Dean Gaudet wrote:
> > > >created something that has massive concurrency in the networking path in
> > > >SMP. 4 interfaces all constantly raising interrupts kills us dead. all
> > > >the hacking of the scheduler and vm and such are just noise when compared
> > > >to this bottleneck.
>
> I think I mentioned this a long time ago... at high speeds, various NT
> network drivers switch from interrupt-driven to polling. The interrupts
> just kill you after some point... and it's pointless to take them all,
> when you could just take a clock interrupt and go fetch packets.
>
> Another thing to think about -- is ways to have CPU/network card affinity.
> You don't want to be playing L1/2 cache ping-pong on the RAM you use to
> load the packets off the card. You hopefully want to use the packets in
> the CPU that you first read them on. The way we're restructuring apache
> will let us plug in whatever extra syscall goop is needed to help this.
>
> Dean
The original posting doesn't say if the 4 cards shared one interrupt or not.
Sharing helps a lot under high loads, when your chances of serving two or three
cards in one interrupt hit may be quite good - assuming the driver is designed to
do that. The fact he talks about a storm of interrupts suggests they were
separate.
Steve
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