From: Daniel Phillips <phillips@bonn-fries.net>
To: Marco Colombo <marco@esi.it>
Cc: Rik van Riel <riel@conectiva.com.br>, <mike_phillips@urscorp.com>,
<linux-kernel@vger.kernel.org>
Subject: Re: VM Requirement Document - v0.0
Date: Wed, 4 Jul 2001 16:44:24 +0200 [thread overview]
Message-ID: <01070416442405.03760@starship> (raw)
In-Reply-To: <Pine.LNX.4.33.0107041026140.4236-100000@Megathlon.ESI>
In-Reply-To: <Pine.LNX.4.33.0107041026140.4236-100000@Megathlon.ESI>
On Wednesday 04 July 2001 10:32, Marco Colombo wrote:
> On Tue, 3 Jul 2001, Daniel Phillips wrote:
> > On Monday 02 July 2001 20:42, Rik van Riel wrote:
> > > On Thu, 28 Jun 2001, Marco Colombo wrote:
> > > > I'm not sure that, in general, recent pages with only one access are
> > > > still better eviction candidates compared to 8 hours old pages. Here
> > > > we need either another way to detect one-shot activity (like the one
> > > > performed by updatedb),
> > >
> > > Fully agreed, but there is one problem with this idea.
> > > Suppose you have a maximum of 20% of your RAM for these
> > > "one-shot" things, now how are you going to be able to
> > > page in an application with a working set of, say, 25%
> > > the size of RAM ?
> >
> > Easy. What's the definition of working set? Those pages that are
> > frequently referenced. So as the application starts up some of its pages
> > will get promoted from used-once to used-often. (On the other hand, the
> > target behavior here conflicts with the goal of grouping together several
> > temporally-related accesses to the same page together as one access, so
> > there's a subtle distinction to be made here, see below.)
>
> [...]
>
> In Rik example, the ws is larger than available memory. Part of it
> (the "hottest" one) will get double-accesses, but other pages will keep
> condending the few available (physical) pages with no chance of being
> accessed twice. But see my previous posting...
But that's exactly what we want. Note that the idea of reserving a fixed
amount of memory for "one-shot" pages wasn't mine. I see no reason to set a
limit. There's only one critereon: does a page get referenced between the
time it's created and when its probation period expires?
Once a page makes it into the active (level 2) set it's on an equal footing
with lots of others and it's up to our intrepid one-hand clock to warm it up
or cool it down as appropriate. On the other hand, if the page gets sent to
death row it still has a few chances to prove its worth before being cleaned
up and sent to the aba^H^H^H^H^H^H^H^H reclaimed. (Apologies for the
multiplying metaphors ;-)
--
Daniel
next prev parent reply other threads:[~2001-07-04 14:42 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-06-28 12:20 VM Requirement Document - v0.0 mike_phillips
2001-06-28 12:30 ` Alan Cox
2001-06-28 13:33 ` Tobias Ringstrom
2001-06-28 13:37 ` Alan Cox
2001-06-28 14:04 ` Tobias Ringstrom
2001-06-28 14:14 ` Alan Cox
2001-06-28 14:52 ` Daniel Phillips
2001-06-28 14:39 ` Daniel Phillips
2001-06-28 18:01 ` Marco Colombo
2001-07-02 18:42 ` Rik van Riel
2001-07-03 10:33 ` Marco Colombo
2001-07-03 15:04 ` Daniel Phillips
2001-07-03 18:24 ` Daniel Phillips
2001-07-04 8:12 ` Ari Heitner
2001-07-04 9:41 ` Marco Colombo
2001-07-04 15:03 ` Daniel Phillips
2001-07-03 18:29 ` Daniel Phillips
2001-07-04 8:32 ` Marco Colombo
2001-07-04 14:44 ` Daniel Phillips [this message]
2001-06-28 15:21 ` Jonathan Morton
2001-06-28 16:02 ` Daniel Phillips
-- strict thread matches above, loose matches on Subject: below --
2001-07-05 15:09 mike_phillips
2001-07-05 15:04 Daniel Phillips
[not found] ` <fa.jprli0v.qlofoc@ifi.uio.no>
[not found] ` <fa.e66agbv.hn0u1v@ifi.uio.no>
2001-07-05 1:49 ` Dan Maas
2001-07-05 13:02 ` Daniel Phillips
2001-07-05 14:00 ` Xavier Bestel
2001-07-05 14:51 ` Daniel Phillips
2001-07-05 15:00 ` Xavier Bestel
2001-07-05 15:12 ` Daniel Phillips
2001-07-05 15:12 ` Alan Shutko
[not found] ` <002501c104f4/mnt/sendme701a8c0@morph>
2001-07-09 12:17 ` Pavel Machek
2001-07-12 23:46 ` Daniel Phillips
2001-07-13 21:07 ` Pavel Machek
2001-07-06 19:09 ` Rik van Riel
2001-07-06 21:57 ` Daniel Phillips
2001-07-04 16:08 mike_phillips
[not found] <fa.oqkojpv.3hosb7@ifi.uio.no>
[not found] ` <fa.jpsks3v.1o2gag4@ifi.uio.no>
2001-06-27 0:43 ` Dan Maas
2001-06-27 0:45 ` Mike Castle
2001-06-27 10:50 ` Xavier Bestel
2001-06-27 8:53 Martin Knoblauch
2001-06-27 18:13 ` Rik van Riel
2001-06-28 6:59 ` Martin Knoblauch
2001-06-28 11:27 ` Helge Hafting
2001-06-28 11:54 ` Martin Knoblauch
2001-06-28 12:02 ` Tobias Ringstrom
2001-06-28 12:31 ` Xavier Bestel
2001-06-28 13:05 ` Tobias Ringstrom
2001-06-26 19:58 Jason McMullan
2001-06-26 21:21 ` Rik van Riel
2001-06-26 21:29 ` Jason McMullan
2001-06-26 21:33 ` John Stoffel
2001-06-26 21:42 ` Rik van Riel
2001-06-26 22:21 ` Stefan Hoffmeister
2001-06-26 22:48 ` Jeffrey W. Baker
2001-06-27 0:18 ` Mike Castle
2001-06-28 13:07 ` John Fremlin
2001-06-27 13:36 ` Marco Colombo
2001-06-27 3:55 ` Daniel Phillips
2001-06-27 14:09 ` Pozsar Balazs
2001-06-28 22:47 ` John Fremlin
2001-06-30 15:37 ` Pavel Machek
2001-07-10 10:34 ` David Woodhouse
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