Re: [Fwd: Re: [patch] Real-Time Preemption, -RT-2.6.9-mm1-V0.4]

Lee Revell
2004-10-30T17:49:34Z

On Sat, 2004-10-30 at 13:58 +0200, Ingo Molnar wrote:
> * Lee Revell <rlrevell@joe-job.com> wrote:
>
> > Here is the dmesg output. It looks like the problem could be related
> > to jackd's printing from the realtime thread. But, this has to be the
> > kernel's fault on some level, because with an earlier version I get no
> > xruns.
>
> with the earlier version these spinlocks were simply disabling
> preemption, while now they will schedule away on contention. If that tty
> lock is held for a long time by a lowprio task then that could delay the
> highprio thread. We are starting to see priority inversion problems.
> But, the core issue is doing tty printouts - does jackd do that
> periodically, or only as a reaction to an already existing latency?
>

No, this cannot be the whole story, because unless verbose mode is
specified, jackd will only prints anything if there is an xrun. So
there is something else going on.

This _really_ feels like a kernel bug. Are you saying that this could
still be a jackd problem, even though T3 works perfectly with the exact
same jackd binary?

Lee