---
id: pr-flash-attention-2100
repo: Dao-AILab/flash-attention
pr: 2100
title: '[Cute,Fwd] improved block sparsity'
author: reubenconducts
date: '2026-01-05'
url: https://github.com/Dao-AILab/flash-attention/pull/2100
source_category: upstream-code
architectures:
- sm100
tags:
- cutlass
techniques: []
hardware_features: []
kernel_types:
- attention
languages:
- cute-dsl
captured_at: '2026-05-16'
status: merged
merge_sha: f98d345f0ac56b36f79a1b135d70b3c53e862b66
inclusion_reason: Search-matched CUDA kernel optimization PR; materialize diff/source before synthesis.
changed_paths:
- flash_attn/cute/block_sparse_utils.py
- flash_attn/cute/block_sparsity.py
- flash_attn/cute/compute_block_sparsity.py
- flash_attn/cute/cute_dsl_utils.py
- flash_attn/cute/flash_bwd_sm100.py
- flash_attn/cute/flash_bwd_sm90.py
- flash_attn/cute/flash_fwd.py
- flash_attn/cute/flash_fwd_sm100.py
- flash_attn/cute/interface.py
- flash_attn/cute/mask.py
- tests/cute/benchmark_block_sparsity.py
- tests/cute/benchmark_mask_mod.py
- tests/cute/mask_mod_definitions.py
- tests/cute/test_block_sparsity.py
- tests/cute/test_mask_mod.py
artifact_dir: evidence/pull-bundles/flash-attention/gh-2100
head_ref_oid: c0677da93284949f4a0cabb1efe1dc2c0a6c40fd
---
# [Cute,Fwd] improved block sparsity

- Repository: `Dao-AILab/flash-attention`
- PR: [2100](https://github.com/Dao-AILab/flash-attention/pull/2100)
- 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/block_sparse_utils.py`
- `flash_attn/cute/block_sparsity.py`
- `flash_attn/cute/compute_block_sparsity.py`
- `flash_attn/cute/cute_dsl_utils.py`
- `flash_attn/cute/flash_bwd_sm100.py`
- `flash_attn/cute/flash_bwd_sm90.py`
- `flash_attn/cute/flash_fwd.py`
- `flash_attn/cute/flash_fwd_sm100.py`
- `flash_attn/cute/interface.py`
- `flash_attn/cute/mask.py`
- `tests/cute/benchmark_block_sparsity.py`
- `tests/cute/benchmark_mask_mod.py`
- `tests/cute/mask_mod_definitions.py`
- `tests/cute/test_block_sparsity.py`
- `tests/cute/test_mask_mod.py`

## Evidence Bundle

`evidence/pull-bundles/flash-attention/gh-2100`
