Date: Tue, 4 Aug 2009 09:55:13 +0200 From: Invernizzi Fabrizio <fabrizio.invernizzi@telecomitalia.it> To: Julian Elischer <julian@elischer.org> Cc: "freebsd-performance@freebsd.org" <freebsd-performance@freebsd.org>, Stefan Lambrev <stefan.lambrev@moneybookers.com> Subject: RE: Test on 10GBE Intel based network card Message-ID: <36A93B31228D3B49B691AD31652BCAE9A45696721F@GRFMBX702BA020.griffon.local> In-Reply-To: <4A77094C.8030308@elischer.org> References: <36A93B31228D3B49B691AD31652BCAE9A4560DF911@GRFMBX702BA020.griffon.local> <0E567C7E-4EAA-4B89-9A8D-FD0450D32ED7@moneybookers.com> <36A93B31228D3B49B691AD31652BCAE9A4560DF947@GRFMBX702BA020.griffon.local> <4A77094C.8030308@elischer.org>
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> >> 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+20:3=
6:58 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: c=
pu3
14 root 1 171 ki31 0K 16K RUN 0 20.2H 50.88% idle: c=
pu0
12 root 1 171 ki31 0K 16K RUN 2 20.2H 50.49% idle: c=
pu2
13 root 1 171 ki31 0K 16K RUN 1 20.2H 50.10% idle: c=
pu1
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 e=
qual 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 sett=
ing?)
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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