Packet loss every 30.999 seconds

David G Lawrence dg at
Tue Dec 18 08:57:33 PST 2007

> I got an almost identical delay (with 64000 vnodes).
> Now, 17ms isn't much.

   Says you. On modern systems, trying to run a pseudo real-time application
on an otherwise quiescent system, 17ms is just short of an eternity. I agree
that the syncer should be preemptable (which is what my bandaid patch
attempts to do), but that probably wouldn't have helped my specific problem
since my application was a user process, not a kernel thread.
   All of my systems have options PREEMPTION - that is the default in
6+. It doesn't affect this problem.
   On the other hand, the syncer shouldn't be consuming this much CPU in
the first place. There is obviously a bug here. Of course looking through
all of the vnodes in the system for something dirty is stupid in the
first place; there should be a seperate list for that. ...but a simple
fix is what is needed right now.
   I'm going to have to bow out of this discussion now. I just don't have
the time for it.


David G. Lawrence
Download Technologies, Inc. - - (866) 399 8500
The FreeBSD Project -
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