[Asterisk-Users] Interrupt latency problems

[Rich Adamson]

> I'm debugging a TxFax problem whereby the fax transmission fails.  I 
> suspect interrupt latency--some interrupt routine is holding its 
> interrupt too long.  I have all unnecessary services switched off and X 
> is not running when I perform these tests.  Some transmission are 
> successful while others fail at random points.
> 
> I've noticed that after I boot Linux, load zaptel, wcfxo, and wcfxs, and 
> then run System Monitor, the CPU utilization spikes to 60% every 10 
> seconds.  After I remove wcfxs the spikes stop, and system utilization 
> stays at 0%.
> 
> I have two TDM22B cards and get these spikes with either card in the system.
> 
> This is an Athlon-64 3000+ CPU and Fedora Core 2.  zaptel-1.0.2.
> 
> Is there anyone who has a TDM card on a "quiet" system who can run 
> System Monitor and observe CPU utilization?

FYI, I see the same thing on a RHv9 2.2ghz box with a single TDM04b and
no calls being processed. Top indicates 30.6% every 10 seconds.

Stopping * has no impact. Stopping zaptel makes that disappear. Starting
zaptel only (no asterisk) brings it back to 30.6%.