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tick/sched: Split out jiffies update helper function

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The logic to get the time of the last jiffies update will be needed by
the timer pull model as well.

Move the code into a global function in anticipation of the new caller.

No functional change.

Signed-off-by: Richard Cochran (linutronix GmbH) <richardcochran@gmail.com>
Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20240221090548.36600-17-anna-maria@linutronix.de
This commit is contained in:
Richard Cochran (linutronix GmbH) 2024-02-21 10:05:44 +01:00 committed by Thomas Gleixner
parent 89f01e10c9
commit 4c532939aa
2 changed files with 20 additions and 7 deletions
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1
kernel/time/tick-internal.h
View File

@ -157,6 +157,7 @@ static inline void tick_nohz_init(void) { }
#ifdef CONFIG_NO_HZ_COMMON
extern unsigned long tick_nohz_active;
extern void timers_update_nohz(void);
extern u64 get_jiffies_update(unsigned long *basej);
# ifdef CONFIG_SMP
extern struct static_key_false timers_migration_enabled;
extern void fetch_next_timer_interrupt_remote(unsigned long basej, u64 basem,

26
kernel/time/tick-sched.c
View File

@ -799,6 +799,24 @@ static inline bool local_timer_softirq_pending(void)
return local_softirq_pending() & BIT(TIMER_SOFTIRQ);
}
/*
* Read jiffies and the time when jiffies were updated last
*/
u64 get_jiffies_update(unsigned long *basej)
{
unsigned long basejiff;
unsigned int seq;
u64 basemono;
do {
seq = read_seqcount_begin(&jiffies_seq);
basemono = last_jiffies_update;
basejiff = jiffies;
} while (read_seqcount_retry(&jiffies_seq, seq));
*basej = basejiff;
return basemono;
}
/**
* tick_nohz_next_event() - return the clock monotonic based next event
* @ts: pointer to tick_sched struct
@ -813,14 +831,8 @@ static ktime_t tick_nohz_next_event(struct tick_sched *ts, int cpu)
{
u64 basemono, next_tick, delta, expires;
unsigned long basejiff;
unsigned int seq;
/* Read jiffies and the time when jiffies were updated last */
do {
seq = read_seqcount_begin(&jiffies_seq);
basemono = last_jiffies_update;
basejiff = jiffies;
} while (read_seqcount_retry(&jiffies_seq, seq));
basemono = get_jiffies_update(&basejiff);
ts->last_jiffies = basejiff;
ts->timer_expires_base = basemono;