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Re: High load on Squid server after change from reiserfs to ext3



On May 24, 2002  13:40 -0400, Andreas Jung wrote:
> From: "Andreas Dilger" <adilger clusterfs com>
> > One simple question - does the increase in the load value actually
> > affect squid performance?  You say there is no increase in CPU
> > utilization.  That may be good or it may be bad, depending if the "idle"
> > CPU is actually waiting on I/O to complete.
> >
> > What does the output of vmstat on both systems show?  Please send two
> > traces, one during low load and one during high load.
> 
> Our big brother diagrams show that the CPU utilization remains *low* all
> the time. I have been running vmstat on both machines when one of the
> machine had a spike. But both machines showed more ore less identical
> vmstat output:  CPU was about 85% idle, no swapping, not much interrupts
> and context switches.
> In general, vmstat showed a perfect behaviour except that the load average
> went up on one box.

Then it is nothing to worry about.  The "load average" does not indicate
anything other than the number of processes runnable or waiting for
disk I/O.  It is likely that when you are doing a large journal flush
the kjournald process is waiting for the disk I/O to complete, so it is
counted 1 towards the load average.  This in itself does not affect the
performance of the system.

Cheers, Andreas
--
Andreas Dilger
http://www-mddsp.enel.ucalgary.ca/People/adilger/
http://sourceforge.net/projects/ext2resize/





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