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
263 * mod_timer is a more efficient way to update the expire field of an
264 * active timer (if the timer is inactive it will be activated)
266 * mod_timer(timer, expires) is equivalent to:
268 * del_timer(timer); timer->expires = expires; add_timer(timer);
270 * Note that if there are multiple unserialized concurrent users of the
271 * same timer, then mod_timer() is the only safe way to modify the timeout,
272 * since add_timer() cannot modify an already running timer.
274 * The function returns whether it has modified a pending timer or not.
275 * (ie. mod_timer() of an inactive timer returns 0, mod_timer() of an
276 * active timer returns 1.)
278 int mod_timer(struct timer_list *timer, unsigned long expires)
280 BUG_ON(!timer->function);
283 * This is a common optimization triggered by the
284 * networking code - if the timer is re-modified
285 * to be the same thing then just return:
287 if (timer->expires == expires && timer_pending(timer))
290 return __mod_timer(timer, expires);
293 EXPORT_SYMBOL(mod_timer);
296 * del_timer - deactive a timer.
297 * @timer: the timer to be deactivated
299 * del_timer() deactivates a timer - this works on both active and inactive
302 * The function returns whether it has deactivated a pending timer or not.
303 * (ie. del_timer() of an inactive timer returns 0, del_timer() of an
304 * active timer returns 1.)
306 int del_timer(struct timer_list *timer)
312 if (timer_pending(timer)) {
313 base = lock_timer_base(timer, &flags);
314 if (timer_pending(timer)) {
315 detach_timer(timer, 1);
318 spin_unlock_irqrestore(&base->lock, flags);
324 EXPORT_SYMBOL(del_timer);
328 * This function tries to deactivate a timer. Upon successful (ret >= 0)
329 * exit the timer is not queued and the handler is not running on any CPU.
331 * It must not be called from interrupt contexts.
333 int try_to_del_timer_sync(struct timer_list *timer)
339 base = lock_timer_base(timer, &flags);
341 if (base->running_timer == timer)
345 if (timer_pending(timer)) {
346 detach_timer(timer, 1);
350 spin_unlock_irqrestore(&base->lock, flags);
356 * del_timer_sync - deactivate a timer and wait for the handler to finish.
357 * @timer: the timer to be deactivated
359 * This function only differs from del_timer() on SMP: besides deactivating
360 * the timer it also makes sure the handler has finished executing on other
363 * Synchronization rules: callers must prevent restarting of the timer,
364 * otherwise this function is meaningless. It must not be called from
365 * interrupt contexts. The caller must not hold locks which would prevent
366 * completion of the timer's handler. The timer's handler must not call
367 * add_timer_on(). Upon exit the timer is not queued and the handler is
368 * not running on any CPU.
370 * The function returns whether it has deactivated a pending timer or not.
372 int del_timer_sync(struct timer_list *timer)
375 int ret = try_to_del_timer_sync(timer);
382 EXPORT_SYMBOL(del_timer_sync);
385 static int cascade(tvec_base_t *base, tvec_t *tv, int index)
387 /* cascade all the timers from tv up one level */
388 struct timer_list *timer, *tmp;
389 struct list_head tv_list;
391 list_replace_init(tv->vec + index, &tv_list);
394 * We are removing _all_ timers from the list, so we
395 * don't have to detach them individually.
397 list_for_each_entry_safe(timer, tmp, &tv_list, entry) {
398 BUG_ON(timer->base != base);
399 internal_add_timer(base, timer);
406 * __run_timers - run all expired timers (if any) on this CPU.
407 * @base: the timer vector to be processed.
409 * This function cascades all vectors and executes all expired timer
412 #define INDEX(N) ((base->timer_jiffies >> (TVR_BITS + (N) * TVN_BITS)) & TVN_MASK)
414 static inline void __run_timers(tvec_base_t *base)
416 struct timer_list *timer;
418 spin_lock_irq(&base->lock);
419 while (time_after_eq(jiffies, base->timer_jiffies)) {
420 struct list_head work_list;
421 struct list_head *head = &work_list;
422 int index = base->timer_jiffies & TVR_MASK;
428 (!cascade(base, &base->tv2, INDEX(0))) &&
429 (!cascade(base, &base->tv3, INDEX(1))) &&
430 !cascade(base, &base->tv4, INDEX(2)))
431 cascade(base, &base->tv5, INDEX(3));
432 ++base->timer_jiffies;
433 list_replace_init(base->tv1.vec + index, &work_list);
434 while (!list_empty(head)) {
435 void (*fn)(unsigned long);
438 timer = list_entry(head->next,struct timer_list,entry);
439 fn = timer->function;
442 set_running_timer(base, timer);
443 detach_timer(timer, 1);
444 spin_unlock_irq(&base->lock);
446 int preempt_count = preempt_count();
448 if (preempt_count != preempt_count()) {
449 printk(KERN_WARNING "huh, entered %p "
450 "with preempt_count %08x, exited"
457 spin_lock_irq(&base->lock);
460 set_running_timer(base, NULL);
461 spin_unlock_irq(&base->lock);
464 #ifdef CONFIG_NO_IDLE_HZ
466 * Find out when the next timer event is due to happen. This
467 * is used on S/390 to stop all activity when a cpus is idle.
468 * This functions needs to be called disabled.
470 unsigned long next_timer_interrupt(void)
473 struct list_head *list;
474 struct timer_list *nte;
475 unsigned long expires;
476 unsigned long hr_expires = MAX_JIFFY_OFFSET;
481 hr_delta = hrtimer_get_next_event();
482 if (hr_delta.tv64 != KTIME_MAX) {
483 struct timespec tsdelta;
484 tsdelta = ktime_to_timespec(hr_delta);
485 hr_expires = timespec_to_jiffies(&tsdelta);
487 return hr_expires + jiffies;
489 hr_expires += jiffies;
491 base = __get_cpu_var(tvec_bases);
492 spin_lock(&base->lock);
493 expires = base->timer_jiffies + (LONG_MAX >> 1);
496 /* Look for timer events in tv1. */
497 j = base->timer_jiffies & TVR_MASK;
499 list_for_each_entry(nte, base->tv1.vec + j, entry) {
500 expires = nte->expires;
501 if (j < (base->timer_jiffies & TVR_MASK))
502 list = base->tv2.vec + (INDEX(0));
505 j = (j + 1) & TVR_MASK;
506 } while (j != (base->timer_jiffies & TVR_MASK));
509 varray[0] = &base->tv2;
510 varray[1] = &base->tv3;
511 varray[2] = &base->tv4;
512 varray[3] = &base->tv5;
513 for (i = 0; i < 4; i++) {
516 if (list_empty(varray[i]->vec + j)) {
517 j = (j + 1) & TVN_MASK;
520 list_for_each_entry(nte, varray[i]->vec + j, entry)
521 if (time_before(nte->expires, expires))
522 expires = nte->expires;
523 if (j < (INDEX(i)) && i < 3)
524 list = varray[i + 1]->vec + (INDEX(i + 1));
526 } while (j != (INDEX(i)));
531 * The search wrapped. We need to look at the next list
532 * from next tv element that would cascade into tv element
533 * where we found the timer element.
535 list_for_each_entry(nte, list, entry) {
536 if (time_before(nte->expires, expires))
537 expires = nte->expires;
540 spin_unlock(&base->lock);
543 * It can happen that other CPUs service timer IRQs and increment
544 * jiffies, but we have not yet got a local timer tick to process
545 * the timer wheels. In that case, the expiry time can be before
546 * jiffies, but since the high-resolution timer here is relative to
547 * jiffies, the default expression when high-resolution timers are
550 * time_before(MAX_JIFFY_OFFSET + jiffies, expires)
552 * would falsely evaluate to true. If that is the case, just
553 * return jiffies so that we can immediately fire the local timer
555 if (time_before(expires, jiffies))
558 if (time_before(hr_expires, expires))
565 /******************************************************************/
568 * Timekeeping variables
570 unsigned long tick_usec = TICK_USEC; /* USER_HZ period (usec) */
571 unsigned long tick_nsec = TICK_NSEC; /* ACTHZ period (nsec) */
575 * wall_to_monotonic is what we need to add to xtime (or xtime corrected
576 * for sub jiffie times) to get to monotonic time. Monotonic is pegged
577 * at zero at system boot time, so wall_to_monotonic will be negative,
578 * however, we will ALWAYS keep the tv_nsec part positive so we can use
579 * the usual normalization.
581 struct timespec xtime __attribute__ ((aligned (16)));
582 struct timespec wall_to_monotonic __attribute__ ((aligned (16)));
584 EXPORT_SYMBOL(xtime);
586 /* Don't completely fail for HZ > 500. */
587 int tickadj = 500/HZ ? : 1; /* microsecs */
591 * phase-lock loop variables
593 /* TIME_ERROR prevents overwriting the CMOS clock */
594 int time_state = TIME_OK; /* clock synchronization status */
595 int time_status = STA_UNSYNC; /* clock status bits */
596 long time_offset; /* time adjustment (us) */
597 long time_constant = 2; /* pll time constant */
598 long time_tolerance = MAXFREQ; /* frequency tolerance (ppm) */
599 long time_precision = 1; /* clock precision (us) */
600 long time_maxerror = NTP_PHASE_LIMIT; /* maximum error (us) */
601 long time_esterror = NTP_PHASE_LIMIT; /* estimated error (us) */
602 long time_freq = (((NSEC_PER_SEC + HZ/2) % HZ - HZ/2) << SHIFT_USEC) / NSEC_PER_USEC;
603 /* frequency offset (scaled ppm)*/
604 static long time_adj; /* tick adjust (scaled 1 / HZ) */
605 long time_reftime; /* time at last adjustment (s) */
607 long time_next_adjust;
610 * this routine handles the overflow of the microsecond field
612 * The tricky bits of code to handle the accurate clock support
613 * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
614 * They were originally developed for SUN and DEC kernels.
615 * All the kudos should go to Dave for this stuff.
618 static void second_overflow(void)
622 /* Bump the maxerror field */
623 time_maxerror += time_tolerance >> SHIFT_USEC;
624 if (time_maxerror > NTP_PHASE_LIMIT) {
625 time_maxerror = NTP_PHASE_LIMIT;
626 time_status |= STA_UNSYNC;
630 * Leap second processing. If in leap-insert state at the end of the
631 * day, the system clock is set back one second; if in leap-delete
632 * state, the system clock is set ahead one second. The microtime()
633 * routine or external clock driver will insure that reported time is
634 * always monotonic. The ugly divides should be replaced.
636 switch (time_state) {
638 if (time_status & STA_INS)
639 time_state = TIME_INS;
640 else if (time_status & STA_DEL)
641 time_state = TIME_DEL;
644 if (xtime.tv_sec % 86400 == 0) {
646 wall_to_monotonic.tv_sec++;
648 * The timer interpolator will make time change
649 * gradually instead of an immediate jump by one second
651 time_interpolator_update(-NSEC_PER_SEC);
652 time_state = TIME_OOP;
654 printk(KERN_NOTICE "Clock: inserting leap second "
659 if ((xtime.tv_sec + 1) % 86400 == 0) {
661 wall_to_monotonic.tv_sec--;
663 * Use of time interpolator for a gradual change of
666 time_interpolator_update(NSEC_PER_SEC);
667 time_state = TIME_WAIT;
669 printk(KERN_NOTICE "Clock: deleting leap second "
674 time_state = TIME_WAIT;
677 if (!(time_status & (STA_INS | STA_DEL)))
678 time_state = TIME_OK;
682 * Compute the phase adjustment for the next second. In PLL mode, the
683 * offset is reduced by a fixed factor times the time constant. In FLL
684 * mode the offset is used directly. In either mode, the maximum phase
685 * adjustment for each second is clamped so as to spread the adjustment
686 * over not more than the number of seconds between updates.
689 if (!(time_status & STA_FLL))
690 ltemp = shift_right(ltemp, SHIFT_KG + time_constant);
691 ltemp = min(ltemp, (MAXPHASE / MINSEC) << SHIFT_UPDATE);
692 ltemp = max(ltemp, -(MAXPHASE / MINSEC) << SHIFT_UPDATE);
693 time_offset -= ltemp;
694 time_adj = ltemp << (SHIFT_SCALE - SHIFT_HZ - SHIFT_UPDATE);
697 * Compute the frequency estimate and additional phase adjustment due
698 * to frequency error for the next second.
701 time_adj += shift_right(ltemp,(SHIFT_USEC + SHIFT_HZ - SHIFT_SCALE));
705 * Compensate for (HZ==100) != (1 << SHIFT_HZ). Add 25% and 3.125% to
706 * get 128.125; => only 0.125% error (p. 14)
708 time_adj += shift_right(time_adj, 2) + shift_right(time_adj, 5);
712 * Compensate for (HZ==250) != (1 << SHIFT_HZ). Add 1.5625% and
713 * 0.78125% to get 255.85938; => only 0.05% error (p. 14)
715 time_adj += shift_right(time_adj, 6) + shift_right(time_adj, 7);
719 * Compensate for (HZ==1000) != (1 << SHIFT_HZ). Add 1.5625% and
720 * 0.78125% to get 1023.4375; => only 0.05% error (p. 14)
722 time_adj += shift_right(time_adj, 6) + shift_right(time_adj, 7);
727 * Returns how many microseconds we need to add to xtime this tick
728 * in doing an adjustment requested with adjtime.
730 static long adjtime_adjustment(void)
732 long time_adjust_step;
734 time_adjust_step = time_adjust;
735 if (time_adjust_step) {
737 * We are doing an adjtime thing. Prepare time_adjust_step to
738 * be within bounds. Note that a positive time_adjust means we
739 * want the clock to run faster.
741 * Limit the amount of the step to be in the range
742 * -tickadj .. +tickadj
744 time_adjust_step = min(time_adjust_step, (long)tickadj);
745 time_adjust_step = max(time_adjust_step, (long)-tickadj);
747 return time_adjust_step;
750 /* in the NTP reference this is called "hardclock()" */
751 static void update_ntp_one_tick(void)
753 long time_adjust_step;
755 time_adjust_step = adjtime_adjustment();
756 if (time_adjust_step)
757 /* Reduce by this step the amount of time left */
758 time_adjust -= time_adjust_step;
760 /* Changes by adjtime() do not take effect till next tick. */
761 if (time_next_adjust != 0) {
762 time_adjust = time_next_adjust;
763 time_next_adjust = 0;
768 * Return how long ticks are at the moment, that is, how much time
769 * update_wall_time_one_tick will add to xtime next time we call it
770 * (assuming no calls to do_adjtimex in the meantime).
771 * The return value is in fixed-point nanoseconds shifted by the
772 * specified number of bits to the right of the binary point.
773 * This function has no side-effects.
775 u64 current_tick_length(void)
780 /* calculate the finest interval NTP will allow.
781 * ie: nanosecond value shifted by (SHIFT_SCALE - 10)
783 delta_nsec = tick_nsec + adjtime_adjustment() * 1000;
784 ret = (u64)delta_nsec << TICK_LENGTH_SHIFT;
785 ret += (s64)time_adj << (TICK_LENGTH_SHIFT - (SHIFT_SCALE - 10));
790 /* XXX - all of this timekeeping code should be later moved to time.c */
791 #include <linux/clocksource.h>
792 static struct clocksource *clock; /* pointer to current clocksource */
794 #ifdef CONFIG_GENERIC_TIME
796 * __get_nsec_offset - Returns nanoseconds since last call to periodic_hook
798 * private function, must hold xtime_lock lock when being
799 * called. Returns the number of nanoseconds since the
800 * last call to update_wall_time() (adjusted by NTP scaling)
802 static inline s64 __get_nsec_offset(void)
804 cycle_t cycle_now, cycle_delta;
807 /* read clocksource: */
808 cycle_now = clocksource_read(clock);
810 /* calculate the delta since the last update_wall_time: */
811 cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
813 /* convert to nanoseconds: */
814 ns_offset = cyc2ns(clock, cycle_delta);
820 * __get_realtime_clock_ts - Returns the time of day in a timespec
821 * @ts: pointer to the timespec to be set
823 * Returns the time of day in a timespec. Used by
824 * do_gettimeofday() and get_realtime_clock_ts().
826 static inline void __get_realtime_clock_ts(struct timespec *ts)
832 seq = read_seqbegin(&xtime_lock);
835 nsecs = __get_nsec_offset();
837 } while (read_seqretry(&xtime_lock, seq));
839 timespec_add_ns(ts, nsecs);
843 * getnstimeofday - Returns the time of day in a timespec
844 * @ts: pointer to the timespec to be set
846 * Returns the time of day in a timespec.
848 void getnstimeofday(struct timespec *ts)
850 __get_realtime_clock_ts(ts);
853 EXPORT_SYMBOL(getnstimeofday);
856 * do_gettimeofday - Returns the time of day in a timeval
857 * @tv: pointer to the timeval to be set
859 * NOTE: Users should be converted to using get_realtime_clock_ts()
861 void do_gettimeofday(struct timeval *tv)
865 __get_realtime_clock_ts(&now);
866 tv->tv_sec = now.tv_sec;
867 tv->tv_usec = now.tv_nsec/1000;
870 EXPORT_SYMBOL(do_gettimeofday);
872 * do_settimeofday - Sets the time of day
873 * @tv: pointer to the timespec variable containing the new time
875 * Sets the time of day to the new time and update NTP and notify hrtimers
877 int do_settimeofday(struct timespec *tv)
880 time_t wtm_sec, sec = tv->tv_sec;
881 long wtm_nsec, nsec = tv->tv_nsec;
883 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
886 write_seqlock_irqsave(&xtime_lock, flags);
888 nsec -= __get_nsec_offset();
890 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
891 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
893 set_normalized_timespec(&xtime, sec, nsec);
894 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
899 write_sequnlock_irqrestore(&xtime_lock, flags);
901 /* signal hrtimers about time change */
907 EXPORT_SYMBOL(do_settimeofday);
910 * change_clocksource - Swaps clocksources if a new one is available
912 * Accumulates current time interval and initializes new clocksource
914 static int change_clocksource(void)
916 struct clocksource *new;
919 new = clocksource_get_next();
921 now = clocksource_read(new);
922 nsec = __get_nsec_offset();
923 timespec_add_ns(&xtime, nsec);
926 clock->cycle_last = now;
927 printk(KERN_INFO "Time: %s clocksource has been installed.\n",
930 } else if (clock->update_callback) {
931 return clock->update_callback();
936 #define change_clocksource() (0)
940 * timeofday_is_continuous - check to see if timekeeping is free running
942 int timekeeping_is_continuous(void)
948 seq = read_seqbegin(&xtime_lock);
950 ret = clock->is_continuous;
952 } while (read_seqretry(&xtime_lock, seq));
958 * timekeeping_init - Initializes the clocksource and common timekeeping values
960 void __init timekeeping_init(void)
964 write_seqlock_irqsave(&xtime_lock, flags);
965 clock = clocksource_get_next();
966 clocksource_calculate_interval(clock, tick_nsec);
967 clock->cycle_last = clocksource_read(clock);
969 write_sequnlock_irqrestore(&xtime_lock, flags);
973 static int timekeeping_suspended;
975 * timekeeping_resume - Resumes the generic timekeeping subsystem.
978 * This is for the generic clocksource timekeeping.
979 * xtime/wall_to_monotonic/jiffies/wall_jiffies/etc are
980 * still managed by arch specific suspend/resume code.
982 static int timekeeping_resume(struct sys_device *dev)
986 write_seqlock_irqsave(&xtime_lock, flags);
987 /* restart the last cycle value */
988 clock->cycle_last = clocksource_read(clock);
990 timekeeping_suspended = 0;
991 write_sequnlock_irqrestore(&xtime_lock, flags);
995 static int timekeeping_suspend(struct sys_device *dev, pm_message_t state)
999 write_seqlock_irqsave(&xtime_lock, flags);
1000 timekeeping_suspended = 1;
1001 write_sequnlock_irqrestore(&xtime_lock, flags);
1005 /* sysfs resume/suspend bits for timekeeping */
1006 static struct sysdev_class timekeeping_sysclass = {
1007 .resume = timekeeping_resume,
1008 .suspend = timekeeping_suspend,
1009 set_kset_name("timekeeping"),
1012 static struct sys_device device_timer = {
1014 .cls = &timekeeping_sysclass,
1017 static int __init timekeeping_init_device(void)
1019 int error = sysdev_class_register(&timekeeping_sysclass);
1021 error = sysdev_register(&device_timer);
1025 device_initcall(timekeeping_init_device);
1028 * If the error is already larger, we look ahead even further
1029 * to compensate for late or lost adjustments.
1031 static __always_inline int clocksource_bigadjust(s64 error, s64 *interval, s64 *offset)
1034 u32 look_ahead, adj;
1038 * Use the current error value to determine how much to look ahead.
1039 * The larger the error the slower we adjust for it to avoid problems
1040 * with losing too many ticks, otherwise we would overadjust and
1041 * produce an even larger error. The smaller the adjustment the
1042 * faster we try to adjust for it, as lost ticks can do less harm
1043 * here. This is tuned so that an error of about 1 msec is adusted
1044 * within about 1 sec (or 2^20 nsec in 2^SHIFT_HZ ticks).
1046 error2 = clock->error >> (TICK_LENGTH_SHIFT + 22 - 2 * SHIFT_HZ);
1047 error2 = abs(error2);
1048 for (look_ahead = 0; error2 > 0; look_ahead++)
1052 * Now calculate the error in (1 << look_ahead) ticks, but first
1053 * remove the single look ahead already included in the error.
1055 tick_error = current_tick_length() >> (TICK_LENGTH_SHIFT - clock->shift + 1);
1056 tick_error -= clock->xtime_interval >> 1;
1057 error = ((error - tick_error) >> look_ahead) + tick_error;
1059 /* Finally calculate the adjustment shift value. */
1064 *interval = -*interval;
1068 for (adj = 0; error > i; adj++)
1077 * Adjust the multiplier to reduce the error value,
1078 * this is optimized for the most common adjustments of -1,0,1,
1079 * for other values we can do a bit more work.
1081 static void clocksource_adjust(struct clocksource *clock, s64 offset)
1083 s64 error, interval = clock->cycle_interval;
1086 error = clock->error >> (TICK_LENGTH_SHIFT - clock->shift - 1);
1087 if (error > interval) {
1089 if (likely(error <= interval))
1092 adj = clocksource_bigadjust(error, &interval, &offset);
1093 } else if (error < -interval) {
1095 if (likely(error >= -interval)) {
1097 interval = -interval;
1100 adj = clocksource_bigadjust(error, &interval, &offset);
1105 clock->xtime_interval += interval;
1106 clock->xtime_nsec -= offset;
1107 clock->error -= (interval - offset) << (TICK_LENGTH_SHIFT - clock->shift);
1111 * update_wall_time - Uses the current clocksource to increment the wall time
1113 * Called from the timer interrupt, must hold a write on xtime_lock.
1115 static void update_wall_time(void)
1119 /* Make sure we're fully resumed: */
1120 if (unlikely(timekeeping_suspended))
1123 #ifdef CONFIG_GENERIC_TIME
1124 offset = (clocksource_read(clock) - clock->cycle_last) & clock->mask;
1126 offset = clock->cycle_interval;
1128 clock->xtime_nsec += (s64)xtime.tv_nsec << clock->shift;
1130 /* normally this loop will run just once, however in the
1131 * case of lost or late ticks, it will accumulate correctly.
1133 while (offset >= clock->cycle_interval) {
1134 /* accumulate one interval */
1135 clock->xtime_nsec += clock->xtime_interval;
1136 clock->cycle_last += clock->cycle_interval;
1137 offset -= clock->cycle_interval;
1139 if (clock->xtime_nsec >= (u64)NSEC_PER_SEC << clock->shift) {
1140 clock->xtime_nsec -= (u64)NSEC_PER_SEC << clock->shift;
1145 /* interpolator bits */
1146 time_interpolator_update(clock->xtime_interval
1148 /* increment the NTP state machine */
1149 update_ntp_one_tick();
1151 /* accumulate error between NTP and clock interval */
1152 clock->error += current_tick_length();
1153 clock->error -= clock->xtime_interval << (TICK_LENGTH_SHIFT - clock->shift);
1156 /* correct the clock when NTP error is too big */
1157 clocksource_adjust(clock, offset);
1159 /* store full nanoseconds into xtime */
1160 xtime.tv_nsec = (s64)clock->xtime_nsec >> clock->shift;
1161 clock->xtime_nsec -= (s64)xtime.tv_nsec << clock->shift;
1163 /* check to see if there is a new clocksource to use */
1164 if (change_clocksource()) {
1166 clock->xtime_nsec = 0;
1167 clocksource_calculate_interval(clock, tick_nsec);
1172 * Called from the timer interrupt handler to charge one tick to the current
1173 * process. user_tick is 1 if the tick is user time, 0 for system.
1175 void update_process_times(int user_tick)
1177 struct task_struct *p = current;
1178 int cpu = smp_processor_id();
1180 /* Note: this timer irq context must be accounted for as well. */
1182 account_user_time(p, jiffies_to_cputime(1));
1184 account_system_time(p, HARDIRQ_OFFSET, jiffies_to_cputime(1));
1186 if (rcu_pending(cpu))
1187 rcu_check_callbacks(cpu, user_tick);
1189 run_posix_cpu_timers(p);
1193 * Nr of active tasks - counted in fixed-point numbers
1195 static unsigned long count_active_tasks(void)
1197 return nr_active() * FIXED_1;
1201 * Hmm.. Changed this, as the GNU make sources (load.c) seems to
1202 * imply that avenrun[] is the standard name for this kind of thing.
1203 * Nothing else seems to be standardized: the fractional size etc
1204 * all seem to differ on different machines.
1206 * Requires xtime_lock to access.
1208 unsigned long avenrun[3];
1210 EXPORT_SYMBOL(avenrun);
1213 * calc_load - given tick count, update the avenrun load estimates.
1214 * This is called while holding a write_lock on xtime_lock.
1216 static inline void calc_load(unsigned long ticks)
1218 unsigned long active_tasks; /* fixed-point */
1219 static int count = LOAD_FREQ;
1224 active_tasks = count_active_tasks();
1225 CALC_LOAD(avenrun[0], EXP_1, active_tasks);
1226 CALC_LOAD(avenrun[1], EXP_5, active_tasks);
1227 CALC_LOAD(avenrun[2], EXP_15, active_tasks);
1231 /* jiffies at the most recent update of wall time */
1232 unsigned long wall_jiffies = INITIAL_JIFFIES;
1235 * This read-write spinlock protects us from races in SMP while
1236 * playing with xtime and avenrun.
1238 #ifndef ARCH_HAVE_XTIME_LOCK
1239 __cacheline_aligned_in_smp DEFINE_SEQLOCK(xtime_lock);
1241 EXPORT_SYMBOL(xtime_lock);
1245 * This function runs timers and the timer-tq in bottom half context.
1247 static void run_timer_softirq(struct softirq_action *h)
1249 tvec_base_t *base = __get_cpu_var(tvec_bases);
1251 hrtimer_run_queues();
1252 if (time_after_eq(jiffies, base->timer_jiffies))
1257 * Called by the local, per-CPU timer interrupt on SMP.
1259 void run_local_timers(void)
1261 raise_softirq(TIMER_SOFTIRQ);
1266 * Called by the timer interrupt. xtime_lock must already be taken
1269 static inline void update_times(void)
1271 unsigned long ticks;
1273 ticks = jiffies - wall_jiffies;
1274 wall_jiffies += ticks;
1280 * The 64-bit jiffies value is not atomic - you MUST NOT read it
1281 * without sampling the sequence number in xtime_lock.
1282 * jiffies is defined in the linker script...
1285 void do_timer(struct pt_regs *regs)
1288 /* prevent loading jiffies before storing new jiffies_64 value. */
1293 #ifdef __ARCH_WANT_SYS_ALARM
1296 * For backwards compatibility? This can be done in libc so Alpha
1297 * and all newer ports shouldn't need it.
1299 asmlinkage unsigned long sys_alarm(unsigned int seconds)
1301 return alarm_setitimer(seconds);
1309 * The Alpha uses getxpid, getxuid, and getxgid instead. Maybe this
1310 * should be moved into arch/i386 instead?
1314 * sys_getpid - return the thread group id of the current process
1316 * Note, despite the name, this returns the tgid not the pid. The tgid and
1317 * the pid are identical unless CLONE_THREAD was specified on clone() in
1318 * which case the tgid is the same in all threads of the same group.
1320 * This is SMP safe as current->tgid does not change.
1322 asmlinkage long sys_getpid(void)
1324 return current->tgid;
1328 * Accessing ->real_parent is not SMP-safe, it could
1329 * change from under us. However, we can use a stale
1330 * value of ->real_parent under rcu_read_lock(), see
1331 * release_task()->call_rcu(delayed_put_task_struct).
1333 asmlinkage long sys_getppid(void)
1338 pid = rcu_dereference(current->real_parent)->tgid;
1344 asmlinkage long sys_getuid(void)
1346 /* Only we change this so SMP safe */
1347 return current->uid;
1350 asmlinkage long sys_geteuid(void)
1352 /* Only we change this so SMP safe */
1353 return current->euid;
1356 asmlinkage long sys_getgid(void)
1358 /* Only we change this so SMP safe */
1359 return current->gid;
1362 asmlinkage long sys_getegid(void)
1364 /* Only we change this so SMP safe */
1365 return current->egid;
1370 static void process_timeout(unsigned long __data)
1372 wake_up_process((struct task_struct *)__data);
1376 * schedule_timeout - sleep until timeout
1377 * @timeout: timeout value in jiffies
1379 * Make the current task sleep until @timeout jiffies have
1380 * elapsed. The routine will return immediately unless
1381 * the current task state has been set (see set_current_state()).
1383 * You can set the task state as follows -
1385 * %TASK_UNINTERRUPTIBLE - at least @timeout jiffies are guaranteed to
1386 * pass before the routine returns. The routine will return 0
1388 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
1389 * delivered to the current task. In this case the remaining time
1390 * in jiffies will be returned, or 0 if the timer expired in time
1392 * The current task state is guaranteed to be TASK_RUNNING when this
1395 * Specifying a @timeout value of %MAX_SCHEDULE_TIMEOUT will schedule
1396 * the CPU away without a bound on the timeout. In this case the return
1397 * value will be %MAX_SCHEDULE_TIMEOUT.
1399 * In all cases the return value is guaranteed to be non-negative.
1401 fastcall signed long __sched schedule_timeout(signed long timeout)
1403 struct timer_list timer;
1404 unsigned long expire;
1408 case MAX_SCHEDULE_TIMEOUT:
1410 * These two special cases are useful to be comfortable
1411 * in the caller. Nothing more. We could take
1412 * MAX_SCHEDULE_TIMEOUT from one of the negative value
1413 * but I' d like to return a valid offset (>=0) to allow
1414 * the caller to do everything it want with the retval.
1420 * Another bit of PARANOID. Note that the retval will be
1421 * 0 since no piece of kernel is supposed to do a check
1422 * for a negative retval of schedule_timeout() (since it
1423 * should never happens anyway). You just have the printk()
1424 * that will tell you if something is gone wrong and where.
1428 printk(KERN_ERR "schedule_timeout: wrong timeout "
1429 "value %lx from %p\n", timeout,
1430 __builtin_return_address(0));
1431 current->state = TASK_RUNNING;
1436 expire = timeout + jiffies;
1438 setup_timer(&timer, process_timeout, (unsigned long)current);
1439 __mod_timer(&timer, expire);
1441 del_singleshot_timer_sync(&timer);
1443 timeout = expire - jiffies;
1446 return timeout < 0 ? 0 : timeout;
1448 EXPORT_SYMBOL(schedule_timeout);
1451 * We can use __set_current_state() here because schedule_timeout() calls
1452 * schedule() unconditionally.
1454 signed long __sched schedule_timeout_interruptible(signed long timeout)
1456 __set_current_state(TASK_INTERRUPTIBLE);
1457 return schedule_timeout(timeout);
1459 EXPORT_SYMBOL(schedule_timeout_interruptible);
1461 signed long __sched schedule_timeout_uninterruptible(signed long timeout)
1463 __set_current_state(TASK_UNINTERRUPTIBLE);
1464 return schedule_timeout(timeout);
1466 EXPORT_SYMBOL(schedule_timeout_uninterruptible);
1468 /* Thread ID - the internal kernel "pid" */
1469 asmlinkage long sys_gettid(void)
1471 return current->pid;
1475 * sys_sysinfo - fill in sysinfo struct
1477 asmlinkage long sys_sysinfo(struct sysinfo __user *info)
1480 unsigned long mem_total, sav_total;
1481 unsigned int mem_unit, bitcount;
1484 memset((char *)&val, 0, sizeof(struct sysinfo));
1488 seq = read_seqbegin(&xtime_lock);
1491 * This is annoying. The below is the same thing
1492 * posix_get_clock_monotonic() does, but it wants to
1493 * take the lock which we want to cover the loads stuff
1497 getnstimeofday(&tp);
1498 tp.tv_sec += wall_to_monotonic.tv_sec;
1499 tp.tv_nsec += wall_to_monotonic.tv_nsec;
1500 if (tp.tv_nsec - NSEC_PER_SEC >= 0) {
1501 tp.tv_nsec = tp.tv_nsec - NSEC_PER_SEC;
1504 val.uptime = tp.tv_sec + (tp.tv_nsec ? 1 : 0);
1506 val.loads[0] = avenrun[0] << (SI_LOAD_SHIFT - FSHIFT);
1507 val.loads[1] = avenrun[1] << (SI_LOAD_SHIFT - FSHIFT);
1508 val.loads[2] = avenrun[2] << (SI_LOAD_SHIFT - FSHIFT);
1510 val.procs = nr_threads;
1511 } while (read_seqretry(&xtime_lock, seq));
1517 * If the sum of all the available memory (i.e. ram + swap)
1518 * is less than can be stored in a 32 bit unsigned long then
1519 * we can be binary compatible with 2.2.x kernels. If not,
1520 * well, in that case 2.2.x was broken anyways...
1522 * -Erik Andersen <andersee@debian.org>
1525 mem_total = val.totalram + val.totalswap;
1526 if (mem_total < val.totalram || mem_total < val.totalswap)
1529 mem_unit = val.mem_unit;
1530 while (mem_unit > 1) {
1533 sav_total = mem_total;
1535 if (mem_total < sav_total)
1540 * If mem_total did not overflow, multiply all memory values by
1541 * val.mem_unit and set it to 1. This leaves things compatible
1542 * with 2.2.x, and also retains compatibility with earlier 2.4.x
1547 val.totalram <<= bitcount;
1548 val.freeram <<= bitcount;
1549 val.sharedram <<= bitcount;
1550 val.bufferram <<= bitcount;
1551 val.totalswap <<= bitcount;
1552 val.freeswap <<= bitcount;
1553 val.totalhigh <<= bitcount;
1554 val.freehigh <<= bitcount;
1557 if (copy_to_user(info, &val, sizeof(struct sysinfo)))
1564 * lockdep: we want to track each per-CPU base as a separate lock-class,
1565 * but timer-bases are kmalloc()-ed, so we need to attach separate
1568 static struct lock_class_key base_lock_keys[NR_CPUS];
1570 static int __devinit init_timers_cpu(int cpu)
1574 static char __devinitdata tvec_base_done[NR_CPUS];
1576 if (!tvec_base_done[cpu]) {
1577 static char boot_done;
1581 * The APs use this path later in boot
1583 base = kmalloc_node(sizeof(*base), GFP_KERNEL,
1587 memset(base, 0, sizeof(*base));
1588 per_cpu(tvec_bases, cpu) = base;
1591 * This is for the boot CPU - we use compile-time
1592 * static initialisation because per-cpu memory isn't
1593 * ready yet and because the memory allocators are not
1594 * initialised either.
1597 base = &boot_tvec_bases;
1599 tvec_base_done[cpu] = 1;
1601 base = per_cpu(tvec_bases, cpu);
1604 spin_lock_init(&base->lock);
1605 lockdep_set_class(&base->lock, base_lock_keys + cpu);
1607 for (j = 0; j < TVN_SIZE; j++) {
1608 INIT_LIST_HEAD(base->tv5.vec + j);
1609 INIT_LIST_HEAD(base->tv4.vec + j);
1610 INIT_LIST_HEAD(base->tv3.vec + j);
1611 INIT_LIST_HEAD(base->tv2.vec + j);
1613 for (j = 0; j < TVR_SIZE; j++)
1614 INIT_LIST_HEAD(base->tv1.vec + j);
1616 base->timer_jiffies = jiffies;
1620 #ifdef CONFIG_HOTPLUG_CPU
1621 static void migrate_timer_list(tvec_base_t *new_base, struct list_head *head)
1623 struct timer_list *timer;
1625 while (!list_empty(head)) {
1626 timer = list_entry(head->next, struct timer_list, entry);
1627 detach_timer(timer, 0);
1628 timer->base = new_base;
1629 internal_add_timer(new_base, timer);
1633 static void __devinit migrate_timers(int cpu)
1635 tvec_base_t *old_base;
1636 tvec_base_t *new_base;
1639 BUG_ON(cpu_online(cpu));
1640 old_base = per_cpu(tvec_bases, cpu);
1641 new_base = get_cpu_var(tvec_bases);
1643 local_irq_disable();
1644 spin_lock(&new_base->lock);
1645 spin_lock(&old_base->lock);
1647 BUG_ON(old_base->running_timer);
1649 for (i = 0; i < TVR_SIZE; i++)
1650 migrate_timer_list(new_base, old_base->tv1.vec + i);
1651 for (i = 0; i < TVN_SIZE; i++) {
1652 migrate_timer_list(new_base, old_base->tv2.vec + i);
1653 migrate_timer_list(new_base, old_base->tv3.vec + i);
1654 migrate_timer_list(new_base, old_base->tv4.vec + i);
1655 migrate_timer_list(new_base, old_base->tv5.vec + i);
1658 spin_unlock(&old_base->lock);
1659 spin_unlock(&new_base->lock);
1661 put_cpu_var(tvec_bases);
1663 #endif /* CONFIG_HOTPLUG_CPU */
1665 static int __cpuinit timer_cpu_notify(struct notifier_block *self,
1666 unsigned long action, void *hcpu)
1668 long cpu = (long)hcpu;
1670 case CPU_UP_PREPARE:
1671 if (init_timers_cpu(cpu) < 0)
1674 #ifdef CONFIG_HOTPLUG_CPU
1676 migrate_timers(cpu);
1685 static struct notifier_block __cpuinitdata timers_nb = {
1686 .notifier_call = timer_cpu_notify,
1690 void __init init_timers(void)
1692 timer_cpu_notify(&timers_nb, (unsigned long)CPU_UP_PREPARE,
1693 (void *)(long)smp_processor_id());
1694 register_cpu_notifier(&timers_nb);
1695 open_softirq(TIMER_SOFTIRQ, run_timer_softirq, NULL);
1698 #ifdef CONFIG_TIME_INTERPOLATION
1700 struct time_interpolator *time_interpolator __read_mostly;
1701 static struct time_interpolator *time_interpolator_list __read_mostly;
1702 static DEFINE_SPINLOCK(time_interpolator_lock);
1704 static inline u64 time_interpolator_get_cycles(unsigned int src)
1706 unsigned long (*x)(void);
1710 case TIME_SOURCE_FUNCTION:
1711 x = time_interpolator->addr;
1714 case TIME_SOURCE_MMIO64 :
1715 return readq_relaxed((void __iomem *)time_interpolator->addr);
1717 case TIME_SOURCE_MMIO32 :
1718 return readl_relaxed((void __iomem *)time_interpolator->addr);
1720 default: return get_cycles();
1724 static inline u64 time_interpolator_get_counter(int writelock)
1726 unsigned int src = time_interpolator->source;
1728 if (time_interpolator->jitter)
1734 lcycle = time_interpolator->last_cycle;
1735 now = time_interpolator_get_cycles(src);
1736 if (lcycle && time_after(lcycle, now))
1739 /* When holding the xtime write lock, there's no need
1740 * to add the overhead of the cmpxchg. Readers are
1741 * force to retry until the write lock is released.
1744 time_interpolator->last_cycle = now;
1747 /* Keep track of the last timer value returned. The use of cmpxchg here
1748 * will cause contention in an SMP environment.
1750 } while (unlikely(cmpxchg(&time_interpolator->last_cycle, lcycle, now) != lcycle));
1754 return time_interpolator_get_cycles(src);
1757 void time_interpolator_reset(void)
1759 time_interpolator->offset = 0;
1760 time_interpolator->last_counter = time_interpolator_get_counter(1);
1763 #define GET_TI_NSECS(count,i) (((((count) - i->last_counter) & (i)->mask) * (i)->nsec_per_cyc) >> (i)->shift)
1765 unsigned long time_interpolator_get_offset(void)
1767 /* If we do not have a time interpolator set up then just return zero */
1768 if (!time_interpolator)
1771 return time_interpolator->offset +
1772 GET_TI_NSECS(time_interpolator_get_counter(0), time_interpolator);
1775 #define INTERPOLATOR_ADJUST 65536
1776 #define INTERPOLATOR_MAX_SKIP 10*INTERPOLATOR_ADJUST
1778 static void time_interpolator_update(long delta_nsec)
1781 unsigned long offset;
1783 /* If there is no time interpolator set up then do nothing */
1784 if (!time_interpolator)
1788 * The interpolator compensates for late ticks by accumulating the late
1789 * time in time_interpolator->offset. A tick earlier than expected will
1790 * lead to a reset of the offset and a corresponding jump of the clock
1791 * forward. Again this only works if the interpolator clock is running
1792 * slightly slower than the regular clock and the tuning logic insures
1796 counter = time_interpolator_get_counter(1);
1797 offset = time_interpolator->offset +
1798 GET_TI_NSECS(counter, time_interpolator);
1800 if (delta_nsec < 0 || (unsigned long) delta_nsec < offset)
1801 time_interpolator->offset = offset - delta_nsec;
1803 time_interpolator->skips++;
1804 time_interpolator->ns_skipped += delta_nsec - offset;
1805 time_interpolator->offset = 0;
1807 time_interpolator->last_counter = counter;
1809 /* Tuning logic for time interpolator invoked every minute or so.
1810 * Decrease interpolator clock speed if no skips occurred and an offset is carried.
1811 * Increase interpolator clock speed if we skip too much time.
1813 if (jiffies % INTERPOLATOR_ADJUST == 0)
1815 if (time_interpolator->skips == 0 && time_interpolator->offset > tick_nsec)
1816 time_interpolator->nsec_per_cyc--;
1817 if (time_interpolator->ns_skipped > INTERPOLATOR_MAX_SKIP && time_interpolator->offset == 0)
1818 time_interpolator->nsec_per_cyc++;
1819 time_interpolator->skips = 0;
1820 time_interpolator->ns_skipped = 0;
1825 is_better_time_interpolator(struct time_interpolator *new)
1827 if (!time_interpolator)
1829 return new->frequency > 2*time_interpolator->frequency ||
1830 (unsigned long)new->drift < (unsigned long)time_interpolator->drift;
1834 register_time_interpolator(struct time_interpolator *ti)
1836 unsigned long flags;
1839 BUG_ON(ti->frequency == 0 || ti->mask == 0);
1841 ti->nsec_per_cyc = ((u64)NSEC_PER_SEC << ti->shift) / ti->frequency;
1842 spin_lock(&time_interpolator_lock);
1843 write_seqlock_irqsave(&xtime_lock, flags);
1844 if (is_better_time_interpolator(ti)) {
1845 time_interpolator = ti;
1846 time_interpolator_reset();
1848 write_sequnlock_irqrestore(&xtime_lock, flags);
1850 ti->next = time_interpolator_list;
1851 time_interpolator_list = ti;
1852 spin_unlock(&time_interpolator_lock);
1856 unregister_time_interpolator(struct time_interpolator *ti)
1858 struct time_interpolator *curr, **prev;
1859 unsigned long flags;
1861 spin_lock(&time_interpolator_lock);
1862 prev = &time_interpolator_list;
1863 for (curr = *prev; curr; curr = curr->next) {
1871 write_seqlock_irqsave(&xtime_lock, flags);
1872 if (ti == time_interpolator) {
1873 /* we lost the best time-interpolator: */
1874 time_interpolator = NULL;
1875 /* find the next-best interpolator */
1876 for (curr = time_interpolator_list; curr; curr = curr->next)
1877 if (is_better_time_interpolator(curr))
1878 time_interpolator = curr;
1879 time_interpolator_reset();
1881 write_sequnlock_irqrestore(&xtime_lock, flags);
1882 spin_unlock(&time_interpolator_lock);
1884 #endif /* CONFIG_TIME_INTERPOLATION */
1887 * msleep - sleep safely even with waitqueue interruptions
1888 * @msecs: Time in milliseconds to sleep for
1890 void msleep(unsigned int msecs)
1892 unsigned long timeout = msecs_to_jiffies(msecs) + 1;
1895 timeout = schedule_timeout_uninterruptible(timeout);
1898 EXPORT_SYMBOL(msleep);
1901 * msleep_interruptible - sleep waiting for signals
1902 * @msecs: Time in milliseconds to sleep for
1904 unsigned long msleep_interruptible(unsigned int msecs)
1906 unsigned long timeout = msecs_to_jiffies(msecs) + 1;
1908 while (timeout && !signal_pending(current))
1909 timeout = schedule_timeout_interruptible(timeout);
1910 return jiffies_to_msecs(timeout);
1913 EXPORT_SYMBOL(msleep_interruptible);