Test on 10GBE Intel based network card
fabrizio.invernizzi at telecomitalia.it
Tue Aug 4 07:55:19 UTC 2009
> >> The limitation that you see is about the max number of packets that
> >> FreeBSD can handle - it looks like your best performance is reached at
> >> 64 byte packets?
> > 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?
> ah that's the whole point of tuning :-)
> there are severalpossibities:
> 1/ the card's interrupts are probably attache dto aonly 1 cpu,
> so that cpu can do no more work
This seems not to be the problem. See below a top snapshot during a 64byte-long packet storm
last pid: 8552; load averages: 0.40, 0.09, 0.03 up 0+20:36:58 09:40:29
124 processes: 13 running, 73 sleeping, 38 waiting
CPU: 0.0% user, 0.0% nice, 86.3% system, 12.3% interrupt, 1.5% idle
Mem: 13M Active, 329M Inact, 372M Wired, 68K Cache, 399M Buf, 7207M Free
Swap: 2048M Total, 2048M Free
PID USERNAME THR PRI NICE SIZE RES STATE C TIME WCPU COMMAND
11 root 1 171 ki31 0K 16K RUN 3 20.2H 51.17% idle: cpu3
14 root 1 171 ki31 0K 16K RUN 0 20.2H 50.88% idle: cpu0
12 root 1 171 ki31 0K 16K RUN 2 20.2H 50.49% idle: cpu2
13 root 1 171 ki31 0K 16K RUN 1 20.2H 50.10% idle: cpu1
42 root 1 -68 - 0K 16K RUN 1 14:20 36.47% ix0 rxq
38 root 1 -68 - 0K 16K CPU0 0 14:15 36.08% ix0 rxq
44 root 1 -68 - 0K 16K CPU2 2 14:08 34.47% ix0 rxq
40 root 1 -68 - 0K 16K CPU3 3 13:42 32.37% ix0 rxq
It looks like the 4 rxq processes are bound to the 4 available cores with equal distribution.
> 2/ if more than 1 cpu is working, it may be that there is a lock in
> heavy contention somewhere.
This I think is the problem. I am trying to understand how to
1- see where the heavy contention is (context switching? Some limiting setting?)
2- mitigate it
> is the machine still responsive to other networks while
> running at maximum capacity on this network? (make sure that
> the other networks are on a differnet CPU (hmm I can't remember how to
> do that :-).
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