Subject: Re: Strange IDE performance change in 2.6.1-rc1 (again)
From: Ram Pai <linuxram@us.ibm.com>
To: Andrew Morton <akpm@osdl.org>
Cc: Paolo Ornati <ornati@lycos.it>, gandalf@wlug.westbo.se,
       linux-kernel@vger.kernel.org
In-Reply-To: <20040107155729.7e737c36.akpm@osdl.org>
References: <200401021658.41384.ornati@lycos.it>
	 <200401071559.16130.ornati@lycos.it>
	 <1073503421.10018.17.camel@dyn319250.beaverton.ibm.com>
	 <200401072112.35334.ornati@lycos.it>
	 <20040107155729.7e737c36.akpm@osdl.org>
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Date: 07 Jan 2004 23:31:44 -0800
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On Wed, 2004-01-07 at 15:57, Andrew Morton wrote:
> Paolo Ornati <ornati@lycos.it> wrote:
> >
> > I haven't done a lot of tests but it seems to me that the changes in 
> > mm/filemap.c are the only things that influence the sequential read 
> > performance on my disk.
> 
> The fact that this only happens when reading a blockdev (true?) is a big
> hint.   Maybe it is because regular files implement ->readpages.
> 
> If the below patch makes read throughput worse on regular files too then
> that would confirm the idea.

No the throughput did not worsen with the patch, for regular files(on
scsi disk). Lets see what Paolo Ornati finds.

Its something to do with the changes in filemap.c,
RP

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