[ardour-users] ok, spoke too soon... major crash w/ 0.9beta16.1
Fernando Pablo Lopez-Lezcano
nando at ccrma.Stanford.EDU
Tue Jun 8 17:57:25 PDT 2004
On Tue, 2004-06-08 at 17:51, Joe Cooper wrote:
> Fernando Pablo Lopez-Lezcano wrote:
> > 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
> >>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.
> I had no idea ardour inherited the realtime scheduling from Jack (at
> least, I've never run ardour explicitly rt, though I do run jack with
> rt). Good to know.
Not all of ardour, just the audio thread.
> That brings to mind the question: Does one have to explicitly run ardour
> with rt to get realtime scheduling in ardour, and if so, how? Running
> jack with realtime scheduling is documented, but I don't recall ever
> seeing anything about ardour and rt. Perhaps I simply misunderstand how
> tightly jack and ardour are coupled (this is not at all unlikely).
You do not need to do anything in ardour. If Jack is running with
SCHED_FIFO scheduling (realtime scheduling) and the kernel has the
capabilities patch (or for 2.6.x the realcap security module), the audio
threads of Jack clients will be run SCHED_FIFO as well.
More information about the Ardour-Users