From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751821AbXDQHME (ORCPT ); Tue, 17 Apr 2007 03:12:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751861AbXDQHMD (ORCPT ); Tue, 17 Apr 2007 03:12:03 -0400 Received: from cantor.suse.de ([195.135.220.2]:41329 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751856AbXDQHMB (ORCPT ); Tue, 17 Apr 2007 03:12:01 -0400 Date: Tue, 17 Apr 2007 09:11:26 +0200 From: Nick Piggin To: Davide Libenzi Cc: William Lee Irwin III , Peter Williams , Mike Galbraith , Con Kolivas , Ingo Molnar , ck list , Bill Huey , Linux Kernel Mailing List , Linus Torvalds , Andrew Morton , Arjan van de Ven , Thomas Gleixner Subject: Re: [Announce] [patch] Modular Scheduler Core and Completely Fair Scheduler [CFS] Message-ID: <20070417071126.GG1057@wotan.suse.de> References: <200704151327.13589.kernel@kolivas.org> <1176619384.6222.70.camel@Homer.simpson.net> <46240F98.3020800@bigpond.net.au> <1176776941.6222.21.camel@Homer.simpson.net> <20070417034050.GD25513@wotan.suse.de> <46244A52.4000403@bigpond.net.au> <20070417042954.GG25513@wotan.suse.de> <20070417060955.GO8915@holomorphy.com> <20070417061503.GC1057@wotan.suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 16, 2007 at 11:50:03PM -0700, Davide Libenzi wrote: > On Tue, 17 Apr 2007, Nick Piggin wrote: > > > > All things are not equal; they all have different properties. I like > > > > Exactly. So we have to explore those properties and evaluate performance > > (in all meanings of the word). That's only logical. > > I had a quick look at Ingo's code yesterday. Ingo is always smart to > prepare a main dish (feature) with a nice sider (code cleanup) to Linus ;) > And even this code does that pretty nicely. The deadline designs looks > good, although I think the final "key" calculation code will end up quite > different from what it looks now. > I would suggest to thoroughly test all your alternatives before deciding. > Some code and design may look very good and small at the beginning, but > when you start patching it to cover all the dark spots, you effectively > end up with another thing (in both design and code footprint). > About O(1), I never thought it was a must (besides a good marketing > material), and O(log(N)) *may* be just fine (to be verified, of course). To be clear, I'm not saying O(logN) itself is a big problem. Type plot [10:100] x with lines, log(x) with lines, 1 with lines into gnuplot. I was just trying to point out that we need to evalute things. Considering how long we've had this scheduler with its known deficiencies, let's pick a new one wisely.