Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755936AbcCCQsA (ORCPT ); Thu, 3 Mar 2016 11:48:00 -0500 Received: from casper.infradead.org ([85.118.1.10]:44115 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752052AbcCCQr7 (ORCPT ); Thu, 3 Mar 2016 11:47:59 -0500 Date: Thu, 3 Mar 2016 17:47:51 +0100 From: Peter Zijlstra To: "Rafael J. Wysocki" Cc: Vincent Guittot , "Rafael J. Wysocki" , Linux PM list , Juri Lelli , Steve Muckle , ACPI Devel Maling List , Linux Kernel Mailing List , Srinivas Pandruvada , Viresh Kumar , Michael Turquette Subject: Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data Message-ID: <20160303164751.GD6375@twins.programming.kicks-ass.net> References: <2495375.dFbdlAZmA6@vostro.rjw.lan> <1842158.0Xhak3Uaac@vostro.rjw.lan> <20160303122030.GN6356@twins.programming.kicks-ass.net> <20160303163735.GS6356@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160303163735.GS6356@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 604 Lines: 14 On Thu, Mar 03, 2016 at 05:37:35PM +0100, Peter Zijlstra wrote: > On Thu, Mar 03, 2016 at 05:24:32PM +0100, Rafael J. Wysocki wrote: > > >> f = a * x + b > > If not, then I think it's reasonable to map the middle of the > > available frequency range to x = 0.5 and then we have b = 0 and a = > > (max_freq + min_freq) / 2. > > So I really think that approach falls apart on the low util bits, you > effectively always run above min speed, even if min is already vstly > over provisioned. Ah nevermind, I cannot read. Yes that is worth trying I suppose. But the b=0,a=1 thing seems more natural still.