From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932738AbWKMSoZ (ORCPT ); Mon, 13 Nov 2006 13:44:25 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755321AbWKMSoZ (ORCPT ); Mon, 13 Nov 2006 13:44:25 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:23199 "EHLO mx2.mail.elte.hu") by vger.kernel.org with ESMTP id S1755320AbWKMSoY (ORCPT ); Mon, 13 Nov 2006 13:44:24 -0500 Date: Mon, 13 Nov 2006 19:42:56 +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: <20061113184255.GA25528@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> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20061113100352.C17720@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: > > for that i'd have to know the bug, and this is the third time i'm > > asking about specifics :-) (The URL that was given in the thread was > > about a chipset bug regarding incompatibility with clustered-APIC > > mode - my patch in fact - because it switches small systems to use > > logical flat mode always - solves that kind of regression too.) > > 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. 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). Ingo