core.c revision f3e947867478af9a12b9956bcd000ac7613a8a95
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 91void 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 111DEFINE_MUTEX(sched_domains_mutex); 112DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues); 113 114static void update_rq_clock_task(struct rq *rq, s64 delta); 115 116void 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 135const_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 145static const char * const sched_feat_names[] = { 146#include "features.h" 147}; 148 149#undef SCHED_FEAT 150 151static 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 173struct static_key sched_feat_keys[__SCHED_FEAT_NR] = { 174#include "features.h" 175}; 176 177#undef SCHED_FEAT 178 179static 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 185static 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 191static void sched_feat_disable(int i) { }; 192static void sched_feat_enable(int i) { }; 193#endif /* HAVE_JUMP_LABEL */ 194 195static ssize_t 196sched_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 239static int sched_feat_open(struct inode *inode, struct file *filp) 240{ 241 return single_open(filp, sched_feat_show, NULL); 242} 243 244static 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 252static __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} 259late_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 */ 266const_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 */ 274const_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 */ 280unsigned 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 */ 288int sysctl_sched_rt_runtime = 950000; 289 290 291 292/* 293 * __task_rq_lock - lock the rq @p resides on. 294 */ 295static 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 */ 314static 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 331static void __task_rq_unlock(struct rq *rq) 332 __releases(rq->lock) 333{ 334 raw_spin_unlock(&rq->lock); 335} 336 337static inline void 338task_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 */ 349static 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 373static 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 */ 383static 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 */ 401static 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 */ 416void 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 431static int 432hotplug_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 450static __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 */ 460void 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 466static inline void init_hrtick(void) 467{ 468} 469#endif /* CONFIG_SMP */ 470 471static 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 */ 485static inline void hrtick_clear(struct rq *rq) 486{ 487} 488 489static inline void init_rq_hrtick(struct rq *rq) 490{ 491} 492 493static 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 511void 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 532void 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 */ 552int 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 } 567unlock: 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 */ 581void 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 611static 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 619static inline bool got_nohz_idle_kick(void) 620{ 621 return false; 622} 623 624#endif /* CONFIG_NO_HZ */ 625 626void 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 */ 643void 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 */ 658int 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 666down: 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 674up: 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; 685out: 686 return ret; 687} 688 689int tg_nop(struct task_group *tg, void *data) 690{ 691 return 0; 692} 693#endif 694 695static 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 713static 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 720static 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 727void 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 735void 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 743static void update_rq_clock_task(struct rq *rq, s64 delta) 744{ 745/* 746 * In theory, the compile should just see 0 here, and optimize out the call 747 * to sched_rt_avg_update. But I don't trust it... 748 */ 749#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING) 750 s64 steal = 0, irq_delta = 0; 751#endif 752#ifdef CONFIG_IRQ_TIME_ACCOUNTING 753 irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time; 754 755 /* 756 * Since irq_time is only updated on {soft,}irq_exit, we might run into 757 * this case when a previous update_rq_clock() happened inside a 758 * {soft,}irq region. 759 * 760 * When this happens, we stop ->clock_task and only update the 761 * prev_irq_time stamp to account for the part that fit, so that a next 762 * update will consume the rest. This ensures ->clock_task is 763 * monotonic. 764 * 765 * It does however cause some slight miss-attribution of {soft,}irq 766 * time, a more accurate solution would be to update the irq_time using 767 * the current rq->clock timestamp, except that would require using 768 * atomic ops. 769 */ 770 if (irq_delta > delta) 771 irq_delta = delta; 772 773 rq->prev_irq_time += irq_delta; 774 delta -= irq_delta; 775#endif 776#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING 777 if (static_key_false((¶virt_steal_rq_enabled))) { 778 u64 st; 779 780 steal = paravirt_steal_clock(cpu_of(rq)); 781 steal -= rq->prev_steal_time_rq; 782 783 if (unlikely(steal > delta)) 784 steal = delta; 785 786 st = steal_ticks(steal); 787 steal = st * TICK_NSEC; 788 789 rq->prev_steal_time_rq += steal; 790 791 delta -= steal; 792 } 793#endif 794 795 rq->clock_task += delta; 796 797#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING) 798 if ((irq_delta + steal) && sched_feat(NONTASK_POWER)) 799 sched_rt_avg_update(rq, irq_delta + steal); 800#endif 801} 802 803void sched_set_stop_task(int cpu, struct task_struct *stop) 804{ 805 struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 }; 806 struct task_struct *old_stop = cpu_rq(cpu)->stop; 807 808 if (stop) { 809 /* 810 * Make it appear like a SCHED_FIFO task, its something 811 * userspace knows about and won't get confused about. 812 * 813 * Also, it will make PI more or less work without too 814 * much confusion -- but then, stop work should not 815 * rely on PI working anyway. 816 */ 817 sched_setscheduler_nocheck(stop, SCHED_FIFO, ¶m); 818 819 stop->sched_class = &stop_sched_class; 820 } 821 822 cpu_rq(cpu)->stop = stop; 823 824 if (old_stop) { 825 /* 826 * Reset it back to a normal scheduling class so that 827 * it can die in pieces. 828 */ 829 old_stop->sched_class = &rt_sched_class; 830 } 831} 832 833/* 834 * __normal_prio - return the priority that is based on the static prio 835 */ 836static inline int __normal_prio(struct task_struct *p) 837{ 838 return p->static_prio; 839} 840 841/* 842 * Calculate the expected normal priority: i.e. priority 843 * without taking RT-inheritance into account. Might be 844 * boosted by interactivity modifiers. Changes upon fork, 845 * setprio syscalls, and whenever the interactivity 846 * estimator recalculates. 847 */ 848static inline int normal_prio(struct task_struct *p) 849{ 850 int prio; 851 852 if (task_has_rt_policy(p)) 853 prio = MAX_RT_PRIO-1 - p->rt_priority; 854 else 855 prio = __normal_prio(p); 856 return prio; 857} 858 859/* 860 * Calculate the current priority, i.e. the priority 861 * taken into account by the scheduler. This value might 862 * be boosted by RT tasks, or might be boosted by 863 * interactivity modifiers. Will be RT if the task got 864 * RT-boosted. If not then it returns p->normal_prio. 865 */ 866static int effective_prio(struct task_struct *p) 867{ 868 p->normal_prio = normal_prio(p); 869 /* 870 * If we are RT tasks or we were boosted to RT priority, 871 * keep the priority unchanged. Otherwise, update priority 872 * to the normal priority: 873 */ 874 if (!rt_prio(p->prio)) 875 return p->normal_prio; 876 return p->prio; 877} 878 879/** 880 * task_curr - is this task currently executing on a CPU? 881 * @p: the task in question. 882 */ 883inline int task_curr(const struct task_struct *p) 884{ 885 return cpu_curr(task_cpu(p)) == p; 886} 887 888static inline void check_class_changed(struct rq *rq, struct task_struct *p, 889 const struct sched_class *prev_class, 890 int oldprio) 891{ 892 if (prev_class != p->sched_class) { 893 if (prev_class->switched_from) 894 prev_class->switched_from(rq, p); 895 p->sched_class->switched_to(rq, p); 896 } else if (oldprio != p->prio) 897 p->sched_class->prio_changed(rq, p, oldprio); 898} 899 900void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags) 901{ 902 const struct sched_class *class; 903 904 if (p->sched_class == rq->curr->sched_class) { 905 rq->curr->sched_class->check_preempt_curr(rq, p, flags); 906 } else { 907 for_each_class(class) { 908 if (class == rq->curr->sched_class) 909 break; 910 if (class == p->sched_class) { 911 resched_task(rq->curr); 912 break; 913 } 914 } 915 } 916 917 /* 918 * A queue event has occurred, and we're going to schedule. In 919 * this case, we can save a useless back to back clock update. 920 */ 921 if (rq->curr->on_rq && test_tsk_need_resched(rq->curr)) 922 rq->skip_clock_update = 1; 923} 924 925#ifdef CONFIG_SMP 926void set_task_cpu(struct task_struct *p, unsigned int new_cpu) 927{ 928#ifdef CONFIG_SCHED_DEBUG 929 /* 930 * We should never call set_task_cpu() on a blocked task, 931 * ttwu() will sort out the placement. 932 */ 933 WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING && 934 !(task_thread_info(p)->preempt_count & PREEMPT_ACTIVE)); 935 936#ifdef CONFIG_LOCKDEP 937 /* 938 * The caller should hold either p->pi_lock or rq->lock, when changing 939 * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks. 940 * 941 * sched_move_task() holds both and thus holding either pins the cgroup, 942 * see task_group(). 943 * 944 * Furthermore, all task_rq users should acquire both locks, see 945 * task_rq_lock(). 946 */ 947 WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) || 948 lockdep_is_held(&task_rq(p)->lock))); 949#endif 950#endif 951 952 trace_sched_migrate_task(p, new_cpu); 953 954 if (task_cpu(p) != new_cpu) { 955 p->se.nr_migrations++; 956 perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, NULL, 0); 957 } 958 959 __set_task_cpu(p, new_cpu); 960} 961 962struct migration_arg { 963 struct task_struct *task; 964 int dest_cpu; 965}; 966 967static int migration_cpu_stop(void *data); 968 969/* 970 * wait_task_inactive - wait for a thread to unschedule. 971 * 972 * If @match_state is nonzero, it's the @p->state value just checked and 973 * not expected to change. If it changes, i.e. @p might have woken up, 974 * then return zero. When we succeed in waiting for @p to be off its CPU, 975 * we return a positive number (its total switch count). If a second call 976 * a short while later returns the same number, the caller can be sure that 977 * @p has remained unscheduled the whole time. 978 * 979 * The caller must ensure that the task *will* unschedule sometime soon, 980 * else this function might spin for a *long* time. This function can't 981 * be called with interrupts off, or it may introduce deadlock with 982 * smp_call_function() if an IPI is sent by the same process we are 983 * waiting to become inactive. 984 */ 985unsigned long wait_task_inactive(struct task_struct *p, long match_state) 986{ 987 unsigned long flags; 988 int running, on_rq; 989 unsigned long ncsw; 990 struct rq *rq; 991 992 for (;;) { 993 /* 994 * We do the initial early heuristics without holding 995 * any task-queue locks at all. We'll only try to get 996 * the runqueue lock when things look like they will 997 * work out! 998 */ 999 rq = task_rq(p); 1000 1001 /* 1002 * If the task is actively running on another CPU 1003 * still, just relax and busy-wait without holding 1004 * any locks. 1005 * 1006 * NOTE! Since we don't hold any locks, it's not 1007 * even sure that "rq" stays as the right runqueue! 1008 * But we don't care, since "task_running()" will 1009 * return false if the runqueue has changed and p 1010 * is actually now running somewhere else! 1011 */ 1012 while (task_running(rq, p)) { 1013 if (match_state && unlikely(p->state != match_state)) 1014 return 0; 1015 cpu_relax(); 1016 } 1017 1018 /* 1019 * Ok, time to look more closely! We need the rq 1020 * lock now, to be *sure*. If we're wrong, we'll 1021 * just go back and repeat. 1022 */ 1023 rq = task_rq_lock(p, &flags); 1024 trace_sched_wait_task(p); 1025 running = task_running(rq, p); 1026 on_rq = p->on_rq; 1027 ncsw = 0; 1028 if (!match_state || p->state == match_state) 1029 ncsw = p->nvcsw | LONG_MIN; /* sets MSB */ 1030 task_rq_unlock(rq, p, &flags); 1031 1032 /* 1033 * If it changed from the expected state, bail out now. 1034 */ 1035 if (unlikely(!ncsw)) 1036 break; 1037 1038 /* 1039 * Was it really running after all now that we 1040 * checked with the proper locks actually held? 1041 * 1042 * Oops. Go back and try again.. 1043 */ 1044 if (unlikely(running)) { 1045 cpu_relax(); 1046 continue; 1047 } 1048 1049 /* 1050 * It's not enough that it's not actively running, 1051 * it must be off the runqueue _entirely_, and not 1052 * preempted! 1053 * 1054 * So if it was still runnable (but just not actively 1055 * running right now), it's preempted, and we should 1056 * yield - it could be a while. 1057 */ 1058 if (unlikely(on_rq)) { 1059 ktime_t to = ktime_set(0, NSEC_PER_SEC/HZ); 1060 1061 set_current_state(TASK_UNINTERRUPTIBLE); 1062 schedule_hrtimeout(&to, HRTIMER_MODE_REL); 1063 continue; 1064 } 1065 1066 /* 1067 * Ahh, all good. It wasn't running, and it wasn't 1068 * runnable, which means that it will never become 1069 * running in the future either. We're all done! 1070 */ 1071 break; 1072 } 1073 1074 return ncsw; 1075} 1076 1077/*** 1078 * kick_process - kick a running thread to enter/exit the kernel 1079 * @p: the to-be-kicked thread 1080 * 1081 * Cause a process which is running on another CPU to enter 1082 * kernel-mode, without any delay. (to get signals handled.) 1083 * 1084 * NOTE: this function doesn't have to take the runqueue lock, 1085 * because all it wants to ensure is that the remote task enters 1086 * the kernel. If the IPI races and the task has been migrated 1087 * to another CPU then no harm is done and the purpose has been 1088 * achieved as well. 1089 */ 1090void kick_process(struct task_struct *p) 1091{ 1092 int cpu; 1093 1094 preempt_disable(); 1095 cpu = task_cpu(p); 1096 if ((cpu != smp_processor_id()) && task_curr(p)) 1097 smp_send_reschedule(cpu); 1098 preempt_enable(); 1099} 1100EXPORT_SYMBOL_GPL(kick_process); 1101#endif /* CONFIG_SMP */ 1102 1103#ifdef CONFIG_SMP 1104/* 1105 * ->cpus_allowed is protected by both rq->lock and p->pi_lock 1106 */ 1107static int select_fallback_rq(int cpu, struct task_struct *p) 1108{ 1109 const struct cpumask *nodemask = cpumask_of_node(cpu_to_node(cpu)); 1110 enum { cpuset, possible, fail } state = cpuset; 1111 int dest_cpu; 1112 1113 /* Look for allowed, online CPU in same node. */ 1114 for_each_cpu(dest_cpu, nodemask) { 1115 if (!cpu_online(dest_cpu)) 1116 continue; 1117 if (!cpu_active(dest_cpu)) 1118 continue; 1119 if (cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p))) 1120 return dest_cpu; 1121 } 1122 1123 for (;;) { 1124 /* Any allowed, online CPU? */ 1125 for_each_cpu(dest_cpu, tsk_cpus_allowed(p)) { 1126 if (!cpu_online(dest_cpu)) 1127 continue; 1128 if (!cpu_active(dest_cpu)) 1129 continue; 1130 goto out; 1131 } 1132 1133 switch (state) { 1134 case cpuset: 1135 /* No more Mr. Nice Guy. */ 1136 cpuset_cpus_allowed_fallback(p); 1137 state = possible; 1138 break; 1139 1140 case possible: 1141 do_set_cpus_allowed(p, cpu_possible_mask); 1142 state = fail; 1143 break; 1144 1145 case fail: 1146 BUG(); 1147 break; 1148 } 1149 } 1150 1151out: 1152 if (state != cpuset) { 1153 /* 1154 * Don't tell them about moving exiting tasks or 1155 * kernel threads (both mm NULL), since they never 1156 * leave kernel. 1157 */ 1158 if (p->mm && printk_ratelimit()) { 1159 printk_sched("process %d (%s) no longer affine to cpu%d\n", 1160 task_pid_nr(p), p->comm, cpu); 1161 } 1162 } 1163 1164 return dest_cpu; 1165} 1166 1167/* 1168 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable. 1169 */ 1170static inline 1171int select_task_rq(struct task_struct *p, int sd_flags, int wake_flags) 1172{ 1173 int cpu = p->sched_class->select_task_rq(p, sd_flags, wake_flags); 1174 1175 /* 1176 * In order not to call set_task_cpu() on a blocking task we need 1177 * to rely on ttwu() to place the task on a valid ->cpus_allowed 1178 * cpu. 1179 * 1180 * Since this is common to all placement strategies, this lives here. 1181 * 1182 * [ this allows ->select_task() to simply return task_cpu(p) and 1183 * not worry about this generic constraint ] 1184 */ 1185 if (unlikely(!cpumask_test_cpu(cpu, tsk_cpus_allowed(p)) || 1186 !cpu_online(cpu))) 1187 cpu = select_fallback_rq(task_cpu(p), p); 1188 1189 return cpu; 1190} 1191 1192static void update_avg(u64 *avg, u64 sample) 1193{ 1194 s64 diff = sample - *avg; 1195 *avg += diff >> 3; 1196} 1197#endif 1198 1199static void 1200ttwu_stat(struct task_struct *p, int cpu, int wake_flags) 1201{ 1202#ifdef CONFIG_SCHEDSTATS 1203 struct rq *rq = this_rq(); 1204 1205#ifdef CONFIG_SMP 1206 int this_cpu = smp_processor_id(); 1207 1208 if (cpu == this_cpu) { 1209 schedstat_inc(rq, ttwu_local); 1210 schedstat_inc(p, se.statistics.nr_wakeups_local); 1211 } else { 1212 struct sched_domain *sd; 1213 1214 schedstat_inc(p, se.statistics.nr_wakeups_remote); 1215 rcu_read_lock(); 1216 for_each_domain(this_cpu, sd) { 1217 if (cpumask_test_cpu(cpu, sched_domain_span(sd))) { 1218 schedstat_inc(sd, ttwu_wake_remote); 1219 break; 1220 } 1221 } 1222 rcu_read_unlock(); 1223 } 1224 1225 if (wake_flags & WF_MIGRATED) 1226 schedstat_inc(p, se.statistics.nr_wakeups_migrate); 1227 1228#endif /* CONFIG_SMP */ 1229 1230 schedstat_inc(rq, ttwu_count); 1231 schedstat_inc(p, se.statistics.nr_wakeups); 1232 1233 if (wake_flags & WF_SYNC) 1234 schedstat_inc(p, se.statistics.nr_wakeups_sync); 1235 1236#endif /* CONFIG_SCHEDSTATS */ 1237} 1238 1239static void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags) 1240{ 1241 activate_task(rq, p, en_flags); 1242 p->on_rq = 1; 1243 1244 /* if a worker is waking up, notify workqueue */ 1245 if (p->flags & PF_WQ_WORKER) 1246 wq_worker_waking_up(p, cpu_of(rq)); 1247} 1248 1249/* 1250 * Mark the task runnable and perform wakeup-preemption. 1251 */ 1252static void 1253ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags) 1254{ 1255 trace_sched_wakeup(p, true); 1256 check_preempt_curr(rq, p, wake_flags); 1257 1258 p->state = TASK_RUNNING; 1259#ifdef CONFIG_SMP 1260 if (p->sched_class->task_woken) 1261 p->sched_class->task_woken(rq, p); 1262 1263 if (rq->idle_stamp) { 1264 u64 delta = rq->clock - rq->idle_stamp; 1265 u64 max = 2*sysctl_sched_migration_cost; 1266 1267 if (delta > max) 1268 rq->avg_idle = max; 1269 else 1270 update_avg(&rq->avg_idle, delta); 1271 rq->idle_stamp = 0; 1272 } 1273#endif 1274} 1275 1276static void 1277ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags) 1278{ 1279#ifdef CONFIG_SMP 1280 if (p->sched_contributes_to_load) 1281 rq->nr_uninterruptible--; 1282#endif 1283 1284 ttwu_activate(rq, p, ENQUEUE_WAKEUP | ENQUEUE_WAKING); 1285 ttwu_do_wakeup(rq, p, wake_flags); 1286} 1287 1288/* 1289 * Called in case the task @p isn't fully descheduled from its runqueue, 1290 * in this case we must do a remote wakeup. Its a 'light' wakeup though, 1291 * since all we need to do is flip p->state to TASK_RUNNING, since 1292 * the task is still ->on_rq. 1293 */ 1294static int ttwu_remote(struct task_struct *p, int wake_flags) 1295{ 1296 struct rq *rq; 1297 int ret = 0; 1298 1299 rq = __task_rq_lock(p); 1300 if (p->on_rq) { 1301 ttwu_do_wakeup(rq, p, wake_flags); 1302 ret = 1; 1303 } 1304 __task_rq_unlock(rq); 1305 1306 return ret; 1307} 1308 1309#ifdef CONFIG_SMP 1310static void sched_ttwu_pending(void) 1311{ 1312 struct rq *rq = this_rq(); 1313 struct llist_node *llist = llist_del_all(&rq->wake_list); 1314 struct task_struct *p; 1315 1316 raw_spin_lock(&rq->lock); 1317 1318 while (llist) { 1319 p = llist_entry(llist, struct task_struct, wake_entry); 1320 llist = llist_next(llist); 1321 ttwu_do_activate(rq, p, 0); 1322 } 1323 1324 raw_spin_unlock(&rq->lock); 1325} 1326 1327void scheduler_ipi(void) 1328{ 1329 if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick()) 1330 return; 1331 1332 /* 1333 * Not all reschedule IPI handlers call irq_enter/irq_exit, since 1334 * traditionally all their work was done from the interrupt return 1335 * path. Now that we actually do some work, we need to make sure 1336 * we do call them. 1337 * 1338 * Some archs already do call them, luckily irq_enter/exit nest 1339 * properly. 1340 * 1341 * Arguably we should visit all archs and update all handlers, 1342 * however a fair share of IPIs are still resched only so this would 1343 * somewhat pessimize the simple resched case. 1344 */ 1345 irq_enter(); 1346 sched_ttwu_pending(); 1347 1348 /* 1349 * Check if someone kicked us for doing the nohz idle load balance. 1350 */ 1351 if (unlikely(got_nohz_idle_kick() && !need_resched())) { 1352 this_rq()->idle_balance = 1; 1353 raise_softirq_irqoff(SCHED_SOFTIRQ); 1354 } 1355 irq_exit(); 1356} 1357 1358static void ttwu_queue_remote(struct task_struct *p, int cpu) 1359{ 1360 if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list)) 1361 smp_send_reschedule(cpu); 1362} 1363 1364bool cpus_share_cache(int this_cpu, int that_cpu) 1365{ 1366 return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu); 1367} 1368#endif /* CONFIG_SMP */ 1369 1370static void ttwu_queue(struct task_struct *p, int cpu) 1371{ 1372 struct rq *rq = cpu_rq(cpu); 1373 1374#if defined(CONFIG_SMP) 1375 if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) { 1376 sched_clock_cpu(cpu); /* sync clocks x-cpu */ 1377 ttwu_queue_remote(p, cpu); 1378 return; 1379 } 1380#endif 1381 1382 raw_spin_lock(&rq->lock); 1383 ttwu_do_activate(rq, p, 0); 1384 raw_spin_unlock(&rq->lock); 1385} 1386 1387/** 1388 * try_to_wake_up - wake up a thread 1389 * @p: the thread to be awakened 1390 * @state: the mask of task states that can be woken 1391 * @wake_flags: wake modifier flags (WF_*) 1392 * 1393 * Put it on the run-queue if it's not already there. The "current" 1394 * thread is always on the run-queue (except when the actual 1395 * re-schedule is in progress), and as such you're allowed to do 1396 * the simpler "current->state = TASK_RUNNING" to mark yourself 1397 * runnable without the overhead of this. 1398 * 1399 * Returns %true if @p was woken up, %false if it was already running 1400 * or @state didn't match @p's state. 1401 */ 1402static int 1403try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) 1404{ 1405 unsigned long flags; 1406 int cpu, success = 0; 1407 1408 smp_wmb(); 1409 raw_spin_lock_irqsave(&p->pi_lock, flags); 1410 if (!(p->state & state)) 1411 goto out; 1412 1413 success = 1; /* we're going to change ->state */ 1414 cpu = task_cpu(p); 1415 1416 if (p->on_rq && ttwu_remote(p, wake_flags)) 1417 goto stat; 1418 1419#ifdef CONFIG_SMP 1420 /* 1421 * If the owning (remote) cpu is still in the middle of schedule() with 1422 * this task as prev, wait until its done referencing the task. 1423 */ 1424 while (p->on_cpu) 1425 cpu_relax(); 1426 /* 1427 * Pairs with the smp_wmb() in finish_lock_switch(). 1428 */ 1429 smp_rmb(); 1430 1431 p->sched_contributes_to_load = !!task_contributes_to_load(p); 1432 p->state = TASK_WAKING; 1433 1434 if (p->sched_class->task_waking) 1435 p->sched_class->task_waking(p); 1436 1437 cpu = select_task_rq(p, SD_BALANCE_WAKE, wake_flags); 1438 if (task_cpu(p) != cpu) { 1439 wake_flags |= WF_MIGRATED; 1440 set_task_cpu(p, cpu); 1441 } 1442#endif /* CONFIG_SMP */ 1443 1444 ttwu_queue(p, cpu); 1445stat: 1446 ttwu_stat(p, cpu, wake_flags); 1447out: 1448 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 1449 1450 return success; 1451} 1452 1453/** 1454 * try_to_wake_up_local - try to wake up a local task with rq lock held 1455 * @p: the thread to be awakened 1456 * 1457 * Put @p on the run-queue if it's not already there. The caller must 1458 * ensure that this_rq() is locked, @p is bound to this_rq() and not 1459 * the current task. 1460 */ 1461static void try_to_wake_up_local(struct task_struct *p) 1462{ 1463 struct rq *rq = task_rq(p); 1464 1465 BUG_ON(rq != this_rq()); 1466 BUG_ON(p == current); 1467 lockdep_assert_held(&rq->lock); 1468 1469 if (!raw_spin_trylock(&p->pi_lock)) { 1470 raw_spin_unlock(&rq->lock); 1471 raw_spin_lock(&p->pi_lock); 1472 raw_spin_lock(&rq->lock); 1473 } 1474 1475 if (!(p->state & TASK_NORMAL)) 1476 goto out; 1477 1478 if (!p->on_rq) 1479 ttwu_activate(rq, p, ENQUEUE_WAKEUP); 1480 1481 ttwu_do_wakeup(rq, p, 0); 1482 ttwu_stat(p, smp_processor_id(), 0); 1483out: 1484 raw_spin_unlock(&p->pi_lock); 1485} 1486 1487/** 1488 * wake_up_process - Wake up a specific process 1489 * @p: The process to be woken up. 1490 * 1491 * Attempt to wake up the nominated process and move it to the set of runnable 1492 * processes. Returns 1 if the process was woken up, 0 if it was already 1493 * running. 1494 * 1495 * It may be assumed that this function implies a write memory barrier before 1496 * changing the task state if and only if any tasks are woken up. 1497 */ 1498int wake_up_process(struct task_struct *p) 1499{ 1500 return try_to_wake_up(p, TASK_ALL, 0); 1501} 1502EXPORT_SYMBOL(wake_up_process); 1503 1504int wake_up_state(struct task_struct *p, unsigned int state) 1505{ 1506 return try_to_wake_up(p, state, 0); 1507} 1508 1509/* 1510 * Perform scheduler related setup for a newly forked process p. 1511 * p is forked by current. 1512 * 1513 * __sched_fork() is basic setup used by init_idle() too: 1514 */ 1515static void __sched_fork(struct task_struct *p) 1516{ 1517 p->on_rq = 0; 1518 1519 p->se.on_rq = 0; 1520 p->se.exec_start = 0; 1521 p->se.sum_exec_runtime = 0; 1522 p->se.prev_sum_exec_runtime = 0; 1523 p->se.nr_migrations = 0; 1524 p->se.vruntime = 0; 1525 INIT_LIST_HEAD(&p->se.group_node); 1526 1527#ifdef CONFIG_SCHEDSTATS 1528 memset(&p->se.statistics, 0, sizeof(p->se.statistics)); 1529#endif 1530 1531 INIT_LIST_HEAD(&p->rt.run_list); 1532 1533#ifdef CONFIG_PREEMPT_NOTIFIERS 1534 INIT_HLIST_HEAD(&p->preempt_notifiers); 1535#endif 1536} 1537 1538/* 1539 * fork()/clone()-time setup: 1540 */ 1541void sched_fork(struct task_struct *p) 1542{ 1543 unsigned long flags; 1544 int cpu = get_cpu(); 1545 1546 __sched_fork(p); 1547 /* 1548 * We mark the process as running here. This guarantees that 1549 * nobody will actually run it, and a signal or other external 1550 * event cannot wake it up and insert it on the runqueue either. 1551 */ 1552 p->state = TASK_RUNNING; 1553 1554 /* 1555 * Make sure we do not leak PI boosting priority to the child. 1556 */ 1557 p->prio = current->normal_prio; 1558 1559 /* 1560 * Revert to default priority/policy on fork if requested. 1561 */ 1562 if (unlikely(p->sched_reset_on_fork)) { 1563 if (task_has_rt_policy(p)) { 1564 p->policy = SCHED_NORMAL; 1565 p->static_prio = NICE_TO_PRIO(0); 1566 p->rt_priority = 0; 1567 } else if (PRIO_TO_NICE(p->static_prio) < 0) 1568 p->static_prio = NICE_TO_PRIO(0); 1569 1570 p->prio = p->normal_prio = __normal_prio(p); 1571 set_load_weight(p); 1572 1573 /* 1574 * We don't need the reset flag anymore after the fork. It has 1575 * fulfilled its duty: 1576 */ 1577 p->sched_reset_on_fork = 0; 1578 } 1579 1580 if (!rt_prio(p->prio)) 1581 p->sched_class = &fair_sched_class; 1582 1583 if (p->sched_class->task_fork) 1584 p->sched_class->task_fork(p); 1585 1586 /* 1587 * The child is not yet in the pid-hash so no cgroup attach races, 1588 * and the cgroup is pinned to this child due to cgroup_fork() 1589 * is ran before sched_fork(). 1590 * 1591 * Silence PROVE_RCU. 1592 */ 1593 raw_spin_lock_irqsave(&p->pi_lock, flags); 1594 set_task_cpu(p, cpu); 1595 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 1596 1597#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) 1598 if (likely(sched_info_on())) 1599 memset(&p->sched_info, 0, sizeof(p->sched_info)); 1600#endif 1601#if defined(CONFIG_SMP) 1602 p->on_cpu = 0; 1603#endif 1604#ifdef CONFIG_PREEMPT_COUNT 1605 /* Want to start with kernel preemption disabled. */ 1606 task_thread_info(p)->preempt_count = 1; 1607#endif 1608#ifdef CONFIG_SMP 1609 plist_node_init(&p->pushable_tasks, MAX_PRIO); 1610#endif 1611 1612 put_cpu(); 1613} 1614 1615/* 1616 * wake_up_new_task - wake up a newly created task for the first time. 1617 * 1618 * This function will do some initial scheduler statistics housekeeping 1619 * that must be done for every newly created context, then puts the task 1620 * on the runqueue and wakes it. 1621 */ 1622void wake_up_new_task(struct task_struct *p) 1623{ 1624 unsigned long flags; 1625 struct rq *rq; 1626 1627 raw_spin_lock_irqsave(&p->pi_lock, flags); 1628#ifdef CONFIG_SMP 1629 /* 1630 * Fork balancing, do it here and not earlier because: 1631 * - cpus_allowed can change in the fork path 1632 * - any previously selected cpu might disappear through hotplug 1633 */ 1634 set_task_cpu(p, select_task_rq(p, SD_BALANCE_FORK, 0)); 1635#endif 1636 1637 rq = __task_rq_lock(p); 1638 activate_task(rq, p, 0); 1639 p->on_rq = 1; 1640 trace_sched_wakeup_new(p, true); 1641 check_preempt_curr(rq, p, WF_FORK); 1642#ifdef CONFIG_SMP 1643 if (p->sched_class->task_woken) 1644 p->sched_class->task_woken(rq, p); 1645#endif 1646 task_rq_unlock(rq, p, &flags); 1647} 1648 1649#ifdef CONFIG_PREEMPT_NOTIFIERS 1650 1651/** 1652 * preempt_notifier_register - tell me when current is being preempted & rescheduled 1653 * @notifier: notifier struct to register 1654 */ 1655void preempt_notifier_register(struct preempt_notifier *notifier) 1656{ 1657 hlist_add_head(¬ifier->link, ¤t->preempt_notifiers); 1658} 1659EXPORT_SYMBOL_GPL(preempt_notifier_register); 1660 1661/** 1662 * preempt_notifier_unregister - no longer interested in preemption notifications 1663 * @notifier: notifier struct to unregister 1664 * 1665 * This is safe to call from within a preemption notifier. 1666 */ 1667void preempt_notifier_unregister(struct preempt_notifier *notifier) 1668{ 1669 hlist_del(¬ifier->link); 1670} 1671EXPORT_SYMBOL_GPL(preempt_notifier_unregister); 1672 1673static void fire_sched_in_preempt_notifiers(struct task_struct *curr) 1674{ 1675 struct preempt_notifier *notifier; 1676 struct hlist_node *node; 1677 1678 hlist_for_each_entry(notifier, node, &curr->preempt_notifiers, link) 1679 notifier->ops->sched_in(notifier, raw_smp_processor_id()); 1680} 1681 1682static void 1683fire_sched_out_preempt_notifiers(struct task_struct *curr, 1684 struct task_struct *next) 1685{ 1686 struct preempt_notifier *notifier; 1687 struct hlist_node *node; 1688 1689 hlist_for_each_entry(notifier, node, &curr->preempt_notifiers, link) 1690 notifier->ops->sched_out(notifier, next); 1691} 1692 1693#else /* !CONFIG_PREEMPT_NOTIFIERS */ 1694 1695static void fire_sched_in_preempt_notifiers(struct task_struct *curr) 1696{ 1697} 1698 1699static void 1700fire_sched_out_preempt_notifiers(struct task_struct *curr, 1701 struct task_struct *next) 1702{ 1703} 1704 1705#endif /* CONFIG_PREEMPT_NOTIFIERS */ 1706 1707/** 1708 * prepare_task_switch - prepare to switch tasks 1709 * @rq: the runqueue preparing to switch 1710 * @prev: the current task that is being switched out 1711 * @next: the task we are going to switch to. 1712 * 1713 * This is called with the rq lock held and interrupts off. It must 1714 * be paired with a subsequent finish_task_switch after the context 1715 * switch. 1716 * 1717 * prepare_task_switch sets up locking and calls architecture specific 1718 * hooks. 1719 */ 1720static inline void 1721prepare_task_switch(struct rq *rq, struct task_struct *prev, 1722 struct task_struct *next) 1723{ 1724 trace_sched_switch(prev, next); 1725 sched_info_switch(prev, next); 1726 perf_event_task_sched_out(prev, next); 1727 fire_sched_out_preempt_notifiers(prev, next); 1728 prepare_lock_switch(rq, next); 1729 prepare_arch_switch(next); 1730} 1731 1732/** 1733 * finish_task_switch - clean up after a task-switch 1734 * @rq: runqueue associated with task-switch 1735 * @prev: the thread we just switched away from. 1736 * 1737 * finish_task_switch must be called after the context switch, paired 1738 * with a prepare_task_switch call before the context switch. 1739 * finish_task_switch will reconcile locking set up by prepare_task_switch, 1740 * and do any other architecture-specific cleanup actions. 1741 * 1742 * Note that we may have delayed dropping an mm in context_switch(). If 1743 * so, we finish that here outside of the runqueue lock. (Doing it 1744 * with the lock held can cause deadlocks; see schedule() for 1745 * details.) 1746 */ 1747static void finish_task_switch(struct rq *rq, struct task_struct *prev) 1748 __releases(rq->lock) 1749{ 1750 struct mm_struct *mm = rq->prev_mm; 1751 long prev_state; 1752 1753 rq->prev_mm = NULL; 1754 1755 /* 1756 * A task struct has one reference for the use as "current". 1757 * If a task dies, then it sets TASK_DEAD in tsk->state and calls 1758 * schedule one last time. The schedule call will never return, and 1759 * the scheduled task must drop that reference. 1760 * The test for TASK_DEAD must occur while the runqueue locks are 1761 * still held, otherwise prev could be scheduled on another cpu, die 1762 * there before we look at prev->state, and then the reference would 1763 * be dropped twice. 1764 * Manfred Spraul <manfred@colorfullife.com> 1765 */ 1766 prev_state = prev->state; 1767 account_switch_vtime(prev); 1768 finish_arch_switch(prev); 1769 perf_event_task_sched_in(prev, current); 1770 finish_lock_switch(rq, prev); 1771 finish_arch_post_lock_switch(); 1772 1773 fire_sched_in_preempt_notifiers(current); 1774 if (mm) 1775 mmdrop(mm); 1776 if (unlikely(prev_state == TASK_DEAD)) { 1777 /* 1778 * Remove function-return probe instances associated with this 1779 * task and put them back on the free list. 1780 */ 1781 kprobe_flush_task(prev); 1782 put_task_struct(prev); 1783 } 1784} 1785 1786#ifdef CONFIG_SMP 1787 1788/* assumes rq->lock is held */ 1789static inline void pre_schedule(struct rq *rq, struct task_struct *prev) 1790{ 1791 if (prev->sched_class->pre_schedule) 1792 prev->sched_class->pre_schedule(rq, prev); 1793} 1794 1795/* rq->lock is NOT held, but preemption is disabled */ 1796static inline void post_schedule(struct rq *rq) 1797{ 1798 if (rq->post_schedule) { 1799 unsigned long flags; 1800 1801 raw_spin_lock_irqsave(&rq->lock, flags); 1802 if (rq->curr->sched_class->post_schedule) 1803 rq->curr->sched_class->post_schedule(rq); 1804 raw_spin_unlock_irqrestore(&rq->lock, flags); 1805 1806 rq->post_schedule = 0; 1807 } 1808} 1809 1810#else 1811 1812static inline void pre_schedule(struct rq *rq, struct task_struct *p) 1813{ 1814} 1815 1816static inline void post_schedule(struct rq *rq) 1817{ 1818} 1819 1820#endif 1821 1822/** 1823 * schedule_tail - first thing a freshly forked thread must call. 1824 * @prev: the thread we just switched away from. 1825 */ 1826asmlinkage void schedule_tail(struct task_struct *prev) 1827 __releases(rq->lock) 1828{ 1829 struct rq *rq = this_rq(); 1830 1831 finish_task_switch(rq, prev); 1832 1833 /* 1834 * FIXME: do we need to worry about rq being invalidated by the 1835 * task_switch? 1836 */ 1837 post_schedule(rq); 1838 1839#ifdef __ARCH_WANT_UNLOCKED_CTXSW 1840 /* In this case, finish_task_switch does not reenable preemption */ 1841 preempt_enable(); 1842#endif 1843 if (current->set_child_tid) 1844 put_user(task_pid_vnr(current), current->set_child_tid); 1845} 1846 1847/* 1848 * context_switch - switch to the new MM and the new 1849 * thread's register state. 1850 */ 1851static inline void 1852context_switch(struct rq *rq, struct task_struct *prev, 1853 struct task_struct *next) 1854{ 1855 struct mm_struct *mm, *oldmm; 1856 1857 prepare_task_switch(rq, prev, next); 1858 1859 mm = next->mm; 1860 oldmm = prev->active_mm; 1861 /* 1862 * For paravirt, this is coupled with an exit in switch_to to 1863 * combine the page table reload and the switch backend into 1864 * one hypercall. 1865 */ 1866 arch_start_context_switch(prev); 1867 1868 if (!mm) { 1869 next->active_mm = oldmm; 1870 atomic_inc(&oldmm->mm_count); 1871 enter_lazy_tlb(oldmm, next); 1872 } else 1873 switch_mm(oldmm, mm, next); 1874 1875 if (!prev->mm) { 1876 prev->active_mm = NULL; 1877 rq->prev_mm = oldmm; 1878 } 1879 /* 1880 * Since the runqueue lock will be released by the next 1881 * task (which is an invalid locking op but in the case 1882 * of the scheduler it's an obvious special-case), so we 1883 * do an early lockdep release here: 1884 */ 1885#ifndef __ARCH_WANT_UNLOCKED_CTXSW 1886 spin_release(&rq->lock.dep_map, 1, _THIS_IP_); 1887#endif 1888 1889 /* Here we just switch the register state and the stack. */ 1890 switch_to(prev, next, prev); 1891 1892 barrier(); 1893 /* 1894 * this_rq must be evaluated again because prev may have moved 1895 * CPUs since it called schedule(), thus the 'rq' on its stack 1896 * frame will be invalid. 1897 */ 1898 finish_task_switch(this_rq(), prev); 1899} 1900 1901/* 1902 * nr_running, nr_uninterruptible and nr_context_switches: 1903 * 1904 * externally visible scheduler statistics: current number of runnable 1905 * threads, current number of uninterruptible-sleeping threads, total 1906 * number of context switches performed since bootup. 1907 */ 1908unsigned long nr_running(void) 1909{ 1910 unsigned long i, sum = 0; 1911 1912 for_each_online_cpu(i) 1913 sum += cpu_rq(i)->nr_running; 1914 1915 return sum; 1916} 1917 1918unsigned long nr_uninterruptible(void) 1919{ 1920 unsigned long i, sum = 0; 1921 1922 for_each_possible_cpu(i) 1923 sum += cpu_rq(i)->nr_uninterruptible; 1924 1925 /* 1926 * Since we read the counters lockless, it might be slightly 1927 * inaccurate. Do not allow it to go below zero though: 1928 */ 1929 if (unlikely((long)sum < 0)) 1930 sum = 0; 1931 1932 return sum; 1933} 1934 1935unsigned long long nr_context_switches(void) 1936{ 1937 int i; 1938 unsigned long long sum = 0; 1939 1940 for_each_possible_cpu(i) 1941 sum += cpu_rq(i)->nr_switches; 1942 1943 return sum; 1944} 1945 1946unsigned long nr_iowait(void) 1947{ 1948 unsigned long i, sum = 0; 1949 1950 for_each_possible_cpu(i) 1951 sum += atomic_read(&cpu_rq(i)->nr_iowait); 1952 1953 return sum; 1954} 1955 1956unsigned long nr_iowait_cpu(int cpu) 1957{ 1958 struct rq *this = cpu_rq(cpu); 1959 return atomic_read(&this->nr_iowait); 1960} 1961 1962unsigned long this_cpu_load(void) 1963{ 1964 struct rq *this = this_rq(); 1965 return this->cpu_load[0]; 1966} 1967 1968 1969/* 1970 * Global load-average calculations 1971 * 1972 * We take a distributed and async approach to calculating the global load-avg 1973 * in order to minimize overhead. 1974 * 1975 * The global load average is an exponentially decaying average of nr_running + 1976 * nr_uninterruptible. 1977 * 1978 * Once every LOAD_FREQ: 1979 * 1980 * nr_active = 0; 1981 * for_each_possible_cpu(cpu) 1982 * nr_active += cpu_of(cpu)->nr_running + cpu_of(cpu)->nr_uninterruptible; 1983 * 1984 * avenrun[n] = avenrun[0] * exp_n + nr_active * (1 - exp_n) 1985 * 1986 * Due to a number of reasons the above turns in the mess below: 1987 * 1988 * - for_each_possible_cpu() is prohibitively expensive on machines with 1989 * serious number of cpus, therefore we need to take a distributed approach 1990 * to calculating nr_active. 1991 * 1992 * \Sum_i x_i(t) = \Sum_i x_i(t) - x_i(t_0) | x_i(t_0) := 0 1993 * = \Sum_i { \Sum_j=1 x_i(t_j) - x_i(t_j-1) } 1994 * 1995 * So assuming nr_active := 0 when we start out -- true per definition, we 1996 * can simply take per-cpu deltas and fold those into a global accumulate 1997 * to obtain the same result. See calc_load_fold_active(). 1998 * 1999 * Furthermore, in order to avoid synchronizing all per-cpu delta folding 2000 * across the machine, we assume 10 ticks is sufficient time for every 2001 * cpu to have completed this task. 2002 * 2003 * This places an upper-bound on the IRQ-off latency of the machine. Then 2004 * again, being late doesn't loose the delta, just wrecks the sample. 2005 * 2006 * - cpu_rq()->nr_uninterruptible isn't accurately tracked per-cpu because 2007 * this would add another cross-cpu cacheline miss and atomic operation 2008 * to the wakeup path. Instead we increment on whatever cpu the task ran 2009 * when it went into uninterruptible state and decrement on whatever cpu 2010 * did the wakeup. This means that only the sum of nr_uninterruptible over 2011 * all cpus yields the correct result. 2012 * 2013 * This covers the NO_HZ=n code, for extra head-aches, see the comment below. 2014 */ 2015 2016/* Variables and functions for calc_load */ 2017static atomic_long_t calc_load_tasks; 2018static unsigned long calc_load_update; 2019unsigned long avenrun[3]; 2020EXPORT_SYMBOL(avenrun); /* should be removed */ 2021 2022/** 2023 * get_avenrun - get the load average array 2024 * @loads: pointer to dest load array 2025 * @offset: offset to add 2026 * @shift: shift count to shift the result left 2027 * 2028 * These values are estimates at best, so no need for locking. 2029 */ 2030void get_avenrun(unsigned long *loads, unsigned long offset, int shift) 2031{ 2032 loads[0] = (avenrun[0] + offset) << shift; 2033 loads[1] = (avenrun[1] + offset) << shift; 2034 loads[2] = (avenrun[2] + offset) << shift; 2035} 2036 2037static long calc_load_fold_active(struct rq *this_rq) 2038{ 2039 long nr_active, delta = 0; 2040 2041 nr_active = this_rq->nr_running; 2042 nr_active += (long) this_rq->nr_uninterruptible; 2043 2044 if (nr_active != this_rq->calc_load_active) { 2045 delta = nr_active - this_rq->calc_load_active; 2046 this_rq->calc_load_active = nr_active; 2047 } 2048 2049 return delta; 2050} 2051 2052/* 2053 * a1 = a0 * e + a * (1 - e) 2054 */ 2055static unsigned long 2056calc_load(unsigned long load, unsigned long exp, unsigned long active) 2057{ 2058 load *= exp; 2059 load += active * (FIXED_1 - exp); 2060 load += 1UL << (FSHIFT - 1); 2061 return load >> FSHIFT; 2062} 2063 2064#ifdef CONFIG_NO_HZ 2065/* 2066 * Handle NO_HZ for the global load-average. 2067 * 2068 * Since the above described distributed algorithm to compute the global 2069 * load-average relies on per-cpu sampling from the tick, it is affected by 2070 * NO_HZ. 2071 * 2072 * The basic idea is to fold the nr_active delta into a global idle-delta upon 2073 * entering NO_HZ state such that we can include this as an 'extra' cpu delta 2074 * when we read the global state. 2075 * 2076 * Obviously reality has to ruin such a delightfully simple scheme: 2077 * 2078 * - When we go NO_HZ idle during the window, we can negate our sample 2079 * contribution, causing under-accounting. 2080 * 2081 * We avoid this by keeping two idle-delta counters and flipping them 2082 * when the window starts, thus separating old and new NO_HZ load. 2083 * 2084 * The only trick is the slight shift in index flip for read vs write. 2085 * 2086 * 0s 5s 10s 15s 2087 * +10 +10 +10 +10 2088 * |-|-----------|-|-----------|-|-----------|-| 2089 * r:0 0 1 1 0 0 1 1 0 2090 * w:0 1 1 0 0 1 1 0 0 2091 * 2092 * This ensures we'll fold the old idle contribution in this window while 2093 * accumlating the new one. 2094 * 2095 * - When we wake up from NO_HZ idle during the window, we push up our 2096 * contribution, since we effectively move our sample point to a known 2097 * busy state. 2098 * 2099 * This is solved by pushing the window forward, and thus skipping the 2100 * sample, for this cpu (effectively using the idle-delta for this cpu which 2101 * was in effect at the time the window opened). This also solves the issue 2102 * of having to deal with a cpu having been in NOHZ idle for multiple 2103 * LOAD_FREQ intervals. 2104 * 2105 * When making the ILB scale, we should try to pull this in as well. 2106 */ 2107static atomic_long_t calc_load_idle[2]; 2108static int calc_load_idx; 2109 2110static inline int calc_load_write_idx(void) 2111{ 2112 int idx = calc_load_idx; 2113 2114 /* 2115 * See calc_global_nohz(), if we observe the new index, we also 2116 * need to observe the new update time. 2117 */ 2118 smp_rmb(); 2119 2120 /* 2121 * If the folding window started, make sure we start writing in the 2122 * next idle-delta. 2123 */ 2124 if (!time_before(jiffies, calc_load_update)) 2125 idx++; 2126 2127 return idx & 1; 2128} 2129 2130static inline int calc_load_read_idx(void) 2131{ 2132 return calc_load_idx & 1; 2133} 2134 2135void calc_load_enter_idle(void) 2136{ 2137 struct rq *this_rq = this_rq(); 2138 long delta; 2139 2140 /* 2141 * We're going into NOHZ mode, if there's any pending delta, fold it 2142 * into the pending idle delta. 2143 */ 2144 delta = calc_load_fold_active(this_rq); 2145 if (delta) { 2146 int idx = calc_load_write_idx(); 2147 atomic_long_add(delta, &calc_load_idle[idx]); 2148 } 2149} 2150 2151void calc_load_exit_idle(void) 2152{ 2153 struct rq *this_rq = this_rq(); 2154 2155 /* 2156 * If we're still before the sample window, we're done. 2157 */ 2158 if (time_before(jiffies, this_rq->calc_load_update)) 2159 return; 2160 2161 /* 2162 * We woke inside or after the sample window, this means we're already 2163 * accounted through the nohz accounting, so skip the entire deal and 2164 * sync up for the next window. 2165 */ 2166 this_rq->calc_load_update = calc_load_update; 2167 if (time_before(jiffies, this_rq->calc_load_update + 10)) 2168 this_rq->calc_load_update += LOAD_FREQ; 2169} 2170 2171static long calc_load_fold_idle(void) 2172{ 2173 int idx = calc_load_read_idx(); 2174 long delta = 0; 2175 2176 if (atomic_long_read(&calc_load_idle[idx])) 2177 delta = atomic_long_xchg(&calc_load_idle[idx], 0); 2178 2179 return delta; 2180} 2181 2182/** 2183 * fixed_power_int - compute: x^n, in O(log n) time 2184 * 2185 * @x: base of the power 2186 * @frac_bits: fractional bits of @x 2187 * @n: power to raise @x to. 2188 * 2189 * By exploiting the relation between the definition of the natural power 2190 * function: x^n := x*x*...*x (x multiplied by itself for n times), and 2191 * the binary encoding of numbers used by computers: n := \Sum n_i * 2^i, 2192 * (where: n_i \elem {0, 1}, the binary vector representing n), 2193 * we find: x^n := x^(\Sum n_i * 2^i) := \Prod x^(n_i * 2^i), which is 2194 * of course trivially computable in O(log_2 n), the length of our binary 2195 * vector. 2196 */ 2197static unsigned long 2198fixed_power_int(unsigned long x, unsigned int frac_bits, unsigned int n) 2199{ 2200 unsigned long result = 1UL << frac_bits; 2201 2202 if (n) for (;;) { 2203 if (n & 1) { 2204 result *= x; 2205 result += 1UL << (frac_bits - 1); 2206 result >>= frac_bits; 2207 } 2208 n >>= 1; 2209 if (!n) 2210 break; 2211 x *= x; 2212 x += 1UL << (frac_bits - 1); 2213 x >>= frac_bits; 2214 } 2215 2216 return result; 2217} 2218 2219/* 2220 * a1 = a0 * e + a * (1 - e) 2221 * 2222 * a2 = a1 * e + a * (1 - e) 2223 * = (a0 * e + a * (1 - e)) * e + a * (1 - e) 2224 * = a0 * e^2 + a * (1 - e) * (1 + e) 2225 * 2226 * a3 = a2 * e + a * (1 - e) 2227 * = (a0 * e^2 + a * (1 - e) * (1 + e)) * e + a * (1 - e) 2228 * = a0 * e^3 + a * (1 - e) * (1 + e + e^2) 2229 * 2230 * ... 2231 * 2232 * an = a0 * e^n + a * (1 - e) * (1 + e + ... + e^n-1) [1] 2233 * = a0 * e^n + a * (1 - e) * (1 - e^n)/(1 - e) 2234 * = a0 * e^n + a * (1 - e^n) 2235 * 2236 * [1] application of the geometric series: 2237 * 2238 * n 1 - x^(n+1) 2239 * S_n := \Sum x^i = ------------- 2240 * i=0 1 - x 2241 */ 2242static unsigned long 2243calc_load_n(unsigned long load, unsigned long exp, 2244 unsigned long active, unsigned int n) 2245{ 2246 2247 return calc_load(load, fixed_power_int(exp, FSHIFT, n), active); 2248} 2249 2250/* 2251 * NO_HZ can leave us missing all per-cpu ticks calling 2252 * calc_load_account_active(), but since an idle CPU folds its delta into 2253 * calc_load_tasks_idle per calc_load_account_idle(), all we need to do is fold 2254 * in the pending idle delta if our idle period crossed a load cycle boundary. 2255 * 2256 * Once we've updated the global active value, we need to apply the exponential 2257 * weights adjusted to the number of cycles missed. 2258 */ 2259static void calc_global_nohz(void) 2260{ 2261 long delta, active, n; 2262 2263 if (!time_before(jiffies, calc_load_update + 10)) { 2264 /* 2265 * Catch-up, fold however many we are behind still 2266 */ 2267 delta = jiffies - calc_load_update - 10; 2268 n = 1 + (delta / LOAD_FREQ); 2269 2270 active = atomic_long_read(&calc_load_tasks); 2271 active = active > 0 ? active * FIXED_1 : 0; 2272 2273 avenrun[0] = calc_load_n(avenrun[0], EXP_1, active, n); 2274 avenrun[1] = calc_load_n(avenrun[1], EXP_5, active, n); 2275 avenrun[2] = calc_load_n(avenrun[2], EXP_15, active, n); 2276 2277 calc_load_update += n * LOAD_FREQ; 2278 } 2279 2280 /* 2281 * Flip the idle index... 2282 * 2283 * Make sure we first write the new time then flip the index, so that 2284 * calc_load_write_idx() will see the new time when it reads the new 2285 * index, this avoids a double flip messing things up. 2286 */ 2287 smp_wmb(); 2288 calc_load_idx++; 2289} 2290#else /* !CONFIG_NO_HZ */ 2291 2292static inline long calc_load_fold_idle(void) { return 0; } 2293static inline void calc_global_nohz(void) { } 2294 2295#endif /* CONFIG_NO_HZ */ 2296 2297/* 2298 * calc_load - update the avenrun load estimates 10 ticks after the 2299 * CPUs have updated calc_load_tasks. 2300 */ 2301void calc_global_load(unsigned long ticks) 2302{ 2303 long active, delta; 2304 2305 if (time_before(jiffies, calc_load_update + 10)) 2306 return; 2307 2308 /* 2309 * Fold the 'old' idle-delta to include all NO_HZ cpus. 2310 */ 2311 delta = calc_load_fold_idle(); 2312 if (delta) 2313 atomic_long_add(delta, &calc_load_tasks); 2314 2315 active = atomic_long_read(&calc_load_tasks); 2316 active = active > 0 ? active * FIXED_1 : 0; 2317 2318 avenrun[0] = calc_load(avenrun[0], EXP_1, active); 2319 avenrun[1] = calc_load(avenrun[1], EXP_5, active); 2320 avenrun[2] = calc_load(avenrun[2], EXP_15, active); 2321 2322 calc_load_update += LOAD_FREQ; 2323 2324 /* 2325 * In case we idled for multiple LOAD_FREQ intervals, catch up in bulk. 2326 */ 2327 calc_global_nohz(); 2328} 2329 2330/* 2331 * Called from update_cpu_load() to periodically update this CPU's 2332 * active count. 2333 */ 2334static void calc_load_account_active(struct rq *this_rq) 2335{ 2336 long delta; 2337 2338 if (time_before(jiffies, this_rq->calc_load_update)) 2339 return; 2340 2341 delta = calc_load_fold_active(this_rq); 2342 if (delta) 2343 atomic_long_add(delta, &calc_load_tasks); 2344 2345 this_rq->calc_load_update += LOAD_FREQ; 2346} 2347 2348/* 2349 * End of global load-average stuff 2350 */ 2351 2352/* 2353 * The exact cpuload at various idx values, calculated at every tick would be 2354 * load = (2^idx - 1) / 2^idx * load + 1 / 2^idx * cur_load 2355 * 2356 * If a cpu misses updates for n-1 ticks (as it was idle) and update gets called 2357 * on nth tick when cpu may be busy, then we have: 2358 * load = ((2^idx - 1) / 2^idx)^(n-1) * load 2359 * load = (2^idx - 1) / 2^idx) * load + 1 / 2^idx * cur_load 2360 * 2361 * decay_load_missed() below does efficient calculation of 2362 * load = ((2^idx - 1) / 2^idx)^(n-1) * load 2363 * avoiding 0..n-1 loop doing load = ((2^idx - 1) / 2^idx) * load 2364 * 2365 * The calculation is approximated on a 128 point scale. 2366 * degrade_zero_ticks is the number of ticks after which load at any 2367 * particular idx is approximated to be zero. 2368 * degrade_factor is a precomputed table, a row for each load idx. 2369 * Each column corresponds to degradation factor for a power of two ticks, 2370 * based on 128 point scale. 2371 * Example: 2372 * row 2, col 3 (=12) says that the degradation at load idx 2 after 2373 * 8 ticks is 12/128 (which is an approximation of exact factor 3^8/4^8). 2374 * 2375 * With this power of 2 load factors, we can degrade the load n times 2376 * by looking at 1 bits in n and doing as many mult/shift instead of 2377 * n mult/shifts needed by the exact degradation. 2378 */ 2379#define DEGRADE_SHIFT 7 2380static const unsigned char 2381 degrade_zero_ticks[CPU_LOAD_IDX_MAX] = {0, 8, 32, 64, 128}; 2382static const unsigned char 2383 degrade_factor[CPU_LOAD_IDX_MAX][DEGRADE_SHIFT + 1] = { 2384 {0, 0, 0, 0, 0, 0, 0, 0}, 2385 {64, 32, 8, 0, 0, 0, 0, 0}, 2386 {96, 72, 40, 12, 1, 0, 0}, 2387 {112, 98, 75, 43, 15, 1, 0}, 2388 {120, 112, 98, 76, 45, 16, 2} }; 2389 2390/* 2391 * Update cpu_load for any missed ticks, due to tickless idle. The backlog 2392 * would be when CPU is idle and so we just decay the old load without 2393 * adding any new load. 2394 */ 2395static unsigned long 2396decay_load_missed(unsigned long load, unsigned long missed_updates, int idx) 2397{ 2398 int j = 0; 2399 2400 if (!missed_updates) 2401 return load; 2402 2403 if (missed_updates >= degrade_zero_ticks[idx]) 2404 return 0; 2405 2406 if (idx == 1) 2407 return load >> missed_updates; 2408 2409 while (missed_updates) { 2410 if (missed_updates % 2) 2411 load = (load * degrade_factor[idx][j]) >> DEGRADE_SHIFT; 2412 2413 missed_updates >>= 1; 2414 j++; 2415 } 2416 return load; 2417} 2418 2419/* 2420 * Update rq->cpu_load[] statistics. This function is usually called every 2421 * scheduler tick (TICK_NSEC). With tickless idle this will not be called 2422 * every tick. We fix it up based on jiffies. 2423 */ 2424static void __update_cpu_load(struct rq *this_rq, unsigned long this_load, 2425 unsigned long pending_updates) 2426{ 2427 int i, scale; 2428 2429 this_rq->nr_load_updates++; 2430 2431 /* Update our load: */ 2432 this_rq->cpu_load[0] = this_load; /* Fasttrack for idx 0 */ 2433 for (i = 1, scale = 2; i < CPU_LOAD_IDX_MAX; i++, scale += scale) { 2434 unsigned long old_load, new_load; 2435 2436 /* scale is effectively 1 << i now, and >> i divides by scale */ 2437 2438 old_load = this_rq->cpu_load[i]; 2439 old_load = decay_load_missed(old_load, pending_updates - 1, i); 2440 new_load = this_load; 2441 /* 2442 * Round up the averaging division if load is increasing. This 2443 * prevents us from getting stuck on 9 if the load is 10, for 2444 * example. 2445 */ 2446 if (new_load > old_load) 2447 new_load += scale - 1; 2448 2449 this_rq->cpu_load[i] = (old_load * (scale - 1) + new_load) >> i; 2450 } 2451 2452 sched_avg_update(this_rq); 2453} 2454 2455#ifdef CONFIG_NO_HZ 2456/* 2457 * There is no sane way to deal with nohz on smp when using jiffies because the 2458 * cpu doing the jiffies update might drift wrt the cpu doing the jiffy reading 2459 * causing off-by-one errors in observed deltas; {0,2} instead of {1,1}. 2460 * 2461 * Therefore we cannot use the delta approach from the regular tick since that 2462 * would seriously skew the load calculation. However we'll make do for those 2463 * updates happening while idle (nohz_idle_balance) or coming out of idle 2464 * (tick_nohz_idle_exit). 2465 * 2466 * This means we might still be one tick off for nohz periods. 2467 */ 2468 2469/* 2470 * Called from nohz_idle_balance() to update the load ratings before doing the 2471 * idle balance. 2472 */ 2473void update_idle_cpu_load(struct rq *this_rq) 2474{ 2475 unsigned long curr_jiffies = ACCESS_ONCE(jiffies); 2476 unsigned long load = this_rq->load.weight; 2477 unsigned long pending_updates; 2478 2479 /* 2480 * bail if there's load or we're actually up-to-date. 2481 */ 2482 if (load || curr_jiffies == this_rq->last_load_update_tick) 2483 return; 2484 2485 pending_updates = curr_jiffies - this_rq->last_load_update_tick; 2486 this_rq->last_load_update_tick = curr_jiffies; 2487 2488 __update_cpu_load(this_rq, load, pending_updates); 2489} 2490 2491/* 2492 * Called from tick_nohz_idle_exit() -- try and fix up the ticks we missed. 2493 */ 2494void update_cpu_load_nohz(void) 2495{ 2496 struct rq *this_rq = this_rq(); 2497 unsigned long curr_jiffies = ACCESS_ONCE(jiffies); 2498 unsigned long pending_updates; 2499 2500 if (curr_jiffies == this_rq->last_load_update_tick) 2501 return; 2502 2503 raw_spin_lock(&this_rq->lock); 2504 pending_updates = curr_jiffies - this_rq->last_load_update_tick; 2505 if (pending_updates) { 2506 this_rq->last_load_update_tick = curr_jiffies; 2507 /* 2508 * We were idle, this means load 0, the current load might be 2509 * !0 due to remote wakeups and the sort. 2510 */ 2511 __update_cpu_load(this_rq, 0, pending_updates); 2512 } 2513 raw_spin_unlock(&this_rq->lock); 2514} 2515#endif /* CONFIG_NO_HZ */ 2516 2517/* 2518 * Called from scheduler_tick() 2519 */ 2520static void update_cpu_load_active(struct rq *this_rq) 2521{ 2522 /* 2523 * See the mess around update_idle_cpu_load() / update_cpu_load_nohz(). 2524 */ 2525 this_rq->last_load_update_tick = jiffies; 2526 __update_cpu_load(this_rq, this_rq->load.weight, 1); 2527 2528 calc_load_account_active(this_rq); 2529} 2530 2531#ifdef CONFIG_SMP 2532 2533/* 2534 * sched_exec - execve() is a valuable balancing opportunity, because at 2535 * this point the task has the smallest effective memory and cache footprint. 2536 */ 2537void sched_exec(void) 2538{ 2539 struct task_struct *p = current; 2540 unsigned long flags; 2541 int dest_cpu; 2542 2543 raw_spin_lock_irqsave(&p->pi_lock, flags); 2544 dest_cpu = p->sched_class->select_task_rq(p, SD_BALANCE_EXEC, 0); 2545 if (dest_cpu == smp_processor_id()) 2546 goto unlock; 2547 2548 if (likely(cpu_active(dest_cpu))) { 2549 struct migration_arg arg = { p, dest_cpu }; 2550 2551 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 2552 stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg); 2553 return; 2554 } 2555unlock: 2556 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 2557} 2558 2559#endif 2560 2561DEFINE_PER_CPU(struct kernel_stat, kstat); 2562DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat); 2563 2564EXPORT_PER_CPU_SYMBOL(kstat); 2565EXPORT_PER_CPU_SYMBOL(kernel_cpustat); 2566 2567/* 2568 * Return any ns on the sched_clock that have not yet been accounted in 2569 * @p in case that task is currently running. 2570 * 2571 * Called with task_rq_lock() held on @rq. 2572 */ 2573static u64 do_task_delta_exec(struct task_struct *p, struct rq *rq) 2574{ 2575 u64 ns = 0; 2576 2577 if (task_current(rq, p)) { 2578 update_rq_clock(rq); 2579 ns = rq->clock_task - p->se.exec_start; 2580 if ((s64)ns < 0) 2581 ns = 0; 2582 } 2583 2584 return ns; 2585} 2586 2587unsigned long long task_delta_exec(struct task_struct *p) 2588{ 2589 unsigned long flags; 2590 struct rq *rq; 2591 u64 ns = 0; 2592 2593 rq = task_rq_lock(p, &flags); 2594 ns = do_task_delta_exec(p, rq); 2595 task_rq_unlock(rq, p, &flags); 2596 2597 return ns; 2598} 2599 2600/* 2601 * Return accounted runtime for the task. 2602 * In case the task is currently running, return the runtime plus current's 2603 * pending runtime that have not been accounted yet. 2604 */ 2605unsigned long long task_sched_runtime(struct task_struct *p) 2606{ 2607 unsigned long flags; 2608 struct rq *rq; 2609 u64 ns = 0; 2610 2611 rq = task_rq_lock(p, &flags); 2612 ns = p->se.sum_exec_runtime + do_task_delta_exec(p, rq); 2613 task_rq_unlock(rq, p, &flags); 2614 2615 return ns; 2616} 2617 2618/* 2619 * This function gets called by the timer code, with HZ frequency. 2620 * We call it with interrupts disabled. 2621 */ 2622void scheduler_tick(void) 2623{ 2624 int cpu = smp_processor_id(); 2625 struct rq *rq = cpu_rq(cpu); 2626 struct task_struct *curr = rq->curr; 2627 2628 sched_clock_tick(); 2629 2630 raw_spin_lock(&rq->lock); 2631 update_rq_clock(rq); 2632 update_cpu_load_active(rq); 2633 curr->sched_class->task_tick(rq, curr, 0); 2634 raw_spin_unlock(&rq->lock); 2635 2636 perf_event_task_tick(); 2637 2638#ifdef CONFIG_SMP 2639 rq->idle_balance = idle_cpu(cpu); 2640 trigger_load_balance(rq, cpu); 2641#endif 2642} 2643 2644notrace unsigned long get_parent_ip(unsigned long addr) 2645{ 2646 if (in_lock_functions(addr)) { 2647 addr = CALLER_ADDR2; 2648 if (in_lock_functions(addr)) 2649 addr = CALLER_ADDR3; 2650 } 2651 return addr; 2652} 2653 2654#if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \ 2655 defined(CONFIG_PREEMPT_TRACER)) 2656 2657void __kprobes add_preempt_count(int val) 2658{ 2659#ifdef CONFIG_DEBUG_PREEMPT 2660 /* 2661 * Underflow? 2662 */ 2663 if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0))) 2664 return; 2665#endif 2666 preempt_count() += val; 2667#ifdef CONFIG_DEBUG_PREEMPT 2668 /* 2669 * Spinlock count overflowing soon? 2670 */ 2671 DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >= 2672 PREEMPT_MASK - 10); 2673#endif 2674 if (preempt_count() == val) 2675 trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1)); 2676} 2677EXPORT_SYMBOL(add_preempt_count); 2678 2679void __kprobes sub_preempt_count(int val) 2680{ 2681#ifdef CONFIG_DEBUG_PREEMPT 2682 /* 2683 * Underflow? 2684 */ 2685 if (DEBUG_LOCKS_WARN_ON(val > preempt_count())) 2686 return; 2687 /* 2688 * Is the spinlock portion underflowing? 2689 */ 2690 if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) && 2691 !(preempt_count() & PREEMPT_MASK))) 2692 return; 2693#endif 2694 2695 if (preempt_count() == val) 2696 trace_preempt_on(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1)); 2697 preempt_count() -= val; 2698} 2699EXPORT_SYMBOL(sub_preempt_count); 2700 2701#endif 2702 2703/* 2704 * Print scheduling while atomic bug: 2705 */ 2706static noinline void __schedule_bug(struct task_struct *prev) 2707{ 2708 if (oops_in_progress) 2709 return; 2710 2711 printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n", 2712 prev->comm, prev->pid, preempt_count()); 2713 2714 debug_show_held_locks(prev); 2715 print_modules(); 2716 if (irqs_disabled()) 2717 print_irqtrace_events(prev); 2718 dump_stack(); 2719 add_taint(TAINT_WARN); 2720} 2721 2722/* 2723 * Various schedule()-time debugging checks and statistics: 2724 */ 2725static inline void schedule_debug(struct task_struct *prev) 2726{ 2727 /* 2728 * Test if we are atomic. Since do_exit() needs to call into 2729 * schedule() atomically, we ignore that path for now. 2730 * Otherwise, whine if we are scheduling when we should not be. 2731 */ 2732 if (unlikely(in_atomic_preempt_off() && !prev->exit_state)) 2733 __schedule_bug(prev); 2734 rcu_sleep_check(); 2735 2736 profile_hit(SCHED_PROFILING, __builtin_return_address(0)); 2737 2738 schedstat_inc(this_rq(), sched_count); 2739} 2740 2741static void put_prev_task(struct rq *rq, struct task_struct *prev) 2742{ 2743 if (prev->on_rq || rq->skip_clock_update < 0) 2744 update_rq_clock(rq); 2745 prev->sched_class->put_prev_task(rq, prev); 2746} 2747 2748/* 2749 * Pick up the highest-prio task: 2750 */ 2751static inline struct task_struct * 2752pick_next_task(struct rq *rq) 2753{ 2754 const struct sched_class *class; 2755 struct task_struct *p; 2756 2757 /* 2758 * Optimization: we know that if all tasks are in 2759 * the fair class we can call that function directly: 2760 */ 2761 if (likely(rq->nr_running == rq->cfs.h_nr_running)) { 2762 p = fair_sched_class.pick_next_task(rq); 2763 if (likely(p)) 2764 return p; 2765 } 2766 2767 for_each_class(class) { 2768 p = class->pick_next_task(rq); 2769 if (p) 2770 return p; 2771 } 2772 2773 BUG(); /* the idle class will always have a runnable task */ 2774} 2775 2776/* 2777 * __schedule() is the main scheduler function. 2778 * 2779 * The main means of driving the scheduler and thus entering this function are: 2780 * 2781 * 1. Explicit blocking: mutex, semaphore, waitqueue, etc. 2782 * 2783 * 2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return 2784 * paths. For example, see arch/x86/entry_64.S. 2785 * 2786 * To drive preemption between tasks, the scheduler sets the flag in timer 2787 * interrupt handler scheduler_tick(). 2788 * 2789 * 3. Wakeups don't really cause entry into schedule(). They add a 2790 * task to the run-queue and that's it. 2791 * 2792 * Now, if the new task added to the run-queue preempts the current 2793 * task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets 2794 * called on the nearest possible occasion: 2795 * 2796 * - If the kernel is preemptible (CONFIG_PREEMPT=y): 2797 * 2798 * - in syscall or exception context, at the next outmost 2799 * preempt_enable(). (this might be as soon as the wake_up()'s 2800 * spin_unlock()!) 2801 * 2802 * - in IRQ context, return from interrupt-handler to 2803 * preemptible context 2804 * 2805 * - If the kernel is not preemptible (CONFIG_PREEMPT is not set) 2806 * then at the next: 2807 * 2808 * - cond_resched() call 2809 * - explicit schedule() call 2810 * - return from syscall or exception to user-space 2811 * - return from interrupt-handler to user-space 2812 */ 2813static void __sched __schedule(void) 2814{ 2815 struct task_struct *prev, *next; 2816 unsigned long *switch_count; 2817 struct rq *rq; 2818 int cpu; 2819 2820need_resched: 2821 preempt_disable(); 2822 cpu = smp_processor_id(); 2823 rq = cpu_rq(cpu); 2824 rcu_note_context_switch(cpu); 2825 prev = rq->curr; 2826 2827 schedule_debug(prev); 2828 2829 if (sched_feat(HRTICK)) 2830 hrtick_clear(rq); 2831 2832 raw_spin_lock_irq(&rq->lock); 2833 2834 switch_count = &prev->nivcsw; 2835 if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) { 2836 if (unlikely(signal_pending_state(prev->state, prev))) { 2837 prev->state = TASK_RUNNING; 2838 } else { 2839 deactivate_task(rq, prev, DEQUEUE_SLEEP); 2840 prev->on_rq = 0; 2841 2842 /* 2843 * If a worker went to sleep, notify and ask workqueue 2844 * whether it wants to wake up a task to maintain 2845 * concurrency. 2846 */ 2847 if (prev->flags & PF_WQ_WORKER) { 2848 struct task_struct *to_wakeup; 2849 2850 to_wakeup = wq_worker_sleeping(prev, cpu); 2851 if (to_wakeup) 2852 try_to_wake_up_local(to_wakeup); 2853 } 2854 } 2855 switch_count = &prev->nvcsw; 2856 } 2857 2858 pre_schedule(rq, prev); 2859 2860 if (unlikely(!rq->nr_running)) 2861 idle_balance(cpu, rq); 2862 2863 put_prev_task(rq, prev); 2864 next = pick_next_task(rq); 2865 clear_tsk_need_resched(prev); 2866 rq->skip_clock_update = 0; 2867 2868 if (likely(prev != next)) { 2869 rq->nr_switches++; 2870 rq->curr = next; 2871 ++*switch_count; 2872 2873 context_switch(rq, prev, next); /* unlocks the rq */ 2874 /* 2875 * The context switch have flipped the stack from under us 2876 * and restored the local variables which were saved when 2877 * this task called schedule() in the past. prev == current 2878 * is still correct, but it can be moved to another cpu/rq. 2879 */ 2880 cpu = smp_processor_id(); 2881 rq = cpu_rq(cpu); 2882 } else 2883 raw_spin_unlock_irq(&rq->lock); 2884 2885 post_schedule(rq); 2886 2887 sched_preempt_enable_no_resched(); 2888 if (need_resched()) 2889 goto need_resched; 2890} 2891 2892static inline void sched_submit_work(struct task_struct *tsk) 2893{ 2894 if (!tsk->state || tsk_is_pi_blocked(tsk)) 2895 return; 2896 /* 2897 * If we are going to sleep and we have plugged IO queued, 2898 * make sure to submit it to avoid deadlocks. 2899 */ 2900 if (blk_needs_flush_plug(tsk)) 2901 blk_schedule_flush_plug(tsk); 2902} 2903 2904asmlinkage void __sched schedule(void) 2905{ 2906 struct task_struct *tsk = current; 2907 2908 sched_submit_work(tsk); 2909 __schedule(); 2910} 2911EXPORT_SYMBOL(schedule); 2912 2913/** 2914 * schedule_preempt_disabled - called with preemption disabled 2915 * 2916 * Returns with preemption disabled. Note: preempt_count must be 1 2917 */ 2918void __sched schedule_preempt_disabled(void) 2919{ 2920 sched_preempt_enable_no_resched(); 2921 schedule(); 2922 preempt_disable(); 2923} 2924 2925#ifdef CONFIG_MUTEX_SPIN_ON_OWNER 2926 2927static inline bool owner_running(struct mutex *lock, struct task_struct *owner) 2928{ 2929 if (lock->owner != owner) 2930 return false; 2931 2932 /* 2933 * Ensure we emit the owner->on_cpu, dereference _after_ checking 2934 * lock->owner still matches owner, if that fails, owner might 2935 * point to free()d memory, if it still matches, the rcu_read_lock() 2936 * ensures the memory stays valid. 2937 */ 2938 barrier(); 2939 2940 return owner->on_cpu; 2941} 2942 2943/* 2944 * Look out! "owner" is an entirely speculative pointer 2945 * access and not reliable. 2946 */ 2947int mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner) 2948{ 2949 if (!sched_feat(OWNER_SPIN)) 2950 return 0; 2951 2952 rcu_read_lock(); 2953 while (owner_running(lock, owner)) { 2954 if (need_resched()) 2955 break; 2956 2957 arch_mutex_cpu_relax(); 2958 } 2959 rcu_read_unlock(); 2960 2961 /* 2962 * We break out the loop above on need_resched() and when the 2963 * owner changed, which is a sign for heavy contention. Return 2964 * success only when lock->owner is NULL. 2965 */ 2966 return lock->owner == NULL; 2967} 2968#endif 2969 2970#ifdef CONFIG_PREEMPT 2971/* 2972 * this is the entry point to schedule() from in-kernel preemption 2973 * off of preempt_enable. Kernel preemptions off return from interrupt 2974 * occur there and call schedule directly. 2975 */ 2976asmlinkage void __sched notrace preempt_schedule(void) 2977{ 2978 struct thread_info *ti = current_thread_info(); 2979 2980 /* 2981 * If there is a non-zero preempt_count or interrupts are disabled, 2982 * we do not want to preempt the current task. Just return.. 2983 */ 2984 if (likely(ti->preempt_count || irqs_disabled())) 2985 return; 2986 2987 do { 2988 add_preempt_count_notrace(PREEMPT_ACTIVE); 2989 __schedule(); 2990 sub_preempt_count_notrace(PREEMPT_ACTIVE); 2991 2992 /* 2993 * Check again in case we missed a preemption opportunity 2994 * between schedule and now. 2995 */ 2996 barrier(); 2997 } while (need_resched()); 2998} 2999EXPORT_SYMBOL(preempt_schedule); 3000 3001/* 3002 * this is the entry point to schedule() from kernel preemption 3003 * off of irq context. 3004 * Note, that this is called and return with irqs disabled. This will 3005 * protect us against recursive calling from irq. 3006 */ 3007asmlinkage void __sched preempt_schedule_irq(void) 3008{ 3009 struct thread_info *ti = current_thread_info(); 3010 3011 /* Catch callers which need to be fixed */ 3012 BUG_ON(ti->preempt_count || !irqs_disabled()); 3013 3014 do { 3015 add_preempt_count(PREEMPT_ACTIVE); 3016 local_irq_enable(); 3017 __schedule(); 3018 local_irq_disable(); 3019 sub_preempt_count(PREEMPT_ACTIVE); 3020 3021 /* 3022 * Check again in case we missed a preemption opportunity 3023 * between schedule and now. 3024 */ 3025 barrier(); 3026 } while (need_resched()); 3027} 3028 3029#endif /* CONFIG_PREEMPT */ 3030 3031int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags, 3032 void *key) 3033{ 3034 return try_to_wake_up(curr->private, mode, wake_flags); 3035} 3036EXPORT_SYMBOL(default_wake_function); 3037 3038/* 3039 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just 3040 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve 3041 * number) then we wake all the non-exclusive tasks and one exclusive task. 3042 * 3043 * There are circumstances in which we can try to wake a task which has already 3044 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns 3045 * zero in this (rare) case, and we handle it by continuing to scan the queue. 3046 */ 3047static void __wake_up_common(wait_queue_head_t *q, unsigned int mode, 3048 int nr_exclusive, int wake_flags, void *key) 3049{ 3050 wait_queue_t *curr, *next; 3051 3052 list_for_each_entry_safe(curr, next, &q->task_list, task_list) { 3053 unsigned flags = curr->flags; 3054 3055 if (curr->func(curr, mode, wake_flags, key) && 3056 (flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive) 3057 break; 3058 } 3059} 3060 3061/** 3062 * __wake_up - wake up threads blocked on a waitqueue. 3063 * @q: the waitqueue 3064 * @mode: which threads 3065 * @nr_exclusive: how many wake-one or wake-many threads to wake up 3066 * @key: is directly passed to the wakeup function 3067 * 3068 * It may be assumed that this function implies a write memory barrier before 3069 * changing the task state if and only if any tasks are woken up. 3070 */ 3071void __wake_up(wait_queue_head_t *q, unsigned int mode, 3072 int nr_exclusive, void *key) 3073{ 3074 unsigned long flags; 3075 3076 spin_lock_irqsave(&q->lock, flags); 3077 __wake_up_common(q, mode, nr_exclusive, 0, key); 3078 spin_unlock_irqrestore(&q->lock, flags); 3079} 3080EXPORT_SYMBOL(__wake_up); 3081 3082/* 3083 * Same as __wake_up but called with the spinlock in wait_queue_head_t held. 3084 */ 3085void __wake_up_locked(wait_queue_head_t *q, unsigned int mode, int nr) 3086{ 3087 __wake_up_common(q, mode, nr, 0, NULL); 3088} 3089EXPORT_SYMBOL_GPL(__wake_up_locked); 3090 3091void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key) 3092{ 3093 __wake_up_common(q, mode, 1, 0, key); 3094} 3095EXPORT_SYMBOL_GPL(__wake_up_locked_key); 3096 3097/** 3098 * __wake_up_sync_key - wake up threads blocked on a waitqueue. 3099 * @q: the waitqueue 3100 * @mode: which threads 3101 * @nr_exclusive: how many wake-one or wake-many threads to wake up 3102 * @key: opaque value to be passed to wakeup targets 3103 * 3104 * The sync wakeup differs that the waker knows that it will schedule 3105 * away soon, so while the target thread will be woken up, it will not 3106 * be migrated to another CPU - ie. the two threads are 'synchronized' 3107 * with each other. This can prevent needless bouncing between CPUs. 3108 * 3109 * On UP it can prevent extra preemption. 3110 * 3111 * It may be assumed that this function implies a write memory barrier before 3112 * changing the task state if and only if any tasks are woken up. 3113 */ 3114void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode, 3115 int nr_exclusive, void *key) 3116{ 3117 unsigned long flags; 3118 int wake_flags = WF_SYNC; 3119 3120 if (unlikely(!q)) 3121 return; 3122 3123 if (unlikely(!nr_exclusive)) 3124 wake_flags = 0; 3125 3126 spin_lock_irqsave(&q->lock, flags); 3127 __wake_up_common(q, mode, nr_exclusive, wake_flags, key); 3128 spin_unlock_irqrestore(&q->lock, flags); 3129} 3130EXPORT_SYMBOL_GPL(__wake_up_sync_key); 3131 3132/* 3133 * __wake_up_sync - see __wake_up_sync_key() 3134 */ 3135void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive) 3136{ 3137 __wake_up_sync_key(q, mode, nr_exclusive, NULL); 3138} 3139EXPORT_SYMBOL_GPL(__wake_up_sync); /* For internal use only */ 3140 3141/** 3142 * complete: - signals a single thread waiting on this completion 3143 * @x: holds the state of this particular completion 3144 * 3145 * This will wake up a single thread waiting on this completion. Threads will be 3146 * awakened in the same order in which they were queued. 3147 * 3148 * See also complete_all(), wait_for_completion() and related routines. 3149 * 3150 * It may be assumed that this function implies a write memory barrier before 3151 * changing the task state if and only if any tasks are woken up. 3152 */ 3153void complete(struct completion *x) 3154{ 3155 unsigned long flags; 3156 3157 spin_lock_irqsave(&x->wait.lock, flags); 3158 x->done++; 3159 __wake_up_common(&x->wait, TASK_NORMAL, 1, 0, NULL); 3160 spin_unlock_irqrestore(&x->wait.lock, flags); 3161} 3162EXPORT_SYMBOL(complete); 3163 3164/** 3165 * complete_all: - signals all threads waiting on this completion 3166 * @x: holds the state of this particular completion 3167 * 3168 * This will wake up all threads waiting on this particular completion event. 3169 * 3170 * It may be assumed that this function implies a write memory barrier before 3171 * changing the task state if and only if any tasks are woken up. 3172 */ 3173void complete_all(struct completion *x) 3174{ 3175 unsigned long flags; 3176 3177 spin_lock_irqsave(&x->wait.lock, flags); 3178 x->done += UINT_MAX/2; 3179 __wake_up_common(&x->wait, TASK_NORMAL, 0, 0, NULL); 3180 spin_unlock_irqrestore(&x->wait.lock, flags); 3181} 3182EXPORT_SYMBOL(complete_all); 3183 3184static inline long __sched 3185do_wait_for_common(struct completion *x, long timeout, int state) 3186{ 3187 if (!x->done) { 3188 DECLARE_WAITQUEUE(wait, current); 3189 3190 __add_wait_queue_tail_exclusive(&x->wait, &wait); 3191 do { 3192 if (signal_pending_state(state, current)) { 3193 timeout = -ERESTARTSYS; 3194 break; 3195 } 3196 __set_current_state(state); 3197 spin_unlock_irq(&x->wait.lock); 3198 timeout = schedule_timeout(timeout); 3199 spin_lock_irq(&x->wait.lock); 3200 } while (!x->done && timeout); 3201 __remove_wait_queue(&x->wait, &wait); 3202 if (!x->done) 3203 return timeout; 3204 } 3205 x->done--; 3206 return timeout ?: 1; 3207} 3208 3209static long __sched 3210wait_for_common(struct completion *x, long timeout, int state) 3211{ 3212 might_sleep(); 3213 3214 spin_lock_irq(&x->wait.lock); 3215 timeout = do_wait_for_common(x, timeout, state); 3216 spin_unlock_irq(&x->wait.lock); 3217 return timeout; 3218} 3219 3220/** 3221 * wait_for_completion: - waits for completion of a task 3222 * @x: holds the state of this particular completion 3223 * 3224 * This waits to be signaled for completion of a specific task. It is NOT 3225 * interruptible and there is no timeout. 3226 * 3227 * See also similar routines (i.e. wait_for_completion_timeout()) with timeout 3228 * and interrupt capability. Also see complete(). 3229 */ 3230void __sched wait_for_completion(struct completion *x) 3231{ 3232 wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_UNINTERRUPTIBLE); 3233} 3234EXPORT_SYMBOL(wait_for_completion); 3235 3236/** 3237 * wait_for_completion_timeout: - waits for completion of a task (w/timeout) 3238 * @x: holds the state of this particular completion 3239 * @timeout: timeout value in jiffies 3240 * 3241 * This waits for either a completion of a specific task to be signaled or for a 3242 * specified timeout to expire. The timeout is in jiffies. It is not 3243 * interruptible. 3244 * 3245 * The return value is 0 if timed out, and positive (at least 1, or number of 3246 * jiffies left till timeout) if completed. 3247 */ 3248unsigned long __sched 3249wait_for_completion_timeout(struct completion *x, unsigned long timeout) 3250{ 3251 return wait_for_common(x, timeout, TASK_UNINTERRUPTIBLE); 3252} 3253EXPORT_SYMBOL(wait_for_completion_timeout); 3254 3255/** 3256 * wait_for_completion_interruptible: - waits for completion of a task (w/intr) 3257 * @x: holds the state of this particular completion 3258 * 3259 * This waits for completion of a specific task to be signaled. It is 3260 * interruptible. 3261 * 3262 * The return value is -ERESTARTSYS if interrupted, 0 if completed. 3263 */ 3264int __sched wait_for_completion_interruptible(struct completion *x) 3265{ 3266 long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_INTERRUPTIBLE); 3267 if (t == -ERESTARTSYS) 3268 return t; 3269 return 0; 3270} 3271EXPORT_SYMBOL(wait_for_completion_interruptible); 3272 3273/** 3274 * wait_for_completion_interruptible_timeout: - waits for completion (w/(to,intr)) 3275 * @x: holds the state of this particular completion 3276 * @timeout: timeout value in jiffies 3277 * 3278 * This waits for either a completion of a specific task to be signaled or for a 3279 * specified timeout to expire. It is interruptible. The timeout is in jiffies. 3280 * 3281 * The return value is -ERESTARTSYS if interrupted, 0 if timed out, 3282 * positive (at least 1, or number of jiffies left till timeout) if completed. 3283 */ 3284long __sched 3285wait_for_completion_interruptible_timeout(struct completion *x, 3286 unsigned long timeout) 3287{ 3288 return wait_for_common(x, timeout, TASK_INTERRUPTIBLE); 3289} 3290EXPORT_SYMBOL(wait_for_completion_interruptible_timeout); 3291 3292/** 3293 * wait_for_completion_killable: - waits for completion of a task (killable) 3294 * @x: holds the state of this particular completion 3295 * 3296 * This waits to be signaled for completion of a specific task. It can be 3297 * interrupted by a kill signal. 3298 * 3299 * The return value is -ERESTARTSYS if interrupted, 0 if completed. 3300 */ 3301int __sched wait_for_completion_killable(struct completion *x) 3302{ 3303 long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_KILLABLE); 3304 if (t == -ERESTARTSYS) 3305 return t; 3306 return 0; 3307} 3308EXPORT_SYMBOL(wait_for_completion_killable); 3309 3310/** 3311 * wait_for_completion_killable_timeout: - waits for completion of a task (w/(to,killable)) 3312 * @x: holds the state of this particular completion 3313 * @timeout: timeout value in jiffies 3314 * 3315 * This waits for either a completion of a specific task to be 3316 * signaled or for a specified timeout to expire. It can be 3317 * interrupted by a kill signal. The timeout is in jiffies. 3318 * 3319 * The return value is -ERESTARTSYS if interrupted, 0 if timed out, 3320 * positive (at least 1, or number of jiffies left till timeout) if completed. 3321 */ 3322long __sched 3323wait_for_completion_killable_timeout(struct completion *x, 3324 unsigned long timeout) 3325{ 3326 return wait_for_common(x, timeout, TASK_KILLABLE); 3327} 3328EXPORT_SYMBOL(wait_for_completion_killable_timeout); 3329 3330/** 3331 * try_wait_for_completion - try to decrement a completion without blocking 3332 * @x: completion structure 3333 * 3334 * Returns: 0 if a decrement cannot be done without blocking 3335 * 1 if a decrement succeeded. 3336 * 3337 * If a completion is being used as a counting completion, 3338 * attempt to decrement the counter without blocking. This 3339 * enables us to avoid waiting if the resource the completion 3340 * is protecting is not available. 3341 */ 3342bool try_wait_for_completion(struct completion *x) 3343{ 3344 unsigned long flags; 3345 int ret = 1; 3346 3347 spin_lock_irqsave(&x->wait.lock, flags); 3348 if (!x->done) 3349 ret = 0; 3350 else 3351 x->done--; 3352 spin_unlock_irqrestore(&x->wait.lock, flags); 3353 return ret; 3354} 3355EXPORT_SYMBOL(try_wait_for_completion); 3356 3357/** 3358 * completion_done - Test to see if a completion has any waiters 3359 * @x: completion structure 3360 * 3361 * Returns: 0 if there are waiters (wait_for_completion() in progress) 3362 * 1 if there are no waiters. 3363 * 3364 */ 3365bool completion_done(struct completion *x) 3366{ 3367 unsigned long flags; 3368 int ret = 1; 3369 3370 spin_lock_irqsave(&x->wait.lock, flags); 3371 if (!x->done) 3372 ret = 0; 3373 spin_unlock_irqrestore(&x->wait.lock, flags); 3374 return ret; 3375} 3376EXPORT_SYMBOL(completion_done); 3377 3378static long __sched 3379sleep_on_common(wait_queue_head_t *q, int state, long timeout) 3380{ 3381 unsigned long flags; 3382 wait_queue_t wait; 3383 3384 init_waitqueue_entry(&wait, current); 3385 3386 __set_current_state(state); 3387 3388 spin_lock_irqsave(&q->lock, flags); 3389 __add_wait_queue(q, &wait); 3390 spin_unlock(&q->lock); 3391 timeout = schedule_timeout(timeout); 3392 spin_lock_irq(&q->lock); 3393 __remove_wait_queue(q, &wait); 3394 spin_unlock_irqrestore(&q->lock, flags); 3395 3396 return timeout; 3397} 3398 3399void __sched interruptible_sleep_on(wait_queue_head_t *q) 3400{ 3401 sleep_on_common(q, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); 3402} 3403EXPORT_SYMBOL(interruptible_sleep_on); 3404 3405long __sched 3406interruptible_sleep_on_timeout(wait_queue_head_t *q, long timeout) 3407{ 3408 return sleep_on_common(q, TASK_INTERRUPTIBLE, timeout); 3409} 3410EXPORT_SYMBOL(interruptible_sleep_on_timeout); 3411 3412void __sched sleep_on(wait_queue_head_t *q) 3413{ 3414 sleep_on_common(q, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); 3415} 3416EXPORT_SYMBOL(sleep_on); 3417 3418long __sched sleep_on_timeout(wait_queue_head_t *q, long timeout) 3419{ 3420 return sleep_on_common(q, TASK_UNINTERRUPTIBLE, timeout); 3421} 3422EXPORT_SYMBOL(sleep_on_timeout); 3423 3424#ifdef CONFIG_RT_MUTEXES 3425 3426/* 3427 * rt_mutex_setprio - set the current priority of a task 3428 * @p: task 3429 * @prio: prio value (kernel-internal form) 3430 * 3431 * This function changes the 'effective' priority of a task. It does 3432 * not touch ->normal_prio like __setscheduler(). 3433 * 3434 * Used by the rt_mutex code to implement priority inheritance logic. 3435 */ 3436void rt_mutex_setprio(struct task_struct *p, int prio) 3437{ 3438 int oldprio, on_rq, running; 3439 struct rq *rq; 3440 const struct sched_class *prev_class; 3441 3442 BUG_ON(prio < 0 || prio > MAX_PRIO); 3443 3444 rq = __task_rq_lock(p); 3445 3446 /* 3447 * Idle task boosting is a nono in general. There is one 3448 * exception, when PREEMPT_RT and NOHZ is active: 3449 * 3450 * The idle task calls get_next_timer_interrupt() and holds 3451 * the timer wheel base->lock on the CPU and another CPU wants 3452 * to access the timer (probably to cancel it). We can safely 3453 * ignore the boosting request, as the idle CPU runs this code 3454 * with interrupts disabled and will complete the lock 3455 * protected section without being interrupted. So there is no 3456 * real need to boost. 3457 */ 3458 if (unlikely(p == rq->idle)) { 3459 WARN_ON(p != rq->curr); 3460 WARN_ON(p->pi_blocked_on); 3461 goto out_unlock; 3462 } 3463 3464 trace_sched_pi_setprio(p, prio); 3465 oldprio = p->prio; 3466 prev_class = p->sched_class; 3467 on_rq = p->on_rq; 3468 running = task_current(rq, p); 3469 if (on_rq) 3470 dequeue_task(rq, p, 0); 3471 if (running) 3472 p->sched_class->put_prev_task(rq, p); 3473 3474 if (rt_prio(prio)) 3475 p->sched_class = &rt_sched_class; 3476 else 3477 p->sched_class = &fair_sched_class; 3478 3479 p->prio = prio; 3480 3481 if (running) 3482 p->sched_class->set_curr_task(rq); 3483 if (on_rq) 3484 enqueue_task(rq, p, oldprio < prio ? ENQUEUE_HEAD : 0); 3485 3486 check_class_changed(rq, p, prev_class, oldprio); 3487out_unlock: 3488 __task_rq_unlock(rq); 3489} 3490#endif 3491void set_user_nice(struct task_struct *p, long nice) 3492{ 3493 int old_prio, delta, on_rq; 3494 unsigned long flags; 3495 struct rq *rq; 3496 3497 if (TASK_NICE(p) == nice || nice < -20 || nice > 19) 3498 return; 3499 /* 3500 * We have to be careful, if called from sys_setpriority(), 3501 * the task might be in the middle of scheduling on another CPU. 3502 */ 3503 rq = task_rq_lock(p, &flags); 3504 /* 3505 * The RT priorities are set via sched_setscheduler(), but we still 3506 * allow the 'normal' nice value to be set - but as expected 3507 * it wont have any effect on scheduling until the task is 3508 * SCHED_FIFO/SCHED_RR: 3509 */ 3510 if (task_has_rt_policy(p)) { 3511 p->static_prio = NICE_TO_PRIO(nice); 3512 goto out_unlock; 3513 } 3514 on_rq = p->on_rq; 3515 if (on_rq) 3516 dequeue_task(rq, p, 0); 3517 3518 p->static_prio = NICE_TO_PRIO(nice); 3519 set_load_weight(p); 3520 old_prio = p->prio; 3521 p->prio = effective_prio(p); 3522 delta = p->prio - old_prio; 3523 3524 if (on_rq) { 3525 enqueue_task(rq, p, 0); 3526 /* 3527 * If the task increased its priority or is running and 3528 * lowered its priority, then reschedule its CPU: 3529 */ 3530 if (delta < 0 || (delta > 0 && task_running(rq, p))) 3531 resched_task(rq->curr); 3532 } 3533out_unlock: 3534 task_rq_unlock(rq, p, &flags); 3535} 3536EXPORT_SYMBOL(set_user_nice); 3537 3538/* 3539 * can_nice - check if a task can reduce its nice value 3540 * @p: task 3541 * @nice: nice value 3542 */ 3543int can_nice(const struct task_struct *p, const int nice) 3544{ 3545 /* convert nice value [19,-20] to rlimit style value [1,40] */ 3546 int nice_rlim = 20 - nice; 3547 3548 return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) || 3549 capable(CAP_SYS_NICE)); 3550} 3551 3552#ifdef __ARCH_WANT_SYS_NICE 3553 3554/* 3555 * sys_nice - change the priority of the current process. 3556 * @increment: priority increment 3557 * 3558 * sys_setpriority is a more generic, but much slower function that 3559 * does similar things. 3560 */ 3561SYSCALL_DEFINE1(nice, int, increment) 3562{ 3563 long nice, retval; 3564 3565 /* 3566 * Setpriority might change our priority at the same moment. 3567 * We don't have to worry. Conceptually one call occurs first 3568 * and we have a single winner. 3569 */ 3570 if (increment < -40) 3571 increment = -40; 3572 if (increment > 40) 3573 increment = 40; 3574 3575 nice = TASK_NICE(current) + increment; 3576 if (nice < -20) 3577 nice = -20; 3578 if (nice > 19) 3579 nice = 19; 3580 3581 if (increment < 0 && !can_nice(current, nice)) 3582 return -EPERM; 3583 3584 retval = security_task_setnice(current, nice); 3585 if (retval) 3586 return retval; 3587 3588 set_user_nice(current, nice); 3589 return 0; 3590} 3591 3592#endif 3593 3594/** 3595 * task_prio - return the priority value of a given task. 3596 * @p: the task in question. 3597 * 3598 * This is the priority value as seen by users in /proc. 3599 * RT tasks are offset by -200. Normal tasks are centered 3600 * around 0, value goes from -16 to +15. 3601 */ 3602int task_prio(const struct task_struct *p) 3603{ 3604 return p->prio - MAX_RT_PRIO; 3605} 3606 3607/** 3608 * task_nice - return the nice value of a given task. 3609 * @p: the task in question. 3610 */ 3611int task_nice(const struct task_struct *p) 3612{ 3613 return TASK_NICE(p); 3614} 3615EXPORT_SYMBOL(task_nice); 3616 3617/** 3618 * idle_cpu - is a given cpu idle currently? 3619 * @cpu: the processor in question. 3620 */ 3621int idle_cpu(int cpu) 3622{ 3623 struct rq *rq = cpu_rq(cpu); 3624 3625 if (rq->curr != rq->idle) 3626 return 0; 3627 3628 if (rq->nr_running) 3629 return 0; 3630 3631#ifdef CONFIG_SMP 3632 if (!llist_empty(&rq->wake_list)) 3633 return 0; 3634#endif 3635 3636 return 1; 3637} 3638 3639/** 3640 * idle_task - return the idle task for a given cpu. 3641 * @cpu: the processor in question. 3642 */ 3643struct task_struct *idle_task(int cpu) 3644{ 3645 return cpu_rq(cpu)->idle; 3646} 3647 3648/** 3649 * find_process_by_pid - find a process with a matching PID value. 3650 * @pid: the pid in question. 3651 */ 3652static struct task_struct *find_process_by_pid(pid_t pid) 3653{ 3654 return pid ? find_task_by_vpid(pid) : current; 3655} 3656 3657/* Actually do priority change: must hold rq lock. */ 3658static void 3659__setscheduler(struct rq *rq, struct task_struct *p, int policy, int prio) 3660{ 3661 p->policy = policy; 3662 p->rt_priority = prio; 3663 p->normal_prio = normal_prio(p); 3664 /* we are holding p->pi_lock already */ 3665 p->prio = rt_mutex_getprio(p); 3666 if (rt_prio(p->prio)) 3667 p->sched_class = &rt_sched_class; 3668 else 3669 p->sched_class = &fair_sched_class; 3670 set_load_weight(p); 3671} 3672 3673/* 3674 * check the target process has a UID that matches the current process's 3675 */ 3676static bool check_same_owner(struct task_struct *p) 3677{ 3678 const struct cred *cred = current_cred(), *pcred; 3679 bool match; 3680 3681 rcu_read_lock(); 3682 pcred = __task_cred(p); 3683 match = (uid_eq(cred->euid, pcred->euid) || 3684 uid_eq(cred->euid, pcred->uid)); 3685 rcu_read_unlock(); 3686 return match; 3687} 3688 3689static int __sched_setscheduler(struct task_struct *p, int policy, 3690 const struct sched_param *param, bool user) 3691{ 3692 int retval, oldprio, oldpolicy = -1, on_rq, running; 3693 unsigned long flags; 3694 const struct sched_class *prev_class; 3695 struct rq *rq; 3696 int reset_on_fork; 3697 3698 /* may grab non-irq protected spin_locks */ 3699 BUG_ON(in_interrupt()); 3700recheck: 3701 /* double check policy once rq lock held */ 3702 if (policy < 0) { 3703 reset_on_fork = p->sched_reset_on_fork; 3704 policy = oldpolicy = p->policy; 3705 } else { 3706 reset_on_fork = !!(policy & SCHED_RESET_ON_FORK); 3707 policy &= ~SCHED_RESET_ON_FORK; 3708 3709 if (policy != SCHED_FIFO && policy != SCHED_RR && 3710 policy != SCHED_NORMAL && policy != SCHED_BATCH && 3711 policy != SCHED_IDLE) 3712 return -EINVAL; 3713 } 3714 3715 /* 3716 * Valid priorities for SCHED_FIFO and SCHED_RR are 3717 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL, 3718 * SCHED_BATCH and SCHED_IDLE is 0. 3719 */ 3720 if (param->sched_priority < 0 || 3721 (p->mm && param->sched_priority > MAX_USER_RT_PRIO-1) || 3722 (!p->mm && param->sched_priority > MAX_RT_PRIO-1)) 3723 return -EINVAL; 3724 if (rt_policy(policy) != (param->sched_priority != 0)) 3725 return -EINVAL; 3726 3727 /* 3728 * Allow unprivileged RT tasks to decrease priority: 3729 */ 3730 if (user && !capable(CAP_SYS_NICE)) { 3731 if (rt_policy(policy)) { 3732 unsigned long rlim_rtprio = 3733 task_rlimit(p, RLIMIT_RTPRIO); 3734 3735 /* can't set/change the rt policy */ 3736 if (policy != p->policy && !rlim_rtprio) 3737 return -EPERM; 3738 3739 /* can't increase priority */ 3740 if (param->sched_priority > p->rt_priority && 3741 param->sched_priority > rlim_rtprio) 3742 return -EPERM; 3743 } 3744 3745 /* 3746 * Treat SCHED_IDLE as nice 20. Only allow a switch to 3747 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it. 3748 */ 3749 if (p->policy == SCHED_IDLE && policy != SCHED_IDLE) { 3750 if (!can_nice(p, TASK_NICE(p))) 3751 return -EPERM; 3752 } 3753 3754 /* can't change other user's priorities */ 3755 if (!check_same_owner(p)) 3756 return -EPERM; 3757 3758 /* Normal users shall not reset the sched_reset_on_fork flag */ 3759 if (p->sched_reset_on_fork && !reset_on_fork) 3760 return -EPERM; 3761 } 3762 3763 if (user) { 3764 retval = security_task_setscheduler(p); 3765 if (retval) 3766 return retval; 3767 } 3768 3769 /* 3770 * make sure no PI-waiters arrive (or leave) while we are 3771 * changing the priority of the task: 3772 * 3773 * To be able to change p->policy safely, the appropriate 3774 * runqueue lock must be held. 3775 */ 3776 rq = task_rq_lock(p, &flags); 3777 3778 /* 3779 * Changing the policy of the stop threads its a very bad idea 3780 */ 3781 if (p == rq->stop) { 3782 task_rq_unlock(rq, p, &flags); 3783 return -EINVAL; 3784 } 3785 3786 /* 3787 * If not changing anything there's no need to proceed further: 3788 */ 3789 if (unlikely(policy == p->policy && (!rt_policy(policy) || 3790 param->sched_priority == p->rt_priority))) { 3791 task_rq_unlock(rq, p, &flags); 3792 return 0; 3793 } 3794 3795#ifdef CONFIG_RT_GROUP_SCHED 3796 if (user) { 3797 /* 3798 * Do not allow realtime tasks into groups that have no runtime 3799 * assigned. 3800 */ 3801 if (rt_bandwidth_enabled() && rt_policy(policy) && 3802 task_group(p)->rt_bandwidth.rt_runtime == 0 && 3803 !task_group_is_autogroup(task_group(p))) { 3804 task_rq_unlock(rq, p, &flags); 3805 return -EPERM; 3806 } 3807 } 3808#endif 3809 3810 /* recheck policy now with rq lock held */ 3811 if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) { 3812 policy = oldpolicy = -1; 3813 task_rq_unlock(rq, p, &flags); 3814 goto recheck; 3815 } 3816 on_rq = p->on_rq; 3817 running = task_current(rq, p); 3818 if (on_rq) 3819 dequeue_task(rq, p, 0); 3820 if (running) 3821 p->sched_class->put_prev_task(rq, p); 3822 3823 p->sched_reset_on_fork = reset_on_fork; 3824 3825 oldprio = p->prio; 3826 prev_class = p->sched_class; 3827 __setscheduler(rq, p, policy, param->sched_priority); 3828 3829 if (running) 3830 p->sched_class->set_curr_task(rq); 3831 if (on_rq) 3832 enqueue_task(rq, p, 0); 3833 3834 check_class_changed(rq, p, prev_class, oldprio); 3835 task_rq_unlock(rq, p, &flags); 3836 3837 rt_mutex_adjust_pi(p); 3838 3839 return 0; 3840} 3841 3842/** 3843 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread. 3844 * @p: the task in question. 3845 * @policy: new policy. 3846 * @param: structure containing the new RT priority. 3847 * 3848 * NOTE that the task may be already dead. 3849 */ 3850int sched_setscheduler(struct task_struct *p, int policy, 3851 const struct sched_param *param) 3852{ 3853 return __sched_setscheduler(p, policy, param, true); 3854} 3855EXPORT_SYMBOL_GPL(sched_setscheduler); 3856 3857/** 3858 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace. 3859 * @p: the task in question. 3860 * @policy: new policy. 3861 * @param: structure containing the new RT priority. 3862 * 3863 * Just like sched_setscheduler, only don't bother checking if the 3864 * current context has permission. For example, this is needed in 3865 * stop_machine(): we create temporary high priority worker threads, 3866 * but our caller might not have that capability. 3867 */ 3868int sched_setscheduler_nocheck(struct task_struct *p, int policy, 3869 const struct sched_param *param) 3870{ 3871 return __sched_setscheduler(p, policy, param, false); 3872} 3873 3874static int 3875do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param) 3876{ 3877 struct sched_param lparam; 3878 struct task_struct *p; 3879 int retval; 3880 3881 if (!param || pid < 0) 3882 return -EINVAL; 3883 if (copy_from_user(&lparam, param, sizeof(struct sched_param))) 3884 return -EFAULT; 3885 3886 rcu_read_lock(); 3887 retval = -ESRCH; 3888 p = find_process_by_pid(pid); 3889 if (p != NULL) 3890 retval = sched_setscheduler(p, policy, &lparam); 3891 rcu_read_unlock(); 3892 3893 return retval; 3894} 3895 3896/** 3897 * sys_sched_setscheduler - set/change the scheduler policy and RT priority 3898 * @pid: the pid in question. 3899 * @policy: new policy. 3900 * @param: structure containing the new RT priority. 3901 */ 3902SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy, 3903 struct sched_param __user *, param) 3904{ 3905 /* negative values for policy are not valid */ 3906 if (policy < 0) 3907 return -EINVAL; 3908 3909 return do_sched_setscheduler(pid, policy, param); 3910} 3911 3912/** 3913 * sys_sched_setparam - set/change the RT priority of a thread 3914 * @pid: the pid in question. 3915 * @param: structure containing the new RT priority. 3916 */ 3917SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param) 3918{ 3919 return do_sched_setscheduler(pid, -1, param); 3920} 3921 3922/** 3923 * sys_sched_getscheduler - get the policy (scheduling class) of a thread 3924 * @pid: the pid in question. 3925 */ 3926SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid) 3927{ 3928 struct task_struct *p; 3929 int retval; 3930 3931 if (pid < 0) 3932 return -EINVAL; 3933 3934 retval = -ESRCH; 3935 rcu_read_lock(); 3936 p = find_process_by_pid(pid); 3937 if (p) { 3938 retval = security_task_getscheduler(p); 3939 if (!retval) 3940 retval = p->policy 3941 | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0); 3942 } 3943 rcu_read_unlock(); 3944 return retval; 3945} 3946 3947/** 3948 * sys_sched_getparam - get the RT priority of a thread 3949 * @pid: the pid in question. 3950 * @param: structure containing the RT priority. 3951 */ 3952SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param) 3953{ 3954 struct sched_param lp; 3955 struct task_struct *p; 3956 int retval; 3957 3958 if (!param || pid < 0) 3959 return -EINVAL; 3960 3961 rcu_read_lock(); 3962 p = find_process_by_pid(pid); 3963 retval = -ESRCH; 3964 if (!p) 3965 goto out_unlock; 3966 3967 retval = security_task_getscheduler(p); 3968 if (retval) 3969 goto out_unlock; 3970 3971 lp.sched_priority = p->rt_priority; 3972 rcu_read_unlock(); 3973 3974 /* 3975 * This one might sleep, we cannot do it with a spinlock held ... 3976 */ 3977 retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0; 3978 3979 return retval; 3980 3981out_unlock: 3982 rcu_read_unlock(); 3983 return retval; 3984} 3985 3986long sched_setaffinity(pid_t pid, const struct cpumask *in_mask) 3987{ 3988 cpumask_var_t cpus_allowed, new_mask; 3989 struct task_struct *p; 3990 int retval; 3991 3992 get_online_cpus(); 3993 rcu_read_lock(); 3994 3995 p = find_process_by_pid(pid); 3996 if (!p) { 3997 rcu_read_unlock(); 3998 put_online_cpus(); 3999 return -ESRCH; 4000 } 4001 4002 /* Prevent p going away */ 4003 get_task_struct(p); 4004 rcu_read_unlock(); 4005 4006 if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) { 4007 retval = -ENOMEM; 4008 goto out_put_task; 4009 } 4010 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) { 4011 retval = -ENOMEM; 4012 goto out_free_cpus_allowed; 4013 } 4014 retval = -EPERM; 4015 if (!check_same_owner(p) && !ns_capable(task_user_ns(p), CAP_SYS_NICE)) 4016 goto out_unlock; 4017 4018 retval = security_task_setscheduler(p); 4019 if (retval) 4020 goto out_unlock; 4021 4022 cpuset_cpus_allowed(p, cpus_allowed); 4023 cpumask_and(new_mask, in_mask, cpus_allowed); 4024again: 4025 retval = set_cpus_allowed_ptr(p, new_mask); 4026 4027 if (!retval) { 4028 cpuset_cpus_allowed(p, cpus_allowed); 4029 if (!cpumask_subset(new_mask, cpus_allowed)) { 4030 /* 4031 * We must have raced with a concurrent cpuset 4032 * update. Just reset the cpus_allowed to the 4033 * cpuset's cpus_allowed 4034 */ 4035 cpumask_copy(new_mask, cpus_allowed); 4036 goto again; 4037 } 4038 } 4039out_unlock: 4040 free_cpumask_var(new_mask); 4041out_free_cpus_allowed: 4042 free_cpumask_var(cpus_allowed); 4043out_put_task: 4044 put_task_struct(p); 4045 put_online_cpus(); 4046 return retval; 4047} 4048 4049static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len, 4050 struct cpumask *new_mask) 4051{ 4052 if (len < cpumask_size()) 4053 cpumask_clear(new_mask); 4054 else if (len > cpumask_size()) 4055 len = cpumask_size(); 4056 4057 return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0; 4058} 4059 4060/** 4061 * sys_sched_setaffinity - set the cpu affinity of a process 4062 * @pid: pid of the process 4063 * @len: length in bytes of the bitmask pointed to by user_mask_ptr 4064 * @user_mask_ptr: user-space pointer to the new cpu mask 4065 */ 4066SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len, 4067 unsigned long __user *, user_mask_ptr) 4068{ 4069 cpumask_var_t new_mask; 4070 int retval; 4071 4072 if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) 4073 return -ENOMEM; 4074 4075 retval = get_user_cpu_mask(user_mask_ptr, len, new_mask); 4076 if (retval == 0) 4077 retval = sched_setaffinity(pid, new_mask); 4078 free_cpumask_var(new_mask); 4079 return retval; 4080} 4081 4082long sched_getaffinity(pid_t pid, struct cpumask *mask) 4083{ 4084 struct task_struct *p; 4085 unsigned long flags; 4086 int retval; 4087 4088 get_online_cpus(); 4089 rcu_read_lock(); 4090 4091 retval = -ESRCH; 4092 p = find_process_by_pid(pid); 4093 if (!p) 4094 goto out_unlock; 4095 4096 retval = security_task_getscheduler(p); 4097 if (retval) 4098 goto out_unlock; 4099 4100 raw_spin_lock_irqsave(&p->pi_lock, flags); 4101 cpumask_and(mask, &p->cpus_allowed, cpu_online_mask); 4102 raw_spin_unlock_irqrestore(&p->pi_lock, flags); 4103 4104out_unlock: 4105 rcu_read_unlock(); 4106 put_online_cpus(); 4107 4108 return retval; 4109} 4110 4111/** 4112 * sys_sched_getaffinity - get the cpu affinity of a process 4113 * @pid: pid of the process 4114 * @len: length in bytes of the bitmask pointed to by user_mask_ptr 4115 * @user_mask_ptr: user-space pointer to hold the current cpu mask 4116 */ 4117SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len, 4118 unsigned long __user *, user_mask_ptr) 4119{ 4120 int ret; 4121 cpumask_var_t mask; 4122 4123 if ((len * BITS_PER_BYTE) < nr_cpu_ids) 4124 return -EINVAL; 4125 if (len & (sizeof(unsigned long)-1)) 4126 return -EINVAL; 4127 4128 if (!alloc_cpumask_var(&mask, GFP_KERNEL)) 4129 return -ENOMEM; 4130 4131 ret = sched_getaffinity(pid, mask); 4132 if (ret == 0) { 4133 size_t retlen = min_t(size_t, len, cpumask_size()); 4134 4135 if (copy_to_user(user_mask_ptr, mask, retlen)) 4136 ret = -EFAULT; 4137 else 4138 ret = retlen; 4139 } 4140 free_cpumask_var(mask); 4141 4142 return ret; 4143} 4144 4145/** 4146 * sys_sched_yield - yield the current processor to other threads. 4147 * 4148 * This function yields the current CPU to other tasks. If there are no 4149 * other threads running on this CPU then this function will return. 4150 */ 4151SYSCALL_DEFINE0(sched_yield) 4152{ 4153 struct rq *rq = this_rq_lock(); 4154 4155 schedstat_inc(rq, yld_count); 4156 current->sched_class->yield_task(rq); 4157 4158 /* 4159 * Since we are going to call schedule() anyway, there's 4160 * no need to preempt or enable interrupts: 4161 */ 4162 __release(rq->lock); 4163 spin_release(&rq->lock.dep_map, 1, _THIS_IP_); 4164 do_raw_spin_unlock(&rq->lock); 4165 sched_preempt_enable_no_resched(); 4166 4167 schedule(); 4168 4169 return 0; 4170} 4171 4172static inline int should_resched(void) 4173{ 4174 return need_resched() && !(preempt_count() & PREEMPT_ACTIVE); 4175} 4176 4177static void __cond_resched(void) 4178{ 4179 add_preempt_count(PREEMPT_ACTIVE); 4180 __schedule(); 4181 sub_preempt_count(PREEMPT_ACTIVE); 4182} 4183 4184int __sched _cond_resched(void) 4185{ 4186 if (should_resched()) { 4187 __cond_resched(); 4188 return 1; 4189 } 4190 return 0; 4191} 4192EXPORT_SYMBOL(_cond_resched); 4193 4194/* 4195 * __cond_resched_lock() - if a reschedule is pending, drop the given lock, 4196 * call schedule, and on return reacquire the lock. 4197 * 4198 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level 4199 * operations here to prevent schedule() from being called twice (once via 4200 * spin_unlock(), once by hand). 4201 */ 4202int __cond_resched_lock(spinlock_t *lock) 4203{ 4204 int resched = should_resched(); 4205 int ret = 0; 4206 4207 lockdep_assert_held(lock); 4208 4209 if (spin_needbreak(lock) || resched) { 4210 spin_unlock(lock); 4211 if (resched) 4212 __cond_resched(); 4213 else 4214 cpu_relax(); 4215 ret = 1; 4216 spin_lock(lock); 4217 } 4218 return ret; 4219} 4220EXPORT_SYMBOL(__cond_resched_lock); 4221 4222int __sched __cond_resched_softirq(void) 4223{ 4224 BUG_ON(!in_softirq()); 4225 4226 if (should_resched()) { 4227 local_bh_enable(); 4228 __cond_resched(); 4229 local_bh_disable(); 4230 return 1; 4231 } 4232 return 0; 4233} 4234EXPORT_SYMBOL(__cond_resched_softirq); 4235 4236/** 4237 * yield - yield the current processor to other threads. 4238 * 4239 * Do not ever use this function, there's a 99% chance you're doing it wrong. 4240 * 4241 * The scheduler is at all times free to pick the calling task as the most 4242 * eligible task to run, if removing the yield() call from your code breaks 4243 * it, its already broken. 4244 * 4245 * Typical broken usage is: 4246 * 4247 * while (!event) 4248 * yield(); 4249 * 4250 * where one assumes that yield() will let 'the other' process run that will 4251 * make event true. If the current task is a SCHED_FIFO task that will never 4252 * happen. Never use yield() as a progress guarantee!! 4253 * 4254 * If you want to use yield() to wait for something, use wait_event(). 4255 * If you want to use yield() to be 'nice' for others, use cond_resched(). 4256 * If you still want to use yield(), do not! 4257 */ 4258void __sched yield(void) 4259{ 4260 set_current_state(TASK_RUNNING); 4261 sys_sched_yield(); 4262} 4263EXPORT_SYMBOL(yield); 4264 4265/** 4266 * yield_to - yield the current processor to another thread in 4267 * your thread group, or accelerate that thread toward the 4268 * processor it's on. 4269 * @p: target task 4270 * @preempt: whether task preemption is allowed or not 4271 * 4272 * It's the caller's job to ensure that the target task struct 4273 * can't go away on us before we can do any checks. 4274 * 4275 * Returns true if we indeed boosted the target task. 4276 */ 4277bool __sched yield_to(struct task_struct *p, bool preempt) 4278{ 4279 struct task_struct *curr = current; 4280 struct rq *rq, *p_rq; 4281 unsigned long flags; 4282 bool yielded = 0; 4283 4284 local_irq_save(flags); 4285 rq = this_rq(); 4286 4287again: 4288 p_rq = task_rq(p); 4289 double_rq_lock(rq, p_rq); 4290 while (task_rq(p) != p_rq) { 4291 double_rq_unlock(rq, p_rq); 4292 goto again; 4293 } 4294 4295 if (!curr->sched_class->yield_to_task) 4296 goto out; 4297 4298 if (curr->sched_class != p->sched_class) 4299 goto out; 4300 4301 if (task_running(p_rq, p) || p->state) 4302 goto out; 4303 4304 yielded = curr->sched_class->yield_to_task(rq, p, preempt); 4305 if (yielded) { 4306 schedstat_inc(rq, yld_count); 4307 /* 4308 * Make p's CPU reschedule; pick_next_entity takes care of 4309 * fairness. 4310 */ 4311 if (preempt && rq != p_rq) 4312 resched_task(p_rq->curr); 4313 } 4314 4315out: 4316 double_rq_unlock(rq, p_rq); 4317 local_irq_restore(flags); 4318 4319 if (yielded) 4320 schedule(); 4321 4322 return yielded; 4323} 4324EXPORT_SYMBOL_GPL(yield_to); 4325 4326/* 4327 * This task is about to go to sleep on IO. Increment rq->nr_iowait so 4328 * that process accounting knows that this is a task in IO wait state. 4329 */ 4330void __sched io_schedule(void) 4331{ 4332 struct rq *rq = raw_rq(); 4333 4334 delayacct_blkio_start(); 4335 atomic_inc(&rq->nr_iowait); 4336 blk_flush_plug(current); 4337 current->in_iowait = 1; 4338 schedule(); 4339 current->in_iowait = 0; 4340 atomic_dec(&rq->nr_iowait); 4341 delayacct_blkio_end(); 4342} 4343EXPORT_SYMBOL(io_schedule); 4344 4345long __sched io_schedule_timeout(long timeout) 4346{ 4347 struct rq *rq = raw_rq(); 4348 long ret; 4349 4350 delayacct_blkio_start(); 4351 atomic_inc(&rq->nr_iowait); 4352 blk_flush_plug(current); 4353 current->in_iowait = 1; 4354 ret = schedule_timeout(timeout); 4355 current->in_iowait = 0; 4356 atomic_dec(&rq->nr_iowait); 4357 delayacct_blkio_end(); 4358 return ret; 4359} 4360 4361/** 4362 * sys_sched_get_priority_max - return maximum RT priority. 4363 * @policy: scheduling class. 4364 * 4365 * this syscall returns the maximum rt_priority that can be used 4366 * by a given scheduling class. 4367 */ 4368SYSCALL_DEFINE1(sched_get_priority_max, int, policy) 4369{ 4370 int ret = -EINVAL; 4371 4372 switch (policy) { 4373 case SCHED_FIFO: 4374 case SCHED_RR: 4375 ret = MAX_USER_RT_PRIO-1; 4376 break; 4377 case SCHED_NORMAL: 4378 case SCHED_BATCH: 4379 case SCHED_IDLE: 4380 ret = 0; 4381 break; 4382 } 4383 return ret; 4384} 4385 4386/** 4387 * sys_sched_get_priority_min - return minimum RT priority. 4388 * @policy: scheduling class. 4389 * 4390 * this syscall returns the minimum rt_priority that can be used 4391 * by a given scheduling class. 4392 */ 4393SYSCALL_DEFINE1(sched_get_priority_min, int, policy) 4394{ 4395 int ret = -EINVAL; 4396 4397 switch (policy) { 4398 case SCHED_FIFO: 4399 case SCHED_RR: 4400 ret = 1; 4401 break; 4402 case SCHED_NORMAL: 4403 case SCHED_BATCH: 4404 case SCHED_IDLE: 4405 ret = 0; 4406 } 4407 return ret; 4408} 4409 4410/** 4411 * sys_sched_rr_get_interval - return the default timeslice of a process. 4412 * @pid: pid of the process. 4413 * @interval: userspace pointer to the timeslice value. 4414 * 4415 * this syscall writes the default timeslice value of a given process 4416 * into the user-space timespec buffer. A value of '0' means infinity. 4417 */ 4418SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid, 4419 struct timespec __user *, interval) 4420{ 4421 struct task_struct *p; 4422 unsigned int time_slice; 4423 unsigned long flags; 4424 struct rq *rq; 4425 int retval; 4426 struct timespec t; 4427 4428 if (pid < 0) 4429 return -EINVAL; 4430 4431 retval = -ESRCH; 4432 rcu_read_lock(); 4433 p = find_process_by_pid(pid); 4434 if (!p) 4435 goto out_unlock; 4436 4437 retval = security_task_getscheduler(p); 4438 if (retval) 4439 goto out_unlock; 4440 4441 rq = task_rq_lock(p, &flags); 4442 time_slice = p->sched_class->get_rr_interval(rq, p); 4443 task_rq_unlock(rq, p, &flags); 4444 4445 rcu_read_unlock(); 4446 jiffies_to_timespec(time_slice, &t); 4447 retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0; 4448 return retval; 4449 4450out_unlock: 4451 rcu_read_unlock(); 4452 return retval; 4453} 4454 4455static const char stat_nam[] = TASK_STATE_TO_CHAR_STR; 4456 4457void sched_show_task(struct task_struct *p) 4458{ 4459 unsigned long free = 0; 4460 unsigned state; 4461 4462 state = p->state ? __ffs(p->state) + 1 : 0; 4463 printk(KERN_INFO "%-15.15s %c", p->comm, 4464 state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?'); 4465#if BITS_PER_LONG == 32 4466 if (state == TASK_RUNNING) 4467 printk(KERN_CONT " running "); 4468 else 4469 printk(KERN_CONT " %08lx ", thread_saved_pc(p)); 4470#else 4471 if (state == TASK_RUNNING) 4472 printk(KERN_CONT " running task "); 4473 else 4474 printk(KERN_CONT " %016lx ", thread_saved_pc(p)); 4475#endif 4476#ifdef CONFIG_DEBUG_STACK_USAGE 4477 free = stack_not_used(p); 4478#endif 4479 printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free, 4480 task_pid_nr(p), task_pid_nr(rcu_dereference(p->real_parent)), 4481 (unsigned long)task_thread_info(p)->flags); 4482 4483 show_stack(p, NULL); 4484} 4485 4486void show_state_filter(unsigned long state_filter) 4487{ 4488 struct task_struct *g, *p; 4489 4490#if BITS_PER_LONG == 32 4491 printk(KERN_INFO 4492 " task PC stack pid father\n"); 4493#else 4494 printk(KERN_INFO 4495 " task PC stack pid father\n"); 4496#endif 4497 rcu_read_lock(); 4498 do_each_thread(g, p) { 4499 /* 4500 * reset the NMI-timeout, listing all files on a slow 4501 * console might take a lot of time: 4502 */ 4503 touch_nmi_watchdog(); 4504 if (!state_filter || (p->state & state_filter)) 4505 sched_show_task(p); 4506 } while_each_thread(g, p); 4507 4508 touch_all_softlockup_watchdogs(); 4509 4510#ifdef CONFIG_SCHED_DEBUG 4511 sysrq_sched_debug_show(); 4512#endif 4513 rcu_read_unlock(); 4514 /* 4515 * Only show locks if all tasks are dumped: 4516 */ 4517 if (!state_filter) 4518 debug_show_all_locks(); 4519} 4520 4521void __cpuinit init_idle_bootup_task(struct task_struct *idle) 4522{ 4523 idle->sched_class = &idle_sched_class; 4524} 4525 4526/** 4527 * init_idle - set up an idle thread for a given CPU 4528 * @idle: task in question 4529 * @cpu: cpu the idle task belongs to 4530 * 4531 * NOTE: this function does not set the idle thread's NEED_RESCHED 4532 * flag, to make booting more robust. 4533 */ 4534void __cpuinit init_idle(struct task_struct *idle, int cpu) 4535{ 4536 struct rq *rq = cpu_rq(cpu); 4537 unsigned long flags; 4538 4539 raw_spin_lock_irqsave(&rq->lock, flags); 4540 4541 __sched_fork(idle); 4542 idle->state = TASK_RUNNING; 4543 idle->se.exec_start = sched_clock(); 4544 4545 do_set_cpus_allowed(idle, cpumask_of(cpu)); 4546 /* 4547 * We're having a chicken and egg problem, even though we are 4548 * holding rq->lock, the cpu isn't yet set to this cpu so the 4549 * lockdep check in task_group() will fail. 4550 * 4551 * Similar case to sched_fork(). / Alternatively we could 4552 * use task_rq_lock() here and obtain the other rq->lock. 4553 * 4554 * Silence PROVE_RCU 4555 */ 4556 rcu_read_lock(); 4557 __set_task_cpu(idle, cpu); 4558 rcu_read_unlock(); 4559 4560 rq->curr = rq->idle = idle; 4561#if defined(CONFIG_SMP) 4562 idle->on_cpu = 1; 4563#endif 4564 raw_spin_unlock_irqrestore(&rq->lock, flags); 4565 4566 /* Set the preempt count _outside_ the spinlocks! */ 4567 task_thread_info(idle)->preempt_count = 0; 4568 4569 /* 4570 * The idle tasks have their own, simple scheduling class: 4571 */ 4572 idle->sched_class = &idle_sched_class; 4573 ftrace_graph_init_idle_task(idle, cpu); 4574#if defined(CONFIG_SMP) 4575 sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu); 4576#endif 4577} 4578 4579#ifdef CONFIG_SMP 4580void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask) 4581{ 4582 if (p->sched_class && p->sched_class->set_cpus_allowed) 4583 p->sched_class->set_cpus_allowed(p, new_mask); 4584 4585 cpumask_copy(&p->cpus_allowed, new_mask); 4586 p->nr_cpus_allowed = cpumask_weight(new_mask); 4587} 4588 4589/* 4590 * This is how migration works: 4591 * 4592 * 1) we invoke migration_cpu_stop() on the target CPU using 4593 * stop_one_cpu(). 4594 * 2) stopper starts to run (implicitly forcing the migrated thread 4595 * off the CPU) 4596 * 3) it checks whether the migrated task is still in the wrong runqueue. 4597 * 4) if it's in the wrong runqueue then the migration thread removes 4598 * it and puts it into the right queue. 4599 * 5) stopper completes and stop_one_cpu() returns and the migration 4600 * is done. 4601 */ 4602 4603/* 4604 * Change a given task's CPU affinity. Migrate the thread to a 4605 * proper CPU and schedule it away if the CPU it's executing on 4606 * is removed from the allowed bitmask. 4607 * 4608 * NOTE: the caller must have a valid reference to the task, the 4609 * task must not exit() & deallocate itself prematurely. The 4610 * call is not atomic; no spinlocks may be held. 4611 */ 4612int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask) 4613{ 4614 unsigned long flags; 4615 struct rq *rq; 4616 unsigned int dest_cpu; 4617 int ret = 0; 4618 4619 rq = task_rq_lock(p, &flags); 4620 4621 if (cpumask_equal(&p->cpus_allowed, new_mask)) 4622 goto out; 4623 4624 if (!cpumask_intersects(new_mask, cpu_active_mask)) { 4625 ret = -EINVAL; 4626 goto out; 4627 } 4628 4629 if (unlikely((p->flags & PF_THREAD_BOUND) && p != current)) { 4630 ret = -EINVAL; 4631 goto out; 4632 } 4633 4634 do_set_cpus_allowed(p, new_mask); 4635 4636 /* Can the task run on the task's current CPU? If so, we're done */ 4637 if (cpumask_test_cpu(task_cpu(p), new_mask)) 4638 goto out; 4639 4640 dest_cpu = cpumask_any_and(cpu_active_mask, new_mask); 4641 if (p->on_rq) { 4642 struct migration_arg arg = { p, dest_cpu }; 4643 /* Need help from migration thread: drop lock and wait. */ 4644 task_rq_unlock(rq, p, &flags); 4645 stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg); 4646 tlb_migrate_finish(p->mm); 4647 return 0; 4648 } 4649out: 4650 task_rq_unlock(rq, p, &flags); 4651 4652 return ret; 4653} 4654EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr); 4655 4656/* 4657 * Move (not current) task off this cpu, onto dest cpu. We're doing 4658 * this because either it can't run here any more (set_cpus_allowed() 4659 * away from this CPU, or CPU going down), or because we're 4660 * attempting to rebalance this task on exec (sched_exec). 4661 * 4662 * So we race with normal scheduler movements, but that's OK, as long 4663 * as the task is no longer on this CPU. 4664 * 4665 * Returns non-zero if task was successfully migrated. 4666 */ 4667static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu) 4668{ 4669 struct rq *rq_dest, *rq_src; 4670 int ret = 0; 4671 4672 if (unlikely(!cpu_active(dest_cpu))) 4673 return ret; 4674 4675 rq_src = cpu_rq(src_cpu); 4676 rq_dest = cpu_rq(dest_cpu); 4677 4678 raw_spin_lock(&p->pi_lock); 4679 double_rq_lock(rq_src, rq_dest); 4680 /* Already moved. */ 4681 if (task_cpu(p) != src_cpu) 4682 goto done; 4683 /* Affinity changed (again). */ 4684 if (!cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p))) 4685 goto fail; 4686 4687 /* 4688 * If we're not on a rq, the next wake-up will ensure we're 4689 * placed properly. 4690 */ 4691 if (p->on_rq) { 4692 dequeue_task(rq_src, p, 0); 4693 set_task_cpu(p, dest_cpu); 4694 enqueue_task(rq_dest, p, 0); 4695 check_preempt_curr(rq_dest, p, 0); 4696 } 4697done: 4698 ret = 1; 4699fail: 4700 double_rq_unlock(rq_src, rq_dest); 4701 raw_spin_unlock(&p->pi_lock); 4702 return ret; 4703} 4704 4705/* 4706 * migration_cpu_stop - this will be executed by a highprio stopper thread 4707 * and performs thread migration by bumping thread off CPU then 4708 * 'pushing' onto another runqueue. 4709 */ 4710static int migration_cpu_stop(void *data) 4711{ 4712 struct migration_arg *arg = data; 4713 4714 /* 4715 * The original target cpu might have gone down and we might 4716 * be on another cpu but it doesn't matter. 4717 */ 4718 local_irq_disable(); 4719 __migrate_task(arg->task, raw_smp_processor_id(), arg->dest_cpu); 4720 local_irq_enable(); 4721 return 0; 4722} 4723 4724#ifdef CONFIG_HOTPLUG_CPU 4725 4726/* 4727 * Ensures that the idle task is using init_mm right before its cpu goes 4728 * offline. 4729 */ 4730void idle_task_exit(void) 4731{ 4732 struct mm_struct *mm = current->active_mm; 4733 4734 BUG_ON(cpu_online(smp_processor_id())); 4735 4736 if (mm != &init_mm) 4737 switch_mm(mm, &init_mm, current); 4738 mmdrop(mm); 4739} 4740 4741/* 4742 * Since this CPU is going 'away' for a while, fold any nr_active delta 4743 * we might have. Assumes we're called after migrate_tasks() so that the 4744 * nr_active count is stable. 4745 * 4746 * Also see the comment "Global load-average calculations". 4747 */ 4748static void calc_load_migrate(struct rq *rq) 4749{ 4750 long delta = calc_load_fold_active(rq); 4751 if (delta) 4752 atomic_long_add(delta, &calc_load_tasks); 4753} 4754 4755/* 4756 * Migrate all tasks from the rq, sleeping tasks will be migrated by 4757 * try_to_wake_up()->select_task_rq(). 4758 * 4759 * Called with rq->lock held even though we'er in stop_machine() and 4760 * there's no concurrency possible, we hold the required locks anyway 4761 * because of lock validation efforts. 4762 */ 4763static void migrate_tasks(unsigned int dead_cpu) 4764{ 4765 struct rq *rq = cpu_rq(dead_cpu); 4766 struct task_struct *next, *stop = rq->stop; 4767 int dest_cpu; 4768 4769 /* 4770 * Fudge the rq selection such that the below task selection loop 4771 * doesn't get stuck on the currently eligible stop task. 4772 * 4773 * We're currently inside stop_machine() and the rq is either stuck 4774 * in the stop_machine_cpu_stop() loop, or we're executing this code, 4775 * either way we should never end up calling schedule() until we're 4776 * done here. 4777 */ 4778 rq->stop = NULL; 4779 4780 for ( ; ; ) { 4781 /* 4782 * There's this thread running, bail when that's the only 4783 * remaining thread. 4784 */ 4785 if (rq->nr_running == 1) 4786 break; 4787 4788 next = pick_next_task(rq); 4789 BUG_ON(!next); 4790 next->sched_class->put_prev_task(rq, next); 4791 4792 /* Find suitable destination for @next, with force if needed. */ 4793 dest_cpu = select_fallback_rq(dead_cpu, next); 4794 raw_spin_unlock(&rq->lock); 4795 4796 __migrate_task(next, dead_cpu, dest_cpu); 4797 4798 raw_spin_lock(&rq->lock); 4799 } 4800 4801 rq->stop = stop; 4802} 4803 4804#endif /* CONFIG_HOTPLUG_CPU */ 4805 4806#if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL) 4807 4808static struct ctl_table sd_ctl_dir[] = { 4809 { 4810 .procname = "sched_domain", 4811 .mode = 0555, 4812 }, 4813 {} 4814}; 4815 4816static struct ctl_table sd_ctl_root[] = { 4817 { 4818 .procname = "kernel", 4819 .mode = 0555, 4820 .child = sd_ctl_dir, 4821 }, 4822 {} 4823}; 4824 4825static struct ctl_table *sd_alloc_ctl_entry(int n) 4826{ 4827 struct ctl_table *entry = 4828 kcalloc(n, sizeof(struct ctl_table), GFP_KERNEL); 4829 4830 return entry; 4831} 4832 4833static void sd_free_ctl_entry(struct ctl_table **tablep) 4834{ 4835 struct ctl_table *entry; 4836 4837 /* 4838 * In the intermediate directories, both the child directory and 4839 * procname are dynamically allocated and could fail but the mode 4840 * will always be set. In the lowest directory the names are 4841 * static strings and all have proc handlers. 4842 */ 4843 for (entry = *tablep; entry->mode; entry++) { 4844 if (entry->child) 4845 sd_free_ctl_entry(&entry->child); 4846 if (entry->proc_handler == NULL) 4847 kfree(entry->procname); 4848 } 4849 4850 kfree(*tablep); 4851 *tablep = NULL; 4852} 4853 4854static int min_load_idx = 0; 4855static int max_load_idx = CPU_LOAD_IDX_MAX; 4856 4857static void 4858set_table_entry(struct ctl_table *entry, 4859 const char *procname, void *data, int maxlen, 4860 umode_t mode, proc_handler *proc_handler, 4861 bool load_idx) 4862{ 4863 entry->procname = procname; 4864 entry->data = data; 4865 entry->maxlen = maxlen; 4866 entry->mode = mode; 4867 entry->proc_handler = proc_handler; 4868 4869 if (load_idx) { 4870 entry->extra1 = &min_load_idx; 4871 entry->extra2 = &max_load_idx; 4872 } 4873} 4874 4875static struct ctl_table * 4876sd_alloc_ctl_domain_table(struct sched_domain *sd) 4877{ 4878 struct ctl_table *table = sd_alloc_ctl_entry(13); 4879 4880 if (table == NULL) 4881 return NULL; 4882 4883 set_table_entry(&table[0], "min_interval", &sd->min_interval, 4884 sizeof(long), 0644, proc_doulongvec_minmax, false); 4885 set_table_entry(&table[1], "max_interval", &sd->max_interval, 4886 sizeof(long), 0644, proc_doulongvec_minmax, false); 4887 set_table_entry(&table[2], "busy_idx", &sd->busy_idx, 4888 sizeof(int), 0644, proc_dointvec_minmax, true); 4889 set_table_entry(&table[3], "idle_idx", &sd->idle_idx, 4890 sizeof(int), 0644, proc_dointvec_minmax, true); 4891 set_table_entry(&table[4], "newidle_idx", &sd->newidle_idx, 4892 sizeof(int), 0644, proc_dointvec_minmax, true); 4893 set_table_entry(&table[5], "wake_idx", &sd->wake_idx, 4894 sizeof(int), 0644, proc_dointvec_minmax, true); 4895 set_table_entry(&table[6], "forkexec_idx", &sd->forkexec_idx, 4896 sizeof(int), 0644, proc_dointvec_minmax, true); 4897 set_table_entry(&table[7], "busy_factor", &sd->busy_factor, 4898 sizeof(int), 0644, proc_dointvec_minmax, false); 4899 set_table_entry(&table[8], "imbalance_pct", &sd->imbalance_pct, 4900 sizeof(int), 0644, proc_dointvec_minmax, false); 4901 set_table_entry(&table[9], "cache_nice_tries", 4902 &sd->cache_nice_tries, 4903 sizeof(int), 0644, proc_dointvec_minmax, false); 4904 set_table_entry(&table[10], "flags", &sd->flags, 4905 sizeof(int), 0644, proc_dointvec_minmax, false); 4906 set_table_entry(&table[11], "name", sd->name, 4907 CORENAME_MAX_SIZE, 0444, proc_dostring, false); 4908 /* &table[12] is terminator */ 4909 4910 return table; 4911} 4912 4913static ctl_table *sd_alloc_ctl_cpu_table(int cpu) 4914{ 4915 struct ctl_table *entry, *table; 4916 struct sched_domain *sd; 4917 int domain_num = 0, i; 4918 char buf[32]; 4919 4920 for_each_domain(cpu, sd) 4921 domain_num++; 4922 entry = table = sd_alloc_ctl_entry(domain_num + 1); 4923 if (table == NULL) 4924 return NULL; 4925 4926 i = 0; 4927 for_each_domain(cpu, sd) { 4928 snprintf(buf, 32, "domain%d", i); 4929 entry->procname = kstrdup(buf, GFP_KERNEL); 4930 entry->mode = 0555; 4931 entry->child = sd_alloc_ctl_domain_table(sd); 4932 entry++; 4933 i++; 4934 } 4935 return table; 4936} 4937 4938static struct ctl_table_header *sd_sysctl_header; 4939static void register_sched_domain_sysctl(void) 4940{ 4941 int i, cpu_num = num_possible_cpus(); 4942 struct ctl_table *entry = sd_alloc_ctl_entry(cpu_num + 1); 4943 char buf[32]; 4944 4945 WARN_ON(sd_ctl_dir[0].child); 4946 sd_ctl_dir[0].child = entry; 4947 4948 if (entry == NULL) 4949 return; 4950 4951 for_each_possible_cpu(i) { 4952 snprintf(buf, 32, "cpu%d", i); 4953 entry->procname = kstrdup(buf, GFP_KERNEL); 4954 entry->mode = 0555; 4955 entry->child = sd_alloc_ctl_cpu_table(i); 4956 entry++; 4957 } 4958 4959 WARN_ON(sd_sysctl_header); 4960 sd_sysctl_header = register_sysctl_table(sd_ctl_root); 4961} 4962 4963/* may be called multiple times per register */ 4964static void unregister_sched_domain_sysctl(void) 4965{ 4966 if (sd_sysctl_header) 4967 unregister_sysctl_table(sd_sysctl_header); 4968 sd_sysctl_header = NULL; 4969 if (sd_ctl_dir[0].child) 4970 sd_free_ctl_entry(&sd_ctl_dir[0].child); 4971} 4972#else 4973static void register_sched_domain_sysctl(void) 4974{ 4975} 4976static void unregister_sched_domain_sysctl(void) 4977{ 4978} 4979#endif 4980 4981static void set_rq_online(struct rq *rq) 4982{ 4983 if (!rq->online) { 4984 const struct sched_class *class; 4985 4986 cpumask_set_cpu(rq->cpu, rq->rd->online); 4987 rq->online = 1; 4988 4989 for_each_class(class) { 4990 if (class->rq_online) 4991 class->rq_online(rq); 4992 } 4993 } 4994} 4995 4996static void set_rq_offline(struct rq *rq) 4997{ 4998 if (rq->online) { 4999 const struct sched_class *class; 5000 5001 for_each_class(class) { 5002 if (class->rq_offline) 5003 class->rq_offline(rq); 5004 } 5005 5006 cpumask_clear_cpu(rq->cpu, rq->rd->online); 5007 rq->online = 0; 5008 } 5009} 5010 5011/* 5012 * migration_call - callback that gets triggered when a CPU is added. 5013 * Here we can start up the necessary migration thread for the new CPU. 5014 */ 5015static int __cpuinit 5016migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu) 5017{ 5018 int cpu = (long)hcpu; 5019 unsigned long flags; 5020 struct rq *rq = cpu_rq(cpu); 5021 5022 switch (action & ~CPU_TASKS_FROZEN) { 5023 5024 case CPU_UP_PREPARE: 5025 rq->calc_load_update = calc_load_update; 5026 break; 5027 5028 case CPU_ONLINE: 5029 /* Update our root-domain */ 5030 raw_spin_lock_irqsave(&rq->lock, flags); 5031 if (rq->rd) { 5032 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); 5033 5034 set_rq_online(rq); 5035 } 5036 raw_spin_unlock_irqrestore(&rq->lock, flags); 5037 break; 5038 5039#ifdef CONFIG_HOTPLUG_CPU 5040 case CPU_DYING: 5041 sched_ttwu_pending(); 5042 /* Update our root-domain */ 5043 raw_spin_lock_irqsave(&rq->lock, flags); 5044 if (rq->rd) { 5045 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); 5046 set_rq_offline(rq); 5047 } 5048 migrate_tasks(cpu); 5049 BUG_ON(rq->nr_running != 1); /* the migration thread */ 5050 raw_spin_unlock_irqrestore(&rq->lock, flags); 5051 5052 calc_load_migrate(rq); 5053 break; 5054#endif 5055 } 5056 5057 update_max_interval(); 5058 5059 return NOTIFY_OK; 5060} 5061 5062/* 5063 * Register at high priority so that task migration (migrate_all_tasks) 5064 * happens before everything else. This has to be lower priority than 5065 * the notifier in the perf_event subsystem, though. 5066 */ 5067static struct notifier_block __cpuinitdata migration_notifier = { 5068 .notifier_call = migration_call, 5069 .priority = CPU_PRI_MIGRATION, 5070}; 5071 5072static int __cpuinit sched_cpu_active(struct notifier_block *nfb, 5073 unsigned long action, void *hcpu) 5074{ 5075 switch (action & ~CPU_TASKS_FROZEN) { 5076 case CPU_STARTING: 5077 case CPU_DOWN_FAILED: 5078 set_cpu_active((long)hcpu, true); 5079 return NOTIFY_OK; 5080 default: 5081 return NOTIFY_DONE; 5082 } 5083} 5084 5085static int __cpuinit sched_cpu_inactive(struct notifier_block *nfb, 5086 unsigned long action, void *hcpu) 5087{ 5088 switch (action & ~CPU_TASKS_FROZEN) { 5089 case CPU_DOWN_PREPARE: 5090 set_cpu_active((long)hcpu, false); 5091 return NOTIFY_OK; 5092 default: 5093 return NOTIFY_DONE; 5094 } 5095} 5096 5097static int __init migration_init(void) 5098{ 5099 void *cpu = (void *)(long)smp_processor_id(); 5100 int err; 5101 5102 /* Initialize migration for the boot CPU */ 5103 err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu); 5104 BUG_ON(err == NOTIFY_BAD); 5105 migration_call(&migration_notifier, CPU_ONLINE, cpu); 5106 register_cpu_notifier(&migration_notifier); 5107 5108 /* Register cpu active notifiers */ 5109 cpu_notifier(sched_cpu_active, CPU_PRI_SCHED_ACTIVE); 5110 cpu_notifier(sched_cpu_inactive, CPU_PRI_SCHED_INACTIVE); 5111 5112 return 0; 5113} 5114early_initcall(migration_init); 5115#endif 5116 5117#ifdef CONFIG_SMP 5118 5119static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */ 5120 5121#ifdef CONFIG_SCHED_DEBUG 5122 5123static __read_mostly int sched_debug_enabled; 5124 5125static int __init sched_debug_setup(char *str) 5126{ 5127 sched_debug_enabled = 1; 5128 5129 return 0; 5130} 5131early_param("sched_debug", sched_debug_setup); 5132 5133static inline bool sched_debug(void) 5134{ 5135 return sched_debug_enabled; 5136} 5137 5138static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level, 5139 struct cpumask *groupmask) 5140{ 5141 struct sched_group *group = sd->groups; 5142 char str[256]; 5143 5144 cpulist_scnprintf(str, sizeof(str), sched_domain_span(sd)); 5145 cpumask_clear(groupmask); 5146 5147 printk(KERN_DEBUG "%*s domain %d: ", level, "", level); 5148 5149 if (!(sd->flags & SD_LOAD_BALANCE)) { 5150 printk("does not load-balance\n"); 5151 if (sd->parent) 5152 printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain" 5153 " has parent"); 5154 return -1; 5155 } 5156 5157 printk(KERN_CONT "span %s level %s\n", str, sd->name); 5158 5159 if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) { 5160 printk(KERN_ERR "ERROR: domain->span does not contain " 5161 "CPU%d\n", cpu); 5162 } 5163 if (!cpumask_test_cpu(cpu, sched_group_cpus(group))) { 5164 printk(KERN_ERR "ERROR: domain->groups does not contain" 5165 " CPU%d\n", cpu); 5166 } 5167 5168 printk(KERN_DEBUG "%*s groups:", level + 1, ""); 5169 do { 5170 if (!group) { 5171 printk("\n"); 5172 printk(KERN_ERR "ERROR: group is NULL\n"); 5173 break; 5174 } 5175 5176 /* 5177 * Even though we initialize ->power to something semi-sane, 5178 * we leave power_orig unset. This allows us to detect if 5179 * domain iteration is still funny without causing /0 traps. 5180 */ 5181 if (!group->sgp->power_orig) { 5182 printk(KERN_CONT "\n"); 5183 printk(KERN_ERR "ERROR: domain->cpu_power not " 5184 "set\n"); 5185 break; 5186 } 5187 5188 if (!cpumask_weight(sched_group_cpus(group))) { 5189 printk(KERN_CONT "\n"); 5190 printk(KERN_ERR "ERROR: empty group\n"); 5191 break; 5192 } 5193 5194 if (!(sd->flags & SD_OVERLAP) && 5195 cpumask_intersects(groupmask, sched_group_cpus(group))) { 5196 printk(KERN_CONT "\n"); 5197 printk(KERN_ERR "ERROR: repeated CPUs\n"); 5198 break; 5199 } 5200 5201 cpumask_or(groupmask, groupmask, sched_group_cpus(group)); 5202 5203 cpulist_scnprintf(str, sizeof(str), sched_group_cpus(group)); 5204 5205 printk(KERN_CONT " %s", str); 5206 if (group->sgp->power != SCHED_POWER_SCALE) { 5207 printk(KERN_CONT " (cpu_power = %d)", 5208 group->sgp->power); 5209 } 5210 5211 group = group->next; 5212 } while (group != sd->groups); 5213 printk(KERN_CONT "\n"); 5214 5215 if (!cpumask_equal(sched_domain_span(sd), groupmask)) 5216 printk(KERN_ERR "ERROR: groups don't span domain->span\n"); 5217 5218 if (sd->parent && 5219 !cpumask_subset(groupmask, sched_domain_span(sd->parent))) 5220 printk(KERN_ERR "ERROR: parent span is not a superset " 5221 "of domain->span\n"); 5222 return 0; 5223} 5224 5225static void sched_domain_debug(struct sched_domain *sd, int cpu) 5226{ 5227 int level = 0; 5228 5229 if (!sched_debug_enabled) 5230 return; 5231 5232 if (!sd) { 5233 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu); 5234 return; 5235 } 5236 5237 printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu); 5238 5239 for (;;) { 5240 if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask)) 5241 break; 5242 level++; 5243 sd = sd->parent; 5244 if (!sd) 5245 break; 5246 } 5247} 5248#else /* !CONFIG_SCHED_DEBUG */ 5249# define sched_domain_debug(sd, cpu) do { } while (0) 5250static inline bool sched_debug(void) 5251{ 5252 return false; 5253} 5254#endif /* CONFIG_SCHED_DEBUG */ 5255 5256static int sd_degenerate(struct sched_domain *sd) 5257{ 5258 if (cpumask_weight(sched_domain_span(sd)) == 1) 5259 return 1; 5260 5261 /* Following flags need at least 2 groups */ 5262 if (sd->flags & (SD_LOAD_BALANCE | 5263 SD_BALANCE_NEWIDLE | 5264 SD_BALANCE_FORK | 5265 SD_BALANCE_EXEC | 5266 SD_SHARE_CPUPOWER | 5267 SD_SHARE_PKG_RESOURCES)) { 5268 if (sd->groups != sd->groups->next) 5269 return 0; 5270 } 5271 5272 /* Following flags don't use groups */ 5273 if (sd->flags & (SD_WAKE_AFFINE)) 5274 return 0; 5275 5276 return 1; 5277} 5278 5279static int 5280sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent) 5281{ 5282 unsigned long cflags = sd->flags, pflags = parent->flags; 5283 5284 if (sd_degenerate(parent)) 5285 return 1; 5286 5287 if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent))) 5288 return 0; 5289 5290 /* Flags needing groups don't count if only 1 group in parent */ 5291 if (parent->groups == parent->groups->next) { 5292 pflags &= ~(SD_LOAD_BALANCE | 5293 SD_BALANCE_NEWIDLE | 5294 SD_BALANCE_FORK | 5295 SD_BALANCE_EXEC | 5296 SD_SHARE_CPUPOWER | 5297 SD_SHARE_PKG_RESOURCES); 5298 if (nr_node_ids == 1) 5299 pflags &= ~SD_SERIALIZE; 5300 } 5301 if (~cflags & pflags) 5302 return 0; 5303 5304 return 1; 5305} 5306 5307static void free_rootdomain(struct rcu_head *rcu) 5308{ 5309 struct root_domain *rd = container_of(rcu, struct root_domain, rcu); 5310 5311 cpupri_cleanup(&rd->cpupri); 5312 free_cpumask_var(rd->rto_mask); 5313 free_cpumask_var(rd->online); 5314 free_cpumask_var(rd->span); 5315 kfree(rd); 5316} 5317 5318static void rq_attach_root(struct rq *rq, struct root_domain *rd) 5319{ 5320 struct root_domain *old_rd = NULL; 5321 unsigned long flags; 5322 5323 raw_spin_lock_irqsave(&rq->lock, flags); 5324 5325 if (rq->rd) { 5326 old_rd = rq->rd; 5327 5328 if (cpumask_test_cpu(rq->cpu, old_rd->online)) 5329 set_rq_offline(rq); 5330 5331 cpumask_clear_cpu(rq->cpu, old_rd->span); 5332 5333 /* 5334 * If we dont want to free the old_rt yet then 5335 * set old_rd to NULL to skip the freeing later 5336 * in this function: 5337 */ 5338 if (!atomic_dec_and_test(&old_rd->refcount)) 5339 old_rd = NULL; 5340 } 5341 5342 atomic_inc(&rd->refcount); 5343 rq->rd = rd; 5344 5345 cpumask_set_cpu(rq->cpu, rd->span); 5346 if (cpumask_test_cpu(rq->cpu, cpu_active_mask)) 5347 set_rq_online(rq); 5348 5349 raw_spin_unlock_irqrestore(&rq->lock, flags); 5350 5351 if (old_rd) 5352 call_rcu_sched(&old_rd->rcu, free_rootdomain); 5353} 5354 5355static int init_rootdomain(struct root_domain *rd) 5356{ 5357 memset(rd, 0, sizeof(*rd)); 5358 5359 if (!alloc_cpumask_var(&rd->span, GFP_KERNEL)) 5360 goto out; 5361 if (!alloc_cpumask_var(&rd->online, GFP_KERNEL)) 5362 goto free_span; 5363 if (!alloc_cpumask_var(&rd->rto_mask, GFP_KERNEL)) 5364 goto free_online; 5365 5366 if (cpupri_init(&rd->cpupri) != 0) 5367 goto free_rto_mask; 5368 return 0; 5369 5370free_rto_mask: 5371 free_cpumask_var(rd->rto_mask); 5372free_online: 5373 free_cpumask_var(rd->online); 5374free_span: 5375 free_cpumask_var(rd->span); 5376out: 5377 return -ENOMEM; 5378} 5379 5380/* 5381 * By default the system creates a single root-domain with all cpus as 5382 * members (mimicking the global state we have today). 5383 */ 5384struct root_domain def_root_domain; 5385 5386static void init_defrootdomain(void) 5387{ 5388 init_rootdomain(&def_root_domain); 5389 5390 atomic_set(&def_root_domain.refcount, 1); 5391} 5392 5393static struct root_domain *alloc_rootdomain(void) 5394{ 5395 struct root_domain *rd; 5396 5397 rd = kmalloc(sizeof(*rd), GFP_KERNEL); 5398 if (!rd) 5399 return NULL; 5400 5401 if (init_rootdomain(rd) != 0) { 5402 kfree(rd); 5403 return NULL; 5404 } 5405 5406 return rd; 5407} 5408 5409static void free_sched_groups(struct sched_group *sg, int free_sgp) 5410{ 5411 struct sched_group *tmp, *first; 5412 5413 if (!sg) 5414 return; 5415 5416 first = sg; 5417 do { 5418 tmp = sg->next; 5419 5420 if (free_sgp && atomic_dec_and_test(&sg->sgp->ref)) 5421 kfree(sg->sgp); 5422 5423 kfree(sg); 5424 sg = tmp; 5425 } while (sg != first); 5426} 5427 5428static void free_sched_domain(struct rcu_head *rcu) 5429{ 5430 struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu); 5431 5432 /* 5433 * If its an overlapping domain it has private groups, iterate and 5434 * nuke them all. 5435 */ 5436 if (sd->flags & SD_OVERLAP) { 5437 free_sched_groups(sd->groups, 1); 5438 } else if (atomic_dec_and_test(&sd->groups->ref)) { 5439 kfree(sd->groups->sgp); 5440 kfree(sd->groups); 5441 } 5442 kfree(sd); 5443} 5444 5445static void destroy_sched_domain(struct sched_domain *sd, int cpu) 5446{ 5447 call_rcu(&sd->rcu, free_sched_domain); 5448} 5449 5450static void destroy_sched_domains(struct sched_domain *sd, int cpu) 5451{ 5452 for (; sd; sd = sd->parent) 5453 destroy_sched_domain(sd, cpu); 5454} 5455 5456/* 5457 * Keep a special pointer to the highest sched_domain that has 5458 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this 5459 * allows us to avoid some pointer chasing select_idle_sibling(). 5460 * 5461 * Iterate domains and sched_groups downward, assigning CPUs to be 5462 * select_idle_sibling() hw buddy. Cross-wiring hw makes bouncing 5463 * due to random perturbation self canceling, ie sw buddies pull 5464 * their counterpart to their CPU's hw counterpart. 5465 * 5466 * Also keep a unique ID per domain (we use the first cpu number in 5467 * the cpumask of the domain), this allows us to quickly tell if 5468 * two cpus are in the same cache domain, see cpus_share_cache(). 5469 */ 5470DEFINE_PER_CPU(struct sched_domain *, sd_llc); 5471DEFINE_PER_CPU(int, sd_llc_id); 5472 5473static void update_top_cache_domain(int cpu) 5474{ 5475 struct sched_domain *sd; 5476 int id = cpu; 5477 5478 sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES); 5479 if (sd) { 5480 struct sched_domain *tmp = sd; 5481 struct sched_group *sg, *prev; 5482 bool right; 5483 5484 /* 5485 * Traverse to first CPU in group, and count hops 5486 * to cpu from there, switching direction on each 5487 * hop, never ever pointing the last CPU rightward. 5488 */ 5489 do { 5490 id = cpumask_first(sched_domain_span(tmp)); 5491 prev = sg = tmp->groups; 5492 right = 1; 5493 5494 while (cpumask_first(sched_group_cpus(sg)) != id) 5495 sg = sg->next; 5496 5497 while (!cpumask_test_cpu(cpu, sched_group_cpus(sg))) { 5498 prev = sg; 5499 sg = sg->next; 5500 right = !right; 5501 } 5502 5503 /* A CPU went down, never point back to domain start. */ 5504 if (right && cpumask_first(sched_group_cpus(sg->next)) == id) 5505 right = false; 5506 5507 sg = right ? sg->next : prev; 5508 tmp->idle_buddy = cpumask_first(sched_group_cpus(sg)); 5509 } while ((tmp = tmp->child)); 5510 5511 id = cpumask_first(sched_domain_span(sd)); 5512 } 5513 5514 rcu_assign_pointer(per_cpu(sd_llc, cpu), sd); 5515 per_cpu(sd_llc_id, cpu) = id; 5516} 5517 5518/* 5519 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must 5520 * hold the hotplug lock. 5521 */ 5522static void 5523cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu) 5524{ 5525 struct rq *rq = cpu_rq(cpu); 5526 struct sched_domain *tmp; 5527 5528 /* Remove the sched domains which do not contribute to scheduling. */ 5529 for (tmp = sd; tmp; ) { 5530 struct sched_domain *parent = tmp->parent; 5531 if (!parent) 5532 break; 5533 5534 if (sd_parent_degenerate(tmp, parent)) { 5535 tmp->parent = parent->parent; 5536 if (parent->parent) 5537 parent->parent->child = tmp; 5538 destroy_sched_domain(parent, cpu); 5539 } else 5540 tmp = tmp->parent; 5541 } 5542 5543 if (sd && sd_degenerate(sd)) { 5544 tmp = sd; 5545 sd = sd->parent; 5546 destroy_sched_domain(tmp, cpu); 5547 if (sd) 5548 sd->child = NULL; 5549 } 5550 5551 sched_domain_debug(sd, cpu); 5552 5553 rq_attach_root(rq, rd); 5554 tmp = rq->sd; 5555 rcu_assign_pointer(rq->sd, sd); 5556 destroy_sched_domains(tmp, cpu); 5557 5558 update_top_cache_domain(cpu); 5559} 5560 5561/* cpus with isolated domains */ 5562static cpumask_var_t cpu_isolated_map; 5563 5564/* Setup the mask of cpus configured for isolated domains */ 5565static int __init isolated_cpu_setup(char *str) 5566{ 5567 alloc_bootmem_cpumask_var(&cpu_isolated_map); 5568 cpulist_parse(str, cpu_isolated_map); 5569 return 1; 5570} 5571 5572__setup("isolcpus=", isolated_cpu_setup); 5573 5574static const struct cpumask *cpu_cpu_mask(int cpu) 5575{ 5576 return cpumask_of_node(cpu_to_node(cpu)); 5577} 5578 5579struct sd_data { 5580 struct sched_domain **__percpu sd; 5581 struct sched_group **__percpu sg; 5582 struct sched_group_power **__percpu sgp; 5583}; 5584 5585struct s_data { 5586 struct sched_domain ** __percpu sd; 5587 struct root_domain *rd; 5588}; 5589 5590enum s_alloc { 5591 sa_rootdomain, 5592 sa_sd, 5593 sa_sd_storage, 5594 sa_none, 5595}; 5596 5597struct sched_domain_topology_level; 5598 5599typedef struct sched_domain *(*sched_domain_init_f)(struct sched_domain_topology_level *tl, int cpu); 5600typedef const struct cpumask *(*sched_domain_mask_f)(int cpu); 5601 5602#define SDTL_OVERLAP 0x01 5603 5604struct sched_domain_topology_level { 5605 sched_domain_init_f init; 5606 sched_domain_mask_f mask; 5607 int flags; 5608 int numa_level; 5609 struct sd_data data; 5610}; 5611 5612/* 5613 * Build an iteration mask that can exclude certain CPUs from the upwards 5614 * domain traversal. 5615 * 5616 * Asymmetric node setups can result in situations where the domain tree is of 5617 * unequal depth, make sure to skip domains that already cover the entire 5618 * range. 5619 * 5620 * In that case build_sched_domains() will have terminated the iteration early 5621 * and our sibling sd spans will be empty. Domains should always include the 5622 * cpu they're built on, so check that. 5623 * 5624 */ 5625static void build_group_mask(struct sched_domain *sd, struct sched_group *sg) 5626{ 5627 const struct cpumask *span = sched_domain_span(sd); 5628 struct sd_data *sdd = sd->private; 5629 struct sched_domain *sibling; 5630 int i; 5631 5632 for_each_cpu(i, span) { 5633 sibling = *per_cpu_ptr(sdd->sd, i); 5634 if (!cpumask_test_cpu(i, sched_domain_span(sibling))) 5635 continue; 5636 5637 cpumask_set_cpu(i, sched_group_mask(sg)); 5638 } 5639} 5640 5641/* 5642 * Return the canonical balance cpu for this group, this is the first cpu 5643 * of this group that's also in the iteration mask. 5644 */ 5645int group_balance_cpu(struct sched_group *sg) 5646{ 5647 return cpumask_first_and(sched_group_cpus(sg), sched_group_mask(sg)); 5648} 5649 5650static int 5651build_overlap_sched_groups(struct sched_domain *sd, int cpu) 5652{ 5653 struct sched_group *first = NULL, *last = NULL, *groups = NULL, *sg; 5654 const struct cpumask *span = sched_domain_span(sd); 5655 struct cpumask *covered = sched_domains_tmpmask; 5656 struct sd_data *sdd = sd->private; 5657 struct sched_domain *child; 5658 int i; 5659 5660 cpumask_clear(covered); 5661 5662 for_each_cpu(i, span) { 5663 struct cpumask *sg_span; 5664 5665 if (cpumask_test_cpu(i, covered)) 5666 continue; 5667 5668 child = *per_cpu_ptr(sdd->sd, i); 5669 5670 /* See the comment near build_group_mask(). */ 5671 if (!cpumask_test_cpu(i, sched_domain_span(child))) 5672 continue; 5673 5674 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(), 5675 GFP_KERNEL, cpu_to_node(cpu)); 5676 5677 if (!sg) 5678 goto fail; 5679 5680 sg_span = sched_group_cpus(sg); 5681 if (child->child) { 5682 child = child->child; 5683 cpumask_copy(sg_span, sched_domain_span(child)); 5684 } else 5685 cpumask_set_cpu(i, sg_span); 5686 5687 cpumask_or(covered, covered, sg_span); 5688 5689 sg->sgp = *per_cpu_ptr(sdd->sgp, i); 5690 if (atomic_inc_return(&sg->sgp->ref) == 1) 5691 build_group_mask(sd, sg); 5692 5693 /* 5694 * Initialize sgp->power such that even if we mess up the 5695 * domains and no possible iteration will get us here, we won't 5696 * die on a /0 trap. 5697 */ 5698 sg->sgp->power = SCHED_POWER_SCALE * cpumask_weight(sg_span); 5699 5700 /* 5701 * Make sure the first group of this domain contains the 5702 * canonical balance cpu. Otherwise the sched_domain iteration 5703 * breaks. See update_sg_lb_stats(). 5704 */ 5705 if ((!groups && cpumask_test_cpu(cpu, sg_span)) || 5706 group_balance_cpu(sg) == cpu) 5707 groups = sg; 5708 5709 if (!first) 5710 first = sg; 5711 if (last) 5712 last->next = sg; 5713 last = sg; 5714 last->next = first; 5715 } 5716 sd->groups = groups; 5717 5718 return 0; 5719 5720fail: 5721 free_sched_groups(first, 0); 5722 5723 return -ENOMEM; 5724} 5725 5726static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg) 5727{ 5728 struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu); 5729 struct sched_domain *child = sd->child; 5730 5731 if (child) 5732 cpu = cpumask_first(sched_domain_span(child)); 5733 5734 if (sg) { 5735 *sg = *per_cpu_ptr(sdd->sg, cpu); 5736 (*sg)->sgp = *per_cpu_ptr(sdd->sgp, cpu); 5737 atomic_set(&(*sg)->sgp->ref, 1); /* for claim_allocations */ 5738 } 5739 5740 return cpu; 5741} 5742 5743/* 5744 * build_sched_groups will build a circular linked list of the groups 5745 * covered by the given span, and will set each group's ->cpumask correctly, 5746 * and ->cpu_power to 0. 5747 * 5748 * Assumes the sched_domain tree is fully constructed 5749 */ 5750static int 5751build_sched_groups(struct sched_domain *sd, int cpu) 5752{ 5753 struct sched_group *first = NULL, *last = NULL; 5754 struct sd_data *sdd = sd->private; 5755 const struct cpumask *span = sched_domain_span(sd); 5756 struct cpumask *covered; 5757 int i; 5758 5759 get_group(cpu, sdd, &sd->groups); 5760 atomic_inc(&sd->groups->ref); 5761 5762 if (cpu != cpumask_first(sched_domain_span(sd))) 5763 return 0; 5764 5765 lockdep_assert_held(&sched_domains_mutex); 5766 covered = sched_domains_tmpmask; 5767 5768 cpumask_clear(covered); 5769 5770 for_each_cpu(i, span) { 5771 struct sched_group *sg; 5772 int group = get_group(i, sdd, &sg); 5773 int j; 5774 5775 if (cpumask_test_cpu(i, covered)) 5776 continue; 5777 5778 cpumask_clear(sched_group_cpus(sg)); 5779 sg->sgp->power = 0; 5780 cpumask_setall(sched_group_mask(sg)); 5781 5782 for_each_cpu(j, span) { 5783 if (get_group(j, sdd, NULL) != group) 5784 continue; 5785 5786 cpumask_set_cpu(j, covered); 5787 cpumask_set_cpu(j, sched_group_cpus(sg)); 5788 } 5789 5790 if (!first) 5791 first = sg; 5792 if (last) 5793 last->next = sg; 5794 last = sg; 5795 } 5796 last->next = first; 5797 5798 return 0; 5799} 5800 5801/* 5802 * Initialize sched groups cpu_power. 5803 * 5804 * cpu_power indicates the capacity of sched group, which is used while 5805 * distributing the load between different sched groups in a sched domain. 5806 * Typically cpu_power for all the groups in a sched domain will be same unless 5807 * there are asymmetries in the topology. If there are asymmetries, group 5808 * having more cpu_power will pickup more load compared to the group having 5809 * less cpu_power. 5810 */ 5811static void init_sched_groups_power(int cpu, struct sched_domain *sd) 5812{ 5813 struct sched_group *sg = sd->groups; 5814 5815 WARN_ON(!sd || !sg); 5816 5817 do { 5818 sg->group_weight = cpumask_weight(sched_group_cpus(sg)); 5819 sg = sg->next; 5820 } while (sg != sd->groups); 5821 5822 if (cpu != group_balance_cpu(sg)) 5823 return; 5824 5825 update_group_power(sd, cpu); 5826 atomic_set(&sg->sgp->nr_busy_cpus, sg->group_weight); 5827} 5828 5829int __weak arch_sd_sibling_asym_packing(void) 5830{ 5831 return 0*SD_ASYM_PACKING; 5832} 5833 5834/* 5835 * Initializers for schedule domains 5836 * Non-inlined to reduce accumulated stack pressure in build_sched_domains() 5837 */ 5838 5839#ifdef CONFIG_SCHED_DEBUG 5840# define SD_INIT_NAME(sd, type) sd->name = #type 5841#else 5842# define SD_INIT_NAME(sd, type) do { } while (0) 5843#endif 5844 5845#define SD_INIT_FUNC(type) \ 5846static noinline struct sched_domain * \ 5847sd_init_##type(struct sched_domain_topology_level *tl, int cpu) \ 5848{ \ 5849 struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu); \ 5850 *sd = SD_##type##_INIT; \ 5851 SD_INIT_NAME(sd, type); \ 5852 sd->private = &tl->data; \ 5853 return sd; \ 5854} 5855 5856SD_INIT_FUNC(CPU) 5857#ifdef CONFIG_SCHED_SMT 5858 SD_INIT_FUNC(SIBLING) 5859#endif 5860#ifdef CONFIG_SCHED_MC 5861 SD_INIT_FUNC(MC) 5862#endif 5863#ifdef CONFIG_SCHED_BOOK 5864 SD_INIT_FUNC(BOOK) 5865#endif 5866 5867static int default_relax_domain_level = -1; 5868int sched_domain_level_max; 5869 5870static int __init setup_relax_domain_level(char *str) 5871{ 5872 if (kstrtoint(str, 0, &default_relax_domain_level)) 5873 pr_warn("Unable to set relax_domain_level\n"); 5874 5875 return 1; 5876} 5877__setup("relax_domain_level=", setup_relax_domain_level); 5878 5879static void set_domain_attribute(struct sched_domain *sd, 5880 struct sched_domain_attr *attr) 5881{ 5882 int request; 5883 5884 if (!attr || attr->relax_domain_level < 0) { 5885 if (default_relax_domain_level < 0) 5886 return; 5887 else 5888 request = default_relax_domain_level; 5889 } else 5890 request = attr->relax_domain_level; 5891 if (request < sd->level) { 5892 /* turn off idle balance on this domain */ 5893 sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE); 5894 } else { 5895 /* turn on idle balance on this domain */ 5896 sd->flags |= (SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE); 5897 } 5898} 5899 5900static void __sdt_free(const struct cpumask *cpu_map); 5901static int __sdt_alloc(const struct cpumask *cpu_map); 5902 5903static void __free_domain_allocs(struct s_data *d, enum s_alloc what, 5904 const struct cpumask *cpu_map) 5905{ 5906 switch (what) { 5907 case sa_rootdomain: 5908 if (!atomic_read(&d->rd->refcount)) 5909 free_rootdomain(&d->rd->rcu); /* fall through */ 5910 case sa_sd: 5911 free_percpu(d->sd); /* fall through */ 5912 case sa_sd_storage: 5913 __sdt_free(cpu_map); /* fall through */ 5914 case sa_none: 5915 break; 5916 } 5917} 5918 5919static enum s_alloc __visit_domain_allocation_hell(struct s_data *d, 5920 const struct cpumask *cpu_map) 5921{ 5922 memset(d, 0, sizeof(*d)); 5923 5924 if (__sdt_alloc(cpu_map)) 5925 return sa_sd_storage; 5926 d->sd = alloc_percpu(struct sched_domain *); 5927 if (!d->sd) 5928 return sa_sd_storage; 5929 d->rd = alloc_rootdomain(); 5930 if (!d->rd) 5931 return sa_sd; 5932 return sa_rootdomain; 5933} 5934 5935/* 5936 * NULL the sd_data elements we've used to build the sched_domain and 5937 * sched_group structure so that the subsequent __free_domain_allocs() 5938 * will not free the data we're using. 5939 */ 5940static void claim_allocations(int cpu, struct sched_domain *sd) 5941{ 5942 struct sd_data *sdd = sd->private; 5943 5944 WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd); 5945 *per_cpu_ptr(sdd->sd, cpu) = NULL; 5946 5947 if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref)) 5948 *per_cpu_ptr(sdd->sg, cpu) = NULL; 5949 5950 if (atomic_read(&(*per_cpu_ptr(sdd->sgp, cpu))->ref)) 5951 *per_cpu_ptr(sdd->sgp, cpu) = NULL; 5952} 5953 5954#ifdef CONFIG_SCHED_SMT 5955static const struct cpumask *cpu_smt_mask(int cpu) 5956{ 5957 return topology_thread_cpumask(cpu); 5958} 5959#endif 5960 5961/* 5962 * Topology list, bottom-up. 5963 */ 5964static struct sched_domain_topology_level default_topology[] = { 5965#ifdef CONFIG_SCHED_SMT 5966 { sd_init_SIBLING, cpu_smt_mask, }, 5967#endif 5968#ifdef CONFIG_SCHED_MC 5969 { sd_init_MC, cpu_coregroup_mask, }, 5970#endif 5971#ifdef CONFIG_SCHED_BOOK 5972 { sd_init_BOOK, cpu_book_mask, }, 5973#endif 5974 { sd_init_CPU, cpu_cpu_mask, }, 5975 { NULL, }, 5976}; 5977 5978static struct sched_domain_topology_level *sched_domain_topology = default_topology; 5979 5980#ifdef CONFIG_NUMA 5981 5982static int sched_domains_numa_levels; 5983static int *sched_domains_numa_distance; 5984static struct cpumask ***sched_domains_numa_masks; 5985static int sched_domains_curr_level; 5986 5987static inline int sd_local_flags(int level) 5988{ 5989 if (sched_domains_numa_distance[level] > RECLAIM_DISTANCE) 5990 return 0; 5991 5992 return SD_BALANCE_EXEC | SD_BALANCE_FORK | SD_WAKE_AFFINE; 5993} 5994 5995static struct sched_domain * 5996sd_numa_init(struct sched_domain_topology_level *tl, int cpu) 5997{ 5998 struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu); 5999 int level = tl->numa_level; 6000 int sd_weight = cpumask_weight( 6001 sched_domains_numa_masks[level][cpu_to_node(cpu)]); 6002 6003 *sd = (struct sched_domain){ 6004 .min_interval = sd_weight, 6005 .max_interval = 2*sd_weight, 6006 .busy_factor = 32, 6007 .imbalance_pct = 125, 6008 .cache_nice_tries = 2, 6009 .busy_idx = 3, 6010 .idle_idx = 2, 6011 .newidle_idx = 0, 6012 .wake_idx = 0, 6013 .forkexec_idx = 0, 6014 6015 .flags = 1*SD_LOAD_BALANCE 6016 | 1*SD_BALANCE_NEWIDLE 6017 | 0*SD_BALANCE_EXEC 6018 | 0*SD_BALANCE_FORK 6019 | 0*SD_BALANCE_WAKE 6020 | 0*SD_WAKE_AFFINE 6021 | 0*SD_SHARE_CPUPOWER 6022 | 0*SD_SHARE_PKG_RESOURCES 6023 | 1*SD_SERIALIZE 6024 | 0*SD_PREFER_SIBLING 6025 | sd_local_flags(level) 6026 , 6027 .last_balance = jiffies, 6028 .balance_interval = sd_weight, 6029 }; 6030 SD_INIT_NAME(sd, NUMA); 6031 sd->private = &tl->data; 6032 6033 /* 6034 * Ugly hack to pass state to sd_numa_mask()... 6035 */ 6036 sched_domains_curr_level = tl->numa_level; 6037 6038 return sd; 6039} 6040 6041static const struct cpumask *sd_numa_mask(int cpu) 6042{ 6043 return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)]; 6044} 6045 6046static void sched_numa_warn(const char *str) 6047{ 6048 static int done = false; 6049 int i,j; 6050 6051 if (done) 6052 return; 6053 6054 done = true; 6055 6056 printk(KERN_WARNING "ERROR: %s\n\n", str); 6057 6058 for (i = 0; i < nr_node_ids; i++) { 6059 printk(KERN_WARNING " "); 6060 for (j = 0; j < nr_node_ids; j++) 6061 printk(KERN_CONT "%02d ", node_distance(i,j)); 6062 printk(KERN_CONT "\n"); 6063 } 6064 printk(KERN_WARNING "\n"); 6065} 6066 6067static bool find_numa_distance(int distance) 6068{ 6069 int i; 6070 6071 if (distance == node_distance(0, 0)) 6072 return true; 6073 6074 for (i = 0; i < sched_domains_numa_levels; i++) { 6075 if (sched_domains_numa_distance[i] == distance) 6076 return true; 6077 } 6078 6079 return false; 6080} 6081 6082static void sched_init_numa(void) 6083{ 6084 int next_distance, curr_distance = node_distance(0, 0); 6085 struct sched_domain_topology_level *tl; 6086 int level = 0; 6087 int i, j, k; 6088 6089 sched_domains_numa_distance = kzalloc(sizeof(int) * nr_node_ids, GFP_KERNEL); 6090 if (!sched_domains_numa_distance) 6091 return; 6092 6093 /* 6094 * O(nr_nodes^2) deduplicating selection sort -- in order to find the 6095 * unique distances in the node_distance() table. 6096 * 6097 * Assumes node_distance(0,j) includes all distances in 6098 * node_distance(i,j) in order to avoid cubic time. 6099 */ 6100 next_distance = curr_distance; 6101 for (i = 0; i < nr_node_ids; i++) { 6102 for (j = 0; j < nr_node_ids; j++) { 6103 for (k = 0; k < nr_node_ids; k++) { 6104 int distance = node_distance(i, k); 6105 6106 if (distance > curr_distance && 6107 (distance < next_distance || 6108 next_distance == curr_distance)) 6109 next_distance = distance; 6110 6111 /* 6112 * While not a strong assumption it would be nice to know 6113 * about cases where if node A is connected to B, B is not 6114 * equally connected to A. 6115 */ 6116 if (sched_debug() && node_distance(k, i) != distance) 6117 sched_numa_warn("Node-distance not symmetric"); 6118 6119 if (sched_debug() && i && !find_numa_distance(distance)) 6120 sched_numa_warn("Node-0 not representative"); 6121 } 6122 if (next_distance != curr_distance) { 6123 sched_domains_numa_distance[level++] = next_distance; 6124 sched_domains_numa_levels = level; 6125 curr_distance = next_distance; 6126 } else break; 6127 } 6128 6129 /* 6130 * In case of sched_debug() we verify the above assumption. 6131 */ 6132 if (!sched_debug()) 6133 break; 6134 } 6135 /* 6136 * 'level' contains the number of unique distances, excluding the 6137 * identity distance node_distance(i,i). 6138 * 6139 * The sched_domains_nume_distance[] array includes the actual distance 6140 * numbers. 6141 */ 6142 6143 sched_domains_numa_masks = kzalloc(sizeof(void *) * level, GFP_KERNEL); 6144 if (!sched_domains_numa_masks) 6145 return; 6146 6147 /* 6148 * Now for each level, construct a mask per node which contains all 6149 * cpus of nodes that are that many hops away from us. 6150 */ 6151 for (i = 0; i < level; i++) { 6152 sched_domains_numa_masks[i] = 6153 kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL); 6154 if (!sched_domains_numa_masks[i]) 6155 return; 6156 6157 for (j = 0; j < nr_node_ids; j++) { 6158 struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL); 6159 if (!mask) 6160 return; 6161 6162 sched_domains_numa_masks[i][j] = mask; 6163 6164 for (k = 0; k < nr_node_ids; k++) { 6165 if (node_distance(j, k) > sched_domains_numa_distance[i]) 6166 continue; 6167 6168 cpumask_or(mask, mask, cpumask_of_node(k)); 6169 } 6170 } 6171 } 6172 6173 tl = kzalloc((ARRAY_SIZE(default_topology) + level) * 6174 sizeof(struct sched_domain_topology_level), GFP_KERNEL); 6175 if (!tl) 6176 return; 6177 6178 /* 6179 * Copy the default topology bits.. 6180 */ 6181 for (i = 0; default_topology[i].init; i++) 6182 tl[i] = default_topology[i]; 6183 6184 /* 6185 * .. and append 'j' levels of NUMA goodness. 6186 */ 6187 for (j = 0; j < level; i++, j++) { 6188 tl[i] = (struct sched_domain_topology_level){ 6189 .init = sd_numa_init, 6190 .mask = sd_numa_mask, 6191 .flags = SDTL_OVERLAP, 6192 .numa_level = j, 6193 }; 6194 } 6195 6196 sched_domain_topology = tl; 6197} 6198#else 6199static inline void sched_init_numa(void) 6200{ 6201} 6202#endif /* CONFIG_NUMA */ 6203 6204static int __sdt_alloc(const struct cpumask *cpu_map) 6205{ 6206 struct sched_domain_topology_level *tl; 6207 int j; 6208 6209 for (tl = sched_domain_topology; tl->init; tl++) { 6210 struct sd_data *sdd = &tl->data; 6211 6212 sdd->sd = alloc_percpu(struct sched_domain *); 6213 if (!sdd->sd) 6214 return -ENOMEM; 6215 6216 sdd->sg = alloc_percpu(struct sched_group *); 6217 if (!sdd->sg) 6218 return -ENOMEM; 6219 6220 sdd->sgp = alloc_percpu(struct sched_group_power *); 6221 if (!sdd->sgp) 6222 return -ENOMEM; 6223 6224 for_each_cpu(j, cpu_map) { 6225 struct sched_domain *sd; 6226 struct sched_group *sg; 6227 struct sched_group_power *sgp; 6228 6229 sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(), 6230 GFP_KERNEL, cpu_to_node(j)); 6231 if (!sd) 6232 return -ENOMEM; 6233 6234 *per_cpu_ptr(sdd->sd, j) = sd; 6235 6236 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(), 6237 GFP_KERNEL, cpu_to_node(j)); 6238 if (!sg) 6239 return -ENOMEM; 6240 6241 sg->next = sg; 6242 6243 *per_cpu_ptr(sdd->sg, j) = sg; 6244 6245 sgp = kzalloc_node(sizeof(struct sched_group_power) + cpumask_size(), 6246 GFP_KERNEL, cpu_to_node(j)); 6247 if (!sgp) 6248 return -ENOMEM; 6249 6250 *per_cpu_ptr(sdd->sgp, j) = sgp; 6251 } 6252 } 6253 6254 return 0; 6255} 6256 6257static void __sdt_free(const struct cpumask *cpu_map) 6258{ 6259 struct sched_domain_topology_level *tl; 6260 int j; 6261 6262 for (tl = sched_domain_topology; tl->init; tl++) { 6263 struct sd_data *sdd = &tl->data; 6264 6265 for_each_cpu(j, cpu_map) { 6266 struct sched_domain *sd; 6267 6268 if (sdd->sd) { 6269 sd = *per_cpu_ptr(sdd->sd, j); 6270 if (sd && (sd->flags & SD_OVERLAP)) 6271 free_sched_groups(sd->groups, 0); 6272 kfree(*per_cpu_ptr(sdd->sd, j)); 6273 } 6274 6275 if (sdd->sg) 6276 kfree(*per_cpu_ptr(sdd->sg, j)); 6277 if (sdd->sgp) 6278 kfree(*per_cpu_ptr(sdd->sgp, j)); 6279 } 6280 free_percpu(sdd->sd); 6281 sdd->sd = NULL; 6282 free_percpu(sdd->sg); 6283 sdd->sg = NULL; 6284 free_percpu(sdd->sgp); 6285 sdd->sgp = NULL; 6286 } 6287} 6288 6289struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl, 6290 struct s_data *d, const struct cpumask *cpu_map, 6291 struct sched_domain_attr *attr, struct sched_domain *child, 6292 int cpu) 6293{ 6294 struct sched_domain *sd = tl->init(tl, cpu); 6295 if (!sd) 6296 return child; 6297 6298 cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu)); 6299 if (child) { 6300 sd->level = child->level + 1; 6301 sched_domain_level_max = max(sched_domain_level_max, sd->level); 6302 child->parent = sd; 6303 } 6304 sd->child = child; 6305 set_domain_attribute(sd, attr); 6306 6307 return sd; 6308} 6309 6310/* 6311 * Build sched domains for a given set of cpus and attach the sched domains 6312 * to the individual cpus 6313 */ 6314static int build_sched_domains(const struct cpumask *cpu_map, 6315 struct sched_domain_attr *attr) 6316{ 6317 enum s_alloc alloc_state = sa_none; 6318 struct sched_domain *sd; 6319 struct s_data d; 6320 int i, ret = -ENOMEM; 6321 6322 alloc_state = __visit_domain_allocation_hell(&d, cpu_map); 6323 if (alloc_state != sa_rootdomain) 6324 goto error; 6325 6326 /* Set up domains for cpus specified by the cpu_map. */ 6327 for_each_cpu(i, cpu_map) { 6328 struct sched_domain_topology_level *tl; 6329 6330 sd = NULL; 6331 for (tl = sched_domain_topology; tl->init; tl++) { 6332 sd = build_sched_domain(tl, &d, cpu_map, attr, sd, i); 6333 if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP)) 6334 sd->flags |= SD_OVERLAP; 6335 if (cpumask_equal(cpu_map, sched_domain_span(sd))) 6336 break; 6337 } 6338 6339 while (sd->child) 6340 sd = sd->child; 6341 6342 *per_cpu_ptr(d.sd, i) = sd; 6343 } 6344 6345 /* Build the groups for the domains */ 6346 for_each_cpu(i, cpu_map) { 6347 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) { 6348 sd->span_weight = cpumask_weight(sched_domain_span(sd)); 6349 if (sd->flags & SD_OVERLAP) { 6350 if (build_overlap_sched_groups(sd, i)) 6351 goto error; 6352 } else { 6353 if (build_sched_groups(sd, i)) 6354 goto error; 6355 } 6356 } 6357 } 6358 6359 /* Calculate CPU power for physical packages and nodes */ 6360 for (i = nr_cpumask_bits-1; i >= 0; i--) { 6361 if (!cpumask_test_cpu(i, cpu_map)) 6362 continue; 6363 6364 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) { 6365 claim_allocations(i, sd); 6366 init_sched_groups_power(i, sd); 6367 } 6368 } 6369 6370 /* Attach the domains */ 6371 rcu_read_lock(); 6372 for_each_cpu(i, cpu_map) { 6373 sd = *per_cpu_ptr(d.sd, i); 6374 cpu_attach_domain(sd, d.rd, i); 6375 } 6376 rcu_read_unlock(); 6377 6378 ret = 0; 6379error: 6380 __free_domain_allocs(&d, alloc_state, cpu_map); 6381 return ret; 6382} 6383 6384static cpumask_var_t *doms_cur; /* current sched domains */ 6385static int ndoms_cur; /* number of sched domains in 'doms_cur' */ 6386static struct sched_domain_attr *dattr_cur; 6387 /* attribues of custom domains in 'doms_cur' */ 6388 6389/* 6390 * Special case: If a kmalloc of a doms_cur partition (array of 6391 * cpumask) fails, then fallback to a single sched domain, 6392 * as determined by the single cpumask fallback_doms. 6393 */ 6394static cpumask_var_t fallback_doms; 6395 6396/* 6397 * arch_update_cpu_topology lets virtualized architectures update the 6398 * cpu core maps. It is supposed to return 1 if the topology changed 6399 * or 0 if it stayed the same. 6400 */ 6401int __attribute__((weak)) arch_update_cpu_topology(void) 6402{ 6403 return 0; 6404} 6405 6406cpumask_var_t *alloc_sched_domains(unsigned int ndoms) 6407{ 6408 int i; 6409 cpumask_var_t *doms; 6410 6411 doms = kmalloc(sizeof(*doms) * ndoms, GFP_KERNEL); 6412 if (!doms) 6413 return NULL; 6414 for (i = 0; i < ndoms; i++) { 6415 if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) { 6416 free_sched_domains(doms, i); 6417 return NULL; 6418 } 6419 } 6420 return doms; 6421} 6422 6423void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms) 6424{ 6425 unsigned int i; 6426 for (i = 0; i < ndoms; i++) 6427 free_cpumask_var(doms[i]); 6428 kfree(doms); 6429} 6430 6431/* 6432 * Set up scheduler domains and groups. Callers must hold the hotplug lock. 6433 * For now this just excludes isolated cpus, but could be used to 6434 * exclude other special cases in the future. 6435 */ 6436static int init_sched_domains(const struct cpumask *cpu_map) 6437{ 6438 int err; 6439 6440 arch_update_cpu_topology(); 6441 ndoms_cur = 1; 6442 doms_cur = alloc_sched_domains(ndoms_cur); 6443 if (!doms_cur) 6444 doms_cur = &fallback_doms; 6445 cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map); 6446 err = build_sched_domains(doms_cur[0], NULL); 6447 register_sched_domain_sysctl(); 6448 6449 return err; 6450} 6451 6452/* 6453 * Detach sched domains from a group of cpus specified in cpu_map 6454 * These cpus will now be attached to the NULL domain 6455 */ 6456static void detach_destroy_domains(const struct cpumask *cpu_map) 6457{ 6458 int i; 6459 6460 rcu_read_lock(); 6461 for_each_cpu(i, cpu_map) 6462 cpu_attach_domain(NULL, &def_root_domain, i); 6463 rcu_read_unlock(); 6464} 6465 6466/* handle null as "default" */ 6467static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur, 6468 struct sched_domain_attr *new, int idx_new) 6469{ 6470 struct sched_domain_attr tmp; 6471 6472 /* fast path */ 6473 if (!new && !cur) 6474 return 1; 6475 6476 tmp = SD_ATTR_INIT; 6477 return !memcmp(cur ? (cur + idx_cur) : &tmp, 6478 new ? (new + idx_new) : &tmp, 6479 sizeof(struct sched_domain_attr)); 6480} 6481 6482/* 6483 * Partition sched domains as specified by the 'ndoms_new' 6484 * cpumasks in the array doms_new[] of cpumasks. This compares 6485 * doms_new[] to the current sched domain partitioning, doms_cur[]. 6486 * It destroys each deleted domain and builds each new domain. 6487 * 6488 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'. 6489 * The masks don't intersect (don't overlap.) We should setup one 6490 * sched domain for each mask. CPUs not in any of the cpumasks will 6491 * not be load balanced. If the same cpumask appears both in the 6492 * current 'doms_cur' domains and in the new 'doms_new', we can leave 6493 * it as it is. 6494 * 6495 * The passed in 'doms_new' should be allocated using 6496 * alloc_sched_domains. This routine takes ownership of it and will 6497 * free_sched_domains it when done with it. If the caller failed the 6498 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1, 6499 * and partition_sched_domains() will fallback to the single partition 6500 * 'fallback_doms', it also forces the domains to be rebuilt. 6501 * 6502 * If doms_new == NULL it will be replaced with cpu_online_mask. 6503 * ndoms_new == 0 is a special case for destroying existing domains, 6504 * and it will not create the default domain. 6505 * 6506 * Call with hotplug lock held 6507 */ 6508void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[], 6509 struct sched_domain_attr *dattr_new) 6510{ 6511 int i, j, n; 6512 int new_topology; 6513 6514 mutex_lock(&sched_domains_mutex); 6515 6516 /* always unregister in case we don't destroy any domains */ 6517 unregister_sched_domain_sysctl(); 6518 6519 /* Let architecture update cpu core mappings. */ 6520 new_topology = arch_update_cpu_topology(); 6521 6522 n = doms_new ? ndoms_new : 0; 6523 6524 /* Destroy deleted domains */ 6525 for (i = 0; i < ndoms_cur; i++) { 6526 for (j = 0; j < n && !new_topology; j++) { 6527 if (cpumask_equal(doms_cur[i], doms_new[j]) 6528 && dattrs_equal(dattr_cur, i, dattr_new, j)) 6529 goto match1; 6530 } 6531 /* no match - a current sched domain not in new doms_new[] */ 6532 detach_destroy_domains(doms_cur[i]); 6533match1: 6534 ; 6535 } 6536 6537 if (doms_new == NULL) { 6538 ndoms_cur = 0; 6539 doms_new = &fallback_doms; 6540 cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map); 6541 WARN_ON_ONCE(dattr_new); 6542 } 6543 6544 /* Build new domains */ 6545 for (i = 0; i < ndoms_new; i++) { 6546 for (j = 0; j < ndoms_cur && !new_topology; j++) { 6547 if (cpumask_equal(doms_new[i], doms_cur[j]) 6548 && dattrs_equal(dattr_new, i, dattr_cur, j)) 6549 goto match2; 6550 } 6551 /* no match - add a new doms_new */ 6552 build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL); 6553match2: 6554 ; 6555 } 6556 6557 /* Remember the new sched domains */ 6558 if (doms_cur != &fallback_doms) 6559 free_sched_domains(doms_cur, ndoms_cur); 6560 kfree(dattr_cur); /* kfree(NULL) is safe */ 6561 doms_cur = doms_new; 6562 dattr_cur = dattr_new; 6563 ndoms_cur = ndoms_new; 6564 6565 register_sched_domain_sysctl(); 6566 6567 mutex_unlock(&sched_domains_mutex); 6568} 6569 6570static int num_cpus_frozen; /* used to mark begin/end of suspend/resume */ 6571 6572/* 6573 * Update cpusets according to cpu_active mask. If cpusets are 6574 * disabled, cpuset_update_active_cpus() becomes a simple wrapper 6575 * around partition_sched_domains(). 6576 * 6577 * If we come here as part of a suspend/resume, don't touch cpusets because we 6578 * want to restore it back to its original state upon resume anyway. 6579 */ 6580static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action, 6581 void *hcpu) 6582{ 6583 switch (action) { 6584 case CPU_ONLINE_FROZEN: 6585 case CPU_DOWN_FAILED_FROZEN: 6586 6587 /* 6588 * num_cpus_frozen tracks how many CPUs are involved in suspend 6589 * resume sequence. As long as this is not the last online 6590 * operation in the resume sequence, just build a single sched 6591 * domain, ignoring cpusets. 6592 */ 6593 num_cpus_frozen--; 6594 if (likely(num_cpus_frozen)) { 6595 partition_sched_domains(1, NULL, NULL); 6596 break; 6597 } 6598 6599 /* 6600 * This is the last CPU online operation. So fall through and 6601 * restore the original sched domains by considering the 6602 * cpuset configurations. 6603 */ 6604 6605 case CPU_ONLINE: 6606 case CPU_DOWN_FAILED: 6607 cpuset_update_active_cpus(true); 6608 break; 6609 default: 6610 return NOTIFY_DONE; 6611 } 6612 return NOTIFY_OK; 6613} 6614 6615static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action, 6616 void *hcpu) 6617{ 6618 switch (action) { 6619 case CPU_DOWN_PREPARE: 6620 cpuset_update_active_cpus(false); 6621 break; 6622 case CPU_DOWN_PREPARE_FROZEN: 6623 num_cpus_frozen++; 6624 partition_sched_domains(1, NULL, NULL); 6625 break; 6626 default: 6627 return NOTIFY_DONE; 6628 } 6629 return NOTIFY_OK; 6630} 6631 6632void __init sched_init_smp(void) 6633{ 6634 cpumask_var_t non_isolated_cpus; 6635 6636 alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL); 6637 alloc_cpumask_var(&fallback_doms, GFP_KERNEL); 6638 6639 sched_init_numa(); 6640 6641 get_online_cpus(); 6642 mutex_lock(&sched_domains_mutex); 6643 init_sched_domains(cpu_active_mask); 6644 cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map); 6645 if (cpumask_empty(non_isolated_cpus)) 6646 cpumask_set_cpu(smp_processor_id(), non_isolated_cpus); 6647 mutex_unlock(&sched_domains_mutex); 6648 put_online_cpus(); 6649 6650 hotcpu_notifier(cpuset_cpu_active, CPU_PRI_CPUSET_ACTIVE); 6651 hotcpu_notifier(cpuset_cpu_inactive, CPU_PRI_CPUSET_INACTIVE); 6652 6653 /* RT runtime code needs to handle some hotplug events */ 6654 hotcpu_notifier(update_runtime, 0); 6655 6656 init_hrtick(); 6657 6658 /* Move init over to a non-isolated CPU */ 6659 if (set_cpus_allowed_ptr(current, non_isolated_cpus) < 0) 6660 BUG(); 6661 sched_init_granularity(); 6662 free_cpumask_var(non_isolated_cpus); 6663 6664 init_sched_rt_class(); 6665} 6666#else 6667void __init sched_init_smp(void) 6668{ 6669 sched_init_granularity(); 6670} 6671#endif /* CONFIG_SMP */ 6672 6673const_debug unsigned int sysctl_timer_migration = 1; 6674 6675int in_sched_functions(unsigned long addr) 6676{ 6677 return in_lock_functions(addr) || 6678 (addr >= (unsigned long)__sched_text_start 6679 && addr < (unsigned long)__sched_text_end); 6680} 6681 6682#ifdef CONFIG_CGROUP_SCHED 6683struct task_group root_task_group; 6684LIST_HEAD(task_groups); 6685#endif 6686 6687DECLARE_PER_CPU(cpumask_var_t, load_balance_tmpmask); 6688 6689void __init sched_init(void) 6690{ 6691 int i, j; 6692 unsigned long alloc_size = 0, ptr; 6693 6694#ifdef CONFIG_FAIR_GROUP_SCHED 6695 alloc_size += 2 * nr_cpu_ids * sizeof(void **); 6696#endif 6697#ifdef CONFIG_RT_GROUP_SCHED 6698 alloc_size += 2 * nr_cpu_ids * sizeof(void **); 6699#endif 6700#ifdef CONFIG_CPUMASK_OFFSTACK 6701 alloc_size += num_possible_cpus() * cpumask_size(); 6702#endif 6703 if (alloc_size) { 6704 ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT); 6705 6706#ifdef CONFIG_FAIR_GROUP_SCHED 6707 root_task_group.se = (struct sched_entity **)ptr; 6708 ptr += nr_cpu_ids * sizeof(void **); 6709 6710 root_task_group.cfs_rq = (struct cfs_rq **)ptr; 6711 ptr += nr_cpu_ids * sizeof(void **); 6712 6713#endif /* CONFIG_FAIR_GROUP_SCHED */ 6714#ifdef CONFIG_RT_GROUP_SCHED 6715 root_task_group.rt_se = (struct sched_rt_entity **)ptr; 6716 ptr += nr_cpu_ids * sizeof(void **); 6717 6718 root_task_group.rt_rq = (struct rt_rq **)ptr; 6719 ptr += nr_cpu_ids * sizeof(void **); 6720 6721#endif /* CONFIG_RT_GROUP_SCHED */ 6722#ifdef CONFIG_CPUMASK_OFFSTACK 6723 for_each_possible_cpu(i) { 6724 per_cpu(load_balance_tmpmask, i) = (void *)ptr; 6725 ptr += cpumask_size(); 6726 } 6727#endif /* CONFIG_CPUMASK_OFFSTACK */ 6728 } 6729 6730#ifdef CONFIG_SMP 6731 init_defrootdomain(); 6732#endif 6733 6734 init_rt_bandwidth(&def_rt_bandwidth, 6735 global_rt_period(), global_rt_runtime()); 6736 6737#ifdef CONFIG_RT_GROUP_SCHED 6738 init_rt_bandwidth(&root_task_group.rt_bandwidth, 6739 global_rt_period(), global_rt_runtime()); 6740#endif /* CONFIG_RT_GROUP_SCHED */ 6741 6742#ifdef CONFIG_CGROUP_SCHED 6743 list_add(&root_task_group.list, &task_groups); 6744 INIT_LIST_HEAD(&root_task_group.children); 6745 INIT_LIST_HEAD(&root_task_group.siblings); 6746 autogroup_init(&init_task); 6747 6748#endif /* CONFIG_CGROUP_SCHED */ 6749 6750#ifdef CONFIG_CGROUP_CPUACCT 6751 root_cpuacct.cpustat = &kernel_cpustat; 6752 root_cpuacct.cpuusage = alloc_percpu(u64); 6753 /* Too early, not expected to fail */ 6754 BUG_ON(!root_cpuacct.cpuusage); 6755#endif 6756 for_each_possible_cpu(i) { 6757 struct rq *rq; 6758 6759 rq = cpu_rq(i); 6760 raw_spin_lock_init(&rq->lock); 6761 rq->nr_running = 0; 6762 rq->calc_load_active = 0; 6763 rq->calc_load_update = jiffies + LOAD_FREQ; 6764 init_cfs_rq(&rq->cfs); 6765 init_rt_rq(&rq->rt, rq); 6766#ifdef CONFIG_FAIR_GROUP_SCHED 6767 root_task_group.shares = ROOT_TASK_GROUP_LOAD; 6768 INIT_LIST_HEAD(&rq->leaf_cfs_rq_list); 6769 /* 6770 * How much cpu bandwidth does root_task_group get? 6771 * 6772 * In case of task-groups formed thr' the cgroup filesystem, it 6773 * gets 100% of the cpu resources in the system. This overall 6774 * system cpu resource is divided among the tasks of 6775 * root_task_group and its child task-groups in a fair manner, 6776 * based on each entity's (task or task-group's) weight 6777 * (se->load.weight). 6778 * 6779 * In other words, if root_task_group has 10 tasks of weight 6780 * 1024) and two child groups A0 and A1 (of weight 1024 each), 6781 * then A0's share of the cpu resource is: 6782 * 6783 * A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33% 6784 * 6785 * We achieve this by letting root_task_group's tasks sit 6786 * directly in rq->cfs (i.e root_task_group->se[] = NULL). 6787 */ 6788 init_cfs_bandwidth(&root_task_group.cfs_bandwidth); 6789 init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL); 6790#endif /* CONFIG_FAIR_GROUP_SCHED */ 6791 6792 rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime; 6793#ifdef CONFIG_RT_GROUP_SCHED 6794 INIT_LIST_HEAD(&rq->leaf_rt_rq_list); 6795 init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL); 6796#endif 6797 6798 for (j = 0; j < CPU_LOAD_IDX_MAX; j++) 6799 rq->cpu_load[j] = 0; 6800 6801 rq->last_load_update_tick = jiffies; 6802 6803#ifdef CONFIG_SMP 6804 rq->sd = NULL; 6805 rq->rd = NULL; 6806 rq->cpu_power = SCHED_POWER_SCALE; 6807 rq->post_schedule = 0; 6808 rq->active_balance = 0; 6809 rq->next_balance = jiffies; 6810 rq->push_cpu = 0; 6811 rq->cpu = i; 6812 rq->online = 0; 6813 rq->idle_stamp = 0; 6814 rq->avg_idle = 2*sysctl_sched_migration_cost; 6815 6816 INIT_LIST_HEAD(&rq->cfs_tasks); 6817 6818 rq_attach_root(rq, &def_root_domain); 6819#ifdef CONFIG_NO_HZ 6820 rq->nohz_flags = 0; 6821#endif 6822#endif 6823 init_rq_hrtick(rq); 6824 atomic_set(&rq->nr_iowait, 0); 6825 } 6826 6827 set_load_weight(&init_task); 6828 6829#ifdef CONFIG_PREEMPT_NOTIFIERS 6830 INIT_HLIST_HEAD(&init_task.preempt_notifiers); 6831#endif 6832 6833#ifdef CONFIG_RT_MUTEXES 6834 plist_head_init(&init_task.pi_waiters); 6835#endif 6836 6837 /* 6838 * The boot idle thread does lazy MMU switching as well: 6839 */ 6840 atomic_inc(&init_mm.mm_count); 6841 enter_lazy_tlb(&init_mm, current); 6842 6843 /* 6844 * Make us the idle thread. Technically, schedule() should not be 6845 * called from this thread, however somewhere below it might be, 6846 * but because we are the idle thread, we just pick up running again 6847 * when this runqueue becomes "idle". 6848 */ 6849 init_idle(current, smp_processor_id()); 6850 6851 calc_load_update = jiffies + LOAD_FREQ; 6852 6853 /* 6854 * During early bootup we pretend to be a normal task: 6855 */ 6856 current->sched_class = &fair_sched_class; 6857 6858#ifdef CONFIG_SMP 6859 zalloc_cpumask_var(&sched_domains_tmpmask, GFP_NOWAIT); 6860 /* May be allocated at isolcpus cmdline parse time */ 6861 if (cpu_isolated_map == NULL) 6862 zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT); 6863 idle_thread_set_boot_cpu(); 6864#endif 6865 init_sched_fair_class(); 6866 6867 scheduler_running = 1; 6868} 6869 6870#ifdef CONFIG_DEBUG_ATOMIC_SLEEP 6871static inline int preempt_count_equals(int preempt_offset) 6872{ 6873 int nested = (preempt_count() & ~PREEMPT_ACTIVE) + rcu_preempt_depth(); 6874 6875 return (nested == preempt_offset); 6876} 6877 6878void __might_sleep(const char *file, int line, int preempt_offset) 6879{ 6880 static unsigned long prev_jiffy; /* ratelimiting */ 6881 6882 rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */ 6883 if ((preempt_count_equals(preempt_offset) && !irqs_disabled()) || 6884 system_state != SYSTEM_RUNNING || oops_in_progress) 6885 return; 6886 if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy) 6887 return; 6888 prev_jiffy = jiffies; 6889 6890 printk(KERN_ERR 6891 "BUG: sleeping function called from invalid context at %s:%d\n", 6892 file, line); 6893 printk(KERN_ERR 6894 "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n", 6895 in_atomic(), irqs_disabled(), 6896 current->pid, current->comm); 6897 6898 debug_show_held_locks(current); 6899 if (irqs_disabled()) 6900 print_irqtrace_events(current); 6901 dump_stack(); 6902} 6903EXPORT_SYMBOL(__might_sleep); 6904#endif 6905 6906#ifdef CONFIG_MAGIC_SYSRQ 6907static void normalize_task(struct rq *rq, struct task_struct *p) 6908{ 6909 const struct sched_class *prev_class = p->sched_class; 6910 int old_prio = p->prio; 6911 int on_rq; 6912 6913 on_rq = p->on_rq; 6914 if (on_rq) 6915 dequeue_task(rq, p, 0); 6916 __setscheduler(rq, p, SCHED_NORMAL, 0); 6917 if (on_rq) { 6918 enqueue_task(rq, p, 0); 6919 resched_task(rq->curr); 6920 } 6921 6922 check_class_changed(rq, p, prev_class, old_prio); 6923} 6924 6925void normalize_rt_tasks(void) 6926{ 6927 struct task_struct *g, *p; 6928 unsigned long flags; 6929 struct rq *rq; 6930 6931 read_lock_irqsave(&tasklist_lock, flags); 6932 do_each_thread(g, p) { 6933 /* 6934 * Only normalize user tasks: 6935 */ 6936 if (!p->mm) 6937 continue; 6938 6939 p->se.exec_start = 0; 6940#ifdef CONFIG_SCHEDSTATS 6941 p->se.statistics.wait_start = 0; 6942 p->se.statistics.sleep_start = 0; 6943 p->se.statistics.block_start = 0; 6944#endif 6945 6946 if (!rt_task(p)) { 6947 /* 6948 * Renice negative nice level userspace 6949 * tasks back to 0: 6950 */ 6951 if (TASK_NICE(p) < 0 && p->mm) 6952 set_user_nice(p, 0); 6953 continue; 6954 } 6955 6956 raw_spin_lock(&p->pi_lock); 6957 rq = __task_rq_lock(p); 6958 6959 normalize_task(rq, p); 6960 6961 __task_rq_unlock(rq); 6962 raw_spin_unlock(&p->pi_lock); 6963 } while_each_thread(g, p); 6964 6965 read_unlock_irqrestore(&tasklist_lock, flags); 6966} 6967 6968#endif /* CONFIG_MAGIC_SYSRQ */ 6969 6970#if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) 6971/* 6972 * These functions are only useful for the IA64 MCA handling, or kdb. 6973 * 6974 * They can only be called when the whole system has been 6975 * stopped - every CPU needs to be quiescent, and no scheduling 6976 * activity can take place. Using them for anything else would 6977 * be a serious bug, and as a result, they aren't even visible 6978 * under any other configuration. 6979 */ 6980 6981/** 6982 * curr_task - return the current task for a given cpu. 6983 * @cpu: the processor in question. 6984 * 6985 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! 6986 */ 6987struct task_struct *curr_task(int cpu) 6988{ 6989 return cpu_curr(cpu); 6990} 6991 6992#endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */ 6993 6994#ifdef CONFIG_IA64 6995/** 6996 * set_curr_task - set the current task for a given cpu. 6997 * @cpu: the processor in question. 6998 * @p: the task pointer to set. 6999 * 7000 * Description: This function must only be used when non-maskable interrupts 7001 * are serviced on a separate stack. It allows the architecture to switch the 7002 * notion of the current task on a cpu in a non-blocking manner. This function 7003 * must be called with all CPU's synchronized, and interrupts disabled, the 7004 * and caller must save the original value of the current task (see 7005 * curr_task() above) and restore that value before reenabling interrupts and 7006 * re-starting the system. 7007 * 7008 * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! 7009 */ 7010void set_curr_task(int cpu, struct task_struct *p) 7011{ 7012 cpu_curr(cpu) = p; 7013} 7014 7015#endif 7016 7017#ifdef CONFIG_CGROUP_SCHED 7018/* task_group_lock serializes the addition/removal of task groups */ 7019static DEFINE_SPINLOCK(task_group_lock); 7020 7021static void free_sched_group(struct task_group *tg) 7022{ 7023 free_fair_sched_group(tg); 7024 free_rt_sched_group(tg); 7025 autogroup_free(tg); 7026 kfree(tg); 7027} 7028 7029/* allocate runqueue etc for a new task group */ 7030struct task_group *sched_create_group(struct task_group *parent) 7031{ 7032 struct task_group *tg; 7033 unsigned long flags; 7034 7035 tg = kzalloc(sizeof(*tg), GFP_KERNEL); 7036 if (!tg) 7037 return ERR_PTR(-ENOMEM); 7038 7039 if (!alloc_fair_sched_group(tg, parent)) 7040 goto err; 7041 7042 if (!alloc_rt_sched_group(tg, parent)) 7043 goto err; 7044 7045 spin_lock_irqsave(&task_group_lock, flags); 7046 list_add_rcu(&tg->list, &task_groups); 7047 7048 WARN_ON(!parent); /* root should already exist */ 7049 7050 tg->parent = parent; 7051 INIT_LIST_HEAD(&tg->children); 7052 list_add_rcu(&tg->siblings, &parent->children); 7053 spin_unlock_irqrestore(&task_group_lock, flags); 7054 7055 return tg; 7056 7057err: 7058 free_sched_group(tg); 7059 return ERR_PTR(-ENOMEM); 7060} 7061 7062/* rcu callback to free various structures associated with a task group */ 7063static void free_sched_group_rcu(struct rcu_head *rhp) 7064{ 7065 /* now it should be safe to free those cfs_rqs */ 7066 free_sched_group(container_of(rhp, struct task_group, rcu)); 7067} 7068 7069/* Destroy runqueue etc associated with a task group */ 7070void sched_destroy_group(struct task_group *tg) 7071{ 7072 unsigned long flags; 7073 int i; 7074 7075 /* end participation in shares distribution */ 7076 for_each_possible_cpu(i) 7077 unregister_fair_sched_group(tg, i); 7078 7079 spin_lock_irqsave(&task_group_lock, flags); 7080 list_del_rcu(&tg->list); 7081 list_del_rcu(&tg->siblings); 7082 spin_unlock_irqrestore(&task_group_lock, flags); 7083 7084 /* wait for possible concurrent references to cfs_rqs complete */ 7085 call_rcu(&tg->rcu, free_sched_group_rcu); 7086} 7087 7088/* change task's runqueue when it moves between groups. 7089 * The caller of this function should have put the task in its new group 7090 * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to 7091 * reflect its new group. 7092 */ 7093void sched_move_task(struct task_struct *tsk) 7094{ 7095 struct task_group *tg; 7096 int on_rq, running; 7097 unsigned long flags; 7098 struct rq *rq; 7099 7100 rq = task_rq_lock(tsk, &flags); 7101 7102 running = task_current(rq, tsk); 7103 on_rq = tsk->on_rq; 7104 7105 if (on_rq) 7106 dequeue_task(rq, tsk, 0); 7107 if (unlikely(running)) 7108 tsk->sched_class->put_prev_task(rq, tsk); 7109 7110 tg = container_of(task_subsys_state_check(tsk, cpu_cgroup_subsys_id, 7111 lockdep_is_held(&tsk->sighand->siglock)), 7112 struct task_group, css); 7113 tg = autogroup_task_group(tsk, tg); 7114 tsk->sched_task_group = tg; 7115 7116#ifdef CONFIG_FAIR_GROUP_SCHED 7117 if (tsk->sched_class->task_move_group) 7118 tsk->sched_class->task_move_group(tsk, on_rq); 7119 else 7120#endif 7121 set_task_rq(tsk, task_cpu(tsk)); 7122 7123 if (unlikely(running)) 7124 tsk->sched_class->set_curr_task(rq); 7125 if (on_rq) 7126 enqueue_task(rq, tsk, 0); 7127 7128 task_rq_unlock(rq, tsk, &flags); 7129} 7130#endif /* CONFIG_CGROUP_SCHED */ 7131 7132#if defined(CONFIG_RT_GROUP_SCHED) || defined(CONFIG_CFS_BANDWIDTH) 7133static unsigned long to_ratio(u64 period, u64 runtime) 7134{ 7135 if (runtime == RUNTIME_INF) 7136 return 1ULL << 20; 7137 7138 return div64_u64(runtime << 20, period); 7139} 7140#endif 7141 7142#ifdef CONFIG_RT_GROUP_SCHED 7143/* 7144 * Ensure that the real time constraints are schedulable. 7145 */ 7146static DEFINE_MUTEX(rt_constraints_mutex); 7147 7148/* Must be called with tasklist_lock held */ 7149static inline int tg_has_rt_tasks(struct task_group *tg) 7150{ 7151 struct task_struct *g, *p; 7152 7153 do_each_thread(g, p) { 7154 if (rt_task(p) && task_rq(p)->rt.tg == tg) 7155 return 1; 7156 } while_each_thread(g, p); 7157 7158 return 0; 7159} 7160 7161struct rt_schedulable_data { 7162 struct task_group *tg; 7163 u64 rt_period; 7164 u64 rt_runtime; 7165}; 7166 7167static int tg_rt_schedulable(struct task_group *tg, void *data) 7168{ 7169 struct rt_schedulable_data *d = data; 7170 struct task_group *child; 7171 unsigned long total, sum = 0; 7172 u64 period, runtime; 7173 7174 period = ktime_to_ns(tg->rt_bandwidth.rt_period); 7175 runtime = tg->rt_bandwidth.rt_runtime; 7176 7177 if (tg == d->tg) { 7178 period = d->rt_period; 7179 runtime = d->rt_runtime; 7180 } 7181 7182 /* 7183 * Cannot have more runtime than the period. 7184 */ 7185 if (runtime > period && runtime != RUNTIME_INF) 7186 return -EINVAL; 7187 7188 /* 7189 * Ensure we don't starve existing RT tasks. 7190 */ 7191 if (rt_bandwidth_enabled() && !runtime && tg_has_rt_tasks(tg)) 7192 return -EBUSY; 7193 7194 total = to_ratio(period, runtime); 7195 7196 /* 7197 * Nobody can have more than the global setting allows. 7198 */ 7199 if (total > to_ratio(global_rt_period(), global_rt_runtime())) 7200 return -EINVAL; 7201 7202 /* 7203 * The sum of our children's runtime should not exceed our own. 7204 */ 7205 list_for_each_entry_rcu(child, &tg->children, siblings) { 7206 period = ktime_to_ns(child->rt_bandwidth.rt_period); 7207 runtime = child->rt_bandwidth.rt_runtime; 7208 7209 if (child == d->tg) { 7210 period = d->rt_period; 7211 runtime = d->rt_runtime; 7212 } 7213 7214 sum += to_ratio(period, runtime); 7215 } 7216 7217 if (sum > total) 7218 return -EINVAL; 7219 7220 return 0; 7221} 7222 7223static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime) 7224{ 7225 int ret; 7226 7227 struct rt_schedulable_data data = { 7228 .tg = tg, 7229 .rt_period = period, 7230 .rt_runtime = runtime, 7231 }; 7232 7233 rcu_read_lock(); 7234 ret = walk_tg_tree(tg_rt_schedulable, tg_nop, &data); 7235 rcu_read_unlock(); 7236 7237 return ret; 7238} 7239 7240static int tg_set_rt_bandwidth(struct task_group *tg, 7241 u64 rt_period, u64 rt_runtime) 7242{ 7243 int i, err = 0; 7244 7245 mutex_lock(&rt_constraints_mutex); 7246 read_lock(&tasklist_lock); 7247 err = __rt_schedulable(tg, rt_period, rt_runtime); 7248 if (err) 7249 goto unlock; 7250 7251 raw_spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock); 7252 tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period); 7253 tg->rt_bandwidth.rt_runtime = rt_runtime; 7254 7255 for_each_possible_cpu(i) { 7256 struct rt_rq *rt_rq = tg->rt_rq[i]; 7257 7258 raw_spin_lock(&rt_rq->rt_runtime_lock); 7259 rt_rq->rt_runtime = rt_runtime; 7260 raw_spin_unlock(&rt_rq->rt_runtime_lock); 7261 } 7262 raw_spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock); 7263unlock: 7264 read_unlock(&tasklist_lock); 7265 mutex_unlock(&rt_constraints_mutex); 7266 7267 return err; 7268} 7269 7270int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us) 7271{ 7272 u64 rt_runtime, rt_period; 7273 7274 rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period); 7275 rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC; 7276 if (rt_runtime_us < 0) 7277 rt_runtime = RUNTIME_INF; 7278 7279 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime); 7280} 7281 7282long sched_group_rt_runtime(struct task_group *tg) 7283{ 7284 u64 rt_runtime_us; 7285 7286 if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF) 7287 return -1; 7288 7289 rt_runtime_us = tg->rt_bandwidth.rt_runtime; 7290 do_div(rt_runtime_us, NSEC_PER_USEC); 7291 return rt_runtime_us; 7292} 7293 7294int sched_group_set_rt_period(struct task_group *tg, long rt_period_us) 7295{ 7296 u64 rt_runtime, rt_period; 7297 7298 rt_period = (u64)rt_period_us * NSEC_PER_USEC; 7299 rt_runtime = tg->rt_bandwidth.rt_runtime; 7300 7301 if (rt_period == 0) 7302 return -EINVAL; 7303 7304 return tg_set_rt_bandwidth(tg, rt_period, rt_runtime); 7305} 7306 7307long sched_group_rt_period(struct task_group *tg) 7308{ 7309 u64 rt_period_us; 7310 7311 rt_period_us = ktime_to_ns(tg->rt_bandwidth.rt_period); 7312 do_div(rt_period_us, NSEC_PER_USEC); 7313 return rt_period_us; 7314} 7315 7316static int sched_rt_global_constraints(void) 7317{ 7318 u64 runtime, period; 7319 int ret = 0; 7320 7321 if (sysctl_sched_rt_period <= 0) 7322 return -EINVAL; 7323 7324 runtime = global_rt_runtime(); 7325 period = global_rt_period(); 7326 7327 /* 7328 * Sanity check on the sysctl variables. 7329 */ 7330 if (runtime > period && runtime != RUNTIME_INF) 7331 return -EINVAL; 7332 7333 mutex_lock(&rt_constraints_mutex); 7334 read_lock(&tasklist_lock); 7335 ret = __rt_schedulable(NULL, 0, 0); 7336 read_unlock(&tasklist_lock); 7337 mutex_unlock(&rt_constraints_mutex); 7338 7339 return ret; 7340} 7341 7342int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk) 7343{ 7344 /* Don't accept realtime tasks when there is no way for them to run */ 7345 if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0) 7346 return 0; 7347 7348 return 1; 7349} 7350 7351#else /* !CONFIG_RT_GROUP_SCHED */ 7352static int sched_rt_global_constraints(void) 7353{ 7354 unsigned long flags; 7355 int i; 7356 7357 if (sysctl_sched_rt_period <= 0) 7358 return -EINVAL; 7359 7360 /* 7361 * There's always some RT tasks in the root group 7362 * -- migration, kstopmachine etc.. 7363 */ 7364 if (sysctl_sched_rt_runtime == 0) 7365 return -EBUSY; 7366 7367 raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags); 7368 for_each_possible_cpu(i) { 7369 struct rt_rq *rt_rq = &cpu_rq(i)->rt; 7370 7371 raw_spin_lock(&rt_rq->rt_runtime_lock); 7372 rt_rq->rt_runtime = global_rt_runtime(); 7373 raw_spin_unlock(&rt_rq->rt_runtime_lock); 7374 } 7375 raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags); 7376 7377 return 0; 7378} 7379#endif /* CONFIG_RT_GROUP_SCHED */ 7380 7381int sched_rt_handler(struct ctl_table *table, int write, 7382 void __user *buffer, size_t *lenp, 7383 loff_t *ppos) 7384{ 7385 int ret; 7386 int old_period, old_runtime; 7387 static DEFINE_MUTEX(mutex); 7388 7389 mutex_lock(&mutex); 7390 old_period = sysctl_sched_rt_period; 7391 old_runtime = sysctl_sched_rt_runtime; 7392 7393 ret = proc_dointvec(table, write, buffer, lenp, ppos); 7394 7395 if (!ret && write) { 7396 ret = sched_rt_global_constraints(); 7397 if (ret) { 7398 sysctl_sched_rt_period = old_period; 7399 sysctl_sched_rt_runtime = old_runtime; 7400 } else { 7401 def_rt_bandwidth.rt_runtime = global_rt_runtime(); 7402 def_rt_bandwidth.rt_period = 7403 ns_to_ktime(global_rt_period()); 7404 } 7405 } 7406 mutex_unlock(&mutex); 7407 7408 return ret; 7409} 7410 7411#ifdef CONFIG_CGROUP_SCHED 7412 7413/* return corresponding task_group object of a cgroup */ 7414static inline struct task_group *cgroup_tg(struct cgroup *cgrp) 7415{ 7416 return container_of(cgroup_subsys_state(cgrp, cpu_cgroup_subsys_id), 7417 struct task_group, css); 7418} 7419 7420static struct cgroup_subsys_state *cpu_cgroup_create(struct cgroup *cgrp) 7421{ 7422 struct task_group *tg, *parent; 7423 7424 if (!cgrp->parent) { 7425 /* This is early initialization for the top cgroup */ 7426 return &root_task_group.css; 7427 } 7428 7429 parent = cgroup_tg(cgrp->parent); 7430 tg = sched_create_group(parent); 7431 if (IS_ERR(tg)) 7432 return ERR_PTR(-ENOMEM); 7433 7434 return &tg->css; 7435} 7436 7437static void cpu_cgroup_destroy(struct cgroup *cgrp) 7438{ 7439 struct task_group *tg = cgroup_tg(cgrp); 7440 7441 sched_destroy_group(tg); 7442} 7443 7444static int cpu_cgroup_can_attach(struct cgroup *cgrp, 7445 struct cgroup_taskset *tset) 7446{ 7447 struct task_struct *task; 7448 7449 cgroup_taskset_for_each(task, cgrp, tset) { 7450#ifdef CONFIG_RT_GROUP_SCHED 7451 if (!sched_rt_can_attach(cgroup_tg(cgrp), task)) 7452 return -EINVAL; 7453#else 7454 /* We don't support RT-tasks being in separate groups */ 7455 if (task->sched_class != &fair_sched_class) 7456 return -EINVAL; 7457#endif 7458 } 7459 return 0; 7460} 7461 7462static void cpu_cgroup_attach(struct cgroup *cgrp, 7463 struct cgroup_taskset *tset) 7464{ 7465 struct task_struct *task; 7466 7467 cgroup_taskset_for_each(task, cgrp, tset) 7468 sched_move_task(task); 7469} 7470 7471static void 7472cpu_cgroup_exit(struct cgroup *cgrp, struct cgroup *old_cgrp, 7473 struct task_struct *task) 7474{ 7475 /* 7476 * cgroup_exit() is called in the copy_process() failure path. 7477 * Ignore this case since the task hasn't ran yet, this avoids 7478 * trying to poke a half freed task state from generic code. 7479 */ 7480 if (!(task->flags & PF_EXITING)) 7481 return; 7482 7483 sched_move_task(task); 7484} 7485 7486#ifdef CONFIG_FAIR_GROUP_SCHED 7487static int cpu_shares_write_u64(struct cgroup *cgrp, struct cftype *cftype, 7488 u64 shareval) 7489{ 7490 return sched_group_set_shares(cgroup_tg(cgrp), scale_load(shareval)); 7491} 7492 7493static u64 cpu_shares_read_u64(struct cgroup *cgrp, struct cftype *cft) 7494{ 7495 struct task_group *tg = cgroup_tg(cgrp); 7496 7497 return (u64) scale_load_down(tg->shares); 7498} 7499 7500#ifdef CONFIG_CFS_BANDWIDTH 7501static DEFINE_MUTEX(cfs_constraints_mutex); 7502 7503const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */ 7504const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */ 7505 7506static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime); 7507 7508static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota) 7509{ 7510 int i, ret = 0, runtime_enabled, runtime_was_enabled; 7511 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; 7512 7513 if (tg == &root_task_group) 7514 return -EINVAL; 7515 7516 /* 7517 * Ensure we have at some amount of bandwidth every period. This is 7518 * to prevent reaching a state of large arrears when throttled via 7519 * entity_tick() resulting in prolonged exit starvation. 7520 */ 7521 if (quota < min_cfs_quota_period || period < min_cfs_quota_period) 7522 return -EINVAL; 7523 7524 /* 7525 * Likewise, bound things on the otherside by preventing insane quota 7526 * periods. This also allows us to normalize in computing quota 7527 * feasibility. 7528 */ 7529 if (period > max_cfs_quota_period) 7530 return -EINVAL; 7531 7532 mutex_lock(&cfs_constraints_mutex); 7533 ret = __cfs_schedulable(tg, period, quota); 7534 if (ret) 7535 goto out_unlock; 7536 7537 runtime_enabled = quota != RUNTIME_INF; 7538 runtime_was_enabled = cfs_b->quota != RUNTIME_INF; 7539 account_cfs_bandwidth_used(runtime_enabled, runtime_was_enabled); 7540 raw_spin_lock_irq(&cfs_b->lock); 7541 cfs_b->period = ns_to_ktime(period); 7542 cfs_b->quota = quota; 7543 7544 __refill_cfs_bandwidth_runtime(cfs_b); 7545 /* restart the period timer (if active) to handle new period expiry */ 7546 if (runtime_enabled && cfs_b->timer_active) { 7547 /* force a reprogram */ 7548 cfs_b->timer_active = 0; 7549 __start_cfs_bandwidth(cfs_b); 7550 } 7551 raw_spin_unlock_irq(&cfs_b->lock); 7552 7553 for_each_possible_cpu(i) { 7554 struct cfs_rq *cfs_rq = tg->cfs_rq[i]; 7555 struct rq *rq = cfs_rq->rq; 7556 7557 raw_spin_lock_irq(&rq->lock); 7558 cfs_rq->runtime_enabled = runtime_enabled; 7559 cfs_rq->runtime_remaining = 0; 7560 7561 if (cfs_rq->throttled) 7562 unthrottle_cfs_rq(cfs_rq); 7563 raw_spin_unlock_irq(&rq->lock); 7564 } 7565out_unlock: 7566 mutex_unlock(&cfs_constraints_mutex); 7567 7568 return ret; 7569} 7570 7571int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us) 7572{ 7573 u64 quota, period; 7574 7575 period = ktime_to_ns(tg->cfs_bandwidth.period); 7576 if (cfs_quota_us < 0) 7577 quota = RUNTIME_INF; 7578 else 7579 quota = (u64)cfs_quota_us * NSEC_PER_USEC; 7580 7581 return tg_set_cfs_bandwidth(tg, period, quota); 7582} 7583 7584long tg_get_cfs_quota(struct task_group *tg) 7585{ 7586 u64 quota_us; 7587 7588 if (tg->cfs_bandwidth.quota == RUNTIME_INF) 7589 return -1; 7590 7591 quota_us = tg->cfs_bandwidth.quota; 7592 do_div(quota_us, NSEC_PER_USEC); 7593 7594 return quota_us; 7595} 7596 7597int tg_set_cfs_period(struct task_group *tg, long cfs_period_us) 7598{ 7599 u64 quota, period; 7600 7601 period = (u64)cfs_period_us * NSEC_PER_USEC; 7602 quota = tg->cfs_bandwidth.quota; 7603 7604 return tg_set_cfs_bandwidth(tg, period, quota); 7605} 7606 7607long tg_get_cfs_period(struct task_group *tg) 7608{ 7609 u64 cfs_period_us; 7610 7611 cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period); 7612 do_div(cfs_period_us, NSEC_PER_USEC); 7613 7614 return cfs_period_us; 7615} 7616 7617static s64 cpu_cfs_quota_read_s64(struct cgroup *cgrp, struct cftype *cft) 7618{ 7619 return tg_get_cfs_quota(cgroup_tg(cgrp)); 7620} 7621 7622static int cpu_cfs_quota_write_s64(struct cgroup *cgrp, struct cftype *cftype, 7623 s64 cfs_quota_us) 7624{ 7625 return tg_set_cfs_quota(cgroup_tg(cgrp), cfs_quota_us); 7626} 7627 7628static u64 cpu_cfs_period_read_u64(struct cgroup *cgrp, struct cftype *cft) 7629{ 7630 return tg_get_cfs_period(cgroup_tg(cgrp)); 7631} 7632 7633static int cpu_cfs_period_write_u64(struct cgroup *cgrp, struct cftype *cftype, 7634 u64 cfs_period_us) 7635{ 7636 return tg_set_cfs_period(cgroup_tg(cgrp), cfs_period_us); 7637} 7638 7639struct cfs_schedulable_data { 7640 struct task_group *tg; 7641 u64 period, quota; 7642}; 7643 7644/* 7645 * normalize group quota/period to be quota/max_period 7646 * note: units are usecs 7647 */ 7648static u64 normalize_cfs_quota(struct task_group *tg, 7649 struct cfs_schedulable_data *d) 7650{ 7651 u64 quota, period; 7652 7653 if (tg == d->tg) { 7654 period = d->period; 7655 quota = d->quota; 7656 } else { 7657 period = tg_get_cfs_period(tg); 7658 quota = tg_get_cfs_quota(tg); 7659 } 7660 7661 /* note: these should typically be equivalent */ 7662 if (quota == RUNTIME_INF || quota == -1) 7663 return RUNTIME_INF; 7664 7665 return to_ratio(period, quota); 7666} 7667 7668static int tg_cfs_schedulable_down(struct task_group *tg, void *data) 7669{ 7670 struct cfs_schedulable_data *d = data; 7671 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; 7672 s64 quota = 0, parent_quota = -1; 7673 7674 if (!tg->parent) { 7675 quota = RUNTIME_INF; 7676 } else { 7677 struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth; 7678 7679 quota = normalize_cfs_quota(tg, d); 7680 parent_quota = parent_b->hierarchal_quota; 7681 7682 /* 7683 * ensure max(child_quota) <= parent_quota, inherit when no 7684 * limit is set 7685 */ 7686 if (quota == RUNTIME_INF) 7687 quota = parent_quota; 7688 else if (parent_quota != RUNTIME_INF && quota > parent_quota) 7689 return -EINVAL; 7690 } 7691 cfs_b->hierarchal_quota = quota; 7692 7693 return 0; 7694} 7695 7696static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota) 7697{ 7698 int ret; 7699 struct cfs_schedulable_data data = { 7700 .tg = tg, 7701 .period = period, 7702 .quota = quota, 7703 }; 7704 7705 if (quota != RUNTIME_INF) { 7706 do_div(data.period, NSEC_PER_USEC); 7707 do_div(data.quota, NSEC_PER_USEC); 7708 } 7709 7710 rcu_read_lock(); 7711 ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data); 7712 rcu_read_unlock(); 7713 7714 return ret; 7715} 7716 7717static int cpu_stats_show(struct cgroup *cgrp, struct cftype *cft, 7718 struct cgroup_map_cb *cb) 7719{ 7720 struct task_group *tg = cgroup_tg(cgrp); 7721 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth; 7722 7723 cb->fill(cb, "nr_periods", cfs_b->nr_periods); 7724 cb->fill(cb, "nr_throttled", cfs_b->nr_throttled); 7725 cb->fill(cb, "throttled_time", cfs_b->throttled_time); 7726 7727 return 0; 7728} 7729#endif /* CONFIG_CFS_BANDWIDTH */ 7730#endif /* CONFIG_FAIR_GROUP_SCHED */ 7731 7732#ifdef CONFIG_RT_GROUP_SCHED 7733static int cpu_rt_runtime_write(struct cgroup *cgrp, struct cftype *cft, 7734 s64 val) 7735{ 7736 return sched_group_set_rt_runtime(cgroup_tg(cgrp), val); 7737} 7738 7739static s64 cpu_rt_runtime_read(struct cgroup *cgrp, struct cftype *cft) 7740{ 7741 return sched_group_rt_runtime(cgroup_tg(cgrp)); 7742} 7743 7744static int cpu_rt_period_write_uint(struct cgroup *cgrp, struct cftype *cftype, 7745 u64 rt_period_us) 7746{ 7747 return sched_group_set_rt_period(cgroup_tg(cgrp), rt_period_us); 7748} 7749 7750static u64 cpu_rt_period_read_uint(struct cgroup *cgrp, struct cftype *cft) 7751{ 7752 return sched_group_rt_period(cgroup_tg(cgrp)); 7753} 7754#endif /* CONFIG_RT_GROUP_SCHED */ 7755 7756static struct cftype cpu_files[] = { 7757#ifdef CONFIG_FAIR_GROUP_SCHED 7758 { 7759 .name = "shares", 7760 .read_u64 = cpu_shares_read_u64, 7761 .write_u64 = cpu_shares_write_u64, 7762 }, 7763#endif 7764#ifdef CONFIG_CFS_BANDWIDTH 7765 { 7766 .name = "cfs_quota_us", 7767 .read_s64 = cpu_cfs_quota_read_s64, 7768 .write_s64 = cpu_cfs_quota_write_s64, 7769 }, 7770 { 7771 .name = "cfs_period_us", 7772 .read_u64 = cpu_cfs_period_read_u64, 7773 .write_u64 = cpu_cfs_period_write_u64, 7774 }, 7775 { 7776 .name = "stat", 7777 .read_map = cpu_stats_show, 7778 }, 7779#endif 7780#ifdef CONFIG_RT_GROUP_SCHED 7781 { 7782 .name = "rt_runtime_us", 7783 .read_s64 = cpu_rt_runtime_read, 7784 .write_s64 = cpu_rt_runtime_write, 7785 }, 7786 { 7787 .name = "rt_period_us", 7788 .read_u64 = cpu_rt_period_read_uint, 7789 .write_u64 = cpu_rt_period_write_uint, 7790 }, 7791#endif 7792 { } /* terminate */ 7793}; 7794 7795struct cgroup_subsys cpu_cgroup_subsys = { 7796 .name = "cpu", 7797 .create = cpu_cgroup_create, 7798 .destroy = cpu_cgroup_destroy, 7799 .can_attach = cpu_cgroup_can_attach, 7800 .attach = cpu_cgroup_attach, 7801 .exit = cpu_cgroup_exit, 7802 .subsys_id = cpu_cgroup_subsys_id, 7803 .base_cftypes = cpu_files, 7804 .early_init = 1, 7805}; 7806 7807#endif /* CONFIG_CGROUP_SCHED */ 7808 7809#ifdef CONFIG_CGROUP_CPUACCT 7810 7811/* 7812 * CPU accounting code for task groups. 7813 * 7814 * Based on the work by Paul Menage (menage@google.com) and Balbir Singh 7815 * (balbir@in.ibm.com). 7816 */ 7817 7818struct cpuacct root_cpuacct; 7819 7820/* create a new cpu accounting group */ 7821static struct cgroup_subsys_state *cpuacct_create(struct cgroup *cgrp) 7822{ 7823 struct cpuacct *ca; 7824 7825 if (!cgrp->parent) 7826 return &root_cpuacct.css; 7827 7828 ca = kzalloc(sizeof(*ca), GFP_KERNEL); 7829 if (!ca) 7830 goto out; 7831 7832 ca->cpuusage = alloc_percpu(u64); 7833 if (!ca->cpuusage) 7834 goto out_free_ca; 7835 7836 ca->cpustat = alloc_percpu(struct kernel_cpustat); 7837 if (!ca->cpustat) 7838 goto out_free_cpuusage; 7839 7840 return &ca->css; 7841 7842out_free_cpuusage: 7843 free_percpu(ca->cpuusage); 7844out_free_ca: 7845 kfree(ca); 7846out: 7847 return ERR_PTR(-ENOMEM); 7848} 7849 7850/* destroy an existing cpu accounting group */ 7851static void cpuacct_destroy(struct cgroup *cgrp) 7852{ 7853 struct cpuacct *ca = cgroup_ca(cgrp); 7854 7855 free_percpu(ca->cpustat); 7856 free_percpu(ca->cpuusage); 7857 kfree(ca); 7858} 7859 7860static u64 cpuacct_cpuusage_read(struct cpuacct *ca, int cpu) 7861{ 7862 u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu); 7863 u64 data; 7864 7865#ifndef CONFIG_64BIT 7866 /* 7867 * Take rq->lock to make 64-bit read safe on 32-bit platforms. 7868 */ 7869 raw_spin_lock_irq(&cpu_rq(cpu)->lock); 7870 data = *cpuusage; 7871 raw_spin_unlock_irq(&cpu_rq(cpu)->lock); 7872#else 7873 data = *cpuusage; 7874#endif 7875 7876 return data; 7877} 7878 7879static void cpuacct_cpuusage_write(struct cpuacct *ca, int cpu, u64 val) 7880{ 7881 u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu); 7882 7883#ifndef CONFIG_64BIT 7884 /* 7885 * Take rq->lock to make 64-bit write safe on 32-bit platforms. 7886 */ 7887 raw_spin_lock_irq(&cpu_rq(cpu)->lock); 7888 *cpuusage = val; 7889 raw_spin_unlock_irq(&cpu_rq(cpu)->lock); 7890#else 7891 *cpuusage = val; 7892#endif 7893} 7894 7895/* return total cpu usage (in nanoseconds) of a group */ 7896static u64 cpuusage_read(struct cgroup *cgrp, struct cftype *cft) 7897{ 7898 struct cpuacct *ca = cgroup_ca(cgrp); 7899 u64 totalcpuusage = 0; 7900 int i; 7901 7902 for_each_present_cpu(i) 7903 totalcpuusage += cpuacct_cpuusage_read(ca, i); 7904 7905 return totalcpuusage; 7906} 7907 7908static int cpuusage_write(struct cgroup *cgrp, struct cftype *cftype, 7909 u64 reset) 7910{ 7911 struct cpuacct *ca = cgroup_ca(cgrp); 7912 int err = 0; 7913 int i; 7914 7915 if (reset) { 7916 err = -EINVAL; 7917 goto out; 7918 } 7919 7920 for_each_present_cpu(i) 7921 cpuacct_cpuusage_write(ca, i, 0); 7922 7923out: 7924 return err; 7925} 7926 7927static int cpuacct_percpu_seq_read(struct cgroup *cgroup, struct cftype *cft, 7928 struct seq_file *m) 7929{ 7930 struct cpuacct *ca = cgroup_ca(cgroup); 7931 u64 percpu; 7932 int i; 7933 7934 for_each_present_cpu(i) { 7935 percpu = cpuacct_cpuusage_read(ca, i); 7936 seq_printf(m, "%llu ", (unsigned long long) percpu); 7937 } 7938 seq_printf(m, "\n"); 7939 return 0; 7940} 7941 7942static const char *cpuacct_stat_desc[] = { 7943 [CPUACCT_STAT_USER] = "user", 7944 [CPUACCT_STAT_SYSTEM] = "system", 7945}; 7946 7947static int cpuacct_stats_show(struct cgroup *cgrp, struct cftype *cft, 7948 struct cgroup_map_cb *cb) 7949{ 7950 struct cpuacct *ca = cgroup_ca(cgrp); 7951 int cpu; 7952 s64 val = 0; 7953 7954 for_each_online_cpu(cpu) { 7955 struct kernel_cpustat *kcpustat = per_cpu_ptr(ca->cpustat, cpu); 7956 val += kcpustat->cpustat[CPUTIME_USER]; 7957 val += kcpustat->cpustat[CPUTIME_NICE]; 7958 } 7959 val = cputime64_to_clock_t(val); 7960 cb->fill(cb, cpuacct_stat_desc[CPUACCT_STAT_USER], val); 7961 7962 val = 0; 7963 for_each_online_cpu(cpu) { 7964 struct kernel_cpustat *kcpustat = per_cpu_ptr(ca->cpustat, cpu); 7965 val += kcpustat->cpustat[CPUTIME_SYSTEM]; 7966 val += kcpustat->cpustat[CPUTIME_IRQ]; 7967 val += kcpustat->cpustat[CPUTIME_SOFTIRQ]; 7968 } 7969 7970 val = cputime64_to_clock_t(val); 7971 cb->fill(cb, cpuacct_stat_desc[CPUACCT_STAT_SYSTEM], val); 7972 7973 return 0; 7974} 7975 7976static struct cftype files[] = { 7977 { 7978 .name = "usage", 7979 .read_u64 = cpuusage_read, 7980 .write_u64 = cpuusage_write, 7981 }, 7982 { 7983 .name = "usage_percpu", 7984 .read_seq_string = cpuacct_percpu_seq_read, 7985 }, 7986 { 7987 .name = "stat", 7988 .read_map = cpuacct_stats_show, 7989 }, 7990 { } /* terminate */ 7991}; 7992 7993/* 7994 * charge this task's execution time to its accounting group. 7995 * 7996 * called with rq->lock held. 7997 */ 7998void cpuacct_charge(struct task_struct *tsk, u64 cputime) 7999{ 8000 struct cpuacct *ca; 8001 int cpu; 8002 8003 if (unlikely(!cpuacct_subsys.active)) 8004 return; 8005 8006 cpu = task_cpu(tsk); 8007 8008 rcu_read_lock(); 8009 8010 ca = task_ca(tsk); 8011 8012 for (; ca; ca = parent_ca(ca)) { 8013 u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu); 8014 *cpuusage += cputime; 8015 } 8016 8017 rcu_read_unlock(); 8018} 8019 8020struct cgroup_subsys cpuacct_subsys = { 8021 .name = "cpuacct", 8022 .create = cpuacct_create, 8023 .destroy = cpuacct_destroy, 8024 .subsys_id = cpuacct_subsys_id, 8025 .base_cftypes = files, 8026}; 8027#endif /* CONFIG_CGROUP_CPUACCT */ 8028