Re: [tip: sched/hrtick] sched/eevdf: Fix HRTICK duration

[Shrikanth Hegde]

On 3/20/26 9:08 PM, Peter Zijlstra wrote:
> On Fri, Mar 20, 2026 at 08:29:11PM +0530, Shrikanth Hegde wrote:
>
> > > +	/*
> > > +	 * Correct for instantaneous load of other classes.
> > > +	 */
> > > +	util += cpu_util_irq(rq);
> > > +	if (util && util < 1024) {
> > > +		scale *= 1024;
> > > +		scale /= (1024 - util);
> > > +	}
> >
> > Comments/Changelog says other classes.
> >
> > Then why not consider cpu_util_dl, cpu_util_rq too?
> > Is there a reason why these are not taken into calculations?
>
> Damn, forgot to fix that comment.
>
> So yes, it used to correct for those, but then I realized that the
> hrtick is strictly for current. So running RT/DL tasks means current is
> different.
>
> The only thing that can actually interrupt current and soak time are
> interrupts.
>
> Does that make sense?

Yes. That helps.