[PlanetCCRMA] guaranteed deadlock w/ 2.4.20-4.ll.acpi

Marc Heckmann mh@nadir.org
Wed May 14 13:02:01 2003


On Wed, May 14, 2003 at 12:51:37PM -0700, Fernando Pablo Lopez-Lezcano wrote:
> > I am running redhat 8.0 with kernel-2.4.20-4.ll.acpi, jack-0.7.x (tried
> > 0.70.. and the freshly updated 0.71..) and ecasound. Filesystems are all
> > ext3. Even when I run jack without the "-R" switch and as an unpriviliged
> > user, using 2 simultaneous sessions of ecasound to record (ecasound -t:60
> > -i:jack_alsa -G:jack,ecasound_rec1,streaming -o stdout) as root with or
> > without the "-r" switch, my system will deadlock reliably and immeadiatly.
> Is this only happening with ecasound? (and only with two copies running
> at the same time?) Or do you see the problem with other jack software as
> well?

no, I managed to crash it a couple of times before, while using a
arecord and jackrec simultaneously. When that happened, jackrec and
arecord were being run without privilieges, but jackd was running with
the "-R" (realtime) switch

> > It still responds to pings but nothing else. I am running with low-latency
> > on. The system is remote, so it's sort of a pain to test out different
> > configurations.
> Yuck. It sounds like an infinite loop on a SCHED_FIFO process (ie:
> anything interrupt related may work but no processes get to be
> schedulled at all other than the realtime process sucking up all cpu
> cycles). But you mention that it also happens when you run as a normal
> users with no special privileges so that should not be the problem. 

no, something has to be running with priviliges. In the case I
described, jackd was running un-priviliged, but both ecasound sessions
were running as root.

> Of course, as you say, it could also be alsa...

possibly. there is a fix regarding spinlocks that went into alsa CVS on
April 26th. Don't know if that fix made it into 0.9.3 or not. While my
system is UP, doesn't preempt use spinlocks? Does 2.4.20-4.ll.acpi have
preempt enabled?

thanks for you help on this, i appreciate it.