From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753536Ab1KWP5j (ORCPT ); Wed, 23 Nov 2011 10:57:39 -0500 Received: from merlin.infradead.org ([205.233.59.134]:56933 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751248Ab1KWP5i convert rfc822-to-8bit (ORCPT ); Wed, 23 Nov 2011 10:57:38 -0500 Message-ID: <1322063851.14799.77.camel@twins> Subject: Re: HW perf initialisation as early_initcall From: Peter Zijlstra To: Will Deacon Cc: "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" Date: Wed, 23 Nov 2011 16:57:31 +0100 In-Reply-To: <20111123153016.GQ25848@mudshark.cambridge.arm.com> References: <20111123145658.GM25848@mudshark.cambridge.arm.com> <1322060889.14799.73.camel@twins> <20111123153016.GQ25848@mudshark.cambridge.arm.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT X-Mailer: Evolution 3.2.1- Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2011-11-23 at 15:30 +0000, Will Deacon wrote: > We don't use this on ARM so I'm not familiar with it. > NMI watchdog is basically a perf counter that fires every few seconds and checks if the system is still making progress (much like the regular soft watchdog stuff we have). If it thinks we're stuck it prints stack traces to the console etc.. Handy for if you do dumb stuff like: local_irq_disable(); while (1) ; Which oddly enough seems to happen way too often ;-) Anyway, it all depends on having NMIs in the first place.