[PlanetCCRMA] audio breaking and cpu load?

Oded Ben-Tal oded at ccrma.Stanford.EDU
Mon Feb 22 14:54:34 PST 2010

> What do you see if you run "top"? What is eating up cpu? (what is your
> period size in jack?) And what happens when you start your pd patches?
> If the load is getting close to, say, 80%, then any spikes in processing
> will trigger xruns.

I'm starting jack with:
/usr/bin/jackd -R -t10000 -dfirewire -r48000 -p256 -n3 -i2 -o6
(also tried 128 & 512).
I get this error message from jack (but only rarely)
JackEngine::XRun: client = pure_data_0 was not run: state = 2
JackAudioDriver::ProcessAsync Process error

should the delay settings in pd (under audio settings) make any difference 
when it's working with jack or does it take all this from jack?

top shows that it's mainly jack and pd (and Xorg occasionally. I presume 
from the gui) taking cpu time.
Interestingly, sometime things run smoothly - I just ran the patch 'on 
idle' dsp on but no user activity for 3 hours with very few recorded DIO 
errors from pd (last one 9800 seconds ago). But then again, sometimes when 
I run the same patch it's constantly breaking.

I was using the cpuload gnome applet to see what's going on (didn't use 
qjackctl to see if it makes any difference).


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