[linux-audio-user] Ingo's RT patch: please tell this newbie the best jack settings

I. I. Ooisen ii001001 at yahoo.ca
Fri Nov 11 10:29:34 EST 2005


On Friday 11 November 2005 09:13 am, Florian Schmidt wrote:

would this help my jackd run more smoothly? (now i have lots of interruptions 
while playing midis)

> On Thu, 10 Nov 2005 20:03:59 -0800
>
> Mark Knecht <markknecht at gmail.com> wrote:
> > jackd -R -p 64 -d alsa -r 44100 -p 64 -n2 -d hw:1,0
>
> jackd -R -P 70 ...
>
> to set the priority of jackd higher than all soundcard irq handlers
> besides the soundcard irq.
>
> Basically the priority setup should look something like this:
>
> keyboard irq handler   - 99
> rtc irq handler        - 99
> soundcard irq handler  - 98
>
> jackd prio             - 70 (creates watchdog at prio 80 and client
> process() threads at prio 69)
>
> all other irq handlers - around 50 (default)
>
> Basically there's also some problems with the timer irq's on -rt kernels
> (which my rt watchdog suffers from). Usually you would want to set
> softirq-timer and softirq-ktime to high prios, too (so high prio
> sleeping threads preempt low prio running threads when getting woken up.
> Actually this should make sure that the timer interrupt which wakes up
> the high prio thread after its sleep actually gets to run), but this
> doesn't quite work with the kernels i tested (this is the reason why my
> rt_watchdog doesn't work right).
>
> I'll try with newer kernels and ask ingo about it if the problem
> persists. Anyways, this should really only be a problem with midi
> sequencers that are sleep based. When using an irq source for timing
> this problem should go away.
>
> Regards,
> Flo
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