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:
58 #define TVN_BITS (CONFIG_BASE_SMALL ? 4 : 6)
59 #define TVR_BITS (CONFIG_BASE_SMALL ? 6 : 8)
60 #define TVN_SIZE (1 << TVN_BITS)
61 #define TVR_SIZE (1 << TVR_BITS)
62 #define TVN_MASK (TVN_SIZE - 1)
63 #define TVR_MASK (TVR_SIZE - 1)
67 struct timer_list *running_timer;
70 typedef struct tvec_s {
71 struct list_head vec[TVN_SIZE];
74 typedef struct tvec_root_s {
75 struct list_head vec[TVR_SIZE];
78 struct tvec_t_base_s {
79 struct timer_base_s t_base;
80 unsigned long timer_jiffies;
86 } ____cacheline_aligned_in_smp;
88 typedef struct tvec_t_base_s tvec_base_t;
89 static DEFINE_PER_CPU(tvec_base_t, tvec_bases);
91 static inline void set_running_timer(tvec_base_t *base,
92 struct timer_list *timer)
95 base->t_base.running_timer = timer;
99 static void internal_add_timer(tvec_base_t *base, struct timer_list *timer)
101 unsigned long expires = timer->expires;
102 unsigned long idx = expires - base->timer_jiffies;
103 struct list_head *vec;
105 if (idx < TVR_SIZE) {
106 int i = expires & TVR_MASK;
107 vec = base->tv1.vec + i;
108 } else if (idx < 1 << (TVR_BITS + TVN_BITS)) {
109 int i = (expires >> TVR_BITS) & TVN_MASK;
110 vec = base->tv2.vec + i;
111 } else if (idx < 1 << (TVR_BITS + 2 * TVN_BITS)) {
112 int i = (expires >> (TVR_BITS + TVN_BITS)) & TVN_MASK;
113 vec = base->tv3.vec + i;
114 } else if (idx < 1 << (TVR_BITS + 3 * TVN_BITS)) {
115 int i = (expires >> (TVR_BITS + 2 * TVN_BITS)) & TVN_MASK;
116 vec = base->tv4.vec + i;
117 } else if ((signed long) idx < 0) {
119 * Can happen if you add a timer with expires == jiffies,
120 * or you set a timer to go off in the past
122 vec = base->tv1.vec + (base->timer_jiffies & TVR_MASK);
125 /* If the timeout is larger than 0xffffffff on 64-bit
126 * architectures then we use the maximum timeout:
128 if (idx > 0xffffffffUL) {
130 expires = idx + base->timer_jiffies;
132 i = (expires >> (TVR_BITS + 3 * TVN_BITS)) & TVN_MASK;
133 vec = base->tv5.vec + i;
138 list_add_tail(&timer->entry, vec);
141 typedef struct timer_base_s timer_base_t;
143 * Used by TIMER_INITIALIZER, we can't use per_cpu(tvec_bases)
144 * at compile time, and we need timer->base to lock the timer.
146 timer_base_t __init_timer_base
147 ____cacheline_aligned_in_smp = { .lock = SPIN_LOCK_UNLOCKED };
148 EXPORT_SYMBOL(__init_timer_base);
151 * init_timer - initialize a timer.
152 * @timer: the timer to be initialized
154 * init_timer() must be done to a timer prior calling *any* of the
155 * other timer functions.
157 void fastcall init_timer(struct timer_list *timer)
159 timer->entry.next = NULL;
160 timer->base = &per_cpu(tvec_bases, raw_smp_processor_id()).t_base;
162 EXPORT_SYMBOL(init_timer);
164 static inline void detach_timer(struct timer_list *timer,
167 struct list_head *entry = &timer->entry;
169 __list_del(entry->prev, entry->next);
172 entry->prev = LIST_POISON2;
176 * We are using hashed locking: holding per_cpu(tvec_bases).t_base.lock
177 * means that all timers which are tied to this base via timer->base are
178 * locked, and the base itself is locked too.
180 * So __run_timers/migrate_timers can safely modify all timers which could
181 * be found on ->tvX lists.
183 * When the timer's base is locked, and the timer removed from list, it is
184 * possible to set timer->base = NULL and drop the lock: the timer remains
187 static timer_base_t *lock_timer_base(struct timer_list *timer,
188 unsigned long *flags)
194 if (likely(base != NULL)) {
195 spin_lock_irqsave(&base->lock, *flags);
196 if (likely(base == timer->base))
198 /* The timer has migrated to another CPU */
199 spin_unlock_irqrestore(&base->lock, *flags);
205 int __mod_timer(struct timer_list *timer, unsigned long expires)
208 tvec_base_t *new_base;
212 BUG_ON(!timer->function);
214 base = lock_timer_base(timer, &flags);
216 if (timer_pending(timer)) {
217 detach_timer(timer, 0);
221 new_base = &__get_cpu_var(tvec_bases);
223 if (base != &new_base->t_base) {
225 * We are trying to schedule the timer on the local CPU.
226 * However we can't change timer's base while it is running,
227 * otherwise del_timer_sync() can't detect that the timer's
228 * handler yet has not finished. This also guarantees that
229 * the timer is serialized wrt itself.
231 if (unlikely(base->running_timer == timer)) {
232 /* The timer remains on a former base */
233 new_base = container_of(base, tvec_base_t, t_base);
235 /* See the comment in lock_timer_base() */
237 spin_unlock(&base->lock);
238 spin_lock(&new_base->t_base.lock);
239 timer->base = &new_base->t_base;
243 timer->expires = expires;
244 internal_add_timer(new_base, timer);
245 spin_unlock_irqrestore(&new_base->t_base.lock, flags);
250 EXPORT_SYMBOL(__mod_timer);
253 * add_timer_on - start a timer on a particular CPU
254 * @timer: the timer to be added
255 * @cpu: the CPU to start it on
257 * This is not very scalable on SMP. Double adds are not possible.
259 void add_timer_on(struct timer_list *timer, int cpu)
261 tvec_base_t *base = &per_cpu(tvec_bases, cpu);
264 BUG_ON(timer_pending(timer) || !timer->function);
265 spin_lock_irqsave(&base->t_base.lock, flags);
266 timer->base = &base->t_base;
267 internal_add_timer(base, timer);
268 spin_unlock_irqrestore(&base->t_base.lock, flags);
273 * mod_timer - modify a timer's timeout
274 * @timer: the timer to be modified
276 * mod_timer is a more efficient way to update the expire field of an
277 * active timer (if the timer is inactive it will be activated)
279 * mod_timer(timer, expires) is equivalent to:
281 * del_timer(timer); timer->expires = expires; add_timer(timer);
283 * Note that if there are multiple unserialized concurrent users of the
284 * same timer, then mod_timer() is the only safe way to modify the timeout,
285 * since add_timer() cannot modify an already running timer.
287 * The function returns whether it has modified a pending timer or not.
288 * (ie. mod_timer() of an inactive timer returns 0, mod_timer() of an
289 * active timer returns 1.)
291 int mod_timer(struct timer_list *timer, unsigned long expires)
293 BUG_ON(!timer->function);
296 * This is a common optimization triggered by the
297 * networking code - if the timer is re-modified
298 * to be the same thing then just return:
300 if (timer->expires == expires && timer_pending(timer))
303 return __mod_timer(timer, expires);
306 EXPORT_SYMBOL(mod_timer);
309 * del_timer - deactive a timer.
310 * @timer: the timer to be deactivated
312 * del_timer() deactivates a timer - this works on both active and inactive
315 * The function returns whether it has deactivated a pending timer or not.
316 * (ie. del_timer() of an inactive timer returns 0, del_timer() of an
317 * active timer returns 1.)
319 int del_timer(struct timer_list *timer)
325 if (timer_pending(timer)) {
326 base = lock_timer_base(timer, &flags);
327 if (timer_pending(timer)) {
328 detach_timer(timer, 1);
331 spin_unlock_irqrestore(&base->lock, flags);
337 EXPORT_SYMBOL(del_timer);
341 * This function tries to deactivate a timer. Upon successful (ret >= 0)
342 * exit the timer is not queued and the handler is not running on any CPU.
344 * It must not be called from interrupt contexts.
346 int try_to_del_timer_sync(struct timer_list *timer)
352 base = lock_timer_base(timer, &flags);
354 if (base->running_timer == timer)
358 if (timer_pending(timer)) {
359 detach_timer(timer, 1);
363 spin_unlock_irqrestore(&base->lock, flags);
369 * del_timer_sync - deactivate a timer and wait for the handler to finish.
370 * @timer: the timer to be deactivated
372 * This function only differs from del_timer() on SMP: besides deactivating
373 * the timer it also makes sure the handler has finished executing on other
376 * Synchronization rules: callers must prevent restarting of the timer,
377 * otherwise this function is meaningless. It must not be called from
378 * interrupt contexts. The caller must not hold locks which would prevent
379 * completion of the timer's handler. The timer's handler must not call
380 * add_timer_on(). Upon exit the timer is not queued and the handler is
381 * not running on any CPU.
383 * The function returns whether it has deactivated a pending timer or not.
385 int del_timer_sync(struct timer_list *timer)
388 int ret = try_to_del_timer_sync(timer);
394 EXPORT_SYMBOL(del_timer_sync);
397 static int cascade(tvec_base_t *base, tvec_t *tv, int index)
399 /* cascade all the timers from tv up one level */
400 struct list_head *head, *curr;
402 head = tv->vec + index;
405 * We are removing _all_ timers from the list, so we don't have to
406 * detach them individually, just clear the list afterwards.
408 while (curr != head) {
409 struct timer_list *tmp;
411 tmp = list_entry(curr, struct timer_list, entry);
412 BUG_ON(tmp->base != &base->t_base);
414 internal_add_timer(base, tmp);
416 INIT_LIST_HEAD(head);
422 * __run_timers - run all expired timers (if any) on this CPU.
423 * @base: the timer vector to be processed.
425 * This function cascades all vectors and executes all expired timer
428 #define INDEX(N) (base->timer_jiffies >> (TVR_BITS + N * TVN_BITS)) & TVN_MASK
430 static inline void __run_timers(tvec_base_t *base)
432 struct timer_list *timer;
434 spin_lock_irq(&base->t_base.lock);
435 while (time_after_eq(jiffies, base->timer_jiffies)) {
436 struct list_head work_list = LIST_HEAD_INIT(work_list);
437 struct list_head *head = &work_list;
438 int index = base->timer_jiffies & TVR_MASK;
444 (!cascade(base, &base->tv2, INDEX(0))) &&
445 (!cascade(base, &base->tv3, INDEX(1))) &&
446 !cascade(base, &base->tv4, INDEX(2)))
447 cascade(base, &base->tv5, INDEX(3));
448 ++base->timer_jiffies;
449 list_splice_init(base->tv1.vec + index, &work_list);
450 while (!list_empty(head)) {
451 void (*fn)(unsigned long);
454 timer = list_entry(head->next,struct timer_list,entry);
455 fn = timer->function;
458 set_running_timer(base, timer);
459 detach_timer(timer, 1);
460 spin_unlock_irq(&base->t_base.lock);
462 int preempt_count = preempt_count();
464 if (preempt_count != preempt_count()) {
465 printk(KERN_WARNING "huh, entered %p "
466 "with preempt_count %08x, exited"
473 spin_lock_irq(&base->t_base.lock);
476 set_running_timer(base, NULL);
477 spin_unlock_irq(&base->t_base.lock);
480 #ifdef CONFIG_NO_IDLE_HZ
482 * Find out when the next timer event is due to happen. This
483 * is used on S/390 to stop all activity when a cpus is idle.
484 * This functions needs to be called disabled.
486 unsigned long next_timer_interrupt(void)
489 struct list_head *list;
490 struct timer_list *nte;
491 unsigned long expires, hr_expires = MAX_JIFFY_OFFSET;
496 hr_delta = hrtimer_get_next_event();
497 if (hr_delta.tv64 != KTIME_MAX) {
498 struct timespec tsdelta;
499 tsdelta = ktime_to_timespec(hr_delta);
500 hr_expires = timespec_to_jiffies(&tsdelta);
502 return hr_expires + jiffies;
504 hr_expires += jiffies;
506 base = &__get_cpu_var(tvec_bases);
507 spin_lock(&base->t_base.lock);
508 expires = base->timer_jiffies + (LONG_MAX >> 1);
511 /* Look for timer events in tv1. */
512 j = base->timer_jiffies & TVR_MASK;
514 list_for_each_entry(nte, base->tv1.vec + j, entry) {
515 expires = nte->expires;
516 if (j < (base->timer_jiffies & TVR_MASK))
517 list = base->tv2.vec + (INDEX(0));
520 j = (j + 1) & TVR_MASK;
521 } while (j != (base->timer_jiffies & TVR_MASK));
524 varray[0] = &base->tv2;
525 varray[1] = &base->tv3;
526 varray[2] = &base->tv4;
527 varray[3] = &base->tv5;
528 for (i = 0; i < 4; i++) {
531 if (list_empty(varray[i]->vec + j)) {
532 j = (j + 1) & TVN_MASK;
535 list_for_each_entry(nte, varray[i]->vec + j, entry)
536 if (time_before(nte->expires, expires))
537 expires = nte->expires;
538 if (j < (INDEX(i)) && i < 3)
539 list = varray[i + 1]->vec + (INDEX(i + 1));
541 } while (j != (INDEX(i)));
546 * The search wrapped. We need to look at the next list
547 * from next tv element that would cascade into tv element
548 * where we found the timer element.
550 list_for_each_entry(nte, list, entry) {
551 if (time_before(nte->expires, expires))
552 expires = nte->expires;
555 spin_unlock(&base->t_base.lock);
557 if (time_before(hr_expires, expires))
564 /******************************************************************/
567 * Timekeeping variables
569 unsigned long tick_usec = TICK_USEC; /* USER_HZ period (usec) */
570 unsigned long tick_nsec = TICK_NSEC; /* ACTHZ period (nsec) */
574 * wall_to_monotonic is what we need to add to xtime (or xtime corrected
575 * for sub jiffie times) to get to monotonic time. Monotonic is pegged
576 * at zero at system boot time, so wall_to_monotonic will be negative,
577 * however, we will ALWAYS keep the tv_nsec part positive so we can use
578 * the usual normalization.
580 struct timespec xtime __attribute__ ((aligned (16)));
581 struct timespec wall_to_monotonic __attribute__ ((aligned (16)));
583 EXPORT_SYMBOL(xtime);
585 /* Don't completely fail for HZ > 500. */
586 int tickadj = 500/HZ ? : 1; /* microsecs */
590 * phase-lock loop variables
592 /* TIME_ERROR prevents overwriting the CMOS clock */
593 int time_state = TIME_OK; /* clock synchronization status */
594 int time_status = STA_UNSYNC; /* clock status bits */
595 long time_offset; /* time adjustment (us) */
596 long time_constant = 2; /* pll time constant */
597 long time_tolerance = MAXFREQ; /* frequency tolerance (ppm) */
598 long time_precision = 1; /* clock precision (us) */
599 long time_maxerror = NTP_PHASE_LIMIT; /* maximum error (us) */
600 long time_esterror = NTP_PHASE_LIMIT; /* estimated error (us) */
601 static long time_phase; /* phase offset (scaled 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. When the PPS signal is
699 * engaged, gnaw on the watchdog counter and update the frequency
700 * computed by the pll and the PPS signal.
703 if (pps_valid == PPS_VALID) { /* PPS signal lost */
704 pps_jitter = MAXTIME;
705 pps_stabil = MAXFREQ;
706 time_status &= ~(STA_PPSSIGNAL | STA_PPSJITTER |
707 STA_PPSWANDER | STA_PPSERROR);
709 ltemp = time_freq + pps_freq;
710 time_adj += shift_right(ltemp,(SHIFT_USEC + SHIFT_HZ - SHIFT_SCALE));
714 * Compensate for (HZ==100) != (1 << SHIFT_HZ). Add 25% and 3.125% to
715 * get 128.125; => only 0.125% error (p. 14)
717 time_adj += shift_right(time_adj, 2) + shift_right(time_adj, 5);
721 * Compensate for (HZ==250) != (1 << SHIFT_HZ). Add 1.5625% and
722 * 0.78125% to get 255.85938; => only 0.05% error (p. 14)
724 time_adj += shift_right(time_adj, 6) + shift_right(time_adj, 7);
728 * Compensate for (HZ==1000) != (1 << SHIFT_HZ). Add 1.5625% and
729 * 0.78125% to get 1023.4375; => only 0.05% error (p. 14)
731 time_adj += shift_right(time_adj, 6) + shift_right(time_adj, 7);
736 * Returns how many microseconds we need to add to xtime this tick
737 * in doing an adjustment requested with adjtime.
739 static long adjtime_adjustment(void)
741 long time_adjust_step;
743 time_adjust_step = time_adjust;
744 if (time_adjust_step) {
746 * We are doing an adjtime thing. Prepare time_adjust_step to
747 * be within bounds. Note that a positive time_adjust means we
748 * want the clock to run faster.
750 * Limit the amount of the step to be in the range
751 * -tickadj .. +tickadj
753 time_adjust_step = min(time_adjust_step, (long)tickadj);
754 time_adjust_step = max(time_adjust_step, (long)-tickadj);
756 return time_adjust_step;
759 /* in the NTP reference this is called "hardclock()" */
760 static void update_wall_time_one_tick(void)
762 long time_adjust_step, delta_nsec;
764 time_adjust_step = adjtime_adjustment();
765 if (time_adjust_step)
766 /* Reduce by this step the amount of time left */
767 time_adjust -= time_adjust_step;
768 delta_nsec = tick_nsec + time_adjust_step * 1000;
770 * Advance the phase, once it gets to one microsecond, then
771 * advance the tick more.
773 time_phase += time_adj;
774 if ((time_phase >= FINENSEC) || (time_phase <= -FINENSEC)) {
775 long ltemp = shift_right(time_phase, (SHIFT_SCALE - 10));
776 time_phase -= ltemp << (SHIFT_SCALE - 10);
779 xtime.tv_nsec += delta_nsec;
780 time_interpolator_update(delta_nsec);
782 /* Changes by adjtime() do not take effect till next tick. */
783 if (time_next_adjust != 0) {
784 time_adjust = time_next_adjust;
785 time_next_adjust = 0;
790 * Return how long ticks are at the moment, that is, how much time
791 * update_wall_time_one_tick will add to xtime next time we call it
792 * (assuming no calls to do_adjtimex in the meantime).
793 * The return value is in fixed-point nanoseconds with SHIFT_SCALE-10
794 * bits to the right of the binary point.
795 * This function has no side-effects.
797 u64 current_tick_length(void)
801 delta_nsec = tick_nsec + adjtime_adjustment() * 1000;
802 return ((u64) delta_nsec << (SHIFT_SCALE - 10)) + time_adj;
806 * Using a loop looks inefficient, but "ticks" is
807 * usually just one (we shouldn't be losing ticks,
808 * we're doing this this way mainly for interrupt
809 * latency reasons, not because we think we'll
810 * have lots of lost timer ticks
812 static void update_wall_time(unsigned long ticks)
816 update_wall_time_one_tick();
817 if (xtime.tv_nsec >= 1000000000) {
818 xtime.tv_nsec -= 1000000000;
826 * Called from the timer interrupt handler to charge one tick to the current
827 * process. user_tick is 1 if the tick is user time, 0 for system.
829 void update_process_times(int user_tick)
831 struct task_struct *p = current;
832 int cpu = smp_processor_id();
834 /* Note: this timer irq context must be accounted for as well. */
836 account_user_time(p, jiffies_to_cputime(1));
838 account_system_time(p, HARDIRQ_OFFSET, jiffies_to_cputime(1));
840 if (rcu_pending(cpu))
841 rcu_check_callbacks(cpu, user_tick);
843 run_posix_cpu_timers(p);
847 * Nr of active tasks - counted in fixed-point numbers
849 static unsigned long count_active_tasks(void)
851 return (nr_running() + nr_uninterruptible()) * FIXED_1;
855 * Hmm.. Changed this, as the GNU make sources (load.c) seems to
856 * imply that avenrun[] is the standard name for this kind of thing.
857 * Nothing else seems to be standardized: the fractional size etc
858 * all seem to differ on different machines.
860 * Requires xtime_lock to access.
862 unsigned long avenrun[3];
864 EXPORT_SYMBOL(avenrun);
867 * calc_load - given tick count, update the avenrun load estimates.
868 * This is called while holding a write_lock on xtime_lock.
870 static inline void calc_load(unsigned long ticks)
872 unsigned long active_tasks; /* fixed-point */
873 static int count = LOAD_FREQ;
878 active_tasks = count_active_tasks();
879 CALC_LOAD(avenrun[0], EXP_1, active_tasks);
880 CALC_LOAD(avenrun[1], EXP_5, active_tasks);
881 CALC_LOAD(avenrun[2], EXP_15, active_tasks);
885 /* jiffies at the most recent update of wall time */
886 unsigned long wall_jiffies = INITIAL_JIFFIES;
889 * This read-write spinlock protects us from races in SMP while
890 * playing with xtime and avenrun.
892 #ifndef ARCH_HAVE_XTIME_LOCK
893 seqlock_t xtime_lock __cacheline_aligned_in_smp = SEQLOCK_UNLOCKED;
895 EXPORT_SYMBOL(xtime_lock);
899 * This function runs timers and the timer-tq in bottom half context.
901 static void run_timer_softirq(struct softirq_action *h)
903 tvec_base_t *base = &__get_cpu_var(tvec_bases);
905 hrtimer_run_queues();
906 if (time_after_eq(jiffies, base->timer_jiffies))
911 * Called by the local, per-CPU timer interrupt on SMP.
913 void run_local_timers(void)
915 raise_softirq(TIMER_SOFTIRQ);
919 * Called by the timer interrupt. xtime_lock must already be taken
922 static inline void update_times(void)
926 ticks = jiffies - wall_jiffies;
928 wall_jiffies += ticks;
929 update_wall_time(ticks);
935 * The 64-bit jiffies value is not atomic - you MUST NOT read it
936 * without sampling the sequence number in xtime_lock.
937 * jiffies is defined in the linker script...
940 void do_timer(struct pt_regs *regs)
944 softlockup_tick(regs);
947 #ifdef __ARCH_WANT_SYS_ALARM
950 * For backwards compatibility? This can be done in libc so Alpha
951 * and all newer ports shouldn't need it.
953 asmlinkage unsigned long sys_alarm(unsigned int seconds)
955 struct itimerval it_new, it_old;
956 unsigned int oldalarm;
958 it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
959 it_new.it_value.tv_sec = seconds;
960 it_new.it_value.tv_usec = 0;
961 do_setitimer(ITIMER_REAL, &it_new, &it_old);
962 oldalarm = it_old.it_value.tv_sec;
963 /* ehhh.. We can't return 0 if we have an alarm pending.. */
964 /* And we'd better return too much than too little anyway */
965 if ((!oldalarm && it_old.it_value.tv_usec) || it_old.it_value.tv_usec >= 500000)
975 * The Alpha uses getxpid, getxuid, and getxgid instead. Maybe this
976 * should be moved into arch/i386 instead?
980 * sys_getpid - return the thread group id of the current process
982 * Note, despite the name, this returns the tgid not the pid. The tgid and
983 * the pid are identical unless CLONE_THREAD was specified on clone() in
984 * which case the tgid is the same in all threads of the same group.
986 * This is SMP safe as current->tgid does not change.
988 asmlinkage long sys_getpid(void)
990 return current->tgid;
994 * Accessing ->group_leader->real_parent is not SMP-safe, it could
995 * change from under us. However, rather than getting any lock
996 * we can use an optimistic algorithm: get the parent
997 * pid, and go back and check that the parent is still
998 * the same. If it has changed (which is extremely unlikely
999 * indeed), we just try again..
1001 * NOTE! This depends on the fact that even if we _do_
1002 * get an old value of "parent", we can happily dereference
1003 * the pointer (it was and remains a dereferencable kernel pointer
1004 * no matter what): we just can't necessarily trust the result
1005 * until we know that the parent pointer is valid.
1007 * NOTE2: ->group_leader never changes from under us.
1009 asmlinkage long sys_getppid(void)
1012 struct task_struct *me = current;
1013 struct task_struct *parent;
1015 parent = me->group_leader->real_parent;
1018 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
1020 struct task_struct *old = parent;
1023 * Make sure we read the pid before re-reading the
1027 parent = me->group_leader->real_parent;
1037 asmlinkage long sys_getuid(void)
1039 /* Only we change this so SMP safe */
1040 return current->uid;
1043 asmlinkage long sys_geteuid(void)
1045 /* Only we change this so SMP safe */
1046 return current->euid;
1049 asmlinkage long sys_getgid(void)
1051 /* Only we change this so SMP safe */
1052 return current->gid;
1055 asmlinkage long sys_getegid(void)
1057 /* Only we change this so SMP safe */
1058 return current->egid;
1063 static void process_timeout(unsigned long __data)
1065 wake_up_process((task_t *)__data);
1069 * schedule_timeout - sleep until timeout
1070 * @timeout: timeout value in jiffies
1072 * Make the current task sleep until @timeout jiffies have
1073 * elapsed. The routine will return immediately unless
1074 * the current task state has been set (see set_current_state()).
1076 * You can set the task state as follows -
1078 * %TASK_UNINTERRUPTIBLE - at least @timeout jiffies are guaranteed to
1079 * pass before the routine returns. The routine will return 0
1081 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
1082 * delivered to the current task. In this case the remaining time
1083 * in jiffies will be returned, or 0 if the timer expired in time
1085 * The current task state is guaranteed to be TASK_RUNNING when this
1088 * Specifying a @timeout value of %MAX_SCHEDULE_TIMEOUT will schedule
1089 * the CPU away without a bound on the timeout. In this case the return
1090 * value will be %MAX_SCHEDULE_TIMEOUT.
1092 * In all cases the return value is guaranteed to be non-negative.
1094 fastcall signed long __sched schedule_timeout(signed long timeout)
1096 struct timer_list timer;
1097 unsigned long expire;
1101 case MAX_SCHEDULE_TIMEOUT:
1103 * These two special cases are useful to be comfortable
1104 * in the caller. Nothing more. We could take
1105 * MAX_SCHEDULE_TIMEOUT from one of the negative value
1106 * but I' d like to return a valid offset (>=0) to allow
1107 * the caller to do everything it want with the retval.
1113 * Another bit of PARANOID. Note that the retval will be
1114 * 0 since no piece of kernel is supposed to do a check
1115 * for a negative retval of schedule_timeout() (since it
1116 * should never happens anyway). You just have the printk()
1117 * that will tell you if something is gone wrong and where.
1121 printk(KERN_ERR "schedule_timeout: wrong timeout "
1122 "value %lx from %p\n", timeout,
1123 __builtin_return_address(0));
1124 current->state = TASK_RUNNING;
1129 expire = timeout + jiffies;
1131 setup_timer(&timer, process_timeout, (unsigned long)current);
1132 __mod_timer(&timer, expire);
1134 del_singleshot_timer_sync(&timer);
1136 timeout = expire - jiffies;
1139 return timeout < 0 ? 0 : timeout;
1141 EXPORT_SYMBOL(schedule_timeout);
1144 * We can use __set_current_state() here because schedule_timeout() calls
1145 * schedule() unconditionally.
1147 signed long __sched schedule_timeout_interruptible(signed long timeout)
1149 __set_current_state(TASK_INTERRUPTIBLE);
1150 return schedule_timeout(timeout);
1152 EXPORT_SYMBOL(schedule_timeout_interruptible);
1154 signed long __sched schedule_timeout_uninterruptible(signed long timeout)
1156 __set_current_state(TASK_UNINTERRUPTIBLE);
1157 return schedule_timeout(timeout);
1159 EXPORT_SYMBOL(schedule_timeout_uninterruptible);
1161 /* Thread ID - the internal kernel "pid" */
1162 asmlinkage long sys_gettid(void)
1164 return current->pid;
1168 * sys_sysinfo - fill in sysinfo struct
1170 asmlinkage long sys_sysinfo(struct sysinfo __user *info)
1173 unsigned long mem_total, sav_total;
1174 unsigned int mem_unit, bitcount;
1177 memset((char *)&val, 0, sizeof(struct sysinfo));
1181 seq = read_seqbegin(&xtime_lock);
1184 * This is annoying. The below is the same thing
1185 * posix_get_clock_monotonic() does, but it wants to
1186 * take the lock which we want to cover the loads stuff
1190 getnstimeofday(&tp);
1191 tp.tv_sec += wall_to_monotonic.tv_sec;
1192 tp.tv_nsec += wall_to_monotonic.tv_nsec;
1193 if (tp.tv_nsec - NSEC_PER_SEC >= 0) {
1194 tp.tv_nsec = tp.tv_nsec - NSEC_PER_SEC;
1197 val.uptime = tp.tv_sec + (tp.tv_nsec ? 1 : 0);
1199 val.loads[0] = avenrun[0] << (SI_LOAD_SHIFT - FSHIFT);
1200 val.loads[1] = avenrun[1] << (SI_LOAD_SHIFT - FSHIFT);
1201 val.loads[2] = avenrun[2] << (SI_LOAD_SHIFT - FSHIFT);
1203 val.procs = nr_threads;
1204 } while (read_seqretry(&xtime_lock, seq));
1210 * If the sum of all the available memory (i.e. ram + swap)
1211 * is less than can be stored in a 32 bit unsigned long then
1212 * we can be binary compatible with 2.2.x kernels. If not,
1213 * well, in that case 2.2.x was broken anyways...
1215 * -Erik Andersen <andersee@debian.org>
1218 mem_total = val.totalram + val.totalswap;
1219 if (mem_total < val.totalram || mem_total < val.totalswap)
1222 mem_unit = val.mem_unit;
1223 while (mem_unit > 1) {
1226 sav_total = mem_total;
1228 if (mem_total < sav_total)
1233 * If mem_total did not overflow, multiply all memory values by
1234 * val.mem_unit and set it to 1. This leaves things compatible
1235 * with 2.2.x, and also retains compatibility with earlier 2.4.x
1240 val.totalram <<= bitcount;
1241 val.freeram <<= bitcount;
1242 val.sharedram <<= bitcount;
1243 val.bufferram <<= bitcount;
1244 val.totalswap <<= bitcount;
1245 val.freeswap <<= bitcount;
1246 val.totalhigh <<= bitcount;
1247 val.freehigh <<= bitcount;
1250 if (copy_to_user(info, &val, sizeof(struct sysinfo)))
1256 static void __devinit init_timers_cpu(int cpu)
1261 base = &per_cpu(tvec_bases, cpu);
1262 spin_lock_init(&base->t_base.lock);
1263 for (j = 0; j < TVN_SIZE; j++) {
1264 INIT_LIST_HEAD(base->tv5.vec + j);
1265 INIT_LIST_HEAD(base->tv4.vec + j);
1266 INIT_LIST_HEAD(base->tv3.vec + j);
1267 INIT_LIST_HEAD(base->tv2.vec + j);
1269 for (j = 0; j < TVR_SIZE; j++)
1270 INIT_LIST_HEAD(base->tv1.vec + j);
1272 base->timer_jiffies = jiffies;
1275 #ifdef CONFIG_HOTPLUG_CPU
1276 static void migrate_timer_list(tvec_base_t *new_base, struct list_head *head)
1278 struct timer_list *timer;
1280 while (!list_empty(head)) {
1281 timer = list_entry(head->next, struct timer_list, entry);
1282 detach_timer(timer, 0);
1283 timer->base = &new_base->t_base;
1284 internal_add_timer(new_base, timer);
1288 static void __devinit migrate_timers(int cpu)
1290 tvec_base_t *old_base;
1291 tvec_base_t *new_base;
1294 BUG_ON(cpu_online(cpu));
1295 old_base = &per_cpu(tvec_bases, cpu);
1296 new_base = &get_cpu_var(tvec_bases);
1298 local_irq_disable();
1299 spin_lock(&new_base->t_base.lock);
1300 spin_lock(&old_base->t_base.lock);
1302 if (old_base->t_base.running_timer)
1304 for (i = 0; i < TVR_SIZE; i++)
1305 migrate_timer_list(new_base, old_base->tv1.vec + i);
1306 for (i = 0; i < TVN_SIZE; i++) {
1307 migrate_timer_list(new_base, old_base->tv2.vec + i);
1308 migrate_timer_list(new_base, old_base->tv3.vec + i);
1309 migrate_timer_list(new_base, old_base->tv4.vec + i);
1310 migrate_timer_list(new_base, old_base->tv5.vec + i);
1313 spin_unlock(&old_base->t_base.lock);
1314 spin_unlock(&new_base->t_base.lock);
1316 put_cpu_var(tvec_bases);
1318 #endif /* CONFIG_HOTPLUG_CPU */
1320 static int __devinit timer_cpu_notify(struct notifier_block *self,
1321 unsigned long action, void *hcpu)
1323 long cpu = (long)hcpu;
1325 case CPU_UP_PREPARE:
1326 init_timers_cpu(cpu);
1328 #ifdef CONFIG_HOTPLUG_CPU
1330 migrate_timers(cpu);
1339 static struct notifier_block __devinitdata timers_nb = {
1340 .notifier_call = timer_cpu_notify,
1344 void __init init_timers(void)
1346 timer_cpu_notify(&timers_nb, (unsigned long)CPU_UP_PREPARE,
1347 (void *)(long)smp_processor_id());
1348 register_cpu_notifier(&timers_nb);
1349 open_softirq(TIMER_SOFTIRQ, run_timer_softirq, NULL);
1352 #ifdef CONFIG_TIME_INTERPOLATION
1354 struct time_interpolator *time_interpolator;
1355 static struct time_interpolator *time_interpolator_list;
1356 static DEFINE_SPINLOCK(time_interpolator_lock);
1358 static inline u64 time_interpolator_get_cycles(unsigned int src)
1360 unsigned long (*x)(void);
1364 case TIME_SOURCE_FUNCTION:
1365 x = time_interpolator->addr;
1368 case TIME_SOURCE_MMIO64 :
1369 return readq((void __iomem *) time_interpolator->addr);
1371 case TIME_SOURCE_MMIO32 :
1372 return readl((void __iomem *) time_interpolator->addr);
1374 default: return get_cycles();
1378 static inline u64 time_interpolator_get_counter(int writelock)
1380 unsigned int src = time_interpolator->source;
1382 if (time_interpolator->jitter)
1388 lcycle = time_interpolator->last_cycle;
1389 now = time_interpolator_get_cycles(src);
1390 if (lcycle && time_after(lcycle, now))
1393 /* When holding the xtime write lock, there's no need
1394 * to add the overhead of the cmpxchg. Readers are
1395 * force to retry until the write lock is released.
1398 time_interpolator->last_cycle = now;
1401 /* Keep track of the last timer value returned. The use of cmpxchg here
1402 * will cause contention in an SMP environment.
1404 } while (unlikely(cmpxchg(&time_interpolator->last_cycle, lcycle, now) != lcycle));
1408 return time_interpolator_get_cycles(src);
1411 void time_interpolator_reset(void)
1413 time_interpolator->offset = 0;
1414 time_interpolator->last_counter = time_interpolator_get_counter(1);
1417 #define GET_TI_NSECS(count,i) (((((count) - i->last_counter) & (i)->mask) * (i)->nsec_per_cyc) >> (i)->shift)
1419 unsigned long time_interpolator_get_offset(void)
1421 /* If we do not have a time interpolator set up then just return zero */
1422 if (!time_interpolator)
1425 return time_interpolator->offset +
1426 GET_TI_NSECS(time_interpolator_get_counter(0), time_interpolator);
1429 #define INTERPOLATOR_ADJUST 65536
1430 #define INTERPOLATOR_MAX_SKIP 10*INTERPOLATOR_ADJUST
1432 static void time_interpolator_update(long delta_nsec)
1435 unsigned long offset;
1437 /* If there is no time interpolator set up then do nothing */
1438 if (!time_interpolator)
1442 * The interpolator compensates for late ticks by accumulating the late
1443 * time in time_interpolator->offset. A tick earlier than expected will
1444 * lead to a reset of the offset and a corresponding jump of the clock
1445 * forward. Again this only works if the interpolator clock is running
1446 * slightly slower than the regular clock and the tuning logic insures
1450 counter = time_interpolator_get_counter(1);
1451 offset = time_interpolator->offset +
1452 GET_TI_NSECS(counter, time_interpolator);
1454 if (delta_nsec < 0 || (unsigned long) delta_nsec < offset)
1455 time_interpolator->offset = offset - delta_nsec;
1457 time_interpolator->skips++;
1458 time_interpolator->ns_skipped += delta_nsec - offset;
1459 time_interpolator->offset = 0;
1461 time_interpolator->last_counter = counter;
1463 /* Tuning logic for time interpolator invoked every minute or so.
1464 * Decrease interpolator clock speed if no skips occurred and an offset is carried.
1465 * Increase interpolator clock speed if we skip too much time.
1467 if (jiffies % INTERPOLATOR_ADJUST == 0)
1469 if (time_interpolator->skips == 0 && time_interpolator->offset > TICK_NSEC)
1470 time_interpolator->nsec_per_cyc--;
1471 if (time_interpolator->ns_skipped > INTERPOLATOR_MAX_SKIP && time_interpolator->offset == 0)
1472 time_interpolator->nsec_per_cyc++;
1473 time_interpolator->skips = 0;
1474 time_interpolator->ns_skipped = 0;
1479 is_better_time_interpolator(struct time_interpolator *new)
1481 if (!time_interpolator)
1483 return new->frequency > 2*time_interpolator->frequency ||
1484 (unsigned long)new->drift < (unsigned long)time_interpolator->drift;
1488 register_time_interpolator(struct time_interpolator *ti)
1490 unsigned long flags;
1493 if (ti->frequency == 0 || ti->mask == 0)
1496 ti->nsec_per_cyc = ((u64)NSEC_PER_SEC << ti->shift) / ti->frequency;
1497 spin_lock(&time_interpolator_lock);
1498 write_seqlock_irqsave(&xtime_lock, flags);
1499 if (is_better_time_interpolator(ti)) {
1500 time_interpolator = ti;
1501 time_interpolator_reset();
1503 write_sequnlock_irqrestore(&xtime_lock, flags);
1505 ti->next = time_interpolator_list;
1506 time_interpolator_list = ti;
1507 spin_unlock(&time_interpolator_lock);
1511 unregister_time_interpolator(struct time_interpolator *ti)
1513 struct time_interpolator *curr, **prev;
1514 unsigned long flags;
1516 spin_lock(&time_interpolator_lock);
1517 prev = &time_interpolator_list;
1518 for (curr = *prev; curr; curr = curr->next) {
1526 write_seqlock_irqsave(&xtime_lock, flags);
1527 if (ti == time_interpolator) {
1528 /* we lost the best time-interpolator: */
1529 time_interpolator = NULL;
1530 /* find the next-best interpolator */
1531 for (curr = time_interpolator_list; curr; curr = curr->next)
1532 if (is_better_time_interpolator(curr))
1533 time_interpolator = curr;
1534 time_interpolator_reset();
1536 write_sequnlock_irqrestore(&xtime_lock, flags);
1537 spin_unlock(&time_interpolator_lock);
1539 #endif /* CONFIG_TIME_INTERPOLATION */
1542 * msleep - sleep safely even with waitqueue interruptions
1543 * @msecs: Time in milliseconds to sleep for
1545 void msleep(unsigned int msecs)
1547 unsigned long timeout = msecs_to_jiffies(msecs) + 1;
1550 timeout = schedule_timeout_uninterruptible(timeout);
1553 EXPORT_SYMBOL(msleep);
1556 * msleep_interruptible - sleep waiting for signals
1557 * @msecs: Time in milliseconds to sleep for
1559 unsigned long msleep_interruptible(unsigned int msecs)
1561 unsigned long timeout = msecs_to_jiffies(msecs) + 1;
1563 while (timeout && !signal_pending(current))
1564 timeout = schedule_timeout_interruptible(timeout);
1565 return jiffies_to_msecs(timeout);
1568 EXPORT_SYMBOL(msleep_interruptible);