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Date:   Wed, 27 Jan 2021 13:21:21 +0000
From:   Mel Gorman <mgorman@techsingularity.net>
To:     Vincent Guittot <vincent.guittot@linaro.org>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Li Aubrey <aubrey.li@linux.intel.com>,
        Qais Yousef <qais.yousef@arm.com>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 4/4] sched/fair: Merge select_idle_core/cpu()
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On Wed, Jan 27, 2021 at 02:07:50PM +0100, Vincent Guittot wrote:
> > @@ -6162,18 +6162,16 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t
> >
> >         for_each_cpu_wrap(cpu, cpus, target) {
> >                 if (smt) {
> > -                       i = select_idle_core(p, cpu, cpus, &idle_cpu);
> > -                       if ((unsigned int)i < nr_cpumask_bits)
> > -                               return i;
> > +                       idle_cpu = select_idle_core(p, cpu, cpus, &idle_cpu);
> 
> but how do you differentiate idle core (return value) and an idle cpu
> in the core set in &idle_cpu
> 
> You will return as soon as a cpu is idle and before testing all cores
> 

Bah, I'm sorry, I was context switching between multiple tasks and failed
to engage brain. I'll apply your hunk and resend. I don't think this
merits retesting as the saving of avoiding the intermeriate is marginal.

-- 
Mel Gorman
SUSE Labs