Re: [PATCH] [request for inclusion] Realtime LSM

Lee Revell
2005-01-13T01:10:09Z

On Wed, 2005-01-12 at 11:09 -0800, Matt Mackall wrote:
> On Tue, Jan 11, 2005 at 09:13:44PM -0500, Paul Davis wrote:
> > >A client starts at normal priority, asks jack nicely to promote it to
> > >RT, then jackd, if so configured/enabled, calls the wrapper with a PID
> >
> > a PID? clients are multithreaded, and only specific threads run with
> > RT scheduling (normally just the one created for them by
> > libjack). So you presumably mean a TID, which in turn creates a
> > problem for any system (e.g. 2.4) where all threads share the PID, and
> > sched_setscheduler() really does use the PID as a PID, not a TID.
>
> That actually sounds like an independent API problem.
>

What's your point? It has to work on 2.4, so this is not a feasible
solution.

> > but its gets worse. JACK clients need to drop RT scheduling under
> > certain, well-defined circumstances. how do they get it back under
> > this scheme?
>
> Assuming a more thread-aware API, they just ask for privileges again.
> But with the non-thread-aware API, my first reaction would be the thread in
> question clones, and the clone drops privileges.
>

Clones? Seems pretty inefficient compared to having a simple mechanism
for root to grant users the ability to run RT tasks. We have such a
system now, and it works perfectly, so any solution that makes people
jump through hoops will be rejected.

Lee