LXR linux/kernel/sched

   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 */
  11static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p)
  12{
  13        resched_task(rq->idle);
  14}
  15
  16static 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 */
  27static void
  28dequeue_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
  36static void put_prev_task_idle(struct rq *rq, struct task_struct *prev)
  37{
  38}
  39
  40#ifdef CONFIG_SMP
  41static unsigned long
  42load_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
  50static int
  51move_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
  58static void task_tick_idle(struct rq *rq, struct task_struct *curr)
  59{
  60}
  61
  62static void set_curr_task_idle(struct rq *rq)
  63{
  64}
  65
  66/*
  67 * Simple, special scheduling class for the per-CPU idle tasks:
  68 */
  69const 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};
  90