From:	 Rik van Riel <riel@conectiva.com.br>
To:	 Jan Harkes <jaharkes@cs.cmu.edu>
Subject: Re: page_launder() on 2.4.9/10 issue
Date:	 Tue, 4 Sep 2001 13:27:50 -0300 (BRST)
Cc:	 Marcelo Tosatti <marcelo@conectiva.com.br>,
	 Linus Torvalds <torvalds@transmeta.com>,
	 Daniel Phillips <phillips@bonn-fries.net>,
	 lkml <linux-kernel@vger.kernel.org>

On Tue, 4 Sep 2001, Jan Harkes wrote:

> NO, please don't add another list to fix the symptoms of bad page aging.
>
> One of the graduate students here at CMU has been looking at the 2.4 VM,
> trying to predict the size of the app that can possibly be loaded
> without causing the system to start trashing.

	[snip results]

> Aging is broken. Horribly. As a result, the inactive list is filled with
> pages that are not necessarily inactive.

I've been working on a CPU and memory efficient reverse
mapping patch for Linux, one which will allow us to do
a bunch of optimisations for later on (infrastructure)
and has as its short-term benefit the potential for
better page aging.

It seems the balancing FreeBSD does (up aging +3, down
aging -1, inactive list in LRU order as extra stage) is
working nicely on my laptop now, but I don't think I'll
be releasing that as part of the patch ...

	http://www.surriel.com/patches/2.4/2.4.8-ac12-pmap3

regards,

Rik
-- 
IA64: a worthy successor to i860.

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

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