Moved, renamed, and deleted files

The original directory structure was scattered and unorganized.
Changes are basically to make it look like kernel structure.

1 files changed, 912 insertions, 0 deletions

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
new file mode 100644
index 00000000..6a3a5b9f
--- /dev/null
+++ b/kernel/time/tick-sched.c
@@ -0,0 +1,912 @@
+/*
+ *  linux/kernel/time/tick-sched.c
+ *
+ *  Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
+ *  Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
+ *  Copyright(C) 2006-2007  Timesys Corp., Thomas Gleixner
+ *
+ *  No idle tick implementation for low and high resolution timers
+ *
+ *  Started by: Thomas Gleixner and Ingo Molnar
+ *
+ *  Distribute under GPLv2.
+ */
+#include <linux/cpu.h>
+#include <linux/err.h>
+#include <linux/hrtimer.h>
+#include <linux/interrupt.h>
+#include <linux/kernel_stat.h>
+#include <linux/percpu.h>
+#include <linux/profile.h>
+#include <linux/sched.h>
+#include <linux/module.h>
+
+#include <asm/irq_regs.h>
+
+#include "tick-internal.h"
+
+/*
+ * Per cpu nohz control structure
+ */
+static DEFINE_PER_CPU(struct tick_sched, tick_cpu_sched);
+
+/*
+ * The time, when the last jiffy update happened. Protected by xtime_lock.
+ */
+static ktime_t last_jiffies_update;
+
+struct tick_sched *tick_get_tick_sched(int cpu)
+{
+	return &per_cpu(tick_cpu_sched, cpu);
+}
+
+/*
+ * Must be called with interrupts disabled !
+ */
+static void tick_do_update_jiffies64(ktime_t now)
+{
+	unsigned long ticks = 0;
+	ktime_t delta;
+
+	/*
+	 * Do a quick check without holding xtime_lock:
+	 */
+	delta = ktime_sub(now, last_jiffies_update);
+	if (delta.tv64 < tick_period.tv64)
+		return;
+
+	/* Reevalute with xtime_lock held */
+	write_seqlock(&xtime_lock);
+
+	delta = ktime_sub(now, last_jiffies_update);
+	if (delta.tv64 >= tick_period.tv64) {
+
+		delta = ktime_sub(delta, tick_period);
+		last_jiffies_update = ktime_add(last_jiffies_update,
+						tick_period);
+
+		/* Slow path for long timeouts */
+		if (unlikely(delta.tv64 >= tick_period.tv64)) {
+			s64 incr = ktime_to_ns(tick_period);
+
+			ticks = ktime_divns(delta, incr);
+
+			last_jiffies_update = ktime_add_ns(last_jiffies_update,
+							   incr * ticks);
+		}
+		do_timer(++ticks);
+
+		/* Keep the tick_next_period variable up to date */
+		tick_next_period = ktime_add(last_jiffies_update, tick_period);
+	}
+	write_sequnlock(&xtime_lock);
+}
+
+/*
+ * Initialize and return retrieve the jiffies update.
+ */
+static ktime_t tick_init_jiffy_update(void)
+{
+	ktime_t period;
+
+	write_seqlock(&xtime_lock);
+	/* Did we start the jiffies update yet ? */
+	if (last_jiffies_update.tv64 == 0)
+		last_jiffies_update = tick_next_period;
+	period = last_jiffies_update;
+	write_sequnlock(&xtime_lock);
+	return period;
+}
+
+/*
+ * NOHZ - aka dynamic tick functionality
+ */
+#ifdef CONFIG_NO_HZ
+/*
+ * NO HZ enabled ?
+ */
+static int tick_nohz_enabled __read_mostly  = 1;
+
+/*
+ * Enable / Disable tickless mode
+ */
+static int __init setup_tick_nohz(char *str)
+{
+	if (!strcmp(str, "off"))
+		tick_nohz_enabled = 0;
+	else if (!strcmp(str, "on"))
+		tick_nohz_enabled = 1;
+	else
+		return 0;
+	return 1;
+}
+
+__setup("nohz=", setup_tick_nohz);
+
+/**
+ * tick_nohz_update_jiffies - update jiffies when idle was interrupted
+ *
+ * Called from interrupt entry when the CPU was idle
+ *
+ * In case the sched_tick was stopped on this CPU, we have to check if jiffies
+ * must be updated. Otherwise an interrupt handler could use a stale jiffy
+ * value. We do this unconditionally on any cpu, as we don't know whether the
+ * cpu, which has the update task assigned is in a long sleep.
+ */
+static void tick_nohz_update_jiffies(ktime_t now)
+{
+	int cpu = smp_processor_id();
+	struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
+	unsigned long flags;
+
+	ts->idle_waketime = now;
+
+	local_irq_save(flags);
+	tick_do_update_jiffies64(now);
+	local_irq_restore(flags);
+
+	touch_softlockup_watchdog();
+}
+
+/*
+ * Updates the per cpu time idle statistics counters
+ */
+static void
+update_ts_time_stats(int cpu, struct tick_sched *ts, ktime_t now, u64 *last_update_time)
+{
+	ktime_t delta;
+
+	if (ts->idle_active) {
+		delta = ktime_sub(now, ts->idle_entrytime);
+		if (nr_iowait_cpu(cpu) > 0)
+			ts->iowait_sleeptime = ktime_add(ts->iowait_sleeptime, delta);
+		else
+			ts->idle_sleeptime = ktime_add(ts->idle_sleeptime, delta);
+		ts->idle_entrytime = now;
+	}
+
+	if (last_update_time)
+		*last_update_time = ktime_to_us(now);
+
+}
+
+static void tick_nohz_stop_idle(int cpu, ktime_t now)
+{
+	struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
+
+	update_ts_time_stats(cpu, ts, now, NULL);
+	ts->idle_active = 0;
+
+	sched_clock_idle_wakeup_event(0);
+}
+
+static ktime_t tick_nohz_start_idle(int cpu, struct tick_sched *ts)
+{
+	ktime_t now = ktime_get();
+
+	ts->idle_entrytime = now;
+	ts->idle_active = 1;
+	sched_clock_idle_sleep_event();
+	return now;
+}
+
+/**
+ * get_cpu_idle_time_us - get the total idle time of a cpu
+ * @cpu: CPU number to query
+ * @last_update_time: variable to store update time in. Do not update
+ * counters if NULL.
+ *
+ * Return the cummulative idle time (since boot) for a given
+ * CPU, in microseconds.
+ *
+ * This time is measured via accounting rather than sampling,
+ * and is as accurate as ktime_get() is.
+ *
+ * This function returns -1 if NOHZ is not enabled.
+ */
+u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time)
+{
+	struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
+	ktime_t now, idle;
+
+	if (!tick_nohz_enabled)
+		return -1;
+
+	now = ktime_get();
+	if (last_update_time) {
+		update_ts_time_stats(cpu, ts, now, last_update_time);
+		idle = ts->idle_sleeptime;
+	} else {
+		if (ts->idle_active && !nr_iowait_cpu(cpu)) {
+			ktime_t delta = ktime_sub(now, ts->idle_entrytime);
+
+			idle = ktime_add(ts->idle_sleeptime, delta);
+		} else {
+			idle = ts->idle_sleeptime;
+		}
+	}
+
+	return ktime_to_us(idle);
+
+}
+EXPORT_SYMBOL_GPL(get_cpu_idle_time_us);
+
+/**
+ * get_cpu_iowait_time_us - get the total iowait time of a cpu
+ * @cpu: CPU number to query
+ * @last_update_time: variable to store update time in. Do not update
+ * counters if NULL.
+ *
+ * Return the cummulative iowait time (since boot) for a given
+ * CPU, in microseconds.
+ *
+ * This time is measured via accounting rather than sampling,
+ * and is as accurate as ktime_get() is.
+ *
+ * This function returns -1 if NOHZ is not enabled.
+ */
+u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time)
+{
+	struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
+	ktime_t now, iowait;
+
+	if (!tick_nohz_enabled)
+		return -1;
+
+	now = ktime_get();
+	if (last_update_time) {
+		update_ts_time_stats(cpu, ts, now, last_update_time);
+		iowait = ts->iowait_sleeptime;
+	} else {
+		if (ts->idle_active && nr_iowait_cpu(cpu) > 0) {
+			ktime_t delta = ktime_sub(now, ts->idle_entrytime);
+
+			iowait = ktime_add(ts->iowait_sleeptime, delta);
+		} else {
+			iowait = ts->iowait_sleeptime;
+		}
+	}
+
+	return ktime_to_us(iowait);
+}
+EXPORT_SYMBOL_GPL(get_cpu_iowait_time_us);
+
+static void tick_nohz_stop_sched_tick(struct tick_sched *ts)
+{
+	unsigned long seq, last_jiffies, next_jiffies, delta_jiffies;
+	ktime_t last_update, expires, now;
+	struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev;
+	u64 time_delta;
+	int cpu;
+
+	cpu = smp_processor_id();
+	ts = &per_cpu(tick_cpu_sched, cpu);
+
+	now = tick_nohz_start_idle(cpu, ts);
+
+	/*
+	 * If this cpu is offline and it is the one which updates
+	 * jiffies, then give up the assignment and let it be taken by
+	 * the cpu which runs the tick timer next. If we don't drop
+	 * this here the jiffies might be stale and do_timer() never
+	 * invoked.
+	 */
+	if (unlikely(!cpu_online(cpu))) {
+		if (cpu == tick_do_timer_cpu)
+			tick_do_timer_cpu = TICK_DO_TIMER_NONE;
+	}
+
+	if (unlikely(ts->nohz_mode == NOHZ_MODE_INACTIVE))
+		return;
+
+	if (need_resched())
+		return;
+
+	if (unlikely(local_softirq_pending() && cpu_online(cpu))) {
+		static int ratelimit;
+
+		if (ratelimit < 10) {
+			printk(KERN_ERR "NOHZ: local_softirq_pending %02x\n",
+			       (unsigned int) local_softirq_pending());
+			ratelimit++;
+		}
+		return;
+	}
+
+	ts->idle_calls++;
+	/* Read jiffies and the time when jiffies were updated last */
+	do {
+		seq = read_seqbegin(&xtime_lock);
+		last_update = last_jiffies_update;
+		last_jiffies = jiffies;
+		time_delta = timekeeping_max_deferment();
+	} while (read_seqretry(&xtime_lock, seq));
+
+	if (rcu_needs_cpu(cpu) || printk_needs_cpu(cpu) ||
+	    arch_needs_cpu(cpu)) {
+		next_jiffies = last_jiffies + 1;
+		delta_jiffies = 1;
+	} else {
+		/* Get the next timer wheel timer */
+		next_jiffies = get_next_timer_interrupt(last_jiffies);
+		delta_jiffies = next_jiffies - last_jiffies;
+	}
+	/*
+	 * Do not stop the tick, if we are only one off
+	 * or if the cpu is required for rcu
+	 */
+	if (!ts->tick_stopped && delta_jiffies == 1)
+		goto out;
+
+	/* Schedule the tick, if we are at least one jiffie off */
+	if ((long)delta_jiffies >= 1) {
+
+		/*
+		 * If this cpu is the one which updates jiffies, then
+		 * give up the assignment and let it be taken by the
+		 * cpu which runs the tick timer next, which might be
+		 * this cpu as well. If we don't drop this here the
+		 * jiffies might be stale and do_timer() never
+		 * invoked. Keep track of the fact that it was the one
+		 * which had the do_timer() duty last. If this cpu is
+		 * the one which had the do_timer() duty last, we
+		 * limit the sleep time to the timekeeping
+		 * max_deferement value which we retrieved
+		 * above. Otherwise we can sleep as long as we want.
+		 */
+		if (cpu == tick_do_timer_cpu) {
+			tick_do_timer_cpu = TICK_DO_TIMER_NONE;
+			ts->do_timer_last = 1;
+		} else if (tick_do_timer_cpu != TICK_DO_TIMER_NONE) {
+			time_delta = KTIME_MAX;
+			ts->do_timer_last = 0;
+		} else if (!ts->do_timer_last) {
+			time_delta = KTIME_MAX;
+		}
+
+		/*
+		 * calculate the expiry time for the next timer wheel
+		 * timer. delta_jiffies >= NEXT_TIMER_MAX_DELTA signals
+		 * that there is no timer pending or at least extremely
+		 * far into the future (12 days for HZ=1000). In this
+		 * case we set the expiry to the end of time.
+		 */
+		if (likely(delta_jiffies < NEXT_TIMER_MAX_DELTA)) {
+			/*
+			 * Calculate the time delta for the next timer event.
+			 * If the time delta exceeds the maximum time delta
+			 * permitted by the current clocksource then adjust
+			 * the time delta accordingly to ensure the
+			 * clocksource does not wrap.
+			 */
+			time_delta = min_t(u64, time_delta,
+					   tick_period.tv64 * delta_jiffies);
+		}
+
+		if (time_delta < KTIME_MAX)
+			expires = ktime_add_ns(last_update, time_delta);
+		else
+			expires.tv64 = KTIME_MAX;
+
+		/* Skip reprogram of event if its not changed */
+		if (ts->tick_stopped && ktime_equal(expires, dev->next_event))
+			goto out;
+
+		/*
+		 * nohz_stop_sched_tick can be called several times before
+		 * the nohz_restart_sched_tick is called. This happens when
+		 * interrupts arrive which do not cause a reschedule. In the
+		 * first call we save the current tick time, so we can restart
+		 * the scheduler tick in nohz_restart_sched_tick.
+		 */
+		if (!ts->tick_stopped) {
+			select_nohz_load_balancer(1);
+
+			ts->idle_tick = hrtimer_get_expires(&ts->sched_timer);
+			ts->tick_stopped = 1;
+			ts->idle_jiffies = last_jiffies;
+		}
+
+		ts->idle_sleeps++;
+
+		/* Mark expires */
+		ts->idle_expires = expires;
+
+		/*
+		 * If the expiration time == KTIME_MAX, then
+		 * in this case we simply stop the tick timer.
+		 */
+		 if (unlikely(expires.tv64 == KTIME_MAX)) {
+			if (ts->nohz_mode == NOHZ_MODE_HIGHRES)
+				hrtimer_cancel(&ts->sched_timer);
+			goto out;
+		}
+
+		if (ts->nohz_mode == NOHZ_MODE_HIGHRES) {
+			hrtimer_start(&ts->sched_timer, expires,
+				      HRTIMER_MODE_ABS_PINNED);
+			/* Check, if the timer was already in the past */
+			if (hrtimer_active(&ts->sched_timer))
+				goto out;
+		} else if (!tick_program_event(expires, 0))
+				goto out;
+		/*
+		 * We are past the event already. So we crossed a
+		 * jiffie boundary. Update jiffies and raise the
+		 * softirq.
+		 */
+		tick_do_update_jiffies64(ktime_get());
+	}
+	raise_softirq_irqoff(TIMER_SOFTIRQ);
+out:
+	ts->next_jiffies = next_jiffies;
+	ts->last_jiffies = last_jiffies;
+	ts->sleep_length = ktime_sub(dev->next_event, now);
+}
+
+/**
+ * tick_nohz_idle_enter - stop the idle tick from the idle task
+ *
+ * When the next event is more than a tick into the future, stop the idle tick
+ * Called when we start the idle loop.
+ *
+ * The arch is responsible of calling:
+ *
+ * - rcu_idle_enter() after its last use of RCU before the CPU is put
+ *  to sleep.
+ * - rcu_idle_exit() before the first use of RCU after the CPU is woken up.
+ */
+void tick_nohz_idle_enter(void)
+{
+	struct tick_sched *ts;
+
+	WARN_ON_ONCE(irqs_disabled());
+
+	/*
+ 	 * Update the idle state in the scheduler domain hierarchy
+ 	 * when tick_nohz_stop_sched_tick() is called from the idle loop.
+ 	 * State will be updated to busy during the first busy tick after
+ 	 * exiting idle.
+ 	 */
+	set_cpu_sd_state_idle();
+
+	local_irq_disable();
+
+	ts = &__get_cpu_var(tick_cpu_sched);
+	/*
+	 * set ts->inidle unconditionally. even if the system did not
+	 * switch to nohz mode the cpu frequency governers rely on the
+	 * update of the idle time accounting in tick_nohz_start_idle().
+	 */
+	ts->inidle = 1;
+	tick_nohz_stop_sched_tick(ts);
+
+	local_irq_enable();
+}
+
+/**
+ * tick_nohz_irq_exit - update next tick event from interrupt exit
+ *
+ * When an interrupt fires while we are idle and it doesn't cause
+ * a reschedule, it may still add, modify or delete a timer, enqueue
+ * an RCU callback, etc...
+ * So we need to re-calculate and reprogram the next tick event.
+ */
+void tick_nohz_irq_exit(void)
+{
+	struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);
+
+	if (!ts->inidle)
+		return;
+
+	tick_nohz_stop_sched_tick(ts);
+}
+
+/**
+ * tick_nohz_get_sleep_length - return the length of the current sleep
+ *
+ * Called from power state control code with interrupts disabled
+ */
+ktime_t tick_nohz_get_sleep_length(void)
+{
+	struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);
+
+	return ts->sleep_length;
+}
+
+static void tick_nohz_restart(struct tick_sched *ts, ktime_t now)
+{
+	hrtimer_cancel(&ts->sched_timer);
+	hrtimer_set_expires(&ts->sched_timer, ts->idle_tick);
+
+	while (1) {
+		/* Forward the time to expire in the future */
+		hrtimer_forward(&ts->sched_timer, now, tick_period);
+
+		if (ts->nohz_mode == NOHZ_MODE_HIGHRES) {
+			hrtimer_start_expires(&ts->sched_timer,
+					      HRTIMER_MODE_ABS_PINNED);
+			/* Check, if the timer was already in the past */
+			if (hrtimer_active(&ts->sched_timer))
+				break;
+		} else {
+			if (!tick_program_event(
+				hrtimer_get_expires(&ts->sched_timer), 0))
+				break;
+		}
+		/* Reread time and update jiffies */
+		now = ktime_get();
+		tick_do_update_jiffies64(now);
+	}
+}
+
+/**
+ * tick_nohz_idle_exit - restart the idle tick from the idle task
+ *
+ * Restart the idle tick when the CPU is woken up from idle
+ * This also exit the RCU extended quiescent state. The CPU
+ * can use RCU again after this function is called.
+ */
+void tick_nohz_idle_exit(void)
+{
+	int cpu = smp_processor_id();
+	struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
+#ifndef CONFIG_VIRT_CPU_ACCOUNTING
+	unsigned long ticks;
+#endif
+	ktime_t now;
+
+	local_irq_disable();
+
+	WARN_ON_ONCE(!ts->inidle);
+
+	ts->inidle = 0;
+
+	if (ts->idle_active || ts->tick_stopped)
+		now = ktime_get();
+
+	if (ts->idle_active)
+		tick_nohz_stop_idle(cpu, now);
+
+	if (!ts->tick_stopped) {
+		local_irq_enable();
+		return;
+	}
+
+	/* Update jiffies first */
+	select_nohz_load_balancer(0);
+	tick_do_update_jiffies64(now);
+
+#ifndef CONFIG_VIRT_CPU_ACCOUNTING
+	/*
+	 * We stopped the tick in idle. Update process times would miss the
+	 * time we slept as update_process_times does only a 1 tick
+	 * accounting. Enforce that this is accounted to idle !
+	 */
+	ticks = jiffies - ts->idle_jiffies;
+	/*
+	 * We might be one off. Do not randomly account a huge number of ticks!
+	 */
+	if (ticks && ticks < LONG_MAX)
+		account_idle_ticks(ticks);
+#endif
+
+	touch_softlockup_watchdog();
+	/*
+	 * Cancel the scheduled timer and restore the tick
+	 */
+	ts->tick_stopped  = 0;
+	ts->idle_exittime = now;
+
+	tick_nohz_restart(ts, now);
+
+	local_irq_enable();
+}
+
+static int tick_nohz_reprogram(struct tick_sched *ts, ktime_t now)
+{
+	hrtimer_forward(&ts->sched_timer, now, tick_period);
+	return tick_program_event(hrtimer_get_expires(&ts->sched_timer), 0);
+}
+
+/*
+ * The nohz low res interrupt handler
+ */
+static void tick_nohz_handler(struct clock_event_device *dev)
+{
+	struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);
+	struct pt_regs *regs = get_irq_regs();
+	int cpu = smp_processor_id();
+	ktime_t now = ktime_get();
+
+	dev->next_event.tv64 = KTIME_MAX;
+
+	/*
+	 * Check if the do_timer duty was dropped. We don't care about
+	 * concurrency: This happens only when the cpu in charge went
+	 * into a long sleep. If two cpus happen to assign themself to
+	 * this duty, then the jiffies update is still serialized by
+	 * xtime_lock.
+	 */
+	if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE))
+		tick_do_timer_cpu = cpu;
+
+	/* Check, if the jiffies need an update */
+	if (tick_do_timer_cpu == cpu)
+		tick_do_update_jiffies64(now);
+
+	/*
+	 * When we are idle and the tick is stopped, we have to touch
+	 * the watchdog as we might not schedule for a really long
+	 * time. This happens on complete idle SMP systems while
+	 * waiting on the login prompt. We also increment the "start
+	 * of idle" jiffy stamp so the idle accounting adjustment we
+	 * do when we go busy again does not account too much ticks.
+	 */
+	if (ts->tick_stopped) {
+		touch_softlockup_watchdog();
+		ts->idle_jiffies++;
+	}
+
+	update_process_times(user_mode(regs));
+	profile_tick(CPU_PROFILING);
+
+	while (tick_nohz_reprogram(ts, now)) {
+		now = ktime_get();
+		tick_do_update_jiffies64(now);
+	}
+}
+
+/**
+ * tick_nohz_switch_to_nohz - switch to nohz mode
+ */
+static void tick_nohz_switch_to_nohz(void)
+{
+	struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);
+	ktime_t next;
+
+	if (!tick_nohz_enabled)
+		return;
+
+	local_irq_disable();
+	if (tick_switch_to_oneshot(tick_nohz_handler)) {
+		local_irq_enable();
+		return;
+	}
+
+	ts->nohz_mode = NOHZ_MODE_LOWRES;
+
+	/*
+	 * Recycle the hrtimer in ts, so we can share the
+	 * hrtimer_forward with the highres code.
+	 */
+	hrtimer_init(&ts->sched_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
+	/* Get the next period */
+	next = tick_init_jiffy_update();
+
+	for (;;) {
+		hrtimer_set_expires(&ts->sched_timer, next);
+		if (!tick_program_event(next, 0))
+			break;
+		next = ktime_add(next, tick_period);
+	}
+	local_irq_enable();
+}
+
+/*
+ * When NOHZ is enabled and the tick is stopped, we need to kick the
+ * tick timer from irq_enter() so that the jiffies update is kept
+ * alive during long running softirqs. That's ugly as hell, but
+ * correctness is key even if we need to fix the offending softirq in
+ * the first place.
+ *
+ * Note, this is different to tick_nohz_restart. We just kick the
+ * timer and do not touch the other magic bits which need to be done
+ * when idle is left.
+ */
+static void tick_nohz_kick_tick(int cpu, ktime_t now)
+{
+#if 0
+	/* Switch back to 2.6.27 behaviour */
+
+	struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
+	ktime_t delta;
+
+	/*
+	 * Do not touch the tick device, when the next expiry is either
+	 * already reached or less/equal than the tick period.
+	 */
+	delta =	ktime_sub(hrtimer_get_expires(&ts->sched_timer), now);
+	if (delta.tv64 <= tick_period.tv64)
+		return;
+
+	tick_nohz_restart(ts, now);
+#endif
+}
+
+static inline void tick_check_nohz(int cpu)
+{
+	struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
+	ktime_t now;
+
+	if (!ts->idle_active && !ts->tick_stopped)
+		return;
+	now = ktime_get();
+	if (ts->idle_active)
+		tick_nohz_stop_idle(cpu, now);
+	if (ts->tick_stopped) {
+		tick_nohz_update_jiffies(now);
+		tick_nohz_kick_tick(cpu, now);
+	}
+}
+
+#else
+
+static inline void tick_nohz_switch_to_nohz(void) { }
+static inline void tick_check_nohz(int cpu) { }
+
+#endif /* NO_HZ */
+
+/*
+ * Called from irq_enter to notify about the possible interruption of idle()
+ */
+void tick_check_idle(int cpu)
+{
+	tick_check_oneshot_broadcast(cpu);
+	tick_check_nohz(cpu);
+}
+
+/*
+ * High resolution timer specific code
+ */
+#ifdef CONFIG_HIGH_RES_TIMERS
+/*
+ * We rearm the timer until we get disabled by the idle code.
+ * Called with interrupts disabled and timer->base->cpu_base->lock held.
+ */
+static enum hrtimer_restart tick_sched_timer(struct hrtimer *timer)
+{
+	struct tick_sched *ts =
+		container_of(timer, struct tick_sched, sched_timer);
+	struct pt_regs *regs = get_irq_regs();
+	ktime_t now = ktime_get();
+	int cpu = smp_processor_id();
+
+#ifdef CONFIG_NO_HZ
+	/*
+	 * Check if the do_timer duty was dropped. We don't care about
+	 * concurrency: This happens only when the cpu in charge went
+	 * into a long sleep. If two cpus happen to assign themself to
+	 * this duty, then the jiffies update is still serialized by
+	 * xtime_lock.
+	 */
+	if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE))
+		tick_do_timer_cpu = cpu;
+#endif
+
+	/* Check, if the jiffies need an update */
+	if (tick_do_timer_cpu == cpu)
+		tick_do_update_jiffies64(now);
+
+	/*
+	 * Do not call, when we are not in irq context and have
+	 * no valid regs pointer
+	 */
+	if (regs) {
+		/*
+		 * When we are idle and the tick is stopped, we have to touch
+		 * the watchdog as we might not schedule for a really long
+		 * time. This happens on complete idle SMP systems while
+		 * waiting on the login prompt. We also increment the "start of
+		 * idle" jiffy stamp so the idle accounting adjustment we do
+		 * when we go busy again does not account too much ticks.
+		 */
+		if (ts->tick_stopped) {
+			touch_softlockup_watchdog();
+			ts->idle_jiffies++;
+		}
+		update_process_times(user_mode(regs));
+		profile_tick(CPU_PROFILING);
+	}
+
+	hrtimer_forward(timer, now, tick_period);
+
+	return HRTIMER_RESTART;
+}
+
+/**
+ * tick_setup_sched_timer - setup the tick emulation timer
+ */
+void tick_setup_sched_timer(void)
+{
+	struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);
+	ktime_t now = ktime_get();
+
+	/*
+	 * Emulate tick processing via per-CPU hrtimers:
+	 */
+	hrtimer_init(&ts->sched_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
+	ts->sched_timer.function = tick_sched_timer;
+
+	/* Get the next period (per cpu) */
+	hrtimer_set_expires(&ts->sched_timer, tick_init_jiffy_update());
+
+	for (;;) {
+		hrtimer_forward(&ts->sched_timer, now, tick_period);
+		hrtimer_start_expires(&ts->sched_timer,
+				      HRTIMER_MODE_ABS_PINNED);
+		/* Check, if the timer was already in the past */
+		if (hrtimer_active(&ts->sched_timer))
+			break;
+		now = ktime_get();
+	}
+
+#ifdef CONFIG_NO_HZ
+	if (tick_nohz_enabled)
+		ts->nohz_mode = NOHZ_MODE_HIGHRES;
+#endif
+}
+#endif /* HIGH_RES_TIMERS */
+
+#if defined CONFIG_NO_HZ || defined CONFIG_HIGH_RES_TIMERS
+void tick_cancel_sched_timer(int cpu)
+{
+	struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
+
+# ifdef CONFIG_HIGH_RES_TIMERS
+	if (ts->sched_timer.base)
+		hrtimer_cancel(&ts->sched_timer);
+# endif
+
+	ts->nohz_mode = NOHZ_MODE_INACTIVE;
+}
+#endif
+
+/**
+ * Async notification about clocksource changes
+ */
+void tick_clock_notify(void)
+{
+	int cpu;
+
+	for_each_possible_cpu(cpu)
+		set_bit(0, &per_cpu(tick_cpu_sched, cpu).check_clocks);
+}
+
+/*
+ * Async notification about clock event changes
+ */
+void tick_oneshot_notify(void)
+{
+	struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);
+
+	set_bit(0, &ts->check_clocks);
+}
+
+/**
+ * Check, if a change happened, which makes oneshot possible.
+ *
+ * Called cyclic from the hrtimer softirq (driven by the timer
+ * softirq) allow_nohz signals, that we can switch into low-res nohz
+ * mode, because high resolution timers are disabled (either compile
+ * or runtime).
+ */
+int tick_check_oneshot_change(int allow_nohz)
+{
+	struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);
+
+	if (!test_and_clear_bit(0, &ts->check_clocks))
+		return 0;
+
+	if (ts->nohz_mode != NOHZ_MODE_INACTIVE)
+		return 0;
+
+	if (!timekeeping_valid_for_hres() || !tick_is_oneshot_available())
+		return 0;
+
+	if (!allow_nohz)
+		return 1;
+
+	tick_nohz_switch_to_nohz();
+	return 0;
+}