sched: isolate SMP balancing code a bit more
[linux-2.6.git] / kernel / sched_idletask.c
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 /*
9  * Idle tasks are unconditionally rescheduled:
10  */
11 static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p)
12 {
13         resched_task(rq->idle);
14 }
15
16 static struct task_struct *pick_next_task_idle(struct rq *rq)
17 {
18         schedstat_inc(rq, sched_goidle);
19
20         return rq->idle;
21 }
22
23 /*
24  * It is not legal to sleep in the idle task - print a warning
25  * message if some code attempts to do it:
26  */
27 static void
28 dequeue_task_idle(struct rq *rq, struct task_struct *p, int sleep)
29 {
30         spin_unlock_irq(&rq->lock);
31         printk(KERN_ERR "bad: scheduling from the idle thread!\n");
32         dump_stack();
33         spin_lock_irq(&rq->lock);
34 }
35
36 static void put_prev_task_idle(struct rq *rq, struct task_struct *prev)
37 {
38 }
39
40 #ifdef CONFIG_SMP
41 static unsigned long
42 load_balance_idle(struct rq *this_rq, int this_cpu, struct rq *busiest,
43                   unsigned long max_load_move,
44                   struct sched_domain *sd, enum cpu_idle_type idle,
45                   int *all_pinned, int *this_best_prio)
46 {
47         return 0;
48 }
49
50 static int
51 move_one_task_idle(struct rq *this_rq, int this_cpu, struct rq *busiest,
52                    struct sched_domain *sd, enum cpu_idle_type idle)
53 {
54         return 0;
55 }
56 #endif
57
58 static void task_tick_idle(struct rq *rq, struct task_struct *curr)
59 {
60 }
61
62 static void set_curr_task_idle(struct rq *rq)
63 {
64 }
65
66 /*
67  * Simple, special scheduling class for the per-CPU idle tasks:
68  */
69 const struct sched_class idle_sched_class = {
70         /* .next is NULL */
71         /* no enqueue/yield_task for idle tasks */
72
73         /* dequeue is not valid, we print a debug message there: */
74         .dequeue_task           = dequeue_task_idle,
75
76         .check_preempt_curr     = check_preempt_curr_idle,
77
78         .pick_next_task         = pick_next_task_idle,
79         .put_prev_task          = put_prev_task_idle,
80
81 #ifdef CONFIG_SMP
82         .load_balance           = load_balance_idle,
83         .move_one_task          = move_one_task_idle,
84 #endif
85
86         .set_curr_task          = set_curr_task_idle,
87         .task_tick              = task_tick_idle,
88         /* no .task_new for idle tasks */
89 };