Kevin Traynor

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Debugging Memory Issues with Open vSwitch DPDK

Debugging Memory Issues with Open vSwitch DPDK

Introduction

This article is about debugging out-of-memory issues with Open vSwitch with the Data Plane Development Kit (OvS-DPDK). It explains the situations in which you can run out of memory when using OvS-DPDK and it shows the log entries that are produced in those circumstances. It also shows some other log entries and commands for further debugging.

When you finish reading this article, you will be able to identify that you have an out-of-memory issue and you’ll know how to fix it. Spoiler: Usually having some more memory on the relevant NUMA node works. It is based on OvS 2.9.

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Open vSwitch-DPDK: How Much Hugepage Memory?

Open vSwitch-DPDK: How Much Hugepage Memory?

Introduction

In order to maximize performance of the Open vSwitch DPDK datapath, it pre-allocates hugepage memory. As a user you are responsible for telling Open vSwitch how much hugepage memory to pre-allocate. The question of exactly what value to use often arises. The answer is, it depends.

There is no simple answer as it depends on things like the MTU size of the ports, the MTU differences between ports, and whether those ports are on the same NUMA node. Just to complicate things a bit more, there are multiple overheads, and alignment and rounding need to be accounted for at various places in OVS-DPDK. Everything clear? OK, you can stop reading then!
However, if not, read on.

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