4c36a5dec2
Introduce a round_jiffies() function as well as a round_jiffies_relative() function. These functions round a jiffies value to the next whole second. The primary purpose of this rounding is to cause all "we don't care exactly when" timers to happen at the same jiffy. This avoids multiple timers firing within the second for no real reason; with dynamic ticks these extra timers cause wakeups from deep sleep CPU sleep states and thus waste power. The exact wakeup moment is skewed by the cpu number, to avoid all cpus from waking up at the exact same time (and hitting the same lock/cachelines there) [akpm@osdl.org: fix variable type] Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
107 lines
2.8 KiB
C
107 lines
2.8 KiB
C
#ifndef _LINUX_TIMER_H
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#define _LINUX_TIMER_H
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#include <linux/list.h>
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#include <linux/spinlock.h>
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#include <linux/stddef.h>
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struct tvec_t_base_s;
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struct timer_list {
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struct list_head entry;
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unsigned long expires;
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void (*function)(unsigned long);
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unsigned long data;
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struct tvec_t_base_s *base;
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};
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extern struct tvec_t_base_s boot_tvec_bases;
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#define TIMER_INITIALIZER(_function, _expires, _data) { \
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.function = (_function), \
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.expires = (_expires), \
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.data = (_data), \
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.base = &boot_tvec_bases, \
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}
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#define DEFINE_TIMER(_name, _function, _expires, _data) \
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struct timer_list _name = \
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TIMER_INITIALIZER(_function, _expires, _data)
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void fastcall init_timer(struct timer_list * timer);
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static inline void setup_timer(struct timer_list * timer,
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void (*function)(unsigned long),
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unsigned long data)
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{
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timer->function = function;
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timer->data = data;
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init_timer(timer);
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}
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/***
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* timer_pending - is a timer pending?
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* @timer: the timer in question
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*
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* timer_pending will tell whether a given timer is currently pending,
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* or not. Callers must ensure serialization wrt. other operations done
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* to this timer, eg. interrupt contexts, or other CPUs on SMP.
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*
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* return value: 1 if the timer is pending, 0 if not.
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*/
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static inline int timer_pending(const struct timer_list * timer)
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{
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return timer->entry.next != NULL;
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}
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extern void add_timer_on(struct timer_list *timer, int cpu);
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extern int del_timer(struct timer_list * timer);
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extern int __mod_timer(struct timer_list *timer, unsigned long expires);
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extern int mod_timer(struct timer_list *timer, unsigned long expires);
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extern unsigned long next_timer_interrupt(void);
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/***
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* add_timer - start a timer
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* @timer: the timer to be added
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*
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* The kernel will do a ->function(->data) callback from the
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* timer interrupt at the ->expires point in the future. The
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* current time is 'jiffies'.
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*
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* The timer's ->expires, ->function (and if the handler uses it, ->data)
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* fields must be set prior calling this function.
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*
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* Timers with an ->expires field in the past will be executed in the next
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* timer tick.
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*/
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static inline void add_timer(struct timer_list *timer)
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{
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BUG_ON(timer_pending(timer));
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__mod_timer(timer, timer->expires);
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}
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#ifdef CONFIG_SMP
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extern int try_to_del_timer_sync(struct timer_list *timer);
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extern int del_timer_sync(struct timer_list *timer);
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#else
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# define try_to_del_timer_sync(t) del_timer(t)
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# define del_timer_sync(t) del_timer(t)
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#endif
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#define del_singleshot_timer_sync(t) del_timer_sync(t)
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extern void init_timers(void);
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extern void run_local_timers(void);
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struct hrtimer;
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extern int it_real_fn(struct hrtimer *);
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unsigned long __round_jiffies(unsigned long j, int cpu);
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unsigned long __round_jiffies_relative(unsigned long j, int cpu);
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unsigned long round_jiffies(unsigned long j);
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unsigned long round_jiffies_relative(unsigned long j);
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#endif
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