Skip to content

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

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Apr 16, 2025
Merged

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

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
25 changes: 15 additions & 10 deletions csrc/attention/merge_attn_states.cu
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand All @@ -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>
Expand All @@ -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);
}

Expand Down