osfmk/kern/sched_prim.h

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  31 /*
  32  * Mach Operating System
  33  * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
  34  * All Rights Reserved.
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  36  * Permission to use, copy, modify and distribute this software and its
  37  * documentation is hereby granted, provided that both the copyright
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  39  * software, derivative works or modified versions, and any portions
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  44  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
  45  *
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  48  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  49  *  School of Computer Science
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  56 /*
  57  */
  58 /*
  59  *      File:   sched_prim.h
  60  *      Author: David Golub
  61  *
  62  *      Scheduling primitive definitions file
  63  *
  64  */
  65
  66 #ifndef _KERN_SCHED_PRIM_H_
  67 #define _KERN_SCHED_PRIM_H_
  68
  69 #include <mach/boolean.h>
  70 #include <mach/machine/vm_types.h>
  71 #include <mach/kern_return.h>
  72 #include <kern/clock.h>
  73 #include <kern/kern_types.h>
  74 #include <kern/thread.h>
  75 #include <sys/cdefs.h>
  76
  77 #ifdef  MACH_KERNEL_PRIVATE
  78
  79 #include <mach/branch_predicates.h>
  80
  81 /* Initialization */
  82 extern void             sched_init(void);
  83
  84 extern void             sched_startup(void);
  85
  86 extern void             sched_timebase_init(void);
  87
  88 /* Force a preemption point for a thread and wait for it to stop running */
  89 extern boolean_t        thread_stop(
  90                                                 thread_t        thread,
  91                                                 boolean_t       until_not_runnable);
  92
  93 /* Release a previous stop request */
  94 extern void                     thread_unstop(
  95                                                 thread_t        thread);
  96
  97 /* Wait for a thread to stop running */
  98 extern void                     thread_wait(
  99                                                 thread_t        thread,
 100                                                 boolean_t       until_not_runnable);
 101
 102 /* Unblock thread on wake up */
 103 extern boolean_t        thread_unblock(
 104                                                 thread_t                thread,
 105                                                 wait_result_t   wresult);
 106
 107 /* Unblock and dispatch thread */
 108 extern kern_return_t    thread_go(
 109                                                         thread_t                thread,
 110                                                         wait_result_t   wresult);
 111
 112 /* Handle threads at context switch */
 113 extern void                     thread_dispatch(
 114                                                 thread_t                old_thread,
 115                                                 thread_t                new_thread);
 116
 117 /* Switch directly to a particular thread */
 118 extern int                      thread_run(
 119                                                 thread_t                        self,
 120                                                 thread_continue_t       continuation,
 121                                                 void                            *parameter,
 122                                                 thread_t                        new_thread);
 123
 124 /* Resume thread with new stack */
 125 extern void                     thread_continue(
 126                                                 thread_t                old_thread);
 127
 128 /* Invoke continuation */
 129 extern void             call_continuation(
 130                                         thread_continue_t       continuation,
 131                                         void                            *parameter,
 132                                         wait_result_t           wresult);
 133
 134 /* Set the current scheduled priority */
 135 extern void             set_sched_pri(
 136                                         thread_t                thread,
 137                                         int                             priority);
 138
 139 /* Set base priority of the specified thread */
 140 extern void             sched_set_thread_base_priority(
 141                                         thread_t                thread,
 142                                         int                             priority);
 143
 144 /* Set the thread to be categorized as 'background' */
 145 extern void             sched_set_thread_throttled(thread_t thread,
 146                                                    boolean_t wants_throttle);
 147
 148 /* Set the thread's true scheduling mode */
 149 extern void             sched_set_thread_mode(thread_t thread,
 150                                               sched_mode_t mode);
 151 /* Demote the true scheduler mode */
 152 extern void             sched_thread_mode_demote(thread_t thread,
 153                                                  uint32_t reason);
 154 /* Un-demote the true scheduler mode */
 155 extern void             sched_thread_mode_undemote(thread_t thread,
 156                                                    uint32_t reason);
 157
 158 /* Re-evaluate base priority of thread (thread locked) */
 159 void thread_recompute_priority(thread_t thread);
 160
 161 /* Re-evaluate base priority of thread (thread unlocked) */
 162 void thread_recompute_qos(thread_t thread);
 163
 164 /* Reset scheduled priority of thread */
 165 extern void             thread_recompute_sched_pri(
 166                                         thread_t                thread,
 167                                         boolean_t               override_depress);
 168
 169 /* Periodic scheduler activity */
 170 extern void             sched_init_thread(void (*)(void));
 171
 172 /* Perform sched_tick housekeeping activities */
 173 extern boolean_t                can_update_priority(
 174                                         thread_t                thread);
 175
 176 extern void             update_priority(
 177                                                                                         thread_t                thread);
 178
 179 extern void             lightweight_update_priority(
 180                                                                 thread_t                thread);
 181
 182 extern void             sched_default_quantum_expire(thread_t thread);
 183
 184 /* Idle processor thread */
 185 extern void             idle_thread(void);
 186
 187 extern kern_return_t    idle_thread_create(
 188                                                         processor_t             processor);
 189
 190 /* Continuation return from syscall */
 191 extern void     thread_syscall_return(
 192                         kern_return_t   ret);
 193
 194 /* Context switch */
 195 extern wait_result_t    thread_block_reason(
 196                                                         thread_continue_t       continuation,
 197                                                         void                            *parameter,
 198                                                         ast_t                           reason);
 199
 200 /* Reschedule thread for execution */
 201 extern void             thread_setrun(
 202                                         thread_t        thread,
 203                                         integer_t       options);
 204
 205 #define SCHED_TAILQ             1
 206 #define SCHED_HEADQ             2
 207 #define SCHED_PREEMPT   4
 208
 209 extern uintptr_t sched_thread_on_rt_queue;
 210 #define THREAD_ON_RT_RUNQ  ((processor_t)(uintptr_t)&sched_thread_on_rt_queue)
 211
 212 extern processor_set_t  task_choose_pset(
 213                                                         task_t                  task);
 214
 215 /* Bind the current thread to a particular processor */
 216 extern processor_t              thread_bind(
 217                                                         processor_t             processor);
 218
 219 /* Choose the best processor to run a thread */
 220 extern processor_t      choose_processor(
 221                                                                          processor_set_t                pset,
 222                                                                          processor_t                    processor,
 223                                                                          thread_t                       thread);
 224
 225
 226 extern void thread_quantum_init(
 227                                                                 thread_t thread);
 228
 229 extern void             run_queue_init(
 230                                         run_queue_t             runq);
 231
 232 extern thread_t run_queue_dequeue(
 233                                                           run_queue_t           runq,
 234                                                           integer_t             options);
 235
 236 extern boolean_t        run_queue_enqueue(
 237                                                           run_queue_t           runq,
 238                                                           thread_t                      thread,
 239                                                           integer_t             options);
 240
 241 extern void     run_queue_remove(
 242                                                                          run_queue_t            runq,
 243                                                                          thread_t                       thread);
 244
 245 struct sched_update_scan_context
 246 {
 247         uint64_t        earliest_bg_make_runnable_time;
 248         uint64_t        earliest_normal_make_runnable_time;
 249         uint64_t        earliest_rt_make_runnable_time;
 250 };
 251 typedef struct sched_update_scan_context *sched_update_scan_context_t;
 252
 253 #if defined(CONFIG_SCHED_TIMESHARE_CORE)
 254
 255 extern boolean_t        thread_update_add_thread(thread_t thread);
 256 extern void             thread_update_process_threads(void);
 257 extern boolean_t        runq_scan(run_queue_t runq, sched_update_scan_context_t scan_context);
 258
 259 extern void sched_timeshare_init(void);
 260 extern void sched_timeshare_timebase_init(void);
 261 extern void sched_timeshare_maintenance_continue(void);
 262
 263 extern boolean_t priority_is_urgent(int priority);
 264 extern uint32_t sched_timeshare_initial_quantum_size(thread_t thread);
 265
 266 extern int sched_compute_timeshare_priority(thread_t thread);
 267
 268 #endif /* CONFIG_SCHED_TIMESHARE_CORE */
 269
 270 extern void        rt_runq_scan(sched_update_scan_context_t scan_context);
 271
 272 /* Remove thread from its run queue */
 273 extern boolean_t        thread_run_queue_remove(thread_t thread);
 274 thread_t thread_run_queue_remove_for_handoff(thread_t thread);
 275
 276 /* Put a thread back in the run queue after being yanked */
 277 extern void thread_run_queue_reinsert(thread_t thread, integer_t options);
 278
 279 extern void             thread_timer_expire(
 280                                         void                    *thread,
 281                                         void                    *p1);
 282
 283 extern boolean_t        thread_eager_preemption(
 284                                                 thread_t thread);
 285
 286 extern boolean_t sched_generic_direct_dispatch_to_idle_processors;
 287
 288 /* Set the maximum interrupt level for the thread */
 289 __private_extern__ wait_interrupt_t thread_interrupt_level(
 290                                                 wait_interrupt_t interruptible);
 291
 292 __private_extern__ wait_result_t thread_mark_wait_locked(
 293                                                 thread_t                 thread,
 294                                                 wait_interrupt_t interruptible);
 295
 296 /* Wake up locked thread directly, passing result */
 297 __private_extern__ kern_return_t clear_wait_internal(
 298                                                 thread_t                thread,
 299                                                 wait_result_t   result);
 300
 301 extern void sched_stats_handle_csw(
 302                                                         processor_t processor,
 303                                                         int reasons,
 304                                                         int selfpri,
 305                                                         int otherpri);
 306
 307 extern void sched_stats_handle_runq_change(
 308                                                                         struct runq_stats *stats,
 309                                                                         int old_count);
 310
 311
 312
 313 #define SCHED_STATS_CSW(processor, reasons, selfpri, otherpri)          \
 314 do {                                                            \
 315         if (__builtin_expect(sched_stats_active, 0)) {  \
 316                 sched_stats_handle_csw((processor),             \
 317                                 (reasons), (selfpri), (otherpri));      \
 318         }                                                       \
 319 } while (0)
 320
 321
 322 #define SCHED_STATS_RUNQ_CHANGE(stats, old_count)               \
 323 do {                                                            \
 324         if (__builtin_expect(sched_stats_active, 0)) {  \
 325                 sched_stats_handle_runq_change((stats),         \
 326                                                                 (old_count));           \
 327         }                                                       \
 328 } while (0)
 329
 330 extern uint32_t sched_debug_flags;
 331 #define SCHED_DEBUG_FLAG_PLATFORM_TRACEPOINTS   0x00000001
 332 #define SCHED_DEBUG_FLAG_CHOOSE_PROCESSOR_TRACEPOINTS   0x00000002
 333
 334 #define SCHED_DEBUG_PLATFORM_KERNEL_DEBUG_CONSTANT(...) do {                                            \
 335                 if (__improbable(sched_debug_flags & SCHED_DEBUG_FLAG_PLATFORM_TRACEPOINTS)) { \
 336                         KERNEL_DEBUG_CONSTANT(__VA_ARGS__);                                                     \
 337                 }                                                                                                                               \
 338         } while(0)
 339
 340 #define SCHED_DEBUG_CHOOSE_PROCESSOR_KERNEL_DEBUG_CONSTANT(...) do {                                            \
 341                 if (__improbable(sched_debug_flags & SCHED_DEBUG_FLAG_CHOOSE_PROCESSOR_TRACEPOINTS)) { \
 342                         KERNEL_DEBUG_CONSTANT(__VA_ARGS__);                                                     \
 343                 }                                                                                                                               \
 344         } while(0)
 345
 346 #define THREAD_URGENCY_NONE             0       /* indicates that there is no currently runnable */
 347 #define THREAD_URGENCY_BACKGROUND       1       /* indicates that the thread is marked as a "background" thread */
 348 #define THREAD_URGENCY_NORMAL           2       /* indicates that the thread is marked as a "normal" thread */
 349 #define THREAD_URGENCY_REAL_TIME        3       /* indicates that the thread is marked as a "real-time" or urgent thread */
 350 #define THREAD_URGENCY_MAX              4       /* Marker */
 351 /* Returns the "urgency" of a thread (provided by scheduler) */
 352 extern int      thread_get_urgency(
 353                                         thread_t        thread,
 354                                         uint64_t        *rt_period,
 355                                         uint64_t        *rt_deadline);
 356
 357 /* Tells the "urgency" of the just scheduled thread (provided by CPU PM) */
 358 extern void     thread_tell_urgency(
 359                                         int             urgency,
 360                                         uint64_t        rt_period,
 361                                         uint64_t        rt_deadline,
 362                                         uint64_t        sched_latency,
 363                                     thread_t nthread);
 364
 365 /* Tells if there are "active" RT threads in the system (provided by CPU PM) */
 366 extern void     active_rt_threads(
 367                                         boolean_t       active);
 368
 369 #endif /* MACH_KERNEL_PRIVATE */
 370
 371 __BEGIN_DECLS
 372
 373 #ifdef  XNU_KERNEL_PRIVATE
 374
 375 extern boolean_t                assert_wait_possible(void);
 376
 377 /* Toggles a global override to turn off CPU Throttling */
 378 #define CPU_THROTTLE_DISABLE    0
 379 #define CPU_THROTTLE_ENABLE     1
 380 extern void     sys_override_cpu_throttle(int flag);
 381
 382 /*
 383  ****************** Only exported until BSD stops using ********************
 384  */
 385
 386 extern void                     thread_vm_bind_group_add(void);
 387
 388 /* Wake up thread directly, passing result */
 389 extern kern_return_t clear_wait(
 390                                                 thread_t                thread,
 391                                                 wait_result_t   result);
 392
 393 /* Start thread running */
 394 extern void             thread_bootstrap_return(void);
 395
 396 /* Return from exception (BSD-visible interface) */
 397 extern void             thread_exception_return(void) __dead2;
 398
 399 #define SCHED_STRING_MAX_LENGTH (48)
 400 /* String declaring the name of the current scheduler */
 401 extern char sched_string[SCHED_STRING_MAX_LENGTH];
 402
 403 extern kern_return_t sched_work_interval_notify(thread_t thread, uint64_t work_interval_id, uint64_t start, uint64_t finish, uint64_t deadline, uint64_t next_start, uint32_t flags);
 404
 405 #endif  /* XNU_KERNEL_PRIVATE */
 406
 407 /* Context switch */
 408 extern wait_result_t    thread_block(
 409                                                         thread_continue_t       continuation);
 410
 411 extern wait_result_t    thread_block_parameter(
 412                                                         thread_continue_t       continuation,
 413                                                         void                            *parameter);
 414
 415 /* Declare thread will wait on a particular event */
 416 extern wait_result_t    assert_wait(
 417                                                         event_t                         event,
 418                                                         wait_interrupt_t        interruptible);
 419
 420 /* Assert that the thread intends to wait with a timeout */
 421 extern wait_result_t    assert_wait_timeout(
 422                                                         event_t                         event,
 423                                                         wait_interrupt_t        interruptible,
 424                                                         uint32_t                        interval,
 425                                                         uint32_t                        scale_factor);
 426
 427 /* Assert that the thread intends to wait with an urgency, timeout and leeway */
 428 extern wait_result_t    assert_wait_timeout_with_leeway(
 429                                                         event_t                         event,
 430                                                         wait_interrupt_t        interruptible,
 431                                                         wait_timeout_urgency_t  urgency,
 432                                                         uint32_t                        interval,
 433                                                         uint32_t                        leeway,
 434                                                         uint32_t                        scale_factor);
 435
 436 extern wait_result_t    assert_wait_deadline(
 437                                                         event_t                         event,
 438                                                         wait_interrupt_t        interruptible,
 439                                                         uint64_t                        deadline);
 440
 441 /* Assert that the thread intends to wait with an urgency, deadline, and leeway */
 442 extern wait_result_t    assert_wait_deadline_with_leeway(
 443                                                         event_t                         event,
 444                                                         wait_interrupt_t        interruptible,
 445                                                         wait_timeout_urgency_t  urgency,
 446                                                         uint64_t                        deadline,
 447                                                         uint64_t                        leeway);
 448
 449 /* Wake up thread (or threads) waiting on a particular event */
 450 extern kern_return_t    thread_wakeup_prim(
 451                                                         event_t                         event,
 452                                                         boolean_t                       one_thread,
 453                                                         wait_result_t                   result);
 454
 455 extern kern_return_t    thread_wakeup_prim_internal(
 456                                                         event_t                         event,
 457                                                         boolean_t                       one_thread,
 458                                                         wait_result_t                   result,
 459                                                         int                             priority);
 460
 461
 462 #define thread_wakeup(x)                                        \
 463                         thread_wakeup_prim((x), FALSE, THREAD_AWAKENED)
 464 #define thread_wakeup_with_result(x, z)         \
 465                         thread_wakeup_prim((x), FALSE, (z))
 466 #define thread_wakeup_one(x)                            \
 467                         thread_wakeup_prim((x), TRUE, THREAD_AWAKENED)
 468
 469 #ifdef MACH_KERNEL_PRIVATE
 470 #define thread_wakeup_one_with_pri(x, pri)                              \
 471                         thread_wakeup_prim_internal((x), TRUE, THREAD_AWAKENED, pri)
 472 #endif
 473
 474 extern boolean_t                preemption_enabled(void);
 475
 476 #ifdef MACH_KERNEL_PRIVATE
 477
 478 /*
 479  * Scheduler algorithm indirection. If only one algorithm is
 480  * enabled at compile-time, a direction function call is used.
 481  * If more than one is enabled, calls are dispatched through
 482  * a function pointer table.
 483  */
 484
 485 #if   !defined(CONFIG_SCHED_TRADITIONAL) && !defined(CONFIG_SCHED_PROTO) && !defined(CONFIG_SCHED_GRRR) && !defined(CONFIG_SCHED_MULTIQ)
 486 #error Enable at least one scheduler algorithm in osfmk/conf/MASTER.XXX
 487 #endif
 488
 489 #define SCHED(f) (sched_current_dispatch->f)
 490
 491 struct sched_dispatch_table {
 492         const char *sched_name;
 493         void    (*init)(void);                          /* Init global state */
 494         void    (*timebase_init)(void);         /* Timebase-dependent initialization */
 495         void    (*processor_init)(processor_t processor);       /* Per-processor scheduler init */
 496         void    (*pset_init)(processor_set_t pset);     /* Per-processor set scheduler init */
 497
 498         void    (*maintenance_continuation)(void);      /* Function called regularly */
 499
 500         /*
 501          * Choose a thread of greater or equal priority from the per-processor
 502          * runqueue for timeshare/fixed threads
 503          */
 504         thread_t        (*choose_thread)(
 505                                                                   processor_t           processor,
 506                                                                   int                           priority,
 507                                                                   ast_t reason);
 508
 509         /* True if scheduler supports stealing threads */
 510         boolean_t   steal_thread_enabled;
 511
 512         /*
 513          * Steal a thread from another processor in the pset so that it can run
 514          * immediately
 515          */
 516         thread_t        (*steal_thread)(
 517                                                                 processor_set_t         pset);
 518
 519         /*
 520          * Compute priority for a timeshare thread based on base priority.
 521          */
 522         int (*compute_timeshare_priority)(thread_t thread);
 523
 524         /*
 525          * Pick the best processor for a thread (any kind of thread) to run on.
 526          */
 527         processor_t     (*choose_processor)(
 528                                                                                  processor_set_t                pset,
 529                                                                                  processor_t                    processor,
 530                                                                                  thread_t                       thread);
 531         /*
 532          * Enqueue a timeshare or fixed priority thread onto the per-processor
 533          * runqueue
 534          */
 535         boolean_t (*processor_enqueue)(
 536                                                                  processor_t                    processor,
 537                                                                  thread_t                       thread,
 538                                                                  integer_t                      options);
 539
 540         /* Migrate threads away in preparation for processor shutdown */
 541         void (*processor_queue_shutdown)(
 542                                                                          processor_t                    processor);
 543
 544         /* Remove the specific thread from the per-processor runqueue */
 545         boolean_t       (*processor_queue_remove)(
 546                                                                         processor_t             processor,
 547                                                                         thread_t                thread);
 548
 549         /*
 550          * Does the per-processor runqueue have any timeshare or fixed priority
 551          * threads on it? Called without pset lock held, so should
 552          * not assume immutability while executing.
 553          */
 554         boolean_t       (*processor_queue_empty)(processor_t            processor);
 555
 556         /*
 557          * Would this priority trigger an urgent preemption if it's sitting
 558          * on the per-processor runqueue?
 559          */
 560         boolean_t       (*priority_is_urgent)(int priority);
 561
 562         /*
 563          * Does the per-processor runqueue contain runnable threads that
 564          * should cause the currently-running thread to be preempted?
 565          */
 566         ast_t           (*processor_csw_check)(processor_t processor);
 567
 568         /*
 569          * Does the per-processor runqueue contain a runnable thread
 570          * of > or >= priority, as a preflight for choose_thread() or other
 571          * thread selection
 572          */
 573         boolean_t       (*processor_queue_has_priority)(processor_t             processor,
 574                                                                                                 int                             priority,
 575                                                                                                 boolean_t               gte);
 576
 577         /* Quantum size for the specified non-realtime thread. */
 578         uint32_t        (*initial_quantum_size)(thread_t thread);
 579
 580         /* Scheduler mode for a new thread */
 581         sched_mode_t    (*initial_thread_sched_mode)(task_t parent_task);
 582
 583         /*
 584          * Is it safe to call update_priority, which may change a thread's
 585          * runqueue or other state. This can be used to throttle changes
 586          * to dynamic priority.
 587          */
 588         boolean_t       (*can_update_priority)(thread_t thread);
 589
 590         /*
 591          * Update both scheduled priority and other persistent state.
 592          * Side effects may including migration to another processor's runqueue.
 593          */
 594         void            (*update_priority)(thread_t thread);
 595
 596         /* Lower overhead update to scheduled priority and state. */
 597         void            (*lightweight_update_priority)(thread_t thread);
 598
 599         /* Callback for non-realtime threads when the quantum timer fires */
 600         void            (*quantum_expire)(thread_t thread);
 601
 602         /*
 603          * Runnable threads on per-processor runqueue. Should only
 604          * be used for relative comparisons of load between processors.
 605          */
 606         int                     (*processor_runq_count)(processor_t     processor);
 607
 608         /* Aggregate runcount statistics for per-processor runqueue */
 609         uint64_t    (*processor_runq_stats_count_sum)(processor_t   processor);
 610
 611         boolean_t       (*processor_bound_count)(processor_t processor);
 612
 613         void            (*thread_update_scan)(sched_update_scan_context_t scan_context);
 614
 615         /*
 616         * Use processor->next_thread to pin a thread to an idle
 617         * processor. If FALSE, threads are enqueued and can
 618         * be stolen by other processors.
 619         */
 620         boolean_t   direct_dispatch_to_idle_processors;
 621
 622         /* Supports more than one pset */
 623         boolean_t   multiple_psets_enabled;
 624         /* Supports scheduler groups */
 625         boolean_t   sched_groups_enabled;
 626 };
 627
 628 #if defined(CONFIG_SCHED_TRADITIONAL)
 629 extern const struct sched_dispatch_table sched_traditional_dispatch;
 630 extern const struct sched_dispatch_table sched_traditional_with_pset_runqueue_dispatch;
 631 #endif
 632
 633 #if defined(CONFIG_SCHED_MULTIQ)
 634 extern const struct sched_dispatch_table sched_multiq_dispatch;
 635 extern const struct sched_dispatch_table sched_dualq_dispatch;
 636 #endif
 637
 638 #if defined(CONFIG_SCHED_PROTO)
 639 extern const struct sched_dispatch_table sched_proto_dispatch;
 640 #endif
 641
 642 #if defined(CONFIG_SCHED_GRRR)
 643 extern const struct sched_dispatch_table sched_grrr_dispatch;
 644 #endif
 645
 646 /*
 647  * It is an error to invoke any scheduler-related code
 648  * before this is set up
 649  */
 650 extern const struct sched_dispatch_table *sched_current_dispatch;
 651
 652 #endif  /* MACH_KERNEL_PRIVATE */
 653
 654 __END_DECLS
 655
 656 #endif  /* _KERN_SCHED_PRIM_H_ */