[asterisk-dev] Asterisk scalability

[Johansson Olle E]

17 feb 2009 kl. 13.10 skrev Benny Amorsen:

> Johansson Olle E <oej at edvina.net> writes:
>
>> With SIP (for some reason, I did not test IAX2 ;-) ) we clearly see
>> that the system dies around 1600 simultaneous channels being trashed
>> by all the RTP traffic using the p2p rtp bridge. irqbalance fails
>> miserably at that point and lack of call quality makes all calls
>> sound like the Swedish chef. Unusable is a good description.
>
>> My conclusion so far is the same as Stephen Uhler's at the Atlanta
>> Astridevcon - the IP stack is our problem here.
>
> The IP stack itself can only do so much here... At 1600 simultaneous
> calls and 20ms packets, that is 80000pps. The ethernet card will do
> interrupt mitigation at that point, but AFAIK no ethernet card has any
> kind of UDP receive offload.
>
> If you have as many ethernet cards as CPU cores, and you balance the
> traffic across the cards, you should in theory get almost perfect
> scaling with number of cores (unless Asterisk has problems, but they
> can be fixed). If you only have one ethernet card, you
> will never go beyond single-core performance -- unless the card does
> multiqueue receive, but that is very new so that probably wasn't in
> use for your test.
>
I'm not a hardware engineer, so here's a stupid question:

If those cards are all on the same PCI bus - do we have the bandwidth
and capacity on that bus?

/O