[Asterisk-Users] Processor load spikes

[mattf]

I always keep a terminal window open with "top" running for my asterisk
servers. Since we've had Asterisk in production, for about 9 months, I've
noticed with every platform and every card we've tried that the load average
will be going along at about 0.1 to 0.5 with about 30 channels(15 SIP ->
Zap conversations) going and then at seemingly random times the load average
will jump to over 2.0.

All the while the processor idle never goes below 50%.

Does anyone know what the asterisk process is doing that causes these load
jumps?
(I have determined that initiating new calls or hanging up calls is not a
factor in the timing of these jumps)

Does anyone not experience these load jumps?

This occurs on all hardware platforms that I've tested: P3 non-SMP, P4
non-SMP, P4 SMP, AMD non-SMP and AMD SMP using all available Digium T1
cards: wct410p, 400p and 100p

The only common element is RedHat 9.0 as the OS and the fact the there is no
other large service running on the machines(no web, no DB, no X)

I have tested other resource-intensive applications(like MySQL in a constant
loop of ordered selects of 1 million records) and not seen any other
instances of load spikes on these systems.

I have loaded up the channels on a test server to see what will happen is
the load spikes while it is already at 2.0 and with 100 channels(50 SIP->
Zap conversations) it ran for 4 hours with the load averaging around 2.0(on
non-SMP P4) and then I got a spike and the load went upto 8.0 and the server
crashed. 

I would like to find out why asterisk is doing this just to satisfy my own
curiosity, but if anything can be done about it I could get a lot more out
of the servers I have before having to buy more whenever I need to increase
capacity.


MATT---