Commit bcf6ad8a authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

sched / idle: Eliminate the "reflect" check from cpuidle_idle_call() 



Since cpuidle_reflect() should only be called if the idle state
to enter was selected by cpuidle_select(), there is the "reflect"
variable in cpuidle_idle_call() whose value is used to determine
whether or not that is the case.

However, if the entire code run between the conditional setting
"reflect" and the call to cpuidle_reflect() is moved to a separate
function, it will be possible to call that new function in both
branches of the conditional, in which case cpuidle_reflect() will
only need to be called from one of them too and the "reflect"
variable won't be necessary any more.

This eliminates one check made by cpuidle_idle_call() on the majority
of its invocations, so change the code as described.

Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: default avatarDaniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
parent a802ea96

kernel/sched/idle.c

+46 −44
Original line number Diff line number Diff line
@@ -79,6 +79,46 @@ static void default_idle_call(void) 
		arch_cpu_idle();

}



static int call_cpuidle(struct cpuidle_driver *drv, struct cpuidle_device *dev,

		      int next_state)

{

	int entered_state;



	/* Fall back to the default arch idle method on errors. */

	if (next_state < 0) {

		default_idle_call();

		return next_state;

	}



	/*

	 * The idle task must be scheduled, it is pointless to go to idle, just

	 * update no idle residency and return.

	 */

	if (current_clr_polling_and_test()) {

		dev->last_residency = 0;

		local_irq_enable();

		return -EBUSY;

	}



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

	idle_set_state(this_rq(), &drv->states[next_state]);



	/*

	 * Enter the idle state previously returned by the governor decision.

	 * This function will block until an interrupt occurs and will take

	 * care of re-enabling the local interrupts

	 */

	entered_state = cpuidle_enter(drv, dev, next_state);



	/* The cpu is no longer idle or about to enter idle. */

	idle_set_state(this_rq(), NULL);



	if (entered_state == -EBUSY)

		default_idle_call();



	return entered_state;

}



/**

 * cpuidle_idle_call - the main idle function

 *
@@ -93,7 +133,6 @@ static void cpuidle_idle_call(void) 
	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);

	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);

	int next_state, entered_state;

	bool reflect;



	/*

	 * Check if the idle task must be rescheduled. If it is the
@@ -138,56 +177,19 @@ static void cpuidle_idle_call(void) 
			goto exit_idle;

		}



		reflect = false;

		next_state = cpuidle_find_deepest_state(drv, dev);

		call_cpuidle(drv, dev, next_state);

	} else {

		reflect = true;

		/*

		 * Ask the cpuidle framework to choose a convenient idle state.

		 */

		next_state = cpuidle_select(drv, dev);

	}

	/* Fall back to the default arch idle method on errors. */

	if (next_state < 0) {

		default_idle_call();

		goto exit_idle;

	}



	/*

	 * The idle task must be scheduled, it is pointless to

	 * go to idle, just update no idle residency and get

	 * out of this function

	 */

	if (current_clr_polling_and_test()) {

		dev->last_residency = 0;

		entered_state = next_state;

		local_irq_enable();

		goto exit_idle;

	}



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

	idle_set_state(this_rq(), &drv->states[next_state]);



	/*

	 * Enter the idle state previously returned by the governor decision.

	 * This function will block until an interrupt occurs and will take

	 * care of re-enabling the local interrupts

	 */

	entered_state = cpuidle_enter(drv, dev, next_state);



	/* The cpu is no longer idle or about to enter idle. */

	idle_set_state(this_rq(), NULL);



	if (entered_state == -EBUSY) {

		default_idle_call();

		goto exit_idle;

	}



		entered_state = call_cpuidle(drv, dev, next_state);

		/*

		 * Give the governor an opportunity to reflect on the outcome

		 */

	if (reflect)

		cpuidle_reflect(dev, entered_state);

	}



exit_idle:

	__current_set_polling();

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