From: Matthias Dahl <mlkernel@mortal-soul.de>
To: Paolo Ornati <ornati@fastwebnet.it>
Subject: Re: sluggish system responsiveness under higher IO load
Date: Sat, 14 Oct 2006 16:39:57 +0200
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Cc: Jens Axboe <axboe@suse.de>, Mike Galbraith <efault@gmx.de>,
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On Friday 06 October 2006 17:58, Paolo Ornati wrote:

> I used to have this type of problem and 2.6.19-rc1 looks much better
> than 2.6.18.
>
> I'm using CONFIG_PREEMPT + CONFIG_PREEMPT_BKL, CFQ i/o scheduler
> and /proc/sys/vm/swappiness = 20.

I will give 2.6.19 a test in a few weeks when the dust of all the changes have 
settled a bit. :-)

As my Mike Galbraith suggested, I made some tests with renicing the IO 
intensive applications. This indeed makes a hell of a difference. Currently I 
am renicing everything that causes a lot of disk IO to a nice of 19. Even 
though this doesn't fix it completely, the occasional short hangs have become 
less common.

Unfortunately things have gotten a bit worse again since I switched my machine 
over to a linux software RAID5 (3 sata disks attached to the nforce4 ultra) 
even though I hoped quite the opposite would happen.

Have a nice weekend,
matthew.
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