Commit 0d94039f authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

cpuidle: Select a different state on tick_broadcast_enter() failures 



If tick_broadcast_enter() fails in cpuidle_enter_state(),
try to find another idle state to enter instead of invoking
default_idle_call() immediately and returning -EBUSY which
should increase the chances of saving some energy in those
cases.

Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: default avatarPreeti U Murthy <preeti@linux.vnet.ibm.com>
Tested-by: default avatarPreeti U Murthy <preeti@linux.vnet.ibm.com>
Tested-by: default avatarSudeep Holla <sudeep.holla@arm.com>
Acked-by: default avatarKevin Hilman <khilman@linaro.org>
parent 827a5aef

drivers/cpuidle/cpuidle.c

+15 −5
Original line number Diff line number Diff line
@@ -73,7 +73,10 @@ int cpuidle_play_dead(void) 
}



static int find_deepest_state(struct cpuidle_driver *drv,

			      struct cpuidle_device *dev, bool freeze)

			      struct cpuidle_device *dev,

			      unsigned int max_latency,

			      unsigned int forbidden_flags,

			      bool freeze)

{

	unsigned int latency_req = 0;

	int i, ret = freeze ? -1 : CPUIDLE_DRIVER_STATE_START - 1;
@@ -83,6 +86,8 @@ static int find_deepest_state(struct cpuidle_driver *drv, 
		struct cpuidle_state_usage *su = &dev->states_usage[i];



		if (s->disabled || su->disable || s->exit_latency <= latency_req

		    || s->exit_latency > max_latency

		    || (s->flags & forbidden_flags)

		    || (freeze && !s->enter_freeze))

			continue;
@@ -100,7 +105,7 @@ static int find_deepest_state(struct cpuidle_driver *drv, 
int cpuidle_find_deepest_state(struct cpuidle_driver *drv,

			       struct cpuidle_device *dev)

{

	return find_deepest_state(drv, dev, false);

	return find_deepest_state(drv, dev, UINT_MAX, 0, false);

}



static void enter_freeze_proper(struct cpuidle_driver *drv,
@@ -139,7 +144,7 @@ int cpuidle_enter_freeze(struct cpuidle_driver *drv, struct cpuidle_device *dev) 
	 * that interrupts won't be enabled when it exits and allows the tick to

	 * be frozen safely.

	 */

	index = find_deepest_state(drv, dev, true);

	index = find_deepest_state(drv, dev, UINT_MAX, 0, true);

	if (index >= 0)

		enter_freeze_proper(drv, dev, index);
@@ -168,9 +173,14 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv, 
	 * CPU as a broadcast timer, this call may fail if it is not available.

	 */

	if (broadcast && tick_broadcast_enter()) {

		index = find_deepest_state(drv, dev, target_state->exit_latency,

					   CPUIDLE_FLAG_TIMER_STOP, false);

		if (index < 0) {

			default_idle_call();

			return -EBUSY;

		}

		target_state = &drv->states[index];

	}



	/* Take note of the planned idle state. */

	sched_idle_set_state(target_state);

CRA Git | Maintained and supported by SUSTech CRA and CCSE