On Thu, Oct 26, 2006 at 04:19:16PM +0200, Christoph Kaegi wrote:
> On 26.10-15:14, Manuel Bouyer wrote:
> > You can also look at netstat -q, to see if there are drops at a highter
> > level. If you see drops here you can try to bump IFQ_MAXLEN
> > to something larger than 256.
> 
> ---------------------------- 8< ----------------------------
> # netstat -q
> arpintrq:
>         queue length: 0
>         maximum queue length: 50
>         packets dropped: 826
> ipintrq:
>         queue length: 0
>         maximum queue length: 256
>         packets dropped: 91897332
> ---------------------------- 8< ----------------------------
> 
> Ugh! Seems like a lot of dropped packets on the last line.
> Can you explain, where exactly that these packets were
> dropped?

When a packet is received, the interrupt handler for the adapter places it
in the IP input queue, which is processed later at a lower interrupt
priority. What happens here is, I guess, that you have several adapters,
each with a large receive ring. When the interrupt handler is going to
process the receive ring of the adapters, and as each have several packets
it reaches the ipintrq length limit.

-- 
Manuel Bouyer <bouyer@antioche.eu.org>
     NetBSD: 26 ans d'experience feront toujours la difference
--