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Date: Sun, 7 Nov 2004 20:46:48 +0000 (GMT)
From: Robert Watson <rwatson@freebsd.org>
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To: Joan Picanyol <lists-freebsd-stable@freebsd.org>
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Subject: Re: process stuck in nfsfsync state
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On Sun, 7 Nov 2004, Joan Picanyol wrote:

> * Joan Picanyol <lists-freebsd-stable@biaix.org> [20041025 18:09]:
> > * Robert Watson <rwatson@freebsd.org> [20041025 14:24]:
> > > - It would be useful to see if less complicated NFS meta-transactions than
> > >   "Start GTK" can trigger the problem.  For example, doing a large dd to a
> > >   file in NFS, varying the blocksize to see if you can find useful
> > >   thresholds that trigger the problem.  I see a lot of successful 512 byte
> > >   writes in the trace, but larger datagram sizes of 8192 for writes seem
> > >   to have problems.
> > 
> > Now this is interesting:
> > 
> > dd if=/dev/urandom of=/fs/bulk/mount/dummy bs=512 count=14
> > 
> > wedges the NFS mount point 100% of the times. Lowering the count to 13
> > doesn't reproduce the hang.
> 
> Oh well, I can't reproduce this any more after upgrading. Go figure... 

If it comes back, please let me know.  It sounds like it may have been a
device driver problem or switch problem.  I suppose it would be
interesting to have you downgrade and see if it comes back, but that might
be a lot more interesting from my perspective than your perspective :-).

Robert N M Watson             FreeBSD Core Team, TrustedBSD Projects
robert@fledge.watson.org      Principal Research Scientist, McAfee Research