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#include <ATen/cuda/CUDAContext.h>
#include <torch/extension.h>
#include <c10/cuda/CUDAGuard.h>
#define VLLM_LDG(arg) *(arg)
#define VLLM_DISPATCH_CASE_FLOATING_TYPES(...) \
AT_DISPATCH_CASE(at::ScalarType::Float, __VA_ARGS__) \
AT_DISPATCH_CASE(at::ScalarType::Half, __VA_ARGS__) \
AT_DISPATCH_CASE(at::ScalarType::BFloat16, __VA_ARGS__)
#define VLLM_DISPATCH_FLOATING_TYPES(TYPE, NAME, ...) \
AT_DISPATCH_SWITCH( \
TYPE, NAME, VLLM_DISPATCH_CASE_FLOATING_TYPES(__VA_ARGS__))
template<typename T>
__device__ __forceinline__ T silu(const T& x) {
// x * sigmoid(x)
return (T) (((float) x) / (1.0f + expf((float) -x)));
}
template<typename scalar_t>
__global__ void silu_and_mul_kernel(
scalar_t* __restrict__ out, // [..., d]
const scalar_t* __restrict__ input, // [..., 2, d]
const int d) {
const int64_t token_idx = blockIdx.x;
for (int64_t idx = threadIdx.x; idx < d; idx += blockDim.x) {
const scalar_t x = VLLM_LDG(&input[token_idx * 2 * d + idx]);
const scalar_t y = VLLM_LDG(&input[token_idx * 2 * d + d + idx]);
out[token_idx * d + idx] = silu(x) * y;
}
}
void silu_and_mul(
torch::Tensor& out, // [..., d]
torch::Tensor& input) // [..., 2 * d]
{
int64_t num_tokens = input.numel() / input.size(-1);
int d = input.size(-1) / 2;
dim3 grid(num_tokens);
dim3 block(std::min(d, 1024));
const at::cuda::OptionalCUDAGuard device_guard(device_of(input));
const cudaStream_t stream = at::cuda::getCurrentCUDAStream();
VLLM_DISPATCH_FLOATING_TYPES(
input.scalar_type(),
"silu_and_mul_kernel",
[&] {
silu_and_mul_kernel<scalar_t><<<grid, block, 0, stream>>>(
out.data_ptr<scalar_t>(),
input.data_ptr<scalar_t>(),
d);
});
} |