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

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#include <ATen/cuda/CUDAContext.h>
#include <torch/extension.h>
#include "utils/vec_copy.h"
#include "funcs/cast_functor.h"
#include "common/micros.h"
using colossalAI::cuda::utils::get_vec_size;
using colossalAI::cuda::utils::copy;
using colossalAI::funcs::CastFunctor;
template<typename T, typename CacheT, bool Aligned, int VecSize>
__global__ void decode_kv_cache_memcpy_kernel(
const T* __restrict__ key,
const T* __restrict__ value,
CacheT* __restrict__ key_cache,
CacheT* __restrict__ value_cache,
const int* __restrict__ sequence_lengths,
const int* __restrict__ block_tables,
const int head_num,
const int head_dim,
const int block_size,
const int64_t key_stride,
const int64_t value_stride,
const int block_table_stride,
const int x
)
{
const int seq_id = blockIdx.x;
const int seq_len = sequence_lengths[seq_id] - 1;
const int block_offset = seq_len % block_size;
const int block_id = block_tables[seq_id * block_table_stride + seq_len / block_size];
const int hidden_size = head_num * head_dim;
if ( block_id < 0 ) {
return ;
}
int i = threadIdx.x * VecSize;
for (; i <= (hidden_size - VecSize); i += blockDim.x * VecSize) {
const int head_id = i / head_dim;
const int head_offset = i % head_dim;
const int x_id = head_offset / x;
const int x_offset = head_offset % x;
const int64_t key_src_id = seq_id * key_stride + i;
const int64_t value_src_id = seq_id * value_stride + i;
const int64_t target_key_id = block_id * hidden_size * block_size
+ head_id * block_size * head_dim
+ x_id * block_size * x
+ block_offset * x
+ x_offset;
const int64_t target_value_id = block_id * hidden_size * block_size
+ head_id * block_size * head_dim
+ block_offset * head_dim + head_offset;
copy<T, CacheT, VecSize>(key + key_src_id, key_cache + target_key_id);
copy<T, CacheT, VecSize>(value + value_src_id, value_cache + target_value_id);
}
if (!Aligned) {
for (; i < hidden_size; ++i ) {
const int head_id = i / head_dim;
const int head_offset = i % head_dim;
const int x_id = head_offset / x;
const int x_offset = head_offset % x;
const int64_t key_src_id = seq_id * key_stride + i;
const int64_t value_src_id = seq_id * value_stride + i;
const int64_t target_key_id = block_id * hidden_size * block_size
+ head_id * block_size * head_dim
+ x_id * block_size * x
+ block_offset * x
+ x_offset;
const int64_t target_value_id = block_id * hidden_size * block_size
+ head_id * block_size * head_dim
+ block_offset * head_dim + head_offset;
key_cache[target_key_id] = CastFunctor<T, CacheT>()(key[key_src_id]);
value_cache[target_value_id] = CastFunctor<T, CacheT>()(value[value_src_id]);
}
}
}
template<typename T, typename CacheT>
void apply_decode_kv_cache_memcpy(
at::Tensor& key, // [num_tokens, head_num, head_dim]
at::Tensor& value, // [num_tokens, head_num, head_dim]
at::Tensor& key_cache, // [num_blocks, head_num, head_dim/x, block_size, x]
at::Tensor& value_cache, // [num_blocks, head_num, block_size, head_dim]
at::Tensor& sequence_lengths, // [batch_size]
at::Tensor& block_tables) // [batch_size, max_seq_len]
{
int num_tokens = key.size(0);
int head_num = key.size(1);
int head_dim = key.size(2);
int block_size = key_cache.size(3);
int x = key_cache.size(4);
int64_t key_stride = key.stride(0);
int64_t value_stride = value.stride(0);
int block_table_stride = block_tables.stride(0);
int vec_size = get_vec_size<T>(key);
bool aligned = true;
if (head_dim % vec_size != 0) {
aligned = false;
}
int thread_nums = head_num * head_dim / vec_size;
const cudaStream_t stream = at::cuda::getCurrentCUDAStream();
dim3 grid(num_tokens);
dim3 block(std::min(thread_nums, 512));
#define DECODE_KV_CACHE_MEMCOPY_KERNEL_LAUNCH(__aligned, __vec_size) \
do { \
decode_kv_cache_memcpy_kernel<T, CacheT, __aligned, __vec_size><<<grid, block, 0, stream>>>( \
reinterpret_cast<T*>(key.data_ptr()), \
reinterpret_cast<T*>(value.data_ptr()), \
reinterpret_cast<CacheT*>(key_cache.data_ptr()), \
reinterpret_cast<CacheT*>(value_cache.data_ptr()), \
sequence_lengths.data_ptr<int>(), \
block_tables.data_ptr<int>(), \
head_num, \
head_dim, \
block_size, \
key_stride, \
value_stride, \
block_table_stride, \
x \
); \
} while(0)
#define DECODE_KV_CACHE_MEMCOPY_KERNEL_LAUNCH_VEC_SIZE_CASE(__aligned, __vec_size) \
do { \
switch (__vec_size) { \
case 1: \
DECODE_KV_CACHE_MEMCOPY_KERNEL_LAUNCH(__aligned, 1); \
break; \
case 2: \
DECODE_KV_CACHE_MEMCOPY_KERNEL_LAUNCH(__aligned, 2); \
break; \
case 4: \
DECODE_KV_CACHE_MEMCOPY_KERNEL_LAUNCH(__aligned, 4); \
break; \
default: \
AT_ERROR("Unsupported vectorized size ", __vec_size); \
break; \
} \
} while(0)
if (aligned) {
DECODE_KV_CACHE_MEMCOPY_KERNEL_LAUNCH_VEC_SIZE_CASE(true, vec_size);
}
else {
DECODE_KV_CACHE_MEMCOPY_KERNEL_LAUNCH_VEC_SIZE_CASE(false, vec_size);
}
AT_CUDA_CHECK(cudaGetLastError());
}
void decode_kv_cache_memcpy(
at::Tensor& key, // [num_tokens, head_num, head_dim]
at::Tensor& value, // [num_tokens, head_num, head_dim]
at::Tensor& key_cache, // [num_blocks, head_num, head_dim/x, block_size, x]
at::Tensor& value_cache, // [num_blocks, head_num, block_size, head_dim]
at::Tensor& sequence_lengths, // [batch_size]
at::Tensor& block_tables) // [batch_size, max_seq_len]
{
#define _(T, CacheT) \
apply_decode_kv_cache_memcpy<T, CacheT>( \
key, \
value, \
key_cache, \
value_cache, \
sequence_lengths, \
block_tables \
)
if(key_cache.scalar_type() == at::ScalarType::Byte)
{
switch (key.scalar_type())
{
case at::ScalarType::Float:
_(float, uint8_t);
break;
case at::ScalarType::Half:
_(half, uint8_t);
break;
case at::ScalarType::BFloat16:
_(__nv_bfloat16, uint8_t);
break;
}
}
else
{
switch (key.scalar_type())
{
case at::ScalarType::Float:
_(float, float);
break;
case at::ScalarType::Half:
_(half, half);
break;
case at::ScalarType::BFloat16:
_(__nv_bfloat16, __nv_bfloat16);
break;
}
}
#undef _
}