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sglang/sgl-kernel/csrc/moe/moe_sum.cu

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#include <ATen/ATen.h>
#include <ATen/cuda/CUDAContext.h>
#include <c10/cuda/CUDAGuard.h>
#include <torch/all.h>
#include <ATen/cuda/Atomic.cuh>
#include <cub/cub.cuh>
#include "utils.h"
template <typename scalar_t, int TOPK>
__global__ void moe_sum_kernel(
scalar_t* __restrict__ out, // [..., d]
const scalar_t* __restrict__ input, // [..., topk, d]
const int d) {
const int64_t token_idx = blockIdx.x;
for (int64_t idx = threadIdx.x; idx < d; idx += blockDim.x) {
scalar_t x = 0.0;
#pragma unroll
for (int k = 0; k < TOPK; ++k) {
x += SGLANG_LDG(&input[token_idx * TOPK * d + k * d + idx]);
}
out[token_idx * d + idx] = x;
}
}
void moe_sum(
torch::Tensor& input, // [num_tokens, topk, hidden_size]
torch::Tensor& output) // [num_tokens, hidden_size]
{
const int hidden_size = input.size(-1);
const auto num_tokens = output.numel() / hidden_size;
const int topk = input.size(1);
dim3 grid(num_tokens);
dim3 block(std::min(hidden_size, 1024));
const at::cuda::OptionalCUDAGuard device_guard(device_of(output));
const cudaStream_t stream = at::cuda::getCurrentCUDAStream();
switch (topk) {
case 2:
DISPATCH_FLOAT_TYPES(input.scalar_type(), "moe_sum_kernel", [&] {
moe_sum_kernel<scalar_t, 2>
<<<grid, block, 0, stream>>>(output.data_ptr<scalar_t>(), input.data_ptr<scalar_t>(), hidden_size);
});
break;
case 3:
DISPATCH_FLOAT_TYPES(input.scalar_type(), "moe_sum_kernel", [&] {
moe_sum_kernel<scalar_t, 3>
<<<grid, block, 0, stream>>>(output.data_ptr<scalar_t>(), input.data_ptr<scalar_t>(), hidden_size);
});
break;
case 4:
DISPATCH_FLOAT_TYPES(input.scalar_type(), "moe_sum_kernel", [&] {
moe_sum_kernel<scalar_t, 4>
<<<grid, block, 0, stream>>>(output.data_ptr<scalar_t>(), input.data_ptr<scalar_t>(), hidden_size);
});
break;
default:
at::sum_out(output, input, 1);
break;
}
}