[pulseaudio-discuss] Rtkit and PulseAudio rlimit_rttime mismatch

[Lennart Poettering]

On Tue, 01.07.14 09:35, Felipe Sateler (fsateler at debian.org) wrote:

> 
> Hi,
> 
> On Mon, Jun 30, 2014 at 1:29 PM, Lennart Poettering
> <lennart at poettering.net> wrote:
> > On Mon, 30.06.14 11:16, Felipe Sateler (fsateler at debian.org) wrote:
> >
> >>
> >> On Fri, Jun 27, 2014 at 4:37 AM, David Henningsson
> >> <david.henningsson at canonical.com> wrote:
> >> > Hi,
> >> >
> >> > Ricardo just noticed that a bug fixed in rtkit 0.11 causes a mismatch
> >> > between PulseAudio and RtKit.
> >> >
> >> > In short, PulseAudio sets its default RLIMIT_RTTIME to one second, and rtkit
> >> > by default refuses to give realtime priority to anything above 200 ms.
> >> >
> >> > So, should we change rtkit to allow an RLIMIT_RTTIME of one second, or
> >> > modify PulseAudio to have itself killed after 200 ms of rtprio? Opinions?
> >>
> >> Also, how does rtkit interoperate with the newer systemd without
> >> ControlGroup stanzas?
> >>
> >
> > Heya, sorry for not responding to this thread earlier, somehow missed it
> > entirely.
> >
> > The thing with rtkit is a bit messy right now. The rt cgroup hookup in
> > the kernel is a fucked up so far, and it is not clear how or when it
> > will be fixed. Because of this uncertain situation we are not exposing
> > any rt cgroup props in systemd but until that happens rtkit is a bit in
> > an unhappy spot, since without rt privs it cannot do its job.
> 
> To be clear, does that mean that since systemd 205 rtkit is expected
> to not work, and no workaround is available?

Yes, I fear. 

A possible work-around for I should probably do is add in a tmpfiles
snippet that uses "w" to manually assign an rt budget to rtkit cgroup
and the user cgroup. It's a bit of a hack, since it bypasses systemd's
cgroup logic, but I probably should have done this a while ago...

Lennart

-- 
Lennart Poettering, Red Hat