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timers: Optimization for timer_base_try_to_set_idle()

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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: 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/20240221090548.36600-5-anna-maria@linutronix.de
This commit is contained in:
Anna-Maria Behnsen 2024-02-21 10:05:32 +01:00 committed by Thomas Gleixner
parent e2e1d724e9
commit 73129cf4b6
2 changed files with 9 additions and 4 deletions
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2
kernel/time/tick-sched.c
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@ -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. */

11
kernel/time/timer.c
View File

@ -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);
}