From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754297AbcESLki (ORCPT ); Thu, 19 May 2016 07:40:38 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:49510 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753942AbcESLkh (ORCPT ); Thu, 19 May 2016 07:40:37 -0400 Date: Thu, 19 May 2016 13:40:29 +0200 From: Peter Zijlstra To: "Rafael J. Wysocki" Cc: Shilpasri G Bhat , "Rafael J. Wysocki" , Viresh Kumar , "linux-pm@vger.kernel.org" , Linux Kernel Mailing List , "Gautham R. Shenoy" , shreyas@linux.vnet.ibm.com, akshay.adiga@linux.vnet.ibm.com, linuxppc-dev@ozlabs.org, Steve Muckle Subject: Re: [RFC PATCH] Increase in idle power with schedutil Message-ID: <20160519114029.GW3193@twins.programming.kicks-ass.net> References: <1463576020-18597-1-git-send-email-shilpa.bhat@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 On Wed, May 18, 2016 at 11:11:51PM +0200, Rafael J. Wysocki wrote: > On Wed, May 18, 2016 at 2:53 PM, Shilpasri G Bhat > wrote: > > This patch adds driver callback for fast_switch and below observations > > on schedutil governor are done with this patch. > > > > In POWER8 there is a regression observed with schedutil compared to > > ondemand. With schedutil the frequency is not ramping down and is > > mostly stuck at max frequency during idle . This is because of the > > watchdog timer, an RT task which is fired every 4 seconds which > > results in requesting max frequency. > > Well, yes, that would be problematic. > Right; we need to come up with something for RT tasks; but what happens if you disable the watchdog? This should be entirely doable and might give a better comparison.