From patchwork Fri Jan 9 09:26:39 2009 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Len Brown X-Patchwork-Id: 1510 Received: from vger.kernel.org (vger.kernel.org [209.132.176.167]) by demeter.kernel.org (8.14.2/8.14.2) with ESMTP id n099NxOB003124 for ; Fri, 9 Jan 2009 01:25:25 -0800 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754888AbZAIJ3G (ORCPT ); Fri, 9 Jan 2009 04:29:06 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754590AbZAIJ3D (ORCPT ); Fri, 9 Jan 2009 04:29:03 -0500 Received: from vms173001pub.verizon.net ([206.46.173.1]:40934 "EHLO vms173001pub.verizon.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753741AbZAIJ23 (ORCPT ); Fri, 9 Jan 2009 04:28:29 -0500 Received: from localhost.localdomain ([96.237.168.40]) by vms173001.mailsrvcs.net (Sun Java System Messaging Server 6.2-6.01 (built Apr 3 2006)) with ESMTPA id <0KD700LFZ6ATLFF7@vms173001.mailsrvcs.net> for linux-acpi@vger.kernel.org; Fri, 09 Jan 2009 03:28:06 -0600 (CST) Received: from localhost.localdomain (d975xbx2 [127.0.0.1]) by localhost.localdomain (8.14.2/8.14.2) with ESMTP id n099S4qV011947; Fri, 09 Jan 2009 04:28:04 -0500 Received: (from lenb@localhost) by localhost.localdomain (8.14.2/8.14.2/Submit) id n099S4eK011946; Fri, 09 Jan 2009 04:28:04 -0500 Date: Fri, 09 Jan 2009 04:26:39 -0500 From: Len Brown Subject: [PATCH 37/94] cpuidle: Add decaying history logic to menu idle predictor In-reply-to: <1231493256-11678-1-git-send-email-lenb@kernel.org> In-reply-to: To: linux-acpi@vger.kernel.org Cc: "Pallipadi, Venkatesh" , Len Brown Message-id: <816bb611e41be29b476dc16f6297eb551bf4d747.1231492609.git.len.brown@intel.com> Organization: Intel Open Source Technology Center X-Mailer: git-send-email 1.6.1.76.gc123b References: <1231493256-11678-1-git-send-email-lenb@kernel.org> References: Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org From: Pallipadi, Venkatesh 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 --- drivers/cpuidle/governors/menu.c | 10 +++++++++- 1 files changed, 9 insertions(+), 1 deletions(-) diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c index 8d7cf3f..f1df59f 100644 --- 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_device *dev) 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_device *dev) 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) {