[Asterisk-Users] IAX2 Vs SIP cpu load

[Colin Anderson]

I use IAX2 quite a bit and I haven't really noticed any difference between
IAX2 and SIP. CPU usage in Asterisk is aggravated by transcoding, changing
one audio format to another, and SIP or IAX2 is simply the protocol used to
carry the audio. Any function of Asterisk will be affected by high system
load; if you have a loadaverage of 3, for example, your box is in trouble
regardless of the protocol used. 

Although this may have changed in the newer 1.2.X series of Asterisk, I
believe that Asterisk does not support SMP from the perspective of
dispatching *internal* processes to different CPU's, instead, *external*
processes such as AGI's are balanced out and dispatched automatically to
different CPU's - but this is a kernel thing. 

It's generally well-known that a "fake" SMP machine such as a HyperThreading
CPU affects Asterisk negatively, and best practice is to disable
HyperThreading. However, "real" SMP machines have no trouble (I use a 4 way
Xeon). It's possible to "pin" a process to a specific CPU, and in fact, I do
this to force Asterisk to it's own CPU, and pin all other processes to a
specific CPU that Asterisk does *not* use:

setasteriskaffinity.sh:

#!/bin/bash
ASTERISKPID=`ps -A | grep -a -A0 "asterisk"`
taskset 0x00000003 -p  ${ASTERISKPID:0:5}

This "pins" Asterisk to CPU # 4 on a 4 way system. Repeat for all other
processes, to different CPU's with the affinity mask:

0x00000000 = CPU 1
0x00000001 = CPU 2
0x00000002 = CPU 3
0x00000003 = CPU 4


-----Original Message-----
From: Jon Schøpzinsky [mailto:jos at detele.dk]
Sent: Tuesday, June 13, 2006 8:14 AM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: [Asterisk-Users] IAX2 Vs SIP cpu load


Hello

Is it correct that IAX2 uses more CPU, than SIP? Also, can it be true that
IAX2 is much more sensitive against high CPU loads?
Also, does Asterisk support and use multiprocessor architectures, such as
Xeon?

 
Regards
Jon


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