[LAU] unable to set scheduling priority with rt kernel

[Dragan Noveski]

Chuckk Hubbard wrote:
> Hallo.
> I posted to the jackit-devel list too, so apologies if you're seeing 
> this again.  No luck there...
>
> jackd version 0.103.0 tmpdir /dev/shm protocol 16
> 2.6.22.1-rt9
> Debian testing
>
> I've just noticed that I am unable to set jackd priority on the 
> command line.  I have a script set up to use "sudo chrt" to change it, 
> but when I comment out that line in the script, jackd runs at 0 with 
> schedule "other".
>
> My script:
> sudo chrt -fp 82 `pidof "IRQ-16"`
> jackd --realtime -P 70 -dalsa -P -p256 -n2 -r44100 &
> sudo chrt -fp 70 `pidof "jackd"`
> chrt -p `pidof "IRQ-16"`
> chrt -p `pidof "jackd"`
> exit
>
> If I comment out the second sudo chrt line, the last line returns:
> pid 5032's current scheduling policy: SCHED_OTHER
> pid 5032's current scheduling priority: 0
> otherwise it is SCHED_FF and 70.
chuckk, i can only try to guess.
perhaps sudo on your system is not allowed to do chrt?
on my system i have the file /etc/sudoers containing this two important 
lines:

root    ALL=(ALL) ALL
nowhiskey       ALL=NOPASSWD: ALL

don't know if it could be the root of the problem, because if so, i 
would expect something like 'operation not permitted' error, but who knows.


cheers,
doc
>
> My kernel has:
> # CONFIG_PREEMPT_NONE is not set
> # CONFIG_PREEMPT_VOLUNTARY is not set
> # CONFIG_PREEMPT_DESKTOP is not set
> CONFIG_PREEMPT_RT=y
> CONFIG_PREEMPT=y
> CONFIG_PREEMPT_SOFTIRQS=y
> CONFIG_PREEMPT_HARDIRQS=y
> CONFIG_PREEMPT_BKL=y
> # CONFIG_CLASSIC_RCU is not set
> CONFIG_PREEMPT_RCU=y
>
> /etc/security/limits.conf has:
> @audio         -     nice         -10
> @audio         -     rtprio         99
> @audio         -     memlock     4000000 (someone on the jack list 
> suggested that my previous value "unlimited" was not recognized, so I 
> stuck this in but no change)
>
> and user "chuckk" is in group "audio".
>
> Lastly, the output from my script when the second sudo chrt line is 
> commented out:
> ------------------------------
> pid 684's current scheduling policy: SCHED_FIFO
> pid 684's current scheduling priority: 82
> jackd 0.103.0
> Copyright 2001-2005 Paul Davis and others.
> jackd comes with ABSOLUTELY NO WARRANTY
> This is free software, and you are welcome to redistribute it
> under certain conditions; see the file COPYING for details
>
> JACK compiled with System V SHM support.
> pid 5132's current scheduling policy: SCHED_OTHER
> pid 5132's current scheduling priority: 0
> loading driver ..
> Enhanced3DNow! detected
> SSE2 detected
> apparent rate = 44100
> creating alsa driver ... hw:0|-|256|2|44100|0|0|nomon
> |swmeter|-|32bit
> control device hw:0
> configuring for 44100Hz, period = 256 frames, buffer = 2 periods
> ALSA: final selected sample format for playback: 32bit little-endian
> ALSA: use 2 periods for playback
>
> --------------------------------------
>
> Any ideas what I may have missed or misconfigured?
>
> Thanks!
> -Chuckk
>
>
> -- 
> http://www.badmuthahubbard.com
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