Re: SCHED_EDF infos

Henrik Austad
2009-05-08T09:11:36Z

On Fri, May 08, 2009 at 11:35:58AM +0900, GeunSik Lim wrote:
> Hi Henlik,

Hi Lim,

First off, to all of you, sorry for my last, very poorly formatted email. I
have now tranceded into the realms of mutt.

> [..]
> I think so.
> How can we approach EDF implementation like Pfair as a generic solution
> for Multicore in Linux?

I am working on an implementation now, and I hope to be able to release a
prototype by the end of next week. I think we can continue the discussion
then based on that.

> > I'm working on SCHED_PFAIR :-) Which is a multicore, ratebased deadline
> > driven global scheduling policy where I use the PD^2 rules to solve
> > tie-breaks. In theory, it can reach 100% utilization on all cores
> > without missing deadlines (but in practice you will only get close to
> > 100% as it is not perfect).

> > [..]
> > I'd suggest getting the scheduler running first, then look at those
> > problems later. If you spend all your time trying to learn the
> > scheduler and design in every little feature you need, you'll never
> > finish in time.

> In fact, I also don't have perfect know how to solve PI in Multicore.
> [...]
> > deadline inversion will be a problem, in fact, whatever you chooose to
> > be the 'key' for picking tasks (priority, niceness, deadlines, wind
> > direction, <whatever>), you can pretty much take that and add a
> > -inversion after it. :)

No, PI is going to be deadly no matter what you do.

Henrik