[net-next-2.6.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 rq *rq, struct task_struct *p, int sd_flag, int flags)
{
	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 flags)
{
	resched_task(rq->idle);
}

static struct task_struct *pick_next_task_idle(struct rq *rq)
{
	schedstat_inc(rq, sched_goidle);
	calc_load_account_idle(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 flags)
{
	raw_spin_unlock_irq(&rq->lock);
	printk(KERN_ERR "bad: scheduling from the idle thread!\n");
	dump_stack();
	raw_spin_lock_irq(&rq->lock);
}

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

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);
}

static unsigned int get_rr_interval_idle(struct rq *rq, struct task_struct *task)
{
	return 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,
#endif

	.set_curr_task          = set_curr_task_idle,
	.task_tick		= task_tick_idle,

	.get_rr_interval	= get_rr_interval_idle,

	.prio_changed		= prio_changed_idle,
	.switched_to		= switched_to_idle,

	/* no .task_new for idle tasks */
};
Commit	Line	Data
	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
	8	#ifdef CONFIG_SMP
	9	static int
	10	select_task_rq_idle(struct rq rq, struct task_struct p, int sd_flag, int flags)
	11	{
	12	return task_cpu(p); /* IDLE tasks as never migrated */
	13	}
	14	#endif /* CONFIG_SMP */
	15	/*
	16	* Idle tasks are unconditionally rescheduled:
	17	*/
	18	static void check_preempt_curr_idle(struct rq rq, struct task_struct p, int flags)
	19	{
	20	resched_task(rq->idle);
	21	}
	22
	23	static struct task_struct pick_next_task_idle(struct rq rq)
	24	{
	25	schedstat_inc(rq, sched_goidle);
	26	calc_load_account_idle(rq);
	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
	35	dequeue_task_idle(struct rq rq, struct task_struct p, int flags)
	36	{
	37	raw_spin_unlock_irq(&rq->lock);
	38	printk(KERN_ERR "bad: scheduling from the idle thread!\n");
	39	dump_stack();
	40	raw_spin_lock_irq(&rq->lock);
	41	}
	42
	43	static void put_prev_task_idle(struct rq rq, struct task_struct prev)
	44	{
	45	}
	46
	47	static void task_tick_idle(struct rq rq, struct task_struct curr, int queued)
	48	{
	49	}
	50
	51	static void set_curr_task_idle(struct rq *rq)
	52	{
	53	}
	54
	55	static void switched_to_idle(struct rq rq, struct task_struct p,
	56	int running)
	57	{
	58	/* Can this actually happen?? */
	59	if (running)
	60	resched_task(rq->curr);
	61	else
	62	check_preempt_curr(rq, p, 0);
	63	}
	64
	65	static void prio_changed_idle(struct rq rq, struct task_struct p,
	66	int oldprio, int running)
	67	{
	68	/* This can happen for hot plug CPUS */
	69
	70	/*
	71	* Reschedule if we are currently running on this runqueue and
	72	* our priority decreased, or if we are not currently running on
	73	* this runqueue and our priority is higher than the current's
	74	*/
	75	if (running) {
	76	if (p->prio > oldprio)
	77	resched_task(rq->curr);
	78	} else
	79	check_preempt_curr(rq, p, 0);
	80	}
	81
	82	static unsigned int get_rr_interval_idle(struct rq rq, struct task_struct task)
	83	{
	84	return 0;
	85	}
	86
	87	/*
	88	* Simple, special scheduling class for the per-CPU idle tasks:
	89	*/
	90	static const struct sched_class idle_sched_class = {
	91	/* .next is NULL */
	92	/* no enqueue/yield_task for idle tasks */
	93
	94	/* dequeue is not valid, we print a debug message there: */
	95	.dequeue_task = dequeue_task_idle,
	96
	97	.check_preempt_curr = check_preempt_curr_idle,
	98
	99	.pick_next_task = pick_next_task_idle,
	100	.put_prev_task = put_prev_task_idle,
	101
	102	#ifdef CONFIG_SMP
	103	.select_task_rq = select_task_rq_idle,
	104	#endif
	105
	106	.set_curr_task = set_curr_task_idle,
	107	.task_tick = task_tick_idle,
	108
	109	.get_rr_interval = get_rr_interval_idle,
	110
	111	.prio_changed = prio_changed_idle,
	112	.switched_to = switched_to_idle,
	113
	114	/* no .task_new for idle tasks */
	115	};