Just for the LP bug number. I guess we now have enough information to
participate in any upcoming discussion. ;)

----- Forwarded message from Ronan Jouchet <ro...@jouchet.fr> -----

Date: Mon, 13 Dec 2010 23:34:21 -0500
From: Ronan Jouchet <ro...@jouchet.fr>
To: ubuntu-studio-de...@lists.ubuntu.com, jack-de...@lists.jackaudio.org,
        Alessio Igor Bogani <abog...@ubuntu.com>
Subject: [Jack-Devel] RT_GROUP_SCHED kernel option makes JACK unusable in
        Ubuntu Natty

Hi Ubuntustudio-devel, Ubuntu-kernel, JACK-devel, Alessio,

After talking with adi in #ffado and las in #jack, it appears that Natty's 
kernel needs adjustment to be usable for audio work. Currently the kernel 
flavors shipped by Ubuntu have the RT_GROUP_SCHED option activated, which 
makes JACK unusable (las put up http://jackaudio.org/linux_group_sched to 
sum up the situation).

*Until this problem is solved, JACK is unusable under Natty*. Las  
mentioned several solutions:
  0. Disabling RT_GROUP_SCHED for all kernels
1. Disabling RT_GROUP_SCHED for the kernel targeting audio users  
(-lowlatency, currently living in abogani's PPA)
2. Set up a cgroup and invoke JACK and every client from a shell script 
that joins the cgroup first
3. Use cgrules.conf to at least put processes into the right group by  
4. Use Ubuntu's specific mechanism to put user tasks into a RT-enabled 

Quoting las: "(1) is the desirable option; (2) would be next and (3) would 
be hard, because it would enforce 'application <foobar> always run in the 
<bazbar> cgroup' which is not really very useful or correct". (0) may also 
be considered since this kernel option is apparently very specialized for 
embedded systems and doesn't make sense for a desktop distro.

Which path should be followed is beyond my knowledge. I just hope this  
discussion will pave the way to a usable audio stack in Natty.

  LP bug: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/690010
  IRC : #jack, #ubuntustudio,  #ubuntustudio-devel
  IRC log of my discussion with las: http://pastebin.com/2yw7aPhr

All the best,

Ronan Jouchet
Jack-Devel mailing list

----- End forwarded message -----

mail: a...@thur.de      http://adi.thur.de      PGP/GPG: key via keyserver

pkg-multimedia-maintainers mailing list

Reply via email to