Date: Sun, 4 Jan 2004 15:22:31 -0800
From: Mike Fedyk <mfedyk@matchmail.com>
To: Andrew Morton <akpm@osdl.org>
Cc: ornati@lycos.it, gandalf@wlug.westbo.se, linuxram@us.ibm.com,
       linux-kernel@vger.kernel.org
Subject: Re: Buffer and Page cache coherent? was: Strange IDE performance change in 2.6.1-rc1 (again)
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On Sun, Jan 04, 2004 at 02:10:30PM -0800, Andrew Morton wrote:
> Mike Fedyk <mfedyk@matchmail.com> wrote:
> >
> > On Sat, Jan 03, 2004 at 02:40:03PM -0800, Andrew Morton wrote:
> > > No effort was made to optimise buffered blockdev reads because it is not
> > > very important and my main interest was in data coherency and filesystem
> > > metadata consistency.
> > 
> > Does that mean that blockdev reads will populate the pagecache in 2.6?
> 
> They have since 2.4.10.  The pagecache is the only cacheing entity for file
> (and blockdev) data.

There was a large thread after 2.4.10 was released about speeding up the
boot proces by reading the underlying blockdev of the root partition in
block order.

Unfortunately at the time reading the files through the pagecache would
cause a second read of the data even if it was already buffered.  I don't
remember the exact details.

Are you saying this is now resolved?  And the above optimization will work?
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