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

[Julian Hagenauer]

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

Thank you,
Julian