Date: Thu, 1 Dec 2005 02:37:14 -0800
From: Andrew Morton <akpm@osdl.org>
To: Wu Fengguang <wfg@mail.ustc.edu.cn>
Cc: linux-kernel@vger.kernel.org, christoph@lameter.com, riel@redhat.com,
       a.p.zijlstra@chello.nl, npiggin@suse.de, andrea@suse.de,
       marcelo.tosatti@cyclades.com, magnus.damm@gmail.com,
       wfg@mail.ustc.edu.cn
Subject: Re: [PATCH 02/12] mm: supporting variables and functions for
 balanced zone aging
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Wu Fengguang <wfg@mail.ustc.edu.cn> wrote:
>
>  The zone aging rates are currently imbalanced,

ZONE_DMA is out of whack.  It shouldn't be, and I'm not aware of anyone
getting in and working out why.  I certainly wouldn't want to go and add
all this stuff without having a good understanding of _why_ it's out of
whack.  Perhaps it's just some silly bug, like the thing I pointed at in
the previous email.

> the gap can be as large as 3 times,

What's the testcase?

> which can severely damage read-ahead requests and shorten their
>  effective life time.

Have you any performance numbers for this?
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