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From: Michal Hocko <mhocko@suse.cz>
To: Simon Jeons <simon.jeons@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	Hedi Berriche <hedi@sgi.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: page_alloc: Avoid marking zones full prematurely after zone_reclaim()
Date: Thu, 21 Mar 2013 09:19:02 +0100	[thread overview]
Message-ID: <20130321081902.GD6094@dhcp22.suse.cz> (raw)
In-Reply-To: <514A7163.5070700@gmail.com>

On Thu 21-03-13 10:33:07, Simon Jeons wrote:
> Hi Mel,
> On 03/21/2013 02:19 AM, Mel Gorman wrote:
> >The following problem was reported against a distribution kernel when
> >zone_reclaim was enabled but the same problem applies to the mainline
> >kernel. The reproduction case was as follows
> >
> >1. Run numactl -m +0 dd if=largefile of=/dev/null
> >    This allocates a large number of clean pages in node 0
> 
> I confuse why this need allocate a large number of clean pages?

It reads from file and puts pages into the page cache. The pages are not
modified so they are clean. Output file is /dev/null so no pages are
written. dd doesn't call fadvise(POSIX_FADV_DONTNEED) on the input file
by default so pages from the file stay in the page cache
-- 
Michal Hocko
SUSE Labs

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  reply	other threads:[~2013-03-21  8:19 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-03-20 18:19 Mel Gorman
2013-03-20 18:45 ` Michal Hocko
2013-03-21  2:32 ` Wanpeng Li
2013-03-21  2:32 ` Wanpeng Li
2013-03-21  2:33 ` Simon Jeons
2013-03-21  8:19   ` Michal Hocko [this message]
2013-03-21  8:32     ` Simon Jeons
2013-03-21  8:44       ` Michal Hocko
2013-03-21  8:59       ` Wanpeng Li
2013-03-21  8:59       ` Wanpeng Li
2013-04-05  6:31     ` Simon Jeons
2013-04-07  6:37       ` Simon Jeons
2013-04-09 10:05       ` Simon Jeons
2013-04-09 10:14         ` Michal Hocko
2013-04-09 10:20           ` Simon Jeons
2013-04-10  5:15           ` Ric Mason

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