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 #ifdef CONFIG_TIME_INTERPOLATION
45 static void time_interpolator_update(long delta_nsec);
47 #define time_interpolator_update(x)
50 u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES;
52 EXPORT_SYMBOL(jiffies_64);
55 * per-CPU timer vector definitions:
57 #define TVN_BITS (CONFIG_BASE_SMALL ? 4 : 6)
58 #define TVR_BITS (CONFIG_BASE_SMALL ? 6 : 8)
59 #define TVN_SIZE (1 << TVN_BITS)
60 #define TVR_SIZE (1 << TVR_BITS)
61 #define TVN_MASK (TVN_SIZE - 1)
62 #define TVR_MASK (TVR_SIZE - 1)
64 typedef struct tvec_s {
65 struct list_head vec[TVN_SIZE];
68 typedef struct tvec_root_s {
69 struct list_head vec[TVR_SIZE];
72 struct tvec_t_base_s {
74 struct timer_list *running_timer;
75 unsigned long timer_jiffies;
81 } ____cacheline_aligned_in_smp;
83 typedef struct tvec_t_base_s tvec_base_t;
85 tvec_base_t boot_tvec_bases;
86 EXPORT_SYMBOL(boot_tvec_bases);
87 static DEFINE_PER_CPU(tvec_base_t *, tvec_bases) = &boot_tvec_bases;
89 static inline void set_running_timer(tvec_base_t *base,
90 struct timer_list *timer)
93 base->running_timer = timer;
97 static void internal_add_timer(tvec_base_t *base, struct timer_list *timer)
99 unsigned long expires = timer->expires;
100 unsigned long idx = expires - base->timer_jiffies;
101 struct list_head *vec;
103 if (idx < TVR_SIZE) {
104 int i = expires & TVR_MASK;
105 vec = base->tv1.vec + i;
106 } else if (idx < 1 << (TVR_BITS + TVN_BITS)) {
107 int i = (expires >> TVR_BITS) & TVN_MASK;
108 vec = base->tv2.vec + i;
109 } else if (idx < 1 << (TVR_BITS + 2 * TVN_BITS)) {
110 int i = (expires >> (TVR_BITS + TVN_BITS)) & TVN_MASK;
111 vec = base->tv3.vec + i;
112 } else if (idx < 1 << (TVR_BITS + 3 * TVN_BITS)) {
113 int i = (expires >> (TVR_BITS + 2 * TVN_BITS)) & TVN_MASK;
114 vec = base->tv4.vec + i;
115 } else if ((signed long) idx < 0) {
117 * Can happen if you add a timer with expires == jiffies,
118 * or you set a timer to go off in the past
120 vec = base->tv1.vec + (base->timer_jiffies & TVR_MASK);
123 /* If the timeout is larger than 0xffffffff on 64-bit
124 * architectures then we use the maximum timeout:
126 if (idx > 0xffffffffUL) {
128 expires = idx + base->timer_jiffies;
130 i = (expires >> (TVR_BITS + 3 * TVN_BITS)) & TVN_MASK;
131 vec = base->tv5.vec + i;
136 list_add_tail(&timer->entry, vec);
140 * init_timer - initialize a timer.
141 * @timer: the timer to be initialized
143 * init_timer() must be done to a timer prior calling *any* of the
144 * other timer functions.
146 void fastcall init_timer(struct timer_list *timer)
148 timer->entry.next = NULL;
149 timer->base = __raw_get_cpu_var(tvec_bases);
151 EXPORT_SYMBOL(init_timer);
153 static inline void detach_timer(struct timer_list *timer,
156 struct list_head *entry = &timer->entry;
158 __list_del(entry->prev, entry->next);
161 entry->prev = LIST_POISON2;
165 * We are using hashed locking: holding per_cpu(tvec_bases).lock
166 * means that all timers which are tied to this base via timer->base are
167 * locked, and the base itself is locked too.
169 * So __run_timers/migrate_timers can safely modify all timers which could
170 * be found on ->tvX lists.
172 * When the timer's base is locked, and the timer removed from list, it is
173 * possible to set timer->base = NULL and drop the lock: the timer remains
176 static tvec_base_t *lock_timer_base(struct timer_list *timer,
177 unsigned long *flags)
178 __acquires(timer->base->lock)
184 if (likely(base != NULL)) {
185 spin_lock_irqsave(&base->lock, *flags);
186 if (likely(base == timer->base))
188 /* The timer has migrated to another CPU */
189 spin_unlock_irqrestore(&base->lock, *flags);
195 int __mod_timer(struct timer_list *timer, unsigned long expires)
197 tvec_base_t *base, *new_base;
201 BUG_ON(!timer->function);
203 base = lock_timer_base(timer, &flags);
205 if (timer_pending(timer)) {
206 detach_timer(timer, 0);
210 new_base = __get_cpu_var(tvec_bases);
212 if (base != new_base) {
214 * We are trying to schedule the timer on the local CPU.
215 * However we can't change timer's base while it is running,
216 * otherwise del_timer_sync() can't detect that the timer's
217 * handler yet has not finished. This also guarantees that
218 * the timer is serialized wrt itself.
220 if (likely(base->running_timer != timer)) {
221 /* See the comment in lock_timer_base() */
223 spin_unlock(&base->lock);
225 spin_lock(&base->lock);
230 timer->expires = expires;
231 internal_add_timer(base, timer);
232 spin_unlock_irqrestore(&base->lock, flags);
237 EXPORT_SYMBOL(__mod_timer);
240 * add_timer_on - start a timer on a particular CPU
241 * @timer: the timer to be added
242 * @cpu: the CPU to start it on
244 * This is not very scalable on SMP. Double adds are not possible.
246 void add_timer_on(struct timer_list *timer, int cpu)
248 tvec_base_t *base = per_cpu(tvec_bases, cpu);
251 BUG_ON(timer_pending(timer) || !timer->function);
252 spin_lock_irqsave(&base->lock, flags);
254 internal_add_timer(base, timer);
255 spin_unlock_irqrestore(&base->lock, flags);
260 * mod_timer - modify a timer's timeout
261 * @timer: the timer to be modified
262 * @expires: new timeout in jiffies
264 * mod_timer is a more efficient way to update the expire field of an
265 * active timer (if the timer is inactive it will be activated)
267 * mod_timer(timer, expires) is equivalent to:
269 * del_timer(timer); timer->expires = expires; add_timer(timer);
271 * Note that if there are multiple unserialized concurrent users of the
272 * same timer, then mod_timer() is the only safe way to modify the timeout,
273 * since add_timer() cannot modify an already running timer.
275 * The function returns whether it has modified a pending timer or not.
276 * (ie. mod_timer() of an inactive timer returns 0, mod_timer() of an
277 * active timer returns 1.)
279 int mod_timer(struct timer_list *timer, unsigned long expires)
281 BUG_ON(!timer->function);
284 * This is a common optimization triggered by the
285 * networking code - if the timer is re-modified
286 * to be the same thing then just return:
288 if (timer->expires == expires && timer_pending(timer))
291 return __mod_timer(timer, expires);
294 EXPORT_SYMBOL(mod_timer);
297 * del_timer - deactive a timer.
298 * @timer: the timer to be deactivated
300 * del_timer() deactivates a timer - this works on both active and inactive
303 * The function returns whether it has deactivated a pending timer or not.
304 * (ie. del_timer() of an inactive timer returns 0, del_timer() of an
305 * active timer returns 1.)
307 int del_timer(struct timer_list *timer)
313 if (timer_pending(timer)) {
314 base = lock_timer_base(timer, &flags);
315 if (timer_pending(timer)) {
316 detach_timer(timer, 1);
319 spin_unlock_irqrestore(&base->lock, flags);
325 EXPORT_SYMBOL(del_timer);
329 * try_to_del_timer_sync - Try to deactivate a timer
330 * @timer: timer do del
332 * This function tries to deactivate a timer. Upon successful (ret >= 0)
333 * exit the timer is not queued and the handler is not running on any CPU.
335 * It must not be called from interrupt contexts.
337 int try_to_del_timer_sync(struct timer_list *timer)
343 base = lock_timer_base(timer, &flags);
345 if (base->running_timer == timer)
349 if (timer_pending(timer)) {
350 detach_timer(timer, 1);
354 spin_unlock_irqrestore(&base->lock, flags);
360 * del_timer_sync - deactivate a timer and wait for the handler to finish.
361 * @timer: the timer to be deactivated
363 * This function only differs from del_timer() on SMP: besides deactivating
364 * the timer it also makes sure the handler has finished executing on other
367 * Synchronization rules: callers must prevent restarting of the timer,
368 * otherwise this function is meaningless. It must not be called from
369 * interrupt contexts. The caller must not hold locks which would prevent
370 * completion of the timer's handler. The timer's handler must not call
371 * add_timer_on(). Upon exit the timer is not queued and the handler is
372 * not running on any CPU.
374 * The function returns whether it has deactivated a pending timer or not.
376 int del_timer_sync(struct timer_list *timer)
379 int ret = try_to_del_timer_sync(timer);
386 EXPORT_SYMBOL(del_timer_sync);
389 static int cascade(tvec_base_t *base, tvec_t *tv, int index)
391 /* cascade all the timers from tv up one level */
392 struct timer_list *timer, *tmp;
393 struct list_head tv_list;
395 list_replace_init(tv->vec + index, &tv_list);
398 * We are removing _all_ timers from the list, so we
399 * don't have to detach them individually.
401 list_for_each_entry_safe(timer, tmp, &tv_list, entry) {
402 BUG_ON(timer->base != base);
403 internal_add_timer(base, timer);
409 #define INDEX(N) ((base->timer_jiffies >> (TVR_BITS + (N) * TVN_BITS)) & TVN_MASK)
412 * __run_timers - run all expired timers (if any) on this CPU.
413 * @base: the timer vector to be processed.
415 * This function cascades all vectors and executes all expired timer
418 static inline void __run_timers(tvec_base_t *base)
420 struct timer_list *timer;
422 spin_lock_irq(&base->lock);
423 while (time_after_eq(jiffies, base->timer_jiffies)) {
424 struct list_head work_list;
425 struct list_head *head = &work_list;
426 int index = base->timer_jiffies & TVR_MASK;
432 (!cascade(base, &base->tv2, INDEX(0))) &&
433 (!cascade(base, &base->tv3, INDEX(1))) &&
434 !cascade(base, &base->tv4, INDEX(2)))
435 cascade(base, &base->tv5, INDEX(3));
436 ++base->timer_jiffies;
437 list_replace_init(base->tv1.vec + index, &work_list);
438 while (!list_empty(head)) {
439 void (*fn)(unsigned long);
442 timer = list_entry(head->next,struct timer_list,entry);
443 fn = timer->function;
446 set_running_timer(base, timer);
447 detach_timer(timer, 1);
448 spin_unlock_irq(&base->lock);
450 int preempt_count = preempt_count();
452 if (preempt_count != preempt_count()) {
453 printk(KERN_WARNING "huh, entered %p "
454 "with preempt_count %08x, exited"
461 spin_lock_irq(&base->lock);
464 set_running_timer(base, NULL);
465 spin_unlock_irq(&base->lock);
468 #ifdef CONFIG_NO_IDLE_HZ
470 * Find out when the next timer event is due to happen. This
471 * is used on S/390 to stop all activity when a cpus is idle.
472 * This functions needs to be called disabled.
474 unsigned long next_timer_interrupt(void)
477 struct list_head *list;
478 struct timer_list *nte;
479 unsigned long expires;
480 unsigned long hr_expires = MAX_JIFFY_OFFSET;
485 hr_delta = hrtimer_get_next_event();
486 if (hr_delta.tv64 != KTIME_MAX) {
487 struct timespec tsdelta;
488 tsdelta = ktime_to_timespec(hr_delta);
489 hr_expires = timespec_to_jiffies(&tsdelta);
491 return hr_expires + jiffies;
493 hr_expires += jiffies;
495 base = __get_cpu_var(tvec_bases);
496 spin_lock(&base->lock);
497 expires = base->timer_jiffies + (LONG_MAX >> 1);
500 /* Look for timer events in tv1. */
501 j = base->timer_jiffies & TVR_MASK;
503 list_for_each_entry(nte, base->tv1.vec + j, entry) {
504 expires = nte->expires;
505 if (j < (base->timer_jiffies & TVR_MASK))
506 list = base->tv2.vec + (INDEX(0));
509 j = (j + 1) & TVR_MASK;
510 } while (j != (base->timer_jiffies & TVR_MASK));
513 varray[0] = &base->tv2;
514 varray[1] = &base->tv3;
515 varray[2] = &base->tv4;
516 varray[3] = &base->tv5;
517 for (i = 0; i < 4; i++) {
520 if (list_empty(varray[i]->vec + j)) {
521 j = (j + 1) & TVN_MASK;
524 list_for_each_entry(nte, varray[i]->vec + j, entry)
525 if (time_before(nte->expires, expires))
526 expires = nte->expires;
527 if (j < (INDEX(i)) && i < 3)
528 list = varray[i + 1]->vec + (INDEX(i + 1));
530 } while (j != (INDEX(i)));
535 * The search wrapped. We need to look at the next list
536 * from next tv element that would cascade into tv element
537 * where we found the timer element.
539 list_for_each_entry(nte, list, entry) {
540 if (time_before(nte->expires, expires))
541 expires = nte->expires;
544 spin_unlock(&base->lock);
547 * It can happen that other CPUs service timer IRQs and increment
548 * jiffies, but we have not yet got a local timer tick to process
549 * the timer wheels. In that case, the expiry time can be before
550 * jiffies, but since the high-resolution timer here is relative to
551 * jiffies, the default expression when high-resolution timers are
554 * time_before(MAX_JIFFY_OFFSET + jiffies, expires)
556 * would falsely evaluate to true. If that is the case, just
557 * return jiffies so that we can immediately fire the local timer
559 if (time_before(expires, jiffies))
562 if (time_before(hr_expires, expires))
569 /******************************************************************/
572 * Timekeeping variables
574 unsigned long tick_usec = TICK_USEC; /* USER_HZ period (usec) */
575 unsigned long tick_nsec = TICK_NSEC; /* ACTHZ period (nsec) */
579 * wall_to_monotonic is what we need to add to xtime (or xtime corrected
580 * for sub jiffie times) to get to monotonic time. Monotonic is pegged
581 * at zero at system boot time, so wall_to_monotonic will be negative,
582 * however, we will ALWAYS keep the tv_nsec part positive so we can use
583 * the usual normalization.
585 struct timespec xtime __attribute__ ((aligned (16)));
586 struct timespec wall_to_monotonic __attribute__ ((aligned (16)));
588 EXPORT_SYMBOL(xtime);
590 /* Don't completely fail for HZ > 500. */
591 int tickadj = 500/HZ ? : 1; /* microsecs */
595 * phase-lock loop variables
597 /* TIME_ERROR prevents overwriting the CMOS clock */
598 int time_state = TIME_OK; /* clock synchronization status */
599 int time_status = STA_UNSYNC; /* clock status bits */
600 long time_offset; /* time adjustment (us) */
601 long time_constant = 2; /* pll time constant */
602 long time_tolerance = MAXFREQ; /* frequency tolerance (ppm) */
603 long time_precision = 1; /* clock precision (us) */
604 long time_maxerror = NTP_PHASE_LIMIT; /* maximum error (us) */
605 long time_esterror = NTP_PHASE_LIMIT; /* estimated error (us) */
606 long time_freq = (((NSEC_PER_SEC + HZ/2) % HZ - HZ/2) << SHIFT_USEC) / NSEC_PER_USEC;
607 /* frequency offset (scaled ppm)*/
608 static long time_adj; /* tick adjust (scaled 1 / HZ) */
609 long time_reftime; /* time at last adjustment (s) */
611 long time_next_adjust;
614 * this routine handles the overflow of the microsecond field
616 * The tricky bits of code to handle the accurate clock support
617 * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
618 * They were originally developed for SUN and DEC kernels.
619 * All the kudos should go to Dave for this stuff.
622 static void second_overflow(void)
626 /* Bump the maxerror field */
627 time_maxerror += time_tolerance >> SHIFT_USEC;
628 if (time_maxerror > NTP_PHASE_LIMIT) {
629 time_maxerror = NTP_PHASE_LIMIT;
630 time_status |= STA_UNSYNC;
634 * Leap second processing. If in leap-insert state at the end of the
635 * day, the system clock is set back one second; if in leap-delete
636 * state, the system clock is set ahead one second. The microtime()
637 * routine or external clock driver will insure that reported time is
638 * always monotonic. The ugly divides should be replaced.
640 switch (time_state) {
642 if (time_status & STA_INS)
643 time_state = TIME_INS;
644 else if (time_status & STA_DEL)
645 time_state = TIME_DEL;
648 if (xtime.tv_sec % 86400 == 0) {
650 wall_to_monotonic.tv_sec++;
652 * The timer interpolator will make time change
653 * gradually instead of an immediate jump by one second
655 time_interpolator_update(-NSEC_PER_SEC);
656 time_state = TIME_OOP;
658 printk(KERN_NOTICE "Clock: inserting leap second "
663 if ((xtime.tv_sec + 1) % 86400 == 0) {
665 wall_to_monotonic.tv_sec--;
667 * Use of time interpolator for a gradual change of
670 time_interpolator_update(NSEC_PER_SEC);
671 time_state = TIME_WAIT;
673 printk(KERN_NOTICE "Clock: deleting leap second "
678 time_state = TIME_WAIT;
681 if (!(time_status & (STA_INS | STA_DEL)))
682 time_state = TIME_OK;
686 * Compute the phase adjustment for the next second. In PLL mode, the
687 * offset is reduced by a fixed factor times the time constant. In FLL
688 * mode the offset is used directly. In either mode, the maximum phase
689 * adjustment for each second is clamped so as to spread the adjustment
690 * over not more than the number of seconds between updates.
693 if (!(time_status & STA_FLL))
694 ltemp = shift_right(ltemp, SHIFT_KG + time_constant);
695 ltemp = min(ltemp, (MAXPHASE / MINSEC) << SHIFT_UPDATE);
696 ltemp = max(ltemp, -(MAXPHASE / MINSEC) << SHIFT_UPDATE);
697 time_offset -= ltemp;
698 time_adj = ltemp << (SHIFT_SCALE - SHIFT_HZ - SHIFT_UPDATE);
701 * Compute the frequency estimate and additional phase adjustment due
702 * to frequency error for the next second.
705 time_adj += shift_right(ltemp,(SHIFT_USEC + SHIFT_HZ - SHIFT_SCALE));
709 * Compensate for (HZ==100) != (1 << SHIFT_HZ). Add 25% and 3.125% to
710 * get 128.125; => only 0.125% error (p. 14)
712 time_adj += shift_right(time_adj, 2) + shift_right(time_adj, 5);
716 * Compensate for (HZ==250) != (1 << SHIFT_HZ). Add 1.5625% and
717 * 0.78125% to get 255.85938; => only 0.05% error (p. 14)
719 time_adj += shift_right(time_adj, 6) + shift_right(time_adj, 7);
723 * Compensate for (HZ==1000) != (1 << SHIFT_HZ). Add 1.5625% and
724 * 0.78125% to get 1023.4375; => only 0.05% error (p. 14)
726 time_adj += shift_right(time_adj, 6) + shift_right(time_adj, 7);
731 * Returns how many microseconds we need to add to xtime this tick
732 * in doing an adjustment requested with adjtime.
734 static long adjtime_adjustment(void)
736 long time_adjust_step;
738 time_adjust_step = time_adjust;
739 if (time_adjust_step) {
741 * We are doing an adjtime thing. Prepare time_adjust_step to
742 * be within bounds. Note that a positive time_adjust means we
743 * want the clock to run faster.
745 * Limit the amount of the step to be in the range
746 * -tickadj .. +tickadj
748 time_adjust_step = min(time_adjust_step, (long)tickadj);
749 time_adjust_step = max(time_adjust_step, (long)-tickadj);
751 return time_adjust_step;
754 /* in the NTP reference this is called "hardclock()" */
755 static void update_ntp_one_tick(void)
757 long time_adjust_step;
759 time_adjust_step = adjtime_adjustment();
760 if (time_adjust_step)
761 /* Reduce by this step the amount of time left */
762 time_adjust -= time_adjust_step;
764 /* Changes by adjtime() do not take effect till next tick. */
765 if (time_next_adjust != 0) {
766 time_adjust = time_next_adjust;
767 time_next_adjust = 0;
772 * Return how long ticks are at the moment, that is, how much time
773 * update_wall_time_one_tick will add to xtime next time we call it
774 * (assuming no calls to do_adjtimex in the meantime).
775 * The return value is in fixed-point nanoseconds shifted by the
776 * specified number of bits to the right of the binary point.
777 * This function has no side-effects.
779 u64 current_tick_length(void)
784 /* calculate the finest interval NTP will allow.
785 * ie: nanosecond value shifted by (SHIFT_SCALE - 10)
787 delta_nsec = tick_nsec + adjtime_adjustment() * 1000;
788 ret = (u64)delta_nsec << TICK_LENGTH_SHIFT;
789 ret += (s64)time_adj << (TICK_LENGTH_SHIFT - (SHIFT_SCALE - 10));
794 /* XXX - all of this timekeeping code should be later moved to time.c */
795 #include <linux/clocksource.h>
796 static struct clocksource *clock; /* pointer to current clocksource */
798 #ifdef CONFIG_GENERIC_TIME
800 * __get_nsec_offset - Returns nanoseconds since last call to periodic_hook
802 * private function, must hold xtime_lock lock when being
803 * called. Returns the number of nanoseconds since the
804 * last call to update_wall_time() (adjusted by NTP scaling)
806 static inline s64 __get_nsec_offset(void)
808 cycle_t cycle_now, cycle_delta;
811 /* read clocksource: */
812 cycle_now = clocksource_read(clock);
814 /* calculate the delta since the last update_wall_time: */
815 cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
817 /* convert to nanoseconds: */
818 ns_offset = cyc2ns(clock, cycle_delta);
824 * __get_realtime_clock_ts - Returns the time of day in a timespec
825 * @ts: pointer to the timespec to be set
827 * Returns the time of day in a timespec. Used by
828 * do_gettimeofday() and get_realtime_clock_ts().
830 static inline void __get_realtime_clock_ts(struct timespec *ts)
836 seq = read_seqbegin(&xtime_lock);
839 nsecs = __get_nsec_offset();
841 } while (read_seqretry(&xtime_lock, seq));
843 timespec_add_ns(ts, nsecs);
847 * getnstimeofday - Returns the time of day in a timespec
848 * @ts: pointer to the timespec to be set
850 * Returns the time of day in a timespec.
852 void getnstimeofday(struct timespec *ts)
854 __get_realtime_clock_ts(ts);
857 EXPORT_SYMBOL(getnstimeofday);
860 * do_gettimeofday - Returns the time of day in a timeval
861 * @tv: pointer to the timeval to be set
863 * NOTE: Users should be converted to using get_realtime_clock_ts()
865 void do_gettimeofday(struct timeval *tv)
869 __get_realtime_clock_ts(&now);
870 tv->tv_sec = now.tv_sec;
871 tv->tv_usec = now.tv_nsec/1000;
874 EXPORT_SYMBOL(do_gettimeofday);
876 * do_settimeofday - Sets the time of day
877 * @tv: pointer to the timespec variable containing the new time
879 * Sets the time of day to the new time and update NTP and notify hrtimers
881 int do_settimeofday(struct timespec *tv)
884 time_t wtm_sec, sec = tv->tv_sec;
885 long wtm_nsec, nsec = tv->tv_nsec;
887 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
890 write_seqlock_irqsave(&xtime_lock, flags);
892 nsec -= __get_nsec_offset();
894 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
895 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
897 set_normalized_timespec(&xtime, sec, nsec);
898 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
903 write_sequnlock_irqrestore(&xtime_lock, flags);
905 /* signal hrtimers about time change */
911 EXPORT_SYMBOL(do_settimeofday);
914 * change_clocksource - Swaps clocksources if a new one is available
916 * Accumulates current time interval and initializes new clocksource
918 static int change_clocksource(void)
920 struct clocksource *new;
923 new = clocksource_get_next();
925 now = clocksource_read(new);
926 nsec = __get_nsec_offset();
927 timespec_add_ns(&xtime, nsec);
930 clock->cycle_last = now;
931 printk(KERN_INFO "Time: %s clocksource has been installed.\n",
934 } else if (clock->update_callback) {
935 return clock->update_callback();
940 #define change_clocksource() (0)
944 * timeofday_is_continuous - check to see if timekeeping is free running
946 int timekeeping_is_continuous(void)
952 seq = read_seqbegin(&xtime_lock);
954 ret = clock->is_continuous;
956 } while (read_seqretry(&xtime_lock, seq));
962 * timekeeping_init - Initializes the clocksource and common timekeeping values
964 void __init timekeeping_init(void)
968 write_seqlock_irqsave(&xtime_lock, flags);
969 clock = clocksource_get_next();
970 clocksource_calculate_interval(clock, tick_nsec);
971 clock->cycle_last = clocksource_read(clock);
973 write_sequnlock_irqrestore(&xtime_lock, flags);
977 static int timekeeping_suspended;
979 * timekeeping_resume - Resumes the generic timekeeping subsystem.
982 * This is for the generic clocksource timekeeping.
983 * xtime/wall_to_monotonic/jiffies/wall_jiffies/etc are
984 * still managed by arch specific suspend/resume code.
986 static int timekeeping_resume(struct sys_device *dev)
990 write_seqlock_irqsave(&xtime_lock, flags);
991 /* restart the last cycle value */
992 clock->cycle_last = clocksource_read(clock);
994 timekeeping_suspended = 0;
995 write_sequnlock_irqrestore(&xtime_lock, flags);
999 static int timekeeping_suspend(struct sys_device *dev, pm_message_t state)
1001 unsigned long flags;
1003 write_seqlock_irqsave(&xtime_lock, flags);
1004 timekeeping_suspended = 1;
1005 write_sequnlock_irqrestore(&xtime_lock, flags);
1009 /* sysfs resume/suspend bits for timekeeping */
1010 static struct sysdev_class timekeeping_sysclass = {
1011 .resume = timekeeping_resume,
1012 .suspend = timekeeping_suspend,
1013 set_kset_name("timekeeping"),
1016 static struct sys_device device_timer = {
1018 .cls = &timekeeping_sysclass,
1021 static int __init timekeeping_init_device(void)
1023 int error = sysdev_class_register(&timekeeping_sysclass);
1025 error = sysdev_register(&device_timer);
1029 device_initcall(timekeeping_init_device);
1032 * If the error is already larger, we look ahead even further
1033 * to compensate for late or lost adjustments.
1035 static __always_inline int clocksource_bigadjust(s64 error, s64 *interval, s64 *offset)
1038 u32 look_ahead, adj;
1042 * Use the current error value to determine how much to look ahead.
1043 * The larger the error the slower we adjust for it to avoid problems
1044 * with losing too many ticks, otherwise we would overadjust and
1045 * produce an even larger error. The smaller the adjustment the
1046 * faster we try to adjust for it, as lost ticks can do less harm
1047 * here. This is tuned so that an error of about 1 msec is adusted
1048 * within about 1 sec (or 2^20 nsec in 2^SHIFT_HZ ticks).
1050 error2 = clock->error >> (TICK_LENGTH_SHIFT + 22 - 2 * SHIFT_HZ);
1051 error2 = abs(error2);
1052 for (look_ahead = 0; error2 > 0; look_ahead++)
1056 * Now calculate the error in (1 << look_ahead) ticks, but first
1057 * remove the single look ahead already included in the error.
1059 tick_error = current_tick_length() >> (TICK_LENGTH_SHIFT - clock->shift + 1);
1060 tick_error -= clock->xtime_interval >> 1;
1061 error = ((error - tick_error) >> look_ahead) + tick_error;
1063 /* Finally calculate the adjustment shift value. */
1068 *interval = -*interval;
1072 for (adj = 0; error > i; adj++)
1081 * Adjust the multiplier to reduce the error value,
1082 * this is optimized for the most common adjustments of -1,0,1,
1083 * for other values we can do a bit more work.
1085 static void clocksource_adjust(struct clocksource *clock, s64 offset)
1087 s64 error, interval = clock->cycle_interval;
1090 error = clock->error >> (TICK_LENGTH_SHIFT - clock->shift - 1);
1091 if (error > interval) {
1093 if (likely(error <= interval))
1096 adj = clocksource_bigadjust(error, &interval, &offset);
1097 } else if (error < -interval) {
1099 if (likely(error >= -interval)) {
1101 interval = -interval;
1104 adj = clocksource_bigadjust(error, &interval, &offset);
1109 clock->xtime_interval += interval;
1110 clock->xtime_nsec -= offset;
1111 clock->error -= (interval - offset) << (TICK_LENGTH_SHIFT - clock->shift);
1115 * update_wall_time - Uses the current clocksource to increment the wall time
1117 * Called from the timer interrupt, must hold a write on xtime_lock.
1119 static void update_wall_time(void)
1123 /* Make sure we're fully resumed: */
1124 if (unlikely(timekeeping_suspended))
1127 #ifdef CONFIG_GENERIC_TIME
1128 offset = (clocksource_read(clock) - clock->cycle_last) & clock->mask;
1130 offset = clock->cycle_interval;
1132 clock->xtime_nsec += (s64)xtime.tv_nsec << clock->shift;
1134 /* normally this loop will run just once, however in the
1135 * case of lost or late ticks, it will accumulate correctly.
1137 while (offset >= clock->cycle_interval) {
1138 /* accumulate one interval */
1139 clock->xtime_nsec += clock->xtime_interval;
1140 clock->cycle_last += clock->cycle_interval;
1141 offset -= clock->cycle_interval;
1143 if (clock->xtime_nsec >= (u64)NSEC_PER_SEC << clock->shift) {
1144 clock->xtime_nsec -= (u64)NSEC_PER_SEC << clock->shift;
1149 /* interpolator bits */
1150 time_interpolator_update(clock->xtime_interval
1152 /* increment the NTP state machine */
1153 update_ntp_one_tick();
1155 /* accumulate error between NTP and clock interval */
1156 clock->error += current_tick_length();
1157 clock->error -= clock->xtime_interval << (TICK_LENGTH_SHIFT - clock->shift);
1160 /* correct the clock when NTP error is too big */
1161 clocksource_adjust(clock, offset);
1163 /* store full nanoseconds into xtime */
1164 xtime.tv_nsec = (s64)clock->xtime_nsec >> clock->shift;
1165 clock->xtime_nsec -= (s64)xtime.tv_nsec << clock->shift;
1167 /* check to see if there is a new clocksource to use */
1168 if (change_clocksource()) {
1170 clock->xtime_nsec = 0;
1171 clocksource_calculate_interval(clock, tick_nsec);
1176 * Called from the timer interrupt handler to charge one tick to the current
1177 * process. user_tick is 1 if the tick is user time, 0 for system.
1179 void update_process_times(int user_tick)
1181 struct task_struct *p = current;
1182 int cpu = smp_processor_id();
1184 /* Note: this timer irq context must be accounted for as well. */
1186 account_user_time(p, jiffies_to_cputime(1));
1188 account_system_time(p, HARDIRQ_OFFSET, jiffies_to_cputime(1));
1190 if (rcu_pending(cpu))
1191 rcu_check_callbacks(cpu, user_tick);
1193 run_posix_cpu_timers(p);
1197 * Nr of active tasks - counted in fixed-point numbers
1199 static unsigned long count_active_tasks(void)
1201 return nr_active() * FIXED_1;
1205 * Hmm.. Changed this, as the GNU make sources (load.c) seems to
1206 * imply that avenrun[] is the standard name for this kind of thing.
1207 * Nothing else seems to be standardized: the fractional size etc
1208 * all seem to differ on different machines.
1210 * Requires xtime_lock to access.
1212 unsigned long avenrun[3];
1214 EXPORT_SYMBOL(avenrun);
1217 * calc_load - given tick count, update the avenrun load estimates.
1218 * This is called while holding a write_lock on xtime_lock.
1220 static inline void calc_load(unsigned long ticks)
1222 unsigned long active_tasks; /* fixed-point */
1223 static int count = LOAD_FREQ;
1228 active_tasks = count_active_tasks();
1229 CALC_LOAD(avenrun[0], EXP_1, active_tasks);
1230 CALC_LOAD(avenrun[1], EXP_5, active_tasks);
1231 CALC_LOAD(avenrun[2], EXP_15, active_tasks);
1235 /* jiffies at the most recent update of wall time */
1236 unsigned long wall_jiffies = INITIAL_JIFFIES;
1239 * This read-write spinlock protects us from races in SMP while
1240 * playing with xtime and avenrun.
1242 #ifndef ARCH_HAVE_XTIME_LOCK
1243 __cacheline_aligned_in_smp DEFINE_SEQLOCK(xtime_lock);
1245 EXPORT_SYMBOL(xtime_lock);
1249 * This function runs timers and the timer-tq in bottom half context.
1251 static void run_timer_softirq(struct softirq_action *h)
1253 tvec_base_t *base = __get_cpu_var(tvec_bases);
1255 hrtimer_run_queues();
1256 if (time_after_eq(jiffies, base->timer_jiffies))
1261 * Called by the local, per-CPU timer interrupt on SMP.
1263 void run_local_timers(void)
1265 raise_softirq(TIMER_SOFTIRQ);
1270 * Called by the timer interrupt. xtime_lock must already be taken
1273 static inline void update_times(void)
1275 unsigned long ticks;
1277 ticks = jiffies - wall_jiffies;
1278 wall_jiffies += ticks;
1284 * The 64-bit jiffies value is not atomic - you MUST NOT read it
1285 * without sampling the sequence number in xtime_lock.
1286 * jiffies is defined in the linker script...
1289 void do_timer(struct pt_regs *regs)
1292 /* prevent loading jiffies before storing new jiffies_64 value. */
1297 #ifdef __ARCH_WANT_SYS_ALARM
1300 * For backwards compatibility? This can be done in libc so Alpha
1301 * and all newer ports shouldn't need it.
1303 asmlinkage unsigned long sys_alarm(unsigned int seconds)
1305 return alarm_setitimer(seconds);
1313 * The Alpha uses getxpid, getxuid, and getxgid instead. Maybe this
1314 * should be moved into arch/i386 instead?
1318 * sys_getpid - return the thread group id of the current process
1320 * Note, despite the name, this returns the tgid not the pid. The tgid and
1321 * the pid are identical unless CLONE_THREAD was specified on clone() in
1322 * which case the tgid is the same in all threads of the same group.
1324 * This is SMP safe as current->tgid does not change.
1326 asmlinkage long sys_getpid(void)
1328 return current->tgid;
1332 * Accessing ->real_parent is not SMP-safe, it could
1333 * change from under us. However, we can use a stale
1334 * value of ->real_parent under rcu_read_lock(), see
1335 * release_task()->call_rcu(delayed_put_task_struct).
1337 asmlinkage long sys_getppid(void)
1342 pid = rcu_dereference(current->real_parent)->tgid;
1348 asmlinkage long sys_getuid(void)
1350 /* Only we change this so SMP safe */
1351 return current->uid;
1354 asmlinkage long sys_geteuid(void)
1356 /* Only we change this so SMP safe */
1357 return current->euid;
1360 asmlinkage long sys_getgid(void)
1362 /* Only we change this so SMP safe */
1363 return current->gid;
1366 asmlinkage long sys_getegid(void)
1368 /* Only we change this so SMP safe */
1369 return current->egid;
1374 static void process_timeout(unsigned long __data)
1376 wake_up_process((struct task_struct *)__data);
1380 * schedule_timeout - sleep until timeout
1381 * @timeout: timeout value in jiffies
1383 * Make the current task sleep until @timeout jiffies have
1384 * elapsed. The routine will return immediately unless
1385 * the current task state has been set (see set_current_state()).
1387 * You can set the task state as follows -
1389 * %TASK_UNINTERRUPTIBLE - at least @timeout jiffies are guaranteed to
1390 * pass before the routine returns. The routine will return 0
1392 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
1393 * delivered to the current task. In this case the remaining time
1394 * in jiffies will be returned, or 0 if the timer expired in time
1396 * The current task state is guaranteed to be TASK_RUNNING when this
1399 * Specifying a @timeout value of %MAX_SCHEDULE_TIMEOUT will schedule
1400 * the CPU away without a bound on the timeout. In this case the return
1401 * value will be %MAX_SCHEDULE_TIMEOUT.
1403 * In all cases the return value is guaranteed to be non-negative.
1405 fastcall signed long __sched schedule_timeout(signed long timeout)
1407 struct timer_list timer;
1408 unsigned long expire;
1412 case MAX_SCHEDULE_TIMEOUT:
1414 * These two special cases are useful to be comfortable
1415 * in the caller. Nothing more. We could take
1416 * MAX_SCHEDULE_TIMEOUT from one of the negative value
1417 * but I' d like to return a valid offset (>=0) to allow
1418 * the caller to do everything it want with the retval.
1424 * Another bit of PARANOID. Note that the retval will be
1425 * 0 since no piece of kernel is supposed to do a check
1426 * for a negative retval of schedule_timeout() (since it
1427 * should never happens anyway). You just have the printk()
1428 * that will tell you if something is gone wrong and where.
1432 printk(KERN_ERR "schedule_timeout: wrong timeout "
1433 "value %lx from %p\n", timeout,
1434 __builtin_return_address(0));
1435 current->state = TASK_RUNNING;
1440 expire = timeout + jiffies;
1442 setup_timer(&timer, process_timeout, (unsigned long)current);
1443 __mod_timer(&timer, expire);
1445 del_singleshot_timer_sync(&timer);
1447 timeout = expire - jiffies;
1450 return timeout < 0 ? 0 : timeout;
1452 EXPORT_SYMBOL(schedule_timeout);
1455 * We can use __set_current_state() here because schedule_timeout() calls
1456 * schedule() unconditionally.
1458 signed long __sched schedule_timeout_interruptible(signed long timeout)
1460 __set_current_state(TASK_INTERRUPTIBLE);
1461 return schedule_timeout(timeout);
1463 EXPORT_SYMBOL(schedule_timeout_interruptible);
1465 signed long __sched schedule_timeout_uninterruptible(signed long timeout)
1467 __set_current_state(TASK_UNINTERRUPTIBLE);
1468 return schedule_timeout(timeout);
1470 EXPORT_SYMBOL(schedule_timeout_uninterruptible);
1472 /* Thread ID - the internal kernel "pid" */
1473 asmlinkage long sys_gettid(void)
1475 return current->pid;
1479 * sys_sysinfo - fill in sysinfo struct
1480 * @info: pointer to buffer to fill
1482 asmlinkage long sys_sysinfo(struct sysinfo __user *info)
1485 unsigned long mem_total, sav_total;
1486 unsigned int mem_unit, bitcount;
1489 memset((char *)&val, 0, sizeof(struct sysinfo));
1493 seq = read_seqbegin(&xtime_lock);
1496 * This is annoying. The below is the same thing
1497 * posix_get_clock_monotonic() does, but it wants to
1498 * take the lock which we want to cover the loads stuff
1502 getnstimeofday(&tp);
1503 tp.tv_sec += wall_to_monotonic.tv_sec;
1504 tp.tv_nsec += wall_to_monotonic.tv_nsec;
1505 if (tp.tv_nsec - NSEC_PER_SEC >= 0) {
1506 tp.tv_nsec = tp.tv_nsec - NSEC_PER_SEC;
1509 val.uptime = tp.tv_sec + (tp.tv_nsec ? 1 : 0);
1511 val.loads[0] = avenrun[0] << (SI_LOAD_SHIFT - FSHIFT);
1512 val.loads[1] = avenrun[1] << (SI_LOAD_SHIFT - FSHIFT);
1513 val.loads[2] = avenrun[2] << (SI_LOAD_SHIFT - FSHIFT);
1515 val.procs = nr_threads;
1516 } while (read_seqretry(&xtime_lock, seq));
1522 * If the sum of all the available memory (i.e. ram + swap)
1523 * is less than can be stored in a 32 bit unsigned long then
1524 * we can be binary compatible with 2.2.x kernels. If not,
1525 * well, in that case 2.2.x was broken anyways...
1527 * -Erik Andersen <andersee@debian.org>
1530 mem_total = val.totalram + val.totalswap;
1531 if (mem_total < val.totalram || mem_total < val.totalswap)
1534 mem_unit = val.mem_unit;
1535 while (mem_unit > 1) {
1538 sav_total = mem_total;
1540 if (mem_total < sav_total)
1545 * If mem_total did not overflow, multiply all memory values by
1546 * val.mem_unit and set it to 1. This leaves things compatible
1547 * with 2.2.x, and also retains compatibility with earlier 2.4.x
1552 val.totalram <<= bitcount;
1553 val.freeram <<= bitcount;
1554 val.sharedram <<= bitcount;
1555 val.bufferram <<= bitcount;
1556 val.totalswap <<= bitcount;
1557 val.freeswap <<= bitcount;
1558 val.totalhigh <<= bitcount;
1559 val.freehigh <<= bitcount;
1562 if (copy_to_user(info, &val, sizeof(struct sysinfo)))
1569 * lockdep: we want to track each per-CPU base as a separate lock-class,
1570 * but timer-bases are kmalloc()-ed, so we need to attach separate
1573 static struct lock_class_key base_lock_keys[NR_CPUS];
1575 static int __devinit init_timers_cpu(int cpu)
1579 static char __devinitdata tvec_base_done[NR_CPUS];
1581 if (!tvec_base_done[cpu]) {
1582 static char boot_done;
1586 * The APs use this path later in boot
1588 base = kmalloc_node(sizeof(*base), GFP_KERNEL,
1592 memset(base, 0, sizeof(*base));
1593 per_cpu(tvec_bases, cpu) = base;
1596 * This is for the boot CPU - we use compile-time
1597 * static initialisation because per-cpu memory isn't
1598 * ready yet and because the memory allocators are not
1599 * initialised either.
1602 base = &boot_tvec_bases;
1604 tvec_base_done[cpu] = 1;
1606 base = per_cpu(tvec_bases, cpu);
1609 spin_lock_init(&base->lock);
1610 lockdep_set_class(&base->lock, base_lock_keys + cpu);
1612 for (j = 0; j < TVN_SIZE; j++) {
1613 INIT_LIST_HEAD(base->tv5.vec + j);
1614 INIT_LIST_HEAD(base->tv4.vec + j);
1615 INIT_LIST_HEAD(base->tv3.vec + j);
1616 INIT_LIST_HEAD(base->tv2.vec + j);
1618 for (j = 0; j < TVR_SIZE; j++)
1619 INIT_LIST_HEAD(base->tv1.vec + j);
1621 base->timer_jiffies = jiffies;
1625 #ifdef CONFIG_HOTPLUG_CPU
1626 static void migrate_timer_list(tvec_base_t *new_base, struct list_head *head)
1628 struct timer_list *timer;
1630 while (!list_empty(head)) {
1631 timer = list_entry(head->next, struct timer_list, entry);
1632 detach_timer(timer, 0);
1633 timer->base = new_base;
1634 internal_add_timer(new_base, timer);
1638 static void __devinit migrate_timers(int cpu)
1640 tvec_base_t *old_base;
1641 tvec_base_t *new_base;
1644 BUG_ON(cpu_online(cpu));
1645 old_base = per_cpu(tvec_bases, cpu);
1646 new_base = get_cpu_var(tvec_bases);
1648 local_irq_disable();
1649 spin_lock(&new_base->lock);
1650 spin_lock(&old_base->lock);
1652 BUG_ON(old_base->running_timer);
1654 for (i = 0; i < TVR_SIZE; i++)
1655 migrate_timer_list(new_base, old_base->tv1.vec + i);
1656 for (i = 0; i < TVN_SIZE; i++) {
1657 migrate_timer_list(new_base, old_base->tv2.vec + i);
1658 migrate_timer_list(new_base, old_base->tv3.vec + i);
1659 migrate_timer_list(new_base, old_base->tv4.vec + i);
1660 migrate_timer_list(new_base, old_base->tv5.vec + i);
1663 spin_unlock(&old_base->lock);
1664 spin_unlock(&new_base->lock);
1666 put_cpu_var(tvec_bases);
1668 #endif /* CONFIG_HOTPLUG_CPU */
1670 static int __cpuinit timer_cpu_notify(struct notifier_block *self,
1671 unsigned long action, void *hcpu)
1673 long cpu = (long)hcpu;
1675 case CPU_UP_PREPARE:
1676 if (init_timers_cpu(cpu) < 0)
1679 #ifdef CONFIG_HOTPLUG_CPU
1681 migrate_timers(cpu);
1690 static struct notifier_block __cpuinitdata timers_nb = {
1691 .notifier_call = timer_cpu_notify,
1695 void __init init_timers(void)
1697 int err = timer_cpu_notify(&timers_nb, (unsigned long)CPU_UP_PREPARE,
1698 (void *)(long)smp_processor_id());
1700 BUG_ON(err == NOTIFY_BAD);
1701 register_cpu_notifier(&timers_nb);
1702 open_softirq(TIMER_SOFTIRQ, run_timer_softirq, NULL);
1705 #ifdef CONFIG_TIME_INTERPOLATION
1707 struct time_interpolator *time_interpolator __read_mostly;
1708 static struct time_interpolator *time_interpolator_list __read_mostly;
1709 static DEFINE_SPINLOCK(time_interpolator_lock);
1711 static inline u64 time_interpolator_get_cycles(unsigned int src)
1713 unsigned long (*x)(void);
1717 case TIME_SOURCE_FUNCTION:
1718 x = time_interpolator->addr;
1721 case TIME_SOURCE_MMIO64 :
1722 return readq_relaxed((void __iomem *)time_interpolator->addr);
1724 case TIME_SOURCE_MMIO32 :
1725 return readl_relaxed((void __iomem *)time_interpolator->addr);
1727 default: return get_cycles();
1731 static inline u64 time_interpolator_get_counter(int writelock)
1733 unsigned int src = time_interpolator->source;
1735 if (time_interpolator->jitter)
1741 lcycle = time_interpolator->last_cycle;
1742 now = time_interpolator_get_cycles(src);
1743 if (lcycle && time_after(lcycle, now))
1746 /* When holding the xtime write lock, there's no need
1747 * to add the overhead of the cmpxchg. Readers are
1748 * force to retry until the write lock is released.
1751 time_interpolator->last_cycle = now;
1754 /* Keep track of the last timer value returned. The use of cmpxchg here
1755 * will cause contention in an SMP environment.
1757 } while (unlikely(cmpxchg(&time_interpolator->last_cycle, lcycle, now) != lcycle));
1761 return time_interpolator_get_cycles(src);
1764 void time_interpolator_reset(void)
1766 time_interpolator->offset = 0;
1767 time_interpolator->last_counter = time_interpolator_get_counter(1);
1770 #define GET_TI_NSECS(count,i) (((((count) - i->last_counter) & (i)->mask) * (i)->nsec_per_cyc) >> (i)->shift)
1772 unsigned long time_interpolator_get_offset(void)
1774 /* If we do not have a time interpolator set up then just return zero */
1775 if (!time_interpolator)
1778 return time_interpolator->offset +
1779 GET_TI_NSECS(time_interpolator_get_counter(0), time_interpolator);
1782 #define INTERPOLATOR_ADJUST 65536
1783 #define INTERPOLATOR_MAX_SKIP 10*INTERPOLATOR_ADJUST
1785 static void time_interpolator_update(long delta_nsec)
1788 unsigned long offset;
1790 /* If there is no time interpolator set up then do nothing */
1791 if (!time_interpolator)
1795 * The interpolator compensates for late ticks by accumulating the late
1796 * time in time_interpolator->offset. A tick earlier than expected will
1797 * lead to a reset of the offset and a corresponding jump of the clock
1798 * forward. Again this only works if the interpolator clock is running
1799 * slightly slower than the regular clock and the tuning logic insures
1803 counter = time_interpolator_get_counter(1);
1804 offset = time_interpolator->offset +
1805 GET_TI_NSECS(counter, time_interpolator);
1807 if (delta_nsec < 0 || (unsigned long) delta_nsec < offset)
1808 time_interpolator->offset = offset - delta_nsec;
1810 time_interpolator->skips++;
1811 time_interpolator->ns_skipped += delta_nsec - offset;
1812 time_interpolator->offset = 0;
1814 time_interpolator->last_counter = counter;
1816 /* Tuning logic for time interpolator invoked every minute or so.
1817 * Decrease interpolator clock speed if no skips occurred and an offset is carried.
1818 * Increase interpolator clock speed if we skip too much time.
1820 if (jiffies % INTERPOLATOR_ADJUST == 0)
1822 if (time_interpolator->skips == 0 && time_interpolator->offset > tick_nsec)
1823 time_interpolator->nsec_per_cyc--;
1824 if (time_interpolator->ns_skipped > INTERPOLATOR_MAX_SKIP && time_interpolator->offset == 0)
1825 time_interpolator->nsec_per_cyc++;
1826 time_interpolator->skips = 0;
1827 time_interpolator->ns_skipped = 0;
1832 is_better_time_interpolator(struct time_interpolator *new)
1834 if (!time_interpolator)
1836 return new->frequency > 2*time_interpolator->frequency ||
1837 (unsigned long)new->drift < (unsigned long)time_interpolator->drift;
1841 register_time_interpolator(struct time_interpolator *ti)
1843 unsigned long flags;
1846 BUG_ON(ti->frequency == 0 || ti->mask == 0);
1848 ti->nsec_per_cyc = ((u64)NSEC_PER_SEC << ti->shift) / ti->frequency;
1849 spin_lock(&time_interpolator_lock);
1850 write_seqlock_irqsave(&xtime_lock, flags);
1851 if (is_better_time_interpolator(ti)) {
1852 time_interpolator = ti;
1853 time_interpolator_reset();
1855 write_sequnlock_irqrestore(&xtime_lock, flags);
1857 ti->next = time_interpolator_list;
1858 time_interpolator_list = ti;
1859 spin_unlock(&time_interpolator_lock);
1863 unregister_time_interpolator(struct time_interpolator *ti)
1865 struct time_interpolator *curr, **prev;
1866 unsigned long flags;
1868 spin_lock(&time_interpolator_lock);
1869 prev = &time_interpolator_list;
1870 for (curr = *prev; curr; curr = curr->next) {
1878 write_seqlock_irqsave(&xtime_lock, flags);
1879 if (ti == time_interpolator) {
1880 /* we lost the best time-interpolator: */
1881 time_interpolator = NULL;
1882 /* find the next-best interpolator */
1883 for (curr = time_interpolator_list; curr; curr = curr->next)
1884 if (is_better_time_interpolator(curr))
1885 time_interpolator = curr;
1886 time_interpolator_reset();
1888 write_sequnlock_irqrestore(&xtime_lock, flags);
1889 spin_unlock(&time_interpolator_lock);
1891 #endif /* CONFIG_TIME_INTERPOLATION */
1894 * msleep - sleep safely even with waitqueue interruptions
1895 * @msecs: Time in milliseconds to sleep for
1897 void msleep(unsigned int msecs)
1899 unsigned long timeout = msecs_to_jiffies(msecs) + 1;
1902 timeout = schedule_timeout_uninterruptible(timeout);
1905 EXPORT_SYMBOL(msleep);
1908 * msleep_interruptible - sleep waiting for signals
1909 * @msecs: Time in milliseconds to sleep for
1911 unsigned long msleep_interruptible(unsigned int msecs)
1913 unsigned long timeout = msecs_to_jiffies(msecs) + 1;
1915 while (timeout && !signal_pending(current))
1916 timeout = schedule_timeout_interruptible(timeout);
1917 return jiffies_to_msecs(timeout);
1920 EXPORT_SYMBOL(msleep_interruptible);