[systemd-devel] cgroupsv2 and realtime processes

[Michał Zegan]

W dniu 6.06.2022 o 17:14, Michal Koutný pisze:
> On Mon, Jun 06, 2022 at 04:54:03PM +0200, Michał Zegan <webczat at outlook.com> wrote:
>> this note pointed to in the readme is quite cgroups v1 specific, I believe
>> what it describes was true in v1, and v2 does not have any capability to
>> control realtime processes in non root cgroups if I read correctly.
> Yes. And it extends to v2 too where there are even no userspace knobs to
> configure the RT attributes.
>
> Therefore it works [1] with CONFIG_RT_GROUP_SCHED unset since RT
> processes remain in the root cgroup (it's an implementation detail you
> won't see from /proc/$pid/cgroup, where is still the regular process
> membership).
> To prevent confusion -- this applies only to processes (threads) with RT
> policy and from all other perspectives these processes (threads) are
> still in the listed cgroup.
>
> Does that explain what you were after?
yes. forgot about that option to be fair. I assume if it would be on it 
would break any and all realtime usage...?
>
> Michal
>
> [1] Unless your goal is to control per-cgroup RT attributes. I
> understood you just wanted to be able to place RT processes into
> non-root cgroups.
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