Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752878AbbDCTVT (ORCPT ); Fri, 3 Apr 2015 15:21:19 -0400 Received: from mail-am1on0059.outbound.protection.outlook.com ([157.56.112.59]:33856 "EHLO emea01-am1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752130AbbDCTVS (ORCPT ); Fri, 3 Apr 2015 15:21:18 -0400 Message-ID: <551EE81C.3050605@ezchip.com> Date: Fri, 3 Apr 2015 15:21:00 -0400 From: Chris Metcalf User-Agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 MIME-Version: 1.0 To: Mike Galbraith CC: "Peter Zijlstra (Intel)" , Frederic Weisbecker , "Paul E. McKenney" , "Rafael J. Wysocki" , Martin Schwidefsky , Ingo Molnar , Subject: Re: [PATCH 2/2] nohz: make nohz_full imply isolcpus References: <1428078248-5425-1-git-send-email-cmetcalf@ezchip.com> <1428078248-5425-2-git-send-email-cmetcalf@ezchip.com> <1428084499.3475.40.camel@gmail.com> In-Reply-To: <1428084499.3475.40.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: CO2PR11CA0037.namprd11.prod.outlook.com (10.141.242.175) To AM2PR02MB0772.eurprd02.prod.outlook.com (25.163.146.16) Authentication-Results: vger.kernel.org; dkim=none (message not signed) header.d=none; X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:;SRVR:AM2PR02MB0772; X-Microsoft-Antispam-PRVS: X-Forefront-Antispam-Report: BMV:1;SFV:NSPM;SFS:(10009020)(6009001)(6049001)(377424004)(51704005)(24454002)(377454003)(479174004)(83506001)(110136001)(86362001)(65806001)(66066001)(19580395003)(65956001)(65816999)(54356999)(50986999)(76176999)(23676002)(19580405001)(2950100001)(15975445007)(80316001)(77096005)(36756003)(62966003)(40100003)(92566002)(122386002)(77156002)(46102003)(42186005)(33656002)(1411001)(47776003)(50466002)(87976001)(18886065003);DIR:OUT;SFP:1101;SCL:1;SRVR:AM2PR02MB0772;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:AM2PR02MB0772;BCL:0;PCL:0;RULEID:;SRVR:AM2PR02MB0772; X-Forefront-PRVS: 05352A48BE X-OriginatorOrg: ezchip.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 03 Apr 2015 19:21:13.2804 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM2PR02MB0772 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1132 Lines: 27 On 04/03/2015 02:08 PM, Mike Galbraith wrote: > On Fri, 2015-04-03 at 12:24 -0400, cmetcalf@ezchip.com wrote: >> From: Chris Metcalf >> >> It's not clear that nohz_full is useful without isolcpus also >> set, since otherwise the scheduler has to run periodically to >> try to determine whether to steal work from other cores. >> >> Signed-off-by: Chris Metcalf > Ack! nohz_full= as currently defined makes zero sense when the cpu > set (which should be spelled cpuset) remains connected to the > scheduler. Perturbation of tasks to PREVENT cpu domination is what > the scheduler does for a living. Sprinkling microsecond savers all > over the kernel is pretty silly if you don't shut down the mother lode > of perturbation. Sounds like a thumbs up for this patch, then? :-) -- Chris Metcalf, EZChip Semiconductor http://www.ezchip.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/