[129/146] cpuidle: menu: fixed wrapping timers at 4.294 seconds

Greg KH
2011-06-01T09:00:34Z

From: Tero Kristo <tero.kristo@nokia.com>

commit 7467571f4480b273007517b26297c07154c73924 upstream.

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 <tero.kristo@nokia.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/cpuidle/governors/menu.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -237,6 +237,7 @@ static int menu_select(struct cpuidle_de
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_de
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);