Test on 10GBE Intel based network card

Invernizzi Fabrizio fabrizio.invernizzi at telecomitalia.it
Mon Aug 3 10:27:00 UTC 2009

> > If you are meaning in term of Packet per second, you are right.
> > These are the packet per second measured during tests:
> >
> > 64 byte:        610119 Pps
> > 512 byte:       516917 Pps
> > 1492 byte:      464962 Pps
> >
> >
> >> Am I correct that the maximum you can reach is around 639,000 packets
> >> per second?
> >
> > Yes, as you can see the maximum is 610119 Pps.
> > Where does this limit come from?
> I duno - the tests I did before were with SYN packets (random source)
> which was my worst scenario,
> and the server CPU were busy generating MD5 check sums for
> "syncache" (around 35% of the time).
> If I have to compare my results with your, you beat me with factor
> 2.5, may be because you use ICMP for the test
> and your processor is better then my test stations :)
> Also my experience is only with gigabit cards (em driver) and FreeBSD
> 7.something_before_1 where the em thread was eating 100% cpu.
> If you are lucky LOCK_PROFILING(9) will help you to see where the CPUs
> spend their time, if not you will see kernel panic :)

I will check, thanks for the hint.

> Once problematic locks identified they can be reworked, but I think
> the first part is already done
> and work on the second already started.
> In my experience increasing hw.em.rxd and hw.em.txd yelled better
> results, but I think ixgb already comes tuned by default
> as it still doesn't have to support such a large number of different
> cards.

I did some tuning in the code of the driver e recompiled the kernel in order to reduce context switching (interrupt mitigation) since the driver does not support POLLING.

> Also at the time of my tests there were not support for multi queues
> in the OS even if they were supported by the HW, which is changed in
> 7.2 (?)

It looks like multi queue is working since I can see the load distributed over the 4 cores.


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