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                           = FALSE,
 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 };
 189
 190 static struct run_queue *global_runq;
 191 static struct run_queue global_runq_storage;
 192
 193 #define GLOBAL_RUNQ             ((processor_t)-2)
 194 decl_simple_lock_data(static,global_runq_lock);
 195
 196 extern int      max_unsafe_quanta;
 197
 198 static uint32_t proto_quantum_us;
 199 static uint32_t proto_quantum;
 200
 201 static uint32_t runqueue_generation;
 202
 203 static processor_t proto_processor;
 204
 205 static uint64_t                 sched_proto_tick_deadline;
 206 static uint32_t                 sched_proto_tick;
 207
 208 static void
 209 sched_proto_init(void)
 210 {
 211         proto_quantum_us = 10*1000;
 212
 213         printf("standard proto timeslicing quantum is %d us\n", proto_quantum_us);
 214
 215         simple_lock_init(&global_runq_lock, 0);
 216         global_runq = &global_runq_storage;
 217         run_queue_init(global_runq);
 218         runqueue_generation = 0;
 219
 220         proto_processor = master_processor;
 221 }
 222
 223 static void
 224 sched_proto_timebase_init(void)
 225 {
 226         uint64_t        abstime;
 227
 228         /* standard timeslicing quantum */
 229         clock_interval_to_absolutetime_interval(
 230                                                                                         proto_quantum_us, NSEC_PER_USEC, &abstime);
 231         assert((abstime >> 32) == 0 && (uint32_t)abstime != 0);
 232         proto_quantum = (uint32_t)abstime;
 233
 234         thread_depress_time = 1 * proto_quantum;
 235         default_timeshare_computation = proto_quantum / 2;
 236         default_timeshare_constraint = proto_quantum;
 237
 238         max_unsafe_computation = max_unsafe_quanta * proto_quantum;
 239         sched_safe_duration = 2 * max_unsafe_quanta * proto_quantum;
 240
 241 }
 242
 243 static void
 244 sched_proto_processor_init(processor_t processor __unused)
 245 {
 246         /* No per-processor state */
 247 }
 248
 249 static void
 250 sched_proto_pset_init(processor_set_t pset __unused)
 251 {
 252 }
 253
 254 static void
 255 sched_proto_maintenance_continuation(void)
 256 {
 257         uint64_t                        abstime = mach_absolute_time();
 258
 259         sched_proto_tick++;
 260
 261         /* Every 8 seconds, switch to another processor */
 262         if ((sched_proto_tick & 0x7) == 0) {
 263                 processor_t new_processor;
 264
 265                 new_processor = proto_processor->processor_list;
 266                 if (new_processor == PROCESSOR_NULL)
 267                         proto_processor = master_processor;
 268                 else
 269                         proto_processor = new_processor;
 270         }
 271
 272
 273         /*
 274          *  Compute various averages.
 275          */
 276         compute_averages(1);
 277
 278         if (sched_proto_tick_deadline == 0)
 279                 sched_proto_tick_deadline = abstime;
 280
 281         clock_deadline_for_periodic_event(sched_one_second_interval, abstime,
 282                                                 &sched_proto_tick_deadline);
 283
 284         assert_wait_deadline((event_t)sched_proto_maintenance_continuation, THREAD_UNINT, sched_proto_tick_deadline);
 285         thread_block((thread_continue_t)sched_proto_maintenance_continuation);
 286         /*NOTREACHED*/
 287 }
 288
 289 static thread_t
 290 sched_proto_choose_thread(processor_t           processor,
 291                                                   int                           priority,
 292                                                   ast_t                         reason __unused)
 293 {
 294         run_queue_t             rq = global_runq;
 295         queue_t                 queue;
 296         int                             pri, count;
 297         thread_t                thread;
 298
 299
 300         simple_lock(&global_runq_lock);
 301
 302         queue = rq->queues + rq->highq;
 303         pri = rq->highq;
 304         count = rq->count;
 305
 306         /*
 307          * Since we don't depress priorities, a high priority thread
 308          * may get selected over and over again. Put a runqueue
 309          * generation number in the thread structure so that we
 310          * can ensure that we've cycled through all runnable tasks
 311          * before coming back to a high priority thread. This isn't
 312          * perfect, especially if the number of runnable threads always
 313          * stays high, but is a workable approximation
 314          */
 315
 316         while (count > 0 && pri >= priority) {
 317                 thread = (thread_t)queue_first(queue);
 318                 while (!queue_end(queue, (queue_entry_t)thread)) {
 319                         if ((thread->bound_processor == PROCESSOR_NULL ||
 320                                 thread->bound_processor == processor) &&
 321                                 runqueue_generation != thread->runqueue_generation) {
 322                                 remqueue((queue_entry_t)thread);
 323
 324                                 thread->runq = PROCESSOR_NULL;
 325                                 thread->runqueue_generation = runqueue_generation;
 326                                 SCHED_STATS_RUNQ_CHANGE(&rq->runq_stats, rq->count);
 327                                 rq->count--;
 328                                 if (queue_empty(queue)) {
 329                                         if (pri != IDLEPRI)
 330                                                 clrbit(MAXPRI - pri, rq->bitmap);
 331                                         rq->highq = MAXPRI - ffsbit(rq->bitmap);
 332                                 }
 333
 334                                 simple_unlock(&global_runq_lock);
 335                                 return (thread);
 336                         }
 337                         count--;
 338
 339                         thread = (thread_t)queue_next((queue_entry_t)thread);
 340                 }
 341
 342                 queue--; pri--;
 343         }
 344
 345         runqueue_generation++;
 346
 347         simple_unlock(&global_runq_lock);
 348         return (THREAD_NULL);
 349 }
 350
 351 static thread_t
 352 sched_proto_steal_thread(processor_set_t                pset)
 353 {
 354         pset_unlock(pset);
 355
 356         return (THREAD_NULL);
 357
 358 }
 359
 360 static int
 361 sched_proto_compute_priority(thread_t thread)
 362 {
 363         return thread->base_pri;
 364 }
 365
 366 static processor_t
 367 sched_proto_choose_processor(   processor_set_t         pset,
 368                                                          processor_t                    processor,
 369                                                          thread_t                       thread __unused)
 370 {
 371         processor = proto_processor;
 372
 373         /*
 374          *      Check that the correct processor set is
 375          *      returned locked.
 376          */
 377         if (pset != processor->processor_set) {
 378                 pset_unlock(pset);
 379
 380                 pset = processor->processor_set;
 381                 pset_lock(pset);
 382         }
 383
 384         return (processor);
 385 }
 386
 387 static boolean_t
 388 sched_proto_processor_enqueue(
 389                                                          processor_t                    processor __unused,
 390                                                          thread_t                       thread,
 391                                                          integer_t                      options)
 392 {
 393         run_queue_t             rq = global_runq;
 394         boolean_t               result;
 395
 396         simple_lock(&global_runq_lock);
 397         result = run_queue_enqueue(rq, thread, options);
 398         thread->runq = GLOBAL_RUNQ;
 399         simple_unlock(&global_runq_lock);
 400
 401         return (result);
 402 }
 403
 404 static void
 405 sched_proto_processor_queue_shutdown(
 406                                                                          processor_t                    processor)
 407 {
 408         /* With a global runqueue, just stop choosing this processor */
 409         (void)processor;
 410 }
 411
 412 static boolean_t
 413 sched_proto_processor_queue_remove(
 414                                                                 processor_t                     processor,
 415                                                                 thread_t                thread)
 416 {
 417         void *                  rqlock;
 418         run_queue_t             rq;
 419
 420         rqlock = &global_runq_lock;
 421         rq = global_runq;
 422
 423         simple_lock(rqlock);
 424         if (processor == thread->runq) {
 425                 /*
 426                  *      Thread is on a run queue and we have a lock on
 427                  *      that run queue.
 428                  */
 429                 remqueue((queue_entry_t)thread);
 430                 SCHED_STATS_RUNQ_CHANGE(&rq->runq_stats, rq->count);
 431                 rq->count--;
 432                 if (SCHED(priority_is_urgent)(thread->sched_pri)) {
 433                         rq->urgency--; assert(rq->urgency >= 0);
 434                 }
 435
 436                 if (queue_empty(rq->queues + thread->sched_pri)) {
 437                         /* update run queue status */
 438                         if (thread->sched_pri != IDLEPRI)
 439                                 clrbit(MAXPRI - thread->sched_pri, rq->bitmap);
 440                         rq->highq = MAXPRI - ffsbit(rq->bitmap);
 441                 }
 442
 443                 thread->runq = PROCESSOR_NULL;
 444         }
 445         else {
 446                 /*
 447                  *      The thread left the run queue before we could
 448                  *      lock the run queue.
 449                  */
 450                 assert(thread->runq == PROCESSOR_NULL);
 451                 processor = PROCESSOR_NULL;
 452         }
 453
 454         simple_unlock(rqlock);
 455
 456         return (processor != PROCESSOR_NULL);
 457 }
 458
 459 static boolean_t
 460 sched_proto_processor_queue_empty(processor_t           processor __unused)
 461 {
 462         boolean_t result;
 463
 464         result = (global_runq->count == 0);
 465
 466         return result;
 467 }
 468
 469 static boolean_t
 470 sched_proto_processor_queue_has_priority(processor_t            processor __unused,
 471                                                                                  int                            priority,
 472                                                                                  boolean_t              gte)
 473 {
 474         boolean_t result;
 475
 476         simple_lock(&global_runq_lock);
 477
 478         if (gte)
 479                 result = global_runq->highq >= priority;
 480         else
 481                 result = global_runq->highq >= priority;
 482
 483         simple_unlock(&global_runq_lock);
 484
 485         return result;
 486 }
 487
 488 /* Implement sched_preempt_pri in code */
 489 static boolean_t
 490 sched_proto_priority_is_urgent(int priority)
 491 {
 492         if (priority <= BASEPRI_FOREGROUND)
 493                 return FALSE;
 494
 495         if (priority < MINPRI_KERNEL)
 496                 return TRUE;
 497
 498         if (priority >= BASEPRI_PREEMPT)
 499                 return TRUE;
 500
 501         return FALSE;
 502 }
 503
 504 static ast_t
 505 sched_proto_processor_csw_check(processor_t processor)
 506 {
 507         run_queue_t             runq;
 508         int                             count, urgency;
 509
 510         runq = global_runq;
 511         count = runq->count;
 512         urgency = runq->urgency;
 513
 514         if (count > 0) {
 515                 if (urgency > 0)
 516                         return (AST_PREEMPT | AST_URGENT);
 517
 518                 return AST_PREEMPT;
 519         }
 520
 521         if (proto_processor != processor)
 522                 return AST_PREEMPT;
 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_can_update_priority(thread_t        thread __unused)
 544 {
 545         return FALSE;
 546 }
 547
 548 static void
 549 sched_proto_update_priority(thread_t    thread __unused)
 550 {
 551
 552 }
 553
 554 static void
 555 sched_proto_lightweight_update_priority(thread_t        thread __unused)
 556 {
 557
 558 }
 559
 560 static void
 561 sched_proto_quantum_expire(thread_t    thread __unused)
 562 {
 563
 564 }
 565
 566 static int
 567 sched_proto_processor_runq_count(processor_t   processor)
 568 {
 569         if (master_processor == processor) {
 570                 return global_runq->count;
 571         } else {
 572                 return 0;
 573         }
 574 }
 575
 576 static uint64_t
 577 sched_proto_processor_runq_stats_count_sum(processor_t   processor)
 578 {
 579         if (master_processor == processor) {
 580                 return global_runq->runq_stats.count_sum;
 581         } else {
 582                 return 0ULL;
 583         }
 584 }
 585
 586 static int
 587 sched_proto_processor_bound_count(__unused processor_t   processor)
 588 {
 589         return 0;
 590 }
 591
 592 static void
 593 sched_proto_thread_update_scan(__unused sched_update_scan_context_t scan_context)
 594 {
 595
 596 }
 597
 598
 599