Invernizzi Fabrizio wrote:
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
there ia a lock profiling tool that right now I can't remember the
name of..
look it up with google :-) FreeBSD lock profiling tool
ah, first hit...
http://blogs.epfl.ch/article/23832
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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