linux-kernel - Re: [PATCH 08/16] sched: Reschedule task on preferred NUMA node once selected

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Message-ID: <20130712102819.GH2355@suse.de>
Date:	Fri, 12 Jul 2013 11:28:19 +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 08/16] sched: Reschedule task on preferred NUMA node once
 selected

On Fri, Jul 12, 2013 at 12:14:08PM +0200, Peter Zijlstra wrote:
> On Thu, Jul 11, 2013 at 03:09:14PM +0100, Mel Gorman wrote:
> > That might be necessary when the machine is overloaded. As a
> > starting point the following should retry the migrate a number of times
> > until success. The retry is checked on every fault but should not fire
> > more than once every 100ms.
>  
> Yeah, something like that might work. But getting a working imbalance bound is
> important. The current very weak direct migration is the only thing that keeps
> the system from massively skewing load.

I've corrected a flaw in that proposed patch, pulled in the check for
dst load vs src load, and am adding another patch that will fallback to
less preferred nodes if task_numa_find_cpu fails to find a suitable CPU.

-- 
Mel Gorman
SUSE Labs
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