[LAU] Realtime, but many xruns when jack is started. Debian Etch

[Nigel Henry]

On Thursday 04 October 2007 18:10, Florian Schmidt wrote:
> On Thursday 04 October 2007, Nigel Henry wrote:
> > > > Ok, you have not done any irq priority tuning.. Try setting the
> > > > IRQ-10 process [your emu10k1] to prio 90..
> > >
> > > I'm not sure what I'm doing here. I presume I need to use chrt to
> > > change the priority, but am not sure of the correct syntax. The current
> > > pid for IRQ10 is 940.
> > >
> > > Could you give me a line that will work for this pid, as the man page
> > > is pretty hopeless with no examples, and about 3 hrs of googling turned
> > > up virtually nothing.
> > >
> > > Many thanks.
> > >
> > > Nigel.
> > >
> > > > Flo
> >
> > Bad to reply to my own post, but I've resolved the problem.
>
> I never quite understood what was supposed to be bad about replying to
> one's own post.. :)

Me neither, but I've seen so many folks saying it, that I said it. That's 2 
times I've said it now, for the first time, and the last time.
>
> > One xrun after 6m 33secs of 0.253 msecs, which is what I'm getting on
> > Fedora 7.
>
> With soundcard irq prio at 90 [not shared with any other device], Jack prio
> at 70 and all other irq prios at default 51?

Yes.
>
> Then it's either an application bug [are you running any applications]? Or
> a bug in the emu10k1 driver. Or in jackd, though i suppose that's rather
> unlikely..
Xawtv is running, and also Gkrellm. Ntpd is getting it's time from the other 
machine, but the 6m 25sec xrun intervals don't match with ntpd's polling. 
Freshclam is running, but I'm not sure how often that checks for updates.

Saying that though, The first xrun occurs about 6m 25secs after starting 
jackd, which is on both Debian Etch, and Fedora 7 on the same machine. If an 
app was responsible for the xruns I'd have thought that the first xrun after 
starting jackd would be logged at xm xsecs, and after that, at 6m 25sec 
intervals. Is an xrun of 0.250 msecs, at 6m 25sec intervals going to be 
noticeable on a piece of music?
>
> > Will that change of priority I've made for the soundcard on the current
> > pid, hold after a reboot?
>
> Nope.. It will be started with the default prio again. Have a look at the
> rtirq script or fiddle your own initscript. Most distros have some "local"
> init script where you put that command..

I'll run your rt-setup-report script on Fedora 7 first I think. I didn't have 
to change soundcard prio's on that. Not sure how to progress from there at 
the moment. Perhaps I'll ask Fernando, and find out whats what, if running 
your script shows a high prio for the soundcard on Fedora 7, with planetccrma 
lowlatency rt kernel, and rtirq installed.
>
> Flo

Thank you for all your help.

Nigel.