1 /* 2 * kernel/sched/core.c 3 * 4 * Kernel scheduler and related syscalls 5 * 6 * Copyright (C) 1991-2002 Linus Torvalds 7 * 8 * 1996-12-23 Modified by Dave Grothe to fix bugs in semaphores and 9 * make semaphores SMP safe 10 * 1998-11-19 Implemented schedule_timeout() and related stuff 11 * by Andrea Arcangeli 12 * 2002-01-04 New ultra-scalable O(1) scheduler by Ingo Molnar: 13 * hybrid priority-list and round-robin design with 14 * an array-switch method of distributing timeslices 15 * and per-CPU runqueues. Cleanups and useful suggestions 16 * by Davide Libenzi, preemptible kernel bits by Robert Love. 17 * 2003-09-03 Interactivity tuning by Con Kolivas. 18 * 2004-04-02 Scheduler domains code by Nick Piggin 19 * 2007-04-15 Work begun on replacing all interactivity tuning with a 20 * fair scheduling design by Con Kolivas. 21 * 2007-05-05 Load balancing (smp-nice) and other improvements 22 * by Peter Williams 23 * 2007-05-06 Interactivity improvements to CFS by Mike Galbraith 24 * 2007-07-01 Group scheduling enhancements by Srivatsa Vaddagiri 25 * 2007-11-29 RT balancing improvements by Steven Rostedt, Gregory Haskins, 26 * Thomas Gleixner, Mike Kravetz 27 */ 28 29 #include <linux/mm.h> 30 #include <linux/module.h> 31 #include <linux/nmi.h> 32 #include <linux/init.h> 33 #include <linux/uaccess.h> 34 #include <linux/highmem.h> 35 #include <asm/mmu_context.h> 36 #include <linux/interrupt.h> 37 #include <linux/capability.h> 38 #include <linux/completion.h> 39 #include <linux/kernel_stat.h> 40 #include <linux/debug_locks.h> 41 #include <linux/perf_event.h> 42 #include <linux/security.h> 43 #include <linux/notifier.h> 44 #include <linux/profile.h> 45 #include <linux/freezer.h> 46 #include <linux/vmalloc.h> 47 #include <linux/blkdev.h> 48 #include <linux/delay.h> 49 #include <linux/pid_namespace.h> 50 #include <linux/smp.h> 51 #include <linux/threads.h> 52 #include <linux/timer.h> 53 #include <linux/rcupdate.h> 54 #include <linux/cpu.h> 55 #include <linux/cpuset.h> 56 #include <linux/percpu.h> 57 #include <linux/proc_fs.h> 58 #include <linux/seq_file.h> 59 #include <linux/sysctl.h> 60 #include <linux/syscalls.h> 61 #include <linux/times.h> 62 #include <linux/tsacct_kern.h> 63 #include <linux/kprobes.h> 64 #include <linux/delayacct.h> 65 #include <linux/unistd.h> 66 #include <linux/pagemap.h> 67 #include <linux/hrtimer.h> 68 #include <linux/tick.h> 69 #include <linux/debugfs.h> 70 #include <linux/ctype.h> 71 #include <linux/ftrace.h> 72 #include <linux/slab.h> 73 #include <linux/init_task.h> 74 #include <linux/binfmts.h> 75 76 #include <asm/switch_to.h> 77 #include <asm/tlb.h> 78 #include <asm/irq_regs.h> 79 #include <asm/mutex.h> 80 #ifdef CONFIG_PARAVIRT 81 #include <asm/paravirt.h> 82 #endif 83 84 #include "sched.h" 85 #include "../workqueue_sched.h" 86 #include "../smpboot.h" 87 88 #define CREATE_TRACE_POINTS 89 #include <trace/events/sched.h> 90 91 void start_bandwidth_timer(struct hrtimer *period_timer, ktime_t period) 92 { 93 unsigned long delta; 94 ktime_t soft, hard, now; 95 96 for (;;) { 97 if (hrtimer_active(period_timer)) 98 break; 99 100 now = hrtimer_cb_get_time(period_timer); 101 hrtimer_forward(period_timer, now, period); 102 103 soft = hrtimer_get_softexpires(period_timer); 104 hard = hrtimer_get_expires(period_timer); 105 delta = ktime_to_ns(ktime_sub(hard, soft)); 106 __hrtimer_start_range_ns(period_timer, soft, delta, 107 HRTIMER_MODE_ABS_PINNED, 0); 108 } 109 } 110 111 DEFINE_MUTEX(sched_domains_mutex); 112 DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues); 113 114 static void update_rq_clock_task(struct rq *rq, s64 delta); 115 116 void update_rq_clock(struct rq *rq) 117 { 118 s64 delta; 119 120 if (rq->skip_clock_update > 0) 121 return; 122 123 delta = sched_clock_cpu(cpu_of(rq)) - rq->clock; 124 rq->clock += delta; 125 update_rq_clock_task(rq, delta); 126 } 127 128 /* 129 * Debugging: various feature bits 130 */ 131 132 #define SCHED_FEAT(name, enabled) \ 133 (1UL << __SCHED_FEAT_##name) * enabled | 134 135 const_debug unsigned int sysctl_sched_features = 136 #include "features.h" 137 0; 138 139 #undef SCHED_FEAT 140 141 #ifdef CONFIG_SCHED_DEBUG 142 #define SCHED_FEAT(name, enabled) \ 143 #name , 144 145 static const char * const sched_feat_names[] = { 146 #include "features.h" 147 }; 148 149 #undef SCHED_FEAT 150 151 static int sched_feat_show(struct seq_file *m, void *v) 152 { 153 int i; 154 155 for (i = 0; i < __SCHED_FEAT_NR; i++) { 156 if (!(sysctl_sched_features & (1UL << i))) 157 seq_puts(m, "NO_"); 158 seq_printf(m, "%s ", sched_feat_names[i]); 159 } 160 seq_puts(m, "\n"); 161 162 return 0; 163 } 164 165 #ifdef HAVE_JUMP_LABEL 166 167 #define jump_label_key__true STATIC_KEY_INIT_TRUE 168 #define jump_label_key__false STATIC_KEY_INIT_FALSE 169 170 #define SCHED_FEAT(name, enabled) \ 171 jump_label_key__##enabled , 172 173 struct static_key sched_feat_keys[__SCHED_FEAT_NR] = { 174 #include "features.h" 175 }; 176 177 #undef SCHED_FEAT 178 179 static void sched_feat_disable(int i) 180 { 181 if (static_key_enabled(&sched_feat_keys[i])) 182 static_key_slow_dec(&sched_feat_keys[i]); 183 } 184 185 static void sched_feat_enable(int i) 186 { 187 if (!static_key_enabled(&sched_feat_keys[i])) 188 static_key_slow_inc(&sched_feat_keys[i]); 189 } 190 #else 191 static void sched_feat_disable(int i) { }; 192 static void sched_feat_enable(int i) { }; 193 #endif /* HAVE_JUMP_LABEL */ 194 195 static ssize_t 196 sched_feat_write(struct file *filp, const char __user *ubuf, 197 size_t cnt, loff_t *ppos) 198 { 199 char buf[64]; 200 char *cmp; 201 int neg = 0; 202 int i; 203 204 if (cnt > 63) 205 cnt = 63; 206 207 if (copy_from_user(&buf, ubuf, cnt)) 208 return -EFAULT; 209 210 buf[cnt] = 0; 211 cmp = strstrip(buf); 212 213 if (strncmp(cmp, "NO_", 3) == 0) { 214 neg = 1; 215 cmp += 3; 216 } 217 218 for (i = 0; i < __SCHED_FEAT_NR; i++) { 219 if (strcmp(cmp, sched_feat_names[i]) == 0) { 220 if (neg) { 221 sysctl_sched_features &= ~(1UL << i); 222 sched_feat_disable(i); 223 } else { 224 sysctl_sched_features |= (1UL << i); 225 sched_feat_enable(i); 226 } 227 break; 228 } 229 } 230 231 if (i == __SCHED_FEAT_NR) 232 return -EINVAL; 233 234 *ppos += cnt; 235 236 return cnt; 237 } 238 239 static int sched_feat_open(struct inode *inode, struct file *filp) 240 { 241 return single_open(filp, sched_feat_show, NULL); 242 } 243 244 static const struct file_operations sched_feat_fops = { 245 .open = sched_feat_open, 246 .write = sched_feat_write, 247 .read = seq_read, 248 .llseek = seq_lseek, 249 .release = single_release, 250 }; 251 252 static __init int sched_init_debug(void) 253 { 254 debugfs_create_file("sched_features", 0644, NULL, NULL, 255 &sched_feat_fops); 256 257 return 0; 258 } 259 late_initcall(sched_init_debug); 260 #endif /* CONFIG_SCHED_DEBUG */ 261 262 /* 263 * Number of tasks to iterate in a single balance run. 264 * Limited because this is done with IRQs disabled. 265 */ 266 const_debug unsigned int sysctl_sched_nr_migrate = 32; 267 268 /* 269 * period over which we average the RT time consumption, measured 270 * in ms. 271 * 272 * default: 1s 273 */ 274 const_debug unsigned int sysctl_sched_time_avg = MSEC_PER_SEC; 275 276 /* 277 * period over which we measure -rt task cpu usage in us. 278 * default: 1s 279 */ 280 unsigned int sysctl_sched_rt_period = 1000000; 281 282 __read_mostly int scheduler_running; 283 284 /* 285 * part of the period that we allow rt tasks to run in us. 286 * default: 0.95s 287 */ 288 int sysctl_sched_rt_runtime = 950000; 289 290 291 292 /* 293 * __task_rq_lock - lock the rq @p resides on. 294 */ 295 static inline struct rq *__task_rq_lock(struct task_struct *p) 296 __acquires(rq->lock) 297 { 298 struct rq *rq; 299 300 lockdep_assert_held(&p->pi_lock); 301 302 for (;;) { 303 rq = task_rq(p); 304 raw_spin_lock(&rq->lock); 305 if (likely(rq == task_rq(p))) 306 return rq; 307 raw_spin_unlock(&rq->lock); 308 } 309 } 310 311 /* 312 * task_rq_lock - lock p->pi_lock and lock the rq @p resides on. 313 */ 314 static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags) 315 __acquires(p->pi_lock) 316 __acquires(rq->lock) 317 { 318 struct rq *rq; 319 320 for (;;) { 321 raw_spin_lock_irqsave(&p->pi_lock, *flags); 322 rq = task_rq(p); 323 raw_spin_lock(&rq->lock); 324 if (likely(rq == task_rq(p))) 325 return rq; 326 raw_spin_unlock(&rq->lock); 327 raw_spin_unlock_irqrestore(&p->pi_lock, *flags); 328 } 329 } 330 331 static void __task_rq_unlock(struct rq *rq) 332 __releases(rq->lock) 333 { 334 raw_spin_unlock(&rq->lock); 335 } 336 337 static inline void 338 task_rq_unlock(struct rq *rq, struct task_struct *p, unsigned long *flags) 339 __releases(rq->lock) 340 __releases(p->pi_lock) 341 { 342 raw_spin_unlock(&rq->lock); 343 raw_spin_unlock_irqrestore(&p->pi_lock, *flags); 344 } 345 346 /* 347 * this_rq_lock - lock this runqueue and disable interrupts. 348 */ 349 static struct rq *this_rq_lock(void) 350 __acquires(rq->lock) 351 { 352 struct rq *rq; 353 354 local_irq_disable(); 355 rq = this_rq(); 356 raw_spin_lock(&rq->lock); 357 358 return rq; 359 } 360 361 #ifdef CONFIG_SCHED_HRTICK 362 /* 363 * Use HR-timers to deliver accurate preemption points. 364 * 365 * Its all a bit involved since we cannot program an hrt while holding the 366 * rq->lock. So what we do is store a state in in rq->hrtick_* and ask for a 367 * reschedule event. 368 * 369 * When we get rescheduled we reprogram the hrtick_timer outside of the 370 * rq->lock. 371 */ 372 373 static void hrtick_clear(struct rq *rq) 374 { 375 if (hrtimer_active(&rq->hrtick_timer)) 376 hrtimer_cancel(&rq->hrtick_timer); 377 } 378 379 /* 380 * High-resolution timer tick. 381 * Runs from hardirq context with interrupts disabled. 382 */ 383 static enum hrtimer_restart hrtick(struct hrtimer *timer) 384 { 385 struct rq *rq = container_of(timer, struct rq, hrtick_timer); 386 387 WARN_ON_ONCE(cpu_of(rq) != smp_processor_id()); 388 389 raw_spin_lock(&rq->lock); 390 update_rq_clock(rq); 391 rq->curr->sched_class->task_tick(rq, rq->curr, 1); 392 raw_spin_unlock(&rq->lock); 393 394 return HRTIMER_NORESTART; 395 } 396 397 #ifdef CONFIG_SMP 398 /* 399 * called from hardirq (IPI) context 400 */ 401 static void __hrtick_start(void *arg) 402 { 403 struct rq *rq = arg; 404 405 raw_spin_lock(&rq->lock); 406 hrtimer_restart(&rq->hrtick_timer); 407 rq->hrtick_csd_pending = 0; 408 raw_spin_unlock(&rq->lock); 409 } 410 411 /* 412 * Called to set the hrtick timer state. 413 * 414 * called with rq->lock held and irqs disabled 415 */ 416 void hrtick_start(struct rq *rq, u64 delay) 417 { 418 struct hrtimer *timer = &rq->hrtick_timer; 419 ktime_t time = ktime_add_ns(timer->base->get_time(), delay); 420 421 hrtimer_set_expires(timer, time); 422 423 if (rq == this_rq()) { 424 hrtimer_restart(timer); 425 } else if (!rq->hrtick_csd_pending) { 426 __smp_call_function_single(cpu_of(rq), &rq->hrtick_csd, 0); 427 rq->hrtick_csd_pending = 1; 428 } 429 } 430 431 static int 432 hotplug_hrtick(struct notifier_block *nfb, unsigned long action, void *hcpu) 433 { 434 int cpu = (int)(long)hcpu; 435 436 switch (action) { 437 case CPU_UP_CANCELED: 438 case CPU_UP_CANCELED_FROZEN: 439 case CPU_DOWN_PREPARE: 440 case CPU_DOWN_PREPARE_FROZEN: 441 case CPU_DEAD: 442 case CPU_DEAD_FROZEN: 443 hrtick_clear(cpu_rq(cpu)); 444 return NOTIFY_OK; 445 } 446 447 return NOTIFY_DONE; 448 } 449 450 static __init void init_hrtick(void) 451 { 452 hotcpu_notifier(hotplug_hrtick, 0); 453 } 454 #else 455 /* 456 * Called to set the hrtick timer state. 457 * 458 * called with rq->lock held and irqs disabled 459 */ 460 void hrtick_start(struct rq *rq, u64 delay) 461 { 462 __hrtimer_start_range_ns(&rq->hrtick_timer, ns_to_ktime(delay), 0, 463 HRTIMER_MODE_REL_PINNED, 0); 464 } 465 466 static inline void init_hrtick(void) 467 { 468 } 469 #endif /* CONFIG_SMP */ 470 471 static void init_rq_hrtick(struct rq *rq) 472 { 473 #ifdef CONFIG_SMP 474 rq->hrtick_csd_pending = 0; 475 476 rq->hrtick_csd.flags = 0; 477 rq->hrtick_csd.func = __hrtick_start; 478 rq->hrtick_csd.info = rq; 479 #endif 480 481 hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 482 rq->hrtick_timer.function = hrtick; 483 } 484 #else /* CONFIG_SCHED_HRTICK */ 485 static inline void hrtick_clear(struct rq *rq) 486 { 487 } 488 489 static inline void init_rq_hrtick(struct rq *rq) 490 { 491 } 492 493 static inline void init_hrtick(void) 494 { 495 } 496 #endif /* CONFIG_SCHED_HRTICK */ 497 498 /* 499 * resched_task - mark a task 'to be rescheduled now'. 500 * 501 * On UP this means the setting of the need_resched flag, on SMP it 502 * might also involve a cross-CPU call to trigger the scheduler on 503 * the target CPU. 504 */ 505 #ifdef CONFIG_SMP 506 507 #ifndef tsk_is_polling 508 #define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG) 509 #endif 510 511 void resched_task(struct task_struct *p) 512 { 513 int cpu; 514 515 assert_raw_spin_locked(&task_rq(p)->lock); 516 517 if (test_tsk_need_resched(p)) 518 return; 519 520 set_tsk_need_resched(p); 521 522 cpu = task_cpu(p); 523 if (cpu == smp_processor_id()) 524 return; 525 526 /* NEED_RESCHED must be visible before we test polling */ 527 smp_mb(); 528 if (!tsk_is_polling(p)) 529 smp_send_reschedule(cpu); 530 } 531 532 void resched_cpu(int cpu) 533 { 534 struct rq *rq = cpu_rq(cpu); 535 unsigned long flags; 536 537 if (!raw_spin_trylock_irqsave(&rq->lock, flags)) 538 return; 539 resched_task(cpu_curr(cpu)); 540 raw_spin_unlock_irqrestore(&rq->lock, flags); 541 } 542 543 #ifdef CONFIG_NO_HZ 544 /* 545 * In the semi idle case, use the nearest busy cpu for migrating timers 546 * from an idle cpu. This is good for power-savings. 547 * 548 * We don't do similar optimization for completely idle system, as 549 * selecting an idle cpu will add more delays to the timers than intended 550 * (as that cpu's timer base may not be uptodate wrt jiffies etc). 551 */ 552 int get_nohz_timer_target(void) 553 { 554 int cpu = smp_processor_id(); 555 int i; 556 struct sched_domain *sd; 557 558 rcu_read_lock(); 559 for_each_domain(cpu, sd) { 560 for_each_cpu(i, sched_domain_span(sd)) { 561 if (!idle_cpu(i)) { 562 cpu = i; 563 goto unlock; 564 } 565 } 566 } 567 unlock: 568 rcu_read_unlock(); 569 return cpu; 570 } 571 /* 572 * When add_timer_on() enqueues a timer into the timer wheel of an 573 * idle CPU then this timer might expire before the next timer event 574 * which is scheduled to wake up that CPU. In case of a completely 575 * idle system the next event might even be infinite time into the 576 * future. wake_up_idle_cpu() ensures that the CPU is woken up and 577 * leaves the inner idle loop so the newly added timer is taken into 578 * account when the CPU goes back to idle and evaluates the timer 579 * wheel for the next timer event. 580 */ 581 void wake_up_idle_cpu(int cpu) 582 { 583 struct rq *rq = cpu_rq(cpu); 584 585 if (cpu == smp_processor_id()) 586 return; 587 588 /* 589 * This is safe, as this function is called with the timer 590 * wheel base lock of (cpu) held. When the CPU is on the way 591 * to idle and has not yet set rq->curr to idle then it will 592 * be serialized on the timer wheel base lock and take the new 593 * timer into account automatically. 594 */ 595 if (rq->curr != rq->idle) 596 return; 597 598 /* 599 * We can set TIF_RESCHED on the idle task of the other CPU 600 * lockless. The worst case is that the other CPU runs the 601 * idle task through an additional NOOP schedule() 602 */ 603 set_tsk_need_resched(rq->idle); 604 605 /* NEED_RESCHED must be visible before we test polling */ 606 smp_mb(); 607 if (!tsk_is_polling(rq->idle)) 608 smp_send_reschedule(cpu); 609 } 610 611 static inline bool got_nohz_idle_kick(void) 612 { 613 int cpu = smp_processor_id(); 614 return idle_cpu(cpu) && test_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu)); 615 } 616 617 #else /* CONFIG_NO_HZ */ 618 619 static inline bool got_nohz_idle_kick(void) 620 { 621 return false; 622 } 623 624 #endif /* CONFIG_NO_HZ */ 625 626 void sched_avg_update(struct rq *rq) 627 { 628 s64 period = sched_avg_period(); 629 630 while ((s64)(rq->clock - rq->age_stamp) > period) { 631 /* 632 * Inline assembly required to prevent the compiler 633 * optimising this loop into a divmod call. 634 * See __iter_div_u64_rem() for another example of this. 635 */ 636 asm("" : "+rm" (rq->age_stamp)); 637 rq->age_stamp += period; 638 rq->rt_avg /= 2; 639 } 640 } 641 642 #else /* !CONFIG_SMP */ 643 void resched_task(struct task_struct *p) 644 { 645 assert_raw_spin_locked(&task_rq(p)->lock); 646 set_tsk_need_resched(p); 647 } 648 #endif /* CONFIG_SMP */ 649 650 #if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \ 651 (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH))) 652 /* 653 * Iterate task_group tree rooted at *from, calling @down when first entering a 654 * node and @up when leaving it for the final time. 655 * 656 * Caller must hold rcu_lock or sufficient equivalent. 657 */ 658 int walk_tg_tree_from(struct task_group *from, 659 tg_visitor down, tg_visitor up, void *data) 660 { 661 struct task_group *parent, *child; 662 int ret; 663 664 parent = from; 665 666 down: 667 ret = (*down)(parent, data); 668 if (ret) 669 goto out; 670 list_for_each_entry_rcu(child, &parent->children, siblings) { 671 parent = child; 672 goto down; 673 674 up: 675 continue; 676 } 677 ret = (*up)(parent, data); 678 if (ret || parent == from) 679 goto out; 680 681 child = parent; 682 parent = parent->parent; 683 if (parent) 684 goto up; 685 out: 686 return ret; 687 } 688 689 int tg_nop(struct task_group *tg, void *data) 690 { 691 return 0; 692 } 693 #endif 694 695 static void set_load_weight(struct task_struct *p) 696 { 697 int prio = p->static_prio - MAX_RT_PRIO; 698 struct load_weight *load = &p->se.load; 699 700 /* 701 * SCHED_IDLE tasks get minimal weight: 702 */ 703 if (p->policy == SCHED_IDLE) { 704 load->weight = scale_load(WEIGHT_IDLEPRIO); 705 load->inv_weight = WMULT_IDLEPRIO; 706 return; 707 } 708 709 load->weight = scale_load(prio_to_weight[prio]); 710 load->inv_weight = prio_to_wmult[prio]; 711 } 712 713 static void enqueue_task(struct rq *rq, struct task_struct *p, int flags) 714 { 715 update_rq_clock(rq); 716 sched_info_queued(p); 717 p->sched_class->enqueue_task(rq, p, flags); 718 } 719 720 static void dequeue_task(struct rq *rq, struct task_struct *p, int flags) 721 { 722 update_rq_clock(rq); 723 sched_info_dequeued(p); 724 p->sched_class->dequeue_task(rq, p, flags); 725 } 726 727 void activate_task(struct rq *rq, struct task_struct *p, int flags) 728 { 729 if (task_contributes_to_load(p)) 730 rq->nr_uninterruptible--; 731 732 enqueue_task(rq, p, flags); 733 } 734 735 void deactivate_task(struct rq *rq, struct task_struct *p, int flags) 736 { 737 if (task_contributes_to_load(p)) 738 rq->nr_uninterruptible++; 739 740 dequeue_task(rq, p, flags); 741 } 742 743 static void update_rq_clock_task(struct rq *rq, s64 delta) 744 { 745 /* 746 * In theory, the compile should just see 0 here, and optimize out the call 747 * to sched_rt_avg_update. But I don't trust it... 748 */ 749 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING) 750 s64 steal = 0, irq_delta = 0; 751 #endif 752 #ifdef CONFIG_IRQ_TIME_ACCOUNTING 753 irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time; 754 755 /* 756 * Since irq_time is only updated on {soft,}irq_exit, we might run into 757 * this case when a previous update_rq_clock() happened inside a 758 * {soft,}irq region. 759 * 760 * When this happens, we stop ->clock_task and only update the 761 * prev_irq_time stamp to account for the part that fit, so that a next 762 * update will consume the rest. This ensures ->clock_task is 763 * monotonic. 764 * 765 * It does however cause some slight miss-attribution of {soft,}irq 766 * time, a more accurate solution would be to update the irq_time using 767 * the current rq->clock timestamp, except that would require using 768 * atomic ops. 769 */ 770 if (irq_delta > delta) 771 irq_delta = delta; 772 773 rq->prev_irq_time += irq_delta; 774 delta -= irq_delta; 775 #endif 776 #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING 777 if (static_key_false((¶virt_steal_rq_enabled))) { 778 u64 st; 779 780 steal = paravirt_steal_clock(cpu_of(rq)); 781 steal -= rq->prev_steal_time_rq; 782 783 if (unlikely(steal > delta)) 784 steal = delta; 785 786 st = steal_ticks(steal); 787 steal = st * TICK_NSEC; 788 789 rq->prev_steal_time_rq += steal; 790 791 delta -= steal; 792 } 793 #endif 794 795 rq->clock_task += delta; 796 797 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING) 798 if ((irq_delta + steal) && sched_feat(NONTASK_POWER)) 799 sched_rt_avg_update(rq, irq_delta + steal); 800 #endif 801 } 802 803 void sched_set_stop_task(int cpu, struct task_struct *stop) 804 { 805 struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 }; 806 struct task_struct *old_stop = cpu_rq(cpu)->stop; 807 808 if (stop) { 809 /* 810 * Make it appear like a SCHED_FIFO task, its something 811 * userspace knows about and won't get confused about. 812 * 813 * Also, it will make PI more or less work without too 814 * much confusion -- but then, stop work should not 815 * rely on PI working anyway. 816 */ 817 sched_setscheduler_nocheck(stop, SCHED_FIFO, ¶m); 818 819 stop->sched_class = &stop_sched_class; 820 } 821 822 cpu_rq(cpu)->stop = stop; 823 824 if (old_stop) { 825 /* 826 * Reset it back to a normal scheduling class so that 827 * it can die in pieces. 828 */ 829 old_stop->sched_class = &rt_sched_class; 830 } 831 } 832 833 /* 834 * __normal_prio - return the priority that is based on the static prio 835 */ 836 static inline int __normal_prio(struct task_struct *p) 837 { 838 return p->static_prio; 839 } 840 841 /* 842 * Calculate the expected normal priority: i.e. priority 843 * without taking RT-inheritance into account. Might be 844 * boosted by interactivity modifiers. Changes upon fork, 845 * setprio syscalls, and whenever the interactivity 846 * estimator recalculates. 847 */ 848 static inline int normal_prio(struct task_struct *p) 849 { 850 int prio; 851 852 if (task_has_rt_policy(p)) 853 prio = MAX_RT_PRIO-1 - p->rt_priority; 854 else 855 prio = __normal_prio(p); 856 return prio; 857 } 858 859 /* 860 * Calculate the current priority, i.e. the priority 861 * taken into account by the scheduler. This value might 862 * be boosted by RT tasks, or might be boosted by 863 * interactivity modifiers. Will be RT if the task got 864 * RT-boosted. If not then it returns p->normal_prio. 865 */ 866 static int effective_prio(struct task_struct *p) 867 { 868 p->normal_prio = normal_prio(p); 869 /* 870 * If we are RT tasks or we were boosted to RT priority, 871 * keep the priority unchanged. Otherwise, update priority 872 * to the normal priority: 873 */ 874 if (!rt_prio(p->prio)) 875 return p->normal_prio; 876 return p->prio; 877 } 878 879 /** 880 * task_curr - is this task currently executing on a CPU? 881 * @p: the task in question. 882 */ 883 inline int task_curr(const struct task_struct *p) 884 { 885 return cpu_curr(task_cpu(p)) == p; 886 } 887 888 static inline void check_class_changed(struct rq *rq, struct task_struct *p, 889 const struct sched_class *prev_class, 890 int oldprio) 891 { 892 if (prev_class != p->sched_class) { 893 if (prev_class->switched_from) 894 prev_class->switched_from(rq, p); 895 p->sched_class->switched_to(rq, p); 896 } else if (oldprio != p->prio) 897 p->sched_class->prio_changed(rq, p, oldprio); 898 } 899 900 void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags) 901 { 902 const struct sched_class *class; 903 904 if (p->sched_class == rq->curr->sched_class) { 905 rq->curr->sched_class->check_preempt_curr(rq, p, flags); 906 } else { 907 for_each_class(class) { 908 if (class == rq->curr->sched_class) 909 break; 910 if (class == p->sched_class) { 911 resched_task(rq->curr); 912 break; 913 } 914 } 915 } 916 917 /* 918 * A queue event has occurred, and we're going to schedule. In 919 * this case, we can save a useless back to back clock update. 920 */ 921 if (rq->curr->on_rq && test_tsk_need_resched(rq->curr)) 922 rq->skip_clock_update = 1; 923 } 924 925 #ifdef CONFIG_SMP 926 void set_task_cpu(struct task_struct *p, unsigned int new_cpu) 927 { 928 #ifdef CONFIG_SCHED_DEBUG 929 /* 930 * We should never call set_task_cpu() on a blocked task, 931 * ttwu() will sort out the placement. 932 */ 933 WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING && 934 !(task_thread_info(p)->preempt_count & PREEMPT_ACTIVE)); 935 936 #ifdef CONFIG_LOCKDEP 937 /* 938 * The caller should hold either p->pi_lock or rq->lock, when changing 939 * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks. 940 * 941 * sched_move_task() holds both and thus holding either pins the cgroup, 942 * see task_group(). 943 * 944 * Furthermore, all task_rq users should acquire both locks, see 945 * task_rq_lock(). 946 */ 947 WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) || 948 lockdep_is_held(&task_rq(p)->lock))); 949 #endif 950 #endif 951 952 trace_sched_migrate_task(p, new_cpu); 953 954 if (task_cpu(p) != new_cpu) { 955 p->se.nr_migrations++; 956 perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, NULL, 0); 957 } 958 959 __set_task_cpu(p, new_cpu); 960 } 961 962 struct migration_arg { 963 struct task_struct *task; 964 int dest_cpu; 965 }; 966 967 static int migration_cpu_stop(void *data); 968 969 /* 970 * wait_task_inactive - wait for a thread to unschedule. 971 * 972 * If @match_state is nonzero, it's the @p->state value just checked and 973 * not expected to change. If it changes, i.e. @p might have woken up, 974 * then return zero. When we succeed in waiting for @p to be off its CPU, 975 * we return a positive number (its total switch count). If a second call 976 * a short while later returns the same number, the caller can be sure that 977 * @p has remained unscheduled the whole time. 978 * 979 * The caller must ensure that the task *will* unschedule sometime soon, 980 * else this function might spin for a *long* time. This function can't 981 * be called with interrupts off, or it may introduce deadlock with 982 * smp_call_function() if an IPI is sent by the same process we are 983 * waiting to become inactive. 984 */ 985 unsigned long wait_task_inactive(struct task_struct *p, long match_state) 986 { 987 unsigned long flags; 988 int running, on_rq; 989 unsigned long ncsw; 990 struct rq *rq; 991 992 for (;;) { 993 /* 994 * We do the initial early heuristics without holding 995 * any task-queue locks at all. We'll only try to get 996 * the runqueue lock when things look like they will 997 * work out! 998 */ 999 rq = task_rq(p); 1000 1001 /* 1002 * If the task is actively running on another CPU 1003 * still, just relax and busy-wait without holding 1004 * any locks. 1005 * 1006 * NOTE! Since we don't hold any locks, it's not 1007 * even sure that "rq" stays as the right runqueue! 1008 * But we don't care, since "task_running()" will 1009 * return false if the runqueue has changed and p 1010 * is actually now running somewhere else! 1011 */ 1012 while (task_running(rq, p)) { 1013 if (match_state && unlikely(p->state != match_state)) 1014 return 0; 1015 cpu_relax(); 1016 } 1017 1018 /* 1019 * Ok, time to look more closely! We need the rq 1020 * lock now, to be *sure*. If we're wrong, we'll 1021 * just go back and repeat. 1022 */ 1023 rq = task_rq_lock(p, &flags); 1024 trace_sched_wait_task(p); 1025 running = task_running(rq, p); 1026 on_rq = p->on_rq; 1027 ncsw = 0; 1028 if (!match_state || p->state == match_state) 1029 ncsw = p->nvcsw | LONG_MIN; /* sets MSB */ 1030 task_rq_unlock(rq, p, &flags); 1031 1032 /* 1033 * If it changed from the expected state, bail out now. 1034 */ 1035 if (unlikely(!ncsw)) 1036 break; 1037 1038 /* 1039 * Was it really running after all now that we 1040 * checked with the proper locks actually held? 1041 * 1042 * Oops. Go back and try again.. 1043 */ 1044 if (unlikely(running)) { 1045 cpu_relax(); 1046 continue; 1047 } 1048 1049 /* 1050 * It's not enough that it's not actively running, 1051 * it must be off the runqueue _entirely_, and not 1052 * preempted! 1053 * 1054 * So if it was still runnable (but just not actively 1055 * running right now), it's preempted, and we should 1056 * yield - it could be a while. 1057 */ 1058 if (unlikely(on_rq)) { 1059 ktime_t to = ktime_set(0, NSEC_PER_SEC/HZ); 1060 1061 set_current_state(TASK_UNINTERRUPTIBLE); 1062 schedule_hrtimeout(&to, HRTIMER_MODE_REL); 1063 continue; 1064 } 1065 1066 /* 1067 * Ahh, all good. It wasn't running, and it wasn't 1068 * runnable, which means that it will never become 1069 * running in the future either. We're all done! 1070 */ 1071 break; 1072 } 1073 1074 return ncsw; 1075 } 1076 1077 /*** 1078 * kick_process - kick a running thread to enter/exit the kernel 1079 * @p: the to-be-kicked thread 1080 * 1081 * Cause a process which is running on another CPU to enter 1082 * kernel-mode, without any delay. (to get signals handled.) 1083 * 1084 * NOTE: this function doesn't have to take the runqueue lock, 1085 * because all it wants to ensure is that the remote task enters 1086 * the kernel. If the IPI races and the task has been migrated 1087 * to another CPU then no harm is done and the purpose has been 1088 * achieved as well. 1089 */ 1090 void kick_process(struct task_struct *p) 1091 { 1092 int cpu; 1093 1094 preempt_disable(); 1095 cpu = task_cpu(p); 1096 if ((cpu != smp_processor_id()) && task_curr(p)) 1097 smp_send_reschedule(cpu); 1098 preempt_enable(); 1099 } 1100 EXPORT_SYMBOL_GPL(kick_process); 1101 #endif /* CONFIG_SMP */ 1102 1103 #ifdef CONFIG_SMP 1104 /* 1105 * ->cpus_allowed is protected by both rq->lock and p->pi_lock 1106 */ 1107 static int select_fallback_rq(int cpu, struct task_struct *p) 1108 { 1109 const struct cpumask *nodemask = cpumask_of_node(cpu_to_node(cpu)); 1110 enum { cpuset, possible, fail } state = cpuset; 1111 int dest_cpu; 1112 1113 /* Look for allowed, online CPU in same node. */ 1114 for_each_cpu(dest_cpu, nodemask) { 1115 if (!cpu_online(dest_cpu)) 1116 continue; 1117 if (!cpu_active(dest_cpu)) 1118 continue; 1119 if (cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p))) 1120 return dest_cpu; 1121 } 1122 1123 for (;;) { 1124 /* Any allowed, online CPU? */ 1125 for_each_cpu(dest_cpu, tsk_cpus_allowed(p)) { 1126 if (!cpu_online(dest_cpu)) 1127 continue; 1128 if (!cpu_active(dest_cpu)) 1129 continue; 1130 goto out; 1131 } 1132 1133 switch (state) { 1134 case cpuset: 1135 /* No more Mr. Nice Guy. */ 1136 cpuset_cpus_allowed_fallback(p); 1137 state = possible; 1138 break; 1139 1140 case possible: 1141 do_set_cpus_allowed(p, cpu_possible_mask); 1142 state = fail; 1143 break; 1144 1145 case fail: 1146 BUG(); 1147 break; 1148 } 1149 } 1150 1151 out: 1152 if (state != cpuset) { 1153 /* 1154 * Don't tell them about moving exiting tasks or 1155 * kernel threads (both mm NULL), since they never 1156 * leave kernel. 1157 */ 1158 if (p->mm && printk_ratelimit()) { 1159 printk_sched("process %d (%s) no longer affine to cpu%d\n", 1160 task_pid_nr(p), p->comm, cpu); 1161 } 1162 } 1163 1164 return dest_cpu; 1165 } 1166 1167 /* 1168 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable. 1169 */ 1170 static inline 1171 int select_task_rq(struct task_struct *p, int sd_flags, int wake_flags) 1172 { 1173 int cpu = p->sched_class->select_task_rq(p, sd_flags, wake_flags); 1174 1175 /* 1176 * In order not to call set_task_cpu() on a blocking task we need 1177 * to rely on ttwu() to place the task on a valid ->cpus_allowed 1178 * cpu. 1179 * 1180 * Since this is common to all placement strategies, this lives here. 1181 * 1182 * [ this allows ->select_task() to simply return task_cpu(p) and 1183 * not worry about this generic constraint ] 1184 */ 1185 if (unlikely(!cpumask_test_cpu(cpu, tsk_cpus_allowed(p)) || 1186 !cpu_online(cpu))) 1187 cpu = select_fallback_rq(task_cpu(p), p); 1188 1189 return cpu; 1190 } 1191 1192 static void update_avg(u64 *avg, u64 sample) 1193 { 1194 s64 diff = sample - *avg; 1195 *avg += diff >> 3; 1196 } 1197 #endif 1198 1199 static void 1200 ttwu_stat(struct task_struct *p, int cpu, int wake_flags) 1201 { 1202 #ifdef CONFIG_SCHEDSTATS 1203 struct rq *rq = this_rq(); 1204 1205 #ifdef CONFIG_SMP 1206 int this_cpu = smp_processor_id(); 1207 1208 if (cpu == this_cpu) { 1209 schedstat_inc(rq, ttwu_local); 1210 schedstat_inc(p, se.statistics.nr_wakeups_local); 1211 } else { 1212 struct sched_domain *sd; 1213 1214 schedstat_inc(p, se.statistics.nr_wakeups_remote); 1215 rcu_read_lock(); 1216 for_each_domain(this_cpu, sd) { 1217 if (cpumask_test_cpu(cpu, sched_domain_span(sd))) { 1218 schedstat_inc(sd, ttwu_wake_remote); 1219 break; 1220 } 1221 } 1222 rcu_read_unlock(); 1223 } 1224 1225 if (wake_flags & WF_MIGRATED) 1226 schedstat_inc(p, se.statistics.nr_wakeups_migrate); 1227 1228 #endif /* CONFIG_SMP */ 1229 1230 schedstat_inc(rq, ttwu_count); 1231 schedstat_inc(p, se.statistics.nr_wakeups); 1232 1233 if (wake_flags & WF_SYNC) 1234 schedstat_inc(p, se.statistics.nr_wakeups_sync); 1235 1236 #endif /* CONFIG_SCHEDSTATS */ 1237 } 1238 1239 static void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags) 1240 { 1241 activate_task(rq, p, en_flags); 1242 p->on_rq = 1; 1243 1244 /* if a worker is waking up, notify workqueue */ 1245 if (p->flags & PF_WQ_WORKER) 1246 wq_worker_waking_up(p, cpu_of(rq)); 1247 } 1248 1249 /* 1250 * Mark the task runnable and perform wakeup-preemption. 1251 */ 1252 static void 1253 ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags) 1254 { 1255 trace_sched_wakeup(p, true); 1256 check_preempt_curr(rq, p, wake_flags); 1257 1258 p->state = TASK_RUNNING; 1259 #ifdef CONFIG_SMP 1260 if (p->sched_class->task_woken) 1261 p->sched_class->task_woken(rq, p); 1262 1263 if (rq->idle_stamp) { 1264 u64 delta = rq->clock - rq->idle_stamp; 1265 u64 max = 2*sysctl_sched_migration_cost; 1266 1267 if (delta > max) 1268 rq->avg_idle = max; 1269 else 1270 update_avg(&rq->avg_idle, delta); 1271 rq->idle_stamp = 0; 1272 } 1273 #endif 1274 } 1275 1276 static void 1277 ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags) 1278 { 1279 #ifdef CONFIG_SMP 1280 if (p->sched_contributes_to_load) 1281 rq->nr_uninterruptible--; 1282 #endif 1283 1284 ttwu_activate(rq, p, ENQUEUE_WAKEUP | ENQUEUE_WAKING); 1285 ttwu_do_wakeup(rq, p, wake_flags); 1286 } 1287 1288 /* 1289 * Called in case the task @p isn't fully descheduled from its runqueue, 1290 * in this case we must do a remote wakeup. Its a 'light' wakeup though, 1291 * since all we need to do is flip p->state to TASK_RUNNING, since 1292 * the task is still ->on_rq. 1293 */ 1294 static int ttwu_remote(struct task_struct *p, int wake_flags) 1295 { 1296 struct rq *rq; 1297 int ret = 0; 1298 1299 rq = __task_rq_lock(p); 1300 if (p->on_rq) { 1301 ttwu_do_wakeup(rq, p, wake_flags); 1302 ret = 1; 1303 } 1304 __task_rq_unlock(rq); 1305 1306 return ret; 1307 } 1308 1309 #ifdef CONFIG_SMP 1310 static void sched_ttwu_pending(void) 1311 { 1312 struct rq *rq = this_rq(); 1313 struct llist_node *llist = llist_del_all(&rq->wake_list); 1314 struct task_struct *p; 1315 1316 raw_spin_lock(&rq->lock); 1317 1318 while (llist) { 1319 p = llist_entry(llist, struct task_struct, wake_entry); 1320 llist = llist_next(llist); 1321 ttwu_do_activate(rq, p, 0); 1322 } 1323 1324 raw_spin_unlock(&rq->lock); 1325 } 1326 1327 void scheduler_ipi(void) 1328 { 1329 if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick()) 1330 return; 1331 1332 /* 1333 * Not all reschedule IPI handlers call irq_enter/irq_exit, since 1334 * traditionally all their work was done from the interrupt return 1335 * path. Now that we actually do some work, we need to make sure 1336 * we do call them. 1337 * 1338 * Some archs already do call them, luckily irq_enter/exit nest 1339 * properly. 1340 * 1341 * Arguably we should visit all archs and update all handlers, 1342 * however a fair share of IPIs are still resched only so this would 1343 * somewhat pessimize the simple resched case. 1344 */ 1345 irq_enter(); 1346 sched_ttwu_pending(); 1347 1348 /* 1349 * Check if someone kicked us for doing the nohz idle load balance. 1350 */ 1351 if (unlikely(got_nohz_idle_kick() && !need_resched())) { 1352 this_rq()->idle_balance = 1; 1353 raise_softirq_irqoff(SCHED_SOFTIRQ); 1354 } 1355 irq_exit(); 1356 } 1357 1358 static void ttwu_queue_remote(struct task_struct *p, int cpu) 1359 { 1360 if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list)) 1361 smp_send_reschedule(cpu); 1362 } 1363 1364 bool cpus_share_cache(int this_cpu, int that_cpu) 1365 { 1366 return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu); 1367 } 1368 #endif /* CONFIG_SMP */ 1369 1370 static void ttwu_queue(struct task_struct *p, int cpu) 1371 { 1372 struct rq *rq = cpu_rq(cpu); 1373 1374 #if defined(CONFIG_SMP) 1375 if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) { 1376 sched_clock_cpu(cpu); /* sync clocks x-cpu */ 1377 ttwu_queue_remote(p, cpu); 1378 return; 1379 } 1380 #endif 1381 1382 raw_spin_lock(&rq->lock); 1383 ttwu_do_activate(rq, p, 0); 1384 raw_spin_unlock(&rq->lock); 1385 } 1386 1387 /** 1388 * try_to_wake_up - wake up a thread 1389 * @p: the thread to be awakened 1390 * @state: the mask of task states that can be woken 1391 * @wake_flags: wake modifier flags (WF_*) 1392 * 1393 * Put it on the run-queue if it's not already there. The "current" 1394 * thread is always on the run-queue (except when the actual 1395 * re-schedule is in progress), and as such you're allowed to do 1396 * the simpler "current->state = TASK_RUNNING" to mark yourself 1397 * runnable without the overhead of this. 1398 * 1399 * Returns %true if @p was woken up, %false if it was already running 1400 * or @state didn't match @p's state. 1401 */ 1402 static int 1403 try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) 1404 { 1405 unsigned long flags; 1406 int cpu, success = 0; 1407 1408 smp_wmb(); 1409 raw_spin_lock_irqsave(&p->pi_lock, flags); 1410 if (!(p->state & state)) 1411 goto out; 1412 1413 success = 1; /* we're going to change ->state */ 1414 cpu = task_cpu(p); 1415 1416 if (p->on_rq && ttwu_remote(p, wake_flags)) 1417 goto stat; 1418 1419 #ifdef CONFIG_SMP 1420 /* 1421 * If the owning (remote) cpu is still in the middle of schedule() with 1422 * this task as prev, wait until its done referencing the task. 1423 */ 1424 while (p->on_cpu) 1425 cpu_relax(); 1426 /* 1427 * Pairs with the smp_wmb() in finish_lock_switch(). 1428 */ 1429 smp_rmb(); 1430 1431 p->sched_contributes_to_load = !!task_contributes_to_load(p); 1432 p->state = TASK_WAKING; 1433 1434 if (p->sched_class->task_waking) 1435 p->sched_class->task_waking(p); 1436 1437 cpu = select_task_rq(p, SD_BALANCE_WAKE, wake_flags); 1438 if (task_cpu(p) != cpu) { 1439 wake_flags |= WF_MIGRATED; 1440 set_task_cpu(p, cpu); 1441 } 1442 #endif /* CONFIG_SMP */ 1443 1444 ttwu_queue(p, cpu); 1445 stat: 1446 ttwu_stat(p, cpu, wake_flags); 1447 out: 1448 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 1449 1450 return success; 1451 } 1452 1453 /** 1454 * try_to_wake_up_local - try to wake up a local task with rq lock held 1455 * @p: the thread to be awakened 1456 * 1457 * Put @p on the run-queue if it's not already there. The caller must 1458 * ensure that this_rq() is locked, @p is bound to this_rq() and not 1459 * the current task. 1460 */ 1461 static void try_to_wake_up_local(struct task_struct *p) 1462 { 1463 struct rq *rq = task_rq(p); 1464 1465 BUG_ON(rq != this_rq()); 1466 BUG_ON(p == current); 1467 lockdep_assert_held(&rq->lock); 1468 1469 if (!raw_spin_trylock(&p->pi_lock)) { 1470 raw_spin_unlock(&rq->lock); 1471 raw_spin_lock(&p->pi_lock); 1472 raw_spin_lock(&rq->lock); 1473 } 1474 1475 if (!(p->state & TASK_NORMAL)) 1476 goto out; 1477 1478 if (!p->on_rq) 1479 ttwu_activate(rq, p, ENQUEUE_WAKEUP); 1480 1481 ttwu_do_wakeup(rq, p, 0); 1482 ttwu_stat(p, smp_processor_id(), 0); 1483 out: 1484 raw_spin_unlock(&p->pi_lock); 1485 } 1486 1487 /** 1488 * wake_up_process - Wake up a specific process 1489 * @p: The process to be woken up. 1490 * 1491 * Attempt to wake up the nominated process and move it to the set of runnable 1492 * processes. Returns 1 if the process was woken up, 0 if it was already 1493 * running. 1494 * 1495 * It may be assumed that this function implies a write memory barrier before 1496 * changing the task state if and only if any tasks are woken up. 1497 */ 1498 int wake_up_process(struct task_struct *p) 1499 { 1500 return try_to_wake_up(p, TASK_ALL, 0); 1501 } 1502 EXPORT_SYMBOL(wake_up_process); 1503 1504 int wake_up_state(struct task_struct *p, unsigned int state) 1505 { 1506 return try_to_wake_up(p, state, 0); 1507 } 1508 1509 /* 1510 * Perform scheduler related setup for a newly forked process p. 1511 * p is forked by current. 1512 * 1513 * __sched_fork() is basic setup used by init_idle() too: 1514 */ 1515 static void __sched_fork(struct task_struct *p) 1516 { 1517 p->on_rq = 0; 1518 1519 p->se.on_rq = 0; 1520 p->se.exec_start = 0; 1521 p->se.sum_exec_runtime = 0; 1522 p->se.prev_sum_exec_runtime = 0; 1523 p->se.nr_migrations = 0; 1524 p->se.vruntime = 0; 1525 INIT_LIST_HEAD(&p->se.group_node); 1526 1527 #ifdef CONFIG_SCHEDSTATS 1528 memset(&p->se.statistics, 0, sizeof(p->se.statistics)); 1529 #endif 1530 1531 INIT_LIST_HEAD(&p->rt.run_list); 1532 1533 #ifdef CONFIG_PREEMPT_NOTIFIERS 1534 INIT_HLIST_HEAD(&p->preempt_notifiers); 1535 #endif 1536 } 1537 1538 /* 1539 * fork()/clone()-time setup: 1540 */ 1541 void sched_fork(struct task_struct *p) 1542 { 1543 unsigned long flags; 1544 int cpu = get_cpu(); 1545 1546 __sched_fork(p); 1547 /* 1548 * We mark the process as running here. This guarantees that 1549 * nobody will actually run it, and a signal or other external 1550 * event cannot wake it up and insert it on the runqueue either. 1551 */ 1552 p->state = TASK_RUNNING; 1553 1554 /* 1555 * Make sure we do not leak PI boosting priority to the child. 1556 */ 1557 p->prio = current->normal_prio; 1558 1559 /* 1560 * Revert to default priority/policy on fork if requested. 1561 */ 1562 if (unlikely(p->sched_reset_on_fork)) { 1563 if (task_has_rt_policy(p)) { 1564 p->policy = SCHED_NORMAL; 1565 p->static_prio = NICE_TO_PRIO(0); 1566 p->rt_priority = 0; 1567 } else if (PRIO_TO_NICE(p->static_prio) < 0) 1568 p->static_prio = NICE_TO_PRIO(0); 1569 1570 p->prio = p->normal_prio = __normal_prio(p); 1571 set_load_weight(p); 1572 1573 /* 1574 * We don't need the reset flag anymore after the fork. It has 1575 * fulfilled its duty: 1576 */ 1577 p->sched_reset_on_fork = 0; 1578 } 1579 1580 if (!rt_prio(p->prio)) 1581 p->sched_class = &fair_sched_class; 1582 1583 if (p->sched_class->task_fork) 1584 p->sched_class->task_fork(p); 1585 1586 /* 1587 * The child is not yet in the pid-hash so no cgroup attach races, 1588 * and the cgroup is pinned to this child due to cgroup_fork() 1589 * is ran before sched_fork(). 1590 * 1591 * Silence PROVE_RCU. 1592 */ 1593 raw_spin_lock_irqsave(&p->pi_lock, flags); 1594 set_task_cpu(p, cpu); 1595 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 1596 1597 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) 1598 if (likely(sched_info_on())) 1599 memset(&p->sched_info, 0, sizeof(p->sched_info)); 1600 #endif 1601 #if defined(CONFIG_SMP) 1602 p->on_cpu = 0; 1603 #endif 1604 #ifdef CONFIG_PREEMPT_COUNT 1605 /* Want to start with kernel preemption disabled. */ 1606 task_thread_info(p)->preempt_count = 1; 1607 #endif 1608 #ifdef CONFIG_SMP 1609 plist_node_init(&p->pushable_tasks, MAX_PRIO); 1610 #endif 1611 1612 put_cpu(); 1613 } 1614 1615 /* 1616 * wake_up_new_task - wake up a newly created task for the first time. 1617 * 1618 * This function will do some initial scheduler statistics housekeeping 1619 * that must be done for every newly created context, then puts the task 1620 * on the runqueue and wakes it. 1621 */ 1622 void wake_up_new_task(struct task_struct *p) 1623 { 1624 unsigned long flags; 1625 struct rq *rq; 1626 1627 raw_spin_lock_irqsave(&p->pi_lock, flags); 1628 #ifdef CONFIG_SMP 1629 /* 1630 * Fork balancing, do it here and not earlier because: 1631 * - cpus_allowed can change in the fork path 1632 * - any previously selected cpu might disappear through hotplug 1633 */ 1634 set_task_cpu(p, select_task_rq(p, SD_BALANCE_FORK, 0)); 1635 #endif 1636 1637 rq = __task_rq_lock(p); 1638 activate_task(rq, p, 0); 1639 p->on_rq = 1; 1640 trace_sched_wakeup_new(p, true); 1641 check_preempt_curr(rq, p, WF_FORK); 1642 #ifdef CONFIG_SMP 1643 if (p->sched_class->task_woken) 1644 p->sched_class->task_woken(rq, p); 1645 #endif 1646 task_rq_unlock(rq, p, &flags); 1647 } 1648 1649 #ifdef CONFIG_PREEMPT_NOTIFIERS 1650 1651 /** 1652 * preempt_notifier_register - tell me when current is being preempted & rescheduled 1653 * @notifier: notifier struct to register 1654 */ 1655 void preempt_notifier_register(struct preempt_notifier *notifier) 1656 { 1657 hlist_add_head(¬ifier->link, ¤t->preempt_notifiers); 1658 } 1659 EXPORT_SYMBOL_GPL(preempt_notifier_register); 1660 1661 /** 1662 * preempt_notifier_unregister - no longer interested in preemption notifications 1663 * @notifier: notifier struct to unregister 1664 * 1665 * This is safe to call from within a preemption notifier. 1666 */ 1667 void preempt_notifier_unregister(struct preempt_notifier *notifier) 1668 { 1669 hlist_del(¬ifier->link); 1670 } 1671 EXPORT_SYMBOL_GPL(preempt_notifier_unregister); 1672 1673 static void fire_sched_in_preempt_notifiers(struct task_struct *curr) 1674 { 1675 struct preempt_notifier *notifier; 1676 struct hlist_node *node; 1677 1678 hlist_for_each_entry(notifier, node, &curr->preempt_notifiers, link) 1679 notifier->ops->sched_in(notifier, raw_smp_processor_id()); 1680 } 1681 1682 static void 1683 fire_sched_out_preempt_notifiers(struct task_struct *curr, 1684 struct task_struct *next) 1685 { 1686 struct preempt_notifier *notifier; 1687 struct hlist_node *node; 1688 1689 hlist_for_each_entry(notifier, node, &curr->preempt_notifiers, link) 1690 notifier->ops->sched_out(notifier, next); 1691 } 1692 1693 #else /* !CONFIG_PREEMPT_NOTIFIERS */ 1694 1695 static void fire_sched_in_preempt_notifiers(struct task_struct *curr) 1696 { 1697 } 1698 1699 static void 1700 fire_sched_out_preempt_notifiers(struct task_struct *curr, 1701 struct task_struct *next) 1702 { 1703 } 1704 1705 #endif /* CONFIG_PREEMPT_NOTIFIERS */ 1706 1707 /** 1708 * prepare_task_switch - prepare to switch tasks 1709 * @rq: the runqueue preparing to switch 1710 * @prev: the current task that is being switched out 1711 * @next: the task we are going to switch to. 1712 * 1713 * This is called with the rq lock held and interrupts off. It must 1714 * be paired with a subsequent finish_task_switch after the context 1715 * switch. 1716 * 1717 * prepare_task_switch sets up locking and calls architecture specific 1718 * hooks. 1719 */ 1720 static inline void 1721 prepare_task_switch(struct rq *rq, struct task_struct *prev, 1722 struct task_struct *next) 1723 { 1724 trace_sched_switch(prev, next); 1725 sched_info_switch(prev, next); 1726 perf_event_task_sched_out(prev, next); 1727 fire_sched_out_preempt_notifiers(prev, next); 1728 prepare_lock_switch(rq, next); 1729 prepare_arch_switch(next); 1730 } 1731 1732 /** 1733 * finish_task_switch - clean up after a task-switch 1734 * @rq: runqueue associated with task-switch 1735 * @prev: the thread we just switched away from. 1736 * 1737 * finish_task_switch must be called after the context switch, paired 1738 * with a prepare_task_switch call before the context switch. 1739 * finish_task_switch will reconcile locking set up by prepare_task_switch, 1740 * and do any other architecture-specific cleanup actions. 1741 * 1742 * Note that we may have delayed dropping an mm in context_switch(). If 1743 * so, we finish that here outside of the runqueue lock. (Doing it 1744 * with the lock held can cause deadlocks; see schedule() for 1745 * details.) 1746 */ 1747 static void finish_task_switch(struct rq *rq, struct task_struct *prev) 1748 __releases(rq->lock) 1749 { 1750 struct mm_struct *mm = rq->prev_mm; 1751 long prev_state; 1752 1753 rq->prev_mm = NULL; 1754 1755 /* 1756 * A task struct has one reference for the use as "current". 1757 * If a task dies, then it sets TASK_DEAD in tsk->state and calls 1758 * schedule one last time. The schedule call will never return, and 1759 * the scheduled task must drop that reference. 1760 * The test for TASK_DEAD must occur while the runqueue locks are 1761 * still held, otherwise prev could be scheduled on another cpu, die 1762 * there before we look at prev->state, and then the reference would 1763 * be dropped twice. 1764 * Manfred Spraul <manfred@colorfullife.com> 1765 */ 1766 prev_state = prev->state; 1767 vtime_task_switch(prev); 1768 finish_arch_switch(prev); 1769 perf_event_task_sched_in(prev, current); 1770 finish_lock_switch(rq, prev); 1771 finish_arch_post_lock_switch(); 1772 1773 fire_sched_in_preempt_notifiers(current); 1774 if (mm) 1775 mmdrop(mm); 1776 if (unlikely(prev_state == TASK_DEAD)) { 1777 /* 1778 * Remove function-return probe instances associated with this 1779 * task and put them back on the free list. 1780 */ 1781 kprobe_flush_task(prev); 1782 put_task_struct(prev); 1783 } 1784 } 1785 1786 #ifdef CONFIG_SMP 1787 1788 /* assumes rq->lock is held */ 1789 static inline void pre_schedule(struct rq *rq, struct task_struct *prev) 1790 { 1791 if (prev->sched_class->pre_schedule) 1792 prev->sched_class->pre_schedule(rq, prev); 1793 } 1794 1795 /* rq->lock is NOT held, but preemption is disabled */ 1796 static inline void post_schedule(struct rq *rq) 1797 { 1798 if (rq->post_schedule) { 1799 unsigned long flags; 1800 1801 raw_spin_lock_irqsave(&rq->lock, flags); 1802 if (rq->curr->sched_class->post_schedule) 1803 rq->curr->sched_class->post_schedule(rq); 1804 raw_spin_unlock_irqrestore(&rq->lock, flags); 1805 1806 rq->post_schedule = 0; 1807 } 1808 } 1809 1810 #else 1811 1812 static inline void pre_schedule(struct rq *rq, struct task_struct *p) 1813 { 1814 } 1815 1816 static inline void post_schedule(struct rq *rq) 1817 { 1818 } 1819 1820 #endif 1821 1822 /** 1823 * schedule_tail - first thing a freshly forked thread must call. 1824 * @prev: the thread we just switched away from. 1825 */ 1826 asmlinkage void schedule_tail(struct task_struct *prev) 1827 __releases(rq->lock) 1828 { 1829 struct rq *rq = this_rq(); 1830 1831 finish_task_switch(rq, prev); 1832 1833 /* 1834 * FIXME: do we need to worry about rq being invalidated by the 1835 * task_switch? 1836 */ 1837 post_schedule(rq); 1838 1839 #ifdef __ARCH_WANT_UNLOCKED_CTXSW 1840 /* In this case, finish_task_switch does not reenable preemption */ 1841 preempt_enable(); 1842 #endif 1843 if (current->set_child_tid) 1844 put_user(task_pid_vnr(current), current->set_child_tid); 1845 } 1846 1847 /* 1848 * context_switch - switch to the new MM and the new 1849 * thread's register state. 1850 */ 1851 static inline void 1852 context_switch(struct rq *rq, struct task_struct *prev, 1853 struct task_struct *next) 1854 { 1855 struct mm_struct *mm, *oldmm; 1856 1857 prepare_task_switch(rq, prev, next); 1858 1859 mm = next->mm; 1860 oldmm = prev->active_mm; 1861 /* 1862 * For paravirt, this is coupled with an exit in switch_to to 1863 * combine the page table reload and the switch backend into 1864 * one hypercall. 1865 */ 1866 arch_start_context_switch(prev); 1867 1868 if (!mm) { 1869 next->active_mm = oldmm; 1870 atomic_inc(&oldmm->mm_count); 1871 enter_lazy_tlb(oldmm, next); 1872 } else 1873 switch_mm(oldmm, mm, next); 1874 1875 if (!prev->mm) { 1876 prev->active_mm = NULL; 1877 rq->prev_mm = oldmm; 1878 } 1879 /* 1880 * Since the runqueue lock will be released by the next 1881 * task (which is an invalid locking op but in the case 1882 * of the scheduler it's an obvious special-case), so we 1883 * do an early lockdep release here: 1884 */ 1885 #ifndef __ARCH_WANT_UNLOCKED_CTXSW 1886 spin_release(&rq->lock.dep_map, 1, _THIS_IP_); 1887 #endif 1888 1889 /* Here we just switch the register state and the stack. */ 1890 rcu_switch(prev, next); 1891 switch_to(prev, next, prev); 1892 1893 barrier(); 1894 /* 1895 * this_rq must be evaluated again because prev may have moved 1896 * CPUs since it called schedule(), thus the 'rq' on its stack 1897 * frame will be invalid. 1898 */ 1899 finish_task_switch(this_rq(), prev); 1900 } 1901 1902 /* 1903 * nr_running, nr_uninterruptible and nr_context_switches: 1904 * 1905 * externally visible scheduler statistics: current number of runnable 1906 * threads, current number of uninterruptible-sleeping threads, total 1907 * number of context switches performed since bootup. 1908 */ 1909 unsigned long nr_running(void) 1910 { 1911 unsigned long i, sum = 0; 1912 1913 for_each_online_cpu(i) 1914 sum += cpu_rq(i)->nr_running; 1915 1916 return sum; 1917 } 1918 1919 unsigned long nr_uninterruptible(void) 1920 { 1921 unsigned long i, sum = 0; 1922 1923 for_each_possible_cpu(i) 1924 sum += cpu_rq(i)->nr_uninterruptible; 1925 1926 /* 1927 * Since we read the counters lockless, it might be slightly 1928 * inaccurate. Do not allow it to go below zero though: 1929 */ 1930 if (unlikely((long)sum < 0)) 1931 sum = 0; 1932 1933 return sum; 1934 } 1935 1936 unsigned long long nr_context_switches(void) 1937 { 1938 int i; 1939 unsigned long long sum = 0; 1940 1941 for_each_possible_cpu(i) 1942 sum += cpu_rq(i)->nr_switches; 1943 1944 return sum; 1945 } 1946 1947 unsigned long nr_iowait(void) 1948 { 1949 unsigned long i, sum = 0; 1950 1951 for_each_possible_cpu(i) 1952 sum += atomic_read(&cpu_rq(i)->nr_iowait); 1953 1954 return sum; 1955 } 1956 1957 unsigned long nr_iowait_cpu(int cpu) 1958 { 1959 struct rq *this = cpu_rq(cpu); 1960 return atomic_read(&this->nr_iowait); 1961 } 1962 1963 unsigned long this_cpu_load(void) 1964 { 1965 struct rq *this = this_rq(); 1966 return this->cpu_load[0]; 1967 } 1968 1969 1970 /* 1971 * Global load-average calculations 1972 * 1973 * We take a distributed and async approach to calculating the global load-avg 1974 * in order to minimize overhead. 1975 * 1976 * The global load average is an exponentially decaying average of nr_running + 1977 * nr_uninterruptible. 1978 * 1979 * Once every LOAD_FREQ: 1980 * 1981 * nr_active = 0; 1982 * for_each_possible_cpu(cpu) 1983 * nr_active += cpu_of(cpu)->nr_running + cpu_of(cpu)->nr_uninterruptible; 1984 * 1985 * avenrun[n] = avenrun[0] * exp_n + nr_active * (1 - exp_n) 1986 * 1987 * Due to a number of reasons the above turns in the mess below: 1988 * 1989 * - for_each_possible_cpu() is prohibitively expensive on machines with 1990 * serious number of cpus, therefore we need to take a distributed approach 1991 * to calculating nr_active. 1992 * 1993 * \Sum_i x_i(t) = \Sum_i x_i(t) - x_i(t_0) | x_i(t_0) := 0 1994 * = \Sum_i { \Sum_j=1 x_i(t_j) - x_i(t_j-1) } 1995 * 1996 * So assuming nr_active := 0 when we start out -- true per definition, we 1997 * can simply take per-cpu deltas and fold those into a global accumulate 1998 * to obtain the same result. See calc_load_fold_active(). 1999 * 2000 * Furthermore, in order to avoid synchronizing all per-cpu delta folding 2001 * across the machine, we assume 10 ticks is sufficient time for every 2002 * cpu to have completed this task. 2003 * 2004 * This places an upper-bound on the IRQ-off latency of the machine. Then 2005 * again, being late doesn't loose the delta, just wrecks the sample. 2006 * 2007 * - cpu_rq()->nr_uninterruptible isn't accurately tracked per-cpu because 2008 * this would add another cross-cpu cacheline miss and atomic operation 2009 * to the wakeup path. Instead we increment on whatever cpu the task ran 2010 * when it went into uninterruptible state and decrement on whatever cpu 2011 * did the wakeup. This means that only the sum of nr_uninterruptible over 2012 * all cpus yields the correct result. 2013 * 2014 * This covers the NO_HZ=n code, for extra head-aches, see the comment below. 2015 */ 2016 2017 /* Variables and functions for calc_load */ 2018 static atomic_long_t calc_load_tasks; 2019 static unsigned long calc_load_update; 2020 unsigned long avenrun[3]; 2021 EXPORT_SYMBOL(avenrun); /* should be removed */ 2022 2023 /** 2024 * get_avenrun - get the load average array 2025 * @loads: pointer to dest load array 2026 * @offset: offset to add 2027 * @shift: shift count to shift the result left 2028 * 2029 * These values are estimates at best, so no need for locking. 2030 */ 2031 void get_avenrun(unsigned long *loads, unsigned long offset, int shift) 2032 { 2033 loads[0] = (avenrun[0] + offset) << shift; 2034 loads[1] = (avenrun[1] + offset) << shift; 2035 loads[2] = (avenrun[2] + offset) << shift; 2036 } 2037 2038 static long calc_load_fold_active(struct rq *this_rq) 2039 { 2040 long nr_active, delta = 0; 2041 2042 nr_active = this_rq->nr_running; 2043 nr_active += (long) this_rq->nr_uninterruptible; 2044 2045 if (nr_active != this_rq->calc_load_active) { 2046 delta = nr_active - this_rq->calc_load_active; 2047 this_rq->calc_load_active = nr_active; 2048 } 2049 2050 return delta; 2051 } 2052 2053 /* 2054 * a1 = a0 * e + a * (1 - e) 2055 */ 2056 static unsigned long 2057 calc_load(unsigned long load, unsigned long exp, unsigned long active) 2058 { 2059 load *= exp; 2060 load += active * (FIXED_1 - exp); 2061 load += 1UL << (FSHIFT - 1); 2062 return load >> FSHIFT; 2063 } 2064 2065 #ifdef CONFIG_NO_HZ 2066 /* 2067 * Handle NO_HZ for the global load-average. 2068 * 2069 * Since the above described distributed algorithm to compute the global 2070 * load-average relies on per-cpu sampling from the tick, it is affected by 2071 * NO_HZ. 2072 * 2073 * The basic idea is to fold the nr_active delta into a global idle-delta upon 2074 * entering NO_HZ state such that we can include this as an 'extra' cpu delta 2075 * when we read the global state. 2076 * 2077 * Obviously reality has to ruin such a delightfully simple scheme: 2078 * 2079 * - When we go NO_HZ idle during the window, we can negate our sample 2080 * contribution, causing under-accounting. 2081 * 2082 * We avoid this by keeping two idle-delta counters and flipping them 2083 * when the window starts, thus separating old and new NO_HZ load. 2084 * 2085 * The only trick is the slight shift in index flip for read vs write. 2086 * 2087 * 0s 5s 10s 15s 2088 * +10 +10 +10 +10 2089 * |-|-----------|-|-----------|-|-----------|-| 2090 * r:0 0 1 1 0 0 1 1 0 2091 * w:0 1 1 0 0 1 1 0 0 2092 * 2093 * This ensures we'll fold the old idle contribution in this window while 2094 * accumlating the new one. 2095 * 2096 * - When we wake up from NO_HZ idle during the window, we push up our 2097 * contribution, since we effectively move our sample point to a known 2098 * busy state. 2099 * 2100 * This is solved by pushing the window forward, and thus skipping the 2101 * sample, for this cpu (effectively using the idle-delta for this cpu which 2102 * was in effect at the time the window opened). This also solves the issue 2103 * of having to deal with a cpu having been in NOHZ idle for multiple 2104 * LOAD_FREQ intervals. 2105 * 2106 * When making the ILB scale, we should try to pull this in as well. 2107 */ 2108 static atomic_long_t calc_load_idle[2]; 2109 static int calc_load_idx; 2110 2111 static inline int calc_load_write_idx(void) 2112 { 2113 int idx = calc_load_idx; 2114 2115 /* 2116 * See calc_global_nohz(), if we observe the new index, we also 2117 * need to observe the new update time. 2118 */ 2119 smp_rmb(); 2120 2121 /* 2122 * If the folding window started, make sure we start writing in the 2123 * next idle-delta. 2124 */ 2125 if (!time_before(jiffies, calc_load_update)) 2126 idx++; 2127 2128 return idx & 1; 2129 } 2130 2131 static inline int calc_load_read_idx(void) 2132 { 2133 return calc_load_idx & 1; 2134 } 2135 2136 void calc_load_enter_idle(void) 2137 { 2138 struct rq *this_rq = this_rq(); 2139 long delta; 2140 2141 /* 2142 * We're going into NOHZ mode, if there's any pending delta, fold it 2143 * into the pending idle delta. 2144 */ 2145 delta = calc_load_fold_active(this_rq); 2146 if (delta) { 2147 int idx = calc_load_write_idx(); 2148 atomic_long_add(delta, &calc_load_idle[idx]); 2149 } 2150 } 2151 2152 void calc_load_exit_idle(void) 2153 { 2154 struct rq *this_rq = this_rq(); 2155 2156 /* 2157 * If we're still before the sample window, we're done. 2158 */ 2159 if (time_before(jiffies, this_rq->calc_load_update)) 2160 return; 2161 2162 /* 2163 * We woke inside or after the sample window, this means we're already 2164 * accounted through the nohz accounting, so skip the entire deal and 2165 * sync up for the next window. 2166 */ 2167 this_rq->calc_load_update = calc_load_update; 2168 if (time_before(jiffies, this_rq->calc_load_update + 10)) 2169 this_rq->calc_load_update += LOAD_FREQ; 2170 } 2171 2172 static long calc_load_fold_idle(void) 2173 { 2174 int idx = calc_load_read_idx(); 2175 long delta = 0; 2176 2177 if (atomic_long_read(&calc_load_idle[idx])) 2178 delta = atomic_long_xchg(&calc_load_idle[idx], 0); 2179 2180 return delta; 2181 } 2182 2183 /** 2184 * fixed_power_int - compute: x^n, in O(log n) time 2185 * 2186 * @x: base of the power 2187 * @frac_bits: fractional bits of @x 2188 * @n: power to raise @x to. 2189 * 2190 * By exploiting the relation between the definition of the natural power 2191 * function: x^n := x*x*...*x (x multiplied by itself for n times), and 2192 * the binary encoding of numbers used by computers: n := \Sum n_i * 2^i, 2193 * (where: n_i \elem {0, 1}, the binary vector representing n), 2194 * we find: x^n := x^(\Sum n_i * 2^i) := \Prod x^(n_i * 2^i), which is 2195 * of course trivially computable in O(log_2 n), the length of our binary 2196 * vector. 2197 */ 2198 static unsigned long 2199 fixed_power_int(unsigned long x, unsigned int frac_bits, unsigned int n) 2200 { 2201 unsigned long result = 1UL << frac_bits; 2202 2203 if (n) for (;;) { 2204 if (n & 1) { 2205 result *= x; 2206 result += 1UL << (frac_bits - 1); 2207 result >>= frac_bits; 2208 } 2209 n >>= 1; 2210 if (!n) 2211 break; 2212 x *= x; 2213 x += 1UL << (frac_bits - 1); 2214 x >>= frac_bits; 2215 } 2216 2217 return result; 2218 } 2219 2220 /* 2221 * a1 = a0 * e + a * (1 - e) 2222 * 2223 * a2 = a1 * e + a * (1 - e) 2224 * = (a0 * e + a * (1 - e)) * e + a * (1 - e) 2225 * = a0 * e^2 + a * (1 - e) * (1 + e) 2226 * 2227 * a3 = a2 * e + a * (1 - e) 2228 * = (a0 * e^2 + a * (1 - e) * (1 + e)) * e + a * (1 - e) 2229 * = a0 * e^3 + a * (1 - e) * (1 + e + e^2) 2230 * 2231 * ... 2232 * 2233 * an = a0 * e^n + a * (1 - e) * (1 + e + ... + e^n-1) [1] 2234 * = a0 * e^n + a * (1 - e) * (1 - e^n)/(1 - e) 2235 * = a0 * e^n + a * (1 - e^n) 2236 * 2237 * [1] application of the geometric series: 2238 * 2239 * n 1 - x^(n+1) 2240 * S_n := \Sum x^i = ------------- 2241 * i=0 1 - x 2242 */ 2243 static unsigned long 2244 calc_load_n(unsigned long load, unsigned long exp, 2245 unsigned long active, unsigned int n) 2246 { 2247 2248 return calc_load(load, fixed_power_int(exp, FSHIFT, n), active); 2249 } 2250 2251 /* 2252 * NO_HZ can leave us missing all per-cpu ticks calling 2253 * calc_load_account_active(), but since an idle CPU folds its delta into 2254 * calc_load_tasks_idle per calc_load_account_idle(), all we need to do is fold 2255 * in the pending idle delta if our idle period crossed a load cycle boundary. 2256 * 2257 * Once we've updated the global active value, we need to apply the exponential 2258 * weights adjusted to the number of cycles missed. 2259 */ 2260 static void calc_global_nohz(void) 2261 { 2262 long delta, active, n; 2263 2264 if (!time_before(jiffies, calc_load_update + 10)) { 2265 /* 2266 * Catch-up, fold however many we are behind still 2267 */ 2268 delta = jiffies - calc_load_update - 10; 2269 n = 1 + (delta / LOAD_FREQ); 2270 2271 active = atomic_long_read(&calc_load_tasks); 2272 active = active > 0 ? active * FIXED_1 : 0; 2273 2274 avenrun[0] = calc_load_n(avenrun[0], EXP_1, active, n); 2275 avenrun[1] = calc_load_n(avenrun[1], EXP_5, active, n); 2276 avenrun[2] = calc_load_n(avenrun[2], EXP_15, active, n); 2277 2278 calc_load_update += n * LOAD_FREQ; 2279 } 2280 2281 /* 2282 * Flip the idle index... 2283 * 2284 * Make sure we first write the new time then flip the index, so that 2285 * calc_load_write_idx() will see the new time when it reads the new 2286 * index, this avoids a double flip messing things up. 2287 */ 2288 smp_wmb(); 2289 calc_load_idx++; 2290 } 2291 #else /* !CONFIG_NO_HZ */ 2292 2293 static inline long calc_load_fold_idle(void) { return 0; } 2294 static inline void calc_global_nohz(void) { } 2295 2296 #endif /* CONFIG_NO_HZ */ 2297 2298 /* 2299 * calc_load - update the avenrun load estimates 10 ticks after the 2300 * CPUs have updated calc_load_tasks. 2301 */ 2302 void calc_global_load(unsigned long ticks) 2303 { 2304 long active, delta; 2305 2306 if (time_before(jiffies, calc_load_update + 10)) 2307 return; 2308 2309 /* 2310 * Fold the 'old' idle-delta to include all NO_HZ cpus. 2311 */ 2312 delta = calc_load_fold_idle(); 2313 if (delta) 2314 atomic_long_add(delta, &calc_load_tasks); 2315 2316 active = atomic_long_read(&calc_load_tasks); 2317 active = active > 0 ? active * FIXED_1 : 0; 2318 2319 avenrun[0] = calc_load(avenrun[0], EXP_1, active); 2320 avenrun[1] = calc_load(avenrun[1], EXP_5, active); 2321 avenrun[2] = calc_load(avenrun[2], EXP_15, active); 2322 2323 calc_load_update += LOAD_FREQ; 2324 2325 /* 2326 * In case we idled for multiple LOAD_FREQ intervals, catch up in bulk. 2327 */ 2328 calc_global_nohz(); 2329 } 2330 2331 /* 2332 * Called from update_cpu_load() to periodically update this CPU's 2333 * active count. 2334 */ 2335 static void calc_load_account_active(struct rq *this_rq) 2336 { 2337 long delta; 2338 2339 if (time_before(jiffies, this_rq->calc_load_update)) 2340 return; 2341 2342 delta = calc_load_fold_active(this_rq); 2343 if (delta) 2344 atomic_long_add(delta, &calc_load_tasks); 2345 2346 this_rq->calc_load_update += LOAD_FREQ; 2347 } 2348 2349 /* 2350 * End of global load-average stuff 2351 */ 2352 2353 /* 2354 * The exact cpuload at various idx values, calculated at every tick would be 2355 * load = (2^idx - 1) / 2^idx * load + 1 / 2^idx * cur_load 2356 * 2357 * If a cpu misses updates for n-1 ticks (as it was idle) and update gets called 2358 * on nth tick when cpu may be busy, then we have: 2359 * load = ((2^idx - 1) / 2^idx)^(n-1) * load 2360 * load = (2^idx - 1) / 2^idx) * load + 1 / 2^idx * cur_load 2361 * 2362 * decay_load_missed() below does efficient calculation of 2363 * load = ((2^idx - 1) / 2^idx)^(n-1) * load 2364 * avoiding 0..n-1 loop doing load = ((2^idx - 1) / 2^idx) * load 2365 * 2366 * The calculation is approximated on a 128 point scale. 2367 * degrade_zero_ticks is the number of ticks after which load at any 2368 * particular idx is approximated to be zero. 2369 * degrade_factor is a precomputed table, a row for each load idx. 2370 * Each column corresponds to degradation factor for a power of two ticks, 2371 * based on 128 point scale. 2372 * Example: 2373 * row 2, col 3 (=12) says that the degradation at load idx 2 after 2374 * 8 ticks is 12/128 (which is an approximation of exact factor 3^8/4^8). 2375 * 2376 * With this power of 2 load factors, we can degrade the load n times 2377 * by looking at 1 bits in n and doing as many mult/shift instead of 2378 * n mult/shifts needed by the exact degradation. 2379 */ 2380 #define DEGRADE_SHIFT 7 2381 static const unsigned char 2382 degrade_zero_ticks[CPU_LOAD_IDX_MAX] = {0, 8, 32, 64, 128}; 2383 static const unsigned char 2384 degrade_factor[CPU_LOAD_IDX_MAX][DEGRADE_SHIFT + 1] = { 2385 {0, 0, 0, 0, 0, 0, 0, 0}, 2386 {64, 32, 8, 0, 0, 0, 0, 0}, 2387 {96, 72, 40, 12, 1, 0, 0}, 2388 {112, 98, 75, 43, 15, 1, 0}, 2389 {120, 112, 98, 76, 45, 16, 2} }; 2390 2391 /* 2392 * Update cpu_load for any missed ticks, due to tickless idle. The backlog 2393 * would be when CPU is idle and so we just decay the old load without 2394 * adding any new load. 2395 */ 2396 static unsigned long 2397 decay_load_missed(unsigned long load, unsigned long missed_updates, int idx) 2398 { 2399 int j = 0; 2400 2401 if (!missed_updates) 2402 return load; 2403 2404 if (missed_updates >= degrade_zero_ticks[idx]) 2405 return 0; 2406 2407 if (idx == 1) 2408 return load >> missed_updates; 2409 2410 while (missed_updates) { 2411 if (missed_updates % 2) 2412 load = (load * degrade_factor[idx][j]) >> DEGRADE_SHIFT; 2413 2414 missed_updates >>= 1; 2415 j++; 2416 } 2417 return load; 2418 } 2419 2420 /* 2421 * Update rq->cpu_load[] statistics. This function is usually called every 2422 * scheduler tick (TICK_NSEC). With tickless idle this will not be called 2423 * every tick. We fix it up based on jiffies. 2424 */ 2425 static void __update_cpu_load(struct rq *this_rq, unsigned long this_load, 2426 unsigned long pending_updates) 2427 { 2428 int i, scale; 2429 2430 this_rq->nr_load_updates++; 2431 2432 /* Update our load: */ 2433 this_rq->cpu_load[0] = this_load; /* Fasttrack for idx 0 */ 2434 for (i = 1, scale = 2; i < CPU_LOAD_IDX_MAX; i++, scale += scale) { 2435 unsigned long old_load, new_load; 2436 2437 /* scale is effectively 1 << i now, and >> i divides by scale */ 2438 2439 old_load = this_rq->cpu_load[i]; 2440 old_load = decay_load_missed(old_load, pending_updates - 1, i); 2441 new_load = this_load; 2442 /* 2443 * Round up the averaging division if load is increasing. This 2444 * prevents us from getting stuck on 9 if the load is 10, for 2445 * example. 2446 */ 2447 if (new_load > old_load) 2448 new_load += scale - 1; 2449 2450 this_rq->cpu_load[i] = (old_load * (scale - 1) + new_load) >> i; 2451 } 2452 2453 sched_avg_update(this_rq); 2454 } 2455 2456 #ifdef CONFIG_NO_HZ 2457 /* 2458 * There is no sane way to deal with nohz on smp when using jiffies because the 2459 * cpu doing the jiffies update might drift wrt the cpu doing the jiffy reading 2460 * causing off-by-one errors in observed deltas; {0,2} instead of {1,1}. 2461 * 2462 * Therefore we cannot use the delta approach from the regular tick since that 2463 * would seriously skew the load calculation. However we'll make do for those 2464 * updates happening while idle (nohz_idle_balance) or coming out of idle 2465 * (tick_nohz_idle_exit). 2466 * 2467 * This means we might still be one tick off for nohz periods. 2468 */ 2469 2470 /* 2471 * Called from nohz_idle_balance() to update the load ratings before doing the 2472 * idle balance. 2473 */ 2474 void update_idle_cpu_load(struct rq *this_rq) 2475 { 2476 unsigned long curr_jiffies = ACCESS_ONCE(jiffies); 2477 unsigned long load = this_rq->load.weight; 2478 unsigned long pending_updates; 2479 2480 /* 2481 * bail if there's load or we're actually up-to-date. 2482 */ 2483 if (load || curr_jiffies == this_rq->last_load_update_tick) 2484 return; 2485 2486 pending_updates = curr_jiffies - this_rq->last_load_update_tick; 2487 this_rq->last_load_update_tick = curr_jiffies; 2488 2489 __update_cpu_load(this_rq, load, pending_updates); 2490 } 2491 2492 /* 2493 * Called from tick_nohz_idle_exit() -- try and fix up the ticks we missed. 2494 */ 2495 void update_cpu_load_nohz(void) 2496 { 2497 struct rq *this_rq = this_rq(); 2498 unsigned long curr_jiffies = ACCESS_ONCE(jiffies); 2499 unsigned long pending_updates; 2500 2501 if (curr_jiffies == this_rq->last_load_update_tick) 2502 return; 2503 2504 raw_spin_lock(&this_rq->lock); 2505 pending_updates = curr_jiffies - this_rq->last_load_update_tick; 2506 if (pending_updates) { 2507 this_rq->last_load_update_tick = curr_jiffies; 2508 /* 2509 * We were idle, this means load 0, the current load might be 2510 * !0 due to remote wakeups and the sort. 2511 */ 2512 __update_cpu_load(this_rq, 0, pending_updates); 2513 } 2514 raw_spin_unlock(&this_rq->lock); 2515 } 2516 #endif /* CONFIG_NO_HZ */ 2517 2518 /* 2519 * Called from scheduler_tick() 2520 */ 2521 static void update_cpu_load_active(struct rq *this_rq) 2522 { 2523 /* 2524 * See the mess around update_idle_cpu_load() / update_cpu_load_nohz(). 2525 */ 2526 this_rq->last_load_update_tick = jiffies; 2527 __update_cpu_load(this_rq, this_rq->load.weight, 1); 2528 2529 calc_load_account_active(this_rq); 2530 } 2531 2532 #ifdef CONFIG_SMP 2533 2534 /* 2535 * sched_exec - execve() is a valuable balancing opportunity, because at 2536 * this point the task has the smallest effective memory and cache footprint. 2537 */ 2538 void sched_exec(void) 2539 { 2540 struct task_struct *p = current; 2541 unsigned long flags; 2542 int dest_cpu; 2543 2544 raw_spin_lock_irqsave(&p->pi_lock, flags); 2545 dest_cpu = p->sched_class->select_task_rq(p, SD_BALANCE_EXEC, 0); 2546 if (dest_cpu == smp_processor_id()) 2547 goto unlock; 2548 2549 if (likely(cpu_active(dest_cpu))) { 2550 struct migration_arg arg = { p, dest_cpu }; 2551 2552 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 2553 stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg); 2554 return; 2555 } 2556 unlock: 2557 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 2558 } 2559 2560 #endif 2561 2562 DEFINE_PER_CPU(struct kernel_stat, kstat); 2563 DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat); 2564 2565 EXPORT_PER_CPU_SYMBOL(kstat); 2566 EXPORT_PER_CPU_SYMBOL(kernel_cpustat); 2567 2568 /* 2569 * Return any ns on the sched_clock that have not yet been accounted in 2570 * @p in case that task is currently running. 2571 * 2572 * Called with task_rq_lock() held on @rq. 2573 */ 2574 static u64 do_task_delta_exec(struct task_struct *p, struct rq *rq) 2575 { 2576 u64 ns = 0; 2577 2578 if (task_current(rq, p)) { 2579 update_rq_clock(rq); 2580 ns = rq->clock_task - p->se.exec_start; 2581 if ((s64)ns < 0) 2582 ns = 0; 2583 } 2584 2585 return ns; 2586 } 2587 2588 unsigned long long task_delta_exec(struct task_struct *p) 2589 { 2590 unsigned long flags; 2591 struct rq *rq; 2592 u64 ns = 0; 2593 2594 rq = task_rq_lock(p, &flags); 2595 ns = do_task_delta_exec(p, rq); 2596 task_rq_unlock(rq, p, &flags); 2597 2598 return ns; 2599 } 2600 2601 /* 2602 * Return accounted runtime for the task. 2603 * In case the task is currently running, return the runtime plus current's 2604 * pending runtime that have not been accounted yet. 2605 */ 2606 unsigned long long task_sched_runtime(struct task_struct *p) 2607 { 2608 unsigned long flags; 2609 struct rq *rq; 2610 u64 ns = 0; 2611 2612 rq = task_rq_lock(p, &flags); 2613 ns = p->se.sum_exec_runtime + do_task_delta_exec(p, rq); 2614 task_rq_unlock(rq, p, &flags); 2615 2616 return ns; 2617 } 2618 2619 /* 2620 * This function gets called by the timer code, with HZ frequency. 2621 * We call it with interrupts disabled. 2622 */ 2623 void scheduler_tick(void) 2624 { 2625 int cpu = smp_processor_id(); 2626 struct rq *rq = cpu_rq(cpu); 2627 struct task_struct *curr = rq->curr; 2628 2629 sched_clock_tick(); 2630 2631 raw_spin_lock(&rq->lock); 2632 update_rq_clock(rq); 2633 update_cpu_load_active(rq); 2634 curr->sched_class->task_tick(rq, curr, 0); 2635 raw_spin_unlock(&rq->lock); 2636 2637 perf_event_task_tick(); 2638 2639 #ifdef CONFIG_SMP 2640 rq->idle_balance = idle_cpu(cpu); 2641 trigger_load_balance(rq, cpu); 2642 #endif 2643 } 2644 2645 notrace unsigned long get_parent_ip(unsigned long addr) 2646 { 2647 if (in_lock_functions(addr)) { 2648 addr = CALLER_ADDR2; 2649 if (in_lock_functions(addr)) 2650 addr = CALLER_ADDR3; 2651 } 2652 return addr; 2653 } 2654 2655 #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \ 2656 defined(CONFIG_PREEMPT_TRACER)) 2657 2658 void __kprobes add_preempt_count(int val) 2659 { 2660 #ifdef CONFIG_DEBUG_PREEMPT 2661 /* 2662 * Underflow? 2663 */ 2664 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0))) 2665 return; 2666 #endif 2667 preempt_count() += val; 2668 #ifdef CONFIG_DEBUG_PREEMPT 2669 /* 2670 * Spinlock count overflowing soon? 2671 */ 2672 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >= 2673 PREEMPT_MASK - 10); 2674 #endif 2675 if (preempt_count() == val) 2676 trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1)); 2677 } 2678 EXPORT_SYMBOL(add_preempt_count); 2679 2680 void __kprobes sub_preempt_count(int val) 2681 { 2682 #ifdef CONFIG_DEBUG_PREEMPT 2683 /* 2684 * Underflow? 2685 */ 2686 if (DEBUG_LOCKS_WARN_ON(val > preempt_count())) 2687 return; 2688 /* 2689 * Is the spinlock portion underflowing? 2690 */ 2691 if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) && 2692 !(preempt_count() & PREEMPT_MASK))) 2693 return; 2694 #endif 2695 2696 if (preempt_count() == val) 2697 trace_preempt_on(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1)); 2698 preempt_count() -= val; 2699 } 2700 EXPORT_SYMBOL(sub_preempt_count); 2701 2702 #endif 2703 2704 /* 2705 * Print scheduling while atomic bug: 2706 */ 2707 static noinline void __schedule_bug(struct task_struct *prev) 2708 { 2709 if (oops_in_progress) 2710 return; 2711 2712 printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n", 2713 prev->comm, prev->pid, preempt_count()); 2714 2715 debug_show_held_locks(prev); 2716 print_modules(); 2717 if (irqs_disabled()) 2718 print_irqtrace_events(prev); 2719 dump_stack(); 2720 add_taint(TAINT_WARN); 2721 } 2722 2723 /* 2724 * Various schedule()-time debugging checks and statistics: 2725 */ 2726 static inline void schedule_debug(struct task_struct *prev) 2727 { 2728 /* 2729 * Test if we are atomic. Since do_exit() needs to call into 2730 * schedule() atomically, we ignore that path for now. 2731 * Otherwise, whine if we are scheduling when we should not be. 2732 */ 2733 if (unlikely(in_atomic_preempt_off() && !prev->exit_state)) 2734 __schedule_bug(prev); 2735 rcu_sleep_check(); 2736 2737 profile_hit(SCHED_PROFILING, __builtin_return_address(0)); 2738 2739 schedstat_inc(this_rq(), sched_count); 2740 } 2741 2742 static void put_prev_task(struct rq *rq, struct task_struct *prev) 2743 { 2744 if (prev->on_rq || rq->skip_clock_update < 0) 2745 update_rq_clock(rq); 2746 prev->sched_class->put_prev_task(rq, prev); 2747 } 2748 2749 /* 2750 * Pick up the highest-prio task: 2751 */ 2752 static inline struct task_struct * 2753 pick_next_task(struct rq *rq) 2754 { 2755 const struct sched_class *class; 2756 struct task_struct *p; 2757 2758 /* 2759 * Optimization: we know that if all tasks are in 2760 * the fair class we can call that function directly: 2761 */ 2762 if (likely(rq->nr_running == rq->cfs.h_nr_running)) { 2763 p = fair_sched_class.pick_next_task(rq); 2764 if (likely(p)) 2765 return p; 2766 } 2767 2768 for_each_class(class) { 2769 p = class->pick_next_task(rq); 2770 if (p) 2771 return p; 2772 } 2773 2774 BUG(); /* the idle class will always have a runnable task */ 2775 } 2776 2777 /* 2778 * __schedule() is the main scheduler function. 2779 * 2780 * The main means of driving the scheduler and thus entering this function are: 2781 * 2782 * 1. Explicit blocking: mutex, semaphore, waitqueue, etc. 2783 * 2784 * 2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return 2785 * paths. For example, see arch/x86/entry_64.S. 2786 * 2787 * To drive preemption between tasks, the scheduler sets the flag in timer 2788 * interrupt handler scheduler_tick(). 2789 * 2790 * 3. Wakeups don't really cause entry into schedule(). They add a 2791 * task to the run-queue and that's it. 2792 * 2793 * Now, if the new task added to the run-queue preempts the current 2794 * task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets 2795 * called on the nearest possible occasion: 2796 * 2797 * - If the kernel is preemptible (CONFIG_PREEMPT=y): 2798 * 2799 * - in syscall or exception context, at the next outmost 2800 * preempt_enable(). (this might be as soon as the wake_up()'s 2801 * spin_unlock()!) 2802 * 2803 * - in IRQ context, return from interrupt-handler to 2804 * preemptible context 2805 * 2806 * - If the kernel is not preemptible (CONFIG_PREEMPT is not set) 2807 * then at the next: 2808 * 2809 * - cond_resched() call 2810 * - explicit schedule() call 2811 * - return from syscall or exception to user-space 2812 * - return from interrupt-handler to user-space 2813 */ 2814 static void __sched __schedule(void) 2815 { 2816 struct task_struct *prev, *next; 2817 unsigned long *switch_count; 2818 struct rq *rq; 2819 int cpu; 2820 2821 need_resched: 2822 preempt_disable(); 2823 cpu = smp_processor_id(); 2824 rq = cpu_rq(cpu); 2825 rcu_note_context_switch(cpu); 2826 prev = rq->curr; 2827 2828 schedule_debug(prev); 2829 2830 if (sched_feat(HRTICK)) 2831 hrtick_clear(rq); 2832 2833 raw_spin_lock_irq(&rq->lock); 2834 2835 switch_count = &prev->nivcsw; 2836 if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) { 2837 if (unlikely(signal_pending_state(prev->state, prev))) { 2838 prev->state = TASK_RUNNING; 2839 } else { 2840 deactivate_task(rq, prev, DEQUEUE_SLEEP); 2841 prev->on_rq = 0; 2842 2843 /* 2844 * If a worker went to sleep, notify and ask workqueue 2845 * whether it wants to wake up a task to maintain 2846 * concurrency. 2847 */ 2848 if (prev->flags & PF_WQ_WORKER) { 2849 struct task_struct *to_wakeup; 2850 2851 to_wakeup = wq_worker_sleeping(prev, cpu); 2852 if (to_wakeup) 2853 try_to_wake_up_local(to_wakeup); 2854 } 2855 } 2856 switch_count = &prev->nvcsw; 2857 } 2858 2859 pre_schedule(rq, prev); 2860 2861 if (unlikely(!rq->nr_running)) 2862 idle_balance(cpu, rq); 2863 2864 put_prev_task(rq, prev); 2865 next = pick_next_task(rq); 2866 clear_tsk_need_resched(prev); 2867 rq->skip_clock_update = 0; 2868 2869 if (likely(prev != next)) { 2870 rq->nr_switches++; 2871 rq->curr = next; 2872 ++*switch_count; 2873 2874 context_switch(rq, prev, next); /* unlocks the rq */ 2875 /* 2876 * The context switch have flipped the stack from under us 2877 * and restored the local variables which were saved when 2878 * this task called schedule() in the past. prev == current 2879 * is still correct, but it can be moved to another cpu/rq. 2880 */ 2881 cpu = smp_processor_id(); 2882 rq = cpu_rq(cpu); 2883 } else 2884 raw_spin_unlock_irq(&rq->lock); 2885 2886 post_schedule(rq); 2887 2888 sched_preempt_enable_no_resched(); 2889 if (need_resched()) 2890 goto need_resched; 2891 } 2892 2893 static inline void sched_submit_work(struct task_struct *tsk) 2894 { 2895 if (!tsk->state || tsk_is_pi_blocked(tsk)) 2896 return; 2897 /* 2898 * If we are going to sleep and we have plugged IO queued, 2899 * make sure to submit it to avoid deadlocks. 2900 */ 2901 if (blk_needs_flush_plug(tsk)) 2902 blk_schedule_flush_plug(tsk); 2903 } 2904 2905 asmlinkage void __sched schedule(void) 2906 { 2907 struct task_struct *tsk = current; 2908 2909 sched_submit_work(tsk); 2910 __schedule(); 2911 } 2912 EXPORT_SYMBOL(schedule); 2913 2914 #ifdef CONFIG_RCU_USER_QS 2915 asmlinkage void __sched schedule_user(void) 2916 { 2917 /* 2918 * If we come here after a random call to set_need_resched(), 2919 * or we have been woken up remotely but the IPI has not yet arrived, 2920 * we haven't yet exited the RCU idle mode. Do it here manually until 2921 * we find a better solution. 2922 */ 2923 rcu_user_exit(); 2924 schedule(); 2925 rcu_user_enter(); 2926 } 2927 #endif 2928 2929 /** 2930 * schedule_preempt_disabled - called with preemption disabled 2931 * 2932 * Returns with preemption disabled. Note: preempt_count must be 1 2933 */ 2934 void __sched schedule_preempt_disabled(void) 2935 { 2936 sched_preempt_enable_no_resched(); 2937 schedule(); 2938 preempt_disable(); 2939 } 2940 2941 #ifdef CONFIG_MUTEX_SPIN_ON_OWNER 2942 2943 static inline bool owner_running(struct mutex *lock, struct task_struct *owner) 2944 { 2945 if (lock->owner != owner) 2946 return false; 2947 2948 /* 2949 * Ensure we emit the owner->on_cpu, dereference _after_ checking 2950 * lock->owner still matches owner, if that fails, owner might 2951 * point to free()d memory, if it still matches, the rcu_read_lock() 2952 * ensures the memory stays valid. 2953 */ 2954 barrier(); 2955 2956 return owner->on_cpu; 2957 } 2958 2959 /* 2960 * Look out! "owner" is an entirely speculative pointer 2961 * access and not reliable. 2962 */ 2963 int mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner) 2964 { 2965 if (!sched_feat(OWNER_SPIN)) 2966 return 0; 2967 2968 rcu_read_lock(); 2969 while (owner_running(lock, owner)) { 2970 if (need_resched()) 2971 break; 2972 2973 arch_mutex_cpu_relax(); 2974 } 2975 rcu_read_unlock(); 2976 2977 /* 2978 * We break out the loop above on need_resched() and when the 2979 * owner changed, which is a sign for heavy contention. Return 2980 * success only when lock->owner is NULL. 2981 */ 2982 return lock->owner == NULL; 2983 } 2984 #endif 2985 2986 #ifdef CONFIG_PREEMPT 2987 /* 2988 * this is the entry point to schedule() from in-kernel preemption 2989 * off of preempt_enable. Kernel preemptions off return from interrupt 2990 * occur there and call schedule directly. 2991 */ 2992 asmlinkage void __sched notrace preempt_schedule(void) 2993 { 2994 struct thread_info *ti = current_thread_info(); 2995 2996 /* 2997 * If there is a non-zero preempt_count or interrupts are disabled, 2998 * we do not want to preempt the current task. Just return.. 2999 */ 3000 if (likely(ti->preempt_count || irqs_disabled())) 3001 return; 3002 3003 do { 3004 add_preempt_count_notrace(PREEMPT_ACTIVE); 3005 __schedule(); 3006 sub_preempt_count_notrace(PREEMPT_ACTIVE); 3007 3008 /* 3009 * Check again in case we missed a preemption opportunity 3010 * between schedule and now. 3011 */ 3012 barrier(); 3013 } while (need_resched()); 3014 } 3015 EXPORT_SYMBOL(preempt_schedule); 3016 3017 /* 3018 * this is the entry point to schedule() from kernel preemption 3019 * off of irq context. 3020 * Note, that this is called and return with irqs disabled. This will 3021 * protect us against recursive calling from irq. 3022 */ 3023 asmlinkage void __sched preempt_schedule_irq(void) 3024 { 3025 struct thread_info *ti = current_thread_info(); 3026 3027 /* Catch callers which need to be fixed */ 3028 BUG_ON(ti->preempt_count || !irqs_disabled()); 3029 3030 rcu_user_exit(); 3031 do { 3032 add_preempt_count(PREEMPT_ACTIVE); 3033 local_irq_enable(); 3034 __schedule(); 3035 local_irq_disable(); 3036 sub_preempt_count(PREEMPT_ACTIVE); 3037 3038 /* 3039 * Check again in case we missed a preemption opportunity 3040 * between schedule and now. 3041 */ 3042 barrier(); 3043 } while (need_resched()); 3044 } 3045 3046 #endif /* CONFIG_PREEMPT */ 3047 3048 int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags, 3049 void *key) 3050 { 3051 return try_to_wake_up(curr->private, mode, wake_flags); 3052 } 3053 EXPORT_SYMBOL(default_wake_function); 3054 3055 /* 3056 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just 3057 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve 3058 * number) then we wake all the non-exclusive tasks and one exclusive task. 3059 * 3060 * There are circumstances in which we can try to wake a task which has already 3061 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns 3062 * zero in this (rare) case, and we handle it by continuing to scan the queue. 3063 */ 3064 static void __wake_up_common(wait_queue_head_t *q, unsigned int mode, 3065 int nr_exclusive, int wake_flags, void *key) 3066 { 3067 wait_queue_t *curr, *next; 3068 3069 list_for_each_entry_safe(curr, next, &q->task_list, task_list) { 3070 unsigned flags = curr->flags; 3071 3072 if (curr->func(curr, mode, wake_flags, key) && 3073 (flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive) 3074 break; 3075 } 3076 } 3077 3078 /** 3079 * __wake_up - wake up threads blocked on a waitqueue. 3080 * @q: the waitqueue 3081 * @mode: which threads 3082 * @nr_exclusive: how many wake-one or wake-many threads to wake up 3083 * @key: is directly passed to the wakeup function 3084 * 3085 * It may be assumed that this function implies a write memory barrier before 3086 * changing the task state if and only if any tasks are woken up. 3087 */ 3088 void __wake_up(wait_queue_head_t *q, unsigned int mode, 3089 int nr_exclusive, void *key) 3090 { 3091 unsigned long flags; 3092 3093 spin_lock_irqsave(&q->lock, flags); 3094 __wake_up_common(q, mode, nr_exclusive, 0, key); 3095 spin_unlock_irqrestore(&q->lock, flags); 3096 } 3097 EXPORT_SYMBOL(__wake_up); 3098 3099 /* 3100 * Same as __wake_up but called with the spinlock in wait_queue_head_t held. 3101 */ 3102 void __wake_up_locked(wait_queue_head_t *q, unsigned int mode, int nr) 3103 { 3104 __wake_up_common(q, mode, nr, 0, NULL); 3105 } 3106 EXPORT_SYMBOL_GPL(__wake_up_locked); 3107 3108 void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key) 3109 { 3110 __wake_up_common(q, mode, 1, 0, key); 3111 } 3112 EXPORT_SYMBOL_GPL(__wake_up_locked_key); 3113 3114 /** 3115 * __wake_up_sync_key - wake up threads blocked on a waitqueue. 3116 * @q: the waitqueue 3117 * @mode: which threads 3118 * @nr_exclusive: how many wake-one or wake-many threads to wake up 3119 * @key: opaque value to be passed to wakeup targets 3120 * 3121 * The sync wakeup differs that the waker knows that it will schedule 3122 * away soon, so while the target thread will be woken up, it will not 3123 * be migrated to another CPU - ie. the two threads are 'synchronized' 3124 * with each other. This can prevent needless bouncing between CPUs. 3125 * 3126 * On UP it can prevent extra preemption. 3127 * 3128 * It may be assumed that this function implies a write memory barrier before 3129 * changing the task state if and only if any tasks are woken up. 3130 */ 3131 void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode, 3132 int nr_exclusive, void *key) 3133 { 3134 unsigned long flags; 3135 int wake_flags = WF_SYNC; 3136 3137 if (unlikely(!q)) 3138 return; 3139 3140 if (unlikely(!nr_exclusive)) 3141 wake_flags = 0; 3142 3143 spin_lock_irqsave(&q->lock, flags); 3144 __wake_up_common(q, mode, nr_exclusive, wake_flags, key); 3145 spin_unlock_irqrestore(&q->lock, flags); 3146 } 3147 EXPORT_SYMBOL_GPL(__wake_up_sync_key); 3148 3149 /* 3150 * __wake_up_sync - see __wake_up_sync_key() 3151 */ 3152 void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive) 3153 { 3154 __wake_up_sync_key(q, mode, nr_exclusive, NULL); 3155 } 3156 EXPORT_SYMBOL_GPL(__wake_up_sync); /* For internal use only */ 3157 3158 /** 3159 * complete: - signals a single thread waiting on this completion 3160 * @x: holds the state of this particular completion 3161 * 3162 * This will wake up a single thread waiting on this completion. Threads will be 3163 * awakened in the same order in which they were queued. 3164 * 3165 * See also complete_all(), wait_for_completion() and related routines. 3166 * 3167 * It may be assumed that this function implies a write memory barrier before 3168 * changing the task state if and only if any tasks are woken up. 3169 */ 3170 void complete(struct completion *x) 3171 { 3172 unsigned long flags; 3173 3174 spin_lock_irqsave(&x->wait.lock, flags); 3175 x->done++; 3176 __wake_up_common(&x->wait, TASK_NORMAL, 1, 0, NULL); 3177 spin_unlock_irqrestore(&x->wait.lock, flags); 3178 } 3179 EXPORT_SYMBOL(complete); 3180 3181 /** 3182 * complete_all: - signals all threads waiting on this completion 3183 * @x: holds the state of this particular completion 3184 * 3185 * This will wake up all threads waiting on this particular completion event. 3186 * 3187 * It may be assumed that this function implies a write memory barrier before 3188 * changing the task state if and only if any tasks are woken up. 3189 */ 3190 void complete_all(struct completion *x) 3191 { 3192 unsigned long flags; 3193 3194 spin_lock_irqsave(&x->wait.lock, flags); 3195 x->done += UINT_MAX/2; 3196 __wake_up_common(&x->wait, TASK_NORMAL, 0, 0, NULL); 3197 spin_unlock_irqrestore(&x->wait.lock, flags); 3198 } 3199 EXPORT_SYMBOL(complete_all); 3200 3201 static inline long __sched 3202 do_wait_for_common(struct completion *x, long timeout, int state) 3203 { 3204 if (!x->done) { 3205 DECLARE_WAITQUEUE(wait, current); 3206 3207 __add_wait_queue_tail_exclusive(&x->wait, &wait); 3208 do { 3209 if (signal_pending_state(state, current)) { 3210 timeout = -ERESTARTSYS; 3211 break; 3212 } 3213 __set_current_state(state); 3214 spin_unlock_irq(&x->wait.lock); 3215 timeout = schedule_timeout(timeout); 3216 spin_lock_irq(&x->wait.lock); 3217 } while (!x->done && timeout); 3218 __remove_wait_queue(&x->wait, &wait); 3219 if (!x->done) 3220 return timeout; 3221 } 3222 x->done--; 3223 return timeout ?: 1; 3224 } 3225 3226 static long __sched 3227 wait_for_common(struct completion *x, long timeout, int state) 3228 { 3229 might_sleep(); 3230 3231 spin_lock_irq(&x->wait.lock); 3232 timeout = do_wait_for_common(x, timeout, state); 3233 spin_unlock_irq(&x->wait.lock); 3234 return timeout; 3235 } 3236 3237 /** 3238 * wait_for_completion: - waits for completion of a task 3239 * @x: holds the state of this particular completion 3240 * 3241 * This waits to be signaled for completion of a specific task. It is NOT 3242 * interruptible and there is no timeout. 3243 * 3244 * See also similar routines (i.e. wait_for_completion_timeout()) with timeout 3245 * and interrupt capability. Also see complete(). 3246 */ 3247 void __sched wait_for_completion(struct completion *x) 3248 { 3249 wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_UNINTERRUPTIBLE); 3250 } 3251 EXPORT_SYMBOL(wait_for_completion); 3252 3253 /** 3254 * wait_for_completion_timeout: - waits for completion of a task (w/timeout) 3255 * @x: holds the state of this particular completion 3256 * @timeout: timeout value in jiffies 3257 * 3258 * This waits for either a completion of a specific task to be signaled or for a 3259 * specified timeout to expire. The timeout is in jiffies. It is not 3260 * interruptible. 3261 * 3262 * The return value is 0 if timed out, and positive (at least 1, or number of 3263 * jiffies left till timeout) if completed. 3264 */ 3265 unsigned long __sched 3266 wait_for_completion_timeout(struct completion *x, unsigned long timeout) 3267 { 3268 return wait_for_common(x, timeout, TASK_UNINTERRUPTIBLE); 3269 } 3270 EXPORT_SYMBOL(wait_for_completion_timeout); 3271 3272 /** 3273 * wait_for_completion_interruptible: - waits for completion of a task (w/intr) 3274 * @x: holds the state of this particular completion 3275 * 3276 * This waits for completion of a specific task to be signaled. It is 3277 * interruptible. 3278 * 3279 * The return value is -ERESTARTSYS if interrupted, 0 if completed. 3280 */ 3281 int __sched wait_for_completion_interruptible(struct completion *x) 3282 { 3283 long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_INTERRUPTIBLE); 3284 if (t == -ERESTARTSYS) 3285 return t; 3286 return 0; 3287 } 3288 EXPORT_SYMBOL(wait_for_completion_interruptible); 3289 3290 /** 3291 * wait_for_completion_interruptible_timeout: - waits for completion (w/(to,intr)) 3292 * @x: holds the state of this particular completion 3293 * @timeout: timeout value in jiffies 3294 * 3295 * This waits for either a completion of a specific task to be signaled or for a 3296 * specified timeout to expire. It is interruptible. The timeout is in jiffies. 3297 * 3298 * The return value is -ERESTARTSYS if interrupted, 0 if timed out, 3299 * positive (at least 1, or number of jiffies left till timeout) if completed. 3300 */ 3301 long __sched 3302 wait_for_completion_interruptible_timeout(struct completion *x, 3303 unsigned long timeout) 3304 { 3305 return wait_for_common(x, timeout, TASK_INTERRUPTIBLE); 3306 } 3307 EXPORT_SYMBOL(wait_for_completion_interruptible_timeout); 3308 3309 /** 3310 * wait_for_completion_killable: - waits for completion of a task (killable) 3311 * @x: holds the state of this particular completion 3312 * 3313 * This waits to be signaled for completion of a specific task. It can be 3314 * interrupted by a kill signal. 3315 * 3316 * The return value is -ERESTARTSYS if interrupted, 0 if completed. 3317 */ 3318 int __sched wait_for_completion_killable(struct completion *x) 3319 { 3320 long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_KILLABLE); 3321 if (t == -ERESTARTSYS) 3322 return t; 3323 return 0; 3324 } 3325 EXPORT_SYMBOL(wait_for_completion_killable); 3326 3327 /** 3328 * wait_for_completion_killable_timeout: - waits for completion of a task (w/(to,killable)) 3329 * @x: holds the state of this particular completion 3330 * @timeout: timeout value in jiffies 3331 * 3332 * This waits for either a completion of a specific task to be 3333 * signaled or for a specified timeout to expire. It can be 3334 * interrupted by a kill signal. The timeout is in jiffies. 3335 * 3336 * The return value is -ERESTARTSYS if interrupted, 0 if timed out, 3337 * positive (at least 1, or number of jiffies left till timeout) if completed. 3338 */ 3339 long __sched 3340 wait_for_completion_killable_timeout(struct completion *x, 3341 unsigned long timeout) 3342 { 3343 return wait_for_common(x, timeout, TASK_KILLABLE); 3344 } 3345 EXPORT_SYMBOL(wait_for_completion_killable_timeout); 3346 3347 /** 3348 * try_wait_for_completion - try to decrement a completion without blocking 3349 * @x: completion structure 3350 * 3351 * Returns: 0 if a decrement cannot be done without blocking 3352 * 1 if a decrement succeeded. 3353 * 3354 * If a completion is being used as a counting completion, 3355 * attempt to decrement the counter without blocking. This 3356 * enables us to avoid waiting if the resource the completion 3357 * is protecting is not available. 3358 */ 3359 bool try_wait_for_completion(struct completion *x) 3360 { 3361 unsigned long flags; 3362 int ret = 1; 3363 3364 spin_lock_irqsave(&x->wait.lock, flags); 3365 if (!x->done) 3366 ret = 0; 3367 else 3368 x->done--; 3369 spin_unlock_irqrestore(&x->wait.lock, flags); 3370 return ret; 3371 } 3372 EXPORT_SYMBOL(try_wait_for_completion); 3373 3374 /** 3375 * completion_done - Test to see if a completion has any waiters 3376 * @x: completion structure 3377 * 3378 * Returns: 0 if there are waiters (wait_for_completion() in progress) 3379 * 1 if there are no waiters. 3380 * 3381 */ 3382 bool completion_done(struct completion *x) 3383 { 3384 unsigned long flags; 3385 int ret = 1; 3386 3387 spin_lock_irqsave(&x->wait.lock, flags); 3388 if (!x->done) 3389 ret = 0; 3390 spin_unlock_irqrestore(&x->wait.lock, flags); 3391 return ret; 3392 } 3393 EXPORT_SYMBOL(completion_done); 3394 3395 static long __sched 3396 sleep_on_common(wait_queue_head_t *q, int state, long timeout) 3397 { 3398 unsigned long flags; 3399 wait_queue_t wait; 3400 3401 init_waitqueue_entry(&wait, current); 3402 3403 __set_current_state(state); 3404 3405 spin_lock_irqsave(&q->lock, flags); 3406 __add_wait_queue(q, &wait); 3407 spin_unlock(&q->lock); 3408 timeout = schedule_timeout(timeout); 3409 spin_lock_irq(&q->lock); 3410 __remove_wait_queue(q, &wait); 3411 spin_unlock_irqrestore(&q->lock, flags); 3412 3413 return timeout; 3414 } 3415 3416 void __sched interruptible_sleep_on(wait_queue_head_t *q) 3417 { 3418 sleep_on_common(q, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); 3419 } 3420 EXPORT_SYMBOL(interruptible_sleep_on); 3421 3422 long __sched 3423 interruptible_sleep_on_timeout(wait_queue_head_t *q, long timeout) 3424 { 3425 return sleep_on_common(q, TASK_INTERRUPTIBLE, timeout); 3426 } 3427 EXPORT_SYMBOL(interruptible_sleep_on_timeout); 3428 3429 void __sched sleep_on(wait_queue_head_t *q) 3430 { 3431 sleep_on_common(q, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); 3432 } 3433 EXPORT_SYMBOL(sleep_on); 3434 3435 long __sched sleep_on_timeout(wait_queue_head_t *q, long timeout) 3436 { 3437 return sleep_on_common(q, TASK_UNINTERRUPTIBLE, timeout); 3438 } 3439 EXPORT_SYMBOL(sleep_on_timeout); 3440 3441 #ifdef CONFIG_RT_MUTEXES 3442 3443 /* 3444 * rt_mutex_setprio - set the current priority of a task 3445 * @p: task 3446 * @prio: prio value (kernel-internal form) 3447 * 3448 * This function changes the 'effective' priority of a task. It does 3449 * not touch ->normal_prio like __setscheduler(). 3450 * 3451 * Used by the rt_mutex code to implement priority inheritance logic. 3452 */ 3453 void rt_mutex_setprio(struct task_struct *p, int prio) 3454 { 3455 int oldprio, on_rq, running; 3456 struct rq *rq; 3457 const struct sched_class *prev_class; 3458 3459 BUG_ON(prio < 0 || prio > MAX_PRIO); 3460 3461 rq = __task_rq_lock(p); 3462 3463 /* 3464 * Idle task boosting is a nono in general. There is one 3465 * exception, when PREEMPT_RT and NOHZ is active: 3466 * 3467 * The idle task calls get_next_timer_interrupt() and holds 3468 * the timer wheel base->lock on the CPU and another CPU wants 3469 * to access the timer (probably to cancel it). We can safely 3470 * ignore the boosting request, as the idle CPU runs this code 3471 * with interrupts disabled and will complete the lock 3472 * protected section without being interrupted. So there is no 3473 * real need to boost. 3474 */ 3475 if (unlikely(p == rq->idle)) { 3476 WARN_ON(p != rq->curr); 3477 WARN_ON(p->pi_blocked_on); 3478 goto out_unlock; 3479 } 3480 3481 trace_sched_pi_setprio(p, prio); 3482 oldprio = p->prio; 3483 prev_class = p->sched_class; 3484 on_rq = p->on_rq; 3485 running = task_current(rq, p); 3486 if (on_rq) 3487 dequeue_task(rq, p, 0); 3488 if (running) 3489 p->sched_class->put_prev_task(rq, p); 3490 3491 if (rt_prio(prio)) 3492 p->sched_class = &rt_sched_class; 3493 else 3494 p->sched_class = &fair_sched_class; 3495 3496 p->prio = prio; 3497 3498 if (running) 3499 p->sched_class->set_curr_task(rq); 3500 if (on_rq) 3501 enqueue_task(rq, p, oldprio < prio ? ENQUEUE_HEAD : 0); 3502 3503 check_class_changed(rq, p, prev_class, oldprio); 3504 out_unlock: 3505 __task_rq_unlock(rq); 3506 } 3507 #endif 3508 void set_user_nice(struct task_struct *p, long nice) 3509 { 3510 int old_prio, delta, on_rq; 3511 unsigned long flags; 3512 struct rq *rq; 3513 3514 if (TASK_NICE(p) == nice || nice < -20 || nice > 19) 3515 return; 3516 /* 3517 * We have to be careful, if called from sys_setpriority(), 3518 * the task might be in the middle of scheduling on another CPU. 3519 */ 3520 rq = task_rq_lock(p, &flags); 3521 /* 3522 * The RT priorities are set via sched_setscheduler(), but we still 3523 * allow the 'normal' nice value to be set - but as expected 3524 * it wont have any effect on scheduling until the task is 3525 * SCHED_FIFO/SCHED_RR: 3526 */ 3527 if (task_has_rt_policy(p)) { 3528 p->static_prio = NICE_TO_PRIO(nice); 3529 goto out_unlock; 3530 } 3531 on_rq = p->on_rq; 3532 if (on_rq) 3533 dequeue_task(rq, p, 0); 3534 3535 p->static_prio = NICE_TO_PRIO(nice); 3536 set_load_weight(p); 3537 old_prio = p->prio; 3538 p->prio = effective_prio(p); 3539 delta = p->prio - old_prio; 3540 3541 if (on_rq) { 3542 enqueue_task(rq, p, 0); 3543 /* 3544 * If the task increased its priority or is running and 3545 * lowered its priority, then reschedule its CPU: 3546 */ 3547 if (delta < 0 || (delta > 0 && task_running(rq, p))) 3548 resched_task(rq->curr); 3549 } 3550 out_unlock: 3551 task_rq_unlock(rq, p, &flags); 3552 } 3553 EXPORT_SYMBOL(set_user_nice); 3554 3555 /* 3556 * can_nice - check if a task can reduce its nice value 3557 * @p: task 3558 * @nice: nice value 3559 */ 3560 int can_nice(const struct task_struct *p, const int nice) 3561 { 3562 /* convert nice value [19,-20] to rlimit style value [1,40] */ 3563 int nice_rlim = 20 - nice; 3564 3565 return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) || 3566 capable(CAP_SYS_NICE)); 3567 } 3568 3569 #ifdef __ARCH_WANT_SYS_NICE 3570 3571 /* 3572 * sys_nice - change the priority of the current process. 3573 * @increment: priority increment 3574 * 3575 * sys_setpriority is a more generic, but much slower function that 3576 * does similar things. 3577 */ 3578 SYSCALL_DEFINE1(nice, int, increment) 3579 { 3580 long nice, retval; 3581 3582 /* 3583 * Setpriority might change our priority at the same moment. 3584 * We don't have to worry. Conceptually one call occurs first 3585 * and we have a single winner. 3586 */ 3587 if (increment < -40) 3588 increment = -40; 3589 if (increment > 40) 3590 increment = 40; 3591 3592 nice = TASK_NICE(current) + increment; 3593 if (nice < -20) 3594 nice = -20; 3595 if (nice > 19) 3596 nice = 19; 3597 3598 if (increment < 0 && !can_nice(current, nice)) 3599 return -EPERM; 3600 3601 retval = security_task_setnice(current, nice); 3602 if (retval) 3603 return retval; 3604 3605 set_user_nice(current, nice); 3606 return 0; 3607 } 3608 3609 #endif 3610 3611 /** 3612 * task_prio - return the priority value of a given task. 3613 * @p: the task in question. 3614 * 3615 * This is the priority value as seen by users in /proc. 3616 * RT tasks are offset by -200. Normal tasks are centered 3617 * around 0, value goes from -16 to +15. 3618 */ 3619 int task_prio(const struct task_struct *p) 3620 { 3621 return p->prio - MAX_RT_PRIO; 3622 } 3623 3624 /** 3625 * task_nice - return the nice value of a given task. 3626 * @p: the task in question. 3627 */ 3628 int task_nice(const struct task_struct *p) 3629 { 3630 return TASK_NICE(p); 3631 } 3632 EXPORT_SYMBOL(task_nice); 3633 3634 /** 3635 * idle_cpu - is a given cpu idle currently? 3636 * @cpu: the processor in question. 3637 */ 3638 int idle_cpu(int cpu) 3639 { 3640 struct rq *rq = cpu_rq(cpu); 3641 3642 if (rq->curr != rq->idle) 3643 return 0; 3644 3645 if (rq->nr_running) 3646 return 0; 3647 3648 #ifdef CONFIG_SMP 3649 if (!llist_empty(&rq->wake_list)) 3650 return 0; 3651 #endif 3652 3653 return 1; 3654 } 3655 3656 /** 3657 * idle_task - return the idle task for a given cpu. 3658 * @cpu: the processor in question. 3659 */ 3660 struct task_struct *idle_task(int cpu) 3661 { 3662 return cpu_rq(cpu)->idle; 3663 } 3664 3665 /** 3666 * find_process_by_pid - find a process with a matching PID value. 3667 * @pid: the pid in question. 3668 */ 3669 static struct task_struct *find_process_by_pid(pid_t pid) 3670 { 3671 return pid ? find_task_by_vpid(pid) : current; 3672 } 3673 3674 /* Actually do priority change: must hold rq lock. */ 3675 static void 3676 __setscheduler(struct rq *rq, struct task_struct *p, int policy, int prio) 3677 { 3678 p->policy = policy; 3679 p->rt_priority = prio; 3680 p->normal_prio = normal_prio(p); 3681 /* we are holding p->pi_lock already */ 3682 p->prio = rt_mutex_getprio(p); 3683 if (rt_prio(p->prio)) 3684 p->sched_class = &rt_sched_class; 3685 else 3686 p->sched_class = &fair_sched_class; 3687 set_load_weight(p); 3688 } 3689 3690 /* 3691 * check the target process has a UID that matches the current process's 3692 */ 3693 static bool check_same_owner(struct task_struct *p) 3694 { 3695 const struct cred *cred = current_cred(), *pcred; 3696 bool match; 3697 3698 rcu_read_lock(); 3699 pcred = __task_cred(p); 3700 match = (uid_eq(cred->euid, pcred->euid) || 3701 uid_eq(cred->euid, pcred->uid)); 3702 rcu_read_unlock(); 3703 return match; 3704 } 3705 3706 static int __sched_setscheduler(struct task_struct *p, int policy, 3707 const struct sched_param *param, bool user) 3708 { 3709 int retval, oldprio, oldpolicy = -1, on_rq, running; 3710 unsigned long flags; 3711 const struct sched_class *prev_class; 3712 struct rq *rq; 3713 int reset_on_fork; 3714 3715 /* may grab non-irq protected spin_locks */ 3716 BUG_ON(in_interrupt()); 3717 recheck: 3718 /* double check policy once rq lock held */ 3719 if (policy < 0) { 3720 reset_on_fork = p->sched_reset_on_fork; 3721 policy = oldpolicy = p->policy; 3722 } else { 3723 reset_on_fork = !!(policy & SCHED_RESET_ON_FORK); 3724 policy &= ~SCHED_RESET_ON_FORK; 3725 3726 if (policy != SCHED_FIFO && policy != SCHED_RR && 3727 policy != SCHED_NORMAL && policy != SCHED_BATCH && 3728 policy != SCHED_IDLE) 3729 return -EINVAL; 3730 } 3731 3732 /* 3733 * Valid priorities for SCHED_FIFO and SCHED_RR are 3734 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL, 3735 * SCHED_BATCH and SCHED_IDLE is 0. 3736 */ 3737 if (param->sched_priority < 0 || 3738 (p->mm && param->sched_priority > MAX_USER_RT_PRIO-1) || 3739 (!p->mm && param->sched_priority > MAX_RT_PRIO-1)) 3740 return -EINVAL; 3741 if (rt_policy(policy) != (param->sched_priority != 0)) 3742 return -EINVAL; 3743 3744 /* 3745 * Allow unprivileged RT tasks to decrease priority: 3746 */ 3747 if (user && !capable(CAP_SYS_NICE)) { 3748 if (rt_policy(policy)) { 3749 unsigned long rlim_rtprio = 3750 task_rlimit(p, RLIMIT_RTPRIO); 3751 3752 /* can't set/change the rt policy */ 3753 if (policy != p->policy && !rlim_rtprio) 3754 return -EPERM; 3755 3756 /* can't increase priority */ 3757 if (param->sched_priority > p->rt_priority && 3758 param->sched_priority > rlim_rtprio) 3759 return -EPERM; 3760 } 3761 3762 /* 3763 * Treat SCHED_IDLE as nice 20. Only allow a switch to 3764 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it. 3765 */ 3766 if (p->policy == SCHED_IDLE && policy != SCHED_IDLE) { 3767 if (!can_nice(p, TASK_NICE(p))) 3768 return -EPERM; 3769 } 3770 3771 /* can't change other user's priorities */ 3772 if (!check_same_owner(p)) 3773 return -EPERM; 3774 3775 /* Normal users shall not reset the sched_reset_on_fork flag */ 3776 if (p->sched_reset_on_fork && !reset_on_fork) 3777 return -EPERM; 3778 } 3779 3780 if (user) { 3781 retval = security_task_setscheduler(p); 3782 if (retval) 3783 return retval; 3784 } 3785 3786 /* 3787 * make sure no PI-waiters arrive (or leave) while we are 3788 * changing the priority of the task: 3789 * 3790 * To be able to change p->policy safely, the appropriate 3791 * runqueue lock must be held. 3792 */ 3793 rq = task_rq_lock(p, &flags); 3794 3795 /* 3796 * Changing the policy of the stop threads its a very bad idea 3797 */ 3798 if (p == rq->stop) { 3799 task_rq_unlock(rq, p, &flags); 3800 return -EINVAL; 3801 } 3802 3803 /* 3804 * If not changing anything there's no need to proceed further: 3805 */ 3806 if (unlikely(policy == p->policy && (!rt_policy(policy) || 3807 param->sched_priority == p->rt_priority))) { 3808 task_rq_unlock(rq, p, &flags); 3809 return 0; 3810 } 3811 3812 #ifdef CONFIG_RT_GROUP_SCHED 3813 if (user) { 3814 /* 3815 * Do not allow realtime tasks into groups that have no runtime 3816 * assigned. 3817 */ 3818 if (rt_bandwidth_enabled() && rt_policy(policy) && 3819 task_group(p)->rt_bandwidth.rt_runtime == 0 && 3820 !task_group_is_autogroup(task_group(p))) { 3821 task_rq_unlock(rq, p, &flags); 3822 return -EPERM; 3823 } 3824 } 3825 #endif 3826 3827 /* recheck policy now with rq lock held */ 3828 if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) { 3829 policy = oldpolicy = -1; 3830 task_rq_unlock(rq, p, &flags); 3831 goto recheck; 3832 } 3833 on_rq = p->on_rq; 3834 running = task_current(rq, p); 3835 if (on_rq) 3836 dequeue_task(rq, p, 0); 3837 if (running) 3838 p->sched_class->put_prev_task(rq, p); 3839 3840 p->sched_reset_on_fork = reset_on_fork; 3841 3842 oldprio = p->prio; 3843 prev_class = p->sched_class; 3844 __setscheduler(rq, p, policy, param->sched_priority); 3845 3846 if (running) 3847 p->sched_class->set_curr_task(rq); 3848 if (on_rq) 3849 enqueue_task(rq, p, 0); 3850 3851 check_class_changed(rq, p, prev_class, oldprio); 3852 task_rq_unlock(rq, p, &flags); 3853 3854 rt_mutex_adjust_pi(p); 3855 3856 return 0; 3857 } 3858 3859 /** 3860 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread. 3861 * @p: the task in question. 3862 * @policy: new policy. 3863 * @param: structure containing the new RT priority. 3864 * 3865 * NOTE that the task may be already dead. 3866 */ 3867 int sched_setscheduler(struct task_struct *p, int policy, 3868 const struct sched_param *param) 3869 { 3870 return __sched_setscheduler(p, policy, param, true); 3871 } 3872 EXPORT_SYMBOL_GPL(sched_setscheduler); 3873 3874 /** 3875 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace. 3876 * @p: the task in question. 3877 * @policy: new policy. 3878 * @param: structure containing the new RT priority. 3879 * 3880 * Just like sched_setscheduler, only don't bother checking if the 3881 * current context has permission. For example, this is needed in 3882 * stop_machine(): we create temporary high priority worker threads, 3883 * but our caller might not have that capability. 3884 */ 3885 int sched_setscheduler_nocheck(struct task_struct *p, int policy, 3886 const struct sched_param *param) 3887 { 3888 return __sched_setscheduler(p, policy, param, false); 3889 } 3890 3891 static int 3892 do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param) 3893 { 3894 struct sched_param lparam; 3895 struct task_struct *p; 3896 int retval; 3897 3898 if (!param || pid < 0) 3899 return -EINVAL; 3900 if (copy_from_user(&lparam, param, sizeof(struct sched_param))) 3901 return -EFAULT; 3902 3903 rcu_read_lock(); 3904 retval = -ESRCH; 3905 p = find_process_by_pid(pid); 3906 if (p != NULL) 3907 retval = sched_setscheduler(p, policy, &lparam); 3908 rcu_read_unlock(); 3909 3910 return retval; 3911 } 3912 3913 /** 3914 * sys_sched_setscheduler - set/change the scheduler policy and RT priority 3915 * @pid: the pid in question. 3916 * @policy: new policy. 3917 * @param: structure containing the new RT priority. 3918 */ 3919 SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy, 3920 struct sched_param __user *, param) 3921 { 3922 /* negative values for policy are not valid */ 3923 if (policy < 0) 3924 return -EINVAL; 3925 3926 return do_sched_setscheduler(pid, policy, param); 3927 } 3928 3929 /** 3930 * sys_sched_setparam - set/change the RT priority of a thread 3931 * @pid: the pid in question. 3932 * @param: structure containing the new RT priority. 3933 */ 3934 SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param) 3935 { 3936 return do_sched_setscheduler(pid, -1, param); 3937 } 3938 3939 /** 3940 * sys_sched_getscheduler - get the policy (scheduling class) of a thread 3941 * @pid: the pid in question. 3942 */ 3943 SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid) 3944 { 3945 struct task_struct *p; 3946 int retval; 3947 3948 if (pid < 0) 3949 return -EINVAL; 3950 3951 retval = -ESRCH; 3952 rcu_read_lock(); 3953 p = find_process_by_pid(pid); 3954 if (p) { 3955 retval = security_task_getscheduler(p); 3956 if (!retval) 3957 retval = p->policy 3958 | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0); 3959 } 3960 rcu_read_unlock(); 3961 return retval; 3962 } 3963 3964 /** 3965 * sys_sched_getparam - get the RT priority of a thread 3966 * @pid: the pid in question. 3967 * @param: structure containing the RT priority. 3968 */ 3969 SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param) 3970 { 3971 struct sched_param lp; 3972 struct task_struct *p; 3973 int retval; 3974 3975 if (!param || pid < 0) 3976 return -EINVAL; 3977 3978 rcu_read_lock(); 3979 p = find_process_by_pid(pid); 3980 retval = -ESRCH; 3981 if (!p) 3982 goto out_unlock; 3983 3984 retval = security_task_getscheduler(p); 3985 if (retval) 3986 goto out_unlock; 3987 3988 lp.sched_priority = p->rt_priority; 3989 rcu_read_unlock(); 3990 3991 /* 3992 * This one might sleep, we cannot do it with a spinlock held ... 3993 */ 3994 retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0; 3995 3996 return retval; 3997 3998 out_unlock: 3999 rcu_read_unlock(); 4000 return retval; 4001 } 4002 4003 long sched_setaffinity(pid_t pid, const struct cpumask *in_mask) 4004 { 4005 cpumask_var_t cpus_allowed, new_mask; 4006 struct task_struct *p; 4007 int retval; 4008 4009 get_online_cpus(); 4010 rcu_read_lock(); 4011 4012 p = find_process_by_pid(pid); 4013 if (!p) { 4014 rcu_read_unlock(); 4015 put_online_cpus(); 4016 return -ESRCH; 4017 } 4018 4019 /* Prevent p going away */ 4020 get_task_struct(p); 4021 rcu_read_unlock(); 4022 4023 if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) { 4024 retval = -ENOMEM; 4025 goto out_put_task; 4026 } 4027 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) { 4028 retval = -ENOMEM; 4029 goto out_free_cpus_allowed; 4030 } 4031 retval = -EPERM; 4032 if (!check_same_owner(p) && !ns_capable(task_user_ns(p), CAP_SYS_NICE)) 4033 goto out_unlock; 4034 4035 retval = security_task_setscheduler(p); 4036 if (retval) 4037 goto out_unlock; 4038 4039 cpuset_cpus_allowed(p, cpus_allowed); 4040 cpumask_and(new_mask, in_mask, cpus_allowed); 4041 again: 4042 retval = set_cpus_allowed_ptr(p, new_mask); 4043 4044 if (!retval) { 4045 cpuset_cpus_allowed(p, cpus_allowed); 4046 if (!cpumask_subset(new_mask, cpus_allowed)) { 4047 /* 4048 * We must have raced with a concurrent cpuset 4049 * update. Just reset the cpus_allowed to the 4050 * cpuset's cpus_allowed 4051 */ 4052 cpumask_copy(new_mask, cpus_allowed); 4053 goto again; 4054 } 4055 } 4056 out_unlock: 4057 free_cpumask_var(new_mask); 4058 out_free_cpus_allowed: 4059 free_cpumask_var(cpus_allowed); 4060 out_put_task: 4061 put_task_struct(p); 4062 put_online_cpus(); 4063 return retval; 4064 } 4065 4066 static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len, 4067 struct cpumask *new_mask) 4068 { 4069 if (len < cpumask_size()) 4070 cpumask_clear(new_mask); 4071 else if (len > cpumask_size()) 4072 len = cpumask_size(); 4073 4074 return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0; 4075 } 4076 4077 /** 4078 * sys_sched_setaffinity - set the cpu affinity of a process 4079 * @pid: pid of the process 4080 * @len: length in bytes of the bitmask pointed to by user_mask_ptr 4081 * @user_mask_ptr: user-space pointer to the new cpu mask 4082 */ 4083 SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len, 4084 unsigned long __user *, user_mask_ptr) 4085 { 4086 cpumask_var_t new_mask; 4087 int retval; 4088 4089 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) 4090 return -ENOMEM; 4091 4092 retval = get_user_cpu_mask(user_mask_ptr, len, new_mask); 4093 if (retval == 0) 4094 retval = sched_setaffinity(pid, new_mask); 4095 free_cpumask_var(new_mask); 4096 return retval; 4097 } 4098 4099 long sched_getaffinity(pid_t pid, struct cpumask *mask) 4100 { 4101 struct task_struct *p; 4102 unsigned long flags; 4103 int retval; 4104 4105 get_online_cpus(); 4106 rcu_read_lock(); 4107 4108 retval = -ESRCH; 4109 p = find_process_by_pid(pid); 4110 if (!p) 4111 goto out_unlock; 4112 4113 retval = security_task_getscheduler(p); 4114 if (retval) 4115 goto out_unlock; 4116 4117 raw_spin_lock_irqsave(&p->pi_lock, flags); 4118 cpumask_and(mask, &p->cpus_allowed, cpu_online_mask); 4119 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 4120 4121 out_unlock: 4122 rcu_read_unlock(); 4123 put_online_cpus(); 4124 4125 return retval; 4126 } 4127 4128 /** 4129 * sys_sched_getaffinity - get the cpu affinity of a process 4130 * @pid: pid of the process 4131 * @len: length in bytes of the bitmask pointed to by user_mask_ptr 4132 * @user_mask_ptr: user-space pointer to hold the current cpu mask 4133 */ 4134 SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len, 4135 unsigned long __user *, user_mask_ptr) 4136 { 4137 int ret; 4138 cpumask_var_t mask; 4139 4140 if ((len * BITS_PER_BYTE) < nr_cpu_ids) 4141 return -EINVAL; 4142 if (len & (sizeof(unsigned long)-1)) 4143 return -EINVAL; 4144 4145 if (!alloc_cpumask_var(&mask, GFP_KERNEL)) 4146 return -ENOMEM; 4147 4148 ret = sched_getaffinity(pid, mask); 4149 if (ret == 0) { 4150 size_t retlen = min_t(size_t, len, cpumask_size()); 4151 4152 if (copy_to_user(user_mask_ptr, mask, retlen)) 4153 ret = -EFAULT; 4154 else 4155 ret = retlen; 4156 } 4157 free_cpumask_var(mask); 4158 4159 return ret; 4160 } 4161 4162 /** 4163 * sys_sched_yield - yield the current processor to other threads. 4164 * 4165 * This function yields the current CPU to other tasks. If there are no 4166 * other threads running on this CPU then this function will return. 4167 */ 4168 SYSCALL_DEFINE0(sched_yield) 4169 { 4170 struct rq *rq = this_rq_lock(); 4171 4172 schedstat_inc(rq, yld_count); 4173 current->sched_class->yield_task(rq); 4174 4175 /* 4176 * Since we are going to call schedule() anyway, there's 4177 * no need to preempt or enable interrupts: 4178 */ 4179 __release(rq->lock); 4180 spin_release(&rq->lock.dep_map, 1, _THIS_IP_); 4181 do_raw_spin_unlock(&rq->lock); 4182 sched_preempt_enable_no_resched(); 4183 4184 schedule(); 4185 4186 return 0; 4187 } 4188 4189 static inline int should_resched(void) 4190 { 4191 return need_resched() && !(preempt_count() & PREEMPT_ACTIVE); 4192 } 4193 4194 static void __cond_resched(void) 4195 { 4196 add_preempt_count(PREEMPT_ACTIVE); 4197 __schedule(); 4198 sub_preempt_count(PREEMPT_ACTIVE); 4199 } 4200 4201 int __sched _cond_resched(void) 4202 { 4203 if (should_resched()) { 4204 __cond_resched(); 4205 return 1; 4206 } 4207 return 0; 4208 } 4209 EXPORT_SYMBOL(_cond_resched); 4210 4211 /* 4212 * __cond_resched_lock() - if a reschedule is pending, drop the given lock, 4213 * call schedule, and on return reacquire the lock. 4214 * 4215 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level 4216 * operations here to prevent schedule() from being called twice (once via 4217 * spin_unlock(), once by hand). 4218 */ 4219 int __cond_resched_lock(spinlock_t *lock) 4220 { 4221 int resched = should_resched(); 4222 int ret = 0; 4223 4224 lockdep_assert_held(lock); 4225 4226 if (spin_needbreak(lock) || resched) { 4227 spin_unlock(lock); 4228 if (resched) 4229 __cond_resched(); 4230 else 4231 cpu_relax(); 4232 ret = 1; 4233 spin_lock(lock); 4234 } 4235 return ret; 4236 } 4237 EXPORT_SYMBOL(__cond_resched_lock); 4238 4239 int __sched __cond_resched_softirq(void) 4240 { 4241 BUG_ON(!in_softirq()); 4242 4243 if (should_resched()) { 4244 local_bh_enable(); 4245 __cond_resched(); 4246 local_bh_disable(); 4247 return 1; 4248 } 4249 return 0; 4250 } 4251 EXPORT_SYMBOL(__cond_resched_softirq); 4252 4253 /** 4254 * yield - yield the current processor to other threads. 4255 * 4256 * Do not ever use this function, there's a 99% chance you're doing it wrong. 4257 * 4258 * The scheduler is at all times free to pick the calling task as the most 4259 * eligible task to run, if removing the yield() call from your code breaks 4260 * it, its already broken. 4261 * 4262 * Typical broken usage is: 4263 * 4264 * while (!event) 4265 * yield(); 4266 * 4267 * where one assumes that yield() will let 'the other' process run that will 4268 * make event true. If the current task is a SCHED_FIFO task that will never 4269 * happen. Never use yield() as a progress guarantee!! 4270 * 4271 * If you want to use yield() to wait for something, use wait_event(). 4272 * If you want to use yield() to be 'nice' for others, use cond_resched(). 4273 * If you still want to use yield(), do not! 4274 */ 4275 void __sched yield(void) 4276 { 4277 set_current_state(TASK_RUNNING); 4278 sys_sched_yield(); 4279 } 4280 EXPORT_SYMBOL(yield); 4281 4282 /** 4283 * yield_to - yield the current processor to another thread in 4284 * your thread group, or accelerate that thread toward the 4285 * processor it's on. 4286 * @p: target task 4287 * @preempt: whether task preemption is allowed or not 4288 * 4289 * It's the caller's job to ensure that the target task struct 4290 * can't go away on us before we can do any checks. 4291 * 4292 * Returns true if we indeed boosted the target task. 4293 */ 4294 bool __sched yield_to(struct task_struct *p, bool preempt) 4295 { 4296 struct task_struct *curr = current; 4297 struct rq *rq, *p_rq; 4298 unsigned long flags; 4299 bool yielded = 0; 4300 4301 local_irq_save(flags); 4302 rq = this_rq(); 4303 4304 again: 4305 p_rq = task_rq(p); 4306 double_rq_lock(rq, p_rq); 4307 while (task_rq(p) != p_rq) { 4308 double_rq_unlock(rq, p_rq); 4309 goto again; 4310 } 4311 4312 if (!curr->sched_class->yield_to_task) 4313 goto out; 4314 4315 if (curr->sched_class != p->sched_class) 4316 goto out; 4317 4318 if (task_running(p_rq, p) || p->state) 4319 goto out; 4320 4321 yielded = curr->sched_class->yield_to_task(rq, p, preempt); 4322 if (yielded) { 4323 schedstat_inc(rq, yld_count); 4324 /* 4325 * Make p's CPU reschedule; pick_next_entity takes care of 4326 * fairness. 4327 */ 4328 if (preempt && rq != p_rq) 4329 resched_task(p_rq->curr); 4330 } 4331 4332 out: 4333 double_rq_unlock(rq, p_rq); 4334 local_irq_restore(flags); 4335 4336 if (yielded) 4337 schedule(); 4338 4339 return yielded; 4340 } 4341 EXPORT_SYMBOL_GPL(yield_to); 4342 4343 /* 4344 * This task is about to go to sleep on IO. Increment rq->nr_iowait so 4345 * that process accounting knows that this is a task in IO wait state. 4346 */ 4347 void __sched io_schedule(void) 4348 { 4349 struct rq *rq = raw_rq(); 4350 4351 delayacct_blkio_start(); 4352 atomic_inc(&rq->nr_iowait); 4353 blk_flush_plug(current); 4354 current->in_iowait = 1; 4355 schedule(); 4356 current->in_iowait = 0; 4357 atomic_dec(&rq->nr_iowait); 4358 delayacct_blkio_end(); 4359 } 4360 EXPORT_SYMBOL(io_schedule); 4361 4362 long __sched io_schedule_timeout(long timeout) 4363 { 4364 struct rq *rq = raw_rq(); 4365 long ret; 4366 4367 delayacct_blkio_start(); 4368 atomic_inc(&rq->nr_iowait); 4369 blk_flush_plug(current); 4370 current->in_iowait = 1; 4371 ret = schedule_timeout(timeout); 4372 current->in_iowait = 0; 4373 atomic_dec(&rq->nr_iowait); 4374 delayacct_blkio_end(); 4375 return ret; 4376 } 4377 4378 /** 4379 * sys_sched_get_priority_max - return maximum RT priority. 4380 * @policy: scheduling class. 4381 * 4382 * this syscall returns the maximum rt_priority that can be used 4383 * by a given scheduling class. 4384 */ 4385 SYSCALL_DEFINE1(sched_get_priority_max, int, policy) 4386 { 4387 int ret = -EINVAL; 4388 4389 switch (policy) { 4390 case SCHED_FIFO: 4391 case SCHED_RR: 4392 ret = MAX_USER_RT_PRIO-1; 4393 break; 4394 case SCHED_NORMAL: 4395 case SCHED_BATCH: 4396 case SCHED_IDLE: 4397 ret = 0; 4398 break; 4399 } 4400 return ret; 4401 } 4402 4403 /** 4404 * sys_sched_get_priority_min - return minimum RT priority. 4405 * @policy: scheduling class. 4406 * 4407 * this syscall returns the minimum rt_priority that can be used 4408 * by a given scheduling class. 4409 */ 4410 SYSCALL_DEFINE1(sched_get_priority_min, int, policy) 4411 { 4412 int ret = -EINVAL; 4413 4414 switch (policy) { 4415 case SCHED_FIFO: 4416 case SCHED_RR: 4417 ret = 1; 4418 break; 4419 case SCHED_NORMAL: 4420 case SCHED_BATCH: 4421 case SCHED_IDLE: 4422 ret = 0; 4423 } 4424 return ret; 4425 } 4426 4427 /** 4428 * sys_sched_rr_get_interval - return the default timeslice of a process. 4429 * @pid: pid of the process. 4430 * @interval: userspace pointer to the timeslice value. 4431 * 4432 * this syscall writes the default timeslice value of a given process 4433 * into the user-space timespec buffer. A value of '0' means infinity. 4434 */ 4435 SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid, 4436 struct timespec __user *, interval) 4437 { 4438 struct task_struct *p; 4439 unsigned int time_slice; 4440 unsigned long flags; 4441 struct rq *rq; 4442 int retval; 4443 struct timespec t; 4444 4445 if (pid < 0) 4446 return -EINVAL; 4447 4448 retval = -ESRCH; 4449 rcu_read_lock(); 4450 p = find_process_by_pid(pid); 4451 if (!p) 4452 goto out_unlock; 4453 4454 retval = security_task_getscheduler(p); 4455 if (retval) 4456 goto out_unlock; 4457 4458 rq = task_rq_lock(p, &flags); 4459 time_slice = p->sched_class->get_rr_interval(rq, p); 4460 task_rq_unlock(rq, p, &flags); 4461 4462 rcu_read_unlock(); 4463 jiffies_to_timespec(time_slice, &t); 4464 retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0; 4465 return retval; 4466 4467 out_unlock: 4468 rcu_read_unlock(); 4469 return retval; 4470 } 4471 4472 static const char stat_nam[] = TASK_STATE_TO_CHAR_STR; 4473 4474 void sched_show_task(struct task_struct *p) 4475 { 4476 unsigned long free = 0; 4477 unsigned state; 4478 4479 state = p->state ? __ffs(p->state) + 1 : 0; 4480 printk(KERN_INFO "%-15.15s %c", p->comm, 4481 state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?'); 4482 #if BITS_PER_LONG == 32 4483 if (state == TASK_RUNNING) 4484 printk(KERN_CONT " running "); 4485 else 4486 printk(KERN_CONT " %08lx ", thread_saved_pc(p)); 4487 #else 4488 if (state == TASK_RUNNING) 4489 printk(KERN_CONT " running task "); 4490 else 4491 printk(KERN_CONT " %016lx ", thread_saved_pc(p)); 4492 #endif 4493 #ifdef CONFIG_DEBUG_STACK_USAGE 4494 free = stack_not_used(p); 4495 #endif 4496 printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free, 4497 task_pid_nr(p), task_pid_nr(rcu_dereference(p->real_parent)), 4498 (unsigned long)task_thread_info(p)->flags); 4499 4500 show_stack(p, NULL); 4501 } 4502 4503 void show_state_filter(unsigned long state_filter) 4504 { 4505 struct task_struct *g, *p; 4506 4507 #if BITS_PER_LONG == 32 4508 printk(KERN_INFO 4509 " task PC stack pid father\n"); 4510 #else 4511 printk(KERN_INFO 4512 " task PC stack pid father\n"); 4513 #endif 4514 rcu_read_lock(); 4515 do_each_thread(g, p) { 4516 /* 4517 * reset the NMI-timeout, listing all files on a slow 4518 * console might take a lot of time: 4519 */ 4520 touch_nmi_watchdog(); 4521 if (!state_filter || (p->state & state_filter)) 4522 sched_show_task(p); 4523 } while_each_thread(g, p); 4524 4525 touch_all_softlockup_watchdogs(); 4526 4527 #ifdef CONFIG_SCHED_DEBUG 4528 sysrq_sched_debug_show(); 4529 #endif 4530 rcu_read_unlock(); 4531 /* 4532 * Only show locks if all tasks are dumped: 4533 */ 4534 if (!state_filter) 4535 debug_show_all_locks(); 4536 } 4537 4538 void __cpuinit init_idle_bootup_task(struct task_struct *idle) 4539 { 4540 idle->sched_class = &idle_sched_class; 4541 } 4542 4543 /** 4544 * init_idle - set up an idle thread for a given CPU 4545 * @idle: task in question 4546 * @cpu: cpu the idle task belongs to 4547 * 4548 * NOTE: this function does not set the idle thread's NEED_RESCHED 4549 * flag, to make booting more robust. 4550 */ 4551 void __cpuinit init_idle(struct task_struct *idle, int cpu) 4552 { 4553 struct rq *rq = cpu_rq(cpu); 4554 unsigned long flags; 4555 4556 raw_spin_lock_irqsave(&rq->lock, flags); 4557 4558 __sched_fork(idle); 4559 idle->state = TASK_RUNNING; 4560 idle->se.exec_start = sched_clock(); 4561 4562 do_set_cpus_allowed(idle, cpumask_of(cpu)); 4563 /* 4564 * We're having a chicken and egg problem, even though we are 4565 * holding rq->lock, the cpu isn't yet set to this cpu so the 4566 * lockdep check in task_group() will fail. 4567 * 4568 * Similar case to sched_fork(). / Alternatively we could 4569 * use task_rq_lock() here and obtain the other rq->lock. 4570 * 4571 * Silence PROVE_RCU 4572 */ 4573 rcu_read_lock(); 4574 __set_task_cpu(idle, cpu); 4575 rcu_read_unlock(); 4576 4577 rq->curr = rq->idle = idle; 4578 #if defined(CONFIG_SMP) 4579 idle->on_cpu = 1; 4580 #endif 4581 raw_spin_unlock_irqrestore(&rq->lock, flags); 4582 4583 /* Set the preempt count _outside_ the spinlocks! */ 4584 task_thread_info(idle)->preempt_count = 0; 4585 4586 /* 4587 * The idle tasks have their own, simple scheduling class: 4588 */ 4589 idle->sched_class = &idle_sched_class; 4590 ftrace_graph_init_idle_task(idle, cpu); 4591 #if defined(CONFIG_SMP) 4592 sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu); 4593 #endif 4594 } 4595 4596 #ifdef CONFIG_SMP 4597 void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask) 4598 { 4599 if (p->sched_class && p->sched_class->set_cpus_allowed) 4600 p->sched_class->set_cpus_allowed(p, new_mask); 4601 4602 cpumask_copy(&p->cpus_allowed, new_mask); 4603 p->nr_cpus_allowed = cpumask_weight(new_mask); 4604 } 4605 4606 /* 4607 * This is how migration works: 4608 * 4609 * 1) we invoke migration_cpu_stop() on the target CPU using 4610 * stop_one_cpu(). 4611 * 2) stopper starts to run (implicitly forcing the migrated thread 4612 * off the CPU) 4613 * 3) it checks whether the migrated task is still in the wrong runqueue. 4614 * 4) if it's in the wrong runqueue then the migration thread removes 4615 * it and puts it into the right queue. 4616 * 5) stopper completes and stop_one_cpu() returns and the migration 4617 * is done. 4618 */ 4619 4620 /* 4621 * Change a given task's CPU affinity. Migrate the thread to a 4622 * proper CPU and schedule it away if the CPU it's executing on 4623 * is removed from the allowed bitmask. 4624 * 4625 * NOTE: the caller must have a valid reference to the task, the 4626 * task must not exit() & deallocate itself prematurely. The 4627 * call is not atomic; no spinlocks may be held. 4628 */ 4629 int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask) 4630 { 4631 unsigned long flags; 4632 struct rq *rq; 4633 unsigned int dest_cpu; 4634 int ret = 0; 4635 4636 rq = task_rq_lock(p, &flags); 4637 4638 if (cpumask_equal(&p->cpus_allowed, new_mask)) 4639 goto out; 4640 4641 if (!cpumask_intersects(new_mask, cpu_active_mask)) { 4642 ret = -EINVAL; 4643 goto out; 4644 } 4645 4646 if (unlikely((p->flags & PF_THREAD_BOUND) && p != current)) { 4647 ret = -EINVAL; 4648 goto out; 4649 } 4650 4651 do_set_cpus_allowed(p, new_mask); 4652 4653 /* Can the task run on the task's current CPU? If so, we're done */ 4654 if (cpumask_test_cpu(task_cpu(p), new_mask)) 4655 goto out; 4656 4657 dest_cpu = cpumask_any_and(cpu_active_mask, new_mask); 4658 if (p->on_rq) { 4659 struct migration_arg arg = { p, dest_cpu }; 4660 /* Need help from migration thread: drop lock and wait. */ 4661 task_rq_unlock(rq, p, &flags); 4662 stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg); 4663 tlb_migrate_finish(p->mm); 4664 return 0; 4665 } 4666 out: 4667 task_rq_unlock(rq, p, &flags); 4668 4669 return ret; 4670 } 4671 EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr); 4672 4673 /* 4674 * Move (not current) task off this cpu, onto dest cpu. We're doing 4675 * this because either it can't run here any more (set_cpus_allowed() 4676 * away from this CPU, or CPU going down), or because we're 4677 * attempting to rebalance this task on exec (sched_exec). 4678 * 4679 * So we race with normal scheduler movements, but that's OK, as long 4680 * as the task is no longer on this CPU. 4681 * 4682 * Returns non-zero if task was successfully migrated. 4683 */ 4684 static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu) 4685 { 4686 struct rq *rq_dest, *rq_src; 4687 int ret = 0; 4688 4689 if (unlikely(!cpu_active(dest_cpu))) 4690 return ret; 4691 4692 rq_src = cpu_rq(src_cpu); 4693 rq_dest = cpu_rq(dest_cpu); 4694 4695 raw_spin_lock(&p->pi_lock); 4696 double_rq_lock(rq_src, rq_dest); 4697 /* Already moved. */ 4698 if (task_cpu(p) != src_cpu) 4699 goto done; 4700 /* Affinity changed (again). */ 4701 if (!cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p))) 4702 goto fail; 4703 4704 /* 4705 * If we're not on a rq, the next wake-up will ensure we're 4706 * placed properly. 4707 */ 4708 if (p->on_rq) { 4709 dequeue_task(rq_src, p, 0); 4710 set_task_cpu(p, dest_cpu); 4711 enqueue_task(rq_dest, p, 0); 4712 check_preempt_curr(rq_dest, p, 0); 4713 } 4714 done: 4715 ret = 1; 4716 fail: 4717 double_rq_unlock(rq_src, rq_dest); 4718 raw_spin_unlock(&p->pi_lock); 4719 return ret; 4720 } 4721 4722 /* 4723 * migration_cpu_stop - this will be executed by a highprio stopper thread 4724 * and performs thread migration by bumping thread off CPU then 4725 * 'pushing' onto another runqueue. 4726 */ 4727 static int migration_cpu_stop(void *data) 4728 { 4729 struct migration_arg *arg = data; 4730 4731 /* 4732 * The original target cpu might have gone down and we might 4733 * be on another cpu but it doesn't matter. 4734 */ 4735 local_irq_disable(); 4736 __migrate_task(arg->task, raw_smp_processor_id(), arg->dest_cpu); 4737 local_irq_enable(); 4738 return 0; 4739 } 4740 4741 #ifdef CONFIG_HOTPLUG_CPU 4742 4743 /* 4744 * Ensures that the idle task is using init_mm right before its cpu goes 4745 * offline. 4746 */ 4747 void idle_task_exit(void) 4748 { 4749 struct mm_struct *mm = current->active_mm; 4750 4751 BUG_ON(cpu_online(smp_processor_id())); 4752 4753 if (mm != &init_mm) 4754 switch_mm(mm, &init_mm, current); 4755 mmdrop(mm); 4756 } 4757 4758 /* 4759 * Since this CPU is going 'away' for a while, fold any nr_active delta 4760 * we might have. Assumes we're called after migrate_tasks() so that the 4761 * nr_active count is stable. 4762 * 4763 * Also see the comment "Global load-average calculations". 4764 */ 4765 static void calc_load_migrate(struct rq *rq) 4766 { 4767 long delta = calc_load_fold_active(rq); 4768 if (delta) 4769 atomic_long_add(delta, &calc_load_tasks); 4770 } 4771 4772 /* 4773 * Migrate all tasks from the rq, sleeping tasks will be migrated by 4774 * try_to_wake_up()->select_task_rq(). 4775 * 4776 * Called with rq->lock held even though we'er in stop_machine() and 4777 * there's no concurrency possible, we hold the required locks anyway 4778 * because of lock validation efforts. 4779 */ 4780 static void migrate_tasks(unsigned int dead_cpu) 4781 { 4782 struct rq *rq = cpu_rq(dead_cpu); 4783 struct task_struct *next, *stop = rq->stop; 4784 int dest_cpu; 4785 4786 /* 4787 * Fudge the rq selection such that the below task selection loop 4788 * doesn't get stuck on the currently eligible stop task. 4789 * 4790 * We're currently inside stop_machine() and the rq is either stuck 4791 * in the stop_machine_cpu_stop() loop, or we're executing this code, 4792 * either way we should never end up calling schedule() until we're 4793 * done here. 4794 */ 4795 rq->stop = NULL; 4796 4797 for ( ; ; ) { 4798 /* 4799 * There's this thread running, bail when that's the only 4800 * remaining thread. 4801 */ 4802 if (rq->nr_running == 1) 4803 break; 4804 4805 next = pick_next_task(rq); 4806 BUG_ON(!next); 4807 next->sched_class->put_prev_task(rq, next); 4808 4809 /* Find suitable destination for @next, with force if needed. */ 4810 dest_cpu = select_fallback_rq(dead_cpu, next); 4811 raw_spin_unlock(&rq->lock); 4812 4813 __migrate_task(next, dead_cpu, dest_cpu); 4814 4815 raw_spin_lock(&rq->lock); 4816 } 4817 4818 rq->stop = stop; 4819 } 4820 4821 #endif /* CONFIG_HOTPLUG_CPU */ 4822 4823 #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL) 4824 4825 static struct ctl_table sd_ctl_dir[] = { 4826 { 4827 .procname = "sched_domain", 4828 .mode = 0555, 4829 }, 4830 {} 4831 }; 4832 4833 static struct ctl_table sd_ctl_root[] = { 4834 { 4835 .procname = "kernel", 4836 .mode = 0555, 4837 .child = sd_ctl_dir, 4838 }, 4839 {} 4840 }; 4841 4842 static struct ctl_table *sd_alloc_ctl_entry(int n) 4843 { 4844 struct ctl_table *entry = 4845 kcalloc(n, sizeof(struct ctl_table), GFP_KERNEL); 4846 4847 return entry; 4848 } 4849 4850 static void sd_free_ctl_entry(struct ctl_table **tablep) 4851 { 4852 struct ctl_table *entry; 4853 4854 /* 4855 * In the intermediate directories, both the child directory and 4856 * procname are dynamically allocated and could fail but the mode 4857 * will always be set. In the lowest directory the names are 4858 * static strings and all have proc handlers. 4859 */ 4860 for (entry = *tablep; entry->mode; entry++) { 4861 if (entry->child) 4862 sd_free_ctl_entry(&entry->child); 4863 if (entry->proc_handler == NULL) 4864 kfree(entry->procname); 4865 } 4866 4867 kfree(*tablep); 4868 *tablep = NULL; 4869 } 4870 4871 static int min_load_idx = 0; 4872 static int max_load_idx = CPU_LOAD_IDX_MAX; 4873 4874 static void 4875 set_table_entry(struct ctl_table *entry, 4876 const char *procname, void *data, int maxlen, 4877 umode_t mode, proc_handler *proc_handler, 4878 bool load_idx) 4879 { 4880 entry->procname = procname; 4881 entry->data = data; 4882 entry->maxlen = maxlen; 4883 entry->mode = mode; 4884 entry->proc_handler = proc_handler; 4885 4886 if (load_idx) { 4887 entry->extra1 = &min_load_idx; 4888 entry->extra2 = &max_load_idx; 4889 } 4890 } 4891 4892 static struct ctl_table * 4893 sd_alloc_ctl_domain_table(struct sched_domain *sd) 4894 { 4895 struct ctl_table *table = sd_alloc_ctl_entry(13); 4896 4897 if (table == NULL) 4898 return NULL; 4899 4900 set_table_entry(&table[0], "min_interval", &sd->min_interval, 4901 sizeof(long), 0644, proc_doulongvec_minmax, false); 4902 set_table_entry(&table[1], "max_interval", &sd->max_interval, 4903 sizeof(long), 0644, proc_doulongvec_minmax, false); 4904 set_table_entry(&table[2], "busy_idx", &sd->busy_idx, 4905 sizeof(int), 0644, proc_dointvec_minmax, true); 4906 set_table_entry(&table[3], "idle_idx", &sd->idle_idx, 4907 sizeof(int), 0644, proc_dointvec_minmax, true); 4908 set_table_entry(&table[4], "newidle_idx", &sd->newidle_idx, 4909 sizeof(int), 0644, proc_dointvec_minmax, true); 4910 set_table_entry(&table[5], "wake_idx", &sd->wake_idx, 4911 sizeof(int), 0644, proc_dointvec_minmax, true); 4912 set_table_entry(&table[6], "forkexec_idx", &sd->forkexec_idx, 4913 sizeof(int), 0644, proc_dointvec_minmax, true); 4914 set_table_entry(&table[7], "busy_factor", &sd->busy_factor, 4915 sizeof(int), 0644, proc_dointvec_minmax, false); 4916 set_table_entry(&table[8], "imbalance_pct", &sd->imbalance_pct, 4917 sizeof(int), 0644, proc_dointvec_minmax, false); 4918 set_table_entry(&table[9], "cache_nice_tries", 4919 &sd->cache_nice_tries, 4920 sizeof(int), 0644, proc_dointvec_minmax, false); 4921 set_table_entry(&table[10], "flags", &sd->flags, 4922 sizeof(int), 0644, proc_dointvec_minmax, false); 4923 set_table_entry(&table[11], "name", sd->name, 4924 CORENAME_MAX_SIZE, 0444, proc_dostring, false); 4925 /* &table[12] is terminator */ 4926 4927 return table; 4928 } 4929 4930 static ctl_table *sd_alloc_ctl_cpu_table(int cpu) 4931 { 4932 struct ctl_table *entry, *table; 4933 struct sched_domain *sd; 4934 int domain_num = 0, i; 4935 char buf[32]; 4936 4937 for_each_domain(cpu, sd) 4938 domain_num++; 4939 entry = table = sd_alloc_ctl_entry(domain_num + 1); 4940 if (table == NULL) 4941 return NULL; 4942 4943 i = 0; 4944 for_each_domain(cpu, sd) { 4945 snprintf(buf, 32, "domain%d", i); 4946 entry->procname = kstrdup(buf, GFP_KERNEL); 4947 entry->mode = 0555; 4948 entry->child = sd_alloc_ctl_domain_table(sd); 4949 entry++; 4950 i++; 4951 } 4952 return table; 4953 } 4954 4955 static struct ctl_table_header *sd_sysctl_header; 4956 static void register_sched_domain_sysctl(void) 4957 { 4958 int i, cpu_num = num_possible_cpus(); 4959 struct ctl_table *entry = sd_alloc_ctl_entry(cpu_num + 1); 4960 char buf[32]; 4961 4962 WARN_ON(sd_ctl_dir[0].child); 4963 sd_ctl_dir[0].child = entry; 4964 4965 if (entry == NULL) 4966 return; 4967 4968 for_each_possible_cpu(i) { 4969 snprintf(buf, 32, "cpu%d", i); 4970 entry->procname = kstrdup(buf, GFP_KERNEL); 4971 entry->mode = 0555; 4972 entry->child = sd_alloc_ctl_cpu_table(i); 4973 entry++; 4974 } 4975 4976 WARN_ON(sd_sysctl_header); 4977 sd_sysctl_header = register_sysctl_table(sd_ctl_root); 4978 } 4979 4980 /* may be called multiple times per register */ 4981 static void unregister_sched_domain_sysctl(void) 4982 { 4983 if (sd_sysctl_header) 4984 unregister_sysctl_table(sd_sysctl_header); 4985 sd_sysctl_header = NULL; 4986 if (sd_ctl_dir[0].child) 4987 sd_free_ctl_entry(&sd_ctl_dir[0].child); 4988 } 4989 #else 4990 static void register_sched_domain_sysctl(void) 4991 { 4992 } 4993 static void unregister_sched_domain_sysctl(void) 4994 { 4995 } 4996 #endif 4997 4998 static void set_rq_online(struct rq *rq) 4999 { 5000 if (!rq->online) { 5001 const struct sched_class *class; 5002 5003 cpumask_set_cpu(rq->cpu, rq->rd->online); 5004 rq->online = 1; 5005 5006 for_each_class(class) { 5007 if (class->rq_online) 5008 class->rq_online(rq); 5009 } 5010 } 5011 } 5012 5013 static void set_rq_offline(struct rq *rq) 5014 { 5015 if (rq->online) { 5016 const struct sched_class *class; 5017 5018 for_each_class(class) { 5019 if (class->rq_offline) 5020 class->rq_offline(rq); 5021 } 5022 5023 cpumask_clear_cpu(rq->cpu, rq->rd->online); 5024 rq->online = 0; 5025 } 5026 } 5027 5028 /* 5029 * migration_call - callback that gets triggered when a CPU is added. 5030 * Here we can start up the necessary migration thread for the new CPU. 5031 */ 5032 static int __cpuinit 5033 migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu) 5034 { 5035 int cpu = (long)hcpu; 5036 unsigned long flags; 5037 struct rq *rq = cpu_rq(cpu); 5038 5039 switch (action & ~CPU_TASKS_FROZEN) { 5040 5041 case CPU_UP_PREPARE: 5042 rq->calc_load_update = calc_load_update; 5043 break; 5044 5045 case CPU_ONLINE: 5046 /* Update our root-domain */ 5047 raw_spin_lock_irqsave(&rq->lock, flags); 5048 if (rq->rd) { 5049 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); 5050 5051 set_rq_online(rq); 5052 } 5053 raw_spin_unlock_irqrestore(&rq->lock, flags); 5054 break; 5055 5056 #ifdef CONFIG_HOTPLUG_CPU 5057 case CPU_DYING: 5058 sched_ttwu_pending(); 5059 /* Update our root-domain */ 5060 raw_spin_lock_irqsave(&rq->lock, flags); 5061 if (rq->rd) { 5062 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); 5063 set_rq_offline(rq); 5064 } 5065 migrate_tasks(cpu); 5066 BUG_ON(rq->nr_running != 1); /* the migration thread */ 5067 raw_spin_unlock_irqrestore(&rq->lock, flags); 5068 break; 5069 5070 case CPU_DEAD: 5071 calc_load_migrate(rq); 5072 break; 5073 #endif 5074 } 5075 5076 update_max_interval(); 5077 5078 return NOTIFY_OK; 5079 } 5080 5081 /* 5082 * Register at high priority so that task migration (migrate_all_tasks) 5083 * happens before everything else. This has to be lower priority than 5084 * the notifier in the perf_event subsystem, though. 5085 */ 5086 static struct notifier_block __cpuinitdata migration_notifier = { 5087 .notifier_call = migration_call, 5088 .priority = CPU_PRI_MIGRATION, 5089 }; 5090 5091 static int __cpuinit sched_cpu_active(struct notifier_block *nfb, 5092 unsigned long action, void *hcpu) 5093 { 5094 switch (action & ~CPU_TASKS_FROZEN) { 5095 case CPU_STARTING: 5096 case CPU_DOWN_FAILED: 5097 set_cpu_active((long)hcpu, true); 5098 return NOTIFY_OK; 5099 default: 5100 return NOTIFY_DONE; 5101 } 5102 } 5103 5104 static int __cpuinit sched_cpu_inactive(struct notifier_block *nfb, 5105 unsigned long action, void *hcpu) 5106 { 5107 switch (action & ~CPU_TASKS_FROZEN) { 5108 case CPU_DOWN_PREPARE: 5109 set_cpu_active((long)hcpu, false); 5110 return NOTIFY_OK; 5111 default: 5112 return NOTIFY_DONE; 5113 } 5114 } 5115 5116 static int __init migration_init(void) 5117 { 5118 void *cpu = (void *)(long)smp_processor_id(); 5119 int err; 5120 5121 /* Initialize migration for the boot CPU */ 5122 err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu); 5123 BUG_ON(err == NOTIFY_BAD); 5124 migration_call(&migration_notifier, CPU_ONLINE, cpu); 5125 register_cpu_notifier(&migration_notifier); 5126 5127 /* Register cpu active notifiers */ 5128 cpu_notifier(sched_cpu_active, CPU_PRI_SCHED_ACTIVE); 5129 cpu_notifier(sched_cpu_inactive, CPU_PRI_SCHED_INACTIVE); 5130 5131 return 0; 5132 } 5133 early_initcall(migration_init); 5134 #endif 5135 5136 #ifdef CONFIG_SMP 5137 5138 static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */ 5139 5140 #ifdef CONFIG_SCHED_DEBUG 5141 5142 static __read_mostly int sched_debug_enabled; 5143 5144 static int __init sched_debug_setup(char *str) 5145 { 5146 sched_debug_enabled = 1; 5147 5148 return 0; 5149 } 5150 early_param("sched_debug", sched_debug_setup); 5151 5152 static inline bool sched_debug(void) 5153 { 5154 return sched_debug_enabled; 5155 } 5156 5157 static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level, 5158 struct cpumask *groupmask) 5159 { 5160 struct sched_group *group = sd->groups; 5161 char str[256]; 5162 5163 cpulist_scnprintf(str, sizeof(str), sched_domain_span(sd)); 5164 cpumask_clear(groupmask); 5165 5166 printk(KERN_DEBUG "%*s domain %d: ", level, "", level); 5167 5168 if (!(sd->flags & SD_LOAD_BALANCE)) { 5169 printk("does not load-balance\n"); 5170 if (sd->parent) 5171 printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain" 5172 " has parent"); 5173 return -1; 5174 } 5175 5176 printk(KERN_CONT "span %s level %s\n", str, sd->name); 5177 5178 if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) { 5179 printk(KERN_ERR "ERROR: domain->span does not contain " 5180 "CPU%d\n", cpu); 5181 } 5182 if (!cpumask_test_cpu(cpu, sched_group_cpus(group))) { 5183 printk(KERN_ERR "ERROR: domain->groups does not contain" 5184 " CPU%d\n", cpu); 5185 } 5186 5187 printk(KERN_DEBUG "%*s groups:", level + 1, ""); 5188 do { 5189 if (!group) { 5190 printk("\n"); 5191 printk(KERN_ERR "ERROR: group is NULL\n"); 5192 break; 5193 } 5194 5195 /* 5196 * Even though we initialize ->power to something semi-sane, 5197 * we leave power_orig unset. This allows us to detect if 5198 * domain iteration is still funny without causing /0 traps. 5199 */ 5200 if (!group->sgp->power_orig) { 5201 printk(KERN_CONT "\n"); 5202 printk(KERN_ERR "ERROR: domain->cpu_power not " 5203 "set\n"); 5204 break; 5205 } 5206 5207 if (!cpumask_weight(sched_group_cpus(group))) { 5208 printk(KERN_CONT "\n"); 5209 printk(KERN_ERR "ERROR: empty group\n"); 5210 break; 5211 } 5212 5213 if (!(sd->flags & SD_OVERLAP) && 5214 cpumask_intersects(groupmask, sched_group_cpus(group))) { 5215 printk(KERN_CONT "\n"); 5216 printk(KERN_ERR "ERROR: repeated CPUs\n"); 5217 break; 5218 } 5219 5220 cpumask_or(groupmask, groupmask, sched_group_cpus(group)); 5221 5222 cpulist_scnprintf(str, sizeof(str), sched_group_cpus(group)); 5223 5224 printk(KERN_CONT " %s", str); 5225 if (group->sgp->power != SCHED_POWER_SCALE) { 5226 printk(KERN_CONT " (cpu_power = %d)", 5227 group->sgp->power); 5228 } 5229 5230 group = group->next; 5231 } while (group != sd->groups); 5232 printk(KERN_CONT "\n"); 5233 5234 if (!cpumask_equal(sched_domain_span(sd), groupmask)) 5235 printk(KERN_ERR "ERROR: groups don't span domain->span\n"); 5236 5237 if (sd->parent && 5238 !cpumask_subset(groupmask, sched_domain_span(sd->parent))) 5239 printk(KERN_ERR "ERROR: parent span is not a superset " 5240 "of domain->span\n"); 5241 return 0; 5242 } 5243 5244 static void sched_domain_debug(struct sched_domain *sd, int cpu) 5245 { 5246 int level = 0; 5247 5248 if (!sched_debug_enabled) 5249 return; 5250 5251 if (!sd) { 5252 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu); 5253 return; 5254 } 5255 5256 printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu); 5257 5258 for (;;) { 5259 if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask)) 5260 break; 5261 level++; 5262 sd = sd->parent; 5263 if (!sd) 5264 break; 5265 } 5266 } 5267 #else /* !CONFIG_SCHED_DEBUG */ 5268 # define sched_domain_debug(sd, cpu) do { } while (0) 5269 static inline bool sched_debug(void) 5270 { 5271 return false; 5272 } 5273 #endif /* CONFIG_SCHED_DEBUG */ 5274 5275 static int sd_degenerate(struct sched_domain *sd) 5276 { 5277 if (cpumask_weight(sched_domain_span(sd)) == 1) 5278 return 1; 5279 5280 /* Following flags need at least 2 groups */ 5281 if (sd->flags & (SD_LOAD_BALANCE | 5282 SD_BALANCE_NEWIDLE | 5283 SD_BALANCE_FORK | 5284 SD_BALANCE_EXEC | 5285 SD_SHARE_CPUPOWER | 5286 SD_SHARE_PKG_RESOURCES)) { 5287 if (sd->groups != sd->groups->next) 5288 return 0; 5289 } 5290 5291 /* Following flags don't use groups */ 5292 if (sd->flags & (SD_WAKE_AFFINE)) 5293 return 0; 5294 5295 return 1; 5296 } 5297 5298 static int 5299 sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent) 5300 { 5301 unsigned long cflags = sd->flags, pflags = parent->flags; 5302 5303 if (sd_degenerate(parent)) 5304 return 1; 5305 5306 if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent))) 5307 return 0; 5308 5309 /* Flags needing groups don't count if only 1 group in parent */ 5310 if (parent->groups == parent->groups->next) { 5311 pflags &= ~(SD_LOAD_BALANCE | 5312 SD_BALANCE_NEWIDLE | 5313 SD_BALANCE_FORK | 5314 SD_BALANCE_EXEC | 5315 SD_SHARE_CPUPOWER | 5316 SD_SHARE_PKG_RESOURCES); 5317 if (nr_node_ids == 1) 5318 pflags &= ~SD_SERIALIZE; 5319 } 5320 if (~cflags & pflags) 5321 return 0; 5322 5323 return 1; 5324 } 5325 5326 static void free_rootdomain(struct rcu_head *rcu) 5327 { 5328 struct root_domain *rd = container_of(rcu, struct root_domain, rcu); 5329 5330 cpupri_cleanup(&rd->cpupri); 5331 free_cpumask_var(rd->rto_mask); 5332 free_cpumask_var(rd->online); 5333 free_cpumask_var(rd->span); 5334 kfree(rd); 5335 } 5336 5337 static void rq_attach_root(struct rq *rq, struct root_domain *rd) 5338 { 5339 struct root_domain *old_rd = NULL; 5340 unsigned long flags; 5341 5342 raw_spin_lock_irqsave(&rq->lock, flags); 5343 5344 if (rq->rd) { 5345 old_rd = rq->rd; 5346 5347 if (cpumask_test_cpu(rq->cpu, old_rd->online)) 5348 set_rq_offline(rq); 5349 5350 cpumask_clear_cpu(rq->cpu, old_rd->span); 5351 5352 /* 5353 * If we dont want to free the old_rt yet then 5354 * set old_rd to NULL to skip the freeing later 5355 * in this function: 5356 */ 5357 if (!atomic_dec_and_test(&old_rd->refcount)) 5358 old_rd = NULL; 5359 } 5360 5361 atomic_inc(&rd->refcount); 5362 rq->rd = rd; 5363 5364 cpumask_set_cpu(rq->cpu, rd->span); 5365 if (cpumask_test_cpu(rq->cpu, cpu_active_mask)) 5366 set_rq_online(rq); 5367 5368 raw_spin_unlock_irqrestore(&rq->lock, flags); 5369 5370 if (old_rd) 5371 call_rcu_sched(&old_rd->rcu, free_rootdomain); 5372 } 5373 5374 static int init_rootdomain(struct root_domain *rd) 5375 { 5376 memset(rd, 0, sizeof(*rd)); 5377 5378 if (!alloc_cpumask_var(&rd->span, GFP_KERNEL)) 5379 goto out; 5380 if (!alloc_cpumask_var(&rd->online, GFP_KERNEL)) 5381 goto free_span; 5382 if (!alloc_cpumask_var(&rd->rto_mask, GFP_KERNEL)) 5383 goto free_online; 5384 5385 if (cpupri_init(&rd->cpupri) != 0) 5386 goto free_rto_mask; 5387 return 0; 5388 5389 free_rto_mask: 5390 free_cpumask_var(rd->rto_mask); 5391 free_online: 5392 free_cpumask_var(rd->online); 5393 free_span: 5394 free_cpumask_var(rd->span); 5395 out: 5396 return -ENOMEM; 5397 } 5398 5399 /* 5400 * By default the system creates a single root-domain with all cpus as 5401 * members (mimicking the global state we have today). 5402 */ 5403 struct root_domain def_root_domain; 5404 5405 static void init_defrootdomain(void) 5406 { 5407 init_rootdomain(&def_root_domain); 5408 5409 atomic_set(&def_root_domain.refcount, 1); 5410 } 5411 5412 static struct root_domain *alloc_rootdomain(void) 5413 { 5414 struct root_domain *rd; 5415 5416 rd = kmalloc(sizeof(*rd), GFP_KERNEL); 5417 if (!rd) 5418 return NULL; 5419 5420 if (init_rootdomain(rd) != 0) { 5421 kfree(rd); 5422 return NULL; 5423 } 5424 5425 return rd; 5426 } 5427 5428 static void free_sched_groups(struct sched_group *sg, int free_sgp) 5429 { 5430 struct sched_group *tmp, *first; 5431 5432 if (!sg) 5433 return; 5434 5435 first = sg; 5436 do { 5437 tmp = sg->next; 5438 5439 if (free_sgp && atomic_dec_and_test(&sg->sgp->ref)) 5440 kfree(sg->sgp); 5441 5442 kfree(sg); 5443 sg = tmp; 5444 } while (sg != first); 5445 } 5446 5447 static void free_sched_domain(struct rcu_head *rcu) 5448 { 5449 struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu); 5450 5451 /* 5452 * If its an overlapping domain it has private groups, iterate and 5453 * nuke them all. 5454 */ 5455 if (sd->flags & SD_OVERLAP) { 5456 free_sched_groups(sd->groups, 1); 5457 } else if (atomic_dec_and_test(&sd->groups->ref)) { 5458 kfree(sd->groups->sgp); 5459 kfree(sd->groups); 5460 } 5461 kfree(sd); 5462 } 5463 5464 static void destroy_sched_domain(struct sched_domain *sd, int cpu) 5465 { 5466 call_rcu(&sd->rcu, free_sched_domain); 5467 } 5468 5469 static void destroy_sched_domains(struct sched_domain *sd, int cpu) 5470 { 5471 for (; sd; sd = sd->parent) 5472 destroy_sched_domain(sd, cpu); 5473 } 5474 5475 /* 5476 * Keep a special pointer to the highest sched_domain that has 5477 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this 5478 * allows us to avoid some pointer chasing select_idle_sibling(). 5479 * 5480 * Also keep a unique ID per domain (we use the first cpu number in 5481 * the cpumask of the domain), this allows us to quickly tell if 5482 * two cpus are in the same cache domain, see cpus_share_cache(). 5483 */ 5484 DEFINE_PER_CPU(struct sched_domain *, sd_llc); 5485 DEFINE_PER_CPU(int, sd_llc_id); 5486 5487 static void update_top_cache_domain(int cpu) 5488 { 5489 struct sched_domain *sd; 5490 int id = cpu; 5491 5492 sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES); 5493 if (sd) 5494 id = cpumask_first(sched_domain_span(sd)); 5495 5496 rcu_assign_pointer(per_cpu(sd_llc, cpu), sd); 5497 per_cpu(sd_llc_id, cpu) = id; 5498 } 5499 5500 /* 5501 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must 5502 * hold the hotplug lock. 5503 */ 5504 static void 5505 cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu) 5506 { 5507 struct rq *rq = cpu_rq(cpu); 5508 struct sched_domain *tmp; 5509 5510 /* Remove the sched domains which do not contribute to scheduling. */ 5511 for (tmp = sd; tmp; ) { 5512 struct sched_domain *parent = tmp->parent; 5513 if (!parent) 5514 break; 5515 5516 if (sd_parent_degenerate(tmp, parent)) { 5517 tmp->parent = parent->parent; 5518 if (parent->parent) 5519 parent->parent->child = tmp; 5520 destroy_sched_domain(parent, cpu); 5521 } else 5522 tmp = tmp->parent; 5523 } 5524 5525 if (sd && sd_degenerate(sd)) { 5526 tmp = sd; 5527 sd = sd->parent; 5528 destroy_sched_domain(tmp, cpu); 5529 if (sd) 5530 sd->child = NULL; 5531 } 5532 5533 sched_domain_debug(sd, cpu); 5534 5535 rq_attach_root(rq, rd); 5536 tmp = rq->sd; 5537 rcu_assign_pointer(rq->sd, sd); 5538 destroy_sched_domains(tmp, cpu); 5539 5540 update_top_cache_domain(cpu); 5541 } 5542 5543 /* cpus with isolated domains */ 5544 static cpumask_var_t cpu_isolated_map; 5545 5546 /* Setup the mask of cpus configured for isolated domains */ 5547 static int __init isolated_cpu_setup(char *str) 5548 { 5549 alloc_bootmem_cpumask_var(&cpu_isolated_map); 5550 cpulist_parse(str, cpu_isolated_map); 5551 return 1; 5552 } 5553 5554 __setup("isolcpus=", isolated_cpu_setup); 5555 5556 static const struct cpumask *cpu_cpu_mask(int cpu) 5557 { 5558 return cpumask_of_node(cpu_to_node(cpu)); 5559 } 5560 5561 struct sd_data { 5562 struct sched_domain **__percpu sd; 5563 struct sched_group **__percpu sg; 5564 struct sched_group_power **__percpu sgp; 5565 }; 5566 5567 struct s_data { 5568 struct sched_domain ** __percpu sd; 5569 struct root_domain *rd; 5570 }; 5571 5572 enum s_alloc { 5573 sa_rootdomain, 5574 sa_sd, 5575 sa_sd_storage, 5576 sa_none, 5577 }; 5578 5579 struct sched_domain_topology_level; 5580 5581 typedef struct sched_domain *(*sched_domain_init_f)(struct sched_domain_topology_level *tl, int cpu); 5582 typedef const struct cpumask *(*sched_domain_mask_f)(int cpu); 5583 5584 #define SDTL_OVERLAP 0x01 5585 5586 struct sched_domain_topology_level { 5587 sched_domain_init_f init; 5588 sched_domain_mask_f mask; 5589 int flags; 5590 int numa_level; 5591 struct sd_data data; 5592 }; 5593 5594 /* 5595 * Build an iteration mask that can exclude certain CPUs from the upwards 5596 * domain traversal. 5597 * 5598 * Asymmetric node setups can result in situations where the domain tree is of 5599 * unequal depth, make sure to skip domains that already cover the entire 5600 * range. 5601 * 5602 * In that case build_sched_domains() will have terminated the iteration early 5603 * and our sibling sd spans will be empty. Domains should always include the 5604 * cpu they're built on, so check that. 5605 * 5606 */ 5607 static void build_group_mask(struct sched_domain *sd, struct sched_group *sg) 5608 { 5609 const struct cpumask *span = sched_domain_span(sd); 5610 struct sd_data *sdd = sd->private; 5611 struct sched_domain *sibling; 5612 int i; 5613 5614 for_each_cpu(i, span) { 5615 sibling = *per_cpu_ptr(sdd->sd, i); 5616 if (!cpumask_test_cpu(i, sched_domain_span(sibling))) 5617 continue; 5618 5619 cpumask_set_cpu(i, sched_group_mask(sg)); 5620 } 5621 } 5622 5623 /* 5624 * Return the canonical balance cpu for this group, this is the first cpu 5625 * of this group that's also in the iteration mask. 5626 */ 5627 int group_balance_cpu(struct sched_group *sg) 5628 { 5629 return cpumask_first_and(sched_group_cpus(sg), sched_group_mask(sg)); 5630 } 5631 5632 static int 5633 build_overlap_sched_groups(struct sched_domain *sd, int cpu) 5634 { 5635 struct sched_group *first = NULL, *last = NULL, *groups = NULL, *sg; 5636 const struct cpumask *span = sched_domain_span(sd); 5637 struct cpumask *covered = sched_domains_tmpmask; 5638 struct sd_data *sdd = sd->private; 5639 struct sched_domain *child; 5640 int i; 5641 5642 cpumask_clear(covered); 5643 5644 for_each_cpu(i, span) { 5645 struct cpumask *sg_span; 5646 5647 if (cpumask_test_cpu(i, covered)) 5648 continue; 5649 5650 child = *per_cpu_ptr(sdd->sd, i); 5651 5652 /* See the comment near build_group_mask(). */ 5653 if (!cpumask_test_cpu(i, sched_domain_span(child))) 5654 continue; 5655 5656 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(), 5657 GFP_KERNEL, cpu_to_node(cpu)); 5658 5659 if (!sg) 5660 goto fail; 5661 5662 sg_span = sched_group_cpus(sg); 5663 if (child->child) { 5664 child = child->child; 5665 cpumask_copy(sg_span, sched_domain_span(child)); 5666 } else 5667 cpumask_set_cpu(i, sg_span); 5668 5669 cpumask_or(covered, covered, sg_span); 5670 5671 sg->sgp = *per_cpu_ptr(sdd->sgp, i); 5672 if (atomic_inc_return(&sg->sgp->ref) == 1) 5673 build_group_mask(sd, sg); 5674 5675 /* 5676 * Initialize sgp->power such that even if we mess up the 5677 * domains and no possible iteration will get us here, we won't 5678 * die on a /0 trap. 5679 */ 5680 sg->sgp->power = SCHED_POWER_SCALE * cpumask_weight(sg_span); 5681 5682 /* 5683 * Make sure the first group of this domain contains the 5684 * canonical balance cpu. Otherwise the sched_domain iteration 5685 * breaks. See update_sg_lb_stats(). 5686 */ 5687 if ((!groups && cpumask_test_cpu(cpu, sg_span)) || 5688 group_balance_cpu(sg) == cpu) 5689 groups = sg; 5690 5691 if (!first) 5692 first = sg; 5693 if (last) 5694 last->next = sg; 5695 last = sg; 5696 last->next = first; 5697 } 5698 sd->groups = groups; 5699 5700 return 0; 5701 5702 fail: 5703 free_sched_groups(first, 0); 5704 5705 return -ENOMEM; 5706 } 5707 5708 static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg) 5709 { 5710 struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu); 5711 struct sched_domain *child = sd->child; 5712 5713 if (child) 5714 cpu = cpumask_first(sched_domain_span(child)); 5715 5716 if (sg) { 5717 *sg = *per_cpu_ptr(sdd->sg, cpu); 5718 (*sg)->sgp = *per_cpu_ptr(sdd->sgp, cpu); 5719 atomic_set(&(*sg)->sgp->ref, 1); /* for claim_allocations */ 5720 } 5721 5722 return cpu; 5723 } 5724 5725 /* 5726 * build_sched_groups will build a circular linked list of the groups 5727 * covered by the given span, and will set each group's ->cpumask correctly, 5728 * and ->cpu_power to 0. 5729 * 5730 * Assumes the sched_domain tree is fully constructed 5731 */ 5732 static int 5733 build_sched_groups(struct sched_domain *sd, int cpu) 5734 { 5735 struct sched_group *first = NULL, *last = NULL; 5736 struct sd_data *sdd = sd->private; 5737 const struct cpumask *span = sched_domain_span(sd); 5738 struct cpumask *covered; 5739 int i; 5740 5741 get_group(cpu, sdd, &sd->groups); 5742 atomic_inc(&sd->groups->ref); 5743 5744 if (cpu != cpumask_first(sched_domain_span(sd))) 5745 return 0; 5746 5747 lockdep_assert_held(&sched_domains_mutex); 5748 covered = sched_domains_tmpmask; 5749 5750 cpumask_clear(covered); 5751 5752 for_each_cpu(i, span) { 5753 struct sched_group *sg; 5754 int group = get_group(i, sdd, &sg); 5755 int j; 5756 5757 if (cpumask_test_cpu(i, covered)) 5758 continue; 5759 5760 cpumask_clear(sched_group_cpus(sg)); 5761 sg->sgp->power = 0; 5762 cpumask_setall(sched_group_mask(sg)); 5763 5764 for_each_cpu(j, span) { 5765 if (get_group(j, sdd, NULL) != group) 5766 continue; 5767 5768 cpumask_set_cpu(j, covered); 5769 cpumask_set_cpu(j, sched_group_cpus(sg)); 5770 } 5771 5772 if (!first) 5773 first = sg; 5774 if (last) 5775 last->next = sg; 5776 last = sg; 5777 } 5778 last->next = first; 5779 5780 return 0; 5781 } 5782 5783 /* 5784 * Initialize sched groups cpu_power. 5785 * 5786 * cpu_power indicates the capacity of sched group, which is used while 5787 * distributing the load between different sched groups in a sched domain. 5788 * Typically cpu_power for all the groups in a sched domain will be same unless 5789 * there are asymmetries in the topology. If there are asymmetries, group 5790 * having more cpu_power will pickup more load compared to the group having 5791 * less cpu_power. 5792 */ 5793 static void init_sched_groups_power(int cpu, struct sched_domain *sd) 5794 { 5795 struct sched_group *sg = sd->groups; 5796 5797 WARN_ON(!sd || !sg); 5798 5799 do { 5800 sg->group_weight = cpumask_weight(sched_group_cpus(sg)); 5801 sg = sg->next; 5802 } while (sg != sd->groups); 5803 5804 if (cpu != group_balance_cpu(sg)) 5805 return; 5806 5807 update_group_power(sd, cpu); 5808 atomic_set(&sg->sgp->nr_busy_cpus, sg->group_weight); 5809 } 5810 5811 int __weak arch_sd_sibling_asym_packing(void) 5812 { 5813 return 0*SD_ASYM_PACKING; 5814 } 5815 5816 /* 5817 * Initializers for schedule domains 5818 * Non-inlined to reduce accumulated stack pressure in build_sched_domains() 5819 */ 5820 5821 #ifdef CONFIG_SCHED_DEBUG 5822 # define SD_INIT_NAME(sd, type) sd->name = #type 5823 #else 5824 # define SD_INIT_NAME(sd, type) do { } while (0) 5825 #endif 5826 5827 #define SD_INIT_FUNC(type) \ 5828 static noinline struct sched_domain * \ 5829 sd_init_##type(struct sched_domain_topology_level *tl, int cpu) \ 5830 { \ 5831 struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu); \ 5832 *sd = SD_##type##_INIT; \ 5833 SD_INIT_NAME(sd, type); \ 5834 sd->private = &tl->data; \ 5835 return sd; \ 5836 } 5837 5838 SD_INIT_FUNC(CPU) 5839 #ifdef CONFIG_SCHED_SMT 5840 SD_INIT_FUNC(SIBLING) 5841 #endif 5842 #ifdef CONFIG_SCHED_MC 5843 SD_INIT_FUNC(MC) 5844 #endif 5845 #ifdef CONFIG_SCHED_BOOK 5846 SD_INIT_FUNC(BOOK) 5847 #endif 5848 5849 static int default_relax_domain_level = -1; 5850 int sched_domain_level_max; 5851 5852 static int __init setup_relax_domain_level(char *str) 5853 { 5854 if (kstrtoint(str, 0, &default_relax_domain_level)) 5855 pr_warn("Unable to set relax_domain_level\n"); 5856 5857 return 1; 5858 } 5859 __setup("relax_domain_level=", setup_relax_domain_level); 5860 5861 static void set_domain_attribute(struct sched_domain *sd, 5862 struct sched_domain_attr *attr) 5863 { 5864 int request; 5865 5866 if (!attr || attr->relax_domain_level < 0) { 5867 if (default_relax_domain_level < 0) 5868 return; 5869 else 5870 request = default_relax_domain_level; 5871 } else 5872 request = attr->relax_domain_level; 5873 if (request < sd->level) { 5874 /* turn off idle balance on this domain */ 5875 sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE); 5876 } else { 5877 /* turn on idle balance on this domain */ 5878 sd->flags |= (SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE); 5879 } 5880 } 5881 5882 static void __sdt_free(const struct cpumask *cpu_map); 5883 static int __sdt_alloc(const struct cpumask *cpu_map); 5884 5885 static void __free_domain_allocs(struct s_data *d, enum s_alloc what, 5886 const struct cpumask *cpu_map) 5887 { 5888 switch (what) { 5889 case sa_rootdomain: 5890 if (!atomic_read(&d->rd->refcount)) 5891 free_rootdomain(&d->rd->rcu); /* fall through */ 5892 case sa_sd: 5893 free_percpu(d->sd); /* fall through */ 5894 case sa_sd_storage: 5895 __sdt_free(cpu_map); /* fall through */ 5896 case sa_none: 5897 break; 5898 } 5899 } 5900 5901 static enum s_alloc __visit_domain_allocation_hell(struct s_data *d, 5902 const struct cpumask *cpu_map) 5903 { 5904 memset(d, 0, sizeof(*d)); 5905 5906 if (__sdt_alloc(cpu_map)) 5907 return sa_sd_storage; 5908 d->sd = alloc_percpu(struct sched_domain *); 5909 if (!d->sd) 5910 return sa_sd_storage; 5911 d->rd = alloc_rootdomain(); 5912 if (!d->rd) 5913 return sa_sd; 5914 return sa_rootdomain; 5915 } 5916 5917 /* 5918 * NULL the sd_data elements we've used to build the sched_domain and 5919 * sched_group structure so that the subsequent __free_domain_allocs() 5920 * will not free the data we're using. 5921 */ 5922 static void claim_allocations(int cpu, struct sched_domain *sd) 5923 { 5924 struct sd_data *sdd = sd->private; 5925 5926 WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd); 5927 *per_cpu_ptr(sdd->sd, cpu) = NULL; 5928 5929 if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref)) 5930 *per_cpu_ptr(sdd->sg, cpu) = NULL; 5931 5932 if (atomic_read(&(*per_cpu_ptr(sdd->sgp, cpu))->ref)) 5933 *per_cpu_ptr(sdd->sgp, cpu) = NULL; 5934 } 5935 5936 #ifdef CONFIG_SCHED_SMT 5937 static const struct cpumask *cpu_smt_mask(int cpu) 5938 { 5939 return topology_thread_cpumask(cpu); 5940 } 5941 #endif 5942 5943 /* 5944 * Topology list, bottom-up. 5945 */ 5946 static struct sched_domain_topology_level default_topology[] = { 5947 #ifdef CONFIG_SCHED_SMT 5948 { sd_init_SIBLING, cpu_smt_mask, }, 5949 #endif 5950 #ifdef CONFIG_SCHED_MC 5951 { sd_init_MC, cpu_coregroup_mask, }, 5952 #endif 5953 #ifdef CONFIG_SCHED_BOOK 5954 { sd_init_BOOK, cpu_book_mask, }, 5955 #endif 5956 { sd_init_CPU, cpu_cpu_mask, }, 5957 { NULL, }, 5958 }; 5959 5960 static struct sched_domain_topology_level *sched_domain_topology = default_topology; 5961 5962 #ifdef CONFIG_NUMA 5963 5964 static int sched_domains_numa_levels; 5965 static int *sched_domains_numa_distance; 5966 static struct cpumask ***sched_domains_numa_masks; 5967 static int sched_domains_curr_level; 5968 5969 static inline int sd_local_flags(int level) 5970 { 5971 if (sched_domains_numa_distance[level] > RECLAIM_DISTANCE) 5972 return 0; 5973 5974 return SD_BALANCE_EXEC | SD_BALANCE_FORK | SD_WAKE_AFFINE; 5975 } 5976 5977 static struct sched_domain * 5978 sd_numa_init(struct sched_domain_topology_level *tl, int cpu) 5979 { 5980 struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu); 5981 int level = tl->numa_level; 5982 int sd_weight = cpumask_weight( 5983 sched_domains_numa_masks[level][cpu_to_node(cpu)]); 5984 5985 *sd = (struct sched_domain){ 5986 .min_interval = sd_weight, 5987 .max_interval = 2*sd_weight, 5988 .busy_factor = 32, 5989 .imbalance_pct = 125, 5990 .cache_nice_tries = 2, 5991 .busy_idx = 3, 5992 .idle_idx = 2, 5993 .newidle_idx = 0, 5994 .wake_idx = 0, 5995 .forkexec_idx = 0, 5996 5997 .flags = 1*SD_LOAD_BALANCE 5998 | 1*SD_BALANCE_NEWIDLE 5999 | 0*SD_BALANCE_EXEC 6000 | 0*SD_BALANCE_FORK 6001 | 0*SD_BALANCE_WAKE 6002 | 0*SD_WAKE_AFFINE 6003 | 0*SD_SHARE_CPUPOWER 6004 | 0*SD_SHARE_PKG_RESOURCES 6005 | 1*SD_SERIALIZE 6006 | 0*SD_PREFER_SIBLING 6007 | sd_local_flags(level) 6008 , 6009 .last_balance = jiffies, 6010 .balance_interval = sd_weight, 6011 }; 6012 SD_INIT_NAME(sd, NUMA); 6013 sd->private = &tl->data; 6014 6015 /* 6016 * Ugly hack to pass state to sd_numa_mask()... 6017 */ 6018 sched_domains_curr_level = tl->numa_level; 6019 6020 return sd; 6021 } 6022 6023 static const struct cpumask *sd_numa_mask(int cpu) 6024 { 6025 return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)]; 6026 } 6027 6028 static void sched_numa_warn(const char *str) 6029 { 6030 static int done = false; 6031 int i,j; 6032 6033 if (done) 6034 return; 6035 6036 done = true; 6037 6038 printk(KERN_WARNING "ERROR: %s\n\n", str); 6039 6040 for (i = 0; i < nr_node_ids; i++) { 6041 printk(KERN_WARNING " "); 6042 for (j = 0; j < nr_node_ids; j++) 6043 printk(KERN_CONT "%02d ", node_distance(i,j)); 6044 printk(KERN_CONT "\n"); 6045 } 6046 printk(KERN_WARNING "\n"); 6047 } 6048 6049 static bool find_numa_distance(int distance) 6050 { 6051 int i; 6052 6053 if (distance == node_distance(0, 0)) 6054 return true; 6055 6056 for (i = 0; i < sched_domains_numa_levels; i++) { 6057 if (sched_domains_numa_distance[i] == distance) 6058 return true; 6059 } 6060 6061 return false; 6062 } 6063 6064 static void sched_init_numa(void) 6065 { 6066 int next_distance, curr_distance = node_distance(0, 0); 6067 struct sched_domain_topology_level *tl; 6068 int level = 0; 6069 int i, j, k; 6070 6071 sched_domains_numa_distance = kzalloc(sizeof(int) * nr_node_ids, GFP_KERNEL); 6072 if (!sched_domains_numa_distance) 6073 return; 6074 6075 /* 6076 * O(nr_nodes^2) deduplicating selection sort -- in order to find the 6077 * unique distances in the node_distance() table. 6078 * 6079 * Assumes node_distance(0,j) includes all distances in 6080 * node_distance(i,j) in order to avoid cubic time. 6081 */ 6082 next_distance = curr_distance; 6083 for (i = 0; i < nr_node_ids; i++) { 6084 for (j = 0; j < nr_node_ids; j++) { 6085 for (k = 0; k < nr_node_ids; k++) { 6086 int distance = node_distance(i, k); 6087 6088 if (distance > curr_distance && 6089 (distance < next_distance || 6090 next_distance == curr_distance)) 6091 next_distance = distance; 6092 6093 /* 6094 * While not a strong assumption it would be nice to know 6095 * about cases where if node A is connected to B, B is not 6096 * equally connected to A. 6097 */ 6098 if (sched_debug() && node_distance(k, i) != distance) 6099 sched_numa_warn("Node-distance not symmetric"); 6100 6101 if (sched_debug() && i && !find_numa_distance(distance)) 6102 sched_numa_warn("Node-0 not representative"); 6103 } 6104 if (next_distance != curr_distance) { 6105 sched_domains_numa_distance[level++] = next_distance; 6106 sched_domains_numa_levels = level; 6107 curr_distance = next_distance; 6108 } else break; 6109 } 6110 6111 /* 6112 * In case of sched_debug() we verify the above assumption. 6113 */ 6114 if (!sched_debug()) 6115 break; 6116 } 6117 /* 6118 * 'level' contains the number of unique distances, excluding the 6119 * identity distance node_distance(i,i). 6120 * 6121 * The sched_domains_nume_distance[] array includes the actual distance 6122 * numbers. 6123 */ 6124 6125 sched_domains_numa_masks = kzalloc(sizeof(void *) * level, GFP_KERNEL); 6126 if (!sched_domains_numa_masks) 6127 return; 6128 6129 /* 6130 * Now for each level, construct a mask per node which contains all 6131 * cpus of nodes that are that many hops away from us. 6132 */ 6133 for (i = 0; i < level; i++) { 6134 sched_domains_numa_masks[i] = 6135 kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL); 6136 if (!sched_domains_numa_masks[i]) 6137 return; 6138 6139 for (j = 0; j < nr_node_ids; j++) { 6140 struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL); 6141 if (!mask) 6142 return; 6143 6144 sched_domains_numa_masks[i][j] = mask; 6145 6146 for (k = 0; k < nr_node_ids; k++) { 6147 if (node_distance(j, k) > sched_domains_numa_distance[i]) 6148 continue; 6149 6150 cpumask_or(mask, mask, cpumask_of_node(k)); 6151 } 6152 } 6153 } 6154 6155 tl = kzalloc((ARRAY_SIZE(default_topology) + level) * 6156 sizeof(struct sched_domain_topology_level), GFP_KERNEL); 6157 if (!tl) 6158 return; 6159 6160 /* 6161 * Copy the default topology bits.. 6162 */ 6163 for (i = 0; default_topology[i].init; i++) 6164 tl[i] = default_topology[i]; 6165 6166 /* 6167 * .. and append 'j' levels of NUMA goodness. 6168 */ 6169 for (j = 0; j < level; i++, j++) { 6170 tl[i] = (struct sched_domain_topology_level){ 6171 .init = sd_numa_init, 6172 .mask = sd_numa_mask, 6173 .flags = SDTL_OVERLAP, 6174 .numa_level = j, 6175 }; 6176 } 6177 6178 sched_domain_topology = tl; 6179 } 6180 #else 6181 static inline void sched_init_numa(void) 6182 { 6183 } 6184 #endif /* CONFIG_NUMA */ 6185 6186 static int __sdt_alloc(const struct cpumask *cpu_map) 6187 { 6188 struct sched_domain_topology_level *tl; 6189 int j; 6190 6191 for (tl = sched_domain_topology; tl->init; tl++) { 6192 struct sd_data *sdd = &tl->data; 6193 6194 sdd->sd = alloc_percpu(struct sched_domain *); 6195 if (!sdd->sd) 6196 return -ENOMEM; 6197 6198 sdd->sg = alloc_percpu(struct sched_group *); 6199 if (!sdd->sg) 6200 return -ENOMEM; 6201 6202 sdd->sgp = alloc_percpu(struct sched_group_power *); 6203 if (!sdd->sgp) 6204 return -ENOMEM; 6205 6206 for_each_cpu(j, cpu_map) { 6207 struct sched_domain *sd; 6208 struct sched_group *sg; 6209 struct sched_group_power *sgp; 6210 6211 sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(), 6212 GFP_KERNEL, cpu_to_node(j)); 6213 if (!sd) 6214 return -ENOMEM; 6215 6216 *per_cpu_ptr(sdd->sd, j) = sd; 6217 6218 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(), 6219 GFP_KERNEL, cpu_to_node(j)); 6220 if (!sg) 6221 return -ENOMEM; 6222 6223 sg->next = sg; 6224 6225 *per_cpu_ptr(sdd->sg, j) = sg; 6226 6227 sgp = kzalloc_node(sizeof(struct sched_group_power) + cpumask_size(), 6228 GFP_KERNEL, cpu_to_node(j)); 6229 if (!sgp) 6230 return -ENOMEM; 6231 6232 *per_cpu_ptr(sdd->sgp, j) = sgp; 6233 } 6234 } 6235 6236 return 0; 6237 } 6238 6239 static void __sdt_free(const struct cpumask *cpu_map) 6240 { 6241 struct sched_domain_topology_level *tl; 6242 int j; 6243 6244 for (tl = sched_domain_topology; tl->init; tl++) { 6245 struct sd_data *sdd = &tl->data; 6246 6247 for_each_cpu(j, cpu_map) { 6248 struct sched_domain *sd; 6249 6250 if (sdd->sd) { 6251 sd = *per_cpu_ptr(sdd->sd, j); 6252 if (sd && (sd->flags & SD_OVERLAP)) 6253 free_sched_groups(sd->groups, 0); 6254 kfree(*per_cpu_ptr(sdd->sd, j)); 6255 } 6256 6257 if (sdd->sg) 6258 kfree(*per_cpu_ptr(sdd->sg, j)); 6259 if (sdd->sgp) 6260 kfree(*per_cpu_ptr(sdd->sgp, j)); 6261 } 6262 free_percpu(sdd->sd); 6263 sdd->sd = NULL; 6264 free_percpu(sdd->sg); 6265 sdd->sg = NULL; 6266 free_percpu(sdd->sgp); 6267 sdd->sgp = NULL; 6268 } 6269 } 6270 6271 struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl, 6272 struct s_data *d, const struct cpumask *cpu_map, 6273 struct sched_domain_attr *attr, struct sched_domain *child, 6274 int cpu) 6275 { 6276 struct sched_domain *sd = tl->init(tl, cpu); 6277 if (!sd) 6278 return child; 6279 6280 cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu)); 6281 if (child) { 6282 sd->level = child->level + 1; 6283 sched_domain_level_max = max(sched_domain_level_max, sd->level); 6284 child->parent = sd; 6285 } 6286 sd->child = child; 6287 set_domain_attribute(sd, attr); 6288 6289 return sd; 6290 } 6291 6292 /* 6293 * Build sched domains for a given set of cpus and attach the sched domains 6294 * to the individual cpus 6295 */ 6296 static int build_sched_domains(const struct cpumask *cpu_map, 6297 struct sched_domain_attr *attr) 6298 { 6299 enum s_alloc alloc_state = sa_none; 6300 struct sched_domain *sd; 6301 struct s_data d; 6302 int i, ret = -ENOMEM; 6303 6304 alloc_state = __visit_domain_allocation_hell(&d, cpu_map); 6305 if (alloc_state != sa_rootdomain) 6306 goto error; 6307 6308 /* Set up domains for cpus specified by the cpu_map. */ 6309 for_each_cpu(i, cpu_map) { 6310 struct sched_domain_topology_level *tl; 6311 6312 sd = NULL; 6313 for (tl = sched_domain_topology; tl->init; tl++) { 6314 sd = build_sched_domain(tl, &d, cpu_map, attr, sd, i); 6315 if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP)) 6316 sd->flags |= SD_OVERLAP; 6317 if (cpumask_equal(cpu_map, sched_domain_span(sd))) 6318 break; 6319 } 6320 6321 while (sd->child) 6322 sd = sd->child; 6323 6324 *per_cpu_ptr(d.sd, i) = sd; 6325 } 6326 6327 /* Build the groups for the domains */ 6328 for_each_cpu(i, cpu_map) { 6329 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) { 6330 sd->span_weight = cpumask_weight(sched_domain_span(sd)); 6331 if (sd->flags & SD_OVERLAP) { 6332 if (build_overlap_sched_groups(sd, i)) 6333 goto error; 6334 } else { 6335 if (build_sched_groups(sd, i)) 6336 goto error; 6337 } 6338 } 6339 } 6340 6341 /* Calculate CPU power for physical packages and nodes */ 6342 for (i = nr_cpumask_bits-1; i >= 0; i--) { 6343 if (!cpumask_test_cpu(i, cpu_map)) 6344 continue; 6345 6346 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) { 6347 claim_allocations(i, sd); 6348 init_sched_groups_power(i, sd); 6349 } 6350 } 6351 6352 /* Attach the domains */ 6353 rcu_read_lock(); 6354 for_each_cpu(i, cpu_map) { 6355 sd = *per_cpu_ptr(d.sd, i); 6356 cpu_attach_domain(sd, d.rd, i); 6357 } 6358 rcu_read_unlock(); 6359 6360 ret = 0; 6361 error: 6362 __free_domain_allocs(&d, alloc_state, cpu_map); 6363 return ret; 6364 } 6365 6366 static cpumask_var_t *doms_cur; /* current sched domains */ 6367 static int ndoms_cur; /* number of sched domains in 'doms_cur' */ 6368 static struct sched_domain_attr *dattr_cur; 6369 /* attribues of custom domains in 'doms_cur' */ 6370 6371 /* 6372 * Special case: If a kmalloc of a doms_cur partition (array of 6373 * cpumask) fails, then fallback to a single sched domain, 6374 * as determined by the single cpumask fallback_doms. 6375 */ 6376 static cpumask_var_t fallback_doms; 6377 6378 /* 6379 * arch_update_cpu_topology lets virtualized architectures update the 6380 * cpu core maps. It is supposed to return 1 if the topology changed 6381 * or 0 if it stayed the same. 6382 */ 6383 int __attribute__((weak)) arch_update_cpu_topology(void) 6384 { 6385 return 0; 6386 } 6387 6388 cpumask_var_t *alloc_sched_domains(unsigned int ndoms) 6389 { 6390 int i; 6391 cpumask_var_t *doms; 6392 6393 doms = kmalloc(sizeof(*doms) * ndoms, GFP_KERNEL); 6394 if (!doms) 6395 return NULL; 6396 for (i = 0; i < ndoms; i++) { 6397 if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) { 6398 free_sched_domains(doms, i); 6399 return NULL; 6400 } 6401 } 6402 return doms; 6403 } 6404 6405 void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms) 6406 { 6407 unsigned int i; 6408 for (i = 0; i < ndoms; i++) 6409 free_cpumask_var(doms[i]); 6410 kfree(doms); 6411 } 6412 6413 /* 6414 * Set up scheduler domains and groups. Callers must hold the hotplug lock. 6415 * For now this just excludes isolated cpus, but could be used to 6416 * exclude other special cases in the future. 6417 */ 6418 static int init_sched_domains(const struct cpumask *cpu_map) 6419 { 6420 int err; 6421 6422 arch_update_cpu_topology(); 6423 ndoms_cur = 1; 6424 doms_cur = alloc_sched_domains(ndoms_cur); 6425 if (!doms_cur) 6426 doms_cur = &fallback_doms; 6427 cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map); 6428 err = build_sched_domains(doms_cur[0], NULL); 6429 register_sched_domain_sysctl(); 6430 6431 return err; 6432 } 6433 6434 /* 6435 * Detach sched domains from a group of cpus specified in cpu_map 6436 * These cpus will now be attached to the NULL domain 6437 */ 6438 static void detach_destroy_domains(const struct cpumask *cpu_map) 6439 { 6440 int i; 6441 6442 rcu_read_lock(); 6443 for_each_cpu(i, cpu_map) 6444 cpu_attach_domain(NULL, &def_root_domain, i); 6445 rcu_read_unlock(); 6446 } 6447 6448 /* handle null as "default" */ 6449 static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur, 6450 struct sched_domain_attr *new, int idx_new) 6451 { 6452 struct sched_domain_attr tmp; 6453 6454 /* fast path */ 6455 if (!new && !cur) 6456 return 1; 6457 6458 tmp = SD_ATTR_INIT; 6459 return !memcmp(cur ? (cur + idx_cur) : &tmp, 6460 new ? (new + idx_new) : &tmp, 6461 sizeof(struct sched_domain_attr)); 6462 } 6463 6464 /* 6465 * Partition sched domains as specified by the 'ndoms_new' 6466 * cpumasks in the array doms_new[] of cpumasks. This compares 6467 * doms_new[] to the current sched domain partitioning, doms_cur[]. 6468 * It destroys each deleted domain and builds each new domain. 6469 * 6470 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'. 6471 * The masks don't intersect (don't overlap.) We should setup one 6472 * sched domain for each mask. CPUs not in any of the cpumasks will 6473 * not be load balanced. If the same cpumask appears both in the 6474 * current 'doms_cur' domains and in the new 'doms_new', we can leave 6475 * it as it is. 6476 * 6477 * The passed in 'doms_new' should be allocated using 6478 * alloc_sched_domains. This routine takes ownership of it and will 6479 * free_sched_domains it when done with it. If the caller failed the 6480 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1, 6481 * and partition_sched_domains() will fallback to the single partition 6482 * 'fallback_doms', it also forces the domains to be rebuilt. 6483 * 6484 * If doms_new == NULL it will be replaced with cpu_online_mask. 6485 * ndoms_new == 0 is a special case for destroying existing domains, 6486 * and it will not create the default domain. 6487 * 6488 * Call with hotplug lock held 6489 */ 6490 void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[], 6491 struct sched_domain_attr *dattr_new) 6492 { 6493 int i, j, n; 6494 int new_topology; 6495 6496 mutex_lock(&sched_domains_mutex); 6497 6498 /* always unregister in case we don't destroy any domains */ 6499 unregister_sched_domain_sysctl(); 6500 6501 /* Let architecture update cpu core mappings. */ 6502 new_topology = arch_update_cpu_topology(); 6503 6504 n = doms_new ? ndoms_new : 0; 6505 6506 /* Destroy deleted domains */ 6507 for (i = 0; i < ndoms_cur; i++) { 6508 for (j = 0; j < n && !new_topology; j++) { 6509 if (cpumask_equal(doms_cur[i], doms_new[j]) 6510 && dattrs_equal(dattr_cur, i, dattr_new, j)) 6511 goto match1; 6512 } 6513 /* no match - a current sched domain not in new doms_new[] */ 6514 detach_destroy_domains(doms_cur[i]); 6515 match1: 6516 ; 6517 } 6518 6519 if (doms_new == NULL) { 6520 ndoms_cur = 0; 6521 doms_new = &fallback_doms; 6522 cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map); 6523 WARN_ON_ONCE(dattr_new); 6524 } 6525 6526 /* Build new domains */ 6527 for (i = 0; i < ndoms_new; i++) { 6528 for (j = 0; j < ndoms_cur && !new_topology; j++) { 6529 if (cpumask_equal(doms_new[i], doms_cur[j]) 6530 && dattrs_equal(dattr_new, i, dattr_cur, j)) 6531 goto match2; 6532 } 6533 /* no match - add a new doms_new */ 6534 build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL); 6535 match2: 6536 ; 6537 } 6538 6539 /* Remember the new sched domains */ 6540 if (doms_cur != &fallback_doms) 6541 free_sched_domains(doms_cur, ndoms_cur); 6542 kfree(dattr_cur); /* kfree(NULL) is safe */ 6543 doms_cur = doms_new; 6544 dattr_cur = dattr_new; 6545 ndoms_cur = ndoms_new; 6546 6547 register_sched_domain_sysctl(); 6548 6549 mutex_unlock(&sched_domains_mutex); 6550 } 6551 6552 static int num_cpus_frozen; /* used to mark begin/end of suspend/resume */ 6553 6554 /* 6555 * Update cpusets according to cpu_active mask. If cpusets are 6556 * disabled, cpuset_update_active_cpus() becomes a simple wrapper 6557 * around partition_sched_domains(). 6558 * 6559 * If we come here as part of a suspend/resume, don't touch cpusets because we 6560 * want to restore it back to its original state upon resume anyway. 6561 */ 6562 static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action, 6563 void *hcpu) 6564 { 6565 switch (action) { 6566 case CPU_ONLINE_FROZEN: 6567 case CPU_DOWN_FAILED_FROZEN: 6568 6569 /* 6570 * num_cpus_frozen tracks how many CPUs are involved in suspend 6571 * resume sequence. As long as this is not the last online 6572 * operation in the resume sequence, just build a single sched 6573 * domain, ignoring cpusets. 6574 */ 6575 num_cpus_frozen--; 6576 if (likely(num_cpus_frozen)) { 6577 partition_sched_domains(1, NULL, NULL); 6578 break; 6579 } 6580 6581 /* 6582 * This is the last CPU online operation. So fall through and 6583 * restore the original sched domains by considering the 6584 * cpuset configurations. 6585 */ 6586 6587 case CPU_ONLINE: 6588 case CPU_DOWN_FAILED: 6589 cpuset_update_active_cpus(true); 6590 break; 6591 default: 6592 return NOTIFY_DONE; 6593 } 6594 return NOTIFY_OK; 6595 } 6596 6597 static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action, 6598 void *hcpu) 6599 { 6600 switch (action) { 6601 case CPU_DOWN_PREPARE: 6602 cpuset_update_active_cpus(false); 6603 break; 6604 case CPU_DOWN_PREPARE_FROZEN: 6605 num_cpus_frozen++; 6606 partition_sched_domains(1, NULL, NULL); 6607 break; 6608 default: 6609 return NOTIFY_DONE; 6610 } 6611 return NOTIFY_OK; 6612 } 6613 6614 void __init sched_init_smp(void) 6615 { 6616 cpumask_var_t non_isolated_cpus; 6617 6618 alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL); 6619 alloc_cpumask_var(&fallback_doms, GFP_KERNEL); 6620 6621 sched_init_numa(); 6622 6623 get_online_cpus(); 6624 mutex_lock(&sched_domains_mutex); 6625 init_sched_domains(cpu_active_mask); 6626 cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map); 6627 if (cpumask_empty(non_isolated_cpus)) 6628 cpumask_set_cpu(smp_processor_id(), non_isolated_cpus); 6629 mutex_unlock(&sched_domains_mutex); 6630 put_online_cpus(); 6631 6632 hotcpu_notifier(cpuset_cpu_active, CPU_PRI_CPUSET_ACTIVE); 6633 hotcpu_notifier(cpuset_cpu_inactive, CPU_PRI_CPUSET_INACTIVE); 6634 6635 /* RT runtime code needs to handle some hotplug events */ 6636 hotcpu_notifier(update_runtime, 0); 6637 6638 init_hrtick(); 6639 6640 /* Move init over to a non-isolated CPU */ 6641 if (set_cpus_allowed_ptr(current, non_isolated_cpus) < 0) 6642 BUG(); 6643 sched_init_granularity(); 6644 free_cpumask_var(non_isolated_cpus); 6645 6646 init_sched_rt_class(); 6647 } 6648 #else 6649 void __init sched_init_smp(void) 6650 { 6651 sched_init_granularity(); 6652 } 6653 #endif /* CONFIG_SMP */ 6654 6655 const_debug unsigned int sysctl_timer_migration = 1; 6656 6657 int in_sched_functions(unsigned long addr) 6658 { 6659 return in_lock_functions(addr) || 6660 (addr >= (unsigned long)__sched_text_start 6661 && addr < (unsigned long)__sched_text_end); 6662 } 6663 6664 #ifdef CONFIG_CGROUP_SCHED 6665 struct task_group root_task_group; 6666 LIST_HEAD(task_groups); 6667 #endif 6668 6669 DECLARE_PER_CPU(cpumask_var_t, load_balance_tmpmask); 6670 6671 void __init sched_init(void) 6672 { 6673 int i, j; 6674 unsigned long alloc_size = 0, ptr; 6675 6676 #ifdef CONFIG_FAIR_GROUP_SCHED 6677 alloc_size += 2 * nr_cpu_ids * sizeof(void **); 6678 #endif 6679 #ifdef CONFIG_RT_GROUP_SCHED 6680 alloc_size += 2 * nr_cpu_ids * sizeof(void **); 6681 #endif 6682 #ifdef CONFIG_CPUMASK_OFFSTACK 6683 alloc_size += num_possible_cpus() * cpumask_size(); 6684 #endif 6685 if (alloc_size) { 6686 ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT); 6687 6688 #ifdef CONFIG_FAIR_GROUP_SCHED 6689 root_task_group.se = (struct sched_entity **)ptr; 6690 ptr += nr_cpu_ids * sizeof(void **); 6691 6692 root_task_group.cfs_rq = (struct cfs_rq **)ptr; 6693 ptr += nr_cpu_ids * sizeof(void **); 6694 6695 #endif /* CONFIG_FAIR_GROUP_SCHED */ 6696 #ifdef CONFIG_RT_GROUP_SCHED 6697 root_task_group.rt_se = (struct sched_rt_entity **)ptr; 6698 ptr += nr_cpu_ids * sizeof(void **); 6699 6700 root_task_group.rt_rq = (struct rt_rq **)ptr; 6701 ptr += nr_cpu_ids * sizeof(void **); 6702 6703 #endif /* CONFIG_RT_GROUP_SCHED */ 6704 #ifdef CONFIG_CPUMASK_OFFSTACK 6705 for_each_possible_cpu(i) { 6706 per_cpu(load_balance_tmpmask, i) = (void *)ptr; 6707 ptr += cpumask_size(); 6708 } 6709 #endif /* CONFIG_CPUMASK_OFFSTACK */ 6710 } 6711 6712 #ifdef CONFIG_SMP 6713 init_defrootdomain(); 6714 #endif 6715 6716 init_rt_bandwidth(&def_rt_bandwidth, 6717 global_rt_period(), global_rt_runtime()); 6718 6719 #ifdef CONFIG_RT_GROUP_SCHED 6720 init_rt_bandwidth(&root_task_group.rt_bandwidth, 6721 global_rt_period(), global_rt_runtime()); 6722 #endif /* CONFIG_RT_GROUP_SCHED */ 6723 6724 #ifdef CONFIG_CGROUP_SCHED 6725 list_add(&root_task_group.list, &task_groups); 6726 INIT_LIST_HEAD(&root_task_group.children); 6727 INIT_LIST_HEAD(&root_task_group.siblings); 6728 autogroup_init(&init_task); 6729 6730 #endif /* CONFIG_CGROUP_SCHED */ 6731 6732 #ifdef CONFIG_CGROUP_CPUACCT 6733 root_cpuacct.cpustat = &kernel_cpustat; 6734 root_cpuacct.cpuusage = alloc_percpu(u64); 6735 /* Too early, not expected to fail */ 6736 BUG_ON(!root_cpuacct.cpuusage); 6737 #endif 6738 for_each_possible_cpu(i) { 6739 struct rq *rq; 6740 6741 rq = cpu_rq(i); 6742 raw_spin_lock_init(&rq->lock); 6743 rq->nr_running = 0; 6744 rq->calc_load_active = 0; 6745 rq->calc_load_update = jiffies + LOAD_FREQ; 6746 init_cfs_rq(&rq->cfs); 6747 init_rt_rq(&rq->rt, rq); 6748 #ifdef CONFIG_FAIR_GROUP_SCHED 6749 root_task_group.shares = ROOT_TASK_GROUP_LOAD; 6750 INIT_LIST_HEAD(&rq->leaf_cfs_rq_list); 6751 /* 6752 * How much cpu bandwidth does root_task_group get? 6753 * 6754 * In case of task-groups formed thr' the cgroup filesystem, it 6755 * gets 100% of the cpu resources in the system. This overall 6756 * system cpu resource is divided among the tasks of 6757 * root_task_group and its child task-groups in a fair manner, 6758 * based on each entity's (task or task-group's) weight 6759 * (se->load.weight). 6760 * 6761 * In other words, if root_task_group has 10 tasks of weight 6762 * 1024) and two child groups A0 and A1 (of weight 1024 each), 6763 * then A0's share of the cpu resource is: 6764 * 6765 * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33% 6766 * 6767 * We achieve this by letting root_task_group's tasks sit 6768 * directly in rq->cfs (i.e root_task_group->se[] = NULL). 6769 */ 6770 init_cfs_bandwidth(&root_task_group.cfs_bandwidth); 6771 init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL); 6772 #endif /* CONFIG_FAIR_GROUP_SCHED */ 6773 6774 rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime; 6775 #ifdef CONFIG_RT_GROUP_SCHED 6776 INIT_LIST_HEAD(&rq->leaf_rt_rq_list); 6777 init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL); 6778 #endif 6779 6780 for (j = 0; j < CPU_LOAD_IDX_MAX; j++) 6781 rq->cpu_load[j] = 0; 6782 6783 rq->last_load_update_tick = jiffies; 6784 6785 #ifdef CONFIG_SMP 6786 rq->sd = NULL; 6787 rq->rd = NULL; 6788 rq->cpu_power = SCHED_POWER_SCALE; 6789 rq->post_schedule = 0; 6790 rq->active_balance = 0; 6791 rq->next_balance = jiffies; 6792 rq->push_cpu = 0; 6793 rq->cpu = i; 6794 rq->online = 0; 6795 rq->idle_stamp = 0; 6796 rq->avg_idle = 2*sysctl_sched_migration_cost; 6797 6798 INIT_LIST_HEAD(&rq->cfs_tasks); 6799 6800 rq_attach_root(rq, &def_root_domain); 6801 #ifdef CONFIG_NO_HZ 6802 rq->nohz_flags = 0; 6803 #endif 6804 #endif 6805 init_rq_hrtick(rq); 6806 atomic_set(&rq->nr_iowait, 0); 6807 } 6808 6809 set_load_weight(&init_task); 6810 6811 #ifdef CONFIG_PREEMPT_NOTIFIERS 6812 INIT_HLIST_HEAD(&init_task.preempt_notifiers); 6813 #endif 6814 6815 #ifdef CONFIG_RT_MUTEXES 6816 plist_head_init(&init_task.pi_waiters); 6817 #endif 6818 6819 /* 6820 * The boot idle thread does lazy MMU switching as well: 6821 */ 6822 atomic_inc(&init_mm.mm_count); 6823 enter_lazy_tlb(&init_mm, current); 6824 6825 /* 6826 * Make us the idle thread. Technically, schedule() should not be 6827 * called from this thread, however somewhere below it might be, 6828 * but because we are the idle thread, we just pick up running again 6829 * when this runqueue becomes "idle". 6830 */ 6831 init_idle(current, smp_processor_id()); 6832 6833 calc_load_update = jiffies + LOAD_FREQ; 6834 6835 /* 6836 * During early bootup we pretend to be a normal task: 6837 */ 6838 current->sched_class = &fair_sched_class; 6839 6840 #ifdef CONFIG_SMP 6841 zalloc_cpumask_var(&sched_domains_tmpmask, GFP_NOWAIT); 6842 /* May be allocated at isolcpus cmdline parse time */ 6843 if (cpu_isolated_map == NULL) 6844 zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT); 6845 idle_thread_set_boot_cpu(); 6846 #endif 6847 init_sched_fair_class(); 6848 6849 scheduler_running = 1; 6850 } 6851 6852 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP 6853 static inline int preempt_count_equals(int preempt_offset) 6854 { 6855 int nested = (preempt_count() & ~PREEMPT_ACTIVE) + rcu_preempt_depth(); 6856 6857 return (nested == preempt_offset); 6858 } 6859 6860 void __might_sleep(const char *file, int line, int preempt_offset) 6861 { 6862 static unsigned long prev_jiffy; /* ratelimiting */ 6863 6864 rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */ 6865 if ((preempt_count_equals(preempt_offset) && !irqs_disabled()) || 6866 system_state != SYSTEM_RUNNING || oops_in_progress) 6867 return; 6868 if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy) 6869 return; 6870 prev_jiffy = jiffies; 6871 6872 printk(KERN_ERR 6873 "BUG: sleeping function called from invalid context at %s:%d\n", 6874 file, line); 6875 printk(KERN_ERR 6876 "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n", 6877 in_atomic(), irqs_disabled(), 6878 current->pid, current->comm); 6879 6880 debug_show_held_locks(current); 6881 if (irqs_disabled()) 6882 print_irqtrace_events(current); 6883 dump_stack(); 6884 } 6885 EXPORT_SYMBOL(__might_sleep); 6886 #endif 6887 6888 #ifdef CONFIG_MAGIC_SYSRQ 6889 static void normalize_task(struct rq *rq, struct task_struct *p) 6890 { 6891 const struct sched_class *prev_class = p->sched_class; 6892 int old_prio = p->prio; 6893 int on_rq; 6894 6895 on_rq = p->on_rq; 6896 if (on_rq) 6897 dequeue_task(rq, p, 0); 6898 __setscheduler(rq, p, SCHED_NORMAL, 0); 6899 if (on_rq) { 6900 enqueue_task(rq, p, 0); 6901 resched_task(rq->curr); 6902 } 6903 6904 check_class_changed(rq, p, prev_class, old_prio); 6905 } 6906 6907 void normalize_rt_tasks(void) 6908 { 6909 struct task_struct *g, *p; 6910 unsigned long flags; 6911 struct rq *rq; 6912 6913 read_lock_irqsave(&tasklist_lock, flags); 6914 do_each_thread(g, p) { 6915 /* 6916 * Only normalize user tasks: 6917 */ 6918 if (!p->mm) 6919 continue; 6920 6921 p->se.exec_start = 0; 6922 #ifdef CONFIG_SCHEDSTATS 6923 p->se.statistics.wait_start = 0; 6924 p->se.statistics.sleep_start = 0; 6925 p->se.statistics.block_start = 0; 6926 #endif 6927 6928 if (!rt_task(p)) { 6929 /* 6930 * Renice negative nice level userspace 6931 * tasks back to 0: 6932 */ 6933 if (TASK_NICE(p) < 0 && p->mm) 6934 set_user_nice(p, 0); 6935 continue; 6936 } 6937 6938 raw_spin_lock(&p->pi_lock); 6939 rq = __task_rq_lock(p); 6940 6941 normalize_task(rq, p); 6942 6943 __task_rq_unlock(rq); 6944 raw_spin_unlock(&p->pi_lock); 6945 } while_each_thread(g, p); 6946 6947 read_unlock_irqrestore(&tasklist_lock, flags); 6948 } 6949 6950 #endif /* CONFIG_MAGIC_SYSRQ */ 6951 6952 #if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) 6953 /* 6954 * These functions are only useful for the IA64 MCA handling, or kdb. 6955 * 6956 * They can only be called when the whole system has been 6957 * stopped - every CPU needs to be quiescent, and no scheduling 6958 * activity can take place. Using them for anything else would 6959 * be a serious bug, and as a result, they aren't even visible 6960 * under any other configuration. 6961 */ 6962 6963 /** 6964 * curr_task - return the current task for a given cpu. 6965 * @cpu: the processor in question. 6966 * 6967 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! 6968 */ 6969 struct task_struct *curr_task(int cpu) 6970 { 6971 return cpu_curr(cpu); 6972 } 6973 6974 #endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */ 6975 6976 #ifdef CONFIG_IA64 6977 /** 6978 * set_curr_task - set the current task for a given cpu. 6979 * @cpu: the processor in question. 6980 * @p: the task pointer to set. 6981 * 6982 * Description: This function must only be used when non-maskable interrupts 6983 * are serviced on a separate stack. It allows the architecture to switch the 6984 * notion of the current task on a cpu in a non-blocking manner. This function 6985 * must be called with all CPU's synchronized, and interrupts disabled, the 6986 * and caller must save the original value of the current task (see 6987 * curr_task() above) and restore that value before reenabling interrupts and 6988 * re-starting the system. 6989 * 6990 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! 6991 */ 6992 void set_curr_task(int cpu, struct task_struct *p) 6993 { 6994 cpu_curr(cpu) = p; 6995 } 6996 6997 #endif 6998 6999 #ifdef CONFIG_CGROUP_SCHED 7000 /* task_group_lock serializes the addition/removal of task groups */ 7001 static DEFINE_SPINLOCK(task_group_lock); 7002 7003 static void free_sched_group(struct task_group *tg) 7004 { 7005 free_fair_sched_group(tg); 7006 free_rt_sched_group(tg); 7007 autogroup_free(tg); 7008 kfree(tg); 7009 } 7010 7011 /* allocate runqueue etc for a new task group */ 7012 struct task_group *sched_create_group(struct task_group *parent) 7013 { 7014 struct task_group *tg; 7015 unsigned long flags; 7016 7017 tg = kzalloc(sizeof(*tg), GFP_KERNEL); 7018 if (!tg) 7019 return ERR_PTR(-ENOMEM); 7020 7021 if (!alloc_fair_sched_group(tg, parent)) 7022 goto err; 7023 7024 if (!alloc_rt_sched_group(tg, parent)) 7025 goto err; 7026 7027 spin_lock_irqsave(&task_group_lock, flags); 7028 list_add_rcu(&tg->list, &task_groups); 7029 7030 WARN_ON(!parent); /* root should already exist */ 7031 7032 tg->parent = parent; 7033 INIT_LIST_HEAD(&tg->children); 7034 list_add_rcu(&tg->siblings, &parent->children); 7035 spin_unlock_irqrestore(&task_group_lock, flags); 7036 7037 return tg; 7038 7039 err: 7040 free_sched_group(tg); 7041 return ERR_PTR(-ENOMEM); 7042 } 7043 7044 /* rcu callback to free various structures associated with a task group */ 7045 static void free_sched_group_rcu(struct rcu_head *rhp) 7046 { 7047 /* now it should be safe to free those cfs_rqs */ 7048 free_sched_group(container_of(rhp, struct task_group, rcu)); 7049 } 7050 7051 /* Destroy runqueue etc associated with a task group */ 7052 void sched_destroy_group(struct task_group *tg) 7053 { 7054 unsigned long flags; 7055 int i; 7056 7057 /* end participation in shares distribution */ 7058 for_each_possible_cpu(i) 7059 unregister_fair_sched_group(tg, i); 7060 7061 spin_lock_irqsave(&task_group_lock, flags); 7062 list_del_rcu(&tg->list); 7063 list_del_rcu(&tg->siblings); 7064 spin_unlock_irqrestore(&task_group_lock, flags); 7065 7066 /* wait for possible concurrent references to cfs_rqs complete */ 7067 call_rcu(&tg->rcu, free_sched_group_rcu); 7068 } 7069 7070 /* change task's runqueue when it moves between groups. 7071 * The caller of this function should have put the task in its new group 7072 * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to 7073 * reflect its new group. 7074 */ 7075 void sched_move_task(struct task_struct *tsk) 7076 { 7077 struct task_group *tg; 7078 int on_rq, running; 7079 unsigned long flags; 7080 struct rq *rq; 7081 7082 rq = task_rq_lock(tsk, &flags); 7083 7084 running = task_current(rq, tsk); 7085 on_rq = tsk->on_rq; 7086 7087 if (on_rq) 7088 dequeue_task(rq, tsk, 0); 7089 if (unlikely(running)) 7090 tsk->sched_class->put_prev_task(rq, tsk); 7091 7092 tg = container_of(task_subsys_state_check(tsk, cpu_cgroup_subsys_id, 7093 lockdep_is_held(&tsk->sighand->siglock)), 7094 struct task_group, css); 7095 tg = autogroup_task_group(tsk, tg); 7096 tsk->sched_task_group = tg; 7097 7098 #ifdef CONFIG_FAIR_GROUP_SCHED 7099 if (tsk->sched_class->task_move_group) 7100 tsk->sched_class->task_move_group(tsk, on_rq); 7101 else 7102 #endif 7103 set_task_rq(tsk, task_cpu(tsk)); 7104 7105 if (unlikely(running)) 7106 tsk->sched_class->set_curr_task(rq); 7107 if (on_rq) 7108 enqueue_task(rq, tsk, 0); 7109 7110 task_rq_unlock(rq, tsk, &flags); 7111 } 7112 #endif /* CONFIG_CGROUP_SCHED */ 7113 7114 #if defined(CONFIG_RT_GROUP_SCHED) || defined(CONFIG_CFS_BANDWIDTH) 7115 static unsigned long to_ratio(u64 period, u64 runtime) 7116 { 7117 if (runtime == RUNTIME_INF) 7118 return 1ULL << 20; 7119 7120 return div64_u64(runtime << 20, period); 7121 } 7122 #endif 7123 7124 #ifdef CONFIG_RT_GROUP_SCHED 7125 /* 7126 * Ensure that the real time constraints are schedulable. 7127 */ 7128 static DEFINE_MUTEX(rt_constraints_mutex); 7129 7130 /* Must be called with tasklist_lock held */ 7131 static inline int tg_has_rt_tasks(struct task_group *tg) 7132 { 7133 struct task_struct *g, *p; 7134 7135 do_each_thread(g, p) { 7136 if (rt_task(p) && task_rq(p)->rt.tg == tg) 7137 return 1; 7138 } while_each_thread(g, p); 7139 7140 return 0; 7141 } 7142 7143 struct rt_schedulable_data { 7144 struct task_group *tg; 7145 u64 rt_period; 7146 u64 rt_runtime; 7147 }; 7148 7149 static int tg_rt_schedulable(struct task_group *tg, void *data) 7150 { 7151 struct rt_schedulable_data *d = data; 7152 struct task_group *child; 7153 unsigned long total, sum = 0; 7154 u64 period, runtime; 7155 7156 period = ktime_to_ns(tg->rt_bandwidth.rt_period); 7157 runtime = tg->rt_bandwidth.rt_runtime; 7158 7159 if (tg == d->tg) { 7160 period = d->rt_period; 7161 runtime = d->rt_runtime; 7162 } 7163 7164 /* 7165 * Cannot have more runtime than the period. 7166 */ 7167 if (runtime > period && runtime != RUNTIME_INF) 7168 return -EINVAL; 7169 7170 /* 7171 * Ensure we don't starve existing RT tasks. 7172 */ 7173 if (rt_bandwidth_enabled() && !runtime && tg_has_rt_tasks(tg)) 7174 return -EBUSY; 7175 7176 total = to_ratio(period, runtime); 7177 7178 /* 7179 * Nobody can have more than the global setting allows. 7180 */ 7181 if (total > to_ratio(global_rt_period(), global_rt_runtime())) 7182 return -EINVAL; 7183 7184 /* 7185 * The sum of our children's runtime should not exceed our own. 7186 */ 7187 list_for_each_entry_rcu(child, &tg->children, siblings) { 7188 period = ktime_to_ns(child->rt_bandwidth.rt_period); 7189 runtime = child->rt_bandwidth.rt_runtime; 7190 7191 if (child == d->tg) { 7192 period = d->rt_period; 7193 runtime = d->rt_runtime; 7194 } 7195 7196 sum += to_ratio(period, runtime); 7197 } 7198 7199 if (sum > total) 7200 return -EINVAL; 7201 7202 return 0; 7203 } 7204 7205 static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime) 7206 { 7207 int ret; 7208 7209 struct rt_schedulable_data data = { 7210 .tg = tg, 7211 .rt_period = period, 7212 .rt_runtime = runtime, 7213 }; 7214 7215 rcu_read_lock(); 7216 ret = walk_tg_tree(tg_rt_schedulable, tg_nop, &data); 7217 rcu_read_unlock(); 7218 7219 return ret; 7220 } 7221 7222 static int tg_set_rt_bandwidth(struct task_group *tg, 7223 u64 rt_period, u64 rt_runtime) 7224 { 7225 int i, err = 0; 7226 7227 mutex_lock(&rt_constraints_mutex); 7228 read_lock(&tasklist_lock); 7229 err = __rt_schedulable(tg, rt_period, rt_runtime); 7230 if (err) 7231 goto unlock; 7232 7233 raw_spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock); 7234 tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period); 7235 tg->rt_bandwidth.rt_runtime = rt_runtime; 7236 7237 for_each_possible_cpu(i) { 7238 struct rt_rq *rt_rq = tg->rt_rq[i]; 7239 7240 raw_spin_lock(&rt_rq->rt_runtime_lock); 7241 rt_rq->rt_runtime = rt_runtime; 7242 raw_spin_unlock(&rt_rq->rt_runtime_lock); 7243 } 7244 raw_spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock); 7245 unlock: 7246 read_unlock(&tasklist_lock); 7247 mutex_unlock(&rt_constraints_mutex); 7248 7249 return err; 7250 } 7251 7252 int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us) 7253 { 7254 u64 rt_runtime, rt_period; 7255 7256 rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period); 7257 rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC; 7258 if (rt_runtime_us < 0) 7259 rt_runtime = RUNTIME_INF; 7260 7261 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime); 7262 } 7263 7264 long sched_group_rt_runtime(struct task_group *tg) 7265 { 7266 u64 rt_runtime_us; 7267 7268 if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF) 7269 return -1; 7270 7271 rt_runtime_us = tg->rt_bandwidth.rt_runtime; 7272 do_div(rt_runtime_us, NSEC_PER_USEC); 7273 return rt_runtime_us; 7274 } 7275 7276 int sched_group_set_rt_period(struct task_group *tg, long rt_period_us) 7277 { 7278 u64 rt_runtime, rt_period; 7279 7280 rt_period = (u64)rt_period_us * NSEC_PER_USEC; 7281 rt_runtime = tg->rt_bandwidth.rt_runtime; 7282 7283 if (rt_period == 0) 7284 return -EINVAL; 7285 7286 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime); 7287 } 7288 7289 long sched_group_rt_period(struct task_group *tg) 7290 { 7291 u64 rt_period_us; 7292 7293 rt_period_us = ktime_to_ns(tg->rt_bandwidth.rt_period); 7294 do_div(rt_period_us, NSEC_PER_USEC); 7295 return rt_period_us; 7296 } 7297 7298 static int sched_rt_global_constraints(void) 7299 { 7300 u64 runtime, period; 7301 int ret = 0; 7302 7303 if (sysctl_sched_rt_period <= 0) 7304 return -EINVAL; 7305 7306 runtime = global_rt_runtime(); 7307 period = global_rt_period(); 7308 7309 /* 7310 * Sanity check on the sysctl variables. 7311 */ 7312 if (runtime > period && runtime != RUNTIME_INF) 7313 return -EINVAL; 7314 7315 mutex_lock(&rt_constraints_mutex); 7316 read_lock(&tasklist_lock); 7317 ret = __rt_schedulable(NULL, 0, 0); 7318 read_unlock(&tasklist_lock); 7319 mutex_unlock(&rt_constraints_mutex); 7320 7321 return ret; 7322 } 7323 7324 int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk) 7325 { 7326 /* Don't accept realtime tasks when there is no way for them to run */ 7327 if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0) 7328 return 0; 7329 7330 return 1; 7331 } 7332 7333 #else /* !CONFIG_RT_GROUP_SCHED */ 7334 static int sched_rt_global_constraints(void) 7335 { 7336 unsigned long flags; 7337 int i; 7338 7339 if (sysctl_sched_rt_period <= 0) 7340 return -EINVAL; 7341 7342 /* 7343 * There's always some RT tasks in the root group 7344 * -- migration, kstopmachine etc.. 7345 */ 7346 if (sysctl_sched_rt_runtime == 0) 7347 return -EBUSY; 7348 7349 raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags); 7350 for_each_possible_cpu(i) { 7351 struct rt_rq *rt_rq = &cpu_rq(i)->rt; 7352 7353 raw_spin_lock(&rt_rq->rt_runtime_lock); 7354 rt_rq->rt_runtime = global_rt_runtime(); 7355 raw_spin_unlock(&rt_rq->rt_runtime_lock); 7356 } 7357 raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags); 7358 7359 return 0; 7360 } 7361 #endif /* CONFIG_RT_GROUP_SCHED */ 7362 7363 int sched_rt_handler(struct ctl_table *table, int write, 7364 void __user *buffer, size_t *lenp, 7365 loff_t *ppos) 7366 { 7367 int ret; 7368 int old_period, old_runtime; 7369 static DEFINE_MUTEX(mutex); 7370 7371 mutex_lock(&mutex); 7372 old_period = sysctl_sched_rt_period; 7373 old_runtime = sysctl_sched_rt_runtime; 7374 7375 ret = proc_dointvec(table, write, buffer, lenp, ppos); 7376 7377 if (!ret && write) { 7378 ret = sched_rt_global_constraints(); 7379 if (ret) { 7380 sysctl_sched_rt_period = old_period; 7381 sysctl_sched_rt_runtime = old_runtime; 7382 } else { 7383 def_rt_bandwidth.rt_runtime = global_rt_runtime(); 7384 def_rt_bandwidth.rt_period = 7385 ns_to_ktime(global_rt_period()); 7386 } 7387 } 7388 mutex_unlock(&mutex); 7389 7390 return ret; 7391 } 7392 7393 #ifdef CONFIG_CGROUP_SCHED 7394 7395 /* return corresponding task_group object of a cgroup */ 7396 static inline struct task_group *cgroup_tg(struct cgroup *cgrp) 7397 { 7398 return container_of(cgroup_subsys_state(cgrp, cpu_cgroup_subsys_id), 7399 struct task_group, css); 7400 } 7401 7402 static struct cgroup_subsys_state *cpu_cgroup_create(struct cgroup *cgrp) 7403 { 7404 struct task_group *tg, *parent; 7405 7406 if (!cgrp->parent) { 7407 /* This is early initialization for the top cgroup */ 7408 return &root_task_group.css; 7409 } 7410 7411 parent = cgroup_tg(cgrp->parent); 7412 tg = sched_create_group(parent); 7413 if (IS_ERR(tg)) 7414 return ERR_PTR(-ENOMEM); 7415 7416 return &tg->css; 7417 } 7418 7419 static void cpu_cgroup_destroy(struct cgroup *cgrp) 7420 { 7421 struct task_group *tg = cgroup_tg(cgrp); 7422 7423 sched_destroy_group(tg); 7424 } 7425 7426 static int cpu_cgroup_can_attach(struct cgroup *cgrp, 7427 struct cgroup_taskset *tset) 7428 { 7429 struct task_struct *task; 7430 7431 cgroup_taskset_for_each(task, cgrp, tset) { 7432 #ifdef CONFIG_RT_GROUP_SCHED 7433 if (!sched_rt_can_attach(cgroup_tg(cgrp), task)) 7434 return -EINVAL; 7435 #else 7436 /* We don't support RT-tasks being in separate groups */ 7437 if (task->sched_class != &fair_sched_class) 7438 return -EINVAL; 7439 #endif 7440 } 7441 return 0; 7442 } 7443 7444 static void cpu_cgroup_attach(struct cgroup *cgrp, 7445 struct cgroup_taskset *tset) 7446 { 7447 struct task_struct *task; 7448 7449 cgroup_taskset_for_each(task, cgrp, tset) 7450 sched_move_task(task); 7451 } 7452 7453 static void 7454 cpu_cgroup_exit(struct cgroup *cgrp, struct cgroup *old_cgrp, 7455 struct task_struct *task) 7456 { 7457 /* 7458 * cgroup_exit() is called in the copy_process() failure path. 7459 * Ignore this case since the task hasn't ran yet, this avoids 7460 * trying to poke a half freed task state from generic code. 7461 */ 7462 if (!(task->flags & PF_EXITING)) 7463 return; 7464 7465 sched_move_task(task); 7466 } 7467 7468 #ifdef CONFIG_FAIR_GROUP_SCHED 7469 static int cpu_shares_write_u64(struct cgroup *cgrp, struct cftype *cftype, 7470 u64 shareval) 7471 { 7472 return sched_group_set_shares(cgroup_tg(cgrp), scale_load(shareval)); 7473 } 7474 7475 static u64 cpu_shares_read_u64(struct cgroup *cgrp, struct cftype *cft) 7476 { 7477 struct task_group *tg = cgroup_tg(cgrp); 7478 7479 return (u64) scale_load_down(tg->shares); 7480 } 7481 7482 #ifdef CONFIG_CFS_BANDWIDTH 7483 static DEFINE_MUTEX(cfs_constraints_mutex); 7484 7485 const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */ 7486 const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */ 7487 7488 static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime); 7489 7490 static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota) 7491 { 7492 int i, ret = 0, runtime_enabled, runtime_was_enabled; 7493 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; 7494 7495 if (tg == &root_task_group) 7496 return -EINVAL; 7497 7498 /* 7499 * Ensure we have at some amount of bandwidth every period. This is 7500 * to prevent reaching a state of large arrears when throttled via 7501 * entity_tick() resulting in prolonged exit starvation. 7502 */ 7503 if (quota < min_cfs_quota_period || period < min_cfs_quota_period) 7504 return -EINVAL; 7505 7506 /* 7507 * Likewise, bound things on the otherside by preventing insane quota 7508 * periods. This also allows us to normalize in computing quota 7509 * feasibility. 7510 */ 7511 if (period > max_cfs_quota_period) 7512 return -EINVAL; 7513 7514 mutex_lock(&cfs_constraints_mutex); 7515 ret = __cfs_schedulable(tg, period, quota); 7516 if (ret) 7517 goto out_unlock; 7518 7519 runtime_enabled = quota != RUNTIME_INF; 7520 runtime_was_enabled = cfs_b->quota != RUNTIME_INF; 7521 account_cfs_bandwidth_used(runtime_enabled, runtime_was_enabled); 7522 raw_spin_lock_irq(&cfs_b->lock); 7523 cfs_b->period = ns_to_ktime(period); 7524 cfs_b->quota = quota; 7525 7526 __refill_cfs_bandwidth_runtime(cfs_b); 7527 /* restart the period timer (if active) to handle new period expiry */ 7528 if (runtime_enabled && cfs_b->timer_active) { 7529 /* force a reprogram */ 7530 cfs_b->timer_active = 0; 7531 __start_cfs_bandwidth(cfs_b); 7532 } 7533 raw_spin_unlock_irq(&cfs_b->lock); 7534 7535 for_each_possible_cpu(i) { 7536 struct cfs_rq *cfs_rq = tg->cfs_rq[i]; 7537 struct rq *rq = cfs_rq->rq; 7538 7539 raw_spin_lock_irq(&rq->lock); 7540 cfs_rq->runtime_enabled = runtime_enabled; 7541 cfs_rq->runtime_remaining = 0; 7542 7543 if (cfs_rq->throttled) 7544 unthrottle_cfs_rq(cfs_rq); 7545 raw_spin_unlock_irq(&rq->lock); 7546 } 7547 out_unlock: 7548 mutex_unlock(&cfs_constraints_mutex); 7549 7550 return ret; 7551 } 7552 7553 int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us) 7554 { 7555 u64 quota, period; 7556 7557 period = ktime_to_ns(tg->cfs_bandwidth.period); 7558 if (cfs_quota_us < 0) 7559 quota = RUNTIME_INF; 7560 else 7561 quota = (u64)cfs_quota_us * NSEC_PER_USEC; 7562 7563 return tg_set_cfs_bandwidth(tg, period, quota); 7564 } 7565 7566 long tg_get_cfs_quota(struct task_group *tg) 7567 { 7568 u64 quota_us; 7569 7570 if (tg->cfs_bandwidth.quota == RUNTIME_INF) 7571 return -1; 7572 7573 quota_us = tg->cfs_bandwidth.quota; 7574 do_div(quota_us, NSEC_PER_USEC); 7575 7576 return quota_us; 7577 } 7578 7579 int tg_set_cfs_period(struct task_group *tg, long cfs_period_us) 7580 { 7581 u64 quota, period; 7582 7583 period = (u64)cfs_period_us * NSEC_PER_USEC; 7584 quota = tg->cfs_bandwidth.quota; 7585 7586 return tg_set_cfs_bandwidth(tg, period, quota); 7587 } 7588 7589 long tg_get_cfs_period(struct task_group *tg) 7590 { 7591 u64 cfs_period_us; 7592 7593 cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period); 7594 do_div(cfs_period_us, NSEC_PER_USEC); 7595 7596 return cfs_period_us; 7597 } 7598 7599 static s64 cpu_cfs_quota_read_s64(struct cgroup *cgrp, struct cftype *cft) 7600 { 7601 return tg_get_cfs_quota(cgroup_tg(cgrp)); 7602 } 7603 7604 static int cpu_cfs_quota_write_s64(struct cgroup *cgrp, struct cftype *cftype, 7605 s64 cfs_quota_us) 7606 { 7607 return tg_set_cfs_quota(cgroup_tg(cgrp), cfs_quota_us); 7608 } 7609 7610 static u64 cpu_cfs_period_read_u64(struct cgroup *cgrp, struct cftype *cft) 7611 { 7612 return tg_get_cfs_period(cgroup_tg(cgrp)); 7613 } 7614 7615 static int cpu_cfs_period_write_u64(struct cgroup *cgrp, struct cftype *cftype, 7616 u64 cfs_period_us) 7617 { 7618 return tg_set_cfs_period(cgroup_tg(cgrp), cfs_period_us); 7619 } 7620 7621 struct cfs_schedulable_data { 7622 struct task_group *tg; 7623 u64 period, quota; 7624 }; 7625 7626 /* 7627 * normalize group quota/period to be quota/max_period 7628 * note: units are usecs 7629 */ 7630 static u64 normalize_cfs_quota(struct task_group *tg, 7631 struct cfs_schedulable_data *d) 7632 { 7633 u64 quota, period; 7634 7635 if (tg == d->tg) { 7636 period = d->period; 7637 quota = d->quota; 7638 } else { 7639 period = tg_get_cfs_period(tg); 7640 quota = tg_get_cfs_quota(tg); 7641 } 7642 7643 /* note: these should typically be equivalent */ 7644 if (quota == RUNTIME_INF || quota == -1) 7645 return RUNTIME_INF; 7646 7647 return to_ratio(period, quota); 7648 } 7649 7650 static int tg_cfs_schedulable_down(struct task_group *tg, void *data) 7651 { 7652 struct cfs_schedulable_data *d = data; 7653 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; 7654 s64 quota = 0, parent_quota = -1; 7655 7656 if (!tg->parent) { 7657 quota = RUNTIME_INF; 7658 } else { 7659 struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth; 7660 7661 quota = normalize_cfs_quota(tg, d); 7662 parent_quota = parent_b->hierarchal_quota; 7663 7664 /* 7665 * ensure max(child_quota) <= parent_quota, inherit when no 7666 * limit is set 7667 */ 7668 if (quota == RUNTIME_INF) 7669 quota = parent_quota; 7670 else if (parent_quota != RUNTIME_INF && quota > parent_quota) 7671 return -EINVAL; 7672 } 7673 cfs_b->hierarchal_quota = quota; 7674 7675 return 0; 7676 } 7677 7678 static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota) 7679 { 7680 int ret; 7681 struct cfs_schedulable_data data = { 7682 .tg = tg, 7683 .period = period, 7684 .quota = quota, 7685 }; 7686 7687 if (quota != RUNTIME_INF) { 7688 do_div(data.period, NSEC_PER_USEC); 7689 do_div(data.quota, NSEC_PER_USEC); 7690 } 7691 7692 rcu_read_lock(); 7693 ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data); 7694 rcu_read_unlock(); 7695 7696 return ret; 7697 } 7698 7699 static int cpu_stats_show(struct cgroup *cgrp, struct cftype *cft, 7700 struct cgroup_map_cb *cb) 7701 { 7702 struct task_group *tg = cgroup_tg(cgrp); 7703 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; 7704 7705 cb->fill(cb, "nr_periods", cfs_b->nr_periods); 7706 cb->fill(cb, "nr_throttled", cfs_b->nr_throttled); 7707 cb->fill(cb, "throttled_time", cfs_b->throttled_time); 7708 7709 return 0; 7710 } 7711 #endif /* CONFIG_CFS_BANDWIDTH */ 7712 #endif /* CONFIG_FAIR_GROUP_SCHED */ 7713 7714 #ifdef CONFIG_RT_GROUP_SCHED 7715 static int cpu_rt_runtime_write(struct cgroup *cgrp, struct cftype *cft, 7716 s64 val) 7717 { 7718 return sched_group_set_rt_runtime(cgroup_tg(cgrp), val); 7719 } 7720 7721 static s64 cpu_rt_runtime_read(struct cgroup *cgrp, struct cftype *cft) 7722 { 7723 return sched_group_rt_runtime(cgroup_tg(cgrp)); 7724 } 7725 7726 static int cpu_rt_period_write_uint(struct cgroup *cgrp, struct cftype *cftype, 7727 u64 rt_period_us) 7728 { 7729 return sched_group_set_rt_period(cgroup_tg(cgrp), rt_period_us); 7730 } 7731 7732 static u64 cpu_rt_period_read_uint(struct cgroup *cgrp, struct cftype *cft) 7733 { 7734 return sched_group_rt_period(cgroup_tg(cgrp)); 7735 } 7736 #endif /* CONFIG_RT_GROUP_SCHED */ 7737 7738 static struct cftype cpu_files[] = { 7739 #ifdef CONFIG_FAIR_GROUP_SCHED 7740 { 7741 .name = "shares", 7742 .read_u64 = cpu_shares_read_u64, 7743 .write_u64 = cpu_shares_write_u64, 7744 }, 7745 #endif 7746 #ifdef CONFIG_CFS_BANDWIDTH 7747 { 7748 .name = "cfs_quota_us", 7749 .read_s64 = cpu_cfs_quota_read_s64, 7750 .write_s64 = cpu_cfs_quota_write_s64, 7751 }, 7752 { 7753 .name = "cfs_period_us", 7754 .read_u64 = cpu_cfs_period_read_u64, 7755 .write_u64 = cpu_cfs_period_write_u64, 7756 }, 7757 { 7758 .name = "stat", 7759 .read_map = cpu_stats_show, 7760 }, 7761 #endif 7762 #ifdef CONFIG_RT_GROUP_SCHED 7763 { 7764 .name = "rt_runtime_us", 7765 .read_s64 = cpu_rt_runtime_read, 7766 .write_s64 = cpu_rt_runtime_write, 7767 }, 7768 { 7769 .name = "rt_period_us", 7770 .read_u64 = cpu_rt_period_read_uint, 7771 .write_u64 = cpu_rt_period_write_uint, 7772 }, 7773 #endif 7774 { } /* terminate */ 7775 }; 7776 7777 struct cgroup_subsys cpu_cgroup_subsys = { 7778 .name = "cpu", 7779 .create = cpu_cgroup_create, 7780 .destroy = cpu_cgroup_destroy, 7781 .can_attach = cpu_cgroup_can_attach, 7782 .attach = cpu_cgroup_attach, 7783 .exit = cpu_cgroup_exit, 7784 .subsys_id = cpu_cgroup_subsys_id, 7785 .base_cftypes = cpu_files, 7786 .early_init = 1, 7787 }; 7788 7789 #endif /* CONFIG_CGROUP_SCHED */ 7790 7791 #ifdef CONFIG_CGROUP_CPUACCT 7792 7793 /* 7794 * CPU accounting code for task groups. 7795 * 7796 * Based on the work by Paul Menage (menage@google.com) and Balbir Singh 7797 * (balbir@in.ibm.com). 7798 */ 7799 7800 struct cpuacct root_cpuacct; 7801 7802 /* create a new cpu accounting group */ 7803 static struct cgroup_subsys_state *cpuacct_create(struct cgroup *cgrp) 7804 { 7805 struct cpuacct *ca; 7806 7807 if (!cgrp->parent) 7808 return &root_cpuacct.css; 7809 7810 ca = kzalloc(sizeof(*ca), GFP_KERNEL); 7811 if (!ca) 7812 goto out; 7813 7814 ca->cpuusage = alloc_percpu(u64); 7815 if (!ca->cpuusage) 7816 goto out_free_ca; 7817 7818 ca->cpustat = alloc_percpu(struct kernel_cpustat); 7819 if (!ca->cpustat) 7820 goto out_free_cpuusage; 7821 7822 return &ca->css; 7823 7824 out_free_cpuusage: 7825 free_percpu(ca->cpuusage); 7826 out_free_ca: 7827 kfree(ca); 7828 out: 7829 return ERR_PTR(-ENOMEM); 7830 } 7831 7832 /* destroy an existing cpu accounting group */ 7833 static void cpuacct_destroy(struct cgroup *cgrp) 7834 { 7835 struct cpuacct *ca = cgroup_ca(cgrp); 7836 7837 free_percpu(ca->cpustat); 7838 free_percpu(ca->cpuusage); 7839 kfree(ca); 7840 } 7841 7842 static u64 cpuacct_cpuusage_read(struct cpuacct *ca, int cpu) 7843 { 7844 u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu); 7845 u64 data; 7846 7847 #ifndef CONFIG_64BIT 7848 /* 7849 * Take rq->lock to make 64-bit read safe on 32-bit platforms. 7850 */ 7851 raw_spin_lock_irq(&cpu_rq(cpu)->lock); 7852 data = *cpuusage; 7853 raw_spin_unlock_irq(&cpu_rq(cpu)->lock); 7854 #else 7855 data = *cpuusage; 7856 #endif 7857 7858 return data; 7859 } 7860 7861 static void cpuacct_cpuusage_write(struct cpuacct *ca, int cpu, u64 val) 7862 { 7863 u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu); 7864 7865 #ifndef CONFIG_64BIT 7866 /* 7867 * Take rq->lock to make 64-bit write safe on 32-bit platforms. 7868 */ 7869 raw_spin_lock_irq(&cpu_rq(cpu)->lock); 7870 *cpuusage = val; 7871 raw_spin_unlock_irq(&cpu_rq(cpu)->lock); 7872 #else 7873 *cpuusage = val; 7874 #endif 7875 } 7876 7877 /* return total cpu usage (in nanoseconds) of a group */ 7878 static u64 cpuusage_read(struct cgroup *cgrp, struct cftype *cft) 7879 { 7880 struct cpuacct *ca = cgroup_ca(cgrp); 7881 u64 totalcpuusage = 0; 7882 int i; 7883 7884 for_each_present_cpu(i) 7885 totalcpuusage += cpuacct_cpuusage_read(ca, i); 7886 7887 return totalcpuusage; 7888 } 7889 7890 static int cpuusage_write(struct cgroup *cgrp, struct cftype *cftype, 7891 u64 reset) 7892 { 7893 struct cpuacct *ca = cgroup_ca(cgrp); 7894 int err = 0; 7895 int i; 7896 7897 if (reset) { 7898 err = -EINVAL; 7899 goto out; 7900 } 7901 7902 for_each_present_cpu(i) 7903 cpuacct_cpuusage_write(ca, i, 0); 7904 7905 out: 7906 return err; 7907 } 7908 7909 static int cpuacct_percpu_seq_read(struct cgroup *cgroup, struct cftype *cft, 7910 struct seq_file *m) 7911 { 7912 struct cpuacct *ca = cgroup_ca(cgroup); 7913 u64 percpu; 7914 int i; 7915 7916 for_each_present_cpu(i) { 7917 percpu = cpuacct_cpuusage_read(ca, i); 7918 seq_printf(m, "%llu ", (unsigned long long) percpu); 7919 } 7920 seq_printf(m, "\n"); 7921 return 0; 7922 } 7923 7924 static const char *cpuacct_stat_desc[] = { 7925 [CPUACCT_STAT_USER] = "user", 7926 [CPUACCT_STAT_SYSTEM] = "system", 7927 }; 7928 7929 static int cpuacct_stats_show(struct cgroup *cgrp, struct cftype *cft, 7930 struct cgroup_map_cb *cb) 7931 { 7932 struct cpuacct *ca = cgroup_ca(cgrp); 7933 int cpu; 7934 s64 val = 0; 7935 7936 for_each_online_cpu(cpu) { 7937 struct kernel_cpustat *kcpustat = per_cpu_ptr(ca->cpustat, cpu); 7938 val += kcpustat->cpustat[CPUTIME_USER]; 7939 val += kcpustat->cpustat[CPUTIME_NICE]; 7940 } 7941 val = cputime64_to_clock_t(val); 7942 cb->fill(cb, cpuacct_stat_desc[CPUACCT_STAT_USER], val); 7943 7944 val = 0; 7945 for_each_online_cpu(cpu) { 7946 struct kernel_cpustat *kcpustat = per_cpu_ptr(ca->cpustat, cpu); 7947 val += kcpustat->cpustat[CPUTIME_SYSTEM]; 7948 val += kcpustat->cpustat[CPUTIME_IRQ]; 7949 val += kcpustat->cpustat[CPUTIME_SOFTIRQ]; 7950 } 7951 7952 val = cputime64_to_clock_t(val); 7953 cb->fill(cb, cpuacct_stat_desc[CPUACCT_STAT_SYSTEM], val); 7954 7955 return 0; 7956 } 7957 7958 static struct cftype files[] = { 7959 { 7960 .name = "usage", 7961 .read_u64 = cpuusage_read, 7962 .write_u64 = cpuusage_write, 7963 }, 7964 { 7965 .name = "usage_percpu", 7966 .read_seq_string = cpuacct_percpu_seq_read, 7967 }, 7968 { 7969 .name = "stat", 7970 .read_map = cpuacct_stats_show, 7971 }, 7972 { } /* terminate */ 7973 }; 7974 7975 /* 7976 * charge this task's execution time to its accounting group. 7977 * 7978 * called with rq->lock held. 7979 */ 7980 void cpuacct_charge(struct task_struct *tsk, u64 cputime) 7981 { 7982 struct cpuacct *ca; 7983 int cpu; 7984 7985 if (unlikely(!cpuacct_subsys.active)) 7986 return; 7987 7988 cpu = task_cpu(tsk); 7989 7990 rcu_read_lock(); 7991 7992 ca = task_ca(tsk); 7993 7994 for (; ca; ca = parent_ca(ca)) { 7995 u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu); 7996 *cpuusage += cputime; 7997 } 7998 7999 rcu_read_unlock(); 8000 } 8001 8002 struct cgroup_subsys cpuacct_subsys = { 8003 .name = "cpuacct", 8004 .create = cpuacct_create, 8005 .destroy = cpuacct_destroy, 8006 .subsys_id = cpuacct_subsys_id, 8007 .base_cftypes = files, 8008 }; 8009 #endif /* CONFIG_CGROUP_CPUACCT */ 8010