Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756012Ab1BXOSP (ORCPT ); Thu, 24 Feb 2011 09:18:15 -0500 Received: from smtp.nokia.com ([147.243.128.24]:35729 "EHLO mgw-da01.nokia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755892Ab1BXOSM (ORCPT ); Thu, 24 Feb 2011 09:18:12 -0500 From: Tero Kristo To: linux-kernel@vger.kernel.org Subject: [PATCH] cpuidle: menu: fixed wrapping timers at 4.294 seconds Date: Thu, 24 Feb 2011 17:19:23 +0200 Message-Id: <1298560763-441-1-git-send-email-tero.kristo@nokia.com> X-Mailer: git-send-email 1.7.1 X-Nokia-AV: Clean Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1512 Lines: 42 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 --- 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); -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/