Re: [PATCH v3 08/20] sched/fair: load balance only among preferred CPUs

[Shrikanth Hegde]

On 6/9/26 4:52 PM, Peter Zijlstra wrote:
> On Thu, Jun 04, 2026 at 06:37:48PM +0530, Shrikanth Hegde wrote:
> > Hi Prateek.
> >
> > On 6/4/26 11:39 AM, K Prateek Nayak wrote:
> > > Hello Shrikanth,
> > >
> > > ... just moving set_cpu_preferred() into sched_cpu_activate() and
> > > sched_cpu_deactivate() instead of doing it at set_cpu_online().
> >
> > Ah ok. Will move it there. I think this should be ok.
>
> Right, such that preferred is a strict subset of active.
>
>    preferred ⊆ active ⊆ online ⊆ present ⊆ possible

Ok. This can be met i think.

In addition to this and in the dec/incr of preferred CPUs if i plug 
active mask instead of online, and disable make it same as active the 
above construct can be met i think. I will give that a try.

That might make it better w.r.t to CPU hotplug too. less races.