From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755488Ab1G0Vsa (ORCPT ); Wed, 27 Jul 2011 17:48:30 -0400 Received: from mga03.intel.com ([143.182.124.21]:17376 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754830Ab1G0VsZ (ORCPT ); Wed, 27 Jul 2011 17:48:25 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.67,278,1309762800"; d="scan'208";a="32274613" From: Andi Kleen References: <20110727247.325703029@firstfloor.org> In-Reply-To: <20110727247.325703029@firstfloor.org> To: tero.kristo@nokia.com, len.brown@intel.com, gregkh@suse.de, ak@linux.intel.com, linux-kernel@vger.kernel.org, stable@kernel.org, tim.bird@am.sony.com Subject: [PATCH] [26/99] cpuidle: menu: fixed wrapping timers at 4.294 seconds Message-Id: <20110727214824.C36E82403FF@tassilo.jf.intel.com> Date: Wed, 27 Jul 2011 14:48:24 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.35-longterm review patch. If anyone has any objections, please let me know. ------------------ From: Tero Kristo commit 7467571f4480b273007517b26297c07154c73924 upstream. Cpuidle menu governor is using u32 as a temporary datatype for storing nanosecond values which wrap around at 4.294 seconds. This causes errors in predicted sleep times resulting in higher than should be C state selection and increased power consumption. This also breaks cpuidle state residency statistics. Signed-off-by: Tero Kristo Signed-off-by: Len Brown Signed-off-by: Greg Kroah-Hartman Signed-off-by: Andi Kleen --- drivers/cpuidle/governors/menu.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) Index: linux-2.6.35.y/drivers/cpuidle/governors/menu.c =================================================================== --- linux-2.6.35.y.orig/drivers/cpuidle/governors/menu.c +++ linux-2.6.35.y/drivers/cpuidle/governors/menu.c @@ -236,6 +236,7 @@ static int menu_select(struct cpuidle_de int latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY); int i; int multiplier; + struct timespec t; if (data->needs_update) { menu_update(dev); @@ -250,8 +251,9 @@ static int menu_select(struct cpuidle_de return 0; /* determine the expected residency time, round up */ + t = ktime_to_timespec(tick_nohz_get_sleep_length()); data->expected_us = - DIV_ROUND_UP((u32)ktime_to_ns(tick_nohz_get_sleep_length()), 1000); + t.tv_sec * USEC_PER_SEC + t.tv_nsec / NSEC_PER_USEC; data->bucket = which_bucket(data->expected_us);