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Date: Fri, 21 Dec 2007 15:43:47 -0800
From: David G Lawrence <dg@dglawrence.com>
To: Alfred Perlstein <alfred@freebsd.org>
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Cc: freebsd-net@freebsd.org, freebsd-stable@freebsd.org
Subject: Re: Packet loss every 30.999 seconds
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> >    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.
> 
> I apologize for not reading the code as I am swamped, but a technique
> that Matt Dillon used for bufs might work here.
> 
> Can you use a placeholder vnode as a place to restart the scan?
> you might have to mark it special so that other threads/things
> (getnewvnode()?) don't molest it, but it can provide for a convenient
> restart point.

   That was one of the solutions that I considered and rejected since it
would significantly increase the overhead of the loop.
   The solution provided by Kostik Belousov that uses uio_yield looks like
a find solution. I intend to try it out on some servers RSN.

-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.