Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262400AbUCCKNn (ORCPT ); Wed, 3 Mar 2004 05:13:43 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262403AbUCCKNn (ORCPT ); Wed, 3 Mar 2004 05:13:43 -0500 Received: from ns.suse.de ([195.135.220.2]:41617 "EHLO Cantor.suse.de") by vger.kernel.org with ESMTP id S262400AbUCCKNi (ORCPT ); Wed, 3 Mar 2004 05:13:38 -0500 Date: Wed, 3 Mar 2004 11:13:37 +0100 From: Andi Kleen To: Peter Williams Cc: Andi Kleen , linux-kernel@vger.kernel.org, johnl@aurema.com Subject: Re: [RFC][PATCH] O(1) Entitlement Based Scheduler Message-ID: <20040303101336.GC8008@wotan.suse.de> References: <40426E1C.8010806@aurema.com.suse.lists.linux.kernel> <404554D8.5040800@aurema.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <404554D8.5040800@aurema.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2309 Lines: 48 On Wed, Mar 03, 2004 at 02:45:28PM +1100, Peter Williams wrote: > Andi Kleen wrote: > >Peter Williams writes: > > > >One comment on the patches: could you remove the zillions of numerical > >Kconfig > >options and just make them sysctls? I don't think it makes any sense > >to require a reboot to change any of that. And the user is unlikely > >to have much idea yet on what he wants on them while configuring. > > The default initial values should be fine and the default configuration > allows the scheduling tuning parameters (i.e. half life and time slice > ) to be changed on a running system via the /proc file system. > These are mainly there so that different settings can be used with > various benchmarks to determine what are the best settings for various > types of loads. If good default values that work well for a wide > variety of load types can be found as a result of these experiments then > these parameters may be made constants in the code. If not they > probably should be made settable via system calls rather than via /proc > as you suggest. No doubt that there are different settings that make sense for different workloads. But there is no reason one has to recompile to set them - it's much nicer to just run a script at boot time to set them, instead of recompiling/rebooting. This will also make benchmarking much easier, because you can just write a script that sets the various parameters, runs workloads, sets other parameters, runs workload again etc. Requiring a recompile and reboot makes this much harder. Also I suspect most people who are not heavily into scheduling theory will go with the defaults at compile time, so it's important that they already work well. And consider it from the side of a standard distribution: users don't normally recompile their kernels there, so everything that makes sense to be tunable should be settable without recompiling. IMHO CONFIG_* should not be used for anything except for kernel binary size tuning and possible compiler tuning. -Andi - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/