2 * include/linux/hrtimer.h
4 * hrtimers - High-resolution kernel timers
6 * Copyright(C) 2005, Thomas Gleixner <tglx@linutronix.de>
7 * Copyright(C) 2005, Red Hat, Inc., Ingo Molnar
9 * data type definitions, declarations, prototypes
11 * Started by: Thomas Gleixner and Ingo Molnar
13 * For licencing details see kernel-base/COPYING
15 #ifndef _LINUX_HRTIMER_H
16 #define _LINUX_HRTIMER_H
18 #include <linux/rbtree.h>
19 #include <linux/ktime.h>
20 #include <linux/init.h>
21 #include <linux/list.h>
22 #include <linux/wait.h>
24 struct hrtimer_clock_base;
25 struct hrtimer_cpu_base;
28 * Mode arguments of xxx_hrtimer functions:
31 HRTIMER_MODE_ABS, /* Time value is absolute */
32 HRTIMER_MODE_REL, /* Time value is relative to now */
36 * Return values for the callback function
38 enum hrtimer_restart {
39 HRTIMER_NORESTART, /* Timer is not restarted */
40 HRTIMER_RESTART, /* Timer must be restarted */
44 * hrtimer callback modes:
46 * HRTIMER_CB_SOFTIRQ: Callback must run in softirq context
47 * HRTIMER_CB_IRQSAFE: Callback may run in hardirq context
48 * HRTIMER_CB_IRQSAFE_NO_RESTART: Callback may run in hardirq context and
49 * does not restart the timer
50 * HRTIMER_CB_IRQSAFE_PERCPU: Callback must run in hardirq context
51 * Special mode for tick emulation and
52 * scheduler timer. Such timers are per
53 * cpu and not allowed to be migrated on
55 * HRTIMER_CB_IRQSAFE_UNLOCKED: Callback should run in hardirq context
56 * with timer->base lock unlocked
57 * used for timers which call wakeup to
58 * avoid lock order problems with rq->lock
60 enum hrtimer_cb_mode {
63 HRTIMER_CB_IRQSAFE_NO_RESTART,
64 HRTIMER_CB_IRQSAFE_PERCPU,
65 HRTIMER_CB_IRQSAFE_UNLOCKED,
69 * Values to track state of the timer
74 * 0x01 enqueued into rbtree
75 * 0x02 callback function running
76 * 0x04 callback pending (high resolution mode)
79 * 0x03 callback function running and enqueued
80 * (was requeued on another CPU)
81 * 0x09 timer was migrated on CPU hotunplug
82 * The "callback function running and enqueued" status is only possible on
83 * SMP. It happens for example when a posix timer expired and the callback
84 * queued a signal. Between dropping the lock which protects the posix timer
85 * and reacquiring the base lock of the hrtimer, another CPU can deliver the
86 * signal and rearm the timer. We have to preserve the callback running state,
87 * as otherwise the timer could be removed before the softirq code finishes the
88 * the handling of the timer.
90 * The HRTIMER_STATE_ENQUEUED bit is always or'ed to the current state to
91 * preserve the HRTIMER_STATE_CALLBACK bit in the above scenario.
93 * All state transitions are protected by cpu_base->lock.
95 #define HRTIMER_STATE_INACTIVE 0x00
96 #define HRTIMER_STATE_ENQUEUED 0x01
97 #define HRTIMER_STATE_CALLBACK 0x02
98 #define HRTIMER_STATE_PENDING 0x04
99 #define HRTIMER_STATE_MIGRATE 0x08
102 * struct hrtimer - the basic hrtimer structure
103 * @node: red black tree node for time ordered insertion
104 * @expires: the absolute expiry time in the hrtimers internal
105 * representation. The time is related to the clock on
106 * which the timer is based.
107 * @function: timer expiry callback function
108 * @base: pointer to the timer base (per cpu and per clock)
109 * @state: state information (See bit values above)
110 * @cb_mode: high resolution timer feature to select the callback execution
112 * @cb_entry: list head to enqueue an expired timer into the callback list
113 * @start_site: timer statistics field to store the site where the timer
115 * @start_comm: timer statistics field to store the name of the process which
117 * @start_pid: timer statistics field to store the pid of the task which
120 * The hrtimer structure must be initialized by hrtimer_init()
125 enum hrtimer_restart (*function)(struct hrtimer *);
126 struct hrtimer_clock_base *base;
128 struct list_head cb_entry;
129 enum hrtimer_cb_mode cb_mode;
130 #ifdef CONFIG_TIMER_STATS
138 * struct hrtimer_sleeper - simple sleeper structure
139 * @timer: embedded timer structure
140 * @task: task to wake up
142 * task is set to NULL, when the timer expires.
144 struct hrtimer_sleeper {
145 struct hrtimer timer;
146 struct task_struct *task;
150 * struct hrtimer_clock_base - the timer base for a specific clock
151 * @cpu_base: per cpu clock base
152 * @index: clock type index for per_cpu support when moving a
153 * timer to a base on another cpu.
154 * @active: red black tree root node for the active timers
155 * @first: pointer to the timer node which expires first
156 * @resolution: the resolution of the clock, in nanoseconds
157 * @get_time: function to retrieve the current time of the clock
158 * @softirq_time: the time when running the hrtimer queue in the softirq
159 * @offset: offset of this clock to the monotonic base
161 struct hrtimer_clock_base {
162 struct hrtimer_cpu_base *cpu_base;
164 struct rb_root active;
165 struct rb_node *first;
167 ktime_t (*get_time)(void);
168 ktime_t softirq_time;
169 #ifdef CONFIG_HIGH_RES_TIMERS
174 #define HRTIMER_MAX_CLOCK_BASES 2
177 * struct hrtimer_cpu_base - the per cpu clock bases
178 * @lock: lock protecting the base and associated clock bases
180 * @clock_base: array of clock bases for this cpu
181 * @curr_timer: the timer which is executing a callback right now
182 * @expires_next: absolute time of the next event which was scheduled
183 * via clock_set_next_event()
184 * @hres_active: State of high resolution mode
185 * @check_clocks: Indictator, when set evaluate time source and clock
186 * event devices whether high resolution mode can be
188 * @cb_pending: Expired timers are moved from the rbtree to this
189 * list in the timer interrupt. The list is processed
191 * @nr_events: Total number of timer interrupt events
193 struct hrtimer_cpu_base {
195 struct hrtimer_clock_base clock_base[HRTIMER_MAX_CLOCK_BASES];
196 struct list_head cb_pending;
197 #ifdef CONFIG_HIGH_RES_TIMERS
198 ktime_t expires_next;
200 unsigned long nr_events;
204 #ifdef CONFIG_HIGH_RES_TIMERS
205 struct clock_event_device;
207 extern void clock_was_set(void);
208 extern void hres_timers_resume(void);
209 extern void hrtimer_interrupt(struct clock_event_device *dev);
212 * In high resolution mode the time reference must be read accurate
214 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
216 return timer->base->get_time();
219 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
221 return timer->base->cpu_base->hres_active;
225 * The resolution of the clocks. The resolution value is returned in
226 * the clock_getres() system call to give application programmers an
227 * idea of the (in)accuracy of timers. Timer values are rounded up to
228 * this resolution values.
230 # define HIGH_RES_NSEC 1
231 # define KTIME_HIGH_RES (ktime_t) { .tv64 = HIGH_RES_NSEC }
232 # define MONOTONIC_RES_NSEC HIGH_RES_NSEC
233 # define KTIME_MONOTONIC_RES KTIME_HIGH_RES
237 # define MONOTONIC_RES_NSEC LOW_RES_NSEC
238 # define KTIME_MONOTONIC_RES KTIME_LOW_RES
241 * clock_was_set() is a NOP for non- high-resolution systems. The
242 * time-sorted order guarantees that a timer does not expire early and
243 * is expired in the next softirq when the clock was advanced.
245 static inline void clock_was_set(void) { }
247 static inline void hres_timers_resume(void) { }
250 * In non high resolution mode the time reference is taken from
251 * the base softirq time variable.
253 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
255 return timer->base->softirq_time;
258 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
264 extern ktime_t ktime_get(void);
265 extern ktime_t ktime_get_real(void);
267 /* Exported timer functions: */
269 /* Initialize timers: */
270 extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
271 enum hrtimer_mode mode);
273 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
274 extern void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t which_clock,
275 enum hrtimer_mode mode);
277 extern void destroy_hrtimer_on_stack(struct hrtimer *timer);
279 static inline void hrtimer_init_on_stack(struct hrtimer *timer,
280 clockid_t which_clock,
281 enum hrtimer_mode mode)
283 hrtimer_init(timer, which_clock, mode);
285 static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { }
288 /* Basic timer operations: */
289 extern int hrtimer_start(struct hrtimer *timer, ktime_t tim,
290 const enum hrtimer_mode mode);
291 extern int hrtimer_cancel(struct hrtimer *timer);
292 extern int hrtimer_try_to_cancel(struct hrtimer *timer);
294 static inline int hrtimer_restart(struct hrtimer *timer)
296 return hrtimer_start(timer, timer->expires, HRTIMER_MODE_ABS);
300 extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
301 extern int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp);
303 extern ktime_t hrtimer_get_next_event(void);
306 * A timer is active, when it is enqueued into the rbtree or the callback
307 * function is running.
309 static inline int hrtimer_active(const struct hrtimer *timer)
311 return timer->state != HRTIMER_STATE_INACTIVE;
315 * Helper function to check, whether the timer is on one of the queues
317 static inline int hrtimer_is_queued(struct hrtimer *timer)
319 return timer->state &
320 (HRTIMER_STATE_ENQUEUED | HRTIMER_STATE_PENDING);
324 * Helper function to check, whether the timer is running the callback
327 static inline int hrtimer_callback_running(struct hrtimer *timer)
329 return timer->state & HRTIMER_STATE_CALLBACK;
332 /* Forward a hrtimer so it expires after now: */
334 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
336 /* Forward a hrtimer so it expires after the hrtimer's current now */
337 static inline u64 hrtimer_forward_now(struct hrtimer *timer,
340 return hrtimer_forward(timer, timer->base->get_time(), interval);
344 extern long hrtimer_nanosleep(struct timespec *rqtp,
345 struct timespec __user *rmtp,
346 const enum hrtimer_mode mode,
347 const clockid_t clockid);
348 extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
350 extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
351 struct task_struct *tsk);
353 /* Soft interrupt function to run the hrtimer queues: */
354 extern void hrtimer_run_queues(void);
355 extern void hrtimer_run_pending(void);
357 /* Bootup initialization: */
358 extern void __init hrtimers_init(void);
360 #if BITS_PER_LONG < 64
361 extern u64 ktime_divns(const ktime_t kt, s64 div);
362 #else /* BITS_PER_LONG < 64 */
363 # define ktime_divns(kt, div) (u64)((kt).tv64 / (div))
366 /* Show pending timers: */
367 extern void sysrq_timer_list_show(void);
370 * Timer-statistics info:
372 #ifdef CONFIG_TIMER_STATS
374 extern void timer_stats_update_stats(void *timer, pid_t pid, void *startf,
375 void *timerf, char *comm,
376 unsigned int timer_flag);
378 static inline void timer_stats_account_hrtimer(struct hrtimer *timer)
380 timer_stats_update_stats(timer, timer->start_pid, timer->start_site,
381 timer->function, timer->start_comm, 0);
384 extern void __timer_stats_hrtimer_set_start_info(struct hrtimer *timer,
387 static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer)
389 __timer_stats_hrtimer_set_start_info(timer, __builtin_return_address(0));
392 static inline void timer_stats_hrtimer_clear_start_info(struct hrtimer *timer)
394 timer->start_site = NULL;
397 static inline void timer_stats_account_hrtimer(struct hrtimer *timer)
401 static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer)
405 static inline void timer_stats_hrtimer_clear_start_info(struct hrtimer *timer)