Re: [PATCH 1/2] cgroup/cpuset: Keep current cpus list if cpus affinity was explicitly set

[Waiman Long <longman@redhat.com>]

On 7/28/22 11:23, Michal Koutný wrote:
> On Thu, Jul 28, 2022 at 10:59:01AM -0400, Waiman Long <longman@redhat.com> wrote:
>> Cgroup v1 doesn't have this problem.
> v1 analogy would be:
>
> 	echo 2-3 >$dst/cpuset.cpus
> 	# job runs in $dst
> 	# one task T in $dst sets affinity just to one cpu
> 	# I rethink my config, I want to allow $dst more space
> 	echo 2-5 >$dst/cpuset.cpus
>
> Most tasks in $dst happily utilize the new cpus but it breaks affinity
> for T -- this must have been broken since ever.
>
> (Or I'd argue that per-thread affinities are just recommendations, if I
> have a task for nohz CPU, I should enforce its placement with cpuset
> from the beginning.)

I should have clarified that what I meant is systemd on a cgroup v1 
environment doesn't cause this cpu list reset to happen. It doesn't mean 
that cgroup v1 has no similar problem. Sorry for the confusion.

Cheers,
Longman