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/lock.h>
  46 #include <kern/macro_help.h>
  47 #include <kern/machine.h>
  48 #include <kern/misc_protos.h>
  49 #include <kern/processor.h>
  50 #include <kern/queue.h>
  51 #include <kern/sched.h>
  52 #include <kern/sched_prim.h>
  53 #include <kern/syscall_subr.h>
  54 #include <kern/task.h>
  55 #include <kern/thread.h>
  56 #include <kern/wait_queue.h>
  57
  58 #include <vm/pmap.h>
  59 #include <vm/vm_kern.h>
  60 #include <vm/vm_map.h>
  61
  62 #include <mach/sdt.h>
  63
  64 #include <sys/kdebug.h>
  65
  66 static void
  67 sched_proto_init(void);
  68
  69 static void
  70 sched_proto_timebase_init(void);
  71
  72 static void
  73 sched_proto_processor_init(processor_t processor);
  74
  75 static void
  76 sched_proto_pset_init(processor_set_t pset);
  77
  78 static void
  79 sched_proto_maintenance_continuation(void);
  80
  81 static thread_t
  82 sched_proto_choose_thread(processor_t           processor,
  83                                                          int                            priority);
  84
  85 static thread_t
  86 sched_proto_steal_thread(processor_set_t                pset);
  87
  88 static void
  89 sched_proto_compute_priority(thread_t   thread,
  90                                                          boolean_t                      override_depress);
  91
  92 static processor_t
  93 sched_proto_choose_processor(   processor_set_t         pset,
  94                                                                 processor_t                     processor,
  95                                                                 thread_t                        thread);
  96
  97
  98 static boolean_t
  99 sched_proto_processor_enqueue(
 100                                                          processor_t                    processor,
 101                                                          thread_t                       thread,
 102                                                          integer_t                      options);
 103
 104 static void
 105 sched_proto_processor_queue_shutdown(
 106                                                                          processor_t                    processor);
 107
 108 static boolean_t
 109 sched_proto_processor_queue_remove(
 110                                                     processor_t                 processor,
 111                                                         thread_t                thread);
 112
 113 static boolean_t
 114 sched_proto_processor_queue_empty(processor_t           processor);
 115
 116 static boolean_t
 117 sched_proto_processor_queue_has_priority(processor_t            processor,
 118                                                                                  int                            priority,
 119                                                                                  boolean_t              gte);
 120
 121 static boolean_t
 122 sched_proto_priority_is_urgent(int priority);
 123
 124 static ast_t
 125 sched_proto_processor_csw_check(processor_t processor);
 126
 127 static uint32_t
 128 sched_proto_initial_quantum_size(thread_t thread);
 129
 130 static sched_mode_t
 131 sched_proto_initial_thread_sched_mode(task_t parent_task);
 132
 133 static boolean_t
 134 sched_proto_supports_timeshare_mode(void);
 135
 136 static boolean_t
 137 sched_proto_can_update_priority(thread_t        thread);
 138
 139 static void
 140 sched_proto_update_priority(thread_t    thread);
 141
 142 static void
 143 sched_proto_lightweight_update_priority(thread_t        thread);
 144
 145 static void
 146 sched_proto_quantum_expire(thread_t     thread);
 147
 148 static boolean_t
 149 sched_proto_should_current_thread_rechoose_processor(processor_t                        processor);
 150
 151 static int
 152 sched_proto_processor_runq_count(processor_t   processor);
 153
 154 static uint64_t
 155 sched_proto_processor_runq_stats_count_sum(processor_t   processor);
 156
 157 const struct sched_dispatch_table sched_proto_dispatch = {
 158         sched_proto_init,
 159         sched_proto_timebase_init,
 160         sched_proto_processor_init,
 161         sched_proto_pset_init,
 162         sched_proto_maintenance_continuation,
 163         sched_proto_choose_thread,
 164         sched_proto_steal_thread,
 165         sched_proto_compute_priority,
 166         sched_proto_choose_processor,
 167         sched_proto_processor_enqueue,
 168         sched_proto_processor_queue_shutdown,
 169         sched_proto_processor_queue_remove,
 170         sched_proto_processor_queue_empty,
 171         sched_proto_priority_is_urgent,
 172         sched_proto_processor_csw_check,
 173         sched_proto_processor_queue_has_priority,
 174         sched_proto_initial_quantum_size,
 175         sched_proto_initial_thread_sched_mode,
 176         sched_proto_supports_timeshare_mode,
 177         sched_proto_can_update_priority,
 178         sched_proto_update_priority,
 179         sched_proto_lightweight_update_priority,
 180         sched_proto_quantum_expire,
 181         sched_proto_should_current_thread_rechoose_processor,
 182         sched_proto_processor_runq_count,
 183         sched_proto_processor_runq_stats_count_sum,
 184         sched_traditional_fairshare_init,
 185         sched_traditional_fairshare_runq_count,
 186         sched_traditional_fairshare_runq_stats_count_sum,
 187         sched_traditional_fairshare_enqueue,
 188         sched_traditional_fairshare_dequeue,
 189         sched_traditional_fairshare_queue_remove,
 190         TRUE /* direct_dispatch_to_idle_processors */
 191 };
 192
 193 static struct run_queue *global_runq;
 194 static struct run_queue global_runq_storage;
 195
 196 #define GLOBAL_RUNQ             ((processor_t)-2)
 197 decl_simple_lock_data(static,global_runq_lock);
 198
 199 extern int      max_unsafe_quanta;
 200
 201 static uint32_t proto_quantum_us;
 202 static uint32_t proto_quantum;
 203
 204 static uint32_t runqueue_generation;
 205
 206 static processor_t proto_processor;
 207
 208 static uint64_t                 sched_proto_tick_deadline;
 209 static uint32_t                 sched_proto_tick;
 210
 211 static void
 212 sched_proto_init(void)
 213 {
 214         proto_quantum_us = 10*1000;
 215
 216         printf("standard proto timeslicing quantum is %d us\n", proto_quantum_us);
 217
 218         simple_lock_init(&global_runq_lock, 0);
 219         global_runq = &global_runq_storage;
 220         run_queue_init(global_runq);
 221         runqueue_generation = 0;
 222
 223         proto_processor = master_processor;
 224 }
 225
 226 static void
 227 sched_proto_timebase_init(void)
 228 {
 229         uint64_t        abstime;
 230
 231         /* standard timeslicing quantum */
 232         clock_interval_to_absolutetime_interval(
 233                                                                                         proto_quantum_us, NSEC_PER_USEC, &abstime);
 234         assert((abstime >> 32) == 0 && (uint32_t)abstime != 0);
 235         proto_quantum = (uint32_t)abstime;
 236
 237         thread_depress_time = 1 * proto_quantum;
 238         default_timeshare_computation = proto_quantum / 2;
 239         default_timeshare_constraint = proto_quantum;
 240
 241         max_unsafe_computation = max_unsafe_quanta * proto_quantum;
 242         sched_safe_duration = 2 * max_unsafe_quanta * proto_quantum;
 243
 244 }
 245
 246 static void
 247 sched_proto_processor_init(processor_t processor __unused)
 248 {
 249         /* No per-processor state */
 250 }
 251
 252 static void
 253 sched_proto_pset_init(processor_set_t pset __unused)
 254 {
 255 }
 256
 257 static void
 258 sched_proto_maintenance_continuation(void)
 259 {
 260         uint64_t                        abstime = mach_absolute_time();
 261
 262         sched_proto_tick++;
 263
 264         /* Every 8 seconds, switch to another processor */
 265         if ((sched_proto_tick & 0x7) == 0) {
 266                 processor_t new_processor;
 267
 268                 new_processor = proto_processor->processor_list;
 269                 if (new_processor == PROCESSOR_NULL)
 270                         proto_processor = master_processor;
 271                 else
 272                         proto_processor = new_processor;
 273         }
 274
 275
 276         /*
 277          *  Compute various averages.
 278          */
 279         compute_averages(1);
 280
 281         if (sched_proto_tick_deadline == 0)
 282                 sched_proto_tick_deadline = abstime;
 283
 284         clock_deadline_for_periodic_event(sched_one_second_interval, abstime,
 285                                                 &sched_proto_tick_deadline);
 286
 287         assert_wait_deadline((event_t)sched_proto_maintenance_continuation, THREAD_UNINT, sched_proto_tick_deadline);
 288         thread_block((thread_continue_t)sched_proto_maintenance_continuation);
 289         /*NOTREACHED*/
 290 }
 291
 292 static thread_t
 293 sched_proto_choose_thread(processor_t           processor,
 294                                                   int                           priority)
 295 {
 296         run_queue_t             rq = global_runq;
 297         queue_t                 queue;
 298         int                             pri, count;
 299         thread_t                thread;
 300
 301
 302         simple_lock(&global_runq_lock);
 303
 304         queue = rq->queues + rq->highq;
 305         pri = rq->highq;
 306         count = rq->count;
 307
 308         /*
 309          * Since we don't depress priorities, a high priority thread
 310          * may get selected over and over again. Put a runqueue
 311          * generation number in the thread structure so that we
 312          * can ensure that we've cycled through all runnable tasks
 313          * before coming back to a high priority thread. This isn't
 314          * perfect, especially if the number of runnable threads always
 315          * stays high, but is a workable approximation
 316          */
 317
 318         while (count > 0 && pri >= priority) {
 319                 thread = (thread_t)queue_first(queue);
 320                 while (!queue_end(queue, (queue_entry_t)thread)) {
 321                         if ((thread->bound_processor == PROCESSOR_NULL ||
 322                                 thread->bound_processor == processor) &&
 323                                 runqueue_generation != thread->runqueue_generation) {
 324                                 remqueue((queue_entry_t)thread);
 325
 326                                 thread->runq = PROCESSOR_NULL;
 327                                 thread->runqueue_generation = runqueue_generation;
 328                                 SCHED_STATS_RUNQ_CHANGE(&rq->runq_stats, rq->count);
 329                                 rq->count--;
 330                                 if (queue_empty(queue)) {
 331                                         if (pri != IDLEPRI)
 332                                                 clrbit(MAXPRI - pri, rq->bitmap);
 333                                         rq->highq = MAXPRI - ffsbit(rq->bitmap);
 334                                 }
 335
 336                                 simple_unlock(&global_runq_lock);
 337                                 return (thread);
 338                         }
 339                         count--;
 340
 341                         thread = (thread_t)queue_next((queue_entry_t)thread);
 342                 }
 343
 344                 queue--; pri--;
 345         }
 346
 347         runqueue_generation++;
 348
 349         simple_unlock(&global_runq_lock);
 350         return (THREAD_NULL);
 351 }
 352
 353 static thread_t
 354 sched_proto_steal_thread(processor_set_t                pset)
 355 {
 356         pset_unlock(pset);
 357
 358         return (THREAD_NULL);
 359
 360 }
 361
 362 static void
 363 sched_proto_compute_priority(thread_t   thread,
 364                                                          boolean_t                      override_depress __unused)
 365 {
 366         set_sched_pri(thread, thread->priority);
 367 }
 368
 369 static processor_t
 370 sched_proto_choose_processor(   processor_set_t         pset,
 371                                                          processor_t                    processor,
 372                                                          thread_t                       thread __unused)
 373 {
 374         processor = proto_processor;
 375
 376         /*
 377          *      Check that the correct processor set is
 378          *      returned locked.
 379          */
 380         if (pset != processor->processor_set) {
 381                 pset_unlock(pset);
 382
 383                 pset = processor->processor_set;
 384                 pset_lock(pset);
 385         }
 386
 387         return (processor);
 388 }
 389
 390 static boolean_t
 391 sched_proto_processor_enqueue(
 392                                                          processor_t                    processor __unused,
 393                                                          thread_t                       thread,
 394                                                          integer_t                      options)
 395 {
 396         run_queue_t             rq = global_runq;
 397         boolean_t               result;
 398
 399         simple_lock(&global_runq_lock);
 400         result = run_queue_enqueue(rq, thread, options);
 401         thread->runq = GLOBAL_RUNQ;
 402         simple_unlock(&global_runq_lock);
 403
 404         return (result);
 405 }
 406
 407 static void
 408 sched_proto_processor_queue_shutdown(
 409                                                                          processor_t                    processor)
 410 {
 411         /* With a global runqueue, just stop choosing this processor */
 412         (void)processor;
 413 }
 414
 415 static boolean_t
 416 sched_proto_processor_queue_remove(
 417                                                                 processor_t                     processor,
 418                                                                 thread_t                thread)
 419 {
 420         void *                  rqlock;
 421         run_queue_t             rq;
 422
 423         rqlock = &global_runq_lock;
 424         rq = global_runq;
 425
 426         simple_lock(rqlock);
 427         if (processor == thread->runq) {
 428                 /*
 429                  *      Thread is on a run queue and we have a lock on
 430                  *      that run queue.
 431                  */
 432                 remqueue((queue_entry_t)thread);
 433                 SCHED_STATS_RUNQ_CHANGE(&rq->runq_stats, rq->count);
 434                 rq->count--;
 435                 if (SCHED(priority_is_urgent)(thread->sched_pri)) {
 436                         rq->urgency--; assert(rq->urgency >= 0);
 437                 }
 438
 439                 if (queue_empty(rq->queues + thread->sched_pri)) {
 440                         /* update run queue status */
 441                         if (thread->sched_pri != IDLEPRI)
 442                                 clrbit(MAXPRI - thread->sched_pri, rq->bitmap);
 443                         rq->highq = MAXPRI - ffsbit(rq->bitmap);
 444                 }
 445
 446                 thread->runq = PROCESSOR_NULL;
 447         }
 448         else {
 449                 /*
 450                  *      The thread left the run queue before we could
 451                  *      lock the run queue.
 452                  */
 453                 assert(thread->runq == PROCESSOR_NULL);
 454                 processor = PROCESSOR_NULL;
 455         }
 456
 457         simple_unlock(rqlock);
 458
 459         return (processor != PROCESSOR_NULL);
 460 }
 461
 462 static boolean_t
 463 sched_proto_processor_queue_empty(processor_t           processor __unused)
 464 {
 465         boolean_t result;
 466
 467         result = (global_runq->count == 0);
 468
 469         return result;
 470 }
 471
 472 static boolean_t
 473 sched_proto_processor_queue_has_priority(processor_t            processor __unused,
 474                                                                                  int                            priority,
 475                                                                                  boolean_t              gte)
 476 {
 477         boolean_t result;
 478
 479         simple_lock(&global_runq_lock);
 480
 481         if (gte)
 482                 result = global_runq->highq >= priority;
 483         else
 484                 result = global_runq->highq >= priority;
 485
 486         simple_unlock(&global_runq_lock);
 487
 488         return result;
 489 }
 490
 491 /* Implement sched_preempt_pri in code */
 492 static boolean_t
 493 sched_proto_priority_is_urgent(int priority)
 494 {
 495         if (priority <= BASEPRI_FOREGROUND)
 496                 return FALSE;
 497
 498         if (priority < MINPRI_KERNEL)
 499                 return TRUE;
 500
 501         if (priority >= BASEPRI_PREEMPT)
 502                 return TRUE;
 503
 504         return FALSE;
 505 }
 506
 507 static ast_t
 508 sched_proto_processor_csw_check(processor_t processor __unused)
 509 {
 510         run_queue_t             runq;
 511         int                             count, urgency;
 512
 513         runq = global_runq;
 514         count = runq->count;
 515         urgency = runq->urgency;
 516
 517         if (count > 0) {
 518                 if (urgency > 0)
 519                         return (AST_PREEMPT | AST_URGENT);
 520
 521                 return AST_PREEMPT;
 522         }
 523
 524         return AST_NONE;
 525 }
 526
 527 static uint32_t
 528 sched_proto_initial_quantum_size(thread_t thread __unused)
 529 {
 530         return proto_quantum;
 531 }
 532
 533 static sched_mode_t
 534 sched_proto_initial_thread_sched_mode(task_t parent_task)
 535 {
 536         if (parent_task == kernel_task)
 537                 return TH_MODE_FIXED;
 538         else
 539                 return TH_MODE_TIMESHARE;
 540 }
 541
 542 static boolean_t
 543 sched_proto_supports_timeshare_mode(void)
 544 {
 545         return TRUE;
 546 }
 547
 548 static boolean_t
 549 sched_proto_can_update_priority(thread_t        thread __unused)
 550 {
 551         return FALSE;
 552 }
 553
 554 static void
 555 sched_proto_update_priority(thread_t    thread __unused)
 556 {
 557
 558 }
 559
 560 static void
 561 sched_proto_lightweight_update_priority(thread_t        thread __unused)
 562 {
 563
 564 }
 565
 566 static void
 567 sched_proto_quantum_expire(thread_t     thread __unused)
 568 {
 569
 570 }
 571
 572 static boolean_t
 573 sched_proto_should_current_thread_rechoose_processor(processor_t                        processor)
 574 {
 575         return (proto_processor != processor);
 576 }
 577
 578 static int
 579 sched_proto_processor_runq_count(processor_t   processor)
 580 {
 581         if (master_processor == processor) {
 582                 return global_runq->count;
 583         } else {
 584                 return 0;
 585         }
 586 }
 587
 588 static uint64_t
 589 sched_proto_processor_runq_stats_count_sum(processor_t   processor)
 590 {
 591         if (master_processor == processor) {
 592                 return global_runq->runq_stats.count_sum;
 593         } else {
 594                 return 0ULL;
 595         }
 596 }
 597