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RE: kjournald using up majority cpu%.


Sounds right - and for some reason it is taking a lot less CPU the last 24
hours - will see f it gets busy again.

Many thanks.

Nico Morrison
nico morrison micronicos com
Micronicos Limited  -  London, UK.
Tel: +44 20 8870 8849 Fax: +44 20 8870 5290

From: Stephen C. Tweedie [mailto:sct redhat com]
Sent: 09 December 2002 12:52
To: Nico Morrison
Cc: 'ext3-users redhat com'
Subject: Re: kjournald using up majority cpu%.


On Sat, 2002-12-07 at 16:45, Nico Morrison wrote:
> We run several RH7.2/7.3 servers & recently 2 of them, although still
> working fine, have started to show kjournald as generally using over 50%
> cpu% on 'top' - virtually continuously.  Free cpu% generally less than 25%
> now!
> Both machines are also using software RAID5 EIDE ....... otherwise are
> standard server installs.

Sounds like you may be spending more time in the raid5 or IDE driver
layers than in kjournald's own code --- all of the IO's CPU overhead can
show up in the context of the process which submitted the IO, and that
is kjournald in the case of ext3.

Could you try running a profile of this?  You need to reboot,
unfortunately, to pass in the "profile=2" kernel option; then
"readprofile" will extract the profiling information from the kernel.


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