Assign pods to specific CPU slices

[HaoxinSEU]

Hi community,

I'm installing K3s on my machine. On my machine, I split my CPU into two slices system.slice and user.slice with different cores. In general system.slice is the OS, while user.slice is running applications.

I find out that K3s is running on the cores belonging to system.slice, and pods are also assigned to that slice. So I'm wondering how can I assign pods to user.slice?

I'm using Red Hat, and install K3s by running

curl -sfL https://get.k3s.io | sh -s - --write-kubeconfig-mode 644

Any hints would be much appreciated!

Best regards,
Haoxin

[brandond]

As per the systemd docs:

By default, service and scope units are placed in system.slice, virtual machines and containers registered with systemd-machined are found in machine.slice, and user sessions handled by systemd-logind in user.slice.

Pods are not user sessions and don't belong in user.slice. If you put them there I suspect it might get confused?

[HaoxinSEU]

Thank you so much for your explanation, Brad!

So is there a way to not run pods on CPU cores in system.slice? For example, should I create a new slice for that?

Thanks again,
Haoxin

[brandond]

You might look at the --cgroup-root and --cgroups-per-qos kubelet args?

[HaoxinSEU]

Thanks Brad!

I will try this out :)