Re: [linux-audio-user] Realtime not working on Debian testing... why?

From: Glenn Greenfield <mzilikazi@email-addr-hidden>
Date: Wed Nov 15 2006 - 00:56:21 EET

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Julian Hagenauer wrote:
> Hi,
> i am using Debian testing with libpam-modules 0.79-4.
> I added
> @audio - rtprio 99
> @audio - nice -10
> @audio - memlock 250000
> to /etc/security/limits.conf and i am member of the audio-group.
> If i start jack with 'jackd -R -d alsa' it says:
> jackd 0.101.1
> 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.
> loading driver ..
> creating alsa driver ... hw:0|hw:0|1024|2|48000|0|0|nomon|swmeter|-|32bit
> control device hw:0
> configuring for 48000Hz, period = 1024 frames, buffer = 2 periods
> nperiods = 2 for capture
> nperiods = 2 for playback
>
> As you see there no warning about missing realtime-cappabilities, anyhow realtime seems not work, because i got a lot of xruns....
> What i am missing?

I run Debian Sid and realtime works perfectly.
$ apt-cache policy libpam-modules
libpam-modules:
  Installed: 0.79-4
  Candidate: 0.79-4
  Version table:
 *** 0.79-4 0
        500 http://ftp.us.debian.org testing/main Packages
        500 http://ftp.us.debian.org unstable/main Packages

The /etc/security/limits.conf as shipped by Debian does still need to be
edited (as you have already done).

> Do i need other requirements to fullfill to get realtime to work, e.g. special kernel-configuration?
>

Yes - a kernel configured for realtime preemtion.

$ zcat /proc/config.gz |grep PREEMPT_RT
CONFIG_PREEMPT_RT=y

The realtime patcheset is slowly getting incorporated into the main
kernel tree. Not exactly sure what the status of that is at this time.
If you don't want to build your own rt kernel you can get one here:

http://mzilikazix.org

These are even configured for 1000 Hz kernel timer.
$ zcat /proc/config.gz |grep CONFIG_HZ_1000=y
CONFIG_HZ_1000=y

Several flavors to choose from with more on the way.

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Received on Wed Nov 15 04:15:02 2006

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