Kubuntu 10.10 and real-time kernel

[Ralf]

On Sun, 2011-02-27 at 14:38 +0100, Victor henri wrote:
> 
> 
> > Date: Sun, 27 Feb 2011 11:47:24 +0100
> > Subject: Re: Kubuntu 10.10 and real-time kernel
> > From: abogani at ubuntu.com
> > To: ubuntu-studio-users at lists.ubuntu.com
> > 
> > Hi,
> > 
> > 2011/2/26 Hartmut Noack <zettberlin at linuxuse.de>:
> > [...]
> > > Kernel and System-Setup are really important. If a capable
> basic-system is
> > > set up carefully, the desktop-system does not matter much.
> > [...]
> > 
> > I agree, definitely.
> > 
> > Please note that Ubuntu Studio don't offer that level of setup at
> the moment.
> 
> Hello,
> 
> Could you please be more specific on what is missing in Ubuntu Studio
> to get that level of setup?
> 
> This what I know already :
> 
>  - Ubuntu Studio already automatically configure
> the /etc/security/limits.d/audio.conf  by adding the lines :
> 
>          @audio   -  rtprio     95
>          @audio   -  memlock    unlimited

rtprio should be 99 and I bet it is 99, there should be an additional
file:

edubuntu at edubuntu:/home/music/edubuntu$
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
edubuntu at edubuntu:/home/music/edubuntu$
cat /etc/security/limits.d/ubuntustudio-audio-rtprio.conf
# Installed by the ubuntustudio-audio package

@audio   -  rtprio     99
edubuntu at edubuntu:/home/music/edubuntu$
> 
> You just have to add yourself in the 'audio' group manually. 
> 
>   - However, there seem to be a problem if you use a generic kernel in
> Ubuntu 10.10, because in Ubuntu 10.10 the "RT_GROUP-SCHED" option in
> the kernel is activated. As far as I understand, this means that doing
> the previous manipulation (ie configuring
> the /etc/security/limits.d/audio.conf and adding yourself in the audio
> group) won't allow real-time erformance for JAck...

Yes, RT_GROUP-SCHED has to be not set.
> 
> "The RT_GROUP_SCHED option overrides everything that may have been
> configured in limits.conf and makes it very complex for regular users
> to get access to the realtime scheduling that JACK works best with. "
> 
> This comes from Jack-audio-connection-kit FAQ
> http://jackaudio.org/linux_group_sched
> 
> Ok so the only option is to use a precompiled real-time kernel, or a
> preemnt kernel having that RT_GROUP_SCHED option disabled (for example
> in Alessio Bogani's ppa), (or a "home-compiled" kernel, which is what
> i'm doing), or use other solutions like it is said in the jack FAQ
> page I mentioned .

Or even a generic with RT_GROUP-SCHED disabled.
> 
> - The rtirq-init script has to be used;

Not necessarily, it doesn't have much effect, but it can't harm to use
it.
> 
> Is there something else in Ubuntu Studio that has to be set up?

You e.g. can run ALSA MIDI latency test and compare settings, e.g. make
an USB port head of the USB ports by editing rtirq and see if
latency/jitter will decrease etc. ...

Remove any unneeded deamon, AppAmor, Firewalls etc. ...

I didn't do that for 10.10, but remember a DAW isn't a washing machine,
multi-user server or toaster, it's a DAW.
> 
> Thank you very much.
> 
> Victor
> 
> 
> > 
> > Ciao,
> > Alessio
> > 
> > -- 
> > Ubuntu-Studio-users mailing list
> > Ubuntu-Studio-users at lists.ubuntu.com
> > Modify settings or unsubscribe at:
> https://lists.ubuntu.com/mailman/listinfo/ubuntu-studio-users

-- 
Asalaam alikum sisters and brothers of Bikini Bottom,

do the Bob attack today, http://www.wmata.com/rail/schedules.cfm.

Allah is great.

N.S. Al Ineeater