Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751771AbcCHNKG (ORCPT ); Tue, 8 Mar 2016 08:10:06 -0500 Received: from bombadil.infradead.org ([198.137.202.9]:60950 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750955AbcCHNKD (ORCPT ); Tue, 8 Mar 2016 08:10:03 -0500 Date: Tue, 8 Mar 2016 14:09:56 +0100 From: Peter Zijlstra To: Dietmar Eggemann Cc: Vincent Guittot , "Rafael J. Wysocki" , "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: <20160308130956.GI6375@twins.programming.kicks-ass.net> References: <2495375.dFbdlAZmA6@vostro.rjw.lan> <1842158.0Xhak3Uaac@vostro.rjw.lan> <20160303153817.GO6344@twins.programming.kicks-ass.net> <20160303162829.GB6375@twins.programming.kicks-ass.net> <56D87457.1050600@arm.com> <20160303182624.GU6356@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160303182624.GU6356@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: 583 Lines: 13 On Thu, Mar 03, 2016 at 07:26:24PM +0100, Peter Zijlstra wrote: > On Thu, Mar 03, 2016 at 05:28:55PM +0000, Dietmar Eggemann wrote: > > Wasn't there the problem that this ratio goes to zero if the cpu is idle > > in the old power estimation approach on x86? > > Yeah, there was something funky. So it might have been that when we're nearly idle the hardware runs at low frequency, which under that old code would have resulted in lowering the capacity of that cpu. Which in turn would have resulted in the scheduler moving the little work it had away and it being even more idle.