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Date: Wed, 19 Dec 2007 09:13:31 -0800
From: David G Lawrence <dg@dglawrence.com>
To: Mark Fullmer <maf@eng.oar.net>
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Cc: freebsd-net@freebsd.org, freebsd-stable@freebsd.org,
	Bruce Evans <brde@optusnet.com.au>
Subject: Re: Packet loss every 30.999 seconds
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> >Try it with "find / -type f >/dev/null" to duplicate the problem  
> >almost
> >instantly.
> 
> I was able to verify last night that (cd /; tar -cpf -) > all.tar would
> trigger the problem.  I'm working getting a test running with
> David's ffs_sync() workaround now, adding a few counters there should
> get this narrowed down a little more.

   Unfortunately, the version of the patch that I sent out isn't going to
help your problem. It needs to yield at the top of the loop, but vp isn't
necessarily valid after the wakeup from the msleep. That's a problem that
I'm having trouble figuring out a solution to - the solutions that come
to mind will all significantly increase the overhead of the loop.
   As a very inadequate work-around, you might consider lowering
kern.maxvnodes to something like 20000 - that might be low enough to
not trigger the problem, but also be high enough to not significantly
affect system I/O performance.

-DG

David G. Lawrence
President
Download Technologies, Inc. - http://www.downloadtech.com - (866) 399 8500
The FreeBSD Project - http://www.freebsd.org
Pave the road of life with opportunities.