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Targeted Megaflow Revalidation in Open vSwitch#

Open vSwitch and OVN 2026 Fall Conference digest Program Core pick 2–4 November 2026

Abstract

Gaetan Rivet, NVIDIA

  • Why: A diagnosed failure mode that "has limited the scale of our Open vSwitch deployments at NVIDIA": after any configuration change, OVS revalidates all megaflows, which can cascade into flow eviction, revalidator destabilization, and megaflow population collapse — a rebuild under overload. A concrete fix with a dependency-tracking design, implemented and running in production fork form.
  • What: Targeted megaflow revalidation, implemented in the OVS-DOCA fork: record the reason for each revalidation and extend xcache to track each megaflow's dependencies, so only affected megaflows are retranslated after a change. Also gives controller authors a way to structure OpenFlow pipelines so configuration changes have bounded impact; upstreaming is intended. (from abstract only)
  • How: Dependency tracking including indirect and negative dependencies (watched ports, missing groups), with AI-assisted testing used to cover the dependency matrix; part of a wider revalidation-stabilization effort that continues with a better flow-capacity control law.
  • Where applicable: Any large OVS deployment, but the current implementation lives in NVIDIA's OVS-DOCA fork (DOCA/BlueField context) — upstream availability is the thing to watch. The dependency-completeness caveat is the main risk.