projects/linux·commit 79bf2bb3

[PATCH] tick-management: dyntick / highres functionality

79bf2bb3 · Thomas Gleixner <[email protected]> · 2007-02-16 01:28:03 -08:00

With Ingo Molnar <[email protected]>

Add functions to provide dynamic ticks and high resolution timers.  The code
which keeps track of jiffies and handles the long idle periods is shared
between tick based and high resolution timer based dynticks.  The dyntick
functionality can be disabled on the kernel commandline.  Provide also the
infrastructure to support high resolution timers.

Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Cc: john stultz <[email protected]>
Cc: Roman Zippel <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Commit
79bf2bb335b85db25d27421c798595a2fa2a0e82
Parents
f8381cba

Changes

15 files changed · +1049 −17

FileStatusAddDelContent
Documentation/kernel-parameters.txtmodified+4−0View file
include/linux/hardirq.hmodified+11−1View file
include/linux/hrtimer.hmodified+6−0View file
include/linux/tick.hmodified+69−2View file
kernel/hrtimer.cmodified+14−6View file
kernel/softirq.cmodified+12−3View file
kernel/time/Kconfigadded+15−0View file
kernel/time/Makefilemodified+2−0View file
kernel/time/clocksource.cmodified+8−0View file
kernel/time/tick-broadcast.cmodified+190−1View file
kernel/time/tick-common.cmodified+26−0View file
kernel/time/tick-internal.hmodified+47−2View file
kernel/time/tick-oneshot.cadded+84−0View file
kernel/time/tick-sched.cadded+558−0View file
kernel/timer.cmodified+3−2View file

Only the first 600 diff lines are shown. Download the complete patch.

Documentation/kernel-parameters.txt

View file
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 22b1996..52bf1ed 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1078,6 +1078,10 @@ and is between 256 and 4096 characters. It is defined in the file
in certain environments such as networked servers or
real-time systems.
+ nohz= [KNL] Boottime enable/disable dynamic ticks
+ Valid arguments: on, off
+ Default: on
+
noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
noirqdebug [IA-32] Disables the code which attempts to detect and

include/linux/hardirq.h

View file
diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h
index 6f657d7..7803014 100644
--- a/include/linux/hardirq.h
+++ b/include/linux/hardirq.h
@@ -106,6 +106,16 @@ static inline void account_system_vtime(struct task_struct *tsk)
* always balanced, so the interrupted value of ->hardirq_context
* will always be restored.
*/
+#define __irq_enter() \
+ do { \
+ account_system_vtime(current); \
+ add_preempt_count(HARDIRQ_OFFSET); \
+ trace_hardirq_enter(); \
+ } while (0)
+
+/*
+ * Enter irq context (on NO_HZ, update jiffies):
+ */
extern void irq_enter(void);
/*
@@ -123,7 +133,7 @@ extern void irq_enter(void);
*/
extern void irq_exit(void);
-#define nmi_enter() do { lockdep_off(); irq_enter(); } while (0)
+#define nmi_enter() do { lockdep_off(); __irq_enter(); } while (0)
#define nmi_exit() do { __irq_exit(); lockdep_on(); } while (0)
#endif /* LINUX_HARDIRQ_H */

include/linux/hrtimer.h

View file
diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index a759636..e95c96c 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -201,4 +201,10 @@ extern void hrtimer_run_queues(void);
/* Bootup initialization: */
extern void __init hrtimers_init(void);
+#if BITS_PER_LONG < 64
+extern unsigned long ktime_divns(const ktime_t kt, s64 div);
+#else /* BITS_PER_LONG < 64 */
+# define ktime_divns(kt, div) (unsigned long)((kt).tv64 / (div))
+#endif
+
#endif

include/linux/tick.h

View file
diff --git a/include/linux/tick.h b/include/linux/tick.h
index e5c0a4e..cf435e4 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -20,12 +20,79 @@ struct tick_device {
enum tick_device_mode mode;
};
+enum tick_nohz_mode {
+ NOHZ_MODE_INACTIVE,
+ NOHZ_MODE_LOWRES,
+ NOHZ_MODE_HIGHRES,
+};
+
+/**
+ * struct tick_sched - sched tick emulation and no idle tick control/stats
+ * @sched_timer: hrtimer to schedule the periodic tick in high
+ * resolution mode
+ * @idle_tick: Store the last idle tick expiry time when the tick
+ * timer is modified for idle sleeps. This is necessary
+ * to resume the tick timer operation in the timeline
+ * when the CPU returns from idle
+ * @tick_stopped: Indicator that the idle tick has been stopped
+ * @idle_jiffies: jiffies at the entry to idle for idle time accounting
+ * @idle_calls: Total number of idle calls
+ * @idle_sleeps: Number of idle calls, where the sched tick was stopped
+ * @idle_entrytime: Time when the idle call was entered
+ * @idle_sleeptime: Sum of the time slept in idle with sched tick stopped
+ */
+struct tick_sched {
+ struct hrtimer sched_timer;
+ unsigned long check_clocks;
+ enum tick_nohz_mode nohz_mode;
+ ktime_t idle_tick;
+ int tick_stopped;
+ unsigned long idle_jiffies;
+ unsigned long idle_calls;
+ unsigned long idle_sleeps;
+ ktime_t idle_entrytime;
+ ktime_t idle_sleeptime;
+ unsigned long last_jiffies;
+ unsigned long next_jiffies;
+ ktime_t idle_expires;
+};
+
extern void __init tick_init(void);
+extern int tick_is_oneshot_available(void);
+
+# ifdef CONFIG_HIGH_RES_TIMERS
+extern int tick_init_highres(void);
+extern int tick_program_event(ktime_t expires, int force);
+extern void tick_setup_sched_timer(void);
+extern void tick_cancel_sched_timer(int cpu);
+# else
+static inline void tick_cancel_sched_timer(int cpu) { }
+# endif /* HIGHRES */
-#else
+# ifdef CONFIG_TICK_ONESHOT
+extern void tick_clock_notify(void);
+extern int tick_check_oneshot_change(int allow_nohz);
+extern struct tick_sched *tick_get_tick_sched(int cpu);
+# else
+static inline void tick_clock_notify(void) { }
+static inline int tick_check_oneshot_change(int allow_nohz) { return 0; }
+# endif
+#else /* CONFIG_GENERIC_CLOCKEVENTS */
static inline void tick_init(void) { }
+static inline void tick_cancel_sched_timer(int cpu) { }
+static inline void tick_clock_notify(void) { }
+static inline int tick_check_oneshot_change(int allow_nohz) { return 0; }
+#endif /* !CONFIG_GENERIC_CLOCKEVENTS */
-#endif
+# ifdef CONFIG_NO_HZ
+extern void tick_nohz_stop_sched_tick(void);
+extern void tick_nohz_restart_sched_tick(void);
+extern void tick_nohz_update_jiffies(void);
+# else
+static inline void tick_nohz_stop_sched_tick(void) { }
+static inline void tick_nohz_restart_sched_tick(void) { }
+static inline void tick_nohz_update_jiffies(void) { }
+# endif /* !NO_HZ */
#endif

kernel/hrtimer.c

View file
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index a2310d1..e04ef38 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -2,8 +2,8 @@
* linux/kernel/hrtimer.c
*
* Copyright(C) 2005-2006, Thomas Gleixner <[email protected]>
- * Copyright(C) 2005-2006, Red Hat, Inc., Ingo Molnar
- * Copyright(C) 2006 Timesys Corp., Thomas Gleixner <[email protected]>
+ * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
+ * Copyright(C) 2006-2007 Timesys Corp., Thomas Gleixner <[email protected]>
*
* High-resolution kernel timers
*
@@ -38,6 +38,7 @@
#include <linux/notifier.h>
#include <linux/syscalls.h>
#include <linux/interrupt.h>
+#include <linux/tick.h>
#include <asm/uaccess.h>
@@ -288,7 +289,7 @@ ktime_t ktime_add_ns(const ktime_t kt, u64 nsec)
/*
* Divide a ktime value by a nanosecond value
*/
-static unsigned long ktime_divns(const ktime_t kt, s64 div)
+unsigned long ktime_divns(const ktime_t kt, s64 div)
{
u64 dclc, inc, dns;
int sft = 0;
@@ -305,9 +306,6 @@ static unsigned long ktime_divns(const ktime_t kt, s64 div)
return (unsigned long) dclc;
}
-
-#else /* BITS_PER_LONG < 64 */
-# define ktime_divns(kt, div) (unsigned long)((kt).tv64 / (div))
#endif /* BITS_PER_LONG >= 64 */
/*
@@ -682,6 +680,16 @@ void hrtimer_run_queues(void)
struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
int i;
+ /*
+ * This _is_ ugly: We have to check in the softirq context,
+ * whether we can switch to highres and / or nohz mode. The
+ * clocksource switch happens in the timer interrupt with
+ * xtime_lock held. Notification from there only sets the
+ * check bit in the tick_oneshot code, otherwise we might
+ * deadlock vs. xtime_lock.
+ */
+ tick_check_oneshot_change(1);
+
hrtimer_get_softirq_time(cpu_base);
for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++)

kernel/softirq.c

View file
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 14e1a14..8b75008 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -17,6 +17,7 @@
#include <linux/kthread.h>
#include <linux/rcupdate.h>
#include <linux/smp.h>
+#include <linux/tick.h>
#include <asm/irq.h>
/*
@@ -278,9 +279,11 @@ EXPORT_SYMBOL(do_softirq);
*/
void irq_enter(void)
{
- account_system_vtime(current);
- add_preempt_count(HARDIRQ_OFFSET);
- trace_hardirq_enter();
+ __irq_enter();
+#ifdef CONFIG_NO_HZ
+ if (idle_cpu(smp_processor_id()))
+ tick_nohz_update_jiffies();
+#endif
}
#ifdef __ARCH_IRQ_EXIT_IRQS_DISABLED
@@ -299,6 +302,12 @@ void irq_exit(void)
sub_preempt_count(IRQ_EXIT_OFFSET);
if (!in_interrupt() && local_softirq_pending())
invoke_softirq();
+
+#ifdef CONFIG_NO_HZ
+ /* Make sure that timer wheel updates are propagated */
+ if (!in_interrupt() && idle_cpu(smp_processor_id()) && !need_resched())
+ tick_nohz_stop_sched_tick();
+#endif
preempt_enable_no_resched();
}

kernel/time/Kconfig

View file
diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig
new file mode 100644
index 0000000..9ec54eb
--- /dev/null
+++ b/kernel/time/Kconfig
@@ -0,0 +1,15 @@
+#
+# Timer subsystem related configuration options
+#
+config TICK_ONESHOT
+ bool
+ default n
+
+config NO_HZ
+ bool "Tickless System (Dynamic Ticks)"
+ depends on GENERIC_TIME && GENERIC_CLOCKEVENTS
+ select TICK_ONESHOT
+ help
+ This option enables a tickless system: timer interrupts will
+ only trigger on an as-needed basis both when the system is
+ busy and when the system is idle.

kernel/time/Makefile

View file
diff --git a/kernel/time/Makefile b/kernel/time/Makefile
index a941743..f246bc8 100644
--- a/kernel/time/Makefile
+++ b/kernel/time/Makefile
@@ -3,3 +3,5 @@ obj-y += ntp.o clocksource.o jiffies.o
obj-$(CONFIG_GENERIC_CLOCKEVENTS) += clockevents.o
obj-$(CONFIG_GENERIC_CLOCKEVENTS) += tick-common.o
obj-$(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST) += tick-broadcast.o
+obj-$(CONFIG_TICK_ONESHOT) += tick-oneshot.o
+obj-$(CONFIG_TICK_ONESHOT) += tick-sched.o

kernel/time/clocksource.c

View file
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 3cb8ac9..193a079 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -29,6 +29,7 @@
#include <linux/init.h>
#include <linux/module.h>
#include <linux/sched.h> /* for spin_unlock_irq() using preempt_count() m68k */
+#include <linux/tick.h>
/* XXX - Would like a better way for initializing curr_clocksource */
extern struct clocksource clocksource_jiffies;
@@ -109,6 +110,13 @@ static void clocksource_watchdog(unsigned long data)
if ((cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) &&
(watchdog->flags & CLOCK_SOURCE_IS_CONTINUOUS)) {
cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES;
+ /*
+ * We just marked the clocksource as
+ * highres-capable, notify the rest of the
+ * system as well so that we transition
+ * into high-res mode:
+ */
+ tick_clock_notify();
}
cs->flags |= CLOCK_SOURCE_WATCHDOG;
cs->wd_last = csnow;

kernel/time/tick-broadcast.c

View file
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index 0ee4968..8314ecb 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -29,7 +29,7 @@
struct tick_device tick_broadcast_device;
static cpumask_t tick_broadcast_mask;
-DEFINE_SPINLOCK(tick_broadcast_lock);
+static DEFINE_SPINLOCK(tick_broadcast_lock);
/*
* Start the device in periodic mode
@@ -215,6 +215,8 @@ static void tick_do_broadcast_on_off(void *why)
else {
if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
tick_broadcast_start_periodic(bc);
+ else
+ tick_broadcast_setup_oneshot(bc);
}
out:
spin_unlock_irqrestore(&tick_broadcast_lock, flags);
@@ -268,3 +270,190 @@ void tick_shutdown_broadcast(unsigned int *cpup)
spin_unlock_irqrestore(&tick_broadcast_lock, flags);
}
+
+#ifdef CONFIG_TICK_ONESHOT
+
+static cpumask_t tick_broadcast_oneshot_mask;
+
+static int tick_broadcast_set_event(ktime_t expires, int force)
+{
+ struct clock_event_device *bc = tick_broadcast_device.evtdev;
+ ktime_t now = ktime_get();
+ int res;
+
+ for(;;) {
+ res = clockevents_program_event(bc, expires, now);
+ if (!res || !force)
+ return res;
+ now = ktime_get();
+ expires = ktime_add(now, ktime_set(0, bc->min_delta_ns));
+ }
+}
+
+/*
+ * Reprogram the broadcast device:
+ *
+ * Called with tick_broadcast_lock held and interrupts disabled.
+ */
+static int tick_broadcast_reprogram(void)
+{
+ ktime_t expires = { .tv64 = KTIME_MAX };
+ struct tick_device *td;
+ int cpu;
+
+ /*
+ * Find the event which expires next:
+ */
+ for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS;
+ cpu = next_cpu(cpu, tick_broadcast_oneshot_mask)) {
+ td = &per_cpu(tick_cpu_device, cpu);
+ if (td->evtdev->next_event.tv64 < expires.tv64)
+ expires = td->evtdev->next_event;
+ }
+
+ if (expires.tv64 == KTIME_MAX)
+ return 0;
+
+ return tick_broadcast_set_event(expires, 0);
+}
+
+/*
+ * Handle oneshot mode broadcasting
+ */
+static void tick_handle_oneshot_broadcast(struct clock_event_device *dev)
+{
+ struct tick_device *td;
+ cpumask_t mask;
+ ktime_t now;
+ int cpu;
+
+ spin_lock(&tick_broadcast_lock);
+again:
+ dev->next_event.tv64 = KTIME_MAX;
+ mask = CPU_MASK_NONE;
+ now = ktime_get();
+ /* Find all expired events */
+ for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS;
+ cpu = next_cpu(cpu, tick_broadcast_oneshot_mask)) {
+ td = &per_cpu(tick_cpu_device, cpu);
+ if (td->evtdev->next_event.tv64 <= now.tv64)
+ cpu_set(cpu, mask);
+ }
+
+ /*
+ * Wakeup the cpus which have an expired event. The broadcast
+ * device is reprogrammed in the return from idle code.
+ */
+ if (!tick_do_broadcast(mask)) {
+ /*
+ * The global event did not expire any CPU local
+ * events. This happens in dyntick mode, as the
+ * maximum PIT delta is quite small.
+ */
+ if (tick_broadcast_reprogram())
+ goto again;
+ }
+ spin_unlock(&tick_broadcast_lock);
+}
+
+/*
+ * Powerstate information: The system enters/leaves a state, where
+ * affected devices might stop
+ */
+void tick_broadcast_oneshot_control(unsigned long reason)
+{
+ struct clock_event_device *bc, *dev;
+ struct tick_device *td;
+ unsigned long flags;
+ int cpu;
+
+ spin_lock_irqsave(&tick_broadcast_lock, flags);
+
+ /*
+ * Periodic mode does not care about the enter/exit of power
+ * states
+ */
+ if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
+ goto out;
+
+ bc = tick_broadcast_device.evtdev;
+ cpu = smp_processor_id();
+ td = &per_cpu(tick_cpu_device, cpu);
+ dev = td->evtdev;
+
+ if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
+ goto out;
+
+ if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) {
+ if (!cpu_isset(cpu, tick_broadcast_oneshot_mask)) {
+ cpu_set(cpu, tick_broadcast_oneshot_mask);
+ clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);
+ if (dev->next_event.tv64 < bc->next_event.tv64)
+ tick_broadcast_set_event(dev->next_event, 1);
+ }
+ } else {
+ if (cpu_isset(cpu, tick_broadcast_oneshot_mask)) {
+ cpu_clear(cpu, tick_broadcast_oneshot_mask);
+ clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
+ if (dev->next_event.tv64 != KTIME_MAX)
+ tick_program_event(dev->next_event, 1);
+ }
+ }
+
+out:
+ spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+}
+
+/**
+ * tick_broadcast_setup_highres - setup the broadcast device for highres
+ */
+void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
+{
+ if (bc->mode != CLOCK_EVT_MODE_ONESHOT) {
+ bc->event_handler = tick_handle_oneshot_broadcast;
+ clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
+ bc->next_event.tv64 = KTIME_MAX;
+ }
+}
+
+/*
+ * Select oneshot operating mode for the broadcast device
+ */
+void tick_broadcast_switch_to_oneshot(void)
+{
+ struct clock_event_device *bc;
+ unsigned long flags;
+
+ spin_lock_irqsave(&tick_broadcast_lock, flags);
+
+ tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
+ bc = tick_broadcast_device.evtdev;
+ if (bc)
+ tick_broadcast_setup_oneshot(bc);
+ spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+}
+
+
+/*
+ * Remove a dead CPU from broadcasting
+ */
+void tick_shutdown_broadcast_oneshot(unsigned int *cpup)
+{
+ struct clock_event_device *bc;
+ unsigned long flags;
+ unsigned int cpu = *cpup;
+
+ spin_lock_irqsave(&tick_broadcast_lock, flags);
+
+ bc = tick_broadcast_device.evtdev;
+ cpu_clear(cpu, tick_broadcast_oneshot_mask);
+
+ if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT) {
+ if (bc && cpus_empty(tick_broadcast_oneshot_mask))
+ clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
+ }
+
+ spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+}
+
+#endif

kernel/time/tick-common.c

View file
diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index 48167a6..c35d449 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -34,6 +34,16 @@ ktime_t tick_period;
static int tick_do_timer_cpu = -1;
DEFINE_SPINLOCK(tick_device_lock);
+/**
+ * tick_is_oneshot_available - check for a oneshot capable event device
+ */
+int tick_is_oneshot_available(void)
+{
+ struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev;
+
+ return dev && (dev->features & CLOCK_EVT_FEAT_ONESHOT);
+}
+
/*
* Periodic tick
*/
@@ -162,6 +172,8 @@ static void tick_setup_device(struct tick_device *td,
if (td->mode == TICKDEV_MODE_PERIODIC)
tick_setup_periodic(newdev, 0);
+ else
+ tick_setup_oneshot(newdev, handler, next_event);
}
/*
@@ -209,6 +221,12 @@ static int tick_check_new_device(struct clock_event_device *newdev)
*/
if (curdev) {
/*
+ * Prefer one shot capable devices !
+ */
+ if ((curdev->features & CLOCK_EVT_FEAT_ONESHOT) &&
+ !(newdev->features & CLOCK_EVT_FEAT_ONESHOT))
+ goto out_bc;
+ /*
* Check the rating
*/
if (curdev->rating >= newdev->rating)
@@ -226,6 +244,8 @@ static int tick_check_new_device(struct clock_event_device *newdev)
}
clockevents_exchange_device(curdev, newdev);
tick_setup_device(td, newdev, cpu, cpumask);
+ if (newdev->features & CLOCK_EVT_FEAT_ONESHOT)
+ tick_oneshot_notify();
spin_unlock_irqrestore(&tick_device_lock, flags);
return NOTIFY_STOP;
@@ -285,7 +305,13 @@ static int tick_notify(struct notifier_block *nb, unsigned long reason,
tick_broadcast_on_off(reason, dev);
break;
+ case CLOCK_EVT_NOTIFY_BROADCAST_ENTER:
+ case CLOCK_EVT_NOTIFY_BROADCAST_EXIT:
+ tick_broadcast_oneshot_control(reason);
+ break;
+
case CLOCK_EVT_NOTIFY_CPU_DEAD:
+ tick_shutdown_broadcast_oneshot(dev);
tick_shutdown_broadcast(dev);
tick_shutdown(dev);
break;

kernel/time/tick-internal.h

View file
diff --git a/kernel/time/tick-internal.h b/kernel/time/tick-internal.h
index 9272f44..54861a0 100644
--- a/kernel/time/tick-internal.h
+++ b/kernel/time/tick-internal.h
@@ -10,12 +10,57 @@ extern void tick_setup_periodic(struct clock_event_device *dev, int broadcast);
extern void tick_handle_periodic(struct clock_event_device *dev);
/*
+ * NO_HZ / high resolution timer shared code
+ */
+#ifdef CONFIG_TICK_ONESHOT
+extern void tick_setup_oneshot(struct clock_event_device *newdev,
+ void (*handler)(struct clock_event_device *),
+ ktime_t nextevt);
+extern int tick_program_event(ktime_t expires, int force);
+extern void tick_oneshot_notify(void);
+extern int tick_switch_to_oneshot(void (*handler)(struct clock_event_device *));
+
+# ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST

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kernel/time/tick-oneshot.c

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kernel/time/tick-sched.c

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kernel/timer.c

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