ElizaWszola 9239bf718e
[Kernel] CUTLASS grouped gemm fp8 MoE kernel (#13972)
Signed-off-by: ElizaWszola <eliza@neuralmagic.com>
Signed-off-by: ElizaWszola <ewszola@redhat.com>
Co-authored-by: Lucas Wilkinson <wilkinson.lucas@gmail.com>
2025-03-27 00:54:44 +00:00

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#include <cudaTypedefs.h>
#include <c10/cuda/CUDAGuard.h>
#include <torch/all.h>
#include <iostream>
constexpr uint64_t THREADS_PER_EXPERT = 512;
__global__ void compute_problem_sizes(const int* __restrict__ topk_ids,
int32_t* problem_sizes1,
int32_t* problem_sizes2,
int32_t* atomic_buffer,
const int topk_length, const int n,
const int k) {
int expert_id = blockIdx.x;
int occurrences = 0;
for (int i = threadIdx.x; i < topk_length; i += THREADS_PER_EXPERT) {
occurrences += (topk_ids[i] == expert_id);
}
atomicAdd(&atomic_buffer[expert_id], occurrences);
__syncthreads();
if (threadIdx.x == 0) {
int final_occurrences = atomic_buffer[expert_id];
problem_sizes1[expert_id * 3] = final_occurrences;
problem_sizes1[expert_id * 3 + 1] = 2 * n;
problem_sizes1[expert_id * 3 + 2] = k;
problem_sizes2[expert_id * 3] = final_occurrences;
problem_sizes2[expert_id * 3 + 1] = k;
problem_sizes2[expert_id * 3 + 2] = n;
}
}
__global__ void compute_expert_offsets(
const int32_t* __restrict__ problem_sizes1, int32_t* expert_offsets,
int32_t* atomic_buffer, const int num_experts) {
int32_t tot_offset = 0;
expert_offsets[0] = 0;
for (int i = 0; i < num_experts; ++i) {
atomic_buffer[i] = tot_offset;
tot_offset += problem_sizes1[i * 3];
expert_offsets[i + 1] = tot_offset;
}
}
__global__ void compute_arg_sorts(const int* __restrict__ topk_ids,
int32_t* input_permutation,
int32_t* output_permutation,
int32_t* atomic_buffer, const int topk_length,
const int topk) {
int expert_id = blockIdx.x;
for (int i = threadIdx.x; i < topk_length; i += THREADS_PER_EXPERT) {
if (topk_ids[i] == expert_id) {
int start = atomicAdd(&atomic_buffer[expert_id], 1);
input_permutation[start] = i / topk;
output_permutation[i] = start;
}
}
}
void get_cutlass_moe_mm_data_caller(
const torch::Tensor& topk_ids, torch::Tensor& expert_offsets,
torch::Tensor& problem_sizes1, torch::Tensor& problem_sizes2,
torch::Tensor& input_permutation, torch::Tensor& output_permutation,
const int64_t num_experts, const int64_t n, const int64_t k) {
auto stream = at::cuda::getCurrentCUDAStream(topk_ids.device().index());
auto options_int32 =
torch::TensorOptions().dtype(torch::kInt32).device(topk_ids.device());
torch::Tensor atomic_buffer = torch::zeros(num_experts, options_int32);
int num_threads = min(THREADS_PER_EXPERT, topk_ids.numel());
compute_problem_sizes<<<num_experts, num_threads, 0, stream>>>(
static_cast<const int32_t*>(topk_ids.data_ptr()),
static_cast<int32_t*>(problem_sizes1.data_ptr()),
static_cast<int32_t*>(problem_sizes2.data_ptr()),
static_cast<int32_t*>(atomic_buffer.data_ptr()), topk_ids.numel(), n, k);
compute_expert_offsets<<<1, 1, 0, stream>>>(
static_cast<const int32_t*>(problem_sizes1.data_ptr()),
static_cast<int32_t*>(expert_offsets.data_ptr()),
static_cast<int32_t*>(atomic_buffer.data_ptr()), num_experts);
compute_arg_sorts<<<num_experts, num_threads, 0, stream>>>(
static_cast<const int32_t*>(topk_ids.data_ptr()),
static_cast<int32_t*>(input_permutation.data_ptr()),
static_cast<int32_t*>(output_permutation.data_ptr()),
static_cast<int32_t*>(atomic_buffer.data_ptr()), topk_ids.numel(),
topk_ids.size(1));
}