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[PATCH] Extend next_timer_interrupt() to use a reference jiffie

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For CONFIG_NO_HZ we need to calculate the next timer wheel event based on a
given jiffie value.  Extend the existing code to allow the extra 'now'
argument.  Provide a compability function for the existing implementations to
call the function with now == jiffies.  (This also solves the racyness of the
original code vs.  jiffies changing during the iteration.)

No functional changes to existing users of this infrastructure.

[ remove WARN_ON() that triggered on s390, by Carsten Otte <cotte@de.ibm.com> ]
[ made new helper static, Adrian Bunk <bunk@stusta.de> ]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Thomas Gleixner 2007-02-16 01:27:47 -08:00 committed by Linus Torvalds
parent 1cfd68496e
commit fd064b9b77
3 changed files with 22 additions and 4 deletions
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10
include/linux/timer.h
View file

@ -61,7 +61,17 @@ extern int del_timer(struct timer_list * timer);
extern int __mod_timer(struct timer_list *timer, unsigned long expires);
extern int mod_timer(struct timer_list *timer, unsigned long expires);
/*
* Return when the next timer-wheel timeout occurs (in absolute jiffies),
* locks the timer base:
*/
extern unsigned long next_timer_interrupt(void);
/*
* Return when the next timer-wheel timeout occurs (in absolute jiffies),
* locks the timer base and does the comparison against the given
* jiffie.
*/
extern unsigned long get_next_timer_interrupt(unsigned long now);
/**
* add_timer - start a timer

2
kernel/hrtimer.c
View file

@ -533,7 +533,7 @@ ktime_t hrtimer_get_remaining(const struct hrtimer *timer)
}
EXPORT_SYMBOL_GPL(hrtimer_get_remaining);
#ifdef CONFIG_NO_IDLE_HZ
#if defined(CONFIG_NO_IDLE_HZ) || defined(CONFIG_NO_HZ)
/**
* hrtimer_get_next_event - get the time until next expiry event
*

14
kernel/timer.c
View file

@ -591,7 +591,7 @@ static inline void __run_timers(tvec_base_t *base)
spin_unlock_irq(&base->lock);
}
#ifdef CONFIG_NO_IDLE_HZ
#if defined(CONFIG_NO_IDLE_HZ) || defined(CONFIG_NO_HZ)
/*
* Find out when the next timer event is due to happen. This
* is used on S/390 to stop all activity when a cpus is idle.
@ -687,10 +687,10 @@ static unsigned long cmp_next_hrtimer_event(unsigned long now,
/**
* next_timer_interrupt - return the jiffy of the next pending timer
*/
unsigned long next_timer_interrupt(void)
unsigned long get_next_timer_interrupt(unsigned long now)
{
tvec_base_t *base = __get_cpu_var(tvec_bases);
unsigned long expires, now = jiffies;
unsigned long expires;
spin_lock(&base->lock);
expires = __next_timer_interrupt(base);
@ -701,6 +701,14 @@ unsigned long next_timer_interrupt(void)
return cmp_next_hrtimer_event(now, expires);
}
#ifdef CONFIG_NO_IDLE_HZ
unsigned long next_timer_interrupt(void)
{
return get_next_timer_interrupt(jiffies);
}
#endif
#endif
/******************************************************************/