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>>>>> "Ingo" == Ingo Molnar <mingo@chiara.csoma.elte.hu> writes:

Ingo> 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.

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

Sorry but thats *BAD* performance by the SK card. I do around 2.5K
ints/sec with the Alteon when doing 65MB/sec traffic in one direction
with regular sized frames. The load is maybe not a problem for the
APIC, but 80k/sec truly sucks for the CPUs considering the number of
context saves/restores they have to do.

>> 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.

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

It's the switch vendors who are causing the problems.

Jes
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