From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761741AbZBDTAJ (ORCPT ); Wed, 4 Feb 2009 14:00:09 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761404AbZBDStc (ORCPT ); Wed, 4 Feb 2009 13:49:32 -0500 Received: from kroah.org ([198.145.64.141]:32799 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1759583AbZBDStX (ORCPT ); Wed, 4 Feb 2009 13:49:23 -0500 Date: Wed, 4 Feb 2009 10:46:34 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: Justin Forbes , Zwane Mwaikambo , "Theodore Ts'o" , Randy Dunlap , Dave Jones , Chuck Wolber , Chris Wedgwood , Michael Krufky , Chuck Ebbert , Domenico Andreoli , Willy Tarreau , Rodrigo Rubira Branco , Jake Edge , Eugene Teo , torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Len Brown , venkatesh.pallipadi@intel.com, Thomas Renninger Subject: [patch 23/41] cpuidle: Add decaying history logic to menu idle predictor Message-ID: <20090204184634.GX25246@kroah.com> References: <20090204184029.881610776@mini.kroah.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline; filename="cpuidle-add-decaying-history-logic-to-menu-idle-predictor.patch" In-Reply-To: <20090204184539.GA25246@kroah.com> User-Agent: Mutt/1.5.16 (2007-06-09) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.27-stable review patch. If anyone has any objections, please let us know. ------------------ From: Venkatesh Pallipadi commit 816bb611e41be29b476dc16f6297eb551bf4d747 upstream Add decaying history of predicted idle time, instead of using the last early wakeup. This logic helps menu governor do better job of predicting idle time. With this change, we also measured noticable (~8%) power savings on a DP server system with CPUs supporting deep C states, when system was lightly loaded. There was no change to power or perf on other load conditions. Signed-off-by: Venkatesh Pallipadi Signed-off-by: Len Brown Cc: Thomas Renninger Signed-off-by: Greg Kroah-Hartman --- drivers/cpuidle/governors/menu.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) --- a/drivers/cpuidle/governors/menu.c +++ b/drivers/cpuidle/governors/menu.c @@ -15,12 +15,14 @@ #include #define BREAK_FUZZ 4 /* 4 us */ +#define PRED_HISTORY_PCT 50 struct menu_device { int last_state_idx; unsigned int expected_us; unsigned int predicted_us; + unsigned int current_predicted_us; unsigned int last_measured_us; unsigned int elapsed_us; }; @@ -47,6 +49,12 @@ static int menu_select(struct cpuidle_de data->expected_us = (u32) ktime_to_ns(tick_nohz_get_sleep_length()) / 1000; + /* Recalculate predicted_us based on prediction_history_pct */ + data->predicted_us *= PRED_HISTORY_PCT; + data->predicted_us += (100 - PRED_HISTORY_PCT) * + data->current_predicted_us; + data->predicted_us /= 100; + /* find the deepest idle state that satisfies our constraints */ for (i = CPUIDLE_DRIVER_STATE_START + 1; i < dev->state_count; i++) { struct cpuidle_state *s = &dev->states[i]; @@ -97,7 +105,7 @@ static void menu_reflect(struct cpuidle_ measured_us = -1; /* Predict time until next break event */ - data->predicted_us = max(measured_us, data->last_measured_us); + data->current_predicted_us = max(measured_us, data->last_measured_us); if (last_idle_us + BREAK_FUZZ < data->expected_us - target->exit_latency) {