vllm/csrc/cache_kernels.cu

387 lines
16 KiB
Plaintext

#include <torch/extension.h>
#include <ATen/cuda/CUDAContext.h>
#include <c10/cuda/CUDAGuard.h>
#include "cuda_compat.h"
#include "dispatch_utils.h"
#ifdef USE_ROCM
#include "quantization/fp8/amd/quant_utils.cuh"
#else
#include "quantization/fp8/nvidia/quant_utils.cuh"
#endif
#include <algorithm>
#include <cassert>
#include <map>
#include <vector>
#ifdef USE_ROCM
#include <hip/hip_bf16.h>
typedef __hip_bfloat16 __nv_bfloat16;
#endif
void swap_blocks(torch::Tensor& src, torch::Tensor& dst,
const torch::Tensor& block_mapping) {
torch::Device src_device = src.device();
torch::Device dst_device = dst.device();
cudaMemcpyKind memcpy_type;
if (src_device.is_cuda() && dst_device.is_cuda()) {
TORCH_CHECK(src_device.index() == dst_device.index(),
"src and dst must be on the same GPU");
memcpy_type = cudaMemcpyDeviceToDevice;
} else if (src_device.is_cuda() && dst_device.is_cpu()) {
memcpy_type = cudaMemcpyDeviceToHost;
} else if (src_device.is_cpu() && dst_device.is_cuda()) {
memcpy_type = cudaMemcpyHostToDevice;
} else {
TORCH_CHECK(false, "Invalid device combination");
}
// NOTE(youkaichao): keep in mind that `block_mapping` should be
// a cpu tensor, otherwise every `item` call will require a gpu-cpu
// synchronization.
TORCH_CHECK(block_mapping.device().is_cpu(), "block_mapping must be on CPU");
char* src_ptr = static_cast<char*>(src.data_ptr());
char* dst_ptr = static_cast<char*>(dst.data_ptr());
const int64_t block_size_in_bytes = src.element_size() * src[0].numel();
const at::cuda::OptionalCUDAGuard device_guard(
src_device.is_cuda() ? src_device : dst_device);
const cudaStream_t stream = at::cuda::getCurrentCUDAStream();
// NOTE(woosuk): This can be slow if the number of blocks is large.
const int64_t num_blocks = block_mapping.size(0);
for (size_t i = 0; i < num_blocks; i++) {
int64_t src_block_number = block_mapping[i][0].item<int64_t>();
int64_t dst_block_number = block_mapping[i][1].item<int64_t>();
int64_t src_offset = src_block_number * block_size_in_bytes;
int64_t dst_offset = dst_block_number * block_size_in_bytes;
cudaMemcpyAsync(dst_ptr + dst_offset, src_ptr + src_offset,
block_size_in_bytes, memcpy_type, stream);
}
}
namespace vllm {
// Grid: (num_layers, num_pairs)
template <typename scalar_t>
__global__ void copy_blocks_kernel(int64_t* key_cache_ptrs,
int64_t* value_cache_ptrs,
const int64_t* __restrict__ block_mapping,
const int numel_per_block) {
const int layer_idx = blockIdx.x;
const int pair_idx = blockIdx.y;
scalar_t* key_cache = reinterpret_cast<scalar_t*>(key_cache_ptrs[layer_idx]);
scalar_t* value_cache =
reinterpret_cast<scalar_t*>(value_cache_ptrs[layer_idx]);
int64_t src_block_number = block_mapping[2 * pair_idx];
int64_t dst_block_number = block_mapping[2 * pair_idx + 1];
const int64_t src_block_offset = src_block_number * numel_per_block;
const int64_t dst_block_offset = dst_block_number * numel_per_block;
for (int i = threadIdx.x; i < numel_per_block; i += blockDim.x) {
int64_t src_offset = src_block_offset + i;
int64_t dst_offset = dst_block_offset + i;
key_cache[dst_offset] = key_cache[src_offset];
}
for (int i = threadIdx.x; i < numel_per_block; i += blockDim.x) {
int64_t src_offset = src_block_offset + i;
int64_t dst_offset = dst_block_offset + i;
value_cache[dst_offset] = value_cache[src_offset];
}
}
} // namespace vllm
void copy_blocks(std::vector<torch::Tensor>& key_caches,
std::vector<torch::Tensor>& value_caches,
const torch::Tensor& block_mapping) {
int num_layers = key_caches.size();
TORCH_CHECK(num_layers == value_caches.size());
if (num_layers == 0) {
return;
}
torch::Device cache_device = key_caches[0].device();
TORCH_CHECK(cache_device.is_cuda());
// Create data structures for the kernel.
// Create an array of pointers to the key and value caches.
int64_t key_cache_ptrs[num_layers];
int64_t value_cache_ptrs[num_layers];
for (int layer_idx = 0; layer_idx < num_layers; ++layer_idx) {
key_cache_ptrs[layer_idx] =
reinterpret_cast<int64_t>(key_caches[layer_idx].data_ptr());
value_cache_ptrs[layer_idx] =
reinterpret_cast<int64_t>(value_caches[layer_idx].data_ptr());
}
// block_mapping is a 2D tensor with shape (num_pairs, 2).
int num_pairs = block_mapping.size(0);
// Move the data structures to the GPU.
// NOTE: This synchronizes the CPU and GPU.
torch::Tensor key_cache_ptrs_tensor =
torch::from_blob(key_cache_ptrs, {num_layers}, torch::kInt64)
.to(cache_device);
torch::Tensor value_cache_ptrs_tensor =
torch::from_blob(value_cache_ptrs, {num_layers}, torch::kInt64)
.to(cache_device);
// Launch the kernel.
const int numel_per_block = key_caches[0][0].numel();
dim3 grid(num_layers, num_pairs);
dim3 block(std::min(1024, numel_per_block));
const at::cuda::OptionalCUDAGuard device_guard(cache_device);
const cudaStream_t stream = at::cuda::getCurrentCUDAStream();
VLLM_DISPATCH_FLOATING_AND_BYTE_TYPES(
key_caches[0].scalar_type(), "copy_blocks_kernel", ([&] {
vllm::copy_blocks_kernel<scalar_t><<<grid, block, 0, stream>>>(
key_cache_ptrs_tensor.data_ptr<int64_t>(),
value_cache_ptrs_tensor.data_ptr<int64_t>(),
block_mapping.data_ptr<int64_t>(), numel_per_block);
}));
}
namespace vllm {
template <typename scalar_t, typename cache_t, Fp8KVCacheDataType kv_dt>
__global__ void reshape_and_cache_kernel(
const scalar_t* __restrict__ key, // [num_tokens, num_heads, head_size]
const scalar_t* __restrict__ value, // [num_tokens, num_heads, head_size]
cache_t* __restrict__ key_cache, // [num_blocks, num_heads, head_size/x,
// block_size, x]
cache_t* __restrict__ value_cache, // [num_blocks, num_heads, head_size,
// block_size]
const int64_t* __restrict__ slot_mapping, // [num_tokens]
const int key_stride, const int value_stride, const int num_heads,
const int head_size, const int block_size, const int x,
const float kv_scale) {
const int64_t token_idx = blockIdx.x;
const int64_t slot_idx = slot_mapping[token_idx];
if (slot_idx < 0) {
// Padding token that should be ignored.
return;
}
const int64_t block_idx = slot_idx / block_size;
const int64_t block_offset = slot_idx % block_size;
const int n = num_heads * head_size;
for (int i = threadIdx.x; i < n; i += blockDim.x) {
const int64_t src_key_idx = token_idx * key_stride + i;
const int64_t src_value_idx = token_idx * value_stride + i;
const int head_idx = i / head_size;
const int head_offset = i % head_size;
const int x_idx = head_offset / x;
const int x_offset = head_offset % x;
const int64_t tgt_key_idx =
block_idx * num_heads * (head_size / x) * block_size * x +
head_idx * (head_size / x) * block_size * x + x_idx * block_size * x +
block_offset * x + x_offset;
const int64_t tgt_value_idx =
block_idx * num_heads * head_size * block_size +
head_idx * head_size * block_size + head_offset * block_size +
block_offset;
scalar_t tgt_key = key[src_key_idx];
scalar_t tgt_value = value[src_value_idx];
if constexpr (kv_dt == Fp8KVCacheDataType::kAuto) {
key_cache[tgt_key_idx] = tgt_key;
value_cache[tgt_value_idx] = tgt_value;
} else {
key_cache[tgt_key_idx] =
fp8::scaled_convert<cache_t, scalar_t, kv_dt>(tgt_key, kv_scale);
value_cache[tgt_value_idx] =
fp8::scaled_convert<cache_t, scalar_t, kv_dt>(tgt_value, kv_scale);
}
}
}
template <typename scalar_t>
__global__ void reshape_and_cache_flash_kernel(
const scalar_t* __restrict__ key, // [num_tokens, num_heads, head_size]
const scalar_t* __restrict__ value, // [num_tokens, num_heads, head_size]
scalar_t* __restrict__ k_cache, // [num_blocks, block_size, num_heads,
// head_size]
scalar_t* __restrict__ v_cache, // [num_blocks, block_size, num_heads,
// head_size]
const int64_t* __restrict__ slot_mapping, // [num_tokens]
const int block_stride, const int key_stride, const int value_stride,
const int num_heads, const int head_size, const int block_size) {
const int64_t token_idx = blockIdx.x;
const int64_t slot_idx = slot_mapping[token_idx];
// NOTE: slot_idx can be -1 if the token is padded
if (slot_idx < 0) {
return;
}
const int64_t block_idx = slot_idx / block_size;
const int64_t block_offset = slot_idx % block_size;
const int n = num_heads * head_size;
for (int i = threadIdx.x; i < n; i += blockDim.x) {
const int64_t src_key_idx = token_idx * key_stride + i;
const int64_t src_value_idx = token_idx * value_stride + i;
const int head_idx = i / head_size;
const int head_offset = i % head_size;
const int64_t tgt_value_idx = block_idx * block_stride +
block_offset * num_heads * head_size +
head_idx * head_size + head_offset;
k_cache[tgt_value_idx] = key[src_key_idx];
v_cache[tgt_value_idx] = value[src_value_idx];
}
}
} // namespace vllm
// KV_T is the stored data type of kv-cache.
// CACHE_T is the data type of key and value tensors.
// KV_DTYPE is the real data type of kv-cache.
#define CALL_RESHAPE_AND_CACHE(KV_T, CACHE_T, KV_DTYPE) \
vllm::reshape_and_cache_kernel<KV_T, CACHE_T, KV_DTYPE> \
<<<grid, block, 0, stream>>>( \
reinterpret_cast<KV_T*>(key.data_ptr()), \
reinterpret_cast<KV_T*>(value.data_ptr()), \
reinterpret_cast<CACHE_T*>(key_cache.data_ptr()), \
reinterpret_cast<CACHE_T*>(value_cache.data_ptr()), \
slot_mapping.data_ptr<int64_t>(), key_stride, value_stride, \
num_heads, head_size, block_size, x, kv_scale);
void reshape_and_cache(
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, head_size/x, block_size, x]
torch::Tensor&
value_cache, // [num_blocks, num_heads, head_size, block_size]
torch::Tensor& slot_mapping, // [num_tokens]
const std::string& kv_cache_dtype, const float kv_scale) {
int num_tokens = key.size(0);
int num_heads = key.size(1);
int head_size = key.size(2);
int block_size = key_cache.size(3);
int x = key_cache.size(4);
int key_stride = key.stride(0);
int value_stride = value.stride(0);
dim3 grid(num_tokens);
dim3 block(std::min(num_heads * head_size, 512));
const at::cuda::OptionalCUDAGuard device_guard(device_of(key));
const cudaStream_t stream = at::cuda::getCurrentCUDAStream();
DISPATCH_BY_KV_CACHE_DTYPE(key.dtype(), kv_cache_dtype,
CALL_RESHAPE_AND_CACHE)
}
void reshape_and_cache_flash(
torch::Tensor& key, // [num_tokens, num_heads, head_size]
torch::Tensor& value, // [num_tokens, num_heads, head_size]
torch::Tensor& k_cache, // [num_blocks, block_size, num_heads, head_size]
torch::Tensor& v_cache, // [num_blocks, block_size, num_heads, head_size]
torch::Tensor& slot_mapping, // [num_tokens]
const std::string& kv_cache_dtype) {
// FIXME: only support auto datatype, does not support fp8
if (kv_cache_dtype != "auto") {
TORCH_CHECK(false, "Unsupported data type of kv cache: ", kv_cache_dtype);
}
int num_tokens = key.size(0);
int num_heads = key.size(1);
int head_size = key.size(2);
int block_size = k_cache.size(1);
int key_stride = key.stride(0);
int value_stride = value.stride(0);
int block_stride = k_cache.stride(0);
TORCH_CHECK(k_cache.stride(0) == v_cache.stride(0));
dim3 grid(num_tokens);
dim3 block(std::min(num_heads * head_size, 512));
const at::cuda::OptionalCUDAGuard device_guard(device_of(key));
const cudaStream_t stream = at::cuda::getCurrentCUDAStream();
VLLM_DISPATCH_FLOATING_TYPES(
key.scalar_type(), "reshape_and_cache_flash", [&] {
vllm::reshape_and_cache_flash_kernel<scalar_t>
<<<grid, block, 0, stream>>>(
key.data_ptr<scalar_t>(), value.data_ptr<scalar_t>(),
k_cache.data_ptr<scalar_t>(), v_cache.data_ptr<scalar_t>(),
slot_mapping.data_ptr<int64_t>(), block_stride, key_stride,
value_stride, num_heads, head_size, block_size);
});
}
namespace vllm {
template <typename Tout, typename Tin, Fp8KVCacheDataType kv_dt>
__global__ void convert_fp8_kernel(const Tin* __restrict__ src_cache,
Tout* __restrict__ dst_cache,
const float kv_scale,
const int64_t block_stride) {
const int64_t block_idx = blockIdx.x;
for (int i = threadIdx.x; i < block_stride; i += blockDim.x) {
int64_t idx = block_idx * block_stride + i;
dst_cache[idx] =
fp8::scaled_convert<Tout, Tin, kv_dt>(src_cache[idx], kv_scale);
}
}
} // namespace vllm
#define CALL_CONVERT_FP8(Tout, Tin, KV_DTYPE) \
vllm::convert_fp8_kernel<Tout, Tin, KV_DTYPE><<<grid, block, 0, stream>>>( \
reinterpret_cast<Tin*>(src_cache.data_ptr()), \
reinterpret_cast<Tout*>(dst_cache.data_ptr()), kv_scale, block_stride);
// Only for testing.
void convert_fp8(torch::Tensor& dst_cache, torch::Tensor& src_cache,
const float kv_scale, const std::string& kv_cache_dtype) {
torch::Device src_device = src_cache.device();
torch::Device dst_device = dst_cache.device();
TORCH_CHECK(src_device.is_cuda(), "src must be on a GPU")
TORCH_CHECK(dst_device.is_cuda(), "dst must be on a GPU")
TORCH_CHECK(src_device.index() == dst_device.index(),
"src and dst must be on the same GPU");
at::cuda::OptionalCUDAGuard device_guard(src_device);
int64_t num_blocks = src_cache.size(0);
int64_t block_stride = src_cache.stride(0);
dim3 grid(num_blocks);
dim3 block(std::min(block_stride, int64_t(512)));
const cudaStream_t stream = at::cuda::getCurrentCUDAStream();
if (kv_cache_dtype == "auto") {
if (src_cache.dtype() == at::ScalarType::Float) {
CALL_CONVERT_FP8(uint8_t, float, vllm::Fp8KVCacheDataType::kAuto);
} else if (src_cache.dtype() == at::ScalarType::Half) {
CALL_CONVERT_FP8(uint8_t, uint16_t, vllm::Fp8KVCacheDataType::kAuto);
} else if (src_cache.dtype() == at::ScalarType::BFloat16) {
CALL_CONVERT_FP8(uint8_t, __nv_bfloat16, vllm::Fp8KVCacheDataType::kAuto);
} else if (dst_cache.dtype() == at::ScalarType::Float) {
CALL_CONVERT_FP8(float, uint8_t, vllm::Fp8KVCacheDataType::kAuto);
} else if (dst_cache.dtype() == at::ScalarType::Half) {
CALL_CONVERT_FP8(uint16_t, uint8_t, vllm::Fp8KVCacheDataType::kAuto);
} else if (dst_cache.dtype() == at::ScalarType::BFloat16) {
CALL_CONVERT_FP8(__nv_bfloat16, uint8_t, vllm::Fp8KVCacheDataType::kAuto);
}
} else if (kv_cache_dtype == "fp8" || kv_cache_dtype == "fp8_e4m3") {
if (src_cache.dtype() == at::ScalarType::Float) {
CALL_CONVERT_FP8(uint8_t, float, vllm::Fp8KVCacheDataType::kFp8E4M3);
} else if (src_cache.dtype() == at::ScalarType::Half) {
CALL_CONVERT_FP8(uint8_t, uint16_t, vllm::Fp8KVCacheDataType::kFp8E4M3);
} else if (src_cache.dtype() == at::ScalarType::BFloat16) {
CALL_CONVERT_FP8(uint8_t, __nv_bfloat16,
vllm::Fp8KVCacheDataType::kFp8E4M3);
} else if (dst_cache.dtype() == at::ScalarType::Float) {
CALL_CONVERT_FP8(float, uint8_t, vllm::Fp8KVCacheDataType::kFp8E4M3);
} else if (dst_cache.dtype() == at::ScalarType::Half) {
CALL_CONVERT_FP8(uint16_t, uint8_t, vllm::Fp8KVCacheDataType::kFp8E4M3);
} else if (dst_cache.dtype() == at::ScalarType::BFloat16) {
CALL_CONVERT_FP8(__nv_bfloat16, uint8_t,
vllm::Fp8KVCacheDataType::kFp8E4M3);
}
} else {
TORCH_CHECK(false, "Unsupported data type: ", kv_cache_dtype);
}
}