From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754410AbcDKOx2 (ORCPT ); Mon, 11 Apr 2016 10:53:28 -0400 Received: from mail-db3on0059.outbound.protection.outlook.com ([157.55.234.59]:12000 "EHLO emea01-db3-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754186AbcDKOx0 (ORCPT ); Mon, 11 Apr 2016 10:53:26 -0400 Authentication-Results: elte.hu; dkim=none (message not signed) header.d=none;elte.hu; dmarc=none action=none header.from=mellanox.com; Subject: Re: [PATCH 3/3] sched: Optimize !CONFIG_NO_HZ_COMMON cpu load updates To: Frederic Weisbecker , Peter Zijlstra References: <1460077633-23431-1-git-send-email-fweisbec@gmail.com> <1460077633-23431-4-git-send-email-fweisbec@gmail.com> <20160408104821.GM3448@twins.programming.kicks-ass.net> <20160408125521.GC24956@lerouge> <20160408174414.GE1087@worktop> <20160411131814.GA22628@lerouge> CC: LKML , Byungchul Park , Thomas Gleixner , Luiz Capitulino , Christoph Lameter , "Paul E . McKenney" , Mike Galbraith , Rik van Riel , Ingo Molnar From: Chris Metcalf Message-ID: <570BBA4D.1060307@mellanox.com> Date: Mon, 11 Apr 2016 10:53:01 -0400 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.7.2 MIME-Version: 1.0 In-Reply-To: <20160411131814.GA22628@lerouge> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [12.216.194.146] X-ClientProxiedBy: DM3PR13CA0011.namprd13.prod.outlook.com (10.164.193.21) To DB5PR05MB1688.eurprd05.prod.outlook.com (10.165.6.154) X-MS-Office365-Filtering-Correlation-Id: 287e0d6c-e9f8-4328-4c8f-08d3621903a1 X-Microsoft-Exchange-Diagnostics: 1;DB5PR05MB1688;2:MoyngJ/6jhbugIDwHaT8ZLKxm3Q0YtxcRy52UNzvVLpa6NfDUfRsa+VrT/Ua9yY/L3VRt1ILCI2qcbY6CYWmGzkLa0tVZjS1VVaOVeD/5Q1VN/9WvkBDn7ac3fjeeUyK2oA3XvF3gXx8gis6vSSLaYOPRVnVdYOU+MoQVyI/gKy3ZNmB77/FVT5BHG+Jj+Ag;3:WODTmsNa05U+0W8YplMzv/kCrqC0q2Bk2Xoukc46RIzP2S0Qp53cZNDhWBW/RWc5DwOs7DkHhiy92kpLn7Nj8WqCihMEOUKN/H7DtgEQE9GvpLKw9SbOJ65ABmAR1GIg X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:;SRVR:DB5PR05MB1688; X-Microsoft-Exchange-Diagnostics: 1;DB5PR05MB1688;25: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 X-Microsoft-Exchange-Diagnostics: 1;DB5PR05MB1688;20: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;4:ybmARvss3iIroL9pp2zjuVIN8NQkB2c+jpIj1s6rWOQ28KsViaKxPhoRZofl4SvLMTTTp46mHyN1xH70qEWRBj1LgJs8Wk1CfvDjILj5Llw3x3hUP3A+sCX4Mjug41dhsYB/VC9KfPosgk8PWEz9qg4V1IraALSqJv1wOqK7q/ss8ctjDpF1QgcCSYLG2xzjlWSSi7LkKkA8B5165oKE/JvwUh+v+LxRFZ8HW03VeYfZVswq2IE/d4qfatg6BbQ5E9krQm2PhC4xSoZ0dcqblOXO9uTqNp+ew2oeLT0LxMBuQMwAzYIelQyjR7KJJ4oLtjQWLaB3o3g2RTkZt1RAQ6yxI0dOKB4445O1XGI+zDfWlnko/0yC/tul7sWrRgtt X-Microsoft-Antispam-PRVS: X-Exchange-Antispam-Report-Test: UriScan:; X-Exchange-Antispam-Report-CFA-Test: BCL:0;PCL:0;RULEID:(601004)(2401047)(5005006)(8121501046)(10201501046)(3002001);SRVR:DB5PR05MB1688;BCL:0;PCL:0;RULEID:;SRVR:DB5PR05MB1688; X-Forefront-PRVS: 09090B6B69 X-Forefront-Antispam-Report: SFV:NSPM;SFS:(10009020)(4630300001)(979002)(6009001)(6049001)(377454003)(24454002)(50986999)(54356999)(65816999)(87266999)(76176999)(83506001)(5004730100002)(33656002)(59896002)(92566002)(80316001)(230700001)(19580395003)(4326007)(86362001)(42186005)(23746002)(36756003)(50466002)(5001770100001)(4001350100001)(189998001)(65806001)(64126003)(2950100001)(3846002)(47776003)(2906002)(586003)(6116002)(77096005)(81166005)(15975445007)(65956001)(66066001)(1096002)(93886004)(5008740100001)(7059030)(18886065003)(969003)(989001)(999001)(1009001)(1019001);DIR:OUT;SFP:1101;SCL:1;SRVR:DB5PR05MB1688;H:[10.15.7.169];FPR:;SPF:None;MLV:ovrnspm;PTR:InfoNoRecords;LANG:en; X-Microsoft-Exchange-Diagnostics: =?Windows-1252?Q?1;DB5PR05MB1688;23:B4S7rPVL7+syxp/NfQsSKn4nuF0iDowflbc2p?= =?Windows-1252?Q?xMcyyCY9gAPxz8YxvxP1NkoyEj3xaZd4MHGHffT92JkZaTp/32KAGTqJ?= =?Windows-1252?Q?wwlbROKxS1FLb+WkoMntbK0/NWqOCuuWIzcch5gB0TosCpOGyiVRzM7J?= =?Windows-1252?Q?RkrlArmkdRu8aiUi7dzqLOMYDFXs4EMH4VN4cv1HAdf8kiJZtG0/w+N3?= =?Windows-1252?Q?PC0HO02liKXFyzrSl6HGGT35BE258NRhamLOqVrdhlHOveNPbl+oE3lU?= =?Windows-1252?Q?zBLFIwrI+odu0yi51wjq+pjJpX/M4M6wxXUIqcXrhXoSThgAoA8OfvWe?= =?Windows-1252?Q?EHu2f6AAe0YDxrG4uSomwivC5qk6ngLKSMUa40TGQyaDe37pxcA76+U5?= =?Windows-1252?Q?XlQQt6TYvNYxoRcG3DQEZHVW1/sa/UyWIMDHSnEuZMfoBWQfuaCgQjqw?= =?Windows-1252?Q?qan9YqwhFF9QvQIKCW5AMLfgXN0BvatkJ0e5OR5ZKVgpt7Bs7mxUoP/7?= =?Windows-1252?Q?zE0wgubiu2VPVEjx4PwgJdTo+SoyEAAEEoR9ADfIDlcRp17mZlo61weR?= =?Windows-1252?Q?dPhE6kkWlh/m8t+4NcTRgBF+LzMquzPPVhkDmlCrBbad3qeFNUQjIIb1?= =?Windows-1252?Q?BB1jiFEAFCd+F+YiCMPnDuxpcqMTiLbDXfrRxr7HacxD8iZp8Peelh06?= =?Windows-1252?Q?cFkVuUBUc4KNGkRv7J/lR0BH41TFsBICAgAiUulhG+hy5S+dNuDCQ/vR?= =?Windows-1252?Q?rY4aXetlv04P5wY6ZA4xCZr6PM5A2I4UV95pGrdcT8R6gjRcsRSGkSdk?= =?Windows-1252?Q?VLjgoR/cgQJno/T17fSf0K7kk94Pq55BIWkIRYZFGRCY7lp3C3eLlK2M?= =?Windows-1252?Q?FsJGS11X+0wKtXfqJ6vsF4y65G9rMIyNDFSZ/clcczw0NGsiC4J3bZez?= =?Windows-1252?Q?JCincPtV9ua5VQrk1UlYfcip81CFQ39QmPvK/cJZYdk8jb5gedCTB6gT?= =?Windows-1252?Q?iGOtOaBF7gkRkvPv2aI0GD3QpR6kORjN8zeYyaeAuJD0q3o+ew0qDHYD?= =?Windows-1252?Q?B7M6cTnQzBsXJAF/HAefEbS5OeHHpc6HjTYe2LO3cl2huSq2paFDjkny?= =?Windows-1252?Q?QqjpJoB3QvT9rLTexYxmND9boma7FUadu4l2svKEkyPTvF7BGgZDAfpd?= =?Windows-1252?Q?BbpV0m5txUGWEowhM/T/hfJAqzHYYN5Lma/E0kNB1qJ+Sz4ITZs/G2bb?= =?Windows-1252?Q?mvvsumXyNNVgHhM6jVDQKBDLSbOIRlMrco6tN37QMV136vAZ1qQmMtA8?= =?Windows-1252?Q?t1bXvrDU+aMFfBocgYxFoss26ieJ/tmxj5ie/oGpknE+CVXB2KtCOSKG?= =?Windows-1252?Q?PQqSWNP62Qua4OoJXOJ7T93FldFVNd8ag=3D=3D?= X-Microsoft-Exchange-Diagnostics: 1;DB5PR05MB1688;5:aG9ln4aCFAoja8Fq5S17wMx6vcaYbYGBjnChcCRstuuffojczP277pjtM4cFptmiqJP2gnPk1vbqxQFPkcwUN/Y+MAw1Ibpv5s9URFZtS/S5ZvOF/CcUiJkaVJsGL5I7nEnwuhuCDA2ff9Bff0Qo2w==;24:Tjdpj1/zPkqtbZWB+tba5jzf3rHGIkijt59v6Xb23RodbuYmmtMskJLkxBAfXc4bEV2Fx6RIDkPatCCXUDfPbhDTIVOYnwqgGE7f+yLBl+U= SpamDiagnosticOutput: 1:23 SpamDiagnosticMetadata: NSPM X-OriginatorOrg: Mellanox.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 11 Apr 2016 14:53:14.2415 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-Transport-CrossTenantHeadersStamped: DB5PR05MB1688 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/11/2016 9:18 AM, Frederic Weisbecker wrote: > So I tried and it warns about the unused variable tickless_load, so I > would need two scattered ifdeffery in the function: > > @@ -4528,7 +4529,9 @@ decay_load_missed(unsigned long load, unsigned long missed_updates, int idx) > static void cpu_load_update(struct rq *this_rq, unsigned long this_load, > unsigned long pending_updates) > { > +#ifdef CONFIG_NO_HZ_COMMON > unsigned long tickless_load = this_rq->cpu_load[0]; > +#endif Just move the initialization down to the first use, as a regular assignment, and add __maybe_unused to the declaration, and the compiler will then keep quiet (see Documentation/CodingStyle). I have no comment on which of the approaches looks better overall, but I think using __maybe_unused definitely improves this approach. -- Chris Metcalf, Mellanox Technologies http://www.mellanox.com