4 * Kernel internal timers, kernel timekeeping, basic process system calls
6 * Copyright (C) 1991, 1992 Linus Torvalds
8 * 1997-01-28 Modified by Finn Arne Gangstad to make timers scale better.
10 * 1997-09-10 Updated NTP code according to technical memorandum Jan '96
11 * "A Kernel Model for Precision Timekeeping" by Dave Mills
12 * 1998-12-24 Fixed a xtime SMP race (we need the xtime_lock rw spinlock to
13 * serialize accesses to xtime/lost_ticks).
14 * Copyright (C) 1998 Andrea Arcangeli
15 * 1999-03-10 Improved NTP compatibility by Ulrich Windl
16 * 2002-05-31 Move sys_sysinfo here and make its locking sane, Robert Love
17 * 2000-10-05 Implemented scalable SMP per-CPU timer handling.
18 * Copyright (C) 2000, 2001, 2002 Ingo Molnar
19 * Designed by David S. Miller, Alexey Kuznetsov and Ingo Molnar
22 #include <linux/kernel_stat.h>
23 #include <linux/module.h>
24 #include <linux/interrupt.h>
25 #include <linux/percpu.h>
26 #include <linux/init.h>
28 #include <linux/swap.h>
29 #include <linux/notifier.h>
30 #include <linux/thread_info.h>
31 #include <linux/time.h>
32 #include <linux/jiffies.h>
33 #include <linux/posix-timers.h>
34 #include <linux/cpu.h>
35 #include <linux/syscalls.h>
36 #include <linux/delay.h>
38 #include <asm/uaccess.h>
39 #include <asm/unistd.h>
40 #include <asm/div64.h>
41 #include <asm/timex.h>
44 u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES;
46 EXPORT_SYMBOL(jiffies_64);
49 * per-CPU timer vector definitions:
51 #define TVN_BITS (CONFIG_BASE_SMALL ? 4 : 6)
52 #define TVR_BITS (CONFIG_BASE_SMALL ? 6 : 8)
53 #define TVN_SIZE (1 << TVN_BITS)
54 #define TVR_SIZE (1 << TVR_BITS)
55 #define TVN_MASK (TVN_SIZE - 1)
56 #define TVR_MASK (TVR_SIZE - 1)
58 typedef struct tvec_s {
59 struct list_head vec[TVN_SIZE];
62 typedef struct tvec_root_s {
63 struct list_head vec[TVR_SIZE];
66 struct tvec_t_base_s {
68 struct timer_list *running_timer;
69 unsigned long timer_jiffies;
75 } ____cacheline_aligned_in_smp;
77 typedef struct tvec_t_base_s tvec_base_t;
79 tvec_base_t boot_tvec_bases;
80 EXPORT_SYMBOL(boot_tvec_bases);
81 static DEFINE_PER_CPU(tvec_base_t *, tvec_bases) = &boot_tvec_bases;
84 * __round_jiffies - function to round jiffies to a full second
85 * @j: the time in (absolute) jiffies that should be rounded
86 * @cpu: the processor number on which the timeout will happen
88 * __round_jiffies() rounds an absolute time in the future (in jiffies)
89 * up or down to (approximately) full seconds. This is useful for timers
90 * for which the exact time they fire does not matter too much, as long as
91 * they fire approximately every X seconds.
93 * By rounding these timers to whole seconds, all such timers will fire
94 * at the same time, rather than at various times spread out. The goal
95 * of this is to have the CPU wake up less, which saves power.
97 * The exact rounding is skewed for each processor to avoid all
98 * processors firing at the exact same time, which could lead
99 * to lock contention or spurious cache line bouncing.
101 * The return value is the rounded version of the @j parameter.
103 unsigned long __round_jiffies(unsigned long j, int cpu)
106 unsigned long original = j;
109 * We don't want all cpus firing their timers at once hitting the
110 * same lock or cachelines, so we skew each extra cpu with an extra
111 * 3 jiffies. This 3 jiffies came originally from the mm/ code which
113 * The skew is done by adding 3*cpunr, then round, then subtract this
114 * extra offset again.
121 * If the target jiffie is just after a whole second (which can happen
122 * due to delays of the timer irq, long irq off times etc etc) then
123 * we should round down to the whole second, not up. Use 1/4th second
124 * as cutoff for this rounding as an extreme upper bound for this.
126 if (rem < HZ/4) /* round down */
131 /* now that we have rounded, subtract the extra skew again */
134 if (j <= jiffies) /* rounding ate our timeout entirely; */
138 EXPORT_SYMBOL_GPL(__round_jiffies);
141 * __round_jiffies_relative - function to round jiffies to a full second
142 * @j: the time in (relative) jiffies that should be rounded
143 * @cpu: the processor number on which the timeout will happen
145 * __round_jiffies_relative() rounds a time delta in the future (in jiffies)
146 * up or down to (approximately) full seconds. This is useful for timers
147 * for which the exact time they fire does not matter too much, as long as
148 * they fire approximately every X seconds.
150 * By rounding these timers to whole seconds, all such timers will fire
151 * at the same time, rather than at various times spread out. The goal
152 * of this is to have the CPU wake up less, which saves power.
154 * The exact rounding is skewed for each processor to avoid all
155 * processors firing at the exact same time, which could lead
156 * to lock contention or spurious cache line bouncing.
158 * The return value is the rounded version of the @j parameter.
160 unsigned long __round_jiffies_relative(unsigned long j, int cpu)
163 * In theory the following code can skip a jiffy in case jiffies
164 * increments right between the addition and the later subtraction.
165 * However since the entire point of this function is to use approximate
166 * timeouts, it's entirely ok to not handle that.
168 return __round_jiffies(j + jiffies, cpu) - jiffies;
170 EXPORT_SYMBOL_GPL(__round_jiffies_relative);
173 * round_jiffies - function to round jiffies to a full second
174 * @j: the time in (absolute) jiffies that should be rounded
176 * round_jiffies() rounds an absolute time in the future (in jiffies)
177 * up or down to (approximately) full seconds. This is useful for timers
178 * for which the exact time they fire does not matter too much, as long as
179 * they fire approximately every X seconds.
181 * By rounding these timers to whole seconds, all such timers will fire
182 * at the same time, rather than at various times spread out. The goal
183 * of this is to have the CPU wake up less, which saves power.
185 * The return value is the rounded version of the @j parameter.
187 unsigned long round_jiffies(unsigned long j)
189 return __round_jiffies(j, raw_smp_processor_id());
191 EXPORT_SYMBOL_GPL(round_jiffies);
194 * round_jiffies_relative - function to round jiffies to a full second
195 * @j: the time in (relative) jiffies that should be rounded
197 * round_jiffies_relative() rounds a time delta in the future (in jiffies)
198 * up or down to (approximately) full seconds. This is useful for timers
199 * for which the exact time they fire does not matter too much, as long as
200 * they fire approximately every X seconds.
202 * By rounding these timers to whole seconds, all such timers will fire
203 * at the same time, rather than at various times spread out. The goal
204 * of this is to have the CPU wake up less, which saves power.
206 * The return value is the rounded version of the @j parameter.
208 unsigned long round_jiffies_relative(unsigned long j)
210 return __round_jiffies_relative(j, raw_smp_processor_id());
212 EXPORT_SYMBOL_GPL(round_jiffies_relative);
215 static inline void set_running_timer(tvec_base_t *base,
216 struct timer_list *timer)
219 base->running_timer = timer;
223 static void internal_add_timer(tvec_base_t *base, struct timer_list *timer)
225 unsigned long expires = timer->expires;
226 unsigned long idx = expires - base->timer_jiffies;
227 struct list_head *vec;
229 if (idx < TVR_SIZE) {
230 int i = expires & TVR_MASK;
231 vec = base->tv1.vec + i;
232 } else if (idx < 1 << (TVR_BITS + TVN_BITS)) {
233 int i = (expires >> TVR_BITS) & TVN_MASK;
234 vec = base->tv2.vec + i;
235 } else if (idx < 1 << (TVR_BITS + 2 * TVN_BITS)) {
236 int i = (expires >> (TVR_BITS + TVN_BITS)) & TVN_MASK;
237 vec = base->tv3.vec + i;
238 } else if (idx < 1 << (TVR_BITS + 3 * TVN_BITS)) {
239 int i = (expires >> (TVR_BITS + 2 * TVN_BITS)) & TVN_MASK;
240 vec = base->tv4.vec + i;
241 } else if ((signed long) idx < 0) {
243 * Can happen if you add a timer with expires == jiffies,
244 * or you set a timer to go off in the past
246 vec = base->tv1.vec + (base->timer_jiffies & TVR_MASK);
249 /* If the timeout is larger than 0xffffffff on 64-bit
250 * architectures then we use the maximum timeout:
252 if (idx > 0xffffffffUL) {
254 expires = idx + base->timer_jiffies;
256 i = (expires >> (TVR_BITS + 3 * TVN_BITS)) & TVN_MASK;
257 vec = base->tv5.vec + i;
262 list_add_tail(&timer->entry, vec);
266 * init_timer - initialize a timer.
267 * @timer: the timer to be initialized
269 * init_timer() must be done to a timer prior calling *any* of the
270 * other timer functions.
272 void fastcall init_timer(struct timer_list *timer)
274 timer->entry.next = NULL;
275 timer->base = __raw_get_cpu_var(tvec_bases);
277 EXPORT_SYMBOL(init_timer);
279 static inline void detach_timer(struct timer_list *timer,
282 struct list_head *entry = &timer->entry;
284 __list_del(entry->prev, entry->next);
287 entry->prev = LIST_POISON2;
291 * We are using hashed locking: holding per_cpu(tvec_bases).lock
292 * means that all timers which are tied to this base via timer->base are
293 * locked, and the base itself is locked too.
295 * So __run_timers/migrate_timers can safely modify all timers which could
296 * be found on ->tvX lists.
298 * When the timer's base is locked, and the timer removed from list, it is
299 * possible to set timer->base = NULL and drop the lock: the timer remains
302 static tvec_base_t *lock_timer_base(struct timer_list *timer,
303 unsigned long *flags)
304 __acquires(timer->base->lock)
310 if (likely(base != NULL)) {
311 spin_lock_irqsave(&base->lock, *flags);
312 if (likely(base == timer->base))
314 /* The timer has migrated to another CPU */
315 spin_unlock_irqrestore(&base->lock, *flags);
321 int __mod_timer(struct timer_list *timer, unsigned long expires)
323 tvec_base_t *base, *new_base;
327 BUG_ON(!timer->function);
329 base = lock_timer_base(timer, &flags);
331 if (timer_pending(timer)) {
332 detach_timer(timer, 0);
336 new_base = __get_cpu_var(tvec_bases);
338 if (base != new_base) {
340 * We are trying to schedule the timer on the local CPU.
341 * However we can't change timer's base while it is running,
342 * otherwise del_timer_sync() can't detect that the timer's
343 * handler yet has not finished. This also guarantees that
344 * the timer is serialized wrt itself.
346 if (likely(base->running_timer != timer)) {
347 /* See the comment in lock_timer_base() */
349 spin_unlock(&base->lock);
351 spin_lock(&base->lock);
356 timer->expires = expires;
357 internal_add_timer(base, timer);
358 spin_unlock_irqrestore(&base->lock, flags);
363 EXPORT_SYMBOL(__mod_timer);
366 * add_timer_on - start a timer on a particular CPU
367 * @timer: the timer to be added
368 * @cpu: the CPU to start it on
370 * This is not very scalable on SMP. Double adds are not possible.
372 void add_timer_on(struct timer_list *timer, int cpu)
374 tvec_base_t *base = per_cpu(tvec_bases, cpu);
377 BUG_ON(timer_pending(timer) || !timer->function);
378 spin_lock_irqsave(&base->lock, flags);
380 internal_add_timer(base, timer);
381 spin_unlock_irqrestore(&base->lock, flags);
386 * mod_timer - modify a timer's timeout
387 * @timer: the timer to be modified
388 * @expires: new timeout in jiffies
390 * mod_timer() is a more efficient way to update the expire field of an
391 * active timer (if the timer is inactive it will be activated)
393 * mod_timer(timer, expires) is equivalent to:
395 * del_timer(timer); timer->expires = expires; add_timer(timer);
397 * Note that if there are multiple unserialized concurrent users of the
398 * same timer, then mod_timer() is the only safe way to modify the timeout,
399 * since add_timer() cannot modify an already running timer.
401 * The function returns whether it has modified a pending timer or not.
402 * (ie. mod_timer() of an inactive timer returns 0, mod_timer() of an
403 * active timer returns 1.)
405 int mod_timer(struct timer_list *timer, unsigned long expires)
407 BUG_ON(!timer->function);
410 * This is a common optimization triggered by the
411 * networking code - if the timer is re-modified
412 * to be the same thing then just return:
414 if (timer->expires == expires && timer_pending(timer))
417 return __mod_timer(timer, expires);
420 EXPORT_SYMBOL(mod_timer);
423 * del_timer - deactive a timer.
424 * @timer: the timer to be deactivated
426 * del_timer() deactivates a timer - this works on both active and inactive
429 * The function returns whether it has deactivated a pending timer or not.
430 * (ie. del_timer() of an inactive timer returns 0, del_timer() of an
431 * active timer returns 1.)
433 int del_timer(struct timer_list *timer)
439 if (timer_pending(timer)) {
440 base = lock_timer_base(timer, &flags);
441 if (timer_pending(timer)) {
442 detach_timer(timer, 1);
445 spin_unlock_irqrestore(&base->lock, flags);
451 EXPORT_SYMBOL(del_timer);
455 * try_to_del_timer_sync - Try to deactivate a timer
456 * @timer: timer do del
458 * This function tries to deactivate a timer. Upon successful (ret >= 0)
459 * exit the timer is not queued and the handler is not running on any CPU.
461 * It must not be called from interrupt contexts.
463 int try_to_del_timer_sync(struct timer_list *timer)
469 base = lock_timer_base(timer, &flags);
471 if (base->running_timer == timer)
475 if (timer_pending(timer)) {
476 detach_timer(timer, 1);
480 spin_unlock_irqrestore(&base->lock, flags);
486 * del_timer_sync - deactivate a timer and wait for the handler to finish.
487 * @timer: the timer to be deactivated
489 * This function only differs from del_timer() on SMP: besides deactivating
490 * the timer it also makes sure the handler has finished executing on other
493 * Synchronization rules: Callers must prevent restarting of the timer,
494 * otherwise this function is meaningless. It must not be called from
495 * interrupt contexts. The caller must not hold locks which would prevent
496 * completion of the timer's handler. The timer's handler must not call
497 * add_timer_on(). Upon exit the timer is not queued and the handler is
498 * not running on any CPU.
500 * The function returns whether it has deactivated a pending timer or not.
502 int del_timer_sync(struct timer_list *timer)
505 int ret = try_to_del_timer_sync(timer);
512 EXPORT_SYMBOL(del_timer_sync);
515 static int cascade(tvec_base_t *base, tvec_t *tv, int index)
517 /* cascade all the timers from tv up one level */
518 struct timer_list *timer, *tmp;
519 struct list_head tv_list;
521 list_replace_init(tv->vec + index, &tv_list);
524 * We are removing _all_ timers from the list, so we
525 * don't have to detach them individually.
527 list_for_each_entry_safe(timer, tmp, &tv_list, entry) {
528 BUG_ON(timer->base != base);
529 internal_add_timer(base, timer);
535 #define INDEX(N) ((base->timer_jiffies >> (TVR_BITS + (N) * TVN_BITS)) & TVN_MASK)
538 * __run_timers - run all expired timers (if any) on this CPU.
539 * @base: the timer vector to be processed.
541 * This function cascades all vectors and executes all expired timer
544 static inline void __run_timers(tvec_base_t *base)
546 struct timer_list *timer;
548 spin_lock_irq(&base->lock);
549 while (time_after_eq(jiffies, base->timer_jiffies)) {
550 struct list_head work_list;
551 struct list_head *head = &work_list;
552 int index = base->timer_jiffies & TVR_MASK;
558 (!cascade(base, &base->tv2, INDEX(0))) &&
559 (!cascade(base, &base->tv3, INDEX(1))) &&
560 !cascade(base, &base->tv4, INDEX(2)))
561 cascade(base, &base->tv5, INDEX(3));
562 ++base->timer_jiffies;
563 list_replace_init(base->tv1.vec + index, &work_list);
564 while (!list_empty(head)) {
565 void (*fn)(unsigned long);
568 timer = list_entry(head->next,struct timer_list,entry);
569 fn = timer->function;
572 set_running_timer(base, timer);
573 detach_timer(timer, 1);
574 spin_unlock_irq(&base->lock);
576 int preempt_count = preempt_count();
578 if (preempt_count != preempt_count()) {
579 printk(KERN_WARNING "huh, entered %p "
580 "with preempt_count %08x, exited"
587 spin_lock_irq(&base->lock);
590 set_running_timer(base, NULL);
591 spin_unlock_irq(&base->lock);
594 #ifdef CONFIG_NO_IDLE_HZ
596 * Find out when the next timer event is due to happen. This
597 * is used on S/390 to stop all activity when a cpus is idle.
598 * This functions needs to be called disabled.
600 unsigned long next_timer_interrupt(void)
603 struct list_head *list;
604 struct timer_list *nte;
605 unsigned long expires;
606 unsigned long hr_expires = MAX_JIFFY_OFFSET;
611 hr_delta = hrtimer_get_next_event();
612 if (hr_delta.tv64 != KTIME_MAX) {
613 struct timespec tsdelta;
614 tsdelta = ktime_to_timespec(hr_delta);
615 hr_expires = timespec_to_jiffies(&tsdelta);
617 return hr_expires + jiffies;
619 hr_expires += jiffies;
621 base = __get_cpu_var(tvec_bases);
622 spin_lock(&base->lock);
623 expires = base->timer_jiffies + (LONG_MAX >> 1);
626 /* Look for timer events in tv1. */
627 j = base->timer_jiffies & TVR_MASK;
629 list_for_each_entry(nte, base->tv1.vec + j, entry) {
630 expires = nte->expires;
631 if (j < (base->timer_jiffies & TVR_MASK))
632 list = base->tv2.vec + (INDEX(0));
635 j = (j + 1) & TVR_MASK;
636 } while (j != (base->timer_jiffies & TVR_MASK));
639 varray[0] = &base->tv2;
640 varray[1] = &base->tv3;
641 varray[2] = &base->tv4;
642 varray[3] = &base->tv5;
643 for (i = 0; i < 4; i++) {
646 if (list_empty(varray[i]->vec + j)) {
647 j = (j + 1) & TVN_MASK;
650 list_for_each_entry(nte, varray[i]->vec + j, entry)
651 if (time_before(nte->expires, expires))
652 expires = nte->expires;
653 if (j < (INDEX(i)) && i < 3)
654 list = varray[i + 1]->vec + (INDEX(i + 1));
656 } while (j != (INDEX(i)));
661 * The search wrapped. We need to look at the next list
662 * from next tv element that would cascade into tv element
663 * where we found the timer element.
665 list_for_each_entry(nte, list, entry) {
666 if (time_before(nte->expires, expires))
667 expires = nte->expires;
670 spin_unlock(&base->lock);
673 * It can happen that other CPUs service timer IRQs and increment
674 * jiffies, but we have not yet got a local timer tick to process
675 * the timer wheels. In that case, the expiry time can be before
676 * jiffies, but since the high-resolution timer here is relative to
677 * jiffies, the default expression when high-resolution timers are
680 * time_before(MAX_JIFFY_OFFSET + jiffies, expires)
682 * would falsely evaluate to true. If that is the case, just
683 * return jiffies so that we can immediately fire the local timer
685 if (time_before(expires, jiffies))
688 if (time_before(hr_expires, expires))
695 /******************************************************************/
699 * wall_to_monotonic is what we need to add to xtime (or xtime corrected
700 * for sub jiffie times) to get to monotonic time. Monotonic is pegged
701 * at zero at system boot time, so wall_to_monotonic will be negative,
702 * however, we will ALWAYS keep the tv_nsec part positive so we can use
703 * the usual normalization.
705 struct timespec xtime __attribute__ ((aligned (16)));
706 struct timespec wall_to_monotonic __attribute__ ((aligned (16)));
708 EXPORT_SYMBOL(xtime);
711 /* XXX - all of this timekeeping code should be later moved to time.c */
712 #include <linux/clocksource.h>
713 static struct clocksource *clock; /* pointer to current clocksource */
715 #ifdef CONFIG_GENERIC_TIME
717 * __get_nsec_offset - Returns nanoseconds since last call to periodic_hook
719 * private function, must hold xtime_lock lock when being
720 * called. Returns the number of nanoseconds since the
721 * last call to update_wall_time() (adjusted by NTP scaling)
723 static inline s64 __get_nsec_offset(void)
725 cycle_t cycle_now, cycle_delta;
728 /* read clocksource: */
729 cycle_now = clocksource_read(clock);
731 /* calculate the delta since the last update_wall_time: */
732 cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
734 /* convert to nanoseconds: */
735 ns_offset = cyc2ns(clock, cycle_delta);
741 * __get_realtime_clock_ts - Returns the time of day in a timespec
742 * @ts: pointer to the timespec to be set
744 * Returns the time of day in a timespec. Used by
745 * do_gettimeofday() and get_realtime_clock_ts().
747 static inline void __get_realtime_clock_ts(struct timespec *ts)
753 seq = read_seqbegin(&xtime_lock);
756 nsecs = __get_nsec_offset();
758 } while (read_seqretry(&xtime_lock, seq));
760 timespec_add_ns(ts, nsecs);
764 * getnstimeofday - Returns the time of day in a timespec
765 * @ts: pointer to the timespec to be set
767 * Returns the time of day in a timespec.
769 void getnstimeofday(struct timespec *ts)
771 __get_realtime_clock_ts(ts);
774 EXPORT_SYMBOL(getnstimeofday);
777 * do_gettimeofday - Returns the time of day in a timeval
778 * @tv: pointer to the timeval to be set
780 * NOTE: Users should be converted to using get_realtime_clock_ts()
782 void do_gettimeofday(struct timeval *tv)
786 __get_realtime_clock_ts(&now);
787 tv->tv_sec = now.tv_sec;
788 tv->tv_usec = now.tv_nsec/1000;
791 EXPORT_SYMBOL(do_gettimeofday);
793 * do_settimeofday - Sets the time of day
794 * @tv: pointer to the timespec variable containing the new time
796 * Sets the time of day to the new time and update NTP and notify hrtimers
798 int do_settimeofday(struct timespec *tv)
801 time_t wtm_sec, sec = tv->tv_sec;
802 long wtm_nsec, nsec = tv->tv_nsec;
804 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
807 write_seqlock_irqsave(&xtime_lock, flags);
809 nsec -= __get_nsec_offset();
811 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
812 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
814 set_normalized_timespec(&xtime, sec, nsec);
815 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
820 write_sequnlock_irqrestore(&xtime_lock, flags);
822 /* signal hrtimers about time change */
828 EXPORT_SYMBOL(do_settimeofday);
831 * change_clocksource - Swaps clocksources if a new one is available
833 * Accumulates current time interval and initializes new clocksource
835 static int change_clocksource(void)
837 struct clocksource *new;
840 new = clocksource_get_next();
842 now = clocksource_read(new);
843 nsec = __get_nsec_offset();
844 timespec_add_ns(&xtime, nsec);
847 clock->cycle_last = now;
848 printk(KERN_INFO "Time: %s clocksource has been installed.\n",
855 static inline int change_clocksource(void)
862 * timeofday_is_continuous - check to see if timekeeping is free running
864 int timekeeping_is_continuous(void)
870 seq = read_seqbegin(&xtime_lock);
872 ret = clock->flags & CLOCK_SOURCE_IS_CONTINUOUS;
874 } while (read_seqretry(&xtime_lock, seq));
880 * read_persistent_clock - Return time in seconds from the persistent clock.
882 * Weak dummy function for arches that do not yet support it.
883 * Returns seconds from epoch using the battery backed persistent clock.
884 * Returns zero if unsupported.
886 * XXX - Do be sure to remove it once all arches implement it.
888 unsigned long __attribute__((weak)) read_persistent_clock(void)
894 * timekeeping_init - Initializes the clocksource and common timekeeping values
896 void __init timekeeping_init(void)
899 unsigned long sec = read_persistent_clock();
901 write_seqlock_irqsave(&xtime_lock, flags);
905 clock = clocksource_get_next();
906 clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH);
907 clock->cycle_last = clocksource_read(clock);
911 set_normalized_timespec(&wall_to_monotonic,
912 -xtime.tv_sec, -xtime.tv_nsec);
914 write_sequnlock_irqrestore(&xtime_lock, flags);
918 /* flag for if timekeeping is suspended */
919 static int timekeeping_suspended;
920 /* time in seconds when suspend began */
921 static unsigned long timekeeping_suspend_time;
924 * timekeeping_resume - Resumes the generic timekeeping subsystem.
927 * This is for the generic clocksource timekeeping.
928 * xtime/wall_to_monotonic/jiffies/etc are
929 * still managed by arch specific suspend/resume code.
931 static int timekeeping_resume(struct sys_device *dev)
934 unsigned long now = read_persistent_clock();
936 write_seqlock_irqsave(&xtime_lock, flags);
938 if (now && (now > timekeeping_suspend_time)) {
939 unsigned long sleep_length = now - timekeeping_suspend_time;
941 xtime.tv_sec += sleep_length;
942 wall_to_monotonic.tv_sec -= sleep_length;
944 /* re-base the last cycle value */
945 clock->cycle_last = clocksource_read(clock);
947 timekeeping_suspended = 0;
948 write_sequnlock_irqrestore(&xtime_lock, flags);
950 touch_softlockup_watchdog();
951 hrtimer_notify_resume();
956 static int timekeeping_suspend(struct sys_device *dev, pm_message_t state)
960 write_seqlock_irqsave(&xtime_lock, flags);
961 timekeeping_suspended = 1;
962 timekeeping_suspend_time = read_persistent_clock();
963 write_sequnlock_irqrestore(&xtime_lock, flags);
967 /* sysfs resume/suspend bits for timekeeping */
968 static struct sysdev_class timekeeping_sysclass = {
969 .resume = timekeeping_resume,
970 .suspend = timekeeping_suspend,
971 set_kset_name("timekeeping"),
974 static struct sys_device device_timer = {
976 .cls = &timekeeping_sysclass,
979 static int __init timekeeping_init_device(void)
981 int error = sysdev_class_register(&timekeeping_sysclass);
983 error = sysdev_register(&device_timer);
987 device_initcall(timekeeping_init_device);
990 * If the error is already larger, we look ahead even further
991 * to compensate for late or lost adjustments.
993 static __always_inline int clocksource_bigadjust(s64 error, s64 *interval,
1001 * Use the current error value to determine how much to look ahead.
1002 * The larger the error the slower we adjust for it to avoid problems
1003 * with losing too many ticks, otherwise we would overadjust and
1004 * produce an even larger error. The smaller the adjustment the
1005 * faster we try to adjust for it, as lost ticks can do less harm
1006 * here. This is tuned so that an error of about 1 msec is adusted
1007 * within about 1 sec (or 2^20 nsec in 2^SHIFT_HZ ticks).
1009 error2 = clock->error >> (TICK_LENGTH_SHIFT + 22 - 2 * SHIFT_HZ);
1010 error2 = abs(error2);
1011 for (look_ahead = 0; error2 > 0; look_ahead++)
1015 * Now calculate the error in (1 << look_ahead) ticks, but first
1016 * remove the single look ahead already included in the error.
1018 tick_error = current_tick_length() >>
1019 (TICK_LENGTH_SHIFT - clock->shift + 1);
1020 tick_error -= clock->xtime_interval >> 1;
1021 error = ((error - tick_error) >> look_ahead) + tick_error;
1023 /* Finally calculate the adjustment shift value. */
1028 *interval = -*interval;
1032 for (adj = 0; error > i; adj++)
1041 * Adjust the multiplier to reduce the error value,
1042 * this is optimized for the most common adjustments of -1,0,1,
1043 * for other values we can do a bit more work.
1045 static void clocksource_adjust(struct clocksource *clock, s64 offset)
1047 s64 error, interval = clock->cycle_interval;
1050 error = clock->error >> (TICK_LENGTH_SHIFT - clock->shift - 1);
1051 if (error > interval) {
1053 if (likely(error <= interval))
1056 adj = clocksource_bigadjust(error, &interval, &offset);
1057 } else if (error < -interval) {
1059 if (likely(error >= -interval)) {
1061 interval = -interval;
1064 adj = clocksource_bigadjust(error, &interval, &offset);
1069 clock->xtime_interval += interval;
1070 clock->xtime_nsec -= offset;
1071 clock->error -= (interval - offset) <<
1072 (TICK_LENGTH_SHIFT - clock->shift);
1076 * update_wall_time - Uses the current clocksource to increment the wall time
1078 * Called from the timer interrupt, must hold a write on xtime_lock.
1080 static void update_wall_time(void)
1084 /* Make sure we're fully resumed: */
1085 if (unlikely(timekeeping_suspended))
1088 #ifdef CONFIG_GENERIC_TIME
1089 offset = (clocksource_read(clock) - clock->cycle_last) & clock->mask;
1091 offset = clock->cycle_interval;
1093 clock->xtime_nsec += (s64)xtime.tv_nsec << clock->shift;
1095 /* normally this loop will run just once, however in the
1096 * case of lost or late ticks, it will accumulate correctly.
1098 while (offset >= clock->cycle_interval) {
1099 /* accumulate one interval */
1100 clock->xtime_nsec += clock->xtime_interval;
1101 clock->cycle_last += clock->cycle_interval;
1102 offset -= clock->cycle_interval;
1104 if (clock->xtime_nsec >= (u64)NSEC_PER_SEC << clock->shift) {
1105 clock->xtime_nsec -= (u64)NSEC_PER_SEC << clock->shift;
1110 /* interpolator bits */
1111 time_interpolator_update(clock->xtime_interval
1114 /* accumulate error between NTP and clock interval */
1115 clock->error += current_tick_length();
1116 clock->error -= clock->xtime_interval << (TICK_LENGTH_SHIFT - clock->shift);
1119 /* correct the clock when NTP error is too big */
1120 clocksource_adjust(clock, offset);
1122 /* store full nanoseconds into xtime */
1123 xtime.tv_nsec = (s64)clock->xtime_nsec >> clock->shift;
1124 clock->xtime_nsec -= (s64)xtime.tv_nsec << clock->shift;
1126 /* check to see if there is a new clocksource to use */
1127 if (change_clocksource()) {
1129 clock->xtime_nsec = 0;
1130 clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH);
1135 * Called from the timer interrupt handler to charge one tick to the current
1136 * process. user_tick is 1 if the tick is user time, 0 for system.
1138 void update_process_times(int user_tick)
1140 struct task_struct *p = current;
1141 int cpu = smp_processor_id();
1143 /* Note: this timer irq context must be accounted for as well. */
1145 account_user_time(p, jiffies_to_cputime(1));
1147 account_system_time(p, HARDIRQ_OFFSET, jiffies_to_cputime(1));
1149 if (rcu_pending(cpu))
1150 rcu_check_callbacks(cpu, user_tick);
1152 run_posix_cpu_timers(p);
1156 * Nr of active tasks - counted in fixed-point numbers
1158 static unsigned long count_active_tasks(void)
1160 return nr_active() * FIXED_1;
1164 * Hmm.. Changed this, as the GNU make sources (load.c) seems to
1165 * imply that avenrun[] is the standard name for this kind of thing.
1166 * Nothing else seems to be standardized: the fractional size etc
1167 * all seem to differ on different machines.
1169 * Requires xtime_lock to access.
1171 unsigned long avenrun[3];
1173 EXPORT_SYMBOL(avenrun);
1176 * calc_load - given tick count, update the avenrun load estimates.
1177 * This is called while holding a write_lock on xtime_lock.
1179 static inline void calc_load(unsigned long ticks)
1181 unsigned long active_tasks; /* fixed-point */
1182 static int count = LOAD_FREQ;
1185 if (unlikely(count < 0)) {
1186 active_tasks = count_active_tasks();
1188 CALC_LOAD(avenrun[0], EXP_1, active_tasks);
1189 CALC_LOAD(avenrun[1], EXP_5, active_tasks);
1190 CALC_LOAD(avenrun[2], EXP_15, active_tasks);
1192 } while (count < 0);
1197 * This read-write spinlock protects us from races in SMP while
1198 * playing with xtime and avenrun.
1200 __attribute__((weak)) __cacheline_aligned_in_smp DEFINE_SEQLOCK(xtime_lock);
1202 EXPORT_SYMBOL(xtime_lock);
1205 * This function runs timers and the timer-tq in bottom half context.
1207 static void run_timer_softirq(struct softirq_action *h)
1209 tvec_base_t *base = __get_cpu_var(tvec_bases);
1211 hrtimer_run_queues();
1212 if (time_after_eq(jiffies, base->timer_jiffies))
1217 * Called by the local, per-CPU timer interrupt on SMP.
1219 void run_local_timers(void)
1221 raise_softirq(TIMER_SOFTIRQ);
1226 * Called by the timer interrupt. xtime_lock must already be taken
1229 static inline void update_times(unsigned long ticks)
1236 * The 64-bit jiffies value is not atomic - you MUST NOT read it
1237 * without sampling the sequence number in xtime_lock.
1238 * jiffies is defined in the linker script...
1241 void do_timer(unsigned long ticks)
1243 jiffies_64 += ticks;
1244 update_times(ticks);
1247 #ifdef __ARCH_WANT_SYS_ALARM
1250 * For backwards compatibility? This can be done in libc so Alpha
1251 * and all newer ports shouldn't need it.
1253 asmlinkage unsigned long sys_alarm(unsigned int seconds)
1255 return alarm_setitimer(seconds);
1263 * The Alpha uses getxpid, getxuid, and getxgid instead. Maybe this
1264 * should be moved into arch/i386 instead?
1268 * sys_getpid - return the thread group id of the current process
1270 * Note, despite the name, this returns the tgid not the pid. The tgid and
1271 * the pid are identical unless CLONE_THREAD was specified on clone() in
1272 * which case the tgid is the same in all threads of the same group.
1274 * This is SMP safe as current->tgid does not change.
1276 asmlinkage long sys_getpid(void)
1278 return current->tgid;
1282 * Accessing ->real_parent is not SMP-safe, it could
1283 * change from under us. However, we can use a stale
1284 * value of ->real_parent under rcu_read_lock(), see
1285 * release_task()->call_rcu(delayed_put_task_struct).
1287 asmlinkage long sys_getppid(void)
1292 pid = rcu_dereference(current->real_parent)->tgid;
1298 asmlinkage long sys_getuid(void)
1300 /* Only we change this so SMP safe */
1301 return current->uid;
1304 asmlinkage long sys_geteuid(void)
1306 /* Only we change this so SMP safe */
1307 return current->euid;
1310 asmlinkage long sys_getgid(void)
1312 /* Only we change this so SMP safe */
1313 return current->gid;
1316 asmlinkage long sys_getegid(void)
1318 /* Only we change this so SMP safe */
1319 return current->egid;
1324 static void process_timeout(unsigned long __data)
1326 wake_up_process((struct task_struct *)__data);
1330 * schedule_timeout - sleep until timeout
1331 * @timeout: timeout value in jiffies
1333 * Make the current task sleep until @timeout jiffies have
1334 * elapsed. The routine will return immediately unless
1335 * the current task state has been set (see set_current_state()).
1337 * You can set the task state as follows -
1339 * %TASK_UNINTERRUPTIBLE - at least @timeout jiffies are guaranteed to
1340 * pass before the routine returns. The routine will return 0
1342 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
1343 * delivered to the current task. In this case the remaining time
1344 * in jiffies will be returned, or 0 if the timer expired in time
1346 * The current task state is guaranteed to be TASK_RUNNING when this
1349 * Specifying a @timeout value of %MAX_SCHEDULE_TIMEOUT will schedule
1350 * the CPU away without a bound on the timeout. In this case the return
1351 * value will be %MAX_SCHEDULE_TIMEOUT.
1353 * In all cases the return value is guaranteed to be non-negative.
1355 fastcall signed long __sched schedule_timeout(signed long timeout)
1357 struct timer_list timer;
1358 unsigned long expire;
1362 case MAX_SCHEDULE_TIMEOUT:
1364 * These two special cases are useful to be comfortable
1365 * in the caller. Nothing more. We could take
1366 * MAX_SCHEDULE_TIMEOUT from one of the negative value
1367 * but I' d like to return a valid offset (>=0) to allow
1368 * the caller to do everything it want with the retval.
1374 * Another bit of PARANOID. Note that the retval will be
1375 * 0 since no piece of kernel is supposed to do a check
1376 * for a negative retval of schedule_timeout() (since it
1377 * should never happens anyway). You just have the printk()
1378 * that will tell you if something is gone wrong and where.
1381 printk(KERN_ERR "schedule_timeout: wrong timeout "
1382 "value %lx\n", timeout);
1384 current->state = TASK_RUNNING;
1389 expire = timeout + jiffies;
1391 setup_timer(&timer, process_timeout, (unsigned long)current);
1392 __mod_timer(&timer, expire);
1394 del_singleshot_timer_sync(&timer);
1396 timeout = expire - jiffies;
1399 return timeout < 0 ? 0 : timeout;
1401 EXPORT_SYMBOL(schedule_timeout);
1404 * We can use __set_current_state() here because schedule_timeout() calls
1405 * schedule() unconditionally.
1407 signed long __sched schedule_timeout_interruptible(signed long timeout)
1409 __set_current_state(TASK_INTERRUPTIBLE);
1410 return schedule_timeout(timeout);
1412 EXPORT_SYMBOL(schedule_timeout_interruptible);
1414 signed long __sched schedule_timeout_uninterruptible(signed long timeout)
1416 __set_current_state(TASK_UNINTERRUPTIBLE);
1417 return schedule_timeout(timeout);
1419 EXPORT_SYMBOL(schedule_timeout_uninterruptible);
1421 /* Thread ID - the internal kernel "pid" */
1422 asmlinkage long sys_gettid(void)
1424 return current->pid;
1428 * do_sysinfo - fill in sysinfo struct
1429 * @info: pointer to buffer to fill
1431 int do_sysinfo(struct sysinfo *info)
1433 unsigned long mem_total, sav_total;
1434 unsigned int mem_unit, bitcount;
1437 memset(info, 0, sizeof(struct sysinfo));
1441 seq = read_seqbegin(&xtime_lock);
1444 * This is annoying. The below is the same thing
1445 * posix_get_clock_monotonic() does, but it wants to
1446 * take the lock which we want to cover the loads stuff
1450 getnstimeofday(&tp);
1451 tp.tv_sec += wall_to_monotonic.tv_sec;
1452 tp.tv_nsec += wall_to_monotonic.tv_nsec;
1453 if (tp.tv_nsec - NSEC_PER_SEC >= 0) {
1454 tp.tv_nsec = tp.tv_nsec - NSEC_PER_SEC;
1457 info->uptime = tp.tv_sec + (tp.tv_nsec ? 1 : 0);
1459 info->loads[0] = avenrun[0] << (SI_LOAD_SHIFT - FSHIFT);
1460 info->loads[1] = avenrun[1] << (SI_LOAD_SHIFT - FSHIFT);
1461 info->loads[2] = avenrun[2] << (SI_LOAD_SHIFT - FSHIFT);
1463 info->procs = nr_threads;
1464 } while (read_seqretry(&xtime_lock, seq));
1470 * If the sum of all the available memory (i.e. ram + swap)
1471 * is less than can be stored in a 32 bit unsigned long then
1472 * we can be binary compatible with 2.2.x kernels. If not,
1473 * well, in that case 2.2.x was broken anyways...
1475 * -Erik Andersen <andersee@debian.org>
1478 mem_total = info->totalram + info->totalswap;
1479 if (mem_total < info->totalram || mem_total < info->totalswap)
1482 mem_unit = info->mem_unit;
1483 while (mem_unit > 1) {
1486 sav_total = mem_total;
1488 if (mem_total < sav_total)
1493 * If mem_total did not overflow, multiply all memory values by
1494 * info->mem_unit and set it to 1. This leaves things compatible
1495 * with 2.2.x, and also retains compatibility with earlier 2.4.x
1500 info->totalram <<= bitcount;
1501 info->freeram <<= bitcount;
1502 info->sharedram <<= bitcount;
1503 info->bufferram <<= bitcount;
1504 info->totalswap <<= bitcount;
1505 info->freeswap <<= bitcount;
1506 info->totalhigh <<= bitcount;
1507 info->freehigh <<= bitcount;
1513 asmlinkage long sys_sysinfo(struct sysinfo __user *info)
1519 if (copy_to_user(info, &val, sizeof(struct sysinfo)))
1526 * lockdep: we want to track each per-CPU base as a separate lock-class,
1527 * but timer-bases are kmalloc()-ed, so we need to attach separate
1530 static struct lock_class_key base_lock_keys[NR_CPUS];
1532 static int __devinit init_timers_cpu(int cpu)
1536 static char __devinitdata tvec_base_done[NR_CPUS];
1538 if (!tvec_base_done[cpu]) {
1539 static char boot_done;
1543 * The APs use this path later in boot
1545 base = kmalloc_node(sizeof(*base), GFP_KERNEL,
1549 memset(base, 0, sizeof(*base));
1550 per_cpu(tvec_bases, cpu) = base;
1553 * This is for the boot CPU - we use compile-time
1554 * static initialisation because per-cpu memory isn't
1555 * ready yet and because the memory allocators are not
1556 * initialised either.
1559 base = &boot_tvec_bases;
1561 tvec_base_done[cpu] = 1;
1563 base = per_cpu(tvec_bases, cpu);
1566 spin_lock_init(&base->lock);
1567 lockdep_set_class(&base->lock, base_lock_keys + cpu);
1569 for (j = 0; j < TVN_SIZE; j++) {
1570 INIT_LIST_HEAD(base->tv5.vec + j);
1571 INIT_LIST_HEAD(base->tv4.vec + j);
1572 INIT_LIST_HEAD(base->tv3.vec + j);
1573 INIT_LIST_HEAD(base->tv2.vec + j);
1575 for (j = 0; j < TVR_SIZE; j++)
1576 INIT_LIST_HEAD(base->tv1.vec + j);
1578 base->timer_jiffies = jiffies;
1582 #ifdef CONFIG_HOTPLUG_CPU
1583 static void migrate_timer_list(tvec_base_t *new_base, struct list_head *head)
1585 struct timer_list *timer;
1587 while (!list_empty(head)) {
1588 timer = list_entry(head->next, struct timer_list, entry);
1589 detach_timer(timer, 0);
1590 timer->base = new_base;
1591 internal_add_timer(new_base, timer);
1595 static void __devinit migrate_timers(int cpu)
1597 tvec_base_t *old_base;
1598 tvec_base_t *new_base;
1601 BUG_ON(cpu_online(cpu));
1602 old_base = per_cpu(tvec_bases, cpu);
1603 new_base = get_cpu_var(tvec_bases);
1605 local_irq_disable();
1606 spin_lock(&new_base->lock);
1607 spin_lock(&old_base->lock);
1609 BUG_ON(old_base->running_timer);
1611 for (i = 0; i < TVR_SIZE; i++)
1612 migrate_timer_list(new_base, old_base->tv1.vec + i);
1613 for (i = 0; i < TVN_SIZE; i++) {
1614 migrate_timer_list(new_base, old_base->tv2.vec + i);
1615 migrate_timer_list(new_base, old_base->tv3.vec + i);
1616 migrate_timer_list(new_base, old_base->tv4.vec + i);
1617 migrate_timer_list(new_base, old_base->tv5.vec + i);
1620 spin_unlock(&old_base->lock);
1621 spin_unlock(&new_base->lock);
1623 put_cpu_var(tvec_bases);
1625 #endif /* CONFIG_HOTPLUG_CPU */
1627 static int __cpuinit timer_cpu_notify(struct notifier_block *self,
1628 unsigned long action, void *hcpu)
1630 long cpu = (long)hcpu;
1632 case CPU_UP_PREPARE:
1633 if (init_timers_cpu(cpu) < 0)
1636 #ifdef CONFIG_HOTPLUG_CPU
1638 migrate_timers(cpu);
1647 static struct notifier_block __cpuinitdata timers_nb = {
1648 .notifier_call = timer_cpu_notify,
1652 void __init init_timers(void)
1654 int err = timer_cpu_notify(&timers_nb, (unsigned long)CPU_UP_PREPARE,
1655 (void *)(long)smp_processor_id());
1657 BUG_ON(err == NOTIFY_BAD);
1658 register_cpu_notifier(&timers_nb);
1659 open_softirq(TIMER_SOFTIRQ, run_timer_softirq, NULL);
1662 #ifdef CONFIG_TIME_INTERPOLATION
1664 struct time_interpolator *time_interpolator __read_mostly;
1665 static struct time_interpolator *time_interpolator_list __read_mostly;
1666 static DEFINE_SPINLOCK(time_interpolator_lock);
1668 static inline cycles_t time_interpolator_get_cycles(unsigned int src)
1670 unsigned long (*x)(void);
1674 case TIME_SOURCE_FUNCTION:
1675 x = time_interpolator->addr;
1678 case TIME_SOURCE_MMIO64 :
1679 return readq_relaxed((void __iomem *)time_interpolator->addr);
1681 case TIME_SOURCE_MMIO32 :
1682 return readl_relaxed((void __iomem *)time_interpolator->addr);
1684 default: return get_cycles();
1688 static inline u64 time_interpolator_get_counter(int writelock)
1690 unsigned int src = time_interpolator->source;
1692 if (time_interpolator->jitter)
1698 lcycle = time_interpolator->last_cycle;
1699 now = time_interpolator_get_cycles(src);
1700 if (lcycle && time_after(lcycle, now))
1703 /* When holding the xtime write lock, there's no need
1704 * to add the overhead of the cmpxchg. Readers are
1705 * force to retry until the write lock is released.
1708 time_interpolator->last_cycle = now;
1711 /* Keep track of the last timer value returned. The use of cmpxchg here
1712 * will cause contention in an SMP environment.
1714 } while (unlikely(cmpxchg(&time_interpolator->last_cycle, lcycle, now) != lcycle));
1718 return time_interpolator_get_cycles(src);
1721 void time_interpolator_reset(void)
1723 time_interpolator->offset = 0;
1724 time_interpolator->last_counter = time_interpolator_get_counter(1);
1727 #define GET_TI_NSECS(count,i) (((((count) - i->last_counter) & (i)->mask) * (i)->nsec_per_cyc) >> (i)->shift)
1729 unsigned long time_interpolator_get_offset(void)
1731 /* If we do not have a time interpolator set up then just return zero */
1732 if (!time_interpolator)
1735 return time_interpolator->offset +
1736 GET_TI_NSECS(time_interpolator_get_counter(0), time_interpolator);
1739 #define INTERPOLATOR_ADJUST 65536
1740 #define INTERPOLATOR_MAX_SKIP 10*INTERPOLATOR_ADJUST
1742 void time_interpolator_update(long delta_nsec)
1745 unsigned long offset;
1747 /* If there is no time interpolator set up then do nothing */
1748 if (!time_interpolator)
1752 * The interpolator compensates for late ticks by accumulating the late
1753 * time in time_interpolator->offset. A tick earlier than expected will
1754 * lead to a reset of the offset and a corresponding jump of the clock
1755 * forward. Again this only works if the interpolator clock is running
1756 * slightly slower than the regular clock and the tuning logic insures
1760 counter = time_interpolator_get_counter(1);
1761 offset = time_interpolator->offset +
1762 GET_TI_NSECS(counter, time_interpolator);
1764 if (delta_nsec < 0 || (unsigned long) delta_nsec < offset)
1765 time_interpolator->offset = offset - delta_nsec;
1767 time_interpolator->skips++;
1768 time_interpolator->ns_skipped += delta_nsec - offset;
1769 time_interpolator->offset = 0;
1771 time_interpolator->last_counter = counter;
1773 /* Tuning logic for time interpolator invoked every minute or so.
1774 * Decrease interpolator clock speed if no skips occurred and an offset is carried.
1775 * Increase interpolator clock speed if we skip too much time.
1777 if (jiffies % INTERPOLATOR_ADJUST == 0)
1779 if (time_interpolator->skips == 0 && time_interpolator->offset > tick_nsec)
1780 time_interpolator->nsec_per_cyc--;
1781 if (time_interpolator->ns_skipped > INTERPOLATOR_MAX_SKIP && time_interpolator->offset == 0)
1782 time_interpolator->nsec_per_cyc++;
1783 time_interpolator->skips = 0;
1784 time_interpolator->ns_skipped = 0;
1789 is_better_time_interpolator(struct time_interpolator *new)
1791 if (!time_interpolator)
1793 return new->frequency > 2*time_interpolator->frequency ||
1794 (unsigned long)new->drift < (unsigned long)time_interpolator->drift;
1798 register_time_interpolator(struct time_interpolator *ti)
1800 unsigned long flags;
1803 BUG_ON(ti->frequency == 0 || ti->mask == 0);
1805 ti->nsec_per_cyc = ((u64)NSEC_PER_SEC << ti->shift) / ti->frequency;
1806 spin_lock(&time_interpolator_lock);
1807 write_seqlock_irqsave(&xtime_lock, flags);
1808 if (is_better_time_interpolator(ti)) {
1809 time_interpolator = ti;
1810 time_interpolator_reset();
1812 write_sequnlock_irqrestore(&xtime_lock, flags);
1814 ti->next = time_interpolator_list;
1815 time_interpolator_list = ti;
1816 spin_unlock(&time_interpolator_lock);
1820 unregister_time_interpolator(struct time_interpolator *ti)
1822 struct time_interpolator *curr, **prev;
1823 unsigned long flags;
1825 spin_lock(&time_interpolator_lock);
1826 prev = &time_interpolator_list;
1827 for (curr = *prev; curr; curr = curr->next) {
1835 write_seqlock_irqsave(&xtime_lock, flags);
1836 if (ti == time_interpolator) {
1837 /* we lost the best time-interpolator: */
1838 time_interpolator = NULL;
1839 /* find the next-best interpolator */
1840 for (curr = time_interpolator_list; curr; curr = curr->next)
1841 if (is_better_time_interpolator(curr))
1842 time_interpolator = curr;
1843 time_interpolator_reset();
1845 write_sequnlock_irqrestore(&xtime_lock, flags);
1846 spin_unlock(&time_interpolator_lock);
1848 #endif /* CONFIG_TIME_INTERPOLATION */
1851 * msleep - sleep safely even with waitqueue interruptions
1852 * @msecs: Time in milliseconds to sleep for
1854 void msleep(unsigned int msecs)
1856 unsigned long timeout = msecs_to_jiffies(msecs) + 1;
1859 timeout = schedule_timeout_uninterruptible(timeout);
1862 EXPORT_SYMBOL(msleep);
1865 * msleep_interruptible - sleep waiting for signals
1866 * @msecs: Time in milliseconds to sleep for
1868 unsigned long msleep_interruptible(unsigned int msecs)
1870 unsigned long timeout = msecs_to_jiffies(msecs) + 1;
1872 while (timeout && !signal_pending(current))
1873 timeout = schedule_timeout_interruptible(timeout);
1874 return jiffies_to_msecs(timeout);
1877 EXPORT_SYMBOL(msleep_interruptible);