From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932619AbWKMTFv (ORCPT ); Mon, 13 Nov 2006 14:05:51 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755334AbWKMTFv (ORCPT ); Mon, 13 Nov 2006 14:05:51 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:42182 "EHLO mx2.mail.elte.hu") by vger.kernel.org with ESMTP id S1755333AbWKMTFu (ORCPT ); Mon, 13 Nov 2006 14:05:50 -0500 Date: Mon, 13 Nov 2006 20:04:52 +0100 From: Ingo Molnar To: "Siddha, Suresh B" Cc: Andi Kleen , Andrew Morton , linux-kernel@vger.kernel.org, ashok.raj@intel.com Subject: Re: [patch] genapic: optimize & fix APIC mode setup Message-ID: <20061113190452.GA29109@elte.hu> References: <20061111151414.GA32507@elte.hu> <200611131529.46464.ak@suse.de> <20061113150415.GA20321@elte.hu> <200611131710.13285.ak@suse.de> <20061113163216.GA3480@elte.hu> <20061113100352.C17720@unix-os.sc.intel.com> <20061113184255.GA25528@elte.hu> <20061113103051.D17720@unix-os.sc.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20061113103051.D17720@unix-os.sc.intel.com> User-Agent: Mutt/1.4.2.2i X-ELTE-SpamScore: -2.8 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.8 required=5.9 tests=ALL_TRUSTED,AWL,BAYES_50 autolearn=no SpamAssassin version=3.0.3 -3.3 ALL_TRUSTED Did not pass through any untrusted hosts 0.5 BAYES_50 BODY: Bayesian spam probability is 40 to 60% [score: 0.5000] -0.0 AWL AWL: From: address is in the auto white-list X-ELTE-VirusStatus: clean Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Siddha, Suresh B wrote: > On Mon, Nov 13, 2006 at 07:42:56PM +0100, Ingo Molnar wrote: > > * Siddha, Suresh B wrote: > > > Not really. That chipset belongs to a MP platform and with your > > > proposed patch, we will endup using clustered APIC mode and will hit > > > the issue(in the presence of cpu hotplug) mentioned in that URL. > > > > hm, why does it end up in clustered mode? Cluster mode should only > > trigger if the APIC IDs go beyond 16. > > go beyond '8' not 16. With Dual-core+HT these MP platforms will have > 16 logical cpus. yes - then the APIC ids will go beyond 15. > > but i'd be fine with never going into cluster mode, instead always > > using physical flat mode when having more than 8 APICs (independent > > of the presence of CPU hotplug). On small systems, logical flat mode > > is what is the best-tested variant (it's also slightly faster). > > Ok. ok, that's really good. Is there any 'weird' platform that you are aware of that absolutely needs clustered APIC mode (because it has no physical delivery mode or something)? Ingo