From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755117AbZFVIS4 (ORCPT ); Mon, 22 Jun 2009 04:18:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752770AbZFVISt (ORCPT ); Mon, 22 Jun 2009 04:18:49 -0400 Received: from one.firstfloor.org ([213.235.205.2]:48513 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752168AbZFVISs (ORCPT ); Mon, 22 Jun 2009 04:18:48 -0400 To: David Miller Cc: linux-kernel@vger.kernel.org, sparclinux@vger.kernel.org Subject: Re: NMI watchdog + NOHZ question From: Andi Kleen References: <20090622.002722.53993293.davem@davemloft.net> Date: Mon, 22 Jun 2009 10:18:50 +0200 In-Reply-To: <20090622.002722.53993293.davem@davemloft.net> (David Miller's message of "Mon, 22 Jun 2009 00:27:22 -0700 (PDT)") Message-ID: <87bpog3clx.fsf@basil.nowhere.org> User-Agent: Gnus/5.1008 (Gnus v5.10.8) Emacs/22.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org David Miller writes: > > Is there something fundamental that should be preventing this? Unless that changed recently when I wasn't looking NOHZ should only stop timers when the CPU is idle. So when a driver is doing something and the interrupts are not disabled for too long the timers should be ticking. Then when you're idle interrupts should be never off, so the NMI watchdog cannot fire. On x86 often the NMI watchdog is in fact stopped on idle. -Andi -- ak@linux.intel.com -- Speaking for myself only.