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.
  35  *
  36  * Permission to use, copy, modify and distribute this software and its
  37  * documentation is hereby granted, provided that both the copyright
  38  * notice and this permission notice appear in all copies of the
  39  * software, derivative works or modified versions, and any portions
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  41  *
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  43  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
  44  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
  45  *
  46  * Carnegie Mellon requests users of this software to return to
  47  *
  48  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  49  *  School of Computer Science
  50  *  Carnegie Mellon University
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  53  * any improvements or extensions that they make and grant Carnegie Mellon
  54  * the rights to redistribute these changes.
  55  */
  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's true scheduling mode */
 145 extern void             sched_set_thread_mode(thread_t thread,
 146                                               sched_mode_t mode);
 147 /* Demote the true scheduler mode */
 148 extern void             sched_thread_mode_demote(thread_t thread,
 149                                                  uint32_t reason);
 150 /* Un-demote the true scheduler mode */
 151 extern void             sched_thread_mode_undemote(thread_t thread,
 152                                                    uint32_t reason);
 153
 154 /* Re-evaluate base priority of thread (thread locked) */
 155 void thread_recompute_priority(thread_t thread);
 156
 157 /* Re-evaluate base priority of thread (thread unlocked) */
 158 void thread_recompute_qos(thread_t thread);
 159
 160 /* Reset scheduled priority of thread */
 161 extern void             thread_recompute_sched_pri(
 162                                         thread_t                thread,
 163                                         boolean_t               override_depress);
 164
 165 /* Periodic scheduler activity */
 166 extern void             sched_init_thread(void (*)(void));
 167
 168 /* Perform sched_tick housekeeping activities */
 169 extern boolean_t                can_update_priority(
 170                                         thread_t                thread);
 171
 172 extern void             update_priority(
 173                                                                                         thread_t                thread);
 174
 175 extern void             lightweight_update_priority(
 176                                                                 thread_t                thread);
 177
 178 extern void             sched_default_quantum_expire(thread_t thread);
 179
 180 /* Idle processor thread */
 181 extern void             idle_thread(void);
 182
 183 extern kern_return_t    idle_thread_create(
 184                                                         processor_t             processor);
 185
 186 /* Continuation return from syscall */
 187 extern void     thread_syscall_return(
 188                         kern_return_t   ret);
 189
 190 /* Context switch */
 191 extern wait_result_t    thread_block_reason(
 192                                                         thread_continue_t       continuation,
 193                                                         void                            *parameter,
 194                                                         ast_t                           reason);
 195
 196 /* Reschedule thread for execution */
 197 extern void             thread_setrun(
 198                                         thread_t        thread,
 199                                         integer_t       options);
 200
 201 #define SCHED_TAILQ             1
 202 #define SCHED_HEADQ             2
 203 #define SCHED_PREEMPT   4
 204
 205 extern uintptr_t sched_thread_on_rt_queue;
 206 #define THREAD_ON_RT_RUNQ  ((processor_t)(uintptr_t)&sched_thread_on_rt_queue)
 207
 208 extern processor_set_t  task_choose_pset(
 209                                                         task_t                  task);
 210
 211 /* Bind the current thread to a particular processor */
 212 extern processor_t              thread_bind(
 213                                                         processor_t             processor);
 214
 215 /* Choose the best processor to run a thread */
 216 extern processor_t      choose_processor(
 217                                                                          processor_set_t                pset,
 218                                                                          processor_t                    processor,
 219                                                                          thread_t                       thread);
 220
 221
 222 extern void thread_quantum_init(
 223                                                                 thread_t thread);
 224
 225 extern void             run_queue_init(
 226                                         run_queue_t             runq);
 227
 228 extern thread_t run_queue_dequeue(
 229                                                           run_queue_t           runq,
 230                                                           integer_t             options);
 231
 232 extern boolean_t        run_queue_enqueue(
 233                                                           run_queue_t           runq,
 234                                                           thread_t                      thread,
 235                                                           integer_t             options);
 236
 237 extern void     run_queue_remove(
 238                                                                          run_queue_t            runq,
 239                                                                          thread_t                       thread);
 240
 241 struct sched_update_scan_context
 242 {
 243         uint64_t        earliest_bg_make_runnable_time;
 244         uint64_t        earliest_normal_make_runnable_time;
 245         uint64_t        earliest_rt_make_runnable_time;
 246 };
 247 typedef struct sched_update_scan_context *sched_update_scan_context_t;
 248
 249 #if defined(CONFIG_SCHED_TIMESHARE_CORE)
 250
 251 extern boolean_t        thread_update_add_thread(thread_t thread);
 252 extern void             thread_update_process_threads(void);
 253 extern boolean_t        runq_scan(run_queue_t runq, sched_update_scan_context_t scan_context);
 254
 255 extern void sched_timeshare_init(void);
 256 extern void sched_timeshare_timebase_init(void);
 257 extern void sched_timeshare_maintenance_continue(void);
 258
 259 extern boolean_t priority_is_urgent(int priority);
 260 extern uint32_t sched_timeshare_initial_quantum_size(thread_t thread);
 261
 262 extern int sched_compute_timeshare_priority(thread_t thread);
 263
 264 #endif /* CONFIG_SCHED_TIMESHARE_CORE */
 265
 266 extern void        rt_runq_scan(sched_update_scan_context_t scan_context);
 267
 268 /* Remove thread from its run queue */
 269 extern boolean_t        thread_run_queue_remove(thread_t thread);
 270 thread_t thread_run_queue_remove_for_handoff(thread_t thread);
 271
 272 /* Put a thread back in the run queue after being yanked */
 273 extern void thread_run_queue_reinsert(thread_t thread, integer_t options);
 274
 275 extern void             thread_timer_expire(
 276                                         void                    *thread,
 277                                         void                    *p1);
 278
 279 extern boolean_t        thread_eager_preemption(
 280                                                 thread_t thread);
 281
 282 extern boolean_t sched_generic_direct_dispatch_to_idle_processors;
 283
 284 /* Set the maximum interrupt level for the thread */
 285 __private_extern__ wait_interrupt_t thread_interrupt_level(
 286                                                 wait_interrupt_t interruptible);
 287
 288 __private_extern__ wait_result_t thread_mark_wait_locked(
 289                                                 thread_t                 thread,
 290                                                 wait_interrupt_t interruptible);
 291
 292 /* Wake up locked thread directly, passing result */
 293 __private_extern__ kern_return_t clear_wait_internal(
 294                                                 thread_t                thread,
 295                                                 wait_result_t   result);
 296
 297 extern void sched_stats_handle_csw(
 298                                                         processor_t processor,
 299                                                         int reasons,
 300                                                         int selfpri,
 301                                                         int otherpri);
 302
 303 extern void sched_stats_handle_runq_change(
 304                                                                         struct runq_stats *stats,
 305                                                                         int old_count);
 306
 307
 308
 309 #define SCHED_STATS_CSW(processor, reasons, selfpri, otherpri)          \
 310 do {                                                            \
 311         if (__builtin_expect(sched_stats_active, 0)) {  \
 312                 sched_stats_handle_csw((processor),             \
 313                                 (reasons), (selfpri), (otherpri));      \
 314         }                                                       \
 315 } while (0)
 316
 317
 318 #define SCHED_STATS_RUNQ_CHANGE(stats, old_count)               \
 319 do {                                                            \
 320         if (__builtin_expect(sched_stats_active, 0)) {  \
 321                 sched_stats_handle_runq_change((stats),         \
 322                                                                 (old_count));           \
 323         }                                                       \
 324 } while (0)
 325
 326 extern uint32_t sched_debug_flags;
 327 #define SCHED_DEBUG_FLAG_PLATFORM_TRACEPOINTS   0x00000001
 328 #define SCHED_DEBUG_FLAG_CHOOSE_PROCESSOR_TRACEPOINTS   0x00000002
 329
 330 #define SCHED_DEBUG_PLATFORM_KERNEL_DEBUG_CONSTANT(...) do {                                            \
 331                 if (__improbable(sched_debug_flags & SCHED_DEBUG_FLAG_PLATFORM_TRACEPOINTS)) { \
 332                         KERNEL_DEBUG_CONSTANT(__VA_ARGS__);                                                     \
 333                 }                                                                                                                               \
 334         } while(0)
 335
 336 #define SCHED_DEBUG_CHOOSE_PROCESSOR_KERNEL_DEBUG_CONSTANT(...) do {                                            \
 337                 if (__improbable(sched_debug_flags & SCHED_DEBUG_FLAG_CHOOSE_PROCESSOR_TRACEPOINTS)) { \
 338                         KERNEL_DEBUG_CONSTANT(__VA_ARGS__);                                                     \
 339                 }                                                                                                                               \
 340         } while(0)
 341
 342 #define THREAD_URGENCY_NONE             0       /* indicates that there is no currently runnable */
 343 #define THREAD_URGENCY_BACKGROUND       1       /* indicates that the thread is marked as a "background" thread */
 344 #define THREAD_URGENCY_NORMAL           2       /* indicates that the thread is marked as a "normal" thread */
 345 #define THREAD_URGENCY_REAL_TIME        3       /* indicates that the thread is marked as a "real-time" or urgent thread */
 346 #define THREAD_URGENCY_MAX              4       /* Marker */
 347 /* Returns the "urgency" of a thread (provided by scheduler) */
 348 extern int      thread_get_urgency(
 349                                         thread_t        thread,
 350                                         uint64_t        *rt_period,
 351                                         uint64_t        *rt_deadline);
 352
 353 /* Tells the "urgency" of the just scheduled thread (provided by CPU PM) */
 354 extern void     thread_tell_urgency(
 355                                         int             urgency,
 356                                         uint64_t        rt_period,
 357                                         uint64_t        rt_deadline,
 358                                         uint64_t        sched_latency,
 359                                     thread_t nthread);
 360
 361 /* Tells if there are "active" RT threads in the system (provided by CPU PM) */
 362 extern void     active_rt_threads(
 363                                         boolean_t       active);
 364
 365 #endif /* MACH_KERNEL_PRIVATE */
 366
 367 __BEGIN_DECLS
 368
 369 #ifdef  XNU_KERNEL_PRIVATE
 370
 371 extern boolean_t                assert_wait_possible(void);
 372
 373 /* Toggles a global override to turn off CPU Throttling */
 374 #define CPU_THROTTLE_DISABLE    0
 375 #define CPU_THROTTLE_ENABLE     1
 376 extern void     sys_override_cpu_throttle(int flag);
 377
 378 /*
 379  ****************** Only exported until BSD stops using ********************
 380  */
 381
 382 extern void                     thread_vm_bind_group_add(void);
 383
 384 /* Wake up thread directly, passing result */
 385 extern kern_return_t clear_wait(
 386                                                 thread_t                thread,
 387                                                 wait_result_t   result);
 388
 389 /* Start thread running */
 390 extern void             thread_bootstrap_return(void);
 391
 392 /* Return from exception (BSD-visible interface) */
 393 extern void             thread_exception_return(void) __dead2;
 394
 395 #define SCHED_STRING_MAX_LENGTH (48)
 396 /* String declaring the name of the current scheduler */
 397 extern char sched_string[SCHED_STRING_MAX_LENGTH];
 398
 399 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);
 400
 401 extern thread_t port_name_to_thread_for_ulock(mach_port_name_t  thread_name);
 402
 403 /* Attempt to context switch to a specific runnable thread */
 404 extern wait_result_t thread_handoff(thread_t thread);
 405
 406 extern struct waitq     *assert_wait_queue(event_t event);
 407
 408 extern kern_return_t thread_wakeup_one_with_pri(event_t event, int priority);
 409
 410 extern thread_t thread_wakeup_identify(event_t event, int priority);
 411
 412 #endif  /* XNU_KERNEL_PRIVATE */
 413
 414 /* Context switch */
 415 extern wait_result_t    thread_block(
 416                                                         thread_continue_t       continuation);
 417
 418 extern wait_result_t    thread_block_parameter(
 419                                                         thread_continue_t       continuation,
 420                                                         void                            *parameter);
 421
 422 /* Declare thread will wait on a particular event */
 423 extern wait_result_t    assert_wait(
 424                                                         event_t                         event,
 425                                                         wait_interrupt_t        interruptible);
 426
 427 /* Assert that the thread intends to wait with a timeout */
 428 extern wait_result_t    assert_wait_timeout(
 429                                                         event_t                         event,
 430                                                         wait_interrupt_t        interruptible,
 431                                                         uint32_t                        interval,
 432                                                         uint32_t                        scale_factor);
 433
 434 /* Assert that the thread intends to wait with an urgency, timeout and leeway */
 435 extern wait_result_t    assert_wait_timeout_with_leeway(
 436                                                         event_t                         event,
 437                                                         wait_interrupt_t        interruptible,
 438                                                         wait_timeout_urgency_t  urgency,
 439                                                         uint32_t                        interval,
 440                                                         uint32_t                        leeway,
 441                                                         uint32_t                        scale_factor);
 442
 443 extern wait_result_t    assert_wait_deadline(
 444                                                         event_t                         event,
 445                                                         wait_interrupt_t        interruptible,
 446                                                         uint64_t                        deadline);
 447
 448 /* Assert that the thread intends to wait with an urgency, deadline, and leeway */
 449 extern wait_result_t    assert_wait_deadline_with_leeway(
 450                                                         event_t                         event,
 451                                                         wait_interrupt_t        interruptible,
 452                                                         wait_timeout_urgency_t  urgency,
 453                                                         uint64_t                        deadline,
 454                                                         uint64_t                        leeway);
 455
 456 /* Wake up thread (or threads) waiting on a particular event */
 457 extern kern_return_t    thread_wakeup_prim(
 458                                                         event_t                         event,
 459                                                         boolean_t                       one_thread,
 460                                                         wait_result_t                   result);
 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 /* Wakeup the specified thread if it is waiting on this event */
 470 extern kern_return_t thread_wakeup_thread(event_t event, thread_t thread);
 471
 472 extern boolean_t preemption_enabled(void);
 473
 474 #ifdef MACH_KERNEL_PRIVATE
 475
 476 /*
 477  * Scheduler algorithm indirection. If only one algorithm is
 478  * enabled at compile-time, a direction function call is used.
 479  * If more than one is enabled, calls are dispatched through
 480  * a function pointer table.
 481  */
 482
 483 #if   !defined(CONFIG_SCHED_TRADITIONAL) && !defined(CONFIG_SCHED_PROTO) && !defined(CONFIG_SCHED_GRRR) && !defined(CONFIG_SCHED_MULTIQ)
 484 #error Enable at least one scheduler algorithm in osfmk/conf/MASTER.XXX
 485 #endif
 486
 487 #define SCHED(f) (sched_current_dispatch->f)
 488
 489 struct sched_dispatch_table {
 490         const char *sched_name;
 491         void    (*init)(void);                          /* Init global state */
 492         void    (*timebase_init)(void);         /* Timebase-dependent initialization */
 493         void    (*processor_init)(processor_t processor);       /* Per-processor scheduler init */
 494         void    (*pset_init)(processor_set_t pset);     /* Per-processor set scheduler init */
 495
 496         void    (*maintenance_continuation)(void);      /* Function called regularly */
 497
 498         /*
 499          * Choose a thread of greater or equal priority from the per-processor
 500          * runqueue for timeshare/fixed threads
 501          */
 502         thread_t        (*choose_thread)(
 503                                                                   processor_t           processor,
 504                                                                   int                           priority,
 505                                                                   ast_t reason);
 506
 507         /* True if scheduler supports stealing threads */
 508         boolean_t   steal_thread_enabled;
 509
 510         /*
 511          * Steal a thread from another processor in the pset so that it can run
 512          * immediately
 513          */
 514         thread_t        (*steal_thread)(
 515                                                                 processor_set_t         pset);
 516
 517         /*
 518          * Compute priority for a timeshare thread based on base priority.
 519          */
 520         int (*compute_timeshare_priority)(thread_t thread);
 521
 522         /*
 523          * Pick the best processor for a thread (any kind of thread) to run on.
 524          */
 525         processor_t     (*choose_processor)(
 526                                                                                  processor_set_t                pset,
 527                                                                                  processor_t                    processor,
 528                                                                                  thread_t                       thread);
 529         /*
 530          * Enqueue a timeshare or fixed priority thread onto the per-processor
 531          * runqueue
 532          */
 533         boolean_t (*processor_enqueue)(
 534                                                                  processor_t                    processor,
 535                                                                  thread_t                       thread,
 536                                                                  integer_t                      options);
 537
 538         /* Migrate threads away in preparation for processor shutdown */
 539         void (*processor_queue_shutdown)(
 540                                                                          processor_t                    processor);
 541
 542         /* Remove the specific thread from the per-processor runqueue */
 543         boolean_t       (*processor_queue_remove)(
 544                                                                         processor_t             processor,
 545                                                                         thread_t                thread);
 546
 547         /*
 548          * Does the per-processor runqueue have any timeshare or fixed priority
 549          * threads on it? Called without pset lock held, so should
 550          * not assume immutability while executing.
 551          */
 552         boolean_t       (*processor_queue_empty)(processor_t            processor);
 553
 554         /*
 555          * Would this priority trigger an urgent preemption if it's sitting
 556          * on the per-processor runqueue?
 557          */
 558         boolean_t       (*priority_is_urgent)(int priority);
 559
 560         /*
 561          * Does the per-processor runqueue contain runnable threads that
 562          * should cause the currently-running thread to be preempted?
 563          */
 564         ast_t           (*processor_csw_check)(processor_t processor);
 565
 566         /*
 567          * Does the per-processor runqueue contain a runnable thread
 568          * of > or >= priority, as a preflight for choose_thread() or other
 569          * thread selection
 570          */
 571         boolean_t       (*processor_queue_has_priority)(processor_t             processor,
 572                                                                                                 int                             priority,
 573                                                                                                 boolean_t               gte);
 574
 575         /* Quantum size for the specified non-realtime thread. */
 576         uint32_t        (*initial_quantum_size)(thread_t thread);
 577
 578         /* Scheduler mode for a new thread */
 579         sched_mode_t    (*initial_thread_sched_mode)(task_t parent_task);
 580
 581         /*
 582          * Is it safe to call update_priority, which may change a thread's
 583          * runqueue or other state. This can be used to throttle changes
 584          * to dynamic priority.
 585          */
 586         boolean_t       (*can_update_priority)(thread_t thread);
 587
 588         /*
 589          * Update both scheduled priority and other persistent state.
 590          * Side effects may including migration to another processor's runqueue.
 591          */
 592         void            (*update_priority)(thread_t thread);
 593
 594         /* Lower overhead update to scheduled priority and state. */
 595         void            (*lightweight_update_priority)(thread_t thread);
 596
 597         /* Callback for non-realtime threads when the quantum timer fires */
 598         void            (*quantum_expire)(thread_t thread);
 599
 600         /*
 601          * Runnable threads on per-processor runqueue. Should only
 602          * be used for relative comparisons of load between processors.
 603          */
 604         int                     (*processor_runq_count)(processor_t     processor);
 605
 606         /* Aggregate runcount statistics for per-processor runqueue */
 607         uint64_t    (*processor_runq_stats_count_sum)(processor_t   processor);
 608
 609         boolean_t       (*processor_bound_count)(processor_t processor);
 610
 611         void            (*thread_update_scan)(sched_update_scan_context_t scan_context);
 612
 613         /*
 614         * Use processor->next_thread to pin a thread to an idle
 615         * processor. If FALSE, threads are enqueued and can
 616         * be stolen by other processors.
 617         */
 618         boolean_t   direct_dispatch_to_idle_processors;
 619
 620         /* Supports more than one pset */
 621         boolean_t   multiple_psets_enabled;
 622         /* Supports scheduler groups */
 623         boolean_t   sched_groups_enabled;
 624 };
 625
 626 #if defined(CONFIG_SCHED_TRADITIONAL)
 627 extern const struct sched_dispatch_table sched_traditional_dispatch;
 628 extern const struct sched_dispatch_table sched_traditional_with_pset_runqueue_dispatch;
 629 #endif
 630
 631 #if defined(CONFIG_SCHED_MULTIQ)
 632 extern const struct sched_dispatch_table sched_multiq_dispatch;
 633 extern const struct sched_dispatch_table sched_dualq_dispatch;
 634 #endif
 635
 636 #if defined(CONFIG_SCHED_PROTO)
 637 extern const struct sched_dispatch_table sched_proto_dispatch;
 638 #endif
 639
 640 #if defined(CONFIG_SCHED_GRRR)
 641 extern const struct sched_dispatch_table sched_grrr_dispatch;
 642 #endif
 643
 644 /*
 645  * It is an error to invoke any scheduler-related code
 646  * before this is set up
 647  */
 648 extern const struct sched_dispatch_table *sched_current_dispatch;
 649
 650 #endif  /* MACH_KERNEL_PRIVATE */
 651
 652 __END_DECLS
 653
 654 #endif  /* _KERN_SCHED_PRIM_H_ */