[asterisk-users] Scaling Asterisk: Dual-Core CPUs not yielding gains at high call volumes

[Mark Coccimiglio]

Matthew J. Roth wrote:

>   In fact, it seems that somewhere between 200 and 300 calls, the two 
> servers start to exhibit similar idle times despite one of them having 
> twice as many cores.
>

Sounds like you are running into the hardware limitations of your 
systems PCI or "Front Side Bus" (FSB) and not necessarily an issue of 
asterisk.  In short there is a limited amount of bandwidth on the 
computer's PCI Bus (33 MHz)  and the FSB (100-800MHz).  One thing to 
remember is that ALL cores and data streams need to share the PCI and 
FSB.    Asterisk is very processor and memory intensive.  At the extreme 
level of usage more cores won't help if data is "stuck in the pipe".  So 
the performance planing you described would be expected.

Mark C.