asterisk users - Jul 2006 - Running 40 active calls (too much för CPU?)

Hi,

We're running asterisk 1.2.1 on a Dell PowerEdge 600SC (2.4 ghz) server
connected to the PSTN through two E1 pipes to a TE405P. This has been running
just fine for several months...

But yesturday we connected a large number of softphone SIP clients (50) and 25
of these where running simultaneous active calls on the INTERNAL ethernet using
g711 (ulaw). We noticed that the sound was jagged just as if the CPU
couldn't handle 25 calls (?!).

I checked the CPU load and it never went over 55 % and memusage was low too.

Does anyone know what could be the problem? Are there some kind of CPU spikes
that make these cuts in the audio? If so, why on earth can't a 2,4 ghz
processor handle 25 low-quality audio "tracks" on asterisk when I can
run +50 cd-quality audio tracks when producing music?

ANY help and/or comments would be appreciated since this is quite an acute
problem.

Regards,
Jan

jan.sarin@securia.se ha scritto:
>Hi,
>
>We're running asterisk 1.2.1 on a Dell PowerEdge 600SC (2.4 ghz) server
connected to the PSTN through two E1 pipes to a TE405P. This has been running
just fine for several months...
>
>But yesturday we connected a large number of softphone SIP clients (50) and
25 of these where running simultaneous active calls on the INTERNAL ethernet
using g711 (ulaw). We noticed that the sound was jagged just as if the CPU
couldn't handle 25 calls (?!).
>
>I checked the CPU load and it never went over 55 % and memusage was low too.
>  
>
>Does anyone know what could be the problem? Are there some kind of CPU
spikes that make these cuts in the audio? If so, why on earth can't a 2,4
ghz processor handle 25 low-quality audio "tracks" on asterisk when I
can run +50 cd-quality audio tracks when producing music?
>
>ANY help and/or comments would be appreciated since this is quite an acute
problem.
>
>  
>
I think there's something "other" wrong with such an huge usage,
meaning
with other either a misconfiguration or another process running on the 
same machine conflicting with asterisk.
What's the load ? in my experience a load > 2 kills audio quality, I 
started with a system with AGI and mysql on the same dell machine as 
yours, had same problems (but not such an high cpu load).
Now with mysql on a dedicated server, fastagi and dbpooling 50 calls 
gives an average load on the long run of 0.3, with lower bounds of 0.08, 
and the digiums are two TE410P.
Why sometimes 50 calls will do 0.3 and sometimes 0.08 is still a mistery 
to me ...