[LAU] unable to set scheduling priority with rt kernel

[Chuckk Hubbard]

On 10/30/07, Lars Luthman <lars.luthman at gmail.com> wrote:
>
> On Mon, 2007-10-29 at 23:54 +0200, Chuckk Hubbard wrote:
> > On 10/29/07, Florian Schmidt <mista.tapas at gmx.net> wrote:
> >         On Monday 29 October 2007, Chuckk Hubbard wrote:
> >         > On 10/25/07, Florian Schmidt <mista.tapas at gmx.net> wrote:
> >         > > Well, if chrt works now without sudo, try running
> >         > >
> >         > > jackd -R -P 70 -d alsa ...
> >         > >
> >         > > again. It should work now, too..
> >         >
> >         > Update: I just discovered that running jackd -R -P 70 -dalsa
> >         -P -p256 -n2
> >         > -r44100 as ROOT doesn't even set priority 70.  jackd then
> >         runs as a root
> >         > process with priority 20, according to both chrt and top.
> >         > Apparently my system is not able to run anything higher than
> >         20 priority;
> >         > does this mean my kernel is misconfigured, or might it be
> >         something else?
> >         > -Chuckk
> >
> >         install htop
> >
> >         run it
> >
> >         press f2 [setup]
> >         -> Display Options
> >           -> uncheck "Hide userland threads"
> >           -> uncheck "Hide kernel threads"
> >
> >         Do you see all 4 jack threads now?
> >
> > Woop, there it is.  Thanks.  I see 5 actually, one -71, one -81
> > (watchdog?), and the rest 20.  Running Csound with its --sched=N flag,
> > I also see two csound processes, one of which is -70 and the other 20,
> > no matter what value I put... time to take that up with the Csound
> > list I guess.
>
> With JACK output?
>
> From the Csound manual:
>
> "DO NOT use "--sched" if you are using JACK for audio output. JACK
> controls scheduling for the audio applications connected to it, and also
> tries to run at the highest possible priority. If the "--sched" flag is
> used, Csound and JACK will be competing rather than cooperating,
> resulting in extremely poor performance."


I combed that section carefully, but I missed that part.  I'll request that
someone put it in the description of either -+rtaudio=jack or --sched...
Thanks so much!

-Chuckk


-- 
http://www.badmuthahubbard.com
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