ColossalAI/extensions/csrc/cuda/decode_kv_cache_memcpy_kern...

91 lines
3.1 KiB
Plaintext

#include <ATen/cuda/CUDAContext.h>
#include <torch/extension.h>
#include <stdio.h>
#include "type_shim.h"
template<typename scalar_t>
__global__ void decode_kv_cache_memcpy_kernel(
const scalar_t* __restrict__ key,
const scalar_t* __restrict__ value,
scalar_t* __restrict__ key_cache,
scalar_t* __restrict__ value_cache,
const int* __restrict__ sequence_lengths,
const int* __restrict__ block_tables,
const int num_heads,
const int head_size,
const int block_size,
const int key_stride,
const int value_stride,
const int block_table_stride
)
{
const int seq_id = blockIdx.x;
const int seq_len = sequence_lengths[seq_id] - 1;
const int seq_id_in_block_table = seq_len / block_size;
const int block_offset = seq_len % block_size;
const int block_id = block_tables[seq_id * block_table_stride + seq_id_in_block_table];
const int hidden_size = num_heads * head_size;
if ( block_id < 0 ) {
return ;
}
for (int i = threadIdx.x; i < hidden_size; i += blockDim.x) {
const int head_id = i / head_size;
const int head_offset = i % head_size;
const int key_src_id = seq_id * key_stride + i;
const int value_src_id = seq_id * value_stride + i;
const int target_src_id = block_id * hidden_size * block_size
+ head_id * block_size * head_size
+ block_offset * head_size + head_offset;
key_cache[target_src_id] = key[key_src_id];
value_cache[target_src_id] = value[value_src_id];
}
}
void decode_kv_cache_memcpy(
torch::Tensor& key, // [num_tokens, num_heads, head_size]
torch::Tensor& value, // [num_tokens, num_heads, head_size]
torch::Tensor& key_cache, // [num_blocks, num_heads, block_size, head_size]
torch::Tensor& value_cache, // [num_blocks, num_heads, block_size, head_size]
torch::Tensor& sequence_lengths, // [batch_size]
torch::Tensor& block_tables) // [batch_size, max_seq_len]
{
int num_tokens = key.size(0);
int num_heads = key.size(1);
int head_size = key.size(2);
int block_size = key_cache.size(2);
int key_stride = key.stride(0);
int value_stride = value.stride(0);
int block_table_stride = block_tables.stride(0);
const cudaStream_t stream = at::cuda::getCurrentCUDAStream();
dim3 grid(num_tokens);
dim3 block(std::min(num_heads * head_size, 512));
DISPATCH_FLOAT_HALF_AND_BFLOAT(
key.scalar_type(),
"decode_kv_cache_memcpy",
decode_kv_cache_memcpy_kernel<scalar_t><<<grid, block, 0, stream>>>(
key.data_ptr<scalar_t>(),
value.data_ptr<scalar_t>(),
key_cache.data_ptr<scalar_t>(),
value_cache.data_ptr<scalar_t>(),
sequence_lengths.data_ptr<int>(),
block_tables.data_ptr<int>(),
num_heads,
head_size,
block_size,
key_stride,
value_stride,
block_table_stride
);)
AT_CUDA_CHECK(cudaGetLastError());
}