From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932268AbcIBOTP (ORCPT ); Fri, 2 Sep 2016 10:19:15 -0400 Received: from mail-db5eur01on0074.outbound.protection.outlook.com ([104.47.2.74]:61984 "EHLO EUR01-DB5-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932213AbcIBOTA (ORCPT ); Fri, 2 Sep 2016 10:19:00 -0400 Authentication-Results: spf=none (sender IP is ) smtp.mailfrom=cmetcalf@mellanox.com; Subject: Re: [PATCH v15 04/13] task_isolation: add initial support To: Peter Zijlstra References: <1471382376-5443-1-git-send-email-cmetcalf@mellanox.com> <1471382376-5443-5-git-send-email-cmetcalf@mellanox.com> <20160829163352.GV10153@twins.programming.kicks-ass.net> <20160830075854.GZ10153@twins.programming.kicks-ass.net> <20160901100631.GQ10153@twins.programming.kicks-ass.net> CC: Gilad Ben Yossef , Steven Rostedt , Ingo Molnar , Andrew Morton , Rik van Riel , Tejun Heo , Frederic Weisbecker , Thomas Gleixner , "Paul E. McKenney" , Christoph Lameter , Viresh Kumar , Catalin Marinas , Will Deacon , Andy Lutomirski , Michal Hocko , , , , From: Chris Metcalf Message-ID: Date: Fri, 2 Sep 2016 10:03:52 -0400 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.3.0 MIME-Version: 1.0 In-Reply-To: <20160901100631.GQ10153@twins.programming.kicks-ass.net> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [12.216.194.146] X-ClientProxiedBy: SN1PR16CA0033.namprd16.prod.outlook.com (10.169.34.43) To VI1PR0501MB2767.eurprd05.prod.outlook.com (10.172.11.17) X-MS-Office365-Filtering-Correlation-Id: dfffb0cc-ff66-41f7-3b46-08d3d33a00d2 X-Microsoft-Exchange-Diagnostics: 1;VI1PR0501MB2767;2:GcFL0WSEMGHIahrvrqW0JrS9MVxM1fWw5hvA5LUlJDW/pC9BgbF9juPKus8M300gQy+s+fawsMrq0JMDSro0glEldzCq9NbTjdO5Bx+tDUj3Y2UTgw7ChDZ0BqRtxwsBcl8zco8e/kFHsAUYYQSGMrK2So8c/ovZQjMHzGp1tO7ug6Mb3J9Me/jhu2rEPVYX;3:bGeQeZZwA2J1GGSM7Lmf8gCqU1zDaWXqy6r3aZTo+FpcLcMoA3Ddx7BFds1qHi9AWDsYsCAnpixtVCDXcUWFwpCQpLdRYYAdtRWC7EtqsmnOdBKAsk/dQqNGy09tbTVt X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:;SRVR:VI1PR0501MB2767; 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I really don't get this, what are you waiting for? Why is >>> rescheduling making things better. >> We need to wait for the last dyntick to fire before we can return to >> userspace. There are plenty of options as to what we can do in the >> meanwhile. > Why not keep your _TIF_TASK_ISOLATION_FOO flag set and re-enter the > loop? > > I really don't see how setting TIF_NEED_RESCHED is helping anything. Yes, I think I addressed that in an earlier reply to Frederic; and you're right, I don't think TIF_NEED_RESCHED or schedule() are the way to go. https://lkml.kernel.org/g/107bd666-dbcf-7fa5-ff9c-f79358899712@mellanox.com Any thoughts on the question of "just re-enter the loop" vs. schedule_timeout()? -- Chris Metcalf, Mellanox Technologies http://www.mellanox.com