[ardour-users] ok, spoke too soon... major crash w/ 0.9beta16.1

Fernando Pablo Lopez-Lezcano nando at ccrma.Stanford.EDU
Tue Jun 8 17:38:06 PDT 2004

On Tue, 2004-06-08 at 17:03, Joe Cooper wrote:
> derek holzer wrote:
> > Just when I was getting to love it, Ardour froze up and made the machine 
> > totally unresponsive! Couldn't even ssh in to kill the process, had to 
> > reboot.
> It's worth pointing out here that a user level application, like ardour, 
> cannot bring down a system*. 

Any user application running threads with realtime scheduling can bring
down a system. That's the tradeoff of not having xruns...

> Only a system level bug can do that (or 
> hardware failure).  Ardour might tickle the bug, but if your system 
> crashed or froze while running Ardour then the kernel has a bug. 
> Possibly, since presumably you've never seen it outside of Ardour (or 
> you wouldn't be blaming Ardour) it is in the sound card driver you are 
> using.  Jack might also be to blame, since it usually runs with rt 
> priority, needs special privileges, and seems to interact more closely 
> with the kernel than most sound servers (I'm guessing--I don't know 
> where the user/system line is in the alsa/jack stack).

A thread running with realtime scheduling can completely hog the cpu of
a running system if it does not return control (ie: no other process
gets to run ever again). Jack has a watchdog timer designed to prevent
such a thing from happening, I guess it is not perfect. 

-- Fernando

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