NOHZ

Linux 6.18.37 LTS: kernel/time/tick-sched.c
Linux 6.18.37 LTS: kernel/sched/core.c
Linux 6.18.37 LTS: kernel/rcu/tree_plugin.h

	 */
	timer_clear_idle();
}

/**
 * tick_nohz_idle_enter - prepare for entering idle on the current CPU
 *
 * Called when we start the idle loop.
 */
void tick_nohz_idle_enter(void)
{
	struct tick_sched *ts;

	lockdep_assert_irqs_enabled();

	local_irq_disable();

	ts = this_cpu_ptr(&tick_cpu_sched);

	WARN_ON_ONCE(ts->timer_expires_base);

	ts->inidle = 1;
	tick_nohz_start_idle(ts);

	local_irq_enable();
}

/**
 * tick_nohz_irq_exit - update next tick event from interrupt exit
 *
 * When an interrupt fires while we are idle and it doesn't cause
 * a reschedule, it may still add, modify or delete a timer, enqueue
 * an RCU callback, etc...
 * So we need to re-calculate and reprogram the next tick event.
 */
void tick_nohz_irq_exit(void)
{
	struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched);

	if (ts->inidle)

		ts->idle_sleeps++;
		ts->idle_expires = expires;

		if (!was_stopped && ts->tick_stopped) {
			ts->idle_jiffies = ts->last_jiffies;
			nohz_balance_enter_idle(cpu);
		}
	} else {
		tick_nohz_retain_tick(ts);
	}
}

void tick_nohz_idle_retain_tick(void)
{
	tick_nohz_retain_tick(this_cpu_ptr(&tick_cpu_sched));
	/*
	 * Undo the effect of get_next_timer_interrupt() called from
	 * tick_nohz_next_event().
	 */
	timer_clear_idle();
}

/**
 * tick_nohz_idle_enter - prepare for entering idle on the current CPU
 *
 * Called when we start the idle loop.
 */
void tick_nohz_idle_enter(void)
{
	struct tick_sched *ts;

	lockdep_assert_irqs_enabled();

	local_irq_disable();

	ts = this_cpu_ptr(&tick_cpu_sched);

	WARN_ON_ONCE(ts->timer_expires_base);

	ts->inidle = 1;