Packet loss every 30.999 seconds

David G Lawrence dg at
Wed Dec 19 09:13:32 PST 2007

> >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.


David G. Lawrence
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