linux-kernel - Re: [PATCH 12/12] sched/numa: Stop an exhastive search if a reasonable swap candidate or idle CPU is found

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Message-ID: <20200214120307.GH3466@techsingularity.net>
Date:   Fri, 14 Feb 2020 12:03:07 +0000
From:   Mel Gorman <mgorman@...hsingularity.net>
To:     Hillf Danton <hdanton@...a.com>
Cc:     Vincent Guittot <vincent.guittot@...aro.org>,
        Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>,
        Valentin Schneider <valentin.schneider@....com>,
        Phil Auld <pauld@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 12/12] sched/numa: Stop an exhastive search if a
 reasonable swap candidate or idle CPU is found

On Fri, Feb 14, 2020 at 07:47:46PM +0800, Hillf Danton wrote:
> > +
> > +	/*
> > +	 * If a move to idle is allowed because there is capacity or load
> > +	 * balance improves then stop the search. While a better swap
> > +	 * candidate may exist, a search is not free.
> > +	 */
> > +	if (maymove && !cur && env->best_cpu >= 0 && idle_cpu(env->best_cpu))
> > +		stopsearch = true;
> > +
> > +	/*
> > +	 * If a swap candidate must be identified and the current best task
> > +	 * moves its preferred node then stop the search.
> > +	 */
> > +	if (!maymove && env->best_task &&
> > +	    env->best_task->numa_preferred_nid == env->src_nid) {
> > +		return true;
> 
> Take another look at the lock left behind please.
> 

/me slaps self

Thanks

-- 
Mel Gorman
SUSE Labs