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Date: Tue, 24 Jul 2001 19:25:06 -0300 (BRST)
From: Rik van Riel <riel@conectiva.com.br>
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To: Patrick Dreker <patrick@dreker.de>
Cc: Linus Torvalds <torvalds@transmeta.com>, <phillips@bonn-fries.net>,
        <linux-kernel@vger.kernel.org>
Subject: Re: [RFC] Optimization for use-once pages
In-Reply-To: <E15PATS-0000A5-00@wintermute>
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On Wed, 25 Jul 2001, Patrick Dreker wrote:

> Anyways, I still have some old routines in the program doing the
> same via read(). I have tried that (although the program is
> pretty silly, as it reads the 240megs in 4 byte chunks.... the
> call overhead probably is the bigger problem there...) and it
> improved the runtime by aproximately 20% using the use_once
> patch.
>
> linux-2.4.7:
> 22.300u 135.310s 2:41.38 97.6%  0+0k 0+0io 110pf+0w
>
> linux-2.4.5-use_once:
> 14.980u 108.870s 2:09.79 95.4%  0+0k 0+0io 200pf+0w

COOL ....

> Both measurements taken after reboot and while running KDE2.2 As
> stated: I am still willing to do further experiments...
> (read()ing larger chunks at once?)

Could you try reading 4kB chunks at once ?

That way you should truly only touch each page once.

(using smaller chunks, or chunks which aren't a
multiple of 4kB should break the current code)

regards,

Rik
--
Executive summary of a recent Microsoft press release:
   "we are concerned about the GNU General Public License (GPL)"


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