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A comment on For the Love of God, Stop Using CPU Limits on Kubernetes. Parent comment

Re:For the Love of God, Stop Using CPU Limits on Kubernetes by lantry on Tuesday July 02, 2024 @10:02AM (#40856795)
The post recommends setting both request and limit for memory. It's only for CPU that it says to use a request and not a limit. It's my understanding that the kernel only kills processes when it's out of memory. In the docs you linked, there doesn't seem to be an "eviction signal" for CPU.
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Re:For the Love of God, Stop Using CPU Limits on Kubernetes by potoftea on Tuesday July 02, 2024 @10:08AM (#40856855)
This doens't match what I've read.

IF you don't set limit to cpu & memory, your pod QoS will be burstable and from kernel/cgroup perspective this process can be killed - it's only question of oom_score_adj.

OOMScore from linux - https://www.freedesktop.org/software/systemd/man/latest/syst...

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Re:For the Love of God, Stop Using CPU Limits on Kubernetes by cassianoleal on Tuesday July 02, 2024 @12:59PM (#40858463)
OOM means "Out Of Memory". The post is about CPU.

> Everything in this post is about CPU and not memory.

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Re:For the Love of God, Stop Using CPU Limits on Kubernetes by potoftea on Tuesday July 02, 2024 @04:57PM (#40860334)
I am aware of it, are you aware that Kubernetes assigned Burstable Qos if you don't defined CPU requests and limits?

What I'm trying to say that while try to avoid one pitfall you fall right into an other - in short there are good reasons to use cpu limits.

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Re:For the Love of God, Stop Using CPU Limits on Kubernetes by cassianoleal on Tuesday July 02, 2024 @07:14PM (#40861353)
That's not what you're saying though. You're also putting requests/limits for CPU and memory in the same class, which they're not.

Lack of CPU will never cause a pod to be killed. Evicted, yes. Killed, no.

Lack of memory can cause a pod to be OOM killed. That's an entirely different failure mode.

Eviction should always be expected by your pods. They should be able to handle eviction gracefully. On the other hand, there is nothing you can do to handle an OOM kill gracefully.

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