AllReduce Stalls Are Network Stalls. Most Tools See Neither.
The article discusses the relationship between AllReduce stalls and network performance in multi-node GPU training jobs. It highlights how slow AllReduce operations can often be attributed to TCP retransmits rather than GPU performance issues. The author provides insights into monitoring tools and methods for diagnosing these stalls effectively.
- ▪A slow AllReduce operation can indicate network stalls rather than GPU issues.
- ▪The article explains how to use monitoring tools to identify the causes of slow AllReduce calls.
- ▪TCP retransmits are a common reason for slow AllReduce performance in multi-node setups.
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Record
| Original publisher | DEV.to (Top) |
| Canonical URL | https://dev.to/ingero/allreduce-stalls-are-network-stalls-most-tools-see-neither-4a40 |
| Publication time | Wed, 27 May 2026 13:30:00 +0000 |
| Retrieval time | 2026-05-27T13:38:00.837Z |
| Last seen | 2026-05-27T13:38:00.837Z |
| Headline source | Publisher (no WeSearch rewrite) |
| Excerpt source | publisher body |
| Excerpt method | First ~120 words (~800 chars) of extracted publisher body, fair-use limited. |
| Summary | WeSearch · cerebras-chat (WeSearch summarizer) |
| Summary source text | contentText |
| Citation coverage | Summary is a WeSearch-generated derivative; primary citation is the original publisher URL. |
| Cluster | 4xoiYSuvQ82c |
| Cluster logic | Grouped by semantic title/content similarity across sources within a rolling window. Same-publisher template collisions are excluded from coverage comparison. |
| Ranking reason | Story pages are not engagement-ranked. Hub feeds use recency, with optional source-diversified chronological ordering (cap consecutive stories per source). No personalized ranking. |
| Publisher visit | Yes — open original |
| Substitutes article? | No — link-out required for full text |
Rights status (four layers)
WeSearch handling by dimension
| Indexing | May the item be indexed (stored, ranked, made findable)? | Allowed |
| Snippet | May a short excerpt of the publisher's text be shown? | Allowed |
| AI summary | May WeSearch generate its own short summary of the article? | Limited |
| Retrieval / RAG | May the content be exposed for third-party retrieval-augmented generation? | Not asserted |
| Model training | May the content be used to train AI models? | Not asserted |
| Commercial reuse | May the content be reused commercially? | Not permitted |
Basis: Derived from the published RSS/Atom feed. Contact: [email protected]. Reviewed: 2026-07-24.
Opening excerpt (first ~120 words) tap to expand
try { if(localStorage) { let currentUser = localStorage.getItem('current_user'); if (currentUser) { currentUser = JSON.parse(currentUser); if (currentUser.id === 3853036) { document.getElementById('article-show-container').classList.add('current-user-is-article-author'); } } } } catch (e) { console.error(e); } Ingero Team Posted on May 27 • Originally published at ingero.io AllReduce Stalls Are Network Stalls. Most Tools See Neither. #machinelearning #devops #performance #networking A slow AllReduce on rank 5 lines up against TCP retransmits on rank 5’s NIC, four ms before the collective completes.
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Excerpt limited to ~120 words for fair-use compliance. The full article is at DEV.to (Top).
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