From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754206AbYHAORm (ORCPT ); Fri, 1 Aug 2008 10:17:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752214AbYHAORf (ORCPT ); Fri, 1 Aug 2008 10:17:35 -0400 Received: from one.firstfloor.org ([213.235.205.2]:37600 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752168AbYHAORe (ORCPT ); Fri, 1 Aug 2008 10:17:34 -0400 Date: Fri, 1 Aug 2008 16:17:43 +0200 From: Andi Kleen To: Ingo Molnar Cc: Jeremy Fitzhardinge , Nick Piggin , Andi Kleen , Linux Kernel Mailing List Subject: Re: [PATCH 2/2] x86: implement multiple queues for smp function call IPIs Message-ID: <20080801141743.GV23938@one.firstfloor.org> References: <488FA8A9.6000005@goop.org> <20080731220825.GD23801@elte.hu> <48923B7A.3020805@goop.org> <20080731224202.GB22426@elte.hu> <4892980A.2010101@goop.org> <20080801090910.GA3282@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080801090910.GA3282@elte.hu> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > So ... how about my original suggestion, to add a (default-off) boot > option that reduces the queues to 1? I.e. lets have something in place > from day 1 on that could be quirk-handler-driven, should the need arise. > "apic=simpleipi" or something like that. > > In a year or two, once this all has proven itself fine on a broad range > of systems, we'll laugh out loud at being so cautious and can remove the > boot option for good ;-) I agree that adding a boot option to turn it off is a good idea (assuming it doesn't take too much code to implement) Adding such paranoid boot options early has saved my ass a few times in the past. Only tricky bit is use if () not "modulo variable", because the if () will be much faster than a division through an arbitary number. -Andi