Packet loss every 30.999 seconds

Alfred Perlstein alfred at
Sat Dec 22 20:04:42 PST 2007

* David G Lawrence <dg at> [071221 23:31] wrote:
> > > > 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.
> > 
> > Out of curiosity's sake, why would it make the loop slower?  one
> > would only add the placeholder when yielding, not for every iteration.
>    Actually, I misread your suggestion and was thinking marker flag,
> rather than placeholder vnode. Sorry about that. The current code
> actually already uses a marker vnode. It is hidden and obfuscated in
> the MNT_VNODE_FOREACH macro, further hidden in the __mnt_vnode_first/next
> functions, so it should be safe from vnode reclaimation/free problems.

That level of obscuring is a bit worrysome.

Yes, I did mean placeholder vnode.

Even so, is it of utility or not?

Or is it already being used and I'm missing something and should
just "utsl" at this point?

- Alfred Perlstein

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