Change from audio group to something else

[Felipe Sateler]

Hi Kaj,

On Tue, Oct 28, 2014 at 3:07 AM, Kaj Ailomaa <zequence at mousike.me> wrote:
> I think I was able to figure out pretty much all about how the cgroups
> tools and configs work (and what is possible), however, I never got
> realtime scheduling to work Not sure why. Compiled a kernel with
> CONFIG_RT_GROUP_SCHED on (which apparently is turned off nowadays),
> which I believe is necessary.
>
> My goal was to first grant realtime privilege to any user, but only to
> selected processes (like jackd). All seemed to be set up right, but no.
> Wonder if anyone would consider this a security issue.

rtkit seems to do what you are proposing to do. It grants realtime
privileges to selected processes. Although I'm not sure of the
implementation details (ie, how does it determine it can grant or not
the privilege), its description roughly correlates with what you are
trying to accomplish.

Except that...

> Heard that systemd might get in the way somehow, and I do have systemd
> on this machine.

It depends on where were you starting your program, I belive. Please
see this bug[1] and the related links for more details on why systemd
causes problems for realtime services.

As I note in that bug log, I do not know what fiddling is necessary
with cgroups to allow rt privileges. Perhaps with your research you
know what needs to be done?


If you are starting your program as a user, you should be OK though
(according to the systemd realtime page linked in the bug log, but
that page is horribly outdated, as the ControlGroup* directives were
removed).


[1]https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=747568

-- 

Saludos,
Felipe Sateler