Commit 21927fc8 authored by Anna-Maria Behnsen's avatar Anna-Maria Behnsen Committed by Thomas Gleixner
Browse files

timers: Retrieve next expiry of pinned/non-pinned timers separately 



For the conversion of the NOHZ timer placement to a pull at expiry time
model it's required to have separate expiry times for the pinned and the
non-pinned (movable) timers. Therefore struct timer_events is introduced.

No functional change

Originally-by: default avatarRichard Cochran (linutronix GmbH) <richardcochran@gmail.com>
Signed-off-by: default avatarAnna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarFrederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20240221090548.36600-12-anna-maria@linutronix.de
parent 83a665dc

kernel/time/timer.c

+31 −4
Original line number Diff line number Diff line
@@ -266,6 +266,11 @@ struct timer_base { 


static DEFINE_PER_CPU(struct timer_base, timer_bases[NR_BASES]);



struct timer_events {

	u64	local;

	u64	global;

};



#ifdef CONFIG_NO_HZ_COMMON



static DEFINE_STATIC_KEY_FALSE(timers_nohz_active);
@@ -2031,10 +2036,11 @@ static unsigned long next_timer_interrupt(struct timer_base *base, 
static inline u64 __get_next_timer_interrupt(unsigned long basej, u64 basem,

					     bool *idle)

{

	struct timer_events tevt = { .local = KTIME_MAX, .global = KTIME_MAX };

	unsigned long nextevt, nextevt_local, nextevt_global;

	struct timer_base *base_local, *base_global;

	u64 expires = KTIME_MAX;

	bool local_first;

	u64 expires;



	/*

	 * Pretend that there is no timer pending if the cpu is offline.
@@ -2043,7 +2049,7 @@ static inline u64 __get_next_timer_interrupt(unsigned long basej, u64 basem, 
	if (cpu_is_offline(smp_processor_id())) {

		if (idle)

			*idle = true;

		return expires;

		return tevt.local;

	}



	base_local = this_cpu_ptr(&timer_bases[BASE_LOCAL]);
@@ -2059,13 +2065,32 @@ static inline u64 __get_next_timer_interrupt(unsigned long basej, u64 basem, 


	nextevt = local_first ? nextevt_local : nextevt_global;



	if (base_local->timers_pending || base_global->timers_pending) {

	/*

	 * If the @nextevt is at max. one tick away, use @nextevt and store

	 * it in the local expiry value. The next global event is irrelevant in

	 * this case and can be left as KTIME_MAX.

	 */

	if (time_before_eq(nextevt, basej + 1)) {

		/* If we missed a tick already, force 0 delta */

		if (time_before(nextevt, basej))

			nextevt = basej;

		expires = basem + (u64)(nextevt - basej) * TICK_NSEC;

		tevt.local = basem + (u64)(nextevt - basej) * TICK_NSEC;

		goto forward;

	}



	/*

	 * Update tevt.* values:

	 *

	 * If the local queue expires first, then the global event can be

	 * ignored. If the global queue is empty, nothing to do either.

	 */

	if (!local_first && base_global->timers_pending)

		tevt.global = basem + (u64)(nextevt_global - basej) * TICK_NSEC;



	if (base_local->timers_pending)

		tevt.local = basem + (u64)(nextevt_local - basej) * TICK_NSEC;



forward:

	/*

	 * We have a fresh next event. Check whether we can forward the

	 * base.
@@ -2096,6 +2121,8 @@ static inline u64 __get_next_timer_interrupt(unsigned long basej, u64 basem, 
	raw_spin_unlock(&base_global->lock);

	raw_spin_unlock(&base_local->lock);



	expires = min_t(u64, tevt.local, tevt.global);



	return cmp_next_hrtimer_event(basem, expires);

}