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[sgl-kernel] Support float64 moe_sum_reduce cuda kernel (#11068)

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Co-authored-by: luoyuan.luo <luoyuan.luo@antgroup.com>
This commit is contained in:
Yuan Luo
2025-10-07 22:31:11 +08:00
committed by GitHub
parent 3ddd7dc9f8
commit 4f42c8cd3e
2 changed files with 222 additions and 88 deletions
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238
sgl-kernel/csrc/moe/moe_sum_reduce.cu
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@@ -1,3 +1,4 @@
#include <ATen/OpMathType.h>
#include <ATen/cuda/CUDAContext.h>
#include <c10/cuda/CUDAGuard.h>
#include <cuda.h>
@@ -12,25 +13,36 @@
#include "utils.h"
template <typename T>
__device__ __forceinline__ float to_float(T x) {
return static_cast<float>(x);
}
using opmath_t = at::opmath_type<T>;
template <>
__device__ __forceinline__ float to_float<half>(half x) {
return __half2float(x);
template <typename T>
__device__ __forceinline__ opmath_t<T> to_acc(T x) {
return static_cast<opmath_t<T>>(x);
}
template <typename T>
__device__ __forceinline__ T from_float(float x) {
__device__ __forceinline__ T from_acc(opmath_t<T> x) {
return static_cast<T>(x);
}
template <>
__device__ __forceinline__ half from_float<half>(float x) {
__device__ __forceinline__ opmath_t<at::Half> to_acc<at::Half>(at::Half x) {
return __half2float(__nv_half(x));
}
template <>
__device__ __forceinline__ at::Half from_acc<at::Half>(opmath_t<at::Half> x) {
return __float2half_rn(x);
}
template <>
__device__ __forceinline__ opmath_t<at::BFloat16> to_acc<at::BFloat16>(at::BFloat16 x) {
return __bfloat162float(__nv_bfloat16(x));
}
template <>
__device__ __forceinline__ at::BFloat16 from_acc<at::BFloat16>(opmath_t<at::BFloat16> x) {
return __float2bfloat16_rn(x);
}
template <typename T>
__device__ __forceinline__ T ldg_cg(const T* p) {
return __ldg(p);
@@ -111,22 +123,22 @@ __global__ void moe_sum_reduce_kernel_warp_token_topk(
const int64_t stride_token,
const int64_t stride_topk,
const int64_t out_stride_token,
const float scale) {
const opmath_t<scalar_t> scale) {
const int warp_id = threadIdx.x / 32;
const int lane = threadIdx.x % 32;
const int64_t t = (int64_t)blockIdx.y * WARPS_PER_BLOCK + warp_id;
if (t >= token_num) return;
for (int64_t d = (int64_t)blockIdx.x * 32 + lane; d < hidden_dim; d += (int64_t)gridDim.x * 32) {
float acc = 0.f;
opmath_t<scalar_t> acc = opmath_t<scalar_t>(0);
const int64_t base = t * stride_token + d;
#pragma unroll
for (int k = 0; k < TOPK; ++k) {
acc += to_float<scalar_t>(ldg_cg(&x[base + (int64_t)k * stride_topk]));
acc += to_acc<scalar_t>(x[base + (int64_t)k * stride_topk]);
}
acc *= scale;
y[t * out_stride_token + d] = from_float<scalar_t>(acc);
y[t * out_stride_token + d] = from_acc<scalar_t>(acc);
}
}
@@ -139,23 +151,79 @@ __global__ void moe_sum_reduce_kernel(
const int64_t stride_token,
const int64_t stride_topk,
const int64_t out_stride_token,
const float scale) {
const opmath_t<scalar_t> scale) {
for (int t = blockIdx.y; t < token_num; t += gridDim.y) {
for (int d = blockIdx.x * blockDim.x + threadIdx.x; d < hidden_dim; d += blockDim.x * gridDim.x) {
const int64_t base = t * stride_token + d;
float acc = 0.f;
opmath_t<scalar_t> acc = opmath_t<scalar_t>(0);
#pragma unroll
for (int k = 0; k < TOPK; ++k) {
acc += to_float<scalar_t>(x[base + (int64_t)k * stride_topk]);
acc += to_acc<scalar_t>(x[base + (int64_t)k * stride_topk]);
}
acc *= scale;
y[t * out_stride_token + d] = from_float<scalar_t>(acc);
y[t * out_stride_token + d] = from_acc<scalar_t>(acc);
}
}
}
// -------------------- general-topk fallback kernels --------------------
// small-token
template <typename scalar_t>
__global__ void moe_sum_reduce_kernel_general(
const scalar_t* __restrict__ x,
scalar_t* __restrict__ y,
const int64_t token_num,
const int64_t hidden_dim,
const int64_t stride_token,
const int64_t stride_topk,
const int64_t out_stride_token,
const int topk_num,
const opmath_t<scalar_t> scale) {
for (int t = blockIdx.y; t < token_num; t += gridDim.y) {
for (int d = blockIdx.x * blockDim.x + threadIdx.x; d < hidden_dim; d += blockDim.x * gridDim.x) {
const int64_t base = t * stride_token + d;
opmath_t<scalar_t> acc = opmath_t<scalar_t>(0);
#pragma unroll 1
for (int k = 0; k < topk_num; ++k) {
acc += to_acc<scalar_t>(x[base + (int64_t)k * stride_topk]);
}
acc *= scale;
y[t * out_stride_token + d] = from_acc<scalar_t>(acc);
}
}
}
// warp-per-token
template <typename scalar_t, int WARPS_PER_BLOCK>
__global__ void moe_sum_reduce_kernel_warp_token_general(
const scalar_t* __restrict__ x,
scalar_t* __restrict__ y,
const int64_t token_num,
const int64_t hidden_dim,
const int64_t stride_token,
const int64_t stride_topk,
const int64_t out_stride_token,
const int topk_num,
const opmath_t<scalar_t> scale) {
const int warp_id = threadIdx.x / 32;
const int lane = threadIdx.x % 32;
const int64_t t = (int64_t)blockIdx.y * WARPS_PER_BLOCK + warp_id;
if (t >= token_num) return;
for (int64_t d = (int64_t)blockIdx.x * 32 + lane; d < hidden_dim; d += (int64_t)gridDim.x * 32) {
opmath_t<scalar_t> acc = opmath_t<scalar_t>(0);
const int64_t base = t * stride_token + d;
#pragma unroll 1
for (int k = 0; k < topk_num; ++k) {
acc += to_acc<scalar_t>(x[base + (int64_t)k * stride_topk]);
}
acc *= scale;
y[t * out_stride_token + d] = from_acc<scalar_t>(acc);
}
}
void moe_sum_reduce(at::Tensor& input, at::Tensor& output, double routed_scaling_factor) {
TORCH_CHECK(input.is_cuda(), "input must be CUDA tensor");
TORCH_CHECK(output.is_cuda(), "output must be CUDA tensor");
@@ -175,8 +243,6 @@ void moe_sum_reduce(at::Tensor& input, at::Tensor& output, double routed_scaling
const int64_t in_stride_topk = input.stride(1);
const int64_t out_stride_token = output.stride(0);
const float scale = static_cast<float>(routed_scaling_factor);
auto stream = at::cuda::getCurrentCUDAStream();
const bool fast_bf16_vec_ok = (input.scalar_type() == at::kBFloat16) && (token_num > 256) && (hidden_dim % 8 == 0);
@@ -198,6 +264,7 @@ void moe_sum_reduce(at::Tensor& input, at::Tensor& output, double routed_scaling
auto stream = at::cuda::getCurrentCUDAStream();
const float scale = static_cast<float>(routed_scaling_factor);
moe_sum_reduce_warp_per_token_vec_kernel<WARPS_PER_BLOCK><<<grid, block, 0, stream>>>(
reinterpret_cast<const at::BFloat16*>(input.data_ptr<at::BFloat16>()),
reinterpret_cast<at::BFloat16*>(output.data_ptr<at::BFloat16>()),
@@ -209,32 +276,12 @@ void moe_sum_reduce(at::Tensor& input, at::Tensor& output, double routed_scaling
out_stride_token,
scale);
TORCH_CHECK(cudaGetLastError() == cudaSuccess, "moe_sum_reduce CUDA kernel launch failed");
TORCH_CHECK(cudaGetLastError() == cudaSuccess, "moe_sum_reduce CUDA kernel (bf16 vec) launch failed");
return;
}
const bool per_token_use_one_warp = (token_num > 128);
auto dispatch_topk = [&](auto&& launch_kernel) {
switch (topk_num) {
case 2:
launch_kernel(std::integral_constant<int, 2>{});
break;
case 4:
launch_kernel(std::integral_constant<int, 4>{});
break;
case 8:
launch_kernel(std::integral_constant<int, 8>{});
break;
case 9:
launch_kernel(std::integral_constant<int, 9>{});
break;
default:
launch_kernel(std::integral_constant<int, -1>{});
break;
}
};
if (!per_token_use_one_warp) {
// ---------- small-token ----------
const int block_size = 256;
@@ -245,28 +292,55 @@ void moe_sum_reduce(at::Tensor& input, at::Tensor& output, double routed_scaling
dim3 block(block_size);
dim3 grid(static_cast<unsigned>(grid_x), static_cast<unsigned>(grid_y));
#define LAUNCH_SMALL_TOKEN_KERNEL(TOPK) \
moe_sum_reduce_kernel<scalar_t_, TOPK><<<grid, block, 0, stream>>>( \
input.data_ptr<scalar_t_>(), \
output.data_ptr<scalar_t_>(), \
token_num, \
hidden_dim, \
in_stride_token, \
in_stride_topk, \
out_stride_token, \
scale);
AT_DISPATCH_FLOATING_TYPES_AND2(
at::kHalf, at::kBFloat16, input.scalar_type(), "moe_sum_reduce_cuda_small_token", [&] {
using scalar_t_ = scalar_t;
using acc_t_ = opmath_t<scalar_t_>;
const acc_t_ scale = static_cast<acc_t_>(routed_scaling_factor);
auto lauch_small_token_kernel = [&](auto topk_c) {
constexpr int TK = decltype(topk_c)::value;
moe_sum_reduce_kernel<scalar_t_, TK><<<grid, block, 0, stream>>>(
input.data_ptr<scalar_t_>(),
output.data_ptr<scalar_t_>(),
token_num,
hidden_dim,
in_stride_token,
in_stride_topk,
out_stride_token,
scale);
};
dispatch_topk(lauch_small_token_kernel);
switch (topk_num) {
case 2:
LAUNCH_SMALL_TOKEN_KERNEL(2);
break;
case 4:
LAUNCH_SMALL_TOKEN_KERNEL(4);
break;
case 8:
LAUNCH_SMALL_TOKEN_KERNEL(8);
break;
case 9:
LAUNCH_SMALL_TOKEN_KERNEL(9);
break;
default: // launch general kernel
moe_sum_reduce_kernel_general<scalar_t_><<<grid, block, 0, stream>>>(
input.data_ptr<scalar_t_>(),
output.data_ptr<scalar_t_>(),
token_num,
hidden_dim,
in_stride_token,
in_stride_topk,
out_stride_token,
static_cast<int>(topk_num),
scale);
}
});
#undef LAUNCH_SMALL_TOKEN_KERNEL
TORCH_CHECK(cudaGetLastError() == cudaSuccess, "moe_sum_reduce CUDA kernel (small-token) launch failed");
} else {
// ---------- warp-token ----------
// ---------- warp-per-token ----------
constexpr int WARPS_PER_BLOCK = 4;
constexpr int THREADS = WARPS_PER_BLOCK * 32;
@@ -279,25 +353,51 @@ void moe_sum_reduce(at::Tensor& input, at::Tensor& output, double routed_scaling
dim3 block(THREADS);
dim3 grid(static_cast<unsigned>(gx), static_cast<unsigned>(gy));
#define LAUNCH_WARP_PER_TOKEN_KERNEL(TOPK) \
moe_sum_reduce_kernel_warp_token_topk<scalar_t_, TOPK, WARPS_PER_BLOCK><<<grid, block, 0, stream>>>( \
input.data_ptr<scalar_t_>(), \
output.data_ptr<scalar_t_>(), \
token_num, \
hidden_dim, \
in_stride_token, \
in_stride_topk, \
out_stride_token, \
scale);
AT_DISPATCH_FLOATING_TYPES_AND2(
at::kHalf, at::kBFloat16, input.scalar_type(), "moe_sum_reduce_cuda_large_token", [&] {
using scalar_t_ = scalar_t;
using acc_t_ = opmath_t<scalar_t_>;
const acc_t_ scale = static_cast<acc_t_>(routed_scaling_factor);
auto launch_large_token_kernel = [&](auto topk_c) {
constexpr int TK = decltype(topk_c)::value;
moe_sum_reduce_kernel_warp_token_topk<scalar_t_, TK, WARPS_PER_BLOCK><<<grid, block, 0, stream>>>(
input.data_ptr<scalar_t_>(),
output.data_ptr<scalar_t_>(),
token_num,
hidden_dim,
in_stride_token,
in_stride_topk,
out_stride_token,
scale);
};
dispatch_topk(launch_large_token_kernel);
switch (topk_num) {
case 2:
LAUNCH_WARP_PER_TOKEN_KERNEL(2);
break;
case 4:
LAUNCH_WARP_PER_TOKEN_KERNEL(4);
break;
case 8:
LAUNCH_WARP_PER_TOKEN_KERNEL(8);
break;
case 9:
LAUNCH_WARP_PER_TOKEN_KERNEL(9);
break;
default: // launch general kernel
moe_sum_reduce_kernel_warp_token_general<scalar_t_, WARPS_PER_BLOCK><<<grid, block, 0, stream>>>(
input.data_ptr<scalar_t_>(),
output.data_ptr<scalar_t_>(),
token_num,
hidden_dim,
in_stride_token,
in_stride_topk,
out_stride_token,
static_cast<int>(topk_num),
scale);
}
});
#undef LAUNCH_WARP_PER_TOKEN_KERNEL
TORCH_CHECK(cudaGetLastError() == cudaSuccess, "moe_sum_reduce CUDA kernel (warp-token) launch failed");
}
TORCH_CHECK(cudaGetLastError() == cudaSuccess, "CUDA kernel launch failed");
}