2 * linux/kernel/hrtimer.c
4 * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
5 * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
6 * Copyright(C) 2006-2007 Timesys Corp., Thomas Gleixner
8 * High-resolution kernel timers
10 * In contrast to the low-resolution timeout API implemented in
11 * kernel/timer.c, hrtimers provide finer resolution and accuracy
12 * depending on system configuration and capabilities.
14 * These timers are currently used for:
18 * - precise in-kernel timing
20 * Started by: Thomas Gleixner and Ingo Molnar
23 * based on kernel/timer.c
25 * Help, testing, suggestions, bugfixes, improvements were
28 * George Anzinger, Andrew Morton, Steven Rostedt, Roman Zippel
31 * For licencing details see kernel-base/COPYING
34 #include <linux/cpu.h>
35 #include <linux/irq.h>
36 #include <linux/module.h>
37 #include <linux/percpu.h>
38 #include <linux/hrtimer.h>
39 #include <linux/notifier.h>
40 #include <linux/syscalls.h>
41 #include <linux/kallsyms.h>
42 #include <linux/interrupt.h>
43 #include <linux/tick.h>
44 #include <linux/seq_file.h>
45 #include <linux/err.h>
47 #include <asm/uaccess.h>
50 * ktime_get - get the monotonic time in ktime_t format
52 * returns the time in ktime_t format
54 ktime_t
ktime_get(void)
60 return timespec_to_ktime(now
);
64 * ktime_get_real - get the real (wall-) time in ktime_t format
66 * returns the time in ktime_t format
68 ktime_t
ktime_get_real(void)
74 return timespec_to_ktime(now
);
77 EXPORT_SYMBOL_GPL(ktime_get_real
);
82 * Note: If we want to add new timer bases, we have to skip the two
83 * clock ids captured by the cpu-timers. We do this by holding empty
84 * entries rather than doing math adjustment of the clock ids.
85 * This ensures that we capture erroneous accesses to these clock ids
86 * rather than moving them into the range of valid clock id's.
88 DEFINE_PER_CPU(struct hrtimer_cpu_base
, hrtimer_bases
) =
94 .index
= CLOCK_REALTIME
,
95 .get_time
= &ktime_get_real
,
96 .resolution
= KTIME_LOW_RES
,
99 .index
= CLOCK_MONOTONIC
,
100 .get_time
= &ktime_get
,
101 .resolution
= KTIME_LOW_RES
,
107 * ktime_get_ts - get the monotonic clock in timespec format
108 * @ts: pointer to timespec variable
110 * The function calculates the monotonic clock from the realtime
111 * clock and the wall_to_monotonic offset and stores the result
112 * in normalized timespec format in the variable pointed to by @ts.
114 void ktime_get_ts(struct timespec
*ts
)
116 struct timespec tomono
;
120 seq
= read_seqbegin(&xtime_lock
);
122 tomono
= wall_to_monotonic
;
124 } while (read_seqretry(&xtime_lock
, seq
));
126 set_normalized_timespec(ts
, ts
->tv_sec
+ tomono
.tv_sec
,
127 ts
->tv_nsec
+ tomono
.tv_nsec
);
129 EXPORT_SYMBOL_GPL(ktime_get_ts
);
132 * Get the coarse grained time at the softirq based on xtime and
135 static void hrtimer_get_softirq_time(struct hrtimer_cpu_base
*base
)
137 ktime_t xtim
, tomono
;
138 struct timespec xts
, tom
;
142 seq
= read_seqbegin(&xtime_lock
);
144 getnstimeofday(&xts
);
148 tom
= wall_to_monotonic
;
149 } while (read_seqretry(&xtime_lock
, seq
));
151 xtim
= timespec_to_ktime(xts
);
152 tomono
= timespec_to_ktime(tom
);
153 base
->clock_base
[CLOCK_REALTIME
].softirq_time
= xtim
;
154 base
->clock_base
[CLOCK_MONOTONIC
].softirq_time
=
155 ktime_add(xtim
, tomono
);
159 * Helper function to check, whether the timer is running the callback
162 static inline int hrtimer_callback_running(struct hrtimer
*timer
)
164 return timer
->state
& HRTIMER_STATE_CALLBACK
;
168 * Functions and macros which are different for UP/SMP systems are kept in a
174 * We are using hashed locking: holding per_cpu(hrtimer_bases)[n].lock
175 * means that all timers which are tied to this base via timer->base are
176 * locked, and the base itself is locked too.
178 * So __run_timers/migrate_timers can safely modify all timers which could
179 * be found on the lists/queues.
181 * When the timer's base is locked, and the timer removed from list, it is
182 * possible to set timer->base = NULL and drop the lock: the timer remains
186 struct hrtimer_clock_base
*lock_hrtimer_base(const struct hrtimer
*timer
,
187 unsigned long *flags
)
189 struct hrtimer_clock_base
*base
;
193 if (likely(base
!= NULL
)) {
194 spin_lock_irqsave(&base
->cpu_base
->lock
, *flags
);
195 if (likely(base
== timer
->base
))
197 /* The timer has migrated to another CPU: */
198 spin_unlock_irqrestore(&base
->cpu_base
->lock
, *flags
);
205 * Switch the timer base to the current CPU when possible.
207 static inline struct hrtimer_clock_base
*
208 switch_hrtimer_base(struct hrtimer
*timer
, struct hrtimer_clock_base
*base
)
210 struct hrtimer_clock_base
*new_base
;
211 struct hrtimer_cpu_base
*new_cpu_base
;
213 new_cpu_base
= &__get_cpu_var(hrtimer_bases
);
214 new_base
= &new_cpu_base
->clock_base
[base
->index
];
216 if (base
!= new_base
) {
218 * We are trying to schedule the timer on the local CPU.
219 * However we can't change timer's base while it is running,
220 * so we keep it on the same CPU. No hassle vs. reprogramming
221 * the event source in the high resolution case. The softirq
222 * code will take care of this when the timer function has
223 * completed. There is no conflict as we hold the lock until
224 * the timer is enqueued.
226 if (unlikely(hrtimer_callback_running(timer
)))
229 /* See the comment in lock_timer_base() */
231 spin_unlock(&base
->cpu_base
->lock
);
232 spin_lock(&new_base
->cpu_base
->lock
);
233 timer
->base
= new_base
;
238 #else /* CONFIG_SMP */
240 static inline struct hrtimer_clock_base
*
241 lock_hrtimer_base(const struct hrtimer
*timer
, unsigned long *flags
)
243 struct hrtimer_clock_base
*base
= timer
->base
;
245 spin_lock_irqsave(&base
->cpu_base
->lock
, *flags
);
250 # define switch_hrtimer_base(t, b) (b)
252 #endif /* !CONFIG_SMP */
255 * Functions for the union type storage format of ktime_t which are
256 * too large for inlining:
258 #if BITS_PER_LONG < 64
259 # ifndef CONFIG_KTIME_SCALAR
261 * ktime_add_ns - Add a scalar nanoseconds value to a ktime_t variable
263 * @nsec: the scalar nsec value to add
265 * Returns the sum of kt and nsec in ktime_t format
267 ktime_t
ktime_add_ns(const ktime_t kt
, u64 nsec
)
271 if (likely(nsec
< NSEC_PER_SEC
)) {
274 unsigned long rem
= do_div(nsec
, NSEC_PER_SEC
);
276 tmp
= ktime_set((long)nsec
, rem
);
279 return ktime_add(kt
, tmp
);
281 # endif /* !CONFIG_KTIME_SCALAR */
284 * Divide a ktime value by a nanosecond value
286 unsigned long ktime_divns(const ktime_t kt
, s64 div
)
291 dclc
= dns
= ktime_to_ns(kt
);
293 /* Make sure the divisor is less than 2^32: */
299 do_div(dclc
, (unsigned long) div
);
301 return (unsigned long) dclc
;
303 #endif /* BITS_PER_LONG >= 64 */
305 /* High resolution timer related functions */
306 #ifdef CONFIG_HIGH_RES_TIMERS
309 * High resolution timer enabled ?
311 static int hrtimer_hres_enabled __read_mostly
= 1;
314 * Enable / Disable high resolution mode
316 static int __init
setup_hrtimer_hres(char *str
)
318 if (!strcmp(str
, "off"))
319 hrtimer_hres_enabled
= 0;
320 else if (!strcmp(str
, "on"))
321 hrtimer_hres_enabled
= 1;
327 __setup("highres=", setup_hrtimer_hres
);
330 * hrtimer_high_res_enabled - query, if the highres mode is enabled
332 static inline int hrtimer_is_hres_enabled(void)
334 return hrtimer_hres_enabled
;
338 * Is the high resolution mode active ?
340 static inline int hrtimer_hres_active(void)
342 return __get_cpu_var(hrtimer_bases
).hres_active
;
346 * Reprogram the event source with checking both queues for the
348 * Called with interrupts disabled and base->lock held
350 static void hrtimer_force_reprogram(struct hrtimer_cpu_base
*cpu_base
)
353 struct hrtimer_clock_base
*base
= cpu_base
->clock_base
;
356 cpu_base
->expires_next
.tv64
= KTIME_MAX
;
358 for (i
= 0; i
< HRTIMER_MAX_CLOCK_BASES
; i
++, base
++) {
359 struct hrtimer
*timer
;
363 timer
= rb_entry(base
->first
, struct hrtimer
, node
);
364 expires
= ktime_sub(timer
->expires
, base
->offset
);
365 if (expires
.tv64
< cpu_base
->expires_next
.tv64
)
366 cpu_base
->expires_next
= expires
;
369 if (cpu_base
->expires_next
.tv64
!= KTIME_MAX
)
370 tick_program_event(cpu_base
->expires_next
, 1);
374 * Shared reprogramming for clock_realtime and clock_monotonic
376 * When a timer is enqueued and expires earlier than the already enqueued
377 * timers, we have to check, whether it expires earlier than the timer for
378 * which the clock event device was armed.
380 * Called with interrupts disabled and base->cpu_base.lock held
382 static int hrtimer_reprogram(struct hrtimer
*timer
,
383 struct hrtimer_clock_base
*base
)
385 ktime_t
*expires_next
= &__get_cpu_var(hrtimer_bases
).expires_next
;
386 ktime_t expires
= ktime_sub(timer
->expires
, base
->offset
);
390 * When the callback is running, we do not reprogram the clock event
391 * device. The timer callback is either running on a different CPU or
392 * the callback is executed in the hrtimer_interupt context. The
393 * reprogramming is handled either by the softirq, which called the
394 * callback or at the end of the hrtimer_interrupt.
396 if (hrtimer_callback_running(timer
))
399 if (expires
.tv64
>= expires_next
->tv64
)
403 * Clockevents returns -ETIME, when the event was in the past.
405 res
= tick_program_event(expires
, 0);
406 if (!IS_ERR_VALUE(res
))
407 *expires_next
= expires
;
413 * Retrigger next event is called after clock was set
415 * Called with interrupts disabled via on_each_cpu()
417 static void retrigger_next_event(void *arg
)
419 struct hrtimer_cpu_base
*base
;
420 struct timespec realtime_offset
;
423 if (!hrtimer_hres_active())
427 seq
= read_seqbegin(&xtime_lock
);
428 set_normalized_timespec(&realtime_offset
,
429 -wall_to_monotonic
.tv_sec
,
430 -wall_to_monotonic
.tv_nsec
);
431 } while (read_seqretry(&xtime_lock
, seq
));
433 base
= &__get_cpu_var(hrtimer_bases
);
435 /* Adjust CLOCK_REALTIME offset */
436 spin_lock(&base
->lock
);
437 base
->clock_base
[CLOCK_REALTIME
].offset
=
438 timespec_to_ktime(realtime_offset
);
440 hrtimer_force_reprogram(base
);
441 spin_unlock(&base
->lock
);
445 * Clock realtime was set
447 * Change the offset of the realtime clock vs. the monotonic
450 * We might have to reprogram the high resolution timer interrupt. On
451 * SMP we call the architecture specific code to retrigger _all_ high
452 * resolution timer interrupts. On UP we just disable interrupts and
453 * call the high resolution interrupt code.
455 void clock_was_set(void)
457 /* Retrigger the CPU local events everywhere */
458 on_each_cpu(retrigger_next_event
, NULL
, 0, 1);
462 * Check, whether the timer is on the callback pending list
464 static inline int hrtimer_cb_pending(const struct hrtimer
*timer
)
466 return timer
->state
& HRTIMER_STATE_PENDING
;
470 * Remove a timer from the callback pending list
472 static inline void hrtimer_remove_cb_pending(struct hrtimer
*timer
)
474 list_del_init(&timer
->cb_entry
);
478 * Initialize the high resolution related parts of cpu_base
480 static inline void hrtimer_init_hres(struct hrtimer_cpu_base
*base
)
482 base
->expires_next
.tv64
= KTIME_MAX
;
483 base
->hres_active
= 0;
484 INIT_LIST_HEAD(&base
->cb_pending
);
488 * Initialize the high resolution related parts of a hrtimer
490 static inline void hrtimer_init_timer_hres(struct hrtimer
*timer
)
492 INIT_LIST_HEAD(&timer
->cb_entry
);
496 * When High resolution timers are active, try to reprogram. Note, that in case
497 * the state has HRTIMER_STATE_CALLBACK set, no reprogramming and no expiry
498 * check happens. The timer gets enqueued into the rbtree. The reprogramming
499 * and expiry check is done in the hrtimer_interrupt or in the softirq.
501 static inline int hrtimer_enqueue_reprogram(struct hrtimer
*timer
,
502 struct hrtimer_clock_base
*base
)
504 if (base
->cpu_base
->hres_active
&& hrtimer_reprogram(timer
, base
)) {
506 /* Timer is expired, act upon the callback mode */
507 switch(timer
->cb_mode
) {
508 case HRTIMER_CB_IRQSAFE_NO_RESTART
:
510 * We can call the callback from here. No restart
511 * happens, so no danger of recursion
513 BUG_ON(timer
->function(timer
) != HRTIMER_NORESTART
);
515 case HRTIMER_CB_IRQSAFE_NO_SOFTIRQ
:
517 * This is solely for the sched tick emulation with
518 * dynamic tick support to ensure that we do not
519 * restart the tick right on the edge and end up with
520 * the tick timer in the softirq ! The calling site
521 * takes care of this.
524 case HRTIMER_CB_IRQSAFE
:
525 case HRTIMER_CB_SOFTIRQ
:
527 * Move everything else into the softirq pending list !
529 list_add_tail(&timer
->cb_entry
,
530 &base
->cpu_base
->cb_pending
);
531 timer
->state
= HRTIMER_STATE_PENDING
;
532 raise_softirq(HRTIMER_SOFTIRQ
);
542 * Switch to high resolution mode
544 static int hrtimer_switch_to_hres(void)
546 struct hrtimer_cpu_base
*base
= &__get_cpu_var(hrtimer_bases
);
549 if (base
->hres_active
)
552 local_irq_save(flags
);
554 if (tick_init_highres()) {
555 local_irq_restore(flags
);
558 base
->hres_active
= 1;
559 base
->clock_base
[CLOCK_REALTIME
].resolution
= KTIME_HIGH_RES
;
560 base
->clock_base
[CLOCK_MONOTONIC
].resolution
= KTIME_HIGH_RES
;
562 tick_setup_sched_timer();
564 /* "Retrigger" the interrupt to get things going */
565 retrigger_next_event(NULL
);
566 local_irq_restore(flags
);
567 printk(KERN_INFO
"Switched to high resolution mode on CPU %d\n",
574 static inline int hrtimer_hres_active(void) { return 0; }
575 static inline int hrtimer_is_hres_enabled(void) { return 0; }
576 static inline int hrtimer_switch_to_hres(void) { return 0; }
577 static inline void hrtimer_force_reprogram(struct hrtimer_cpu_base
*base
) { }
578 static inline int hrtimer_enqueue_reprogram(struct hrtimer
*timer
,
579 struct hrtimer_clock_base
*base
)
583 static inline int hrtimer_cb_pending(struct hrtimer
*timer
) { return 0; }
584 static inline void hrtimer_remove_cb_pending(struct hrtimer
*timer
) { }
585 static inline void hrtimer_init_hres(struct hrtimer_cpu_base
*base
) { }
586 static inline void hrtimer_init_timer_hres(struct hrtimer
*timer
) { }
588 #endif /* CONFIG_HIGH_RES_TIMERS */
590 #ifdef CONFIG_TIMER_STATS
591 void __timer_stats_hrtimer_set_start_info(struct hrtimer
*timer
, void *addr
)
593 if (timer
->start_site
)
596 timer
->start_site
= addr
;
597 memcpy(timer
->start_comm
, current
->comm
, TASK_COMM_LEN
);
598 timer
->start_pid
= current
->pid
;
603 * Counterpart to lock_timer_base above:
606 void unlock_hrtimer_base(const struct hrtimer
*timer
, unsigned long *flags
)
608 spin_unlock_irqrestore(&timer
->base
->cpu_base
->lock
, *flags
);
612 * hrtimer_forward - forward the timer expiry
613 * @timer: hrtimer to forward
614 * @now: forward past this time
615 * @interval: the interval to forward
617 * Forward the timer expiry so it will expire in the future.
618 * Returns the number of overruns.
621 hrtimer_forward(struct hrtimer
*timer
, ktime_t now
, ktime_t interval
)
623 unsigned long orun
= 1;
626 delta
= ktime_sub(now
, timer
->expires
);
631 if (interval
.tv64
< timer
->base
->resolution
.tv64
)
632 interval
.tv64
= timer
->base
->resolution
.tv64
;
634 if (unlikely(delta
.tv64
>= interval
.tv64
)) {
635 s64 incr
= ktime_to_ns(interval
);
637 orun
= ktime_divns(delta
, incr
);
638 timer
->expires
= ktime_add_ns(timer
->expires
, incr
* orun
);
639 if (timer
->expires
.tv64
> now
.tv64
)
642 * This (and the ktime_add() below) is the
643 * correction for exact:
647 timer
->expires
= ktime_add(timer
->expires
, interval
);
649 * Make sure, that the result did not wrap with a very large
652 if (timer
->expires
.tv64
< 0)
653 timer
->expires
= ktime_set(KTIME_SEC_MAX
, 0);
659 * enqueue_hrtimer - internal function to (re)start a timer
661 * The timer is inserted in expiry order. Insertion into the
662 * red black tree is O(log(n)). Must hold the base lock.
664 static void enqueue_hrtimer(struct hrtimer
*timer
,
665 struct hrtimer_clock_base
*base
, int reprogram
)
667 struct rb_node
**link
= &base
->active
.rb_node
;
668 struct rb_node
*parent
= NULL
;
669 struct hrtimer
*entry
;
672 * Find the right place in the rbtree:
676 entry
= rb_entry(parent
, struct hrtimer
, node
);
678 * We dont care about collisions. Nodes with
679 * the same expiry time stay together.
681 if (timer
->expires
.tv64
< entry
->expires
.tv64
)
682 link
= &(*link
)->rb_left
;
684 link
= &(*link
)->rb_right
;
688 * Insert the timer to the rbtree and check whether it
689 * replaces the first pending timer
691 if (!base
->first
|| timer
->expires
.tv64
<
692 rb_entry(base
->first
, struct hrtimer
, node
)->expires
.tv64
) {
694 * Reprogram the clock event device. When the timer is already
695 * expired hrtimer_enqueue_reprogram has either called the
696 * callback or added it to the pending list and raised the
699 * This is a NOP for !HIGHRES
701 if (reprogram
&& hrtimer_enqueue_reprogram(timer
, base
))
704 base
->first
= &timer
->node
;
707 rb_link_node(&timer
->node
, parent
, link
);
708 rb_insert_color(&timer
->node
, &base
->active
);
710 * HRTIMER_STATE_ENQUEUED is or'ed to the current state to preserve the
711 * state of a possibly running callback.
713 timer
->state
|= HRTIMER_STATE_ENQUEUED
;
717 * __remove_hrtimer - internal function to remove a timer
719 * Caller must hold the base lock.
721 * High resolution timer mode reprograms the clock event device when the
722 * timer is the one which expires next. The caller can disable this by setting
723 * reprogram to zero. This is useful, when the context does a reprogramming
724 * anyway (e.g. timer interrupt)
726 static void __remove_hrtimer(struct hrtimer
*timer
,
727 struct hrtimer_clock_base
*base
,
728 unsigned long newstate
, int reprogram
)
730 /* High res. callback list. NOP for !HIGHRES */
731 if (hrtimer_cb_pending(timer
))
732 hrtimer_remove_cb_pending(timer
);
735 * Remove the timer from the rbtree and replace the
736 * first entry pointer if necessary.
738 if (base
->first
== &timer
->node
) {
739 base
->first
= rb_next(&timer
->node
);
740 /* Reprogram the clock event device. if enabled */
741 if (reprogram
&& hrtimer_hres_active())
742 hrtimer_force_reprogram(base
->cpu_base
);
744 rb_erase(&timer
->node
, &base
->active
);
746 timer
->state
= newstate
;
750 * remove hrtimer, called with base lock held
753 remove_hrtimer(struct hrtimer
*timer
, struct hrtimer_clock_base
*base
)
755 if (hrtimer_is_queued(timer
)) {
759 * Remove the timer and force reprogramming when high
760 * resolution mode is active and the timer is on the current
761 * CPU. If we remove a timer on another CPU, reprogramming is
762 * skipped. The interrupt event on this CPU is fired and
763 * reprogramming happens in the interrupt handler. This is a
764 * rare case and less expensive than a smp call.
766 timer_stats_hrtimer_clear_start_info(timer
);
767 reprogram
= base
->cpu_base
== &__get_cpu_var(hrtimer_bases
);
768 __remove_hrtimer(timer
, base
, HRTIMER_STATE_INACTIVE
,
776 * hrtimer_start - (re)start an relative timer on the current CPU
777 * @timer: the timer to be added
779 * @mode: expiry mode: absolute (HRTIMER_ABS) or relative (HRTIMER_REL)
783 * 1 when the timer was active
786 hrtimer_start(struct hrtimer
*timer
, ktime_t tim
, const enum hrtimer_mode mode
)
788 struct hrtimer_clock_base
*base
, *new_base
;
792 base
= lock_hrtimer_base(timer
, &flags
);
794 /* Remove an active timer from the queue: */
795 ret
= remove_hrtimer(timer
, base
);
797 /* Switch the timer base, if necessary: */
798 new_base
= switch_hrtimer_base(timer
, base
);
800 if (mode
== HRTIMER_MODE_REL
) {
801 tim
= ktime_add(tim
, new_base
->get_time());
803 * CONFIG_TIME_LOW_RES is a temporary way for architectures
804 * to signal that they simply return xtime in
805 * do_gettimeoffset(). In this case we want to round up by
806 * resolution when starting a relative timer, to avoid short
807 * timeouts. This will go away with the GTOD framework.
809 #ifdef CONFIG_TIME_LOW_RES
810 tim
= ktime_add(tim
, base
->resolution
);
813 timer
->expires
= tim
;
815 timer_stats_hrtimer_set_start_info(timer
);
817 enqueue_hrtimer(timer
, new_base
, base
== new_base
);
819 unlock_hrtimer_base(timer
, &flags
);
823 EXPORT_SYMBOL_GPL(hrtimer_start
);
826 * hrtimer_try_to_cancel - try to deactivate a timer
827 * @timer: hrtimer to stop
830 * 0 when the timer was not active
831 * 1 when the timer was active
832 * -1 when the timer is currently excuting the callback function and
835 int hrtimer_try_to_cancel(struct hrtimer
*timer
)
837 struct hrtimer_clock_base
*base
;
841 base
= lock_hrtimer_base(timer
, &flags
);
843 if (!hrtimer_callback_running(timer
))
844 ret
= remove_hrtimer(timer
, base
);
846 unlock_hrtimer_base(timer
, &flags
);
851 EXPORT_SYMBOL_GPL(hrtimer_try_to_cancel
);
854 * hrtimer_cancel - cancel a timer and wait for the handler to finish.
855 * @timer: the timer to be cancelled
858 * 0 when the timer was not active
859 * 1 when the timer was active
861 int hrtimer_cancel(struct hrtimer
*timer
)
864 int ret
= hrtimer_try_to_cancel(timer
);
871 EXPORT_SYMBOL_GPL(hrtimer_cancel
);
874 * hrtimer_get_remaining - get remaining time for the timer
875 * @timer: the timer to read
877 ktime_t
hrtimer_get_remaining(const struct hrtimer
*timer
)
879 struct hrtimer_clock_base
*base
;
883 base
= lock_hrtimer_base(timer
, &flags
);
884 rem
= ktime_sub(timer
->expires
, base
->get_time());
885 unlock_hrtimer_base(timer
, &flags
);
889 EXPORT_SYMBOL_GPL(hrtimer_get_remaining
);
891 #if defined(CONFIG_NO_IDLE_HZ) || defined(CONFIG_NO_HZ)
893 * hrtimer_get_next_event - get the time until next expiry event
895 * Returns the delta to the next expiry event or KTIME_MAX if no timer
898 ktime_t
hrtimer_get_next_event(void)
900 struct hrtimer_cpu_base
*cpu_base
= &__get_cpu_var(hrtimer_bases
);
901 struct hrtimer_clock_base
*base
= cpu_base
->clock_base
;
902 ktime_t delta
, mindelta
= { .tv64
= KTIME_MAX
};
906 spin_lock_irqsave(&cpu_base
->lock
, flags
);
908 if (!hrtimer_hres_active()) {
909 for (i
= 0; i
< HRTIMER_MAX_CLOCK_BASES
; i
++, base
++) {
910 struct hrtimer
*timer
;
915 timer
= rb_entry(base
->first
, struct hrtimer
, node
);
916 delta
.tv64
= timer
->expires
.tv64
;
917 delta
= ktime_sub(delta
, base
->get_time());
918 if (delta
.tv64
< mindelta
.tv64
)
919 mindelta
.tv64
= delta
.tv64
;
923 spin_unlock_irqrestore(&cpu_base
->lock
, flags
);
925 if (mindelta
.tv64
< 0)
932 * hrtimer_init - initialize a timer to the given clock
933 * @timer: the timer to be initialized
934 * @clock_id: the clock to be used
935 * @mode: timer mode abs/rel
937 void hrtimer_init(struct hrtimer
*timer
, clockid_t clock_id
,
938 enum hrtimer_mode mode
)
940 struct hrtimer_cpu_base
*cpu_base
;
942 memset(timer
, 0, sizeof(struct hrtimer
));
944 cpu_base
= &__raw_get_cpu_var(hrtimer_bases
);
946 if (clock_id
== CLOCK_REALTIME
&& mode
!= HRTIMER_MODE_ABS
)
947 clock_id
= CLOCK_MONOTONIC
;
949 timer
->base
= &cpu_base
->clock_base
[clock_id
];
950 hrtimer_init_timer_hres(timer
);
952 #ifdef CONFIG_TIMER_STATS
953 timer
->start_site
= NULL
;
954 timer
->start_pid
= -1;
955 memset(timer
->start_comm
, 0, TASK_COMM_LEN
);
958 EXPORT_SYMBOL_GPL(hrtimer_init
);
961 * hrtimer_get_res - get the timer resolution for a clock
962 * @which_clock: which clock to query
963 * @tp: pointer to timespec variable to store the resolution
965 * Store the resolution of the clock selected by @which_clock in the
966 * variable pointed to by @tp.
968 int hrtimer_get_res(const clockid_t which_clock
, struct timespec
*tp
)
970 struct hrtimer_cpu_base
*cpu_base
;
972 cpu_base
= &__raw_get_cpu_var(hrtimer_bases
);
973 *tp
= ktime_to_timespec(cpu_base
->clock_base
[which_clock
].resolution
);
977 EXPORT_SYMBOL_GPL(hrtimer_get_res
);
979 #ifdef CONFIG_HIGH_RES_TIMERS
982 * High resolution timer interrupt
983 * Called with interrupts disabled
985 void hrtimer_interrupt(struct clock_event_device
*dev
)
987 struct hrtimer_cpu_base
*cpu_base
= &__get_cpu_var(hrtimer_bases
);
988 struct hrtimer_clock_base
*base
;
989 ktime_t expires_next
, now
;
992 BUG_ON(!cpu_base
->hres_active
);
993 cpu_base
->nr_events
++;
994 dev
->next_event
.tv64
= KTIME_MAX
;
999 expires_next
.tv64
= KTIME_MAX
;
1001 base
= cpu_base
->clock_base
;
1003 for (i
= 0; i
< HRTIMER_MAX_CLOCK_BASES
; i
++) {
1005 struct rb_node
*node
;
1007 spin_lock(&cpu_base
->lock
);
1009 basenow
= ktime_add(now
, base
->offset
);
1011 while ((node
= base
->first
)) {
1012 struct hrtimer
*timer
;
1014 timer
= rb_entry(node
, struct hrtimer
, node
);
1016 if (basenow
.tv64
< timer
->expires
.tv64
) {
1019 expires
= ktime_sub(timer
->expires
,
1021 if (expires
.tv64
< expires_next
.tv64
)
1022 expires_next
= expires
;
1026 /* Move softirq callbacks to the pending list */
1027 if (timer
->cb_mode
== HRTIMER_CB_SOFTIRQ
) {
1028 __remove_hrtimer(timer
, base
,
1029 HRTIMER_STATE_PENDING
, 0);
1030 list_add_tail(&timer
->cb_entry
,
1031 &base
->cpu_base
->cb_pending
);
1036 __remove_hrtimer(timer
, base
,
1037 HRTIMER_STATE_CALLBACK
, 0);
1038 timer_stats_account_hrtimer(timer
);
1041 * Note: We clear the CALLBACK bit after
1042 * enqueue_hrtimer to avoid reprogramming of
1043 * the event hardware. This happens at the end
1044 * of this function anyway.
1046 if (timer
->function(timer
) != HRTIMER_NORESTART
) {
1047 BUG_ON(timer
->state
!= HRTIMER_STATE_CALLBACK
);
1048 enqueue_hrtimer(timer
, base
, 0);
1050 timer
->state
&= ~HRTIMER_STATE_CALLBACK
;
1052 spin_unlock(&cpu_base
->lock
);
1056 cpu_base
->expires_next
= expires_next
;
1058 /* Reprogramming necessary ? */
1059 if (expires_next
.tv64
!= KTIME_MAX
) {
1060 if (tick_program_event(expires_next
, 0))
1064 /* Raise softirq ? */
1066 raise_softirq(HRTIMER_SOFTIRQ
);
1069 static void run_hrtimer_softirq(struct softirq_action
*h
)
1071 struct hrtimer_cpu_base
*cpu_base
= &__get_cpu_var(hrtimer_bases
);
1073 spin_lock_irq(&cpu_base
->lock
);
1075 while (!list_empty(&cpu_base
->cb_pending
)) {
1076 enum hrtimer_restart (*fn
)(struct hrtimer
*);
1077 struct hrtimer
*timer
;
1080 timer
= list_entry(cpu_base
->cb_pending
.next
,
1081 struct hrtimer
, cb_entry
);
1083 timer_stats_account_hrtimer(timer
);
1085 fn
= timer
->function
;
1086 __remove_hrtimer(timer
, timer
->base
, HRTIMER_STATE_CALLBACK
, 0);
1087 spin_unlock_irq(&cpu_base
->lock
);
1089 restart
= fn(timer
);
1091 spin_lock_irq(&cpu_base
->lock
);
1093 timer
->state
&= ~HRTIMER_STATE_CALLBACK
;
1094 if (restart
== HRTIMER_RESTART
) {
1095 BUG_ON(hrtimer_active(timer
));
1097 * Enqueue the timer, allow reprogramming of the event
1100 enqueue_hrtimer(timer
, timer
->base
, 1);
1101 } else if (hrtimer_active(timer
)) {
1103 * If the timer was rearmed on another CPU, reprogram
1106 if (timer
->base
->first
== &timer
->node
)
1107 hrtimer_reprogram(timer
, timer
->base
);
1110 spin_unlock_irq(&cpu_base
->lock
);
1113 #endif /* CONFIG_HIGH_RES_TIMERS */
1116 * Expire the per base hrtimer-queue:
1118 static inline void run_hrtimer_queue(struct hrtimer_cpu_base
*cpu_base
,
1121 struct rb_node
*node
;
1122 struct hrtimer_clock_base
*base
= &cpu_base
->clock_base
[index
];
1127 if (base
->get_softirq_time
)
1128 base
->softirq_time
= base
->get_softirq_time();
1130 spin_lock_irq(&cpu_base
->lock
);
1132 while ((node
= base
->first
)) {
1133 struct hrtimer
*timer
;
1134 enum hrtimer_restart (*fn
)(struct hrtimer
*);
1137 timer
= rb_entry(node
, struct hrtimer
, node
);
1138 if (base
->softirq_time
.tv64
<= timer
->expires
.tv64
)
1141 #ifdef CONFIG_HIGH_RES_TIMERS
1142 WARN_ON_ONCE(timer
->cb_mode
== HRTIMER_CB_IRQSAFE_NO_SOFTIRQ
);
1144 timer_stats_account_hrtimer(timer
);
1146 fn
= timer
->function
;
1147 __remove_hrtimer(timer
, base
, HRTIMER_STATE_CALLBACK
, 0);
1148 spin_unlock_irq(&cpu_base
->lock
);
1150 restart
= fn(timer
);
1152 spin_lock_irq(&cpu_base
->lock
);
1154 timer
->state
&= ~HRTIMER_STATE_CALLBACK
;
1155 if (restart
!= HRTIMER_NORESTART
) {
1156 BUG_ON(hrtimer_active(timer
));
1157 enqueue_hrtimer(timer
, base
, 0);
1160 spin_unlock_irq(&cpu_base
->lock
);
1164 * Called from timer softirq every jiffy, expire hrtimers:
1166 * For HRT its the fall back code to run the softirq in the timer
1167 * softirq context in case the hrtimer initialization failed or has
1168 * not been done yet.
1170 void hrtimer_run_queues(void)
1172 struct hrtimer_cpu_base
*cpu_base
= &__get_cpu_var(hrtimer_bases
);
1175 if (hrtimer_hres_active())
1179 * This _is_ ugly: We have to check in the softirq context,
1180 * whether we can switch to highres and / or nohz mode. The
1181 * clocksource switch happens in the timer interrupt with
1182 * xtime_lock held. Notification from there only sets the
1183 * check bit in the tick_oneshot code, otherwise we might
1184 * deadlock vs. xtime_lock.
1186 if (tick_check_oneshot_change(!hrtimer_is_hres_enabled()))
1187 if (hrtimer_switch_to_hres())
1190 hrtimer_get_softirq_time(cpu_base
);
1192 for (i
= 0; i
< HRTIMER_MAX_CLOCK_BASES
; i
++)
1193 run_hrtimer_queue(cpu_base
, i
);
1197 * Sleep related functions:
1199 static enum hrtimer_restart
hrtimer_wakeup(struct hrtimer
*timer
)
1201 struct hrtimer_sleeper
*t
=
1202 container_of(timer
, struct hrtimer_sleeper
, timer
);
1203 struct task_struct
*task
= t
->task
;
1207 wake_up_process(task
);
1209 return HRTIMER_NORESTART
;
1212 void hrtimer_init_sleeper(struct hrtimer_sleeper
*sl
, struct task_struct
*task
)
1214 sl
->timer
.function
= hrtimer_wakeup
;
1216 #ifdef CONFIG_HIGH_RES_TIMERS
1217 sl
->timer
.cb_mode
= HRTIMER_CB_IRQSAFE_NO_RESTART
;
1221 static int __sched
do_nanosleep(struct hrtimer_sleeper
*t
, enum hrtimer_mode mode
)
1223 hrtimer_init_sleeper(t
, current
);
1226 set_current_state(TASK_INTERRUPTIBLE
);
1227 hrtimer_start(&t
->timer
, t
->timer
.expires
, mode
);
1229 if (likely(t
->task
))
1232 hrtimer_cancel(&t
->timer
);
1233 mode
= HRTIMER_MODE_ABS
;
1235 } while (t
->task
&& !signal_pending(current
));
1237 return t
->task
== NULL
;
1240 long __sched
hrtimer_nanosleep_restart(struct restart_block
*restart
)
1242 struct hrtimer_sleeper t
;
1243 struct timespec __user
*rmtp
;
1247 restart
->fn
= do_no_restart_syscall
;
1249 hrtimer_init(&t
.timer
, restart
->arg0
, HRTIMER_MODE_ABS
);
1250 t
.timer
.expires
.tv64
= ((u64
)restart
->arg3
<< 32) | (u64
) restart
->arg2
;
1252 if (do_nanosleep(&t
, HRTIMER_MODE_ABS
))
1255 rmtp
= (struct timespec __user
*) restart
->arg1
;
1257 time
= ktime_sub(t
.timer
.expires
, t
.timer
.base
->get_time());
1260 tu
= ktime_to_timespec(time
);
1261 if (copy_to_user(rmtp
, &tu
, sizeof(tu
)))
1265 restart
->fn
= hrtimer_nanosleep_restart
;
1267 /* The other values in restart are already filled in */
1268 return -ERESTART_RESTARTBLOCK
;
1271 long hrtimer_nanosleep(struct timespec
*rqtp
, struct timespec __user
*rmtp
,
1272 const enum hrtimer_mode mode
, const clockid_t clockid
)
1274 struct restart_block
*restart
;
1275 struct hrtimer_sleeper t
;
1279 hrtimer_init(&t
.timer
, clockid
, mode
);
1280 t
.timer
.expires
= timespec_to_ktime(*rqtp
);
1281 if (do_nanosleep(&t
, mode
))
1284 /* Absolute timers do not update the rmtp value and restart: */
1285 if (mode
== HRTIMER_MODE_ABS
)
1286 return -ERESTARTNOHAND
;
1289 rem
= ktime_sub(t
.timer
.expires
, t
.timer
.base
->get_time());
1292 tu
= ktime_to_timespec(rem
);
1293 if (copy_to_user(rmtp
, &tu
, sizeof(tu
)))
1297 restart
= ¤t_thread_info()->restart_block
;
1298 restart
->fn
= hrtimer_nanosleep_restart
;
1299 restart
->arg0
= (unsigned long) t
.timer
.base
->index
;
1300 restart
->arg1
= (unsigned long) rmtp
;
1301 restart
->arg2
= t
.timer
.expires
.tv64
& 0xFFFFFFFF;
1302 restart
->arg3
= t
.timer
.expires
.tv64
>> 32;
1304 return -ERESTART_RESTARTBLOCK
;
1308 sys_nanosleep(struct timespec __user
*rqtp
, struct timespec __user
*rmtp
)
1312 if (copy_from_user(&tu
, rqtp
, sizeof(tu
)))
1315 if (!timespec_valid(&tu
))
1318 return hrtimer_nanosleep(&tu
, rmtp
, HRTIMER_MODE_REL
, CLOCK_MONOTONIC
);
1322 * Functions related to boot-time initialization:
1324 static void __devinit
init_hrtimers_cpu(int cpu
)
1326 struct hrtimer_cpu_base
*cpu_base
= &per_cpu(hrtimer_bases
, cpu
);
1329 spin_lock_init(&cpu_base
->lock
);
1330 lockdep_set_class(&cpu_base
->lock
, &cpu_base
->lock_key
);
1332 for (i
= 0; i
< HRTIMER_MAX_CLOCK_BASES
; i
++)
1333 cpu_base
->clock_base
[i
].cpu_base
= cpu_base
;
1335 hrtimer_init_hres(cpu_base
);
1338 #ifdef CONFIG_HOTPLUG_CPU
1340 static void migrate_hrtimer_list(struct hrtimer_clock_base
*old_base
,
1341 struct hrtimer_clock_base
*new_base
)
1343 struct hrtimer
*timer
;
1344 struct rb_node
*node
;
1346 while ((node
= rb_first(&old_base
->active
))) {
1347 timer
= rb_entry(node
, struct hrtimer
, node
);
1348 BUG_ON(hrtimer_callback_running(timer
));
1349 __remove_hrtimer(timer
, old_base
, HRTIMER_STATE_INACTIVE
, 0);
1350 timer
->base
= new_base
;
1352 * Enqueue the timer. Allow reprogramming of the event device
1354 enqueue_hrtimer(timer
, new_base
, 1);
1358 static void migrate_hrtimers(int cpu
)
1360 struct hrtimer_cpu_base
*old_base
, *new_base
;
1363 BUG_ON(cpu_online(cpu
));
1364 old_base
= &per_cpu(hrtimer_bases
, cpu
);
1365 new_base
= &get_cpu_var(hrtimer_bases
);
1367 tick_cancel_sched_timer(cpu
);
1369 local_irq_disable();
1370 double_spin_lock(&new_base
->lock
, &old_base
->lock
,
1371 smp_processor_id() < cpu
);
1373 for (i
= 0; i
< HRTIMER_MAX_CLOCK_BASES
; i
++) {
1374 migrate_hrtimer_list(&old_base
->clock_base
[i
],
1375 &new_base
->clock_base
[i
]);
1378 double_spin_unlock(&new_base
->lock
, &old_base
->lock
,
1379 smp_processor_id() < cpu
);
1381 put_cpu_var(hrtimer_bases
);
1383 #endif /* CONFIG_HOTPLUG_CPU */
1385 static int __cpuinit
hrtimer_cpu_notify(struct notifier_block
*self
,
1386 unsigned long action
, void *hcpu
)
1388 long cpu
= (long)hcpu
;
1392 case CPU_UP_PREPARE
:
1393 init_hrtimers_cpu(cpu
);
1396 #ifdef CONFIG_HOTPLUG_CPU
1398 clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DEAD
, &cpu
);
1399 migrate_hrtimers(cpu
);
1410 static struct notifier_block __cpuinitdata hrtimers_nb
= {
1411 .notifier_call
= hrtimer_cpu_notify
,
1414 void __init
hrtimers_init(void)
1416 hrtimer_cpu_notify(&hrtimers_nb
, (unsigned long)CPU_UP_PREPARE
,
1417 (void *)(long)smp_processor_id());
1418 register_cpu_notifier(&hrtimers_nb
);
1419 #ifdef CONFIG_HIGH_RES_TIMERS
1420 open_softirq(HRTIMER_SOFTIRQ
, run_hrtimer_softirq
, NULL
);