RT_GROUP_SCHED kernel option makes JACK and Rtkit unusable in Ubuntu Natty
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://
*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 default
4. Use Ubuntu's specific mechanism to put user tasks into a RT-enabled cgroup
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.
IRC resources: #jack, #ubuntustudio, #ubuntustudio-
|David Henningsson (diwic) wrote : Re: [Jack-Devel] [PATCH] [cgroups] add basic support to move jack client threads into the same cgroup as jackd||#7|
|Changed in linux (Ubuntu):|
|status:||Fix Committed → Fix Released|