From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752314Ab2GSWgI (ORCPT ); Thu, 19 Jul 2012 18:36:08 -0400 Received: from toro.web-alm.net ([62.245.132.31]:58452 "EHLO toro.web-alm.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751036Ab2GSWgD (ORCPT ); Thu, 19 Jul 2012 18:36:03 -0400 Message-ID: <500888A6.4080702@osadl.org> Date: Fri, 20 Jul 2012 00:22:30 +0200 From: Carsten Emde Organization: Open Source Automation Development Lab (OSADL) User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.24) Gecko/20111108 Fedora/3.1.16-1.fc14 Thunderbird/3.1.16 MIME-Version: 1.0 To: "Rafael J. Wysocki" CC: Deepthi Dharwar , Len Brown , Kevin Hilman , Thomas Gleixner , LKML , Linux PM mailing list Subject: Re: [PATCH 1/1 v3] Honor state disabling in the cpuidle ladder governor References: <201207192130.20520.rjw@sisk.pl> <20120719203409.398114351@osadl.org> <20120719204338.905308004@osadl.org> <201207192348.06045.rjw@sisk.pl> In-Reply-To: <201207192348.06045.rjw@sisk.pl> Content-Type: text/plain; charset=ISO-8859-2; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/19/2012 11:48 PM, Rafael J. Wysocki wrote: > On Thursday, July 19, 2012, Carsten Emde wrote: >> There are two cpuidle governors ladder and menu. While the ladder >> governor is always available, if CONFIG_CPU_IDLE is selected, the >> menu governor additionally requires CONFIG_NO_HZ. >> >> A particular C state can be disabled by writing to the sysfs file >> /sys/devices/system/cpu/cpuN/cpuidle/stateN/disable, but this mechanism >> is only implemented in the menu governor. Thus, in a system where >> CONFIG_NO_HZ is not selected, the ladder governor becomes default and >> always will walk through all sleep states - irrespective of whether the >> C state was disabled via sysfs or not. The only way to select a specific >> C state was to write the related latency to /dev/cpu_dma_latency and >> keep the file open as long as this setting was required - not very >> practical and not suitable for setting a single core in an SMP system. >> >> With this patch, the ladder governor only will promote to the next >> C state, if it has not been disabled, and it will demote, if the >> current C state was disabled. >> >> Note that the patch does not make the setting of the sysfs variable >> "disable" coherent, i.e. if one is disabling a light state, then all >> deeper states are disabled as well, but the "disable" variable does not >> reflect it. Likewise, if one enables a deep state but a lighter state >> still is disabled, then this has no effect. A related section has been >> added to the documentation. >> >> Signed-off-by: Carsten Emde > > This looks fine to me, but it's too late for v3.6. I can queue it up > for v3.7, though. Yes, please. Thanks, -Carsten.