blob: 3a4f92dbbe6609b786da0add62f2306e991b791f [file] [log] [blame]
Ingo Molnarfa72e9e2007-07-09 18:51:58 +02001/*
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
Gregory Haskinse7693a32008-01-25 21:08:09 +01008#ifdef CONFIG_SMP
9static 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 */
Ingo Molnarfa72e9e2007-07-09 18:51:58 +020014/*
15 * Idle tasks are unconditionally rescheduled:
16 */
17static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p)
18{
19 resched_task(rq->idle);
20}
21
Ingo Molnarfb8d4722007-08-09 11:16:48 +020022static struct task_struct *pick_next_task_idle(struct rq *rq)
Ingo Molnarfa72e9e2007-07-09 18:51:58 +020023{
24 schedstat_inc(rq, sched_goidle);
25
26 return rq->idle;
27}
28
29/*
30 * It is not legal to sleep in the idle task - print a warning
31 * message if some code attempts to do it:
32 */
33static void
Ingo Molnarf02231e2007-08-09 11:16:48 +020034dequeue_task_idle(struct rq *rq, struct task_struct *p, int sleep)
Ingo Molnarfa72e9e2007-07-09 18:51:58 +020035{
36 spin_unlock_irq(&rq->lock);
37 printk(KERN_ERR "bad: scheduling from the idle thread!\n");
38 dump_stack();
39 spin_lock_irq(&rq->lock);
40}
41
Ingo Molnar31ee5292007-08-09 11:16:49 +020042static void put_prev_task_idle(struct rq *rq, struct task_struct *prev)
Ingo Molnarfa72e9e2007-07-09 18:51:58 +020043{
44}
45
Peter Williams681f3e62007-10-24 18:23:51 +020046#ifdef CONFIG_SMP
Peter Williams43010652007-08-09 11:16:46 +020047static unsigned long
Ingo Molnarfa72e9e2007-07-09 18:51:58 +020048load_balance_idle(struct rq *this_rq, int this_cpu, struct rq *busiest,
Peter Williamse1d14842007-10-24 18:23:51 +020049 unsigned long max_load_move,
50 struct sched_domain *sd, enum cpu_idle_type idle,
51 int *all_pinned, int *this_best_prio)
52{
53 return 0;
54}
55
56static int
57move_one_task_idle(struct rq *this_rq, int this_cpu, struct rq *busiest,
58 struct sched_domain *sd, enum cpu_idle_type idle)
Ingo Molnarfa72e9e2007-07-09 18:51:58 +020059{
60 return 0;
61}
Peter Williams681f3e62007-10-24 18:23:51 +020062#endif
Ingo Molnarfa72e9e2007-07-09 18:51:58 +020063
Peter Zijlstra8f4d37e2008-01-25 21:08:29 +010064static void task_tick_idle(struct rq *rq, struct task_struct *curr, int queued)
Ingo Molnarfa72e9e2007-07-09 18:51:58 +020065{
66}
67
Srivatsa Vaddagiri83b699e2007-10-15 17:00:08 +020068static void set_curr_task_idle(struct rq *rq)
69{
70}
71
Steven Rostedtcb469842008-01-25 21:08:22 +010072static void switched_to_idle(struct rq *rq, struct task_struct *p,
73 int running)
74{
75 /* Can this actually happen?? */
76 if (running)
77 resched_task(rq->curr);
78 else
79 check_preempt_curr(rq, p);
80}
81
82static void prio_changed_idle(struct rq *rq, struct task_struct *p,
83 int oldprio, int running)
84{
85 /* This can happen for hot plug CPUS */
86
87 /*
88 * Reschedule if we are currently running on this runqueue and
89 * our priority decreased, or if we are not currently running on
90 * this runqueue and our priority is higher than the current's
91 */
92 if (running) {
93 if (p->prio > oldprio)
94 resched_task(rq->curr);
95 } else
96 check_preempt_curr(rq, p);
97}
98
Ingo Molnarfa72e9e2007-07-09 18:51:58 +020099/*
100 * Simple, special scheduling class for the per-CPU idle tasks:
101 */
Harvey Harrison2abdad02008-04-25 10:53:13 -0700102static const struct sched_class idle_sched_class = {
Ingo Molnar5522d5d2007-10-15 17:00:12 +0200103 /* .next is NULL */
Ingo Molnarfa72e9e2007-07-09 18:51:58 +0200104 /* no enqueue/yield_task for idle tasks */
105
106 /* dequeue is not valid, we print a debug message there: */
107 .dequeue_task = dequeue_task_idle,
Gregory Haskinse7693a32008-01-25 21:08:09 +0100108#ifdef CONFIG_SMP
109 .select_task_rq = select_task_rq_idle,
110#endif /* CONFIG_SMP */
Ingo Molnarfa72e9e2007-07-09 18:51:58 +0200111
112 .check_preempt_curr = check_preempt_curr_idle,
113
114 .pick_next_task = pick_next_task_idle,
115 .put_prev_task = put_prev_task_idle,
116
Peter Williams681f3e62007-10-24 18:23:51 +0200117#ifdef CONFIG_SMP
Ingo Molnarfa72e9e2007-07-09 18:51:58 +0200118 .load_balance = load_balance_idle,
Peter Williamse1d14842007-10-24 18:23:51 +0200119 .move_one_task = move_one_task_idle,
Peter Williams681f3e62007-10-24 18:23:51 +0200120#endif
Ingo Molnarfa72e9e2007-07-09 18:51:58 +0200121
Srivatsa Vaddagiri83b699e2007-10-15 17:00:08 +0200122 .set_curr_task = set_curr_task_idle,
Ingo Molnarfa72e9e2007-07-09 18:51:58 +0200123 .task_tick = task_tick_idle,
Steven Rostedtcb469842008-01-25 21:08:22 +0100124
125 .prio_changed = prio_changed_idle,
126 .switched_to = switched_to_idle,
127
Ingo Molnarfa72e9e2007-07-09 18:51:58 +0200128 /* no .task_new for idle tasks */
129};