[asterisk-dev] Asterisk and multicore processors

[Eric Germann]

I'm specing out a new box to act as a tandem switch.  It will have a TE410P
with 4 x PRI and support IAX connections to four other boxes using
predominantly ilbc and/or gsm.  It also has 3 IAX trunks to Teliax for call
routing also using gsm.  No extensions actually terminate on the tandem,
they're all switched to other boxes (highly distributed).  On the PRI card,
one goes to Embarq, the PSTN and two go to a legacy SX-200 which is being
phased out.  The fourth is a connection to an Adtran TSU-600 channel bank.

Given this is a greenfield spec and we're building it from scratch, I'm
looking at SuperMicro and their motherboards.  Architecturally, I see the
tandem as being CPU bound, if anything.  Backbone is GigE connected to the
server so I/O there isn't an issue and we aren't doing voicemail on it so it
isn't diskbound.  Primarily the load will in in transcoding between the PRI
channels and the IAX channels. We're looking at probably no more than 100
calls simultaneously.  All the remote boxes use the same codec on the
channels, so it doesn't have to transcode for inter box comm's.

How well does asterisk spread itself out over multiple CPU's (aka Cores).
I'm looking at their 2xQuadCore (clovertown) motherboards and was spec'ing
CPU's.  I know this is a religious issue in some circles, but is it better
to have one Quad core as fast as you can buy (4 CPU's) or 2 x Quad core at a
lower speed (8 CPU's).  Obviously, I've got to shoehorn a budget here and
can do 8 for the price of 4 if * will spread itself out.  If transcoding is
threaded and doesn't deadlock for a single resource, it seems 8 cores would
be better than 4.

Thoughts?

Thanks for any input.

Eric