---
id: pr-flash-attention-2186
repo: Dao-AILab/flash-attention
pr: 2186
title: '[Cute,Fwd,Sm100] support irregular qhead / kvhead ratios'
author: timmy-feng
date: '2026-03-20'
url: https://github.com/Dao-AILab/flash-attention/pull/2186
source_category: upstream-code
architectures:
- sm100
- sm90
tags:
- arch_pipeline
- attention_kv
- benchmark_test
- compiler_runtime
- cute dsl
- sm100
- sm90
- varlen
techniques:
- pipeline-stages
hardware_features:
- blackwell
- hopper
kernel_types:
- attention
- compiler
- runtime
- sampling
languages:
- cute-dsl
captured_at: '2026-05-16'
status: merged
merge_sha: 32500812bdc39017f3be0e5f162551d3aec619ef
inclusion_reason: Preserve page/KV/layout and plan-run contracts; profile memory traffic separately from math utilization.
changed_paths:
- flash_attn/cute/flash_fwd_sm100.py
- flash_attn/cute/interface.py
- tests/cute/test_flash_attn_fast.py
artifact_dir: evidence/pull-bundles/flash-attention/gh-2186
head_ref_oid: 074ec36f4ce0d722cb7d1d3a596746873d235d07
---
# [Cute,Fwd,Sm100] support irregular qhead / kvhead ratios

- Repository: `Dao-AILab/flash-attention`
- PR: [2186](https://github.com/Dao-AILab/flash-attention/pull/2186)
- 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_fwd_sm100.py`
- `flash_attn/cute/interface.py`
- `tests/cute/test_flash_attn_fast.py`

## Evidence Bundle

`evidence/pull-bundles/flash-attention/gh-2186`
