Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754498AbZIWHko (ORCPT ); Wed, 23 Sep 2009 03:40:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754305AbZIWHkn (ORCPT ); Wed, 23 Sep 2009 03:40:43 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:60284 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754251AbZIWHkn (ORCPT ); Wed, 23 Sep 2009 03:40:43 -0400 Date: Wed, 23 Sep 2009 09:40:28 +0200 From: Ingo Molnar To: Peter Zijlstra , Cyrill Gorcunov Cc: Frederic Weisbecker , Chris Malley , linux-kernel@vger.kernel.org, Steven Rostedt Subject: Re: perf sched record hangs machine Message-ID: <20090923074028.GA3078@elte.hu> References: <7863dc4c0909221409v7893bfd3o4b590d5951a233ba@mail.gmail.com> <20090922212453.GB6062@nowhere> <1253686585.7695.84.camel@twins> <20090923073253.GA18022@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090923073253.GA18022@elte.hu> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1369 Lines: 44 * Ingo Molnar wrote: > > * Peter Zijlstra wrote: > > > .size default_send_IPI_self, .-default_send_IPI_self > > > > Which seems to suggest that cmove is in __prepare_ICR, but I'm not > > sure how that can cause a page-fault, as that function is rather > > pointer-less. > > > > Did it maybe delay evaluating apic->dest_logical that late, it appear > > to be the first usage of that argument? > > > > Ingo, any ideas? > > Yeah, the problem is: > > [ 0.042445] Local APIC not detected. Using dummy APIC emulation. > > we shouldnt be trying to program the lapic in that case - all ops > should be a NOP, including send-ipi-self. Cyrill? Cyrill, the right fix would be to define a: struct apic apic_none; with dummy functions injected. Set struct apic *apic to _that_, instead of apic_default. This means that if we manage to detect a local APIC, we will set it to apic_default (or some other driver) - but the bootup default will be 'no APIC'. This is a lot cleaner and a lot less error-prone than the direct frobbing of the function pointers. Ingo -- 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/