---
id: pr-flashinfer-2125
repo: flashinfer-ai/flashinfer
pr: 2125
title: 'feat: support variable sequence length in decode kernel of trtllm-gen attention'
author: yaoyaoding
date: '2025-12-20'
url: https://github.com/flashinfer-ai/flashinfer/pull/2125
source_category: upstream-code
architectures:
- sm100
tags:
- attention
- decode
- flash-attention
- mla
techniques: []
hardware_features: []
kernel_types:
- attention
- decode
- flash-attention
- mla
languages:
- cuda-cpp
captured_at: '2026-04-27'
status: merged
merge_sha: 4aa46124831233fdd561aedb332d0d71fba227c6
inclusion_reason: kernel file changes
changed_paths:
- csrc/trtllm_fmha_kernel_launcher.cu
- flashinfer/decode.py
- flashinfer/mla.py
- tests/attention/test_trtllm_gen_attention.py
head_ref_oid: 8e48f09e0b060182dc799b55db207bc31217146c
artifact_dir: evidence/pull-bundles/flashinfer/gh-2125
---
# feat: support variable sequence length in decode kernel of trtllm-gen attention

- Repository: `flashinfer-ai/flashinfer`
- PR: [2125](https://github.com/flashinfer-ai/flashinfer/pull/2125)
- Decision: `kernel file changes`
- Reason: kernel file changes

## Changed Paths

- `csrc/trtllm_fmha_kernel_launcher.cu`
- `flashinfer/decode.py`
- `flashinfer/mla.py`
- `tests/attention/test_trtllm_gen_attention.py`

## Evidence Bundle

`evidence/pull-bundles/flashinfer/gh-2125`
