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Code Pull requests 5 Wiki Activity

cpuidle: menu: fixed wrapping timers at 4.294 seconds

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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 <tero.kristo@nokia.com>
Signed-off-by: Len Brown <len.brown@intel.com>
This commit is contained in:
Tero Kristo 2011-02-24 17:19:23 +02:00 committed by Len Brown
parent 521cb40b0c
commit 7467571f44
1 changed files with 3 additions and 1 deletions
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4
drivers/cpuidle/governors/menu.c
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@ -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);