From patchwork Thu Jul 19 20:34:10 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Carsten Emde X-Patchwork-Id: 1218481 Return-Path: X-Original-To: patchwork-linux-pm@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork1.kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by patchwork1.kernel.org (Postfix) with ESMTP id 4A89340074 for ; Thu, 19 Jul 2012 20:50:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751739Ab2GSUuW (ORCPT ); Thu, 19 Jul 2012 16:50:22 -0400 Received: from toro.web-alm.net ([62.245.132.31]:58313 "EHLO toro.web-alm.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751479Ab2GSUuU (ORCPT ); Thu, 19 Jul 2012 16:50:20 -0400 Received: from toro.web-alm.net (localhost.localdomain [127.0.0.1]) by toro.web-alm.net (8.12.11.20060308/8.12.11/Web-Alm-2003112001) with ESMTP id q6JKoBjg002487; Thu, 19 Jul 2012 22:50:11 +0200 Received: from rack3slot8.osadl.org (uucp@localhost) by toro.web-alm.net (8.12.11.20060308/8.12.10/Submit/Web-Alm-2003112001) with bsmtp id q6JKoB4h002471; Thu, 19 Jul 2012 22:50:11 +0200 Received: from rack0slot7.osadl.org (rack0slot7.osadl.org [192.168.255.7]) by rack3slot8.osadl.org (8.13.8/8.13.8/CE-2010120801) with ESMTP id q6JKhdcI011055; Thu, 19 Jul 2012 22:43:39 +0200 Received: from rack0slot7.osadl.org (rack0slot7.osadl.org [127.0.0.1]) by rack0slot7.osadl.org (8.14.5/8.14.5) with ESMTP id q6JKhdfp001685; Thu, 19 Jul 2012 22:43:39 +0200 Received: (from root@localhost) by rack0slot7.osadl.org (8.14.5/8.14.5/Submit) id q6JKhc1H001684; Thu, 19 Jul 2012 22:43:38 +0200 Message-Id: <20120719204338.905308004@osadl.org> User-Agent: quilt/0.51-1 Date: Thu, 19 Jul 2012 22:34:10 +0200 From: Carsten Emde To: Rafael Wysocki Cc: Deepthi Dharwar , Len Brown , Kevin Hilman , Thomas Gleixner , LKML , Linux PM mailing list , Carsten Emde Subject: [PATCH 1/1 v3] Honor state disabling in the cpuidle ladder governor References: <201207192130.20520.rjw@sisk.pl> <201207192042.57935.rjw@sisk.pl> <20120719185212.184458166@osadl.org> <20120719190740.215034590@osadl.org> <20120719203409.398114351@osadl.org> Content-Disposition: inline; filename=drivers-cpuidle-ladder-honor-disabling-with-doc.patch X-Virus-Scanned: ClamAV version 0.94.2, clamav-milter version 0.94.2 on rack3slot8.osadl.org X-Virus-Status: Clean Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org 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 --- Documentation/cpuidle/sysfs.txt | 10 +++++++++- drivers/cpuidle/governors/ladder.c | 4 +++- 2 files changed, 12 insertions(+), 2 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Index: linux-3.4.4-rt14-rc2-64/Documentation/cpuidle/sysfs.txt =================================================================== --- linux-3.4.4-rt14-rc2-64.orig/Documentation/cpuidle/sysfs.txt +++ linux-3.4.4-rt14-rc2-64/Documentation/cpuidle/sysfs.txt @@ -76,9 +76,17 @@ total 0 * desc : Small description about the idle state (string) -* disable : Option to disable this idle state (bool) +* disable : Option to disable this idle state (bool) -> see note below * latency : Latency to exit out of this idle state (in microseconds) * name : Name of the idle state (string) * power : Power consumed while in this idle state (in milliwatts) * time : Total time spent in this idle state (in microseconds) * usage : Number of times this state was entered (count) + +Note: +The behavior and the effect of the disable variable depends on the +implementation of a particular governor. In the ladder governor, for +example, it is not 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. Index: linux-3.4.4-rt14-rc2-64/drivers/cpuidle/governors/ladder.c =================================================================== --- linux-3.4.4-rt14-rc2-64.orig/drivers/cpuidle/governors/ladder.c +++ linux-3.4.4-rt14-rc2-64/drivers/cpuidle/governors/ladder.c @@ -88,6 +88,7 @@ static int ladder_select_state(struct cp /* consider promotion */ if (last_idx < drv->state_count - 1 && + !dev->states_usage[last_idx + 1].disable && last_residency > last_state->threshold.promotion_time && drv->states[last_idx + 1].exit_latency <= latency_req) { last_state->stats.promotion_count++; @@ -100,7 +101,8 @@ static int ladder_select_state(struct cp /* consider demotion */ if (last_idx > CPUIDLE_DRIVER_STATE_START && - drv->states[last_idx].exit_latency > latency_req) { + (dev->states_usage[last_idx].disable || + drv->states[last_idx].exit_latency > latency_req)) { int i; for (i = last_idx - 1; i > CPUIDLE_DRIVER_STATE_START; i--) {