From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756476AbXD2Nf6 (ORCPT ); Sun, 29 Apr 2007 09:35:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756474AbXD2Nf6 (ORCPT ); Sun, 29 Apr 2007 09:35:58 -0400 Received: from www.osadl.org ([213.239.205.134]:33469 "EHLO mail.tglx.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1756471AbXD2Nfm (ORCPT ); Sun, 29 Apr 2007 09:35:42 -0400 Subject: Re: [patch] CFS scheduler, -v6 From: Thomas Gleixner Reply-To: tglx@linutronix.de To: William Lee Irwin III Cc: Kasper Sandberg , Willy Tarreau , Ingo Molnar , Linus Torvalds , Andrew Morton , Gene Heskett , linux-kernel@vger.kernel.org, Con Kolivas , Nick Piggin , Mike Galbraith , Arjan van de Ven , Peter Williams , caglar@pardus.org.tr, Mark Lord , Zach Carter , buddabrod In-Reply-To: <20070429125522.GB31925@holomorphy.com> References: <20070427115526.GA7699@elte.hu> <1177774551.21279.8.camel@localhost> <1177809512.9756.10.camel@localhost> <20070429053022.GB23638@1wt.eu> <20070429065900.GB32281@elte.hu> <20070429071627.GC23638@1wt.eu> <1177842654.5791.85.camel@localhost.localdomain> <20070429111159.GH23638@1wt.eu> <1177848054.9756.30.camel@localhost> <1177848810.5791.104.camel@localhost.localdomain> <20070429125522.GB31925@holomorphy.com> Content-Type: text/plain Date: Sun, 29 Apr 2007 15:37:47 +0200 Message-Id: <1177853867.5791.120.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.6.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 2007-04-29 at 05:55 -0700, William Lee Irwin III wrote: > You'll also hit the same holes should you attempt to write such a > modularity patch for mainline as opposed to porting current mainline to > the driver API as-given. It takes a bit more work to get something that > actually works for all this, and it borders on disingenuity to > suggest that the scheduler class/driver API as it now stands is > capable of any such thing as porting current mainline, nicksched, or SD > to it without significant code impact to the core scheduler code. I never said, that the current implementation of CFS fits the criteria of modularity, but it is a step in that direction. I'm well aware that there is a bunch of things missing and it has hard coded leftovers, which are related to the current two hard coded policy classes. > So on both these points, I don't see cfs as being adequate as it now > stands for a modular, hierarchical scheduler design. If we want a truly > modular and hierarchical scheduler design, I'd suggest pursuing it > directly and independently of policy, and furthermore considering the > representability of various policies in the scheduling class/driver API > as a test of its adequacy. Ack. I don't worry much whether the CFS policy is better than the SD one. I'm all for a truly modular design. SD and SCHED_FAIR are good proofs for it. tglx