linux-kernel - Re: [PATCH -v2 12/17] sched,rt: Use cpumask_any*

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Date:   Tue, 6 Oct 2020 16:20:04 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Juri Lelli <juri.lelli@...hat.com>
Cc:     tglx@...utronix.de, mingo@...nel.org, linux-kernel@...r.kernel.org,
        bigeasy@...utronix.de, qais.yousef@....com, swood@...hat.com,
        valentin.schneider@....com, vincent.guittot@...aro.org,
        dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
        mgorman@...e.de, bristot@...hat.com, vincent.donnefort@....com,
        tj@...nel.org
Subject: Re: [PATCH -v2 12/17] sched,rt: Use cpumask_any*_distribute()

On Tue, Oct 06, 2020 at 04:09:26PM +0200, Juri Lelli wrote:

> > --- a/kernel/sched/deadline.c
> > +++ b/kernel/sched/deadline.c
> > @@ -2001,7 +2001,7 @@ static int find_later_rq(struct task_str
> >  	if (this_cpu != -1)
> >  		return this_cpu;
> >  
> > -	cpu = cpumask_any(later_mask);
> > +	cpu = cpumask_any_distribute(later_mask);
> >  	if (cpu < nr_cpu_ids)
> >  		return cpu;
> 
> Think we can use cpumask_any_and_distribute() with later_mask for
> deadline as well inside the for_each_domain loop as you do for rt below.

Ah, indeed.. I missed it because it is cpumask_first, instead of
cpumask_any as with rt.

I folded the below.

---
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1981,8 +1981,8 @@ static int find_later_rq(struct task_str
 				return this_cpu;
 			}
 
-			best_cpu = cpumask_first_and(later_mask,
-							sched_domain_span(sd));
+			best_cpu = cpumask_any_and_distribute(later_mask,
+							      sched_domain_span(sd));
 			/*
 			 * Last chance: if a CPU being in both later_mask
 			 * and current sd span is valid, that becomes our