diff options
Diffstat (limited to 'kernel/timer.c')
| -rw-r--r-- | kernel/timer.c | 540 |
1 files changed, 71 insertions, 469 deletions
diff --git a/kernel/timer.c b/kernel/timer.c index b22bd39740d..1a69705c2fb 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -1,7 +1,7 @@ /* * linux/kernel/timer.c * - * Kernel internal timers, kernel timekeeping, basic process system calls + * Kernel internal timers, basic process system calls * * Copyright (C) 1991, 1992 Linus Torvalds * @@ -74,7 +74,7 @@ struct tvec_t_base_s { tvec_t tv3; tvec_t tv4; tvec_t tv5; -} ____cacheline_aligned_in_smp; +} ____cacheline_aligned; typedef struct tvec_t_base_s tvec_base_t; @@ -82,6 +82,37 @@ tvec_base_t boot_tvec_bases; EXPORT_SYMBOL(boot_tvec_bases); static DEFINE_PER_CPU(tvec_base_t *, tvec_bases) = &boot_tvec_bases; +/* + * Note that all tvec_bases is 2 byte aligned and lower bit of + * base in timer_list is guaranteed to be zero. Use the LSB for + * the new flag to indicate whether the timer is deferrable + */ +#define TBASE_DEFERRABLE_FLAG (0x1) + +/* Functions below help us manage 'deferrable' flag */ +static inline unsigned int tbase_get_deferrable(tvec_base_t *base) +{ + return ((unsigned int)(unsigned long)base & TBASE_DEFERRABLE_FLAG); +} + +static inline tvec_base_t *tbase_get_base(tvec_base_t *base) +{ + return ((tvec_base_t *)((unsigned long)base & ~TBASE_DEFERRABLE_FLAG)); +} + +static inline void timer_set_deferrable(struct timer_list *timer) +{ + timer->base = ((tvec_base_t *)((unsigned long)(timer->base) | + TBASE_DEFERRABLE_FLAG)); +} + +static inline void +timer_set_base(struct timer_list *timer, tvec_base_t *new_base) +{ + timer->base = (tvec_base_t *)((unsigned long)(new_base) | + tbase_get_deferrable(timer->base)); +} + /** * __round_jiffies - function to round jiffies to a full second * @j: the time in (absolute) jiffies that should be rounded @@ -295,6 +326,13 @@ void fastcall init_timer(struct timer_list *timer) } EXPORT_SYMBOL(init_timer); +void fastcall init_timer_deferrable(struct timer_list *timer) +{ + init_timer(timer); + timer_set_deferrable(timer); +} +EXPORT_SYMBOL(init_timer_deferrable); + static inline void detach_timer(struct timer_list *timer, int clear_pending) { @@ -325,10 +363,11 @@ static tvec_base_t *lock_timer_base(struct timer_list *timer, tvec_base_t *base; for (;;) { - base = timer->base; + tvec_base_t *prelock_base = timer->base; + base = tbase_get_base(prelock_base); if (likely(base != NULL)) { spin_lock_irqsave(&base->lock, *flags); - if (likely(base == timer->base)) + if (likely(prelock_base == timer->base)) return base; /* The timer has migrated to another CPU */ spin_unlock_irqrestore(&base->lock, *flags); @@ -365,11 +404,11 @@ int __mod_timer(struct timer_list *timer, unsigned long expires) */ if (likely(base->running_timer != timer)) { /* See the comment in lock_timer_base() */ - timer->base = NULL; + timer_set_base(timer, NULL); spin_unlock(&base->lock); base = new_base; spin_lock(&base->lock); - timer->base = base; + timer_set_base(timer, base); } } @@ -397,7 +436,7 @@ void add_timer_on(struct timer_list *timer, int cpu) timer_stats_timer_set_start_info(timer); BUG_ON(timer_pending(timer) || !timer->function); spin_lock_irqsave(&base->lock, flags); - timer->base = base; + timer_set_base(timer, base); internal_add_timer(base, timer); spin_unlock_irqrestore(&base->lock, flags); } @@ -550,7 +589,7 @@ static int cascade(tvec_base_t *base, tvec_t *tv, int index) * don't have to detach them individually. */ list_for_each_entry_safe(timer, tmp, &tv_list, entry) { - BUG_ON(timer->base != base); + BUG_ON(tbase_get_base(timer->base) != base); internal_add_timer(base, timer); } @@ -590,7 +629,7 @@ static inline void __run_timers(tvec_base_t *base) void (*fn)(unsigned long); unsigned long data; - timer = list_entry(head->next,struct timer_list,entry); + timer = list_first_entry(head, struct timer_list,entry); fn = timer->function; data = timer->data; @@ -627,7 +666,7 @@ static inline void __run_timers(tvec_base_t *base) static unsigned long __next_timer_interrupt(tvec_base_t *base) { unsigned long timer_jiffies = base->timer_jiffies; - unsigned long expires = timer_jiffies + (LONG_MAX >> 1); + unsigned long expires = timer_jiffies + NEXT_TIMER_MAX_DELTA; int index, slot, array, found = 0; struct timer_list *nte; tvec_t *varray[4]; @@ -636,6 +675,9 @@ static unsigned long __next_timer_interrupt(tvec_base_t *base) index = slot = timer_jiffies & TVR_MASK; do { list_for_each_entry(nte, base->tv1.vec + slot, entry) { + if (tbase_get_deferrable(nte->base)) + continue; + found = 1; expires = nte->expires; /* Look at the cascade bucket(s)? */ @@ -710,6 +752,14 @@ static unsigned long cmp_next_hrtimer_event(unsigned long now, tsdelta = ktime_to_timespec(hr_delta); delta = timespec_to_jiffies(&tsdelta); + + /* + * Limit the delta to the max value, which is checked in + * tick_nohz_stop_sched_tick(): + */ + if (delta > NEXT_TIMER_MAX_DELTA) + delta = NEXT_TIMER_MAX_DELTA; + /* * Take rounding errors in to account and make sure, that it * expires in the next tick. Otherwise we go into an endless @@ -752,455 +802,6 @@ unsigned long next_timer_interrupt(void) #endif -/******************************************************************/ - -/* - * The current time - * wall_to_monotonic is what we need to add to xtime (or xtime corrected - * for sub jiffie times) to get to monotonic time. Monotonic is pegged - * at zero at system boot time, so wall_to_monotonic will be negative, - * however, we will ALWAYS keep the tv_nsec part positive so we can use - * the usual normalization. - */ -struct timespec xtime __attribute__ ((aligned (16))); -struct timespec wall_to_monotonic __attribute__ ((aligned (16))); - -EXPORT_SYMBOL(xtime); - - -/* XXX - all of this timekeeping code should be later moved to time.c */ -#include <linux/clocksource.h> -static struct clocksource *clock; /* pointer to current clocksource */ - -#ifdef CONFIG_GENERIC_TIME -/** - * __get_nsec_offset - Returns nanoseconds since last call to periodic_hook - * - * private function, must hold xtime_lock lock when being - * called. Returns the number of nanoseconds since the - * last call to update_wall_time() (adjusted by NTP scaling) - */ -static inline s64 __get_nsec_offset(void) -{ - cycle_t cycle_now, cycle_delta; - s64 ns_offset; - - /* read clocksource: */ - cycle_now = clocksource_read(clock); - - /* calculate the delta since the last update_wall_time: */ - cycle_delta = (cycle_now - clock->cycle_last) & clock->mask; - - /* convert to nanoseconds: */ - ns_offset = cyc2ns(clock, cycle_delta); - - return ns_offset; -} - -/** - * __get_realtime_clock_ts - Returns the time of day in a timespec - * @ts: pointer to the timespec to be set - * - * Returns the time of day in a timespec. Used by - * do_gettimeofday() and get_realtime_clock_ts(). - */ -static inline void __get_realtime_clock_ts(struct timespec *ts) -{ - unsigned long seq; - s64 nsecs; - - do { - seq = read_seqbegin(&xtime_lock); - - *ts = xtime; - nsecs = __get_nsec_offset(); - - } while (read_seqretry(&xtime_lock, seq)); - - timespec_add_ns(ts, nsecs); -} - -/** - * getnstimeofday - Returns the time of day in a timespec - * @ts: pointer to the timespec to be set - * - * Returns the time of day in a timespec. - */ -void getnstimeofday(struct timespec *ts) -{ - __get_realtime_clock_ts(ts); -} - -EXPORT_SYMBOL(getnstimeofday); - -/** - * do_gettimeofday - Returns the time of day in a timeval - * @tv: pointer to the timeval to be set - * - * NOTE: Users should be converted to using get_realtime_clock_ts() - */ -void do_gettimeofday(struct timeval *tv) -{ - struct timespec now; - - __get_realtime_clock_ts(&now); - tv->tv_sec = now.tv_sec; - tv->tv_usec = now.tv_nsec/1000; -} - -EXPORT_SYMBOL(do_gettimeofday); -/** - * do_settimeofday - Sets the time of day - * @tv: pointer to the timespec variable containing the new time - * - * Sets the time of day to the new time and update NTP and notify hrtimers - */ -int do_settimeofday(struct timespec *tv) -{ - unsigned long flags; - time_t wtm_sec, sec = tv->tv_sec; - long wtm_nsec, nsec = tv->tv_nsec; - - if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC) - return -EINVAL; - - write_seqlock_irqsave(&xtime_lock, flags); - - nsec -= __get_nsec_offset(); - - wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec); - wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec); - - set_normalized_timespec(&xtime, sec, nsec); - set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec); - - clock->error = 0; - ntp_clear(); - - update_vsyscall(&xtime, clock); - - write_sequnlock_irqrestore(&xtime_lock, flags); - - /* signal hrtimers about time change */ - clock_was_set(); - - return 0; -} - -EXPORT_SYMBOL(do_settimeofday); - -/** - * change_clocksource - Swaps clocksources if a new one is available - * - * Accumulates current time interval and initializes new clocksource - */ -static void change_clocksource(void) -{ - struct clocksource *new; - cycle_t now; - u64 nsec; - - new = clocksource_get_next(); - - if (clock == new) - return; - - now = clocksource_read(new); - nsec = __get_nsec_offset(); - timespec_add_ns(&xtime, nsec); - - clock = new; - clock->cycle_last = now; - - clock->error = 0; - clock->xtime_nsec = 0; - clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH); - - tick_clock_notify(); - - printk(KERN_INFO "Time: %s clocksource has been installed.\n", - clock->name); -} -#else -static inline void change_clocksource(void) { } -#endif - -/** - * timekeeping_is_continuous - check to see if timekeeping is free running - */ -int timekeeping_is_continuous(void) -{ - unsigned long seq; - int ret; - - do { - seq = read_seqbegin(&xtime_lock); - - ret = clock->flags & CLOCK_SOURCE_VALID_FOR_HRES; - - } while (read_seqretry(&xtime_lock, seq)); - - return ret; -} - -/** - * read_persistent_clock - Return time in seconds from the persistent clock. - * - * Weak dummy function for arches that do not yet support it. - * Returns seconds from epoch using the battery backed persistent clock. - * Returns zero if unsupported. - * - * XXX - Do be sure to remove it once all arches implement it. - */ -unsigned long __attribute__((weak)) read_persistent_clock(void) -{ - return 0; -} - -/* - * timekeeping_init - Initializes the clocksource and common timekeeping values - */ -void __init timekeeping_init(void) -{ - unsigned long flags; - unsigned long sec = read_persistent_clock(); - - write_seqlock_irqsave(&xtime_lock, flags); - - ntp_clear(); - - clock = clocksource_get_next(); - clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH); - clock->cycle_last = clocksource_read(clock); - - xtime.tv_sec = sec; - xtime.tv_nsec = 0; - set_normalized_timespec(&wall_to_monotonic, - -xtime.tv_sec, -xtime.tv_nsec); - - write_sequnlock_irqrestore(&xtime_lock, flags); -} - -/* flag for if timekeeping is suspended */ -static int timekeeping_suspended; -/* time in seconds when suspend began */ -static unsigned long timekeeping_suspend_time; - -/** - * timekeeping_resume - Resumes the generic timekeeping subsystem. - * @dev: unused - * - * This is for the generic clocksource timekeeping. - * xtime/wall_to_monotonic/jiffies/etc are - * still managed by arch specific suspend/resume code. - */ -static int timekeeping_resume(struct sys_device *dev) -{ - unsigned long flags; - unsigned long now = read_persistent_clock(); - - write_seqlock_irqsave(&xtime_lock, flags); - - if (now && (now > timekeeping_suspend_time)) { - unsigned long sleep_length = now - timekeeping_suspend_time; - - xtime.tv_sec += sleep_length; - wall_to_monotonic.tv_sec -= sleep_length; - } - /* re-base the last cycle value */ - clock->cycle_last = clocksource_read(clock); - clock->error = 0; - timekeeping_suspended = 0; - write_sequnlock_irqrestore(&xtime_lock, flags); - - touch_softlockup_watchdog(); - - clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL); - - /* Resume hrtimers */ - hres_timers_resume(); - - return 0; -} - -static int timekeeping_suspend(struct sys_device *dev, pm_message_t state) -{ - unsigned long flags; - - write_seqlock_irqsave(&xtime_lock, flags); - timekeeping_suspended = 1; - timekeeping_suspend_time = read_persistent_clock(); - write_sequnlock_irqrestore(&xtime_lock, flags); - - clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL); - - return 0; -} - -/* sysfs resume/suspend bits for timekeeping */ -static struct sysdev_class timekeeping_sysclass = { - .resume = timekeeping_resume, - .suspend = timekeeping_suspend, - set_kset_name("timekeeping"), -}; - -static struct sys_device device_timer = { - .id = 0, - .cls = &timekeeping_sysclass, -}; - -static int __init timekeeping_init_device(void) -{ - int error = sysdev_class_register(&timekeeping_sysclass); - if (!error) - error = sysdev_register(&device_timer); - return error; -} - -device_initcall(timekeeping_init_device); - -/* - * If the error is already larger, we look ahead even further - * to compensate for late or lost adjustments. - */ -static __always_inline int clocksource_bigadjust(s64 error, s64 *interval, - s64 *offset) -{ - s64 tick_error, i; - u32 look_ahead, adj; - s32 error2, mult; - - /* - * Use the current error value to determine how much to look ahead. - * The larger the error the slower we adjust for it to avoid problems - * with losing too many ticks, otherwise we would overadjust and - * produce an even larger error. The smaller the adjustment the - * faster we try to adjust for it, as lost ticks can do less harm - * here. This is tuned so that an error of about 1 msec is adusted - * within about 1 sec (or 2^20 nsec in 2^SHIFT_HZ ticks). - */ - error2 = clock->error >> (TICK_LENGTH_SHIFT + 22 - 2 * SHIFT_HZ); - error2 = abs(error2); - for (look_ahead = 0; error2 > 0; look_ahead++) - error2 >>= 2; - - /* - * Now calculate the error in (1 << look_ahead) ticks, but first - * remove the single look ahead already included in the error. - */ - tick_error = current_tick_length() >> - (TICK_LENGTH_SHIFT - clock->shift + 1); - tick_error -= clock->xtime_interval >> 1; - error = ((error - tick_error) >> look_ahead) + tick_error; - - /* Finally calculate the adjustment shift value. */ - i = *interval; - mult = 1; - if (error < 0) { - error = -error; - *interval = -*interval; - *offset = -*offset; - mult = -1; - } - for (adj = 0; error > i; adj++) - error >>= 1; - - *interval <<= adj; - *offset <<= adj; - return mult << adj; -} - -/* - * Adjust the multiplier to reduce the error value, - * this is optimized for the most common adjustments of -1,0,1, - * for other values we can do a bit more work. - */ -static void clocksource_adjust(struct clocksource *clock, s64 offset) -{ - s64 error, interval = clock->cycle_interval; - int adj; - - error = clock->error >> (TICK_LENGTH_SHIFT - clock->shift - 1); - if (error > interval) { - error >>= 2; - if (likely(error <= interval)) - adj = 1; - else - adj = clocksource_bigadjust(error, &interval, &offset); - } else if (error < -interval) { - error >>= 2; - if (likely(error >= -interval)) { - adj = -1; - interval = -interval; - offset = -offset; - } else - adj = clocksource_bigadjust(error, &interval, &offset); - } else - return; - - clock->mult += adj; - clock->xtime_interval += interval; - clock->xtime_nsec -= offset; - clock->error -= (interval - offset) << - (TICK_LENGTH_SHIFT - clock->shift); -} - -/** - * update_wall_time - Uses the current clocksource to increment the wall time - * - * Called from the timer interrupt, must hold a write on xtime_lock. - */ -static void update_wall_time(void) -{ - cycle_t offset; - - /* Make sure we're fully resumed: */ - if (unlikely(timekeeping_suspended)) - return; - -#ifdef CONFIG_GENERIC_TIME - offset = (clocksource_read(clock) - clock->cycle_last) & clock->mask; -#else - offset = clock->cycle_interval; -#endif - clock->xtime_nsec += (s64)xtime.tv_nsec << clock->shift; - - /* normally this loop will run just once, however in the - * case of lost or late ticks, it will accumulate correctly. - */ - while (offset >= clock->cycle_interval) { - /* accumulate one interval */ - clock->xtime_nsec += clock->xtime_interval; - clock->cycle_last += clock->cycle_interval; - offset -= clock->cycle_interval; - - if (clock->xtime_nsec >= (u64)NSEC_PER_SEC << clock->shift) { - clock->xtime_nsec -= (u64)NSEC_PER_SEC << clock->shift; - xtime.tv_sec++; - second_overflow(); - } - - /* interpolator bits */ - time_interpolator_update(clock->xtime_interval - >> clock->shift); - - /* accumulate error between NTP and clock interval */ - clock->error += current_tick_length(); - clock->error -= clock->xtime_interval << (TICK_LENGTH_SHIFT - clock->shift); - } - - /* correct the clock when NTP error is too big */ - clocksource_adjust(clock, offset); - - /* store full nanoseconds into xtime */ - xtime.tv_nsec = (s64)clock->xtime_nsec >> clock->shift; - clock->xtime_nsec -= (s64)xtime.tv_nsec << clock->shift; - - /* check to see if there is a new clocksource to use */ - change_clocksource(); - update_vsyscall(&xtime, clock); -} - /* * Called from the timer interrupt handler to charge one tick to the current * process. user_tick is 1 if the tick is user time, 0 for system. @@ -1264,14 +865,6 @@ static inline void calc_load(unsigned long ticks) } /* - * This read-write spinlock protects us from races in SMP while - * playing with xtime and avenrun. - */ -__attribute__((weak)) __cacheline_aligned_in_smp DEFINE_SEQLOCK(xtime_lock); - -EXPORT_SYMBOL(xtime_lock); - -/* * This function runs timers and the timer-tq in bottom half context. */ static void run_timer_softirq(struct softirq_action *h) @@ -1617,6 +1210,13 @@ static int __devinit init_timers_cpu(int cpu) cpu_to_node(cpu)); if (!base) return -ENOMEM; + + /* Make sure that tvec_base is 2 byte aligned */ + if (tbase_get_deferrable(base)) { + WARN_ON(1); + kfree(base); + return -ENOMEM; + } memset(base, 0, sizeof(*base)); per_cpu(tvec_bases, cpu) = base; } else { @@ -1656,9 +1256,9 @@ static void migrate_timer_list(tvec_base_t *new_base, struct list_head *head) struct timer_list *timer; while (!list_empty(head)) { - timer = list_entry(head->next, struct timer_list, entry); + timer = list_first_entry(head, struct timer_list, entry); detach_timer(timer, 0); - timer->base = new_base; + timer_set_base(timer, new_base); internal_add_timer(new_base, timer); } } @@ -1701,11 +1301,13 @@ static int __cpuinit timer_cpu_notify(struct notifier_block *self, long cpu = (long)hcpu; switch(action) { case CPU_UP_PREPARE: + case CPU_UP_PREPARE_FROZEN: if (init_timers_cpu(cpu) < 0) return NOTIFY_BAD; break; #ifdef CONFIG_HOTPLUG_CPU case CPU_DEAD: + case CPU_DEAD_FROZEN: migrate_timers(cpu); break; #endif |