Commit | Line | Data |
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029632fb PZ |
1 | #include "sched.h" |
2 | ||
34f971f6 PZ |
3 | /* |
4 | * stop-task scheduling class. | |
5 | * | |
6 | * The stop task is the highest priority task in the system, it preempts | |
7 | * everything and will be preempted by nothing. | |
8 | * | |
9 | * See kernel/stop_machine.c | |
10 | */ | |
11 | ||
12 | #ifdef CONFIG_SMP | |
13 | static int | |
7608dec2 | 14 | select_task_rq_stop(struct task_struct *p, int sd_flag, int flags) |
34f971f6 PZ |
15 | { |
16 | return task_cpu(p); /* stop tasks as never migrate */ | |
17 | } | |
18 | #endif /* CONFIG_SMP */ | |
19 | ||
20 | static void | |
21 | check_preempt_curr_stop(struct rq *rq, struct task_struct *p, int flags) | |
22 | { | |
1e5a7405 | 23 | /* we're never preempted */ |
34f971f6 PZ |
24 | } |
25 | ||
26 | static struct task_struct *pick_next_task_stop(struct rq *rq) | |
27 | { | |
28 | struct task_struct *stop = rq->stop; | |
29 | ||
8f618968 | 30 | if (stop && stop->on_rq) { |
78becc27 | 31 | stop->se.exec_start = rq_clock_task(rq); |
34f971f6 | 32 | return stop; |
8f618968 | 33 | } |
34f971f6 PZ |
34 | |
35 | return NULL; | |
36 | } | |
37 | ||
38 | static void | |
39 | enqueue_task_stop(struct rq *rq, struct task_struct *p, int flags) | |
40 | { | |
953bfcd1 | 41 | inc_nr_running(rq); |
34f971f6 PZ |
42 | } |
43 | ||
44 | static void | |
45 | dequeue_task_stop(struct rq *rq, struct task_struct *p, int flags) | |
46 | { | |
953bfcd1 | 47 | dec_nr_running(rq); |
34f971f6 PZ |
48 | } |
49 | ||
50 | static void yield_task_stop(struct rq *rq) | |
51 | { | |
52 | BUG(); /* the stop task should never yield, its pointless. */ | |
53 | } | |
54 | ||
55 | static void put_prev_task_stop(struct rq *rq, struct task_struct *prev) | |
56 | { | |
8f618968 MG |
57 | struct task_struct *curr = rq->curr; |
58 | u64 delta_exec; | |
59 | ||
78becc27 | 60 | delta_exec = rq_clock_task(rq) - curr->se.exec_start; |
8f618968 MG |
61 | if (unlikely((s64)delta_exec < 0)) |
62 | delta_exec = 0; | |
63 | ||
64 | schedstat_set(curr->se.statistics.exec_max, | |
65 | max(curr->se.statistics.exec_max, delta_exec)); | |
66 | ||
67 | curr->se.sum_exec_runtime += delta_exec; | |
68 | account_group_exec_runtime(curr, delta_exec); | |
69 | ||
78becc27 | 70 | curr->se.exec_start = rq_clock_task(rq); |
8f618968 | 71 | cpuacct_charge(curr, delta_exec); |
34f971f6 PZ |
72 | } |
73 | ||
74 | static void task_tick_stop(struct rq *rq, struct task_struct *curr, int queued) | |
75 | { | |
76 | } | |
77 | ||
78 | static void set_curr_task_stop(struct rq *rq) | |
79 | { | |
8f618968 MG |
80 | struct task_struct *stop = rq->stop; |
81 | ||
78becc27 | 82 | stop->se.exec_start = rq_clock_task(rq); |
34f971f6 PZ |
83 | } |
84 | ||
da7a735e | 85 | static void switched_to_stop(struct rq *rq, struct task_struct *p) |
34f971f6 PZ |
86 | { |
87 | BUG(); /* its impossible to change to this class */ | |
88 | } | |
89 | ||
da7a735e PZ |
90 | static void |
91 | prio_changed_stop(struct rq *rq, struct task_struct *p, int oldprio) | |
34f971f6 PZ |
92 | { |
93 | BUG(); /* how!?, what priority? */ | |
94 | } | |
95 | ||
96 | static unsigned int | |
97 | get_rr_interval_stop(struct rq *rq, struct task_struct *task) | |
98 | { | |
99 | return 0; | |
100 | } | |
101 | ||
102 | /* | |
103 | * Simple, special scheduling class for the per-CPU stop tasks: | |
104 | */ | |
029632fb | 105 | const struct sched_class stop_sched_class = { |
34f971f6 PZ |
106 | .next = &rt_sched_class, |
107 | ||
108 | .enqueue_task = enqueue_task_stop, | |
109 | .dequeue_task = dequeue_task_stop, | |
110 | .yield_task = yield_task_stop, | |
111 | ||
112 | .check_preempt_curr = check_preempt_curr_stop, | |
113 | ||
114 | .pick_next_task = pick_next_task_stop, | |
115 | .put_prev_task = put_prev_task_stop, | |
116 | ||
117 | #ifdef CONFIG_SMP | |
118 | .select_task_rq = select_task_rq_stop, | |
119 | #endif | |
120 | ||
121 | .set_curr_task = set_curr_task_stop, | |
122 | .task_tick = task_tick_stop, | |
123 | ||
124 | .get_rr_interval = get_rr_interval_stop, | |
125 | ||
126 | .prio_changed = prio_changed_stop, | |
127 | .switched_to = switched_to_stop, | |
34f971f6 | 128 | }; |