Messages in this thread | | | Subject | Re: [RFC][PATCH 18/22] sched: add reclaiming logic to -deadline tasks | From | Raistlin <> | Date | Fri, 12 Nov 2010 19:56:55 +0100 |
| |
On Fri, 2010-11-12 at 17:04 +0100, Peter Zijlstra wrote: > On Fri, 2010-11-12 at 16:36 +0100, Raistlin wrote: > > But at this point I can't avoid asking. That model aims at _pure_ > > hard real-time scheduling *without* resource reservation capabilities, > > provided it deals with temporal overruns by means of a probabilistic > > analysis, right? > > From what I understood from it, its a soft real-time scheduling > algorithm with resource reservation. > Mmm... I've gone through it (again!) quickly, and you're right, it mentions soft real-time, and I agree that for those systems average CET is better than worst CET. However, I'm not sure resource reservation is there... Not in the paper I have at least, but I may be wrong.
> The problem the stochastic execution time model tries to address is the > WCET computation mess, WCET computation is hard and often overly > pessimistic, resulting in under-utilized systems. > I know, and it's very reasonable. The point I'm trying to make is that resource reservation tries to address the very same issue. I am all but against this model, just want to be sure it's not too much in conflict to the other features we have, especially with resource reservation. Especially considering that --if I got the whole thing about this scheduler right-- resource reservation is something we really want, and I think UNC people would agree here, since I heard Bjorn stating this very clear both in Dresden and in Dublin. :-)
BTW, I'm adding them to the Cc, seems fair, and more useful than all this speculation! :-P
Bjorn, Jim, sorry for bothering. If you're interested, this is the very beginning of the whole thread: http://lkml.org/lkml/2010/10/29/67
And these should be from where this specific discussion starts (I hope, the mirror is not updated yet I guess :-( ): http://lkml.org/lkml/2010/10/29/49 http://groups.google.com/group/linux.kernel/msg/1dadeca435631b60
Thanks and Regards, Dario
-- <<This happens because I choose it to happen!>> (Raistlin Majere) ---------------------------------------------------------------------- Dario Faggioli, ReTiS Lab, Scuola Superiore Sant'Anna, Pisa (Italy)
http://blog.linux.it/raistlin / raistlin@ekiga.net / dario.faggioli@jabber.org [unhandled content-type:application/pgp-signature] | |