Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751282AbdGMIg4 (ORCPT ); Thu, 13 Jul 2017 04:36:56 -0400 Received: from bombadil.infradead.org ([65.50.211.133]:56665 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750947AbdGMIgz (ORCPT ); Thu, 13 Jul 2017 04:36:55 -0400 Date: Thu, 13 Jul 2017 10:36:49 +0200 From: Peter Zijlstra To: Andi Kleen 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, arjan@linux.intel.com, paulmck@linux.vnet.ibm.com, yang.zhang.wz@gmail.com, x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Message-ID: <20170713083649.febfflfl5hafkko5@hirez.programming.kicks-ass.net> References: <20170710144609.GD31832@tassilo.jf.intel.com> <20170710164206.5aon5kelbisxqyxq@hirez.programming.kicks-ass.net> <20170710172705.GA3441@tassilo.jf.intel.com> <20170711094157.5xcwkloxnjehieqv@hirez.programming.kicks-ass.net> <20170711160926.GA18805@lerouge> <20170711163422.etydkhhtgfthpfi5@hirez.programming.kicks-ass.net> <496d4921-5768-cd1e-654b-38630b7d2e13@linux.intel.com> <20170712083410.ualmvnvzoohyami5@hirez.programming.kicks-ass.net> <20170712213240.GE3441@tassilo.jf.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170712213240.GE3441@tassilo.jf.intel.com> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1224 Lines: 29 On Wed, Jul 12, 2017 at 02:32:40PM -0700, Andi Kleen wrote: > On Wed, Jul 12, 2017 at 10:34:10AM +0200, Peter Zijlstra wrote: > > On Wed, Jul 12, 2017 at 12:15:08PM +0800, Li, Aubrey wrote: > > > Okay, the difference is that Mike's patch uses a very simple algorithm to make the decision. > > > > No, the difference is that we don't end up with duplication of a metric > > ton of code. > > What do you mean? There isn't much duplication from the fast path > in Aubrey's patch kit. A whole second idle path is one too many. We're not going to have duplicate idle paths. > It just moves some code around from the cpuidle governor to be generic, > that accounts for the bulk of the changes. It's just moving however, > not adding. It wasn't at first glance evident it was a pure move because he does it over a bunch of patches. Also, that code will not be moved to the generic code, people are working on alternatives and very much rely on this being a governor thing. > > It uses the normal idle path, it just makes the NOHZ enter fail. > > Which is only a small part of the problem. Given the data so far provided it was by far the biggest problem. If you want more things changed, you really have to give more data.