Messages in this thread Patch in this message | | | From | Len Brown <> | Subject | [PATCH 01/18] cpuidle: menu: fixed wrapping timers at 4.294 seconds | Date | Sat, 02 Apr 2011 02:22:43 -0400 |
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From: Tero Kristo <tero.kristo@nokia.com>
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 Signed-off-by: Tero Kristo <tero.kristo@nokia.com> Signed-off-by: Len Brown <len.brown@intel.com> --- 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); -- 1.7.5.rc0
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