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sglang/sgl-kernel/csrc/moe/cutlass_moe/w4a8/w4a8_moe_data.cu
2025-07-04 20:50:12 -07:00

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#include <c10/cuda/CUDAGuard.h>
#include <cudaTypedefs.h>
#include <torch/all.h>
#include <iostream>
constexpr uint64_t THREADS_PER_EXPERT = 512;
__global__ void compute_problem_sizes_w4a8(
const int32_t* __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] = 2 * n;
problem_sizes1[expert_id * 3 + 1] = final_occurrences;
problem_sizes1[expert_id * 3 + 2] = k;
problem_sizes2[expert_id * 3] = k;
problem_sizes2[expert_id * 3 + 1] = final_occurrences;
problem_sizes2[expert_id * 3 + 2] = n;
}
}
__global__ void compute_expert_offsets_w4a8(
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 + 1];
expert_offsets[i + 1] = tot_offset;
}
}
void get_cutlass_w4a8_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_w4a8<<<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_w4a8<<<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);
}