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>
23 #include <linux/percpu.h>
26 struct hrtimer_clock_base
;
27 struct hrtimer_cpu_base
;
30 * Mode arguments of xxx_hrtimer functions:
33 HRTIMER_MODE_ABS
, /* Time value is absolute */
34 HRTIMER_MODE_REL
, /* Time value is relative to now */
38 * Return values for the callback function
40 enum hrtimer_restart
{
41 HRTIMER_NORESTART
, /* Timer is not restarted */
42 HRTIMER_RESTART
, /* Timer must be restarted */
46 * hrtimer callback modes:
48 * HRTIMER_CB_SOFTIRQ: Callback must run in softirq context
49 * HRTIMER_CB_IRQSAFE: Callback may run in hardirq context
50 * HRTIMER_CB_IRQSAFE_NO_RESTART: Callback may run in hardirq context and
51 * does not restart the timer
52 * HRTIMER_CB_IRQSAFE_PERCPU: Callback must run in hardirq context
53 * Special mode for tick emulation and
54 * scheduler timer. Such timers are per
55 * cpu and not allowed to be migrated on
57 * HRTIMER_CB_IRQSAFE_UNLOCKED: Callback should run in hardirq context
58 * with timer->base lock unlocked
59 * used for timers which call wakeup to
60 * avoid lock order problems with rq->lock
62 enum hrtimer_cb_mode
{
65 HRTIMER_CB_IRQSAFE_NO_RESTART
,
66 HRTIMER_CB_IRQSAFE_PERCPU
,
67 HRTIMER_CB_IRQSAFE_UNLOCKED
,
71 * Values to track state of the timer
76 * 0x01 enqueued into rbtree
77 * 0x02 callback function running
78 * 0x04 callback pending (high resolution mode)
81 * 0x03 callback function running and enqueued
82 * (was requeued on another CPU)
83 * 0x09 timer was migrated on CPU hotunplug
84 * The "callback function running and enqueued" status is only possible on
85 * SMP. It happens for example when a posix timer expired and the callback
86 * queued a signal. Between dropping the lock which protects the posix timer
87 * and reacquiring the base lock of the hrtimer, another CPU can deliver the
88 * signal and rearm the timer. We have to preserve the callback running state,
89 * as otherwise the timer could be removed before the softirq code finishes the
90 * the handling of the timer.
92 * The HRTIMER_STATE_ENQUEUED bit is always or'ed to the current state to
93 * preserve the HRTIMER_STATE_CALLBACK bit in the above scenario.
95 * All state transitions are protected by cpu_base->lock.
97 #define HRTIMER_STATE_INACTIVE 0x00
98 #define HRTIMER_STATE_ENQUEUED 0x01
99 #define HRTIMER_STATE_CALLBACK 0x02
100 #define HRTIMER_STATE_PENDING 0x04
101 #define HRTIMER_STATE_MIGRATE 0x08
104 * struct hrtimer - the basic hrtimer structure
105 * @node: red black tree node for time ordered insertion
106 * @expires: the absolute expiry time in the hrtimers internal
107 * representation. The time is related to the clock on
108 * which the timer is based.
109 * @function: timer expiry callback function
110 * @base: pointer to the timer base (per cpu and per clock)
111 * @state: state information (See bit values above)
112 * @cb_mode: high resolution timer feature to select the callback execution
114 * @cb_entry: list head to enqueue an expired timer into the callback list
115 * @start_site: timer statistics field to store the site where the timer
117 * @start_comm: timer statistics field to store the name of the process which
119 * @start_pid: timer statistics field to store the pid of the task which
122 * The hrtimer structure must be initialized by hrtimer_init()
127 ktime_t _softexpires
;
128 enum hrtimer_restart (*function
)(struct hrtimer
*);
129 struct hrtimer_clock_base
*base
;
131 enum hrtimer_cb_mode cb_mode
;
132 struct list_head cb_entry
;
133 #ifdef CONFIG_TIMER_STATS
141 * struct hrtimer_sleeper - simple sleeper structure
142 * @timer: embedded timer structure
143 * @task: task to wake up
145 * task is set to NULL, when the timer expires.
147 struct hrtimer_sleeper
{
148 struct hrtimer timer
;
149 struct task_struct
*task
;
153 * struct hrtimer_clock_base - the timer base for a specific clock
154 * @cpu_base: per cpu clock base
155 * @index: clock type index for per_cpu support when moving a
156 * timer to a base on another cpu.
157 * @active: red black tree root node for the active timers
158 * @first: pointer to the timer node which expires first
159 * @resolution: the resolution of the clock, in nanoseconds
160 * @get_time: function to retrieve the current time of the clock
161 * @get_softirq_time: function to retrieve the current time from the softirq
162 * @softirq_time: the time when running the hrtimer queue in the softirq
163 * @offset: offset of this clock to the monotonic base
164 * @reprogram: function to reprogram the timer event
166 struct hrtimer_clock_base
{
167 struct hrtimer_cpu_base
*cpu_base
;
169 struct rb_root active
;
170 struct rb_node
*first
;
172 ktime_t (*get_time
)(void);
173 ktime_t (*get_softirq_time
)(void);
174 ktime_t softirq_time
;
175 #ifdef CONFIG_HIGH_RES_TIMERS
177 int (*reprogram
)(struct hrtimer
*t
,
178 struct hrtimer_clock_base
*b
,
183 #define HRTIMER_MAX_CLOCK_BASES 2
186 * struct hrtimer_cpu_base - the per cpu clock bases
187 * @lock: lock protecting the base and associated clock bases
189 * @clock_base: array of clock bases for this cpu
190 * @curr_timer: the timer which is executing a callback right now
191 * @expires_next: absolute time of the next event which was scheduled
192 * via clock_set_next_event()
193 * @hres_active: State of high resolution mode
194 * @check_clocks: Indictator, when set evaluate time source and clock
195 * event devices whether high resolution mode can be
197 * @cb_pending: Expired timers are moved from the rbtree to this
198 * list in the timer interrupt. The list is processed
200 * @nr_events: Total number of timer interrupt events
202 struct hrtimer_cpu_base
{
204 struct hrtimer_clock_base clock_base
[HRTIMER_MAX_CLOCK_BASES
];
205 struct list_head cb_pending
;
206 #ifdef CONFIG_HIGH_RES_TIMERS
207 ktime_t expires_next
;
209 unsigned long nr_events
;
213 static inline void hrtimer_set_expires(struct hrtimer
*timer
, ktime_t time
)
215 timer
->_expires
= time
;
216 timer
->_softexpires
= time
;
219 static inline void hrtimer_set_expires_range(struct hrtimer
*timer
, ktime_t time
, ktime_t delta
)
221 timer
->_softexpires
= time
;
222 timer
->_expires
= ktime_add_safe(time
, delta
);
225 static inline void hrtimer_set_expires_range_ns(struct hrtimer
*timer
, ktime_t time
, unsigned long delta
)
227 timer
->_softexpires
= time
;
228 timer
->_expires
= ktime_add_safe(time
, ns_to_ktime(delta
));
231 static inline void hrtimer_set_expires_tv64(struct hrtimer
*timer
, s64 tv64
)
233 timer
->_expires
.tv64
= tv64
;
234 timer
->_softexpires
.tv64
= tv64
;
237 static inline void hrtimer_add_expires(struct hrtimer
*timer
, ktime_t time
)
239 timer
->_expires
= ktime_add_safe(timer
->_expires
, time
);
240 timer
->_softexpires
= ktime_add_safe(timer
->_softexpires
, time
);
243 static inline void hrtimer_add_expires_ns(struct hrtimer
*timer
, unsigned long ns
)
245 timer
->_expires
= ktime_add_ns(timer
->_expires
, ns
);
246 timer
->_softexpires
= ktime_add_ns(timer
->_softexpires
, ns
);
249 static inline ktime_t
hrtimer_get_expires(const struct hrtimer
*timer
)
251 return timer
->_expires
;
254 static inline ktime_t
hrtimer_get_softexpires(const struct hrtimer
*timer
)
256 return timer
->_softexpires
;
259 static inline s64
hrtimer_get_expires_tv64(const struct hrtimer
*timer
)
261 return timer
->_expires
.tv64
;
263 static inline s64
hrtimer_get_softexpires_tv64(const struct hrtimer
*timer
)
265 return timer
->_softexpires
.tv64
;
268 static inline s64
hrtimer_get_expires_ns(const struct hrtimer
*timer
)
270 return ktime_to_ns(timer
->_expires
);
273 static inline ktime_t
hrtimer_expires_remaining(const struct hrtimer
*timer
)
275 return ktime_sub(timer
->_expires
, timer
->base
->get_time());
278 #ifdef CONFIG_HIGH_RES_TIMERS
279 struct clock_event_device
;
281 extern void clock_was_set(void);
282 extern void hres_timers_resume(void);
283 extern void hrtimer_interrupt(struct clock_event_device
*dev
);
286 * In high resolution mode the time reference must be read accurate
288 static inline ktime_t
hrtimer_cb_get_time(struct hrtimer
*timer
)
290 return timer
->base
->get_time();
293 static inline int hrtimer_is_hres_active(struct hrtimer
*timer
)
295 return timer
->base
->cpu_base
->hres_active
;
298 extern void hrtimer_peek_ahead_timers(void);
301 * The resolution of the clocks. The resolution value is returned in
302 * the clock_getres() system call to give application programmers an
303 * idea of the (in)accuracy of timers. Timer values are rounded up to
304 * this resolution values.
306 # define HIGH_RES_NSEC 1
307 # define KTIME_HIGH_RES (ktime_t) { .tv64 = HIGH_RES_NSEC }
308 # define MONOTONIC_RES_NSEC HIGH_RES_NSEC
309 # define KTIME_MONOTONIC_RES KTIME_HIGH_RES
313 # define MONOTONIC_RES_NSEC LOW_RES_NSEC
314 # define KTIME_MONOTONIC_RES KTIME_LOW_RES
317 * clock_was_set() is a NOP for non- high-resolution systems. The
318 * time-sorted order guarantees that a timer does not expire early and
319 * is expired in the next softirq when the clock was advanced.
321 static inline void clock_was_set(void) { }
322 static inline void hrtimer_peek_ahead_timers(void) { }
324 static inline void hres_timers_resume(void) { }
327 * In non high resolution mode the time reference is taken from
328 * the base softirq time variable.
330 static inline ktime_t
hrtimer_cb_get_time(struct hrtimer
*timer
)
332 return timer
->base
->softirq_time
;
335 static inline int hrtimer_is_hres_active(struct hrtimer
*timer
)
341 extern ktime_t
ktime_get(void);
342 extern ktime_t
ktime_get_real(void);
345 DECLARE_PER_CPU(struct tick_device
, tick_cpu_device
);
348 /* Exported timer functions: */
350 /* Initialize timers: */
351 extern void hrtimer_init(struct hrtimer
*timer
, clockid_t which_clock
,
352 enum hrtimer_mode mode
);
354 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
355 extern void hrtimer_init_on_stack(struct hrtimer
*timer
, clockid_t which_clock
,
356 enum hrtimer_mode mode
);
358 extern void destroy_hrtimer_on_stack(struct hrtimer
*timer
);
360 static inline void hrtimer_init_on_stack(struct hrtimer
*timer
,
361 clockid_t which_clock
,
362 enum hrtimer_mode mode
)
364 hrtimer_init(timer
, which_clock
, mode
);
366 static inline void destroy_hrtimer_on_stack(struct hrtimer
*timer
) { }
369 /* Basic timer operations: */
370 extern int hrtimer_start(struct hrtimer
*timer
, ktime_t tim
,
371 const enum hrtimer_mode mode
);
372 extern int hrtimer_start_range_ns(struct hrtimer
*timer
, ktime_t tim
,
373 unsigned long range_ns
, const enum hrtimer_mode mode
);
374 extern int hrtimer_cancel(struct hrtimer
*timer
);
375 extern int hrtimer_try_to_cancel(struct hrtimer
*timer
);
377 static inline int hrtimer_start_expires(struct hrtimer
*timer
,
378 enum hrtimer_mode mode
)
382 soft
= hrtimer_get_softexpires(timer
);
383 hard
= hrtimer_get_expires(timer
);
384 delta
= ktime_to_ns(ktime_sub(hard
, soft
));
385 return hrtimer_start_range_ns(timer
, soft
, delta
, mode
);
388 static inline int hrtimer_restart(struct hrtimer
*timer
)
390 return hrtimer_start_expires(timer
, HRTIMER_MODE_ABS
);
394 extern ktime_t
hrtimer_get_remaining(const struct hrtimer
*timer
);
395 extern int hrtimer_get_res(const clockid_t which_clock
, struct timespec
*tp
);
397 extern ktime_t
hrtimer_get_next_event(void);
400 * A timer is active, when it is enqueued into the rbtree or the callback
401 * function is running.
403 static inline int hrtimer_active(const struct hrtimer
*timer
)
405 return timer
->state
!= HRTIMER_STATE_INACTIVE
;
409 * Helper function to check, whether the timer is on one of the queues
411 static inline int hrtimer_is_queued(struct hrtimer
*timer
)
413 return timer
->state
&
414 (HRTIMER_STATE_ENQUEUED
| HRTIMER_STATE_PENDING
);
418 * Helper function to check, whether the timer is running the callback
421 static inline int hrtimer_callback_running(struct hrtimer
*timer
)
423 return timer
->state
& HRTIMER_STATE_CALLBACK
;
426 /* Forward a hrtimer so it expires after now: */
428 hrtimer_forward(struct hrtimer
*timer
, ktime_t now
, ktime_t interval
);
430 /* Forward a hrtimer so it expires after the hrtimer's current now */
431 static inline u64
hrtimer_forward_now(struct hrtimer
*timer
,
434 return hrtimer_forward(timer
, timer
->base
->get_time(), interval
);
438 extern long hrtimer_nanosleep(struct timespec
*rqtp
,
439 struct timespec __user
*rmtp
,
440 const enum hrtimer_mode mode
,
441 const clockid_t clockid
);
442 extern long hrtimer_nanosleep_restart(struct restart_block
*restart_block
);
444 extern void hrtimer_init_sleeper(struct hrtimer_sleeper
*sl
,
445 struct task_struct
*tsk
);
447 extern int schedule_hrtimeout_range(ktime_t
*expires
, unsigned long delta
,
448 const enum hrtimer_mode mode
);
449 extern int schedule_hrtimeout(ktime_t
*expires
, const enum hrtimer_mode mode
);
451 /* Soft interrupt function to run the hrtimer queues: */
452 extern void hrtimer_run_queues(void);
453 extern void hrtimer_run_pending(void);
455 /* Bootup initialization: */
456 extern void __init
hrtimers_init(void);
458 #if BITS_PER_LONG < 64
459 extern u64
ktime_divns(const ktime_t kt
, s64 div
);
460 #else /* BITS_PER_LONG < 64 */
461 # define ktime_divns(kt, div) (u64)((kt).tv64 / (div))
464 /* Show pending timers: */
465 extern void sysrq_timer_list_show(void);
468 * Timer-statistics info:
470 #ifdef CONFIG_TIMER_STATS
472 extern void timer_stats_update_stats(void *timer
, pid_t pid
, void *startf
,
473 void *timerf
, char *comm
,
474 unsigned int timer_flag
);
476 static inline void timer_stats_account_hrtimer(struct hrtimer
*timer
)
478 timer_stats_update_stats(timer
, timer
->start_pid
, timer
->start_site
,
479 timer
->function
, timer
->start_comm
, 0);
482 extern void __timer_stats_hrtimer_set_start_info(struct hrtimer
*timer
,
485 static inline void timer_stats_hrtimer_set_start_info(struct hrtimer
*timer
)
487 __timer_stats_hrtimer_set_start_info(timer
, __builtin_return_address(0));
490 static inline void timer_stats_hrtimer_clear_start_info(struct hrtimer
*timer
)
492 timer
->start_site
= NULL
;
495 static inline void timer_stats_account_hrtimer(struct hrtimer
*timer
)
499 static inline void timer_stats_hrtimer_set_start_info(struct hrtimer
*timer
)
503 static inline void timer_stats_hrtimer_clear_start_info(struct hrtimer
*timer
)