Re: [RESEND PATCH] sched/fair: consider RT/IRQ pressure in select_idle_sibling

[Dietmar Eggemann]

On 02/09/2018 01:53 PM, Peter Zijlstra wrote:
> On Mon, Jan 29, 2018 at 03:27:09PM -0800, Rohit Jain wrote:

[...]

> > @@ -6173,8 +6183,15 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t
> >   			return -1;
> >   		if (!cpumask_test_cpu(cpu, &p->cpus_allowed))
> >   			continue;
> > +		if (idle_cpu(cpu)) {
> > +			if (full_capacity(cpu)) {
> > +				best_cpu = cpu;
> > +				break;
> > +			} else if (capacity_of(cpu) > best_cap) {
> > +				best_cap = capacity_of(cpu);
> > +				best_cpu = cpu;
> > +			}
> > +		}
>
> No need for the else. And you'll note you're once again inconsistent
> with your previous self.
>
> But here I worry about big.little a wee bit. I think we're allowed big
> and little cores on the same L3 these days, and you can't directly
> compare capacity between them.
>
> Morten / Dietmar, any comments?

Yes, for DynamIQ (big.little successor) systems, those cpus can have 
different capacity_orig_of() values already.