---
id: pr-flash-attention-2495
repo: Dao-AILab/flash-attention
pr: 2495
title: 'benchmarks/tune_ex2_emu: hd256 sweep support and clock lock/unlock'
author: Johnsonms
date: '2026-05-01'
url: https://github.com/Dao-AILab/flash-attention/pull/2495
source_category: upstream-code
architectures:
- sm100
tags:
- attention kernel
- benchmark kernel
- cuda kernel
- sm100
techniques: []
hardware_features:
- blackwell
kernel_types:
- attention
languages:
- cuda-cpp
captured_at: '2026-05-16'
status: merged
merge_sha: a7f6fbd9cf51101786157bb087438b584e0f6747
inclusion_reason: Search-matched CUDA kernel optimization PR; materialize diff/source before synthesis.
changed_paths:
- benchmarks/tune_ex2_emu.py
artifact_dir: evidence/pull-bundles/flash-attention/gh-2495
head_ref_oid: 8b7acfa0b3c883b3782b98fcd46a37c8198f1028
---
# benchmarks/tune_ex2_emu: hd256 sweep support and clock lock/unlock

- Repository: `Dao-AILab/flash-attention`
- PR: [2495](https://github.com/Dao-AILab/flash-attention/pull/2495)
- Decision: `Search-matched CUDA kernel optimization PR; materialize diff/source before synthesis.`
- Reason: Search-matched CUDA kernel optimization PR; materialize diff/source before synthesis.

## Changed Paths

- `benchmarks/tune_ex2_emu.py`

## Evidence Bundle

`evidence/pull-bundles/flash-attention/gh-2495`
