---
id: pr-vllm-20759
repo: vllm-project/vllm
pr: 20759
title: '[PERF] PyTorch Symmetric Memory All-Reduce'
author: ilmarkov
date: '2025-08-22'
url: https://github.com/vllm-project/vllm/pull/20759
source_category: upstream-code
architectures:
- sm100
tags: []
techniques: []
hardware_features: []
kernel_types: []
languages: []
captured_at: '2026-05-16'
status: merged
merge_sha: 0313cf854d87a41c84efb69e89a79cd7b5897593
inclusion_reason: include
changed_paths:
- docs/design/multiprocessing.md
- tests/distributed/test_symm_mem_allreduce.py
- tools/check_pickle_imports.py
- vllm/distributed/device_communicators/all_reduce_utils.py
- vllm/distributed/device_communicators/cuda_communicator.py
- vllm/distributed/device_communicators/custom_all_reduce.py
- vllm/distributed/device_communicators/symm_mem.py
- vllm/envs.py
artifact_dir: evidence/pull-bundles/vllm/gh-20759
head_ref_oid: eacc031fd7d45bf061e8924c153e65ac459190cb
---
# [PERF] PyTorch Symmetric Memory All-Reduce

- Repository: `vllm-project/vllm`
- PR: [20759](https://github.com/vllm-project/vllm/pull/20759)
- Decision: `include`
- Reason: include

## Changed Paths

- `docs/design/multiprocessing.md`
- `tests/distributed/test_symm_mem_allreduce.py`
- `tools/check_pickle_imports.py`
- `vllm/distributed/device_communicators/all_reduce_utils.py`
- `vllm/distributed/device_communicators/cuda_communicator.py`
- `vllm/distributed/device_communicators/custom_all_reduce.py`
- `vllm/distributed/device_communicators/symm_mem.py`
- `vllm/envs.py`

## Evidence Bundle

`evidence/pull-bundles/vllm/gh-20759`
