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Date: Mon, 1 Oct 2001 16:44:52 -0300 (BRST)
From: Rik van Riel <riel@conectiva.com.br>
X-X-Sender: <riel@imladris.rielhome.conectiva>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Lorenzo Allegrucci <lenstra@tiscalinet.it>, <linux-kernel@vger.kernel.org>,
        Linus Torvalds <torvalds@transmeta.com>
Subject: Re: VM: 2.4.10 vs. 2.4.10-ac2 and qsort()
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On Mon, 1 Oct 2001, Alan Cox wrote:

> > I'm not sure either, since qsort doesn't really have much
> > locality of reference but just walks all over the place.
>
> qsort can be made to perform reasonably well providing you try to cache
> colour the objects you sort and try to use prefetches a bit.

That won't quite work when the qsort in question is 150%
the size of your RAM ;)

> > One thing which could make 2.4.10 faster for this single case
> > is the fact that it doesn't keep any page aging info, so IO
> > clustering won't be confused by the process accessing its
> > pages ;)
>
> I don't think that is too unusual a case. If the smarter vm is making
> poorer I/O clustering decisions it wants investigating

Absolutely, this is something we really want to know ...

I guess I'll play with Lorenzo's program a bit to see how
the system behaves and how it can be improved.

regards,

Rik
-- 
IA64: a worthy successor to i860.

http://www.surriel.com/		http://distro.conectiva.com/

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