Another way to do it is to switch/route multiple packets
per interrupt. This is a solution a large router vendor
does...
-Anders
> one of them is the (relatively high) interrupt overhead,
> as reported by many. There is a good description of the problem
> in the Click's paper at http://www.pdos.lcs.mit.edu/click/ and
> in the Mogul's paper referenced in there.
>
> In line with what is suggested above, reducing this overhead requires
> a solution that involves some form of polling. This gives you
> a lot of improvement in performance, maybe by a factor of 3 or so.
>
> The approach we are trying is based on some very simple modifications
> to the interrupt dispatcher. Basically the idea is to run with
> e.g. HZ=2000 or so, and disable interrupts on a line for the rest
> of a tick after you get more than X interrupts per tick (with small
> X).
>
> The system remains decently responsive, because you are re-enabling
> ints at the next clock tick (in 500us or less), or when you enter
> the idle loop; and when you happen to call ether_output() you have
> a chance to poll the device.
>
> The advantage of this approach is that you don't have to implement
> a real polling system (which can become expensive when the number
> of cards in a box becomes large), and that modifications are
> relatively small and, especially, device-independent. Hopefully
> we will be able to post them soon, after a bit more experiments.
>
> After this change, using FASTFORWARDING seems to save
> another 20-30% on the per-packet processing time.
>
> cheers
> luigi
> -----------------------------------+-------------------------------------
> Luigi RIZZO, [EMAIL PROTECTED] . Dip. di Ing. dell'Informazione
> http://www.iet.unipi.it/~luigi/ . Universita` di Pisa
> TEL/FAX: +39-050-568.533/522 . via Diotisalvi 2, 56126 PISA (Italy)
> Mobile +39-347-0373137
> -----------------------------------+-------------------------------------
>
> To Unsubscribe: send mail to [EMAIL PROTECTED]
> with "unsubscribe freebsd-net" in the body of the message
>
To Unsubscribe: send mail to [EMAIL PROTECTED]
with "unsubscribe freebsd-net" in the body of the message
