From patchwork Wed Jun 22 09:40:45 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [1/1] cpuidle: menu: fixed wrapping timers at 4.294 seconds Date: Tue, 21 Jun 2011 23:40:45 -0000 From: Colin King X-Patchwork-Id: 101424 Message-Id: <1308735645-5298-2-git-send-email-colin.king@canonical.com> To: kernel-team@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);