---
id: pr-flash-attention-1072
repo: Dao-AILab/flash-attention
pr: 1072
title: Add var-seq-len to FA3 fp16 / bf16 fwd
author: ipiszy
date: '2024-07-23'
url: https://github.com/Dao-AILab/flash-attention/pull/1072
source_category: upstream-code
architectures:
- sm90
tags:
- FA3
- arch_pipeline
- attention_kv
- benchmark_test
- fp8
techniques:
- async-copy
- epilogue-fusion
- pipeline-stages
hardware_features:
- fp8
- hopper
- tma
kernel_types:
- attention
- runtime
languages:
- cuda-cpp
captured_at: '2026-05-16'
status: merged
merge_sha: dfe1a59e4bcd932248f1e72b7c39cb2f80c18d2e
inclusion_reason: Mine shape sets, tolerance rules, warmup logic, and profile commands before mutating code.
changed_paths:
- hopper/benchmark_attn.py
- hopper/epilogue_fwd_sm90_tma.hpp
- hopper/flash.h
- hopper/flash_api.cpp
- hopper/flash_attn_interface.py
- hopper/flash_fwd_kernel.h
- hopper/flash_fwd_launch_template.h
- hopper/mainloop_fwd_sm90_tma_gmma_ws.hpp
- hopper/seq_len.h
- hopper/static_switch.h
- hopper/test_flash_attn.py
- hopper/utils.h
- tests/test_util.py
artifact_dir: evidence/pull-bundles/flash-attention/gh-1072
head_ref_oid: 01c7093e255559484731ca007755c026f053d68a
---
# Add var-seq-len to FA3 fp16 / bf16 fwd

- Repository: `Dao-AILab/flash-attention`
- PR: [1072](https://github.com/Dao-AILab/flash-attention/pull/1072)
- Decision: `Mine shape sets, tolerance rules, warmup logic, and profile commands before mutating code.`
- Reason: Mine shape sets, tolerance rules, warmup logic, and profile commands before mutating code.

## Changed Paths

- `hopper/benchmark_attn.py`
- `hopper/epilogue_fwd_sm90_tma.hpp`
- `hopper/flash.h`
- `hopper/flash_api.cpp`
- `hopper/flash_attn_interface.py`
- `hopper/flash_fwd_kernel.h`
- `hopper/flash_fwd_launch_template.h`
- `hopper/mainloop_fwd_sm90_tma_gmma_ws.hpp`
- `hopper/seq_len.h`
- `hopper/static_switch.h`
- `hopper/test_flash_attn.py`
- `hopper/utils.h`
- `tests/test_util.py`

## Evidence Bundle

`evidence/pull-bundles/flash-attention/gh-1072`
