linux-kernel - Re: [PATCH 0/3] mm: fixup changers of per cpu pageset's ->high and ->batch

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Message-ID: <51631C70.8010404@linux.vnet.ibm.com>
Date:	Mon, 08 Apr 2013 12:37:20 -0700
From:	Cody P Schafer <cody@...ux.vnet.ibm.com>
To:	Simon Jeons <simon.jeons@...il.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Mel Gorman <mgorman@...e.de>, Linux MM <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/3] mm: fixup changers of per cpu pageset's ->high and
 ->batch

On 04/06/2013 06:32 PM, Simon Jeons wrote:
> Hi Cody,
> On 04/06/2013 04:33 AM, Cody P Schafer wrote:
>> In one case while modifying the ->high and ->batch fields of per cpu
>> pagesets
>> we're unneededly using stop_machine() (patches 1 & 2), and in another
>> we don't have any
>> syncronization at all (patch 3).
>
> Do you mean stop_machine() is used for syncronization between each
> online cpu?
>

I mean that it looks like synchronization between cpus is unneeded 
because of how per cpu pagesets are used, so stop_machine() (which does 
provide syncro between all cpus) is unnecessarily "strong".

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