From: Roger Luethi <rl@hellgate.ch>
To: Rik van Riel <riel@redhat.com>
Cc: William Lee Irwin III <wli@holomorphy.com>,
Con Kolivas <kernel@kolivas.org>,
Chris Vine <chris@cvine.freeserve.co.uk>,
linux-kernel@vger.kernel.org,
"Martin J. Bligh" <mbligh@aracnet.com>
Subject: Re: 2.6.0-test9 - poor swap performance on low end machines
Date: Tue, 9 Dec 2003 17:31:49 +0100 [thread overview]
Message-ID: <20031209163149.GA7735@k3.hellgate.ch> (raw)
In-Reply-To: <Pine.LNX.4.44.0312091103100.8917-100000@chimarrao.boston.redhat.com>
On Tue, 09 Dec 2003 11:04:49 -0500, Rik van Riel wrote:
> > The classic strategies based on these criteria work for transaction and
> > batch systems. They are all but useless, though, for a workstation and
> > even most modern servers, due to assumptions that are incorrect today
> > (remember all the degrees of freedom a scheduler had 30 years ago)
> > and additional factors that only became crucial in the past few decades
> > (latency again).
>
> Don't forget that computers have gotten a lot slower
> over the years ;)
>
> Swapping out a 64kB process to a disk that does 180kB/s
> is a lot faster than swapping out a 100MB process to a
> disk that does 50MB/s ...
>
> Once you figure in seek times, the picture looks even
> worse.
Exactly -- I did mention the growing access time gap between RAM and
disks in an earlier message. Yes, there are quite a few developments in
hardware and in the way we use computers (interactive, Client/Server,
dedicated machines, etc.) that made thrashing pretty much unsolvable
at an OS level. Fortunately, fixing it in hardware by adding RAM works
for most.
What we _can_ do in software, though, is prevent thrashing as long as
possible. Comparing 2.4 and 2.6 shows that a kernel can still make a
significant difference with smart pageout algorithms, I/O scheduling etc.
But you won't get much help with that from ancient papers.
Roger
next prev parent reply other threads:[~2003-12-09 16:32 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-10-29 22:30 2.6.0-test9 - poor swap performance on low end machines Chris Vine
2003-10-31 3:57 ` Rik van Riel
2003-10-31 11:26 ` Roger Luethi
2003-10-31 12:37 ` Con Kolivas
2003-10-31 12:59 ` Roger Luethi
2003-10-31 12:55 ` Ed Tomlinson
2003-11-01 18:34 ` Pasi Savolainen
2003-11-06 18:40 ` bill davidsen
2003-10-31 21:52 ` Chris Vine
2003-11-02 23:06 ` Chris Vine
2003-11-03 0:48 ` Con Kolivas
2003-11-03 21:13 ` Chris Vine
2003-11-04 2:55 ` Con Kolivas
2003-11-04 22:08 ` Chris Vine
2003-11-04 22:30 ` Con Kolivas
2003-12-08 13:52 ` William Lee Irwin III
2003-12-08 14:23 ` Con Kolivas
2003-12-08 14:30 ` William Lee Irwin III
2003-12-09 21:03 ` Chris Vine
2003-12-13 14:08 ` Chris Vine
2003-12-08 19:49 ` Roger Luethi
2003-12-08 20:48 ` William Lee Irwin III
2003-12-09 0:27 ` Roger Luethi
2003-12-09 4:05 ` William Lee Irwin III
2003-12-09 15:11 ` Roger Luethi
2003-12-09 16:04 ` Rik van Riel
2003-12-09 16:31 ` Roger Luethi [this message]
2003-12-09 18:31 ` William Lee Irwin III
2003-12-09 19:38 ` William Lee Irwin III
2003-12-10 13:58 ` Roger Luethi
2003-12-10 17:47 ` William Lee Irwin III
2003-12-10 22:23 ` Roger Luethi
2003-12-11 0:12 ` William Lee Irwin III
2003-12-10 21:04 ` Rik van Riel
2003-12-10 23:17 ` Roger Luethi
2003-12-11 1:31 ` Rik van Riel
2003-12-11 10:16 ` Roger Luethi
2003-12-10 23:30 ` Helge Hafting
2003-12-10 21:52 ` Andrea Arcangeli
2003-12-10 22:05 ` Roger Luethi
2003-12-10 22:44 ` Andrea Arcangeli
2003-12-11 1:28 ` William Lee Irwin III
2003-12-11 1:32 ` Rik van Riel
2003-12-11 10:16 ` Roger Luethi
2003-12-15 23:31 ` Andrew Morton
2003-12-15 23:37 ` Andrea Arcangeli
2003-12-15 23:54 ` Andrew Morton
2003-12-16 0:17 ` Rik van Riel
2003-12-16 11:23 ` Roger Luethi
2003-12-16 16:29 ` Rik van Riel
2003-12-17 11:03 ` Roger Luethi
2003-12-17 11:06 ` William Lee Irwin III
2003-12-17 16:50 ` Roger Luethi
2003-12-17 11:33 ` Rik van Riel
2003-12-17 18:53 ` Rik van Riel
2003-12-17 19:27 ` William Lee Irwin III
2003-12-17 19:51 ` Rik van Riel
2003-12-17 19:49 ` Roger Luethi
2003-12-17 21:41 ` Andrew Morton
2003-12-17 21:41 ` Roger Luethi
2003-12-18 0:21 ` Rik van Riel
2003-12-18 22:53 ` Roger Luethi
2003-12-18 23:38 ` William Lee Irwin III
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