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

Matt Mackall
2005-01-12T19:21:39Z

On Tue, Jan 11, 2005 at 09:13:44PM -0500, Paul Davis wrote:
> >And that is a failure of imagination on the part of the JACK
>
> Please be careful with your words. Based on your comments below, it
> appears that you've never read any of the technical docs on it, and
> almost certainly never read the source code.

I thought I made it clear that I didn't even know the name of library.
And I thought I understood from you that you had to do different
start-up per client depending on whether RT was available. Have I
misunderstood you?

> >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.

> 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.

--
Mathematics is the supreme nostalgia of our time.