From: Con Kolivas <kernel@kolivas.org>
To: warudkar@vsnl.net, linux-kernel@vger.kernel.org
Subject: Re: 2.6.0-test4-mm1 - kswap hogs cpu OO takes ages to start!
Date: Wed, 27 Aug 2003 21:37:42 +1000
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Cc: Andrew Morton <akpm@osdl.org>
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On Thu, 28 Aug 2003 07:38, warudkar@vsnl.net wrote:
> Trying out 2.6.0-test4-mm1. Inside KDE, I start OpenOffice.org, Rational
> Rose and Konsole at a time. All of these take extremely long time to
> startup. (approx > 5 minutes). Kswapd hogs the CPU all the time. X becomes
> unusable till all of them startup, although I can telnet and run top. Same
> thing run under 2.4.18 starts up in 3 minutes, X stays usable and kswapd
> never take more than 2% CPU.

Yes I can reproduce this with a memory heavy load as well on low memory 
(linking at the end of a big kernel compile is standard problem). I actually 
found the best workaround was to increase the swappiness instead of 
decreasing it.

Try 
echo 100 > /proc/sys/vm/swappiness

time it

then try
echo 0 > /proc/sys/vm/swappiness

you'll see that at low swappiness kswapd0 can use ridiculous amounts of cpu 
trying to avoid swap. The default is 60.

Con

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