vllm/csrc/pos_encoding_kernels.cu

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#include <torch/all.h>
#include <ATen/cuda/CUDAContext.h>
#include <c10/cuda/CUDAGuard.h>
#include "cuda_compat.h"
#include "dispatch_utils.h"
namespace vllm {
template <typename scalar_t, bool IS_NEOX>
inline __device__ void apply_token_rotary_embedding(
scalar_t* __restrict__ arr, const scalar_t* __restrict__ cos_ptr,
const scalar_t* __restrict__ sin_ptr, int rot_offset, int embed_dim) {
int x_index, y_index;
scalar_t cos, sin;
if (IS_NEOX) {
// GPT-NeoX style rotary embedding.
x_index = rot_offset;
y_index = embed_dim + rot_offset;
cos = VLLM_LDG(cos_ptr + x_index);
sin = VLLM_LDG(sin_ptr + x_index);
} else {
// GPT-J style rotary embedding.
x_index = 2 * rot_offset;
y_index = 2 * rot_offset + 1;
cos = VLLM_LDG(cos_ptr + x_index / 2);
sin = VLLM_LDG(sin_ptr + x_index / 2);
}
const scalar_t x = arr[x_index];
const scalar_t y = arr[y_index];
arr[x_index] = x * cos - y * sin;
arr[y_index] = y * cos + x * sin;
}
template <typename scalar_t, bool IS_NEOX>
inline __device__ void apply_rotary_embedding(
scalar_t* __restrict__ query, // [batch_size, seq_len, num_heads,
// head_size] or [num_tokens, num_heads,
// head_size]
scalar_t* __restrict__ key, // [batch_size, seq_len, num_kv_heads,
// head_size] or [num_tokens, num_kv_heads,
// head_size]
const scalar_t* cache_ptr, const int head_size, const int num_heads,
const int num_kv_heads, const int rot_dim, const int token_idx,
const int64_t query_stride, const int64_t key_stride) {
const int embed_dim = rot_dim / 2;
const scalar_t* cos_ptr = cache_ptr;
const scalar_t* sin_ptr = cache_ptr + embed_dim;
const int nq = num_heads * embed_dim;
for (int i = threadIdx.x; i < nq; i += blockDim.x) {
const int head_idx = i / embed_dim;
const int64_t token_head = token_idx * query_stride + head_idx * head_size;
const int rot_offset = i % embed_dim;
apply_token_rotary_embedding<scalar_t, IS_NEOX>(
query + token_head, cos_ptr, sin_ptr, rot_offset, embed_dim);
}
const int nk = num_kv_heads * embed_dim;
for (int i = threadIdx.x; i < nk; i += blockDim.x) {
const int head_idx = i / embed_dim;
const int64_t token_head = token_idx * key_stride + head_idx * head_size;
const int rot_offset = i % embed_dim;
apply_token_rotary_embedding<scalar_t, IS_NEOX>(
key + token_head, cos_ptr, sin_ptr, rot_offset, embed_dim);
}
}
template <typename scalar_t, bool IS_NEOX>
__global__ void rotary_embedding_kernel(
const int64_t* __restrict__ positions, // [batch_size, seq_len] or
// [num_tokens]
scalar_t* __restrict__ query, // [batch_size, seq_len, num_heads,
// head_size] or [num_tokens, num_heads,
// head_size]
scalar_t* __restrict__ key, // [batch_size, seq_len, num_kv_heads,
// head_size] or [num_tokens, num_kv_heads,
// head_size]
const scalar_t* __restrict__ cos_sin_cache, // [max_position, 2, rot_dim //
// 2]
const int rot_dim, const int64_t query_stride, const int64_t key_stride,
const int num_heads, const int num_kv_heads, const int head_size) {
// Each thread block is responsible for one token.
const int token_idx = blockIdx.x;
int64_t pos = positions[token_idx];
const scalar_t* cache_ptr = cos_sin_cache + pos * rot_dim;
apply_rotary_embedding<scalar_t, IS_NEOX>(
query, key, cache_ptr, head_size, num_heads, num_kv_heads, rot_dim,
token_idx, query_stride, key_stride);
}
template <typename scalar_t, bool IS_NEOX>
__global__ void batched_rotary_embedding_kernel(
const int64_t* __restrict__ positions, // [batch_size, seq_len] or
// [num_tokens]
scalar_t* __restrict__ query, // [batch_size, seq_len, num_heads,
// head_size] or [num_tokens, num_heads,
// head_size]
scalar_t* __restrict__ key, // [batch_size, seq_len, num_kv_heads,
// head_size] or [num_tokens, num_kv_heads,
// head_size]
const scalar_t* __restrict__ cos_sin_cache, // [max_position, 2, rot_dim //
// 2]
const int64_t* __restrict__ cos_sin_cache_offsets, // [batch_size, seq_len]
// or [num_tokens]
const int rot_dim, const int64_t query_stride, const int64_t key_stride,
const int num_heads, const int num_kv_heads, const int head_size) {
// Each thread block is responsible for one token.
const int token_idx = blockIdx.x;
int64_t pos = positions[token_idx];
int64_t cos_sin_cache_offset = cos_sin_cache_offsets[token_idx];
const scalar_t* cache_ptr =
cos_sin_cache + (cos_sin_cache_offset + pos) * rot_dim;
apply_rotary_embedding<scalar_t, IS_NEOX>(
query, key, cache_ptr, head_size, num_heads, num_kv_heads, rot_dim,
token_idx, query_stride, key_stride);
}
} // namespace vllm
void rotary_embedding(
torch::Tensor& positions, // [batch_size, seq_len] or [num_tokens]
torch::Tensor& query, // [batch_size, seq_len, num_heads * head_size] or
// [num_tokens, num_heads * head_size] or
// [batch_size, seq_len, num_heads, head_size] or
// [num_tokens, num_heads, head_size]
torch::Tensor& key, // [batch_size, seq_len, num_kv_heads * head_size] or
// [num_tokens, num_kv_heads * head_size] or
// [batch_size, seq_len, num_heads, head_size] or
// [num_tokens, num_heads, head_size]
int64_t head_size,
torch::Tensor& cos_sin_cache, // [max_position, rot_dim]
bool is_neox) {
// num_tokens = batch_size * seq_len
int64_t num_tokens = positions.numel();
int positions_ndim = positions.dim();
// Make sure num_tokens dim is consistent across positions, query, and key.
TORCH_CHECK(
positions_ndim == 1 || positions_ndim == 2,
"positions must have shape [num_tokens] or [batch_size, seq_len]");
if (positions_ndim == 1) {
TORCH_CHECK(
query.size(0) == positions.size(0) && key.size(0) == positions.size(0),
"query, key and positions must have the same number of tokens");
}
if (positions_ndim == 2) {
TORCH_CHECK(
query.size(0) == positions.size(0) &&
key.size(0) == positions.size(0) &&
query.size(1) == positions.size(1) &&
key.size(1) == positions.size(1),
"query, key and positions must have the same batch_size and seq_len");
}
// Make sure head_size is valid for query and key
// hidden_size = num_heads * head_size
int query_hidden_size = query.numel() / num_tokens;
int key_hidden_size = key.numel() / num_tokens;
TORCH_CHECK(query_hidden_size % head_size == 0);
TORCH_CHECK(key_hidden_size % head_size == 0);
// Make sure query and key have consistent number of heads
int num_heads = query_hidden_size / head_size;
int num_kv_heads = key_hidden_size / head_size;
TORCH_CHECK(num_heads % num_kv_heads == 0);
int rot_dim = cos_sin_cache.size(1);
int seq_dim_idx = positions_ndim - 1;
int64_t query_stride = query.stride(seq_dim_idx);
int64_t key_stride = key.stride(seq_dim_idx);
dim3 grid(num_tokens);
dim3 block(std::min<int64_t>(num_heads * rot_dim / 2, 512));
const at::cuda::OptionalCUDAGuard device_guard(device_of(query));
const cudaStream_t stream = at::cuda::getCurrentCUDAStream();
VLLM_DISPATCH_FLOATING_TYPES(query.scalar_type(), "rotary_embedding", [&] {
if (is_neox) {
vllm::rotary_embedding_kernel<scalar_t, true><<<grid, block, 0, stream>>>(
positions.data_ptr<int64_t>(), query.data_ptr<scalar_t>(),
key.data_ptr<scalar_t>(), cos_sin_cache.data_ptr<scalar_t>(), rot_dim,
query_stride, key_stride, num_heads, num_kv_heads, head_size);
} else {
vllm::rotary_embedding_kernel<scalar_t, false>
<<<grid, block, 0, stream>>>(
positions.data_ptr<int64_t>(), query.data_ptr<scalar_t>(),
key.data_ptr<scalar_t>(), cos_sin_cache.data_ptr<scalar_t>(),
rot_dim, query_stride, key_stride, num_heads, num_kv_heads,
head_size);
}
});
}
/*
Batched version of rotary embedding, pack multiple LoRAs together
and process in batched manner.
*/
void batched_rotary_embedding(
torch::Tensor& positions, // [batch_size, seq_len] or [num_tokens]
torch::Tensor& query, // [batch_size, seq_len, num_heads * head_size] or
// [num_tokens, num_heads * head_size] or
// [batch_size, seq_len, num_heads, head_size] or
// [num_tokens, num_heads, head_size]
torch::Tensor& key, // [batch_size, seq_len, num_kv_heads * head_size] or
// [num_tokens, num_kv_heads * head_size] or
// [batch_size, seq_len, num_heads, head_size] or
// [num_tokens, num_heads, head_size]
int64_t head_size,
torch::Tensor& cos_sin_cache, // [max_position, rot_dim]
bool is_neox, int64_t rot_dim,
torch::Tensor& cos_sin_cache_offsets // [num_tokens] or [batch_size]
) {
// num_tokens = batch_size * seq_len
int64_t num_tokens = cos_sin_cache_offsets.size(0);
TORCH_CHECK(
positions.size(0) == num_tokens || positions.numel() == num_tokens,
"positions must have the same num_tokens or batch_size as "
"cos_sin_cache_offsets");
int positions_ndim = positions.dim();
// Make sure num_tokens dim is consistent across positions, query, and key.
TORCH_CHECK(
positions_ndim == 1 || positions_ndim == 2,
"positions must have shape [num_tokens] or [batch_size, seq_len]");
if (positions_ndim == 1) {
TORCH_CHECK(
query.size(0) == positions.size(0) && key.size(0) == positions.size(0),
"query, key and positions must have the same number of tokens");
}
if (positions_ndim == 2) {
TORCH_CHECK(
query.size(0) == positions.size(0) &&
key.size(0) == positions.size(0) &&
query.size(1) == positions.size(1) &&
key.size(1) == positions.size(1),
"query, key and positions must have the same batch_size and seq_len");
}
// Make sure head_size is valid for query and key
int query_hidden_size = query.numel() / num_tokens;
int key_hidden_size = key.numel() / num_tokens;
TORCH_CHECK(query_hidden_size % head_size == 0);
TORCH_CHECK(key_hidden_size % head_size == 0);
// Make sure query and key have concistent number of heads
int num_heads = query_hidden_size / head_size;
int num_kv_heads = key_hidden_size / head_size;
TORCH_CHECK(num_heads % num_kv_heads == 0);
int seq_dim_idx = positions_ndim - 1;
int64_t query_stride = query.stride(seq_dim_idx);
int64_t key_stride = key.stride(seq_dim_idx);
dim3 grid(num_tokens);
dim3 block(std::min<int64_t>(num_heads * rot_dim / 2, 512));
const at::cuda::OptionalCUDAGuard device_guard(device_of(query));
const cudaStream_t stream = at::cuda::getCurrentCUDAStream();
VLLM_DISPATCH_FLOATING_TYPES(query.scalar_type(), "rotary_embedding", [&] {
if (is_neox) {
vllm::batched_rotary_embedding_kernel<scalar_t, true>
<<<grid, block, 0, stream>>>(
positions.data_ptr<int64_t>(), query.data_ptr<scalar_t>(),
key.data_ptr<scalar_t>(), cos_sin_cache.data_ptr<scalar_t>(),
cos_sin_cache_offsets.data_ptr<int64_t>(), rot_dim, query_stride,
key_stride, num_heads, num_kv_heads, head_size);
} else {
vllm::batched_rotary_embedding_kernel<scalar_t, false>
<<<grid, block, 0, stream>>>(
positions.data_ptr<int64_t>(), query.data_ptr<scalar_t>(),
key.data_ptr<scalar_t>(), cos_sin_cache.data_ptr<scalar_t>(),
cos_sin_cache_offsets.data_ptr<int64_t>(), rot_dim, query_stride,
key_stride, num_heads, num_kv_heads, head_size);
}
});
}