On Thu, Feb 28, 2013 at 8:50 AM, Peter P. <p8rpp@aol.com> wrote:
* Paul Davis <paul@linuxaudiosystems.com> [2013-02-28 14:07]:
> On Thu, Feb 28, 2013 at 5:34 AM, Peter P. <p8rpp@aol.com> wrote:
>
> > Hey list,
> >
> > using jack_capture on an -RT kernel, I see the following message from
> > the program:
> >
> > Warning. Could not set higher priority for a SCHED_FIFO process using
> > setpriority().
> >
> > How could I set this higher priority?
> >
>
> http://jackaudio.org/faq

Thanks Paul!
If I consider this to be the documents you had in mind
http://jackaudio.org/realtime_vs_realtime_kernel
http://jackaudio.org/linux_rt_config
http://jackaudio.org/linux_group_sched

correct.

I can already start Jack using RT-Scheduling. At least this is
what I assume, as the RT Icon flashes slowly on/off in the qjackctl
GUI, and the messages window says
"JACK server starting in realtime mode with priority 10"
"ulimit -l" says:
        unlimited

then the problem is that jack_capture is asking for an even higher priority than your system is configured to allow. 
 
Or did you imply that I should not run an RT-kernel?

i would hope that the first URL you mention above would provide a clear answer to that question.