Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751434AbdGRGoP (ORCPT ); Tue, 18 Jul 2017 02:44:15 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:35574 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751026AbdGRGoO (ORCPT ); Tue, 18 Jul 2017 02:44:14 -0400 Date: Tue, 18 Jul 2017 08:43:53 +0200 (CEST) From: Thomas Gleixner To: Andi Kleen cc: "Li, Aubrey" , Peter Zijlstra , Frederic Weisbecker , Christoph Lameter , Aubrey Li , len.brown@intel.com, rjw@rjwysocki.net, tim.c.chen@linux.intel.com, arjan@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 Subject: Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods In-Reply-To: <20170718044521.GO3441@tassilo.jf.intel.com> Message-ID: References: <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> <34371ef8-b8bc-d2bf-93de-3fccd6beb032@linux.intel.com> <20170718044521.GO3441@tassilo.jf.intel.com> User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 653 Lines: 18 On Mon, 17 Jul 2017, Andi Kleen wrote: > > We need a tradeoff here IMHO. I'll check Daniel's work to understand how/if > > it's better than menu governor. > > I still would like to see how the fast path without the C1 heuristic works. > > Fast pathing is a different concept from a better predictor. IMHO we need > both, but the first is likely lower hanging fruit. Hacking something on the side is always the lower hanging fruit as it avoids solving the hard problems. As Peter said already, that's not going to happen unless there is a real technical reason why the general path cannot be fixed. So far there is no proof for that. Thanks, tglx