Re: Gigabit Linux Server Bottlenecks

From: Ingo Molnar (mingo@chiara.csoma.elte.hu)
Date: Tue Feb 08 2000 - 07:16:36 EST


On Tue, 8 Feb 2000, Anton Ivanov wrote:

> Wrong. All GigE cards I have checked so far have interrupt mitigation.
> At init you program them to delay IRQ until that many packets are in
> the queue or a timer expires and the timer value. The only problem is
> that these are usually not passed as module params. So you have to
> recompile if you find your current mitigation params bad.

yep, also with jumbo frames (mtu 9000) there is no problem at all. Eg. the
SysKonnect cards i use do just over 20k IRQs/sec when i'm saturating
107MB/sec TCP bandwith - this IRQ load is simply not a problem at all for
an APIC controller. I've seen IRQ rates of 80k/sec as well.

> > Since no one seems to want to jump on the 8K jumbo frames bandwagon
>
> See above. If you program a sane GigE NIC correctly you actually
> transfer more than 8K at a time. Donald Becker's hamachi driver is a
> good example.

also other cards are using jumbo frames as well (and it actually makes
sense to increase packet size).

-- mingo

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