Re: [PATCH 8/8] sched/eevdf: Add min slice check when selecting CPU

[Kayra Cizmeci]

Hi Vincent,

> > > Add a new level for selecting CPU when select_task_rq_fair() fails to find
> > > an idle CPU. This last level will compare the slice to select a CPU where
> > > the task could run 1st.
> > > This helps a waking task to select a CPU where a longer slice runs
> > > instead of one where a task with the same or shorter slice already runs.

> > > +     if (sched_feat(SIS_UTIL) && sd->shared) {
> > > +             /*
> > > +              * Same nr_idle_scan hint as select_idle_cpu(), nr only limits
> > > +              * the scan when not preferring an idle core.
> > > +              */
> > > +             nr = READ_ONCE(sd->shared->nr_idle_scan) + 1;
> > > +             /* overloaded domain is unlikely to have idle cpu/core */
> > > +             if (nr == 1)
> > > +                     return -1;
> > > +     }

Ain't nr_idle_scan shows load of the system? Even the comment at top talks about
idle CPU's, but we're not looking for a idle CPU right now.

I may be getting something wrong, so please correct me so.


Thanks,
Kayra