From patchwork Wed Jun 22 09:40:45 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Colin Ian King X-Patchwork-Id: 101424 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from chlorine.canonical.com (chlorine.canonical.com [91.189.94.204]) by ozlabs.org (Postfix) with ESMTP id 25620B6FDE for ; Wed, 22 Jun 2011 19:40:59 +1000 (EST) Received: from localhost ([127.0.0.1] helo=chlorine.canonical.com) by chlorine.canonical.com with esmtp (Exim 4.71) (envelope-from ) id 1QZJvW-0007px-KM; Wed, 22 Jun 2011 09:40:50 +0000 Received: from adelie.canonical.com ([91.189.90.139]) by chlorine.canonical.com with esmtp (Exim 4.71) (envelope-from ) id 1QZJvT-0007p6-7V for kernel-team@lists.ubuntu.com; Wed, 22 Jun 2011 09:40:47 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by adelie.canonical.com with esmtp (Exim 4.71 #1 (Debian)) id 1QZJvT-0000jp-5R for ; Wed, 22 Jun 2011 09:40:47 +0000 Received: from cpc7-craw6-2-0-cust128.croy.cable.virginmedia.com ([94.172.219.129] helo=localhost) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1QZJvT-0004tr-2z for kernel-team@lists.ubuntu.com; Wed, 22 Jun 2011 09:40:47 +0000 From: Colin King To: kernel-team@lists.ubuntu.com Subject: [PATCH 1/1] cpuidle: menu: fixed wrapping timers at 4.294 seconds Date: Wed, 22 Jun 2011 10:40:45 +0100 Message-Id: <1308735645-5298-2-git-send-email-colin.king@canonical.com> X-Mailer: git-send-email 1.7.4.1 In-Reply-To: <1308735645-5298-1-git-send-email-colin.king@canonical.com> References: <1308735645-5298-1-git-send-email-colin.king@canonical.com> X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.13 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: kernel-team-bounces@lists.ubuntu.com Errors-To: kernel-team-bounces@lists.ubuntu.com From: Tero Kristo 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. cc: stable@kernel.org # .32.x through .39.x Signed-off-by: Tero Kristo Signed-off-by: Len Brown Acked-by: Stefan Bader --- drivers/cpuidle/governors/menu.c | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-) diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c index f508690..c47f3d0 100644 --- a/drivers/cpuidle/governors/menu.c +++ b/drivers/cpuidle/governors/menu.c @@ -237,6 +237,7 @@ static int menu_select(struct cpuidle_device *dev) unsigned int power_usage = -1; int i; int multiplier; + struct timespec t; if (data->needs_update) { menu_update(dev); @@ -251,8 +252,9 @@ static int menu_select(struct cpuidle_device *dev) 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);