示例#1
0
文件: idle.c 项目: 513855417/linux
/**
 * cpuidle_idle_call - the main idle function
 *
 * NOTE: no locks or semaphores should be used here
 *
 * On archs that support TIF_POLLING_NRFLAG, is called with polling
 * set, and it returns with polling set.  If it ever stops polling, it
 * must clear the polling bit.
 */
static void cpuidle_idle_call(void)
{
	struct cpuidle_device *dev = cpuidle_get_device();
	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
	int next_state, entered_state;

	/*
	 * Check if the idle task must be rescheduled. If it is the
	 * case, exit the function after re-enabling the local irq.
	 */
	if (need_resched()) {
		local_irq_enable();
		return;
	}

	/*
	 * Tell the RCU framework we are entering an idle section,
	 * so no more rcu read side critical sections and one more
	 * step to the grace period
	 */
	rcu_idle_enter();

	if (cpuidle_not_available(drv, dev)) {
		default_idle_call();
		goto exit_idle;
	}

	/*
	 * Suspend-to-idle ("freeze") is a system state in which all user space
	 * has been frozen, all I/O devices have been suspended and the only
	 * activity happens here and in iterrupts (if any).  In that case bypass
	 * the cpuidle governor and go stratight for the deepest idle state
	 * available.  Possibly also suspend the local tick and the entire
	 * timekeeping to prevent timer interrupts from kicking us out of idle
	 * until a proper wakeup interrupt happens.
	 */
	if (idle_should_freeze()) {
		entered_state = cpuidle_enter_freeze(drv, dev);
		if (entered_state > 0) {
			local_irq_enable();
			goto exit_idle;
		}

		next_state = cpuidle_find_deepest_state(drv, dev);
		call_cpuidle(drv, dev, next_state);
	} else {
		/*
		 * Ask the cpuidle framework to choose a convenient idle state.
		 */
		next_state = cpuidle_select(drv, dev);
		entered_state = call_cpuidle(drv, dev, next_state);
		/*
		 * Give the governor an opportunity to reflect on the outcome
		 */
		cpuidle_reflect(dev, entered_state);
	}

exit_idle:
	__current_set_polling();

	/*
	 * It is up to the idle functions to reenable local interrupts
	 */
	if (WARN_ON_ONCE(irqs_disabled()))
		local_irq_enable();

	rcu_idle_exit();
}
示例#2
0
文件: idle.c 项目: Abhi1919/ath
/**
 * cpuidle_idle_call - the main idle function
 *
 * NOTE: no locks or semaphores should be used here
 *
 * On archs that support TIF_POLLING_NRFLAG, is called with polling
 * set, and it returns with polling set.  If it ever stops polling, it
 * must clear the polling bit.
 */
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;
	unsigned int broadcast;
	bool reflect;

	/*
	 * Check if the idle task must be rescheduled. If it is the
	 * case, exit the function after re-enabling the local irq.
	 */
	if (need_resched()) {
		local_irq_enable();
		return;
	}

	/*
	 * During the idle period, stop measuring the disabled irqs
	 * critical sections latencies
	 */
	stop_critical_timings();

	/*
	 * Tell the RCU framework we are entering an idle section,
	 * so no more rcu read side critical sections and one more
	 * step to the grace period
	 */
	rcu_idle_enter();

	if (cpuidle_not_available(drv, dev))
		goto use_default;

	/*
	 * Suspend-to-idle ("freeze") is a system state in which all user space
	 * has been frozen, all I/O devices have been suspended and the only
	 * activity happens here and in iterrupts (if any).  In that case bypass
	 * the cpuidle governor and go stratight for the deepest idle state
	 * available.  Possibly also suspend the local tick and the entire
	 * timekeeping to prevent timer interrupts from kicking us out of idle
	 * until a proper wakeup interrupt happens.
	 */
	if (idle_should_freeze()) {
		entered_state = cpuidle_enter_freeze(drv, dev);
		if (entered_state >= 0) {
			local_irq_enable();
			goto exit_idle;
		}

		reflect = false;
		next_state = cpuidle_find_deepest_state(drv, dev);
	} 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)
		goto use_default;

	/*
	 * 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;
	}

	broadcast = drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP;

	/*
	 * Tell the time framework to switch to a broadcast timer
	 * because our local timer will be shutdown. If a local timer
	 * is used from another cpu as a broadcast timer, this call may
	 * fail if it is not available
	 */
	if (broadcast && tick_broadcast_enter())
		goto use_default;

	/* 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 (broadcast)
		tick_broadcast_exit();

	/*
	 * Give the governor an opportunity to reflect on the outcome
	 */
	if (reflect)
		cpuidle_reflect(dev, entered_state);

exit_idle:
	__current_set_polling();

	/*
	 * It is up to the idle functions to reenable local interrupts
	 */
	if (WARN_ON_ONCE(irqs_disabled()))
		local_irq_enable();

	rcu_idle_exit();
	start_critical_timings();
	return;

use_default:
	/*
	 * We can't use the cpuidle framework, let's use the default
	 * idle routine.
	 */
	if (current_clr_polling_and_test())
		local_irq_enable();
	else
		arch_cpu_idle();

	goto exit_idle;
}