[Asterisk-Users] wcfxs causing constant CPU spikes

[Michael Welter]

Jim Van Meggelen wrote:
> 
> There's more to this than that, but my advice would be to not even
> bother until you've built a fresh kernel over the RedHat one. (check out
> the list archives -- you're not the only one with this problem).
> 
> I'm right in the middle of something that may have a huge impact on all
> the IRQ latency issues everyone's been having. Let me know if you're
> interested in using your system as a guinea pig.
> 

I'm running vanilla linux-2.6.9 over Fedora 2/3.  I've replaced a 
GigaByte MB/VIA chipset with an ASUS MB/nVIDIA and still get the spike. 
  I've purchased additional TDM22B boards.  In fact, I've replaced every 
bit of hardware several times over--from mother boards to Digium cards 
to fax machines.  And I've tried both i386 and x86_64 architectures.

I get the spikes with both the TDM22B and T100P cards.  The spikes begin 
when the Digium modules are loaded, and the CPU utilization goes to 
solid 100% idle when the Digium modules are unloaded.

I use 'vmstat 1' to monitor CPU utilization.  The system (not userspace) 
utilization goes to 40% every three seconds.  This spike is usually 
within a one second interval but is sometimes spread across two 
intervals (say 10% system utilization in the first interval, 30% in the 
next interval).  During the one second vmstat interval, the spikes occur 
without a corresponding increase in the number of interrupts, and this 
tells me an interrupt is being held for a very long time--200-400ms.

The end result is that the spandsp transmission is corrupted with 
garbage printed at the fax machine.

I'm really discouraged at Digium's disinterest in this problem.  I 
understand they have limited resources with lots to do, but it only 
takes a minute to reply to my email to say either they are aware or not 
aware of the problem.

Thanks Jim, I'd be interested in assisting.

Mike


-- 
Michael Welter
Introspect Telephony Corp.
Denver, Colorado US
+1.303.674.2575
mike at introspect.com
www.introspect.com