When a cpu enters a deep idle state, the local timers are stopped and the time framework falls back to the timer device used as a broadcast timer.
The different cpuidle drivers are calling clockevents_notify ENTER/EXIT when the idle state stops the local timer.
The proposed patch introduces a new flag CPUIDLE_FLAG_TIMER_STOP to let the cpuidle framework to call clockevents_notify instead of duplicating again and again these lines in all the cpuidle drivers.
Signed-off-by: Daniel Lezcano daniel.lezcano@linaro.org --- drivers/cpuidle/cpuidle.c | 9 +++++++++ include/linux/cpuidle.h | 1 + 2 files changed, 10 insertions(+)
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index eba6929..c500370 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -8,6 +8,7 @@ * This code is licenced under the GPL. */
+#include <linux/clockchips.h> #include <linux/kernel.h> #include <linux/mutex.h> #include <linux/sched.h> @@ -146,12 +147,20 @@ int cpuidle_idle_call(void)
trace_cpu_idle_rcuidle(next_state, dev->cpu);
+ if (drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP) + clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, + &dev->cpu); + if (cpuidle_state_is_coupled(dev, drv, next_state)) entered_state = cpuidle_enter_state_coupled(dev, drv, next_state); else entered_state = cpuidle_enter_state(dev, drv, next_state);
+ if (drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP) + clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, + &dev->cpu); + trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
/* give the governor an opportunity to reflect on the outcome */ diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h index 480c14d..a837b33 100644 --- a/include/linux/cpuidle.h +++ b/include/linux/cpuidle.h @@ -57,6 +57,7 @@ struct cpuidle_state { /* Idle State Flags */ #define CPUIDLE_FLAG_TIME_VALID (0x01) /* is residency time measurable? */ #define CPUIDLE_FLAG_COUPLED (0x02) /* state applies to multiple cpus */ +#define CPUIDLE_FLAG_TIMER_STOP (0x04) /* timer is stopped on this state */
#define CPUIDLE_DRIVER_FLAGS_MASK (0xFFFF0000)
On Wed, 20 Mar 2013, Daniel Lezcano wrote:
When a cpu enters a deep idle state, the local timers are stopped and the time framework falls back to the timer device used as a broadcast timer.
The different cpuidle drivers are calling clockevents_notify ENTER/EXIT when the idle state stops the local timer.
The proposed patch introduces a new flag CPUIDLE_FLAG_TIMER_STOP to let
Please stop using "proposed patch ...." wording in a patch description. The changelog you submit with your patch should be applicable w/o rewriting.
the cpuidle framework to call clockevents_notify instead of duplicating again and again these lines in all the cpuidle drivers.
That's a good enough reason, really. So that paragraph should be something like:
"Add a new flag CPUIDLE_FLAG_TIMER_STOP which can be set by cpuidle drivers. If the flag is set the cpuidle core code takes care of the notification on behalf of the driver to avoid pointless code duplication."
Ideally you would follow up with two or three drivers converted to that new infrastructure instead of sending that patch standalone. That way reviewers can really see the benefit in terms of reduced code duplication.
Signed-off-by: Daniel Lezcano daniel.lezcano@linaro.org
Other than the above rant:
Reviewed-by: Thomas Gleixner tglx@linutronix.de
On 03/20/2013 10:21 PM, Thomas Gleixner wrote:
On Wed, 20 Mar 2013, Daniel Lezcano wrote:
When a cpu enters a deep idle state, the local timers are stopped and the time framework falls back to the timer device used as a broadcast timer.
The different cpuidle drivers are calling clockevents_notify ENTER/EXIT when the idle state stops the local timer.
The proposed patch introduces a new flag CPUIDLE_FLAG_TIMER_STOP to let
Please stop using "proposed patch ...." wording in a patch description. The changelog you submit with your patch should be applicable w/o rewriting.
Oh, yes. Thanks for pointing this.
the cpuidle framework to call clockevents_notify instead of duplicating again and again these lines in all the cpuidle drivers.
That's a good enough reason, really. So that paragraph should be something like:
"Add a new flag CPUIDLE_FLAG_TIMER_STOP which can be set by cpuidle drivers. If the flag is set the cpuidle core code takes care of the notification on behalf of the driver to avoid pointless code duplication."
Ideally you would follow up with two or three drivers converted to that new infrastructure instead of sending that patch standalone. That way reviewers can really see the benefit in terms of reduced code duplication.
Thanks for your review. I will resend this patch with a better log and a couple of patches on top using this flag.
-- Daniel
linaro-kernel@lists.linaro.org
-
Daniel Lezcano -
Thomas Gleixner