From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753597AbbCaScZ (ORCPT ); Tue, 31 Mar 2015 14:32:25 -0400 Received: from mail-db3on0074.outbound.protection.outlook.com ([157.55.234.74]:61248 "EHLO emea01-db3-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752787AbbCaScY (ORCPT ); Tue, 31 Mar 2015 14:32:24 -0400 Message-ID: <551AE82C.7000101@ezchip.com> Date: Tue, 31 Mar 2015 14:32:12 -0400 From: Chris Metcalf User-Agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 MIME-Version: 1.0 To: Mike Galbraith , Don Zickus CC: Andrew Morton , Andrew Jones , chai wen , Ingo Molnar , Ulrich Obergfell , Fabian Frederick , Aaron Tomlin , Ben Zhang , Christoph Lameter , Frederic Weisbecker , Gilad Ben-Yossef , Steven Rostedt , open list Subject: Re: [PATCH] watchdog: nohz: don't run watchdog on nohz_full cores References: <1427741465-15747-1-git-send-email-cmetcalf@ezchip.com> <20150330191245.GO162412@redhat.com> <1427767475.3147.32.camel@gmail.com> In-Reply-To: <1427767475.3147.32.camel@gmail.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [12.216.194.146] X-ClientProxiedBy: BN1PR12CA0034.namprd12.prod.outlook.com (25.160.77.44) To AM3PR02MB0535.eurprd02.prod.outlook.com (25.160.6.141) Authentication-Results: vger.kernel.org; dkim=none (message not signed) header.d=none; X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:;SRVR:AM3PR02MB0535; X-Microsoft-Antispam-PRVS: X-Forefront-Antispam-Report: BMV:1;SFV:NSPM;SFS:(10009020)(6049001)(6009001)(24454002)(479174004)(377454003)(64126003)(66066001)(92566002)(62966003)(86362001)(47776003)(15975445007)(50986999)(87266999)(54356999)(59896002)(23676002)(77156002)(42186005)(65816999)(33656002)(46102003)(77096005)(76176999)(122386002)(87976001)(50466002)(83506001)(36756003)(2950100001)(19580405001)(19580395003)(40100003)(18886065003);DIR:OUT;SFP:1101;SCL:1;SRVR:AM3PR02MB0535;H:[10.7.0.41];FPR:;SPF:None;MLV:sfv;LANG:en; X-Exchange-Antispam-Report-Test: UriScan:; X-Exchange-Antispam-Report-CFA-Test: BCL:0;PCL:0;RULEID:(601004)(5005006)(5002010);SRVR:AM3PR02MB0535;BCL:0;PCL:0;RULEID:;SRVR:AM3PR02MB0535; X-Forefront-PRVS: 0532BF6DC2 X-OriginatorOrg: ezchip.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 31 Mar 2015 18:32:19.9033 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM3PR02MB0535 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/30/2015 10:04 PM, Mike Galbraith wrote: > On Mon, Mar 30, 2015 at 02:51:05PM -0400, cmetcalf@ezchip.com wrote: >> From: Chris Metcalf >> >> Running watchdog can be a helpful debugging feature on regular >> cores, but it's incompatible with nohz_full, since it forces >> regular scheduling events. Accordingly, just exit out immediately >> from any nohz_full core. > Hm, I don't see why this is needed, for debugging/testing you turn it > on, when you set up for critical operation, you turn it off. It can be helpful to keep the watchdog running even in production to help diagnose hard-to-reproduce failures. You just can't have it running on the nohz_full cores. -- Chris Metcalf, EZChip Semiconductor http://www.ezchip.com