High system load causing audio loss

I’m running Asterisk on a Dell Poweredge 1950, with dual, dual core xeon processors. It is running Ubuntu 6.06 and Asterisk / Zaptel 1.2.7. There are no other servers running on this machine. All calls are being handled with SIP. It has a public IP address.

The problem is like this. If I get a good number of calls on the system the audio stop playing for periods of time (usually minutes).


I have 48 conference calls running with 2 - 8 people in each call, about 250 - 275 people total. The machine is running around 25 - 30% usage. As I get to the upper limit of these numbers, new calls hear no audio and existing calls no longer hear audio. The really odd part is that it happens in cycles, where I’ll be able to hear audio for a few minutes, then it will be gone for a few minutes.

When I cannot hear any audio, the CPU usage drops to between 1 and 3 percent. However, if I try to do anything through the Asterisk console the commands execute, but the actions are not executed until the next time I can hear audio. If I hang up on enough callers normal behaviour will be restored.

Does anyone have any thoughts on what might be causing this behaviour? At the moment I am stumped. If I have not been detailed enough, please let me know.


this may sound really dumb, but have you tried app_conference as a replacement to meetme?

voip-info.org/wiki/view/Aste … conference

SUPPOSEDLY, it handles higher loads better and doesn’t have some of the random audio issues that meetme does.

it’s fairly easy to download and compile, and you shouldn’t have to do alot of reworking on your dialplan for it to work (mainly change ‘meetme’ to ‘conference’).

if your network and CPU aren’t being maxed out, then i’m guessing it’s the asterisk core or app_meetme itself…so app_conference would be my choice as a possible fix…

also, what codecs are you using? if you’re not using ulaw, keep in mind that the conference bridge will use ulaw and transcode to whatever other formats your endpoints are using, eating up more CPU than is necessary.

we’re using dell 2850’s for our servers, one of which has dual core procs, and our average CPU utilization with just 45 active calls (not conferences but regular calls) is between 20% and 40%. we’re recording every call, which adds some overhead.

'm wondering where you are getting your CPU stats from…that sounds awful low for that many participants, especially when meetme is involved, and since your machine is about the same in horsepower as ours, i’m curious why your load equates to about 1/10th of what ours does…

I’m using the ulaw codec.

The CPU stats were from ‘top’.

My guess on the CPU differences is that the majority of our callers (90%) are connected in listen only mode.