| 1 | /* |
| 2 | * Real-Time Scheduling Class (mapped to the SCHED_FIFO and SCHED_RR |
| 3 | * policies) |
| 4 | */ |
| 5 | |
| 6 | #include "sched.h" |
| 7 | |
| 8 | #include <linux/slab.h> |
| 9 | #include <linux/irq_work.h> |
| 10 | |
| 11 | int sched_rr_timeslice = RR_TIMESLICE; |
| 12 | |
| 13 | static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun); |
| 14 | |
| 15 | struct rt_bandwidth def_rt_bandwidth; |
| 16 | |
| 17 | static enum hrtimer_restart sched_rt_period_timer(struct hrtimer *timer) |
| 18 | { |
| 19 | struct rt_bandwidth *rt_b = |
| 20 | container_of(timer, struct rt_bandwidth, rt_period_timer); |
| 21 | int idle = 0; |
| 22 | int overrun; |
| 23 | |
| 24 | raw_spin_lock(&rt_b->rt_runtime_lock); |
| 25 | for (;;) { |
| 26 | overrun = hrtimer_forward_now(timer, rt_b->rt_period); |
| 27 | if (!overrun) |
| 28 | break; |
| 29 | |
| 30 | raw_spin_unlock(&rt_b->rt_runtime_lock); |
| 31 | idle = do_sched_rt_period_timer(rt_b, overrun); |
| 32 | raw_spin_lock(&rt_b->rt_runtime_lock); |
| 33 | } |
| 34 | if (idle) |
| 35 | rt_b->rt_period_active = 0; |
| 36 | raw_spin_unlock(&rt_b->rt_runtime_lock); |
| 37 | |
| 38 | return idle ? HRTIMER_NORESTART : HRTIMER_RESTART; |
| 39 | } |
| 40 | |
| 41 | void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime) |
| 42 | { |
| 43 | rt_b->rt_period = ns_to_ktime(period); |
| 44 | rt_b->rt_runtime = runtime; |
| 45 | |
| 46 | raw_spin_lock_init(&rt_b->rt_runtime_lock); |
| 47 | |
| 48 | hrtimer_init(&rt_b->rt_period_timer, |
| 49 | CLOCK_MONOTONIC, HRTIMER_MODE_REL); |
| 50 | rt_b->rt_period_timer.function = sched_rt_period_timer; |
| 51 | } |
| 52 | |
| 53 | static void start_rt_bandwidth(struct rt_bandwidth *rt_b) |
| 54 | { |
| 55 | if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF) |
| 56 | return; |
| 57 | |
| 58 | raw_spin_lock(&rt_b->rt_runtime_lock); |
| 59 | if (!rt_b->rt_period_active) { |
| 60 | rt_b->rt_period_active = 1; |
| 61 | /* |
| 62 | * SCHED_DEADLINE updates the bandwidth, as a run away |
| 63 | * RT task with a DL task could hog a CPU. But DL does |
| 64 | * not reset the period. If a deadline task was running |
| 65 | * without an RT task running, it can cause RT tasks to |
| 66 | * throttle when they start up. Kick the timer right away |
| 67 | * to update the period. |
| 68 | */ |
| 69 | hrtimer_forward_now(&rt_b->rt_period_timer, ns_to_ktime(0)); |
| 70 | hrtimer_start_expires(&rt_b->rt_period_timer, HRTIMER_MODE_ABS_PINNED); |
| 71 | } |
| 72 | raw_spin_unlock(&rt_b->rt_runtime_lock); |
| 73 | } |
| 74 | |
| 75 | #if defined(CONFIG_SMP) && defined(HAVE_RT_PUSH_IPI) |
| 76 | static void push_irq_work_func(struct irq_work *work); |
| 77 | #endif |
| 78 | |
| 79 | void init_rt_rq(struct rt_rq *rt_rq) |
| 80 | { |
| 81 | struct rt_prio_array *array; |
| 82 | int i; |
| 83 | |
| 84 | array = &rt_rq->active; |
| 85 | for (i = 0; i < MAX_RT_PRIO; i++) { |
| 86 | INIT_LIST_HEAD(array->queue + i); |
| 87 | __clear_bit(i, array->bitmap); |
| 88 | } |
| 89 | /* delimiter for bitsearch: */ |
| 90 | __set_bit(MAX_RT_PRIO, array->bitmap); |
| 91 | |
| 92 | #if defined CONFIG_SMP |
| 93 | rt_rq->highest_prio.curr = MAX_RT_PRIO; |
| 94 | rt_rq->highest_prio.next = MAX_RT_PRIO; |
| 95 | rt_rq->rt_nr_migratory = 0; |
| 96 | rt_rq->overloaded = 0; |
| 97 | plist_head_init(&rt_rq->pushable_tasks); |
| 98 | |
| 99 | #ifdef HAVE_RT_PUSH_IPI |
| 100 | rt_rq->push_flags = 0; |
| 101 | rt_rq->push_cpu = nr_cpu_ids; |
| 102 | raw_spin_lock_init(&rt_rq->push_lock); |
| 103 | init_irq_work(&rt_rq->push_work, push_irq_work_func); |
| 104 | #endif |
| 105 | #endif /* CONFIG_SMP */ |
| 106 | /* We start is dequeued state, because no RT tasks are queued */ |
| 107 | rt_rq->rt_queued = 0; |
| 108 | |
| 109 | rt_rq->rt_time = 0; |
| 110 | rt_rq->rt_throttled = 0; |
| 111 | rt_rq->rt_runtime = 0; |
| 112 | raw_spin_lock_init(&rt_rq->rt_runtime_lock); |
| 113 | } |
| 114 | |
| 115 | #ifdef CONFIG_RT_GROUP_SCHED |
| 116 | static void destroy_rt_bandwidth(struct rt_bandwidth *rt_b) |
| 117 | { |
| 118 | hrtimer_cancel(&rt_b->rt_period_timer); |
| 119 | } |
| 120 | |
| 121 | #define rt_entity_is_task(rt_se) (!(rt_se)->my_q) |
| 122 | |
| 123 | static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se) |
| 124 | { |
| 125 | #ifdef CONFIG_SCHED_DEBUG |
| 126 | WARN_ON_ONCE(!rt_entity_is_task(rt_se)); |
| 127 | #endif |
| 128 | return container_of(rt_se, struct task_struct, rt); |
| 129 | } |
| 130 | |
| 131 | static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq) |
| 132 | { |
| 133 | return rt_rq->rq; |
| 134 | } |
| 135 | |
| 136 | static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se) |
| 137 | { |
| 138 | return rt_se->rt_rq; |
| 139 | } |
| 140 | |
| 141 | static inline struct rq *rq_of_rt_se(struct sched_rt_entity *rt_se) |
| 142 | { |
| 143 | struct rt_rq *rt_rq = rt_se->rt_rq; |
| 144 | |
| 145 | return rt_rq->rq; |
| 146 | } |
| 147 | |
| 148 | void free_rt_sched_group(struct task_group *tg) |
| 149 | { |
| 150 | int i; |
| 151 | |
| 152 | if (tg->rt_se) |
| 153 | destroy_rt_bandwidth(&tg->rt_bandwidth); |
| 154 | |
| 155 | for_each_possible_cpu(i) { |
| 156 | if (tg->rt_rq) |
| 157 | kfree(tg->rt_rq[i]); |
| 158 | if (tg->rt_se) |
| 159 | kfree(tg->rt_se[i]); |
| 160 | } |
| 161 | |
| 162 | kfree(tg->rt_rq); |
| 163 | kfree(tg->rt_se); |
| 164 | } |
| 165 | |
| 166 | void init_tg_rt_entry(struct task_group *tg, struct rt_rq *rt_rq, |
| 167 | struct sched_rt_entity *rt_se, int cpu, |
| 168 | struct sched_rt_entity *parent) |
| 169 | { |
| 170 | struct rq *rq = cpu_rq(cpu); |
| 171 | |
| 172 | rt_rq->highest_prio.curr = MAX_RT_PRIO; |
| 173 | rt_rq->rt_nr_boosted = 0; |
| 174 | rt_rq->rq = rq; |
| 175 | rt_rq->tg = tg; |
| 176 | |
| 177 | tg->rt_rq[cpu] = rt_rq; |
| 178 | tg->rt_se[cpu] = rt_se; |
| 179 | |
| 180 | if (!rt_se) |
| 181 | return; |
| 182 | |
| 183 | if (!parent) |
| 184 | rt_se->rt_rq = &rq->rt; |
| 185 | else |
| 186 | rt_se->rt_rq = parent->my_q; |
| 187 | |
| 188 | rt_se->my_q = rt_rq; |
| 189 | rt_se->parent = parent; |
| 190 | INIT_LIST_HEAD(&rt_se->run_list); |
| 191 | } |
| 192 | |
| 193 | int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent) |
| 194 | { |
| 195 | struct rt_rq *rt_rq; |
| 196 | struct sched_rt_entity *rt_se; |
| 197 | int i; |
| 198 | |
| 199 | tg->rt_rq = kzalloc(sizeof(rt_rq) * nr_cpu_ids, GFP_KERNEL); |
| 200 | if (!tg->rt_rq) |
| 201 | goto err; |
| 202 | tg->rt_se = kzalloc(sizeof(rt_se) * nr_cpu_ids, GFP_KERNEL); |
| 203 | if (!tg->rt_se) |
| 204 | goto err; |
| 205 | |
| 206 | init_rt_bandwidth(&tg->rt_bandwidth, |
| 207 | ktime_to_ns(def_rt_bandwidth.rt_period), 0); |
| 208 | |
| 209 | for_each_possible_cpu(i) { |
| 210 | rt_rq = kzalloc_node(sizeof(struct rt_rq), |
| 211 | GFP_KERNEL, cpu_to_node(i)); |
| 212 | if (!rt_rq) |
| 213 | goto err; |
| 214 | |
| 215 | rt_se = kzalloc_node(sizeof(struct sched_rt_entity), |
| 216 | GFP_KERNEL, cpu_to_node(i)); |
| 217 | if (!rt_se) |
| 218 | goto err_free_rq; |
| 219 | |
| 220 | init_rt_rq(rt_rq); |
| 221 | rt_rq->rt_runtime = tg->rt_bandwidth.rt_runtime; |
| 222 | init_tg_rt_entry(tg, rt_rq, rt_se, i, parent->rt_se[i]); |
| 223 | } |
| 224 | |
| 225 | return 1; |
| 226 | |
| 227 | err_free_rq: |
| 228 | kfree(rt_rq); |
| 229 | err: |
| 230 | return 0; |
| 231 | } |
| 232 | |
| 233 | #else /* CONFIG_RT_GROUP_SCHED */ |
| 234 | |
| 235 | #define rt_entity_is_task(rt_se) (1) |
| 236 | |
| 237 | static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se) |
| 238 | { |
| 239 | return container_of(rt_se, struct task_struct, rt); |
| 240 | } |
| 241 | |
| 242 | static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq) |
| 243 | { |
| 244 | return container_of(rt_rq, struct rq, rt); |
| 245 | } |
| 246 | |
| 247 | static inline struct rq *rq_of_rt_se(struct sched_rt_entity *rt_se) |
| 248 | { |
| 249 | struct task_struct *p = rt_task_of(rt_se); |
| 250 | |
| 251 | return task_rq(p); |
| 252 | } |
| 253 | |
| 254 | static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se) |
| 255 | { |
| 256 | struct rq *rq = rq_of_rt_se(rt_se); |
| 257 | |
| 258 | return &rq->rt; |
| 259 | } |
| 260 | |
| 261 | void free_rt_sched_group(struct task_group *tg) { } |
| 262 | |
| 263 | int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent) |
| 264 | { |
| 265 | return 1; |
| 266 | } |
| 267 | #endif /* CONFIG_RT_GROUP_SCHED */ |
| 268 | |
| 269 | #ifdef CONFIG_SMP |
| 270 | |
| 271 | static void pull_rt_task(struct rq *this_rq); |
| 272 | |
| 273 | static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev) |
| 274 | { |
| 275 | /* Try to pull RT tasks here if we lower this rq's prio */ |
| 276 | return rq->rt.highest_prio.curr > prev->prio; |
| 277 | } |
| 278 | |
| 279 | static inline int rt_overloaded(struct rq *rq) |
| 280 | { |
| 281 | return atomic_read(&rq->rd->rto_count); |
| 282 | } |
| 283 | |
| 284 | static inline void rt_set_overload(struct rq *rq) |
| 285 | { |
| 286 | if (!rq->online) |
| 287 | return; |
| 288 | |
| 289 | cpumask_set_cpu(rq->cpu, rq->rd->rto_mask); |
| 290 | /* |
| 291 | * Make sure the mask is visible before we set |
| 292 | * the overload count. That is checked to determine |
| 293 | * if we should look at the mask. It would be a shame |
| 294 | * if we looked at the mask, but the mask was not |
| 295 | * updated yet. |
| 296 | * |
| 297 | * Matched by the barrier in pull_rt_task(). |
| 298 | */ |
| 299 | smp_wmb(); |
| 300 | atomic_inc(&rq->rd->rto_count); |
| 301 | } |
| 302 | |
| 303 | static inline void rt_clear_overload(struct rq *rq) |
| 304 | { |
| 305 | if (!rq->online) |
| 306 | return; |
| 307 | |
| 308 | /* the order here really doesn't matter */ |
| 309 | atomic_dec(&rq->rd->rto_count); |
| 310 | cpumask_clear_cpu(rq->cpu, rq->rd->rto_mask); |
| 311 | } |
| 312 | |
| 313 | static void update_rt_migration(struct rt_rq *rt_rq) |
| 314 | { |
| 315 | if (rt_rq->rt_nr_migratory && rt_rq->rt_nr_total > 1) { |
| 316 | if (!rt_rq->overloaded) { |
| 317 | rt_set_overload(rq_of_rt_rq(rt_rq)); |
| 318 | rt_rq->overloaded = 1; |
| 319 | } |
| 320 | } else if (rt_rq->overloaded) { |
| 321 | rt_clear_overload(rq_of_rt_rq(rt_rq)); |
| 322 | rt_rq->overloaded = 0; |
| 323 | } |
| 324 | } |
| 325 | |
| 326 | static void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) |
| 327 | { |
| 328 | struct task_struct *p; |
| 329 | |
| 330 | if (!rt_entity_is_task(rt_se)) |
| 331 | return; |
| 332 | |
| 333 | p = rt_task_of(rt_se); |
| 334 | rt_rq = &rq_of_rt_rq(rt_rq)->rt; |
| 335 | |
| 336 | rt_rq->rt_nr_total++; |
| 337 | if (p->nr_cpus_allowed > 1) |
| 338 | rt_rq->rt_nr_migratory++; |
| 339 | |
| 340 | update_rt_migration(rt_rq); |
| 341 | } |
| 342 | |
| 343 | static void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) |
| 344 | { |
| 345 | struct task_struct *p; |
| 346 | |
| 347 | if (!rt_entity_is_task(rt_se)) |
| 348 | return; |
| 349 | |
| 350 | p = rt_task_of(rt_se); |
| 351 | rt_rq = &rq_of_rt_rq(rt_rq)->rt; |
| 352 | |
| 353 | rt_rq->rt_nr_total--; |
| 354 | if (p->nr_cpus_allowed > 1) |
| 355 | rt_rq->rt_nr_migratory--; |
| 356 | |
| 357 | update_rt_migration(rt_rq); |
| 358 | } |
| 359 | |
| 360 | static inline int has_pushable_tasks(struct rq *rq) |
| 361 | { |
| 362 | return !plist_head_empty(&rq->rt.pushable_tasks); |
| 363 | } |
| 364 | |
| 365 | static DEFINE_PER_CPU(struct callback_head, rt_push_head); |
| 366 | static DEFINE_PER_CPU(struct callback_head, rt_pull_head); |
| 367 | |
| 368 | static void push_rt_tasks(struct rq *); |
| 369 | static void pull_rt_task(struct rq *); |
| 370 | |
| 371 | static inline void queue_push_tasks(struct rq *rq) |
| 372 | { |
| 373 | if (!has_pushable_tasks(rq)) |
| 374 | return; |
| 375 | |
| 376 | queue_balance_callback(rq, &per_cpu(rt_push_head, rq->cpu), push_rt_tasks); |
| 377 | } |
| 378 | |
| 379 | static inline void queue_pull_task(struct rq *rq) |
| 380 | { |
| 381 | queue_balance_callback(rq, &per_cpu(rt_pull_head, rq->cpu), pull_rt_task); |
| 382 | } |
| 383 | |
| 384 | static void enqueue_pushable_task(struct rq *rq, struct task_struct *p) |
| 385 | { |
| 386 | plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks); |
| 387 | plist_node_init(&p->pushable_tasks, p->prio); |
| 388 | plist_add(&p->pushable_tasks, &rq->rt.pushable_tasks); |
| 389 | |
| 390 | /* Update the highest prio pushable task */ |
| 391 | if (p->prio < rq->rt.highest_prio.next) |
| 392 | rq->rt.highest_prio.next = p->prio; |
| 393 | } |
| 394 | |
| 395 | static void dequeue_pushable_task(struct rq *rq, struct task_struct *p) |
| 396 | { |
| 397 | plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks); |
| 398 | |
| 399 | /* Update the new highest prio pushable task */ |
| 400 | if (has_pushable_tasks(rq)) { |
| 401 | p = plist_first_entry(&rq->rt.pushable_tasks, |
| 402 | struct task_struct, pushable_tasks); |
| 403 | rq->rt.highest_prio.next = p->prio; |
| 404 | } else |
| 405 | rq->rt.highest_prio.next = MAX_RT_PRIO; |
| 406 | } |
| 407 | |
| 408 | #else |
| 409 | |
| 410 | static inline void enqueue_pushable_task(struct rq *rq, struct task_struct *p) |
| 411 | { |
| 412 | } |
| 413 | |
| 414 | static inline void dequeue_pushable_task(struct rq *rq, struct task_struct *p) |
| 415 | { |
| 416 | } |
| 417 | |
| 418 | static inline |
| 419 | void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) |
| 420 | { |
| 421 | } |
| 422 | |
| 423 | static inline |
| 424 | void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) |
| 425 | { |
| 426 | } |
| 427 | |
| 428 | static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev) |
| 429 | { |
| 430 | return false; |
| 431 | } |
| 432 | |
| 433 | static inline void pull_rt_task(struct rq *this_rq) |
| 434 | { |
| 435 | } |
| 436 | |
| 437 | static inline void queue_push_tasks(struct rq *rq) |
| 438 | { |
| 439 | } |
| 440 | #endif /* CONFIG_SMP */ |
| 441 | |
| 442 | static void enqueue_top_rt_rq(struct rt_rq *rt_rq); |
| 443 | static void dequeue_top_rt_rq(struct rt_rq *rt_rq); |
| 444 | |
| 445 | static inline int on_rt_rq(struct sched_rt_entity *rt_se) |
| 446 | { |
| 447 | return rt_se->on_rq; |
| 448 | } |
| 449 | |
| 450 | #ifdef CONFIG_RT_GROUP_SCHED |
| 451 | |
| 452 | static inline u64 sched_rt_runtime(struct rt_rq *rt_rq) |
| 453 | { |
| 454 | if (!rt_rq->tg) |
| 455 | return RUNTIME_INF; |
| 456 | |
| 457 | return rt_rq->rt_runtime; |
| 458 | } |
| 459 | |
| 460 | static inline u64 sched_rt_period(struct rt_rq *rt_rq) |
| 461 | { |
| 462 | return ktime_to_ns(rt_rq->tg->rt_bandwidth.rt_period); |
| 463 | } |
| 464 | |
| 465 | typedef struct task_group *rt_rq_iter_t; |
| 466 | |
| 467 | static inline struct task_group *next_task_group(struct task_group *tg) |
| 468 | { |
| 469 | do { |
| 470 | tg = list_entry_rcu(tg->list.next, |
| 471 | typeof(struct task_group), list); |
| 472 | } while (&tg->list != &task_groups && task_group_is_autogroup(tg)); |
| 473 | |
| 474 | if (&tg->list == &task_groups) |
| 475 | tg = NULL; |
| 476 | |
| 477 | return tg; |
| 478 | } |
| 479 | |
| 480 | #define for_each_rt_rq(rt_rq, iter, rq) \ |
| 481 | for (iter = container_of(&task_groups, typeof(*iter), list); \ |
| 482 | (iter = next_task_group(iter)) && \ |
| 483 | (rt_rq = iter->rt_rq[cpu_of(rq)]);) |
| 484 | |
| 485 | #define for_each_sched_rt_entity(rt_se) \ |
| 486 | for (; rt_se; rt_se = rt_se->parent) |
| 487 | |
| 488 | static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se) |
| 489 | { |
| 490 | return rt_se->my_q; |
| 491 | } |
| 492 | |
| 493 | static void enqueue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags); |
| 494 | static void dequeue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags); |
| 495 | |
| 496 | static void sched_rt_rq_enqueue(struct rt_rq *rt_rq) |
| 497 | { |
| 498 | struct task_struct *curr = rq_of_rt_rq(rt_rq)->curr; |
| 499 | struct rq *rq = rq_of_rt_rq(rt_rq); |
| 500 | struct sched_rt_entity *rt_se; |
| 501 | |
| 502 | int cpu = cpu_of(rq); |
| 503 | |
| 504 | rt_se = rt_rq->tg->rt_se[cpu]; |
| 505 | |
| 506 | if (rt_rq->rt_nr_running) { |
| 507 | if (!rt_se) |
| 508 | enqueue_top_rt_rq(rt_rq); |
| 509 | else if (!on_rt_rq(rt_se)) |
| 510 | enqueue_rt_entity(rt_se, 0); |
| 511 | |
| 512 | if (rt_rq->highest_prio.curr < curr->prio) |
| 513 | resched_curr(rq); |
| 514 | } |
| 515 | } |
| 516 | |
| 517 | static void sched_rt_rq_dequeue(struct rt_rq *rt_rq) |
| 518 | { |
| 519 | struct sched_rt_entity *rt_se; |
| 520 | int cpu = cpu_of(rq_of_rt_rq(rt_rq)); |
| 521 | |
| 522 | rt_se = rt_rq->tg->rt_se[cpu]; |
| 523 | |
| 524 | if (!rt_se) |
| 525 | dequeue_top_rt_rq(rt_rq); |
| 526 | else if (on_rt_rq(rt_se)) |
| 527 | dequeue_rt_entity(rt_se, 0); |
| 528 | } |
| 529 | |
| 530 | static inline int rt_rq_throttled(struct rt_rq *rt_rq) |
| 531 | { |
| 532 | return rt_rq->rt_throttled && !rt_rq->rt_nr_boosted; |
| 533 | } |
| 534 | |
| 535 | static int rt_se_boosted(struct sched_rt_entity *rt_se) |
| 536 | { |
| 537 | struct rt_rq *rt_rq = group_rt_rq(rt_se); |
| 538 | struct task_struct *p; |
| 539 | |
| 540 | if (rt_rq) |
| 541 | return !!rt_rq->rt_nr_boosted; |
| 542 | |
| 543 | p = rt_task_of(rt_se); |
| 544 | return p->prio != p->normal_prio; |
| 545 | } |
| 546 | |
| 547 | #ifdef CONFIG_SMP |
| 548 | static inline const struct cpumask *sched_rt_period_mask(void) |
| 549 | { |
| 550 | return this_rq()->rd->span; |
| 551 | } |
| 552 | #else |
| 553 | static inline const struct cpumask *sched_rt_period_mask(void) |
| 554 | { |
| 555 | return cpu_online_mask; |
| 556 | } |
| 557 | #endif |
| 558 | |
| 559 | static inline |
| 560 | struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu) |
| 561 | { |
| 562 | return container_of(rt_b, struct task_group, rt_bandwidth)->rt_rq[cpu]; |
| 563 | } |
| 564 | |
| 565 | static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq) |
| 566 | { |
| 567 | return &rt_rq->tg->rt_bandwidth; |
| 568 | } |
| 569 | |
| 570 | #else /* !CONFIG_RT_GROUP_SCHED */ |
| 571 | |
| 572 | static inline u64 sched_rt_runtime(struct rt_rq *rt_rq) |
| 573 | { |
| 574 | return rt_rq->rt_runtime; |
| 575 | } |
| 576 | |
| 577 | static inline u64 sched_rt_period(struct rt_rq *rt_rq) |
| 578 | { |
| 579 | return ktime_to_ns(def_rt_bandwidth.rt_period); |
| 580 | } |
| 581 | |
| 582 | typedef struct rt_rq *rt_rq_iter_t; |
| 583 | |
| 584 | #define for_each_rt_rq(rt_rq, iter, rq) \ |
| 585 | for ((void) iter, rt_rq = &rq->rt; rt_rq; rt_rq = NULL) |
| 586 | |
| 587 | #define for_each_sched_rt_entity(rt_se) \ |
| 588 | for (; rt_se; rt_se = NULL) |
| 589 | |
| 590 | static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se) |
| 591 | { |
| 592 | return NULL; |
| 593 | } |
| 594 | |
| 595 | static inline void sched_rt_rq_enqueue(struct rt_rq *rt_rq) |
| 596 | { |
| 597 | struct rq *rq = rq_of_rt_rq(rt_rq); |
| 598 | |
| 599 | if (!rt_rq->rt_nr_running) |
| 600 | return; |
| 601 | |
| 602 | enqueue_top_rt_rq(rt_rq); |
| 603 | resched_curr(rq); |
| 604 | } |
| 605 | |
| 606 | static inline void sched_rt_rq_dequeue(struct rt_rq *rt_rq) |
| 607 | { |
| 608 | dequeue_top_rt_rq(rt_rq); |
| 609 | } |
| 610 | |
| 611 | static inline int rt_rq_throttled(struct rt_rq *rt_rq) |
| 612 | { |
| 613 | return rt_rq->rt_throttled; |
| 614 | } |
| 615 | |
| 616 | static inline const struct cpumask *sched_rt_period_mask(void) |
| 617 | { |
| 618 | return cpu_online_mask; |
| 619 | } |
| 620 | |
| 621 | static inline |
| 622 | struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu) |
| 623 | { |
| 624 | return &cpu_rq(cpu)->rt; |
| 625 | } |
| 626 | |
| 627 | static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq) |
| 628 | { |
| 629 | return &def_rt_bandwidth; |
| 630 | } |
| 631 | |
| 632 | #endif /* CONFIG_RT_GROUP_SCHED */ |
| 633 | |
| 634 | bool sched_rt_bandwidth_account(struct rt_rq *rt_rq) |
| 635 | { |
| 636 | struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq); |
| 637 | |
| 638 | return (hrtimer_active(&rt_b->rt_period_timer) || |
| 639 | rt_rq->rt_time < rt_b->rt_runtime); |
| 640 | } |
| 641 | |
| 642 | #ifdef CONFIG_SMP |
| 643 | /* |
| 644 | * We ran out of runtime, see if we can borrow some from our neighbours. |
| 645 | */ |
| 646 | static void do_balance_runtime(struct rt_rq *rt_rq) |
| 647 | { |
| 648 | struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq); |
| 649 | struct root_domain *rd = rq_of_rt_rq(rt_rq)->rd; |
| 650 | int i, weight; |
| 651 | u64 rt_period; |
| 652 | |
| 653 | weight = cpumask_weight(rd->span); |
| 654 | |
| 655 | raw_spin_lock(&rt_b->rt_runtime_lock); |
| 656 | rt_period = ktime_to_ns(rt_b->rt_period); |
| 657 | for_each_cpu(i, rd->span) { |
| 658 | struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i); |
| 659 | s64 diff; |
| 660 | |
| 661 | if (iter == rt_rq) |
| 662 | continue; |
| 663 | |
| 664 | raw_spin_lock(&iter->rt_runtime_lock); |
| 665 | /* |
| 666 | * Either all rqs have inf runtime and there's nothing to steal |
| 667 | * or __disable_runtime() below sets a specific rq to inf to |
| 668 | * indicate its been disabled and disalow stealing. |
| 669 | */ |
| 670 | if (iter->rt_runtime == RUNTIME_INF) |
| 671 | goto next; |
| 672 | |
| 673 | /* |
| 674 | * From runqueues with spare time, take 1/n part of their |
| 675 | * spare time, but no more than our period. |
| 676 | */ |
| 677 | diff = iter->rt_runtime - iter->rt_time; |
| 678 | if (diff > 0) { |
| 679 | diff = div_u64((u64)diff, weight); |
| 680 | if (rt_rq->rt_runtime + diff > rt_period) |
| 681 | diff = rt_period - rt_rq->rt_runtime; |
| 682 | iter->rt_runtime -= diff; |
| 683 | rt_rq->rt_runtime += diff; |
| 684 | if (rt_rq->rt_runtime == rt_period) { |
| 685 | raw_spin_unlock(&iter->rt_runtime_lock); |
| 686 | break; |
| 687 | } |
| 688 | } |
| 689 | next: |
| 690 | raw_spin_unlock(&iter->rt_runtime_lock); |
| 691 | } |
| 692 | raw_spin_unlock(&rt_b->rt_runtime_lock); |
| 693 | } |
| 694 | |
| 695 | /* |
| 696 | * Ensure this RQ takes back all the runtime it lend to its neighbours. |
| 697 | */ |
| 698 | static void __disable_runtime(struct rq *rq) |
| 699 | { |
| 700 | struct root_domain *rd = rq->rd; |
| 701 | rt_rq_iter_t iter; |
| 702 | struct rt_rq *rt_rq; |
| 703 | |
| 704 | if (unlikely(!scheduler_running)) |
| 705 | return; |
| 706 | |
| 707 | for_each_rt_rq(rt_rq, iter, rq) { |
| 708 | struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq); |
| 709 | s64 want; |
| 710 | int i; |
| 711 | |
| 712 | raw_spin_lock(&rt_b->rt_runtime_lock); |
| 713 | raw_spin_lock(&rt_rq->rt_runtime_lock); |
| 714 | /* |
| 715 | * Either we're all inf and nobody needs to borrow, or we're |
| 716 | * already disabled and thus have nothing to do, or we have |
| 717 | * exactly the right amount of runtime to take out. |
| 718 | */ |
| 719 | if (rt_rq->rt_runtime == RUNTIME_INF || |
| 720 | rt_rq->rt_runtime == rt_b->rt_runtime) |
| 721 | goto balanced; |
| 722 | raw_spin_unlock(&rt_rq->rt_runtime_lock); |
| 723 | |
| 724 | /* |
| 725 | * Calculate the difference between what we started out with |
| 726 | * and what we current have, that's the amount of runtime |
| 727 | * we lend and now have to reclaim. |
| 728 | */ |
| 729 | want = rt_b->rt_runtime - rt_rq->rt_runtime; |
| 730 | |
| 731 | /* |
| 732 | * Greedy reclaim, take back as much as we can. |
| 733 | */ |
| 734 | for_each_cpu(i, rd->span) { |
| 735 | struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i); |
| 736 | s64 diff; |
| 737 | |
| 738 | /* |
| 739 | * Can't reclaim from ourselves or disabled runqueues. |
| 740 | */ |
| 741 | if (iter == rt_rq || iter->rt_runtime == RUNTIME_INF) |
| 742 | continue; |
| 743 | |
| 744 | raw_spin_lock(&iter->rt_runtime_lock); |
| 745 | if (want > 0) { |
| 746 | diff = min_t(s64, iter->rt_runtime, want); |
| 747 | iter->rt_runtime -= diff; |
| 748 | want -= diff; |
| 749 | } else { |
| 750 | iter->rt_runtime -= want; |
| 751 | want -= want; |
| 752 | } |
| 753 | raw_spin_unlock(&iter->rt_runtime_lock); |
| 754 | |
| 755 | if (!want) |
| 756 | break; |
| 757 | } |
| 758 | |
| 759 | raw_spin_lock(&rt_rq->rt_runtime_lock); |
| 760 | /* |
| 761 | * We cannot be left wanting - that would mean some runtime |
| 762 | * leaked out of the system. |
| 763 | */ |
| 764 | BUG_ON(want); |
| 765 | balanced: |
| 766 | /* |
| 767 | * Disable all the borrow logic by pretending we have inf |
| 768 | * runtime - in which case borrowing doesn't make sense. |
| 769 | */ |
| 770 | rt_rq->rt_runtime = RUNTIME_INF; |
| 771 | rt_rq->rt_throttled = 0; |
| 772 | raw_spin_unlock(&rt_rq->rt_runtime_lock); |
| 773 | raw_spin_unlock(&rt_b->rt_runtime_lock); |
| 774 | |
| 775 | /* Make rt_rq available for pick_next_task() */ |
| 776 | sched_rt_rq_enqueue(rt_rq); |
| 777 | } |
| 778 | } |
| 779 | |
| 780 | static void __enable_runtime(struct rq *rq) |
| 781 | { |
| 782 | rt_rq_iter_t iter; |
| 783 | struct rt_rq *rt_rq; |
| 784 | |
| 785 | if (unlikely(!scheduler_running)) |
| 786 | return; |
| 787 | |
| 788 | /* |
| 789 | * Reset each runqueue's bandwidth settings |
| 790 | */ |
| 791 | for_each_rt_rq(rt_rq, iter, rq) { |
| 792 | struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq); |
| 793 | |
| 794 | raw_spin_lock(&rt_b->rt_runtime_lock); |
| 795 | raw_spin_lock(&rt_rq->rt_runtime_lock); |
| 796 | rt_rq->rt_runtime = rt_b->rt_runtime; |
| 797 | rt_rq->rt_time = 0; |
| 798 | rt_rq->rt_throttled = 0; |
| 799 | raw_spin_unlock(&rt_rq->rt_runtime_lock); |
| 800 | raw_spin_unlock(&rt_b->rt_runtime_lock); |
| 801 | } |
| 802 | } |
| 803 | |
| 804 | static void balance_runtime(struct rt_rq *rt_rq) |
| 805 | { |
| 806 | if (!sched_feat(RT_RUNTIME_SHARE)) |
| 807 | return; |
| 808 | |
| 809 | if (rt_rq->rt_time > rt_rq->rt_runtime) { |
| 810 | raw_spin_unlock(&rt_rq->rt_runtime_lock); |
| 811 | do_balance_runtime(rt_rq); |
| 812 | raw_spin_lock(&rt_rq->rt_runtime_lock); |
| 813 | } |
| 814 | } |
| 815 | #else /* !CONFIG_SMP */ |
| 816 | static inline void balance_runtime(struct rt_rq *rt_rq) {} |
| 817 | #endif /* CONFIG_SMP */ |
| 818 | |
| 819 | static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun) |
| 820 | { |
| 821 | int i, idle = 1, throttled = 0; |
| 822 | const struct cpumask *span; |
| 823 | |
| 824 | span = sched_rt_period_mask(); |
| 825 | #ifdef CONFIG_RT_GROUP_SCHED |
| 826 | /* |
| 827 | * FIXME: isolated CPUs should really leave the root task group, |
| 828 | * whether they are isolcpus or were isolated via cpusets, lest |
| 829 | * the timer run on a CPU which does not service all runqueues, |
| 830 | * potentially leaving other CPUs indefinitely throttled. If |
| 831 | * isolation is really required, the user will turn the throttle |
| 832 | * off to kill the perturbations it causes anyway. Meanwhile, |
| 833 | * this maintains functionality for boot and/or troubleshooting. |
| 834 | */ |
| 835 | if (rt_b == &root_task_group.rt_bandwidth) |
| 836 | span = cpu_online_mask; |
| 837 | #endif |
| 838 | for_each_cpu(i, span) { |
| 839 | int enqueue = 0; |
| 840 | struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i); |
| 841 | struct rq *rq = rq_of_rt_rq(rt_rq); |
| 842 | |
| 843 | raw_spin_lock(&rq->lock); |
| 844 | if (rt_rq->rt_time) { |
| 845 | u64 runtime; |
| 846 | |
| 847 | raw_spin_lock(&rt_rq->rt_runtime_lock); |
| 848 | if (rt_rq->rt_throttled) |
| 849 | balance_runtime(rt_rq); |
| 850 | runtime = rt_rq->rt_runtime; |
| 851 | rt_rq->rt_time -= min(rt_rq->rt_time, overrun*runtime); |
| 852 | if (rt_rq->rt_throttled && rt_rq->rt_time < runtime) { |
| 853 | rt_rq->rt_throttled = 0; |
| 854 | enqueue = 1; |
| 855 | |
| 856 | /* |
| 857 | * When we're idle and a woken (rt) task is |
| 858 | * throttled check_preempt_curr() will set |
| 859 | * skip_update and the time between the wakeup |
| 860 | * and this unthrottle will get accounted as |
| 861 | * 'runtime'. |
| 862 | */ |
| 863 | if (rt_rq->rt_nr_running && rq->curr == rq->idle) |
| 864 | rq_clock_skip_update(rq, false); |
| 865 | } |
| 866 | if (rt_rq->rt_time || rt_rq->rt_nr_running) |
| 867 | idle = 0; |
| 868 | raw_spin_unlock(&rt_rq->rt_runtime_lock); |
| 869 | } else if (rt_rq->rt_nr_running) { |
| 870 | idle = 0; |
| 871 | if (!rt_rq_throttled(rt_rq)) |
| 872 | enqueue = 1; |
| 873 | } |
| 874 | if (rt_rq->rt_throttled) |
| 875 | throttled = 1; |
| 876 | |
| 877 | if (enqueue) |
| 878 | sched_rt_rq_enqueue(rt_rq); |
| 879 | raw_spin_unlock(&rq->lock); |
| 880 | } |
| 881 | |
| 882 | if (!throttled && (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)) |
| 883 | return 1; |
| 884 | |
| 885 | return idle; |
| 886 | } |
| 887 | |
| 888 | static inline int rt_se_prio(struct sched_rt_entity *rt_se) |
| 889 | { |
| 890 | #ifdef CONFIG_RT_GROUP_SCHED |
| 891 | struct rt_rq *rt_rq = group_rt_rq(rt_se); |
| 892 | |
| 893 | if (rt_rq) |
| 894 | return rt_rq->highest_prio.curr; |
| 895 | #endif |
| 896 | |
| 897 | return rt_task_of(rt_se)->prio; |
| 898 | } |
| 899 | |
| 900 | static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq) |
| 901 | { |
| 902 | u64 runtime = sched_rt_runtime(rt_rq); |
| 903 | |
| 904 | if (rt_rq->rt_throttled) |
| 905 | return rt_rq_throttled(rt_rq); |
| 906 | |
| 907 | if (runtime >= sched_rt_period(rt_rq)) |
| 908 | return 0; |
| 909 | |
| 910 | balance_runtime(rt_rq); |
| 911 | runtime = sched_rt_runtime(rt_rq); |
| 912 | if (runtime == RUNTIME_INF) |
| 913 | return 0; |
| 914 | |
| 915 | if (rt_rq->rt_time > runtime) { |
| 916 | struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq); |
| 917 | |
| 918 | /* |
| 919 | * Don't actually throttle groups that have no runtime assigned |
| 920 | * but accrue some time due to boosting. |
| 921 | */ |
| 922 | if (likely(rt_b->rt_runtime)) { |
| 923 | rt_rq->rt_throttled = 1; |
| 924 | printk_deferred_once("sched: RT throttling activated\n"); |
| 925 | } else { |
| 926 | /* |
| 927 | * In case we did anyway, make it go away, |
| 928 | * replenishment is a joke, since it will replenish us |
| 929 | * with exactly 0 ns. |
| 930 | */ |
| 931 | rt_rq->rt_time = 0; |
| 932 | } |
| 933 | |
| 934 | if (rt_rq_throttled(rt_rq)) { |
| 935 | sched_rt_rq_dequeue(rt_rq); |
| 936 | return 1; |
| 937 | } |
| 938 | } |
| 939 | |
| 940 | return 0; |
| 941 | } |
| 942 | |
| 943 | /* |
| 944 | * Update the current task's runtime statistics. Skip current tasks that |
| 945 | * are not in our scheduling class. |
| 946 | */ |
| 947 | static void update_curr_rt(struct rq *rq) |
| 948 | { |
| 949 | struct task_struct *curr = rq->curr; |
| 950 | struct sched_rt_entity *rt_se = &curr->rt; |
| 951 | u64 delta_exec; |
| 952 | |
| 953 | if (curr->sched_class != &rt_sched_class) |
| 954 | return; |
| 955 | |
| 956 | /* Kick cpufreq (see the comment in linux/cpufreq.h). */ |
| 957 | if (cpu_of(rq) == smp_processor_id()) |
| 958 | cpufreq_trigger_update(rq_clock(rq)); |
| 959 | |
| 960 | delta_exec = rq_clock_task(rq) - curr->se.exec_start; |
| 961 | if (unlikely((s64)delta_exec <= 0)) |
| 962 | return; |
| 963 | |
| 964 | schedstat_set(curr->se.statistics.exec_max, |
| 965 | max(curr->se.statistics.exec_max, delta_exec)); |
| 966 | |
| 967 | curr->se.sum_exec_runtime += delta_exec; |
| 968 | account_group_exec_runtime(curr, delta_exec); |
| 969 | |
| 970 | curr->se.exec_start = rq_clock_task(rq); |
| 971 | cpuacct_charge(curr, delta_exec); |
| 972 | |
| 973 | sched_rt_avg_update(rq, delta_exec); |
| 974 | |
| 975 | if (!rt_bandwidth_enabled()) |
| 976 | return; |
| 977 | |
| 978 | for_each_sched_rt_entity(rt_se) { |
| 979 | struct rt_rq *rt_rq = rt_rq_of_se(rt_se); |
| 980 | |
| 981 | if (sched_rt_runtime(rt_rq) != RUNTIME_INF) { |
| 982 | raw_spin_lock(&rt_rq->rt_runtime_lock); |
| 983 | rt_rq->rt_time += delta_exec; |
| 984 | if (sched_rt_runtime_exceeded(rt_rq)) |
| 985 | resched_curr(rq); |
| 986 | raw_spin_unlock(&rt_rq->rt_runtime_lock); |
| 987 | } |
| 988 | } |
| 989 | } |
| 990 | |
| 991 | static void |
| 992 | dequeue_top_rt_rq(struct rt_rq *rt_rq) |
| 993 | { |
| 994 | struct rq *rq = rq_of_rt_rq(rt_rq); |
| 995 | |
| 996 | BUG_ON(&rq->rt != rt_rq); |
| 997 | |
| 998 | if (!rt_rq->rt_queued) |
| 999 | return; |
| 1000 | |
| 1001 | BUG_ON(!rq->nr_running); |
| 1002 | |
| 1003 | sub_nr_running(rq, rt_rq->rt_nr_running); |
| 1004 | rt_rq->rt_queued = 0; |
| 1005 | } |
| 1006 | |
| 1007 | static void |
| 1008 | enqueue_top_rt_rq(struct rt_rq *rt_rq) |
| 1009 | { |
| 1010 | struct rq *rq = rq_of_rt_rq(rt_rq); |
| 1011 | |
| 1012 | BUG_ON(&rq->rt != rt_rq); |
| 1013 | |
| 1014 | if (rt_rq->rt_queued) |
| 1015 | return; |
| 1016 | if (rt_rq_throttled(rt_rq) || !rt_rq->rt_nr_running) |
| 1017 | return; |
| 1018 | |
| 1019 | add_nr_running(rq, rt_rq->rt_nr_running); |
| 1020 | rt_rq->rt_queued = 1; |
| 1021 | } |
| 1022 | |
| 1023 | #if defined CONFIG_SMP |
| 1024 | |
| 1025 | static void |
| 1026 | inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) |
| 1027 | { |
| 1028 | struct rq *rq = rq_of_rt_rq(rt_rq); |
| 1029 | |
| 1030 | #ifdef CONFIG_RT_GROUP_SCHED |
| 1031 | /* |
| 1032 | * Change rq's cpupri only if rt_rq is the top queue. |
| 1033 | */ |
| 1034 | if (&rq->rt != rt_rq) |
| 1035 | return; |
| 1036 | #endif |
| 1037 | if (rq->online && prio < prev_prio) |
| 1038 | cpupri_set(&rq->rd->cpupri, rq->cpu, prio); |
| 1039 | } |
| 1040 | |
| 1041 | static void |
| 1042 | dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) |
| 1043 | { |
| 1044 | struct rq *rq = rq_of_rt_rq(rt_rq); |
| 1045 | |
| 1046 | #ifdef CONFIG_RT_GROUP_SCHED |
| 1047 | /* |
| 1048 | * Change rq's cpupri only if rt_rq is the top queue. |
| 1049 | */ |
| 1050 | if (&rq->rt != rt_rq) |
| 1051 | return; |
| 1052 | #endif |
| 1053 | if (rq->online && rt_rq->highest_prio.curr != prev_prio) |
| 1054 | cpupri_set(&rq->rd->cpupri, rq->cpu, rt_rq->highest_prio.curr); |
| 1055 | } |
| 1056 | |
| 1057 | #else /* CONFIG_SMP */ |
| 1058 | |
| 1059 | static inline |
| 1060 | void inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {} |
| 1061 | static inline |
| 1062 | void dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {} |
| 1063 | |
| 1064 | #endif /* CONFIG_SMP */ |
| 1065 | |
| 1066 | #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED |
| 1067 | static void |
| 1068 | inc_rt_prio(struct rt_rq *rt_rq, int prio) |
| 1069 | { |
| 1070 | int prev_prio = rt_rq->highest_prio.curr; |
| 1071 | |
| 1072 | if (prio < prev_prio) |
| 1073 | rt_rq->highest_prio.curr = prio; |
| 1074 | |
| 1075 | inc_rt_prio_smp(rt_rq, prio, prev_prio); |
| 1076 | } |
| 1077 | |
| 1078 | static void |
| 1079 | dec_rt_prio(struct rt_rq *rt_rq, int prio) |
| 1080 | { |
| 1081 | int prev_prio = rt_rq->highest_prio.curr; |
| 1082 | |
| 1083 | if (rt_rq->rt_nr_running) { |
| 1084 | |
| 1085 | WARN_ON(prio < prev_prio); |
| 1086 | |
| 1087 | /* |
| 1088 | * This may have been our highest task, and therefore |
| 1089 | * we may have some recomputation to do |
| 1090 | */ |
| 1091 | if (prio == prev_prio) { |
| 1092 | struct rt_prio_array *array = &rt_rq->active; |
| 1093 | |
| 1094 | rt_rq->highest_prio.curr = |
| 1095 | sched_find_first_bit(array->bitmap); |
| 1096 | } |
| 1097 | |
| 1098 | } else |
| 1099 | rt_rq->highest_prio.curr = MAX_RT_PRIO; |
| 1100 | |
| 1101 | dec_rt_prio_smp(rt_rq, prio, prev_prio); |
| 1102 | } |
| 1103 | |
| 1104 | #else |
| 1105 | |
| 1106 | static inline void inc_rt_prio(struct rt_rq *rt_rq, int prio) {} |
| 1107 | static inline void dec_rt_prio(struct rt_rq *rt_rq, int prio) {} |
| 1108 | |
| 1109 | #endif /* CONFIG_SMP || CONFIG_RT_GROUP_SCHED */ |
| 1110 | |
| 1111 | #ifdef CONFIG_RT_GROUP_SCHED |
| 1112 | |
| 1113 | static void |
| 1114 | inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) |
| 1115 | { |
| 1116 | if (rt_se_boosted(rt_se)) |
| 1117 | rt_rq->rt_nr_boosted++; |
| 1118 | |
| 1119 | if (rt_rq->tg) |
| 1120 | start_rt_bandwidth(&rt_rq->tg->rt_bandwidth); |
| 1121 | } |
| 1122 | |
| 1123 | static void |
| 1124 | dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) |
| 1125 | { |
| 1126 | if (rt_se_boosted(rt_se)) |
| 1127 | rt_rq->rt_nr_boosted--; |
| 1128 | |
| 1129 | WARN_ON(!rt_rq->rt_nr_running && rt_rq->rt_nr_boosted); |
| 1130 | } |
| 1131 | |
| 1132 | #else /* CONFIG_RT_GROUP_SCHED */ |
| 1133 | |
| 1134 | static void |
| 1135 | inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) |
| 1136 | { |
| 1137 | start_rt_bandwidth(&def_rt_bandwidth); |
| 1138 | } |
| 1139 | |
| 1140 | static inline |
| 1141 | void dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) {} |
| 1142 | |
| 1143 | #endif /* CONFIG_RT_GROUP_SCHED */ |
| 1144 | |
| 1145 | static inline |
| 1146 | unsigned int rt_se_nr_running(struct sched_rt_entity *rt_se) |
| 1147 | { |
| 1148 | struct rt_rq *group_rq = group_rt_rq(rt_se); |
| 1149 | |
| 1150 | if (group_rq) |
| 1151 | return group_rq->rt_nr_running; |
| 1152 | else |
| 1153 | return 1; |
| 1154 | } |
| 1155 | |
| 1156 | static inline |
| 1157 | unsigned int rt_se_rr_nr_running(struct sched_rt_entity *rt_se) |
| 1158 | { |
| 1159 | struct rt_rq *group_rq = group_rt_rq(rt_se); |
| 1160 | struct task_struct *tsk; |
| 1161 | |
| 1162 | if (group_rq) |
| 1163 | return group_rq->rr_nr_running; |
| 1164 | |
| 1165 | tsk = rt_task_of(rt_se); |
| 1166 | |
| 1167 | return (tsk->policy == SCHED_RR) ? 1 : 0; |
| 1168 | } |
| 1169 | |
| 1170 | static inline |
| 1171 | void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) |
| 1172 | { |
| 1173 | int prio = rt_se_prio(rt_se); |
| 1174 | |
| 1175 | WARN_ON(!rt_prio(prio)); |
| 1176 | rt_rq->rt_nr_running += rt_se_nr_running(rt_se); |
| 1177 | rt_rq->rr_nr_running += rt_se_rr_nr_running(rt_se); |
| 1178 | |
| 1179 | inc_rt_prio(rt_rq, prio); |
| 1180 | inc_rt_migration(rt_se, rt_rq); |
| 1181 | inc_rt_group(rt_se, rt_rq); |
| 1182 | } |
| 1183 | |
| 1184 | static inline |
| 1185 | void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) |
| 1186 | { |
| 1187 | WARN_ON(!rt_prio(rt_se_prio(rt_se))); |
| 1188 | WARN_ON(!rt_rq->rt_nr_running); |
| 1189 | rt_rq->rt_nr_running -= rt_se_nr_running(rt_se); |
| 1190 | rt_rq->rr_nr_running -= rt_se_rr_nr_running(rt_se); |
| 1191 | |
| 1192 | dec_rt_prio(rt_rq, rt_se_prio(rt_se)); |
| 1193 | dec_rt_migration(rt_se, rt_rq); |
| 1194 | dec_rt_group(rt_se, rt_rq); |
| 1195 | } |
| 1196 | |
| 1197 | /* |
| 1198 | * Change rt_se->run_list location unless SAVE && !MOVE |
| 1199 | * |
| 1200 | * assumes ENQUEUE/DEQUEUE flags match |
| 1201 | */ |
| 1202 | static inline bool move_entity(unsigned int flags) |
| 1203 | { |
| 1204 | if ((flags & (DEQUEUE_SAVE | DEQUEUE_MOVE)) == DEQUEUE_SAVE) |
| 1205 | return false; |
| 1206 | |
| 1207 | return true; |
| 1208 | } |
| 1209 | |
| 1210 | static void __delist_rt_entity(struct sched_rt_entity *rt_se, struct rt_prio_array *array) |
| 1211 | { |
| 1212 | list_del_init(&rt_se->run_list); |
| 1213 | |
| 1214 | if (list_empty(array->queue + rt_se_prio(rt_se))) |
| 1215 | __clear_bit(rt_se_prio(rt_se), array->bitmap); |
| 1216 | |
| 1217 | rt_se->on_list = 0; |
| 1218 | } |
| 1219 | |
| 1220 | static void __enqueue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags) |
| 1221 | { |
| 1222 | struct rt_rq *rt_rq = rt_rq_of_se(rt_se); |
| 1223 | struct rt_prio_array *array = &rt_rq->active; |
| 1224 | struct rt_rq *group_rq = group_rt_rq(rt_se); |
| 1225 | struct list_head *queue = array->queue + rt_se_prio(rt_se); |
| 1226 | |
| 1227 | /* |
| 1228 | * Don't enqueue the group if its throttled, or when empty. |
| 1229 | * The latter is a consequence of the former when a child group |
| 1230 | * get throttled and the current group doesn't have any other |
| 1231 | * active members. |
| 1232 | */ |
| 1233 | if (group_rq && (rt_rq_throttled(group_rq) || !group_rq->rt_nr_running)) { |
| 1234 | if (rt_se->on_list) |
| 1235 | __delist_rt_entity(rt_se, array); |
| 1236 | return; |
| 1237 | } |
| 1238 | |
| 1239 | if (move_entity(flags)) { |
| 1240 | WARN_ON_ONCE(rt_se->on_list); |
| 1241 | if (flags & ENQUEUE_HEAD) |
| 1242 | list_add(&rt_se->run_list, queue); |
| 1243 | else |
| 1244 | list_add_tail(&rt_se->run_list, queue); |
| 1245 | |
| 1246 | __set_bit(rt_se_prio(rt_se), array->bitmap); |
| 1247 | rt_se->on_list = 1; |
| 1248 | } |
| 1249 | rt_se->on_rq = 1; |
| 1250 | |
| 1251 | inc_rt_tasks(rt_se, rt_rq); |
| 1252 | } |
| 1253 | |
| 1254 | static void __dequeue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags) |
| 1255 | { |
| 1256 | struct rt_rq *rt_rq = rt_rq_of_se(rt_se); |
| 1257 | struct rt_prio_array *array = &rt_rq->active; |
| 1258 | |
| 1259 | if (move_entity(flags)) { |
| 1260 | WARN_ON_ONCE(!rt_se->on_list); |
| 1261 | __delist_rt_entity(rt_se, array); |
| 1262 | } |
| 1263 | rt_se->on_rq = 0; |
| 1264 | |
| 1265 | dec_rt_tasks(rt_se, rt_rq); |
| 1266 | } |
| 1267 | |
| 1268 | /* |
| 1269 | * Because the prio of an upper entry depends on the lower |
| 1270 | * entries, we must remove entries top - down. |
| 1271 | */ |
| 1272 | static void dequeue_rt_stack(struct sched_rt_entity *rt_se, unsigned int flags) |
| 1273 | { |
| 1274 | struct sched_rt_entity *back = NULL; |
| 1275 | |
| 1276 | for_each_sched_rt_entity(rt_se) { |
| 1277 | rt_se->back = back; |
| 1278 | back = rt_se; |
| 1279 | } |
| 1280 | |
| 1281 | dequeue_top_rt_rq(rt_rq_of_se(back)); |
| 1282 | |
| 1283 | for (rt_se = back; rt_se; rt_se = rt_se->back) { |
| 1284 | if (on_rt_rq(rt_se)) |
| 1285 | __dequeue_rt_entity(rt_se, flags); |
| 1286 | } |
| 1287 | } |
| 1288 | |
| 1289 | static void enqueue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags) |
| 1290 | { |
| 1291 | struct rq *rq = rq_of_rt_se(rt_se); |
| 1292 | |
| 1293 | dequeue_rt_stack(rt_se, flags); |
| 1294 | for_each_sched_rt_entity(rt_se) |
| 1295 | __enqueue_rt_entity(rt_se, flags); |
| 1296 | enqueue_top_rt_rq(&rq->rt); |
| 1297 | } |
| 1298 | |
| 1299 | static void dequeue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags) |
| 1300 | { |
| 1301 | struct rq *rq = rq_of_rt_se(rt_se); |
| 1302 | |
| 1303 | dequeue_rt_stack(rt_se, flags); |
| 1304 | |
| 1305 | for_each_sched_rt_entity(rt_se) { |
| 1306 | struct rt_rq *rt_rq = group_rt_rq(rt_se); |
| 1307 | |
| 1308 | if (rt_rq && rt_rq->rt_nr_running) |
| 1309 | __enqueue_rt_entity(rt_se, flags); |
| 1310 | } |
| 1311 | enqueue_top_rt_rq(&rq->rt); |
| 1312 | } |
| 1313 | |
| 1314 | /* |
| 1315 | * Adding/removing a task to/from a priority array: |
| 1316 | */ |
| 1317 | static void |
| 1318 | enqueue_task_rt(struct rq *rq, struct task_struct *p, int flags) |
| 1319 | { |
| 1320 | struct sched_rt_entity *rt_se = &p->rt; |
| 1321 | |
| 1322 | if (flags & ENQUEUE_WAKEUP) |
| 1323 | rt_se->timeout = 0; |
| 1324 | |
| 1325 | enqueue_rt_entity(rt_se, flags); |
| 1326 | |
| 1327 | if (!task_current(rq, p) && p->nr_cpus_allowed > 1) |
| 1328 | enqueue_pushable_task(rq, p); |
| 1329 | } |
| 1330 | |
| 1331 | static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags) |
| 1332 | { |
| 1333 | struct sched_rt_entity *rt_se = &p->rt; |
| 1334 | |
| 1335 | update_curr_rt(rq); |
| 1336 | dequeue_rt_entity(rt_se, flags); |
| 1337 | |
| 1338 | dequeue_pushable_task(rq, p); |
| 1339 | } |
| 1340 | |
| 1341 | /* |
| 1342 | * Put task to the head or the end of the run list without the overhead of |
| 1343 | * dequeue followed by enqueue. |
| 1344 | */ |
| 1345 | static void |
| 1346 | requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se, int head) |
| 1347 | { |
| 1348 | if (on_rt_rq(rt_se)) { |
| 1349 | struct rt_prio_array *array = &rt_rq->active; |
| 1350 | struct list_head *queue = array->queue + rt_se_prio(rt_se); |
| 1351 | |
| 1352 | if (head) |
| 1353 | list_move(&rt_se->run_list, queue); |
| 1354 | else |
| 1355 | list_move_tail(&rt_se->run_list, queue); |
| 1356 | } |
| 1357 | } |
| 1358 | |
| 1359 | static void requeue_task_rt(struct rq *rq, struct task_struct *p, int head) |
| 1360 | { |
| 1361 | struct sched_rt_entity *rt_se = &p->rt; |
| 1362 | struct rt_rq *rt_rq; |
| 1363 | |
| 1364 | for_each_sched_rt_entity(rt_se) { |
| 1365 | rt_rq = rt_rq_of_se(rt_se); |
| 1366 | requeue_rt_entity(rt_rq, rt_se, head); |
| 1367 | } |
| 1368 | } |
| 1369 | |
| 1370 | static void yield_task_rt(struct rq *rq) |
| 1371 | { |
| 1372 | requeue_task_rt(rq, rq->curr, 0); |
| 1373 | } |
| 1374 | |
| 1375 | #ifdef CONFIG_SMP |
| 1376 | static int find_lowest_rq(struct task_struct *task); |
| 1377 | |
| 1378 | static int |
| 1379 | select_task_rq_rt(struct task_struct *p, int cpu, int sd_flag, int flags) |
| 1380 | { |
| 1381 | struct task_struct *curr; |
| 1382 | struct rq *rq; |
| 1383 | |
| 1384 | /* For anything but wake ups, just return the task_cpu */ |
| 1385 | if (sd_flag != SD_BALANCE_WAKE && sd_flag != SD_BALANCE_FORK) |
| 1386 | goto out; |
| 1387 | |
| 1388 | rq = cpu_rq(cpu); |
| 1389 | |
| 1390 | rcu_read_lock(); |
| 1391 | curr = READ_ONCE(rq->curr); /* unlocked access */ |
| 1392 | |
| 1393 | /* |
| 1394 | * If the current task on @p's runqueue is an RT task, then |
| 1395 | * try to see if we can wake this RT task up on another |
| 1396 | * runqueue. Otherwise simply start this RT task |
| 1397 | * on its current runqueue. |
| 1398 | * |
| 1399 | * We want to avoid overloading runqueues. If the woken |
| 1400 | * task is a higher priority, then it will stay on this CPU |
| 1401 | * and the lower prio task should be moved to another CPU. |
| 1402 | * Even though this will probably make the lower prio task |
| 1403 | * lose its cache, we do not want to bounce a higher task |
| 1404 | * around just because it gave up its CPU, perhaps for a |
| 1405 | * lock? |
| 1406 | * |
| 1407 | * For equal prio tasks, we just let the scheduler sort it out. |
| 1408 | * |
| 1409 | * Otherwise, just let it ride on the affined RQ and the |
| 1410 | * post-schedule router will push the preempted task away |
| 1411 | * |
| 1412 | * This test is optimistic, if we get it wrong the load-balancer |
| 1413 | * will have to sort it out. |
| 1414 | */ |
| 1415 | if (curr && unlikely(rt_task(curr)) && |
| 1416 | (curr->nr_cpus_allowed < 2 || |
| 1417 | curr->prio <= p->prio)) { |
| 1418 | int target = find_lowest_rq(p); |
| 1419 | |
| 1420 | /* |
| 1421 | * Don't bother moving it if the destination CPU is |
| 1422 | * not running a lower priority task. |
| 1423 | */ |
| 1424 | if (target != -1 && |
| 1425 | p->prio < cpu_rq(target)->rt.highest_prio.curr) |
| 1426 | cpu = target; |
| 1427 | } |
| 1428 | rcu_read_unlock(); |
| 1429 | |
| 1430 | out: |
| 1431 | return cpu; |
| 1432 | } |
| 1433 | |
| 1434 | static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p) |
| 1435 | { |
| 1436 | /* |
| 1437 | * Current can't be migrated, useless to reschedule, |
| 1438 | * let's hope p can move out. |
| 1439 | */ |
| 1440 | if (rq->curr->nr_cpus_allowed == 1 || |
| 1441 | !cpupri_find(&rq->rd->cpupri, rq->curr, NULL)) |
| 1442 | return; |
| 1443 | |
| 1444 | /* |
| 1445 | * p is migratable, so let's not schedule it and |
| 1446 | * see if it is pushed or pulled somewhere else. |
| 1447 | */ |
| 1448 | if (p->nr_cpus_allowed != 1 |
| 1449 | && cpupri_find(&rq->rd->cpupri, p, NULL)) |
| 1450 | return; |
| 1451 | |
| 1452 | /* |
| 1453 | * There appears to be other cpus that can accept |
| 1454 | * current and none to run 'p', so lets reschedule |
| 1455 | * to try and push current away: |
| 1456 | */ |
| 1457 | requeue_task_rt(rq, p, 1); |
| 1458 | resched_curr(rq); |
| 1459 | } |
| 1460 | |
| 1461 | #endif /* CONFIG_SMP */ |
| 1462 | |
| 1463 | /* |
| 1464 | * Preempt the current task with a newly woken task if needed: |
| 1465 | */ |
| 1466 | static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p, int flags) |
| 1467 | { |
| 1468 | if (p->prio < rq->curr->prio) { |
| 1469 | resched_curr(rq); |
| 1470 | return; |
| 1471 | } |
| 1472 | |
| 1473 | #ifdef CONFIG_SMP |
| 1474 | /* |
| 1475 | * If: |
| 1476 | * |
| 1477 | * - the newly woken task is of equal priority to the current task |
| 1478 | * - the newly woken task is non-migratable while current is migratable |
| 1479 | * - current will be preempted on the next reschedule |
| 1480 | * |
| 1481 | * we should check to see if current can readily move to a different |
| 1482 | * cpu. If so, we will reschedule to allow the push logic to try |
| 1483 | * to move current somewhere else, making room for our non-migratable |
| 1484 | * task. |
| 1485 | */ |
| 1486 | if (p->prio == rq->curr->prio && !test_tsk_need_resched(rq->curr)) |
| 1487 | check_preempt_equal_prio(rq, p); |
| 1488 | #endif |
| 1489 | } |
| 1490 | |
| 1491 | static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq, |
| 1492 | struct rt_rq *rt_rq) |
| 1493 | { |
| 1494 | struct rt_prio_array *array = &rt_rq->active; |
| 1495 | struct sched_rt_entity *next = NULL; |
| 1496 | struct list_head *queue; |
| 1497 | int idx; |
| 1498 | |
| 1499 | idx = sched_find_first_bit(array->bitmap); |
| 1500 | BUG_ON(idx >= MAX_RT_PRIO); |
| 1501 | |
| 1502 | queue = array->queue + idx; |
| 1503 | next = list_entry(queue->next, struct sched_rt_entity, run_list); |
| 1504 | |
| 1505 | return next; |
| 1506 | } |
| 1507 | |
| 1508 | static struct task_struct *_pick_next_task_rt(struct rq *rq) |
| 1509 | { |
| 1510 | struct sched_rt_entity *rt_se; |
| 1511 | struct task_struct *p; |
| 1512 | struct rt_rq *rt_rq = &rq->rt; |
| 1513 | |
| 1514 | do { |
| 1515 | rt_se = pick_next_rt_entity(rq, rt_rq); |
| 1516 | BUG_ON(!rt_se); |
| 1517 | rt_rq = group_rt_rq(rt_se); |
| 1518 | } while (rt_rq); |
| 1519 | |
| 1520 | p = rt_task_of(rt_se); |
| 1521 | p->se.exec_start = rq_clock_task(rq); |
| 1522 | |
| 1523 | return p; |
| 1524 | } |
| 1525 | |
| 1526 | static struct task_struct * |
| 1527 | pick_next_task_rt(struct rq *rq, struct task_struct *prev) |
| 1528 | { |
| 1529 | struct task_struct *p; |
| 1530 | struct rt_rq *rt_rq = &rq->rt; |
| 1531 | |
| 1532 | if (need_pull_rt_task(rq, prev)) { |
| 1533 | /* |
| 1534 | * This is OK, because current is on_cpu, which avoids it being |
| 1535 | * picked for load-balance and preemption/IRQs are still |
| 1536 | * disabled avoiding further scheduler activity on it and we're |
| 1537 | * being very careful to re-start the picking loop. |
| 1538 | */ |
| 1539 | lockdep_unpin_lock(&rq->lock); |
| 1540 | pull_rt_task(rq); |
| 1541 | lockdep_pin_lock(&rq->lock); |
| 1542 | /* |
| 1543 | * pull_rt_task() can drop (and re-acquire) rq->lock; this |
| 1544 | * means a dl or stop task can slip in, in which case we need |
| 1545 | * to re-start task selection. |
| 1546 | */ |
| 1547 | if (unlikely((rq->stop && task_on_rq_queued(rq->stop)) || |
| 1548 | rq->dl.dl_nr_running)) |
| 1549 | return RETRY_TASK; |
| 1550 | } |
| 1551 | |
| 1552 | /* |
| 1553 | * We may dequeue prev's rt_rq in put_prev_task(). |
| 1554 | * So, we update time before rt_nr_running check. |
| 1555 | */ |
| 1556 | if (prev->sched_class == &rt_sched_class) |
| 1557 | update_curr_rt(rq); |
| 1558 | |
| 1559 | if (!rt_rq->rt_queued) |
| 1560 | return NULL; |
| 1561 | |
| 1562 | put_prev_task(rq, prev); |
| 1563 | |
| 1564 | p = _pick_next_task_rt(rq); |
| 1565 | |
| 1566 | /* The running task is never eligible for pushing */ |
| 1567 | dequeue_pushable_task(rq, p); |
| 1568 | |
| 1569 | queue_push_tasks(rq); |
| 1570 | |
| 1571 | return p; |
| 1572 | } |
| 1573 | |
| 1574 | static void put_prev_task_rt(struct rq *rq, struct task_struct *p) |
| 1575 | { |
| 1576 | update_curr_rt(rq); |
| 1577 | |
| 1578 | /* |
| 1579 | * The previous task needs to be made eligible for pushing |
| 1580 | * if it is still active |
| 1581 | */ |
| 1582 | if (on_rt_rq(&p->rt) && p->nr_cpus_allowed > 1) |
| 1583 | enqueue_pushable_task(rq, p); |
| 1584 | } |
| 1585 | |
| 1586 | #ifdef CONFIG_SMP |
| 1587 | |
| 1588 | /* Only try algorithms three times */ |
| 1589 | #define RT_MAX_TRIES 3 |
| 1590 | |
| 1591 | static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu) |
| 1592 | { |
| 1593 | if (!task_running(rq, p) && |
| 1594 | cpumask_test_cpu(cpu, tsk_cpus_allowed(p))) |
| 1595 | return 1; |
| 1596 | return 0; |
| 1597 | } |
| 1598 | |
| 1599 | /* |
| 1600 | * Return the highest pushable rq's task, which is suitable to be executed |
| 1601 | * on the cpu, NULL otherwise |
| 1602 | */ |
| 1603 | static struct task_struct *pick_highest_pushable_task(struct rq *rq, int cpu) |
| 1604 | { |
| 1605 | struct plist_head *head = &rq->rt.pushable_tasks; |
| 1606 | struct task_struct *p; |
| 1607 | |
| 1608 | if (!has_pushable_tasks(rq)) |
| 1609 | return NULL; |
| 1610 | |
| 1611 | plist_for_each_entry(p, head, pushable_tasks) { |
| 1612 | if (pick_rt_task(rq, p, cpu)) |
| 1613 | return p; |
| 1614 | } |
| 1615 | |
| 1616 | return NULL; |
| 1617 | } |
| 1618 | |
| 1619 | static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask); |
| 1620 | |
| 1621 | static int find_lowest_rq(struct task_struct *task) |
| 1622 | { |
| 1623 | struct sched_domain *sd; |
| 1624 | struct cpumask *lowest_mask = this_cpu_cpumask_var_ptr(local_cpu_mask); |
| 1625 | int this_cpu = smp_processor_id(); |
| 1626 | int cpu = task_cpu(task); |
| 1627 | |
| 1628 | /* Make sure the mask is initialized first */ |
| 1629 | if (unlikely(!lowest_mask)) |
| 1630 | return -1; |
| 1631 | |
| 1632 | if (task->nr_cpus_allowed == 1) |
| 1633 | return -1; /* No other targets possible */ |
| 1634 | |
| 1635 | if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask)) |
| 1636 | return -1; /* No targets found */ |
| 1637 | |
| 1638 | /* |
| 1639 | * At this point we have built a mask of cpus representing the |
| 1640 | * lowest priority tasks in the system. Now we want to elect |
| 1641 | * the best one based on our affinity and topology. |
| 1642 | * |
| 1643 | * We prioritize the last cpu that the task executed on since |
| 1644 | * it is most likely cache-hot in that location. |
| 1645 | */ |
| 1646 | if (cpumask_test_cpu(cpu, lowest_mask)) |
| 1647 | return cpu; |
| 1648 | |
| 1649 | /* |
| 1650 | * Otherwise, we consult the sched_domains span maps to figure |
| 1651 | * out which cpu is logically closest to our hot cache data. |
| 1652 | */ |
| 1653 | if (!cpumask_test_cpu(this_cpu, lowest_mask)) |
| 1654 | this_cpu = -1; /* Skip this_cpu opt if not among lowest */ |
| 1655 | |
| 1656 | rcu_read_lock(); |
| 1657 | for_each_domain(cpu, sd) { |
| 1658 | if (sd->flags & SD_WAKE_AFFINE) { |
| 1659 | int best_cpu; |
| 1660 | |
| 1661 | /* |
| 1662 | * "this_cpu" is cheaper to preempt than a |
| 1663 | * remote processor. |
| 1664 | */ |
| 1665 | if (this_cpu != -1 && |
| 1666 | cpumask_test_cpu(this_cpu, sched_domain_span(sd))) { |
| 1667 | rcu_read_unlock(); |
| 1668 | return this_cpu; |
| 1669 | } |
| 1670 | |
| 1671 | best_cpu = cpumask_first_and(lowest_mask, |
| 1672 | sched_domain_span(sd)); |
| 1673 | if (best_cpu < nr_cpu_ids) { |
| 1674 | rcu_read_unlock(); |
| 1675 | return best_cpu; |
| 1676 | } |
| 1677 | } |
| 1678 | } |
| 1679 | rcu_read_unlock(); |
| 1680 | |
| 1681 | /* |
| 1682 | * And finally, if there were no matches within the domains |
| 1683 | * just give the caller *something* to work with from the compatible |
| 1684 | * locations. |
| 1685 | */ |
| 1686 | if (this_cpu != -1) |
| 1687 | return this_cpu; |
| 1688 | |
| 1689 | cpu = cpumask_any(lowest_mask); |
| 1690 | if (cpu < nr_cpu_ids) |
| 1691 | return cpu; |
| 1692 | return -1; |
| 1693 | } |
| 1694 | |
| 1695 | /* Will lock the rq it finds */ |
| 1696 | static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq) |
| 1697 | { |
| 1698 | struct rq *lowest_rq = NULL; |
| 1699 | int tries; |
| 1700 | int cpu; |
| 1701 | |
| 1702 | for (tries = 0; tries < RT_MAX_TRIES; tries++) { |
| 1703 | cpu = find_lowest_rq(task); |
| 1704 | |
| 1705 | if ((cpu == -1) || (cpu == rq->cpu)) |
| 1706 | break; |
| 1707 | |
| 1708 | lowest_rq = cpu_rq(cpu); |
| 1709 | |
| 1710 | if (lowest_rq->rt.highest_prio.curr <= task->prio) { |
| 1711 | /* |
| 1712 | * Target rq has tasks of equal or higher priority, |
| 1713 | * retrying does not release any lock and is unlikely |
| 1714 | * to yield a different result. |
| 1715 | */ |
| 1716 | lowest_rq = NULL; |
| 1717 | break; |
| 1718 | } |
| 1719 | |
| 1720 | /* if the prio of this runqueue changed, try again */ |
| 1721 | if (double_lock_balance(rq, lowest_rq)) { |
| 1722 | /* |
| 1723 | * We had to unlock the run queue. In |
| 1724 | * the mean time, task could have |
| 1725 | * migrated already or had its affinity changed. |
| 1726 | * Also make sure that it wasn't scheduled on its rq. |
| 1727 | */ |
| 1728 | if (unlikely(task_rq(task) != rq || |
| 1729 | !cpumask_test_cpu(lowest_rq->cpu, |
| 1730 | tsk_cpus_allowed(task)) || |
| 1731 | task_running(rq, task) || |
| 1732 | !task_on_rq_queued(task))) { |
| 1733 | |
| 1734 | double_unlock_balance(rq, lowest_rq); |
| 1735 | lowest_rq = NULL; |
| 1736 | break; |
| 1737 | } |
| 1738 | } |
| 1739 | |
| 1740 | /* If this rq is still suitable use it. */ |
| 1741 | if (lowest_rq->rt.highest_prio.curr > task->prio) |
| 1742 | break; |
| 1743 | |
| 1744 | /* try again */ |
| 1745 | double_unlock_balance(rq, lowest_rq); |
| 1746 | lowest_rq = NULL; |
| 1747 | } |
| 1748 | |
| 1749 | return lowest_rq; |
| 1750 | } |
| 1751 | |
| 1752 | static struct task_struct *pick_next_pushable_task(struct rq *rq) |
| 1753 | { |
| 1754 | struct task_struct *p; |
| 1755 | |
| 1756 | if (!has_pushable_tasks(rq)) |
| 1757 | return NULL; |
| 1758 | |
| 1759 | p = plist_first_entry(&rq->rt.pushable_tasks, |
| 1760 | struct task_struct, pushable_tasks); |
| 1761 | |
| 1762 | BUG_ON(rq->cpu != task_cpu(p)); |
| 1763 | BUG_ON(task_current(rq, p)); |
| 1764 | BUG_ON(p->nr_cpus_allowed <= 1); |
| 1765 | |
| 1766 | BUG_ON(!task_on_rq_queued(p)); |
| 1767 | BUG_ON(!rt_task(p)); |
| 1768 | |
| 1769 | return p; |
| 1770 | } |
| 1771 | |
| 1772 | /* |
| 1773 | * If the current CPU has more than one RT task, see if the non |
| 1774 | * running task can migrate over to a CPU that is running a task |
| 1775 | * of lesser priority. |
| 1776 | */ |
| 1777 | static int push_rt_task(struct rq *rq) |
| 1778 | { |
| 1779 | struct task_struct *next_task; |
| 1780 | struct rq *lowest_rq; |
| 1781 | int ret = 0; |
| 1782 | |
| 1783 | if (!rq->rt.overloaded) |
| 1784 | return 0; |
| 1785 | |
| 1786 | next_task = pick_next_pushable_task(rq); |
| 1787 | if (!next_task) |
| 1788 | return 0; |
| 1789 | |
| 1790 | retry: |
| 1791 | if (unlikely(next_task == rq->curr)) { |
| 1792 | WARN_ON(1); |
| 1793 | return 0; |
| 1794 | } |
| 1795 | |
| 1796 | /* |
| 1797 | * It's possible that the next_task slipped in of |
| 1798 | * higher priority than current. If that's the case |
| 1799 | * just reschedule current. |
| 1800 | */ |
| 1801 | if (unlikely(next_task->prio < rq->curr->prio)) { |
| 1802 | resched_curr(rq); |
| 1803 | return 0; |
| 1804 | } |
| 1805 | |
| 1806 | /* We might release rq lock */ |
| 1807 | get_task_struct(next_task); |
| 1808 | |
| 1809 | /* find_lock_lowest_rq locks the rq if found */ |
| 1810 | lowest_rq = find_lock_lowest_rq(next_task, rq); |
| 1811 | if (!lowest_rq) { |
| 1812 | struct task_struct *task; |
| 1813 | /* |
| 1814 | * find_lock_lowest_rq releases rq->lock |
| 1815 | * so it is possible that next_task has migrated. |
| 1816 | * |
| 1817 | * We need to make sure that the task is still on the same |
| 1818 | * run-queue and is also still the next task eligible for |
| 1819 | * pushing. |
| 1820 | */ |
| 1821 | task = pick_next_pushable_task(rq); |
| 1822 | if (task_cpu(next_task) == rq->cpu && task == next_task) { |
| 1823 | /* |
| 1824 | * The task hasn't migrated, and is still the next |
| 1825 | * eligible task, but we failed to find a run-queue |
| 1826 | * to push it to. Do not retry in this case, since |
| 1827 | * other cpus will pull from us when ready. |
| 1828 | */ |
| 1829 | goto out; |
| 1830 | } |
| 1831 | |
| 1832 | if (!task) |
| 1833 | /* No more tasks, just exit */ |
| 1834 | goto out; |
| 1835 | |
| 1836 | /* |
| 1837 | * Something has shifted, try again. |
| 1838 | */ |
| 1839 | put_task_struct(next_task); |
| 1840 | next_task = task; |
| 1841 | goto retry; |
| 1842 | } |
| 1843 | |
| 1844 | deactivate_task(rq, next_task, 0); |
| 1845 | set_task_cpu(next_task, lowest_rq->cpu); |
| 1846 | activate_task(lowest_rq, next_task, 0); |
| 1847 | ret = 1; |
| 1848 | |
| 1849 | resched_curr(lowest_rq); |
| 1850 | |
| 1851 | double_unlock_balance(rq, lowest_rq); |
| 1852 | |
| 1853 | out: |
| 1854 | put_task_struct(next_task); |
| 1855 | |
| 1856 | return ret; |
| 1857 | } |
| 1858 | |
| 1859 | static void push_rt_tasks(struct rq *rq) |
| 1860 | { |
| 1861 | /* push_rt_task will return true if it moved an RT */ |
| 1862 | while (push_rt_task(rq)) |
| 1863 | ; |
| 1864 | } |
| 1865 | |
| 1866 | #ifdef HAVE_RT_PUSH_IPI |
| 1867 | /* |
| 1868 | * The search for the next cpu always starts at rq->cpu and ends |
| 1869 | * when we reach rq->cpu again. It will never return rq->cpu. |
| 1870 | * This returns the next cpu to check, or nr_cpu_ids if the loop |
| 1871 | * is complete. |
| 1872 | * |
| 1873 | * rq->rt.push_cpu holds the last cpu returned by this function, |
| 1874 | * or if this is the first instance, it must hold rq->cpu. |
| 1875 | */ |
| 1876 | static int rto_next_cpu(struct rq *rq) |
| 1877 | { |
| 1878 | int prev_cpu = rq->rt.push_cpu; |
| 1879 | int cpu; |
| 1880 | |
| 1881 | cpu = cpumask_next(prev_cpu, rq->rd->rto_mask); |
| 1882 | |
| 1883 | /* |
| 1884 | * If the previous cpu is less than the rq's CPU, then it already |
| 1885 | * passed the end of the mask, and has started from the beginning. |
| 1886 | * We end if the next CPU is greater or equal to rq's CPU. |
| 1887 | */ |
| 1888 | if (prev_cpu < rq->cpu) { |
| 1889 | if (cpu >= rq->cpu) |
| 1890 | return nr_cpu_ids; |
| 1891 | |
| 1892 | } else if (cpu >= nr_cpu_ids) { |
| 1893 | /* |
| 1894 | * We passed the end of the mask, start at the beginning. |
| 1895 | * If the result is greater or equal to the rq's CPU, then |
| 1896 | * the loop is finished. |
| 1897 | */ |
| 1898 | cpu = cpumask_first(rq->rd->rto_mask); |
| 1899 | if (cpu >= rq->cpu) |
| 1900 | return nr_cpu_ids; |
| 1901 | } |
| 1902 | rq->rt.push_cpu = cpu; |
| 1903 | |
| 1904 | /* Return cpu to let the caller know if the loop is finished or not */ |
| 1905 | return cpu; |
| 1906 | } |
| 1907 | |
| 1908 | static int find_next_push_cpu(struct rq *rq) |
| 1909 | { |
| 1910 | struct rq *next_rq; |
| 1911 | int cpu; |
| 1912 | |
| 1913 | while (1) { |
| 1914 | cpu = rto_next_cpu(rq); |
| 1915 | if (cpu >= nr_cpu_ids) |
| 1916 | break; |
| 1917 | next_rq = cpu_rq(cpu); |
| 1918 | |
| 1919 | /* Make sure the next rq can push to this rq */ |
| 1920 | if (next_rq->rt.highest_prio.next < rq->rt.highest_prio.curr) |
| 1921 | break; |
| 1922 | } |
| 1923 | |
| 1924 | return cpu; |
| 1925 | } |
| 1926 | |
| 1927 | #define RT_PUSH_IPI_EXECUTING 1 |
| 1928 | #define RT_PUSH_IPI_RESTART 2 |
| 1929 | |
| 1930 | static void tell_cpu_to_push(struct rq *rq) |
| 1931 | { |
| 1932 | int cpu; |
| 1933 | |
| 1934 | if (rq->rt.push_flags & RT_PUSH_IPI_EXECUTING) { |
| 1935 | raw_spin_lock(&rq->rt.push_lock); |
| 1936 | /* Make sure it's still executing */ |
| 1937 | if (rq->rt.push_flags & RT_PUSH_IPI_EXECUTING) { |
| 1938 | /* |
| 1939 | * Tell the IPI to restart the loop as things have |
| 1940 | * changed since it started. |
| 1941 | */ |
| 1942 | rq->rt.push_flags |= RT_PUSH_IPI_RESTART; |
| 1943 | raw_spin_unlock(&rq->rt.push_lock); |
| 1944 | return; |
| 1945 | } |
| 1946 | raw_spin_unlock(&rq->rt.push_lock); |
| 1947 | } |
| 1948 | |
| 1949 | /* When here, there's no IPI going around */ |
| 1950 | |
| 1951 | rq->rt.push_cpu = rq->cpu; |
| 1952 | cpu = find_next_push_cpu(rq); |
| 1953 | if (cpu >= nr_cpu_ids) |
| 1954 | return; |
| 1955 | |
| 1956 | rq->rt.push_flags = RT_PUSH_IPI_EXECUTING; |
| 1957 | |
| 1958 | irq_work_queue_on(&rq->rt.push_work, cpu); |
| 1959 | } |
| 1960 | |
| 1961 | /* Called from hardirq context */ |
| 1962 | static void try_to_push_tasks(void *arg) |
| 1963 | { |
| 1964 | struct rt_rq *rt_rq = arg; |
| 1965 | struct rq *rq, *src_rq; |
| 1966 | int this_cpu; |
| 1967 | int cpu; |
| 1968 | |
| 1969 | this_cpu = rt_rq->push_cpu; |
| 1970 | |
| 1971 | /* Paranoid check */ |
| 1972 | BUG_ON(this_cpu != smp_processor_id()); |
| 1973 | |
| 1974 | rq = cpu_rq(this_cpu); |
| 1975 | src_rq = rq_of_rt_rq(rt_rq); |
| 1976 | |
| 1977 | again: |
| 1978 | if (has_pushable_tasks(rq)) { |
| 1979 | raw_spin_lock(&rq->lock); |
| 1980 | push_rt_task(rq); |
| 1981 | raw_spin_unlock(&rq->lock); |
| 1982 | } |
| 1983 | |
| 1984 | /* Pass the IPI to the next rt overloaded queue */ |
| 1985 | raw_spin_lock(&rt_rq->push_lock); |
| 1986 | /* |
| 1987 | * If the source queue changed since the IPI went out, |
| 1988 | * we need to restart the search from that CPU again. |
| 1989 | */ |
| 1990 | if (rt_rq->push_flags & RT_PUSH_IPI_RESTART) { |
| 1991 | rt_rq->push_flags &= ~RT_PUSH_IPI_RESTART; |
| 1992 | rt_rq->push_cpu = src_rq->cpu; |
| 1993 | } |
| 1994 | |
| 1995 | cpu = find_next_push_cpu(src_rq); |
| 1996 | |
| 1997 | if (cpu >= nr_cpu_ids) |
| 1998 | rt_rq->push_flags &= ~RT_PUSH_IPI_EXECUTING; |
| 1999 | raw_spin_unlock(&rt_rq->push_lock); |
| 2000 | |
| 2001 | if (cpu >= nr_cpu_ids) |
| 2002 | return; |
| 2003 | |
| 2004 | /* |
| 2005 | * It is possible that a restart caused this CPU to be |
| 2006 | * chosen again. Don't bother with an IPI, just see if we |
| 2007 | * have more to push. |
| 2008 | */ |
| 2009 | if (unlikely(cpu == rq->cpu)) |
| 2010 | goto again; |
| 2011 | |
| 2012 | /* Try the next RT overloaded CPU */ |
| 2013 | irq_work_queue_on(&rt_rq->push_work, cpu); |
| 2014 | } |
| 2015 | |
| 2016 | static void push_irq_work_func(struct irq_work *work) |
| 2017 | { |
| 2018 | struct rt_rq *rt_rq = container_of(work, struct rt_rq, push_work); |
| 2019 | |
| 2020 | try_to_push_tasks(rt_rq); |
| 2021 | } |
| 2022 | #endif /* HAVE_RT_PUSH_IPI */ |
| 2023 | |
| 2024 | static void pull_rt_task(struct rq *this_rq) |
| 2025 | { |
| 2026 | int this_cpu = this_rq->cpu, cpu; |
| 2027 | bool resched = false; |
| 2028 | struct task_struct *p; |
| 2029 | struct rq *src_rq; |
| 2030 | |
| 2031 | if (likely(!rt_overloaded(this_rq))) |
| 2032 | return; |
| 2033 | |
| 2034 | /* |
| 2035 | * Match the barrier from rt_set_overloaded; this guarantees that if we |
| 2036 | * see overloaded we must also see the rto_mask bit. |
| 2037 | */ |
| 2038 | smp_rmb(); |
| 2039 | |
| 2040 | #ifdef HAVE_RT_PUSH_IPI |
| 2041 | if (sched_feat(RT_PUSH_IPI)) { |
| 2042 | tell_cpu_to_push(this_rq); |
| 2043 | return; |
| 2044 | } |
| 2045 | #endif |
| 2046 | |
| 2047 | for_each_cpu(cpu, this_rq->rd->rto_mask) { |
| 2048 | if (this_cpu == cpu) |
| 2049 | continue; |
| 2050 | |
| 2051 | src_rq = cpu_rq(cpu); |
| 2052 | |
| 2053 | /* |
| 2054 | * Don't bother taking the src_rq->lock if the next highest |
| 2055 | * task is known to be lower-priority than our current task. |
| 2056 | * This may look racy, but if this value is about to go |
| 2057 | * logically higher, the src_rq will push this task away. |
| 2058 | * And if its going logically lower, we do not care |
| 2059 | */ |
| 2060 | if (src_rq->rt.highest_prio.next >= |
| 2061 | this_rq->rt.highest_prio.curr) |
| 2062 | continue; |
| 2063 | |
| 2064 | /* |
| 2065 | * We can potentially drop this_rq's lock in |
| 2066 | * double_lock_balance, and another CPU could |
| 2067 | * alter this_rq |
| 2068 | */ |
| 2069 | double_lock_balance(this_rq, src_rq); |
| 2070 | |
| 2071 | /* |
| 2072 | * We can pull only a task, which is pushable |
| 2073 | * on its rq, and no others. |
| 2074 | */ |
| 2075 | p = pick_highest_pushable_task(src_rq, this_cpu); |
| 2076 | |
| 2077 | /* |
| 2078 | * Do we have an RT task that preempts |
| 2079 | * the to-be-scheduled task? |
| 2080 | */ |
| 2081 | if (p && (p->prio < this_rq->rt.highest_prio.curr)) { |
| 2082 | WARN_ON(p == src_rq->curr); |
| 2083 | WARN_ON(!task_on_rq_queued(p)); |
| 2084 | |
| 2085 | /* |
| 2086 | * There's a chance that p is higher in priority |
| 2087 | * than what's currently running on its cpu. |
| 2088 | * This is just that p is wakeing up and hasn't |
| 2089 | * had a chance to schedule. We only pull |
| 2090 | * p if it is lower in priority than the |
| 2091 | * current task on the run queue |
| 2092 | */ |
| 2093 | if (p->prio < src_rq->curr->prio) |
| 2094 | goto skip; |
| 2095 | |
| 2096 | resched = true; |
| 2097 | |
| 2098 | deactivate_task(src_rq, p, 0); |
| 2099 | set_task_cpu(p, this_cpu); |
| 2100 | activate_task(this_rq, p, 0); |
| 2101 | /* |
| 2102 | * We continue with the search, just in |
| 2103 | * case there's an even higher prio task |
| 2104 | * in another runqueue. (low likelihood |
| 2105 | * but possible) |
| 2106 | */ |
| 2107 | } |
| 2108 | skip: |
| 2109 | double_unlock_balance(this_rq, src_rq); |
| 2110 | } |
| 2111 | |
| 2112 | if (resched) |
| 2113 | resched_curr(this_rq); |
| 2114 | } |
| 2115 | |
| 2116 | /* |
| 2117 | * If we are not running and we are not going to reschedule soon, we should |
| 2118 | * try to push tasks away now |
| 2119 | */ |
| 2120 | static void task_woken_rt(struct rq *rq, struct task_struct *p) |
| 2121 | { |
| 2122 | if (!task_running(rq, p) && |
| 2123 | !test_tsk_need_resched(rq->curr) && |
| 2124 | p->nr_cpus_allowed > 1 && |
| 2125 | (dl_task(rq->curr) || rt_task(rq->curr)) && |
| 2126 | (rq->curr->nr_cpus_allowed < 2 || |
| 2127 | rq->curr->prio <= p->prio)) |
| 2128 | push_rt_tasks(rq); |
| 2129 | } |
| 2130 | |
| 2131 | /* Assumes rq->lock is held */ |
| 2132 | static void rq_online_rt(struct rq *rq) |
| 2133 | { |
| 2134 | if (rq->rt.overloaded) |
| 2135 | rt_set_overload(rq); |
| 2136 | |
| 2137 | __enable_runtime(rq); |
| 2138 | |
| 2139 | cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio.curr); |
| 2140 | } |
| 2141 | |
| 2142 | /* Assumes rq->lock is held */ |
| 2143 | static void rq_offline_rt(struct rq *rq) |
| 2144 | { |
| 2145 | if (rq->rt.overloaded) |
| 2146 | rt_clear_overload(rq); |
| 2147 | |
| 2148 | __disable_runtime(rq); |
| 2149 | |
| 2150 | cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_INVALID); |
| 2151 | } |
| 2152 | |
| 2153 | /* |
| 2154 | * When switch from the rt queue, we bring ourselves to a position |
| 2155 | * that we might want to pull RT tasks from other runqueues. |
| 2156 | */ |
| 2157 | static void switched_from_rt(struct rq *rq, struct task_struct *p) |
| 2158 | { |
| 2159 | /* |
| 2160 | * If there are other RT tasks then we will reschedule |
| 2161 | * and the scheduling of the other RT tasks will handle |
| 2162 | * the balancing. But if we are the last RT task |
| 2163 | * we may need to handle the pulling of RT tasks |
| 2164 | * now. |
| 2165 | */ |
| 2166 | if (!task_on_rq_queued(p) || rq->rt.rt_nr_running) |
| 2167 | return; |
| 2168 | |
| 2169 | queue_pull_task(rq); |
| 2170 | } |
| 2171 | |
| 2172 | void __init init_sched_rt_class(void) |
| 2173 | { |
| 2174 | unsigned int i; |
| 2175 | |
| 2176 | for_each_possible_cpu(i) { |
| 2177 | zalloc_cpumask_var_node(&per_cpu(local_cpu_mask, i), |
| 2178 | GFP_KERNEL, cpu_to_node(i)); |
| 2179 | } |
| 2180 | } |
| 2181 | #endif /* CONFIG_SMP */ |
| 2182 | |
| 2183 | /* |
| 2184 | * When switching a task to RT, we may overload the runqueue |
| 2185 | * with RT tasks. In this case we try to push them off to |
| 2186 | * other runqueues. |
| 2187 | */ |
| 2188 | static void switched_to_rt(struct rq *rq, struct task_struct *p) |
| 2189 | { |
| 2190 | /* |
| 2191 | * If we are already running, then there's nothing |
| 2192 | * that needs to be done. But if we are not running |
| 2193 | * we may need to preempt the current running task. |
| 2194 | * If that current running task is also an RT task |
| 2195 | * then see if we can move to another run queue. |
| 2196 | */ |
| 2197 | if (task_on_rq_queued(p) && rq->curr != p) { |
| 2198 | #ifdef CONFIG_SMP |
| 2199 | if (p->nr_cpus_allowed > 1 && rq->rt.overloaded) |
| 2200 | queue_push_tasks(rq); |
| 2201 | #else |
| 2202 | if (p->prio < rq->curr->prio) |
| 2203 | resched_curr(rq); |
| 2204 | #endif /* CONFIG_SMP */ |
| 2205 | } |
| 2206 | } |
| 2207 | |
| 2208 | /* |
| 2209 | * Priority of the task has changed. This may cause |
| 2210 | * us to initiate a push or pull. |
| 2211 | */ |
| 2212 | static void |
| 2213 | prio_changed_rt(struct rq *rq, struct task_struct *p, int oldprio) |
| 2214 | { |
| 2215 | if (!task_on_rq_queued(p)) |
| 2216 | return; |
| 2217 | |
| 2218 | if (rq->curr == p) { |
| 2219 | #ifdef CONFIG_SMP |
| 2220 | /* |
| 2221 | * If our priority decreases while running, we |
| 2222 | * may need to pull tasks to this runqueue. |
| 2223 | */ |
| 2224 | if (oldprio < p->prio) |
| 2225 | queue_pull_task(rq); |
| 2226 | |
| 2227 | /* |
| 2228 | * If there's a higher priority task waiting to run |
| 2229 | * then reschedule. |
| 2230 | */ |
| 2231 | if (p->prio > rq->rt.highest_prio.curr) |
| 2232 | resched_curr(rq); |
| 2233 | #else |
| 2234 | /* For UP simply resched on drop of prio */ |
| 2235 | if (oldprio < p->prio) |
| 2236 | resched_curr(rq); |
| 2237 | #endif /* CONFIG_SMP */ |
| 2238 | } else { |
| 2239 | /* |
| 2240 | * This task is not running, but if it is |
| 2241 | * greater than the current running task |
| 2242 | * then reschedule. |
| 2243 | */ |
| 2244 | if (p->prio < rq->curr->prio) |
| 2245 | resched_curr(rq); |
| 2246 | } |
| 2247 | } |
| 2248 | |
| 2249 | static void watchdog(struct rq *rq, struct task_struct *p) |
| 2250 | { |
| 2251 | unsigned long soft, hard; |
| 2252 | |
| 2253 | /* max may change after cur was read, this will be fixed next tick */ |
| 2254 | soft = task_rlimit(p, RLIMIT_RTTIME); |
| 2255 | hard = task_rlimit_max(p, RLIMIT_RTTIME); |
| 2256 | |
| 2257 | if (soft != RLIM_INFINITY) { |
| 2258 | unsigned long next; |
| 2259 | |
| 2260 | if (p->rt.watchdog_stamp != jiffies) { |
| 2261 | p->rt.timeout++; |
| 2262 | p->rt.watchdog_stamp = jiffies; |
| 2263 | } |
| 2264 | |
| 2265 | next = DIV_ROUND_UP(min(soft, hard), USEC_PER_SEC/HZ); |
| 2266 | if (p->rt.timeout > next) |
| 2267 | p->cputime_expires.sched_exp = p->se.sum_exec_runtime; |
| 2268 | } |
| 2269 | } |
| 2270 | |
| 2271 | static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued) |
| 2272 | { |
| 2273 | struct sched_rt_entity *rt_se = &p->rt; |
| 2274 | |
| 2275 | update_curr_rt(rq); |
| 2276 | |
| 2277 | watchdog(rq, p); |
| 2278 | |
| 2279 | /* |
| 2280 | * RR tasks need a special form of timeslice management. |
| 2281 | * FIFO tasks have no timeslices. |
| 2282 | */ |
| 2283 | if (p->policy != SCHED_RR) |
| 2284 | return; |
| 2285 | |
| 2286 | if (--p->rt.time_slice) |
| 2287 | return; |
| 2288 | |
| 2289 | p->rt.time_slice = sched_rr_timeslice; |
| 2290 | |
| 2291 | /* |
| 2292 | * Requeue to the end of queue if we (and all of our ancestors) are not |
| 2293 | * the only element on the queue |
| 2294 | */ |
| 2295 | for_each_sched_rt_entity(rt_se) { |
| 2296 | if (rt_se->run_list.prev != rt_se->run_list.next) { |
| 2297 | requeue_task_rt(rq, p, 0); |
| 2298 | resched_curr(rq); |
| 2299 | return; |
| 2300 | } |
| 2301 | } |
| 2302 | } |
| 2303 | |
| 2304 | static void set_curr_task_rt(struct rq *rq) |
| 2305 | { |
| 2306 | struct task_struct *p = rq->curr; |
| 2307 | |
| 2308 | p->se.exec_start = rq_clock_task(rq); |
| 2309 | |
| 2310 | /* The running task is never eligible for pushing */ |
| 2311 | dequeue_pushable_task(rq, p); |
| 2312 | } |
| 2313 | |
| 2314 | static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task) |
| 2315 | { |
| 2316 | /* |
| 2317 | * Time slice is 0 for SCHED_FIFO tasks |
| 2318 | */ |
| 2319 | if (task->policy == SCHED_RR) |
| 2320 | return sched_rr_timeslice; |
| 2321 | else |
| 2322 | return 0; |
| 2323 | } |
| 2324 | |
| 2325 | const struct sched_class rt_sched_class = { |
| 2326 | .next = &fair_sched_class, |
| 2327 | .enqueue_task = enqueue_task_rt, |
| 2328 | .dequeue_task = dequeue_task_rt, |
| 2329 | .yield_task = yield_task_rt, |
| 2330 | |
| 2331 | .check_preempt_curr = check_preempt_curr_rt, |
| 2332 | |
| 2333 | .pick_next_task = pick_next_task_rt, |
| 2334 | .put_prev_task = put_prev_task_rt, |
| 2335 | |
| 2336 | #ifdef CONFIG_SMP |
| 2337 | .select_task_rq = select_task_rq_rt, |
| 2338 | |
| 2339 | .set_cpus_allowed = set_cpus_allowed_common, |
| 2340 | .rq_online = rq_online_rt, |
| 2341 | .rq_offline = rq_offline_rt, |
| 2342 | .task_woken = task_woken_rt, |
| 2343 | .switched_from = switched_from_rt, |
| 2344 | #endif |
| 2345 | |
| 2346 | .set_curr_task = set_curr_task_rt, |
| 2347 | .task_tick = task_tick_rt, |
| 2348 | |
| 2349 | .get_rr_interval = get_rr_interval_rt, |
| 2350 | |
| 2351 | .prio_changed = prio_changed_rt, |
| 2352 | .switched_to = switched_to_rt, |
| 2353 | |
| 2354 | .update_curr = update_curr_rt, |
| 2355 | }; |
| 2356 | |
| 2357 | #ifdef CONFIG_SCHED_DEBUG |
| 2358 | extern void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq); |
| 2359 | |
| 2360 | void print_rt_stats(struct seq_file *m, int cpu) |
| 2361 | { |
| 2362 | rt_rq_iter_t iter; |
| 2363 | struct rt_rq *rt_rq; |
| 2364 | |
| 2365 | rcu_read_lock(); |
| 2366 | for_each_rt_rq(rt_rq, iter, cpu_rq(cpu)) |
| 2367 | print_rt_rq(m, cpu, rt_rq); |
| 2368 | rcu_read_unlock(); |
| 2369 | } |
| 2370 | #endif /* CONFIG_SCHED_DEBUG */ |