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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); | |
58e2d4ca | 35 | inc_cpu_load(rq, p->se.load.weight); |
bb44e5d1 IM |
36 | } |
37 | ||
38 | /* | |
39 | * Adding/removing a task to/from a priority array: | |
40 | */ | |
f02231e5 | 41 | static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int sleep) |
bb44e5d1 IM |
42 | { |
43 | struct rt_prio_array *array = &rq->rt.active; | |
44 | ||
f1e14ef6 | 45 | update_curr_rt(rq); |
bb44e5d1 IM |
46 | |
47 | list_del(&p->run_list); | |
48 | if (list_empty(array->queue + p->prio)) | |
49 | __clear_bit(p->prio, array->bitmap); | |
58e2d4ca | 50 | dec_cpu_load(rq, p->se.load.weight); |
bb44e5d1 IM |
51 | } |
52 | ||
53 | /* | |
54 | * Put task to the end of the run list without the overhead of dequeue | |
55 | * followed by enqueue. | |
56 | */ | |
57 | static void requeue_task_rt(struct rq *rq, struct task_struct *p) | |
58 | { | |
59 | struct rt_prio_array *array = &rq->rt.active; | |
60 | ||
61 | list_move_tail(&p->run_list, array->queue + p->prio); | |
62 | } | |
63 | ||
64 | static void | |
4530d7ab | 65 | yield_task_rt(struct rq *rq) |
bb44e5d1 | 66 | { |
4530d7ab | 67 | requeue_task_rt(rq, rq->curr); |
bb44e5d1 IM |
68 | } |
69 | ||
70 | /* | |
71 | * Preempt the current task with a newly woken task if needed: | |
72 | */ | |
73 | static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p) | |
74 | { | |
75 | if (p->prio < rq->curr->prio) | |
76 | resched_task(rq->curr); | |
77 | } | |
78 | ||
fb8d4724 | 79 | static struct task_struct *pick_next_task_rt(struct rq *rq) |
bb44e5d1 IM |
80 | { |
81 | struct rt_prio_array *array = &rq->rt.active; | |
82 | struct task_struct *next; | |
83 | struct list_head *queue; | |
84 | int idx; | |
85 | ||
86 | idx = sched_find_first_bit(array->bitmap); | |
87 | if (idx >= MAX_RT_PRIO) | |
88 | return NULL; | |
89 | ||
90 | queue = array->queue + idx; | |
91 | next = list_entry(queue->next, struct task_struct, run_list); | |
92 | ||
d281918d | 93 | next->se.exec_start = rq->clock; |
bb44e5d1 IM |
94 | |
95 | return next; | |
96 | } | |
97 | ||
31ee529c | 98 | static void put_prev_task_rt(struct rq *rq, struct task_struct *p) |
bb44e5d1 | 99 | { |
f1e14ef6 | 100 | update_curr_rt(rq); |
bb44e5d1 IM |
101 | p->se.exec_start = 0; |
102 | } | |
103 | ||
681f3e68 | 104 | #ifdef CONFIG_SMP |
bb44e5d1 IM |
105 | /* |
106 | * Load-balancing iterator. Note: while the runqueue stays locked | |
107 | * during the whole iteration, the current task might be | |
108 | * dequeued so the iterator has to be dequeue-safe. Here we | |
109 | * achieve that by always pre-iterating before returning | |
110 | * the current task: | |
111 | */ | |
112 | static struct task_struct *load_balance_start_rt(void *arg) | |
113 | { | |
114 | struct rq *rq = arg; | |
115 | struct rt_prio_array *array = &rq->rt.active; | |
116 | struct list_head *head, *curr; | |
117 | struct task_struct *p; | |
118 | int idx; | |
119 | ||
120 | idx = sched_find_first_bit(array->bitmap); | |
121 | if (idx >= MAX_RT_PRIO) | |
122 | return NULL; | |
123 | ||
124 | head = array->queue + idx; | |
125 | curr = head->prev; | |
126 | ||
127 | p = list_entry(curr, struct task_struct, run_list); | |
128 | ||
129 | curr = curr->prev; | |
130 | ||
131 | rq->rt.rt_load_balance_idx = idx; | |
132 | rq->rt.rt_load_balance_head = head; | |
133 | rq->rt.rt_load_balance_curr = curr; | |
134 | ||
135 | return p; | |
136 | } | |
137 | ||
138 | static struct task_struct *load_balance_next_rt(void *arg) | |
139 | { | |
140 | struct rq *rq = arg; | |
141 | struct rt_prio_array *array = &rq->rt.active; | |
142 | struct list_head *head, *curr; | |
143 | struct task_struct *p; | |
144 | int idx; | |
145 | ||
146 | idx = rq->rt.rt_load_balance_idx; | |
147 | head = rq->rt.rt_load_balance_head; | |
148 | curr = rq->rt.rt_load_balance_curr; | |
149 | ||
150 | /* | |
151 | * If we arrived back to the head again then | |
152 | * iterate to the next queue (if any): | |
153 | */ | |
154 | if (unlikely(head == curr)) { | |
155 | int next_idx = find_next_bit(array->bitmap, MAX_RT_PRIO, idx+1); | |
156 | ||
157 | if (next_idx >= MAX_RT_PRIO) | |
158 | return NULL; | |
159 | ||
160 | idx = next_idx; | |
161 | head = array->queue + idx; | |
162 | curr = head->prev; | |
163 | ||
164 | rq->rt.rt_load_balance_idx = idx; | |
165 | rq->rt.rt_load_balance_head = head; | |
166 | } | |
167 | ||
168 | p = list_entry(curr, struct task_struct, run_list); | |
169 | ||
170 | curr = curr->prev; | |
171 | ||
172 | rq->rt.rt_load_balance_curr = curr; | |
173 | ||
174 | return p; | |
175 | } | |
176 | ||
43010659 | 177 | static unsigned long |
bb44e5d1 | 178 | load_balance_rt(struct rq *this_rq, int this_cpu, struct rq *busiest, |
e1d1484f PW |
179 | unsigned long max_load_move, |
180 | struct sched_domain *sd, enum cpu_idle_type idle, | |
181 | int *all_pinned, int *this_best_prio) | |
bb44e5d1 | 182 | { |
bb44e5d1 IM |
183 | struct rq_iterator rt_rq_iterator; |
184 | ||
bb44e5d1 IM |
185 | rt_rq_iterator.start = load_balance_start_rt; |
186 | rt_rq_iterator.next = load_balance_next_rt; | |
187 | /* pass 'busiest' rq argument into | |
188 | * load_balance_[start|next]_rt iterators | |
189 | */ | |
190 | rt_rq_iterator.arg = busiest; | |
191 | ||
e1d1484f PW |
192 | return balance_tasks(this_rq, this_cpu, busiest, max_load_move, sd, |
193 | idle, all_pinned, this_best_prio, &rt_rq_iterator); | |
194 | } | |
195 | ||
196 | static int | |
197 | move_one_task_rt(struct rq *this_rq, int this_cpu, struct rq *busiest, | |
198 | struct sched_domain *sd, enum cpu_idle_type idle) | |
199 | { | |
200 | struct rq_iterator rt_rq_iterator; | |
201 | ||
202 | rt_rq_iterator.start = load_balance_start_rt; | |
203 | rt_rq_iterator.next = load_balance_next_rt; | |
204 | rt_rq_iterator.arg = busiest; | |
bb44e5d1 | 205 | |
e1d1484f PW |
206 | return iter_move_one_task(this_rq, this_cpu, busiest, sd, idle, |
207 | &rt_rq_iterator); | |
bb44e5d1 | 208 | } |
681f3e68 | 209 | #endif |
bb44e5d1 IM |
210 | |
211 | static void task_tick_rt(struct rq *rq, struct task_struct *p) | |
212 | { | |
67e2be02 PZ |
213 | update_curr_rt(rq); |
214 | ||
bb44e5d1 IM |
215 | /* |
216 | * RR tasks need a special form of timeslice management. | |
217 | * FIFO tasks have no timeslices. | |
218 | */ | |
219 | if (p->policy != SCHED_RR) | |
220 | return; | |
221 | ||
222 | if (--p->time_slice) | |
223 | return; | |
224 | ||
a4ec24b4 | 225 | p->time_slice = DEF_TIMESLICE; |
bb44e5d1 | 226 | |
98fbc798 DA |
227 | /* |
228 | * Requeue to the end of queue if we are not the only element | |
229 | * on the queue: | |
230 | */ | |
231 | if (p->run_list.prev != p->run_list.next) { | |
232 | requeue_task_rt(rq, p); | |
233 | set_tsk_need_resched(p); | |
234 | } | |
bb44e5d1 IM |
235 | } |
236 | ||
83b699ed SV |
237 | static void set_curr_task_rt(struct rq *rq) |
238 | { | |
239 | struct task_struct *p = rq->curr; | |
240 | ||
241 | p->se.exec_start = rq->clock; | |
242 | } | |
243 | ||
5522d5d5 IM |
244 | const struct sched_class rt_sched_class = { |
245 | .next = &fair_sched_class, | |
bb44e5d1 IM |
246 | .enqueue_task = enqueue_task_rt, |
247 | .dequeue_task = dequeue_task_rt, | |
248 | .yield_task = yield_task_rt, | |
249 | ||
250 | .check_preempt_curr = check_preempt_curr_rt, | |
251 | ||
252 | .pick_next_task = pick_next_task_rt, | |
253 | .put_prev_task = put_prev_task_rt, | |
254 | ||
681f3e68 | 255 | #ifdef CONFIG_SMP |
bb44e5d1 | 256 | .load_balance = load_balance_rt, |
e1d1484f | 257 | .move_one_task = move_one_task_rt, |
681f3e68 | 258 | #endif |
bb44e5d1 | 259 | |
83b699ed | 260 | .set_curr_task = set_curr_task_rt, |
bb44e5d1 | 261 | .task_tick = task_tick_rt, |
bb44e5d1 | 262 | }; |