linux-kernel - Re: mapped pagecache pages vs unmapped pages

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Message-ID: <4F7E9854.1020904@gmail.com>
Date:	Fri, 06 Apr 2012 15:16:36 +0800
From:	"gnehzuil.lzheng@...il.com" <gnehzuil.lzheng@...il.com>
To:	Alexey Ivanov <rbtz@...dex-team.ru>
CC:	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: mapped pagecache pages vs unmapped pages

On 04/06/2012 08:29 AM, Alexey Ivanov wrote:

> In progress of migration from FreeBSD to Linux and we found some strange behavior: periodically running tasks (like rsync/p2p deployment) evict mapped pages from memory.
> 
> From my little research I've found following lkml thread:
> https://lkml.org/lkml/2008/6/11/278
> And more precisely this commit: https://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=4f98a2fee8acdb4ac84545df98cccecfd130f8db
> which along with splitting LRU into "anon" and "file" removed support of reclaim_mapped.
> 
> Is there a knob to prioritize mapped memory over unmapped (without modifying all apps to use O_DIRECT/fadvise/madvise or mlocking our data in memory) or at least some way to change proportion of Active(file)/Inactive(file)?
> 


Hi Alexey,

Cc to linux-mm mailing list.

I have met the similar problem and I have sent a mail to discuss it.
Maybe it can help you
(http://marc.info/?l=linux-mm&m=132947026019538&w=2).

Now Konstantin has sent a patch set to try to expand vm_flags from 32
bit to 64 bit.  Then we can add the new flag into vm_flags and
prioritize mmaped pages in madvise(2).

Regards,
Zheng
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