usb audio device --> frequent lockups

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dewdrop_world
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Posts: 36
Joined: Mon Aug 09, 2010 10:17 pm
Location: Guangzhou, China
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usb audio device --> frequent lockups

Post by dewdrop_world »

Okay... here's the story... my rt-kernel system has been running beautifully for the better part of a year. Then I decided to add an m-audio fast track pro (running currently in class compliant mode), which generally works okay EXCEPT when there is a little glitch in the power line. Then jack (1.9.6) xruns...

alsa_driver_xrun_recovery
**** alsa_pcm: xrun of at least 0.074 msecs
15:18:57.798 ALSA connection graph change.
ALSA: prepare error for playback on "hw:1" (File descriptor in bad state)
JackAudioDriver::ProcessSync: read error, skip cycle
15:18:57.881 ALSA connection change.

... and here, if I'm lucky, I can get to a terminal and stop jack with kill -9. Usually I'm not lucky, and the machine locks up completely.

So then I found das-watchdog, installed from the Ubuntu repositories, rebooted, tested with test-rt and... nothing. The watchdog never kicked in. After 15-20 seconds, I had to kill the test process manually (either that or fry some eggs on top of my laptop).

Note that I'm living in China, in a tall apartment building where the power line is probably not all that clean to begin with, and even if it came into the building cleanly, there are too many people tapped into the same line to be sure of a pristine power source.

Anything else I can do short of spending big bucks on a power line conditioner? (I started to look at IRQ priorities, to see if maybe I can reduce the priority of everything except for audio hardware. It's confusing, hardly know where to start.)

Thanks,
James

dewdrop_world
Established Member
Posts: 36
Joined: Mon Aug 09, 2010 10:17 pm
Location: Guangzhou, China
Contact:

Re: usb audio device --> frequent lockups

Post by dewdrop_world »

Actually, hold that thought... I took a deep breath and read over [1] again, then found that the irq handler for usb2 (where lsusb shows the fast track) was actually lower than Jack's priority. Installing the Ubuntu rtirq package seems to have taken care of that -- the USB interrupts now have priority 79 (they were 50 before) and Jack is running at priority 60. Other interrupts are 50 (I was especially checking network interfaces).

I have a feeling this will make some sort of a difference. If it doesn't, I'll write back. Otherwise, no follow-up messages would mean that I'm not still having the issue.

James

[1] http://subversion.ffado.org/wiki/IrqPriorities

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