From mboxrd@z Thu Jan 1 00:00:00 1970 From: Raistlin Subject: Re: RFC for a new Scheduling policy/class in the Linux-kernel Date: Fri, 17 Jul 2009 02:43:17 +0200 Message-ID: <1247791397.4929.191.camel@Palantir> References: <4A5B61DF.8090101@nortel.com> <1247568455.9086.115.camel@Palantir> <4A5C9ABA.9070909@nortel.com> <1247589099.7500.191.camel@twins> <20090715205503.GA14993@cs.fsu.edu> <4A5E4FDD.7090307@nortel.com> <20090715223400.GF14993@cs.fsu.edu> <8aa016e10907151539t16fb1d7fk3122d77e69ac7de5@mail.gmail.com> <20090715231646.GI14993@cs.fsu.edu> <1247734722.15471.83.camel@twins> Mime-Version: 1.0 Content-Type: multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature"; boundary="=-/hVZGFjHDzKHtQjDG7Mg" Cc: Ted Baker , Dhaval Giani , Chris Friesen , "James H. Anderson" , Douglas Niehaus , Henrik Austad , LKML , Ingo Molnar , Bill Huey , Linux RT , Fabio Checconi , Thomas Gleixner , Noah Watkins , KUSP Google Group , Tommaso Cucinotta , Giuseppe Lipari , Bjoern Brandenburg To: Peter Zijlstra Return-path: Received: from ms01.sssup.it ([193.205.80.99]:42745 "EHLO sssup.it" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S933314AbZGQAnY (ORCPT ); Thu, 16 Jul 2009 20:43:24 -0400 In-Reply-To: <1247734722.15471.83.camel@twins> Sender: linux-rt-users-owner@vger.kernel.org List-ID: --=-/hVZGFjHDzKHtQjDG7Mg Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Thu, 2009-07-16 at 10:58 +0200, Peter Zijlstra wrote: > Now, let me first state that the current code is a hack, and I know its > nowhere near proper. But it was the best I could come up with on a short > notice -- and Fabio is now looking at doing better :-) >=20 If I can say something (more!) there is quite a lot of work in our lab on this stuff, starting from different perspective and aiming at different goals. I've been involved, and continuing being, on sporadic server implementation, EDF implementation in separate scheduling class (with Michael), while Fabio is doing a lot (and a lot better!) work on deadlines in sched-rt. Independently from what concerns priorities or deadlines, the way the global scheduling is implemented, i.e., with distributed ready queues, raises a lot of issues with the implementation of _global_ _hierarchical_ scheduling policies of both kind, EDF and FP. It is being very hard to figure out, and much more to implement, how things should go when you have push, pull, affinity, and so on! :-( I'll be more precise when I have the code ready, but here the question is, do you think the push and pull approach "is there to stay", or is there room, maybe after trials, errors, experiments and exhaustive search for the correct data structure, to migrate to something that would make global scheduling easier? Dario --=20 <> (Raistlin Majere) ---------------------------------------------------------------------- Dario Faggioli, ReTiS Lab, Scuola Superiore Sant'Anna, Pisa (Italy) http://blog.linux.it/raistlin / raistlin@ekiga.net / dario.faggioli@jabber.org --=-/hVZGFjHDzKHtQjDG7Mg Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) iEYEABECAAYFAkpfyR4ACgkQk4XaBE3IOsR3/ACfcQFOsY/OgLPCjhjYUS3wpciQ 2EAAnAwtWbR6ghmdQL7ilK41sLyETf3u =cSQp -----END PGP SIGNATURE----- --=-/hVZGFjHDzKHtQjDG7Mg--