* Tony Sarendal <tony@polarcap.org> [2007-09-27 10:36]:
quoted text
> On 9/26/07, Tom Bombadil <grlists@gmail.com> wrote:
> > > net.inet.ip.ifq.maxlen defines how many packets can be queued in the IP
> > > input queue before further packets are dropped. Packets comming from the
> > > network card are first put into this queue and the actuall IP packet
> > > processing is done later. Gigabit cards with interrupt mitigation may
> > spit
> > > out many packets per interrupt plus heavy use of pf can slowdown the
> > > packet forwarding. So it is possible that a heavy burst of packets is
> > > overflowing this queue. On the other hand you do not want to use a too
> > big
> > > number because this has negative effects on the system (livelock etc).
> > > 256 seems to be a better default then the 50 but additional tweaking may
> > > allow you to process a few packets more.
> > Thanks Claudio...
> > In the link that Stuart posted here, Henning mentions 256 times the
> > number of interfaces:
> > http://archive.openbsd.nu/?ml=openbsd-tech&a=2006-10&t=2474666
> Is that per physical or per logical interface  ?

it is a rule of thumb. an approximation. for typical cases.

quoted text
> tony@rocket$ ifconfig -a | grep ^vlan | wc -l
>     4094

that is not a typical case.
you do not wanna set your ifqlen to 1048064 :)

the highest qlen I have is somewhere around 2500.
where the high watermark is... I cannot really say. I'd be careful 
going far higher than the above.

-- 
Henning Brauer, hb@bsws.de, henning@openbsd.org
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