[OpenAFS-devel] Performance single proc. vers. SMP

[Hartmut Reuter]

I made a strange observation:

Running openafs (from cvs) on my laptop I got rather bad read
performance on large files: about 1.3 MB/s.

Then I built an SMP-kernel, rebooted with that one and built the the
libafs for SMP. With this one I can read with 5 MB/s. 

I also made fstraces in both cases. 

It turns out that the trace lines inside afs_UFSCacheFetchProc() which
appear whenever he wakes up waiters for tdc->f.validPos come rather
continously in the SMP case, but in the single processor case appear
some times long delays.

This lets me think of a problem in the rx-layer because in this loop
nothing else happens than rx_Read() and afs_osi_Write(). I suppose
afs_osi_write() is fast and could only be faster in the single-processor
kernel.

Any ideas?

Hartmut
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Hartmut Reuter                           e-mail reuter@rzg.mpg.de
					   phone +49-89-3299-1328
RZG (Rechenzentrum Garching)               fax   +49-89-3299-1301 
Computing Center of the Max-Planck-Gesellschaft (MPG) and the
Institut fuer Plasmaphysik (IPP)
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