Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754073Ab1DBAH0 (ORCPT ); Fri, 1 Apr 2011 20:07:26 -0400 Received: from vms173007pub.verizon.net ([206.46.173.7]:45135 "EHLO vms173007pub.verizon.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752129Ab1DBAHZ (ORCPT ); Fri, 1 Apr 2011 20:07:25 -0400 Date: Fri, 01 Apr 2011 20:07:04 -0400 (EDT) From: Len Brown X-X-Sender: lenb@x980 To: Tero Kristo Cc: linux-kernel@vger.kernel.org, linux-pm@lists.linux-foundation.org Subject: Re: [PATCH] cpuidle: menu: fixed wrapping timers at 4.294 seconds In-reply-to: <1298560763-441-1-git-send-email-tero.kristo@nokia.com> Message-id: References: <1298560763-441-1-git-send-email-tero.kristo@nokia.com> User-Agent: Alpine 2.02 (LFD 1266 2009-07-14) MIME-version: 1.0 Content-type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2006 Lines: 57 applied to idle-test thanks, Len Brown, Intel Open Source Technology Center ps. please cc linux-pm on cpuidle pathces On Thu, 24 Feb 2011, Tero Kristo wrote: > 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/ > -- 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/