osfmk/kern/sched_proto.c

   1 /*
   2  * Copyright (c) 2009 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28
  29 #include <mach/mach_types.h>
  30 #include <mach/machine.h>
  31 #include <mach/policy.h>
  32 #include <mach/sync_policy.h>
  33 #include <mach/thread_act.h>
  34
  35 #include <machine/machine_routines.h>
  36 #include <machine/sched_param.h>
  37 #include <machine/machine_cpu.h>
  38
  39 #include <kern/kern_types.h>
  40 #include <kern/clock.h>
  41 #include <kern/counters.h>
  42 #include <kern/cpu_number.h>
  43 #include <kern/cpu_data.h>
  44 #include <kern/debug.h>
  45 #include <kern/macro_help.h>
  46 #include <kern/machine.h>
  47 #include <kern/misc_protos.h>
  48 #include <kern/processor.h>
  49 #include <kern/queue.h>
  50 #include <kern/sched.h>
  51 #include <kern/sched_prim.h>
  52 #include <kern/syscall_subr.h>
  53 #include <kern/task.h>
  54 #include <kern/thread.h>
  55
  56 #include <vm/pmap.h>
  57 #include <vm/vm_kern.h>
  58 #include <vm/vm_map.h>
  59
  60 #include <mach/sdt.h>
  61
  62 #include <sys/kdebug.h>
  63
  64 static void
  65 sched_proto_init(void);
  66
  67 static void
  68 sched_proto_timebase_init(void);
  69
  70 static void
  71 sched_proto_processor_init(processor_t processor);
  72
  73 static void
  74 sched_proto_pset_init(processor_set_t pset);
  75
  76 static void
  77 sched_proto_maintenance_continuation(void);
  78
  79 static thread_t
  80 sched_proto_choose_thread(processor_t           processor,
  81     int                            priority,
  82     ast_t                          reason);
  83
  84 static thread_t
  85 sched_proto_steal_thread(processor_set_t                pset);
  86
  87 static int
  88 sched_proto_compute_priority(thread_t thread);
  89
  90 static processor_t
  91 sched_proto_choose_processor(   processor_set_t         pset,
  92     processor_t                     processor,
  93     thread_t                        thread);
  94
  95
  96 static boolean_t
  97 sched_proto_processor_enqueue(
  98         processor_t                    processor,
  99         thread_t                       thread,
 100         integer_t                      options);
 101
 102 static void
 103 sched_proto_processor_queue_shutdown(
 104         processor_t                    processor);
 105
 106 static boolean_t
 107 sched_proto_processor_queue_remove(
 108         processor_t                 processor,
 109         thread_t                thread);
 110
 111 static boolean_t
 112 sched_proto_processor_queue_empty(processor_t           processor);
 113
 114 static boolean_t
 115 sched_proto_processor_queue_has_priority(processor_t            processor,
 116     int                            priority,
 117     boolean_t              gte);
 118
 119 static boolean_t
 120 sched_proto_priority_is_urgent(int priority);
 121
 122 static ast_t
 123 sched_proto_processor_csw_check(processor_t processor);
 124
 125 static uint32_t
 126 sched_proto_initial_quantum_size(thread_t thread);
 127
 128 static sched_mode_t
 129 sched_proto_initial_thread_sched_mode(task_t parent_task);
 130
 131 static boolean_t
 132 sched_proto_can_update_priority(thread_t        thread);
 133
 134 static void
 135 sched_proto_update_priority(thread_t    thread);
 136
 137 static void
 138 sched_proto_lightweight_update_priority(thread_t        thread);
 139
 140 static void
 141 sched_proto_quantum_expire(thread_t     thread);
 142
 143 static int
 144 sched_proto_processor_runq_count(processor_t   processor);
 145
 146 static uint64_t
 147 sched_proto_processor_runq_stats_count_sum(processor_t   processor);
 148
 149 static int
 150 sched_proto_processor_bound_count(processor_t   processor);
 151
 152 static void
 153 sched_proto_thread_update_scan(sched_update_scan_context_t scan_context);
 154
 155
 156 const struct sched_dispatch_table sched_proto_dispatch = {
 157         .sched_name                                     = "proto",
 158         .init                                           = sched_proto_init,
 159         .timebase_init                                  = sched_proto_timebase_init,
 160         .processor_init                                 = sched_proto_processor_init,
 161         .pset_init                                      = sched_proto_pset_init,
 162         .maintenance_continuation                       = sched_proto_maintenance_continuation,
 163         .choose_thread                                  = sched_proto_choose_thread,
 164         .steal_thread_enabled                           = sched_steal_thread_DISABLED,
 165         .steal_thread                                   = sched_proto_steal_thread,
 166         .compute_timeshare_priority                     = sched_proto_compute_priority,
 167         .choose_processor                               = sched_proto_choose_processor,
 168         .processor_enqueue                              = sched_proto_processor_enqueue,
 169         .processor_queue_shutdown                       = sched_proto_processor_queue_shutdown,
 170         .processor_queue_remove                         = sched_proto_processor_queue_remove,
 171         .processor_queue_empty                          = sched_proto_processor_queue_empty,
 172         .priority_is_urgent                             = sched_proto_priority_is_urgent,
 173         .processor_csw_check                            = sched_proto_processor_csw_check,
 174         .processor_queue_has_priority                   = sched_proto_processor_queue_has_priority,
 175         .initial_quantum_size                           = sched_proto_initial_quantum_size,
 176         .initial_thread_sched_mode                      = sched_proto_initial_thread_sched_mode,
 177         .can_update_priority                            = sched_proto_can_update_priority,
 178         .update_priority                                = sched_proto_update_priority,
 179         .lightweight_update_priority                    = sched_proto_lightweight_update_priority,
 180         .quantum_expire                                 = sched_proto_quantum_expire,
 181         .processor_runq_count                           = sched_proto_processor_runq_count,
 182         .processor_runq_stats_count_sum                 = sched_proto_processor_runq_stats_count_sum,
 183         .processor_bound_count                          = sched_proto_processor_bound_count,
 184         .thread_update_scan                             = sched_proto_thread_update_scan,
 185         .direct_dispatch_to_idle_processors             = TRUE,
 186         .multiple_psets_enabled                         = TRUE,
 187         .sched_groups_enabled                           = FALSE,
 188         .avoid_processor_enabled                        = FALSE,
 189         .thread_avoid_processor                         = NULL,
 190         .processor_balance                              = sched_SMT_balance,
 191
 192         .rt_runq                                        = sched_rtglobal_runq,
 193         .rt_init                                        = sched_rtglobal_init,
 194         .rt_queue_shutdown                              = sched_rtglobal_queue_shutdown,
 195         .rt_runq_scan                                   = sched_rtglobal_runq_scan,
 196         .rt_runq_count_sum                              = sched_rtglobal_runq_count_sum,
 197
 198         .qos_max_parallelism                            = sched_qos_max_parallelism,
 199         .check_spill                                    = sched_check_spill,
 200         .ipi_policy                                     = sched_ipi_policy,
 201         .thread_should_yield                            = sched_thread_should_yield,
 202 };
 203
 204 static struct run_queue *global_runq;
 205 static struct run_queue global_runq_storage;
 206
 207 #define GLOBAL_RUNQ             ((processor_t)-2)
 208 decl_simple_lock_data(static, global_runq_lock);
 209
 210 extern int      max_unsafe_quanta;
 211
 212 static uint32_t proto_quantum_us;
 213 static uint32_t proto_quantum;
 214
 215 static uint32_t runqueue_generation;
 216
 217 static processor_t proto_processor;
 218
 219 static uint64_t                 sched_proto_tick_deadline;
 220 static uint32_t                 sched_proto_tick;
 221
 222 static void
 223 sched_proto_init(void)
 224 {
 225         proto_quantum_us = 10 * 1000;
 226
 227         printf("standard proto timeslicing quantum is %d us\n", proto_quantum_us);
 228
 229         simple_lock_init(&global_runq_lock, 0);
 230         global_runq = &global_runq_storage;
 231         run_queue_init(global_runq);
 232         runqueue_generation = 0;
 233
 234         proto_processor = master_processor;
 235 }
 236
 237 static void
 238 sched_proto_timebase_init(void)
 239 {
 240         uint64_t        abstime;
 241
 242         /* standard timeslicing quantum */
 243         clock_interval_to_absolutetime_interval(
 244                 proto_quantum_us, NSEC_PER_USEC, &abstime);
 245         assert((abstime >> 32) == 0 && (uint32_t)abstime != 0);
 246         proto_quantum = (uint32_t)abstime;
 247
 248         thread_depress_time = 1 * proto_quantum;
 249         default_timeshare_computation = proto_quantum / 2;
 250         default_timeshare_constraint = proto_quantum;
 251
 252         max_unsafe_computation = max_unsafe_quanta * proto_quantum;
 253         sched_safe_duration = 2 * max_unsafe_quanta * proto_quantum;
 254 }
 255
 256 static void
 257 sched_proto_processor_init(processor_t processor __unused)
 258 {
 259         /* No per-processor state */
 260 }
 261
 262 static void
 263 sched_proto_pset_init(processor_set_t pset __unused)
 264 {
 265 }
 266
 267 static void
 268 sched_proto_maintenance_continuation(void)
 269 {
 270         uint64_t                        abstime = mach_absolute_time();
 271
 272         sched_proto_tick++;
 273
 274         /* Every 8 seconds, switch to another processor */
 275         if ((sched_proto_tick & 0x7) == 0) {
 276                 processor_t new_processor;
 277
 278                 new_processor = proto_processor->processor_list;
 279                 if (new_processor == PROCESSOR_NULL) {
 280                         proto_processor = master_processor;
 281                 } else {
 282                         proto_processor = new_processor;
 283                 }
 284         }
 285
 286
 287         /*
 288          *  Compute various averages.
 289          */
 290         compute_averages(1);
 291
 292         if (sched_proto_tick_deadline == 0) {
 293                 sched_proto_tick_deadline = abstime;
 294         }
 295
 296         clock_deadline_for_periodic_event(sched_one_second_interval, abstime,
 297             &sched_proto_tick_deadline);
 298
 299         assert_wait_deadline((event_t)sched_proto_maintenance_continuation, THREAD_UNINT, sched_proto_tick_deadline);
 300         thread_block((thread_continue_t)sched_proto_maintenance_continuation);
 301         /*NOTREACHED*/
 302 }
 303
 304 static thread_t
 305 sched_proto_choose_thread(processor_t           processor,
 306     int                           priority,
 307     ast_t                         reason __unused)
 308 {
 309         run_queue_t             rq = global_runq;
 310         queue_t                 queue;
 311         int                             pri, count;
 312         thread_t                thread;
 313
 314
 315         simple_lock(&global_runq_lock, LCK_GRP_NULL);
 316
 317         queue = rq->queues + rq->highq;
 318         pri = rq->highq;
 319         count = rq->count;
 320
 321         /*
 322          * Since we don't depress priorities, a high priority thread
 323          * may get selected over and over again. Put a runqueue
 324          * generation number in the thread structure so that we
 325          * can ensure that we've cycled through all runnable tasks
 326          * before coming back to a high priority thread. This isn't
 327          * perfect, especially if the number of runnable threads always
 328          * stays high, but is a workable approximation
 329          */
 330
 331         while (count > 0 && pri >= priority) {
 332                 thread = (thread_t)queue_first(queue);
 333                 while (!queue_end(queue, (queue_entry_t)thread)) {
 334                         if ((thread->bound_processor == PROCESSOR_NULL ||
 335                             thread->bound_processor == processor) &&
 336                             runqueue_generation != thread->runqueue_generation) {
 337                                 remqueue((queue_entry_t)thread);
 338
 339                                 thread->runq = PROCESSOR_NULL;
 340                                 thread->runqueue_generation = runqueue_generation;
 341                                 SCHED_STATS_RUNQ_CHANGE(&rq->runq_stats, rq->count);
 342                                 rq->count--;
 343                                 if (queue_empty(queue)) {
 344                                         bitmap_clear(rq->bitmap, pri);
 345                                         rq->highq = bitmap_first(rq->bitmap, NRQS);
 346                                 }
 347
 348                                 simple_unlock(&global_runq_lock);
 349                                 return thread;
 350                         }
 351                         count--;
 352
 353                         thread = (thread_t)queue_next((queue_entry_t)thread);
 354                 }
 355
 356                 queue--; pri--;
 357         }
 358
 359         runqueue_generation++;
 360
 361         simple_unlock(&global_runq_lock);
 362         return THREAD_NULL;
 363 }
 364
 365 static thread_t
 366 sched_proto_steal_thread(processor_set_t                pset)
 367 {
 368         pset_unlock(pset);
 369
 370         return THREAD_NULL;
 371 }
 372
 373 static int
 374 sched_proto_compute_priority(thread_t thread)
 375 {
 376         return thread->base_pri;
 377 }
 378
 379 static processor_t
 380 sched_proto_choose_processor(   processor_set_t         pset,
 381     processor_t                    processor,
 382     thread_t                       thread __unused)
 383 {
 384         processor = proto_processor;
 385
 386         /*
 387          *      Check that the correct processor set is
 388          *      returned locked.
 389          */
 390         if (pset != processor->processor_set) {
 391                 pset_unlock(pset);
 392
 393                 pset = processor->processor_set;
 394                 pset_lock(pset);
 395         }
 396
 397         return processor;
 398 }
 399
 400 static boolean_t
 401 sched_proto_processor_enqueue(
 402         processor_t                    processor __unused,
 403         thread_t                       thread,
 404         integer_t                      options)
 405 {
 406         run_queue_t             rq = global_runq;
 407         boolean_t               result;
 408
 409         simple_lock(&global_runq_lock, LCK_GRP_NULL);
 410         result = run_queue_enqueue(rq, thread, options);
 411         thread->runq = GLOBAL_RUNQ;
 412         simple_unlock(&global_runq_lock);
 413
 414         return result;
 415 }
 416
 417 static void
 418 sched_proto_processor_queue_shutdown(
 419         processor_t                    processor)
 420 {
 421         /* With a global runqueue, just stop choosing this processor */
 422         (void)processor;
 423 }
 424
 425 static boolean_t
 426 sched_proto_processor_queue_remove(
 427         processor_t                     processor,
 428         thread_t                thread)
 429 {
 430         void *                  rqlock;
 431         run_queue_t             rq;
 432
 433         rqlock = &global_runq_lock;
 434         rq = global_runq;
 435
 436         simple_lock(rqlock, LCK_GRP_NULL);
 437         if (processor == thread->runq) {
 438                 /*
 439                  *      Thread is on a run queue and we have a lock on
 440                  *      that run queue.
 441                  */
 442                 remqueue((queue_entry_t)thread);
 443                 SCHED_STATS_RUNQ_CHANGE(&rq->runq_stats, rq->count);
 444                 rq->count--;
 445                 if (SCHED(priority_is_urgent)(thread->sched_pri)) {
 446                         rq->urgency--; assert(rq->urgency >= 0);
 447                 }
 448
 449                 if (queue_empty(rq->queues + thread->sched_pri)) {
 450                         /* update run queue status */
 451                         bitmap_clear(rq->bitmap, thread->sched_pri);
 452                         rq->highq = bitmap_first(rq->bitmap, NRQS);
 453                 }
 454
 455                 thread->runq = PROCESSOR_NULL;
 456         } else {
 457                 /*
 458                  *      The thread left the run queue before we could
 459                  *      lock the run queue.
 460                  */
 461                 assert(thread->runq == PROCESSOR_NULL);
 462                 processor = PROCESSOR_NULL;
 463         }
 464
 465         simple_unlock(rqlock);
 466
 467         return processor != PROCESSOR_NULL;
 468 }
 469
 470 static boolean_t
 471 sched_proto_processor_queue_empty(processor_t           processor __unused)
 472 {
 473         boolean_t result;
 474
 475         result = (global_runq->count == 0);
 476
 477         return result;
 478 }
 479
 480 static boolean_t
 481 sched_proto_processor_queue_has_priority(processor_t            processor __unused,
 482     int                            priority,
 483     boolean_t              gte)
 484 {
 485         boolean_t result;
 486
 487         simple_lock(&global_runq_lock, LCK_GRP_NULL);
 488
 489         if (gte) {
 490                 result = global_runq->highq >= priority;
 491         } else {
 492                 result = global_runq->highq > priority;
 493         }
 494
 495         simple_unlock(&global_runq_lock);
 496
 497         return result;
 498 }
 499
 500 /* Implement sched_preempt_pri in code */
 501 static boolean_t
 502 sched_proto_priority_is_urgent(int priority)
 503 {
 504         if (priority <= BASEPRI_FOREGROUND) {
 505                 return FALSE;
 506         }
 507
 508         if (priority < MINPRI_KERNEL) {
 509                 return TRUE;
 510         }
 511
 512         if (priority >= BASEPRI_PREEMPT) {
 513                 return TRUE;
 514         }
 515
 516         return FALSE;
 517 }
 518
 519 static ast_t
 520 sched_proto_processor_csw_check(processor_t processor)
 521 {
 522         run_queue_t             runq;
 523         int                             count, urgency;
 524
 525         runq = global_runq;
 526         count = runq->count;
 527         urgency = runq->urgency;
 528
 529         if (count > 0) {
 530                 if (urgency > 0) {
 531                         return AST_PREEMPT | AST_URGENT;
 532                 }
 533
 534                 return AST_PREEMPT;
 535         }
 536
 537         if (proto_processor != processor) {
 538                 return AST_PREEMPT;
 539         }
 540
 541         return AST_NONE;
 542 }
 543
 544 static uint32_t
 545 sched_proto_initial_quantum_size(thread_t thread __unused)
 546 {
 547         return proto_quantum;
 548 }
 549
 550 static sched_mode_t
 551 sched_proto_initial_thread_sched_mode(task_t parent_task)
 552 {
 553         if (parent_task == kernel_task) {
 554                 return TH_MODE_FIXED;
 555         } else {
 556                 return TH_MODE_TIMESHARE;
 557         }
 558 }
 559
 560 static boolean_t
 561 sched_proto_can_update_priority(thread_t        thread __unused)
 562 {
 563         return FALSE;
 564 }
 565
 566 static void
 567 sched_proto_update_priority(thread_t    thread __unused)
 568 {
 569 }
 570
 571 static void
 572 sched_proto_lightweight_update_priority(thread_t        thread __unused)
 573 {
 574 }
 575
 576 static void
 577 sched_proto_quantum_expire(thread_t    thread __unused)
 578 {
 579 }
 580
 581 static int
 582 sched_proto_processor_runq_count(processor_t   processor)
 583 {
 584         if (master_processor == processor) {
 585                 return global_runq->count;
 586         } else {
 587                 return 0;
 588         }
 589 }
 590
 591 static uint64_t
 592 sched_proto_processor_runq_stats_count_sum(processor_t   processor)
 593 {
 594         if (master_processor == processor) {
 595                 return global_runq->runq_stats.count_sum;
 596         } else {
 597                 return 0ULL;
 598         }
 599 }
 600
 601 static int
 602 sched_proto_processor_bound_count(__unused processor_t   processor)
 603 {
 604         return 0;
 605 }
 606
 607 static void
 608 sched_proto_thread_update_scan(__unused sched_update_scan_context_t scan_context)
 609 {
 610 }