linux-kernel - Re: [PATCH v3 06/13] mm, compaction: periodically drop lock and restore IRQs in scanners

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Message-ID: <53A99CCD.5050103@suse.cz>
Date:	Tue, 24 Jun 2014 17:44:13 +0200
From:	Vlastimil Babka <vbabka@...e.cz>
To:	Naoya Horiguchi <n-horiguchi@...jp.nec.com>
CC:	linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
	David Rientjes <rientjes@...gle.com>,
	Minchan Kim <minchan@...nel.org>, Mel Gorman <mgorman@...e.de>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Michal Nazarewicz <mina86@...a86.com>,
	Christoph Lameter <cl@...ux.com>,
	Rik van Riel <riel@...hat.com>,
	Zhang Yanfei <zhangyanfei@...fujitsu.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 06/13] mm, compaction: periodically drop lock and restore
 IRQs in scanners

On 06/24/2014 05:39 PM, Naoya Horiguchi wrote:
> On Fri, Jun 20, 2014 at 05:49:36PM +0200, Vlastimil Babka wrote:
>> Compaction scanners regularly check for lock contention and need_resched()
>> through the compact_checklock_irqsave() function. However, if there is no
>> contention, the lock can be held and IRQ disabled for potentially long time.
>>
>> This has been addressed by commit b2eef8c0d0 ("mm: compaction: minimise the
>> time IRQs are disabled while isolating pages for migration") for the migration
>> scanner. However, the refactoring done by commit 748446bb6b ("mm: compaction:
>> acquire the zone->lru_lock as late as possible") has changed the conditions so
>
> You seem to refer to the incorrect commit, maybe you meant commit 2a1402aa044b?

Oops, right. Thanks!

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