| Message ID | 1308735645-5298-2-git-send-email-colin.king@canonical.com |
|---|---|
| State | New |
| Headers | show |
On 22.06.2011 11:40, Colin King wrote: > 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 # .32.x through .39.x > 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); Clean pick and also queued for upstream stable. Acked-by: Stefan Bader <stefan.bader@canonical.com>
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);