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From: Chuck Lever <cel@monkey.org>
To: Roger Larsson <roger.larsson@norran.net>
Cc: Rik van Riel <riel@conectiva.com.br>,
	linux-mm@kvack.org, Matthew Dillon <dillon@apollo.backplane.com>
Subject: Re: [PATCH--] Re: Linux VM/IO balancing (fwd to linux-mm?) (fwd)
Date: Tue, 23 May 2000 12:51:15 -0400 (EDT)	[thread overview]
Message-ID: <Pine.BSO.4.20.0005231244060.1176-100000@naughty.monkey.org> (raw)
In-Reply-To: <392AA3D5.FD6B5399@norran.net>

hi roger-

list manipulations are probably more expensive than maintaining a "load
average" value associated with a page.  usually a list manipulation will
require several memory writes into areas shared across CPUs; maintaining a
weighted load average requires a single write.

this was an issue with andrea's original LRU implementation, IIRC.

On Tue, 23 May 2000, Roger Larsson wrote:

> From: Matthew Dillon <dillon@apollo.backplane.com>
> >     The algorithm is a *modified* LRU.  Lets say you decide on a weighting
> >     betweeen 0 and 10.  When a page is first allocated (either to the
> >     buffer cache or for anonymous memory) its statistical weight is
> >     set to the middle (5).  If the page is used often the statistical 
> >     weight slowly rises to its maximum (10).  If the page remains idle
> >     (or was just used once) the statistical weight slowly drops to its
> >     minimum (0).
> 
> My patches has been approaching this a while... [slowly...]
> The currently included patch adds has divided lru in four lists [0..3].
> New pages are added at level 1.
> Scan is performed - and referenced pages are moved up.
> 
> Pages are moved down due to list balancing, but I have been playing with
> other ideas.
> 
> These patches should be a good continuation point.
> Patches are against pre9-3 with Quintela applied.

	- Chuck Lever
--
corporate:	<chuckl@netscape.com>
personal:	<chucklever@bigfoot.com>

The Linux Scalability project:
	http://www.citi.umich.edu/projects/linux-scalability/

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  reply	other threads:[~2000-05-23 16:51 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2000-05-23 12:35 Rik van Riel
2000-05-23 15:29 ` [PATCH--] " Roger Larsson
2000-05-23 16:51   ` Chuck Lever [this message]
2000-05-23 19:56     ` Roger Larsson

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