---
id: pr-vllm-41189
repo: vllm-project/vllm
pr: 41189
title: '[Bugfix] Fix persistent_topk cooperative deadlock at TopK=1024'
author: zyongye
date: '2026-04-30'
url: https://github.com/vllm-project/vllm/pull/41189
source_category: upstream-code
architectures:
- sm100
tags:
- csrc kernel
- moe_routing
- scheduler_autotune
- topk
techniques:
- autotuning
- persistent-kernels
- tile-scheduling
hardware_features: []
kernel_types:
- moe
- scheduler
languages:
- cuda-cpp
captured_at: '2026-05-16'
status: merged
merge_sha: a749a33d8d05acdd3ab346bd3f0c6b5c9c80474f
inclusion_reason: Separate routing, permutation, top-k, and expert GEMM costs; keep tail-token and expert-layout tests attached to the idea.
changed_paths:
- csrc/topk.cu
artifact_dir: evidence/pull-bundles/vllm/gh-41189
head_ref_oid: 61c3a50f43b527d49b66ff744f497def489f8e6d
---
# [Bugfix] Fix persistent_topk cooperative deadlock at TopK=1024

- Repository: `vllm-project/vllm`
- PR: [41189](https://github.com/vllm-project/vllm/pull/41189)
- Decision: `Separate routing, permutation, top-k, and expert GEMM costs; keep tail-token and expert-layout tests attached to the idea.`
- Reason: Separate routing, permutation, top-k, and expert GEMM costs; keep tail-token and expert-layout tests attached to the idea.

## Changed Paths

- `csrc/topk.cu`

## Evidence Bundle

`evidence/pull-bundles/vllm/gh-41189`
