Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756360AbYH1SFR (ORCPT ); Thu, 28 Aug 2008 14:05:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753418AbYH1SFD (ORCPT ); Thu, 28 Aug 2008 14:05:03 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.125]:34349 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751805AbYH1SFC (ORCPT ); Thu, 28 Aug 2008 14:05:02 -0400 Date: Thu, 28 Aug 2008 14:04:59 -0400 (EDT) From: Steven Rostedt X-X-Sender: rostedt@gandalf.stny.rr.com To: Linus Torvalds cc: Nick Piggin , Ingo Molnar , Peter Zijlstra , LKML , Stefani Seibold , Dario Faggioli , Max Krasnyansky , Thomas Gleixner , Andrew Morton Subject: Re: [PATCH 6/6] sched: disabled rt-bandwidth by default In-Reply-To: Message-ID: References: <20080819103301.787700742@chello.nl> <200808290036.35817.nickpiggin@yahoo.com.au> <200808290134.35093.nickpiggin@yahoo.com.au> User-Agent: Alpine 1.10 (DEB 962 2008-03-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1990 Lines: 48 On Thu, 28 Aug 2008, Linus Torvalds wrote: > > > On Thu, 28 Aug 2008, Steven Rostedt wrote: > > > > I've always thought that the policy settings belong in the distro, and the > > kernel should never enforce a policy (by setting this as default, it is > > enforcing a policy, even though an RT user can change it). > > The kernel has always done a certain amount of "default policy". > > What do you think things like "swappiness" etc are? Or things like > oevrcommit settings? They're all policies, and there is always a default > one. So in that sense the kernel always has - and fundamentally _must_ - > set some kind of policy. > > And the default policy should generally be the one that makes sense for > most people. Quite frankly, if it's an issue where all normal distros > would basically be expected to set a value, then that value should _be_ > the default policy, and none of the normal distros should ever need to > worry. > > Whether this case is one such, I dunno. Quite frankly, I don't think it's > even _nearly_ important enough to get this kind of noise. I guess the reason that this is getting so much noise over other default policies, is that this default policy is changing a well known definition: The meaning of FIFO. By making the default policy limit the time an RT task runs, we have, in essence, changed a user API. Applications that expect to be able to run uninterrupted by SCHED_OTHER tasks, will now break. No one is arguing that this new feature is not useful. The argument is, should the kernel set the default policy of an old well known scheduling policy to something different than what is expected? Distros set SE Linux on by default, should the kernel do that too? -- Steve -- 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/