---
id: pr-flash-attention-2543
repo: Dao-AILab/flash-attention
pr: 2543
title: '[CuTe,Bwd,Sm100] don''t disable 2cta due to cuda 12 in bwd'
author: reubenconducts
date: '2026-05-06'
url: https://github.com/Dao-AILab/flash-attention/pull/2543
source_category: upstream-code
architectures:
- sm100
tags:
- attention
- cute
- sm100
techniques: []
hardware_features:
- blackwell
kernel_types:
- attention
languages:
- cuda-cpp
- cute-dsl
captured_at: '2026-05-16'
status: merged
merge_sha: c263382a091cc0545afd2169a873328243f792c8
inclusion_reason: Search-matched CUDA kernel optimization PR; materialize diff/source before synthesis.
changed_paths:
- flash_attn/cute/interface.py
- flash_attn/cute/utils.py
artifact_dir: evidence/pull-bundles/flash-attention/gh-2543
head_ref_oid: 08f49124c16ef484045b9c048cf82ce465b0e2a5
---
# [CuTe,Bwd,Sm100] don't disable 2cta due to cuda 12 in bwd

- Repository: `Dao-AILab/flash-attention`
- PR: [2543](https://github.com/Dao-AILab/flash-attention/pull/2543)
- 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

- `flash_attn/cute/interface.py`
- `flash_attn/cute/utils.py`

## Evidence Bundle

`evidence/pull-bundles/flash-attention/gh-2543`
