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Message-ID: <48C776B0.9070703@gmail.com>
Date: Wed, 10 Sep 2008 09:26:40 +0200
From: Andrea Righi <righi.andrea@gmail.com>
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To: Dave Hansen <dave@linux.vnet.ibm.com>
CC: Balbir Singh <balbir@linux.vnet.ibm.com>, Paul Menage <menage@google.com>,
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       David Radford <dradford@bluehost.com>,
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	<fernando@oss.ntt.co.jp>,
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       Andrew Morton <akpm@linux-foundation.org>,
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Subject: Re: [RFC] [PATCH -mm] cgroup: limit the amount of dirty file pages
References: <48C6987D.2050905@gmail.com> <1220982584.23386.219.camel@nimitz>
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Dave Hansen wrote:
> On Tue, 2008-09-09 at 17:38 +0200, Andrea Righi wrote:
>> It allows to control how much dirty file pages a cgroup can have at any
>> given time. This feature is supposed to be strictly connected to a
>> generic cgroup IO controller (see below).
> 
> So, this functions similarly to our global dirty ratio?  Is it just
> intended to keep a cgroup from wedging itself too hard with too many
> dirty pages, just like the global ratio?
> 
> -- Dave

Correct, it's the same functionality provided by vm.dirty_ratio and
vm.dirty_background_ratio, except that is intended to be per-cgroup.

Without this functionality, a cgroup can even dirty all its memory,
allocated by the memory controller, since statistics and writeback
configurations are global.

-Andrea