From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: nmi_watchdog fix for x86_64 to be more like i386 Date: Mon, 1 Oct 2007 23:41:52 +0200 Message-ID: <200710012341.53169.ak@suse.de> References: <46FA4A800200006C000192FE@sinclair.provo.novell.com> <20071001125626.32eb6d0b@laptopd505.fenrus.org> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Cc: Arjan van de Ven , David Bahi , LKML , linux-rt-users@vger.kernel.org, Andrew Morton , Ingo Molnar , Gregory Haskins To: Thomas Gleixner Return-path: Received: from cantor2.suse.de ([195.135.220.15]:47948 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753175AbXJAVni (ORCPT ); Mon, 1 Oct 2007 17:43:38 -0400 In-Reply-To: Content-Disposition: inline Sender: linux-rt-users-owner@vger.kernel.org List-Id: linux-rt-users.vger.kernel.org > IRQ_NOBALANCING is not preventing cpu unplug. It moves the affinity to the > next CPU, but the check in NMI watchdog for CPU == 0 would not longer > work. That cannot happen right now because cpu_disable() on both i386/x86-64 reject CPU #0. So just setting IRQ_NOBALANCING is sufficient and both do that already. I was wrong earlier in being concerned about this. > int tick_do_broadcast(cpumask_t mask) > @@ -137,6 +147,7 @@ int tick_do_broadcast(cpumask_t mask) > cpu_clear(cpu, mask); > td = &per_cpu(tick_cpu_device, cpu); > td->evtdev->event_handler(td->evtdev); > + tick_broadcast_account(cpu); That would not handle the case with a single CPU running only irq 0 but not broadcasting I think. I believe ftp://ftp.firstfloor.org/pub/ak/x86_64/quilt/patches/fix-watchdog is the correct fix -Andi