| Message ID | c55877aa13886c660da484118a96117f939553e3.1418712225.git.len.brown@intel.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
On 12/16/2014 07:52 AM, Len Brown wrote: > From: Len Brown <len.brown@intel.com> > > When menu sees CPUIDLE_FLAG_TIME_INVALID, it ignores its timestamps, > and assumes that idle lasted as long as the time till next predicted > timer expiration. > > But if an interrupt was seen and serviced before that duration, > it would actually be more accurate to use the measured time > rather than rounding up to the next predicted timer expiration. > > And if an interrupt is seen and serviced such that the mesured time > exceeds the time till next predicted timer expiration, then > truncating to that expiration is the right thing to do -- > since we can never stay idle past that timer expiration. > > So the code can do a better job without > checking for CPUIDLE_FLAG_TIME_INVALID. Good point. Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org> > Signed-off-by: Len Brown <len.brown@intel.com> > Cc: Daniel Lezcano <daniel.lezcano@linaro.org> > --- > drivers/cpuidle/governors/menu.c | 25 ++++++++++--------------- > 1 file changed, 10 insertions(+), 15 deletions(-) > > diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c > index 659d7b0..4058079 100644 > --- a/drivers/cpuidle/governors/menu.c > +++ b/drivers/cpuidle/governors/menu.c > @@ -396,8 +396,8 @@ static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev) > * power state and occurrence of the wakeup event. > * > * If the entered idle state didn't support residency measurements, > - * we are basically lost in the dark how much time passed. > - * As a compromise, assume we slept for the whole expected time. > + * we use them anyway if they are short, and if long, > + * truncate to the whole expected time. > * > * Any measured amount of time will include the exit latency. > * Since we are interested in when the wakeup begun, not when it > @@ -405,22 +405,17 @@ static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev) > * the measured amount of time is less than the exit latency, > * assume the state was never reached and the exit latency is 0. > */ > - if (unlikely(target->flags & CPUIDLE_FLAG_TIME_INVALID)) { > - /* Use timer value as is */ > - measured_us = data->next_timer_us; > > - } else { > - /* Use measured value */ > - measured_us = cpuidle_get_last_residency(dev); > + /* measured value */ > + measured_us = cpuidle_get_last_residency(dev); > > - /* Deduct exit latency */ > - if (measured_us > target->exit_latency) > - measured_us -= target->exit_latency; > + /* Deduct exit latency */ > + if (measured_us > target->exit_latency) > + measured_us -= target->exit_latency; > > - /* Make sure our coefficients do not exceed unity */ > - if (measured_us > data->next_timer_us) > - measured_us = data->next_timer_us; > - } > + /* Make sure our coefficients do not exceed unity */ > + if (measured_us > data->next_timer_us) > + measured_us = data->next_timer_us; > > /* Update our correction ratio */ > new_factor = data->correction_factor[data->bucket]; >
On Tue, Dec 16, 2014 at 8:52 AM, Len Brown <lenb@kernel.org> wrote: > From: Len Brown <len.brown@intel.com> > > When menu sees CPUIDLE_FLAG_TIME_INVALID, it ignores its timestamps, > and assumes that idle lasted as long as the time till next predicted > timer expiration. > > But if an interrupt was seen and serviced before that duration, > it would actually be more accurate to use the measured time > rather than rounding up to the next predicted timer expiration. > > And if an interrupt is seen and serviced such that the mesured time > exceeds the time till next predicted timer expiration, then > truncating to that expiration is the right thing to do -- > since we can never stay idle past that timer expiration. > > So the code can do a better job without > checking for CPUIDLE_FLAG_TIME_INVALID. > > Signed-off-by: Len Brown <len.brown@intel.com> > Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Reviewed-by: Tuukka Tikkanen <tuukka.tikkanen@linaro.org> > --- > drivers/cpuidle/governors/menu.c | 25 ++++++++++--------------- > 1 file changed, 10 insertions(+), 15 deletions(-) > > diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c > index 659d7b0..4058079 100644 > --- a/drivers/cpuidle/governors/menu.c > +++ b/drivers/cpuidle/governors/menu.c > @@ -396,8 +396,8 @@ static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev) > * power state and occurrence of the wakeup event. > * > * If the entered idle state didn't support residency measurements, > - * we are basically lost in the dark how much time passed. > - * As a compromise, assume we slept for the whole expected time. > + * we use them anyway if they are short, and if long, > + * truncate to the whole expected time. > * > * Any measured amount of time will include the exit latency. > * Since we are interested in when the wakeup begun, not when it > @@ -405,22 +405,17 @@ static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev) > * the measured amount of time is less than the exit latency, > * assume the state was never reached and the exit latency is 0. > */ > - if (unlikely(target->flags & CPUIDLE_FLAG_TIME_INVALID)) { > - /* Use timer value as is */ > - measured_us = data->next_timer_us; > > - } else { > - /* Use measured value */ > - measured_us = cpuidle_get_last_residency(dev); > + /* measured value */ > + measured_us = cpuidle_get_last_residency(dev); > > - /* Deduct exit latency */ > - if (measured_us > target->exit_latency) > - measured_us -= target->exit_latency; > + /* Deduct exit latency */ > + if (measured_us > target->exit_latency) > + measured_us -= target->exit_latency; > > - /* Make sure our coefficients do not exceed unity */ > - if (measured_us > data->next_timer_us) > - measured_us = data->next_timer_us; > - } > + /* Make sure our coefficients do not exceed unity */ > + if (measured_us > data->next_timer_us) > + measured_us = data->next_timer_us; > > /* Update our correction ratio */ > new_factor = data->correction_factor[data->bucket]; > -- > 2.1.2.451.g98349e5 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-pm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c index 659d7b0..4058079 100644 --- a/drivers/cpuidle/governors/menu.c +++ b/drivers/cpuidle/governors/menu.c @@ -396,8 +396,8 @@ static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev) * power state and occurrence of the wakeup event. * * If the entered idle state didn't support residency measurements, - * we are basically lost in the dark how much time passed. - * As a compromise, assume we slept for the whole expected time. + * we use them anyway if they are short, and if long, + * truncate to the whole expected time. * * Any measured amount of time will include the exit latency. * Since we are interested in when the wakeup begun, not when it @@ -405,22 +405,17 @@ static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev) * the measured amount of time is less than the exit latency, * assume the state was never reached and the exit latency is 0. */ - if (unlikely(target->flags & CPUIDLE_FLAG_TIME_INVALID)) { - /* Use timer value as is */ - measured_us = data->next_timer_us; - } else { - /* Use measured value */ - measured_us = cpuidle_get_last_residency(dev); + /* measured value */ + measured_us = cpuidle_get_last_residency(dev); - /* Deduct exit latency */ - if (measured_us > target->exit_latency) - measured_us -= target->exit_latency; + /* Deduct exit latency */ + if (measured_us > target->exit_latency) + measured_us -= target->exit_latency; - /* Make sure our coefficients do not exceed unity */ - if (measured_us > data->next_timer_us) - measured_us = data->next_timer_us; - } + /* Make sure our coefficients do not exceed unity */ + if (measured_us > data->next_timer_us) + measured_us = data->next_timer_us; /* Update our correction ratio */ new_factor = data->correction_factor[data->bucket];