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From: Rik van Riel <riel@redhat.com>
To: Minchan Kim <minchan@kernel.org>
Cc: Alexey Ivanov <rbtz@yandex-team.ru>,
	"gnehzuil.lzheng@gmail.com" <gnehzuil.lzheng@gmail.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	yinghan@google.com
Subject: Re: mapped pagecache pages vs unmapped pages
Date: Mon, 09 Apr 2012 20:49:20 -0400	[thread overview]
Message-ID: <4F838390.1080909@redhat.com> (raw)
In-Reply-To: <4F837F6E.3010508@kernel.org>

On 04/09/2012 08:31 PM, Minchan Kim wrote:
> 2012-04-10 i??i ? 8:50, Alexey Ivanov i?' e,?:
>
>> Did you consider making this ratio tunable, at least manually(i.e. via sysctl)?
>> I suppose we are not the only ones with almost-whole-ram-mmaped workload.
>
> Personally, I think it's not good approach.
> It depends on kernel's internal implemenatation which would be changed
> in future as we chagend it at 2.6.28.

I also believe that a tunable for this is not going to be
a very workable approach, for the simple reason that changing
the value does not make a predictable change in the effectiveness
of working set detection or protection.

> In my opinion, kernel just should do best effort to keep active working
> set except some critical pages which are code pages.

Johannes has some experimental code to measure refaults, and
calculate their distance in a multi-zone, multi-cgroup environment.

That would allow us to predictably place things in the working set
as required.

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  reply	other threads:[~2012-04-10  0:49 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <37371333672160@webcorp7.yandex-team.ru>
2012-04-06  7:16 ` mapped pagecache pages vs unmapped pages gnehzuil.lzheng
2012-04-09 17:11   ` Alexey Ivanov
2012-04-09 18:14     ` Rik van Riel
2012-04-09 23:50       ` Alexey Ivanov
2012-04-10  0:31         ` Minchan Kim
2012-04-10  0:49           ` Rik van Riel [this message]
2012-04-10  1:25             ` Minchan Kim
2012-04-09 18:17     ` Ying Han

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