[PLUG] Debian Sarge SMP slowness?

[Russell Senior]

>>>>> "Eric" == Eric Harrison <eharrison at mail.mesd.k12.or.us> writes:

Eric> One of the school districts I often work with (who happen to be
Eric> near Redmond Washington ;-) is having SMP performance problems
Eric> with the Sarge 2.6.8-i686-smp kernel.

Eric> They are working on a backup server. The symptom is that if they
Eric> fire up 6 concurrent backup processes, every minute or so one of
Eric> the processes goes to 100% wa state, the others go to 100% idle,
Eric> the backup processes go to a D state, and nothing happens for 10
Eric> - 60 seconds. Then everything works again for another minute.

Eric> Running the same tests on a Red Hat box, every process runs,
Eric> raising the load average to 6 as would be expected. The
Eric> throughput is twice as high as the Debian box.

Eric> Have any of you Debian gurus here seen this, and more
Eric> importantly know a fix? ;-)

Caveat: I don't use Debian's kernels, I compile my own from vanilla
tarballs.  

This might not be relevant, but I have seen thus far unexplained I/O
stalls on firewire/SBP2 attached storage when rsyncing to reiserfs
partitions.  Your friends stalls are very similar sounding.  I
especially see them running a "vmstat 1".

You might compare .configs or patches between the kernels.


-- 
Russell Senior         ``I have nine fingers; you have ten.''
seniorr at aracnet.com