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

From: Peter Zijlstra
Date: Fri Jul 20 2018 - 07:31:49 EST


On Thu, Jul 19, 2018 at 09:52:01AM -0700, Tejun Heo wrote:
> Hello,
>
> On Thu, Jul 19, 2018 at 11:52:46AM -0400, Waiman Long wrote:
> > BTW, the way the partition is currently implemented right now is that a
> > child cannot be a partition root unless its parent is a partition root
> > itself. That is to avoid turning on partition to affect ancestors
> > further up the hierarchy than just the parent. So in the case of a
> > container, it cannot allocate sub-partitions underneath it unless it is
> > a partition itself. Will that solve your concern?
>
> Hmm... so a given ancestor must be able to both
>
> 1. control which cpus are moved into a partition in all of its
> subtree.

By virtue of the partition file being owned by the parent, this is
already achived, no?

> 2. take away any given cpu from ist subtree.

I really hate this obsession of yours and doubly so for partitions. But
why would this currently not be allowed?