Ingo Molnar | fa72e9e | 2007-07-09 18:51:58 +0200 | [diff] [blame] | 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 | |
Gregory Haskins | e7693a3 | 2008-01-25 21:08:09 +0100 | [diff] [blame] | 8 | #ifdef CONFIG_SMP |
Peter Zijlstra | 0017d73 | 2010-03-24 18:34:10 +0100 | [diff] [blame] | 9 | static int |
| 10 | select_task_rq_idle(struct rq *rq, struct task_struct *p, int sd_flag, int flags) |
Gregory Haskins | e7693a3 | 2008-01-25 21:08:09 +0100 | [diff] [blame] | 11 | { |
| 12 | return task_cpu(p); /* IDLE tasks as never migrated */ |
| 13 | } |
| 14 | #endif /* CONFIG_SMP */ |
Ingo Molnar | fa72e9e | 2007-07-09 18:51:58 +0200 | [diff] [blame] | 15 | /* |
| 16 | * Idle tasks are unconditionally rescheduled: |
| 17 | */ |
Peter Zijlstra | 7d47872 | 2009-09-14 19:55:44 +0200 | [diff] [blame] | 18 | static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p, int flags) |
Ingo Molnar | fa72e9e | 2007-07-09 18:51:58 +0200 | [diff] [blame] | 19 | { |
| 20 | resched_task(rq->idle); |
| 21 | } |
| 22 | |
Ingo Molnar | fb8d472 | 2007-08-09 11:16:48 +0200 | [diff] [blame] | 23 | static struct task_struct *pick_next_task_idle(struct rq *rq) |
Ingo Molnar | fa72e9e | 2007-07-09 18:51:58 +0200 | [diff] [blame] | 24 | { |
| 25 | schedstat_inc(rq, sched_goidle); |
Peter Zijlstra | 74f5187 | 2010-04-22 21:50:19 +0200 | [diff] [blame] | 26 | calc_load_account_idle(rq); |
Ingo Molnar | fa72e9e | 2007-07-09 18:51:58 +0200 | [diff] [blame] | 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 |
Peter Zijlstra | 371fd7e | 2010-03-24 16:38:48 +0100 | [diff] [blame] | 35 | dequeue_task_idle(struct rq *rq, struct task_struct *p, int flags) |
Ingo Molnar | fa72e9e | 2007-07-09 18:51:58 +0200 | [diff] [blame] | 36 | { |
Thomas Gleixner | 05fa785 | 2009-11-17 14:28:38 +0100 | [diff] [blame] | 37 | raw_spin_unlock_irq(&rq->lock); |
Peter Zijlstra | 3df0fc5 | 2009-12-20 14:23:57 +0100 | [diff] [blame] | 38 | printk(KERN_ERR "bad: scheduling from the idle thread!\n"); |
Ingo Molnar | fa72e9e | 2007-07-09 18:51:58 +0200 | [diff] [blame] | 39 | dump_stack(); |
Thomas Gleixner | 05fa785 | 2009-11-17 14:28:38 +0100 | [diff] [blame] | 40 | raw_spin_lock_irq(&rq->lock); |
Ingo Molnar | fa72e9e | 2007-07-09 18:51:58 +0200 | [diff] [blame] | 41 | } |
| 42 | |
Ingo Molnar | 31ee529 | 2007-08-09 11:16:49 +0200 | [diff] [blame] | 43 | static void put_prev_task_idle(struct rq *rq, struct task_struct *prev) |
Ingo Molnar | fa72e9e | 2007-07-09 18:51:58 +0200 | [diff] [blame] | 44 | { |
| 45 | } |
| 46 | |
Peter Zijlstra | 8f4d37e | 2008-01-25 21:08:29 +0100 | [diff] [blame] | 47 | static void task_tick_idle(struct rq *rq, struct task_struct *curr, int queued) |
Ingo Molnar | fa72e9e | 2007-07-09 18:51:58 +0200 | [diff] [blame] | 48 | { |
| 49 | } |
| 50 | |
Srivatsa Vaddagiri | 83b699e | 2007-10-15 17:00:08 +0200 | [diff] [blame] | 51 | static void set_curr_task_idle(struct rq *rq) |
| 52 | { |
| 53 | } |
| 54 | |
Steven Rostedt | cb46984 | 2008-01-25 21:08:22 +0100 | [diff] [blame] | 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 |
Peter Zijlstra | 15afe09 | 2008-09-20 23:38:02 +0200 | [diff] [blame] | 62 | check_preempt_curr(rq, p, 0); |
Steven Rostedt | cb46984 | 2008-01-25 21:08:22 +0100 | [diff] [blame] | 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 |
Peter Zijlstra | 15afe09 | 2008-09-20 23:38:02 +0200 | [diff] [blame] | 79 | check_preempt_curr(rq, p, 0); |
Steven Rostedt | cb46984 | 2008-01-25 21:08:22 +0100 | [diff] [blame] | 80 | } |
| 81 | |
H Hartley Sweeten | 6d686f4 | 2010-01-13 20:21:52 -0700 | [diff] [blame] | 82 | static unsigned int get_rr_interval_idle(struct rq *rq, struct task_struct *task) |
Peter Williams | 0d721ce | 2009-09-21 01:31:53 +0000 | [diff] [blame] | 83 | { |
| 84 | return 0; |
| 85 | } |
| 86 | |
Ingo Molnar | fa72e9e | 2007-07-09 18:51:58 +0200 | [diff] [blame] | 87 | /* |
| 88 | * Simple, special scheduling class for the per-CPU idle tasks: |
| 89 | */ |
Harvey Harrison | 2abdad0 | 2008-04-25 10:53:13 -0700 | [diff] [blame] | 90 | static const struct sched_class idle_sched_class = { |
Ingo Molnar | 5522d5d | 2007-10-15 17:00:12 +0200 | [diff] [blame] | 91 | /* .next is NULL */ |
Ingo Molnar | fa72e9e | 2007-07-09 18:51:58 +0200 | [diff] [blame] | 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 | |
Peter Williams | 681f3e6 | 2007-10-24 18:23:51 +0200 | [diff] [blame] | 102 | #ifdef CONFIG_SMP |
Li Zefan | 4ce72a2 | 2008-10-22 15:25:26 +0800 | [diff] [blame] | 103 | .select_task_rq = select_task_rq_idle, |
Peter Williams | 681f3e6 | 2007-10-24 18:23:51 +0200 | [diff] [blame] | 104 | #endif |
Ingo Molnar | fa72e9e | 2007-07-09 18:51:58 +0200 | [diff] [blame] | 105 | |
Srivatsa Vaddagiri | 83b699e | 2007-10-15 17:00:08 +0200 | [diff] [blame] | 106 | .set_curr_task = set_curr_task_idle, |
Ingo Molnar | fa72e9e | 2007-07-09 18:51:58 +0200 | [diff] [blame] | 107 | .task_tick = task_tick_idle, |
Steven Rostedt | cb46984 | 2008-01-25 21:08:22 +0100 | [diff] [blame] | 108 | |
Peter Williams | 0d721ce | 2009-09-21 01:31:53 +0000 | [diff] [blame] | 109 | .get_rr_interval = get_rr_interval_idle, |
| 110 | |
Steven Rostedt | cb46984 | 2008-01-25 21:08:22 +0100 | [diff] [blame] | 111 | .prio_changed = prio_changed_idle, |
| 112 | .switched_to = switched_to_idle, |
| 113 | |
Ingo Molnar | fa72e9e | 2007-07-09 18:51:58 +0200 | [diff] [blame] | 114 | /* no .task_new for idle tasks */ |
| 115 | }; |