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From: Rik van Riel <riel@surriel.com>
To: Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
	Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Mel Gorman <mgorman@techsingularity.net>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 04/19] sched/numa: Set preferred_node based on best_cpu
Date: Mon, 04 Jun 2018 10:37:30 -0400	[thread overview]
Message-ID: <1528123050.7898.99.camel@surriel.com> (raw)
In-Reply-To: <20180604125939.GB38574@linux.vnet.ibm.com>

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On Mon, 2018-06-04 at 05:59 -0700, Srikar Dronamraju wrote:
> * Peter Zijlstra <peterz@infradead.org> [2018-06-04 14:23:36]:
> 
> > OK, the above matches the description, but I'm puzzled by the
> > remainder:
> > 
> > > 
> > > -		if (ng->active_nodes > 1 &&
> > > numa_is_active_node(env.dst_nid, ng))
> > > -			sched_setnuma(p, env.dst_nid);
> > > +		if (nid != p->numa_preferred_nid)
> > > +			sched_setnuma(p, nid);
> > >  	}
> > 
> > That seems to entirely loose the active_node thing, or are you
> > saying
> > best_cpu already includes that? (Changelog could use a little help
> > there
> > I suppose)
> 
> I think checking for active_nodes before calling sched_setnuma was a
> mistake.
> 
> Before this change, we may be retaining numa_preferred_nid to be the
> source node while we select another node with better numa affinity to
> run on. 

Sometimes workloads are so large they get spread
around to multiple NUMA nodes.

In that case, you do NOT want all the tasks of
that workload (numa group) to try squeezing onto
the same load, only to have the load balancer
randomly move tasks off of that node again later.

How do you keep that from happening?

-- 
All Rights Reversed.

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  parent reply	other threads:[~2018-06-04 14:37 UTC|newest]

Thread overview: 66+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-04 10:00 [PATCH 00/19] Fixes for sched/numa_balancing Srikar Dronamraju
2018-06-04 10:00 ` [PATCH 01/19] sched/numa: Remove redundant field Srikar Dronamraju
2018-06-04 14:53   ` Rik van Riel
2018-06-05  8:41   ` Mel Gorman
2018-06-04 10:00 ` [PATCH 02/19] sched/numa: Evaluate move once per node Srikar Dronamraju
2018-06-04 14:51   ` Rik van Riel
2018-06-04 15:45     ` Srikar Dronamraju
2018-06-04 10:00 ` [PATCH 03/19] sched/numa: Simplify load_too_imbalanced Srikar Dronamraju
2018-06-04 14:57   ` Rik van Riel
2018-06-05  8:46   ` Mel Gorman
2018-06-04 10:00 ` [PATCH 04/19] sched/numa: Set preferred_node based on best_cpu Srikar Dronamraju
2018-06-04 12:18   ` Peter Zijlstra
2018-06-04 12:53     ` Srikar Dronamraju
2018-06-04 12:23   ` Peter Zijlstra
2018-06-04 12:59     ` Srikar Dronamraju
2018-06-04 13:39       ` Peter Zijlstra
2018-06-04 13:48         ` Srikar Dronamraju
2018-06-04 14:37       ` Rik van Riel [this message]
2018-06-04 15:56         ` Srikar Dronamraju
2018-06-04 10:00 ` [PATCH 05/19] sched/numa: Use task faults only if numa_group is not yet setup Srikar Dronamraju
2018-06-04 12:24   ` Peter Zijlstra
2018-06-04 13:09     ` Srikar Dronamraju
2018-06-04 10:00 ` [PATCH 06/19] sched/debug: Reverse the order of printing faults Srikar Dronamraju
2018-06-04 16:28   ` Rik van Riel
2018-06-05  8:50   ` Mel Gorman
2018-06-04 10:00 ` [PATCH 07/19] sched/numa: Skip nodes that are at hoplimit Srikar Dronamraju
2018-06-04 16:27   ` Rik van Riel
2018-06-05  8:50   ` Mel Gorman
2018-06-04 10:00 ` [PATCH 08/19] sched/numa: Remove unused task_capacity from numa_stats Srikar Dronamraju
2018-06-04 16:28   ` Rik van Riel
2018-06-05  8:57   ` Mel Gorman
2018-06-04 10:00 ` [PATCH 09/19] sched/numa: Modify migrate_swap to accept additional params Srikar Dronamraju
2018-06-04 17:00   ` Rik van Riel
2018-06-05  8:58   ` Mel Gorman
2018-06-04 10:00 ` [PATCH 10/19] sched/numa: Stop multiple tasks from moving to the cpu at the same time Srikar Dronamraju
2018-06-04 17:57   ` Rik van Riel
2018-06-05  9:51   ` Mel Gorman
2018-06-04 10:00 ` [PATCH 11/19] sched/numa: Restrict migrating in parallel to the same node Srikar Dronamraju
2018-06-04 17:59   ` Rik van Riel
2018-06-05  9:53   ` Mel Gorman
2018-06-06 12:58     ` Srikar Dronamraju
2018-06-04 10:00 ` [PATCH 12/19] sched:numa Remove numa_has_capacity Srikar Dronamraju
2018-06-04 18:07   ` Rik van Riel
2018-06-04 10:00 ` [PATCH 13/19] mm/migrate: Use xchg instead of spinlock Srikar Dronamraju
2018-06-04 18:22   ` Rik van Riel
2018-06-04 19:28   ` Peter Zijlstra
2018-06-05  7:24     ` Srikar Dronamraju
2018-06-05  8:16       ` Peter Zijlstra
2018-06-04 10:00 ` [PATCH 14/19] sched/numa: Updation of scan period need not be in lock Srikar Dronamraju
2018-06-04 18:24   ` Rik van Riel
2018-06-04 10:00 ` [PATCH 15/19] sched/numa: Use group_weights to identify if migration degrades locality Srikar Dronamraju
2018-06-04 18:56   ` Rik van Riel
2018-06-04 10:00 ` [PATCH 16/19] sched/numa: Detect if node actively handling migration Srikar Dronamraju
2018-06-04 20:05   ` Rik van Riel
2018-06-05  3:56     ` Srikar Dronamraju
2018-06-05 13:07       ` Rik van Riel
2018-06-06 12:55         ` Srikar Dronamraju
2018-06-06 13:55           ` Rik van Riel
2018-06-06 15:32             ` Srikar Dronamraju
2018-06-06 17:06               ` Rik van Riel
2018-06-04 10:00 ` [PATCH 17/19] sched/numa: Pass destination cpu as a parameter to migrate_task_rq Srikar Dronamraju
2018-06-04 10:00 ` [PATCH 18/19] sched/numa: Reset scan rate whenever task moves across nodes Srikar Dronamraju
2018-06-04 20:08   ` Rik van Riel
2018-06-05  9:58   ` Mel Gorman
2018-06-06 13:47     ` Srikar Dronamraju
2018-06-04 10:00 ` [PATCH 19/19] sched/numa: Move task_placement closer to numa_migrate_preferred Srikar Dronamraju

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