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Date: Thu, 14 May 2009 19:42:48 -0400
From: Rik van Riel <riel@redhat.com>
Organization: Red Hat, Inc
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To: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
CC: Christoph Lameter <cl@linux-foundation.org>,
       Wu Fengguang <fengguang.wu@intel.com>,
       Andrew Morton <akpm@linux-foundation.org>,
       "hannes@cmpxchg.org" <hannes@cmpxchg.org>,
       "peterz@infradead.org" <peterz@infradead.org>,
       "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
       "tytso@mit.edu" <tytso@mit.edu>,
       "linux-mm@kvack.org" <linux-mm@kvack.org>,
       "elladan@eskimo.com" <elladan@eskimo.com>,
       "npiggin@suse.de" <npiggin@suse.de>,
       "minchan.kim@gmail.com" <minchan.kim@gmail.com>
Subject: Re: [PATCH -mm] vmscan: protect a fraction of file backed mapped
 pages from reclaim
References: <20090513084306.5874.A69D9226@jp.fujitsu.com> <alpine.DEB.1.10.0905141612100.15881@qirst.com> <20090515082312.F5B6.A69D9226@jp.fujitsu.com>
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KOSAKI Motohiro wrote:

>>>> The percentage of file backed pages protected is set via
>>>> /proc/sys/vm/file_mapped_ratio. This defaults to 20%.
>>> Why do you think typical mapped ratio is less than 20% on desktop machine?
>> Observation of the typical mapped size of Firefox under KDE.
> 
> My point is, desktop people have very various mapped ratio.
> Do you oppose this?

I suspect that the mapped ratio could be much higher
on my system.  I have only 2GB of RAM dedicated to my
dom0 (which is also my desktop) and the amount of page
cache often goes down to about 150MB.

At the moment nr_mapped is 26400 and the amount of
memory taken up by buffer and page cache together is
a little over 300MB.  That's close to 50%.

-- 
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