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Date: Wed, 5 Nov 2008 13:55:33 -0800
Message-ID: <6599ad830811051355n5765a115mbd6eb389504d125d@mail.gmail.com>
Subject: Re: [patch 0/7] cpuset writeback throttling
From: Paul Menage <menage@google.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux-foundation.org>, peterz@infradead.org,
       rientjes@google.com, npiggin@suse.de, dfults@sgi.com,
       linux-kernel@vger.kernel.org, containers@lists.osdl.org
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On Wed, Nov 5, 2008 at 12:56 PM, Andrew Morton
<akpm@linux-foundation.org> wrote:
>>
>> 1. Reduce the global dirty ratios so that the number of dirty pages in a
>> cpuset cannot become too high.
>
> That would be less than the smallest node's memory capacity, I guess.

Even that doesn't work - if there's a single global limit on dirty
pages, then any cpuset/cgroup with access to enough memory can exhaust
that limit and cause other processes to block when they try to write
to disk. You need independent dirty counts to avoid that, whether it
be per-node or per-cgroup.

Paul