[Asterisk-biz] Large Asterisk Setup (~500 ConcurrentCalls+Scalability)

[David Mandelstam]

Hi Matt,

I think that the advice may be related more towards processor load than PCI
bus load, which is almost negligible. Zaptel drivers produce at least one
interrupt per millisecond per board, which is minimal if the interrupt
handlers are short. But on a heavily loaded machine doing lots of echo
cancellation, each interrupt can approach 1 millisecond in length. So if
there are interrupts coming from several cards, you can see how you could
get into trouble.

> This runs contrary to the advice that was given to us by a 
> Digium representative, even when we asked about using Intel 
> Dialogic quad-span cards.
> 
> Do Sangoma cards do any on-board processing to decrease PCI 
> bus traffic, such as DSP and codec transcoding?
>
> I am learning as I go and would appreciate it if you could 
> share any information regarding the PCI bus traffic generated 
> by quad-span cards.  
> What are the sources, and how much traffic do they generate 
> per channel?
> 
> In your opinion, why did the Digium representative advise 
> against more than two quad-span cards per machine?  Could the 
> bottleneck actually be induced by CPU interrupts?
> 
> Thank you,
> 
> Matthew Roth
> http://www.voip-info.org/tiki-index.php?page=Running%20Asteris
> k%20on%20Debian
> 
> David Mandelstam wrote:
> 
> >Hi Bill,
> >
> >Of course no one is. But there is utterly no problem running 
> multiple 
> >quad port boards on a PCI bus. The standard PCI has a throughput of 
> >132Mbytes/sec, and each quad board has a total load of 2.1Mbytes/sec 
> >max with full E1. So you can throw quite a lot of boards into a PC 
> >before you start getting close to PCI limits. We have operational 
> >customers using 4 quads per machine, and I have no reason to 
> suppose that is the maximum.
> >
> >Regards,
> >
> >David Mandelstam
> >Sangoma Technologies Corporation
> >email:     dm at sangoma.com
> >web:       www.sangoma.com
> >Tel:       905-474-1990 x 106
> >           800-388-2475 x 106
> >FAX:       905-474-9223
> >
> > 
> >
> >  
> >
> >>From: asterisk-biz-bounces at lists.digium.com
> >>[mailto:asterisk-biz-bounces at lists.digium.com] On Behalf Of William 
> >>Boehlke
> >>Sent: Thursday, April 21, 2005 1:21 PM
> >>To: 'Commercial and Business-Oriented Asterisk Discussion'
> >>Subject: RE: [Asterisk-biz] Large Asterisk Setup (~500 Concurrent 
> >>Calls+Scalability)
> >>
> >>
> >>Who is building motherboards with a dedicated bus for each PCI slot?
> >> 
> >>
> >>-----Original Message-----
> >>From: asterisk-biz-bounces at lists.digium.com
> >>[mailto:asterisk-biz-bounces at lists.digium.com] On Behalf Of 
> Brian West
> >>Sent: Wednesday, April 20, 2005 3:37 PM
> >>To: Commercial and Business-Oriented Asterisk Discussion
> >>Subject: Re: [Asterisk-biz] Large Asterisk Setup (~500 Concurrent 
> >>Calls
> >>+Scalability)
> >>
> >>
> >>On Apr 20, 2005, at 4:20 PM, Matt Roth wrote:
> >>
> >>    
> >>
> >>>Allow me to clarify that statement.  The traffic on the PCI
> >>>      
> >>>
> >>bus to the
> >>    
> >>
> >>>CPU is the bottleneck.  We have sent emails to Digium regarding 
> >>>multiple quad-span cards in a single PC-class machine and they 
> >>>recommended against it for this reason.
> >>>
> >>>      
> >>>
> >>Not if you get a good board with a dedicated bus per PCI slot.
> >>
> >>/b
> >>
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> >>    
> >>
> >
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