em forwarding performance (was Proposed 6.2 em RELEASE patch

Mike Tancsa mike at sentex.net
Thu Nov 30 10:11:19 PST 2006

At 12:57 PM 11/30/2006, Ivan Voras wrote:
>Mike Tancsa wrote:
> > Yeah I inadvertently slighted the NetBSD folks by leaving them out.  So
> > I guess I better give them a try as well.
> >
> > The part that really surprises me is the drop in performance as firewall
> > rules are added to RELENG_6 and above.  Both LINUX and RELENG_4 seem to
> > scale well with the number of rules added but RELENG_6 takes a big drop.
>Wasn't there some important setting in ipfw you can tweak if you need
>lots of ipfw rules? Size of some hash table?
>Quick Googling found this: http://info.iet.unipi.it/~luigi/ip_dummynet/
>and net.inet.ip.fw.dyn_buckets: 256. AFAIK the hash size needed to be
>tweaked manually in the code, and net.inet.ip.fw.dyn_buckets: 256 is
>listed as read-only so this might be it. Maybe mailing Luigi will help
>finding out...

I was told offlist  "there is additional per-packet locking overhead 
not seen in RELENG_4 where all processing is covered by the same spl."...


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