From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752439AbdJEVPf (ORCPT ); Thu, 5 Oct 2017 17:15:35 -0400 Received: from mx0b-00010702.pphosted.com ([148.163.158.57]:51340 "EHLO mx0b-00010702.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752022AbdJEVPa (ORCPT ); Thu, 5 Oct 2017 17:15:30 -0400 References: <20171004160820.27754-1-bigeasy@linutronix.de> User-agent: mu4e 0.9.19; emacs 25.2.1 From: Gratian Crisan To: Sebastian Andrzej Siewior Cc: linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org, Gratian Crisan , Piotr Gregor , tglx@linutronix.de, Peter Zijlstra , Steven Rostedt Subject: Re: [PATCH RT] time/hrtimer: Use softirq based wakeups for non-RT threads In-reply-to: <20171004160820.27754-1-bigeasy@linutronix.de> Date: Thu, 05 Oct 2017 16:14:49 -0500 Message-ID: <87d161pa9i.fsf@kerf.amer.corp.natinst.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [130.164.62.165] X-ClientProxiedBy: BN6PR18CA0015.namprd18.prod.outlook.com (2603:10b6:404:121::25) To SN4PR0401MB3600.namprd04.prod.outlook.com (2603:10b6:803:46::31) X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 79399413-2397-4de5-5394-08d50c361f22 X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:(22001)(2017030254152)(2017052603199)(201703131423075)(201703031133081)(201702281549075);SRVR:SN4PR0401MB3600; 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I ran an overnight test (about 30 hours total) on two platforms using cyclictest + hrtimer stress load: configurable number of SCHED_OTHER threads doing random clock_nanosleep() in up to 1 mS intervals. Without this patch the max latency recorded was: * on dual core, Intel Atom E3825 @ 1.33GHz: 107 uS * on dual core, Zynq 7020 @ 667MHz: 261 uS With this patch the max numbers drop to: * on dual core, Intel Atom E3825 @ 1.33GHz: 66 uS * on dual core, Zynq 7020 @ 667MHz: 90 uS The max latency numbers with this patch are in-line with expectations for these platforms. Thank you so much, -Gratian