[LAU] unable to set scheduling priority with rt kernel

[Lars Luthman]

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."


--ll
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