[asterisk-dev] rtp scalability improvement...

[Mike Taht]

Van Jacobson had a nice talk recently on the subject of making networking
faster on modern architectures. See:

http://lwn.net/Articles/169961/

On 3/19/06, Sergey Kuznetsov <asterisk_biz at deeptown.org> wrote:
>
> Anton wrote:
> > I would say that more than one server is not good, when
> > there is performance issues only. having processing 1000
> > calls/s on fast hardware and good clustering options will
> > bring asterisk to a new usage levels. Industry levels. And
> > possibly Industry would involve it's developers too. In
> > normal case that will lead asterisk to became a monster
> > app, able to do most things needed in telephony :)
> >
> > In the comparisions of price/performace - Asterisk can
> > win... but total luck of H323 support kills any advantages.
> > MVTS costs $3500 per 30 concurent calls (E1) and I would
> > love to replace it with Asterisk even in cost of extra
> > servers. But as I said - there is no H323 in Asterisk.
> >
> > Regards,
> > Anton
> >
>
> Asterisk works with H323 but crappy. I spent some time to marry
> Asterisk/OH323 with
> Cisco Gateway ( not Gatekeeper ). At some moment it starts to work but
> then
> after some time without any interaction it stops to work. It dying in
> Master-Slave determination,
> even if signalling part is went thru, and remote side was alerted.
> And this is happened with both my H323 providers. The same symptoms.
>
> MVTS mostly signaling switch. I don't think they are trans-coding
> anything and passing any traffic.
>
>
> PS: As of number of packets sent thru computer:
>
> 50 packets per second * 400 channels * 2 in/out = 40 000 packets per
> second.
>
> Performance dies not because of system calls, but because 20 000
> interruptions/sec happened at that moment.
> It's named IRQ poisoning. Because IRQ switching is longer that standard
> task switching.
>
> When you switch from task to kernel in most cases you don't have to
> reload MMU, because kernel
> don't care about virtual addresses of task. therefore there is very
> small penalty for that. If you will give real-time
> priviledge - it will improve the performance for Asterisk.
>
> When you do IRQ, in that case it's more complicated. But in Linux you
> can emable NAPI if your card allows it
> and then it can improve the performance.
>
> It works in such a way:
> When first IRQ arrives, IRQ handler disables this IRQ and strarts to
> poll packets within specified quota.
> When it's done, it's re-enables IRQ, and returns back to the task. This
> eliminates IRQ switching overhead and can improve
> the performance and number of channels.
>
>
> All the Best!
> Sergey.
>
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--
Mike Taht
PostCards From the Bleeding Edge
http://the-edge.blogspot.com
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