Re: [PATCH v11 7/9] cpuset: Expose cpus.effective and mems.effective on cgroup v2 root

From: Tejun Heo
Date: Tue Jul 03 2018 - 11:58:33 EST

Hello, Waiman.

On Tue, Jul 03, 2018 at 08:41:31AM +0800, Waiman Long wrote:
> > So, effective changing when enabling partition on a child feels wrong
> > to me. It's supposed to contain what's actually allowed to the cgroup
> > from its parent and that shouldn't change regardless of how those
> > resources are used. It's still given to the cgroup from its parent.
> Another way to work around this issue is to expose the reserved_cpus in
> the parent for holding CPUs that can taken by a chid partition. That
> will require adding one more cpuset file for those cgroups that are
> partition roots.

Yeah, that should work.

> I don't mind restricting that to the first level children for now. That
> does restrict where we can put the container root if we want a separate
> partition for a container. Let's hear if others have any objection about
> that.

As currently implemented, partioning locks away the cpus which should
be a system level decision, not container level, so it makes sense to
me that it is only available to system root.