Test on 10GBE Intel based network card

[Invernizzi Fabrizio]

Hi all.

Going on with my tests.
I noticed that I have always a (received) pps/interrupt ratio(per second) that is always about 14 (a very low ratio in my opinion).
If I disable aim via sysctl

sysctl -w dev.ix.0.enable_aim=0
dev.ix.0.enable_aim: 1 -> 0


this ration remain the same. Something going wrong with interrupt coalescing, but I can't find out what.

Any idea?


Fabrizio


> -----Original Message-----
> From: owner-freebsd-performance at freebsd.org [mailto:owner-freebsd-
> performance at freebsd.org] On Behalf Of Invernizzi Fabrizio
> Sent: martedì 4 agosto 2009 9.55
> To: Julian Elischer
> Cc: freebsd-performance at freebsd.org; Stefan Lambrev
> Subject: RE: Test on 10GBE Intel based network card
>
> > >> 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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>
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This e-mail and any attachments is confidential and may contain privileged information intended for the addressee(s) only. Dissemination, copying, printing or use by anybody else is unauthorised. If you are not the intended recipient, please delete this message and any attachments and advise the sender by return e-mail, Thanks.