---
id: pr-vllm-16173
repo: vllm-project/vllm
pr: 16173
title: '[Kernel] support merge_attn_states CUDA kernel, 3x speedup'
author: DefTruth
date: '2025-04-11'
url: https://github.com/vllm-project/vllm/pull/16173
source_category: upstream-code
architectures:
- sm100
tags:
- attention
- mla
techniques: []
hardware_features: []
kernel_types:
- attention
- mla
languages:
- cuda-cpp
captured_at: '2026-04-27'
status: merged
merge_sha: e9528f6dc614879952aa871fae8df296adcfc559
inclusion_reason: kernel file changes
changed_paths:
- CMakeLists.txt
- csrc/attention/merge_attn_states.cu
- csrc/ops.h
- csrc/torch_bindings.cpp
- tests/kernels/test_merge_attn_states.py
- vllm/_custom_ops.py
- vllm/attention/backends/mla/common.py
- vllm/attention/ops/merge_attn_states.py
- vllm/v1/attention/backends/flash_attn.py
- vllm/v1/attention/backends/mla/common.py
head_ref_oid: c9c10bab1b39a7c7d4791f93e6d819e18228ac48
artifact_dir: evidence/pull-bundles/vllm/gh-16173
---
# [Kernel] support merge_attn_states CUDA kernel, 3x speedup

- Repository: `vllm-project/vllm`
- PR: [16173](https://github.com/vllm-project/vllm/pull/16173)
- Decision: `kernel file changes`
- Reason: kernel file changes

## Changed Paths

- `CMakeLists.txt`
- `csrc/attention/merge_attn_states.cu`
- `csrc/ops.h`
- `csrc/torch_bindings.cpp`
- `tests/kernels/test_merge_attn_states.py`
- `vllm/_custom_ops.py`
- `vllm/attention/backends/mla/common.py`
- `vllm/attention/ops/merge_attn_states.py`
- `vllm/v1/attention/backends/flash_attn.py`
- `vllm/v1/attention/backends/mla/common.py`

## Evidence Bundle

`evidence/pull-bundles/vllm/gh-16173`
