Commit | Line | Data |
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bb44e5d1 IM |
1 | /* |
2 | * Real-Time Scheduling Class (mapped to the SCHED_FIFO and SCHED_RR | |
3 | * policies) | |
4 | */ | |
5 | ||
6 | /* | |
7 | * Update the current task's runtime statistics. Skip current tasks that | |
8 | * are not in our scheduling class. | |
9 | */ | |
a9957449 | 10 | static void update_curr_rt(struct rq *rq) |
bb44e5d1 IM |
11 | { |
12 | struct task_struct *curr = rq->curr; | |
13 | u64 delta_exec; | |
14 | ||
15 | if (!task_has_rt_policy(curr)) | |
16 | return; | |
17 | ||
d281918d | 18 | delta_exec = rq->clock - curr->se.exec_start; |
bb44e5d1 IM |
19 | if (unlikely((s64)delta_exec < 0)) |
20 | delta_exec = 0; | |
6cfb0d5d IM |
21 | |
22 | schedstat_set(curr->se.exec_max, max(curr->se.exec_max, delta_exec)); | |
bb44e5d1 IM |
23 | |
24 | curr->se.sum_exec_runtime += delta_exec; | |
d281918d | 25 | curr->se.exec_start = rq->clock; |
d842de87 | 26 | cpuacct_charge(curr, delta_exec); |
bb44e5d1 IM |
27 | } |
28 | ||
fd390f6a | 29 | static void enqueue_task_rt(struct rq *rq, struct task_struct *p, int wakeup) |
bb44e5d1 IM |
30 | { |
31 | struct rt_prio_array *array = &rq->rt.active; | |
32 | ||
33 | list_add_tail(&p->run_list, array->queue + p->prio); | |
34 | __set_bit(p->prio, array->bitmap); | |
35 | } | |
36 | ||
37 | /* | |
38 | * Adding/removing a task to/from a priority array: | |
39 | */ | |
f02231e5 | 40 | static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int sleep) |
bb44e5d1 IM |
41 | { |
42 | struct rt_prio_array *array = &rq->rt.active; | |
43 | ||
f1e14ef6 | 44 | update_curr_rt(rq); |
bb44e5d1 IM |
45 | |
46 | list_del(&p->run_list); | |
47 | if (list_empty(array->queue + p->prio)) | |
48 | __clear_bit(p->prio, array->bitmap); | |
49 | } | |
50 | ||
51 | /* | |
52 | * Put task to the end of the run list without the overhead of dequeue | |
53 | * followed by enqueue. | |
54 | */ | |
55 | static void requeue_task_rt(struct rq *rq, struct task_struct *p) | |
56 | { | |
57 | struct rt_prio_array *array = &rq->rt.active; | |
58 | ||
59 | list_move_tail(&p->run_list, array->queue + p->prio); | |
60 | } | |
61 | ||
62 | static void | |
4530d7ab | 63 | yield_task_rt(struct rq *rq) |
bb44e5d1 | 64 | { |
4530d7ab | 65 | requeue_task_rt(rq, rq->curr); |
bb44e5d1 IM |
66 | } |
67 | ||
68 | /* | |
69 | * Preempt the current task with a newly woken task if needed: | |
70 | */ | |
71 | static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p) | |
72 | { | |
73 | if (p->prio < rq->curr->prio) | |
74 | resched_task(rq->curr); | |
75 | } | |
76 | ||
fb8d4724 | 77 | static struct task_struct *pick_next_task_rt(struct rq *rq) |
bb44e5d1 IM |
78 | { |
79 | struct rt_prio_array *array = &rq->rt.active; | |
80 | struct task_struct *next; | |
81 | struct list_head *queue; | |
82 | int idx; | |
83 | ||
84 | idx = sched_find_first_bit(array->bitmap); | |
85 | if (idx >= MAX_RT_PRIO) | |
86 | return NULL; | |
87 | ||
88 | queue = array->queue + idx; | |
89 | next = list_entry(queue->next, struct task_struct, run_list); | |
90 | ||
d281918d | 91 | next->se.exec_start = rq->clock; |
bb44e5d1 IM |
92 | |
93 | return next; | |
94 | } | |
95 | ||
31ee529c | 96 | static void put_prev_task_rt(struct rq *rq, struct task_struct *p) |
bb44e5d1 | 97 | { |
f1e14ef6 | 98 | update_curr_rt(rq); |
bb44e5d1 IM |
99 | p->se.exec_start = 0; |
100 | } | |
101 | ||
681f3e68 | 102 | #ifdef CONFIG_SMP |
bb44e5d1 IM |
103 | /* |
104 | * Load-balancing iterator. Note: while the runqueue stays locked | |
105 | * during the whole iteration, the current task might be | |
106 | * dequeued so the iterator has to be dequeue-safe. Here we | |
107 | * achieve that by always pre-iterating before returning | |
108 | * the current task: | |
109 | */ | |
110 | static struct task_struct *load_balance_start_rt(void *arg) | |
111 | { | |
112 | struct rq *rq = arg; | |
113 | struct rt_prio_array *array = &rq->rt.active; | |
114 | struct list_head *head, *curr; | |
115 | struct task_struct *p; | |
116 | int idx; | |
117 | ||
118 | idx = sched_find_first_bit(array->bitmap); | |
119 | if (idx >= MAX_RT_PRIO) | |
120 | return NULL; | |
121 | ||
122 | head = array->queue + idx; | |
123 | curr = head->prev; | |
124 | ||
125 | p = list_entry(curr, struct task_struct, run_list); | |
126 | ||
127 | curr = curr->prev; | |
128 | ||
129 | rq->rt.rt_load_balance_idx = idx; | |
130 | rq->rt.rt_load_balance_head = head; | |
131 | rq->rt.rt_load_balance_curr = curr; | |
132 | ||
133 | return p; | |
134 | } | |
135 | ||
136 | static struct task_struct *load_balance_next_rt(void *arg) | |
137 | { | |
138 | struct rq *rq = arg; | |
139 | struct rt_prio_array *array = &rq->rt.active; | |
140 | struct list_head *head, *curr; | |
141 | struct task_struct *p; | |
142 | int idx; | |
143 | ||
144 | idx = rq->rt.rt_load_balance_idx; | |
145 | head = rq->rt.rt_load_balance_head; | |
146 | curr = rq->rt.rt_load_balance_curr; | |
147 | ||
148 | /* | |
149 | * If we arrived back to the head again then | |
150 | * iterate to the next queue (if any): | |
151 | */ | |
152 | if (unlikely(head == curr)) { | |
153 | int next_idx = find_next_bit(array->bitmap, MAX_RT_PRIO, idx+1); | |
154 | ||
155 | if (next_idx >= MAX_RT_PRIO) | |
156 | return NULL; | |
157 | ||
158 | idx = next_idx; | |
159 | head = array->queue + idx; | |
160 | curr = head->prev; | |
161 | ||
162 | rq->rt.rt_load_balance_idx = idx; | |
163 | rq->rt.rt_load_balance_head = head; | |
164 | } | |
165 | ||
166 | p = list_entry(curr, struct task_struct, run_list); | |
167 | ||
168 | curr = curr->prev; | |
169 | ||
170 | rq->rt.rt_load_balance_curr = curr; | |
171 | ||
172 | return p; | |
173 | } | |
174 | ||
43010659 | 175 | static unsigned long |
bb44e5d1 | 176 | load_balance_rt(struct rq *this_rq, int this_cpu, struct rq *busiest, |
e1d1484f PW |
177 | unsigned long max_load_move, |
178 | struct sched_domain *sd, enum cpu_idle_type idle, | |
179 | int *all_pinned, int *this_best_prio) | |
bb44e5d1 | 180 | { |
bb44e5d1 IM |
181 | struct rq_iterator rt_rq_iterator; |
182 | ||
bb44e5d1 IM |
183 | rt_rq_iterator.start = load_balance_start_rt; |
184 | rt_rq_iterator.next = load_balance_next_rt; | |
185 | /* pass 'busiest' rq argument into | |
186 | * load_balance_[start|next]_rt iterators | |
187 | */ | |
188 | rt_rq_iterator.arg = busiest; | |
189 | ||
e1d1484f PW |
190 | return balance_tasks(this_rq, this_cpu, busiest, max_load_move, sd, |
191 | idle, all_pinned, this_best_prio, &rt_rq_iterator); | |
192 | } | |
193 | ||
194 | static int | |
195 | move_one_task_rt(struct rq *this_rq, int this_cpu, struct rq *busiest, | |
196 | struct sched_domain *sd, enum cpu_idle_type idle) | |
197 | { | |
198 | struct rq_iterator rt_rq_iterator; | |
199 | ||
200 | rt_rq_iterator.start = load_balance_start_rt; | |
201 | rt_rq_iterator.next = load_balance_next_rt; | |
202 | rt_rq_iterator.arg = busiest; | |
bb44e5d1 | 203 | |
e1d1484f PW |
204 | return iter_move_one_task(this_rq, this_cpu, busiest, sd, idle, |
205 | &rt_rq_iterator); | |
bb44e5d1 | 206 | } |
681f3e68 | 207 | #endif |
bb44e5d1 IM |
208 | |
209 | static void task_tick_rt(struct rq *rq, struct task_struct *p) | |
210 | { | |
67e2be02 PZ |
211 | update_curr_rt(rq); |
212 | ||
bb44e5d1 IM |
213 | /* |
214 | * RR tasks need a special form of timeslice management. | |
215 | * FIFO tasks have no timeslices. | |
216 | */ | |
217 | if (p->policy != SCHED_RR) | |
218 | return; | |
219 | ||
220 | if (--p->time_slice) | |
221 | return; | |
222 | ||
a4ec24b4 | 223 | p->time_slice = DEF_TIMESLICE; |
bb44e5d1 | 224 | |
98fbc798 DA |
225 | /* |
226 | * Requeue to the end of queue if we are not the only element | |
227 | * on the queue: | |
228 | */ | |
229 | if (p->run_list.prev != p->run_list.next) { | |
230 | requeue_task_rt(rq, p); | |
231 | set_tsk_need_resched(p); | |
232 | } | |
bb44e5d1 IM |
233 | } |
234 | ||
83b699ed SV |
235 | static void set_curr_task_rt(struct rq *rq) |
236 | { | |
237 | struct task_struct *p = rq->curr; | |
238 | ||
239 | p->se.exec_start = rq->clock; | |
240 | } | |
241 | ||
5522d5d5 IM |
242 | const struct sched_class rt_sched_class = { |
243 | .next = &fair_sched_class, | |
bb44e5d1 IM |
244 | .enqueue_task = enqueue_task_rt, |
245 | .dequeue_task = dequeue_task_rt, | |
246 | .yield_task = yield_task_rt, | |
247 | ||
248 | .check_preempt_curr = check_preempt_curr_rt, | |
249 | ||
250 | .pick_next_task = pick_next_task_rt, | |
251 | .put_prev_task = put_prev_task_rt, | |
252 | ||
681f3e68 | 253 | #ifdef CONFIG_SMP |
bb44e5d1 | 254 | .load_balance = load_balance_rt, |
e1d1484f | 255 | .move_one_task = move_one_task_rt, |
681f3e68 | 256 | #endif |
bb44e5d1 | 257 | |
83b699ed | 258 | .set_curr_task = set_curr_task_rt, |
bb44e5d1 | 259 | .task_tick = task_tick_rt, |
bb44e5d1 | 260 | }; |