Strange CPU distributionat very high level bandwidth

[Invernizzi Fabrizio]

There is an error in my previous email: the upper limit I see is 5722 Mbps (total).

I am sending 239700 pps  per interface, 1492-bytes long.

Fabrizio



> -----Original Message-----
> From: Gergely CZUCZY [mailto:phoemix at harmless.hu]
> Sent: mercoledì 19 agosto 2009 12.57
> To: Invernizzi Fabrizio
> Cc: freebsd-performance at freebsd.org
> Subject: Re: Strange CPU distributionat very high level bandwidth
>
> Hello,
>
> Just a question. May I ask how many pps is this traffic
> (packet per second). Forward performance actually depends on
> the pps rate and not on the bandwidth usage as far as my
> experience goes. As I've calculated by your given data, it
> might be around 166Kpps, but i might be wrong there.
>
> On Wed, 19 Aug 2009 12:13:37 +0200
> Invernizzi Fabrizio <fabrizio.invernizzi at telecomitalia.it> wrote:
>
> > Hi all
> >
> > i am going on with some performance tests on a 10gbe
> network card with
> > FreeBSD.
> >
> > I am doing this test: I send UDP traffic to be forwarded to
> the other
> > port of the card on both the card ports. Using 1492-long
> packets i am
> > uppering the number  of packets per second i sent In order
> to see wich
> > is the maximum bandwidth (or pps) the system can support without
> > losses.
> >
> > The limit seems to be about 1890Mbps per port (3870 Mbps total).
> > Looking more in deep the CPU behaviour i see this :
> >   - uppering the sent pps results in uppering the intterrupt time
> > (about 90%)
> >   - when i am very strict to the limit, interrupt time
> falls to about
> > 10% and CPU is always (85%) in system (rx/tx driver procedure)
> >
> > Questions:
> > - Is not the AIM intended to contrast this behaviour to limit
> > interrupts sent to CPU? (nothing changes if i disable it)
> > - Why does the system start loosing pkts in that condition?
> > - Why does the system seem to perform better when it is
> managing more
> > context switches?
> >
> >
> >
> > These are my system details:
> >
> > - HP 380 G5 (XEON X5420, CPU speed: 2.50GHz, BUS speed:
> 1333 MHz, L2
> > cache size: 12 MB, L2 cache speed: 2,5 GHz) with 1 quad-core
> > installed.
> >
> > - Network card: Silicom PE10G2i-LR - Dual Port Fiber (LR)
> 10 Gigabit
> > Ethernet PCI Express Server Adapter Intel(r) based (chip 82598EB).
> >
> > - FreeBSD 7.2-RELEASE (64 bit)
> >
> > Driver ixgbe-1.8.6
> >
> > hw.intr_storm_threshold:2000000
> >
> > dev.ix.0.low_latency: 128
> > dev.ix.0.ave_latency: 400
> > dev.ix.0.bulk_latency: 1200
> > dev.ix.1.low_latency: 128
> > dev.ix.1.ave_latency: 400
> > dev.ix.1.bulk_latency: 1200
> >
> > ------------------------------------------------------------------
> > Telecom Italia
> > Fabrizio INVERNIZZI
> > Technology - TILAB
> > Accesso Fisso e Trasporto
> > Via Reiss Romoli, 274 10148 Torino
> > Tel.  +39 011 2285497
> > Mob. +39 3316001344
> > Fax +39 06 41867287
> >
> > Questo messaggio e i suoi allegati sono indirizzati esclusivamente
> > alle persone indicate. La diffusione, copia o qualsiasi
> altra azione
> > derivante dalla conoscenza di queste informazioni sono
> rigorosamente
> > vietate. Qualora abbiate ricevuto questo documento per errore siete
> > cortesemente pregati di darne immediata comunicazione al
> mittente e di
> > provvedere alla sua distruzione, Grazie.
> >
> > 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
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> >
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> >
> >
>
>
>
> --
> Sincerely,
> Gergely CZUCZY
> Harmless Digital Bt
>
> +36-30-9702963
>

Questo messaggio e i suoi allegati sono indirizzati esclusivamente alle persone indicate. La diffusione, copia o qualsiasi altra azione derivante dalla conoscenza di queste informazioni sono rigorosamente vietate. Qualora abbiate ricevuto questo documento per errore siete cortesemente pregati di darne immediata comunicazione al mittente e di provvedere alla sua distruzione, Grazie.

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.