On Wed, Sep 26, 2007 at 10:48:02AM -0700, Tom Bombadil wrote: > Hi Claudio... > > What does 'net.inet.ip.ifq.maxlen=256' do for us? > > Tried a few 'man', and a few google searches and I wasn't very > successful. Found tons of other posts telling ppl to bump up that > sysctl, but never found what it does exactly. >
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. -- :wq Claudio
