Bug#612023: jackd1: Jack1/2 no longer run with Realtime permissions following update

[info at bandshed.net]

Hi Adi,

POSIX stuff is all there:

tester at av5devel:~$ cat /etc/security/limits.d/audio.conf
# Provided by the jackd package.
#
# Changes to this file will be preserved.
#
# If you want to enable/disable realtime permissions, run
#
#    dpkg-reconfigure -p high jackd

@audio   -  rtprio     95
@audio   -  memlock    unlimited
#@audio   -  nice      -19
tester at av5devel:~$

Limits look messed up!

tester at av5devel:~$ ulimit -l -r
max locked memory       (kbytes, -l) 64
real-time priority              (-r) 0
tester at av5devel:~$

I have been using this kernel for a few weeks, and it runs JACK1 fine on
another Squeeze system that has not been upgraded. CGROUPS are enabled but
NOT 'RT_GROUP_SCHED'

Config is attached...

Thanks for your help!
-GLEN




> On Fri, Feb 04, 2011 at 03:19:58PM -0500, Glen MacArthur wrote:
>
> Hi!
>
>> A routine update on 20110204 renders both JACK1 and JACK2 unable to run
>> with
>> Realtime permissions thus rendering both unuseable for low-latency audio
>
> I fear we need more information here.
>
> AFAICS, no real changes regarding priority scheduling have been applied
> upstream. It's even more suspicious that both, jackd1 and jackd2, should
> be affected.
>
> Let's first make sure you have the POSIX prios in place. Can you verify
> /etc/security/limits.d/audio.conf looks more or less like this?
>
> adi at chopin:~$ cat /etc/security/limits.d/audio.conf
> # Provided by the jackd package.
> #
> # Changes to this file will be preserved.
> #
> # If you want to enable/disable realtime permissions, run
> #
> #    dpkg-reconfigure -p high jackd
>
> @audio   -  rtprio     95
> @audio   -  memlock    unlimited
> #@audio   -  nice      -19
>
>
> Next, please verify that those limits are really active:
>
> adi at chopin:~$ ulimit -l -r
> max locked memory       (kbytes, -l) unlimited
> real-time priority              (-r) 95
>
>> sched_get_priority_min(SCHED_RR)        = 1
>> sched_setscheduler(0, SCHED_RR, { 1 })  = -1 EPERM (Operation not
>> permitted)
>
> Here we can see it's even failing with the lowest realtime permission of
> only 1.
>
> I suspect we (you) are facing the CGROUP thing:
>
>    http://jackaudio.org/linux_group_sched
>
> Can you check your kernel config, either via /boot/config-`uname -r` or
> /proc/config.gz, if available?
>
>
> You could also try to boot the stock Debian squeeze kernel, because I
> have no idea about the settings in this kernel:
>
>> Kernel: Linux 2.6.36-liquorix-2.6.36-3.dmz.2-avlinux-default (SMP w/1
>> CPU core; PREEMPT)
>
> Could be everything.
>
>
> Cheers and please report back. ;)
>
> --
> mail: adi at thur.de  	http://adi.thur.de	PGP/GPG: key via keyserver
>
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