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[Bugfix][Kernel] fix potential cuda graph broken for merge_attn_states kernel (#16693)

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Signed-off-by: DefTruth <qiustudent_r@163.com>
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DefTruth 2025-04-16 18:31:39 +08:00 committed by GitHub
parent facbe2a114
commit e82ee40de3
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1 changed files with 15 additions and 10 deletions
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25
csrc/attention/merge_attn_states.cu
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@ -107,13 +107,14 @@ __global__ void merge_attn_states_kernel(
#define LAUNCH_MERGE_ATTN_STATES(scalar_t, NUM_THREADS) \
{ \
vllm::merge_attn_states_kernel<scalar_t, NUM_THREADS><<<grid, block>>>( \
reinterpret_cast<scalar_t*>(output.data_ptr()), output_lse_ptr, \
reinterpret_cast<scalar_t*>(prefix_output.data_ptr()), \
reinterpret_cast<float*>(prefix_lse.data_ptr()), \
reinterpret_cast<scalar_t*>(suffix_output.data_ptr()), \
reinterpret_cast<float*>(suffix_lse.data_ptr()), num_tokens, \
num_heads, head_size); \
vllm::merge_attn_states_kernel<scalar_t, NUM_THREADS> \
<<<grid, block, 0, stream>>>( \
reinterpret_cast<scalar_t*>(output.data_ptr()), output_lse_ptr, \
reinterpret_cast<scalar_t*>(prefix_output.data_ptr()), \
reinterpret_cast<float*>(prefix_lse.data_ptr()), \
reinterpret_cast<scalar_t*>(suffix_output.data_ptr()), \
reinterpret_cast<float*>(suffix_lse.data_ptr()), num_tokens, \
num_heads, head_size); \
}
/*@brief Merges the attention states from prefix and suffix
@ -122,10 +123,10 @@ __global__ void merge_attn_states_kernel(
* @param output [n,h,d] The output tensor to store the merged attention states.
* @param output_lse [h,d] Optional tensor to store the log-sum-exp values.
* @param prefix_output [n,h,d] The prefix attention states.
* @param prefix_lse [h,d] The log-sum-exp values for the prefix attention
* @param prefix_lse [h,n] The log-sum-exp values for the prefix attention
* states.
* @param suffix_output [n,h,d] The suffix attention states.
* @param suffix_lse [h,d] The log-sum-exp values for the suffix attention
* @param suffix_lse [h,n] The log-sum-exp values for the suffix attention
* states.
*/
template <typename scalar_t>
@ -146,13 +147,17 @@ void merge_attn_states_launcher(torch::Tensor& output,
if (output_lse.has_value()) {
output_lse_ptr = output_lse.value().data_ptr<float>();
}
// process one pack elements per thread. float -> 4, half/bf16 -> 8
// Process one pack elements per thread. for float, the
// pack_size is 4 for half/bf16, the pack_size is 8.
const uint threads_per_head = head_size / pack_size;
const uint total_threads = num_tokens * num_heads * threads_per_head;
dim3 block(NUM_THREADS);
dim3 grid((total_threads + NUM_THREADS - 1) / NUM_THREADS);
const c10::cuda::OptionalCUDAGuard device_guard(prefix_output.device());
auto stream = at::cuda::getCurrentCUDAStream();
LAUNCH_MERGE_ATTN_STATES(scalar_t, NUM_THREADS);
}