From: Roger Larsson <roger.larsson@norran.net>
To: Chuck Lever <cel@monkey.org>
Cc: linux-mm@kvack.org
Subject: Re: [PATCH--] Re: Linux VM/IO balancing (fwd to linux-mm?) (fwd)
Date: Tue, 23 May 2000 21:56:35 +0200 [thread overview]
Message-ID: <392AE273.D24CBC10@norran.net> (raw)
In-Reply-To: <Pine.BSO.4.20.0005231244060.1176-100000@naughty.monkey.org>
Yes, I know - that is why I do _fewer_ memory writes than the standard
pre9-3 kernel!
The standard kernel deletes and reinserts every linked page.
I do only move referenced pages once a second (trim able) in age_mmap or
when
hit by a search in shrink_mmap (not that likely due to age_mmap).
Other pages are not modified!
Since all pages is not in the lru (or phys page array) you have to
maintain
a list. That can be fixed in 2.5 ...
/RogerL
Chuck Lever wrote:
>
> 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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prev parent reply other threads:[~2000-05-23 19:56 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
2000-05-23 19:56 ` Roger Larsson [this message]
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