Re: [PATCH 1/2] sched/rt: Fix RT utilization tracking during policy change

[Vincent Guittot]

On Mon, 21 Jun 2021 at 11:03, Vincent Donnefort
<vincent.donnefort@xxxxxxx> wrote:
>
> [...]
>
> > >         /*
> > > -        * If we are already running, then there's nothing
> > > -        * that needs to be done. But if we are not running
> > > -        * we may need to preempt the current running task.
> > > -        * If that current running task is also an RT task
> > > +        * If we are not running we may need to preempt the current
> > > +        * running task. If that current running task is also an RT task
> > >          * then see if we can move to another run queue.
> > >          */
> > >         if (task_on_rq_queued(p) && rq->curr != p) {
> > > @@ -2355,6 +2353,13 @@ static void switched_to_rt(struct rq *rq, struct task_struct *p)
> > >                 if (p->prio < rq->curr->prio && cpu_online(cpu_of(rq)))
> > >                         resched_curr(rq);
> > >         }
> > > +
> > > +       /*
> > > +        * If we are running, update the avg_rt tracking, as the running time
> > > +        * will now on be accounted into the latter.
> > > +        */
> > > +       if (task_current(rq, p))
> >
> > task_current(rq,p) equals the "rq->curr != p" above. Having 2
> > different ways to get the same value in the function is a bit
> > confusing.
> >
> > And call it once
> >
> > Otherwise, the fix looks good to me
>
> I can change it to something like:
>
> if (task_current(rq, p)) {
>     update_rt_rq_load_avg()
>     return;
> }
>
> if (task_on_rq_queued(p) {
>         ...
>         if (p->prio ...)
>                 resched_curr(rq);
> }
>
> ?

yes, looks good to me


>
> >
> > > +               update_rt_rq_load_avg(rq_clock_pelt(rq), rq, 0);
> > >  }
> > >
> > >  /*
> > > --
> > > 2.7.4
> > >