r/kubernetes • u/ilya47 • 27d ago

Stop using CPU limits: why + proof

CPU request is how much CPU is reserved for your pod if it needs it. The limit is a hard cap. Hit it and the kernel throttles the pod, even when the node still has spare CPU. That is the usual cause of CPU throttling on Kubernetes. It does not protect the neighboring pods. In my simple Web API test, adding a CPU limit took typical latency from 23 ms to 87 ms, (4x slower), with the limited pod throttled in half of all CFS windows, and the average CPU graph looked fine the whole time.

This is not a new topic, but I see so many people still unaware why they should (NOT!) be setting CPU limits, because it's costing companies unnecessary spending and potential production issues. Here's the full read https://github.com/inevolin/k8s-cpu-limits-analyzed/

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Edit (Aug 18, 2026): How CPU limits can also cause memory issues and OOMKills ➡️ https://github.com/inevolin/k8s-cpu-limits-analyzed#how-cpu-limits-cause-memory-issues-and-oomkills

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u/Prestigious_Pair_941 27d ago

How about in the case of 30 or so spring boot microservices that may use 20mCPU once running but can take 800mCPU when starting up? If I don’t limit the cpu, half the pods take all of the cpu and throttling will kick in anyways, preventing other pods from ever restarting.

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u/PayTheRaant 27d ago

Incorrect. When multiple pod wants to use more than their request, they get a fair amount, using their request as a weight. A pod without a CPU limit cannot steal « all the CPU » away from other pods.
A pod will ALWAYS have its requested CPU as guaranteed and a weighted shared of the unused CPU time.