linux-kernel - Re: [PATCH 13/13] sched: Account for the number of preferred tasks running on a node when selecting a preferred node

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Message-ID: <20130704144018.GS1875@suse.de>
Date:	Thu, 4 Jul 2013 15:40:18 +0100
From:	Mel Gorman <mgorman@...e.de>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
	Ingo Molnar <mingo@...nel.org>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Linux-MM <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 13/13] sched: Account for the number of preferred tasks
 running on a node when selecting a preferred node

On Thu, Jul 04, 2013 at 04:06:13PM +0200, Peter Zijlstra wrote:
> On Thu, Jul 04, 2013 at 02:54:15PM +0100, Mel Gorman wrote:
> > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> > index 9247345..387f28d 100644
> > --- a/kernel/sched/fair.c
> > +++ b/kernel/sched/fair.c
> > @@ -863,9 +863,13 @@ find_idlest_cpu_node(int this_cpu, int nid)
> >  		load = weighted_cpuload(i);
> >  
> >  		if (load < min_load) {
> > -			/* Do not preempt a task running on a preferred node */
> > +			/*
> > +			 * Do not preempt a task running on a preferred node or
> > +			 * tasks are are pinned to their current CPU
> > +			 */
> >  			struct task_struct *p = cpu_rq(i)->curr;
> > -			if (p->numa_preferred_nid != nid) {
> > +			if (p->numa_preferred_nid != nid &&
> > +			    cpumask_weight(tsk_cpus_allowed(p)) > 1) {
> 
> We have p->nr_cpus_allowed for that.
> 

/me slaps self

That's a bit easier to calculate, thanks.

-- 
Mel Gorman
SUSE Labs
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