Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751461AbdGQT2B (ORCPT ); Mon, 17 Jul 2017 15:28:01 -0400 Received: from mga07.intel.com ([134.134.136.100]:28007 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751317AbdGQT2A (ORCPT ); Mon, 17 Jul 2017 15:28:00 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.40,375,1496127600"; d="scan'208";a="126162638" Subject: Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods To: Peter Zijlstra , Andi Kleen References: <20170713083649.febfflfl5hafkko5@hirez.programming.kicks-ass.net> <16e12e23-6b28-f174-7c4b-4d719225cd3b@linux.intel.com> <20170713145311.z4zxlyd2dospeoqg@hirez.programming.kicks-ass.net> <4a577bd6-20b1-abb6-2153-f9870f0a721e@linux.intel.com> <20170713182820.sn3fjitnd3mca27p@hirez.programming.kicks-ass.net> <31170ac6-9db1-f0b8-4841-f1661c8ed6e1@linux.intel.com> <20170714153818.pjauqxebxyhs6ljp@hirez.programming.kicks-ass.net> <20170714155356.GH3441@tassilo.jf.intel.com> <20170714160648.tg2u6eo2id6gmnjz@hirez.programming.kicks-ass.net> <20170714162619.GJ3441@tassilo.jf.intel.com> <20170717192309.ubn5muvc3u7htuaw@hirez.programming.kicks-ass.net> Cc: "Li, Aubrey" , Frederic Weisbecker , Christoph Lameter , Aubrey Li , tglx@linutronix.de, len.brown@intel.com, rjw@rjwysocki.net, tim.c.chen@linux.intel.com, paulmck@linux.vnet.ibm.com, yang.zhang.wz@gmail.com, x86@kernel.org, linux-kernel@vger.kernel.org, daniel.lezcano@linaro.org From: Arjan van de Ven Message-ID: <91d02dce-7a3c-371c-a247-55fce1e7124a@linux.intel.com> Date: Mon, 17 Jul 2017 12:27:56 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <20170717192309.ubn5muvc3u7htuaw@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 388 Lines: 9 On 7/17/2017 12:23 PM, Peter Zijlstra wrote: > Now I think the problem is that the current predictor goes for an > average idle duration. This means that we, on average, get it wrong 50% > of the time. For performance that's bad. that's not really what it does; it looks at next tick and then discounts that based on history; (with different discounts for different order of magnitude)