Re: [RFC] Optimization for use-once pages

From: Rik van Riel (
Date: Tue Jul 24 2001 - 17:25:06 EST

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)



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

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