Re: 2.6.15-rt2 - repeatable xrun - no good data in trace

[Michal Schmidt]

Mark Knecht wrote:
> On 1/8/06, Jan Engelhardt <jengelh@xxxxxxxxxxxxxxx> wrote:
> > > >  I did run across a way that I can create a repeatable xrun on my
> > > > AMD64 machine by burning a CD in k3b while Jack is running.
> > > > Unfortunately I do not see any good trace data in dmesg when I do it.
> > > Maybe your cdrecord is running with realtime priority higher than Jack?
> > > Michal
> > cdrecord does run with SCHED_RR/99 when started with proper privileges.
> Ah, then it's likely that this isn't a real problem and it would be
> expected to cause an xrun?

By running cdrecord with a higher priority than Jack, you're telling the 
system that burning the CD is more important than not getting xruns in Jack.

> Anyway, it seems strange that the trace doesn't show anything. I
> suppose that's because cdrecord just grabs a lot of time at a higher
> priority than Jack and Jack ends up not getting serivces at all for
> 5-10mS?

I guess that's exactly what's happening.

> OK, back to the drawing board about debugging my problems!

Try running cdrecord as a normal user and don't give it SUID root.

Michal
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