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From: Peter Zijlstra <peterz@infradead.org>
To: Mel Gorman <mgorman@techsingularity.net>
Cc: Vincent Guittot <vincent.guittot@linaro.org>,
	Ingo Molnar <mingo@kernel.org>, Phil Auld <pauld@redhat.com>,
	Valentin Schneider <valentin.schneider@arm.com>,
	Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
	Quentin Perret <quentin.perret@arm.com>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Morten Rasmussen <Morten.Rasmussen@arm.com>,
	Hillf Danton <hdanton@sina.com>, Parth Shah <parth@linux.ibm.com>,
	Rik van Riel <riel@surriel.com>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] sched, fair: Allow a small degree of load imbalance between SD_NUMA domains v2
Date: Tue, 7 Jan 2020 13:29:43 +0100	[thread overview]
Message-ID: <20200107122943.GW2827@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200107114211.GH3466@techsingularity.net>

On Tue, Jan 07, 2020 at 11:42:11AM +0000, Mel Gorman wrote:
> On Tue, Jan 07, 2020 at 12:22:55PM +0100, Peter Zijlstra wrote:

> > > +		/* Consider allowing a small imbalance between NUMA groups */
> > > +		if (env->sd->flags & SD_NUMA) {
> > > +			struct sched_domain *child = env->sd->child;
> > 
> > This assumes sd-child exists, which should be true for NUMA domains I
> > suppose.
> > 
> 
> I would be stunned if it was not. What sort of NUMA domain would not have
> child domains? Does a memory-only NUMA node with no CPUs even generate
> a scheduler domain? If it does, then I guess the check is necessary.

I think it's fine, it was just my paranoia triggering. At the very least
we'll have the single CPU domain there.

  reply	other threads:[~2020-01-07 12:30 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-20  8:42 [PATCH] sched, fair: Allow a small degree of load imbalance between SD_NUMA domains v2 Mel Gorman
2019-12-20 12:40 ` Valentin Schneider
2019-12-20 14:22   ` Mel Gorman
2019-12-20 15:32     ` Valentin Schneider
2019-12-21 11:25   ` Mel Gorman
2019-12-22 12:00 ` Srikar Dronamraju
2019-12-23 13:31 ` Vincent Guittot
2019-12-23 13:41   ` Vincent Guittot
2020-01-03 14:31   ` Mel Gorman
2020-01-06 13:55     ` Vincent Guittot
2020-01-06 14:52       ` Mel Gorman
2020-01-07  8:38         ` Vincent Guittot
2020-01-07  9:56           ` Mel Gorman
2020-01-07 11:17             ` Vincent Guittot
2020-01-07 11:56               ` Mel Gorman
2020-01-07 16:00                 ` Vincent Guittot
2020-01-07 20:24                   ` Mel Gorman
2020-01-08  8:25                     ` Vincent Guittot
2020-01-08  8:49                       ` Mel Gorman
2020-01-08 13:18                     ` Peter Zijlstra
2020-01-08 14:03                       ` Mel Gorman
2020-01-08 16:46                         ` Vincent Guittot
2020-01-08 18:03                           ` Mel Gorman
2020-01-07 11:22             ` Peter Zijlstra
2020-01-07 11:42               ` Mel Gorman
2020-01-07 12:29                 ` Peter Zijlstra [this message]
2020-01-07 12:28               ` Peter Zijlstra
2020-01-07 19:26             ` Phil Auld

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