Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754648AbZIWIws (ORCPT ); Wed, 23 Sep 2009 04:52:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754601AbZIWIws (ORCPT ); Wed, 23 Sep 2009 04:52:48 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:42246 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754558AbZIWIwr (ORCPT ); Wed, 23 Sep 2009 04:52:47 -0400 Subject: Re: perf sched record hangs machine From: Peter Zijlstra To: Cyrill Gorcunov Cc: Ingo Molnar , Frederic Weisbecker , Chris Malley , linux-kernel@vger.kernel.org, Steven Rostedt In-Reply-To: References: <7863dc4c0909221409v7893bfd3o4b590d5951a233ba@mail.gmail.com> <20090922212453.GB6062@nowhere> <1253686585.7695.84.camel@twins> <20090923073253.GA18022@elte.hu> <20090923074028.GA3078@elte.hu> Content-Type: text/plain Content-Transfer-Encoding: 7bit Date: Wed, 23 Sep 2009 10:52:48 +0200 Message-Id: <1253695968.7695.125.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.26.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2270 Lines: 62 On Wed, 2009-09-23 at 12:48 +0400, Cyrill Gorcunov wrote: > On 9/23/09, Cyrill Gorcunov wrote: > > On 9/23/09, Ingo Molnar wrote: > >> > >> * 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'. > >> > > > > May it wait till evening (i'll back from office and take a look)? > > > >> This is a lot cleaner and a lot less error-prone than the direct > >> frobbing of the function pointers. > >> > >> Ingo > >> > > > > Btw, meanwhile Chris may try to pass lapic boot-option in attempt to > reenable apic via msr registers. Also (iirc) i feel we may be hiding > errors if complete noop apic would be used since i belive we need to > check out under which condition a particular operation is called and > when apic is disabled it's mean we're switched to UP mode and > inter-cpu interrupts are under suspicion too. Will take a look during > ~6 hours ;) Thing is, this is a self-ipi, nothing inter-cpu about it. -- 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/