Commit 73129cf4 authored by Anna-Maria Behnsen's avatar Anna-Maria Behnsen Committed by Thomas Gleixner
Browse files

timers: Optimization for timer_base_try_to_set_idle() 



When tick is stopped also the timer base is_idle flag is set. When
reentering timer_base_try_to_set_idle() with the tick stopped, there is no
need to check whether the timer base needs to be set idle again. When a
timer was enqueued in the meantime, this is already handled by the
tick_nohz_next_event() call which was executed before
tick_nohz_stop_tick().

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/20240221090548.36600-5-anna-maria@linutronix.de
parent e2e1d724

kernel/time/tick-sched.c

+1 −1
Original line number Diff line number Diff line
@@ -896,7 +896,7 @@ static void tick_nohz_stop_tick(struct tick_sched *ts, int cpu) 
	struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev);

	unsigned long basejiff = ts->last_jiffies;

	u64 basemono = ts->timer_expires_base;

	bool timer_idle;

	bool timer_idle = ts->tick_stopped;

	u64 expires;



	/* Make sure we won't be trying to stop it twice in a row. */

kernel/time/timer.c

+8 −3
Original line number Diff line number Diff line
@@ -2044,13 +2044,18 @@ u64 get_next_timer_interrupt(unsigned long basej, u64 basem) 
 * timer_base_try_to_set_idle() - Try to set the idle state of the timer bases

 * @basej:	base time jiffies

 * @basem:	base time clock monotonic

 * @idle:	pointer to store the value of timer_base->is_idle

 * @idle:	pointer to store the value of timer_base->is_idle on return;

 *		*idle contains the information whether tick was already stopped

 *

 * Returns the tick aligned clock monotonic time of the next pending

 * timer or KTIME_MAX if no timer is pending.

 * Returns the tick aligned clock monotonic time of the next pending timer or

 * KTIME_MAX if no timer is pending. When tick was already stopped KTIME_MAX is

 * returned as well.

 */

u64 timer_base_try_to_set_idle(unsigned long basej, u64 basem, bool *idle)

{

	if (*idle)

		return KTIME_MAX;



	return __get_next_timer_interrupt(basej, basem, idle);

}