Messages in this thread | | | Date | Tue, 29 Jun 1999 00:30:19 +0000 | From | Steve Underwood <> | Subject | Re: Apache performance: Run queue proportional to number of connections? |
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Hi all,
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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