[linux.git] / kernel / sched_idletask.c

/*
 * idle-task scheduling class.
 *
 * (NOTE: these are not related to SCHED_IDLE tasks which are
 *  handled in sched_fair.c)
 */

#ifdef CONFIG_SMP
static int select_task_rq_idle(struct task_struct *p, int sync)
{
	return task_cpu(p); /* IDLE tasks as never migrated */
}
#endif /* CONFIG_SMP */
/*
 * Idle tasks are unconditionally rescheduled:
 */
static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p, int sync)
{
	resched_task(rq->idle);
}

static struct task_struct *pick_next_task_idle(struct rq *rq)
{
	schedstat_inc(rq, sched_goidle);
	/* adjust the active tasks as we might go into a long sleep */
	calc_load_account_active(rq);
	return rq->idle;
}

/*
 * It is not legal to sleep in the idle task - print a warning
 * message if some code attempts to do it:
 */
static void
dequeue_task_idle(struct rq *rq, struct task_struct *p, int sleep)
{
	spin_unlock_irq(&rq->lock);
	printk(KERN_ERR "bad: scheduling from the idle thread!\n");
	dump_stack();
	spin_lock_irq(&rq->lock);
}

static void put_prev_task_idle(struct rq *rq, struct task_struct *prev)
{
}

#ifdef CONFIG_SMP
static unsigned long
load_balance_idle(struct rq *this_rq, int this_cpu, struct rq *busiest,
		  unsigned long max_load_move,
		  struct sched_domain *sd, enum cpu_idle_type idle,
		  int *all_pinned, int *this_best_prio)
{
	return 0;
}

static int
move_one_task_idle(struct rq *this_rq, int this_cpu, struct rq *busiest,
		   struct sched_domain *sd, enum cpu_idle_type idle)
{
	return 0;
}
#endif

static void task_tick_idle(struct rq *rq, struct task_struct *curr, int queued)
{
}

static void set_curr_task_idle(struct rq *rq)
{
}

static void switched_to_idle(struct rq *rq, struct task_struct *p,
			     int running)
{
	/* Can this actually happen?? */
	if (running)
		resched_task(rq->curr);
	else
		check_preempt_curr(rq, p, 0);
}

static void prio_changed_idle(struct rq *rq, struct task_struct *p,
			      int oldprio, int running)
{
	/* This can happen for hot plug CPUS */

	/*
	 * Reschedule if we are currently running on this runqueue and
	 * our priority decreased, or if we are not currently running on
	 * this runqueue and our priority is higher than the current's
	 */
	if (running) {
		if (p->prio > oldprio)
			resched_task(rq->curr);
	} else
		check_preempt_curr(rq, p, 0);
}

/*
 * Simple, special scheduling class for the per-CPU idle tasks:
 */
static const struct sched_class idle_sched_class = {
	/* .next is NULL */
	/* no enqueue/yield_task for idle tasks */

	/* dequeue is not valid, we print a debug message there: */
	.dequeue_task		= dequeue_task_idle,

	.check_preempt_curr	= check_preempt_curr_idle,

	.pick_next_task		= pick_next_task_idle,
	.put_prev_task		= put_prev_task_idle,

#ifdef CONFIG_SMP
	.select_task_rq		= select_task_rq_idle,

	.load_balance		= load_balance_idle,
	.move_one_task		= move_one_task_idle,
#endif

	.set_curr_task          = set_curr_task_idle,
	.task_tick		= task_tick_idle,

	.prio_changed		= prio_changed_idle,
	.switched_to		= switched_to_idle,

	/* no .task_new for idle tasks */
};
Commit	Line	Data
fa72e9e4 IM	1	/*
	2	* idle-task scheduling class.
	3	*
	4	* (NOTE: these are not related to SCHED_IDLE tasks which are
	5	* handled in sched_fair.c)
	6	*/
	7
e7693a36 GH	8	#ifdef CONFIG_SMP
	9	static int select_task_rq_idle(struct task_struct *p, int sync)
	10	{
	11	return task_cpu(p); /* IDLE tasks as never migrated */
	12	}
	13	#endif /* CONFIG_SMP */
fa72e9e4 IM	14	/*
	15	* Idle tasks are unconditionally rescheduled:
	16	*/
15afe09b	17	static void check_preempt_curr_idle(struct rq rq, struct task_struct p, int sync)
fa72e9e4 IM	18	{
	19	resched_task(rq->idle);
	20	}
	21
fb8d4724	22	static struct task_struct pick_next_task_idle(struct rq rq)
fa72e9e4 IM	23	{
fa72e9e4 IM	24	schedstat_inc(rq, sched_goidle);
dce48a84 TG	25	/* adjust the active tasks as we might go into a long sleep */
dce48a84 TG	26	calc_load_account_active(rq);
fa72e9e4 IM	27	return rq->idle;
	28	}
	29
	30	/*
	31	* It is not legal to sleep in the idle task - print a warning
	32	* message if some code attempts to do it:
	33	*/
	34	static void
f02231e5	35	dequeue_task_idle(struct rq rq, struct task_struct p, int sleep)
fa72e9e4 IM	36	{
	37	spin_unlock_irq(&rq->lock);
	38	printk(KERN_ERR "bad: scheduling from the idle thread!\n");
	39	dump_stack();
	40	spin_lock_irq(&rq->lock);
	41	}
	42
31ee529c	43	static void put_prev_task_idle(struct rq rq, struct task_struct prev)
fa72e9e4 IM	44	{
	45	}
	46
681f3e68	47	#ifdef CONFIG_SMP
43010659	48	static unsigned long
fa72e9e4	49	load_balance_idle(struct rq this_rq, int this_cpu, struct rq busiest,
e1d1484f PW	50	unsigned long max_load_move,
	51	struct sched_domain *sd, enum cpu_idle_type idle,
	52	int all_pinned, int this_best_prio)
	53	{
	54	return 0;
	55	}
	56
	57	static int
	58	move_one_task_idle(struct rq this_rq, int this_cpu, struct rq busiest,
	59	struct sched_domain *sd, enum cpu_idle_type idle)
fa72e9e4 IM	60	{
	61	return 0;
	62	}
681f3e68	63	#endif
fa72e9e4	64
8f4d37ec	65	static void task_tick_idle(struct rq rq, struct task_struct curr, int queued)
fa72e9e4 IM	66	{
	67	}
	68
83b699ed SV	69	static void set_curr_task_idle(struct rq *rq)
	70	{
	71	}
	72
cb469845 SR	73	static void switched_to_idle(struct rq rq, struct task_struct p,
	74	int running)
	75	{
	76	/* Can this actually happen?? */
	77	if (running)
	78	resched_task(rq->curr);
	79	else
15afe09b	80	check_preempt_curr(rq, p, 0);
cb469845 SR	81	}
	82
	83	static void prio_changed_idle(struct rq rq, struct task_struct p,
	84	int oldprio, int running)
	85	{
	86	/* This can happen for hot plug CPUS */
	87
	88	/*
	89	* Reschedule if we are currently running on this runqueue and
	90	* our priority decreased, or if we are not currently running on
	91	* this runqueue and our priority is higher than the current's
	92	*/
	93	if (running) {
	94	if (p->prio > oldprio)
	95	resched_task(rq->curr);
	96	} else
15afe09b	97	check_preempt_curr(rq, p, 0);
cb469845 SR	98	}
cb469845 SR	99
fa72e9e4 IM	100	/*
	101	* Simple, special scheduling class for the per-CPU idle tasks:
	102	*/
2abdad0a	103	static const struct sched_class idle_sched_class = {
5522d5d5	104	/* .next is NULL */
fa72e9e4 IM	105	/* no enqueue/yield_task for idle tasks */
	106
	107	/* dequeue is not valid, we print a debug message there: */
	108	.dequeue_task = dequeue_task_idle,
	109
	110	.check_preempt_curr = check_preempt_curr_idle,
	111
	112	.pick_next_task = pick_next_task_idle,
	113	.put_prev_task = put_prev_task_idle,
	114
681f3e68	115	#ifdef CONFIG_SMP
4ce72a2c LZ	116	.select_task_rq = select_task_rq_idle,
4ce72a2c LZ	117
fa72e9e4	118	.load_balance = load_balance_idle,
e1d1484f	119	.move_one_task = move_one_task_idle,
681f3e68	120	#endif
fa72e9e4	121
83b699ed	122	.set_curr_task = set_curr_task_idle,
fa72e9e4	123	.task_tick = task_tick_idle,
cb469845 SR	124
	125	.prio_changed = prio_changed_idle,
	126	.switched_to = switched_to_idle,
	127
fa72e9e4 IM	128	/* no .task_new for idle tasks */
fa72e9e4 IM	129	};