From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756817AbZKWUfA (ORCPT ); Mon, 23 Nov 2009 15:35:00 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756001AbZKWUe7 (ORCPT ); Mon, 23 Nov 2009 15:34:59 -0500 Received: from panacea.frsk.net ([92.243.16.10]:36178 "EHLO panacea.frsk.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755990AbZKWUe6 (ORCPT ); Mon, 23 Nov 2009 15:34:58 -0500 X-Greylist: delayed 1949 seconds by postgrey-1.27 at vger.kernel.org; Mon, 23 Nov 2009 15:34:58 EST From: Henrik Austad To: Peter Zijlstra Date: Mon, 23 Nov 2009 21:02:03 +0100 User-Agent: KMail/1.12.2 (Linux/2.6.31-14-generic; KDE/4.3.2; i686; ; ) Cc: Jon Tore Hafstad , linux-kernel@vger.kernel.org, dhaval.giani@gmail.com, mingo@elte.hu, tglx@linutronix.de, bbb@cs.unc.edu, jmc@cs.unc.edu, Jeff Dike References: <78b8ce680911181211k6c15a976u52186b5849224040@mail.gmail.com> <1258985295.4531.496.camel@laptop> In-Reply-To: <1258985295.4531.496.camel@laptop> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart2781745.HptGoNdTSc"; protocol="application/pgp-signature"; micalg=pgp-sha1 Content-Transfer-Encoding: 7bit Message-Id: <200911232102.07419.henrik@austad.us> X-SA-Exim-Connect-IP: 129.241.93.108 X-SA-Exim-Mail-From: henrik@austad.us Subject: Re: LinSched updated to current linux kernel version X-SA-Exim-Version: 4.2.1 (built Wed, 25 Jun 2008 17:14:11 +0000) X-SA-Exim-Scanned: Yes (on panacea.frsk.net) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --nextPart2781745.HptGoNdTSc Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable On Monday 23. November 2009 15.08.15 Peter Zijlstra wrote: > On Wed, 2009-11-18 at 21:11 +0100, Jon Tore Hafstad wrote: > > Hi all > > > > I wish to inform you about an update of LinSched (The Linux Scheduler > > Simulator([1])) I'm currently working on. > > > > =3D=3D Motivation =3D=3D > > I wished to implement different EDF schedulers to gain a better > > understanding of kernel internals as well as scheduling dynamics. I > > got some feedback from Henrik Austad that LinSched was a tool that > > made implementing a scheduler in to the linux kernel easier, since > > the code compiles in a fraction of the time the kernel does (Yes, I > > know you can pull all sorts of tricks and tweaks in order to speed up > > a kernel compilation), a segfault will be a segfault, and not a kernel > > oops ;),and the full range of debuggers and memory analyzers will be > > available. >=20 > I would have expected people to use UML for this (User-Mode-Linux, not > the draw lots of silly pictures thing). What is the current status of UML - is anyone actually working on that thes= e=20 days? > The main draw-back is that UML doesn't currently support SMP and any > interesting preemption modes, but adding that to UML would help out more > people -- I know the VM (virtual Memory, not the machine thing) people > used to use UML for exactly these reasons, easy gdb, etc.. Well, another drawback of UML is the size. The whole point with LinSched is= to=20 be *lightweight* while still being accurate. By accurate I mean that code=20 written and tested with LinSched should work nearly out of the box when pla= ced=20 in the kernel. LinSched is all about scheduling - nothing else. To be able to compile the= =20 code in a fraction of a second, and then simulate hours worth of computing = (or=20 at least the task-switches) can be *very* useful.=20 IMHO, making it easy to test new scheduling algorithms is a very neat way o= f=20 attracting new kernel/scheduler hackers (as well as testing all sorts of cr= azy=20 algorithms). Just my $0.02 =2D-=20 henrik --nextPart2781745.HptGoNdTSc 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) iEYEABECAAYFAksK6jsACgkQ6k5VT6v45lmn5wCghhXWM8YS29rFJqekE5tPhFQF eyAAn3Vm3ZyolhViOHniSBPRdvBYPhpk =ZY+4 -----END PGP SIGNATURE----- --nextPart2781745.HptGoNdTSc--