >= 32) {
auto num_previous_lines = scheduler.get_global_idx<false>(ceil_div(SHAPE_N, BLOCK_K), 0, 0, m_block_idx);
auto local_scales_b = scales_b + (num_previous_lines + ((n_block_idx * BLOCK_N) / BLOCK_K)) * SHAPE_K_SCALES;
#pragma unroll
for (uint32_t i = threadIdx.x - 32; i < num_scales_b; i += kNumMathThreads - 32)
st_shared(smem_scales_b + i, __ldg(local_scales_b + i));
}
cutlass::arch::NamedBarrier(kNumMathThreads).sync();
// Accumulation for WGMMA or CUDA promotion
float accum[WGMMA::kNumAccum], final_accum[WGMMA::kNumAccum] = {0};
// Empty barrier arrival
auto empty_barrier_arrive = [&](int s) {
if constexpr (kNumTMAMulticast == 1) {
lane_idx == 0 ? empty_barriers[s]->arrive() : void();
} else {
lane_idx < kNumTMAMulticast ? empty_barriers[s]->arrive(lane_idx) : void();
}
};
// Launch MMAs
launch_k_iterations([&](int k_iter, auto type) {
constexpr bool kHasDivisibleStages = std::is_same_v<decltype(type), DivisibleK>;
constexpr int kNumInnerStages = kHasDivisibleStages ? kNumStages : (SHAPE_K % kFullKOfAllStages) / BLOCK_K;
DG_STATIC_ASSERT(kNumInnerStages != 0, "Invalid number of inner stages");
#pragma unroll
for (int s = 0; s < kNumInnerStages; ++ s) {
// Read B scales
float scale_b_0 = ld_shared(smem_scales_b + k_iter * kNumStages + s), scale_b_1;
// NOTES: even some blocks do not need to read the second row, but we still load one to align with other blocks
if constexpr (not kMustUseUniformedScaleB)
scale_b_1 = ld_shared(smem_scales_b + k_iter * kNumStages + s + SHAPE_K_SCALES);
// Wait TMA arrivals
full_barriers[s]->wait((scheduler.current_iter * kNumIterations + k_iter) & 1);
// Read A scales
// NOTES: all shared memory read must be prior to `warpgroup_arrive` to avoid next scheduled block polluting the results
auto scale_a_0 = ld_shared(smem_scales_a[s] + r_0), scale_a_1 = ld_shared(smem_scales_a[s] + r_1);
// Commit WGMMA instructions
#pragma unroll
for (int i = 0; i < WGMMA::kNumAccum; ++ i)
warpgroup_fence_operand(accum[i]);
warpgroup_arrive();
#pragma unroll
for (int k = 0; k < BLOCK_K / WGMMA::K; ++ k) {
auto desc_a = make_smem_desc(smem_a[s] + math_wg_idx * WGMMA::M * BLOCK_K + k * WGMMA::K, 1);
auto desc_b = make_smem_desc(smem_b[s] + k * WGMMA::K, 1);
WGMMA::wgmma(desc_a, desc_b, accum, k);
}
warpgroup_commit_batch();
#pragma unroll
for (int i = 0; i < WGMMA::kNumAccum; ++ i)
warpgroup_fence_operand(accum[i]);
warpgroup_wait<0>();
// Notify barrier arrival
empty_barrier_arrive(s);
// Promote with scales
float scale_0_0 = scale_a_0 * scale_b_0, scale_1_0 = scale_a_1 * scale_b_0;
float scale_0_1, scale_1_1;
if constexpr (not kMustUseUniformedScaleB)
scale_0_1 = scale_a_0 * scale_b_1, scale_1_1 = scale_a_1 * scale_b_1;
#pragma unroll
for (int i = 0; i < WGMMA::kNumAccum / 4; ++ i) {
bool predicate = kMustUseUniformedScaleB or i < num_former_iters;
final_accum[i * 4 + 0] += (predicate ? scale_0_0 : scale_0_1) * accum[i * 4 + 0];
final_accum[i * 4 + 1] += (predicate ? scale_0_0 : scale_0_1) * accum[i * 4 + 1];
final_accum[i * 4 + 2] += (predicate ? scale_1_0 : scale_1_1) * accum[i * 4 + 2];
final_accum[i * 4 + 3] += (predicate ? scale_1_0 : scale_1_1) * accum[i * 4 + 3];
}
}
// Wait unaligned cases
#pragma unroll
for (uint32_t s = kNumInnerStages; s < kNumStages; ++ s) {
full_barriers[s]->wait((scheduler.current_iter * kNumIterations + k_iter) & 1);
empty_barrier_arrive(s);
}
});
// Write back to shared memory using STSM
DG_STATIC_ASSERT(WGMMA::kNumAccum % 4 == 0, "Invalid STSM x2 vectorization");
#pragma unroll
for (auto i = 0; i < WGMMA::kNumAccum / 8; ++ i) {
SM90_U32x4_STSM_N<nv_bfloat162>::copy(
__float22bfloat162_rn({final_accum[i * 8 + 0], final_accum[i * 8 + 1]}),
__float22bfloat162_rn({final_accum[i * 8 + 2], final_accum[i * 8 + 3]}),
__float22bfloat162_rn({final_accum[i * 8 + 4], final_accum[i * 8 + 5]}),
__float22bfloat162_rn({final_accum[i * 8 + 6], final_accum[i * 8 + 7]}),
smem_d + (warp_idx * 16 + lane_idx % 16) * BLOCK_N + i * 16 + 8 * (lane_idx / 16)
);
}
if constexpr (WGMMA::kNumAccum % 8 != 0) {
SM90_U32x2_STSM_N<nv_bfloat162>::copy(
__float22bfloat162_rn({final_accum[WGMMA::kNumAccum / 8 * 8 + 0], final_accum[WGMMA::kNumAccum / 8 * 8 + 1]}),
__float22bfloat162_rn({final_accum[WGMMA::kNumAccum / 8 * 8 + 2], final_accum[WGMMA::kNumAccum / 8 * 8 + 3]}),
smem_d + (warp_idx * 16 + lane_idx % 16) * BLOCK_N + WGMMA::kNumAccum / 8 * 16
);
}
cute::tma_store_fence();
cutlass::arch::NamedBarrier(kNumMathThreads).sync();
// Use TMA store to write back to global memory
if (threadIdx.x == 0) {
cute::SM90_TMA_STORE_2D::copy(&tensor_map_d, smem_d, n_block_idx * BLOCK_N,
scheduler.get_global_idx(shape_m, BLOCK_M, m_block_idx));
cute::tma_store_arrive();
cute::tma_store_wait<0>();
}
__syncwarp();
}
}
#else
if (blockIdx.x == 0 and threadIdx.x == 0)
DG_DEVICE_ASSERT(false and "This kernel only support sm_90a");
#endif
}
template <uint32_t SHAPE_N, uint32_t SHAPE_K,
uint32_t BLOCK_M, uint32_t BLOCK_N, uint32_t BLOCK_K,
uint32_t kNumGroups, uint32_t kNumStages,
uint32_t kNumTMAMulticast,
GemmType kGemmType>
class Gemm {
private:
using Barrier = cuda::barrier<cuda::thread_scope_block>;
public:
Gemm() = default;
static void run(__nv_bfloat16* gmem_d, float* scales_b, int* grouped_layout,
uint32_t shape_m,
const CUtensorMap& tma_a_desc,
const CUtensorMap& tma_b_desc,
const CUtensorMap& tma_scales_a_desc,
const CUtensorMap& tma_d_desc,
cudaStream_t stream,
int num_sms, uint32_t smem_size) {
// NOTES: we must use 4 warps to do TMA, because `setmaxnreg.aligned` requires 4 warps
constexpr uint32_t kNumTMAThreads = 128;
constexpr uint32_t kNumMathThreadsPerGroup = 128;
auto kernel = fp8_gemm_kernel<SHAPE_N, SHAPE_K, BLOCK_M, BLOCK_N, BLOCK_K,
kNumGroups, kNumStages, kNumTMAThreads, kNumMathThreadsPerGroup,
kNumTMAMulticast, kGemmType>;
DG_HOST_ASSERT(cudaFuncSetAttribute(kernel, cudaFuncAttributeMaxDynamicSharedMemorySize, smem_size) == cudaSuccess);
// Cluster launch
cudaLaunchConfig_t config;
config.gridDim = num_sms;
config.blockDim = get_num_threads_per_sm<kNumTMAThreads, kNumMathThreadsPerGroup>(BLOCK_M);
config.dynamicSmemBytes = smem_size;
config.stream = stream;
// Clusters for TMA multicast
// NOTES: `>= 4` cluster size will cause performance degradation
cudaLaunchAttribute attr;
attr.id = cudaLaunchAttributeClusterDimension;
attr.val.clusterDim = {kNumTMAMulticast, 1, 1};
config.attrs = &attr;
config.numAttrs = 1;
// Launch
auto status = cudaLaunchKernelEx(&config, kernel,
gmem_d, scales_b, grouped_layout,
shape_m,
tma_a_desc, tma_b_desc, tma_scales_a_desc, tma_d_desc);
DG_HOST_ASSERT(status == cudaSuccess);
}
template <typename T>
static CUtensorMap make_2d_tma_a_desc(T* global_address, uint32_t shape_m) {
return make_2d_tma_desc(global_address, Layout::RowMajor,
shape_m * (kGemmType == GemmType::GroupedMasked ? kNumGroups : 1), SHAPE_K, BLOCK_M, BLOCK_K);
}
template <typename T>
static CUtensorMap make_2d_tma_b_desc(T* global_address) {
return make_2d_tma_desc(global_address, Layout::ColMajor,
SHAPE_K, SHAPE_N * (kGemmType != GemmType::Normal ? kNumGroups : 1), BLOCK_K, BLOCK_N);
}
template <typename T>
static CUtensorMap make_2d_tma_d_desc(T* global_address, uint32_t shape_m) {
return make_2d_tma_desc(global_address, Layout::RowMajor,
shape_m * (kGemmType == GemmType::GroupedMasked ? kNumGroups : 1), SHAPE_N, BLOCK_M, BLOCK_N,
CUtensorMapSwizzle::CU_TENSOR_MAP_SWIZZLE_NONE);
}
template <typename T>
static CUtensorMap make_2d_tma_scales_a_desc(T* global_address, uint32_t shape_m) {
// Make TMA aligned to 16 bytes
constexpr uint32_t kAlignment = 16 / sizeof(T);
shape_m = ceil_div(shape_m, kAlignment) * kAlignment;
return make_2d_tma_desc(global_address, Layout::ColMajor,
shape_m, ceil_div(SHAPE_K, BLOCK_K) * (kGemmType == GemmType::GroupedMasked ? kNumGroups : 1), BLOCK_M, 1,
CUtensorMapSwizzle::CU_TENSOR_MAP_SWIZZLE_NONE);
}
template <typename T>
static CUtensorMap make_2d_tma_desc(
T* global_address, Layout layout,
uint32_t gmem_rows, uint32_t gmem_cols,
uint32_t smem_rows, uint32_t smem_cols,
CUtensorMapSwizzle swizzle_type = CUtensorMapSwizzle::CU_TENSOR_MAP_SWIZZLE_128B) {
if (layout == Layout::RowMajor) {
uint64_t gmem_dim[2] = {gmem_cols, gmem_rows};
uint32_t smem_dim[2] = {smem_cols, smem_rows};
return make_2d_tma_copy_desc(global_address, gmem_dim, gmem_cols * sizeof(T), smem_dim, swizzle_type);
} else {
uint64_t gmem_dim[2] = {gmem_rows, gmem_cols};
uint32_t smem_dim[2] = {smem_rows, smem_cols};
return make_2d_tma_copy_desc(global_address, gmem_dim, gmem_rows * sizeof(T), smem_dim, swizzle_type);
}
}
};
}; // namespace deep_gemm
#pragma clang diagnostic pop
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