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 #ifdef CONFIG_IRQ_TIME_ACCOUNTING 744 745 /* 746 * There are no locks covering percpu hardirq/softirq time. 747 * They are only modified in account_system_vtime, on corresponding CPU 748 * with interrupts disabled. So, writes are safe. 749 * They are read and saved off onto struct rq in update_rq_clock(). 750 * This may result in other CPU reading this CPU's irq time and can 751 * race with irq/account_system_vtime on this CPU. We would either get old 752 * or new value with a side effect of accounting a slice of irq time to wrong 753 * task when irq is in progress while we read rq->clock. That is a worthy 754 * compromise in place of having locks on each irq in account_system_time. 755 */ 756 static DEFINE_PER_CPU(u64, cpu_hardirq_time); 757 static DEFINE_PER_CPU(u64, cpu_softirq_time); 758 759 static DEFINE_PER_CPU(u64, irq_start_time); 760 static int sched_clock_irqtime; 761 762 void enable_sched_clock_irqtime(void) 763 { 764 sched_clock_irqtime = 1; 765 } 766 767 void disable_sched_clock_irqtime(void) 768 { 769 sched_clock_irqtime = 0; 770 } 771 772 #ifndef CONFIG_64BIT 773 static DEFINE_PER_CPU(seqcount_t, irq_time_seq); 774 775 static inline void irq_time_write_begin(void) 776 { 777 __this_cpu_inc(irq_time_seq.sequence); 778 smp_wmb(); 779 } 780 781 static inline void irq_time_write_end(void) 782 { 783 smp_wmb(); 784 __this_cpu_inc(irq_time_seq.sequence); 785 } 786 787 static inline u64 irq_time_read(int cpu) 788 { 789 u64 irq_time; 790 unsigned seq; 791 792 do { 793 seq = read_seqcount_begin(&per_cpu(irq_time_seq, cpu)); 794 irq_time = per_cpu(cpu_softirq_time, cpu) + 795 per_cpu(cpu_hardirq_time, cpu); 796 } while (read_seqcount_retry(&per_cpu(irq_time_seq, cpu), seq)); 797 798 return irq_time; 799 } 800 #else /* CONFIG_64BIT */ 801 static inline void irq_time_write_begin(void) 802 { 803 } 804 805 static inline void irq_time_write_end(void) 806 { 807 } 808 809 static inline u64 irq_time_read(int cpu) 810 { 811 return per_cpu(cpu_softirq_time, cpu) + per_cpu(cpu_hardirq_time, cpu); 812 } 813 #endif /* CONFIG_64BIT */ 814 815 /* 816 * Called before incrementing preempt_count on {soft,}irq_enter 817 * and before decrementing preempt_count on {soft,}irq_exit. 818 */ 819 void account_system_vtime(struct task_struct *curr) 820 { 821 unsigned long flags; 822 s64 delta; 823 int cpu; 824 825 if (!sched_clock_irqtime) 826 return; 827 828 local_irq_save(flags); 829 830 cpu = smp_processor_id(); 831 delta = sched_clock_cpu(cpu) - __this_cpu_read(irq_start_time); 832 __this_cpu_add(irq_start_time, delta); 833 834 irq_time_write_begin(); 835 /* 836 * We do not account for softirq time from ksoftirqd here. 837 * We want to continue accounting softirq time to ksoftirqd thread 838 * in that case, so as not to confuse scheduler with a special task 839 * that do not consume any time, but still wants to run. 840 */ 841 if (hardirq_count()) 842 __this_cpu_add(cpu_hardirq_time, delta); 843 else if (in_serving_softirq() && curr != this_cpu_ksoftirqd()) 844 __this_cpu_add(cpu_softirq_time, delta); 845 846 irq_time_write_end(); 847 local_irq_restore(flags); 848 } 849 EXPORT_SYMBOL_GPL(account_system_vtime); 850 851 #endif /* CONFIG_IRQ_TIME_ACCOUNTING */ 852 853 #ifdef CONFIG_PARAVIRT 854 static inline u64 steal_ticks(u64 steal) 855 { 856 if (unlikely(steal > NSEC_PER_SEC)) 857 return div_u64(steal, TICK_NSEC); 858 859 return __iter_div_u64_rem(steal, TICK_NSEC, &steal); 860 } 861 #endif 862 863 static void update_rq_clock_task(struct rq *rq, s64 delta) 864 { 865 /* 866 * In theory, the compile should just see 0 here, and optimize out the call 867 * to sched_rt_avg_update. But I don't trust it... 868 */ 869 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING) 870 s64 steal = 0, irq_delta = 0; 871 #endif 872 #ifdef CONFIG_IRQ_TIME_ACCOUNTING 873 irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time; 874 875 /* 876 * Since irq_time is only updated on {soft,}irq_exit, we might run into 877 * this case when a previous update_rq_clock() happened inside a 878 * {soft,}irq region. 879 * 880 * When this happens, we stop ->clock_task and only update the 881 * prev_irq_time stamp to account for the part that fit, so that a next 882 * update will consume the rest. This ensures ->clock_task is 883 * monotonic. 884 * 885 * It does however cause some slight miss-attribution of {soft,}irq 886 * time, a more accurate solution would be to update the irq_time using 887 * the current rq->clock timestamp, except that would require using 888 * atomic ops. 889 */ 890 if (irq_delta > delta) 891 irq_delta = delta; 892 893 rq->prev_irq_time += irq_delta; 894 delta -= irq_delta; 895 #endif 896 #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING 897 if (static_key_false((¶virt_steal_rq_enabled))) { 898 u64 st; 899 900 steal = paravirt_steal_clock(cpu_of(rq)); 901 steal -= rq->prev_steal_time_rq; 902 903 if (unlikely(steal > delta)) 904 steal = delta; 905 906 st = steal_ticks(steal); 907 steal = st * TICK_NSEC; 908 909 rq->prev_steal_time_rq += steal; 910 911 delta -= steal; 912 } 913 #endif 914 915 rq->clock_task += delta; 916 917 #if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING) 918 if ((irq_delta + steal) && sched_feat(NONTASK_POWER)) 919 sched_rt_avg_update(rq, irq_delta + steal); 920 #endif 921 } 922 923 #ifdef CONFIG_IRQ_TIME_ACCOUNTING 924 static int irqtime_account_hi_update(void) 925 { 926 u64 *cpustat = kcpustat_this_cpu->cpustat; 927 unsigned long flags; 928 u64 latest_ns; 929 int ret = 0; 930 931 local_irq_save(flags); 932 latest_ns = this_cpu_read(cpu_hardirq_time); 933 if (nsecs_to_cputime64(latest_ns) > cpustat[CPUTIME_IRQ]) 934 ret = 1; 935 local_irq_restore(flags); 936 return ret; 937 } 938 939 static int irqtime_account_si_update(void) 940 { 941 u64 *cpustat = kcpustat_this_cpu->cpustat; 942 unsigned long flags; 943 u64 latest_ns; 944 int ret = 0; 945 946 local_irq_save(flags); 947 latest_ns = this_cpu_read(cpu_softirq_time); 948 if (nsecs_to_cputime64(latest_ns) > cpustat[CPUTIME_SOFTIRQ]) 949 ret = 1; 950 local_irq_restore(flags); 951 return ret; 952 } 953 954 #else /* CONFIG_IRQ_TIME_ACCOUNTING */ 955 956 #define sched_clock_irqtime (0) 957 958 #endif 959 960 void sched_set_stop_task(int cpu, struct task_struct *stop) 961 { 962 struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 }; 963 struct task_struct *old_stop = cpu_rq(cpu)->stop; 964 965 if (stop) { 966 /* 967 * Make it appear like a SCHED_FIFO task, its something 968 * userspace knows about and won't get confused about. 969 * 970 * Also, it will make PI more or less work without too 971 * much confusion -- but then, stop work should not 972 * rely on PI working anyway. 973 */ 974 sched_setscheduler_nocheck(stop, SCHED_FIFO, ¶m); 975 976 stop->sched_class = &stop_sched_class; 977 } 978 979 cpu_rq(cpu)->stop = stop; 980 981 if (old_stop) { 982 /* 983 * Reset it back to a normal scheduling class so that 984 * it can die in pieces. 985 */ 986 old_stop->sched_class = &rt_sched_class; 987 } 988 } 989 990 /* 991 * __normal_prio - return the priority that is based on the static prio 992 */ 993 static inline int __normal_prio(struct task_struct *p) 994 { 995 return p->static_prio; 996 } 997 998 /* 999 * Calculate the expected normal priority: i.e. priority 1000 * without taking RT-inheritance into account. Might be 1001 * boosted by interactivity modifiers. Changes upon fork, 1002 * setprio syscalls, and whenever the interactivity 1003 * estimator recalculates. 1004 */ 1005 static inline int normal_prio(struct task_struct *p) 1006 { 1007 int prio; 1008 1009 if (task_has_rt_policy(p)) 1010 prio = MAX_RT_PRIO-1 - p->rt_priority; 1011 else 1012 prio = __normal_prio(p); 1013 return prio; 1014 } 1015 1016 /* 1017 * Calculate the current priority, i.e. the priority 1018 * taken into account by the scheduler. This value might 1019 * be boosted by RT tasks, or might be boosted by 1020 * interactivity modifiers. Will be RT if the task got 1021 * RT-boosted. If not then it returns p->normal_prio. 1022 */ 1023 static int effective_prio(struct task_struct *p) 1024 { 1025 p->normal_prio = normal_prio(p); 1026 /* 1027 * If we are RT tasks or we were boosted to RT priority, 1028 * keep the priority unchanged. Otherwise, update priority 1029 * to the normal priority: 1030 */ 1031 if (!rt_prio(p->prio)) 1032 return p->normal_prio; 1033 return p->prio; 1034 } 1035 1036 /** 1037 * task_curr - is this task currently executing on a CPU? 1038 * @p: the task in question. 1039 */ 1040 inline int task_curr(const struct task_struct *p) 1041 { 1042 return cpu_curr(task_cpu(p)) == p; 1043 } 1044 1045 static inline void check_class_changed(struct rq *rq, struct task_struct *p, 1046 const struct sched_class *prev_class, 1047 int oldprio) 1048 { 1049 if (prev_class != p->sched_class) { 1050 if (prev_class->switched_from) 1051 prev_class->switched_from(rq, p); 1052 p->sched_class->switched_to(rq, p); 1053 } else if (oldprio != p->prio) 1054 p->sched_class->prio_changed(rq, p, oldprio); 1055 } 1056 1057 void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags) 1058 { 1059 const struct sched_class *class; 1060 1061 if (p->sched_class == rq->curr->sched_class) { 1062 rq->curr->sched_class->check_preempt_curr(rq, p, flags); 1063 } else { 1064 for_each_class(class) { 1065 if (class == rq->curr->sched_class) 1066 break; 1067 if (class == p->sched_class) { 1068 resched_task(rq->curr); 1069 break; 1070 } 1071 } 1072 } 1073 1074 /* 1075 * A queue event has occurred, and we're going to schedule. In 1076 * this case, we can save a useless back to back clock update. 1077 */ 1078 if (rq->curr->on_rq && test_tsk_need_resched(rq->curr)) 1079 rq->skip_clock_update = 1; 1080 } 1081 1082 #ifdef CONFIG_SMP 1083 void set_task_cpu(struct task_struct *p, unsigned int new_cpu) 1084 { 1085 #ifdef CONFIG_SCHED_DEBUG 1086 /* 1087 * We should never call set_task_cpu() on a blocked task, 1088 * ttwu() will sort out the placement. 1089 */ 1090 WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING && 1091 !(task_thread_info(p)->preempt_count & PREEMPT_ACTIVE)); 1092 1093 #ifdef CONFIG_LOCKDEP 1094 /* 1095 * The caller should hold either p->pi_lock or rq->lock, when changing 1096 * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks. 1097 * 1098 * sched_move_task() holds both and thus holding either pins the cgroup, 1099 * see task_group(). 1100 * 1101 * Furthermore, all task_rq users should acquire both locks, see 1102 * task_rq_lock(). 1103 */ 1104 WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) || 1105 lockdep_is_held(&task_rq(p)->lock))); 1106 #endif 1107 #endif 1108 1109 trace_sched_migrate_task(p, new_cpu); 1110 1111 if (task_cpu(p) != new_cpu) { 1112 p->se.nr_migrations++; 1113 perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, NULL, 0); 1114 } 1115 1116 __set_task_cpu(p, new_cpu); 1117 } 1118 1119 struct migration_arg { 1120 struct task_struct *task; 1121 int dest_cpu; 1122 }; 1123 1124 static int migration_cpu_stop(void *data); 1125 1126 /* 1127 * wait_task_inactive - wait for a thread to unschedule. 1128 * 1129 * If @match_state is nonzero, it's the @p->state value just checked and 1130 * not expected to change. If it changes, i.e. @p might have woken up, 1131 * then return zero. When we succeed in waiting for @p to be off its CPU, 1132 * we return a positive number (its total switch count). If a second call 1133 * a short while later returns the same number, the caller can be sure that 1134 * @p has remained unscheduled the whole time. 1135 * 1136 * The caller must ensure that the task *will* unschedule sometime soon, 1137 * else this function might spin for a *long* time. This function can't 1138 * be called with interrupts off, or it may introduce deadlock with 1139 * smp_call_function() if an IPI is sent by the same process we are 1140 * waiting to become inactive. 1141 */ 1142 unsigned long wait_task_inactive(struct task_struct *p, long match_state) 1143 { 1144 unsigned long flags; 1145 int running, on_rq; 1146 unsigned long ncsw; 1147 struct rq *rq; 1148 1149 for (;;) { 1150 /* 1151 * We do the initial early heuristics without holding 1152 * any task-queue locks at all. We'll only try to get 1153 * the runqueue lock when things look like they will 1154 * work out! 1155 */ 1156 rq = task_rq(p); 1157 1158 /* 1159 * If the task is actively running on another CPU 1160 * still, just relax and busy-wait without holding 1161 * any locks. 1162 * 1163 * NOTE! Since we don't hold any locks, it's not 1164 * even sure that "rq" stays as the right runqueue! 1165 * But we don't care, since "task_running()" will 1166 * return false if the runqueue has changed and p 1167 * is actually now running somewhere else! 1168 */ 1169 while (task_running(rq, p)) { 1170 if (match_state && unlikely(p->state != match_state)) 1171 return 0; 1172 cpu_relax(); 1173 } 1174 1175 /* 1176 * Ok, time to look more closely! We need the rq 1177 * lock now, to be *sure*. If we're wrong, we'll 1178 * just go back and repeat. 1179 */ 1180 rq = task_rq_lock(p, &flags); 1181 trace_sched_wait_task(p); 1182 running = task_running(rq, p); 1183 on_rq = p->on_rq; 1184 ncsw = 0; 1185 if (!match_state || p->state == match_state) 1186 ncsw = p->nvcsw | LONG_MIN; /* sets MSB */ 1187 task_rq_unlock(rq, p, &flags); 1188 1189 /* 1190 * If it changed from the expected state, bail out now. 1191 */ 1192 if (unlikely(!ncsw)) 1193 break; 1194 1195 /* 1196 * Was it really running after all now that we 1197 * checked with the proper locks actually held? 1198 * 1199 * Oops. Go back and try again.. 1200 */ 1201 if (unlikely(running)) { 1202 cpu_relax(); 1203 continue; 1204 } 1205 1206 /* 1207 * It's not enough that it's not actively running, 1208 * it must be off the runqueue _entirely_, and not 1209 * preempted! 1210 * 1211 * So if it was still runnable (but just not actively 1212 * running right now), it's preempted, and we should 1213 * yield - it could be a while. 1214 */ 1215 if (unlikely(on_rq)) { 1216 ktime_t to = ktime_set(0, NSEC_PER_SEC/HZ); 1217 1218 set_current_state(TASK_UNINTERRUPTIBLE); 1219 schedule_hrtimeout(&to, HRTIMER_MODE_REL); 1220 continue; 1221 } 1222 1223 /* 1224 * Ahh, all good. It wasn't running, and it wasn't 1225 * runnable, which means that it will never become 1226 * running in the future either. We're all done! 1227 */ 1228 break; 1229 } 1230 1231 return ncsw; 1232 } 1233 1234 /*** 1235 * kick_process - kick a running thread to enter/exit the kernel 1236 * @p: the to-be-kicked thread 1237 * 1238 * Cause a process which is running on another CPU to enter 1239 * kernel-mode, without any delay. (to get signals handled.) 1240 * 1241 * NOTE: this function doesn't have to take the runqueue lock, 1242 * because all it wants to ensure is that the remote task enters 1243 * the kernel. If the IPI races and the task has been migrated 1244 * to another CPU then no harm is done and the purpose has been 1245 * achieved as well. 1246 */ 1247 void kick_process(struct task_struct *p) 1248 { 1249 int cpu; 1250 1251 preempt_disable(); 1252 cpu = task_cpu(p); 1253 if ((cpu != smp_processor_id()) && task_curr(p)) 1254 smp_send_reschedule(cpu); 1255 preempt_enable(); 1256 } 1257 EXPORT_SYMBOL_GPL(kick_process); 1258 #endif /* CONFIG_SMP */ 1259 1260 #ifdef CONFIG_SMP 1261 /* 1262 * ->cpus_allowed is protected by both rq->lock and p->pi_lock 1263 */ 1264 static int select_fallback_rq(int cpu, struct task_struct *p) 1265 { 1266 const struct cpumask *nodemask = cpumask_of_node(cpu_to_node(cpu)); 1267 enum { cpuset, possible, fail } state = cpuset; 1268 int dest_cpu; 1269 1270 /* Look for allowed, online CPU in same node. */ 1271 for_each_cpu(dest_cpu, nodemask) { 1272 if (!cpu_online(dest_cpu)) 1273 continue; 1274 if (!cpu_active(dest_cpu)) 1275 continue; 1276 if (cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p))) 1277 return dest_cpu; 1278 } 1279 1280 for (;;) { 1281 /* Any allowed, online CPU? */ 1282 for_each_cpu(dest_cpu, tsk_cpus_allowed(p)) { 1283 if (!cpu_online(dest_cpu)) 1284 continue; 1285 if (!cpu_active(dest_cpu)) 1286 continue; 1287 goto out; 1288 } 1289 1290 switch (state) { 1291 case cpuset: 1292 /* No more Mr. Nice Guy. */ 1293 cpuset_cpus_allowed_fallback(p); 1294 state = possible; 1295 break; 1296 1297 case possible: 1298 do_set_cpus_allowed(p, cpu_possible_mask); 1299 state = fail; 1300 break; 1301 1302 case fail: 1303 BUG(); 1304 break; 1305 } 1306 } 1307 1308 out: 1309 if (state != cpuset) { 1310 /* 1311 * Don't tell them about moving exiting tasks or 1312 * kernel threads (both mm NULL), since they never 1313 * leave kernel. 1314 */ 1315 if (p->mm && printk_ratelimit()) { 1316 printk_sched("process %d (%s) no longer affine to cpu%d\n", 1317 task_pid_nr(p), p->comm, cpu); 1318 } 1319 } 1320 1321 return dest_cpu; 1322 } 1323 1324 /* 1325 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable. 1326 */ 1327 static inline 1328 int select_task_rq(struct task_struct *p, int sd_flags, int wake_flags) 1329 { 1330 int cpu = p->sched_class->select_task_rq(p, sd_flags, wake_flags); 1331 1332 /* 1333 * In order not to call set_task_cpu() on a blocking task we need 1334 * to rely on ttwu() to place the task on a valid ->cpus_allowed 1335 * cpu. 1336 * 1337 * Since this is common to all placement strategies, this lives here. 1338 * 1339 * [ this allows ->select_task() to simply return task_cpu(p) and 1340 * not worry about this generic constraint ] 1341 */ 1342 if (unlikely(!cpumask_test_cpu(cpu, tsk_cpus_allowed(p)) || 1343 !cpu_online(cpu))) 1344 cpu = select_fallback_rq(task_cpu(p), p); 1345 1346 return cpu; 1347 } 1348 1349 static void update_avg(u64 *avg, u64 sample) 1350 { 1351 s64 diff = sample - *avg; 1352 *avg += diff >> 3; 1353 } 1354 #endif 1355 1356 static void 1357 ttwu_stat(struct task_struct *p, int cpu, int wake_flags) 1358 { 1359 #ifdef CONFIG_SCHEDSTATS 1360 struct rq *rq = this_rq(); 1361 1362 #ifdef CONFIG_SMP 1363 int this_cpu = smp_processor_id(); 1364 1365 if (cpu == this_cpu) { 1366 schedstat_inc(rq, ttwu_local); 1367 schedstat_inc(p, se.statistics.nr_wakeups_local); 1368 } else { 1369 struct sched_domain *sd; 1370 1371 schedstat_inc(p, se.statistics.nr_wakeups_remote); 1372 rcu_read_lock(); 1373 for_each_domain(this_cpu, sd) { 1374 if (cpumask_test_cpu(cpu, sched_domain_span(sd))) { 1375 schedstat_inc(sd, ttwu_wake_remote); 1376 break; 1377 } 1378 } 1379 rcu_read_unlock(); 1380 } 1381 1382 if (wake_flags & WF_MIGRATED) 1383 schedstat_inc(p, se.statistics.nr_wakeups_migrate); 1384 1385 #endif /* CONFIG_SMP */ 1386 1387 schedstat_inc(rq, ttwu_count); 1388 schedstat_inc(p, se.statistics.nr_wakeups); 1389 1390 if (wake_flags & WF_SYNC) 1391 schedstat_inc(p, se.statistics.nr_wakeups_sync); 1392 1393 #endif /* CONFIG_SCHEDSTATS */ 1394 } 1395 1396 static void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags) 1397 { 1398 activate_task(rq, p, en_flags); 1399 p->on_rq = 1; 1400 1401 /* if a worker is waking up, notify workqueue */ 1402 if (p->flags & PF_WQ_WORKER) 1403 wq_worker_waking_up(p, cpu_of(rq)); 1404 } 1405 1406 /* 1407 * Mark the task runnable and perform wakeup-preemption. 1408 */ 1409 static void 1410 ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags) 1411 { 1412 trace_sched_wakeup(p, true); 1413 check_preempt_curr(rq, p, wake_flags); 1414 1415 p->state = TASK_RUNNING; 1416 #ifdef CONFIG_SMP 1417 if (p->sched_class->task_woken) 1418 p->sched_class->task_woken(rq, p); 1419 1420 if (rq->idle_stamp) { 1421 u64 delta = rq->clock - rq->idle_stamp; 1422 u64 max = 2*sysctl_sched_migration_cost; 1423 1424 if (delta > max) 1425 rq->avg_idle = max; 1426 else 1427 update_avg(&rq->avg_idle, delta); 1428 rq->idle_stamp = 0; 1429 } 1430 #endif 1431 } 1432 1433 static void 1434 ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags) 1435 { 1436 #ifdef CONFIG_SMP 1437 if (p->sched_contributes_to_load) 1438 rq->nr_uninterruptible--; 1439 #endif 1440 1441 ttwu_activate(rq, p, ENQUEUE_WAKEUP | ENQUEUE_WAKING); 1442 ttwu_do_wakeup(rq, p, wake_flags); 1443 } 1444 1445 /* 1446 * Called in case the task @p isn't fully descheduled from its runqueue, 1447 * in this case we must do a remote wakeup. Its a 'light' wakeup though, 1448 * since all we need to do is flip p->state to TASK_RUNNING, since 1449 * the task is still ->on_rq. 1450 */ 1451 static int ttwu_remote(struct task_struct *p, int wake_flags) 1452 { 1453 struct rq *rq; 1454 int ret = 0; 1455 1456 rq = __task_rq_lock(p); 1457 if (p->on_rq) { 1458 ttwu_do_wakeup(rq, p, wake_flags); 1459 ret = 1; 1460 } 1461 __task_rq_unlock(rq); 1462 1463 return ret; 1464 } 1465 1466 #ifdef CONFIG_SMP 1467 static void sched_ttwu_pending(void) 1468 { 1469 struct rq *rq = this_rq(); 1470 struct llist_node *llist = llist_del_all(&rq->wake_list); 1471 struct task_struct *p; 1472 1473 raw_spin_lock(&rq->lock); 1474 1475 while (llist) { 1476 p = llist_entry(llist, struct task_struct, wake_entry); 1477 llist = llist_next(llist); 1478 ttwu_do_activate(rq, p, 0); 1479 } 1480 1481 raw_spin_unlock(&rq->lock); 1482 } 1483 1484 void scheduler_ipi(void) 1485 { 1486 if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick()) 1487 return; 1488 1489 /* 1490 * Not all reschedule IPI handlers call irq_enter/irq_exit, since 1491 * traditionally all their work was done from the interrupt return 1492 * path. Now that we actually do some work, we need to make sure 1493 * we do call them. 1494 * 1495 * Some archs already do call them, luckily irq_enter/exit nest 1496 * properly. 1497 * 1498 * Arguably we should visit all archs and update all handlers, 1499 * however a fair share of IPIs are still resched only so this would 1500 * somewhat pessimize the simple resched case. 1501 */ 1502 irq_enter(); 1503 sched_ttwu_pending(); 1504 1505 /* 1506 * Check if someone kicked us for doing the nohz idle load balance. 1507 */ 1508 if (unlikely(got_nohz_idle_kick() && !need_resched())) { 1509 this_rq()->idle_balance = 1; 1510 raise_softirq_irqoff(SCHED_SOFTIRQ); 1511 } 1512 irq_exit(); 1513 } 1514 1515 static void ttwu_queue_remote(struct task_struct *p, int cpu) 1516 { 1517 if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list)) 1518 smp_send_reschedule(cpu); 1519 } 1520 1521 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW 1522 static int ttwu_activate_remote(struct task_struct *p, int wake_flags) 1523 { 1524 struct rq *rq; 1525 int ret = 0; 1526 1527 rq = __task_rq_lock(p); 1528 if (p->on_cpu) { 1529 ttwu_activate(rq, p, ENQUEUE_WAKEUP); 1530 ttwu_do_wakeup(rq, p, wake_flags); 1531 ret = 1; 1532 } 1533 __task_rq_unlock(rq); 1534 1535 return ret; 1536 1537 } 1538 #endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */ 1539 1540 bool cpus_share_cache(int this_cpu, int that_cpu) 1541 { 1542 return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu); 1543 } 1544 #endif /* CONFIG_SMP */ 1545 1546 static void ttwu_queue(struct task_struct *p, int cpu) 1547 { 1548 struct rq *rq = cpu_rq(cpu); 1549 1550 #if defined(CONFIG_SMP) 1551 if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) { 1552 sched_clock_cpu(cpu); /* sync clocks x-cpu */ 1553 ttwu_queue_remote(p, cpu); 1554 return; 1555 } 1556 #endif 1557 1558 raw_spin_lock(&rq->lock); 1559 ttwu_do_activate(rq, p, 0); 1560 raw_spin_unlock(&rq->lock); 1561 } 1562 1563 /** 1564 * try_to_wake_up - wake up a thread 1565 * @p: the thread to be awakened 1566 * @state: the mask of task states that can be woken 1567 * @wake_flags: wake modifier flags (WF_*) 1568 * 1569 * Put it on the run-queue if it's not already there. The "current" 1570 * thread is always on the run-queue (except when the actual 1571 * re-schedule is in progress), and as such you're allowed to do 1572 * the simpler "current->state = TASK_RUNNING" to mark yourself 1573 * runnable without the overhead of this. 1574 * 1575 * Returns %true if @p was woken up, %false if it was already running 1576 * or @state didn't match @p's state. 1577 */ 1578 static int 1579 try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) 1580 { 1581 unsigned long flags; 1582 int cpu, success = 0; 1583 1584 smp_wmb(); 1585 raw_spin_lock_irqsave(&p->pi_lock, flags); 1586 if (!(p->state & state)) 1587 goto out; 1588 1589 success = 1; /* we're going to change ->state */ 1590 cpu = task_cpu(p); 1591 1592 if (p->on_rq && ttwu_remote(p, wake_flags)) 1593 goto stat; 1594 1595 #ifdef CONFIG_SMP 1596 /* 1597 * If the owning (remote) cpu is still in the middle of schedule() with 1598 * this task as prev, wait until its done referencing the task. 1599 */ 1600 while (p->on_cpu) { 1601 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW 1602 /* 1603 * In case the architecture enables interrupts in 1604 * context_switch(), we cannot busy wait, since that 1605 * would lead to deadlocks when an interrupt hits and 1606 * tries to wake up @prev. So bail and do a complete 1607 * remote wakeup. 1608 */ 1609 if (ttwu_activate_remote(p, wake_flags)) 1610 goto stat; 1611 #else 1612 cpu_relax(); 1613 #endif 1614 } 1615 /* 1616 * Pairs with the smp_wmb() in finish_lock_switch(). 1617 */ 1618 smp_rmb(); 1619 1620 p->sched_contributes_to_load = !!task_contributes_to_load(p); 1621 p->state = TASK_WAKING; 1622 1623 if (p->sched_class->task_waking) 1624 p->sched_class->task_waking(p); 1625 1626 cpu = select_task_rq(p, SD_BALANCE_WAKE, wake_flags); 1627 if (task_cpu(p) != cpu) { 1628 wake_flags |= WF_MIGRATED; 1629 set_task_cpu(p, cpu); 1630 } 1631 #endif /* CONFIG_SMP */ 1632 1633 ttwu_queue(p, cpu); 1634 stat: 1635 ttwu_stat(p, cpu, wake_flags); 1636 out: 1637 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 1638 1639 return success; 1640 } 1641 1642 /** 1643 * try_to_wake_up_local - try to wake up a local task with rq lock held 1644 * @p: the thread to be awakened 1645 * 1646 * Put @p on the run-queue if it's not already there. The caller must 1647 * ensure that this_rq() is locked, @p is bound to this_rq() and not 1648 * the current task. 1649 */ 1650 static void try_to_wake_up_local(struct task_struct *p) 1651 { 1652 struct rq *rq = task_rq(p); 1653 1654 BUG_ON(rq != this_rq()); 1655 BUG_ON(p == current); 1656 lockdep_assert_held(&rq->lock); 1657 1658 if (!raw_spin_trylock(&p->pi_lock)) { 1659 raw_spin_unlock(&rq->lock); 1660 raw_spin_lock(&p->pi_lock); 1661 raw_spin_lock(&rq->lock); 1662 } 1663 1664 if (!(p->state & TASK_NORMAL)) 1665 goto out; 1666 1667 if (!p->on_rq) 1668 ttwu_activate(rq, p, ENQUEUE_WAKEUP); 1669 1670 ttwu_do_wakeup(rq, p, 0); 1671 ttwu_stat(p, smp_processor_id(), 0); 1672 out: 1673 raw_spin_unlock(&p->pi_lock); 1674 } 1675 1676 /** 1677 * wake_up_process - Wake up a specific process 1678 * @p: The process to be woken up. 1679 * 1680 * Attempt to wake up the nominated process and move it to the set of runnable 1681 * processes. Returns 1 if the process was woken up, 0 if it was already 1682 * running. 1683 * 1684 * It may be assumed that this function implies a write memory barrier before 1685 * changing the task state if and only if any tasks are woken up. 1686 */ 1687 int wake_up_process(struct task_struct *p) 1688 { 1689 return try_to_wake_up(p, TASK_ALL, 0); 1690 } 1691 EXPORT_SYMBOL(wake_up_process); 1692 1693 int wake_up_state(struct task_struct *p, unsigned int state) 1694 { 1695 return try_to_wake_up(p, state, 0); 1696 } 1697 1698 /* 1699 * Perform scheduler related setup for a newly forked process p. 1700 * p is forked by current. 1701 * 1702 * __sched_fork() is basic setup used by init_idle() too: 1703 */ 1704 static void __sched_fork(struct task_struct *p) 1705 { 1706 p->on_rq = 0; 1707 1708 p->se.on_rq = 0; 1709 p->se.exec_start = 0; 1710 p->se.sum_exec_runtime = 0; 1711 p->se.prev_sum_exec_runtime = 0; 1712 p->se.nr_migrations = 0; 1713 p->se.vruntime = 0; 1714 INIT_LIST_HEAD(&p->se.group_node); 1715 1716 #ifdef CONFIG_SCHEDSTATS 1717 memset(&p->se.statistics, 0, sizeof(p->se.statistics)); 1718 #endif 1719 1720 INIT_LIST_HEAD(&p->rt.run_list); 1721 1722 #ifdef CONFIG_PREEMPT_NOTIFIERS 1723 INIT_HLIST_HEAD(&p->preempt_notifiers); 1724 #endif 1725 } 1726 1727 /* 1728 * fork()/clone()-time setup: 1729 */ 1730 void sched_fork(struct task_struct *p) 1731 { 1732 unsigned long flags; 1733 int cpu = get_cpu(); 1734 1735 __sched_fork(p); 1736 /* 1737 * We mark the process as running here. This guarantees that 1738 * nobody will actually run it, and a signal or other external 1739 * event cannot wake it up and insert it on the runqueue either. 1740 */ 1741 p->state = TASK_RUNNING; 1742 1743 /* 1744 * Make sure we do not leak PI boosting priority to the child. 1745 */ 1746 p->prio = current->normal_prio; 1747 1748 /* 1749 * Revert to default priority/policy on fork if requested. 1750 */ 1751 if (unlikely(p->sched_reset_on_fork)) { 1752 if (task_has_rt_policy(p)) { 1753 p->policy = SCHED_NORMAL; 1754 p->static_prio = NICE_TO_PRIO(0); 1755 p->rt_priority = 0; 1756 } else if (PRIO_TO_NICE(p->static_prio) < 0) 1757 p->static_prio = NICE_TO_PRIO(0); 1758 1759 p->prio = p->normal_prio = __normal_prio(p); 1760 set_load_weight(p); 1761 1762 /* 1763 * We don't need the reset flag anymore after the fork. It has 1764 * fulfilled its duty: 1765 */ 1766 p->sched_reset_on_fork = 0; 1767 } 1768 1769 if (!rt_prio(p->prio)) 1770 p->sched_class = &fair_sched_class; 1771 1772 if (p->sched_class->task_fork) 1773 p->sched_class->task_fork(p); 1774 1775 /* 1776 * The child is not yet in the pid-hash so no cgroup attach races, 1777 * and the cgroup is pinned to this child due to cgroup_fork() 1778 * is ran before sched_fork(). 1779 * 1780 * Silence PROVE_RCU. 1781 */ 1782 raw_spin_lock_irqsave(&p->pi_lock, flags); 1783 set_task_cpu(p, cpu); 1784 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 1785 1786 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) 1787 if (likely(sched_info_on())) 1788 memset(&p->sched_info, 0, sizeof(p->sched_info)); 1789 #endif 1790 #if defined(CONFIG_SMP) 1791 p->on_cpu = 0; 1792 #endif 1793 #ifdef CONFIG_PREEMPT_COUNT 1794 /* Want to start with kernel preemption disabled. */ 1795 task_thread_info(p)->preempt_count = 1; 1796 #endif 1797 #ifdef CONFIG_SMP 1798 plist_node_init(&p->pushable_tasks, MAX_PRIO); 1799 #endif 1800 1801 put_cpu(); 1802 } 1803 1804 /* 1805 * wake_up_new_task - wake up a newly created task for the first time. 1806 * 1807 * This function will do some initial scheduler statistics housekeeping 1808 * that must be done for every newly created context, then puts the task 1809 * on the runqueue and wakes it. 1810 */ 1811 void wake_up_new_task(struct task_struct *p) 1812 { 1813 unsigned long flags; 1814 struct rq *rq; 1815 1816 raw_spin_lock_irqsave(&p->pi_lock, flags); 1817 #ifdef CONFIG_SMP 1818 /* 1819 * Fork balancing, do it here and not earlier because: 1820 * - cpus_allowed can change in the fork path 1821 * - any previously selected cpu might disappear through hotplug 1822 */ 1823 set_task_cpu(p, select_task_rq(p, SD_BALANCE_FORK, 0)); 1824 #endif 1825 1826 rq = __task_rq_lock(p); 1827 activate_task(rq, p, 0); 1828 p->on_rq = 1; 1829 trace_sched_wakeup_new(p, true); 1830 check_preempt_curr(rq, p, WF_FORK); 1831 #ifdef CONFIG_SMP 1832 if (p->sched_class->task_woken) 1833 p->sched_class->task_woken(rq, p); 1834 #endif 1835 task_rq_unlock(rq, p, &flags); 1836 } 1837 1838 #ifdef CONFIG_PREEMPT_NOTIFIERS 1839 1840 /** 1841 * preempt_notifier_register - tell me when current is being preempted & rescheduled 1842 * @notifier: notifier struct to register 1843 */ 1844 void preempt_notifier_register(struct preempt_notifier *notifier) 1845 { 1846 hlist_add_head(¬ifier->link, ¤t->preempt_notifiers); 1847 } 1848 EXPORT_SYMBOL_GPL(preempt_notifier_register); 1849 1850 /** 1851 * preempt_notifier_unregister - no longer interested in preemption notifications 1852 * @notifier: notifier struct to unregister 1853 * 1854 * This is safe to call from within a preemption notifier. 1855 */ 1856 void preempt_notifier_unregister(struct preempt_notifier *notifier) 1857 { 1858 hlist_del(¬ifier->link); 1859 } 1860 EXPORT_SYMBOL_GPL(preempt_notifier_unregister); 1861 1862 static void fire_sched_in_preempt_notifiers(struct task_struct *curr) 1863 { 1864 struct preempt_notifier *notifier; 1865 struct hlist_node *node; 1866 1867 hlist_for_each_entry(notifier, node, &curr->preempt_notifiers, link) 1868 notifier->ops->sched_in(notifier, raw_smp_processor_id()); 1869 } 1870 1871 static void 1872 fire_sched_out_preempt_notifiers(struct task_struct *curr, 1873 struct task_struct *next) 1874 { 1875 struct preempt_notifier *notifier; 1876 struct hlist_node *node; 1877 1878 hlist_for_each_entry(notifier, node, &curr->preempt_notifiers, link) 1879 notifier->ops->sched_out(notifier, next); 1880 } 1881 1882 #else /* !CONFIG_PREEMPT_NOTIFIERS */ 1883 1884 static void fire_sched_in_preempt_notifiers(struct task_struct *curr) 1885 { 1886 } 1887 1888 static void 1889 fire_sched_out_preempt_notifiers(struct task_struct *curr, 1890 struct task_struct *next) 1891 { 1892 } 1893 1894 #endif /* CONFIG_PREEMPT_NOTIFIERS */ 1895 1896 /** 1897 * prepare_task_switch - prepare to switch tasks 1898 * @rq: the runqueue preparing to switch 1899 * @prev: the current task that is being switched out 1900 * @next: the task we are going to switch to. 1901 * 1902 * This is called with the rq lock held and interrupts off. It must 1903 * be paired with a subsequent finish_task_switch after the context 1904 * switch. 1905 * 1906 * prepare_task_switch sets up locking and calls architecture specific 1907 * hooks. 1908 */ 1909 static inline void 1910 prepare_task_switch(struct rq *rq, struct task_struct *prev, 1911 struct task_struct *next) 1912 { 1913 trace_sched_switch(prev, next); 1914 sched_info_switch(prev, next); 1915 perf_event_task_sched_out(prev, next); 1916 fire_sched_out_preempt_notifiers(prev, next); 1917 prepare_lock_switch(rq, next); 1918 prepare_arch_switch(next); 1919 } 1920 1921 /** 1922 * finish_task_switch - clean up after a task-switch 1923 * @rq: runqueue associated with task-switch 1924 * @prev: the thread we just switched away from. 1925 * 1926 * finish_task_switch must be called after the context switch, paired 1927 * with a prepare_task_switch call before the context switch. 1928 * finish_task_switch will reconcile locking set up by prepare_task_switch, 1929 * and do any other architecture-specific cleanup actions. 1930 * 1931 * Note that we may have delayed dropping an mm in context_switch(). If 1932 * so, we finish that here outside of the runqueue lock. (Doing it 1933 * with the lock held can cause deadlocks; see schedule() for 1934 * details.) 1935 */ 1936 static void finish_task_switch(struct rq *rq, struct task_struct *prev) 1937 __releases(rq->lock) 1938 { 1939 struct mm_struct *mm = rq->prev_mm; 1940 long prev_state; 1941 1942 rq->prev_mm = NULL; 1943 1944 /* 1945 * A task struct has one reference for the use as "current". 1946 * If a task dies, then it sets TASK_DEAD in tsk->state and calls 1947 * schedule one last time. The schedule call will never return, and 1948 * the scheduled task must drop that reference. 1949 * The test for TASK_DEAD must occur while the runqueue locks are 1950 * still held, otherwise prev could be scheduled on another cpu, die 1951 * there before we look at prev->state, and then the reference would 1952 * be dropped twice. 1953 * Manfred Spraul <manfred@colorfullife.com> 1954 */ 1955 prev_state = prev->state; 1956 finish_arch_switch(prev); 1957 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW 1958 local_irq_disable(); 1959 #endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */ 1960 perf_event_task_sched_in(prev, current); 1961 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW 1962 local_irq_enable(); 1963 #endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */ 1964 finish_lock_switch(rq, prev); 1965 finish_arch_post_lock_switch(); 1966 1967 fire_sched_in_preempt_notifiers(current); 1968 if (mm) 1969 mmdrop(mm); 1970 if (unlikely(prev_state == TASK_DEAD)) { 1971 /* 1972 * Remove function-return probe instances associated with this 1973 * task and put them back on the free list. 1974 */ 1975 kprobe_flush_task(prev); 1976 put_task_struct(prev); 1977 } 1978 } 1979 1980 #ifdef CONFIG_SMP 1981 1982 /* assumes rq->lock is held */ 1983 static inline void pre_schedule(struct rq *rq, struct task_struct *prev) 1984 { 1985 if (prev->sched_class->pre_schedule) 1986 prev->sched_class->pre_schedule(rq, prev); 1987 } 1988 1989 /* rq->lock is NOT held, but preemption is disabled */ 1990 static inline void post_schedule(struct rq *rq) 1991 { 1992 if (rq->post_schedule) { 1993 unsigned long flags; 1994 1995 raw_spin_lock_irqsave(&rq->lock, flags); 1996 if (rq->curr->sched_class->post_schedule) 1997 rq->curr->sched_class->post_schedule(rq); 1998 raw_spin_unlock_irqrestore(&rq->lock, flags); 1999 2000 rq->post_schedule = 0; 2001 } 2002 } 2003 2004 #else 2005 2006 static inline void pre_schedule(struct rq *rq, struct task_struct *p) 2007 { 2008 } 2009 2010 static inline void post_schedule(struct rq *rq) 2011 { 2012 } 2013 2014 #endif 2015 2016 /** 2017 * schedule_tail - first thing a freshly forked thread must call. 2018 * @prev: the thread we just switched away from. 2019 */ 2020 asmlinkage void schedule_tail(struct task_struct *prev) 2021 __releases(rq->lock) 2022 { 2023 struct rq *rq = this_rq(); 2024 2025 finish_task_switch(rq, prev); 2026 2027 /* 2028 * FIXME: do we need to worry about rq being invalidated by the 2029 * task_switch? 2030 */ 2031 post_schedule(rq); 2032 2033 #ifdef __ARCH_WANT_UNLOCKED_CTXSW 2034 /* In this case, finish_task_switch does not reenable preemption */ 2035 preempt_enable(); 2036 #endif 2037 if (current->set_child_tid) 2038 put_user(task_pid_vnr(current), current->set_child_tid); 2039 } 2040 2041 /* 2042 * context_switch - switch to the new MM and the new 2043 * thread's register state. 2044 */ 2045 static inline void 2046 context_switch(struct rq *rq, struct task_struct *prev, 2047 struct task_struct *next) 2048 { 2049 struct mm_struct *mm, *oldmm; 2050 2051 prepare_task_switch(rq, prev, next); 2052 2053 mm = next->mm; 2054 oldmm = prev->active_mm; 2055 /* 2056 * For paravirt, this is coupled with an exit in switch_to to 2057 * combine the page table reload and the switch backend into 2058 * one hypercall. 2059 */ 2060 arch_start_context_switch(prev); 2061 2062 if (!mm) { 2063 next->active_mm = oldmm; 2064 atomic_inc(&oldmm->mm_count); 2065 enter_lazy_tlb(oldmm, next); 2066 } else 2067 switch_mm(oldmm, mm, next); 2068 2069 if (!prev->mm) { 2070 prev->active_mm = NULL; 2071 rq->prev_mm = oldmm; 2072 } 2073 /* 2074 * Since the runqueue lock will be released by the next 2075 * task (which is an invalid locking op but in the case 2076 * of the scheduler it's an obvious special-case), so we 2077 * do an early lockdep release here: 2078 */ 2079 #ifndef __ARCH_WANT_UNLOCKED_CTXSW 2080 spin_release(&rq->lock.dep_map, 1, _THIS_IP_); 2081 #endif 2082 2083 /* Here we just switch the register state and the stack. */ 2084 switch_to(prev, next, prev); 2085 2086 barrier(); 2087 /* 2088 * this_rq must be evaluated again because prev may have moved 2089 * CPUs since it called schedule(), thus the 'rq' on its stack 2090 * frame will be invalid. 2091 */ 2092 finish_task_switch(this_rq(), prev); 2093 } 2094 2095 /* 2096 * nr_running, nr_uninterruptible and nr_context_switches: 2097 * 2098 * externally visible scheduler statistics: current number of runnable 2099 * threads, current number of uninterruptible-sleeping threads, total 2100 * number of context switches performed since bootup. 2101 */ 2102 unsigned long nr_running(void) 2103 { 2104 unsigned long i, sum = 0; 2105 2106 for_each_online_cpu(i) 2107 sum += cpu_rq(i)->nr_running; 2108 2109 return sum; 2110 } 2111 2112 unsigned long nr_uninterruptible(void) 2113 { 2114 unsigned long i, sum = 0; 2115 2116 for_each_possible_cpu(i) 2117 sum += cpu_rq(i)->nr_uninterruptible; 2118 2119 /* 2120 * Since we read the counters lockless, it might be slightly 2121 * inaccurate. Do not allow it to go below zero though: 2122 */ 2123 if (unlikely((long)sum < 0)) 2124 sum = 0; 2125 2126 return sum; 2127 } 2128 2129 unsigned long long nr_context_switches(void) 2130 { 2131 int i; 2132 unsigned long long sum = 0; 2133 2134 for_each_possible_cpu(i) 2135 sum += cpu_rq(i)->nr_switches; 2136 2137 return sum; 2138 } 2139 2140 unsigned long nr_iowait(void) 2141 { 2142 unsigned long i, sum = 0; 2143 2144 for_each_possible_cpu(i) 2145 sum += atomic_read(&cpu_rq(i)->nr_iowait); 2146 2147 return sum; 2148 } 2149 2150 unsigned long nr_iowait_cpu(int cpu) 2151 { 2152 struct rq *this = cpu_rq(cpu); 2153 return atomic_read(&this->nr_iowait); 2154 } 2155 2156 unsigned long this_cpu_load(void) 2157 { 2158 struct rq *this = this_rq(); 2159 return this->cpu_load[0]; 2160 } 2161 2162 2163 /* 2164 * Global load-average calculations 2165 * 2166 * We take a distributed and async approach to calculating the global load-avg 2167 * in order to minimize overhead. 2168 * 2169 * The global load average is an exponentially decaying average of nr_running + 2170 * nr_uninterruptible. 2171 * 2172 * Once every LOAD_FREQ: 2173 * 2174 * nr_active = 0; 2175 * for_each_possible_cpu(cpu) 2176 * nr_active += cpu_of(cpu)->nr_running + cpu_of(cpu)->nr_uninterruptible; 2177 * 2178 * avenrun[n] = avenrun[0] * exp_n + nr_active * (1 - exp_n) 2179 * 2180 * Due to a number of reasons the above turns in the mess below: 2181 * 2182 * - for_each_possible_cpu() is prohibitively expensive on machines with 2183 * serious number of cpus, therefore we need to take a distributed approach 2184 * to calculating nr_active. 2185 * 2186 * \Sum_i x_i(t) = \Sum_i x_i(t) - x_i(t_0) | x_i(t_0) := 0 2187 * = \Sum_i { \Sum_j=1 x_i(t_j) - x_i(t_j-1) } 2188 * 2189 * So assuming nr_active := 0 when we start out -- true per definition, we 2190 * can simply take per-cpu deltas and fold those into a global accumulate 2191 * to obtain the same result. See calc_load_fold_active(). 2192 * 2193 * Furthermore, in order to avoid synchronizing all per-cpu delta folding 2194 * across the machine, we assume 10 ticks is sufficient time for every 2195 * cpu to have completed this task. 2196 * 2197 * This places an upper-bound on the IRQ-off latency of the machine. Then 2198 * again, being late doesn't loose the delta, just wrecks the sample. 2199 * 2200 * - cpu_rq()->nr_uninterruptible isn't accurately tracked per-cpu because 2201 * this would add another cross-cpu cacheline miss and atomic operation 2202 * to the wakeup path. Instead we increment on whatever cpu the task ran 2203 * when it went into uninterruptible state and decrement on whatever cpu 2204 * did the wakeup. This means that only the sum of nr_uninterruptible over 2205 * all cpus yields the correct result. 2206 * 2207 * This covers the NO_HZ=n code, for extra head-aches, see the comment below. 2208 */ 2209 2210 /* Variables and functions for calc_load */ 2211 static atomic_long_t calc_load_tasks; 2212 static unsigned long calc_load_update; 2213 unsigned long avenrun[3]; 2214 EXPORT_SYMBOL(avenrun); /* should be removed */ 2215 2216 /** 2217 * get_avenrun - get the load average array 2218 * @loads: pointer to dest load array 2219 * @offset: offset to add 2220 * @shift: shift count to shift the result left 2221 * 2222 * These values are estimates at best, so no need for locking. 2223 */ 2224 void get_avenrun(unsigned long *loads, unsigned long offset, int shift) 2225 { 2226 loads[0] = (avenrun[0] + offset) << shift; 2227 loads[1] = (avenrun[1] + offset) << shift; 2228 loads[2] = (avenrun[2] + offset) << shift; 2229 } 2230 2231 static long calc_load_fold_active(struct rq *this_rq) 2232 { 2233 long nr_active, delta = 0; 2234 2235 nr_active = this_rq->nr_running; 2236 nr_active += (long) this_rq->nr_uninterruptible; 2237 2238 if (nr_active != this_rq->calc_load_active) { 2239 delta = nr_active - this_rq->calc_load_active; 2240 this_rq->calc_load_active = nr_active; 2241 } 2242 2243 return delta; 2244 } 2245 2246 /* 2247 * a1 = a0 * e + a * (1 - e) 2248 */ 2249 static unsigned long 2250 calc_load(unsigned long load, unsigned long exp, unsigned long active) 2251 { 2252 load *= exp; 2253 load += active * (FIXED_1 - exp); 2254 load += 1UL << (FSHIFT - 1); 2255 return load >> FSHIFT; 2256 } 2257 2258 #ifdef CONFIG_NO_HZ 2259 /* 2260 * Handle NO_HZ for the global load-average. 2261 * 2262 * Since the above described distributed algorithm to compute the global 2263 * load-average relies on per-cpu sampling from the tick, it is affected by 2264 * NO_HZ. 2265 * 2266 * The basic idea is to fold the nr_active delta into a global idle-delta upon 2267 * entering NO_HZ state such that we can include this as an 'extra' cpu delta 2268 * when we read the global state. 2269 * 2270 * Obviously reality has to ruin such a delightfully simple scheme: 2271 * 2272 * - When we go NO_HZ idle during the window, we can negate our sample 2273 * contribution, causing under-accounting. 2274 * 2275 * We avoid this by keeping two idle-delta counters and flipping them 2276 * when the window starts, thus separating old and new NO_HZ load. 2277 * 2278 * The only trick is the slight shift in index flip for read vs write. 2279 * 2280 * 0s 5s 10s 15s 2281 * +10 +10 +10 +10 2282 * |-|-----------|-|-----------|-|-----------|-| 2283 * r:0 0 1 1 0 0 1 1 0 2284 * w:0 1 1 0 0 1 1 0 0 2285 * 2286 * This ensures we'll fold the old idle contribution in this window while 2287 * accumlating the new one. 2288 * 2289 * - When we wake up from NO_HZ idle during the window, we push up our 2290 * contribution, since we effectively move our sample point to a known 2291 * busy state. 2292 * 2293 * This is solved by pushing the window forward, and thus skipping the 2294 * sample, for this cpu (effectively using the idle-delta for this cpu which 2295 * was in effect at the time the window opened). This also solves the issue 2296 * of having to deal with a cpu having been in NOHZ idle for multiple 2297 * LOAD_FREQ intervals. 2298 * 2299 * When making the ILB scale, we should try to pull this in as well. 2300 */ 2301 static atomic_long_t calc_load_idle[2]; 2302 static int calc_load_idx; 2303 2304 static inline int calc_load_write_idx(void) 2305 { 2306 int idx = calc_load_idx; 2307 2308 /* 2309 * See calc_global_nohz(), if we observe the new index, we also 2310 * need to observe the new update time. 2311 */ 2312 smp_rmb(); 2313 2314 /* 2315 * If the folding window started, make sure we start writing in the 2316 * next idle-delta. 2317 */ 2318 if (!time_before(jiffies, calc_load_update)) 2319 idx++; 2320 2321 return idx & 1; 2322 } 2323 2324 static inline int calc_load_read_idx(void) 2325 { 2326 return calc_load_idx & 1; 2327 } 2328 2329 void calc_load_enter_idle(void) 2330 { 2331 struct rq *this_rq = this_rq(); 2332 long delta; 2333 2334 /* 2335 * We're going into NOHZ mode, if there's any pending delta, fold it 2336 * into the pending idle delta. 2337 */ 2338 delta = calc_load_fold_active(this_rq); 2339 if (delta) { 2340 int idx = calc_load_write_idx(); 2341 atomic_long_add(delta, &calc_load_idle[idx]); 2342 } 2343 } 2344 2345 void calc_load_exit_idle(void) 2346 { 2347 struct rq *this_rq = this_rq(); 2348 2349 /* 2350 * If we're still before the sample window, we're done. 2351 */ 2352 if (time_before(jiffies, this_rq->calc_load_update)) 2353 return; 2354 2355 /* 2356 * We woke inside or after the sample window, this means we're already 2357 * accounted through the nohz accounting, so skip the entire deal and 2358 * sync up for the next window. 2359 */ 2360 this_rq->calc_load_update = calc_load_update; 2361 if (time_before(jiffies, this_rq->calc_load_update + 10)) 2362 this_rq->calc_load_update += LOAD_FREQ; 2363 } 2364 2365 static long calc_load_fold_idle(void) 2366 { 2367 int idx = calc_load_read_idx(); 2368 long delta = 0; 2369 2370 if (atomic_long_read(&calc_load_idle[idx])) 2371 delta = atomic_long_xchg(&calc_load_idle[idx], 0); 2372 2373 return delta; 2374 } 2375 2376 /** 2377 * fixed_power_int - compute: x^n, in O(log n) time 2378 * 2379 * @x: base of the power 2380 * @frac_bits: fractional bits of @x 2381 * @n: power to raise @x to. 2382 * 2383 * By exploiting the relation between the definition of the natural power 2384 * function: x^n := x*x*...*x (x multiplied by itself for n times), and 2385 * the binary encoding of numbers used by computers: n := \Sum n_i * 2^i, 2386 * (where: n_i \elem {0, 1}, the binary vector representing n), 2387 * we find: x^n := x^(\Sum n_i * 2^i) := \Prod x^(n_i * 2^i), which is 2388 * of course trivially computable in O(log_2 n), the length of our binary 2389 * vector. 2390 */ 2391 static unsigned long 2392 fixed_power_int(unsigned long x, unsigned int frac_bits, unsigned int n) 2393 { 2394 unsigned long result = 1UL << frac_bits; 2395 2396 if (n) for (;;) { 2397 if (n & 1) { 2398 result *= x; 2399 result += 1UL << (frac_bits - 1); 2400 result >>= frac_bits; 2401 } 2402 n >>= 1; 2403 if (!n) 2404 break; 2405 x *= x; 2406 x += 1UL << (frac_bits - 1); 2407 x >>= frac_bits; 2408 } 2409 2410 return result; 2411 } 2412 2413 /* 2414 * a1 = a0 * e + a * (1 - e) 2415 * 2416 * a2 = a1 * e + a * (1 - e) 2417 * = (a0 * e + a * (1 - e)) * e + a * (1 - e) 2418 * = a0 * e^2 + a * (1 - e) * (1 + e) 2419 * 2420 * a3 = a2 * e + a * (1 - e) 2421 * = (a0 * e^2 + a * (1 - e) * (1 + e)) * e + a * (1 - e) 2422 * = a0 * e^3 + a * (1 - e) * (1 + e + e^2) 2423 * 2424 * ... 2425 * 2426 * an = a0 * e^n + a * (1 - e) * (1 + e + ... + e^n-1) [1] 2427 * = a0 * e^n + a * (1 - e) * (1 - e^n)/(1 - e) 2428 * = a0 * e^n + a * (1 - e^n) 2429 * 2430 * [1] application of the geometric series: 2431 * 2432 * n 1 - x^(n+1) 2433 * S_n := \Sum x^i = ------------- 2434 * i=0 1 - x 2435 */ 2436 static unsigned long 2437 calc_load_n(unsigned long load, unsigned long exp, 2438 unsigned long active, unsigned int n) 2439 { 2440 2441 return calc_load(load, fixed_power_int(exp, FSHIFT, n), active); 2442 } 2443 2444 /* 2445 * NO_HZ can leave us missing all per-cpu ticks calling 2446 * calc_load_account_active(), but since an idle CPU folds its delta into 2447 * calc_load_tasks_idle per calc_load_account_idle(), all we need to do is fold 2448 * in the pending idle delta if our idle period crossed a load cycle boundary. 2449 * 2450 * Once we've updated the global active value, we need to apply the exponential 2451 * weights adjusted to the number of cycles missed. 2452 */ 2453 static void calc_global_nohz(void) 2454 { 2455 long delta, active, n; 2456 2457 if (!time_before(jiffies, calc_load_update + 10)) { 2458 /* 2459 * Catch-up, fold however many we are behind still 2460 */ 2461 delta = jiffies - calc_load_update - 10; 2462 n = 1 + (delta / LOAD_FREQ); 2463 2464 active = atomic_long_read(&calc_load_tasks); 2465 active = active > 0 ? active * FIXED_1 : 0; 2466 2467 avenrun[0] = calc_load_n(avenrun[0], EXP_1, active, n); 2468 avenrun[1] = calc_load_n(avenrun[1], EXP_5, active, n); 2469 avenrun[2] = calc_load_n(avenrun[2], EXP_15, active, n); 2470 2471 calc_load_update += n * LOAD_FREQ; 2472 } 2473 2474 /* 2475 * Flip the idle index... 2476 * 2477 * Make sure we first write the new time then flip the index, so that 2478 * calc_load_write_idx() will see the new time when it reads the new 2479 * index, this avoids a double flip messing things up. 2480 */ 2481 smp_wmb(); 2482 calc_load_idx++; 2483 } 2484 #else /* !CONFIG_NO_HZ */ 2485 2486 static inline long calc_load_fold_idle(void) { return 0; } 2487 static inline void calc_global_nohz(void) { } 2488 2489 #endif /* CONFIG_NO_HZ */ 2490 2491 /* 2492 * calc_load - update the avenrun load estimates 10 ticks after the 2493 * CPUs have updated calc_load_tasks. 2494 */ 2495 void calc_global_load(unsigned long ticks) 2496 { 2497 long active, delta; 2498 2499 if (time_before(jiffies, calc_load_update + 10)) 2500 return; 2501 2502 /* 2503 * Fold the 'old' idle-delta to include all NO_HZ cpus. 2504 */ 2505 delta = calc_load_fold_idle(); 2506 if (delta) 2507 atomic_long_add(delta, &calc_load_tasks); 2508 2509 active = atomic_long_read(&calc_load_tasks); 2510 active = active > 0 ? active * FIXED_1 : 0; 2511 2512 avenrun[0] = calc_load(avenrun[0], EXP_1, active); 2513 avenrun[1] = calc_load(avenrun[1], EXP_5, active); 2514 avenrun[2] = calc_load(avenrun[2], EXP_15, active); 2515 2516 calc_load_update += LOAD_FREQ; 2517 2518 /* 2519 * In case we idled for multiple LOAD_FREQ intervals, catch up in bulk. 2520 */ 2521 calc_global_nohz(); 2522 } 2523 2524 /* 2525 * Called from update_cpu_load() to periodically update this CPU's 2526 * active count. 2527 */ 2528 static void calc_load_account_active(struct rq *this_rq) 2529 { 2530 long delta; 2531 2532 if (time_before(jiffies, this_rq->calc_load_update)) 2533 return; 2534 2535 delta = calc_load_fold_active(this_rq); 2536 if (delta) 2537 atomic_long_add(delta, &calc_load_tasks); 2538 2539 this_rq->calc_load_update += LOAD_FREQ; 2540 } 2541 2542 /* 2543 * End of global load-average stuff 2544 */ 2545 2546 /* 2547 * The exact cpuload at various idx values, calculated at every tick would be 2548 * load = (2^idx - 1) / 2^idx * load + 1 / 2^idx * cur_load 2549 * 2550 * If a cpu misses updates for n-1 ticks (as it was idle) and update gets called 2551 * on nth tick when cpu may be busy, then we have: 2552 * load = ((2^idx - 1) / 2^idx)^(n-1) * load 2553 * load = (2^idx - 1) / 2^idx) * load + 1 / 2^idx * cur_load 2554 * 2555 * decay_load_missed() below does efficient calculation of 2556 * load = ((2^idx - 1) / 2^idx)^(n-1) * load 2557 * avoiding 0..n-1 loop doing load = ((2^idx - 1) / 2^idx) * load 2558 * 2559 * The calculation is approximated on a 128 point scale. 2560 * degrade_zero_ticks is the number of ticks after which load at any 2561 * particular idx is approximated to be zero. 2562 * degrade_factor is a precomputed table, a row for each load idx. 2563 * Each column corresponds to degradation factor for a power of two ticks, 2564 * based on 128 point scale. 2565 * Example: 2566 * row 2, col 3 (=12) says that the degradation at load idx 2 after 2567 * 8 ticks is 12/128 (which is an approximation of exact factor 3^8/4^8). 2568 * 2569 * With this power of 2 load factors, we can degrade the load n times 2570 * by looking at 1 bits in n and doing as many mult/shift instead of 2571 * n mult/shifts needed by the exact degradation. 2572 */ 2573 #define DEGRADE_SHIFT 7 2574 static const unsigned char 2575 degrade_zero_ticks[CPU_LOAD_IDX_MAX] = {0, 8, 32, 64, 128}; 2576 static const unsigned char 2577 degrade_factor[CPU_LOAD_IDX_MAX][DEGRADE_SHIFT + 1] = { 2578 {0, 0, 0, 0, 0, 0, 0, 0}, 2579 {64, 32, 8, 0, 0, 0, 0, 0}, 2580 {96, 72, 40, 12, 1, 0, 0}, 2581 {112, 98, 75, 43, 15, 1, 0}, 2582 {120, 112, 98, 76, 45, 16, 2} }; 2583 2584 /* 2585 * Update cpu_load for any missed ticks, due to tickless idle. The backlog 2586 * would be when CPU is idle and so we just decay the old load without 2587 * adding any new load. 2588 */ 2589 static unsigned long 2590 decay_load_missed(unsigned long load, unsigned long missed_updates, int idx) 2591 { 2592 int j = 0; 2593 2594 if (!missed_updates) 2595 return load; 2596 2597 if (missed_updates >= degrade_zero_ticks[idx]) 2598 return 0; 2599 2600 if (idx == 1) 2601 return load >> missed_updates; 2602 2603 while (missed_updates) { 2604 if (missed_updates % 2) 2605 load = (load * degrade_factor[idx][j]) >> DEGRADE_SHIFT; 2606 2607 missed_updates >>= 1; 2608 j++; 2609 } 2610 return load; 2611 } 2612 2613 /* 2614 * Update rq->cpu_load[] statistics. This function is usually called every 2615 * scheduler tick (TICK_NSEC). With tickless idle this will not be called 2616 * every tick. We fix it up based on jiffies. 2617 */ 2618 static void __update_cpu_load(struct rq *this_rq, unsigned long this_load, 2619 unsigned long pending_updates) 2620 { 2621 int i, scale; 2622 2623 this_rq->nr_load_updates++; 2624 2625 /* Update our load: */ 2626 this_rq->cpu_load[0] = this_load; /* Fasttrack for idx 0 */ 2627 for (i = 1, scale = 2; i < CPU_LOAD_IDX_MAX; i++, scale += scale) { 2628 unsigned long old_load, new_load; 2629 2630 /* scale is effectively 1 << i now, and >> i divides by scale */ 2631 2632 old_load = this_rq->cpu_load[i]; 2633 old_load = decay_load_missed(old_load, pending_updates - 1, i); 2634 new_load = this_load; 2635 /* 2636 * Round up the averaging division if load is increasing. This 2637 * prevents us from getting stuck on 9 if the load is 10, for 2638 * example. 2639 */ 2640 if (new_load > old_load) 2641 new_load += scale - 1; 2642 2643 this_rq->cpu_load[i] = (old_load * (scale - 1) + new_load) >> i; 2644 } 2645 2646 sched_avg_update(this_rq); 2647 } 2648 2649 #ifdef CONFIG_NO_HZ 2650 /* 2651 * There is no sane way to deal with nohz on smp when using jiffies because the 2652 * cpu doing the jiffies update might drift wrt the cpu doing the jiffy reading 2653 * causing off-by-one errors in observed deltas; {0,2} instead of {1,1}. 2654 * 2655 * Therefore we cannot use the delta approach from the regular tick since that 2656 * would seriously skew the load calculation. However we'll make do for those 2657 * updates happening while idle (nohz_idle_balance) or coming out of idle 2658 * (tick_nohz_idle_exit). 2659 * 2660 * This means we might still be one tick off for nohz periods. 2661 */ 2662 2663 /* 2664 * Called from nohz_idle_balance() to update the load ratings before doing the 2665 * idle balance. 2666 */ 2667 void update_idle_cpu_load(struct rq *this_rq) 2668 { 2669 unsigned long curr_jiffies = ACCESS_ONCE(jiffies); 2670 unsigned long load = this_rq->load.weight; 2671 unsigned long pending_updates; 2672 2673 /* 2674 * bail if there's load or we're actually up-to-date. 2675 */ 2676 if (load || curr_jiffies == this_rq->last_load_update_tick) 2677 return; 2678 2679 pending_updates = curr_jiffies - this_rq->last_load_update_tick; 2680 this_rq->last_load_update_tick = curr_jiffies; 2681 2682 __update_cpu_load(this_rq, load, pending_updates); 2683 } 2684 2685 /* 2686 * Called from tick_nohz_idle_exit() -- try and fix up the ticks we missed. 2687 */ 2688 void update_cpu_load_nohz(void) 2689 { 2690 struct rq *this_rq = this_rq(); 2691 unsigned long curr_jiffies = ACCESS_ONCE(jiffies); 2692 unsigned long pending_updates; 2693 2694 if (curr_jiffies == this_rq->last_load_update_tick) 2695 return; 2696 2697 raw_spin_lock(&this_rq->lock); 2698 pending_updates = curr_jiffies - this_rq->last_load_update_tick; 2699 if (pending_updates) { 2700 this_rq->last_load_update_tick = curr_jiffies; 2701 /* 2702 * We were idle, this means load 0, the current load might be 2703 * !0 due to remote wakeups and the sort. 2704 */ 2705 __update_cpu_load(this_rq, 0, pending_updates); 2706 } 2707 raw_spin_unlock(&this_rq->lock); 2708 } 2709 #endif /* CONFIG_NO_HZ */ 2710 2711 /* 2712 * Called from scheduler_tick() 2713 */ 2714 static void update_cpu_load_active(struct rq *this_rq) 2715 { 2716 /* 2717 * See the mess around update_idle_cpu_load() / update_cpu_load_nohz(). 2718 */ 2719 this_rq->last_load_update_tick = jiffies; 2720 __update_cpu_load(this_rq, this_rq->load.weight, 1); 2721 2722 calc_load_account_active(this_rq); 2723 } 2724 2725 #ifdef CONFIG_SMP 2726 2727 /* 2728 * sched_exec - execve() is a valuable balancing opportunity, because at 2729 * this point the task has the smallest effective memory and cache footprint. 2730 */ 2731 void sched_exec(void) 2732 { 2733 struct task_struct *p = current; 2734 unsigned long flags; 2735 int dest_cpu; 2736 2737 raw_spin_lock_irqsave(&p->pi_lock, flags); 2738 dest_cpu = p->sched_class->select_task_rq(p, SD_BALANCE_EXEC, 0); 2739 if (dest_cpu == smp_processor_id()) 2740 goto unlock; 2741 2742 if (likely(cpu_active(dest_cpu))) { 2743 struct migration_arg arg = { p, dest_cpu }; 2744 2745 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 2746 stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg); 2747 return; 2748 } 2749 unlock: 2750 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 2751 } 2752 2753 #endif 2754 2755 DEFINE_PER_CPU(struct kernel_stat, kstat); 2756 DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat); 2757 2758 EXPORT_PER_CPU_SYMBOL(kstat); 2759 EXPORT_PER_CPU_SYMBOL(kernel_cpustat); 2760 2761 /* 2762 * Return any ns on the sched_clock that have not yet been accounted in 2763 * @p in case that task is currently running. 2764 * 2765 * Called with task_rq_lock() held on @rq. 2766 */ 2767 static u64 do_task_delta_exec(struct task_struct *p, struct rq *rq) 2768 { 2769 u64 ns = 0; 2770 2771 if (task_current(rq, p)) { 2772 update_rq_clock(rq); 2773 ns = rq->clock_task - p->se.exec_start; 2774 if ((s64)ns < 0) 2775 ns = 0; 2776 } 2777 2778 return ns; 2779 } 2780 2781 unsigned long long task_delta_exec(struct task_struct *p) 2782 { 2783 unsigned long flags; 2784 struct rq *rq; 2785 u64 ns = 0; 2786 2787 rq = task_rq_lock(p, &flags); 2788 ns = do_task_delta_exec(p, rq); 2789 task_rq_unlock(rq, p, &flags); 2790 2791 return ns; 2792 } 2793 2794 /* 2795 * Return accounted runtime for the task. 2796 * In case the task is currently running, return the runtime plus current's 2797 * pending runtime that have not been accounted yet. 2798 */ 2799 unsigned long long task_sched_runtime(struct task_struct *p) 2800 { 2801 unsigned long flags; 2802 struct rq *rq; 2803 u64 ns = 0; 2804 2805 rq = task_rq_lock(p, &flags); 2806 ns = p->se.sum_exec_runtime + do_task_delta_exec(p, rq); 2807 task_rq_unlock(rq, p, &flags); 2808 2809 return ns; 2810 } 2811 2812 #ifdef CONFIG_CGROUP_CPUACCT 2813 struct cgroup_subsys cpuacct_subsys; 2814 struct cpuacct root_cpuacct; 2815 #endif 2816 2817 static inline void task_group_account_field(struct task_struct *p, int index, 2818 u64 tmp) 2819 { 2820 #ifdef CONFIG_CGROUP_CPUACCT 2821 struct kernel_cpustat *kcpustat; 2822 struct cpuacct *ca; 2823 #endif 2824 /* 2825 * Since all updates are sure to touch the root cgroup, we 2826 * get ourselves ahead and touch it first. If the root cgroup 2827 * is the only cgroup, then nothing else should be necessary. 2828 * 2829 */ 2830 __get_cpu_var(kernel_cpustat).cpustat[index] += tmp; 2831 2832 #ifdef CONFIG_CGROUP_CPUACCT 2833 if (unlikely(!cpuacct_subsys.active)) 2834 return; 2835 2836 rcu_read_lock(); 2837 ca = task_ca(p); 2838 while (ca && (ca != &root_cpuacct)) { 2839 kcpustat = this_cpu_ptr(ca->cpustat); 2840 kcpustat->cpustat[index] += tmp; 2841 ca = parent_ca(ca); 2842 } 2843 rcu_read_unlock(); 2844 #endif 2845 } 2846 2847 2848 /* 2849 * Account user cpu time to a process. 2850 * @p: the process that the cpu time gets accounted to 2851 * @cputime: the cpu time spent in user space since the last update 2852 * @cputime_scaled: cputime scaled by cpu frequency 2853 */ 2854 void account_user_time(struct task_struct *p, cputime_t cputime, 2855 cputime_t cputime_scaled) 2856 { 2857 int index; 2858 2859 /* Add user time to process. */ 2860 p->utime += cputime; 2861 p->utimescaled += cputime_scaled; 2862 account_group_user_time(p, cputime); 2863 2864 index = (TASK_NICE(p) > 0) ? CPUTIME_NICE : CPUTIME_USER; 2865 2866 /* Add user time to cpustat. */ 2867 task_group_account_field(p, index, (__force u64) cputime); 2868 2869 /* Account for user time used */ 2870 acct_update_integrals(p); 2871 } 2872 2873 /* 2874 * Account guest cpu time to a process. 2875 * @p: the process that the cpu time gets accounted to 2876 * @cputime: the cpu time spent in virtual machine since the last update 2877 * @cputime_scaled: cputime scaled by cpu frequency 2878 */ 2879 static void account_guest_time(struct task_struct *p, cputime_t cputime, 2880 cputime_t cputime_scaled) 2881 { 2882 u64 *cpustat = kcpustat_this_cpu->cpustat; 2883 2884 /* Add guest time to process. */ 2885 p->utime += cputime; 2886 p->utimescaled += cputime_scaled; 2887 account_group_user_time(p, cputime); 2888 p->gtime += cputime; 2889 2890 /* Add guest time to cpustat. */ 2891 if (TASK_NICE(p) > 0) { 2892 cpustat[CPUTIME_NICE] += (__force u64) cputime; 2893 cpustat[CPUTIME_GUEST_NICE] += (__force u64) cputime; 2894 } else { 2895 cpustat[CPUTIME_USER] += (__force u64) cputime; 2896 cpustat[CPUTIME_GUEST] += (__force u64) cputime; 2897 } 2898 } 2899 2900 /* 2901 * Account system cpu time to a process and desired cpustat field 2902 * @p: the process that the cpu time gets accounted to 2903 * @cputime: the cpu time spent in kernel space since the last update 2904 * @cputime_scaled: cputime scaled by cpu frequency 2905 * @target_cputime64: pointer to cpustat field that has to be updated 2906 */ 2907 static inline 2908 void __account_system_time(struct task_struct *p, cputime_t cputime, 2909 cputime_t cputime_scaled, int index) 2910 { 2911 /* Add system time to process. */ 2912 p->stime += cputime; 2913 p->stimescaled += cputime_scaled; 2914 account_group_system_time(p, cputime); 2915 2916 /* Add system time to cpustat. */ 2917 task_group_account_field(p, index, (__force u64) cputime); 2918 2919 /* Account for system time used */ 2920 acct_update_integrals(p); 2921 } 2922 2923 /* 2924 * Account system cpu time to a process. 2925 * @p: the process that the cpu time gets accounted to 2926 * @hardirq_offset: the offset to subtract from hardirq_count() 2927 * @cputime: the cpu time spent in kernel space since the last update 2928 * @cputime_scaled: cputime scaled by cpu frequency 2929 */ 2930 void account_system_time(struct task_struct *p, int hardirq_offset, 2931 cputime_t cputime, cputime_t cputime_scaled) 2932 { 2933 int index; 2934 2935 if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) { 2936 account_guest_time(p, cputime, cputime_scaled); 2937 return; 2938 } 2939 2940 if (hardirq_count() - hardirq_offset) 2941 index = CPUTIME_IRQ; 2942 else if (in_serving_softirq()) 2943 index = CPUTIME_SOFTIRQ; 2944 else 2945 index = CPUTIME_SYSTEM; 2946 2947 __account_system_time(p, cputime, cputime_scaled, index); 2948 } 2949 2950 /* 2951 * Account for involuntary wait time. 2952 * @cputime: the cpu time spent in involuntary wait 2953 */ 2954 void account_steal_time(cputime_t cputime) 2955 { 2956 u64 *cpustat = kcpustat_this_cpu->cpustat; 2957 2958 cpustat[CPUTIME_STEAL] += (__force u64) cputime; 2959 } 2960 2961 /* 2962 * Account for idle time. 2963 * @cputime: the cpu time spent in idle wait 2964 */ 2965 void account_idle_time(cputime_t cputime) 2966 { 2967 u64 *cpustat = kcpustat_this_cpu->cpustat; 2968 struct rq *rq = this_rq(); 2969 2970 if (atomic_read(&rq->nr_iowait) > 0) 2971 cpustat[CPUTIME_IOWAIT] += (__force u64) cputime; 2972 else 2973 cpustat[CPUTIME_IDLE] += (__force u64) cputime; 2974 } 2975 2976 static __always_inline bool steal_account_process_tick(void) 2977 { 2978 #ifdef CONFIG_PARAVIRT 2979 if (static_key_false(¶virt_steal_enabled)) { 2980 u64 steal, st = 0; 2981 2982 steal = paravirt_steal_clock(smp_processor_id()); 2983 steal -= this_rq()->prev_steal_time; 2984 2985 st = steal_ticks(steal); 2986 this_rq()->prev_steal_time += st * TICK_NSEC; 2987 2988 account_steal_time(st); 2989 return st; 2990 } 2991 #endif 2992 return false; 2993 } 2994 2995 #ifndef CONFIG_VIRT_CPU_ACCOUNTING 2996 2997 #ifdef CONFIG_IRQ_TIME_ACCOUNTING 2998 /* 2999 * Account a tick to a process and cpustat 3000 * @p: the process that the cpu time gets accounted to 3001 * @user_tick: is the tick from userspace 3002 * @rq: the pointer to rq 3003 * 3004 * Tick demultiplexing follows the order 3005 * - pending hardirq update 3006 * - pending softirq update 3007 * - user_time 3008 * - idle_time 3009 * - system time 3010 * - check for guest_time 3011 * - else account as system_time 3012 * 3013 * Check for hardirq is done both for system and user time as there is 3014 * no timer going off while we are on hardirq and hence we may never get an 3015 * opportunity to update it solely in system time. 3016 * p->stime and friends are only updated on system time and not on irq 3017 * softirq as those do not count in task exec_runtime any more. 3018 */ 3019 static void irqtime_account_process_tick(struct task_struct *p, int user_tick, 3020 struct rq *rq) 3021 { 3022 cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy); 3023 u64 *cpustat = kcpustat_this_cpu->cpustat; 3024 3025 if (steal_account_process_tick()) 3026 return; 3027 3028 if (irqtime_account_hi_update()) { 3029 cpustat[CPUTIME_IRQ] += (__force u64) cputime_one_jiffy; 3030 } else if (irqtime_account_si_update()) { 3031 cpustat[CPUTIME_SOFTIRQ] += (__force u64) cputime_one_jiffy; 3032 } else if (this_cpu_ksoftirqd() == p) { 3033 /* 3034 * ksoftirqd time do not get accounted in cpu_softirq_time. 3035 * So, we have to handle it separately here. 3036 * Also, p->stime needs to be updated for ksoftirqd. 3037 */ 3038 __account_system_time(p, cputime_one_jiffy, one_jiffy_scaled, 3039 CPUTIME_SOFTIRQ); 3040 } else if (user_tick) { 3041 account_user_time(p, cputime_one_jiffy, one_jiffy_scaled); 3042 } else if (p == rq->idle) { 3043 account_idle_time(cputime_one_jiffy); 3044 } else if (p->flags & PF_VCPU) { /* System time or guest time */ 3045 account_guest_time(p, cputime_one_jiffy, one_jiffy_scaled); 3046 } else { 3047 __account_system_time(p, cputime_one_jiffy, one_jiffy_scaled, 3048 CPUTIME_SYSTEM); 3049 } 3050 } 3051 3052 static void irqtime_account_idle_ticks(int ticks) 3053 { 3054 int i; 3055 struct rq *rq = this_rq(); 3056 3057 for (i = 0; i < ticks; i++) 3058 irqtime_account_process_tick(current, 0, rq); 3059 } 3060 #else /* CONFIG_IRQ_TIME_ACCOUNTING */ 3061 static void irqtime_account_idle_ticks(int ticks) {} 3062 static void irqtime_account_process_tick(struct task_struct *p, int user_tick, 3063 struct rq *rq) {} 3064 #endif /* CONFIG_IRQ_TIME_ACCOUNTING */ 3065 3066 /* 3067 * Account a single tick of cpu time. 3068 * @p: the process that the cpu time gets accounted to 3069 * @user_tick: indicates if the tick is a user or a system tick 3070 */ 3071 void account_process_tick(struct task_struct *p, int user_tick) 3072 { 3073 cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy); 3074 struct rq *rq = this_rq(); 3075 3076 if (sched_clock_irqtime) { 3077 irqtime_account_process_tick(p, user_tick, rq); 3078 return; 3079 } 3080 3081 if (steal_account_process_tick()) 3082 return; 3083 3084 if (user_tick) 3085 account_user_time(p, cputime_one_jiffy, one_jiffy_scaled); 3086 else if ((p != rq->idle) || (irq_count() != HARDIRQ_OFFSET)) 3087 account_system_time(p, HARDIRQ_OFFSET, cputime_one_jiffy, 3088 one_jiffy_scaled); 3089 else 3090 account_idle_time(cputime_one_jiffy); 3091 } 3092 3093 /* 3094 * Account multiple ticks of steal time. 3095 * @p: the process from which the cpu time has been stolen 3096 * @ticks: number of stolen ticks 3097 */ 3098 void account_steal_ticks(unsigned long ticks) 3099 { 3100 account_steal_time(jiffies_to_cputime(ticks)); 3101 } 3102 3103 /* 3104 * Account multiple ticks of idle time. 3105 * @ticks: number of stolen ticks 3106 */ 3107 void account_idle_ticks(unsigned long ticks) 3108 { 3109 3110 if (sched_clock_irqtime) { 3111 irqtime_account_idle_ticks(ticks); 3112 return; 3113 } 3114 3115 account_idle_time(jiffies_to_cputime(ticks)); 3116 } 3117 3118 #endif 3119 3120 /* 3121 * Use precise platform statistics if available: 3122 */ 3123 #ifdef CONFIG_VIRT_CPU_ACCOUNTING 3124 void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st) 3125 { 3126 *ut = p->utime; 3127 *st = p->stime; 3128 } 3129 3130 void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st) 3131 { 3132 struct task_cputime cputime; 3133 3134 thread_group_cputime(p, &cputime); 3135 3136 *ut = cputime.utime; 3137 *st = cputime.stime; 3138 } 3139 #else 3140 3141 #ifndef nsecs_to_cputime 3142 # define nsecs_to_cputime(__nsecs) nsecs_to_jiffies(__nsecs) 3143 #endif 3144 3145 static cputime_t scale_utime(cputime_t utime, cputime_t rtime, cputime_t total) 3146 { 3147 u64 temp = (__force u64) rtime; 3148 3149 temp *= (__force u64) utime; 3150 3151 if (sizeof(cputime_t) == 4) 3152 temp = div_u64(temp, (__force u32) total); 3153 else 3154 temp = div64_u64(temp, (__force u64) total); 3155 3156 return (__force cputime_t) temp; 3157 } 3158 3159 void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st) 3160 { 3161 cputime_t rtime, utime = p->utime, total = utime + p->stime; 3162 3163 /* 3164 * Use CFS's precise accounting: 3165 */ 3166 rtime = nsecs_to_cputime(p->se.sum_exec_runtime); 3167 3168 if (total) 3169 utime = scale_utime(utime, rtime, total); 3170 else 3171 utime = rtime; 3172 3173 /* 3174 * Compare with previous values, to keep monotonicity: 3175 */ 3176 p->prev_utime = max(p->prev_utime, utime); 3177 p->prev_stime = max(p->prev_stime, rtime - p->prev_utime); 3178 3179 *ut = p->prev_utime; 3180 *st = p->prev_stime; 3181 } 3182 3183 /* 3184 * Must be called with siglock held. 3185 */ 3186 void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st) 3187 { 3188 struct signal_struct *sig = p->signal; 3189 struct task_cputime cputime; 3190 cputime_t rtime, utime, total; 3191 3192 thread_group_cputime(p, &cputime); 3193 3194 total = cputime.utime + cputime.stime; 3195 rtime = nsecs_to_cputime(cputime.sum_exec_runtime); 3196 3197 if (total) 3198 utime = scale_utime(cputime.utime, rtime, total); 3199 else 3200 utime = rtime; 3201 3202 sig->prev_utime = max(sig->prev_utime, utime); 3203 sig->prev_stime = max(sig->prev_stime, rtime - sig->prev_utime); 3204 3205 *ut = sig->prev_utime; 3206 *st = sig->prev_stime; 3207 } 3208 #endif 3209 3210 /* 3211 * This function gets called by the timer code, with HZ frequency. 3212 * We call it with interrupts disabled. 3213 */ 3214 void scheduler_tick(void) 3215 { 3216 int cpu = smp_processor_id(); 3217 struct rq *rq = cpu_rq(cpu); 3218 struct task_struct *curr = rq->curr; 3219 3220 sched_clock_tick(); 3221 3222 raw_spin_lock(&rq->lock); 3223 update_rq_clock(rq); 3224 update_cpu_load_active(rq); 3225 curr->sched_class->task_tick(rq, curr, 0); 3226 raw_spin_unlock(&rq->lock); 3227 3228 perf_event_task_tick(); 3229 3230 #ifdef CONFIG_SMP 3231 rq->idle_balance = idle_cpu(cpu); 3232 trigger_load_balance(rq, cpu); 3233 #endif 3234 } 3235 3236 notrace unsigned long get_parent_ip(unsigned long addr) 3237 { 3238 if (in_lock_functions(addr)) { 3239 addr = CALLER_ADDR2; 3240 if (in_lock_functions(addr)) 3241 addr = CALLER_ADDR3; 3242 } 3243 return addr; 3244 } 3245 3246 #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \ 3247 defined(CONFIG_PREEMPT_TRACER)) 3248 3249 void __kprobes add_preempt_count(int val) 3250 { 3251 #ifdef CONFIG_DEBUG_PREEMPT 3252 /* 3253 * Underflow? 3254 */ 3255 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0))) 3256 return; 3257 #endif 3258 preempt_count() += val; 3259 #ifdef CONFIG_DEBUG_PREEMPT 3260 /* 3261 * Spinlock count overflowing soon? 3262 */ 3263 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >= 3264 PREEMPT_MASK - 10); 3265 #endif 3266 if (preempt_count() == val) 3267 trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1)); 3268 } 3269 EXPORT_SYMBOL(add_preempt_count); 3270 3271 void __kprobes sub_preempt_count(int val) 3272 { 3273 #ifdef CONFIG_DEBUG_PREEMPT 3274 /* 3275 * Underflow? 3276 */ 3277 if (DEBUG_LOCKS_WARN_ON(val > preempt_count())) 3278 return; 3279 /* 3280 * Is the spinlock portion underflowing? 3281 */ 3282 if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) && 3283 !(preempt_count() & PREEMPT_MASK))) 3284 return; 3285 #endif 3286 3287 if (preempt_count() == val) 3288 trace_preempt_on(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1)); 3289 preempt_count() -= val; 3290 } 3291 EXPORT_SYMBOL(sub_preempt_count); 3292 3293 #endif 3294 3295 /* 3296 * Print scheduling while atomic bug: 3297 */ 3298 static noinline void __schedule_bug(struct task_struct *prev) 3299 { 3300 if (oops_in_progress) 3301 return; 3302 3303 printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n", 3304 prev->comm, prev->pid, preempt_count()); 3305 3306 debug_show_held_locks(prev); 3307 print_modules(); 3308 if (irqs_disabled()) 3309 print_irqtrace_events(prev); 3310 dump_stack(); 3311 add_taint(TAINT_WARN); 3312 } 3313 3314 /* 3315 * Various schedule()-time debugging checks and statistics: 3316 */ 3317 static inline void schedule_debug(struct task_struct *prev) 3318 { 3319 /* 3320 * Test if we are atomic. Since do_exit() needs to call into 3321 * schedule() atomically, we ignore that path for now. 3322 * Otherwise, whine if we are scheduling when we should not be. 3323 */ 3324 if (unlikely(in_atomic_preempt_off() && !prev->exit_state)) 3325 __schedule_bug(prev); 3326 rcu_sleep_check(); 3327 3328 profile_hit(SCHED_PROFILING, __builtin_return_address(0)); 3329 3330 schedstat_inc(this_rq(), sched_count); 3331 } 3332 3333 static void put_prev_task(struct rq *rq, struct task_struct *prev) 3334 { 3335 if (prev->on_rq || rq->skip_clock_update < 0) 3336 update_rq_clock(rq); 3337 prev->sched_class->put_prev_task(rq, prev); 3338 } 3339 3340 /* 3341 * Pick up the highest-prio task: 3342 */ 3343 static inline struct task_struct * 3344 pick_next_task(struct rq *rq) 3345 { 3346 const struct sched_class *class; 3347 struct task_struct *p; 3348 3349 /* 3350 * Optimization: we know that if all tasks are in 3351 * the fair class we can call that function directly: 3352 */ 3353 if (likely(rq->nr_running == rq->cfs.h_nr_running)) { 3354 p = fair_sched_class.pick_next_task(rq); 3355 if (likely(p)) 3356 return p; 3357 } 3358 3359 for_each_class(class) { 3360 p = class->pick_next_task(rq); 3361 if (p) 3362 return p; 3363 } 3364 3365 BUG(); /* the idle class will always have a runnable task */ 3366 } 3367 3368 /* 3369 * __schedule() is the main scheduler function. 3370 */ 3371 static void __sched __schedule(void) 3372 { 3373 struct task_struct *prev, *next; 3374 unsigned long *switch_count; 3375 struct rq *rq; 3376 int cpu; 3377 3378 need_resched: 3379 preempt_disable(); 3380 cpu = smp_processor_id(); 3381 rq = cpu_rq(cpu); 3382 rcu_note_context_switch(cpu); 3383 prev = rq->curr; 3384 3385 schedule_debug(prev); 3386 3387 if (sched_feat(HRTICK)) 3388 hrtick_clear(rq); 3389 3390 raw_spin_lock_irq(&rq->lock); 3391 3392 switch_count = &prev->nivcsw; 3393 if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) { 3394 if (unlikely(signal_pending_state(prev->state, prev))) { 3395 prev->state = TASK_RUNNING; 3396 } else { 3397 deactivate_task(rq, prev, DEQUEUE_SLEEP); 3398 prev->on_rq = 0; 3399 3400 /* 3401 * If a worker went to sleep, notify and ask workqueue 3402 * whether it wants to wake up a task to maintain 3403 * concurrency. 3404 */ 3405 if (prev->flags & PF_WQ_WORKER) { 3406 struct task_struct *to_wakeup; 3407 3408 to_wakeup = wq_worker_sleeping(prev, cpu); 3409 if (to_wakeup) 3410 try_to_wake_up_local(to_wakeup); 3411 } 3412 } 3413 switch_count = &prev->nvcsw; 3414 } 3415 3416 pre_schedule(rq, prev); 3417 3418 if (unlikely(!rq->nr_running)) 3419 idle_balance(cpu, rq); 3420 3421 put_prev_task(rq, prev); 3422 next = pick_next_task(rq); 3423 clear_tsk_need_resched(prev); 3424 rq->skip_clock_update = 0; 3425 3426 if (likely(prev != next)) { 3427 rq->nr_switches++; 3428 rq->curr = next; 3429 ++*switch_count; 3430 3431 context_switch(rq, prev, next); /* unlocks the rq */ 3432 /* 3433 * The context switch have flipped the stack from under us 3434 * and restored the local variables which were saved when 3435 * this task called schedule() in the past. prev == current 3436 * is still correct, but it can be moved to another cpu/rq. 3437 */ 3438 cpu = smp_processor_id(); 3439 rq = cpu_rq(cpu); 3440 } else 3441 raw_spin_unlock_irq(&rq->lock); 3442 3443 post_schedule(rq); 3444 3445 sched_preempt_enable_no_resched(); 3446 if (need_resched()) 3447 goto need_resched; 3448 } 3449 3450 static inline void sched_submit_work(struct task_struct *tsk) 3451 { 3452 if (!tsk->state || tsk_is_pi_blocked(tsk)) 3453 return; 3454 /* 3455 * If we are going to sleep and we have plugged IO queued, 3456 * make sure to submit it to avoid deadlocks. 3457 */ 3458 if (blk_needs_flush_plug(tsk)) 3459 blk_schedule_flush_plug(tsk); 3460 } 3461 3462 asmlinkage void __sched schedule(void) 3463 { 3464 struct task_struct *tsk = current; 3465 3466 sched_submit_work(tsk); 3467 __schedule(); 3468 } 3469 EXPORT_SYMBOL(schedule); 3470 3471 /** 3472 * schedule_preempt_disabled - called with preemption disabled 3473 * 3474 * Returns with preemption disabled. Note: preempt_count must be 1 3475 */ 3476 void __sched schedule_preempt_disabled(void) 3477 { 3478 sched_preempt_enable_no_resched(); 3479 schedule(); 3480 preempt_disable(); 3481 } 3482 3483 #ifdef CONFIG_MUTEX_SPIN_ON_OWNER 3484 3485 static inline bool owner_running(struct mutex *lock, struct task_struct *owner) 3486 { 3487 if (lock->owner != owner) 3488 return false; 3489 3490 /* 3491 * Ensure we emit the owner->on_cpu, dereference _after_ checking 3492 * lock->owner still matches owner, if that fails, owner might 3493 * point to free()d memory, if it still matches, the rcu_read_lock() 3494 * ensures the memory stays valid. 3495 */ 3496 barrier(); 3497 3498 return owner->on_cpu; 3499 } 3500 3501 /* 3502 * Look out! "owner" is an entirely speculative pointer 3503 * access and not reliable. 3504 */ 3505 int mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner) 3506 { 3507 if (!sched_feat(OWNER_SPIN)) 3508 return 0; 3509 3510 rcu_read_lock(); 3511 while (owner_running(lock, owner)) { 3512 if (need_resched()) 3513 break; 3514 3515 arch_mutex_cpu_relax(); 3516 } 3517 rcu_read_unlock(); 3518 3519 /* 3520 * We break out the loop above on need_resched() and when the 3521 * owner changed, which is a sign for heavy contention. Return 3522 * success only when lock->owner is NULL. 3523 */ 3524 return lock->owner == NULL; 3525 } 3526 #endif 3527 3528 #ifdef CONFIG_PREEMPT 3529 /* 3530 * this is the entry point to schedule() from in-kernel preemption 3531 * off of preempt_enable. Kernel preemptions off return from interrupt 3532 * occur there and call schedule directly. 3533 */ 3534 asmlinkage void __sched notrace preempt_schedule(void) 3535 { 3536 struct thread_info *ti = current_thread_info(); 3537 3538 /* 3539 * If there is a non-zero preempt_count or interrupts are disabled, 3540 * we do not want to preempt the current task. Just return.. 3541 */ 3542 if (likely(ti->preempt_count || irqs_disabled())) 3543 return; 3544 3545 do { 3546 add_preempt_count_notrace(PREEMPT_ACTIVE); 3547 __schedule(); 3548 sub_preempt_count_notrace(PREEMPT_ACTIVE); 3549 3550 /* 3551 * Check again in case we missed a preemption opportunity 3552 * between schedule and now. 3553 */ 3554 barrier(); 3555 } while (need_resched()); 3556 } 3557 EXPORT_SYMBOL(preempt_schedule); 3558 3559 /* 3560 * this is the entry point to schedule() from kernel preemption 3561 * off of irq context. 3562 * Note, that this is called and return with irqs disabled. This will 3563 * protect us against recursive calling from irq. 3564 */ 3565 asmlinkage void __sched preempt_schedule_irq(void) 3566 { 3567 struct thread_info *ti = current_thread_info(); 3568 3569 /* Catch callers which need to be fixed */ 3570 BUG_ON(ti->preempt_count || !irqs_disabled()); 3571 3572 do { 3573 add_preempt_count(PREEMPT_ACTIVE); 3574 local_irq_enable(); 3575 __schedule(); 3576 local_irq_disable(); 3577 sub_preempt_count(PREEMPT_ACTIVE); 3578 3579 /* 3580 * Check again in case we missed a preemption opportunity 3581 * between schedule and now. 3582 */ 3583 barrier(); 3584 } while (need_resched()); 3585 } 3586 3587 #endif /* CONFIG_PREEMPT */ 3588 3589 int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags, 3590 void *key) 3591 { 3592 return try_to_wake_up(curr->private, mode, wake_flags); 3593 } 3594 EXPORT_SYMBOL(default_wake_function); 3595 3596 /* 3597 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just 3598 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve 3599 * number) then we wake all the non-exclusive tasks and one exclusive task. 3600 * 3601 * There are circumstances in which we can try to wake a task which has already 3602 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns 3603 * zero in this (rare) case, and we handle it by continuing to scan the queue. 3604 */ 3605 static void __wake_up_common(wait_queue_head_t *q, unsigned int mode, 3606 int nr_exclusive, int wake_flags, void *key) 3607 { 3608 wait_queue_t *curr, *next; 3609 3610 list_for_each_entry_safe(curr, next, &q->task_list, task_list) { 3611 unsigned flags = curr->flags; 3612 3613 if (curr->func(curr, mode, wake_flags, key) && 3614 (flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive) 3615 break; 3616 } 3617 } 3618 3619 /** 3620 * __wake_up - wake up threads blocked on a waitqueue. 3621 * @q: the waitqueue 3622 * @mode: which threads 3623 * @nr_exclusive: how many wake-one or wake-many threads to wake up 3624 * @key: is directly passed to the wakeup function 3625 * 3626 * It may be assumed that this function implies a write memory barrier before 3627 * changing the task state if and only if any tasks are woken up. 3628 */ 3629 void __wake_up(wait_queue_head_t *q, unsigned int mode, 3630 int nr_exclusive, void *key) 3631 { 3632 unsigned long flags; 3633 3634 spin_lock_irqsave(&q->lock, flags); 3635 __wake_up_common(q, mode, nr_exclusive, 0, key); 3636 spin_unlock_irqrestore(&q->lock, flags); 3637 } 3638 EXPORT_SYMBOL(__wake_up); 3639 3640 /* 3641 * Same as __wake_up but called with the spinlock in wait_queue_head_t held. 3642 */ 3643 void __wake_up_locked(wait_queue_head_t *q, unsigned int mode, int nr) 3644 { 3645 __wake_up_common(q, mode, nr, 0, NULL); 3646 } 3647 EXPORT_SYMBOL_GPL(__wake_up_locked); 3648 3649 void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key) 3650 { 3651 __wake_up_common(q, mode, 1, 0, key); 3652 } 3653 EXPORT_SYMBOL_GPL(__wake_up_locked_key); 3654 3655 /** 3656 * __wake_up_sync_key - wake up threads blocked on a waitqueue. 3657 * @q: the waitqueue 3658 * @mode: which threads 3659 * @nr_exclusive: how many wake-one or wake-many threads to wake up 3660 * @key: opaque value to be passed to wakeup targets 3661 * 3662 * The sync wakeup differs that the waker knows that it will schedule 3663 * away soon, so while the target thread will be woken up, it will not 3664 * be migrated to another CPU - ie. the two threads are 'synchronized' 3665 * with each other. This can prevent needless bouncing between CPUs. 3666 * 3667 * On UP it can prevent extra preemption. 3668 * 3669 * It may be assumed that this function implies a write memory barrier before 3670 * changing the task state if and only if any tasks are woken up. 3671 */ 3672 void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode, 3673 int nr_exclusive, void *key) 3674 { 3675 unsigned long flags; 3676 int wake_flags = WF_SYNC; 3677 3678 if (unlikely(!q)) 3679 return; 3680 3681 if (unlikely(!nr_exclusive)) 3682 wake_flags = 0; 3683 3684 spin_lock_irqsave(&q->lock, flags); 3685 __wake_up_common(q, mode, nr_exclusive, wake_flags, key); 3686 spin_unlock_irqrestore(&q->lock, flags); 3687 } 3688 EXPORT_SYMBOL_GPL(__wake_up_sync_key); 3689 3690 /* 3691 * __wake_up_sync - see __wake_up_sync_key() 3692 */ 3693 void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive) 3694 { 3695 __wake_up_sync_key(q, mode, nr_exclusive, NULL); 3696 } 3697 EXPORT_SYMBOL_GPL(__wake_up_sync); /* For internal use only */ 3698 3699 /** 3700 * complete: - signals a single thread waiting on this completion 3701 * @x: holds the state of this particular completion 3702 * 3703 * This will wake up a single thread waiting on this completion. Threads will be 3704 * awakened in the same order in which they were queued. 3705 * 3706 * See also complete_all(), wait_for_completion() and related routines. 3707 * 3708 * It may be assumed that this function implies a write memory barrier before 3709 * changing the task state if and only if any tasks are woken up. 3710 */ 3711 void complete(struct completion *x) 3712 { 3713 unsigned long flags; 3714 3715 spin_lock_irqsave(&x->wait.lock, flags); 3716 x->done++; 3717 __wake_up_common(&x->wait, TASK_NORMAL, 1, 0, NULL); 3718 spin_unlock_irqrestore(&x->wait.lock, flags); 3719 } 3720 EXPORT_SYMBOL(complete); 3721 3722 /** 3723 * complete_all: - signals all threads waiting on this completion 3724 * @x: holds the state of this particular completion 3725 * 3726 * This will wake up all threads waiting on this particular completion event. 3727 * 3728 * It may be assumed that this function implies a write memory barrier before 3729 * changing the task state if and only if any tasks are woken up. 3730 */ 3731 void complete_all(struct completion *x) 3732 { 3733 unsigned long flags; 3734 3735 spin_lock_irqsave(&x->wait.lock, flags); 3736 x->done += UINT_MAX/2; 3737 __wake_up_common(&x->wait, TASK_NORMAL, 0, 0, NULL); 3738 spin_unlock_irqrestore(&x->wait.lock, flags); 3739 } 3740 EXPORT_SYMBOL(complete_all); 3741 3742 static inline long __sched 3743 do_wait_for_common(struct completion *x, long timeout, int state) 3744 { 3745 if (!x->done) { 3746 DECLARE_WAITQUEUE(wait, current); 3747 3748 __add_wait_queue_tail_exclusive(&x->wait, &wait); 3749 do { 3750 if (signal_pending_state(state, current)) { 3751 timeout = -ERESTARTSYS; 3752 break; 3753 } 3754 __set_current_state(state); 3755 spin_unlock_irq(&x->wait.lock); 3756 timeout = schedule_timeout(timeout); 3757 spin_lock_irq(&x->wait.lock); 3758 } while (!x->done && timeout); 3759 __remove_wait_queue(&x->wait, &wait); 3760 if (!x->done) 3761 return timeout; 3762 } 3763 x->done--; 3764 return timeout ?: 1; 3765 } 3766 3767 static long __sched 3768 wait_for_common(struct completion *x, long timeout, int state) 3769 { 3770 might_sleep(); 3771 3772 spin_lock_irq(&x->wait.lock); 3773 timeout = do_wait_for_common(x, timeout, state); 3774 spin_unlock_irq(&x->wait.lock); 3775 return timeout; 3776 } 3777 3778 /** 3779 * wait_for_completion: - waits for completion of a task 3780 * @x: holds the state of this particular completion 3781 * 3782 * This waits to be signaled for completion of a specific task. It is NOT 3783 * interruptible and there is no timeout. 3784 * 3785 * See also similar routines (i.e. wait_for_completion_timeout()) with timeout 3786 * and interrupt capability. Also see complete(). 3787 */ 3788 void __sched wait_for_completion(struct completion *x) 3789 { 3790 wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_UNINTERRUPTIBLE); 3791 } 3792 EXPORT_SYMBOL(wait_for_completion); 3793 3794 /** 3795 * wait_for_completion_timeout: - waits for completion of a task (w/timeout) 3796 * @x: holds the state of this particular completion 3797 * @timeout: timeout value in jiffies 3798 * 3799 * This waits for either a completion of a specific task to be signaled or for a 3800 * specified timeout to expire. The timeout is in jiffies. It is not 3801 * interruptible. 3802 * 3803 * The return value is 0 if timed out, and positive (at least 1, or number of 3804 * jiffies left till timeout) if completed. 3805 */ 3806 unsigned long __sched 3807 wait_for_completion_timeout(struct completion *x, unsigned long timeout) 3808 { 3809 return wait_for_common(x, timeout, TASK_UNINTERRUPTIBLE); 3810 } 3811 EXPORT_SYMBOL(wait_for_completion_timeout); 3812 3813 /** 3814 * wait_for_completion_interruptible: - waits for completion of a task (w/intr) 3815 * @x: holds the state of this particular completion 3816 * 3817 * This waits for completion of a specific task to be signaled. It is 3818 * interruptible. 3819 * 3820 * The return value is -ERESTARTSYS if interrupted, 0 if completed. 3821 */ 3822 int __sched wait_for_completion_interruptible(struct completion *x) 3823 { 3824 long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_INTERRUPTIBLE); 3825 if (t == -ERESTARTSYS) 3826 return t; 3827 return 0; 3828 } 3829 EXPORT_SYMBOL(wait_for_completion_interruptible); 3830 3831 /** 3832 * wait_for_completion_interruptible_timeout: - waits for completion (w/(to,intr)) 3833 * @x: holds the state of this particular completion 3834 * @timeout: timeout value in jiffies 3835 * 3836 * This waits for either a completion of a specific task to be signaled or for a 3837 * specified timeout to expire. It is interruptible. The timeout is in jiffies. 3838 * 3839 * The return value is -ERESTARTSYS if interrupted, 0 if timed out, 3840 * positive (at least 1, or number of jiffies left till timeout) if completed. 3841 */ 3842 long __sched 3843 wait_for_completion_interruptible_timeout(struct completion *x, 3844 unsigned long timeout) 3845 { 3846 return wait_for_common(x, timeout, TASK_INTERRUPTIBLE); 3847 } 3848 EXPORT_SYMBOL(wait_for_completion_interruptible_timeout); 3849 3850 /** 3851 * wait_for_completion_killable: - waits for completion of a task (killable) 3852 * @x: holds the state of this particular completion 3853 * 3854 * This waits to be signaled for completion of a specific task. It can be 3855 * interrupted by a kill signal. 3856 * 3857 * The return value is -ERESTARTSYS if interrupted, 0 if completed. 3858 */ 3859 int __sched wait_for_completion_killable(struct completion *x) 3860 { 3861 long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_KILLABLE); 3862 if (t == -ERESTARTSYS) 3863 return t; 3864 return 0; 3865 } 3866 EXPORT_SYMBOL(wait_for_completion_killable); 3867 3868 /** 3869 * wait_for_completion_killable_timeout: - waits for completion of a task (w/(to,killable)) 3870 * @x: holds the state of this particular completion 3871 * @timeout: timeout value in jiffies 3872 * 3873 * This waits for either a completion of a specific task to be 3874 * signaled or for a specified timeout to expire. It can be 3875 * interrupted by a kill signal. The timeout is in jiffies. 3876 * 3877 * The return value is -ERESTARTSYS if interrupted, 0 if timed out, 3878 * positive (at least 1, or number of jiffies left till timeout) if completed. 3879 */ 3880 long __sched 3881 wait_for_completion_killable_timeout(struct completion *x, 3882 unsigned long timeout) 3883 { 3884 return wait_for_common(x, timeout, TASK_KILLABLE); 3885 } 3886 EXPORT_SYMBOL(wait_for_completion_killable_timeout); 3887 3888 /** 3889 * try_wait_for_completion - try to decrement a completion without blocking 3890 * @x: completion structure 3891 * 3892 * Returns: 0 if a decrement cannot be done without blocking 3893 * 1 if a decrement succeeded. 3894 * 3895 * If a completion is being used as a counting completion, 3896 * attempt to decrement the counter without blocking. This 3897 * enables us to avoid waiting if the resource the completion 3898 * is protecting is not available. 3899 */ 3900 bool try_wait_for_completion(struct completion *x) 3901 { 3902 unsigned long flags; 3903 int ret = 1; 3904 3905 spin_lock_irqsave(&x->wait.lock, flags); 3906 if (!x->done) 3907 ret = 0; 3908 else 3909 x->done--; 3910 spin_unlock_irqrestore(&x->wait.lock, flags); 3911 return ret; 3912 } 3913 EXPORT_SYMBOL(try_wait_for_completion); 3914 3915 /** 3916 * completion_done - Test to see if a completion has any waiters 3917 * @x: completion structure 3918 * 3919 * Returns: 0 if there are waiters (wait_for_completion() in progress) 3920 * 1 if there are no waiters. 3921 * 3922 */ 3923 bool completion_done(struct completion *x) 3924 { 3925 unsigned long flags; 3926 int ret = 1; 3927 3928 spin_lock_irqsave(&x->wait.lock, flags); 3929 if (!x->done) 3930 ret = 0; 3931 spin_unlock_irqrestore(&x->wait.lock, flags); 3932 return ret; 3933 } 3934 EXPORT_SYMBOL(completion_done); 3935 3936 static long __sched 3937 sleep_on_common(wait_queue_head_t *q, int state, long timeout) 3938 { 3939 unsigned long flags; 3940 wait_queue_t wait; 3941 3942 init_waitqueue_entry(&wait, current); 3943 3944 __set_current_state(state); 3945 3946 spin_lock_irqsave(&q->lock, flags); 3947 __add_wait_queue(q, &wait); 3948 spin_unlock(&q->lock); 3949 timeout = schedule_timeout(timeout); 3950 spin_lock_irq(&q->lock); 3951 __remove_wait_queue(q, &wait); 3952 spin_unlock_irqrestore(&q->lock, flags); 3953 3954 return timeout; 3955 } 3956 3957 void __sched interruptible_sleep_on(wait_queue_head_t *q) 3958 { 3959 sleep_on_common(q, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); 3960 } 3961 EXPORT_SYMBOL(interruptible_sleep_on); 3962 3963 long __sched 3964 interruptible_sleep_on_timeout(wait_queue_head_t *q, long timeout) 3965 { 3966 return sleep_on_common(q, TASK_INTERRUPTIBLE, timeout); 3967 } 3968 EXPORT_SYMBOL(interruptible_sleep_on_timeout); 3969 3970 void __sched sleep_on(wait_queue_head_t *q) 3971 { 3972 sleep_on_common(q, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); 3973 } 3974 EXPORT_SYMBOL(sleep_on); 3975 3976 long __sched sleep_on_timeout(wait_queue_head_t *q, long timeout) 3977 { 3978 return sleep_on_common(q, TASK_UNINTERRUPTIBLE, timeout); 3979 } 3980 EXPORT_SYMBOL(sleep_on_timeout); 3981 3982 #ifdef CONFIG_RT_MUTEXES 3983 3984 /* 3985 * rt_mutex_setprio - set the current priority of a task 3986 * @p: task 3987 * @prio: prio value (kernel-internal form) 3988 * 3989 * This function changes the 'effective' priority of a task. It does 3990 * not touch ->normal_prio like __setscheduler(). 3991 * 3992 * Used by the rt_mutex code to implement priority inheritance logic. 3993 */ 3994 void rt_mutex_setprio(struct task_struct *p, int prio) 3995 { 3996 int oldprio, on_rq, running; 3997 struct rq *rq; 3998 const struct sched_class *prev_class; 3999 4000 BUG_ON(prio < 0 || prio > MAX_PRIO); 4001 4002 rq = __task_rq_lock(p); 4003 4004 /* 4005 * Idle task boosting is a nono in general. There is one 4006 * exception, when PREEMPT_RT and NOHZ is active: 4007 * 4008 * The idle task calls get_next_timer_interrupt() and holds 4009 * the timer wheel base->lock on the CPU and another CPU wants 4010 * to access the timer (probably to cancel it). We can safely 4011 * ignore the boosting request, as the idle CPU runs this code 4012 * with interrupts disabled and will complete the lock 4013 * protected section without being interrupted. So there is no 4014 * real need to boost. 4015 */ 4016 if (unlikely(p == rq->idle)) { 4017 WARN_ON(p != rq->curr); 4018 WARN_ON(p->pi_blocked_on); 4019 goto out_unlock; 4020 } 4021 4022 trace_sched_pi_setprio(p, prio); 4023 oldprio = p->prio; 4024 prev_class = p->sched_class; 4025 on_rq = p->on_rq; 4026 running = task_current(rq, p); 4027 if (on_rq) 4028 dequeue_task(rq, p, 0); 4029 if (running) 4030 p->sched_class->put_prev_task(rq, p); 4031 4032 if (rt_prio(prio)) 4033 p->sched_class = &rt_sched_class; 4034 else 4035 p->sched_class = &fair_sched_class; 4036 4037 p->prio = prio; 4038 4039 if (running) 4040 p->sched_class->set_curr_task(rq); 4041 if (on_rq) 4042 enqueue_task(rq, p, oldprio < prio ? ENQUEUE_HEAD : 0); 4043 4044 check_class_changed(rq, p, prev_class, oldprio); 4045 out_unlock: 4046 __task_rq_unlock(rq); 4047 } 4048 #endif 4049 void set_user_nice(struct task_struct *p, long nice) 4050 { 4051 int old_prio, delta, on_rq; 4052 unsigned long flags; 4053 struct rq *rq; 4054 4055 if (TASK_NICE(p) == nice || nice < -20 || nice > 19) 4056 return; 4057 /* 4058 * We have to be careful, if called from sys_setpriority(), 4059 * the task might be in the middle of scheduling on another CPU. 4060 */ 4061 rq = task_rq_lock(p, &flags); 4062 /* 4063 * The RT priorities are set via sched_setscheduler(), but we still 4064 * allow the 'normal' nice value to be set - but as expected 4065 * it wont have any effect on scheduling until the task is 4066 * SCHED_FIFO/SCHED_RR: 4067 */ 4068 if (task_has_rt_policy(p)) { 4069 p->static_prio = NICE_TO_PRIO(nice); 4070 goto out_unlock; 4071 } 4072 on_rq = p->on_rq; 4073 if (on_rq) 4074 dequeue_task(rq, p, 0); 4075 4076 p->static_prio = NICE_TO_PRIO(nice); 4077 set_load_weight(p); 4078 old_prio = p->prio; 4079 p->prio = effective_prio(p); 4080 delta = p->prio - old_prio; 4081 4082 if (on_rq) { 4083 enqueue_task(rq, p, 0); 4084 /* 4085 * If the task increased its priority or is running and 4086 * lowered its priority, then reschedule its CPU: 4087 */ 4088 if (delta < 0 || (delta > 0 && task_running(rq, p))) 4089 resched_task(rq->curr); 4090 } 4091 out_unlock: 4092 task_rq_unlock(rq, p, &flags); 4093 } 4094 EXPORT_SYMBOL(set_user_nice); 4095 4096 /* 4097 * can_nice - check if a task can reduce its nice value 4098 * @p: task 4099 * @nice: nice value 4100 */ 4101 int can_nice(const struct task_struct *p, const int nice) 4102 { 4103 /* convert nice value [19,-20] to rlimit style value [1,40] */ 4104 int nice_rlim = 20 - nice; 4105 4106 return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) || 4107 capable(CAP_SYS_NICE)); 4108 } 4109 4110 #ifdef __ARCH_WANT_SYS_NICE 4111 4112 /* 4113 * sys_nice - change the priority of the current process. 4114 * @increment: priority increment 4115 * 4116 * sys_setpriority is a more generic, but much slower function that 4117 * does similar things. 4118 */ 4119 SYSCALL_DEFINE1(nice, int, increment) 4120 { 4121 long nice, retval; 4122 4123 /* 4124 * Setpriority might change our priority at the same moment. 4125 * We don't have to worry. Conceptually one call occurs first 4126 * and we have a single winner. 4127 */ 4128 if (increment < -40) 4129 increment = -40; 4130 if (increment > 40) 4131 increment = 40; 4132 4133 nice = TASK_NICE(current) + increment; 4134 if (nice < -20) 4135 nice = -20; 4136 if (nice > 19) 4137 nice = 19; 4138 4139 if (increment < 0 && !can_nice(current, nice)) 4140 return -EPERM; 4141 4142 retval = security_task_setnice(current, nice); 4143 if (retval) 4144 return retval; 4145 4146 set_user_nice(current, nice); 4147 return 0; 4148 } 4149 4150 #endif 4151 4152 /** 4153 * task_prio - return the priority value of a given task. 4154 * @p: the task in question. 4155 * 4156 * This is the priority value as seen by users in /proc. 4157 * RT tasks are offset by -200. Normal tasks are centered 4158 * around 0, value goes from -16 to +15. 4159 */ 4160 int task_prio(const struct task_struct *p) 4161 { 4162 return p->prio - MAX_RT_PRIO; 4163 } 4164 4165 /** 4166 * task_nice - return the nice value of a given task. 4167 * @p: the task in question. 4168 */ 4169 int task_nice(const struct task_struct *p) 4170 { 4171 return TASK_NICE(p); 4172 } 4173 EXPORT_SYMBOL(task_nice); 4174 4175 /** 4176 * idle_cpu - is a given cpu idle currently? 4177 * @cpu: the processor in question. 4178 */ 4179 int idle_cpu(int cpu) 4180 { 4181 struct rq *rq = cpu_rq(cpu); 4182 4183 if (rq->curr != rq->idle) 4184 return 0; 4185 4186 if (rq->nr_running) 4187 return 0; 4188 4189 #ifdef CONFIG_SMP 4190 if (!llist_empty(&rq->wake_list)) 4191 return 0; 4192 #endif 4193 4194 return 1; 4195 } 4196 4197 /** 4198 * idle_task - return the idle task for a given cpu. 4199 * @cpu: the processor in question. 4200 */ 4201 struct task_struct *idle_task(int cpu) 4202 { 4203 return cpu_rq(cpu)->idle; 4204 } 4205 4206 /** 4207 * find_process_by_pid - find a process with a matching PID value. 4208 * @pid: the pid in question. 4209 */ 4210 static struct task_struct *find_process_by_pid(pid_t pid) 4211 { 4212 return pid ? find_task_by_vpid(pid) : current; 4213 } 4214 4215 /* Actually do priority change: must hold rq lock. */ 4216 static void 4217 __setscheduler(struct rq *rq, struct task_struct *p, int policy, int prio) 4218 { 4219 p->policy = policy; 4220 p->rt_priority = prio; 4221 p->normal_prio = normal_prio(p); 4222 /* we are holding p->pi_lock already */ 4223 p->prio = rt_mutex_getprio(p); 4224 if (rt_prio(p->prio)) 4225 p->sched_class = &rt_sched_class; 4226 else 4227 p->sched_class = &fair_sched_class; 4228 set_load_weight(p); 4229 } 4230 4231 /* 4232 * check the target process has a UID that matches the current process's 4233 */ 4234 static bool check_same_owner(struct task_struct *p) 4235 { 4236 const struct cred *cred = current_cred(), *pcred; 4237 bool match; 4238 4239 rcu_read_lock(); 4240 pcred = __task_cred(p); 4241 match = (uid_eq(cred->euid, pcred->euid) || 4242 uid_eq(cred->euid, pcred->uid)); 4243 rcu_read_unlock(); 4244 return match; 4245 } 4246 4247 static int __sched_setscheduler(struct task_struct *p, int policy, 4248 const struct sched_param *param, bool user) 4249 { 4250 int retval, oldprio, oldpolicy = -1, on_rq, running; 4251 unsigned long flags; 4252 const struct sched_class *prev_class; 4253 struct rq *rq; 4254 int reset_on_fork; 4255 4256 /* may grab non-irq protected spin_locks */ 4257 BUG_ON(in_interrupt()); 4258 recheck: 4259 /* double check policy once rq lock held */ 4260 if (policy < 0) { 4261 reset_on_fork = p->sched_reset_on_fork; 4262 policy = oldpolicy = p->policy; 4263 } else { 4264 reset_on_fork = !!(policy & SCHED_RESET_ON_FORK); 4265 policy &= ~SCHED_RESET_ON_FORK; 4266 4267 if (policy != SCHED_FIFO && policy != SCHED_RR && 4268 policy != SCHED_NORMAL && policy != SCHED_BATCH && 4269 policy != SCHED_IDLE) 4270 return -EINVAL; 4271 } 4272 4273 /* 4274 * Valid priorities for SCHED_FIFO and SCHED_RR are 4275 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL, 4276 * SCHED_BATCH and SCHED_IDLE is 0. 4277 */ 4278 if (param->sched_priority < 0 || 4279 (p->mm && param->sched_priority > MAX_USER_RT_PRIO-1) || 4280 (!p->mm && param->sched_priority > MAX_RT_PRIO-1)) 4281 return -EINVAL; 4282 if (rt_policy(policy) != (param->sched_priority != 0)) 4283 return -EINVAL; 4284 4285 /* 4286 * Allow unprivileged RT tasks to decrease priority: 4287 */ 4288 if (user && !capable(CAP_SYS_NICE)) { 4289 if (rt_policy(policy)) { 4290 unsigned long rlim_rtprio = 4291 task_rlimit(p, RLIMIT_RTPRIO); 4292 4293 /* can't set/change the rt policy */ 4294 if (policy != p->policy && !rlim_rtprio) 4295 return -EPERM; 4296 4297 /* can't increase priority */ 4298 if (param->sched_priority > p->rt_priority && 4299 param->sched_priority > rlim_rtprio) 4300 return -EPERM; 4301 } 4302 4303 /* 4304 * Treat SCHED_IDLE as nice 20. Only allow a switch to 4305 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it. 4306 */ 4307 if (p->policy == SCHED_IDLE && policy != SCHED_IDLE) { 4308 if (!can_nice(p, TASK_NICE(p))) 4309 return -EPERM; 4310 } 4311 4312 /* can't change other user's priorities */ 4313 if (!check_same_owner(p)) 4314 return -EPERM; 4315 4316 /* Normal users shall not reset the sched_reset_on_fork flag */ 4317 if (p->sched_reset_on_fork && !reset_on_fork) 4318 return -EPERM; 4319 } 4320 4321 if (user) { 4322 retval = security_task_setscheduler(p); 4323 if (retval) 4324 return retval; 4325 } 4326 4327 /* 4328 * make sure no PI-waiters arrive (or leave) while we are 4329 * changing the priority of the task: 4330 * 4331 * To be able to change p->policy safely, the appropriate 4332 * runqueue lock must be held. 4333 */ 4334 rq = task_rq_lock(p, &flags); 4335 4336 /* 4337 * Changing the policy of the stop threads its a very bad idea 4338 */ 4339 if (p == rq->stop) { 4340 task_rq_unlock(rq, p, &flags); 4341 return -EINVAL; 4342 } 4343 4344 /* 4345 * If not changing anything there's no need to proceed further: 4346 */ 4347 if (unlikely(policy == p->policy && (!rt_policy(policy) || 4348 param->sched_priority == p->rt_priority))) { 4349 task_rq_unlock(rq, p, &flags); 4350 return 0; 4351 } 4352 4353 #ifdef CONFIG_RT_GROUP_SCHED 4354 if (user) { 4355 /* 4356 * Do not allow realtime tasks into groups that have no runtime 4357 * assigned. 4358 */ 4359 if (rt_bandwidth_enabled() && rt_policy(policy) && 4360 task_group(p)->rt_bandwidth.rt_runtime == 0 && 4361 !task_group_is_autogroup(task_group(p))) { 4362 task_rq_unlock(rq, p, &flags); 4363 return -EPERM; 4364 } 4365 } 4366 #endif 4367 4368 /* recheck policy now with rq lock held */ 4369 if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) { 4370 policy = oldpolicy = -1; 4371 task_rq_unlock(rq, p, &flags); 4372 goto recheck; 4373 } 4374 on_rq = p->on_rq; 4375 running = task_current(rq, p); 4376 if (on_rq) 4377 dequeue_task(rq, p, 0); 4378 if (running) 4379 p->sched_class->put_prev_task(rq, p); 4380 4381 p->sched_reset_on_fork = reset_on_fork; 4382 4383 oldprio = p->prio; 4384 prev_class = p->sched_class; 4385 __setscheduler(rq, p, policy, param->sched_priority); 4386 4387 if (running) 4388 p->sched_class->set_curr_task(rq); 4389 if (on_rq) 4390 enqueue_task(rq, p, 0); 4391 4392 check_class_changed(rq, p, prev_class, oldprio); 4393 task_rq_unlock(rq, p, &flags); 4394 4395 rt_mutex_adjust_pi(p); 4396 4397 return 0; 4398 } 4399 4400 /** 4401 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread. 4402 * @p: the task in question. 4403 * @policy: new policy. 4404 * @param: structure containing the new RT priority. 4405 * 4406 * NOTE that the task may be already dead. 4407 */ 4408 int sched_setscheduler(struct task_struct *p, int policy, 4409 const struct sched_param *param) 4410 { 4411 return __sched_setscheduler(p, policy, param, true); 4412 } 4413 EXPORT_SYMBOL_GPL(sched_setscheduler); 4414 4415 /** 4416 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace. 4417 * @p: the task in question. 4418 * @policy: new policy. 4419 * @param: structure containing the new RT priority. 4420 * 4421 * Just like sched_setscheduler, only don't bother checking if the 4422 * current context has permission. For example, this is needed in 4423 * stop_machine(): we create temporary high priority worker threads, 4424 * but our caller might not have that capability. 4425 */ 4426 int sched_setscheduler_nocheck(struct task_struct *p, int policy, 4427 const struct sched_param *param) 4428 { 4429 return __sched_setscheduler(p, policy, param, false); 4430 } 4431 4432 static int 4433 do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param) 4434 { 4435 struct sched_param lparam; 4436 struct task_struct *p; 4437 int retval; 4438 4439 if (!param || pid < 0) 4440 return -EINVAL; 4441 if (copy_from_user(&lparam, param, sizeof(struct sched_param))) 4442 return -EFAULT; 4443 4444 rcu_read_lock(); 4445 retval = -ESRCH; 4446 p = find_process_by_pid(pid); 4447 if (p != NULL) 4448 retval = sched_setscheduler(p, policy, &lparam); 4449 rcu_read_unlock(); 4450 4451 return retval; 4452 } 4453 4454 /** 4455 * sys_sched_setscheduler - set/change the scheduler policy and RT priority 4456 * @pid: the pid in question. 4457 * @policy: new policy. 4458 * @param: structure containing the new RT priority. 4459 */ 4460 SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy, 4461 struct sched_param __user *, param) 4462 { 4463 /* negative values for policy are not valid */ 4464 if (policy < 0) 4465 return -EINVAL; 4466 4467 return do_sched_setscheduler(pid, policy, param); 4468 } 4469 4470 /** 4471 * sys_sched_setparam - set/change the RT priority of a thread 4472 * @pid: the pid in question. 4473 * @param: structure containing the new RT priority. 4474 */ 4475 SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param) 4476 { 4477 return do_sched_setscheduler(pid, -1, param); 4478 } 4479 4480 /** 4481 * sys_sched_getscheduler - get the policy (scheduling class) of a thread 4482 * @pid: the pid in question. 4483 */ 4484 SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid) 4485 { 4486 struct task_struct *p; 4487 int retval; 4488 4489 if (pid < 0) 4490 return -EINVAL; 4491 4492 retval = -ESRCH; 4493 rcu_read_lock(); 4494 p = find_process_by_pid(pid); 4495 if (p) { 4496 retval = security_task_getscheduler(p); 4497 if (!retval) 4498 retval = p->policy 4499 | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0); 4500 } 4501 rcu_read_unlock(); 4502 return retval; 4503 } 4504 4505 /** 4506 * sys_sched_getparam - get the RT priority of a thread 4507 * @pid: the pid in question. 4508 * @param: structure containing the RT priority. 4509 */ 4510 SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param) 4511 { 4512 struct sched_param lp; 4513 struct task_struct *p; 4514 int retval; 4515 4516 if (!param || pid < 0) 4517 return -EINVAL; 4518 4519 rcu_read_lock(); 4520 p = find_process_by_pid(pid); 4521 retval = -ESRCH; 4522 if (!p) 4523 goto out_unlock; 4524 4525 retval = security_task_getscheduler(p); 4526 if (retval) 4527 goto out_unlock; 4528 4529 lp.sched_priority = p->rt_priority; 4530 rcu_read_unlock(); 4531 4532 /* 4533 * This one might sleep, we cannot do it with a spinlock held ... 4534 */ 4535 retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0; 4536 4537 return retval; 4538 4539 out_unlock: 4540 rcu_read_unlock(); 4541 return retval; 4542 } 4543 4544 long sched_setaffinity(pid_t pid, const struct cpumask *in_mask) 4545 { 4546 cpumask_var_t cpus_allowed, new_mask; 4547 struct task_struct *p; 4548 int retval; 4549 4550 get_online_cpus(); 4551 rcu_read_lock(); 4552 4553 p = find_process_by_pid(pid); 4554 if (!p) { 4555 rcu_read_unlock(); 4556 put_online_cpus(); 4557 return -ESRCH; 4558 } 4559 4560 /* Prevent p going away */ 4561 get_task_struct(p); 4562 rcu_read_unlock(); 4563 4564 if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) { 4565 retval = -ENOMEM; 4566 goto out_put_task; 4567 } 4568 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) { 4569 retval = -ENOMEM; 4570 goto out_free_cpus_allowed; 4571 } 4572 retval = -EPERM; 4573 if (!check_same_owner(p) && !ns_capable(task_user_ns(p), CAP_SYS_NICE)) 4574 goto out_unlock; 4575 4576 retval = security_task_setscheduler(p); 4577 if (retval) 4578 goto out_unlock; 4579 4580 cpuset_cpus_allowed(p, cpus_allowed); 4581 cpumask_and(new_mask, in_mask, cpus_allowed); 4582 again: 4583 retval = set_cpus_allowed_ptr(p, new_mask); 4584 4585 if (!retval) { 4586 cpuset_cpus_allowed(p, cpus_allowed); 4587 if (!cpumask_subset(new_mask, cpus_allowed)) { 4588 /* 4589 * We must have raced with a concurrent cpuset 4590 * update. Just reset the cpus_allowed to the 4591 * cpuset's cpus_allowed 4592 */ 4593 cpumask_copy(new_mask, cpus_allowed); 4594 goto again; 4595 } 4596 } 4597 out_unlock: 4598 free_cpumask_var(new_mask); 4599 out_free_cpus_allowed: 4600 free_cpumask_var(cpus_allowed); 4601 out_put_task: 4602 put_task_struct(p); 4603 put_online_cpus(); 4604 return retval; 4605 } 4606 4607 static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len, 4608 struct cpumask *new_mask) 4609 { 4610 if (len < cpumask_size()) 4611 cpumask_clear(new_mask); 4612 else if (len > cpumask_size()) 4613 len = cpumask_size(); 4614 4615 return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0; 4616 } 4617 4618 /** 4619 * sys_sched_setaffinity - set the cpu affinity of a process 4620 * @pid: pid of the process 4621 * @len: length in bytes of the bitmask pointed to by user_mask_ptr 4622 * @user_mask_ptr: user-space pointer to the new cpu mask 4623 */ 4624 SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len, 4625 unsigned long __user *, user_mask_ptr) 4626 { 4627 cpumask_var_t new_mask; 4628 int retval; 4629 4630 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) 4631 return -ENOMEM; 4632 4633 retval = get_user_cpu_mask(user_mask_ptr, len, new_mask); 4634 if (retval == 0) 4635 retval = sched_setaffinity(pid, new_mask); 4636 free_cpumask_var(new_mask); 4637 return retval; 4638 } 4639 4640 long sched_getaffinity(pid_t pid, struct cpumask *mask) 4641 { 4642 struct task_struct *p; 4643 unsigned long flags; 4644 int retval; 4645 4646 get_online_cpus(); 4647 rcu_read_lock(); 4648 4649 retval = -ESRCH; 4650 p = find_process_by_pid(pid); 4651 if (!p) 4652 goto out_unlock; 4653 4654 retval = security_task_getscheduler(p); 4655 if (retval) 4656 goto out_unlock; 4657 4658 raw_spin_lock_irqsave(&p->pi_lock, flags); 4659 cpumask_and(mask, &p->cpus_allowed, cpu_online_mask); 4660 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 4661 4662 out_unlock: 4663 rcu_read_unlock(); 4664 put_online_cpus(); 4665 4666 return retval; 4667 } 4668 4669 /** 4670 * sys_sched_getaffinity - get the cpu affinity of a process 4671 * @pid: pid of the process 4672 * @len: length in bytes of the bitmask pointed to by user_mask_ptr 4673 * @user_mask_ptr: user-space pointer to hold the current cpu mask 4674 */ 4675 SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len, 4676 unsigned long __user *, user_mask_ptr) 4677 { 4678 int ret; 4679 cpumask_var_t mask; 4680 4681 if ((len * BITS_PER_BYTE) < nr_cpu_ids) 4682 return -EINVAL; 4683 if (len & (sizeof(unsigned long)-1)) 4684 return -EINVAL; 4685 4686 if (!alloc_cpumask_var(&mask, GFP_KERNEL)) 4687 return -ENOMEM; 4688 4689 ret = sched_getaffinity(pid, mask); 4690 if (ret == 0) { 4691 size_t retlen = min_t(size_t, len, cpumask_size()); 4692 4693 if (copy_to_user(user_mask_ptr, mask, retlen)) 4694 ret = -EFAULT; 4695 else 4696 ret = retlen; 4697 } 4698 free_cpumask_var(mask); 4699 4700 return ret; 4701 } 4702 4703 /** 4704 * sys_sched_yield - yield the current processor to other threads. 4705 * 4706 * This function yields the current CPU to other tasks. If there are no 4707 * other threads running on this CPU then this function will return. 4708 */ 4709 SYSCALL_DEFINE0(sched_yield) 4710 { 4711 struct rq *rq = this_rq_lock(); 4712 4713 schedstat_inc(rq, yld_count); 4714 current->sched_class->yield_task(rq); 4715 4716 /* 4717 * Since we are going to call schedule() anyway, there's 4718 * no need to preempt or enable interrupts: 4719 */ 4720 __release(rq->lock); 4721 spin_release(&rq->lock.dep_map, 1, _THIS_IP_); 4722 do_raw_spin_unlock(&rq->lock); 4723 sched_preempt_enable_no_resched(); 4724 4725 schedule(); 4726 4727 return 0; 4728 } 4729 4730 static inline int should_resched(void) 4731 { 4732 return need_resched() && !(preempt_count() & PREEMPT_ACTIVE); 4733 } 4734 4735 static void __cond_resched(void) 4736 { 4737 add_preempt_count(PREEMPT_ACTIVE); 4738 __schedule(); 4739 sub_preempt_count(PREEMPT_ACTIVE); 4740 } 4741 4742 int __sched _cond_resched(void) 4743 { 4744 if (should_resched()) { 4745 __cond_resched(); 4746 return 1; 4747 } 4748 return 0; 4749 } 4750 EXPORT_SYMBOL(_cond_resched); 4751 4752 /* 4753 * __cond_resched_lock() - if a reschedule is pending, drop the given lock, 4754 * call schedule, and on return reacquire the lock. 4755 * 4756 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level 4757 * operations here to prevent schedule() from being called twice (once via 4758 * spin_unlock(), once by hand). 4759 */ 4760 int __cond_resched_lock(spinlock_t *lock) 4761 { 4762 int resched = should_resched(); 4763 int ret = 0; 4764 4765 lockdep_assert_held(lock); 4766 4767 if (spin_needbreak(lock) || resched) { 4768 spin_unlock(lock); 4769 if (resched) 4770 __cond_resched(); 4771 else 4772 cpu_relax(); 4773 ret = 1; 4774 spin_lock(lock); 4775 } 4776 return ret; 4777 } 4778 EXPORT_SYMBOL(__cond_resched_lock); 4779 4780 int __sched __cond_resched_softirq(void) 4781 { 4782 BUG_ON(!in_softirq()); 4783 4784 if (should_resched()) { 4785 local_bh_enable(); 4786 __cond_resched(); 4787 local_bh_disable(); 4788 return 1; 4789 } 4790 return 0; 4791 } 4792 EXPORT_SYMBOL(__cond_resched_softirq); 4793 4794 /** 4795 * yield - yield the current processor to other threads. 4796 * 4797 * Do not ever use this function, there's a 99% chance you're doing it wrong. 4798 * 4799 * The scheduler is at all times free to pick the calling task as the most 4800 * eligible task to run, if removing the yield() call from your code breaks 4801 * it, its already broken. 4802 * 4803 * Typical broken usage is: 4804 * 4805 * while (!event) 4806 * yield(); 4807 * 4808 * where one assumes that yield() will let 'the other' process run that will 4809 * make event true. If the current task is a SCHED_FIFO task that will never 4810 * happen. Never use yield() as a progress guarantee!! 4811 * 4812 * If you want to use yield() to wait for something, use wait_event(). 4813 * If you want to use yield() to be 'nice' for others, use cond_resched(). 4814 * If you still want to use yield(), do not! 4815 */ 4816 void __sched yield(void) 4817 { 4818 set_current_state(TASK_RUNNING); 4819 sys_sched_yield(); 4820 } 4821 EXPORT_SYMBOL(yield); 4822 4823 /** 4824 * yield_to - yield the current processor to another thread in 4825 * your thread group, or accelerate that thread toward the 4826 * processor it's on. 4827 * @p: target task 4828 * @preempt: whether task preemption is allowed or not 4829 * 4830 * It's the caller's job to ensure that the target task struct 4831 * can't go away on us before we can do any checks. 4832 * 4833 * Returns true if we indeed boosted the target task. 4834 */ 4835 bool __sched yield_to(struct task_struct *p, bool preempt) 4836 { 4837 struct task_struct *curr = current; 4838 struct rq *rq, *p_rq; 4839 unsigned long flags; 4840 bool yielded = 0; 4841 4842 local_irq_save(flags); 4843 rq = this_rq(); 4844 4845 again: 4846 p_rq = task_rq(p); 4847 double_rq_lock(rq, p_rq); 4848 while (task_rq(p) != p_rq) { 4849 double_rq_unlock(rq, p_rq); 4850 goto again; 4851 } 4852 4853 if (!curr->sched_class->yield_to_task) 4854 goto out; 4855 4856 if (curr->sched_class != p->sched_class) 4857 goto out; 4858 4859 if (task_running(p_rq, p) || p->state) 4860 goto out; 4861 4862 yielded = curr->sched_class->yield_to_task(rq, p, preempt); 4863 if (yielded) { 4864 schedstat_inc(rq, yld_count); 4865 /* 4866 * Make p's CPU reschedule; pick_next_entity takes care of 4867 * fairness. 4868 */ 4869 if (preempt && rq != p_rq) 4870 resched_task(p_rq->curr); 4871 } else { 4872 /* 4873 * We might have set it in task_yield_fair(), but are 4874 * not going to schedule(), so don't want to skip 4875 * the next update. 4876 */ 4877 rq->skip_clock_update = 0; 4878 } 4879 4880 out: 4881 double_rq_unlock(rq, p_rq); 4882 local_irq_restore(flags); 4883 4884 if (yielded) 4885 schedule(); 4886 4887 return yielded; 4888 } 4889 EXPORT_SYMBOL_GPL(yield_to); 4890 4891 /* 4892 * This task is about to go to sleep on IO. Increment rq->nr_iowait so 4893 * that process accounting knows that this is a task in IO wait state. 4894 */ 4895 void __sched io_schedule(void) 4896 { 4897 struct rq *rq = raw_rq(); 4898 4899 delayacct_blkio_start(); 4900 atomic_inc(&rq->nr_iowait); 4901 blk_flush_plug(current); 4902 current->in_iowait = 1; 4903 schedule(); 4904 current->in_iowait = 0; 4905 atomic_dec(&rq->nr_iowait); 4906 delayacct_blkio_end(); 4907 } 4908 EXPORT_SYMBOL(io_schedule); 4909 4910 long __sched io_schedule_timeout(long timeout) 4911 { 4912 struct rq *rq = raw_rq(); 4913 long ret; 4914 4915 delayacct_blkio_start(); 4916 atomic_inc(&rq->nr_iowait); 4917 blk_flush_plug(current); 4918 current->in_iowait = 1; 4919 ret = schedule_timeout(timeout); 4920 current->in_iowait = 0; 4921 atomic_dec(&rq->nr_iowait); 4922 delayacct_blkio_end(); 4923 return ret; 4924 } 4925 4926 /** 4927 * sys_sched_get_priority_max - return maximum RT priority. 4928 * @policy: scheduling class. 4929 * 4930 * this syscall returns the maximum rt_priority that can be used 4931 * by a given scheduling class. 4932 */ 4933 SYSCALL_DEFINE1(sched_get_priority_max, int, policy) 4934 { 4935 int ret = -EINVAL; 4936 4937 switch (policy) { 4938 case SCHED_FIFO: 4939 case SCHED_RR: 4940 ret = MAX_USER_RT_PRIO-1; 4941 break; 4942 case SCHED_NORMAL: 4943 case SCHED_BATCH: 4944 case SCHED_IDLE: 4945 ret = 0; 4946 break; 4947 } 4948 return ret; 4949 } 4950 4951 /** 4952 * sys_sched_get_priority_min - return minimum RT priority. 4953 * @policy: scheduling class. 4954 * 4955 * this syscall returns the minimum rt_priority that can be used 4956 * by a given scheduling class. 4957 */ 4958 SYSCALL_DEFINE1(sched_get_priority_min, int, policy) 4959 { 4960 int ret = -EINVAL; 4961 4962 switch (policy) { 4963 case SCHED_FIFO: 4964 case SCHED_RR: 4965 ret = 1; 4966 break; 4967 case SCHED_NORMAL: 4968 case SCHED_BATCH: 4969 case SCHED_IDLE: 4970 ret = 0; 4971 } 4972 return ret; 4973 } 4974 4975 /** 4976 * sys_sched_rr_get_interval - return the default timeslice of a process. 4977 * @pid: pid of the process. 4978 * @interval: userspace pointer to the timeslice value. 4979 * 4980 * this syscall writes the default timeslice value of a given process 4981 * into the user-space timespec buffer. A value of '0' means infinity. 4982 */ 4983 SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid, 4984 struct timespec __user *, interval) 4985 { 4986 struct task_struct *p; 4987 unsigned int time_slice; 4988 unsigned long flags; 4989 struct rq *rq; 4990 int retval; 4991 struct timespec t; 4992 4993 if (pid < 0) 4994 return -EINVAL; 4995 4996 retval = -ESRCH; 4997 rcu_read_lock(); 4998 p = find_process_by_pid(pid); 4999 if (!p) 5000 goto out_unlock; 5001 5002 retval = security_task_getscheduler(p); 5003 if (retval) 5004 goto out_unlock; 5005 5006 rq = task_rq_lock(p, &flags); 5007 time_slice = p->sched_class->get_rr_interval(rq, p); 5008 task_rq_unlock(rq, p, &flags); 5009 5010 rcu_read_unlock(); 5011 jiffies_to_timespec(time_slice, &t); 5012 retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0; 5013 return retval; 5014 5015 out_unlock: 5016 rcu_read_unlock(); 5017 return retval; 5018 } 5019 5020 static const char stat_nam[] = TASK_STATE_TO_CHAR_STR; 5021 5022 void sched_show_task(struct task_struct *p) 5023 { 5024 unsigned long free = 0; 5025 unsigned state; 5026 5027 state = p->state ? __ffs(p->state) + 1 : 0; 5028 printk(KERN_INFO "%-15.15s %c", p->comm, 5029 state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?'); 5030 #if BITS_PER_LONG == 32 5031 if (state == TASK_RUNNING) 5032 printk(KERN_CONT " running "); 5033 else 5034 printk(KERN_CONT " %08lx ", thread_saved_pc(p)); 5035 #else 5036 if (state == TASK_RUNNING) 5037 printk(KERN_CONT " running task "); 5038 else 5039 printk(KERN_CONT " %016lx ", thread_saved_pc(p)); 5040 #endif 5041 #ifdef CONFIG_DEBUG_STACK_USAGE 5042 free = stack_not_used(p); 5043 #endif 5044 printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free, 5045 task_pid_nr(p), task_pid_nr(rcu_dereference(p->real_parent)), 5046 (unsigned long)task_thread_info(p)->flags); 5047 5048 show_stack(p, NULL); 5049 } 5050 5051 void show_state_filter(unsigned long state_filter) 5052 { 5053 struct task_struct *g, *p; 5054 5055 #if BITS_PER_LONG == 32 5056 printk(KERN_INFO 5057 " task PC stack pid father\n"); 5058 #else 5059 printk(KERN_INFO 5060 " task PC stack pid father\n"); 5061 #endif 5062 rcu_read_lock(); 5063 do_each_thread(g, p) { 5064 /* 5065 * reset the NMI-timeout, listing all files on a slow 5066 * console might take a lot of time: 5067 */ 5068 touch_nmi_watchdog(); 5069 if (!state_filter || (p->state & state_filter)) 5070 sched_show_task(p); 5071 } while_each_thread(g, p); 5072 5073 touch_all_softlockup_watchdogs(); 5074 5075 #ifdef CONFIG_SCHED_DEBUG 5076 sysrq_sched_debug_show(); 5077 #endif 5078 rcu_read_unlock(); 5079 /* 5080 * Only show locks if all tasks are dumped: 5081 */ 5082 if (!state_filter) 5083 debug_show_all_locks(); 5084 } 5085 5086 void __cpuinit init_idle_bootup_task(struct task_struct *idle) 5087 { 5088 idle->sched_class = &idle_sched_class; 5089 } 5090 5091 /** 5092 * init_idle - set up an idle thread for a given CPU 5093 * @idle: task in question 5094 * @cpu: cpu the idle task belongs to 5095 * 5096 * NOTE: this function does not set the idle thread's NEED_RESCHED 5097 * flag, to make booting more robust. 5098 */ 5099 void __cpuinit init_idle(struct task_struct *idle, int cpu) 5100 { 5101 struct rq *rq = cpu_rq(cpu); 5102 unsigned long flags; 5103 5104 raw_spin_lock_irqsave(&rq->lock, flags); 5105 5106 __sched_fork(idle); 5107 idle->state = TASK_RUNNING; 5108 idle->se.exec_start = sched_clock(); 5109 5110 do_set_cpus_allowed(idle, cpumask_of(cpu)); 5111 /* 5112 * We're having a chicken and egg problem, even though we are 5113 * holding rq->lock, the cpu isn't yet set to this cpu so the 5114 * lockdep check in task_group() will fail. 5115 * 5116 * Similar case to sched_fork(). / Alternatively we could 5117 * use task_rq_lock() here and obtain the other rq->lock. 5118 * 5119 * Silence PROVE_RCU 5120 */ 5121 rcu_read_lock(); 5122 __set_task_cpu(idle, cpu); 5123 rcu_read_unlock(); 5124 5125 rq->curr = rq->idle = idle; 5126 #if defined(CONFIG_SMP) 5127 idle->on_cpu = 1; 5128 #endif 5129 raw_spin_unlock_irqrestore(&rq->lock, flags); 5130 5131 /* Set the preempt count _outside_ the spinlocks! */ 5132 task_thread_info(idle)->preempt_count = 0; 5133 5134 /* 5135 * The idle tasks have their own, simple scheduling class: 5136 */ 5137 idle->sched_class = &idle_sched_class; 5138 ftrace_graph_init_idle_task(idle, cpu); 5139 #if defined(CONFIG_SMP) 5140 sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu); 5141 #endif 5142 } 5143 5144 #ifdef CONFIG_SMP 5145 void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask) 5146 { 5147 if (p->sched_class && p->sched_class->set_cpus_allowed) 5148 p->sched_class->set_cpus_allowed(p, new_mask); 5149 5150 cpumask_copy(&p->cpus_allowed, new_mask); 5151 p->nr_cpus_allowed = cpumask_weight(new_mask); 5152 } 5153 5154 /* 5155 * This is how migration works: 5156 * 5157 * 1) we invoke migration_cpu_stop() on the target CPU using 5158 * stop_one_cpu(). 5159 * 2) stopper starts to run (implicitly forcing the migrated thread 5160 * off the CPU) 5161 * 3) it checks whether the migrated task is still in the wrong runqueue. 5162 * 4) if it's in the wrong runqueue then the migration thread removes 5163 * it and puts it into the right queue. 5164 * 5) stopper completes and stop_one_cpu() returns and the migration 5165 * is done. 5166 */ 5167 5168 /* 5169 * Change a given task's CPU affinity. Migrate the thread to a 5170 * proper CPU and schedule it away if the CPU it's executing on 5171 * is removed from the allowed bitmask. 5172 * 5173 * NOTE: the caller must have a valid reference to the task, the 5174 * task must not exit() & deallocate itself prematurely. The 5175 * call is not atomic; no spinlocks may be held. 5176 */ 5177 int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask) 5178 { 5179 unsigned long flags; 5180 struct rq *rq; 5181 unsigned int dest_cpu; 5182 int ret = 0; 5183 5184 rq = task_rq_lock(p, &flags); 5185 5186 if (cpumask_equal(&p->cpus_allowed, new_mask)) 5187 goto out; 5188 5189 if (!cpumask_intersects(new_mask, cpu_active_mask)) { 5190 ret = -EINVAL; 5191 goto out; 5192 } 5193 5194 if (unlikely((p->flags & PF_THREAD_BOUND) && p != current)) { 5195 ret = -EINVAL; 5196 goto out; 5197 } 5198 5199 do_set_cpus_allowed(p, new_mask); 5200 5201 /* Can the task run on the task's current CPU? If so, we're done */ 5202 if (cpumask_test_cpu(task_cpu(p), new_mask)) 5203 goto out; 5204 5205 dest_cpu = cpumask_any_and(cpu_active_mask, new_mask); 5206 if (p->on_rq) { 5207 struct migration_arg arg = { p, dest_cpu }; 5208 /* Need help from migration thread: drop lock and wait. */ 5209 task_rq_unlock(rq, p, &flags); 5210 stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg); 5211 tlb_migrate_finish(p->mm); 5212 return 0; 5213 } 5214 out: 5215 task_rq_unlock(rq, p, &flags); 5216 5217 return ret; 5218 } 5219 EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr); 5220 5221 /* 5222 * Move (not current) task off this cpu, onto dest cpu. We're doing 5223 * this because either it can't run here any more (set_cpus_allowed() 5224 * away from this CPU, or CPU going down), or because we're 5225 * attempting to rebalance this task on exec (sched_exec). 5226 * 5227 * So we race with normal scheduler movements, but that's OK, as long 5228 * as the task is no longer on this CPU. 5229 * 5230 * Returns non-zero if task was successfully migrated. 5231 */ 5232 static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu) 5233 { 5234 struct rq *rq_dest, *rq_src; 5235 int ret = 0; 5236 5237 if (unlikely(!cpu_active(dest_cpu))) 5238 return ret; 5239 5240 rq_src = cpu_rq(src_cpu); 5241 rq_dest = cpu_rq(dest_cpu); 5242 5243 raw_spin_lock(&p->pi_lock); 5244 double_rq_lock(rq_src, rq_dest); 5245 /* Already moved. */ 5246 if (task_cpu(p) != src_cpu) 5247 goto done; 5248 /* Affinity changed (again). */ 5249 if (!cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p))) 5250 goto fail; 5251 5252 /* 5253 * If we're not on a rq, the next wake-up will ensure we're 5254 * placed properly. 5255 */ 5256 if (p->on_rq) { 5257 dequeue_task(rq_src, p, 0); 5258 set_task_cpu(p, dest_cpu); 5259 enqueue_task(rq_dest, p, 0); 5260 check_preempt_curr(rq_dest, p, 0); 5261 } 5262 done: 5263 ret = 1; 5264 fail: 5265 double_rq_unlock(rq_src, rq_dest); 5266 raw_spin_unlock(&p->pi_lock); 5267 return ret; 5268 } 5269 5270 /* 5271 * migration_cpu_stop - this will be executed by a highprio stopper thread 5272 * and performs thread migration by bumping thread off CPU then 5273 * 'pushing' onto another runqueue. 5274 */ 5275 static int migration_cpu_stop(void *data) 5276 { 5277 struct migration_arg *arg = data; 5278 5279 /* 5280 * The original target cpu might have gone down and we might 5281 * be on another cpu but it doesn't matter. 5282 */ 5283 local_irq_disable(); 5284 __migrate_task(arg->task, raw_smp_processor_id(), arg->dest_cpu); 5285 local_irq_enable(); 5286 return 0; 5287 } 5288 5289 #ifdef CONFIG_HOTPLUG_CPU 5290 5291 /* 5292 * Ensures that the idle task is using init_mm right before its cpu goes 5293 * offline. 5294 */ 5295 void idle_task_exit(void) 5296 { 5297 struct mm_struct *mm = current->active_mm; 5298 5299 BUG_ON(cpu_online(smp_processor_id())); 5300 5301 if (mm != &init_mm) 5302 switch_mm(mm, &init_mm, current); 5303 mmdrop(mm); 5304 } 5305 5306 /* 5307 * Since this CPU is going 'away' for a while, fold any nr_active delta 5308 * we might have. Assumes we're called after migrate_tasks() so that the 5309 * nr_active count is stable. 5310 * 5311 * Also see the comment "Global load-average calculations". 5312 */ 5313 static void calc_load_migrate(struct rq *rq) 5314 { 5315 long delta = calc_load_fold_active(rq); 5316 if (delta) 5317 atomic_long_add(delta, &calc_load_tasks); 5318 } 5319 5320 /* 5321 * Migrate all tasks from the rq, sleeping tasks will be migrated by 5322 * try_to_wake_up()->select_task_rq(). 5323 * 5324 * Called with rq->lock held even though we'er in stop_machine() and 5325 * there's no concurrency possible, we hold the required locks anyway 5326 * because of lock validation efforts. 5327 */ 5328 static void migrate_tasks(unsigned int dead_cpu) 5329 { 5330 struct rq *rq = cpu_rq(dead_cpu); 5331 struct task_struct *next, *stop = rq->stop; 5332 int dest_cpu; 5333 5334 /* 5335 * Fudge the rq selection such that the below task selection loop 5336 * doesn't get stuck on the currently eligible stop task. 5337 * 5338 * We're currently inside stop_machine() and the rq is either stuck 5339 * in the stop_machine_cpu_stop() loop, or we're executing this code, 5340 * either way we should never end up calling schedule() until we're 5341 * done here. 5342 */ 5343 rq->stop = NULL; 5344 5345 for ( ; ; ) { 5346 /* 5347 * There's this thread running, bail when that's the only 5348 * remaining thread. 5349 */ 5350 if (rq->nr_running == 1) 5351 break; 5352 5353 next = pick_next_task(rq); 5354 BUG_ON(!next); 5355 next->sched_class->put_prev_task(rq, next); 5356 5357 /* Find suitable destination for @next, with force if needed. */ 5358 dest_cpu = select_fallback_rq(dead_cpu, next); 5359 raw_spin_unlock(&rq->lock); 5360 5361 __migrate_task(next, dead_cpu, dest_cpu); 5362 5363 raw_spin_lock(&rq->lock); 5364 } 5365 5366 rq->stop = stop; 5367 } 5368 5369 #endif /* CONFIG_HOTPLUG_CPU */ 5370 5371 #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL) 5372 5373 static struct ctl_table sd_ctl_dir[] = { 5374 { 5375 .procname = "sched_domain", 5376 .mode = 0555, 5377 }, 5378 {} 5379 }; 5380 5381 static struct ctl_table sd_ctl_root[] = { 5382 { 5383 .procname = "kernel", 5384 .mode = 0555, 5385 .child = sd_ctl_dir, 5386 }, 5387 {} 5388 }; 5389 5390 static struct ctl_table *sd_alloc_ctl_entry(int n) 5391 { 5392 struct ctl_table *entry = 5393 kcalloc(n, sizeof(struct ctl_table), GFP_KERNEL); 5394 5395 return entry; 5396 } 5397 5398 static void sd_free_ctl_entry(struct ctl_table **tablep) 5399 { 5400 struct ctl_table *entry; 5401 5402 /* 5403 * In the intermediate directories, both the child directory and 5404 * procname are dynamically allocated and could fail but the mode 5405 * will always be set. In the lowest directory the names are 5406 * static strings and all have proc handlers. 5407 */ 5408 for (entry = *tablep; entry->mode; entry++) { 5409 if (entry->child) 5410 sd_free_ctl_entry(&entry->child); 5411 if (entry->proc_handler == NULL) 5412 kfree(entry->procname); 5413 } 5414 5415 kfree(*tablep); 5416 *tablep = NULL; 5417 } 5418 5419 static void 5420 set_table_entry(struct ctl_table *entry, 5421 const char *procname, void *data, int maxlen, 5422 umode_t mode, proc_handler *proc_handler) 5423 { 5424 entry->procname = procname; 5425 entry->data = data; 5426 entry->maxlen = maxlen; 5427 entry->mode = mode; 5428 entry->proc_handler = proc_handler; 5429 } 5430 5431 static struct ctl_table * 5432 sd_alloc_ctl_domain_table(struct sched_domain *sd) 5433 { 5434 struct ctl_table *table = sd_alloc_ctl_entry(13); 5435 5436 if (table == NULL) 5437 return NULL; 5438 5439 set_table_entry(&table[0], "min_interval", &sd->min_interval, 5440 sizeof(long), 0644, proc_doulongvec_minmax); 5441 set_table_entry(&table[1], "max_interval", &sd->max_interval, 5442 sizeof(long), 0644, proc_doulongvec_minmax); 5443 set_table_entry(&table[2], "busy_idx", &sd->busy_idx, 5444 sizeof(int), 0644, proc_dointvec_minmax); 5445 set_table_entry(&table[3], "idle_idx", &sd->idle_idx, 5446 sizeof(int), 0644, proc_dointvec_minmax); 5447 set_table_entry(&table[4], "newidle_idx", &sd->newidle_idx, 5448 sizeof(int), 0644, proc_dointvec_minmax); 5449 set_table_entry(&table[5], "wake_idx", &sd->wake_idx, 5450 sizeof(int), 0644, proc_dointvec_minmax); 5451 set_table_entry(&table[6], "forkexec_idx", &sd->forkexec_idx, 5452 sizeof(int), 0644, proc_dointvec_minmax); 5453 set_table_entry(&table[7], "busy_factor", &sd->busy_factor, 5454 sizeof(int), 0644, proc_dointvec_minmax); 5455 set_table_entry(&table[8], "imbalance_pct", &sd->imbalance_pct, 5456 sizeof(int), 0644, proc_dointvec_minmax); 5457 set_table_entry(&table[9], "cache_nice_tries", 5458 &sd->cache_nice_tries, 5459 sizeof(int), 0644, proc_dointvec_minmax); 5460 set_table_entry(&table[10], "flags", &sd->flags, 5461 sizeof(int), 0644, proc_dointvec_minmax); 5462 set_table_entry(&table[11], "name", sd->name, 5463 CORENAME_MAX_SIZE, 0444, proc_dostring); 5464 /* &table[12] is terminator */ 5465 5466 return table; 5467 } 5468 5469 static ctl_table *sd_alloc_ctl_cpu_table(int cpu) 5470 { 5471 struct ctl_table *entry, *table; 5472 struct sched_domain *sd; 5473 int domain_num = 0, i; 5474 char buf[32]; 5475 5476 for_each_domain(cpu, sd) 5477 domain_num++; 5478 entry = table = sd_alloc_ctl_entry(domain_num + 1); 5479 if (table == NULL) 5480 return NULL; 5481 5482 i = 0; 5483 for_each_domain(cpu, sd) { 5484 snprintf(buf, 32, "domain%d", i); 5485 entry->procname = kstrdup(buf, GFP_KERNEL); 5486 entry->mode = 0555; 5487 entry->child = sd_alloc_ctl_domain_table(sd); 5488 entry++; 5489 i++; 5490 } 5491 return table; 5492 } 5493 5494 static struct ctl_table_header *sd_sysctl_header; 5495 static void register_sched_domain_sysctl(void) 5496 { 5497 int i, cpu_num = num_possible_cpus(); 5498 struct ctl_table *entry = sd_alloc_ctl_entry(cpu_num + 1); 5499 char buf[32]; 5500 5501 WARN_ON(sd_ctl_dir[0].child); 5502 sd_ctl_dir[0].child = entry; 5503 5504 if (entry == NULL) 5505 return; 5506 5507 for_each_possible_cpu(i) { 5508 snprintf(buf, 32, "cpu%d", i); 5509 entry->procname = kstrdup(buf, GFP_KERNEL); 5510 entry->mode = 0555; 5511 entry->child = sd_alloc_ctl_cpu_table(i); 5512 entry++; 5513 } 5514 5515 WARN_ON(sd_sysctl_header); 5516 sd_sysctl_header = register_sysctl_table(sd_ctl_root); 5517 } 5518 5519 /* may be called multiple times per register */ 5520 static void unregister_sched_domain_sysctl(void) 5521 { 5522 if (sd_sysctl_header) 5523 unregister_sysctl_table(sd_sysctl_header); 5524 sd_sysctl_header = NULL; 5525 if (sd_ctl_dir[0].child) 5526 sd_free_ctl_entry(&sd_ctl_dir[0].child); 5527 } 5528 #else 5529 static void register_sched_domain_sysctl(void) 5530 { 5531 } 5532 static void unregister_sched_domain_sysctl(void) 5533 { 5534 } 5535 #endif 5536 5537 static void set_rq_online(struct rq *rq) 5538 { 5539 if (!rq->online) { 5540 const struct sched_class *class; 5541 5542 cpumask_set_cpu(rq->cpu, rq->rd->online); 5543 rq->online = 1; 5544 5545 for_each_class(class) { 5546 if (class->rq_online) 5547 class->rq_online(rq); 5548 } 5549 } 5550 } 5551 5552 static void set_rq_offline(struct rq *rq) 5553 { 5554 if (rq->online) { 5555 const struct sched_class *class; 5556 5557 for_each_class(class) { 5558 if (class->rq_offline) 5559 class->rq_offline(rq); 5560 } 5561 5562 cpumask_clear_cpu(rq->cpu, rq->rd->online); 5563 rq->online = 0; 5564 } 5565 } 5566 5567 /* 5568 * migration_call - callback that gets triggered when a CPU is added. 5569 * Here we can start up the necessary migration thread for the new CPU. 5570 */ 5571 static int __cpuinit 5572 migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu) 5573 { 5574 int cpu = (long)hcpu; 5575 unsigned long flags; 5576 struct rq *rq = cpu_rq(cpu); 5577 5578 switch (action & ~CPU_TASKS_FROZEN) { 5579 5580 case CPU_UP_PREPARE: 5581 rq->calc_load_update = calc_load_update; 5582 break; 5583 5584 case CPU_ONLINE: 5585 /* Update our root-domain */ 5586 raw_spin_lock_irqsave(&rq->lock, flags); 5587 if (rq->rd) { 5588 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); 5589 5590 set_rq_online(rq); 5591 } 5592 raw_spin_unlock_irqrestore(&rq->lock, flags); 5593 break; 5594 5595 #ifdef CONFIG_HOTPLUG_CPU 5596 case CPU_DYING: 5597 sched_ttwu_pending(); 5598 /* Update our root-domain */ 5599 raw_spin_lock_irqsave(&rq->lock, flags); 5600 if (rq->rd) { 5601 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); 5602 set_rq_offline(rq); 5603 } 5604 migrate_tasks(cpu); 5605 BUG_ON(rq->nr_running != 1); /* the migration thread */ 5606 raw_spin_unlock_irqrestore(&rq->lock, flags); 5607 5608 calc_load_migrate(rq); 5609 break; 5610 #endif 5611 } 5612 5613 update_max_interval(); 5614 5615 return NOTIFY_OK; 5616 } 5617 5618 /* 5619 * Register at high priority so that task migration (migrate_all_tasks) 5620 * happens before everything else. This has to be lower priority than 5621 * the notifier in the perf_event subsystem, though. 5622 */ 5623 static struct notifier_block __cpuinitdata migration_notifier = { 5624 .notifier_call = migration_call, 5625 .priority = CPU_PRI_MIGRATION, 5626 }; 5627 5628 static int __cpuinit sched_cpu_active(struct notifier_block *nfb, 5629 unsigned long action, void *hcpu) 5630 { 5631 switch (action & ~CPU_TASKS_FROZEN) { 5632 case CPU_STARTING: 5633 case CPU_DOWN_FAILED: 5634 set_cpu_active((long)hcpu, true); 5635 return NOTIFY_OK; 5636 default: 5637 return NOTIFY_DONE; 5638 } 5639 } 5640 5641 static int __cpuinit sched_cpu_inactive(struct notifier_block *nfb, 5642 unsigned long action, void *hcpu) 5643 { 5644 switch (action & ~CPU_TASKS_FROZEN) { 5645 case CPU_DOWN_PREPARE: 5646 set_cpu_active((long)hcpu, false); 5647 return NOTIFY_OK; 5648 default: 5649 return NOTIFY_DONE; 5650 } 5651 } 5652 5653 static int __init migration_init(void) 5654 { 5655 void *cpu = (void *)(long)smp_processor_id(); 5656 int err; 5657 5658 /* Initialize migration for the boot CPU */ 5659 err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu); 5660 BUG_ON(err == NOTIFY_BAD); 5661 migration_call(&migration_notifier, CPU_ONLINE, cpu); 5662 register_cpu_notifier(&migration_notifier); 5663 5664 /* Register cpu active notifiers */ 5665 cpu_notifier(sched_cpu_active, CPU_PRI_SCHED_ACTIVE); 5666 cpu_notifier(sched_cpu_inactive, CPU_PRI_SCHED_INACTIVE); 5667 5668 return 0; 5669 } 5670 early_initcall(migration_init); 5671 #endif 5672 5673 #ifdef CONFIG_SMP 5674 5675 static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */ 5676 5677 #ifdef CONFIG_SCHED_DEBUG 5678 5679 static __read_mostly int sched_debug_enabled; 5680 5681 static int __init sched_debug_setup(char *str) 5682 { 5683 sched_debug_enabled = 1; 5684 5685 return 0; 5686 } 5687 early_param("sched_debug", sched_debug_setup); 5688 5689 static inline bool sched_debug(void) 5690 { 5691 return sched_debug_enabled; 5692 } 5693 5694 static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level, 5695 struct cpumask *groupmask) 5696 { 5697 struct sched_group *group = sd->groups; 5698 char str[256]; 5699 5700 cpulist_scnprintf(str, sizeof(str), sched_domain_span(sd)); 5701 cpumask_clear(groupmask); 5702 5703 printk(KERN_DEBUG "%*s domain %d: ", level, "", level); 5704 5705 if (!(sd->flags & SD_LOAD_BALANCE)) { 5706 printk("does not load-balance\n"); 5707 if (sd->parent) 5708 printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain" 5709 " has parent"); 5710 return -1; 5711 } 5712 5713 printk(KERN_CONT "span %s level %s\n", str, sd->name); 5714 5715 if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) { 5716 printk(KERN_ERR "ERROR: domain->span does not contain " 5717 "CPU%d\n", cpu); 5718 } 5719 if (!cpumask_test_cpu(cpu, sched_group_cpus(group))) { 5720 printk(KERN_ERR "ERROR: domain->groups does not contain" 5721 " CPU%d\n", cpu); 5722 } 5723 5724 printk(KERN_DEBUG "%*s groups:", level + 1, ""); 5725 do { 5726 if (!group) { 5727 printk("\n"); 5728 printk(KERN_ERR "ERROR: group is NULL\n"); 5729 break; 5730 } 5731 5732 /* 5733 * Even though we initialize ->power to something semi-sane, 5734 * we leave power_orig unset. This allows us to detect if 5735 * domain iteration is still funny without causing /0 traps. 5736 */ 5737 if (!group->sgp->power_orig) { 5738 printk(KERN_CONT "\n"); 5739 printk(KERN_ERR "ERROR: domain->cpu_power not " 5740 "set\n"); 5741 break; 5742 } 5743 5744 if (!cpumask_weight(sched_group_cpus(group))) { 5745 printk(KERN_CONT "\n"); 5746 printk(KERN_ERR "ERROR: empty group\n"); 5747 break; 5748 } 5749 5750 if (!(sd->flags & SD_OVERLAP) && 5751 cpumask_intersects(groupmask, sched_group_cpus(group))) { 5752 printk(KERN_CONT "\n"); 5753 printk(KERN_ERR "ERROR: repeated CPUs\n"); 5754 break; 5755 } 5756 5757 cpumask_or(groupmask, groupmask, sched_group_cpus(group)); 5758 5759 cpulist_scnprintf(str, sizeof(str), sched_group_cpus(group)); 5760 5761 printk(KERN_CONT " %s", str); 5762 if (group->sgp->power != SCHED_POWER_SCALE) { 5763 printk(KERN_CONT " (cpu_power = %d)", 5764 group->sgp->power); 5765 } 5766 5767 group = group->next; 5768 } while (group != sd->groups); 5769 printk(KERN_CONT "\n"); 5770 5771 if (!cpumask_equal(sched_domain_span(sd), groupmask)) 5772 printk(KERN_ERR "ERROR: groups don't span domain->span\n"); 5773 5774 if (sd->parent && 5775 !cpumask_subset(groupmask, sched_domain_span(sd->parent))) 5776 printk(KERN_ERR "ERROR: parent span is not a superset " 5777 "of domain->span\n"); 5778 return 0; 5779 } 5780 5781 static void sched_domain_debug(struct sched_domain *sd, int cpu) 5782 { 5783 int level = 0; 5784 5785 if (!sched_debug_enabled) 5786 return; 5787 5788 if (!sd) { 5789 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu); 5790 return; 5791 } 5792 5793 printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu); 5794 5795 for (;;) { 5796 if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask)) 5797 break; 5798 level++; 5799 sd = sd->parent; 5800 if (!sd) 5801 break; 5802 } 5803 } 5804 #else /* !CONFIG_SCHED_DEBUG */ 5805 # define sched_domain_debug(sd, cpu) do { } while (0) 5806 static inline bool sched_debug(void) 5807 { 5808 return false; 5809 } 5810 #endif /* CONFIG_SCHED_DEBUG */ 5811 5812 static int sd_degenerate(struct sched_domain *sd) 5813 { 5814 if (cpumask_weight(sched_domain_span(sd)) == 1) 5815 return 1; 5816 5817 /* Following flags need at least 2 groups */ 5818 if (sd->flags & (SD_LOAD_BALANCE | 5819 SD_BALANCE_NEWIDLE | 5820 SD_BALANCE_FORK | 5821 SD_BALANCE_EXEC | 5822 SD_SHARE_CPUPOWER | 5823 SD_SHARE_PKG_RESOURCES)) { 5824 if (sd->groups != sd->groups->next) 5825 return 0; 5826 } 5827 5828 /* Following flags don't use groups */ 5829 if (sd->flags & (SD_WAKE_AFFINE)) 5830 return 0; 5831 5832 return 1; 5833 } 5834 5835 static int 5836 sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent) 5837 { 5838 unsigned long cflags = sd->flags, pflags = parent->flags; 5839 5840 if (sd_degenerate(parent)) 5841 return 1; 5842 5843 if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent))) 5844 return 0; 5845 5846 /* Flags needing groups don't count if only 1 group in parent */ 5847 if (parent->groups == parent->groups->next) { 5848 pflags &= ~(SD_LOAD_BALANCE | 5849 SD_BALANCE_NEWIDLE | 5850 SD_BALANCE_FORK | 5851 SD_BALANCE_EXEC | 5852 SD_SHARE_CPUPOWER | 5853 SD_SHARE_PKG_RESOURCES); 5854 if (nr_node_ids == 1) 5855 pflags &= ~SD_SERIALIZE; 5856 } 5857 if (~cflags & pflags) 5858 return 0; 5859 5860 return 1; 5861 } 5862 5863 static void free_rootdomain(struct rcu_head *rcu) 5864 { 5865 struct root_domain *rd = container_of(rcu, struct root_domain, rcu); 5866 5867 cpupri_cleanup(&rd->cpupri); 5868 free_cpumask_var(rd->rto_mask); 5869 free_cpumask_var(rd->online); 5870 free_cpumask_var(rd->span); 5871 kfree(rd); 5872 } 5873 5874 static void rq_attach_root(struct rq *rq, struct root_domain *rd) 5875 { 5876 struct root_domain *old_rd = NULL; 5877 unsigned long flags; 5878 5879 raw_spin_lock_irqsave(&rq->lock, flags); 5880 5881 if (rq->rd) { 5882 old_rd = rq->rd; 5883 5884 if (cpumask_test_cpu(rq->cpu, old_rd->online)) 5885 set_rq_offline(rq); 5886 5887 cpumask_clear_cpu(rq->cpu, old_rd->span); 5888 5889 /* 5890 * If we dont want to free the old_rt yet then 5891 * set old_rd to NULL to skip the freeing later 5892 * in this function: 5893 */ 5894 if (!atomic_dec_and_test(&old_rd->refcount)) 5895 old_rd = NULL; 5896 } 5897 5898 atomic_inc(&rd->refcount); 5899 rq->rd = rd; 5900 5901 cpumask_set_cpu(rq->cpu, rd->span); 5902 if (cpumask_test_cpu(rq->cpu, cpu_active_mask)) 5903 set_rq_online(rq); 5904 5905 raw_spin_unlock_irqrestore(&rq->lock, flags); 5906 5907 if (old_rd) 5908 call_rcu_sched(&old_rd->rcu, free_rootdomain); 5909 } 5910 5911 static int init_rootdomain(struct root_domain *rd) 5912 { 5913 memset(rd, 0, sizeof(*rd)); 5914 5915 if (!alloc_cpumask_var(&rd->span, GFP_KERNEL)) 5916 goto out; 5917 if (!alloc_cpumask_var(&rd->online, GFP_KERNEL)) 5918 goto free_span; 5919 if (!alloc_cpumask_var(&rd->rto_mask, GFP_KERNEL)) 5920 goto free_online; 5921 5922 if (cpupri_init(&rd->cpupri) != 0) 5923 goto free_rto_mask; 5924 return 0; 5925 5926 free_rto_mask: 5927 free_cpumask_var(rd->rto_mask); 5928 free_online: 5929 free_cpumask_var(rd->online); 5930 free_span: 5931 free_cpumask_var(rd->span); 5932 out: 5933 return -ENOMEM; 5934 } 5935 5936 /* 5937 * By default the system creates a single root-domain with all cpus as 5938 * members (mimicking the global state we have today). 5939 */ 5940 struct root_domain def_root_domain; 5941 5942 static void init_defrootdomain(void) 5943 { 5944 init_rootdomain(&def_root_domain); 5945 5946 atomic_set(&def_root_domain.refcount, 1); 5947 } 5948 5949 static struct root_domain *alloc_rootdomain(void) 5950 { 5951 struct root_domain *rd; 5952 5953 rd = kmalloc(sizeof(*rd), GFP_KERNEL); 5954 if (!rd) 5955 return NULL; 5956 5957 if (init_rootdomain(rd) != 0) { 5958 kfree(rd); 5959 return NULL; 5960 } 5961 5962 return rd; 5963 } 5964 5965 static void free_sched_groups(struct sched_group *sg, int free_sgp) 5966 { 5967 struct sched_group *tmp, *first; 5968 5969 if (!sg) 5970 return; 5971 5972 first = sg; 5973 do { 5974 tmp = sg->next; 5975 5976 if (free_sgp && atomic_dec_and_test(&sg->sgp->ref)) 5977 kfree(sg->sgp); 5978 5979 kfree(sg); 5980 sg = tmp; 5981 } while (sg != first); 5982 } 5983 5984 static void free_sched_domain(struct rcu_head *rcu) 5985 { 5986 struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu); 5987 5988 /* 5989 * If its an overlapping domain it has private groups, iterate and 5990 * nuke them all. 5991 */ 5992 if (sd->flags & SD_OVERLAP) { 5993 free_sched_groups(sd->groups, 1); 5994 } else if (atomic_dec_and_test(&sd->groups->ref)) { 5995 kfree(sd->groups->sgp); 5996 kfree(sd->groups); 5997 } 5998 kfree(sd); 5999 } 6000 6001 static void destroy_sched_domain(struct sched_domain *sd, int cpu) 6002 { 6003 call_rcu(&sd->rcu, free_sched_domain); 6004 } 6005 6006 static void destroy_sched_domains(struct sched_domain *sd, int cpu) 6007 { 6008 for (; sd; sd = sd->parent) 6009 destroy_sched_domain(sd, cpu); 6010 } 6011 6012 /* 6013 * Keep a special pointer to the highest sched_domain that has 6014 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this 6015 * allows us to avoid some pointer chasing select_idle_sibling(). 6016 * 6017 * Also keep a unique ID per domain (we use the first cpu number in 6018 * the cpumask of the domain), this allows us to quickly tell if 6019 * two cpus are in the same cache domain, see cpus_share_cache(). 6020 */ 6021 DEFINE_PER_CPU(struct sched_domain *, sd_llc); 6022 DEFINE_PER_CPU(int, sd_llc_id); 6023 6024 static void update_top_cache_domain(int cpu) 6025 { 6026 struct sched_domain *sd; 6027 int id = cpu; 6028 6029 sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES); 6030 if (sd) 6031 id = cpumask_first(sched_domain_span(sd)); 6032 6033 rcu_assign_pointer(per_cpu(sd_llc, cpu), sd); 6034 per_cpu(sd_llc_id, cpu) = id; 6035 } 6036 6037 /* 6038 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must 6039 * hold the hotplug lock. 6040 */ 6041 static void 6042 cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu) 6043 { 6044 struct rq *rq = cpu_rq(cpu); 6045 struct sched_domain *tmp; 6046 6047 /* Remove the sched domains which do not contribute to scheduling. */ 6048 for (tmp = sd; tmp; ) { 6049 struct sched_domain *parent = tmp->parent; 6050 if (!parent) 6051 break; 6052 6053 if (sd_parent_degenerate(tmp, parent)) { 6054 tmp->parent = parent->parent; 6055 if (parent->parent) 6056 parent->parent->child = tmp; 6057 destroy_sched_domain(parent, cpu); 6058 } else 6059 tmp = tmp->parent; 6060 } 6061 6062 if (sd && sd_degenerate(sd)) { 6063 tmp = sd; 6064 sd = sd->parent; 6065 destroy_sched_domain(tmp, cpu); 6066 if (sd) 6067 sd->child = NULL; 6068 } 6069 6070 sched_domain_debug(sd, cpu); 6071 6072 rq_attach_root(rq, rd); 6073 tmp = rq->sd; 6074 rcu_assign_pointer(rq->sd, sd); 6075 destroy_sched_domains(tmp, cpu); 6076 6077 update_top_cache_domain(cpu); 6078 } 6079 6080 /* cpus with isolated domains */ 6081 static cpumask_var_t cpu_isolated_map; 6082 6083 /* Setup the mask of cpus configured for isolated domains */ 6084 static int __init isolated_cpu_setup(char *str) 6085 { 6086 alloc_bootmem_cpumask_var(&cpu_isolated_map); 6087 cpulist_parse(str, cpu_isolated_map); 6088 return 1; 6089 } 6090 6091 __setup("isolcpus=", isolated_cpu_setup); 6092 6093 static const struct cpumask *cpu_cpu_mask(int cpu) 6094 { 6095 return cpumask_of_node(cpu_to_node(cpu)); 6096 } 6097 6098 struct sd_data { 6099 struct sched_domain **__percpu sd; 6100 struct sched_group **__percpu sg; 6101 struct sched_group_power **__percpu sgp; 6102 }; 6103 6104 struct s_data { 6105 struct sched_domain ** __percpu sd; 6106 struct root_domain *rd; 6107 }; 6108 6109 enum s_alloc { 6110 sa_rootdomain, 6111 sa_sd, 6112 sa_sd_storage, 6113 sa_none, 6114 }; 6115 6116 struct sched_domain_topology_level; 6117 6118 typedef struct sched_domain *(*sched_domain_init_f)(struct sched_domain_topology_level *tl, int cpu); 6119 typedef const struct cpumask *(*sched_domain_mask_f)(int cpu); 6120 6121 #define SDTL_OVERLAP 0x01 6122 6123 struct sched_domain_topology_level { 6124 sched_domain_init_f init; 6125 sched_domain_mask_f mask; 6126 int flags; 6127 int numa_level; 6128 struct sd_data data; 6129 }; 6130 6131 /* 6132 * Build an iteration mask that can exclude certain CPUs from the upwards 6133 * domain traversal. 6134 * 6135 * Asymmetric node setups can result in situations where the domain tree is of 6136 * unequal depth, make sure to skip domains that already cover the entire 6137 * range. 6138 * 6139 * In that case build_sched_domains() will have terminated the iteration early 6140 * and our sibling sd spans will be empty. Domains should always include the 6141 * cpu they're built on, so check that. 6142 * 6143 */ 6144 static void build_group_mask(struct sched_domain *sd, struct sched_group *sg) 6145 { 6146 const struct cpumask *span = sched_domain_span(sd); 6147 struct sd_data *sdd = sd->private; 6148 struct sched_domain *sibling; 6149 int i; 6150 6151 for_each_cpu(i, span) { 6152 sibling = *per_cpu_ptr(sdd->sd, i); 6153 if (!cpumask_test_cpu(i, sched_domain_span(sibling))) 6154 continue; 6155 6156 cpumask_set_cpu(i, sched_group_mask(sg)); 6157 } 6158 } 6159 6160 /* 6161 * Return the canonical balance cpu for this group, this is the first cpu 6162 * of this group that's also in the iteration mask. 6163 */ 6164 int group_balance_cpu(struct sched_group *sg) 6165 { 6166 return cpumask_first_and(sched_group_cpus(sg), sched_group_mask(sg)); 6167 } 6168 6169 static int 6170 build_overlap_sched_groups(struct sched_domain *sd, int cpu) 6171 { 6172 struct sched_group *first = NULL, *last = NULL, *groups = NULL, *sg; 6173 const struct cpumask *span = sched_domain_span(sd); 6174 struct cpumask *covered = sched_domains_tmpmask; 6175 struct sd_data *sdd = sd->private; 6176 struct sched_domain *child; 6177 int i; 6178 6179 cpumask_clear(covered); 6180 6181 for_each_cpu(i, span) { 6182 struct cpumask *sg_span; 6183 6184 if (cpumask_test_cpu(i, covered)) 6185 continue; 6186 6187 child = *per_cpu_ptr(sdd->sd, i); 6188 6189 /* See the comment near build_group_mask(). */ 6190 if (!cpumask_test_cpu(i, sched_domain_span(child))) 6191 continue; 6192 6193 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(), 6194 GFP_KERNEL, cpu_to_node(cpu)); 6195 6196 if (!sg) 6197 goto fail; 6198 6199 sg_span = sched_group_cpus(sg); 6200 if (child->child) { 6201 child = child->child; 6202 cpumask_copy(sg_span, sched_domain_span(child)); 6203 } else 6204 cpumask_set_cpu(i, sg_span); 6205 6206 cpumask_or(covered, covered, sg_span); 6207 6208 sg->sgp = *per_cpu_ptr(sdd->sgp, i); 6209 if (atomic_inc_return(&sg->sgp->ref) == 1) 6210 build_group_mask(sd, sg); 6211 6212 /* 6213 * Initialize sgp->power such that even if we mess up the 6214 * domains and no possible iteration will get us here, we won't 6215 * die on a /0 trap. 6216 */ 6217 sg->sgp->power = SCHED_POWER_SCALE * cpumask_weight(sg_span); 6218 6219 /* 6220 * Make sure the first group of this domain contains the 6221 * canonical balance cpu. Otherwise the sched_domain iteration 6222 * breaks. See update_sg_lb_stats(). 6223 */ 6224 if ((!groups && cpumask_test_cpu(cpu, sg_span)) || 6225 group_balance_cpu(sg) == cpu) 6226 groups = sg; 6227 6228 if (!first) 6229 first = sg; 6230 if (last) 6231 last->next = sg; 6232 last = sg; 6233 last->next = first; 6234 } 6235 sd->groups = groups; 6236 6237 return 0; 6238 6239 fail: 6240 free_sched_groups(first, 0); 6241 6242 return -ENOMEM; 6243 } 6244 6245 static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg) 6246 { 6247 struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu); 6248 struct sched_domain *child = sd->child; 6249 6250 if (child) 6251 cpu = cpumask_first(sched_domain_span(child)); 6252 6253 if (sg) { 6254 *sg = *per_cpu_ptr(sdd->sg, cpu); 6255 (*sg)->sgp = *per_cpu_ptr(sdd->sgp, cpu); 6256 atomic_set(&(*sg)->sgp->ref, 1); /* for claim_allocations */ 6257 } 6258 6259 return cpu; 6260 } 6261 6262 /* 6263 * build_sched_groups will build a circular linked list of the groups 6264 * covered by the given span, and will set each group's ->cpumask correctly, 6265 * and ->cpu_power to 0. 6266 * 6267 * Assumes the sched_domain tree is fully constructed 6268 */ 6269 static int 6270 build_sched_groups(struct sched_domain *sd, int cpu) 6271 { 6272 struct sched_group *first = NULL, *last = NULL; 6273 struct sd_data *sdd = sd->private; 6274 const struct cpumask *span = sched_domain_span(sd); 6275 struct cpumask *covered; 6276 int i; 6277 6278 get_group(cpu, sdd, &sd->groups); 6279 atomic_inc(&sd->groups->ref); 6280 6281 if (cpu != cpumask_first(sched_domain_span(sd))) 6282 return 0; 6283 6284 lockdep_assert_held(&sched_domains_mutex); 6285 covered = sched_domains_tmpmask; 6286 6287 cpumask_clear(covered); 6288 6289 for_each_cpu(i, span) { 6290 struct sched_group *sg; 6291 int group = get_group(i, sdd, &sg); 6292 int j; 6293 6294 if (cpumask_test_cpu(i, covered)) 6295 continue; 6296 6297 cpumask_clear(sched_group_cpus(sg)); 6298 sg->sgp->power = 0; 6299 cpumask_setall(sched_group_mask(sg)); 6300 6301 for_each_cpu(j, span) { 6302 if (get_group(j, sdd, NULL) != group) 6303 continue; 6304 6305 cpumask_set_cpu(j, covered); 6306 cpumask_set_cpu(j, sched_group_cpus(sg)); 6307 } 6308 6309 if (!first) 6310 first = sg; 6311 if (last) 6312 last->next = sg; 6313 last = sg; 6314 } 6315 last->next = first; 6316 6317 return 0; 6318 } 6319 6320 /* 6321 * Initialize sched groups cpu_power. 6322 * 6323 * cpu_power indicates the capacity of sched group, which is used while 6324 * distributing the load between different sched groups in a sched domain. 6325 * Typically cpu_power for all the groups in a sched domain will be same unless 6326 * there are asymmetries in the topology. If there are asymmetries, group 6327 * having more cpu_power will pickup more load compared to the group having 6328 * less cpu_power. 6329 */ 6330 static void init_sched_groups_power(int cpu, struct sched_domain *sd) 6331 { 6332 struct sched_group *sg = sd->groups; 6333 6334 WARN_ON(!sd || !sg); 6335 6336 do { 6337 sg->group_weight = cpumask_weight(sched_group_cpus(sg)); 6338 sg = sg->next; 6339 } while (sg != sd->groups); 6340 6341 if (cpu != group_balance_cpu(sg)) 6342 return; 6343 6344 update_group_power(sd, cpu); 6345 atomic_set(&sg->sgp->nr_busy_cpus, sg->group_weight); 6346 } 6347 6348 int __weak arch_sd_sibling_asym_packing(void) 6349 { 6350 return 0*SD_ASYM_PACKING; 6351 } 6352 6353 /* 6354 * Initializers for schedule domains 6355 * Non-inlined to reduce accumulated stack pressure in build_sched_domains() 6356 */ 6357 6358 #ifdef CONFIG_SCHED_DEBUG 6359 # define SD_INIT_NAME(sd, type) sd->name = #type 6360 #else 6361 # define SD_INIT_NAME(sd, type) do { } while (0) 6362 #endif 6363 6364 #define SD_INIT_FUNC(type) \ 6365 static noinline struct sched_domain * \ 6366 sd_init_##type(struct sched_domain_topology_level *tl, int cpu) \ 6367 { \ 6368 struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu); \ 6369 *sd = SD_##type##_INIT; \ 6370 SD_INIT_NAME(sd, type); \ 6371 sd->private = &tl->data; \ 6372 return sd; \ 6373 } 6374 6375 SD_INIT_FUNC(CPU) 6376 #ifdef CONFIG_SCHED_SMT 6377 SD_INIT_FUNC(SIBLING) 6378 #endif 6379 #ifdef CONFIG_SCHED_MC 6380 SD_INIT_FUNC(MC) 6381 #endif 6382 #ifdef CONFIG_SCHED_BOOK 6383 SD_INIT_FUNC(BOOK) 6384 #endif 6385 6386 static int default_relax_domain_level = -1; 6387 int sched_domain_level_max; 6388 6389 static int __init setup_relax_domain_level(char *str) 6390 { 6391 if (kstrtoint(str, 0, &default_relax_domain_level)) 6392 pr_warn("Unable to set relax_domain_level\n"); 6393 6394 return 1; 6395 } 6396 __setup("relax_domain_level=", setup_relax_domain_level); 6397 6398 static void set_domain_attribute(struct sched_domain *sd, 6399 struct sched_domain_attr *attr) 6400 { 6401 int request; 6402 6403 if (!attr || attr->relax_domain_level < 0) { 6404 if (default_relax_domain_level < 0) 6405 return; 6406 else 6407 request = default_relax_domain_level; 6408 } else 6409 request = attr->relax_domain_level; 6410 if (request < sd->level) { 6411 /* turn off idle balance on this domain */ 6412 sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE); 6413 } else { 6414 /* turn on idle balance on this domain */ 6415 sd->flags |= (SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE); 6416 } 6417 } 6418 6419 static void __sdt_free(const struct cpumask *cpu_map); 6420 static int __sdt_alloc(const struct cpumask *cpu_map); 6421 6422 static void __free_domain_allocs(struct s_data *d, enum s_alloc what, 6423 const struct cpumask *cpu_map) 6424 { 6425 switch (what) { 6426 case sa_rootdomain: 6427 if (!atomic_read(&d->rd->refcount)) 6428 free_rootdomain(&d->rd->rcu); /* fall through */ 6429 case sa_sd: 6430 free_percpu(d->sd); /* fall through */ 6431 case sa_sd_storage: 6432 __sdt_free(cpu_map); /* fall through */ 6433 case sa_none: 6434 break; 6435 } 6436 } 6437 6438 static enum s_alloc __visit_domain_allocation_hell(struct s_data *d, 6439 const struct cpumask *cpu_map) 6440 { 6441 memset(d, 0, sizeof(*d)); 6442 6443 if (__sdt_alloc(cpu_map)) 6444 return sa_sd_storage; 6445 d->sd = alloc_percpu(struct sched_domain *); 6446 if (!d->sd) 6447 return sa_sd_storage; 6448 d->rd = alloc_rootdomain(); 6449 if (!d->rd) 6450 return sa_sd; 6451 return sa_rootdomain; 6452 } 6453 6454 /* 6455 * NULL the sd_data elements we've used to build the sched_domain and 6456 * sched_group structure so that the subsequent __free_domain_allocs() 6457 * will not free the data we're using. 6458 */ 6459 static void claim_allocations(int cpu, struct sched_domain *sd) 6460 { 6461 struct sd_data *sdd = sd->private; 6462 6463 WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd); 6464 *per_cpu_ptr(sdd->sd, cpu) = NULL; 6465 6466 if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref)) 6467 *per_cpu_ptr(sdd->sg, cpu) = NULL; 6468 6469 if (atomic_read(&(*per_cpu_ptr(sdd->sgp, cpu))->ref)) 6470 *per_cpu_ptr(sdd->sgp, cpu) = NULL; 6471 } 6472 6473 #ifdef CONFIG_SCHED_SMT 6474 static const struct cpumask *cpu_smt_mask(int cpu) 6475 { 6476 return topology_thread_cpumask(cpu); 6477 } 6478 #endif 6479 6480 /* 6481 * Topology list, bottom-up. 6482 */ 6483 static struct sched_domain_topology_level default_topology[] = { 6484 #ifdef CONFIG_SCHED_SMT 6485 { sd_init_SIBLING, cpu_smt_mask, }, 6486 #endif 6487 #ifdef CONFIG_SCHED_MC 6488 { sd_init_MC, cpu_coregroup_mask, }, 6489 #endif 6490 #ifdef CONFIG_SCHED_BOOK 6491 { sd_init_BOOK, cpu_book_mask, }, 6492 #endif 6493 { sd_init_CPU, cpu_cpu_mask, }, 6494 { NULL, }, 6495 }; 6496 6497 static struct sched_domain_topology_level *sched_domain_topology = default_topology; 6498 6499 #ifdef CONFIG_NUMA 6500 6501 static int sched_domains_numa_levels; 6502 static int *sched_domains_numa_distance; 6503 static struct cpumask ***sched_domains_numa_masks; 6504 static int sched_domains_curr_level; 6505 6506 static inline int sd_local_flags(int level) 6507 { 6508 if (sched_domains_numa_distance[level] > RECLAIM_DISTANCE) 6509 return 0; 6510 6511 return SD_BALANCE_EXEC | SD_BALANCE_FORK | SD_WAKE_AFFINE; 6512 } 6513 6514 static struct sched_domain * 6515 sd_numa_init(struct sched_domain_topology_level *tl, int cpu) 6516 { 6517 struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu); 6518 int level = tl->numa_level; 6519 int sd_weight = cpumask_weight( 6520 sched_domains_numa_masks[level][cpu_to_node(cpu)]); 6521 6522 *sd = (struct sched_domain){ 6523 .min_interval = sd_weight, 6524 .max_interval = 2*sd_weight, 6525 .busy_factor = 32, 6526 .imbalance_pct = 125, 6527 .cache_nice_tries = 2, 6528 .busy_idx = 3, 6529 .idle_idx = 2, 6530 .newidle_idx = 0, 6531 .wake_idx = 0, 6532 .forkexec_idx = 0, 6533 6534 .flags = 1*SD_LOAD_BALANCE 6535 | 1*SD_BALANCE_NEWIDLE 6536 | 0*SD_BALANCE_EXEC 6537 | 0*SD_BALANCE_FORK 6538 | 0*SD_BALANCE_WAKE 6539 | 0*SD_WAKE_AFFINE 6540 | 0*SD_PREFER_LOCAL 6541 | 0*SD_SHARE_CPUPOWER 6542 | 0*SD_SHARE_PKG_RESOURCES 6543 | 1*SD_SERIALIZE 6544 | 0*SD_PREFER_SIBLING 6545 | sd_local_flags(level) 6546 , 6547 .last_balance = jiffies, 6548 .balance_interval = sd_weight, 6549 }; 6550 SD_INIT_NAME(sd, NUMA); 6551 sd->private = &tl->data; 6552 6553 /* 6554 * Ugly hack to pass state to sd_numa_mask()... 6555 */ 6556 sched_domains_curr_level = tl->numa_level; 6557 6558 return sd; 6559 } 6560 6561 static const struct cpumask *sd_numa_mask(int cpu) 6562 { 6563 return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)]; 6564 } 6565 6566 static void sched_numa_warn(const char *str) 6567 { 6568 static int done = false; 6569 int i,j; 6570 6571 if (done) 6572 return; 6573 6574 done = true; 6575 6576 printk(KERN_WARNING "ERROR: %s\n\n", str); 6577 6578 for (i = 0; i < nr_node_ids; i++) { 6579 printk(KERN_WARNING " "); 6580 for (j = 0; j < nr_node_ids; j++) 6581 printk(KERN_CONT "%02d ", node_distance(i,j)); 6582 printk(KERN_CONT "\n"); 6583 } 6584 printk(KERN_WARNING "\n"); 6585 } 6586 6587 static bool find_numa_distance(int distance) 6588 { 6589 int i; 6590 6591 if (distance == node_distance(0, 0)) 6592 return true; 6593 6594 for (i = 0; i < sched_domains_numa_levels; i++) { 6595 if (sched_domains_numa_distance[i] == distance) 6596 return true; 6597 } 6598 6599 return false; 6600 } 6601 6602 static void sched_init_numa(void) 6603 { 6604 int next_distance, curr_distance = node_distance(0, 0); 6605 struct sched_domain_topology_level *tl; 6606 int level = 0; 6607 int i, j, k; 6608 6609 sched_domains_numa_distance = kzalloc(sizeof(int) * nr_node_ids, GFP_KERNEL); 6610 if (!sched_domains_numa_distance) 6611 return; 6612 6613 /* 6614 * O(nr_nodes^2) deduplicating selection sort -- in order to find the 6615 * unique distances in the node_distance() table. 6616 * 6617 * Assumes node_distance(0,j) includes all distances in 6618 * node_distance(i,j) in order to avoid cubic time. 6619 */ 6620 next_distance = curr_distance; 6621 for (i = 0; i < nr_node_ids; i++) { 6622 for (j = 0; j < nr_node_ids; j++) { 6623 for (k = 0; k < nr_node_ids; k++) { 6624 int distance = node_distance(i, k); 6625 6626 if (distance > curr_distance && 6627 (distance < next_distance || 6628 next_distance == curr_distance)) 6629 next_distance = distance; 6630 6631 /* 6632 * While not a strong assumption it would be nice to know 6633 * about cases where if node A is connected to B, B is not 6634 * equally connected to A. 6635 */ 6636 if (sched_debug() && node_distance(k, i) != distance) 6637 sched_numa_warn("Node-distance not symmetric"); 6638 6639 if (sched_debug() && i && !find_numa_distance(distance)) 6640 sched_numa_warn("Node-0 not representative"); 6641 } 6642 if (next_distance != curr_distance) { 6643 sched_domains_numa_distance[level++] = next_distance; 6644 sched_domains_numa_levels = level; 6645 curr_distance = next_distance; 6646 } else break; 6647 } 6648 6649 /* 6650 * In case of sched_debug() we verify the above assumption. 6651 */ 6652 if (!sched_debug()) 6653 break; 6654 } 6655 /* 6656 * 'level' contains the number of unique distances, excluding the 6657 * identity distance node_distance(i,i). 6658 * 6659 * The sched_domains_nume_distance[] array includes the actual distance 6660 * numbers. 6661 */ 6662 6663 sched_domains_numa_masks = kzalloc(sizeof(void *) * level, GFP_KERNEL); 6664 if (!sched_domains_numa_masks) 6665 return; 6666 6667 /* 6668 * Now for each level, construct a mask per node which contains all 6669 * cpus of nodes that are that many hops away from us. 6670 */ 6671 for (i = 0; i < level; i++) { 6672 sched_domains_numa_masks[i] = 6673 kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL); 6674 if (!sched_domains_numa_masks[i]) 6675 return; 6676 6677 for (j = 0; j < nr_node_ids; j++) { 6678 struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL); 6679 if (!mask) 6680 return; 6681 6682 sched_domains_numa_masks[i][j] = mask; 6683 6684 for (k = 0; k < nr_node_ids; k++) { 6685 if (node_distance(j, k) > sched_domains_numa_distance[i]) 6686 continue; 6687 6688 cpumask_or(mask, mask, cpumask_of_node(k)); 6689 } 6690 } 6691 } 6692 6693 tl = kzalloc((ARRAY_SIZE(default_topology) + level) * 6694 sizeof(struct sched_domain_topology_level), GFP_KERNEL); 6695 if (!tl) 6696 return; 6697 6698 /* 6699 * Copy the default topology bits.. 6700 */ 6701 for (i = 0; default_topology[i].init; i++) 6702 tl[i] = default_topology[i]; 6703 6704 /* 6705 * .. and append 'j' levels of NUMA goodness. 6706 */ 6707 for (j = 0; j < level; i++, j++) { 6708 tl[i] = (struct sched_domain_topology_level){ 6709 .init = sd_numa_init, 6710 .mask = sd_numa_mask, 6711 .flags = SDTL_OVERLAP, 6712 .numa_level = j, 6713 }; 6714 } 6715 6716 sched_domain_topology = tl; 6717 } 6718 #else 6719 static inline void sched_init_numa(void) 6720 { 6721 } 6722 #endif /* CONFIG_NUMA */ 6723 6724 static int __sdt_alloc(const struct cpumask *cpu_map) 6725 { 6726 struct sched_domain_topology_level *tl; 6727 int j; 6728 6729 for (tl = sched_domain_topology; tl->init; tl++) { 6730 struct sd_data *sdd = &tl->data; 6731 6732 sdd->sd = alloc_percpu(struct sched_domain *); 6733 if (!sdd->sd) 6734 return -ENOMEM; 6735 6736 sdd->sg = alloc_percpu(struct sched_group *); 6737 if (!sdd->sg) 6738 return -ENOMEM; 6739 6740 sdd->sgp = alloc_percpu(struct sched_group_power *); 6741 if (!sdd->sgp) 6742 return -ENOMEM; 6743 6744 for_each_cpu(j, cpu_map) { 6745 struct sched_domain *sd; 6746 struct sched_group *sg; 6747 struct sched_group_power *sgp; 6748 6749 sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(), 6750 GFP_KERNEL, cpu_to_node(j)); 6751 if (!sd) 6752 return -ENOMEM; 6753 6754 *per_cpu_ptr(sdd->sd, j) = sd; 6755 6756 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(), 6757 GFP_KERNEL, cpu_to_node(j)); 6758 if (!sg) 6759 return -ENOMEM; 6760 6761 sg->next = sg; 6762 6763 *per_cpu_ptr(sdd->sg, j) = sg; 6764 6765 sgp = kzalloc_node(sizeof(struct sched_group_power) + cpumask_size(), 6766 GFP_KERNEL, cpu_to_node(j)); 6767 if (!sgp) 6768 return -ENOMEM; 6769 6770 *per_cpu_ptr(sdd->sgp, j) = sgp; 6771 } 6772 } 6773 6774 return 0; 6775 } 6776 6777 static void __sdt_free(const struct cpumask *cpu_map) 6778 { 6779 struct sched_domain_topology_level *tl; 6780 int j; 6781 6782 for (tl = sched_domain_topology; tl->init; tl++) { 6783 struct sd_data *sdd = &tl->data; 6784 6785 for_each_cpu(j, cpu_map) { 6786 struct sched_domain *sd; 6787 6788 if (sdd->sd) { 6789 sd = *per_cpu_ptr(sdd->sd, j); 6790 if (sd && (sd->flags & SD_OVERLAP)) 6791 free_sched_groups(sd->groups, 0); 6792 kfree(*per_cpu_ptr(sdd->sd, j)); 6793 } 6794 6795 if (sdd->sg) 6796 kfree(*per_cpu_ptr(sdd->sg, j)); 6797 if (sdd->sgp) 6798 kfree(*per_cpu_ptr(sdd->sgp, j)); 6799 } 6800 free_percpu(sdd->sd); 6801 sdd->sd = NULL; 6802 free_percpu(sdd->sg); 6803 sdd->sg = NULL; 6804 free_percpu(sdd->sgp); 6805 sdd->sgp = NULL; 6806 } 6807 } 6808 6809 struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl, 6810 struct s_data *d, const struct cpumask *cpu_map, 6811 struct sched_domain_attr *attr, struct sched_domain *child, 6812 int cpu) 6813 { 6814 struct sched_domain *sd = tl->init(tl, cpu); 6815 if (!sd) 6816 return child; 6817 6818 cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu)); 6819 if (child) { 6820 sd->level = child->level + 1; 6821 sched_domain_level_max = max(sched_domain_level_max, sd->level); 6822 child->parent = sd; 6823 } 6824 sd->child = child; 6825 set_domain_attribute(sd, attr); 6826 6827 return sd; 6828 } 6829 6830 /* 6831 * Build sched domains for a given set of cpus and attach the sched domains 6832 * to the individual cpus 6833 */ 6834 static int build_sched_domains(const struct cpumask *cpu_map, 6835 struct sched_domain_attr *attr) 6836 { 6837 enum s_alloc alloc_state = sa_none; 6838 struct sched_domain *sd; 6839 struct s_data d; 6840 int i, ret = -ENOMEM; 6841 6842 alloc_state = __visit_domain_allocation_hell(&d, cpu_map); 6843 if (alloc_state != sa_rootdomain) 6844 goto error; 6845 6846 /* Set up domains for cpus specified by the cpu_map. */ 6847 for_each_cpu(i, cpu_map) { 6848 struct sched_domain_topology_level *tl; 6849 6850 sd = NULL; 6851 for (tl = sched_domain_topology; tl->init; tl++) { 6852 sd = build_sched_domain(tl, &d, cpu_map, attr, sd, i); 6853 if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP)) 6854 sd->flags |= SD_OVERLAP; 6855 if (cpumask_equal(cpu_map, sched_domain_span(sd))) 6856 break; 6857 } 6858 6859 while (sd->child) 6860 sd = sd->child; 6861 6862 *per_cpu_ptr(d.sd, i) = sd; 6863 } 6864 6865 /* Build the groups for the domains */ 6866 for_each_cpu(i, cpu_map) { 6867 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) { 6868 sd->span_weight = cpumask_weight(sched_domain_span(sd)); 6869 if (sd->flags & SD_OVERLAP) { 6870 if (build_overlap_sched_groups(sd, i)) 6871 goto error; 6872 } else { 6873 if (build_sched_groups(sd, i)) 6874 goto error; 6875 } 6876 } 6877 } 6878 6879 /* Calculate CPU power for physical packages and nodes */ 6880 for (i = nr_cpumask_bits-1; i >= 0; i--) { 6881 if (!cpumask_test_cpu(i, cpu_map)) 6882 continue; 6883 6884 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) { 6885 claim_allocations(i, sd); 6886 init_sched_groups_power(i, sd); 6887 } 6888 } 6889 6890 /* Attach the domains */ 6891 rcu_read_lock(); 6892 for_each_cpu(i, cpu_map) { 6893 sd = *per_cpu_ptr(d.sd, i); 6894 cpu_attach_domain(sd, d.rd, i); 6895 } 6896 rcu_read_unlock(); 6897 6898 ret = 0; 6899 error: 6900 __free_domain_allocs(&d, alloc_state, cpu_map); 6901 return ret; 6902 } 6903 6904 static cpumask_var_t *doms_cur; /* current sched domains */ 6905 static int ndoms_cur; /* number of sched domains in 'doms_cur' */ 6906 static struct sched_domain_attr *dattr_cur; 6907 /* attribues of custom domains in 'doms_cur' */ 6908 6909 /* 6910 * Special case: If a kmalloc of a doms_cur partition (array of 6911 * cpumask) fails, then fallback to a single sched domain, 6912 * as determined by the single cpumask fallback_doms. 6913 */ 6914 static cpumask_var_t fallback_doms; 6915 6916 /* 6917 * arch_update_cpu_topology lets virtualized architectures update the 6918 * cpu core maps. It is supposed to return 1 if the topology changed 6919 * or 0 if it stayed the same. 6920 */ 6921 int __attribute__((weak)) arch_update_cpu_topology(void) 6922 { 6923 return 0; 6924 } 6925 6926 cpumask_var_t *alloc_sched_domains(unsigned int ndoms) 6927 { 6928 int i; 6929 cpumask_var_t *doms; 6930 6931 doms = kmalloc(sizeof(*doms) * ndoms, GFP_KERNEL); 6932 if (!doms) 6933 return NULL; 6934 for (i = 0; i < ndoms; i++) { 6935 if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) { 6936 free_sched_domains(doms, i); 6937 return NULL; 6938 } 6939 } 6940 return doms; 6941 } 6942 6943 void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms) 6944 { 6945 unsigned int i; 6946 for (i = 0; i < ndoms; i++) 6947 free_cpumask_var(doms[i]); 6948 kfree(doms); 6949 } 6950 6951 /* 6952 * Set up scheduler domains and groups. Callers must hold the hotplug lock. 6953 * For now this just excludes isolated cpus, but could be used to 6954 * exclude other special cases in the future. 6955 */ 6956 static int init_sched_domains(const struct cpumask *cpu_map) 6957 { 6958 int err; 6959 6960 arch_update_cpu_topology(); 6961 ndoms_cur = 1; 6962 doms_cur = alloc_sched_domains(ndoms_cur); 6963 if (!doms_cur) 6964 doms_cur = &fallback_doms; 6965 cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map); 6966 err = build_sched_domains(doms_cur[0], NULL); 6967 register_sched_domain_sysctl(); 6968 6969 return err; 6970 } 6971 6972 /* 6973 * Detach sched domains from a group of cpus specified in cpu_map 6974 * These cpus will now be attached to the NULL domain 6975 */ 6976 static void detach_destroy_domains(const struct cpumask *cpu_map) 6977 { 6978 int i; 6979 6980 rcu_read_lock(); 6981 for_each_cpu(i, cpu_map) 6982 cpu_attach_domain(NULL, &def_root_domain, i); 6983 rcu_read_unlock(); 6984 } 6985 6986 /* handle null as "default" */ 6987 static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur, 6988 struct sched_domain_attr *new, int idx_new) 6989 { 6990 struct sched_domain_attr tmp; 6991 6992 /* fast path */ 6993 if (!new && !cur) 6994 return 1; 6995 6996 tmp = SD_ATTR_INIT; 6997 return !memcmp(cur ? (cur + idx_cur) : &tmp, 6998 new ? (new + idx_new) : &tmp, 6999 sizeof(struct sched_domain_attr)); 7000 } 7001 7002 /* 7003 * Partition sched domains as specified by the 'ndoms_new' 7004 * cpumasks in the array doms_new[] of cpumasks. This compares 7005 * doms_new[] to the current sched domain partitioning, doms_cur[]. 7006 * It destroys each deleted domain and builds each new domain. 7007 * 7008 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'. 7009 * The masks don't intersect (don't overlap.) We should setup one 7010 * sched domain for each mask. CPUs not in any of the cpumasks will 7011 * not be load balanced. If the same cpumask appears both in the 7012 * current 'doms_cur' domains and in the new 'doms_new', we can leave 7013 * it as it is. 7014 * 7015 * The passed in 'doms_new' should be allocated using 7016 * alloc_sched_domains. This routine takes ownership of it and will 7017 * free_sched_domains it when done with it. If the caller failed the 7018 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1, 7019 * and partition_sched_domains() will fallback to the single partition 7020 * 'fallback_doms', it also forces the domains to be rebuilt. 7021 * 7022 * If doms_new == NULL it will be replaced with cpu_online_mask. 7023 * ndoms_new == 0 is a special case for destroying existing domains, 7024 * and it will not create the default domain. 7025 * 7026 * Call with hotplug lock held 7027 */ 7028 void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[], 7029 struct sched_domain_attr *dattr_new) 7030 { 7031 int i, j, n; 7032 int new_topology; 7033 7034 mutex_lock(&sched_domains_mutex); 7035 7036 /* always unregister in case we don't destroy any domains */ 7037 unregister_sched_domain_sysctl(); 7038 7039 /* Let architecture update cpu core mappings. */ 7040 new_topology = arch_update_cpu_topology(); 7041 7042 n = doms_new ? ndoms_new : 0; 7043 7044 /* Destroy deleted domains */ 7045 for (i = 0; i < ndoms_cur; i++) { 7046 for (j = 0; j < n && !new_topology; j++) { 7047 if (cpumask_equal(doms_cur[i], doms_new[j]) 7048 && dattrs_equal(dattr_cur, i, dattr_new, j)) 7049 goto match1; 7050 } 7051 /* no match - a current sched domain not in new doms_new[] */ 7052 detach_destroy_domains(doms_cur[i]); 7053 match1: 7054 ; 7055 } 7056 7057 if (doms_new == NULL) { 7058 ndoms_cur = 0; 7059 doms_new = &fallback_doms; 7060 cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map); 7061 WARN_ON_ONCE(dattr_new); 7062 } 7063 7064 /* Build new domains */ 7065 for (i = 0; i < ndoms_new; i++) { 7066 for (j = 0; j < ndoms_cur && !new_topology; j++) { 7067 if (cpumask_equal(doms_new[i], doms_cur[j]) 7068 && dattrs_equal(dattr_new, i, dattr_cur, j)) 7069 goto match2; 7070 } 7071 /* no match - add a new doms_new */ 7072 build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL); 7073 match2: 7074 ; 7075 } 7076 7077 /* Remember the new sched domains */ 7078 if (doms_cur != &fallback_doms) 7079 free_sched_domains(doms_cur, ndoms_cur); 7080 kfree(dattr_cur); /* kfree(NULL) is safe */ 7081 doms_cur = doms_new; 7082 dattr_cur = dattr_new; 7083 ndoms_cur = ndoms_new; 7084 7085 register_sched_domain_sysctl(); 7086 7087 mutex_unlock(&sched_domains_mutex); 7088 } 7089 7090 static int num_cpus_frozen; /* used to mark begin/end of suspend/resume */ 7091 7092 /* 7093 * Update cpusets according to cpu_active mask. If cpusets are 7094 * disabled, cpuset_update_active_cpus() becomes a simple wrapper 7095 * around partition_sched_domains(). 7096 * 7097 * If we come here as part of a suspend/resume, don't touch cpusets because we 7098 * want to restore it back to its original state upon resume anyway. 7099 */ 7100 static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action, 7101 void *hcpu) 7102 { 7103 switch (action) { 7104 case CPU_ONLINE_FROZEN: 7105 case CPU_DOWN_FAILED_FROZEN: 7106 7107 /* 7108 * num_cpus_frozen tracks how many CPUs are involved in suspend 7109 * resume sequence. As long as this is not the last online 7110 * operation in the resume sequence, just build a single sched 7111 * domain, ignoring cpusets. 7112 */ 7113 num_cpus_frozen--; 7114 if (likely(num_cpus_frozen)) { 7115 partition_sched_domains(1, NULL, NULL); 7116 break; 7117 } 7118 7119 /* 7120 * This is the last CPU online operation. So fall through and 7121 * restore the original sched domains by considering the 7122 * cpuset configurations. 7123 */ 7124 7125 case CPU_ONLINE: 7126 case CPU_DOWN_FAILED: 7127 cpuset_update_active_cpus(true); 7128 break; 7129 default: 7130 return NOTIFY_DONE; 7131 } 7132 return NOTIFY_OK; 7133 } 7134 7135 static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action, 7136 void *hcpu) 7137 { 7138 switch (action) { 7139 case CPU_DOWN_PREPARE: 7140 cpuset_update_active_cpus(false); 7141 break; 7142 case CPU_DOWN_PREPARE_FROZEN: 7143 num_cpus_frozen++; 7144 partition_sched_domains(1, NULL, NULL); 7145 break; 7146 default: 7147 return NOTIFY_DONE; 7148 } 7149 return NOTIFY_OK; 7150 } 7151 7152 void __init sched_init_smp(void) 7153 { 7154 cpumask_var_t non_isolated_cpus; 7155 7156 alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL); 7157 alloc_cpumask_var(&fallback_doms, GFP_KERNEL); 7158 7159 sched_init_numa(); 7160 7161 get_online_cpus(); 7162 mutex_lock(&sched_domains_mutex); 7163 init_sched_domains(cpu_active_mask); 7164 cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map); 7165 if (cpumask_empty(non_isolated_cpus)) 7166 cpumask_set_cpu(smp_processor_id(), non_isolated_cpus); 7167 mutex_unlock(&sched_domains_mutex); 7168 put_online_cpus(); 7169 7170 hotcpu_notifier(cpuset_cpu_active, CPU_PRI_CPUSET_ACTIVE); 7171 hotcpu_notifier(cpuset_cpu_inactive, CPU_PRI_CPUSET_INACTIVE); 7172 7173 /* RT runtime code needs to handle some hotplug events */ 7174 hotcpu_notifier(update_runtime, 0); 7175 7176 init_hrtick(); 7177 7178 /* Move init over to a non-isolated CPU */ 7179 if (set_cpus_allowed_ptr(current, non_isolated_cpus) < 0) 7180 BUG(); 7181 sched_init_granularity(); 7182 free_cpumask_var(non_isolated_cpus); 7183 7184 init_sched_rt_class(); 7185 } 7186 #else 7187 void __init sched_init_smp(void) 7188 { 7189 sched_init_granularity(); 7190 } 7191 #endif /* CONFIG_SMP */ 7192 7193 const_debug unsigned int sysctl_timer_migration = 1; 7194 7195 int in_sched_functions(unsigned long addr) 7196 { 7197 return in_lock_functions(addr) || 7198 (addr >= (unsigned long)__sched_text_start 7199 && addr < (unsigned long)__sched_text_end); 7200 } 7201 7202 #ifdef CONFIG_CGROUP_SCHED 7203 struct task_group root_task_group; 7204 LIST_HEAD(task_groups); 7205 #endif 7206 7207 DECLARE_PER_CPU(cpumask_var_t, load_balance_tmpmask); 7208 7209 void __init sched_init(void) 7210 { 7211 int i, j; 7212 unsigned long alloc_size = 0, ptr; 7213 7214 #ifdef CONFIG_FAIR_GROUP_SCHED 7215 alloc_size += 2 * nr_cpu_ids * sizeof(void **); 7216 #endif 7217 #ifdef CONFIG_RT_GROUP_SCHED 7218 alloc_size += 2 * nr_cpu_ids * sizeof(void **); 7219 #endif 7220 #ifdef CONFIG_CPUMASK_OFFSTACK 7221 alloc_size += num_possible_cpus() * cpumask_size(); 7222 #endif 7223 if (alloc_size) { 7224 ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT); 7225 7226 #ifdef CONFIG_FAIR_GROUP_SCHED 7227 root_task_group.se = (struct sched_entity **)ptr; 7228 ptr += nr_cpu_ids * sizeof(void **); 7229 7230 root_task_group.cfs_rq = (struct cfs_rq **)ptr; 7231 ptr += nr_cpu_ids * sizeof(void **); 7232 7233 #endif /* CONFIG_FAIR_GROUP_SCHED */ 7234 #ifdef CONFIG_RT_GROUP_SCHED 7235 root_task_group.rt_se = (struct sched_rt_entity **)ptr; 7236 ptr += nr_cpu_ids * sizeof(void **); 7237 7238 root_task_group.rt_rq = (struct rt_rq **)ptr; 7239 ptr += nr_cpu_ids * sizeof(void **); 7240 7241 #endif /* CONFIG_RT_GROUP_SCHED */ 7242 #ifdef CONFIG_CPUMASK_OFFSTACK 7243 for_each_possible_cpu(i) { 7244 per_cpu(load_balance_tmpmask, i) = (void *)ptr; 7245 ptr += cpumask_size(); 7246 } 7247 #endif /* CONFIG_CPUMASK_OFFSTACK */ 7248 } 7249 7250 #ifdef CONFIG_SMP 7251 init_defrootdomain(); 7252 #endif 7253 7254 init_rt_bandwidth(&def_rt_bandwidth, 7255 global_rt_period(), global_rt_runtime()); 7256 7257 #ifdef CONFIG_RT_GROUP_SCHED 7258 init_rt_bandwidth(&root_task_group.rt_bandwidth, 7259 global_rt_period(), global_rt_runtime()); 7260 #endif /* CONFIG_RT_GROUP_SCHED */ 7261 7262 #ifdef CONFIG_CGROUP_SCHED 7263 list_add(&root_task_group.list, &task_groups); 7264 INIT_LIST_HEAD(&root_task_group.children); 7265 INIT_LIST_HEAD(&root_task_group.siblings); 7266 autogroup_init(&init_task); 7267 7268 #endif /* CONFIG_CGROUP_SCHED */ 7269 7270 #ifdef CONFIG_CGROUP_CPUACCT 7271 root_cpuacct.cpustat = &kernel_cpustat; 7272 root_cpuacct.cpuusage = alloc_percpu(u64); 7273 /* Too early, not expected to fail */ 7274 BUG_ON(!root_cpuacct.cpuusage); 7275 #endif 7276 for_each_possible_cpu(i) { 7277 struct rq *rq; 7278 7279 rq = cpu_rq(i); 7280 raw_spin_lock_init(&rq->lock); 7281 rq->nr_running = 0; 7282 rq->calc_load_active = 0; 7283 rq->calc_load_update = jiffies + LOAD_FREQ; 7284 init_cfs_rq(&rq->cfs); 7285 init_rt_rq(&rq->rt, rq); 7286 #ifdef CONFIG_FAIR_GROUP_SCHED 7287 root_task_group.shares = ROOT_TASK_GROUP_LOAD; 7288 INIT_LIST_HEAD(&rq->leaf_cfs_rq_list); 7289 /* 7290 * How much cpu bandwidth does root_task_group get? 7291 * 7292 * In case of task-groups formed thr' the cgroup filesystem, it 7293 * gets 100% of the cpu resources in the system. This overall 7294 * system cpu resource is divided among the tasks of 7295 * root_task_group and its child task-groups in a fair manner, 7296 * based on each entity's (task or task-group's) weight 7297 * (se->load.weight). 7298 * 7299 * In other words, if root_task_group has 10 tasks of weight 7300 * 1024) and two child groups A0 and A1 (of weight 1024 each), 7301 * then A0's share of the cpu resource is: 7302 * 7303 * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33% 7304 * 7305 * We achieve this by letting root_task_group's tasks sit 7306 * directly in rq->cfs (i.e root_task_group->se[] = NULL). 7307 */ 7308 init_cfs_bandwidth(&root_task_group.cfs_bandwidth); 7309 init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL); 7310 #endif /* CONFIG_FAIR_GROUP_SCHED */ 7311 7312 rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime; 7313 #ifdef CONFIG_RT_GROUP_SCHED 7314 INIT_LIST_HEAD(&rq->leaf_rt_rq_list); 7315 init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL); 7316 #endif 7317 7318 for (j = 0; j < CPU_LOAD_IDX_MAX; j++) 7319 rq->cpu_load[j] = 0; 7320 7321 rq->last_load_update_tick = jiffies; 7322 7323 #ifdef CONFIG_SMP 7324 rq->sd = NULL; 7325 rq->rd = NULL; 7326 rq->cpu_power = SCHED_POWER_SCALE; 7327 rq->post_schedule = 0; 7328 rq->active_balance = 0; 7329 rq->next_balance = jiffies; 7330 rq->push_cpu = 0; 7331 rq->cpu = i; 7332 rq->online = 0; 7333 rq->idle_stamp = 0; 7334 rq->avg_idle = 2*sysctl_sched_migration_cost; 7335 7336 INIT_LIST_HEAD(&rq->cfs_tasks); 7337 7338 rq_attach_root(rq, &def_root_domain); 7339 #ifdef CONFIG_NO_HZ 7340 rq->nohz_flags = 0; 7341 #endif 7342 #endif 7343 init_rq_hrtick(rq); 7344 atomic_set(&rq->nr_iowait, 0); 7345 } 7346 7347 set_load_weight(&init_task); 7348 7349 #ifdef CONFIG_PREEMPT_NOTIFIERS 7350 INIT_HLIST_HEAD(&init_task.preempt_notifiers); 7351 #endif 7352 7353 #ifdef CONFIG_RT_MUTEXES 7354 plist_head_init(&init_task.pi_waiters); 7355 #endif 7356 7357 /* 7358 * The boot idle thread does lazy MMU switching as well: 7359 */ 7360 atomic_inc(&init_mm.mm_count); 7361 enter_lazy_tlb(&init_mm, current); 7362 7363 /* 7364 * Make us the idle thread. Technically, schedule() should not be 7365 * called from this thread, however somewhere below it might be, 7366 * but because we are the idle thread, we just pick up running again 7367 * when this runqueue becomes "idle". 7368 */ 7369 init_idle(current, smp_processor_id()); 7370 7371 calc_load_update = jiffies + LOAD_FREQ; 7372 7373 /* 7374 * During early bootup we pretend to be a normal task: 7375 */ 7376 current->sched_class = &fair_sched_class; 7377 7378 #ifdef CONFIG_SMP 7379 zalloc_cpumask_var(&sched_domains_tmpmask, GFP_NOWAIT); 7380 /* May be allocated at isolcpus cmdline parse time */ 7381 if (cpu_isolated_map == NULL) 7382 zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT); 7383 idle_thread_set_boot_cpu(); 7384 #endif 7385 init_sched_fair_class(); 7386 7387 scheduler_running = 1; 7388 } 7389 7390 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP 7391 static inline int preempt_count_equals(int preempt_offset) 7392 { 7393 int nested = (preempt_count() & ~PREEMPT_ACTIVE) + rcu_preempt_depth(); 7394 7395 return (nested == preempt_offset); 7396 } 7397 7398 void __might_sleep(const char *file, int line, int preempt_offset) 7399 { 7400 static unsigned long prev_jiffy; /* ratelimiting */ 7401 7402 rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */ 7403 if ((preempt_count_equals(preempt_offset) && !irqs_disabled()) || 7404 system_state != SYSTEM_RUNNING || oops_in_progress) 7405 return; 7406 if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy) 7407 return; 7408 prev_jiffy = jiffies; 7409 7410 printk(KERN_ERR 7411 "BUG: sleeping function called from invalid context at %s:%d\n", 7412 file, line); 7413 printk(KERN_ERR 7414 "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n", 7415 in_atomic(), irqs_disabled(), 7416 current->pid, current->comm); 7417 7418 debug_show_held_locks(current); 7419 if (irqs_disabled()) 7420 print_irqtrace_events(current); 7421 dump_stack(); 7422 } 7423 EXPORT_SYMBOL(__might_sleep); 7424 #endif 7425 7426 #ifdef CONFIG_MAGIC_SYSRQ 7427 static void normalize_task(struct rq *rq, struct task_struct *p) 7428 { 7429 const struct sched_class *prev_class = p->sched_class; 7430 int old_prio = p->prio; 7431 int on_rq; 7432 7433 on_rq = p->on_rq; 7434 if (on_rq) 7435 dequeue_task(rq, p, 0); 7436 __setscheduler(rq, p, SCHED_NORMAL, 0); 7437 if (on_rq) { 7438 enqueue_task(rq, p, 0); 7439 resched_task(rq->curr); 7440 } 7441 7442 check_class_changed(rq, p, prev_class, old_prio); 7443 } 7444 7445 void normalize_rt_tasks(void) 7446 { 7447 struct task_struct *g, *p; 7448 unsigned long flags; 7449 struct rq *rq; 7450 7451 read_lock_irqsave(&tasklist_lock, flags); 7452 do_each_thread(g, p) { 7453 /* 7454 * Only normalize user tasks: 7455 */ 7456 if (!p->mm) 7457 continue; 7458 7459 p->se.exec_start = 0; 7460 #ifdef CONFIG_SCHEDSTATS 7461 p->se.statistics.wait_start = 0; 7462 p->se.statistics.sleep_start = 0; 7463 p->se.statistics.block_start = 0; 7464 #endif 7465 7466 if (!rt_task(p)) { 7467 /* 7468 * Renice negative nice level userspace 7469 * tasks back to 0: 7470 */ 7471 if (TASK_NICE(p) < 0 && p->mm) 7472 set_user_nice(p, 0); 7473 continue; 7474 } 7475 7476 raw_spin_lock(&p->pi_lock); 7477 rq = __task_rq_lock(p); 7478 7479 normalize_task(rq, p); 7480 7481 __task_rq_unlock(rq); 7482 raw_spin_unlock(&p->pi_lock); 7483 } while_each_thread(g, p); 7484 7485 read_unlock_irqrestore(&tasklist_lock, flags); 7486 } 7487 7488 #endif /* CONFIG_MAGIC_SYSRQ */ 7489 7490 #if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) 7491 /* 7492 * These functions are only useful for the IA64 MCA handling, or kdb. 7493 * 7494 * They can only be called when the whole system has been 7495 * stopped - every CPU needs to be quiescent, and no scheduling 7496 * activity can take place. Using them for anything else would 7497 * be a serious bug, and as a result, they aren't even visible 7498 * under any other configuration. 7499 */ 7500 7501 /** 7502 * curr_task - return the current task for a given cpu. 7503 * @cpu: the processor in question. 7504 * 7505 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! 7506 */ 7507 struct task_struct *curr_task(int cpu) 7508 { 7509 return cpu_curr(cpu); 7510 } 7511 7512 #endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */ 7513 7514 #ifdef CONFIG_IA64 7515 /** 7516 * set_curr_task - set the current task for a given cpu. 7517 * @cpu: the processor in question. 7518 * @p: the task pointer to set. 7519 * 7520 * Description: This function must only be used when non-maskable interrupts 7521 * are serviced on a separate stack. It allows the architecture to switch the 7522 * notion of the current task on a cpu in a non-blocking manner. This function 7523 * must be called with all CPU's synchronized, and interrupts disabled, the 7524 * and caller must save the original value of the current task (see 7525 * curr_task() above) and restore that value before reenabling interrupts and 7526 * re-starting the system. 7527 * 7528 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! 7529 */ 7530 void set_curr_task(int cpu, struct task_struct *p) 7531 { 7532 cpu_curr(cpu) = p; 7533 } 7534 7535 #endif 7536 7537 #ifdef CONFIG_CGROUP_SCHED 7538 /* task_group_lock serializes the addition/removal of task groups */ 7539 static DEFINE_SPINLOCK(task_group_lock); 7540 7541 static void free_sched_group(struct task_group *tg) 7542 { 7543 free_fair_sched_group(tg); 7544 free_rt_sched_group(tg); 7545 autogroup_free(tg); 7546 kfree(tg); 7547 } 7548 7549 /* allocate runqueue etc for a new task group */ 7550 struct task_group *sched_create_group(struct task_group *parent) 7551 { 7552 struct task_group *tg; 7553 unsigned long flags; 7554 7555 tg = kzalloc(sizeof(*tg), GFP_KERNEL); 7556 if (!tg) 7557 return ERR_PTR(-ENOMEM); 7558 7559 if (!alloc_fair_sched_group(tg, parent)) 7560 goto err; 7561 7562 if (!alloc_rt_sched_group(tg, parent)) 7563 goto err; 7564 7565 spin_lock_irqsave(&task_group_lock, flags); 7566 list_add_rcu(&tg->list, &task_groups); 7567 7568 WARN_ON(!parent); /* root should already exist */ 7569 7570 tg->parent = parent; 7571 INIT_LIST_HEAD(&tg->children); 7572 list_add_rcu(&tg->siblings, &parent->children); 7573 spin_unlock_irqrestore(&task_group_lock, flags); 7574 7575 return tg; 7576 7577 err: 7578 free_sched_group(tg); 7579 return ERR_PTR(-ENOMEM); 7580 } 7581 7582 /* rcu callback to free various structures associated with a task group */ 7583 static void free_sched_group_rcu(struct rcu_head *rhp) 7584 { 7585 /* now it should be safe to free those cfs_rqs */ 7586 free_sched_group(container_of(rhp, struct task_group, rcu)); 7587 } 7588 7589 /* Destroy runqueue etc associated with a task group */ 7590 void sched_destroy_group(struct task_group *tg) 7591 { 7592 unsigned long flags; 7593 int i; 7594 7595 /* end participation in shares distribution */ 7596 for_each_possible_cpu(i) 7597 unregister_fair_sched_group(tg, i); 7598 7599 spin_lock_irqsave(&task_group_lock, flags); 7600 list_del_rcu(&tg->list); 7601 list_del_rcu(&tg->siblings); 7602 spin_unlock_irqrestore(&task_group_lock, flags); 7603 7604 /* wait for possible concurrent references to cfs_rqs complete */ 7605 call_rcu(&tg->rcu, free_sched_group_rcu); 7606 } 7607 7608 /* change task's runqueue when it moves between groups. 7609 * The caller of this function should have put the task in its new group 7610 * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to 7611 * reflect its new group. 7612 */ 7613 void sched_move_task(struct task_struct *tsk) 7614 { 7615 struct task_group *tg; 7616 int on_rq, running; 7617 unsigned long flags; 7618 struct rq *rq; 7619 7620 rq = task_rq_lock(tsk, &flags); 7621 7622 running = task_current(rq, tsk); 7623 on_rq = tsk->on_rq; 7624 7625 if (on_rq) 7626 dequeue_task(rq, tsk, 0); 7627 if (unlikely(running)) 7628 tsk->sched_class->put_prev_task(rq, tsk); 7629 7630 tg = container_of(task_subsys_state_check(tsk, cpu_cgroup_subsys_id, 7631 lockdep_is_held(&tsk->sighand->siglock)), 7632 struct task_group, css); 7633 tg = autogroup_task_group(tsk, tg); 7634 tsk->sched_task_group = tg; 7635 7636 #ifdef CONFIG_FAIR_GROUP_SCHED 7637 if (tsk->sched_class->task_move_group) 7638 tsk->sched_class->task_move_group(tsk, on_rq); 7639 else 7640 #endif 7641 set_task_rq(tsk, task_cpu(tsk)); 7642 7643 if (unlikely(running)) 7644 tsk->sched_class->set_curr_task(rq); 7645 if (on_rq) 7646 enqueue_task(rq, tsk, 0); 7647 7648 task_rq_unlock(rq, tsk, &flags); 7649 } 7650 #endif /* CONFIG_CGROUP_SCHED */ 7651 7652 #if defined(CONFIG_RT_GROUP_SCHED) || defined(CONFIG_CFS_BANDWIDTH) 7653 static unsigned long to_ratio(u64 period, u64 runtime) 7654 { 7655 if (runtime == RUNTIME_INF) 7656 return 1ULL << 20; 7657 7658 return div64_u64(runtime << 20, period); 7659 } 7660 #endif 7661 7662 #ifdef CONFIG_RT_GROUP_SCHED 7663 /* 7664 * Ensure that the real time constraints are schedulable. 7665 */ 7666 static DEFINE_MUTEX(rt_constraints_mutex); 7667 7668 /* Must be called with tasklist_lock held */ 7669 static inline int tg_has_rt_tasks(struct task_group *tg) 7670 { 7671 struct task_struct *g, *p; 7672 7673 do_each_thread(g, p) { 7674 if (rt_task(p) && task_rq(p)->rt.tg == tg) 7675 return 1; 7676 } while_each_thread(g, p); 7677 7678 return 0; 7679 } 7680 7681 struct rt_schedulable_data { 7682 struct task_group *tg; 7683 u64 rt_period; 7684 u64 rt_runtime; 7685 }; 7686 7687 static int tg_rt_schedulable(struct task_group *tg, void *data) 7688 { 7689 struct rt_schedulable_data *d = data; 7690 struct task_group *child; 7691 unsigned long total, sum = 0; 7692 u64 period, runtime; 7693 7694 period = ktime_to_ns(tg->rt_bandwidth.rt_period); 7695 runtime = tg->rt_bandwidth.rt_runtime; 7696 7697 if (tg == d->tg) { 7698 period = d->rt_period; 7699 runtime = d->rt_runtime; 7700 } 7701 7702 /* 7703 * Cannot have more runtime than the period. 7704 */ 7705 if (runtime > period && runtime != RUNTIME_INF) 7706 return -EINVAL; 7707 7708 /* 7709 * Ensure we don't starve existing RT tasks. 7710 */ 7711 if (rt_bandwidth_enabled() && !runtime && tg_has_rt_tasks(tg)) 7712 return -EBUSY; 7713 7714 total = to_ratio(period, runtime); 7715 7716 /* 7717 * Nobody can have more than the global setting allows. 7718 */ 7719 if (total > to_ratio(global_rt_period(), global_rt_runtime())) 7720 return -EINVAL; 7721 7722 /* 7723 * The sum of our children's runtime should not exceed our own. 7724 */ 7725 list_for_each_entry_rcu(child, &tg->children, siblings) { 7726 period = ktime_to_ns(child->rt_bandwidth.rt_period); 7727 runtime = child->rt_bandwidth.rt_runtime; 7728 7729 if (child == d->tg) { 7730 period = d->rt_period; 7731 runtime = d->rt_runtime; 7732 } 7733 7734 sum += to_ratio(period, runtime); 7735 } 7736 7737 if (sum > total) 7738 return -EINVAL; 7739 7740 return 0; 7741 } 7742 7743 static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime) 7744 { 7745 int ret; 7746 7747 struct rt_schedulable_data data = { 7748 .tg = tg, 7749 .rt_period = period, 7750 .rt_runtime = runtime, 7751 }; 7752 7753 rcu_read_lock(); 7754 ret = walk_tg_tree(tg_rt_schedulable, tg_nop, &data); 7755 rcu_read_unlock(); 7756 7757 return ret; 7758 } 7759 7760 static int tg_set_rt_bandwidth(struct task_group *tg, 7761 u64 rt_period, u64 rt_runtime) 7762 { 7763 int i, err = 0; 7764 7765 mutex_lock(&rt_constraints_mutex); 7766 read_lock(&tasklist_lock); 7767 err = __rt_schedulable(tg, rt_period, rt_runtime); 7768 if (err) 7769 goto unlock; 7770 7771 raw_spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock); 7772 tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period); 7773 tg->rt_bandwidth.rt_runtime = rt_runtime; 7774 7775 for_each_possible_cpu(i) { 7776 struct rt_rq *rt_rq = tg->rt_rq[i]; 7777 7778 raw_spin_lock(&rt_rq->rt_runtime_lock); 7779 rt_rq->rt_runtime = rt_runtime; 7780 raw_spin_unlock(&rt_rq->rt_runtime_lock); 7781 } 7782 raw_spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock); 7783 unlock: 7784 read_unlock(&tasklist_lock); 7785 mutex_unlock(&rt_constraints_mutex); 7786 7787 return err; 7788 } 7789 7790 int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us) 7791 { 7792 u64 rt_runtime, rt_period; 7793 7794 rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period); 7795 rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC; 7796 if (rt_runtime_us < 0) 7797 rt_runtime = RUNTIME_INF; 7798 7799 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime); 7800 } 7801 7802 long sched_group_rt_runtime(struct task_group *tg) 7803 { 7804 u64 rt_runtime_us; 7805 7806 if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF) 7807 return -1; 7808 7809 rt_runtime_us = tg->rt_bandwidth.rt_runtime; 7810 do_div(rt_runtime_us, NSEC_PER_USEC); 7811 return rt_runtime_us; 7812 } 7813 7814 int sched_group_set_rt_period(struct task_group *tg, long rt_period_us) 7815 { 7816 u64 rt_runtime, rt_period; 7817 7818 rt_period = (u64)rt_period_us * NSEC_PER_USEC; 7819 rt_runtime = tg->rt_bandwidth.rt_runtime; 7820 7821 if (rt_period == 0) 7822 return -EINVAL; 7823 7824 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime); 7825 } 7826 7827 long sched_group_rt_period(struct task_group *tg) 7828 { 7829 u64 rt_period_us; 7830 7831 rt_period_us = ktime_to_ns(tg->rt_bandwidth.rt_period); 7832 do_div(rt_period_us, NSEC_PER_USEC); 7833 return rt_period_us; 7834 } 7835 7836 static int sched_rt_global_constraints(void) 7837 { 7838 u64 runtime, period; 7839 int ret = 0; 7840 7841 if (sysctl_sched_rt_period <= 0) 7842 return -EINVAL; 7843 7844 runtime = global_rt_runtime(); 7845 period = global_rt_period(); 7846 7847 /* 7848 * Sanity check on the sysctl variables. 7849 */ 7850 if (runtime > period && runtime != RUNTIME_INF) 7851 return -EINVAL; 7852 7853 mutex_lock(&rt_constraints_mutex); 7854 read_lock(&tasklist_lock); 7855 ret = __rt_schedulable(NULL, 0, 0); 7856 read_unlock(&tasklist_lock); 7857 mutex_unlock(&rt_constraints_mutex); 7858 7859 return ret; 7860 } 7861 7862 int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk) 7863 { 7864 /* Don't accept realtime tasks when there is no way for them to run */ 7865 if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0) 7866 return 0; 7867 7868 return 1; 7869 } 7870 7871 #else /* !CONFIG_RT_GROUP_SCHED */ 7872 static int sched_rt_global_constraints(void) 7873 { 7874 unsigned long flags; 7875 int i; 7876 7877 if (sysctl_sched_rt_period <= 0) 7878 return -EINVAL; 7879 7880 /* 7881 * There's always some RT tasks in the root group 7882 * -- migration, kstopmachine etc.. 7883 */ 7884 if (sysctl_sched_rt_runtime == 0) 7885 return -EBUSY; 7886 7887 raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags); 7888 for_each_possible_cpu(i) { 7889 struct rt_rq *rt_rq = &cpu_rq(i)->rt; 7890 7891 raw_spin_lock(&rt_rq->rt_runtime_lock); 7892 rt_rq->rt_runtime = global_rt_runtime(); 7893 raw_spin_unlock(&rt_rq->rt_runtime_lock); 7894 } 7895 raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags); 7896 7897 return 0; 7898 } 7899 #endif /* CONFIG_RT_GROUP_SCHED */ 7900 7901 int sched_rt_handler(struct ctl_table *table, int write, 7902 void __user *buffer, size_t *lenp, 7903 loff_t *ppos) 7904 { 7905 int ret; 7906 int old_period, old_runtime; 7907 static DEFINE_MUTEX(mutex); 7908 7909 mutex_lock(&mutex); 7910 old_period = sysctl_sched_rt_period; 7911 old_runtime = sysctl_sched_rt_runtime; 7912 7913 ret = proc_dointvec(table, write, buffer, lenp, ppos); 7914 7915 if (!ret && write) { 7916 ret = sched_rt_global_constraints(); 7917 if (ret) { 7918 sysctl_sched_rt_period = old_period; 7919 sysctl_sched_rt_runtime = old_runtime; 7920 } else { 7921 def_rt_bandwidth.rt_runtime = global_rt_runtime(); 7922 def_rt_bandwidth.rt_period = 7923 ns_to_ktime(global_rt_period()); 7924 } 7925 } 7926 mutex_unlock(&mutex); 7927 7928 return ret; 7929 } 7930 7931 #ifdef CONFIG_CGROUP_SCHED 7932 7933 /* return corresponding task_group object of a cgroup */ 7934 static inline struct task_group *cgroup_tg(struct cgroup *cgrp) 7935 { 7936 return container_of(cgroup_subsys_state(cgrp, cpu_cgroup_subsys_id), 7937 struct task_group, css); 7938 } 7939 7940 static struct cgroup_subsys_state *cpu_cgroup_create(struct cgroup *cgrp) 7941 { 7942 struct task_group *tg, *parent; 7943 7944 if (!cgrp->parent) { 7945 /* This is early initialization for the top cgroup */ 7946 return &root_task_group.css; 7947 } 7948 7949 parent = cgroup_tg(cgrp->parent); 7950 tg = sched_create_group(parent); 7951 if (IS_ERR(tg)) 7952 return ERR_PTR(-ENOMEM); 7953 7954 return &tg->css; 7955 } 7956 7957 static void cpu_cgroup_destroy(struct cgroup *cgrp) 7958 { 7959 struct task_group *tg = cgroup_tg(cgrp); 7960 7961 sched_destroy_group(tg); 7962 } 7963 7964 static int cpu_cgroup_can_attach(struct cgroup *cgrp, 7965 struct cgroup_taskset *tset) 7966 { 7967 struct task_struct *task; 7968 7969 cgroup_taskset_for_each(task, cgrp, tset) { 7970 #ifdef CONFIG_RT_GROUP_SCHED 7971 if (!sched_rt_can_attach(cgroup_tg(cgrp), task)) 7972 return -EINVAL; 7973 #else 7974 /* We don't support RT-tasks being in separate groups */ 7975 if (task->sched_class != &fair_sched_class) 7976 return -EINVAL; 7977 #endif 7978 } 7979 return 0; 7980 } 7981 7982 static void cpu_cgroup_attach(struct cgroup *cgrp, 7983 struct cgroup_taskset *tset) 7984 { 7985 struct task_struct *task; 7986 7987 cgroup_taskset_for_each(task, cgrp, tset) 7988 sched_move_task(task); 7989 } 7990 7991 static void 7992 cpu_cgroup_exit(struct cgroup *cgrp, struct cgroup *old_cgrp, 7993 struct task_struct *task) 7994 { 7995 /* 7996 * cgroup_exit() is called in the copy_process() failure path. 7997 * Ignore this case since the task hasn't ran yet, this avoids 7998 * trying to poke a half freed task state from generic code. 7999 */ 8000 if (!(task->flags & PF_EXITING)) 8001 return; 8002 8003 sched_move_task(task); 8004 } 8005 8006 #ifdef CONFIG_FAIR_GROUP_SCHED 8007 static int cpu_shares_write_u64(struct cgroup *cgrp, struct cftype *cftype, 8008 u64 shareval) 8009 { 8010 return sched_group_set_shares(cgroup_tg(cgrp), scale_load(shareval)); 8011 } 8012 8013 static u64 cpu_shares_read_u64(struct cgroup *cgrp, struct cftype *cft) 8014 { 8015 struct task_group *tg = cgroup_tg(cgrp); 8016 8017 return (u64) scale_load_down(tg->shares); 8018 } 8019 8020 #ifdef CONFIG_CFS_BANDWIDTH 8021 static DEFINE_MUTEX(cfs_constraints_mutex); 8022 8023 const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */ 8024 const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */ 8025 8026 static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime); 8027 8028 static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota) 8029 { 8030 int i, ret = 0, runtime_enabled, runtime_was_enabled; 8031 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; 8032 8033 if (tg == &root_task_group) 8034 return -EINVAL; 8035 8036 /* 8037 * Ensure we have at some amount of bandwidth every period. This is 8038 * to prevent reaching a state of large arrears when throttled via 8039 * entity_tick() resulting in prolonged exit starvation. 8040 */ 8041 if (quota < min_cfs_quota_period || period < min_cfs_quota_period) 8042 return -EINVAL; 8043 8044 /* 8045 * Likewise, bound things on the otherside by preventing insane quota 8046 * periods. This also allows us to normalize in computing quota 8047 * feasibility. 8048 */ 8049 if (period > max_cfs_quota_period) 8050 return -EINVAL; 8051 8052 mutex_lock(&cfs_constraints_mutex); 8053 ret = __cfs_schedulable(tg, period, quota); 8054 if (ret) 8055 goto out_unlock; 8056 8057 runtime_enabled = quota != RUNTIME_INF; 8058 runtime_was_enabled = cfs_b->quota != RUNTIME_INF; 8059 account_cfs_bandwidth_used(runtime_enabled, runtime_was_enabled); 8060 raw_spin_lock_irq(&cfs_b->lock); 8061 cfs_b->period = ns_to_ktime(period); 8062 cfs_b->quota = quota; 8063 8064 __refill_cfs_bandwidth_runtime(cfs_b); 8065 /* restart the period timer (if active) to handle new period expiry */ 8066 if (runtime_enabled && cfs_b->timer_active) { 8067 /* force a reprogram */ 8068 cfs_b->timer_active = 0; 8069 __start_cfs_bandwidth(cfs_b); 8070 } 8071 raw_spin_unlock_irq(&cfs_b->lock); 8072 8073 for_each_possible_cpu(i) { 8074 struct cfs_rq *cfs_rq = tg->cfs_rq[i]; 8075 struct rq *rq = cfs_rq->rq; 8076 8077 raw_spin_lock_irq(&rq->lock); 8078 cfs_rq->runtime_enabled = runtime_enabled; 8079 cfs_rq->runtime_remaining = 0; 8080 8081 if (cfs_rq->throttled) 8082 unthrottle_cfs_rq(cfs_rq); 8083 raw_spin_unlock_irq(&rq->lock); 8084 } 8085 out_unlock: 8086 mutex_unlock(&cfs_constraints_mutex); 8087 8088 return ret; 8089 } 8090 8091 int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us) 8092 { 8093 u64 quota, period; 8094 8095 period = ktime_to_ns(tg->cfs_bandwidth.period); 8096 if (cfs_quota_us < 0) 8097 quota = RUNTIME_INF; 8098 else 8099 quota = (u64)cfs_quota_us * NSEC_PER_USEC; 8100 8101 return tg_set_cfs_bandwidth(tg, period, quota); 8102 } 8103 8104 long tg_get_cfs_quota(struct task_group *tg) 8105 { 8106 u64 quota_us; 8107 8108 if (tg->cfs_bandwidth.quota == RUNTIME_INF) 8109 return -1; 8110 8111 quota_us = tg->cfs_bandwidth.quota; 8112 do_div(quota_us, NSEC_PER_USEC); 8113 8114 return quota_us; 8115 } 8116 8117 int tg_set_cfs_period(struct task_group *tg, long cfs_period_us) 8118 { 8119 u64 quota, period; 8120 8121 period = (u64)cfs_period_us * NSEC_PER_USEC; 8122 quota = tg->cfs_bandwidth.quota; 8123 8124 return tg_set_cfs_bandwidth(tg, period, quota); 8125 } 8126 8127 long tg_get_cfs_period(struct task_group *tg) 8128 { 8129 u64 cfs_period_us; 8130 8131 cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period); 8132 do_div(cfs_period_us, NSEC_PER_USEC); 8133 8134 return cfs_period_us; 8135 } 8136 8137 static s64 cpu_cfs_quota_read_s64(struct cgroup *cgrp, struct cftype *cft) 8138 { 8139 return tg_get_cfs_quota(cgroup_tg(cgrp)); 8140 } 8141 8142 static int cpu_cfs_quota_write_s64(struct cgroup *cgrp, struct cftype *cftype, 8143 s64 cfs_quota_us) 8144 { 8145 return tg_set_cfs_quota(cgroup_tg(cgrp), cfs_quota_us); 8146 } 8147 8148 static u64 cpu_cfs_period_read_u64(struct cgroup *cgrp, struct cftype *cft) 8149 { 8150 return tg_get_cfs_period(cgroup_tg(cgrp)); 8151 } 8152 8153 static int cpu_cfs_period_write_u64(struct cgroup *cgrp, struct cftype *cftype, 8154 u64 cfs_period_us) 8155 { 8156 return tg_set_cfs_period(cgroup_tg(cgrp), cfs_period_us); 8157 } 8158 8159 struct cfs_schedulable_data { 8160 struct task_group *tg; 8161 u64 period, quota; 8162 }; 8163 8164 /* 8165 * normalize group quota/period to be quota/max_period 8166 * note: units are usecs 8167 */ 8168 static u64 normalize_cfs_quota(struct task_group *tg, 8169 struct cfs_schedulable_data *d) 8170 { 8171 u64 quota, period; 8172 8173 if (tg == d->tg) { 8174 period = d->period; 8175 quota = d->quota; 8176 } else { 8177 period = tg_get_cfs_period(tg); 8178 quota = tg_get_cfs_quota(tg); 8179 } 8180 8181 /* note: these should typically be equivalent */ 8182 if (quota == RUNTIME_INF || quota == -1) 8183 return RUNTIME_INF; 8184 8185 return to_ratio(period, quota); 8186 } 8187 8188 static int tg_cfs_schedulable_down(struct task_group *tg, void *data) 8189 { 8190 struct cfs_schedulable_data *d = data; 8191 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; 8192 s64 quota = 0, parent_quota = -1; 8193 8194 if (!tg->parent) { 8195 quota = RUNTIME_INF; 8196 } else { 8197 struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth; 8198 8199 quota = normalize_cfs_quota(tg, d); 8200 parent_quota = parent_b->hierarchal_quota; 8201 8202 /* 8203 * ensure max(child_quota) <= parent_quota, inherit when no 8204 * limit is set 8205 */ 8206 if (quota == RUNTIME_INF) 8207 quota = parent_quota; 8208 else if (parent_quota != RUNTIME_INF && quota > parent_quota) 8209 return -EINVAL; 8210 } 8211 cfs_b->hierarchal_quota = quota; 8212 8213 return 0; 8214 } 8215 8216 static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota) 8217 { 8218 int ret; 8219 struct cfs_schedulable_data data = { 8220 .tg = tg, 8221 .period = period, 8222 .quota = quota, 8223 }; 8224 8225 if (quota != RUNTIME_INF) { 8226 do_div(data.period, NSEC_PER_USEC); 8227 do_div(data.quota, NSEC_PER_USEC); 8228 } 8229 8230 rcu_read_lock(); 8231 ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data); 8232 rcu_read_unlock(); 8233 8234 return ret; 8235 } 8236 8237 static int cpu_stats_show(struct cgroup *cgrp, struct cftype *cft, 8238 struct cgroup_map_cb *cb) 8239 { 8240 struct task_group *tg = cgroup_tg(cgrp); 8241 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; 8242 8243 cb->fill(cb, "nr_periods", cfs_b->nr_periods); 8244 cb->fill(cb, "nr_throttled", cfs_b->nr_throttled); 8245 cb->fill(cb, "throttled_time", cfs_b->throttled_time); 8246 8247 return 0; 8248 } 8249 #endif /* CONFIG_CFS_BANDWIDTH */ 8250 #endif /* CONFIG_FAIR_GROUP_SCHED */ 8251 8252 #ifdef CONFIG_RT_GROUP_SCHED 8253 static int cpu_rt_runtime_write(struct cgroup *cgrp, struct cftype *cft, 8254 s64 val) 8255 { 8256 return sched_group_set_rt_runtime(cgroup_tg(cgrp), val); 8257 } 8258 8259 static s64 cpu_rt_runtime_read(struct cgroup *cgrp, struct cftype *cft) 8260 { 8261 return sched_group_rt_runtime(cgroup_tg(cgrp)); 8262 } 8263 8264 static int cpu_rt_period_write_uint(struct cgroup *cgrp, struct cftype *cftype, 8265 u64 rt_period_us) 8266 { 8267 return sched_group_set_rt_period(cgroup_tg(cgrp), rt_period_us); 8268 } 8269 8270 static u64 cpu_rt_period_read_uint(struct cgroup *cgrp, struct cftype *cft) 8271 { 8272 return sched_group_rt_period(cgroup_tg(cgrp)); 8273 } 8274 #endif /* CONFIG_RT_GROUP_SCHED */ 8275 8276 static struct cftype cpu_files[] = { 8277 #ifdef CONFIG_FAIR_GROUP_SCHED 8278 { 8279 .name = "shares", 8280 .read_u64 = cpu_shares_read_u64, 8281 .write_u64 = cpu_shares_write_u64, 8282 }, 8283 #endif 8284 #ifdef CONFIG_CFS_BANDWIDTH 8285 { 8286 .name = "cfs_quota_us", 8287 .read_s64 = cpu_cfs_quota_read_s64, 8288 .write_s64 = cpu_cfs_quota_write_s64, 8289 }, 8290 { 8291 .name = "cfs_period_us", 8292 .read_u64 = cpu_cfs_period_read_u64, 8293 .write_u64 = cpu_cfs_period_write_u64, 8294 }, 8295 { 8296 .name = "stat", 8297 .read_map = cpu_stats_show, 8298 }, 8299 #endif 8300 #ifdef CONFIG_RT_GROUP_SCHED 8301 { 8302 .name = "rt_runtime_us", 8303 .read_s64 = cpu_rt_runtime_read, 8304 .write_s64 = cpu_rt_runtime_write, 8305 }, 8306 { 8307 .name = "rt_period_us", 8308 .read_u64 = cpu_rt_period_read_uint, 8309 .write_u64 = cpu_rt_period_write_uint, 8310 }, 8311 #endif 8312 { } /* terminate */ 8313 }; 8314 8315 struct cgroup_subsys cpu_cgroup_subsys = { 8316 .name = "cpu", 8317 .create = cpu_cgroup_create, 8318 .destroy = cpu_cgroup_destroy, 8319 .can_attach = cpu_cgroup_can_attach, 8320 .attach = cpu_cgroup_attach, 8321 .exit = cpu_cgroup_exit, 8322 .subsys_id = cpu_cgroup_subsys_id, 8323 .base_cftypes = cpu_files, 8324 .early_init = 1, 8325 }; 8326 8327 #endif /* CONFIG_CGROUP_SCHED */ 8328 8329 #ifdef CONFIG_CGROUP_CPUACCT 8330 8331 /* 8332 * CPU accounting code for task groups. 8333 * 8334 * Based on the work by Paul Menage (menage@google.com) and Balbir Singh 8335 * (balbir@in.ibm.com). 8336 */ 8337 8338 /* create a new cpu accounting group */ 8339 static struct cgroup_subsys_state *cpuacct_create(struct cgroup *cgrp) 8340 { 8341 struct cpuacct *ca; 8342 8343 if (!cgrp->parent) 8344 return &root_cpuacct.css; 8345 8346 ca = kzalloc(sizeof(*ca), GFP_KERNEL); 8347 if (!ca) 8348 goto out; 8349 8350 ca->cpuusage = alloc_percpu(u64); 8351 if (!ca->cpuusage) 8352 goto out_free_ca; 8353 8354 ca->cpustat = alloc_percpu(struct kernel_cpustat); 8355 if (!ca->cpustat) 8356 goto out_free_cpuusage; 8357 8358 return &ca->css; 8359 8360 out_free_cpuusage: 8361 free_percpu(ca->cpuusage); 8362 out_free_ca: 8363 kfree(ca); 8364 out: 8365 return ERR_PTR(-ENOMEM); 8366 } 8367 8368 /* destroy an existing cpu accounting group */ 8369 static void cpuacct_destroy(struct cgroup *cgrp) 8370 { 8371 struct cpuacct *ca = cgroup_ca(cgrp); 8372 8373 free_percpu(ca->cpustat); 8374 free_percpu(ca->cpuusage); 8375 kfree(ca); 8376 } 8377 8378 static u64 cpuacct_cpuusage_read(struct cpuacct *ca, int cpu) 8379 { 8380 u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu); 8381 u64 data; 8382 8383 #ifndef CONFIG_64BIT 8384 /* 8385 * Take rq->lock to make 64-bit read safe on 32-bit platforms. 8386 */ 8387 raw_spin_lock_irq(&cpu_rq(cpu)->lock); 8388 data = *cpuusage; 8389 raw_spin_unlock_irq(&cpu_rq(cpu)->lock); 8390 #else 8391 data = *cpuusage; 8392 #endif 8393 8394 return data; 8395 } 8396 8397 static void cpuacct_cpuusage_write(struct cpuacct *ca, int cpu, u64 val) 8398 { 8399 u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu); 8400 8401 #ifndef CONFIG_64BIT 8402 /* 8403 * Take rq->lock to make 64-bit write safe on 32-bit platforms. 8404 */ 8405 raw_spin_lock_irq(&cpu_rq(cpu)->lock); 8406 *cpuusage = val; 8407 raw_spin_unlock_irq(&cpu_rq(cpu)->lock); 8408 #else 8409 *cpuusage = val; 8410 #endif 8411 } 8412 8413 /* return total cpu usage (in nanoseconds) of a group */ 8414 static u64 cpuusage_read(struct cgroup *cgrp, struct cftype *cft) 8415 { 8416 struct cpuacct *ca = cgroup_ca(cgrp); 8417 u64 totalcpuusage = 0; 8418 int i; 8419 8420 for_each_present_cpu(i) 8421 totalcpuusage += cpuacct_cpuusage_read(ca, i); 8422 8423 return totalcpuusage; 8424 } 8425 8426 static int cpuusage_write(struct cgroup *cgrp, struct cftype *cftype, 8427 u64 reset) 8428 { 8429 struct cpuacct *ca = cgroup_ca(cgrp); 8430 int err = 0; 8431 int i; 8432 8433 if (reset) { 8434 err = -EINVAL; 8435 goto out; 8436 } 8437 8438 for_each_present_cpu(i) 8439 cpuacct_cpuusage_write(ca, i, 0); 8440 8441 out: 8442 return err; 8443 } 8444 8445 static int cpuacct_percpu_seq_read(struct cgroup *cgroup, struct cftype *cft, 8446 struct seq_file *m) 8447 { 8448 struct cpuacct *ca = cgroup_ca(cgroup); 8449 u64 percpu; 8450 int i; 8451 8452 for_each_present_cpu(i) { 8453 percpu = cpuacct_cpuusage_read(ca, i); 8454 seq_printf(m, "%llu ", (unsigned long long) percpu); 8455 } 8456 seq_printf(m, "\n"); 8457 return 0; 8458 } 8459 8460 static const char *cpuacct_stat_desc[] = { 8461 [CPUACCT_STAT_USER] = "user", 8462 [CPUACCT_STAT_SYSTEM] = "system", 8463 }; 8464 8465 static int cpuacct_stats_show(struct cgroup *cgrp, struct cftype *cft, 8466 struct cgroup_map_cb *cb) 8467 { 8468 struct cpuacct *ca = cgroup_ca(cgrp); 8469 int cpu; 8470 s64 val = 0; 8471 8472 for_each_online_cpu(cpu) { 8473 struct kernel_cpustat *kcpustat = per_cpu_ptr(ca->cpustat, cpu); 8474 val += kcpustat->cpustat[CPUTIME_USER]; 8475 val += kcpustat->cpustat[CPUTIME_NICE]; 8476 } 8477 val = cputime64_to_clock_t(val); 8478 cb->fill(cb, cpuacct_stat_desc[CPUACCT_STAT_USER], val); 8479 8480 val = 0; 8481 for_each_online_cpu(cpu) { 8482 struct kernel_cpustat *kcpustat = per_cpu_ptr(ca->cpustat, cpu); 8483 val += kcpustat->cpustat[CPUTIME_SYSTEM]; 8484 val += kcpustat->cpustat[CPUTIME_IRQ]; 8485 val += kcpustat->cpustat[CPUTIME_SOFTIRQ]; 8486 } 8487 8488 val = cputime64_to_clock_t(val); 8489 cb->fill(cb, cpuacct_stat_desc[CPUACCT_STAT_SYSTEM], val); 8490 8491 return 0; 8492 } 8493 8494 static struct cftype files[] = { 8495 { 8496 .name = "usage", 8497 .read_u64 = cpuusage_read, 8498 .write_u64 = cpuusage_write, 8499 }, 8500 { 8501 .name = "usage_percpu", 8502 .read_seq_string = cpuacct_percpu_seq_read, 8503 }, 8504 { 8505 .name = "stat", 8506 .read_map = cpuacct_stats_show, 8507 }, 8508 { } /* terminate */ 8509 }; 8510 8511 /* 8512 * charge this task's execution time to its accounting group. 8513 * 8514 * called with rq->lock held. 8515 */ 8516 void cpuacct_charge(struct task_struct *tsk, u64 cputime) 8517 { 8518 struct cpuacct *ca; 8519 int cpu; 8520 8521 if (unlikely(!cpuacct_subsys.active)) 8522 return; 8523 8524 cpu = task_cpu(tsk); 8525 8526 rcu_read_lock(); 8527 8528 ca = task_ca(tsk); 8529 8530 for (; ca; ca = parent_ca(ca)) { 8531 u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu); 8532 *cpuusage += cputime; 8533 } 8534 8535 rcu_read_unlock(); 8536 } 8537 8538 struct cgroup_subsys cpuacct_subsys = { 8539 .name = "cpuacct", 8540 .create = cpuacct_create, 8541 .destroy = cpuacct_destroy, 8542 .subsys_id = cpuacct_subsys_id, 8543 .base_cftypes = files, 8544 }; 8545 #endif /* CONFIG_CGROUP_CPUACCT */ 8546