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

[Adrian Knoth]

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. ;)

-- 
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