---
id: pr-flash-attention-1945
repo: Dao-AILab/flash-attention
pr: 1945
title: Blackwell FlashAttention-BWD (v1.0)
author: tzadouri
date: '2025-10-19'
url: https://github.com/Dao-AILab/flash-attention/pull/1945
source_category: upstream-code
architectures:
- sm100
tags:
- arch_pipeline
- attention_kv
- blackwell
- head_dim
techniques:
- pipeline-stages
hardware_features:
- blackwell
kernel_types:
- attention
- runtime
languages:
- cuda-cpp
- cute-dsl
captured_at: '2026-05-16'
status: merged
merge_sha: 83eb8d6c082a6bd9c6c986a890eddae7ad2a257e
inclusion_reason: Preserve page/KV/layout and plan-run contracts; profile memory traffic separately from math utilization.
changed_paths:
- flash_attn/cute/flash_bwd_postprocess.py
- flash_attn/cute/flash_bwd_sm100.py
- flash_attn/cute/mask.py
- flash_attn/cute/named_barrier.py
artifact_dir: evidence/pull-bundles/flash-attention/gh-1945
head_ref_oid: 2c560d93ef53e0e897ad52c3068dbf20f789ceb4
---
# Blackwell FlashAttention-BWD (v1.0)

- Repository: `Dao-AILab/flash-attention`
- PR: [1945](https://github.com/Dao-AILab/flash-attention/pull/1945)
- Decision: `Preserve page/KV/layout and plan-run contracts; profile memory traffic separately from math utilization.`
- Reason: Preserve page/KV/layout and plan-run contracts; profile memory traffic separately from math utilization.

## Changed Paths

- `flash_attn/cute/flash_bwd_postprocess.py`
- `flash_attn/cute/flash_bwd_sm100.py`
- `flash_attn/cute/mask.py`
- `flash_attn/cute/named_barrier.py`

## Evidence Bundle

`evidence/pull-bundles/flash-attention/gh-1945`
