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

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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: 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/20240221090548.36600-12-anna-maria@linutronix.de
This commit is contained in:
Anna-Maria Behnsen 2024-02-21 10:05:39 +01:00 committed by Thomas Gleixner
parent 83a665dc99
commit 21927fc89e
1 changed files with 31 additions and 4 deletions
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35
kernel/time/timer.c
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@ -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);
}