linux/kernel/sched/fair.c
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   1/*
   2 * Completely Fair Scheduling (CFS) Class (SCHED_NORMAL/SCHED_BATCH)
   3 *
   4 *  Copyright (C) 2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
   5 *
   6 *  Interactivity improvements by Mike Galbraith
   7 *  (C) 2007 Mike Galbraith <efault@gmx.de>
   8 *
   9 *  Various enhancements by Dmitry Adamushko.
  10 *  (C) 2007 Dmitry Adamushko <dmitry.adamushko@gmail.com>
  11 *
  12 *  Group scheduling enhancements by Srivatsa Vaddagiri
  13 *  Copyright IBM Corporation, 2007
  14 *  Author: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
  15 *
  16 *  Scaled math optimizations by Thomas Gleixner
  17 *  Copyright (C) 2007, Thomas Gleixner <tglx@linutronix.de>
  18 *
  19 *  Adaptive scheduling granularity, math enhancements by Peter Zijlstra
  20 *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
  21 */
  22
  23#include <linux/latencytop.h>
  24#include <linux/sched.h>
  25#include <linux/cpumask.h>
  26#include <linux/slab.h>
  27#include <linux/profile.h>
  28#include <linux/interrupt.h>
  29
  30#include <trace/events/sched.h>
  31
  32#include "sched.h"
  33
  34/*
  35 * Targeted preemption latency for CPU-bound tasks:
  36 * (default: 6ms * (1 + ilog(ncpus)), units: nanoseconds)
  37 *
  38 * NOTE: this latency value is not the same as the concept of
  39 * 'timeslice length' - timeslices in CFS are of variable length
  40 * and have no persistent notion like in traditional, time-slice
  41 * based scheduling concepts.
  42 *
  43 * (to see the precise effective timeslice length of your workload,
  44 *  run vmstat and monitor the context-switches (cs) field)
  45 */
  46unsigned int sysctl_sched_latency = 6000000ULL;
  47unsigned int normalized_sysctl_sched_latency = 6000000ULL;
  48
  49/*
  50 * The initial- and re-scaling of tunables is configurable
  51 * (default SCHED_TUNABLESCALING_LOG = *(1+ilog(ncpus))
  52 *
  53 * Options are:
  54 * SCHED_TUNABLESCALING_NONE - unscaled, always *1
  55 * SCHED_TUNABLESCALING_LOG - scaled logarithmical, *1+ilog(ncpus)
  56 * SCHED_TUNABLESCALING_LINEAR - scaled linear, *ncpus
  57 */
  58enum sched_tunable_scaling sysctl_sched_tunable_scaling
  59        = SCHED_TUNABLESCALING_LOG;
  60
  61/*
  62 * Minimal preemption granularity for CPU-bound tasks:
  63 * (default: 0.75 msec * (1 + ilog(ncpus)), units: nanoseconds)
  64 */
  65unsigned int sysctl_sched_min_granularity = 750000ULL;
  66unsigned int normalized_sysctl_sched_min_granularity = 750000ULL;
  67
  68/*
  69 * is kept at sysctl_sched_latency / sysctl_sched_min_granularity
  70 */
  71static unsigned int sched_nr_latency = 8;
  72
  73/*
  74 * After fork, child runs first. If set to 0 (default) then
  75 * parent will (try to) run first.
  76 */
  77unsigned int sysctl_sched_child_runs_first __read_mostly;
  78
  79/*
  80 * SCHED_OTHER wake-up granularity.
  81 * (default: 1 msec * (1 + ilog(ncpus)), units: nanoseconds)
  82 *
  83 * This option delays the preemption effects of decoupled workloads
  84 * and reduces their over-scheduling. Synchronous workloads will still
  85 * have immediate wakeup/sleep latencies.
  86 */
  87unsigned int sysctl_sched_wakeup_granularity = 1000000UL;
  88unsigned int normalized_sysctl_sched_wakeup_granularity = 1000000UL;
  89
  90const_debug unsigned int sysctl_sched_migration_cost = 500000UL;
  91
  92/*
  93 * The exponential sliding  window over which load is averaged for shares
  94 * distribution.
  95 * (default: 10msec)
  96 */
  97unsigned int __read_mostly sysctl_sched_shares_window = 10000000UL;
  98
  99#ifdef CONFIG_CFS_BANDWIDTH
 100/*
 101 * Amount of runtime to allocate from global (tg) to local (per-cfs_rq) pool
 102 * each time a cfs_rq requests quota.
 103 *
 104 * Note: in the case that the slice exceeds the runtime remaining (either due
 105 * to consumption or the quota being specified to be smaller than the slice)
 106 * we will always only issue the remaining available time.
 107 *
 108 * default: 5 msec, units: microseconds
 109  */
 110unsigned int sysctl_sched_cfs_bandwidth_slice = 5000UL;
 111#endif
 112
 113/*
 114 * Increase the granularity value when there are more CPUs,
 115 * because with more CPUs the 'effective latency' as visible
 116 * to users decreases. But the relationship is not linear,
 117 * so pick a second-best guess by going with the log2 of the
 118 * number of CPUs.
 119 *
 120 * This idea comes from the SD scheduler of Con Kolivas:
 121 */
 122static int get_update_sysctl_factor(void)
 123{
 124        unsigned int cpus = min_t(int, num_online_cpus(), 8);
 125        unsigned int factor;
 126
 127        switch (sysctl_sched_tunable_scaling) {
 128        case SCHED_TUNABLESCALING_NONE:
 129                factor = 1;
 130                break;
 131        case SCHED_TUNABLESCALING_LINEAR:
 132                factor = cpus;
 133                break;
 134        case SCHED_TUNABLESCALING_LOG:
 135        default:
 136                factor = 1 + ilog2(cpus);
 137                break;
 138        }
 139
 140        return factor;
 141}
 142
 143static void update_sysctl(void)
 144{
 145        unsigned int factor = get_update_sysctl_factor();
 146
 147#define SET_SYSCTL(name) \
 148        (sysctl_##name = (factor) * normalized_sysctl_##name)
 149        SET_SYSCTL(sched_min_granularity);
 150        SET_SYSCTL(sched_latency);
 151        SET_SYSCTL(sched_wakeup_granularity);
 152#undef SET_SYSCTL
 153}
 154
 155void sched_init_granularity(void)
 156{
 157        update_sysctl();
 158}
 159
 160#if BITS_PER_LONG == 32
 161# define WMULT_CONST    (~0UL)
 162#else
 163# define WMULT_CONST    (1UL << 32)
 164#endif
 165
 166#define WMULT_SHIFT     32
 167
 168/*
 169 * Shift right and round:
 170 */
 171#define SRR(x, y) (((x) + (1UL << ((y) - 1))) >> (y))
 172
 173/*
 174 * delta *= weight / lw
 175 */
 176static unsigned long
 177calc_delta_mine(unsigned long delta_exec, unsigned long weight,
 178                struct load_weight *lw)
 179{
 180        u64 tmp;
 181
 182        /*
 183         * weight can be less than 2^SCHED_LOAD_RESOLUTION for task group sched
 184         * entities since MIN_SHARES = 2. Treat weight as 1 if less than
 185         * 2^SCHED_LOAD_RESOLUTION.
 186         */
 187        if (likely(weight > (1UL << SCHED_LOAD_RESOLUTION)))
 188                tmp = (u64)delta_exec * scale_load_down(weight);
 189        else
 190                tmp = (u64)delta_exec;
 191
 192        if (!lw->inv_weight) {
 193                unsigned long w = scale_load_down(lw->weight);
 194
 195                if (BITS_PER_LONG > 32 && unlikely(w >= WMULT_CONST))
 196                        lw->inv_weight = 1;
 197                else if (unlikely(!w))
 198                        lw->inv_weight = WMULT_CONST;
 199                else
 200                        lw->inv_weight = WMULT_CONST / w;
 201        }
 202
 203        /*
 204         * Check whether we'd overflow the 64-bit multiplication:
 205         */
 206        if (unlikely(tmp > WMULT_CONST))
 207                tmp = SRR(SRR(tmp, WMULT_SHIFT/2) * lw->inv_weight,
 208                        WMULT_SHIFT/2);
 209        else
 210                tmp = SRR(tmp * lw->inv_weight, WMULT_SHIFT);
 211
 212        return (unsigned long)min(tmp, (u64)(unsigned long)LONG_MAX);
 213}
 214
 215
 216const struct sched_class fair_sched_class;
 217
 218/**************************************************************
 219 * CFS operations on generic schedulable entities:
 220 */
 221
 222#ifdef CONFIG_FAIR_GROUP_SCHED
 223
 224/* cpu runqueue to which this cfs_rq is attached */
 225static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
 226{
 227        return cfs_rq->rq;
 228}
 229
 230/* An entity is a task if it doesn't "own" a runqueue */
 231#define entity_is_task(se)      (!se->my_q)
 232
 233static inline struct task_struct *task_of(struct sched_entity *se)
 234{
 235#ifdef CONFIG_SCHED_DEBUG
 236        WARN_ON_ONCE(!entity_is_task(se));
 237#endif
 238        return container_of(se, struct task_struct, se);
 239}
 240
 241/* Walk up scheduling entities hierarchy */
 242#define for_each_sched_entity(se) \
 243                for (; se; se = se->parent)
 244
 245static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
 246{
 247        return p->se.cfs_rq;
 248}
 249
 250/* runqueue on which this entity is (to be) queued */
 251static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
 252{
 253        return se->cfs_rq;
 254}
 255
 256/* runqueue "owned" by this group */
 257static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
 258{
 259        return grp->my_q;
 260}
 261
 262static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
 263{
 264        if (!cfs_rq->on_list) {
 265                /*
 266                 * Ensure we either appear before our parent (if already
 267                 * enqueued) or force our parent to appear after us when it is
 268                 * enqueued.  The fact that we always enqueue bottom-up
 269                 * reduces this to two cases.
 270                 */
 271                if (cfs_rq->tg->parent &&
 272                    cfs_rq->tg->parent->cfs_rq[cpu_of(rq_of(cfs_rq))]->on_list) {
 273                        list_add_rcu(&cfs_rq->leaf_cfs_rq_list,
 274                                &rq_of(cfs_rq)->leaf_cfs_rq_list);
 275                } else {
 276                        list_add_tail_rcu(&cfs_rq->leaf_cfs_rq_list,
 277                                &rq_of(cfs_rq)->leaf_cfs_rq_list);
 278                }
 279
 280                cfs_rq->on_list = 1;
 281        }
 282}
 283
 284static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq)
 285{
 286        if (cfs_rq->on_list) {
 287                list_del_rcu(&cfs_rq->leaf_cfs_rq_list);
 288                cfs_rq->on_list = 0;
 289        }
 290}
 291
 292/* Iterate thr' all leaf cfs_rq's on a runqueue */
 293#define for_each_leaf_cfs_rq(rq, cfs_rq) \
 294        list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list)
 295
 296/* Do the two (enqueued) entities belong to the same group ? */
 297static inline int
 298is_same_group(struct sched_entity *se, struct sched_entity *pse)
 299{
 300        if (se->cfs_rq == pse->cfs_rq)
 301                return 1;
 302
 303        return 0;
 304}
 305
 306static inline struct sched_entity *parent_entity(struct sched_entity *se)
 307{
 308        return se->parent;
 309}
 310
 311/* return depth at which a sched entity is present in the hierarchy */
 312static inline int depth_se(struct sched_entity *se)
 313{
 314        int depth = 0;
 315
 316        for_each_sched_entity(se)
 317                depth++;
 318
 319        return depth;
 320}
 321
 322static void
 323find_matching_se(struct sched_entity **se, struct sched_entity **pse)
 324{
 325        int se_depth, pse_depth;
 326
 327        /*
 328         * preemption test can be made between sibling entities who are in the
 329         * same cfs_rq i.e who have a common parent. Walk up the hierarchy of
 330         * both tasks until we find their ancestors who are siblings of common
 331         * parent.
 332         */
 333
 334        /* First walk up until both entities are at same depth */
 335        se_depth = depth_se(*se);
 336        pse_depth = depth_se(*pse);
 337
 338        while (se_depth > pse_depth) {
 339                se_depth--;
 340                *se = parent_entity(*se);
 341        }
 342
 343        while (pse_depth > se_depth) {
 344                pse_depth--;
 345                *pse = parent_entity(*pse);
 346        }
 347
 348        while (!is_same_group(*se, *pse)) {
 349                *se = parent_entity(*se);
 350                *pse = parent_entity(*pse);
 351        }
 352}
 353
 354#else   /* !CONFIG_FAIR_GROUP_SCHED */
 355
 356static inline struct task_struct *task_of(struct sched_entity *se)
 357{
 358        return container_of(se, struct task_struct, se);
 359}
 360
 361static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
 362{
 363        return container_of(cfs_rq, struct rq, cfs);
 364}
 365
 366#define entity_is_task(se)      1
 367
 368#define for_each_sched_entity(se) \
 369                for (; se; se = NULL)
 370
 371static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
 372{
 373        return &task_rq(p)->cfs;
 374}
 375
 376static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
 377{
 378        struct task_struct *p = task_of(se);
 379        struct rq *rq = task_rq(p);
 380
 381        return &rq->cfs;
 382}
 383
 384/* runqueue "owned" by this group */
 385static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
 386{
 387        return NULL;
 388}
 389
 390static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
 391{
 392}
 393
 394static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq)
 395{
 396}
 397
 398#define for_each_leaf_cfs_rq(rq, cfs_rq) \
 399                for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL)
 400
 401static inline int
 402is_same_group(struct sched_entity *se, struct sched_entity *pse)
 403{
 404        return 1;
 405}
 406
 407static inline struct sched_entity *parent_entity(struct sched_entity *se)
 408{
 409        return NULL;
 410}
 411
 412static inline void
 413find_matching_se(struct sched_entity **se, struct sched_entity **pse)
 414{
 415}
 416
 417#endif  /* CONFIG_FAIR_GROUP_SCHED */
 418
 419static __always_inline
 420void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, unsigned long delta_exec);
 421
 422/**************************************************************
 423 * Scheduling class tree data structure manipulation methods:
 424 */
 425
 426static inline u64 max_vruntime(u64 min_vruntime, u64 vruntime)
 427{
 428        s64 delta = (s64)(vruntime - min_vruntime);
 429        if (delta > 0)
 430                min_vruntime = vruntime;
 431
 432        return min_vruntime;
 433}
 434
 435static inline u64 min_vruntime(u64 min_vruntime, u64 vruntime)
 436{
 437        s64 delta = (s64)(vruntime - min_vruntime);
 438        if (delta < 0)
 439                min_vruntime = vruntime;
 440
 441        return min_vruntime;
 442}
 443
 444static inline int entity_before(struct sched_entity *a,
 445                                struct sched_entity *b)
 446{
 447        return (s64)(a->vruntime - b->vruntime) < 0;
 448}
 449
 450static void update_min_vruntime(struct cfs_rq *cfs_rq)
 451{
 452        u64 vruntime = cfs_rq->min_vruntime;
 453
 454        if (cfs_rq->curr)
 455                vruntime = cfs_rq->curr->vruntime;
 456
 457        if (cfs_rq->rb_leftmost) {
 458                struct sched_entity *se = rb_entry(cfs_rq->rb_leftmost,
 459                                                   struct sched_entity,
 460                                                   run_node);
 461
 462                if (!cfs_rq->curr)
 463                        vruntime = se->vruntime;
 464                else
 465                        vruntime = min_vruntime(vruntime, se->vruntime);
 466        }
 467
 468        cfs_rq->min_vruntime = max_vruntime(cfs_rq->min_vruntime, vruntime);
 469#ifndef CONFIG_64BIT
 470        smp_wmb();
 471        cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime;
 472#endif
 473}
 474
 475/*
 476 * Enqueue an entity into the rb-tree:
 477 */
 478static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
 479{
 480        struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
 481        struct rb_node *parent = NULL;
 482        struct sched_entity *entry;
 483        int leftmost = 1;
 484
 485        /*
 486         * Find the right place in the rbtree:
 487         */
 488        while (*link) {
 489                parent = *link;
 490                entry = rb_entry(parent, struct sched_entity, run_node);
 491                /*
 492                 * We dont care about collisions. Nodes with
 493                 * the same key stay together.
 494                 */
 495                if (entity_before(se, entry)) {
 496                        link = &parent->rb_left;
 497                } else {
 498                        link = &parent->rb_right;
 499                        leftmost = 0;
 500                }
 501        }
 502
 503        /*
 504         * Maintain a cache of leftmost tree entries (it is frequently
 505         * used):
 506         */
 507        if (leftmost)
 508                cfs_rq->rb_leftmost = &se->run_node;
 509
 510        rb_link_node(&se->run_node, parent, link);
 511        rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline);
 512}
 513
 514static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
 515{
 516        if (cfs_rq->rb_leftmost == &se->run_node) {
 517                struct rb_node *next_node;
 518
 519                next_node = rb_next(&se->run_node);
 520                cfs_rq->rb_leftmost = next_node;
 521        }
 522
 523        rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
 524}
 525
 526struct sched_entity *__pick_first_entity(struct cfs_rq *cfs_rq)
 527{
 528        struct rb_node *left = cfs_rq->rb_leftmost;
 529
 530        if (!left)
 531                return NULL;
 532
 533        return rb_entry(left, struct sched_entity, run_node);
 534}
 535
 536static struct sched_entity *__pick_next_entity(struct sched_entity *se)
 537{
 538        struct rb_node *next = rb_next(&se->run_node);
 539
 540        if (!next)
 541                return NULL;
 542
 543        return rb_entry(next, struct sched_entity, run_node);
 544}
 545
 546#ifdef CONFIG_SCHED_DEBUG
 547struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
 548{
 549        struct rb_node *last = rb_last(&cfs_rq->tasks_timeline);
 550
 551        if (!last)
 552                return NULL;
 553
 554        return rb_entry(last, struct sched_entity, run_node);
 555}
 556
 557/**************************************************************
 558 * Scheduling class statistics methods:
 559 */
 560
 561int sched_proc_update_handler(struct ctl_table *table, int write,
 562                void __user *buffer, size_t *lenp,
 563                loff_t *ppos)
 564{
 565        int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
 566        int factor = get_update_sysctl_factor();
 567
 568        if (ret || !write)
 569                return ret;
 570
 571        sched_nr_latency = DIV_ROUND_UP(sysctl_sched_latency,
 572                                        sysctl_sched_min_granularity);
 573
 574#define WRT_SYSCTL(name) \
 575        (normalized_sysctl_##name = sysctl_##name / (factor))
 576        WRT_SYSCTL(sched_min_granularity);
 577        WRT_SYSCTL(sched_latency);
 578        WRT_SYSCTL(sched_wakeup_granularity);
 579#undef WRT_SYSCTL
 580
 581        return 0;
 582}
 583#endif
 584
 585/*
 586 * delta /= w
 587 */
 588static inline unsigned long
 589calc_delta_fair(unsigned long delta, struct sched_entity *se)
 590{
 591        if (unlikely(se->load.weight != NICE_0_LOAD))
 592                delta = calc_delta_mine(delta, NICE_0_LOAD, &se->load);
 593
 594        return delta;
 595}
 596
 597/*
 598 * The idea is to set a period in which each task runs once.
 599 *
 600 * When there are too many tasks (sysctl_sched_nr_latency) we have to stretch
 601 * this period because otherwise the slices get too small.
 602 *
 603 * p = (nr <= nl) ? l : l*nr/nl
 604 */
 605static u64 __sched_period(unsigned long nr_running)
 606{
 607        u64 period = sysctl_sched_latency;
 608        unsigned long nr_latency = sched_nr_latency;
 609
 610        if (unlikely(nr_running > nr_latency)) {
 611                period = sysctl_sched_min_granularity;
 612                period *= nr_running;
 613        }
 614
 615        return period;
 616}
 617
 618/*
 619 * We calculate the wall-time slice from the period by taking a part
 620 * proportional to the weight.
 621 *
 622 * s = p*P[w/rw]
 623 */
 624static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se)
 625{
 626        u64 slice = __sched_period(cfs_rq->nr_running + !se->on_rq);
 627
 628        for_each_sched_entity(se) {
 629                struct load_weight *load;
 630                struct load_weight lw;
 631
 632                cfs_rq = cfs_rq_of(se);
 633                load = &cfs_rq->load;
 634
 635                if (unlikely(!se->on_rq)) {
 636                        lw = cfs_rq->load;
 637
 638                        update_load_add(&lw, se->load.weight);
 639                        load = &lw;
 640                }
 641                slice = calc_delta_mine(slice, se->load.weight, load);
 642        }
 643        return slice;
 644}
 645
 646/*
 647 * We calculate the vruntime slice of a to be inserted task
 648 *
 649 * vs = s/w
 650 */
 651static u64 sched_vslice(struct cfs_rq *cfs_rq, struct sched_entity *se)
 652{
 653        return calc_delta_fair(sched_slice(cfs_rq, se), se);
 654}
 655
 656static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update);
 657static void update_cfs_shares(struct cfs_rq *cfs_rq);
 658
 659/*
 660 * Update the current task's runtime statistics. Skip current tasks that
 661 * are not in our scheduling class.
 662 */
 663static inline void
 664__update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr,
 665              unsigned long delta_exec)
 666{
 667        unsigned long delta_exec_weighted;
 668
 669        schedstat_set(curr->statistics.exec_max,
 670                      max((u64)delta_exec, curr->statistics.exec_max));
 671
 672        curr->sum_exec_runtime += delta_exec;
 673        schedstat_add(cfs_rq, exec_clock, delta_exec);
 674        delta_exec_weighted = calc_delta_fair(delta_exec, curr);
 675
 676        curr->vruntime += delta_exec_weighted;
 677        update_min_vruntime(cfs_rq);
 678
 679#if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED
 680        cfs_rq->load_unacc_exec_time += delta_exec;
 681#endif
 682}
 683
 684static void update_curr(struct cfs_rq *cfs_rq)
 685{
 686        struct sched_entity *curr = cfs_rq->curr;
 687        u64 now = rq_of(cfs_rq)->clock_task;
 688        unsigned long delta_exec;
 689
 690        if (unlikely(!curr))
 691                return;
 692
 693        /*
 694         * Get the amount of time the current task was running
 695         * since the last time we changed load (this cannot
 696         * overflow on 32 bits):
 697         */
 698        delta_exec = (unsigned long)(now - curr->exec_start);
 699        if (!delta_exec)
 700                return;
 701
 702        __update_curr(cfs_rq, curr, delta_exec);
 703        curr->exec_start = now;
 704
 705        if (entity_is_task(curr)) {
 706                struct task_struct *curtask = task_of(curr);
 707
 708                trace_sched_stat_runtime(curtask, delta_exec, curr->vruntime);
 709                cpuacct_charge(curtask, delta_exec);
 710                account_group_exec_runtime(curtask, delta_exec);
 711        }
 712
 713        account_cfs_rq_runtime(cfs_rq, delta_exec);
 714}
 715
 716static inline void
 717update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
 718{
 719        schedstat_set(se->statistics.wait_start, rq_of(cfs_rq)->clock);
 720}
 721
 722/*
 723 * Task is being enqueued - update stats:
 724 */
 725static void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
 726{
 727        /*
 728         * Are we enqueueing a waiting task? (for current tasks
 729         * a dequeue/enqueue event is a NOP)
 730         */
 731        if (se != cfs_rq->curr)
 732                update_stats_wait_start(cfs_rq, se);
 733}
 734
 735static void
 736update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
 737{
 738        schedstat_set(se->statistics.wait_max, max(se->statistics.wait_max,
 739                        rq_of(cfs_rq)->clock - se->statistics.wait_start));
 740        schedstat_set(se->statistics.wait_count, se->statistics.wait_count + 1);
 741        schedstat_set(se->statistics.wait_sum, se->statistics.wait_sum +
 742                        rq_of(cfs_rq)->clock - se->statistics.wait_start);
 743#ifdef CONFIG_SCHEDSTATS
 744        if (entity_is_task(se)) {
 745                trace_sched_stat_wait(task_of(se),
 746                        rq_of(cfs_rq)->clock - se->statistics.wait_start);
 747        }
 748#endif
 749        schedstat_set(se->statistics.wait_start, 0);
 750}
 751
 752static inline void
 753update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
 754{
 755        /*
 756         * Mark the end of the wait period if dequeueing a
 757         * waiting task:
 758         */
 759        if (se != cfs_rq->curr)
 760                update_stats_wait_end(cfs_rq, se);
 761}
 762
 763/*
 764 * We are picking a new current task - update its stats:
 765 */
 766static inline void
 767update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
 768{
 769        /*
 770         * We are starting a new run period:
 771         */
 772        se->exec_start = rq_of(cfs_rq)->clock_task;
 773}
 774
 775/**************************************************
 776 * Scheduling class queueing methods:
 777 */
 778
 779static void
 780account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
 781{
 782        update_load_add(&cfs_rq->load, se->load.weight);
 783        if (!parent_entity(se))
 784                update_load_add(&rq_of(cfs_rq)->load, se->load.weight);
 785#ifdef CONFIG_SMP
 786        if (entity_is_task(se))
 787                list_add(&se->group_node, &rq_of(cfs_rq)->cfs_tasks);
 788#endif
 789        cfs_rq->nr_running++;
 790}
 791
 792static void
 793account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
 794{
 795        update_load_sub(&cfs_rq->load, se->load.weight);
 796        if (!parent_entity(se))
 797                update_load_sub(&rq_of(cfs_rq)->load, se->load.weight);
 798        if (entity_is_task(se))
 799                list_del_init(&se->group_node);
 800        cfs_rq->nr_running--;
 801}
 802
 803#ifdef CONFIG_FAIR_GROUP_SCHED
 804/* we need this in update_cfs_load and load-balance functions below */
 805static inline int throttled_hierarchy(struct cfs_rq *cfs_rq);
 806# ifdef CONFIG_SMP
 807static void update_cfs_rq_load_contribution(struct cfs_rq *cfs_rq,
 808                                            int global_update)
 809{
 810        struct task_group *tg = cfs_rq->tg;
 811        long load_avg;
 812
 813        load_avg = div64_u64(cfs_rq->load_avg, cfs_rq->load_period+1);
 814        load_avg -= cfs_rq->load_contribution;
 815
 816        if (global_update || abs(load_avg) > cfs_rq->load_contribution / 8) {
 817                atomic_add(load_avg, &tg->load_weight);
 818                cfs_rq->load_contribution += load_avg;
 819        }
 820}
 821
 822static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update)
 823{
 824        u64 period = sysctl_sched_shares_window;
 825        u64 now, delta;
 826        unsigned long load = cfs_rq->load.weight;
 827
 828        if (cfs_rq->tg == &root_task_group || throttled_hierarchy(cfs_rq))
 829                return;
 830
 831        now = rq_of(cfs_rq)->clock_task;
 832        delta = now - cfs_rq->load_stamp;
 833
 834        /* truncate load history at 4 idle periods */
 835        if (cfs_rq->load_stamp > cfs_rq->load_last &&
 836            now - cfs_rq->load_last > 4 * period) {
 837                cfs_rq->load_period = 0;
 838                cfs_rq->load_avg = 0;
 839                delta = period - 1;
 840        }
 841
 842        cfs_rq->load_stamp = now;
 843        cfs_rq->load_unacc_exec_time = 0;
 844        cfs_rq->load_period += delta;
 845        if (load) {
 846                cfs_rq->load_last = now;
 847                cfs_rq->load_avg += delta * load;
 848        }
 849
 850        /* consider updating load contribution on each fold or truncate */
 851        if (global_update || cfs_rq->load_period > period
 852            || !cfs_rq->load_period)
 853                update_cfs_rq_load_contribution(cfs_rq, global_update);
 854
 855        while (cfs_rq->load_period > period) {
 856                /*
 857                 * Inline assembly required to prevent the compiler
 858                 * optimising this loop into a divmod call.
 859                 * See __iter_div_u64_rem() for another example of this.
 860                 */
 861                asm("" : "+rm" (cfs_rq->load_period));
 862                cfs_rq->load_period /= 2;
 863                cfs_rq->load_avg /= 2;
 864        }
 865
 866        if (!cfs_rq->curr && !cfs_rq->nr_running && !cfs_rq->load_avg)
 867                list_del_leaf_cfs_rq(cfs_rq);
 868}
 869
 870static inline long calc_tg_weight(struct task_group *tg, struct cfs_rq *cfs_rq)
 871{
 872        long tg_weight;
 873
 874        /*
 875         * Use this CPU's actual weight instead of the last load_contribution
 876         * to gain a more accurate current total weight. See
 877         * update_cfs_rq_load_contribution().
 878         */
 879        tg_weight = atomic_read(&tg->load_weight);
 880        tg_weight -= cfs_rq->load_contribution;
 881        tg_weight += cfs_rq->load.weight;
 882
 883        return tg_weight;
 884}
 885
 886static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
 887{
 888        long tg_weight, load, shares;
 889
 890        tg_weight = calc_tg_weight(tg, cfs_rq);
 891        load = cfs_rq->load.weight;
 892
 893        shares = (tg->shares * load);
 894        if (tg_weight)
 895                shares /= tg_weight;
 896
 897        if (shares < MIN_SHARES)
 898                shares = MIN_SHARES;
 899        if (shares > tg->shares)
 900                shares = tg->shares;
 901
 902        return shares;
 903}
 904
 905static void update_entity_shares_tick(struct cfs_rq *cfs_rq)
 906{
 907        if (cfs_rq->load_unacc_exec_time > sysctl_sched_shares_window) {
 908                update_cfs_load(cfs_rq, 0);
 909                update_cfs_shares(cfs_rq);
 910        }
 911}
 912# else /* CONFIG_SMP */
 913static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update)
 914{
 915}
 916
 917static inline long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
 918{
 919        return tg->shares;
 920}
 921
 922static inline void update_entity_shares_tick(struct cfs_rq *cfs_rq)
 923{
 924}
 925# endif /* CONFIG_SMP */
 926static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
 927                            unsigned long weight)
 928{
 929        if (se->on_rq) {
 930                /* commit outstanding execution time */
 931                if (cfs_rq->curr == se)
 932                        update_curr(cfs_rq);
 933                account_entity_dequeue(cfs_rq, se);
 934        }
 935
 936        update_load_set(&se->load, weight);
 937
 938        if (se->on_rq)
 939                account_entity_enqueue(cfs_rq, se);
 940}
 941
 942static void update_cfs_shares(struct cfs_rq *cfs_rq)
 943{
 944        struct task_group *tg;
 945        struct sched_entity *se;
 946        long shares;
 947
 948        tg = cfs_rq->tg;
 949        se = tg->se[cpu_of(rq_of(cfs_rq))];
 950        if (!se || throttled_hierarchy(cfs_rq))
 951                return;
 952#ifndef CONFIG_SMP
 953        if (likely(se->load.weight == tg->shares))
 954                return;
 955#endif
 956        shares = calc_cfs_shares(cfs_rq, tg);
 957
 958        reweight_entity(cfs_rq_of(se), se, shares);
 959}
 960#else /* CONFIG_FAIR_GROUP_SCHED */
 961static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update)
 962{
 963}
 964
 965static inline void update_cfs_shares(struct cfs_rq *cfs_rq)
 966{
 967}
 968
 969static inline void update_entity_shares_tick(struct cfs_rq *cfs_rq)
 970{
 971}
 972#endif /* CONFIG_FAIR_GROUP_SCHED */
 973
 974static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
 975{
 976#ifdef CONFIG_SCHEDSTATS
 977        struct task_struct *tsk = NULL;
 978
 979        if (entity_is_task(se))
 980                tsk = task_of(se);
 981
 982        if (se->statistics.sleep_start) {
 983                u64 delta = rq_of(cfs_rq)->clock - se->statistics.sleep_start;
 984
 985                if ((s64)delta < 0)
 986                        delta = 0;
 987
 988                if (unlikely(delta > se->statistics.sleep_max))
 989                        se->statistics.sleep_max = delta;
 990
 991                se->statistics.sleep_start = 0;
 992                se->statistics.sum_sleep_runtime += delta;
 993
 994                if (tsk) {
 995                        account_scheduler_latency(tsk, delta >> 10, 1);
 996                        trace_sched_stat_sleep(tsk, delta);
 997                }
 998        }
 999        if (se->statistics.block_start) {
1000                u64 delta = rq_of(cfs_rq)->clock - se->statistics.block_start;
1001
1002                if ((s64)delta < 0)
1003                        delta = 0;
1004
1005                if (unlikely(delta > se->statistics.block_max))
1006                        se->statistics.block_max = delta;
1007
1008                se->statistics.block_start = 0;
1009                se->statistics.sum_sleep_runtime += delta;
1010
1011                if (tsk) {
1012                        if (tsk->in_iowait) {
1013                                se->statistics.iowait_sum += delta;
1014                                se->statistics.iowait_count++;
1015                                trace_sched_stat_iowait(tsk, delta);
1016                        }
1017
1018                        trace_sched_stat_blocked(tsk, delta);
1019
1020                        /*
1021                         * Blocking time is in units of nanosecs, so shift by
1022                         * 20 to get a milliseconds-range estimation of the
1023                         * amount of time that the task spent sleeping:
1024                         */
1025                        if (unlikely(prof_on == SLEEP_PROFILING)) {
1026                                profile_hits(SLEEP_PROFILING,
1027                                                (void *)get_wchan(tsk),
1028                                                delta >> 20);
1029                        }
1030                        account_scheduler_latency(tsk, delta >> 10, 0);
1031                }
1032        }
1033#endif
1034}
1035
1036static void check_spread(struct cfs_rq *cfs_rq, struct sched_entity *se)
1037{
1038#ifdef CONFIG_SCHED_DEBUG
1039        s64 d = se->vruntime - cfs_rq->min_vruntime;
1040
1041        if (d < 0)
1042                d = -d;
1043
1044        if (d > 3*sysctl_sched_latency)
1045                schedstat_inc(cfs_rq, nr_spread_over);
1046#endif
1047}
1048
1049static void
1050place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
1051{
1052        u64 vruntime = cfs_rq->min_vruntime;
1053
1054        /*
1055         * The 'current' period is already promised to the current tasks,
1056         * however the extra weight of the new task will slow them down a
1057         * little, place the new task so that it fits in the slot that
1058         * stays open at the end.
1059         */
1060        if (initial && sched_feat(START_DEBIT))
1061                vruntime += sched_vslice(cfs_rq, se);
1062
1063        /* sleeps up to a single latency don't count. */
1064        if (!initial) {
1065                unsigned long thresh = sysctl_sched_latency;
1066
1067                /*
1068                 * Halve their sleep time's effect, to allow
1069                 * for a gentler effect of sleepers:
1070                 */
1071                if (sched_feat(GENTLE_FAIR_SLEEPERS))
1072                        thresh >>= 1;
1073
1074                vruntime -= thresh;
1075        }
1076
1077        /* ensure we never gain time by being placed backwards. */
1078        vruntime = max_vruntime(se->vruntime, vruntime);
1079
1080        se->vruntime = vruntime;
1081}
1082
1083static void check_enqueue_throttle(struct cfs_rq *cfs_rq);
1084
1085static void
1086enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
1087{
1088        /*
1089         * Update the normalized vruntime before updating min_vruntime
1090         * through callig update_curr().
1091         */
1092        if (!(flags & ENQUEUE_WAKEUP) || (flags & ENQUEUE_WAKING))
1093                se->vruntime += cfs_rq->min_vruntime;
1094
1095        /*
1096         * Update run-time statistics of the 'current'.
1097         */
1098        update_curr(cfs_rq);
1099        update_cfs_load(cfs_rq, 0);
1100        account_entity_enqueue(cfs_rq, se);
1101        update_cfs_shares(cfs_rq);
1102
1103        if (flags & ENQUEUE_WAKEUP) {
1104                place_entity(cfs_rq, se, 0);
1105                enqueue_sleeper(cfs_rq, se);
1106        }
1107
1108        update_stats_enqueue(cfs_rq, se);
1109        check_spread(cfs_rq, se);
1110        if (se != cfs_rq->curr)
1111                __enqueue_entity(cfs_rq, se);
1112        se->on_rq = 1;
1113
1114        if (cfs_rq->nr_running == 1) {
1115                list_add_leaf_cfs_rq(cfs_rq);
1116                check_enqueue_throttle(cfs_rq);
1117        }
1118}
1119
1120static void __clear_buddies_last(struct sched_entity *se)
1121{
1122        for_each_sched_entity(se) {
1123                struct cfs_rq *cfs_rq = cfs_rq_of(se);
1124                if (cfs_rq->last == se)
1125                        cfs_rq->last = NULL;
1126                else
1127                        break;
1128        }
1129}
1130
1131static void __clear_buddies_next(struct sched_entity *se)
1132{
1133        for_each_sched_entity(se) {
1134                struct cfs_rq *cfs_rq = cfs_rq_of(se);
1135                if (cfs_rq->next == se)
1136                        cfs_rq->next = NULL;
1137                else
1138                        break;
1139        }
1140}
1141
1142static void __clear_buddies_skip(struct sched_entity *se)
1143{
1144        for_each_sched_entity(se) {
1145                struct cfs_rq *cfs_rq = cfs_rq_of(se);
1146                if (cfs_rq->skip == se)
1147                        cfs_rq->skip = NULL;
1148                else
1149                        break;
1150        }
1151}
1152
1153static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se)
1154{
1155        if (cfs_rq->last == se)
1156                __clear_buddies_last(se);
1157
1158        if (cfs_rq->next == se)
1159                __clear_buddies_next(se);
1160
1161        if (cfs_rq->skip == se)
1162                __clear_buddies_skip(se);
1163}
1164
1165static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq);
1166
1167static void
1168dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
1169{
1170        /*
1171         * Update run-time statistics of the 'current'.
1172         */
1173        update_curr(cfs_rq);
1174
1175        update_stats_dequeue(cfs_rq, se);
1176        if (flags & DEQUEUE_SLEEP) {
1177#ifdef CONFIG_SCHEDSTATS
1178                if (entity_is_task(se)) {
1179                        struct task_struct *tsk = task_of(se);
1180
1181                        if (tsk->state & TASK_INTERRUPTIBLE)
1182                                se->statistics.sleep_start = rq_of(cfs_rq)->clock;
1183                        if (tsk->state & TASK_UNINTERRUPTIBLE)
1184                                se->statistics.block_start = rq_of(cfs_rq)->clock;
1185                }
1186#endif
1187        }
1188
1189        clear_buddies(cfs_rq, se);
1190
1191        if (se != cfs_rq->curr)
1192                __dequeue_entity(cfs_rq, se);
1193        se->on_rq = 0;
1194        update_cfs_load(cfs_rq, 0);
1195        account_entity_dequeue(cfs_rq, se);
1196
1197        /*
1198         * Normalize the entity after updating the min_vruntime because the
1199         * update can refer to the ->curr item and we need to reflect this
1200         * movement in our normalized position.
1201         */
1202        if (!(flags & DEQUEUE_SLEEP))
1203                se->vruntime -= cfs_rq->min_vruntime;
1204
1205        /* return excess runtime on last dequeue */
1206        return_cfs_rq_runtime(cfs_rq);
1207
1208        update_min_vruntime(cfs_rq);
1209        update_cfs_shares(cfs_rq);
1210}
1211
1212/*
1213 * Preempt the current task with a newly woken task if needed:
1214 */
1215static void
1216check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
1217{
1218        unsigned long ideal_runtime, delta_exec;
1219        struct sched_entity *se;
1220        s64 delta;
1221
1222        ideal_runtime = sched_slice(cfs_rq, curr);
1223        delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
1224        if (delta_exec > ideal_runtime) {
1225                resched_task(rq_of(cfs_rq)->curr);
1226                /*
1227                 * The current task ran long enough, ensure it doesn't get
1228                 * re-elected due to buddy favours.
1229                 */
1230                clear_buddies(cfs_rq, curr);
1231                return;
1232        }
1233
1234        /*
1235         * Ensure that a task that missed wakeup preemption by a
1236         * narrow margin doesn't have to wait for a full slice.
1237         * This also mitigates buddy induced latencies under load.
1238         */
1239        if (delta_exec < sysctl_sched_min_granularity)
1240                return;
1241
1242        se = __pick_first_entity(cfs_rq);
1243        delta = curr->vruntime - se->vruntime;
1244
1245        if (delta < 0)
1246                return;
1247
1248        if (delta > ideal_runtime)
1249                resched_task(rq_of(cfs_rq)->curr);
1250}
1251
1252static void
1253set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
1254{
1255        /* 'current' is not kept within the tree. */
1256        if (se->on_rq) {
1257                /*
1258                 * Any task has to be enqueued before it get to execute on
1259                 * a CPU. So account for the time it spent waiting on the
1260                 * runqueue.
1261                 */
1262                update_stats_wait_end(cfs_rq, se);
1263                __dequeue_entity(cfs_rq, se);
1264        }
1265
1266        update_stats_curr_start(cfs_rq, se);
1267        cfs_rq->curr = se;
1268#ifdef CONFIG_SCHEDSTATS
1269        /*
1270         * Track our maximum slice length, if the CPU's load is at
1271         * least twice that of our own weight (i.e. dont track it
1272         * when there are only lesser-weight tasks around):
1273         */
1274        if (rq_of(cfs_rq)->load.weight >= 2*se->load.weight) {
1275                se->statistics.slice_max = max(se->statistics.slice_max,
1276                        se->sum_exec_runtime - se->prev_sum_exec_runtime);
1277        }
1278#endif
1279        se->prev_sum_exec_runtime = se->sum_exec_runtime;
1280}
1281
1282static int
1283wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se);
1284
1285/*
1286 * Pick the next process, keeping these things in mind, in this order:
1287 * 1) keep things fair between processes/task groups
1288 * 2) pick the "next" process, since someone really wants that to run
1289 * 3) pick the "last" process, for cache locality
1290 * 4) do not run the "skip" process, if something else is available
1291 */
1292static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq)
1293{
1294        struct sched_entity *se = __pick_first_entity(cfs_rq);
1295        struct sched_entity *left = se;
1296
1297        /*
1298         * Avoid running the skip buddy, if running something else can
1299         * be done without getting too unfair.
1300         */
1301        if (cfs_rq->skip == se) {
1302                struct sched_entity *second = __pick_next_entity(se);
1303                if (second && wakeup_preempt_entity(second, left) < 1)
1304                        se = second;
1305        }
1306
1307        /*
1308         * Prefer last buddy, try to return the CPU to a preempted task.
1309         */
1310        if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1)
1311                se = cfs_rq->last;
1312
1313        /*
1314         * Someone really wants this to run. If it's not unfair, run it.
1315         */
1316        if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1)
1317                se = cfs_rq->next;
1318
1319        clear_buddies(cfs_rq, se);
1320
1321        return se;
1322}
1323
1324static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq);
1325
1326static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
1327{
1328        /*
1329         * If still on the runqueue then deactivate_task()
1330         * was not called and update_curr() has to be done:
1331         */
1332        if (prev->on_rq)
1333                update_curr(cfs_rq);
1334
1335        /* throttle cfs_rqs exceeding runtime */
1336        check_cfs_rq_runtime(cfs_rq);
1337
1338        check_spread(cfs_rq, prev);
1339        if (prev->on_rq) {
1340                update_stats_wait_start(cfs_rq, prev);
1341                /* Put 'current' back into the tree. */
1342                __enqueue_entity(cfs_rq, prev);
1343        }
1344        cfs_rq->curr = NULL;
1345}
1346
1347static void
1348entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
1349{
1350        /*
1351         * Update run-time statistics of the 'current'.
1352         */
1353        update_curr(cfs_rq);
1354
1355        /*
1356         * Update share accounting for long-running entities.
1357         */
1358        update_entity_shares_tick(cfs_rq);
1359
1360#ifdef CONFIG_SCHED_HRTICK
1361        /*
1362         * queued ticks are scheduled to match the slice, so don't bother
1363         * validating it and just reschedule.
1364         */
1365        if (queued) {
1366                resched_task(rq_of(cfs_rq)->curr);
1367                return;
1368        }
1369        /*
1370         * don't let the period tick interfere with the hrtick preemption
1371         */
1372        if (!sched_feat(DOUBLE_TICK) &&
1373                        hrtimer_active(&rq_of(cfs_rq)->hrtick_timer))
1374                return;
1375#endif
1376
1377        if (cfs_rq->nr_running > 1)
1378                check_preempt_tick(cfs_rq, curr);
1379}
1380
1381
1382/**************************************************
1383 * CFS bandwidth control machinery
1384 */
1385
1386#ifdef CONFIG_CFS_BANDWIDTH
1387
1388#ifdef HAVE_JUMP_LABEL
1389static struct static_key __cfs_bandwidth_used;
1390
1391static inline bool cfs_bandwidth_used(void)
1392{
1393        return static_key_false(&__cfs_bandwidth_used);
1394}
1395
1396void account_cfs_bandwidth_used(int enabled, int was_enabled)
1397{
1398        /* only need to count groups transitioning between enabled/!enabled */
1399        if (enabled && !was_enabled)
1400                static_key_slow_inc(&__cfs_bandwidth_used);
1401        else if (!enabled && was_enabled)
1402                static_key_slow_dec(&__cfs_bandwidth_used);
1403}
1404#else /* HAVE_JUMP_LABEL */
1405static bool cfs_bandwidth_used(void)
1406{
1407        return true;
1408}
1409
1410void account_cfs_bandwidth_used(int enabled, int was_enabled) {}
1411#endif /* HAVE_JUMP_LABEL */
1412
1413/*
1414 * default period for cfs group bandwidth.
1415 * default: 0.1s, units: nanoseconds
1416 */
1417static inline u64 default_cfs_period(void)
1418{
1419        return 100000000ULL;
1420}
1421
1422static inline u64 sched_cfs_bandwidth_slice(void)
1423{
1424        return (u64)sysctl_sched_cfs_bandwidth_slice * NSEC_PER_USEC;
1425}
1426
1427/*
1428 * Replenish runtime according to assigned quota and update expiration time.
1429 * We use sched_clock_cpu directly instead of rq->clock to avoid adding
1430 * additional synchronization around rq->lock.
1431 *
1432 * requires cfs_b->lock
1433 */
1434void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b)
1435{
1436        u64 now;
1437
1438        if (cfs_b->quota == RUNTIME_INF)
1439                return;
1440
1441        now = sched_clock_cpu(smp_processor_id());
1442        cfs_b->runtime = cfs_b->quota;
1443        cfs_b->runtime_expires = now + ktime_to_ns(cfs_b->period);
1444}
1445
1446static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
1447{
1448        return &tg->cfs_bandwidth;
1449}
1450
1451/* returns 0 on failure to allocate runtime */
1452static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq)
1453{
1454        struct task_group *tg = cfs_rq->tg;
1455        struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(tg);
1456        u64 amount = 0, min_amount, expires;
1457
1458        /* note: this is a positive sum as runtime_remaining <= 0 */
1459        min_amount = sched_cfs_bandwidth_slice() - cfs_rq->runtime_remaining;
1460
1461        raw_spin_lock(&cfs_b->lock);
1462        if (cfs_b->quota == RUNTIME_INF)
1463                amount = min_amount;
1464        else {
1465                /*
1466                 * If the bandwidth pool has become inactive, then at least one
1467                 * period must have elapsed since the last consumption.
1468                 * Refresh the global state and ensure bandwidth timer becomes
1469                 * active.
1470                 */
1471                if (!cfs_b->timer_active) {
1472                        __refill_cfs_bandwidth_runtime(cfs_b);
1473                        __start_cfs_bandwidth(cfs_b);
1474                }
1475
1476                if (cfs_b->runtime > 0) {
1477                        amount = min(cfs_b->runtime, min_amount);
1478                        cfs_b->runtime -= amount;
1479                        cfs_b->idle = 0;
1480                }
1481        }
1482        expires = cfs_b->runtime_expires;
1483        raw_spin_unlock(&cfs_b->lock);
1484
1485        cfs_rq->runtime_remaining += amount;
1486        /*
1487         * we may have advanced our local expiration to account for allowed
1488         * spread between our sched_clock and the one on which runtime was
1489         * issued.
1490         */
1491        if ((s64)(expires - cfs_rq->runtime_expires) > 0)
1492                cfs_rq->runtime_expires = expires;
1493
1494        return cfs_rq->runtime_remaining > 0;
1495}
1496
1497/*
1498 * Note: This depends on the synchronization provided by sched_clock and the
1499 * fact that rq->clock snapshots this value.
1500 */
1501static void expire_cfs_rq_runtime(struct cfs_rq *cfs_rq)
1502{
1503        struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
1504        struct rq *rq = rq_of(cfs_rq);
1505
1506        /* if the deadline is ahead of our clock, nothing to do */
1507        if (likely((s64)(rq->clock - cfs_rq->runtime_expires) < 0))
1508                return;
1509
1510        if (cfs_rq->runtime_remaining < 0)
1511                return;
1512
1513        /*
1514         * If the local deadline has passed we have to consider the
1515         * possibility that our sched_clock is 'fast' and the global deadline
1516         * has not truly expired.
1517         *
1518         * Fortunately we can check determine whether this the case by checking
1519         * whether the global deadline has advanced.
1520         */
1521
1522        if ((s64)(cfs_rq->runtime_expires - cfs_b->runtime_expires) >= 0) {
1523                /* extend local deadline, drift is bounded above by 2 ticks */
1524                cfs_rq->runtime_expires += TICK_NSEC;
1525        } else {
1526                /* global deadline is ahead, expiration has passed */
1527                cfs_rq->runtime_remaining = 0;
1528        }
1529}
1530
1531static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq,
1532                                     unsigned long delta_exec)
1533{
1534        /* dock delta_exec before expiring quota (as it could span periods) */
1535        cfs_rq->runtime_remaining -= delta_exec;
1536        expire_cfs_rq_runtime(cfs_rq);
1537
1538        if (likely(cfs_rq->runtime_remaining > 0))
1539                return;
1540
1541        /*
1542         * if we're unable to extend our runtime we resched so that the active
1543         * hierarchy can be throttled
1544         */
1545        if (!assign_cfs_rq_runtime(cfs_rq) && likely(cfs_rq->curr))
1546                resched_task(rq_of(cfs_rq)->curr);
1547}
1548
1549static __always_inline
1550void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, unsigned long delta_exec)
1551{
1552        if (!cfs_bandwidth_used() || !cfs_rq->runtime_enabled)
1553                return;
1554
1555        __account_cfs_rq_runtime(cfs_rq, delta_exec);
1556}
1557
1558static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
1559{
1560        return cfs_bandwidth_used() && cfs_rq->throttled;
1561}
1562
1563/* check whether cfs_rq, or any parent, is throttled */
1564static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)
1565{
1566        return cfs_bandwidth_used() && cfs_rq->throttle_count;
1567}
1568
1569/*
1570 * Ensure that neither of the group entities corresponding to src_cpu or
1571 * dest_cpu are members of a throttled hierarchy when performing group
1572 * load-balance operations.
1573 */
1574static inline int throttled_lb_pair(struct task_group *tg,
1575                                    int src_cpu, int dest_cpu)
1576{
1577        struct cfs_rq *src_cfs_rq, *dest_cfs_rq;
1578
1579        src_cfs_rq = tg->cfs_rq[src_cpu];
1580        dest_cfs_rq = tg->cfs_rq[dest_cpu];
1581
1582        return throttled_hierarchy(src_cfs_rq) ||
1583               throttled_hierarchy(dest_cfs_rq);
1584}
1585
1586/* updated child weight may affect parent so we have to do this bottom up */
1587static int tg_unthrottle_up(struct task_group *tg, void *data)
1588{
1589        struct rq *rq = data;
1590        struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
1591
1592        cfs_rq->throttle_count--;
1593#ifdef CONFIG_SMP
1594        if (!cfs_rq->throttle_count) {
1595                u64 delta = rq->clock_task - cfs_rq->load_stamp;
1596
1597                /* leaving throttled state, advance shares averaging windows */
1598                cfs_rq->load_stamp += delta;
1599                cfs_rq->load_last += delta;
1600
1601                /* update entity weight now that we are on_rq again */
1602                update_cfs_shares(cfs_rq);
1603        }
1604#endif
1605
1606        return 0;
1607}
1608
1609static int tg_throttle_down(struct task_group *tg, void *data)
1610{
1611        struct rq *rq = data;
1612        struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
1613
1614        /* group is entering throttled state, record last load */
1615        if (!cfs_rq->throttle_count)
1616                update_cfs_load(cfs_rq, 0);
1617        cfs_rq->throttle_count++;
1618
1619        return 0;
1620}
1621
1622static void throttle_cfs_rq(struct cfs_rq *cfs_rq)
1623{
1624        struct rq *rq = rq_of(cfs_rq);
1625        struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
1626        struct sched_entity *se;
1627        long task_delta, dequeue = 1;
1628
1629        se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))];
1630
1631        /* account load preceding throttle */
1632        rcu_read_lock();
1633        walk_tg_tree_from(cfs_rq->tg, tg_throttle_down, tg_nop, (void *)rq);
1634        rcu_read_unlock();
1635
1636        task_delta = cfs_rq->h_nr_running;
1637        for_each_sched_entity(se) {
1638                struct cfs_rq *qcfs_rq = cfs_rq_of(se);
1639                /* throttled entity or throttle-on-deactivate */
1640                if (!se->on_rq)
1641                        break;
1642
1643                if (dequeue)
1644                        dequeue_entity(qcfs_rq, se, DEQUEUE_SLEEP);
1645                qcfs_rq->h_nr_running -= task_delta;
1646
1647                if (qcfs_rq->load.weight)
1648                        dequeue = 0;
1649        }
1650
1651        if (!se)
1652                rq->nr_running -= task_delta;
1653
1654        cfs_rq->throttled = 1;
1655        cfs_rq->throttled_timestamp = rq->clock;
1656        raw_spin_lock(&cfs_b->lock);
1657        list_add_tail_rcu(&cfs_rq->throttled_list, &cfs_b->throttled_cfs_rq);
1658        raw_spin_unlock(&cfs_b->lock);
1659}
1660
1661void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
1662{
1663        struct rq *rq = rq_of(cfs_rq);
1664        struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
1665        struct sched_entity *se;
1666        int enqueue = 1;
1667        long task_delta;
1668
1669        se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))];
1670
1671        cfs_rq->throttled = 0;
1672        raw_spin_lock(&cfs_b->lock);
1673        cfs_b->throttled_time += rq->clock - cfs_rq->throttled_timestamp;
1674        list_del_rcu(&cfs_rq->throttled_list);
1675        raw_spin_unlock(&cfs_b->lock);
1676        cfs_rq->throttled_timestamp = 0;
1677
1678        update_rq_clock(rq);
1679        /* update hierarchical throttle state */
1680        walk_tg_tree_from(cfs_rq->tg, tg_nop, tg_unthrottle_up, (void *)rq);
1681
1682        if (!cfs_rq->load.weight)
1683                return;
1684
1685        task_delta = cfs_rq->h_nr_running;
1686        for_each_sched_entity(se) {
1687                if (se->on_rq)
1688                        enqueue = 0;
1689
1690                cfs_rq = cfs_rq_of(se);
1691                if (enqueue)
1692                        enqueue_entity(cfs_rq, se, ENQUEUE_WAKEUP);
1693                cfs_rq->h_nr_running += task_delta;
1694
1695                if (cfs_rq_throttled(cfs_rq))
1696                        break;
1697        }
1698
1699        if (!se)
1700                rq->nr_running += task_delta;
1701
1702        /* determine whether we need to wake up potentially idle cpu */
1703        if (rq->curr == rq->idle && rq->cfs.nr_running)
1704                resched_task(rq->curr);
1705}
1706
1707static u64 distribute_cfs_runtime(struct cfs_bandwidth *cfs_b,
1708                u64 remaining, u64 expires)
1709{
1710        struct cfs_rq *cfs_rq;
1711        u64 runtime = remaining;
1712
1713        rcu_read_lock();
1714        list_for_each_entry_rcu(cfs_rq, &cfs_b->throttled_cfs_rq,
1715                                throttled_list) {
1716                struct rq *rq = rq_of(cfs_rq);
1717
1718                raw_spin_lock(&rq->lock);
1719                if (!cfs_rq_throttled(cfs_rq))
1720                        goto next;
1721
1722                runtime = -cfs_rq->runtime_remaining + 1;
1723                if (runtime > remaining)
1724                        runtime = remaining;
1725                remaining -= runtime;
1726
1727                cfs_rq->runtime_remaining += runtime;
1728                cfs_rq->runtime_expires = expires;
1729
1730                /* we check whether we're throttled above */
1731                if (cfs_rq->runtime_remaining > 0)
1732                        unthrottle_cfs_rq(cfs_rq);
1733
1734next:
1735                raw_spin_unlock(&rq->lock);
1736
1737                if (!remaining)
1738                        break;
1739        }
1740        rcu_read_unlock();
1741
1742        return remaining;
1743}
1744
1745/*
1746 * Responsible for refilling a task_group's bandwidth and unthrottling its
1747 * cfs_rqs as appropriate. If there has been no activity within the last
1748 * period the timer is deactivated until scheduling resumes; cfs_b->idle is
1749 * used to track this state.
1750 */
1751static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun)
1752{
1753        u64 runtime, runtime_expires;
1754        int idle = 1, throttled;
1755
1756        raw_spin_lock(&cfs_b->lock);
1757        /* no need to continue the timer with no bandwidth constraint */
1758        if (cfs_b->quota == RUNTIME_INF)
1759                goto out_unlock;
1760
1761        throttled = !list_empty(&cfs_b->throttled_cfs_rq);
1762        /* idle depends on !throttled (for the case of a large deficit) */
1763        idle = cfs_b->idle && !throttled;
1764        cfs_b->nr_periods += overrun;
1765
1766        /* if we're going inactive then everything else can be deferred */
1767        if (idle)
1768                goto out_unlock;
1769
1770        __refill_cfs_bandwidth_runtime(cfs_b);
1771
1772        if (!throttled) {
1773                /* mark as potentially idle for the upcoming period */
1774                cfs_b->idle = 1;
1775                goto out_unlock;
1776        }
1777
1778        /* account preceding periods in which throttling occurred */
1779        cfs_b->nr_throttled += overrun;
1780
1781        /*
1782         * There are throttled entities so we must first use the new bandwidth
1783         * to unthrottle them before making it generally available.  This
1784         * ensures that all existing debts will be paid before a new cfs_rq is
1785         * allowed to run.
1786         */
1787        runtime = cfs_b->runtime;
1788        runtime_expires = cfs_b->runtime_expires;
1789        cfs_b->runtime = 0;
1790
1791        /*
1792         * This check is repeated as we are holding onto the new bandwidth
1793         * while we unthrottle.  This can potentially race with an unthrottled
1794         * group trying to acquire new bandwidth from the global pool.
1795         */
1796        while (throttled && runtime > 0) {
1797                raw_spin_unlock(&cfs_b->lock);
1798                /* we can't nest cfs_b->lock while distributing bandwidth */
1799                runtime = distribute_cfs_runtime(cfs_b, runtime,
1800                                                 runtime_expires);
1801                raw_spin_lock(&cfs_b->lock);
1802
1803                throttled = !list_empty(&cfs_b->throttled_cfs_rq);
1804        }
1805
1806        /* return (any) remaining runtime */
1807        cfs_b->runtime = runtime;
1808        /*
1809         * While we are ensured activity in the period following an
1810         * unthrottle, this also covers the case in which the new bandwidth is
1811         * insufficient to cover the existing bandwidth deficit.  (Forcing the
1812         * timer to remain active while there are any throttled entities.)
1813         */
1814        cfs_b->idle = 0;
1815out_unlock:
1816        if (idle)
1817                cfs_b->timer_active = 0;
1818        raw_spin_unlock(&cfs_b->lock);
1819
1820        return idle;
1821}
1822
1823/* a cfs_rq won't donate quota below this amount */
1824static const u64 min_cfs_rq_runtime = 1 * NSEC_PER_MSEC;
1825/* minimum remaining period time to redistribute slack quota */
1826static const u64 min_bandwidth_expiration = 2 * NSEC_PER_MSEC;
1827/* how long we wait to gather additional slack before distributing */
1828static const u64 cfs_bandwidth_slack_period = 5 * NSEC_PER_MSEC;
1829
1830/* are we near the end of the current quota period? */
1831static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire)
1832{
1833        struct hrtimer *refresh_timer = &cfs_b->period_timer;
1834        u64 remaining;
1835
1836        /* if the call-back is running a quota refresh is already occurring */
1837        if (hrtimer_callback_running(refresh_timer))
1838                return 1;
1839
1840        /* is a quota refresh about to occur? */
1841        remaining = ktime_to_ns(hrtimer_expires_remaining(refresh_timer));
1842        if (remaining < min_expire)
1843                return 1;
1844
1845        return 0;
1846}
1847
1848static void start_cfs_slack_bandwidth(struct cfs_bandwidth *cfs_b)
1849{
1850        u64 min_left = cfs_bandwidth_slack_period + min_bandwidth_expiration;
1851
1852        /* if there's a quota refresh soon don't bother with slack */
1853        if (runtime_refresh_within(cfs_b, min_left))
1854                return;
1855
1856        start_bandwidth_timer(&cfs_b->slack_timer,
1857                                ns_to_ktime(cfs_bandwidth_slack_period));
1858}
1859
1860/* we know any runtime found here is valid as update_curr() precedes return */
1861static void __return_cfs_rq_runtime(struct cfs_rq *cfs_rq)
1862{
1863        struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
1864        s64 slack_runtime = cfs_rq->runtime_remaining - min_cfs_rq_runtime;
1865
1866        if (slack_runtime <= 0)
1867                return;
1868
1869        raw_spin_lock(&cfs_b->lock);
1870        if (cfs_b->quota != RUNTIME_INF &&
1871            cfs_rq->runtime_expires == cfs_b->runtime_expires) {
1872                cfs_b->runtime += slack_runtime;
1873
1874                /* we are under rq->lock, defer unthrottling using a timer */
1875                if (cfs_b->runtime > sched_cfs_bandwidth_slice() &&
1876                    !list_empty(&cfs_b->throttled_cfs_rq))
1877                        start_cfs_slack_bandwidth(cfs_b);
1878        }
1879        raw_spin_unlock(&cfs_b->lock);
1880
1881        /* even if it's not valid for return we don't want to try again */
1882        cfs_rq->runtime_remaining -= slack_runtime;
1883}
1884
1885static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq)
1886{
1887        if (!cfs_bandwidth_used())
1888                return;
1889
1890        if (!cfs_rq->runtime_enabled || cfs_rq->nr_running)
1891                return;
1892
1893        __return_cfs_rq_runtime(cfs_rq);
1894}
1895
1896/*
1897 * This is done with a timer (instead of inline with bandwidth return) since
1898 * it's necessary to juggle rq->locks to unthrottle their respective cfs_rqs.
1899 */
1900static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b)
1901{
1902        u64 runtime = 0, slice = sched_cfs_bandwidth_slice();
1903        u64 expires;
1904
1905        /* confirm we're still not at a refresh boundary */
1906        if (runtime_refresh_within(cfs_b, min_bandwidth_expiration))
1907                return;
1908
1909        raw_spin_lock(&cfs_b->lock);
1910        if (cfs_b->quota != RUNTIME_INF && cfs_b->runtime > slice) {
1911                runtime = cfs_b->runtime;
1912                cfs_b->runtime = 0;
1913        }
1914        expires = cfs_b->runtime_expires;
1915        raw_spin_unlock(&cfs_b->lock);
1916
1917        if (!runtime)
1918                return;
1919
1920        runtime = distribute_cfs_runtime(cfs_b, runtime, expires);
1921
1922        raw_spin_lock(&cfs_b->lock);
1923        if (expires == cfs_b->runtime_expires)
1924                cfs_b->runtime = runtime;
1925        raw_spin_unlock(&cfs_b->lock);
1926}
1927
1928/*
1929 * When a group wakes up we want to make sure that its quota is not already
1930 * expired/exceeded, otherwise it may be allowed to steal additional ticks of
1931 * runtime as update_curr() throttling can not not trigger until it's on-rq.
1932 */
1933static void check_enqueue_throttle(struct cfs_rq *cfs_rq)
1934{
1935        if (!cfs_bandwidth_used())
1936                return;
1937
1938        /* an active group must be handled by the update_curr()->put() path */
1939        if (!cfs_rq->runtime_enabled || cfs_rq->curr)
1940                return;
1941
1942        /* ensure the group is not already throttled */
1943        if (cfs_rq_throttled(cfs_rq))
1944                return;
1945
1946        /* update runtime allocation */
1947        account_cfs_rq_runtime(cfs_rq, 0);
1948        if (cfs_rq->runtime_remaining <= 0)
1949                throttle_cfs_rq(cfs_rq);
1950}
1951
1952/* conditionally throttle active cfs_rq's from put_prev_entity() */
1953static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq)
1954{
1955        if (!cfs_bandwidth_used())
1956                return;
1957
1958        if (likely(!cfs_rq->runtime_enabled || cfs_rq->runtime_remaining > 0))
1959                return;
1960
1961        /*
1962         * it's possible for a throttled entity to be forced into a running
1963         * state (e.g. set_curr_task), in this case we're finished.
1964         */
1965        if (cfs_rq_throttled(cfs_rq))
1966                return;
1967
1968        throttle_cfs_rq(cfs_rq);
1969}
1970
1971static inline u64 default_cfs_period(void);
1972static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun);
1973static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b);
1974
1975static enum hrtimer_restart sched_cfs_slack_timer(struct hrtimer *timer)
1976{
1977        struct cfs_bandwidth *cfs_b =
1978                container_of(timer, struct cfs_bandwidth, slack_timer);
1979        do_sched_cfs_slack_timer(cfs_b);
1980
1981        return HRTIMER_NORESTART;
1982}
1983
1984static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer)
1985{
1986        struct cfs_bandwidth *cfs_b =
1987                container_of(timer, struct cfs_bandwidth, period_timer);
1988        ktime_t now;
1989        int overrun;
1990        int idle = 0;
1991
1992        for (;;) {
1993                now = hrtimer_cb_get_time(timer);
1994                overrun = hrtimer_forward(timer, now, cfs_b->period);
1995
1996                if (!overrun)
1997                        break;
1998
1999                idle = do_sched_cfs_period_timer(cfs_b, overrun);
2000        }
2001
2002        return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
2003}
2004
2005void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
2006{
2007        raw_spin_lock_init(&cfs_b->lock);
2008        cfs_b->runtime = 0;
2009        cfs_b->quota = RUNTIME_INF;
2010        cfs_b->period = ns_to_ktime(default_cfs_period());
2011
2012        INIT_LIST_HEAD(&cfs_b->throttled_cfs_rq);
2013        hrtimer_init(&cfs_b->period_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
2014        cfs_b->period_timer.function = sched_cfs_period_timer;
2015        hrtimer_init(&cfs_b->slack_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
2016        cfs_b->slack_timer.function = sched_cfs_slack_timer;
2017}
2018
2019static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq)
2020{
2021        cfs_rq->runtime_enabled = 0;
2022        INIT_LIST_HEAD(&cfs_rq->throttled_list);
2023}
2024
2025/* requires cfs_b->lock, may release to reprogram timer */
2026void __start_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
2027{
2028        /*
2029         * The timer may be active because we're trying to set a new bandwidth
2030         * period or because we're racing with the tear-down path
2031         * (timer_active==0 becomes visible before the hrtimer call-back
2032         * terminates).  In either case we ensure that it's re-programmed
2033         */
2034        while (unlikely(hrtimer_active(&cfs_b->period_timer))) {
2035                raw_spin_unlock(&cfs_b->lock);
2036                /* ensure cfs_b->lock is available while we wait */
2037                hrtimer_cancel(&cfs_b->period_timer);
2038
2039                raw_spin_lock(&cfs_b->lock);
2040                /* if someone else restarted the timer then we're done */
2041                if (cfs_b->timer_active)
2042                        return;
2043        }
2044
2045        cfs_b->timer_active = 1;
2046        start_bandwidth_timer(&cfs_b->period_timer, cfs_b->period);
2047}
2048
2049static void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
2050{
2051        hrtimer_cancel(&cfs_b->period_timer);
2052        hrtimer_cancel(&cfs_b->slack_timer);
2053}
2054
2055static void unthrottle_offline_cfs_rqs(struct rq *rq)
2056{
2057        struct cfs_rq *cfs_rq;
2058
2059        for_each_leaf_cfs_rq(rq, cfs_rq) {
2060                struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
2061
2062                if (!cfs_rq->runtime_enabled)
2063                        continue;
2064
2065                /*
2066                 * clock_task is not advancing so we just need to make sure
2067                 * there's some valid quota amount
2068                 */
2069                cfs_rq->runtime_remaining = cfs_b->quota;
2070                if (cfs_rq_throttled(cfs_rq))
2071                        unthrottle_cfs_rq(cfs_rq);
2072        }
2073}
2074
2075#else /* CONFIG_CFS_BANDWIDTH */
2076static __always_inline
2077void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, unsigned long delta_exec) {}
2078static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
2079static void check_enqueue_throttle(struct cfs_rq *cfs_rq) {}
2080static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
2081
2082static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
2083{
2084        return 0;
2085}
2086
2087static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)
2088{
2089        return 0;
2090}
2091
2092static inline int throttled_lb_pair(struct task_group *tg,
2093                                    int src_cpu, int dest_cpu)
2094{
2095        return 0;
2096}
2097
2098void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
2099
2100#ifdef CONFIG_FAIR_GROUP_SCHED
2101static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
2102#endif
2103
2104static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
2105{
2106        return NULL;
2107}
2108static inline void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
2109static inline void unthrottle_offline_cfs_rqs(struct rq *rq) {}
2110
2111#endif /* CONFIG_CFS_BANDWIDTH */
2112
2113/**************************************************
2114 * CFS operations on tasks:
2115 */
2116
2117#ifdef CONFIG_SCHED_HRTICK
2118static void hrtick_start_fair(struct rq *rq, struct task_struct *p)
2119{
2120        struct sched_entity *se = &p->se;
2121        struct cfs_rq *cfs_rq = cfs_rq_of(se);
2122
2123        WARN_ON(task_rq(p) != rq);
2124
2125        if (cfs_rq->nr_running > 1) {
2126                u64 slice = sched_slice(cfs_rq, se);
2127                u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime;
2128                s64 delta = slice - ran;
2129
2130                if (delta < 0) {
2131                        if (rq->curr == p)
2132                                resched_task(p);
2133                        return;
2134                }
2135
2136                /*
2137                 * Don't schedule slices shorter than 10000ns, that just
2138                 * doesn't make sense. Rely on vruntime for fairness.
2139                 */
2140                if (rq->curr != p)
2141                        delta = max_t(s64, 10000LL, delta);
2142
2143                hrtick_start(rq, delta);
2144        }
2145}
2146
2147/*
2148 * called from enqueue/dequeue and updates the hrtick when the
2149 * current task is from our class and nr_running is low enough
2150 * to matter.
2151 */
2152static void hrtick_update(struct rq *rq)
2153{
2154        struct task_struct *curr = rq->curr;
2155
2156        if (!hrtick_enabled(rq) || curr->sched_class != &fair_sched_class)
2157                return;
2158
2159        if (cfs_rq_of(&curr->se)->nr_running < sched_nr_latency)
2160                hrtick_start_fair(rq, curr);
2161}
2162#else /* !CONFIG_SCHED_HRTICK */
2163static inline void
2164hrtick_start_fair(struct rq *rq, struct task_struct *p)
2165{
2166}
2167
2168static inline void hrtick_update(struct rq *rq)
2169{
2170}
2171#endif
2172
2173/*
2174 * The enqueue_task method is called before nr_running is
2175 * increased. Here we update the fair scheduling stats and
2176 * then put the task into the rbtree:
2177 */
2178static void
2179enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
2180{
2181        struct cfs_rq *cfs_rq;
2182        struct sched_entity *se = &p->se;
2183
2184        for_each_sched_entity(se) {
2185                if (se->on_rq)
2186                        break;
2187                cfs_rq = cfs_rq_of(se);
2188                enqueue_entity(cfs_rq, se, flags);
2189
2190                /*
2191                 * end evaluation on encountering a throttled cfs_rq
2192                 *
2193                 * note: in the case of encountering a throttled cfs_rq we will
2194                 * post the final h_nr_running increment below.
2195                */
2196                if (cfs_rq_throttled(cfs_rq))
2197                        break;
2198                cfs_rq->h_nr_running++;
2199
2200                flags = ENQUEUE_WAKEUP;
2201        }
2202
2203        for_each_sched_entity(se) {
2204                cfs_rq = cfs_rq_of(se);
2205                cfs_rq->h_nr_running++;
2206
2207                if (cfs_rq_throttled(cfs_rq))
2208                        break;
2209
2210                update_cfs_load(cfs_rq, 0);
2211                update_cfs_shares(cfs_rq);
2212        }
2213
2214        if (!se)
2215                inc_nr_running(rq);
2216        hrtick_update(rq);
2217}
2218
2219static void set_next_buddy(struct sched_entity *se);
2220
2221/*
2222 * The dequeue_task method is called before nr_running is
2223 * decreased. We remove the task from the rbtree and
2224 * update the fair scheduling stats:
2225 */
2226static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
2227{
2228        struct cfs_rq *cfs_rq;
2229        struct sched_entity *se = &p->se;
2230        int task_sleep = flags & DEQUEUE_SLEEP;
2231
2232        for_each_sched_entity(se) {
2233                cfs_rq = cfs_rq_of(se);
2234                dequeue_entity(cfs_rq, se, flags);
2235
2236                /*
2237                 * end evaluation on encountering a throttled cfs_rq
2238                 *
2239                 * note: in the case of encountering a throttled cfs_rq we will
2240                 * post the final h_nr_running decrement below.
2241                */
2242                if (cfs_rq_throttled(cfs_rq))
2243                        break;
2244                cfs_rq->h_nr_running--;
2245
2246                /* Don't dequeue parent if it has other entities besides us */
2247                if (cfs_rq->load.weight) {
2248                        /*
2249                         * Bias pick_next to pick a task from this cfs_rq, as
2250                         * p is sleeping when it is within its sched_slice.
2251                         */
2252                        if (task_sleep && parent_entity(se))
2253                                set_next_buddy(parent_entity(se));
2254
2255                        /* avoid re-evaluating load for this entity */
2256                        se = parent_entity(se);
2257                        break;
2258                }
2259                flags |= DEQUEUE_SLEEP;
2260        }
2261
2262        for_each_sched_entity(se) {
2263                cfs_rq = cfs_rq_of(se);
2264                cfs_rq->h_nr_running--;
2265
2266                if (cfs_rq_throttled(cfs_rq))
2267                        break;
2268
2269                update_cfs_load(cfs_rq, 0);
2270                update_cfs_shares(cfs_rq);
2271        }
2272
2273        if (!se)
2274                dec_nr_running(rq);
2275        hrtick_update(rq);
2276}
2277
2278#ifdef CONFIG_SMP
2279/* Used instead of source_load when we know the type == 0 */
2280static unsigned long weighted_cpuload(const int cpu)
2281{
2282        return cpu_rq(cpu)->load.weight;
2283}
2284
2285/*
2286 * Return a low guess at the load of a migration-source cpu weighted
2287 * according to the scheduling class and "nice" value.
2288 *
2289 * We want to under-estimate the load of migration sources, to
2290 * balance conservatively.
2291 */
2292static unsigned long source_load(int cpu, int type)
2293{
2294        struct rq *rq = cpu_rq(cpu);
2295        unsigned long total = weighted_cpuload(cpu);
2296
2297        if (type == 0 || !sched_feat(LB_BIAS))
2298                return total;
2299
2300        return min(rq->cpu_load[type-1], total);
2301}
2302
2303/*
2304 * Return a high guess at the load of a migration-target cpu weighted
2305 * according to the scheduling class and "nice" value.
2306 */
2307static unsigned long target_load(int cpu, int type)
2308{
2309        struct rq *rq = cpu_rq(cpu);
2310        unsigned long total = weighted_cpuload(cpu);
2311
2312        if (type == 0 || !sched_feat(LB_BIAS))
2313                return total;
2314
2315        return max(rq->cpu_load[type-1], total);
2316}
2317
2318static unsigned long power_of(int cpu)
2319{
2320        return cpu_rq(cpu)->cpu_power;
2321}
2322
2323static unsigned long cpu_avg_load_per_task(int cpu)
2324{
2325        struct rq *rq = cpu_rq(cpu);
2326        unsigned long nr_running = ACCESS_ONCE(rq->nr_running);
2327
2328        if (nr_running)
2329                return rq->load.weight / nr_running;
2330
2331        return 0;
2332}
2333
2334
2335static void task_waking_fair(struct task_struct *p)
2336{
2337        struct sched_entity *se = &p->se;
2338        struct cfs_rq *cfs_rq = cfs_rq_of(se);
2339        u64 min_vruntime;
2340
2341#ifndef CONFIG_64BIT
2342        u64 min_vruntime_copy;
2343
2344        do {
2345                min_vruntime_copy = cfs_rq->min_vruntime_copy;
2346                smp_rmb();
2347                min_vruntime = cfs_rq->min_vruntime;
2348        } while (min_vruntime != min_vruntime_copy);
2349#else
2350        min_vruntime = cfs_rq->min_vruntime;
2351#endif
2352
2353        se->vruntime -= min_vruntime;
2354}
2355
2356#ifdef CONFIG_FAIR_GROUP_SCHED
2357/*
2358 * effective_load() calculates the load change as seen from the root_task_group
2359 *
2360 * Adding load to a group doesn't make a group heavier, but can cause movement
2361 * of group shares between cpus. Assuming the shares were perfectly aligned one
2362 * can calculate the shift in shares.
2363 *
2364 * Calculate the effective load difference if @wl is added (subtracted) to @tg
2365 * on this @cpu and results in a total addition (subtraction) of @wg to the
2366 * total group weight.
2367 *
2368 * Given a runqueue weight distribution (rw_i) we can compute a shares
2369 * distribution (s_i) using:
2370 *
2371 *   s_i = rw_i / \Sum rw_j                                             (1)
2372 *
2373 * Suppose we have 4 CPUs and our @tg is a direct child of the root group and
2374 * has 7 equal weight tasks, distributed as below (rw_i), with the resulting
2375 * shares distribution (s_i):
2376 *
2377 *   rw_i = {   2,   4,   1,   0 }
2378 *   s_i  = { 2/7, 4/7, 1/7,   0 }
2379 *
2380 * As per wake_affine() we're interested in the load of two CPUs (the CPU the
2381 * task used to run on and the CPU the waker is running on), we need to
2382 * compute the effect of waking a task on either CPU and, in case of a sync
2383 * wakeup, compute the effect of the current task going to sleep.
2384 *
2385 * So for a change of @wl to the local @cpu with an overall group weight change
2386 * of @wl we can compute the new shares distribution (s'_i) using:
2387 *
2388 *   s'_i = (rw_i + @wl) / (@wg + \Sum rw_j)                            (2)
2389 *
2390 * Suppose we're interested in CPUs 0 and 1, and want to compute the load
2391 * differences in waking a task to CPU 0. The additional task changes the
2392 * weight and shares distributions like:
2393 *
2394 *   rw'_i = {   3,   4,   1,   0 }
2395 *   s'_i  = { 3/8, 4/8, 1/8,   0 }
2396 *
2397 * We can then compute the difference in effective weight by using:
2398 *
2399 *   dw_i = S * (s'_i - s_i)                                            (3)
2400 *
2401 * Where 'S' is the group weight as seen by its parent.
2402 *
2403 * Therefore the effective change in loads on CPU 0 would be 5/56 (3/8 - 2/7)
2404 * times the weight of the group. The effect on CPU 1 would be -4/56 (4/8 -
2405 * 4/7) times the weight of the group.
2406 */
2407static long effective_load(struct task_group *tg, int cpu, long wl, long wg)
2408{
2409        struct sched_entity *se = tg->se[cpu];
2410
2411        if (!tg->parent)        /* the trivial, non-cgroup case */
2412                return wl;
2413
2414        for_each_sched_entity(se) {
2415                long w, W;
2416
2417                tg = se->my_q->tg;
2418
2419                /*
2420                 * W = @wg + \Sum rw_j
2421                 */
2422                W = wg + calc_tg_weight(tg, se->my_q);
2423
2424                /*
2425                 * w = rw_i + @wl
2426                 */
2427                w = se->my_q->load.weight + wl;
2428
2429                /*
2430                 * wl = S * s'_i; see (2)
2431                 */
2432                if (W > 0 && w < W)
2433                        wl = (w * tg->shares) / W;
2434                else
2435                        wl = tg->shares;
2436
2437                /*
2438                 * Per the above, wl is the new se->load.weight value; since
2439                 * those are clipped to [MIN_SHARES, ...) do so now. See
2440                 * calc_cfs_shares().
2441                 */
2442                if (wl < MIN_SHARES)
2443                        wl = MIN_SHARES;
2444
2445                /*
2446                 * wl = dw_i = S * (s'_i - s_i); see (3)
2447                 */
2448                wl -= se->load.weight;
2449
2450                /*
2451                 * Recursively apply this logic to all parent groups to compute
2452                 * the final effective load change on the root group. Since
2453                 * only the @tg group gets extra weight, all parent groups can
2454                 * only redistribute existing shares. @wl is the shift in shares
2455                 * resulting from this level per the above.
2456                 */
2457                wg = 0;
2458        }
2459
2460        return wl;
2461}
2462#else
2463
2464static inline unsigned long effective_load(struct task_group *tg, int cpu,
2465                unsigned long wl, unsigned long wg)
2466{
2467        return wl;
2468}
2469
2470#endif
2471
2472static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
2473{
2474        s64 this_load, load;
2475        int idx, this_cpu, prev_cpu;
2476        unsigned long tl_per_task;
2477        struct task_group *tg;
2478        unsigned long weight;
2479        int balanced;
2480
2481        idx       = sd->wake_idx;
2482        this_cpu  = smp_processor_id();
2483        prev_cpu  = task_cpu(p);
2484        load      = source_load(prev_cpu, idx);
2485        this_load = target_load(this_cpu, idx);
2486
2487        /*
2488         * If sync wakeup then subtract the (maximum possible)
2489         * effect of the currently running task from the load
2490         * of the current CPU:
2491         */
2492        if (sync) {
2493                tg = task_group(current);
2494                weight = current->se.load.weight;
2495
2496                this_load += effective_load(tg, this_cpu, -weight, -weight);
2497                load += effective_load(tg, prev_cpu, 0, -weight);
2498        }
2499
2500        tg = task_group(p);
2501        weight = p->se.load.weight;
2502
2503        /*
2504         * In low-load situations, where prev_cpu is idle and this_cpu is idle
2505         * due to the sync cause above having dropped this_load to 0, we'll
2506         * always have an imbalance, but there's really nothing you can do
2507         * about that, so that's good too.
2508         *
2509         * Otherwise check if either cpus are near enough in load to allow this
2510         * task to be woken on this_cpu.
2511         */
2512        if (this_load > 0) {
2513                s64 this_eff_load, prev_eff_load;
2514
2515                this_eff_load = 100;
2516                this_eff_load *= power_of(prev_cpu);
2517                this_eff_load *= this_load +
2518                        effective_load(tg, this_cpu, weight, weight);
2519
2520                prev_eff_load = 100 + (sd->imbalance_pct - 100) / 2;
2521                prev_eff_load *= power_of(this_cpu);
2522                prev_eff_load *= load + effective_load(tg, prev_cpu, 0, weight);
2523
2524                balanced = this_eff_load <= prev_eff_load;
2525        } else
2526                balanced = true;
2527
2528        /*
2529         * If the currently running task will sleep within
2530         * a reasonable amount of time then attract this newly
2531         * woken task:
2532         */
2533        if (sync && balanced)
2534                return 1;
2535
2536        schedstat_inc(p, se.statistics.nr_wakeups_affine_attempts);
2537        tl_per_task = cpu_avg_load_per_task(this_cpu);
2538
2539        if (balanced ||
2540            (this_load <= load &&
2541             this_load + target_load(prev_cpu, idx) <= tl_per_task)) {
2542                /*
2543                 * This domain has SD_WAKE_AFFINE and
2544                 * p is cache cold in this domain, and
2545                 * there is no bad imbalance.
2546                 */
2547                schedstat_inc(sd, ttwu_move_affine);
2548                schedstat_inc(p, se.statistics.nr_wakeups_affine);
2549
2550                return 1;
2551        }
2552        return 0;
2553}
2554
2555/*
2556 * find_idlest_group finds and returns the least busy CPU group within the
2557 * domain.
2558 */
2559static struct sched_group *
2560find_idlest_group(struct sched_domain *sd, struct task_struct *p,
2561                  int this_cpu, int load_idx)
2562{
2563        struct sched_group *idlest = NULL, *group = sd->groups;
2564        unsigned long min_load = ULONG_MAX, this_load = 0;
2565        int imbalance = 100 + (sd->imbalance_pct-100)/2;
2566
2567        do {
2568                unsigned long load, avg_load;
2569                int local_group;
2570                int i;
2571
2572                /* Skip over this group if it has no CPUs allowed */
2573                if (!cpumask_intersects(sched_group_cpus(group),
2574                                        tsk_cpus_allowed(p)))
2575                        continue;
2576
2577                local_group = cpumask_test_cpu(this_cpu,
2578                                               sched_group_cpus(group));
2579
2580                /* Tally up the load of all CPUs in the group */
2581                avg_load = 0;
2582
2583                for_each_cpu(i, sched_group_cpus(group)) {
2584                        /* Bias balancing toward cpus of our domain */
2585                        if (local_group)
2586                                load = source_load(i, load_idx);
2587                        else
2588                                load = target_load(i, load_idx);
2589
2590                        avg_load += load;
2591                }
2592
2593                /* Adjust by relative CPU power of the group */
2594                avg_load = (avg_load * SCHED_POWER_SCALE) / group->sgp->power;
2595
2596                if (local_group) {
2597                        this_load = avg_load;
2598                } else if (avg_load < min_load) {
2599                        min_load = avg_load;
2600                        idlest = group;
2601                }
2602        } while (group = group->next, group != sd->groups);
2603
2604        if (!idlest || 100*this_load < imbalance*min_load)
2605                return NULL;
2606        return idlest;
2607}
2608
2609/*
2610 * find_idlest_cpu - find the idlest cpu among the cpus in group.
2611 */
2612static int
2613find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
2614{
2615        unsigned long load, min_load = ULONG_MAX;
2616        int idlest = -1;
2617        int i;
2618
2619        /* Traverse only the allowed CPUs */
2620        for_each_cpu_and(i, sched_group_cpus(group), tsk_cpus_allowed(p)) {
2621                load = weighted_cpuload(i);
2622
2623                if (load < min_load || (load == min_load && i == this_cpu)) {
2624                        min_load = load;
2625                        idlest = i;
2626                }
2627        }
2628
2629        return idlest;
2630}
2631
2632/*
2633 * Try and locate an idle CPU in the sched_domain.
2634 */
2635static int select_idle_sibling(struct task_struct *p, int target)
2636{
2637        int cpu = smp_processor_id();
2638        int prev_cpu = task_cpu(p);
2639        struct sched_domain *sd;
2640        struct sched_group *sg;
2641        int i;
2642
2643        /*
2644         * If the task is going to be woken-up on this cpu and if it is
2645         * already idle, then it is the right target.
2646         */
2647        if (target == cpu && idle_cpu(cpu))
2648                return cpu;
2649
2650        /*
2651         * If the task is going to be woken-up on the cpu where it previously
2652         * ran and if it is currently idle, then it the right target.
2653         */
2654        if (target == prev_cpu && idle_cpu(prev_cpu))
2655                return prev_cpu;
2656
2657        /*
2658         * Otherwise, iterate the domains and find an elegible idle cpu.
2659         */
2660        sd = rcu_dereference(per_cpu(sd_llc, target));
2661        for_each_lower_domain(sd) {
2662                sg = sd->groups;
2663                do {
2664                        if (!cpumask_intersects(sched_group_cpus(sg),
2665                                                tsk_cpus_allowed(p)))
2666                                goto next;
2667
2668                        for_each_cpu(i, sched_group_cpus(sg)) {
2669                                if (!idle_cpu(i))
2670                                        goto next;
2671                        }
2672
2673                        target = cpumask_first_and(sched_group_cpus(sg),
2674                                        tsk_cpus_allowed(p));
2675                        goto done;
2676next:
2677                        sg = sg->next;
2678                } while (sg != sd->groups);
2679        }
2680done:
2681        return target;
2682}
2683
2684/*
2685 * sched_balance_self: balance the current task (running on cpu) in domains
2686 * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
2687 * SD_BALANCE_EXEC.
2688 *
2689 * Balance, ie. select the least loaded group.
2690 *
2691 * Returns the target CPU number, or the same CPU if no balancing is needed.
2692 *
2693 * preempt must be disabled.
2694 */
2695static int
2696select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flags)
2697{
2698        struct sched_domain *tmp, *affine_sd = NULL, *sd = NULL;
2699        int cpu = smp_processor_id();
2700        int prev_cpu = task_cpu(p);
2701        int new_cpu = cpu;
2702        int want_affine = 0;
2703        int want_sd = 1;
2704        int sync = wake_flags & WF_SYNC;
2705
2706        if (p->nr_cpus_allowed == 1)
2707                return prev_cpu;
2708
2709        if (sd_flag & SD_BALANCE_WAKE) {
2710                if (cpumask_test_cpu(cpu, tsk_cpus_allowed(p)))
2711                        want_affine = 1;
2712                new_cpu = prev_cpu;
2713        }
2714
2715        rcu_read_lock();
2716        for_each_domain(cpu, tmp) {
2717                if (!(tmp->flags & SD_LOAD_BALANCE))
2718                        continue;
2719
2720                /*
2721                 * If power savings logic is enabled for a domain, see if we
2722                 * are not overloaded, if so, don't balance wider.
2723                 */
2724                if (tmp->flags & (SD_PREFER_LOCAL)) {
2725                        unsigned long power = 0;
2726                        unsigned long nr_running = 0;
2727                        unsigned long capacity;
2728                        int i;
2729
2730                        for_each_cpu(i, sched_domain_span(tmp)) {
2731                                power += power_of(i);
2732                                nr_running += cpu_rq(i)->cfs.nr_running;
2733                        }
2734
2735                        capacity = DIV_ROUND_CLOSEST(power, SCHED_POWER_SCALE);
2736
2737                        if (nr_running < capacity)
2738                                want_sd = 0;
2739                }
2740
2741                /*
2742                 * If both cpu and prev_cpu are part of this domain,
2743                 * cpu is a valid SD_WAKE_AFFINE target.
2744                 */
2745                if (want_affine && (tmp->flags & SD_WAKE_AFFINE) &&
2746                    cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) {
2747                        affine_sd = tmp;
2748                        want_affine = 0;
2749                }
2750
2751                if (!want_sd && !want_affine)
2752                        break;
2753
2754                if (!(tmp->flags & sd_flag))
2755                        continue;
2756
2757                if (want_sd)
2758                        sd = tmp;
2759        }
2760
2761        if (affine_sd) {
2762                if (cpu == prev_cpu || wake_affine(affine_sd, p, sync))
2763                        prev_cpu = cpu;
2764
2765                new_cpu = select_idle_sibling(p, prev_cpu);
2766                goto unlock;
2767        }
2768
2769        while (sd) {
2770                int load_idx = sd->forkexec_idx;
2771                struct sched_group *group;
2772                int weight;
2773
2774                if (!(sd->flags & sd_flag)) {
2775                        sd = sd->child;
2776                        continue;
2777                }
2778
2779                if (sd_flag & SD_BALANCE_WAKE)
2780                        load_idx = sd->wake_idx;
2781
2782                group = find_idlest_group(sd, p, cpu, load_idx);
2783                if (!group) {
2784                        sd = sd->child;
2785                        continue;
2786                }
2787
2788                new_cpu = find_idlest_cpu(group, p, cpu);
2789                if (new_cpu == -1 || new_cpu == cpu) {
2790                        /* Now try balancing at a lower domain level of cpu */
2791                        sd = sd->child;
2792                        continue;
2793                }
2794
2795                /* Now try balancing at a lower domain level of new_cpu */
2796                cpu = new_cpu;
2797                weight = sd->span_weight;
2798                sd = NULL;
2799                for_each_domain(cpu, tmp) {
2800                        if (weight <= tmp->span_weight)
2801                                break;
2802                        if (tmp->flags & sd_flag)
2803                                sd = tmp;
2804                }
2805                /* while loop will break here if sd == NULL */
2806        }
2807unlock:
2808        rcu_read_unlock();
2809
2810        return new_cpu;
2811}
2812#endif /* CONFIG_SMP */
2813
2814static unsigned long
2815wakeup_gran(struct sched_entity *curr, struct sched_entity *se)
2816{
2817        unsigned long gran = sysctl_sched_wakeup_granularity;
2818
2819        /*
2820         * Since its curr running now, convert the gran from real-time
2821         * to virtual-time in his units.
2822         *
2823         * By using 'se' instead of 'curr' we penalize light tasks, so
2824         * they get preempted easier. That is, if 'se' < 'curr' then
2825         * the resulting gran will be larger, therefore penalizing the
2826         * lighter, if otoh 'se' > 'curr' then the resulting gran will
2827         * be smaller, again penalizing the lighter task.
2828         *
2829         * This is especially important for buddies when the leftmost
2830         * task is higher priority than the buddy.
2831         */
2832        return calc_delta_fair(gran, se);
2833}
2834
2835/*
2836 * Should 'se' preempt 'curr'.
2837 *
2838 *             |s1
2839 *        |s2
2840 *   |s3
2841 *         g
2842 *      |<--->|c
2843 *
2844 *  w(c, s1) = -1
2845 *  w(c, s2) =  0
2846 *  w(c, s3) =  1
2847 *
2848 */
2849static int
2850wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se)
2851{
2852        s64 gran, vdiff = curr->vruntime - se->vruntime;
2853
2854        if (vdiff <= 0)
2855                return -1;
2856
2857        gran = wakeup_gran(curr, se);
2858        if (vdiff > gran)
2859                return 1;
2860
2861        return 0;
2862}
2863
2864static void set_last_buddy(struct sched_entity *se)
2865{
2866        if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE))
2867                return;
2868
2869        for_each_sched_entity(se)
2870                cfs_rq_of(se)->last = se;
2871}
2872
2873static void set_next_buddy(struct sched_entity *se)
2874{
2875        if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE))
2876                return;
2877
2878        for_each_sched_entity(se)
2879                cfs_rq_of(se)->next = se;
2880}
2881
2882static void set_skip_buddy(struct sched_entity *se)
2883{
2884        for_each_sched_entity(se)
2885                cfs_rq_of(se)->skip = se;
2886}
2887
2888/*
2889 * Preempt the current task with a newly woken task if needed:
2890 */
2891static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
2892{
2893        struct task_struct *curr = rq->curr;
2894        struct sched_entity *se = &curr->se, *pse = &p->se;
2895        struct cfs_rq *cfs_rq = task_cfs_rq(curr);
2896        int scale = cfs_rq->nr_running >= sched_nr_latency;
2897        int next_buddy_marked = 0;
2898
2899        if (unlikely(se == pse))
2900                return;
2901
2902        /*
2903         * This is possible from callers such as move_task(), in which we
2904         * unconditionally check_prempt_curr() after an enqueue (which may have
2905         * lead to a throttle).  This both saves work and prevents false
2906         * next-buddy nomination below.
2907         */
2908        if (unlikely(throttled_hierarchy(cfs_rq_of(pse))))
2909                return;
2910
2911        if (sched_feat(NEXT_BUDDY) && scale && !(wake_flags & WF_FORK)) {
2912                set_next_buddy(pse);
2913                next_buddy_marked = 1;
2914        }
2915
2916        /*
2917         * We can come here with TIF_NEED_RESCHED already set from new task
2918         * wake up path.
2919         *
2920         * Note: this also catches the edge-case of curr being in a throttled
2921         * group (e.g. via set_curr_task), since update_curr() (in the
2922         * enqueue of curr) will have resulted in resched being set.  This
2923         * prevents us from potentially nominating it as a false LAST_BUDDY
2924         * below.
2925         */
2926        if (test_tsk_need_resched(curr))
2927                return;
2928
2929        /* Idle tasks are by definition preempted by non-idle tasks. */
2930        if (unlikely(curr->policy == SCHED_IDLE) &&
2931            likely(p->policy != SCHED_IDLE))
2932                goto preempt;
2933
2934        /*
2935         * Batch and idle tasks do not preempt non-idle tasks (their preemption
2936         * is driven by the tick):
2937         */
2938        if (unlikely(p->policy != SCHED_NORMAL))
2939                return;
2940
2941        find_matching_se(&se, &pse);
2942        update_curr(cfs_rq_of(se));
2943        BUG_ON(!pse);
2944        if (wakeup_preempt_entity(se, pse) == 1) {
2945                /*
2946                 * Bias pick_next to pick the sched entity that is
2947                 * triggering this preemption.
2948                 */
2949                if (!next_buddy_marked)
2950                        set_next_buddy(pse);
2951                goto preempt;
2952        }
2953
2954        return;
2955
2956preempt:
2957        resched_task(curr);
2958        /*
2959         * Only set the backward buddy when the current task is still
2960         * on the rq. This can happen when a wakeup gets interleaved
2961         * with schedule on the ->pre_schedule() or idle_balance()
2962         * point, either of which can * drop the rq lock.
2963         *
2964         * Also, during early boot the idle thread is in the fair class,
2965         * for obvious reasons its a bad idea to schedule back to it.
2966         */
2967        if (unlikely(!se->on_rq || curr == rq->idle))
2968                return;
2969
2970        if (sched_feat(LAST_BUDDY) && scale && entity_is_task(se))
2971                set_last_buddy(se);
2972}
2973
2974static struct task_struct *pick_next_task_fair(struct rq *rq)
2975{
2976        struct task_struct *p;
2977        struct cfs_rq *cfs_rq = &rq->cfs;
2978        struct sched_entity *se;
2979
2980        if (!cfs_rq->nr_running)
2981                return NULL;
2982
2983        do {
2984                se = pick_next_entity(cfs_rq);
2985                set_next_entity(cfs_rq, se);
2986                cfs_rq = group_cfs_rq(se);
2987        } while (cfs_rq);
2988
2989        p = task_of(se);
2990        if (hrtick_enabled(rq))
2991                hrtick_start_fair(rq, p);
2992
2993        return p;
2994}
2995
2996/*
2997 * Account for a descheduled task:
2998 */
2999static void put_prev_task_fair(struct rq *rq, struct task_struct *prev)
3000{
3001        struct sched_entity *se = &prev->se;
3002        struct cfs_rq *cfs_rq;
3003
3004        for_each_sched_entity(se) {
3005                cfs_rq = cfs_rq_of(se);
3006                put_prev_entity(cfs_rq, se);
3007        }
3008}
3009
3010/*
3011 * sched_yield() is very simple
3012 *
3013 * The magic of dealing with the ->skip buddy is in pick_next_entity.
3014 */
3015static void yield_task_fair(struct rq *rq)
3016{
3017        struct task_struct *curr = rq->curr;
3018        struct cfs_rq *cfs_rq = task_cfs_rq(curr);
3019        struct sched_entity *se = &curr->se;
3020
3021        /*
3022         * Are we the only task in the tree?
3023         */
3024        if (unlikely(rq->nr_running == 1))
3025                return;
3026
3027        clear_buddies(cfs_rq, se);
3028
3029        if (curr->policy != SCHED_BATCH) {
3030                update_rq_clock(rq);
3031                /*
3032                 * Update run-time statistics of the 'current'.
3033                 */
3034                update_curr(cfs_rq);
3035                /*
3036                 * Tell update_rq_clock() that we've just updated,
3037                 * so we don't do microscopic update in schedule()
3038                 * and double the fastpath cost.
3039                 */
3040                 rq->skip_clock_update = 1;
3041        }
3042
3043        set_skip_buddy(se);
3044}
3045
3046static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preempt)
3047{
3048        struct sched_entity *se = &p->se;
3049
3050        /* throttled hierarchies are not runnable */
3051        if (!se->on_rq || throttled_hierarchy(cfs_rq_of(se)))
3052                return false;
3053
3054        /* Tell the scheduler that we'd really like pse to run next. */
3055        set_next_buddy(se);
3056
3057        yield_task_fair(rq);
3058
3059        return true;
3060}
3061
3062#ifdef CONFIG_SMP
3063/**************************************************
3064 * Fair scheduling class load-balancing methods:
3065 */
3066
3067static unsigned long __read_mostly max_load_balance_interval = HZ/10;
3068
3069#define LBF_ALL_PINNED  0x01
3070#define LBF_NEED_BREAK  0x02
3071#define LBF_SOME_PINNED 0x04
3072
3073struct lb_env {
3074        struct sched_domain     *sd;
3075
3076        struct rq               *src_rq;
3077        int                     src_cpu;
3078
3079        int                     dst_cpu;
3080        struct rq               *dst_rq;
3081
3082        struct cpumask          *dst_grpmask;
3083        int                     new_dst_cpu;
3084        enum cpu_idle_type      idle;
3085        long                    imbalance;
3086        /* The set of CPUs under consideration for load-balancing */
3087        struct cpumask          *cpus;
3088
3089        unsigned int            flags;
3090
3091        unsigned int            loop;
3092        unsigned int            loop_break;
3093        unsigned int            loop_max;
3094};
3095
3096/*
3097 * move_task - move a task from one runqueue to another runqueue.
3098 * Both runqueues must be locked.
3099 */
3100static void move_task(struct task_struct *p, struct lb_env *env)
3101{
3102        deactivate_task(env->src_rq, p, 0);
3103        set_task_cpu(p, env->dst_cpu);
3104        activate_task(env->dst_rq, p, 0);
3105        check_preempt_curr(env->dst_rq, p, 0);
3106}
3107
3108/*
3109 * Is this task likely cache-hot:
3110 */
3111static int
3112task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)
3113{
3114        s64 delta;
3115
3116        if (p->sched_class != &fair_sched_class)
3117                return 0;
3118
3119        if (unlikely(p->policy == SCHED_IDLE))
3120                return 0;
3121
3122        /*
3123         * Buddy candidates are cache hot:
3124         */
3125        if (sched_feat(CACHE_HOT_BUDDY) && this_rq()->nr_running &&
3126                        (&p->se == cfs_rq_of(&p->se)->next ||
3127                         &p->se == cfs_rq_of(&p->se)->last))
3128                return 1;
3129
3130        if (sysctl_sched_migration_cost == -1)
3131                return 1;
3132        if (sysctl_sched_migration_cost == 0)
3133                return 0;
3134
3135        delta = now - p->se.exec_start;
3136
3137        return delta < (s64)sysctl_sched_migration_cost;
3138}
3139
3140/*
3141 * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
3142 */
3143static
3144int can_migrate_task(struct task_struct *p, struct lb_env *env)
3145{
3146        int tsk_cache_hot = 0;
3147        /*
3148         * We do not migrate tasks that are:
3149         * 1) running (obviously), or
3150         * 2) cannot be migrated to this CPU due to cpus_allowed, or
3151         * 3) are cache-hot on their current CPU.
3152         */
3153        if (!cpumask_test_cpu(env->dst_cpu, tsk_cpus_allowed(p))) {
3154                int new_dst_cpu;
3155
3156                schedstat_inc(p, se.statistics.nr_failed_migrations_affine);
3157
3158                /*
3159                 * Remember if this task can be migrated to any other cpu in
3160                 * our sched_group. We may want to revisit it if we couldn't
3161                 * meet load balance goals by pulling other tasks on src_cpu.
3162                 *
3163                 * Also avoid computing new_dst_cpu if we have already computed
3164                 * one in current iteration.
3165                 */
3166                if (!env->dst_grpmask || (env->flags & LBF_SOME_PINNED))
3167                        return 0;
3168
3169                new_dst_cpu = cpumask_first_and(env->dst_grpmask,
3170                                                tsk_cpus_allowed(p));
3171                if (new_dst_cpu < nr_cpu_ids) {
3172                        env->flags |= LBF_SOME_PINNED;
3173                        env->new_dst_cpu = new_dst_cpu;
3174                }
3175                return 0;
3176        }
3177
3178        /* Record that we found atleast one task that could run on dst_cpu */
3179        env->flags &= ~LBF_ALL_PINNED;
3180
3181        if (task_running(env->src_rq, p)) {
3182                schedstat_inc(p, se.statistics.nr_failed_migrations_running);
3183                return 0;
3184        }
3185
3186        /*
3187         * Aggressive migration if:
3188         * 1) task is cache cold, or
3189         * 2) too many balance attempts have failed.
3190         */
3191
3192        tsk_cache_hot = task_hot(p, env->src_rq->clock_task, env->sd);
3193        if (!tsk_cache_hot ||
3194                env->sd->nr_balance_failed > env->sd->cache_nice_tries) {
3195#ifdef CONFIG_SCHEDSTATS
3196                if (tsk_cache_hot) {
3197                        schedstat_inc(env->sd, lb_hot_gained[env->idle]);
3198                        schedstat_inc(p, se.statistics.nr_forced_migrations);
3199                }
3200#endif
3201                return 1;
3202        }
3203
3204        if (tsk_cache_hot) {
3205                schedstat_inc(p, se.statistics.nr_failed_migrations_hot);
3206                return 0;
3207        }
3208        return 1;
3209}
3210
3211/*
3212 * move_one_task tries to move exactly one task from busiest to this_rq, as
3213 * part of active balancing operations within "domain".
3214 * Returns 1 if successful and 0 otherwise.
3215 *
3216 * Called with both runqueues locked.
3217 */
3218static int move_one_task(struct lb_env *env)
3219{
3220        struct task_struct *p, *n;
3221
3222        list_for_each_entry_safe(p, n, &env->src_rq->cfs_tasks, se.group_node) {
3223                if (throttled_lb_pair(task_group(p), env->src_rq->cpu, env->dst_cpu))
3224                        continue;
3225
3226                if (!can_migrate_task(p, env))
3227                        continue;
3228
3229                move_task(p, env);
3230                /*
3231                 * Right now, this is only the second place move_task()
3232                 * is called, so we can safely collect move_task()
3233                 * stats here rather than inside move_task().
3234                 */
3235                schedstat_inc(env->sd, lb_gained[env->idle]);
3236                return 1;
3237        }
3238        return 0;
3239}
3240
3241static unsigned long task_h_load(struct task_struct *p);
3242
3243static const unsigned int sched_nr_migrate_break = 32;
3244
3245/*
3246 * move_tasks tries to move up to imbalance weighted load from busiest to
3247 * this_rq, as part of a balancing operation within domain "sd".
3248 * Returns 1 if successful and 0 otherwise.
3249 *
3250 * Called with both runqueues locked.
3251 */
3252static int move_tasks(struct lb_env *env)
3253{
3254        struct list_head *tasks = &env->src_rq->cfs_tasks;
3255        struct task_struct *p;
3256        unsigned long load;
3257        int pulled = 0;
3258
3259        if (env->imbalance <= 0)
3260                return 0;
3261
3262        while (!list_empty(tasks)) {
3263                p = list_first_entry(tasks, struct task_struct, se.group_node);
3264
3265                env->loop++;
3266                /* We've more or less seen every task there is, call it quits */
3267                if (env->loop > env->loop_max)
3268                        break;
3269
3270                /* take a breather every nr_migrate tasks */
3271                if (env->loop > env->loop_break) {
3272                        env->loop_break += sched_nr_migrate_break;
3273                        env->flags |= LBF_NEED_BREAK;
3274                        break;
3275                }
3276
3277                if (throttled_lb_pair(task_group(p), env->src_cpu, env->dst_cpu))
3278                        goto next;
3279
3280                load = task_h_load(p);
3281
3282                if (sched_feat(LB_MIN) && load < 16 && !env->sd->nr_balance_failed)
3283                        goto next;
3284
3285                if ((load / 2) > env->imbalance)
3286                        goto next;
3287
3288                if (!can_migrate_task(p, env))
3289                        goto next;
3290
3291                move_task(p, env);
3292                pulled++;
3293                env->imbalance -= load;
3294
3295#ifdef CONFIG_PREEMPT
3296                /*
3297                 * NEWIDLE balancing is a source of latency, so preemptible
3298                 * kernels will stop after the first task is pulled to minimize
3299                 * the critical section.
3300                 */
3301                if (env->idle == CPU_NEWLY_IDLE)
3302                        break;
3303#endif
3304
3305                /*
3306                 * We only want to steal up to the prescribed amount of
3307                 * weighted load.
3308                 */
3309                if (env->imbalance <= 0)
3310                        break;
3311
3312                continue;
3313next:
3314                list_move_tail(&p->se.group_node, tasks);
3315        }
3316
3317        /*
3318         * Right now, this is one of only two places move_task() is called,
3319         * so we can safely collect move_task() stats here rather than
3320         * inside move_task().
3321         */
3322        schedstat_add(env->sd, lb_gained[env->idle], pulled);
3323
3324        return pulled;
3325}
3326
3327#ifdef CONFIG_FAIR_GROUP_SCHED
3328/*
3329 * update tg->load_weight by folding this cpu's load_avg
3330 */
3331static int update_shares_cpu(struct task_group *tg, int cpu)
3332{
3333        struct cfs_rq *cfs_rq;
3334        unsigned long flags;
3335        struct rq *rq;
3336
3337        if (!tg->se[cpu])
3338                return 0;
3339
3340        rq = cpu_rq(cpu);
3341        cfs_rq = tg->cfs_rq[cpu];
3342
3343        raw_spin_lock_irqsave(&rq->lock, flags);
3344
3345        update_rq_clock(rq);
3346        update_cfs_load(cfs_rq, 1);
3347
3348        /*
3349         * We need to update shares after updating tg->load_weight in
3350         * order to adjust the weight of groups with long running tasks.
3351         */
3352        update_cfs_shares(cfs_rq);
3353
3354        raw_spin_unlock_irqrestore(&rq->lock, flags);
3355
3356        return 0;
3357}
3358
3359static void update_shares(int cpu)
3360{
3361        struct cfs_rq *cfs_rq;
3362        struct rq *rq = cpu_rq(cpu);
3363
3364        rcu_read_lock();
3365        /*
3366         * Iterates the task_group tree in a bottom up fashion, see
3367         * list_add_leaf_cfs_rq() for details.
3368         */
3369        for_each_leaf_cfs_rq(rq, cfs_rq) {
3370                /* throttled entities do not contribute to load */
3371                if (throttled_hierarchy(cfs_rq))
3372                        continue;
3373
3374                update_shares_cpu(cfs_rq->tg, cpu);
3375        }
3376        rcu_read_unlock();
3377}
3378
3379/*
3380 * Compute the cpu's hierarchical load factor for each task group.
3381 * This needs to be done in a top-down fashion because the load of a child
3382 * group is a fraction of its parents load.
3383 */
3384static int tg_load_down(struct task_group *tg, void *data)
3385{
3386        unsigned long load;
3387        long cpu = (long)data;
3388
3389        if (!tg->parent) {
3390                load = cpu_rq(cpu)->load.weight;
3391        } else {
3392                load = tg->parent->cfs_rq[cpu]->h_load;
3393                load *= tg->se[cpu]->load.weight;
3394                load /= tg->parent->cfs_rq[cpu]->load.weight + 1;
3395        }
3396
3397        tg->cfs_rq[cpu]->h_load = load;
3398
3399        return 0;
3400}
3401
3402static void update_h_load(long cpu)
3403{
3404        struct rq *rq = cpu_rq(cpu);
3405        unsigned long now = jiffies;
3406
3407        if (rq->h_load_throttle == now)
3408                return;
3409
3410        rq->h_load_throttle = now;
3411
3412        rcu_read_lock();
3413        walk_tg_tree(tg_load_down, tg_nop, (void *)cpu);
3414        rcu_read_unlock();
3415}
3416
3417static unsigned long task_h_load(struct task_struct *p)
3418{
3419        struct cfs_rq *cfs_rq = task_cfs_rq(p);
3420        unsigned long load;
3421
3422        load = p->se.load.weight;
3423        load = div_u64(load * cfs_rq->h_load, cfs_rq->load.weight + 1);
3424
3425        return load;
3426}
3427#else
3428static inline void update_shares(int cpu)
3429{
3430}
3431
3432static inline void update_h_load(long cpu)
3433{
3434}
3435
3436static unsigned long task_h_load(struct task_struct *p)
3437{
3438        return p->se.load.weight;
3439}
3440#endif
3441
3442/********** Helpers for find_busiest_group ************************/
3443/*
3444 * sd_lb_stats - Structure to store the statistics of a sched_domain
3445 *              during load balancing.
3446 */
3447struct sd_lb_stats {
3448        struct sched_group *busiest; /* Busiest group in this sd */
3449        struct sched_group *this;  /* Local group in this sd */
3450        unsigned long total_load;  /* Total load of all groups in sd */
3451        unsigned long total_pwr;   /*   Total power of all groups in sd */
3452        unsigned long avg_load;    /* Average load across all groups in sd */
3453
3454        /** Statistics of this group */
3455        unsigned long this_load;
3456        unsigned long this_load_per_task;
3457        unsigned long this_nr_running;
3458        unsigned long this_has_capacity;
3459        unsigned int  this_idle_cpus;
3460
3461        /* Statistics of the busiest group */
3462        unsigned int  busiest_idle_cpus;
3463        unsigned long max_load;
3464        unsigned long busiest_load_per_task;
3465        unsigned long busiest_nr_running;
3466        unsigned long busiest_group_capacity;
3467        unsigned long busiest_has_capacity;
3468        unsigned int  busiest_group_weight;
3469
3470        int group_imb; /* Is there imbalance in this sd */
3471};
3472
3473/*
3474 * sg_lb_stats - stats of a sched_group required for load_balancing
3475 */
3476struct sg_lb_stats {
3477        unsigned long avg_load; /*Avg load across the CPUs of the group */
3478        unsigned long group_load; /* Total load over the CPUs of the group */
3479        unsigned long sum_nr_running; /* Nr tasks running in the group */
3480        unsigned long sum_weighted_load; /* Weighted load of group's tasks */
3481        unsigned long group_capacity;
3482        unsigned long idle_cpus;
3483        unsigned long group_weight;
3484        int group_imb; /* Is there an imbalance in the group ? */
3485        int group_has_capacity; /* Is there extra capacity in the group? */
3486};
3487
3488/**
3489 * get_sd_load_idx - Obtain the load index for a given sched domain.
3490 * @sd: The sched_domain whose load_idx is to be obtained.
3491 * @idle: The Idle status of the CPU for whose sd load_icx is obtained.
3492 */
3493static inline int get_sd_load_idx(struct sched_domain *sd,
3494                                        enum cpu_idle_type idle)
3495{
3496        int load_idx;
3497
3498        switch (idle) {
3499        case CPU_NOT_IDLE:
3500                load_idx = sd->busy_idx;
3501                break;
3502
3503        case CPU_NEWLY_IDLE:
3504                load_idx = sd->newidle_idx;
3505                break;
3506        default:
3507                load_idx = sd->idle_idx;
3508                break;
3509        }
3510
3511        return load_idx;
3512}
3513
3514unsigned long default_scale_freq_power(struct sched_domain *sd, int cpu)
3515{
3516        return SCHED_POWER_SCALE;
3517}
3518
3519unsigned long __weak arch_scale_freq_power(struct sched_domain *sd, int cpu)
3520{
3521        return default_scale_freq_power(sd, cpu);
3522}
3523
3524unsigned long default_scale_smt_power(struct sched_domain *sd, int cpu)
3525{
3526        unsigned long weight = sd->span_weight;
3527        unsigned long smt_gain = sd->smt_gain;
3528
3529        smt_gain /= weight;
3530
3531        return smt_gain;
3532}
3533
3534unsigned long __weak arch_scale_smt_power(struct sched_domain *sd, int cpu)
3535{
3536        return default_scale_smt_power(sd, cpu);
3537}
3538
3539unsigned long scale_rt_power(int cpu)
3540{
3541        struct rq *rq = cpu_rq(cpu);
3542        u64 total, available, age_stamp, avg;
3543
3544        /*
3545         * Since we're reading these variables without serialization make sure
3546         * we read them once before doing sanity checks on them.
3547         */
3548        age_stamp = ACCESS_ONCE(rq->age_stamp);
3549        avg = ACCESS_ONCE(rq->rt_avg);
3550
3551        total = sched_avg_period() + (rq->clock - age_stamp);
3552
3553        if (unlikely(total < avg)) {
3554                /* Ensures that power won't end up being negative */
3555                available = 0;
3556        } else {
3557                available = total - avg;
3558        }
3559
3560        if (unlikely((s64)total < SCHED_POWER_SCALE))
3561                total = SCHED_POWER_SCALE;
3562
3563        total >>= SCHED_POWER_SHIFT;
3564
3565        return div_u64(available, total);
3566}
3567
3568static void update_cpu_power(struct sched_domain *sd, int cpu)
3569{
3570        unsigned long weight = sd->span_weight;
3571        unsigned long power = SCHED_POWER_SCALE;
3572        struct sched_group *sdg = sd->groups;
3573
3574        if ((sd->flags & SD_SHARE_CPUPOWER) && weight > 1) {
3575                if (sched_feat(ARCH_POWER))
3576                        power *= arch_scale_smt_power(sd, cpu);
3577                else
3578                        power *= default_scale_smt_power(sd, cpu);
3579
3580                power >>= SCHED_POWER_SHIFT;
3581        }
3582
3583        sdg->sgp->power_orig = power;
3584
3585        if (sched_feat(ARCH_POWER))
3586                power *= arch_scale_freq_power(sd, cpu);
3587        else
3588                power *= default_scale_freq_power(sd, cpu);
3589
3590        power >>= SCHED_POWER_SHIFT;
3591
3592        power *= scale_rt_power(cpu);
3593        power >>= SCHED_POWER_SHIFT;
3594
3595        if (!power)
3596                power = 1;
3597
3598        cpu_rq(cpu)->cpu_power = power;
3599        sdg->sgp->power = power;
3600}
3601
3602void update_group_power(struct sched_domain *sd, int cpu)
3603{
3604        struct sched_domain *child = sd->child;
3605        struct sched_group *group, *sdg = sd->groups;
3606        unsigned long power;
3607        unsigned long interval;
3608
3609        interval = msecs_to_jiffies(sd->balance_interval);
3610        interval = clamp(interval, 1UL, max_load_balance_interval);
3611        sdg->sgp->next_update = jiffies + interval;
3612
3613        if (!child) {
3614                update_cpu_power(sd, cpu);
3615                return;
3616        }
3617
3618        power = 0;
3619
3620        if (child->flags & SD_OVERLAP) {
3621                /*
3622                 * SD_OVERLAP domains cannot assume that child groups
3623                 * span the current group.
3624                 */
3625
3626                for_each_cpu(cpu, sched_group_cpus(sdg))
3627                        power += power_of(cpu);
3628        } else  {
3629                /*
3630                 * !SD_OVERLAP domains can assume that child groups
3631                 * span the current group.
3632                 */ 
3633
3634                group = child->groups;
3635                do {
3636                        power += group->sgp->power;
3637                        group = group->next;
3638                } while (group != child->groups);
3639        }
3640
3641        sdg->sgp->power_orig = sdg->sgp->power = power;
3642}
3643
3644/*
3645 * Try and fix up capacity for tiny siblings, this is needed when
3646 * things like SD_ASYM_PACKING need f_b_g to select another sibling
3647 * which on its own isn't powerful enough.
3648 *
3649 * See update_sd_pick_busiest() and check_asym_packing().
3650 */
3651static inline int
3652fix_small_capacity(struct sched_domain *sd, struct sched_group *group)
3653{
3654        /*
3655         * Only siblings can have significantly less than SCHED_POWER_SCALE
3656         */
3657        if (!(sd->flags & SD_SHARE_CPUPOWER))
3658                return 0;
3659
3660        /*
3661         * If ~90% of the cpu_power is still there, we're good.
3662         */
3663        if (group->sgp->power * 32 > group->sgp->power_orig * 29)
3664                return 1;
3665
3666        return 0;
3667}
3668
3669/**
3670 * update_sg_lb_stats - Update sched_group's statistics for load balancing.
3671 * @env: The load balancing environment.
3672 * @group: sched_group whose statistics are to be updated.
3673 * @load_idx: Load index of sched_domain of this_cpu for load calc.
3674 * @local_group: Does group contain this_cpu.
3675 * @balance: Should we balance.
3676 * @sgs: variable to hold the statistics for this group.
3677 */
3678static inline void update_sg_lb_stats(struct lb_env *env,
3679                        struct sched_group *group, int load_idx,
3680                        int local_group, int *balance, struct sg_lb_stats *sgs)
3681{
3682        unsigned long nr_running, max_nr_running, min_nr_running;
3683        unsigned long load, max_cpu_load, min_cpu_load;
3684        unsigned int balance_cpu = -1, first_idle_cpu = 0;
3685        unsigned long avg_load_per_task = 0;
3686        int i;
3687
3688        if (local_group)
3689                balance_cpu = group_balance_cpu(group);
3690
3691        /* Tally up the load of all CPUs in the group */
3692        max_cpu_load = 0;
3693        min_cpu_load = ~0UL;
3694        max_nr_running = 0;
3695        min_nr_running = ~0UL;
3696
3697        for_each_cpu_and(i, sched_group_cpus(group), env->cpus) {
3698                struct rq *rq = cpu_rq(i);
3699
3700                nr_running = rq->nr_running;
3701
3702                /* Bias balancing toward cpus of our domain */
3703                if (local_group) {
3704                        if (idle_cpu(i) && !first_idle_cpu &&
3705                                        cpumask_test_cpu(i, sched_group_mask(group))) {
3706                                first_idle_cpu = 1;
3707                                balance_cpu = i;
3708                        }
3709
3710                        load = target_load(i, load_idx);
3711                } else {
3712                        load = source_load(i, load_idx);
3713                        if (load > max_cpu_load)
3714                                max_cpu_load = load;
3715                        if (min_cpu_load > load)
3716                                min_cpu_load = load;
3717
3718                        if (nr_running > max_nr_running)
3719                                max_nr_running = nr_running;
3720                        if (min_nr_running > nr_running)
3721                                min_nr_running = nr_running;
3722                }
3723
3724                sgs->group_load += load;
3725                sgs->sum_nr_running += nr_running;
3726                sgs->sum_weighted_load += weighted_cpuload(i);
3727                if (idle_cpu(i))
3728                        sgs->idle_cpus++;
3729        }
3730
3731        /*
3732         * First idle cpu or the first cpu(busiest) in this sched group
3733         * is eligible for doing load balancing at this and above
3734         * domains. In the newly idle case, we will allow all the cpu's
3735         * to do the newly idle load balance.
3736         */
3737        if (local_group) {
3738                if (env->idle != CPU_NEWLY_IDLE) {
3739                        if (balance_cpu != env->dst_cpu) {
3740                                *balance = 0;
3741                                return;
3742                        }
3743                        update_group_power(env->sd, env->dst_cpu);
3744                } else if (time_after_eq(jiffies, group->sgp->next_update))
3745                        update_group_power(env->sd, env->dst_cpu);
3746        }
3747
3748        /* Adjust by relative CPU power of the group */
3749        sgs->avg_load = (sgs->group_load*SCHED_POWER_SCALE) / group->sgp->power;
3750
3751        /*
3752         * Consider the group unbalanced when the imbalance is larger
3753         * than the average weight of a task.
3754         *
3755         * APZ: with cgroup the avg task weight can vary wildly and
3756         *      might not be a suitable number - should we keep a
3757         *      normalized nr_running number somewhere that negates
3758         *      the hierarchy?
3759         */
3760        if (sgs->sum_nr_running)
3761                avg_load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running;
3762
3763        if ((max_cpu_load - min_cpu_load) >= avg_load_per_task &&
3764            (max_nr_running - min_nr_running) > 1)
3765                sgs->group_imb = 1;
3766
3767        sgs->group_capacity = DIV_ROUND_CLOSEST(group->sgp->power,
3768                                                SCHED_POWER_SCALE);
3769        if (!sgs->group_capacity)
3770                sgs->group_capacity = fix_small_capacity(env->sd, group);
3771        sgs->group_weight = group->group_weight;
3772
3773        if (sgs->group_capacity > sgs->sum_nr_running)
3774                sgs->group_has_capacity = 1;
3775}
3776
3777/**
3778 * update_sd_pick_busiest - return 1 on busiest group
3779 * @env: The load balancing environment.
3780 * @sds: sched_domain statistics
3781 * @sg: sched_group candidate to be checked for being the busiest
3782 * @sgs: sched_group statistics
3783 *
3784 * Determine if @sg is a busier group than the previously selected
3785 * busiest group.
3786 */
3787static bool update_sd_pick_busiest(struct lb_env *env,
3788                                   struct sd_lb_stats *sds,
3789                                   struct sched_group *sg,
3790                                   struct sg_lb_stats *sgs)
3791{
3792        if (sgs->avg_load <= sds->max_load)
3793                return false;
3794
3795        if (sgs->sum_nr_running > sgs->group_capacity)
3796                return true;
3797
3798        if (sgs->group_imb)
3799                return true;
3800
3801        /*
3802         * ASYM_PACKING needs to move all the work to the lowest
3803         * numbered CPUs in the group, therefore mark all groups
3804         * higher than ourself as busy.
3805         */
3806        if ((env->sd->flags & SD_ASYM_PACKING) && sgs->sum_nr_running &&
3807            env->dst_cpu < group_first_cpu(sg)) {
3808                if (!sds->busiest)
3809                        return true;
3810
3811                if (group_first_cpu(sds->busiest) > group_first_cpu(sg))
3812                        return true;
3813        }
3814
3815        return false;
3816}
3817
3818/**
3819 * update_sd_lb_stats - Update sched_domain's statistics for load balancing.
3820 * @env: The load balancing environment.
3821 * @balance: Should we balance.
3822 * @sds: variable to hold the statistics for this sched_domain.
3823 */
3824static inline void update_sd_lb_stats(struct lb_env *env,
3825                                        int *balance, struct sd_lb_stats *sds)
3826{
3827        struct sched_domain *child = env->sd->child;
3828        struct sched_group *sg = env->sd->groups;
3829        struct sg_lb_stats sgs;
3830        int load_idx, prefer_sibling = 0;
3831
3832        if (child && child->flags & SD_PREFER_SIBLING)
3833                prefer_sibling = 1;
3834
3835        load_idx = get_sd_load_idx(env->sd, env->idle);
3836
3837        do {
3838                int local_group;
3839
3840                local_group = cpumask_test_cpu(env->dst_cpu, sched_group_cpus(sg));
3841                memset(&sgs, 0, sizeof(sgs));
3842                update_sg_lb_stats(env, sg, load_idx, local_group, balance, &sgs);
3843
3844                if (local_group && !(*balance))
3845                        return;
3846
3847                sds->total_load += sgs.group_load;
3848                sds->total_pwr += sg->sgp->power;
3849
3850                /*
3851                 * In case the child domain prefers tasks go to siblings
3852                 * first, lower the sg capacity to one so that we'll try
3853                 * and move all the excess tasks away. We lower the capacity
3854                 * of a group only if the local group has the capacity to fit
3855                 * these excess tasks, i.e. nr_running < group_capacity. The
3856                 * extra check prevents the case where you always pull from the
3857                 * heaviest group when it is already under-utilized (possible
3858                 * with a large weight task outweighs the tasks on the system).
3859                 */
3860                if (prefer_sibling && !local_group && sds->this_has_capacity)
3861                        sgs.group_capacity = min(sgs.group_capacity, 1UL);
3862
3863                if (local_group) {
3864                        sds->this_load = sgs.avg_load;
3865                        sds->this = sg;
3866                        sds->this_nr_running = sgs.sum_nr_running;
3867                        sds->this_load_per_task = sgs.sum_weighted_load;
3868                        sds->this_has_capacity = sgs.group_has_capacity;
3869                        sds->this_idle_cpus = sgs.idle_cpus;
3870                } else if (update_sd_pick_busiest(env, sds, sg, &sgs)) {
3871                        sds->max_load = sgs.avg_load;
3872                        sds->busiest = sg;
3873                        sds->busiest_nr_running = sgs.sum_nr_running;
3874                        sds->busiest_idle_cpus = sgs.idle_cpus;
3875                        sds->busiest_group_capacity = sgs.group_capacity;
3876                        sds->busiest_load_per_task = sgs.sum_weighted_load;
3877                        sds->busiest_has_capacity = sgs.group_has_capacity;
3878                        sds->busiest_group_weight = sgs.group_weight;
3879                        sds->group_imb = sgs.group_imb;
3880                }
3881
3882                sg = sg->next;
3883        } while (sg != env->sd->groups);
3884}
3885
3886/**
3887 * check_asym_packing - Check to see if the group is packed into the
3888 *                      sched doman.
3889 *
3890 * This is primarily intended to used at the sibling level.  Some
3891 * cores like POWER7 prefer to use lower numbered SMT threads.  In the
3892 * case of POWER7, it can move to lower SMT modes only when higher
3893 * threads are idle.  When in lower SMT modes, the threads will
3894 * perform better since they share less core resources.  Hence when we
3895 * have idle threads, we want them to be the higher ones.
3896 *
3897 * This packing function is run on idle threads.  It checks to see if
3898 * the busiest CPU in this domain (core in the P7 case) has a higher
3899 * CPU number than the packing function is being run on.  Here we are
3900 * assuming lower CPU number will be equivalent to lower a SMT thread
3901 * number.
3902 *
3903 * Returns 1 when packing is required and a task should be moved to
3904 * this CPU.  The amount of the imbalance is returned in *imbalance.
3905 *
3906 * @env: The load balancing environment.
3907 * @sds: Statistics of the sched_domain which is to be packed
3908 */
3909static int check_asym_packing(struct lb_env *env, struct sd_lb_stats *sds)
3910{
3911        int busiest_cpu;
3912
3913        if (!(env->sd->flags & SD_ASYM_PACKING))
3914                return 0;
3915
3916        if (!sds->busiest)
3917                return 0;
3918
3919        busiest_cpu = group_first_cpu(sds->busiest);
3920        if (env->dst_cpu > busiest_cpu)
3921                return 0;
3922
3923        env->imbalance = DIV_ROUND_CLOSEST(
3924                sds->max_load * sds->busiest->sgp->power, SCHED_POWER_SCALE);
3925
3926        return 1;
3927}
3928
3929/**
3930 * fix_small_imbalance - Calculate the minor imbalance that exists
3931 *                      amongst the groups of a sched_domain, during
3932 *                      load balancing.
3933 * @env: The load balancing environment.
3934 * @sds: Statistics of the sched_domain whose imbalance is to be calculated.
3935 */
3936static inline
3937void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
3938{
3939        unsigned long tmp, pwr_now = 0, pwr_move = 0;
3940        unsigned int imbn = 2;
3941        unsigned long scaled_busy_load_per_task;
3942
3943        if (sds->this_nr_running) {
3944                sds->this_load_per_task /= sds->this_nr_running;
3945                if (sds->busiest_load_per_task >
3946                                sds->this_load_per_task)
3947                        imbn = 1;
3948        } else {
3949                sds->this_load_per_task =
3950                        cpu_avg_load_per_task(env->dst_cpu);
3951        }
3952
3953        scaled_busy_load_per_task = sds->busiest_load_per_task
3954                                         * SCHED_POWER_SCALE;
3955        scaled_busy_load_per_task /= sds->busiest->sgp->power;
3956
3957        if (sds->max_load - sds->this_load + scaled_busy_load_per_task >=
3958                        (scaled_busy_load_per_task * imbn)) {
3959                env->imbalance = sds->busiest_load_per_task;
3960                return;
3961        }
3962
3963        /*
3964         * OK, we don't have enough imbalance to justify moving tasks,
3965         * however we may be able to increase total CPU power used by
3966         * moving them.
3967         */
3968
3969        pwr_now += sds->busiest->sgp->power *
3970                        min(sds->busiest_load_per_task, sds->max_load);
3971        pwr_now += sds->this->sgp->power *
3972                        min(sds->this_load_per_task, sds->this_load);
3973        pwr_now /= SCHED_POWER_SCALE;
3974
3975        /* Amount of load we'd subtract */
3976        tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) /
3977                sds->busiest->sgp->power;
3978        if (sds->max_load > tmp)
3979                pwr_move += sds->busiest->sgp->power *
3980                        min(sds->busiest_load_per_task, sds->max_load - tmp);
3981
3982        /* Amount of load we'd add */
3983        if (sds->max_load * sds->busiest->sgp->power <
3984                sds->busiest_load_per_task * SCHED_POWER_SCALE)
3985                tmp = (sds->max_load * sds->busiest->sgp->power) /
3986                        sds->this->sgp->power;
3987        else
3988                tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) /
3989                        sds->this->sgp->power;
3990        pwr_move += sds->this->sgp->power *
3991                        min(sds->this_load_per_task, sds->this_load + tmp);
3992        pwr_move /= SCHED_POWER_SCALE;
3993
3994        /* Move if we gain throughput */
3995        if (pwr_move > pwr_now)
3996                env->imbalance = sds->busiest_load_per_task;
3997}
3998
3999/**
4000 * calculate_imbalance - Calculate the amount of imbalance present within the
4001 *                       groups of a given sched_domain during load balance.
4002 * @env: load balance environment
4003 * @sds: statistics of the sched_domain whose imbalance is to be calculated.
4004 */
4005static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
4006{
4007        unsigned long max_pull, load_above_capacity = ~0UL;
4008
4009        sds->busiest_load_per_task /= sds->busiest_nr_running;
4010        if (sds->group_imb) {
4011                sds->busiest_load_per_task =
4012                        min(sds->busiest_load_per_task, sds->avg_load);
4013        }
4014
4015        /*
4016         * In the presence of smp nice balancing, certain scenarios can have
4017         * max load less than avg load(as we skip the groups at or below
4018         * its cpu_power, while calculating max_load..)
4019         */
4020        if (sds->max_load < sds->avg_load) {
4021                env->imbalance = 0;
4022                return fix_small_imbalance(env, sds);
4023        }
4024
4025        if (!sds->group_imb) {
4026                /*
4027                 * Don't want to pull so many tasks that a group would go idle.
4028                 */
4029                load_above_capacity = (sds->busiest_nr_running -
4030                                                sds->busiest_group_capacity);
4031
4032                load_above_capacity *= (SCHED_LOAD_SCALE * SCHED_POWER_SCALE);
4033
4034                load_above_capacity /= sds->busiest->sgp->power;
4035        }
4036
4037        /*
4038         * We're trying to get all the cpus to the average_load, so we don't
4039         * want to push ourselves above the average load, nor do we wish to
4040         * reduce the max loaded cpu below the average load. At the same time,
4041         * we also don't want to reduce the group load below the group capacity
4042         * (so that we can implement power-savings policies etc). Thus we look
4043         * for the minimum possible imbalance.
4044         * Be careful of negative numbers as they'll appear as very large values
4045         * with unsigned longs.
4046         */
4047        max_pull = min(sds->max_load - sds->avg_load, load_above_capacity);
4048
4049        /* How much load to actually move to equalise the imbalance */
4050        env->imbalance = min(max_pull * sds->busiest->sgp->power,
4051                (sds->avg_load - sds->this_load) * sds->this->sgp->power)
4052                        / SCHED_POWER_SCALE;
4053
4054        /*
4055         * if *imbalance is less than the average load per runnable task
4056         * there is no guarantee that any tasks will be moved so we'll have
4057         * a think about bumping its value to force at least one task to be
4058         * moved
4059         */
4060        if (env->imbalance < sds->busiest_load_per_task)
4061                return fix_small_imbalance(env, sds);
4062
4063}
4064
4065/******* find_busiest_group() helpers end here *********************/
4066
4067/**
4068 * find_busiest_group - Returns the busiest group within the sched_domain
4069 * if there is an imbalance. If there isn't an imbalance, and
4070 * the user has opted for power-savings, it returns a group whose
4071 * CPUs can be put to idle by rebalancing those tasks elsewhere, if
4072 * such a group exists.
4073 *
4074 * Also calculates the amount of weighted load which should be moved
4075 * to restore balance.
4076 *
4077 * @env: The load balancing environment.
4078 * @balance: Pointer to a variable indicating if this_cpu
4079 *      is the appropriate cpu to perform load balancing at this_level.
4080 *
4081 * Returns:     - the busiest group if imbalance exists.
4082 *              - If no imbalance and user has opted for power-savings balance,
4083 *                 return the least loaded group whose CPUs can be
4084 *                 put to idle by rebalancing its tasks onto our group.
4085 */
4086static struct sched_group *
4087find_busiest_group(struct lb_env *env, int *balance)
4088{
4089        struct sd_lb_stats sds;
4090
4091        memset(&sds, 0, sizeof(sds));
4092
4093        /*
4094         * Compute the various statistics relavent for load balancing at
4095         * this level.
4096         */
4097        update_sd_lb_stats(env, balance, &sds);
4098
4099        /*
4100         * this_cpu is not the appropriate cpu to perform load balancing at
4101         * this level.
4102         */
4103        if (!(*balance))
4104                goto ret;
4105
4106        if ((env->idle == CPU_IDLE || env->idle == CPU_NEWLY_IDLE) &&
4107            check_asym_packing(env, &sds))
4108                return sds.busiest;
4109
4110        /* There is no busy sibling group to pull tasks from */
4111        if (!sds.busiest || sds.busiest_nr_running == 0)
4112                goto out_balanced;
4113
4114        sds.avg_load = (SCHED_POWER_SCALE * sds.total_load) / sds.total_pwr;
4115
4116        /*
4117         * If the busiest group is imbalanced the below checks don't
4118         * work because they assumes all things are equal, which typically
4119         * isn't true due to cpus_allowed constraints and the like.
4120         */
4121        if (sds.group_imb)
4122                goto force_balance;
4123
4124        /* SD_BALANCE_NEWIDLE trumps SMP nice when underutilized */
4125        if (env->idle == CPU_NEWLY_IDLE && sds.this_has_capacity &&
4126                        !sds.busiest_has_capacity)
4127                goto force_balance;
4128
4129        /*
4130         * If the local group is more busy than the selected busiest group
4131         * don't try and pull any tasks.
4132         */
4133        if (sds.this_load >= sds.max_load)
4134                goto out_balanced;
4135
4136        /*
4137         * Don't pull any tasks if this group is already above the domain
4138         * average load.
4139         */
4140        if (sds.this_load >= sds.avg_load)
4141                goto out_balanced;
4142
4143        if (env->idle == CPU_IDLE) {
4144                /*
4145                 * This cpu is idle. If the busiest group load doesn't
4146                 * have more tasks than the number of available cpu's and
4147                 * there is no imbalance between this and busiest group
4148                 * wrt to idle cpu's, it is balanced.
4149                 */
4150                if ((sds.this_idle_cpus <= sds.busiest_idle_cpus + 1) &&
4151                    sds.busiest_nr_running <= sds.busiest_group_weight)
4152                        goto out_balanced;
4153        } else {
4154                /*
4155                 * In the CPU_NEWLY_IDLE, CPU_NOT_IDLE cases, use
4156                 * imbalance_pct to be conservative.
4157                 */
4158                if (100 * sds.max_load <= env->sd->imbalance_pct * sds.this_load)
4159                        goto out_balanced;
4160        }
4161
4162force_balance:
4163        /* Looks like there is an imbalance. Compute it */
4164        calculate_imbalance(env, &sds);
4165        return sds.busiest;
4166
4167out_balanced:
4168ret:
4169        env->imbalance = 0;
4170        return NULL;
4171}
4172
4173/*
4174 * find_busiest_queue - find the busiest runqueue among the cpus in group.
4175 */
4176static struct rq *find_busiest_queue(struct lb_env *env,
4177                                     struct sched_group *group)
4178{
4179        struct rq *busiest = NULL, *rq;
4180        unsigned long max_load = 0;
4181        int i;
4182
4183        for_each_cpu(i, sched_group_cpus(group)) {
4184                unsigned long power = power_of(i);
4185                unsigned long capacity = DIV_ROUND_CLOSEST(power,
4186                                                           SCHED_POWER_SCALE);
4187                unsigned long wl;
4188
4189                if (!capacity)
4190                        capacity = fix_small_capacity(env->sd, group);
4191
4192                if (!cpumask_test_cpu(i, env->cpus))
4193                        continue;
4194
4195                rq = cpu_rq(i);
4196                wl = weighted_cpuload(i);
4197
4198                /*
4199                 * When comparing with imbalance, use weighted_cpuload()
4200                 * which is not scaled with the cpu power.
4201                 */
4202                if (capacity && rq->nr_running == 1 && wl > env->imbalance)
4203                        continue;
4204
4205                /*
4206                 * For the load comparisons with the other cpu's, consider
4207                 * the weighted_cpuload() scaled with the cpu power, so that
4208                 * the load can be moved away from the cpu that is potentially
4209                 * running at a lower capacity.
4210                 */
4211                wl = (wl * SCHED_POWER_SCALE) / power;
4212
4213                if (wl > max_load) {
4214                        max_load = wl;
4215                        busiest = rq;
4216                }
4217        }
4218
4219        return busiest;
4220}
4221
4222/*
4223 * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
4224 * so long as it is large enough.
4225 */
4226#define MAX_PINNED_INTERVAL     512
4227
4228/* Working cpumask for load_balance and load_balance_newidle. */
4229DEFINE_PER_CPU(cpumask_var_t, load_balance_tmpmask);
4230
4231static int need_active_balance(struct lb_env *env)
4232{
4233        struct sched_domain *sd = env->sd;
4234
4235        if (env->idle == CPU_NEWLY_IDLE) {
4236
4237                /*
4238                 * ASYM_PACKING needs to force migrate tasks from busy but
4239                 * higher numbered CPUs in order to pack all tasks in the
4240                 * lowest numbered CPUs.
4241                 */
4242                if ((sd->flags & SD_ASYM_PACKING) && env->src_cpu > env->dst_cpu)
4243                        return 1;
4244        }
4245
4246        return unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2);
4247}
4248
4249static int active_load_balance_cpu_stop(void *data);
4250
4251/*
4252 * Check this_cpu to ensure it is balanced within domain. Attempt to move
4253 * tasks if there is an imbalance.
4254 */
4255static int load_balance(int this_cpu, struct rq *this_rq,
4256                        struct sched_domain *sd, enum cpu_idle_type idle,
4257                        int *balance)
4258{
4259        int ld_moved, cur_ld_moved, active_balance = 0;
4260        int lb_iterations, max_lb_iterations;
4261        struct sched_group *group;
4262        struct rq *busiest;
4263        unsigned long flags;
4264        struct cpumask *cpus = __get_cpu_var(load_balance_tmpmask);
4265
4266        struct lb_env env = {
4267                .sd             = sd,
4268                .dst_cpu        = this_cpu,
4269                .dst_rq         = this_rq,
4270                .dst_grpmask    = sched_group_cpus(sd->groups),
4271                .idle           = idle,
4272                .loop_break     = sched_nr_migrate_break,
4273                .cpus           = cpus,
4274        };
4275
4276        cpumask_copy(cpus, cpu_active_mask);
4277        max_lb_iterations = cpumask_weight(env.dst_grpmask);
4278
4279        schedstat_inc(sd, lb_count[idle]);
4280
4281redo:
4282        group = find_busiest_group(&env, balance);
4283
4284        if (*balance == 0)
4285                goto out_balanced;
4286
4287        if (!group) {
4288                schedstat_inc(sd, lb_nobusyg[idle]);
4289                goto out_balanced;
4290        }
4291
4292        busiest = find_busiest_queue(&env, group);
4293        if (!busiest) {
4294                schedstat_inc(sd, lb_nobusyq[idle]);
4295                goto out_balanced;
4296        }
4297
4298        BUG_ON(busiest == this_rq);
4299
4300        schedstat_add(sd, lb_imbalance[idle], env.imbalance);
4301
4302        ld_moved = 0;
4303        lb_iterations = 1;
4304        if (busiest->nr_running > 1) {
4305                /*
4306                 * Attempt to move tasks. If find_busiest_group has found
4307                 * an imbalance but busiest->nr_running <= 1, the group is
4308                 * still unbalanced. ld_moved simply stays zero, so it is
4309                 * correctly treated as an imbalance.
4310                 */
4311                env.flags |= LBF_ALL_PINNED;
4312                env.src_cpu   = busiest->cpu;
4313                env.src_rq    = busiest;
4314                env.loop_max  = min(sysctl_sched_nr_migrate, busiest->nr_running);
4315
4316                update_h_load(env.src_cpu);
4317more_balance:
4318                local_irq_save(flags);
4319                double_rq_lock(this_rq, busiest);
4320
4321                /*
4322                 * cur_ld_moved - load moved in current iteration
4323                 * ld_moved     - cumulative load moved across iterations
4324                 */
4325                cur_ld_moved = move_tasks(&env);
4326                ld_moved += cur_ld_moved;
4327                double_rq_unlock(this_rq, busiest);
4328                local_irq_restore(flags);
4329
4330                if (env.flags & LBF_NEED_BREAK) {
4331                        env.flags &= ~LBF_NEED_BREAK;
4332                        goto more_balance;
4333                }
4334
4335                /*
4336                 * some other cpu did the load balance for us.
4337                 */
4338                if (cur_ld_moved && env.dst_cpu != smp_processor_id())
4339                        resched_cpu(env.dst_cpu);
4340
4341                /*
4342                 * Revisit (affine) tasks on src_cpu that couldn't be moved to
4343                 * us and move them to an alternate dst_cpu in our sched_group
4344                 * where they can run. The upper limit on how many times we
4345                 * iterate on same src_cpu is dependent on number of cpus in our
4346                 * sched_group.
4347                 *
4348                 * This changes load balance semantics a bit on who can move
4349                 * load to a given_cpu. In addition to the given_cpu itself
4350                 * (or a ilb_cpu acting on its behalf where given_cpu is
4351                 * nohz-idle), we now have balance_cpu in a position to move
4352                 * load to given_cpu. In rare situations, this may cause
4353                 * conflicts (balance_cpu and given_cpu/ilb_cpu deciding
4354                 * _independently_ and at _same_ time to move some load to
4355                 * given_cpu) causing exceess load to be moved to given_cpu.
4356                 * This however should not happen so much in practice and
4357                 * moreover subsequent load balance cycles should correct the
4358                 * excess load moved.
4359                 */
4360                if ((env.flags & LBF_SOME_PINNED) && env.imbalance > 0 &&
4361                                lb_iterations++ < max_lb_iterations) {
4362
4363                        this_rq          = cpu_rq(env.new_dst_cpu);
4364                        env.dst_rq       = this_rq;
4365                        env.dst_cpu      = env.new_dst_cpu;
4366                        env.flags       &= ~LBF_SOME_PINNED;
4367                        env.loop         = 0;
4368                        env.loop_break   = sched_nr_migrate_break;
4369                        /*
4370                         * Go back to "more_balance" rather than "redo" since we
4371                         * need to continue with same src_cpu.
4372                         */
4373                        goto more_balance;
4374                }
4375
4376                /* All tasks on this runqueue were pinned by CPU affinity */
4377                if (unlikely(env.flags & LBF_ALL_PINNED)) {
4378                        cpumask_clear_cpu(cpu_of(busiest), cpus);
4379                        if (!cpumask_empty(cpus)) {
4380                                env.loop = 0;
4381                                env.loop_break = sched_nr_migrate_break;
4382                                goto redo;
4383                        }
4384                        goto out_balanced;
4385                }
4386        }
4387
4388        if (!ld_moved) {
4389                schedstat_inc(sd, lb_failed[idle]);
4390                /*
4391                 * Increment the failure counter only on periodic balance.
4392                 * We do not want newidle balance, which can be very
4393                 * frequent, pollute the failure counter causing
4394                 * excessive cache_hot migrations and active balances.
4395                 */
4396                if (idle != CPU_NEWLY_IDLE)
4397                        sd->nr_balance_failed++;
4398
4399                if (need_active_balance(&env)) {
4400                        raw_spin_lock_irqsave(&busiest->lock, flags);
4401
4402                        /* don't kick the active_load_balance_cpu_stop,
4403                         * if the curr task on busiest cpu can't be
4404                         * moved to this_cpu
4405                         */
4406                        if (!cpumask_test_cpu(this_cpu,
4407                                        tsk_cpus_allowed(busiest->curr))) {
4408                                raw_spin_unlock_irqrestore(&busiest->lock,
4409                                                            flags);
4410                                env.flags |= LBF_ALL_PINNED;
4411                                goto out_one_pinned;
4412                        }
4413
4414                        /*
4415                         * ->active_balance synchronizes accesses to
4416                         * ->active_balance_work.  Once set, it's cleared
4417                         * only after active load balance is finished.
4418                         */
4419                        if (!busiest->active_balance) {
4420                                busiest->active_balance = 1;
4421                                busiest->push_cpu = this_cpu;
4422                                active_balance = 1;
4423                        }
4424                        raw_spin_unlock_irqrestore(&busiest->lock, flags);
4425
4426                        if (active_balance) {
4427                                stop_one_cpu_nowait(cpu_of(busiest),
4428                                        active_load_balance_cpu_stop, busiest,
4429                                        &busiest->active_balance_work);
4430                        }
4431
4432                        /*
4433                         * We've kicked active balancing, reset the failure
4434                         * counter.
4435                         */
4436                        sd->nr_balance_failed = sd->cache_nice_tries+1;
4437                }
4438        } else
4439                sd->nr_balance_failed = 0;
4440
4441        if (likely(!active_balance)) {
4442                /* We were unbalanced, so reset the balancing interval */
4443                sd->balance_interval = sd->min_interval;
4444        } else {
4445                /*
4446                 * If we've begun active balancing, start to back off. This
4447                 * case may not be covered by the all_pinned logic if there
4448                 * is only 1 task on the busy runqueue (because we don't call
4449                 * move_tasks).
4450                 */
4451                if (sd->balance_interval < sd->max_interval)
4452                        sd->balance_interval *= 2;
4453        }
4454
4455        goto out;
4456
4457out_balanced:
4458        schedstat_inc(sd, lb_balanced[idle]);
4459
4460        sd->nr_balance_failed = 0;
4461
4462out_one_pinned:
4463        /* tune up the balancing interval */
4464        if (((env.flags & LBF_ALL_PINNED) &&
4465                        sd->balance_interval < MAX_PINNED_INTERVAL) ||
4466                        (sd->balance_interval < sd->max_interval))
4467                sd->balance_interval *= 2;
4468
4469        ld_moved = 0;
4470out:
4471        return ld_moved;
4472}
4473
4474/*
4475 * idle_balance is called by schedule() if this_cpu is about to become
4476 * idle. Attempts to pull tasks from other CPUs.
4477 */
4478void idle_balance(int this_cpu, struct rq *this_rq)
4479{
4480        struct sched_domain *sd;
4481        int pulled_task = 0;
4482        unsigned long next_balance = jiffies + HZ;
4483
4484        this_rq->idle_stamp = this_rq->clock;
4485
4486        if (this_rq->avg_idle < sysctl_sched_migration_cost)
4487                return;
4488
4489        /*
4490         * Drop the rq->lock, but keep IRQ/preempt disabled.
4491         */
4492        raw_spin_unlock(&this_rq->lock);
4493
4494        update_shares(this_cpu);
4495        rcu_read_lock();
4496        for_each_domain(this_cpu, sd) {
4497                unsigned long interval;
4498                int balance = 1;
4499
4500                if (!(sd->flags & SD_LOAD_BALANCE))
4501                        continue;
4502
4503                if (sd->flags & SD_BALANCE_NEWIDLE) {
4504                        /* If we've pulled tasks over stop searching: */
4505                        pulled_task = load_balance(this_cpu, this_rq,
4506                                                   sd, CPU_NEWLY_IDLE, &balance);
4507                }
4508
4509                interval = msecs_to_jiffies(sd->balance_interval);
4510                if (time_after(next_balance, sd->last_balance + interval))
4511                        next_balance = sd->last_balance + interval;
4512                if (pulled_task) {
4513                        this_rq->idle_stamp = 0;
4514                        break;
4515                }
4516        }
4517        rcu_read_unlock();
4518
4519        raw_spin_lock(&this_rq->lock);
4520
4521        if (pulled_task || time_after(jiffies, this_rq->next_balance)) {
4522                /*
4523                 * We are going idle. next_balance may be set based on
4524                 * a busy processor. So reset next_balance.
4525                 */
4526                this_rq->next_balance = next_balance;
4527        }
4528}
4529
4530/*
4531 * active_load_balance_cpu_stop is run by cpu stopper. It pushes
4532 * running tasks off the busiest CPU onto idle CPUs. It requires at
4533 * least 1 task to be running on each physical CPU where possible, and
4534 * avoids physical / logical imbalances.
4535 */
4536static int active_load_balance_cpu_stop(void *data)
4537{
4538        struct rq *busiest_rq = data;
4539        int busiest_cpu = cpu_of(busiest_rq);
4540        int target_cpu = busiest_rq->push_cpu;
4541        struct rq *target_rq = cpu_rq(target_cpu);
4542        struct sched_domain *sd;
4543
4544        raw_spin_lock_irq(&busiest_rq->lock);
4545
4546        /* make sure the requested cpu hasn't gone down in the meantime */
4547        if (unlikely(busiest_cpu != smp_processor_id() ||
4548                     !busiest_rq->active_balance))
4549                goto out_unlock;
4550
4551        /* Is there any task to move? */
4552        if (busiest_rq->nr_running <= 1)
4553                goto out_unlock;
4554
4555        /*
4556         * This condition is "impossible", if it occurs
4557         * we need to fix it. Originally reported by
4558         * Bjorn Helgaas on a 128-cpu setup.
4559         */
4560        BUG_ON(busiest_rq == target_rq);
4561
4562        /* move a task from busiest_rq to target_rq */
4563        double_lock_balance(busiest_rq, target_rq);
4564
4565        /* Search for an sd spanning us and the target CPU. */
4566        rcu_read_lock();
4567        for_each_domain(target_cpu, sd) {
4568                if ((sd->flags & SD_LOAD_BALANCE) &&
4569                    cpumask_test_cpu(busiest_cpu, sched_domain_span(sd)))
4570                                break;
4571        }
4572
4573        if (likely(sd)) {
4574                struct lb_env env = {
4575                        .sd             = sd,
4576                        .dst_cpu        = target_cpu,
4577                        .dst_rq         = target_rq,
4578                        .src_cpu        = busiest_rq->cpu,
4579                        .src_rq         = busiest_rq,
4580                        .idle           = CPU_IDLE,
4581                };
4582
4583                schedstat_inc(sd, alb_count);
4584
4585                if (move_one_task(&env))
4586                        schedstat_inc(sd, alb_pushed);
4587                else
4588                        schedstat_inc(sd, alb_failed);
4589        }
4590        rcu_read_unlock();
4591        double_unlock_balance(busiest_rq, target_rq);
4592out_unlock:
4593        busiest_rq->active_balance = 0;
4594        raw_spin_unlock_irq(&busiest_rq->lock);
4595        return 0;
4596}
4597
4598#ifdef CONFIG_NO_HZ
4599/*
4600 * idle load balancing details
4601 * - When one of the busy CPUs notice that there may be an idle rebalancing
4602 *   needed, they will kick the idle load balancer, which then does idle
4603 *   load balancing for all the idle CPUs.
4604 */
4605static struct {
4606        cpumask_var_t idle_cpus_mask;
4607        atomic_t nr_cpus;
4608        unsigned long next_balance;     /* in jiffy units */
4609} nohz ____cacheline_aligned;
4610
4611static inline int find_new_ilb(int call_cpu)
4612{
4613        int ilb = cpumask_first(nohz.idle_cpus_mask);
4614
4615        if (ilb < nr_cpu_ids && idle_cpu(ilb))
4616                return ilb;
4617
4618        return nr_cpu_ids;
4619}
4620
4621/*
4622 * Kick a CPU to do the nohz balancing, if it is time for it. We pick the
4623 * nohz_load_balancer CPU (if there is one) otherwise fallback to any idle
4624 * CPU (if there is one).
4625 */
4626static void nohz_balancer_kick(int cpu)
4627{
4628        int ilb_cpu;
4629
4630        nohz.next_balance++;
4631
4632        ilb_cpu = find_new_ilb(cpu);
4633
4634        if (ilb_cpu >= nr_cpu_ids)
4635                return;
4636
4637        if (test_and_set_bit(NOHZ_BALANCE_KICK, nohz_flags(ilb_cpu)))
4638                return;
4639        /*
4640         * Use smp_send_reschedule() instead of resched_cpu().
4641         * This way we generate a sched IPI on the target cpu which
4642         * is idle. And the softirq performing nohz idle load balance
4643         * will be run before returning from the IPI.
4644         */
4645        smp_send_reschedule(ilb_cpu);
4646        return;
4647}
4648
4649static inline void clear_nohz_tick_stopped(int cpu)
4650{
4651        if (unlikely(test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))) {
4652                cpumask_clear_cpu(cpu, nohz.idle_cpus_mask);
4653                atomic_dec(&nohz.nr_cpus);
4654                clear_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
4655        }
4656}
4657
4658static inline void set_cpu_sd_state_busy(void)
4659{
4660        struct sched_domain *sd;
4661        int cpu = smp_processor_id();
4662
4663        if (!test_bit(NOHZ_IDLE, nohz_flags(cpu)))
4664                return;
4665        clear_bit(NOHZ_IDLE, nohz_flags(cpu));
4666
4667        rcu_read_lock();
4668        for_each_domain(cpu, sd)
4669                atomic_inc(&sd->groups->sgp->nr_busy_cpus);
4670        rcu_read_unlock();
4671}
4672
4673void set_cpu_sd_state_idle(void)
4674{
4675        struct sched_domain *sd;
4676        int cpu = smp_processor_id();
4677
4678        if (test_bit(NOHZ_IDLE, nohz_flags(cpu)))
4679                return;
4680        set_bit(NOHZ_IDLE, nohz_flags(cpu));
4681
4682        rcu_read_lock();
4683        for_each_domain(cpu, sd)
4684                atomic_dec(&sd->groups->sgp->nr_busy_cpus);
4685        rcu_read_unlock();
4686}
4687
4688/*
4689 * This routine will record that this cpu is going idle with tick stopped.
4690 * This info will be used in performing idle load balancing in the future.
4691 */
4692void select_nohz_load_balancer(int stop_tick)
4693{
4694        int cpu = smp_processor_id();
4695
4696        /*
4697         * If this cpu is going down, then nothing needs to be done.
4698         */
4699        if (!cpu_active(cpu))
4700                return;
4701
4702        if (stop_tick) {
4703                if (test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))
4704                        return;
4705
4706                cpumask_set_cpu(cpu, nohz.idle_cpus_mask);
4707                atomic_inc(&nohz.nr_cpus);
4708                set_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
4709        }
4710        return;
4711}
4712
4713static int __cpuinit sched_ilb_notifier(struct notifier_block *nfb,
4714                                        unsigned long action, void *hcpu)
4715{
4716        switch (action & ~CPU_TASKS_FROZEN) {
4717        case CPU_DYING:
4718                clear_nohz_tick_stopped(smp_processor_id());
4719                return NOTIFY_OK;
4720        default:
4721                return NOTIFY_DONE;
4722        }
4723}
4724#endif
4725
4726static DEFINE_SPINLOCK(balancing);
4727
4728/*
4729 * Scale the max load_balance interval with the number of CPUs in the system.
4730 * This trades load-balance latency on larger machines for less cross talk.
4731 */
4732void update_max_interval(void)
4733{
4734        max_load_balance_interval = HZ*num_online_cpus()/10;
4735}
4736
4737/*
4738 * It checks each scheduling domain to see if it is due to be balanced,
4739 * and initiates a balancing operation if so.
4740 *
4741 * Balancing parameters are set up in arch_init_sched_domains.
4742 */
4743static void rebalance_domains(int cpu, enum cpu_idle_type idle)
4744{
4745        int balance = 1;
4746        struct rq *rq = cpu_rq(cpu);
4747        unsigned long interval;
4748        struct sched_domain *sd;
4749        /* Earliest time when we have to do rebalance again */
4750        unsigned long next_balance = jiffies + 60*HZ;
4751        int update_next_balance = 0;
4752        int need_serialize;
4753
4754        update_shares(cpu);
4755
4756        rcu_read_lock();
4757        for_each_domain(cpu, sd) {
4758                if (!(sd->flags & SD_LOAD_BALANCE))
4759                        continue;
4760
4761                interval = sd->balance_interval;
4762                if (idle != CPU_IDLE)
4763                        interval *= sd->busy_factor;
4764
4765                /* scale ms to jiffies */
4766                interval = msecs_to_jiffies(interval);
4767                interval = clamp(interval, 1UL, max_load_balance_interval);
4768
4769                need_serialize = sd->flags & SD_SERIALIZE;
4770
4771                if (need_serialize) {
4772                        if (!spin_trylock(&balancing))
4773                                goto out;
4774                }
4775
4776                if (time_after_eq(jiffies, sd->last_balance + interval)) {
4777                        if (load_balance(cpu, rq, sd, idle, &balance)) {
4778                                /*
4779                                 * We've pulled tasks over so either we're no
4780                                 * longer idle.
4781                                 */
4782                                idle = CPU_NOT_IDLE;
4783                        }
4784                        sd->last_balance = jiffies;
4785                }
4786                if (need_serialize)
4787                        spin_unlock(&balancing);
4788out:
4789                if (time_after(next_balance, sd->last_balance + interval)) {
4790                        next_balance = sd->last_balance + interval;
4791                        update_next_balance = 1;
4792                }
4793
4794                /*
4795                 * Stop the load balance at this level. There is another
4796                 * CPU in our sched group which is doing load balancing more
4797                 * actively.
4798                 */
4799                if (!balance)
4800                        break;
4801        }
4802        rcu_read_unlock();
4803
4804        /*
4805         * next_balance will be updated only when there is a need.
4806         * When the cpu is attached to null domain for ex, it will not be
4807         * updated.
4808         */
4809        if (likely(update_next_balance))
4810                rq->next_balance = next_balance;
4811}
4812
4813#ifdef CONFIG_NO_HZ
4814/*
4815 * In CONFIG_NO_HZ case, the idle balance kickee will do the
4816 * rebalancing for all the cpus for whom scheduler ticks are stopped.
4817 */
4818static void nohz_idle_balance(int this_cpu, enum cpu_idle_type idle)
4819{
4820        struct rq *this_rq = cpu_rq(this_cpu);
4821        struct rq *rq;
4822        int balance_cpu;
4823
4824        if (idle != CPU_IDLE ||
4825            !test_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu)))
4826                goto end;
4827
4828        for_each_cpu(balance_cpu, nohz.idle_cpus_mask) {
4829                if (balance_cpu == this_cpu || !idle_cpu(balance_cpu))
4830                        continue;
4831
4832                /*
4833                 * If this cpu gets work to do, stop the load balancing
4834                 * work being done for other cpus. Next load
4835                 * balancing owner will pick it up.
4836                 */
4837                if (need_resched())
4838                        break;
4839
4840                raw_spin_lock_irq(&this_rq->lock);
4841                update_rq_clock(this_rq);
4842                update_idle_cpu_load(this_rq);
4843                raw_spin_unlock_irq(&this_rq->lock);
4844
4845                rebalance_domains(balance_cpu, CPU_IDLE);
4846
4847                rq = cpu_rq(balance_cpu);
4848                if (time_after(this_rq->next_balance, rq->next_balance))
4849                        this_rq->next_balance = rq->next_balance;
4850        }
4851        nohz.next_balance = this_rq->next_balance;
4852end:
4853        clear_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu));
4854}
4855
4856/*
4857 * Current heuristic for kicking the idle load balancer in the presence
4858 * of an idle cpu is the system.
4859 *   - This rq has more than one task.
4860 *   - At any scheduler domain level, this cpu's scheduler group has multiple
4861 *     busy cpu's exceeding the group's power.
4862 *   - For SD_ASYM_PACKING, if the lower numbered cpu's in the scheduler
4863 *     domain span are idle.
4864 */
4865static inline int nohz_kick_needed(struct rq *rq, int cpu)
4866{
4867        unsigned long now = jiffies;
4868        struct sched_domain *sd;
4869
4870        if (unlikely(idle_cpu(cpu)))
4871                return 0;
4872
4873       /*
4874        * We may be recently in ticked or tickless idle mode. At the first
4875        * busy tick after returning from idle, we will update the busy stats.
4876        */
4877        set_cpu_sd_state_busy();
4878        clear_nohz_tick_stopped(cpu);
4879
4880        /*
4881         * None are in tickless mode and hence no need for NOHZ idle load
4882         * balancing.
4883         */
4884        if (likely(!atomic_read(&nohz.nr_cpus)))
4885                return 0;
4886
4887        if (time_before(now, nohz.next_balance))
4888                return 0;
4889
4890        if (rq->nr_running >= 2)
4891                goto need_kick;
4892
4893        rcu_read_lock();
4894        for_each_domain(cpu, sd) {
4895                struct sched_group *sg = sd->groups;
4896                struct sched_group_power *sgp = sg->sgp;
4897                int nr_busy = atomic_read(&sgp->nr_busy_cpus);
4898
4899                if (sd->flags & SD_SHARE_PKG_RESOURCES && nr_busy > 1)
4900                        goto need_kick_unlock;
4901
4902                if (sd->flags & SD_ASYM_PACKING && nr_busy != sg->group_weight
4903                    && (cpumask_first_and(nohz.idle_cpus_mask,
4904                                          sched_domain_span(sd)) < cpu))
4905                        goto need_kick_unlock;
4906
4907                if (!(sd->flags & (SD_SHARE_PKG_RESOURCES | SD_ASYM_PACKING)))
4908                        break;
4909        }
4910        rcu_read_unlock();
4911        return 0;
4912
4913need_kick_unlock:
4914        rcu_read_unlock();
4915need_kick:
4916        return 1;
4917}
4918#else
4919static void nohz_idle_balance(int this_cpu, enum cpu_idle_type idle) { }
4920#endif
4921
4922/*
4923 * run_rebalance_domains is triggered when needed from the scheduler tick.
4924 * Also triggered for nohz idle balancing (with nohz_balancing_kick set).
4925 */
4926static void run_rebalance_domains(struct softirq_action *h)
4927{
4928        int this_cpu = smp_processor_id();
4929        struct rq *this_rq = cpu_rq(this_cpu);
4930        enum cpu_idle_type idle = this_rq->idle_balance ?
4931                                                CPU_IDLE : CPU_NOT_IDLE;
4932
4933        rebalance_domains(this_cpu, idle);
4934
4935        /*
4936         * If this cpu has a pending nohz_balance_kick, then do the
4937         * balancing on behalf of the other idle cpus whose ticks are
4938         * stopped.
4939         */
4940        nohz_idle_balance(this_cpu, idle);
4941}
4942
4943static inline int on_null_domain(int cpu)
4944{
4945        return !rcu_dereference_sched(cpu_rq(cpu)->sd);
4946}
4947
4948/*
4949 * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
4950 */
4951void trigger_load_balance(struct rq *rq, int cpu)
4952{
4953        /* Don't need to rebalance while attached to NULL domain */
4954        if (time_after_eq(jiffies, rq->next_balance) &&
4955            likely(!on_null_domain(cpu)))
4956                raise_softirq(SCHED_SOFTIRQ);
4957#ifdef CONFIG_NO_HZ
4958        if (nohz_kick_needed(rq, cpu) && likely(!on_null_domain(cpu)))
4959                nohz_balancer_kick(cpu);
4960#endif
4961}
4962
4963static void rq_online_fair(struct rq *rq)
4964{
4965        update_sysctl();
4966}
4967
4968static void rq_offline_fair(struct rq *rq)
4969{
4970        update_sysctl();
4971
4972        /* Ensure any throttled groups are reachable by pick_next_task */
4973        unthrottle_offline_cfs_rqs(rq);
4974}
4975
4976#endif /* CONFIG_SMP */
4977
4978/*
4979 * scheduler tick hitting a task of our scheduling class:
4980 */
4981static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued)
4982{
4983        struct cfs_rq *cfs_rq;
4984        struct sched_entity *se = &curr->se;
4985
4986        for_each_sched_entity(se) {
4987                cfs_rq = cfs_rq_of(se);
4988                entity_tick(cfs_rq, se, queued);
4989        }
4990}
4991
4992/*
4993 * called on fork with the child task as argument from the parent's context
4994 *  - child not yet on the tasklist
4995 *  - preemption disabled
4996 */
4997static void task_fork_fair(struct task_struct *p)
4998{
4999        struct cfs_rq *cfs_rq;
5000        struct sched_entity *se = &p->se, *curr;
5001        int this_cpu = smp_processor_id();
5002        struct rq *rq = this_rq();
5003        unsigned long flags;
5004
5005        raw_spin_lock_irqsave(&rq->lock, flags);
5006
5007        update_rq_clock(rq);
5008
5009        cfs_rq = task_cfs_rq(current);
5010        curr = cfs_rq->curr;
5011
5012        if (unlikely(task_cpu(p) != this_cpu)) {
5013                rcu_read_lock();
5014                __set_task_cpu(p, this_cpu);
5015                rcu_read_unlock();
5016        }
5017
5018        update_curr(cfs_rq);
5019
5020        if (curr)
5021                se->vruntime = curr->vruntime;
5022        place_entity(cfs_rq, se, 1);
5023
5024        if (sysctl_sched_child_runs_first && curr && entity_before(curr, se)) {
5025                /*
5026                 * Upon rescheduling, sched_class::put_prev_task() will place
5027                 * 'current' within the tree based on its new key value.
5028                 */
5029                swap(curr->vruntime, se->vruntime);
5030                resched_task(rq->curr);
5031        }
5032
5033        se->vruntime -= cfs_rq->min_vruntime;
5034
5035        raw_spin_unlock_irqrestore(&rq->lock, flags);
5036}
5037
5038/*
5039 * Priority of the task has changed. Check to see if we preempt
5040 * the current task.
5041 */
5042static void
5043prio_changed_fair(struct rq *rq, struct task_struct *p, int oldprio)
5044{
5045        if (!p->se.on_rq)
5046                return;
5047
5048        /*
5049         * Reschedule if we are currently running on this runqueue and
5050         * our priority decreased, or if we are not currently running on
5051         * this runqueue and our priority is higher than the current's
5052         */
5053        if (rq->curr == p) {
5054                if (p->prio > oldprio)
5055                        resched_task(rq->curr);
5056        } else
5057                check_preempt_curr(rq, p, 0);
5058}
5059
5060static void switched_from_fair(struct rq *rq, struct task_struct *p)
5061{
5062        struct sched_entity *se = &p->se;
5063        struct cfs_rq *cfs_rq = cfs_rq_of(se);
5064
5065        /*
5066         * Ensure the task's vruntime is normalized, so that when its
5067         * switched back to the fair class the enqueue_entity(.flags=0) will
5068         * do the right thing.
5069         *
5070         * If it was on_rq, then the dequeue_entity(.flags=0) will already
5071         * have normalized the vruntime, if it was !on_rq, then only when
5072         * the task is sleeping will it still have non-normalized vruntime.
5073         */
5074        if (!se->on_rq && p->state != TASK_RUNNING) {
5075                /*
5076                 * Fix up our vruntime so that the current sleep doesn't
5077                 * cause 'unlimited' sleep bonus.
5078                 */
5079                place_entity(cfs_rq, se, 0);
5080                se->vruntime -= cfs_rq->min_vruntime;
5081        }
5082}
5083
5084/*
5085 * We switched to the sched_fair class.
5086 */
5087static void switched_to_fair(struct rq *rq, struct task_struct *p)
5088{
5089        if (!p->se.on_rq)
5090                return;
5091
5092        /*
5093         * We were most likely switched from sched_rt, so
5094         * kick off the schedule if running, otherwise just see
5095         * if we can still preempt the current task.
5096         */
5097        if (rq->curr == p)
5098                resched_task(rq->curr);
5099        else
5100                check_preempt_curr(rq, p, 0);
5101}
5102
5103/* Account for a task changing its policy or group.
5104 *
5105 * This routine is mostly called to set cfs_rq->curr field when a task
5106 * migrates between groups/classes.
5107 */
5108static void set_curr_task_fair(struct rq *rq)
5109{
5110        struct sched_entity *se = &rq->curr->se;
5111
5112        for_each_sched_entity(se) {
5113                struct cfs_rq *cfs_rq = cfs_rq_of(se);
5114
5115                set_next_entity(cfs_rq, se);
5116                /* ensure bandwidth has been allocated on our new cfs_rq */
5117                account_cfs_rq_runtime(cfs_rq, 0);
5118        }
5119}
5120
5121void init_cfs_rq(struct cfs_rq *cfs_rq)
5122{
5123        cfs_rq->tasks_timeline = RB_ROOT;
5124        cfs_rq->min_vruntime = (u64)(-(1LL << 20));
5125#ifndef CONFIG_64BIT
5126        cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime;
5127#endif
5128}
5129
5130#ifdef CONFIG_FAIR_GROUP_SCHED
5131static void task_move_group_fair(struct task_struct *p, int on_rq)
5132{
5133        /*
5134         * If the task was not on the rq at the time of this cgroup movement
5135         * it must have been asleep, sleeping tasks keep their ->vruntime
5136         * absolute on their old rq until wakeup (needed for the fair sleeper
5137         * bonus in place_entity()).
5138         *
5139         * If it was on the rq, we've just 'preempted' it, which does convert
5140         * ->vruntime to a relative base.
5141         *
5142         * Make sure both cases convert their relative position when migrating
5143         * to another cgroup's rq. This does somewhat interfere with the
5144         * fair sleeper stuff for the first placement, but who cares.
5145         */
5146        /*
5147         * When !on_rq, vruntime of the task has usually NOT been normalized.
5148         * But there are some cases where it has already been normalized:
5149         *
5150         * - Moving a forked child which is waiting for being woken up by
5151         *   wake_up_new_task().
5152         * - Moving a task which has been woken up by try_to_wake_up() and
5153         *   waiting for actually being woken up by sched_ttwu_pending().
5154         *
5155         * To prevent boost or penalty in the new cfs_rq caused by delta
5156         * min_vruntime between the two cfs_rqs, we skip vruntime adjustment.
5157         */
5158        if (!on_rq && (!p->se.sum_exec_runtime || p->state == TASK_WAKING))
5159                on_rq = 1;
5160
5161        if (!on_rq)
5162                p->se.vruntime -= cfs_rq_of(&p->se)->min_vruntime;
5163        set_task_rq(p, task_cpu(p));
5164        if (!on_rq)
5165                p->se.vruntime += cfs_rq_of(&p->se)->min_vruntime;
5166}
5167
5168void free_fair_sched_group(struct task_group *tg)
5169{
5170        int i;
5171
5172        destroy_cfs_bandwidth(tg_cfs_bandwidth(tg));
5173
5174        for_each_possible_cpu(i) {
5175                if (tg->cfs_rq)
5176                        kfree(tg->cfs_rq[i]);
5177                if (tg->se)
5178                        kfree(tg->se[i]);
5179        }
5180
5181        kfree(tg->cfs_rq);
5182        kfree(tg->se);
5183}
5184
5185int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
5186{
5187        struct cfs_rq *cfs_rq;
5188        struct sched_entity *se;
5189        int i;
5190
5191        tg->cfs_rq = kzalloc(sizeof(cfs_rq) * nr_cpu_ids, GFP_KERNEL);
5192        if (!tg->cfs_rq)
5193                goto err;
5194        tg->se = kzalloc(sizeof(se) * nr_cpu_ids, GFP_KERNEL);
5195        if (!tg->se)
5196                goto err;
5197
5198        tg->shares = NICE_0_LOAD;
5199
5200        init_cfs_bandwidth(tg_cfs_bandwidth(tg));
5201
5202        for_each_possible_cpu(i) {
5203                cfs_rq = kzalloc_node(sizeof(struct cfs_rq),
5204                                      GFP_KERNEL, cpu_to_node(i));
5205                if (!cfs_rq)
5206                        goto err;
5207
5208                se = kzalloc_node(sizeof(struct sched_entity),
5209                                  GFP_KERNEL, cpu_to_node(i));
5210                if (!se)
5211                        goto err_free_rq;
5212
5213                init_cfs_rq(cfs_rq);
5214                init_tg_cfs_entry(tg, cfs_rq, se, i, parent->se[i]);
5215        }
5216
5217        return 1;
5218
5219err_free_rq:
5220        kfree(cfs_rq);
5221err:
5222        return 0;
5223}
5224
5225void unregister_fair_sched_group(struct task_group *tg, int cpu)
5226{
5227        struct rq *rq = cpu_rq(cpu);
5228        unsigned long flags;
5229
5230        /*
5231        * Only empty task groups can be destroyed; so we can speculatively
5232        * check on_list without danger of it being re-added.
5233        */
5234        if (!tg->cfs_rq[cpu]->on_list)
5235                return;
5236
5237        raw_spin_lock_irqsave(&rq->lock, flags);
5238        list_del_leaf_cfs_rq(tg->cfs_rq[cpu]);
5239        raw_spin_unlock_irqrestore(&rq->lock, flags);
5240}
5241
5242void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq,
5243                        struct sched_entity *se, int cpu,
5244                        struct sched_entity *parent)
5245{
5246        struct rq *rq = cpu_rq(cpu);
5247
5248        cfs_rq->tg = tg;
5249        cfs_rq->rq = rq;
5250#ifdef CONFIG_SMP
5251        /* allow initial update_cfs_load() to truncate */
5252        cfs_rq->load_stamp = 1;
5253#endif
5254        init_cfs_rq_runtime(cfs_rq);
5255
5256        tg->cfs_rq[cpu] = cfs_rq;
5257        tg->se[cpu] = se;
5258
5259        /* se could be NULL for root_task_group */
5260        if (!se)
5261                return;
5262
5263        if (!parent)
5264                se->cfs_rq = &rq->cfs;
5265        else
5266                se->cfs_rq = parent->my_q;
5267
5268        se->my_q = cfs_rq;
5269        update_load_set(&se->load, 0);
5270        se->parent = parent;
5271}
5272
5273static DEFINE_MUTEX(shares_mutex);
5274
5275int sched_group_set_shares(struct task_group *tg, unsigned long shares)
5276{
5277        int i;
5278        unsigned long flags;
5279
5280        /*
5281         * We can't change the weight of the root cgroup.
5282         */
5283        if (!tg->se[0])
5284                return -EINVAL;
5285
5286        shares = clamp(shares, scale_load(MIN_SHARES), scale_load(MAX_SHARES));
5287
5288        mutex_lock(&shares_mutex);
5289        if (tg->shares == shares)
5290                goto done;
5291
5292        tg->shares = shares;
5293        for_each_possible_cpu(i) {
5294                struct rq *rq = cpu_rq(i);
5295                struct sched_entity *se;
5296
5297                se = tg->se[i];
5298                /* Propagate contribution to hierarchy */
5299                raw_spin_lock_irqsave(&rq->lock, flags);
5300                for_each_sched_entity(se)
5301                        update_cfs_shares(group_cfs_rq(se));
5302                raw_spin_unlock_irqrestore(&rq->lock, flags);
5303        }
5304
5305done:
5306        mutex_unlock(&shares_mutex);
5307        return 0;
5308}
5309#else /* CONFIG_FAIR_GROUP_SCHED */
5310
5311void free_fair_sched_group(struct task_group *tg) { }
5312
5313int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
5314{
5315        return 1;
5316}
5317
5318void unregister_fair_sched_group(struct task_group *tg, int cpu) { }
5319
5320#endif /* CONFIG_FAIR_GROUP_SCHED */
5321
5322
5323static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task)
5324{
5325        struct sched_entity *se = &task->se;
5326        unsigned int rr_interval = 0;
5327
5328        /*
5329         * Time slice is 0 for SCHED_OTHER tasks that are on an otherwise
5330         * idle runqueue:
5331         */
5332        if (rq->cfs.load.weight)
5333                rr_interval = NS_TO_JIFFIES(sched_slice(&rq->cfs, se));
5334
5335        return rr_interval;
5336}
5337
5338/*
5339 * All the scheduling class methods:
5340 */
5341const struct sched_class fair_sched_class = {
5342        .next                   = &idle_sched_class,
5343        .enqueue_task           = enqueue_task_fair,
5344        .dequeue_task           = dequeue_task_fair,
5345        .yield_task             = yield_task_fair,
5346        .yield_to_task          = yield_to_task_fair,
5347
5348        .check_preempt_curr     = check_preempt_wakeup,
5349
5350        .pick_next_task         = pick_next_task_fair,
5351        .put_prev_task          = put_prev_task_fair,
5352
5353#ifdef CONFIG_SMP
5354        .select_task_rq         = select_task_rq_fair,
5355
5356        .rq_online              = rq_online_fair,
5357        .rq_offline             = rq_offline_fair,
5358
5359        .task_waking            = task_waking_fair,
5360#endif
5361
5362        .set_curr_task          = set_curr_task_fair,
5363        .task_tick              = task_tick_fair,
5364        .task_fork              = task_fork_fair,
5365
5366        .prio_changed           = prio_changed_fair,
5367        .switched_from          = switched_from_fair,
5368        .switched_to            = switched_to_fair,
5369
5370        .get_rr_interval        = get_rr_interval_fair,
5371
5372#ifdef CONFIG_FAIR_GROUP_SCHED
5373        .task_move_group        = task_move_group_fair,
5374#endif
5375};
5376
5377#ifdef CONFIG_SCHED_DEBUG
5378void print_cfs_stats(struct seq_file *m, int cpu)
5379{
5380        struct cfs_rq *cfs_rq;
5381
5382        rcu_read_lock();
5383        for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq)
5384                print_cfs_rq(m, cpu, cfs_rq);
5385        rcu_read_unlock();
5386}
5387#endif
5388
5389__init void init_sched_fair_class(void)
5390{
5391#ifdef CONFIG_SMP
5392        open_softirq(SCHED_SOFTIRQ, run_rebalance_domains);
5393
5394#ifdef CONFIG_NO_HZ
5395        nohz.next_balance = jiffies;
5396        zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT);
5397        cpu_notifier(sched_ilb_notifier, 0);
5398#endif
5399#endif /* SMP */
5400
5401}
5402
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