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Date:      Mon, 25 Oct 2004 18:09:30 +0200
From:      Joan Picanyol <lists-freebsd-stable@biaix.org>
To:        Robert Watson <rwatson@freebsd.org>
Cc:        freebsd-stable@freebsd.org
Subject:   Re: process stuck in nfsfsync state
Message-ID:  <20041025160930.GA41784@grummit.biaix.org>
In-Reply-To: <Pine.NEB.3.96L.1041025131419.3203A-100000@fledge.watson.org>
References:  <20041025092330.GB39457@grummit.biaix.org> <Pine.NEB.3.96L.1041025131419.3203A-100000@fledge.watson.org>

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* Robert Watson <rwatson@freebsd.org> [20041025 14:24]:
> 
> On Mon, 25 Oct 2004, Joan Picanyol wrote:
> 
> > > Is there an response to the request?  If not, that might suggest the
> > > server is wedged, not the client.  If you are willing to share the results
> > > of a tcpdump -s 1500 -w <whatever> output from a few seconds during the
> > > wedge, that would be very useful.
> > 
> > Available at http://biaix.org/pk/debug/nfs/ These are from just after
> > logging in to GNOME until gconfd-2 goes to nfsfsync, and the nfs server
> > not responding messages start appearing. 
> 

[snip *much* appreciated detailed analysis]

>   So if possible, I might try some of the following:
[...]
> - I think someone already suggested disabling hardware checksumming, but
>   if you haven't tried that, it would be worth trying it.

No difference. 

> - 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.

An another possibly interesting data point is that NFS over TCP works
ok. For this I'm particularly grateful, since I can now mount my /home
fs and do my work.

Am I the only one seeing this?

tks
-- 
pica



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