vllm/csrc/moe/moe_align_sum_kernels.cu
gnovack ea657f2078
Lora MoE Align Improvements (#29257)
Signed-off-by: gnovack <gnovack@amazon.com>
2025-12-09 10:35:16 +08:00

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29 KiB
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#include <torch/all.h>
#include <ATen/cuda/CUDAContext.h>
#include <c10/cuda/CUDAGuard.h>
#include <cub/cub.cuh>
#include <ATen/ATen.h>
#include <ATen/cuda/Atomic.cuh>
#include "../cuda_compat.h"
#include "../dispatch_utils.h"
#include "core/math.hpp"
#define CEILDIV(x, y) (((x) + (y) - 1) / (y))
namespace vllm {
namespace moe {
namespace batched_moe_align_block_size {
// Note num_threads needs to be 1024 for BlockScan Reduction in the kernel.
static constexpr int32_t num_threads = 1024;
static constexpr int32_t num_blocks = 1;
__global__ void batched_moe_align_block_size_kernel(
int32_t const num_batches, int32_t const max_tokens_per_batch,
int32_t const block_size, int32_t const* __restrict__ batch_num_tokens,
int32_t* __restrict__ sorted_ids, int32_t* __restrict__ block_ids,
int32_t* __restrict__ num_tokens_post_pad) {
// TODO(varun): This is a naive implementation. Could be optimized.
size_t const batch_id = threadIdx.x;
size_t const stride = blockDim.x * gridDim.x;
int32_t const num_blocks_per_batch =
CEILDIV(max_tokens_per_batch, block_size);
int32_t const sorted_ids_size =
num_blocks_per_batch * num_batches * block_size;
int32_t const block_ids_size = sorted_ids_size / block_size;
int32_t const SENTINEL =
num_batches * max_tokens_per_batch; // To denote invalid entries.
// Intialize sorted_ids
for (size_t i = threadIdx.x; i < sorted_ids_size; i += stride) {
sorted_ids[i] = SENTINEL;
}
// Intialize expert_ids with -1
for (size_t i = threadIdx.x; i < block_ids_size; i += stride) {
block_ids[i] = -1;
}
int32_t b_num_tokens = 0;
if (batch_id < num_batches) {
b_num_tokens = batch_num_tokens[batch_id];
}
int32_t const ceil_b_num_tokens =
CEILDIV(b_num_tokens, block_size) * block_size;
// Compute prefix sum over token counts per expert
using BlockScan = cub::BlockScan<int32_t, 1024>;
__shared__ typename BlockScan::TempStorage temp_storage;
int cumsum_val;
BlockScan(temp_storage).ExclusiveSum(ceil_b_num_tokens, cumsum_val);
__syncthreads();
bool const is_last_batch = batch_id == (num_batches - 1);
if (is_last_batch) {
*num_tokens_post_pad = cumsum_val + ceil_b_num_tokens;
}
if (batch_id < num_batches) {
int32_t const batch_offset = batch_id * max_tokens_per_batch;
for (size_t i = 0; i < b_num_tokens; ++i) {
sorted_ids[cumsum_val + i] = batch_offset + i;
}
int32_t const block_start = cumsum_val / block_size;
int32_t const num_blocks = ceil_b_num_tokens / block_size;
for (size_t i = 0; i < num_blocks; ++i) {
block_ids[block_start + i] = batch_id;
}
}
}
} // namespace batched_moe_align_block_size
template <typename scalar_t>
__device__ void _moe_align_block_size(
const scalar_t* __restrict__ topk_ids,
int32_t* __restrict__ sorted_token_ids, int32_t* __restrict__ expert_ids,
int32_t* __restrict__ total_tokens_post_pad,
int32_t* __restrict__ expert_map, int32_t num_experts,
int32_t padded_num_experts, int32_t experts_per_warp, int32_t block_size,
size_t numel, int32_t* __restrict__ cumsum, int32_t max_num_tokens_padded,
int32_t max_num_m_blocks, int32_t model_offset, int32_t inactive_expert_id,
int32_t topk_num, int32_t* token_mask, bool has_expert_map) {
extern __shared__ int32_t shared_counts[];
// Compute input buffer offsets. Typically these will all be 0, except when
// using Multi LoRA.
int sorted_token_ids_offset = max_num_tokens_padded * model_offset;
int expert_ids_offset = max_num_m_blocks * model_offset;
int cumsum_offset = (num_experts + 1) * model_offset;
// Use separate threadblocks to fill sorted_token_ids.
// This is safe since the current kernel does not use sorted_token_ids.
if (blockIdx.x % 2) {
// Initialize sorted_token_ids with numel
for (size_t it = threadIdx.x; it < max_num_tokens_padded;
it += blockDim.x) {
sorted_token_ids[sorted_token_ids_offset + it] = numel;
}
return;
}
const int warp_id = threadIdx.x / WARP_SIZE;
const int my_expert_start = warp_id * experts_per_warp;
for (int i = 0; i < experts_per_warp; ++i) {
if (my_expert_start + i < padded_num_experts) {
shared_counts[warp_id * experts_per_warp + i] = 0;
}
}
__syncthreads();
const size_t tid = threadIdx.x;
const size_t stride = blockDim.x;
for (size_t i = tid; i < numel; i += stride) {
int expert_id = topk_ids[i];
if (expert_id >= num_experts) {
continue;
}
if (has_expert_map) {
expert_id = expert_map[expert_id];
// filter invalid experts
if (expert_id == -1) continue;
}
int warp_idx = expert_id / experts_per_warp;
int expert_offset = expert_id % experts_per_warp;
int mask = token_mask == nullptr ? 1 : token_mask[i / topk_num];
atomicAdd(&shared_counts[warp_idx * experts_per_warp + expert_offset],
mask);
}
__syncthreads();
// Compute prefix sum over token counts per expert
using BlockScan = cub::BlockScan<int32_t, 1024>;
__shared__ typename BlockScan::TempStorage temp_storage;
int expert_count = 0;
int expert_id = threadIdx.x;
if (expert_id < num_experts) {
int warp_idx = expert_id / experts_per_warp;
int expert_offset = expert_id % experts_per_warp;
expert_count = shared_counts[warp_idx * experts_per_warp + expert_offset];
expert_count = CEILDIV(expert_count, block_size) * block_size;
}
int cumsum_val;
BlockScan(temp_storage).ExclusiveSum(expert_count, cumsum_val);
if (expert_id <= num_experts) {
cumsum[cumsum_offset + expert_id] = cumsum_val;
}
if (expert_id == num_experts) {
total_tokens_post_pad[model_offset] = cumsum_val;
}
__syncthreads();
if (threadIdx.x < num_experts) {
for (int i = cumsum[cumsum_offset + threadIdx.x];
i < cumsum[cumsum_offset + threadIdx.x + 1]; i += block_size) {
expert_ids[expert_ids_offset + i / block_size] = threadIdx.x;
}
}
// Fill remaining expert_ids with 0
const size_t fill_start_idx =
cumsum[cumsum_offset + num_experts] / block_size + threadIdx.x;
for (size_t i = fill_start_idx; i < max_num_m_blocks; i += blockDim.x) {
expert_ids[expert_ids_offset + i] = inactive_expert_id;
}
}
template <typename scalar_t, int32_t fill_threads>
__device__ void _moe_align_block_size_small_batch_expert(
const scalar_t* __restrict__ topk_ids,
int32_t* __restrict__ sorted_token_ids, int32_t* __restrict__ expert_ids,
int32_t* __restrict__ total_tokens_post_pad,
int32_t* __restrict__ expert_map, int32_t num_experts, int32_t block_size,
size_t numel, int32_t max_num_tokens_padded, int32_t max_num_m_blocks,
int32_t inactive_expert_id, int32_t model_offset, int32_t topk_num,
int32_t* token_mask, bool has_expert_map) {
// Compute input buffer offsets. Typically these will all be 0, except when
// using Multi LoRA.
int sorted_token_ids_offset = max_num_tokens_padded * model_offset;
int expert_ids_offset = max_num_m_blocks * model_offset;
// Use an additional group of threads to fill sorted_token_ids.
// Since the current kernel will use sorted_token_ids afterward,
// we fill sorted_token_ids within the same threadblock to make
// synchronization easier.
if (threadIdx.x < fill_threads) {
// Initialize sorted_token_ids with numel
for (size_t it = threadIdx.x; it < max_num_tokens_padded;
it += fill_threads) {
sorted_token_ids[sorted_token_ids_offset + it] = numel;
}
// Three __syncthreads() corresponding to the other threads
__syncthreads();
__syncthreads();
__syncthreads();
return;
}
const size_t tid = threadIdx.x - fill_threads;
const size_t stride = blockDim.x - fill_threads;
extern __shared__ int32_t shared_mem[];
int32_t* cumsum = shared_mem;
int32_t* tokens_cnts = (int32_t*)(shared_mem + num_experts + 1);
for (int i = 0; i < num_experts; ++i) {
tokens_cnts[(tid + 1) * num_experts + i] = 0;
}
for (size_t i = tid; i < numel; i += stride) {
int32_t expert_id = topk_ids[i];
if (has_expert_map) {
expert_id = expert_map[expert_id];
// filter invalid expert
if (expert_id == -1) continue;
}
int mask = token_mask == nullptr ? 1 : token_mask[i / topk_num];
tokens_cnts[(tid + 1) * num_experts + expert_id] += mask;
}
__syncthreads();
if (tid < num_experts) {
tokens_cnts[tid] = 0;
for (int i = 1; i <= stride; ++i) {
tokens_cnts[i * num_experts + tid] +=
tokens_cnts[(i - 1) * num_experts + tid];
}
}
__syncthreads();
if (tid == 0) {
cumsum[0] = 0;
for (int i = 1; i <= num_experts; ++i) {
cumsum[i] =
cumsum[i - 1] +
CEILDIV(tokens_cnts[stride * num_experts + i - 1], block_size) *
block_size;
}
total_tokens_post_pad[model_offset] =
static_cast<int32_t>(cumsum[num_experts]);
}
__syncthreads();
if (tid < num_experts) {
for (int i = cumsum[tid]; i < cumsum[tid + 1]; i += block_size) {
expert_ids[expert_ids_offset + i / block_size] = tid;
}
}
// Fill remaining expert_ids with 0
const size_t fill_start_idx = cumsum[num_experts] / block_size + tid;
for (size_t i = fill_start_idx; i < max_num_m_blocks; i += stride) {
expert_ids[expert_ids_offset + i] = inactive_expert_id;
}
for (size_t i = tid; i < numel; i += stride) {
int32_t expert_id = topk_ids[i];
if (has_expert_map) {
expert_id = expert_map[expert_id];
// filter invalid expert
if (expert_id == -1) continue;
}
int32_t rank_post_pad =
tokens_cnts[tid * num_experts + expert_id] + cumsum[expert_id];
if (token_mask == nullptr || token_mask[i / topk_num]) {
sorted_token_ids[sorted_token_ids_offset + rank_post_pad] = i;
++tokens_cnts[tid * num_experts + expert_id];
}
}
}
template <typename scalar_t>
__device__ void _count_and_sort_expert_tokens(
const scalar_t* __restrict__ topk_ids,
int32_t* __restrict__ sorted_token_ids, int32_t* __restrict__ cumsum_buffer,
int32_t* __restrict__ expert_map, size_t numel, int32_t num_experts,
int32_t max_num_tokens_padded, int32_t* __restrict__ token_mask,
int32_t model_offset, int32_t topk_num, bool has_expert_map) {
const size_t tid = blockIdx.y * blockDim.x + threadIdx.x;
const size_t stride = blockDim.x * gridDim.y;
for (size_t i = tid; i < numel; i += stride) {
int32_t expert_id = topk_ids[i];
if (expert_id >= num_experts) {
continue;
}
if (has_expert_map) {
expert_id = expert_map[expert_id];
// filter invalid experts
if (expert_id == -1) continue;
}
if (token_mask == nullptr || token_mask[i / topk_num]) {
int32_t rank_post_pad = atomicAdd(
&cumsum_buffer[(model_offset * (num_experts + 1)) + expert_id], 1);
sorted_token_ids[max_num_tokens_padded * model_offset + rank_post_pad] =
i;
}
}
}
template <typename scalar_t>
__global__ void moe_align_block_size_kernel(
const scalar_t* __restrict__ topk_ids,
int32_t* __restrict__ sorted_token_ids, int32_t* __restrict__ expert_ids,
int32_t* __restrict__ total_tokens_post_pad,
int32_t* __restrict__ expert_map, int32_t num_experts,
int32_t padded_num_experts, int32_t experts_per_warp, int32_t block_size,
size_t numel, int32_t* __restrict__ cumsum, int32_t max_num_tokens_padded,
int32_t topk_num, bool has_expert_map) {
_moe_align_block_size(
topk_ids, sorted_token_ids, expert_ids, total_tokens_post_pad, expert_map,
num_experts, padded_num_experts, experts_per_warp, block_size, numel,
cumsum, max_num_tokens_padded, CEILDIV(max_num_tokens_padded, block_size),
0, 0, topk_num, nullptr, has_expert_map);
}
template <typename scalar_t>
__global__ void count_and_sort_expert_tokens_kernel(
const scalar_t* __restrict__ topk_ids,
int32_t* __restrict__ sorted_token_ids, int32_t* __restrict__ cumsum_buffer,
int32_t* __restrict__ expert_map, size_t numel, int32_t num_experts,
int32_t max_num_tokens_padded, int32_t topk_num, bool has_expert_map) {
_count_and_sort_expert_tokens(
topk_ids, sorted_token_ids, cumsum_buffer, expert_map, numel, num_experts,
max_num_tokens_padded, nullptr, 0, topk_num, has_expert_map);
}
template <typename scalar_t, int TOPK>
__global__ void moe_sum_kernel(
scalar_t* __restrict__ out, // [..., d]
const scalar_t* __restrict__ input, // [..., topk, d]
const int d) {
const int64_t token_idx = blockIdx.x;
for (int64_t idx = threadIdx.x; idx < d; idx += blockDim.x) {
scalar_t x = 0.0;
#pragma unroll
for (int k = 0; k < TOPK; ++k) {
x += VLLM_LDG(&input[token_idx * TOPK * d + k * d + idx]);
}
out[token_idx * d + idx] = x;
}
}
template <typename scalar_t, int32_t fill_threads>
__global__ void moe_align_block_size_small_batch_expert_kernel(
const scalar_t* __restrict__ topk_ids,
int32_t* __restrict__ sorted_token_ids, int32_t* __restrict__ expert_ids,
int32_t* __restrict__ total_tokens_post_pad,
int32_t* __restrict__ expert_map, int32_t num_experts, int32_t block_size,
size_t numel, int32_t max_num_tokens_padded, int32_t topk_num,
bool has_expert_map) {
_moe_align_block_size_small_batch_expert<scalar_t, fill_threads>(
topk_ids, sorted_token_ids, expert_ids, total_tokens_post_pad, expert_map,
num_experts, block_size, numel, max_num_tokens_padded,
CEILDIV(max_num_tokens_padded, block_size), 0, 0, topk_num, nullptr,
has_expert_map);
}
template <typename scalar_t>
__global__ void moe_lora_align_block_size_kernel(
scalar_t* __restrict__ topk_ids, int32_t* __restrict__ token_lora_mapping,
int64_t block_size, int32_t* __restrict__ expert_map, int num_experts,
int max_loras, size_t numel, int max_num_tokens_padded,
int max_num_m_blocks, int32_t* __restrict__ sorted_token_ids,
int32_t* __restrict__ expert_ids, int32_t topk_num,
int32_t* total_tokens_post_pad, int32_t* adapter_enabled,
int32_t* __restrict__ cumsum, int32_t experts_per_warp,
int32_t padded_num_experts, int32_t* lora_ids,
int32_t* __restrict__ token_mask, bool has_expert_map) {
int lora_idx = blockIdx.x / 2;
int lora_id = lora_ids[lora_idx];
if (lora_id == -1 || adapter_enabled[lora_id] == 0) {
return;
}
// Populate the token_mask based on the token-LoRA mapping
int num_tokens = numel / topk_num;
if (threadIdx.x == 0) {
total_tokens_post_pad[lora_id] = 0;
for (int i = 0; i < num_tokens; i++) {
token_mask[(lora_id * num_tokens) + i] =
(int)token_lora_mapping[i] == lora_id;
}
}
__syncthreads();
_moe_align_block_size(
topk_ids, sorted_token_ids, expert_ids, total_tokens_post_pad, expert_map,
num_experts, padded_num_experts, experts_per_warp, block_size, numel,
cumsum, max_num_tokens_padded, max_num_m_blocks, lora_id, -1, topk_num,
&token_mask[(lora_id * num_tokens)], has_expert_map);
}
template <typename scalar_t>
__global__ void lora_count_and_sort_expert_tokens_kernel(
const scalar_t* __restrict__ topk_ids,
int32_t* __restrict__ sorted_token_ids, int32_t* __restrict__ cumsum_buffer,
int32_t* __restrict__ expert_map, size_t numel, int32_t num_experts,
int32_t max_num_tokens_padded, int32_t topk_num, int32_t* token_mask,
int32_t* lora_ids, bool has_expert_map) {
int lora_idx = blockIdx.x;
int lora_id = lora_ids[lora_idx];
if (lora_id == -1) {
return;
}
int num_tokens = numel / topk_num;
_count_and_sort_expert_tokens(
topk_ids, sorted_token_ids, cumsum_buffer, expert_map, numel, num_experts,
max_num_tokens_padded, &token_mask[(lora_id * num_tokens)], lora_id,
topk_num, has_expert_map);
}
template <typename scalar_t, int32_t fill_threads>
__global__ void moe_lora_align_block_size_small_batch_expert_kernel(
scalar_t* __restrict__ topk_ids, int32_t* token_lora_mapping,
int64_t block_size, int32_t* __restrict__ expert_map, int num_experts,
int max_loras, size_t numel, int max_num_tokens_padded,
int max_num_m_blocks, int32_t* __restrict__ sorted_token_ids,
int32_t* __restrict__ expert_ids, int topk_num,
int32_t* total_tokens_post_pad, int32_t* adapter_enabled, int32_t* lora_ids,
int32_t* token_mask, bool has_expert_map) {
int lora_idx = blockIdx.x;
int lora_id = lora_ids[lora_idx];
if (lora_id == -1 || adapter_enabled[lora_id] == 0) {
return;
}
int num_tokens = numel / topk_num;
if (threadIdx.x == 0) {
total_tokens_post_pad[lora_id] = 0;
for (int i = 0; i < num_tokens; i++) {
token_mask[(lora_id * num_tokens) + i] =
(int)token_lora_mapping[i] == lora_id;
}
}
__syncthreads();
_moe_align_block_size_small_batch_expert<scalar_t, fill_threads>(
topk_ids, sorted_token_ids, expert_ids, total_tokens_post_pad, expert_map,
num_experts, block_size, numel, max_num_tokens_padded, max_num_m_blocks,
-1, lora_id, topk_num, &token_mask[(lora_id * num_tokens)],
has_expert_map);
}
} // namespace moe
} // namespace vllm
// taken from
// https://github.com/sgl-project/sglang/blob/8b5f83ed3b7d2a49ad5c5cd5aa61c5d502f47dbc
void moe_align_block_size(torch::Tensor topk_ids, int64_t num_experts,
int64_t block_size, torch::Tensor sorted_token_ids,
torch::Tensor experts_ids,
torch::Tensor num_tokens_post_pad,
std::optional<torch::Tensor> maybe_expert_map) {
const cudaStream_t stream = at::cuda::getCurrentCUDAStream();
int64_t padded_num_experts =
((num_experts + WARP_SIZE - 1) / WARP_SIZE) * WARP_SIZE;
int experts_per_warp = WARP_SIZE;
int threads = 1024;
threads = ((threads + WARP_SIZE - 1) / WARP_SIZE) * WARP_SIZE;
// BlockScan uses 1024 threads and assigns one thread per expert.
TORCH_CHECK(padded_num_experts < 1024,
"padded_num_experts must be less than 1024");
auto options_int =
torch::TensorOptions().dtype(torch::kInt).device(topk_ids.device());
bool has_expert_map = maybe_expert_map.has_value();
torch::Tensor expert_map;
if (has_expert_map) {
expert_map = maybe_expert_map.value();
} else {
expert_map = torch::empty({0}, options_int);
}
VLLM_DISPATCH_INTEGRAL_AND_UNSIGNED_TYPES(
topk_ids.scalar_type(), "moe_align_block_size_kernel", [&] {
// calc needed amount of shared mem for `cumsum` tensors
bool small_batch_expert_mode =
(topk_ids.numel() < 1024) && (num_experts <= 64);
if (small_batch_expert_mode) {
const int32_t threads = max((int32_t)num_experts, WARP_SIZE);
const int32_t shared_mem_size =
((threads + 1) * num_experts + (num_experts + 1)) *
sizeof(int32_t);
// threadIdx.x >= fill_threads: counting experts and aligning
// threadIdx.x < fill_threads: filling sorted_token_ids
constexpr int32_t fill_threads = 256;
auto small_batch_expert_kernel =
vllm::moe::moe_align_block_size_small_batch_expert_kernel<
scalar_t, fill_threads>;
small_batch_expert_kernel<<<1, fill_threads + threads,
shared_mem_size, stream>>>(
topk_ids.data_ptr<scalar_t>(),
sorted_token_ids.data_ptr<int32_t>(),
experts_ids.data_ptr<int32_t>(),
num_tokens_post_pad.data_ptr<int32_t>(),
expert_map.data_ptr<int32_t>(), num_experts, block_size,
topk_ids.numel(), sorted_token_ids.size(0), topk_ids.size(1),
has_expert_map);
} else {
torch::Tensor cumsum_buffer =
torch::empty({num_experts + 1}, options_int);
auto align_kernel = vllm::moe::moe_align_block_size_kernel<scalar_t>;
size_t num_warps = CEILDIV(padded_num_experts, experts_per_warp);
size_t shared_mem_size =
num_warps * experts_per_warp * sizeof(int32_t);
// launch two threadblocks
// blockIdx.x == 0: counting experts and aligning
// blockIdx.x == 1: filling sorted_token_ids
align_kernel<<<2, threads, shared_mem_size, stream>>>(
topk_ids.data_ptr<scalar_t>(),
sorted_token_ids.data_ptr<int32_t>(),
experts_ids.data_ptr<int32_t>(),
num_tokens_post_pad.data_ptr<int32_t>(),
expert_map.data_ptr<int32_t>(), num_experts, padded_num_experts,
experts_per_warp, block_size, topk_ids.numel(),
cumsum_buffer.data_ptr<int32_t>(), sorted_token_ids.size(0),
topk_ids.size(1), has_expert_map);
const int block_threads = std::min(256, (int)threads);
const int num_blocks =
(topk_ids.numel() + block_threads - 1) / block_threads;
const int max_blocks = 65535;
const int actual_blocks = std::min(num_blocks, max_blocks);
dim3 gridDims(1, actual_blocks);
auto sort_kernel =
vllm::moe::count_and_sort_expert_tokens_kernel<scalar_t>;
sort_kernel<<<gridDims, block_threads, 0, stream>>>(
topk_ids.data_ptr<scalar_t>(),
sorted_token_ids.data_ptr<int32_t>(),
cumsum_buffer.data_ptr<int32_t>(), expert_map.data_ptr<int32_t>(),
topk_ids.numel(), num_experts, sorted_token_ids.size(0),
topk_ids.size(1), has_expert_map);
}
});
}
void batched_moe_align_block_size(int64_t max_tokens_per_batch,
int64_t block_size,
torch::Tensor const& batch_num_tokens,
torch::Tensor sorted_ids,
torch::Tensor batch_ids,
torch::Tensor num_tokens_post_pad) {
namespace batched_kernel = vllm::moe::batched_moe_align_block_size;
const cudaStream_t stream = at::cuda::getCurrentCUDAStream();
int32_t const B = batch_num_tokens.size(0);
int32_t const num_blocks_per_batch =
round_to_next_multiple_of(max_tokens_per_batch, block_size) / block_size;
int32_t const num_blocks = num_blocks_per_batch * B;
int64_t const sorted_ids_size = num_blocks * block_size;
TORCH_CHECK(sorted_ids.size(0) == sorted_ids_size);
TORCH_CHECK(batch_ids.size(0) == sorted_ids_size / block_size);
TORCH_CHECK(num_tokens_post_pad.size(0) == 1);
TORCH_CHECK(B <= batched_kernel::num_threads);
batched_kernel::batched_moe_align_block_size_kernel<<<
batched_kernel::num_blocks, batched_kernel::num_threads, 0, stream>>>(
B, max_tokens_per_batch, block_size, batch_num_tokens.data_ptr<int32_t>(),
sorted_ids.data_ptr<int32_t>(), batch_ids.data_ptr<int32_t>(),
num_tokens_post_pad.data_ptr<int32_t>());
}
void moe_sum(torch::Tensor& input, // [num_tokens, topk, hidden_size]
torch::Tensor& output) // [num_tokens, hidden_size]
{
const int hidden_size = input.size(-1);
const auto num_tokens = output.numel() / hidden_size;
const int topk = input.size(1);
dim3 grid(num_tokens);
dim3 block(std::min(hidden_size, 1024));
const at::cuda::OptionalCUDAGuard device_guard(device_of(output));
const cudaStream_t stream = at::cuda::getCurrentCUDAStream();
switch (topk) {
case 2:
VLLM_DISPATCH_FLOATING_TYPES(input.scalar_type(), "moe_sum_kernel", [&] {
vllm::moe::moe_sum_kernel<scalar_t, 2><<<grid, block, 0, stream>>>(
output.data_ptr<scalar_t>(), input.data_ptr<scalar_t>(),
hidden_size);
});
break;
case 3:
VLLM_DISPATCH_FLOATING_TYPES(input.scalar_type(), "moe_sum_kernel", [&] {
vllm::moe::moe_sum_kernel<scalar_t, 3><<<grid, block, 0, stream>>>(
output.data_ptr<scalar_t>(), input.data_ptr<scalar_t>(),
hidden_size);
});
break;
case 4:
VLLM_DISPATCH_FLOATING_TYPES(input.scalar_type(), "moe_sum_kernel", [&] {
vllm::moe::moe_sum_kernel<scalar_t, 4><<<grid, block, 0, stream>>>(
output.data_ptr<scalar_t>(), input.data_ptr<scalar_t>(),
hidden_size);
});
break;
default:
at::sum_out(output, input, 1);
break;
}
}
void moe_lora_align_block_size(
torch::Tensor topk_ids, torch::Tensor token_lora_mapping,
int64_t num_experts, int64_t block_size, int64_t max_loras,
int64_t max_num_tokens_padded, int64_t max_num_m_blocks,
torch::Tensor sorted_token_ids, torch::Tensor expert_ids,
torch::Tensor num_tokens_post_pad, torch::Tensor adapter_enabled,
torch::Tensor lora_ids, std::optional<torch::Tensor> maybe_expert_map) {
const int topk_num = topk_ids.size(1);
TORCH_CHECK(block_size > 0, "block_size should be greater than 0. ");
int device_max_shared_mem;
auto dev = topk_ids.get_device();
cudaDeviceGetAttribute(&device_max_shared_mem,
cudaDevAttrMaxSharedMemoryPerBlockOptin, dev);
const cudaStream_t stream = at::cuda::getCurrentCUDAStream();
int64_t padded_num_experts =
((num_experts + WARP_SIZE - 1) / WARP_SIZE) * WARP_SIZE;
// BlockScan uses 1024 threads and assigns one thread per expert.
TORCH_CHECK(padded_num_experts < 1024,
"padded_num_experts must be less than 1024");
auto options_int =
torch::TensorOptions().dtype(torch::kInt).device(topk_ids.device());
torch::Tensor token_mask =
torch::empty({max_loras * topk_ids.size(0)}, options_int);
bool has_expert_map = maybe_expert_map.has_value();
torch::Tensor expert_map;
if (has_expert_map) {
expert_map = maybe_expert_map.value();
} else {
expert_map = torch::empty({0}, options_int);
}
VLLM_DISPATCH_INTEGRAL_TYPES(
topk_ids.scalar_type(), "moe_lora_align_sum_kernel", [&] {
bool small_batch_expert_mode =
(topk_ids.numel() < 1024) && (num_experts <= 64);
if (small_batch_expert_mode) {
const int32_t num_thread = max((int32_t)num_experts, 128);
const int32_t shared_mem =
(num_thread + 1) * num_experts * sizeof(int32_t) +
(num_experts + 1) * sizeof(int32_t);
if (shared_mem > device_max_shared_mem) {
TORCH_CHECK(false, "Shared memory usage exceeds device limit.");
}
// threadIdx.x >= fill_threads: counting experts and aligning
// threadIdx.x < fill_threads: filling sorted_token_ids
constexpr int32_t fill_threads = 256;
dim3 blockDim(num_thread + fill_threads);
auto kernel =
vllm::moe::moe_lora_align_block_size_small_batch_expert_kernel<
scalar_t, fill_threads>;
AT_CUDA_CHECK(VLLM_DevFuncAttribute_SET_MaxDynamicSharedMemorySize(
(void*)kernel, shared_mem));
kernel<<<max_loras, blockDim, shared_mem, stream>>>(
topk_ids.data_ptr<scalar_t>(),
token_lora_mapping.data_ptr<int32_t>(), block_size,
expert_map.data_ptr<int32_t>(), num_experts, max_loras,
topk_ids.numel(), max_num_tokens_padded, max_num_m_blocks,
sorted_token_ids.data_ptr<int32_t>(),
expert_ids.data_ptr<int32_t>(), topk_num,
num_tokens_post_pad.data_ptr<int32_t>(),
adapter_enabled.data_ptr<int32_t>(), lora_ids.data_ptr<int32_t>(),
token_mask.data_ptr<int32_t>(), has_expert_map);
} else {
int num_thread = 1024;
dim3 blockDim(num_thread);
size_t num_warps = CEILDIV(padded_num_experts, WARP_SIZE);
size_t shared_mem_size = num_warps * WARP_SIZE * sizeof(int32_t);
// cumsum buffer
torch::Tensor cumsum =
torch::zeros({max_loras * (num_experts + 1)}, options_int);
auto align_kernel =
vllm::moe::moe_lora_align_block_size_kernel<scalar_t>;
// launch two threadblocks for each lora
// blockIdx.x % 2 == 0: counting experts and aligning
// blockIdx.x % 2 == 1: filling sorted_token_ids
align_kernel<<<max_loras * 2, blockDim, shared_mem_size, stream>>>(
topk_ids.data_ptr<scalar_t>(),
token_lora_mapping.data_ptr<int32_t>(), block_size,
expert_map.data_ptr<int32_t>(), num_experts, max_loras,
topk_ids.numel(), max_num_tokens_padded, max_num_m_blocks,
sorted_token_ids.data_ptr<int32_t>(),
expert_ids.data_ptr<int32_t>(), topk_num,
num_tokens_post_pad.data_ptr<int32_t>(),
adapter_enabled.data_ptr<int32_t>(), cumsum.data_ptr<int32_t>(),
WARP_SIZE, padded_num_experts, lora_ids.data_ptr<int32_t>(),
token_mask.data_ptr<int32_t>(), has_expert_map);
const int block_threads = std::min(256, (int)num_thread);
const int num_blocks =
(topk_ids.numel() + block_threads - 1) / block_threads;
const int max_blocks = 65535;
const int actual_blocks = std::min(num_blocks, max_blocks);
dim3 gridDims(max_loras, actual_blocks);
auto sort_kernel =
vllm::moe::lora_count_and_sort_expert_tokens_kernel<scalar_t>;
sort_kernel<<<gridDims, block_threads, 0, stream>>>(
topk_ids.data_ptr<scalar_t>(),
sorted_token_ids.data_ptr<int32_t>(), cumsum.data_ptr<int32_t>(),
expert_map.data_ptr<int32_t>(), topk_ids.numel(), num_experts,
max_num_tokens_padded, topk_num, token_mask.data_ptr<int32_t>(),
lora_ids.data_ptr<int32_t>(), has_expert_map);
}
});
}