priority.c
1 /* 2 * Copyright (c) 2000-2019 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 * @OSF_COPYRIGHT@ 30 */ 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 40 * thereof, and that both notices appear in supporting documentation. 41 * 42 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 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 51 * Pittsburgh PA 15213-3890 52 * 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: priority.c 60 * Author: Avadis Tevanian, Jr. 61 * Date: 1986 62 * 63 * Priority related scheduler bits. 64 */ 65 66 #include <mach/boolean.h> 67 #include <mach/kern_return.h> 68 #include <mach/machine.h> 69 #include <kern/host.h> 70 #include <kern/mach_param.h> 71 #include <kern/sched.h> 72 #include <sys/kdebug.h> 73 #include <kern/spl.h> 74 #include <kern/thread.h> 75 #include <kern/processor.h> 76 #include <kern/ledger.h> 77 #include <machine/machparam.h> 78 #include <kern/machine.h> 79 #include <kern/policy_internal.h> 80 #include <kern/sched_clutch.h> 81 82 #ifdef CONFIG_MACH_APPROXIMATE_TIME 83 #include <machine/commpage.h> /* for commpage_update_mach_approximate_time */ 84 #endif 85 86 #if MONOTONIC 87 #include <kern/monotonic.h> 88 #endif /* MONOTONIC */ 89 90 /* 91 * thread_quantum_expire: 92 * 93 * Recalculate the quantum and priority for a thread. 94 * 95 * Called at splsched. 96 */ 97 98 void 99 thread_quantum_expire( 100 timer_call_param_t p0, 101 timer_call_param_t p1) 102 { 103 processor_t processor = p0; 104 thread_t thread = p1; 105 ast_t preempt; 106 uint64_t ctime; 107 108 assert(processor == current_processor()); 109 assert(thread == current_thread()); 110 111 KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_QUANTUM_EXPIRED) | DBG_FUNC_START, 0, 0, 0, 0, 0); 112 113 SCHED_STATS_INC(quantum_timer_expirations); 114 115 /* 116 * We bill CPU time to both the individual thread and its task. 117 * 118 * Because this balance adjustment could potentially attempt to wake this 119 * very thread, we must credit the ledger before taking the thread lock. 120 * The ledger pointers are only manipulated by the thread itself at the ast 121 * boundary. 122 * 123 * TODO: This fails to account for the time between when the timer was 124 * armed and when it fired. It should be based on the system_timer and 125 * running a timer_update operation here. 126 */ 127 ledger_credit(thread->t_ledger, task_ledgers.cpu_time, thread->quantum_remaining); 128 ledger_credit(thread->t_threadledger, thread_ledgers.cpu_time, thread->quantum_remaining); 129 if (thread->t_bankledger) { 130 ledger_credit(thread->t_bankledger, bank_ledgers.cpu_time, 131 (thread->quantum_remaining - thread->t_deduct_bank_ledger_time)); 132 } 133 thread->t_deduct_bank_ledger_time = 0; 134 ctime = mach_absolute_time(); 135 136 #ifdef CONFIG_MACH_APPROXIMATE_TIME 137 commpage_update_mach_approximate_time(ctime); 138 #endif 139 sched_update_pset_avg_execution_time(processor->processor_set, thread->quantum_remaining, ctime, thread->th_sched_bucket); 140 141 #if MONOTONIC 142 mt_sched_update(thread); 143 #endif /* MONOTONIC */ 144 145 thread_lock(thread); 146 147 /* 148 * We've run up until our quantum expiration, and will (potentially) 149 * continue without re-entering the scheduler, so update this now. 150 */ 151 processor->last_dispatch = ctime; 152 thread->last_run_time = ctime; 153 154 /* 155 * Check for fail-safe trip. 156 */ 157 if ((thread->sched_mode == TH_MODE_REALTIME || thread->sched_mode == TH_MODE_FIXED) && 158 !(thread->sched_flags & TH_SFLAG_PROMOTED) && 159 !(thread->kern_promotion_schedpri != 0) && 160 !(thread->sched_flags & TH_SFLAG_PROMOTE_REASON_MASK) && 161 !(thread->options & TH_OPT_SYSTEM_CRITICAL)) { 162 uint64_t new_computation; 163 164 new_computation = ctime - thread->computation_epoch; 165 new_computation += thread->computation_metered; 166 if (new_computation > max_unsafe_computation) { 167 KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_FAILSAFE) | DBG_FUNC_NONE, 168 (uintptr_t)thread->sched_pri, (uintptr_t)thread->sched_mode, 0, 0, 0); 169 170 thread->safe_release = ctime + sched_safe_duration; 171 172 sched_thread_mode_demote(thread, TH_SFLAG_FAILSAFE); 173 } 174 } 175 176 /* 177 * Recompute scheduled priority if appropriate. 178 */ 179 if (SCHED(can_update_priority)(thread)) { 180 SCHED(update_priority)(thread); 181 } else { 182 SCHED(lightweight_update_priority)(thread); 183 } 184 185 if (thread->sched_mode != TH_MODE_REALTIME) { 186 SCHED(quantum_expire)(thread); 187 } 188 189 /* 190 * This quantum is up, give this thread another. 191 */ 192 processor->first_timeslice = FALSE; 193 194 thread_quantum_init(thread); 195 196 /* Reload precise timing global policy to thread-local policy */ 197 thread->precise_user_kernel_time = use_precise_user_kernel_time(thread); 198 199 /* 200 * Since non-precise user/kernel time doesn't update the state/thread timer 201 * during privilege transitions, synthesize an event now. 202 */ 203 if (!thread->precise_user_kernel_time) { 204 timer_update(processor->current_state, ctime); 205 timer_update(processor->thread_timer, ctime); 206 timer_update(&thread->runnable_timer, ctime); 207 } 208 209 210 processor->quantum_end = ctime + thread->quantum_remaining; 211 212 /* 213 * Context switch check 214 * 215 * non-urgent flags don't affect kernel threads, so upgrade to urgent 216 * to ensure that rebalancing and non-recommendation kick in quickly. 217 */ 218 219 ast_t check_reason = AST_QUANTUM; 220 if (thread->task == kernel_task) { 221 check_reason |= AST_URGENT; 222 } 223 224 if ((preempt = csw_check(thread, processor, check_reason)) != AST_NONE) { 225 ast_on(preempt); 226 } 227 228 /* 229 * AST_KEVENT does not send an IPI when setting the AST, 230 * to avoid waiting for the next context switch to propagate the AST, 231 * the AST is propagated here at quantum expiration. 232 */ 233 ast_propagate(thread); 234 235 thread_unlock(thread); 236 running_timer_enter(processor, RUNNING_TIMER_QUANTUM, thread, 237 processor->quantum_end, ctime); 238 239 /* Tell platform layer that we are still running this thread */ 240 thread_urgency_t urgency = thread_get_urgency(thread, NULL, NULL); 241 machine_thread_going_on_core(thread, urgency, 0, 0, ctime); 242 machine_switch_perfcontrol_state_update(QUANTUM_EXPIRY, ctime, 243 0, thread); 244 245 #if defined(CONFIG_SCHED_TIMESHARE_CORE) 246 sched_timeshare_consider_maintenance(ctime); 247 #endif /* CONFIG_SCHED_TIMESHARE_CORE */ 248 249 #if __arm__ || __arm64__ 250 if (thread->sched_mode == TH_MODE_REALTIME) { 251 sched_consider_recommended_cores(ctime, thread); 252 } 253 #endif /* __arm__ || __arm64__ */ 254 255 KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_QUANTUM_EXPIRED) | DBG_FUNC_END, preempt, 0, 0, 0, 0); 256 } 257 258 /* 259 * sched_set_thread_base_priority: 260 * 261 * Set the base priority of the thread 262 * and reset its scheduled priority. 263 * 264 * This is the only path to change base_pri. 265 * 266 * Called with the thread locked. 267 */ 268 void 269 sched_set_thread_base_priority(thread_t thread, int priority) 270 { 271 assert(priority >= MINPRI); 272 uint64_t ctime = 0; 273 274 if (thread->sched_mode == TH_MODE_REALTIME) { 275 assert(priority <= BASEPRI_RTQUEUES); 276 } else { 277 assert(priority < BASEPRI_RTQUEUES); 278 } 279 280 int old_base_pri = thread->base_pri; 281 thread->req_base_pri = (int16_t)priority; 282 if (thread->sched_flags & TH_SFLAG_BASE_PRI_FROZEN) { 283 priority = MAX(priority, old_base_pri); 284 } 285 thread->base_pri = (int16_t)priority; 286 287 if ((thread->state & TH_RUN) == TH_RUN) { 288 assert(thread->last_made_runnable_time != THREAD_NOT_RUNNABLE); 289 ctime = mach_approximate_time(); 290 thread->last_basepri_change_time = ctime; 291 } else { 292 assert(thread->last_basepri_change_time == THREAD_NOT_RUNNABLE); 293 assert(thread->last_made_runnable_time == THREAD_NOT_RUNNABLE); 294 } 295 296 /* 297 * Currently the perfcontrol_attr depends on the base pri of the 298 * thread. Therefore, we use this function as the hook for the 299 * perfcontrol callout. 300 */ 301 if (thread == current_thread() && old_base_pri != priority) { 302 if (!ctime) { 303 ctime = mach_approximate_time(); 304 } 305 machine_switch_perfcontrol_state_update(PERFCONTROL_ATTR_UPDATE, 306 ctime, PERFCONTROL_CALLOUT_WAKE_UNSAFE, thread); 307 } 308 #if !CONFIG_SCHED_CLUTCH 309 /* For the clutch scheduler, this operation is done in set_sched_pri() */ 310 SCHED(update_thread_bucket)(thread); 311 #endif /* !CONFIG_SCHED_CLUTCH */ 312 313 thread_recompute_sched_pri(thread, SETPRI_DEFAULT); 314 } 315 316 /* 317 * sched_set_kernel_thread_priority: 318 * 319 * Set the absolute base priority of the thread 320 * and reset its scheduled priority. 321 * 322 * Called with the thread unlocked. 323 */ 324 void 325 sched_set_kernel_thread_priority(thread_t thread, int new_priority) 326 { 327 spl_t s = splsched(); 328 329 thread_lock(thread); 330 331 assert(thread->sched_mode != TH_MODE_REALTIME); 332 assert(thread->effective_policy.thep_qos == THREAD_QOS_UNSPECIFIED); 333 334 if (new_priority > thread->max_priority) { 335 new_priority = thread->max_priority; 336 } 337 #if !defined(XNU_TARGET_OS_OSX) 338 if (new_priority < MAXPRI_THROTTLE) { 339 new_priority = MAXPRI_THROTTLE; 340 } 341 #endif /* !defined(XNU_TARGET_OS_OSX) */ 342 343 thread->importance = new_priority - thread->task_priority; 344 345 sched_set_thread_base_priority(thread, new_priority); 346 347 thread_unlock(thread); 348 splx(s); 349 } 350 351 /* 352 * thread_recompute_sched_pri: 353 * 354 * Reset the scheduled priority of the thread 355 * according to its base priority if the 356 * thread has not been promoted or depressed. 357 * 358 * This is the only way to push base_pri changes into sched_pri, 359 * or to recalculate the appropriate sched_pri after changing 360 * a promotion or depression. 361 * 362 * Called at splsched with the thread locked. 363 * 364 * TODO: Add an 'update urgency' flag to avoid urgency callouts on every rwlock operation 365 */ 366 void 367 thread_recompute_sched_pri(thread_t thread, set_sched_pri_options_t options) 368 { 369 uint32_t sched_flags = thread->sched_flags; 370 sched_mode_t sched_mode = thread->sched_mode; 371 372 int16_t priority = thread->base_pri; 373 374 if (sched_mode == TH_MODE_TIMESHARE) { 375 priority = (int16_t)SCHED(compute_timeshare_priority)(thread); 376 } 377 378 if (sched_flags & TH_SFLAG_DEPRESS) { 379 /* thread_yield_internal overrides kernel mutex promotion */ 380 priority = DEPRESSPRI; 381 } else { 382 /* poll-depress is overridden by mutex promotion and promote-reasons */ 383 if ((sched_flags & TH_SFLAG_POLLDEPRESS)) { 384 priority = DEPRESSPRI; 385 } 386 387 if (thread->kern_promotion_schedpri > 0) { 388 priority = MAX(priority, thread->kern_promotion_schedpri); 389 390 if (sched_mode != TH_MODE_REALTIME) { 391 priority = MIN(priority, MAXPRI_PROMOTE); 392 } 393 } 394 395 if (sched_flags & TH_SFLAG_PROMOTED) { 396 priority = MAX(priority, thread->promotion_priority); 397 398 if (sched_mode != TH_MODE_REALTIME) { 399 priority = MIN(priority, MAXPRI_PROMOTE); 400 } 401 } 402 403 if (sched_flags & TH_SFLAG_PROMOTE_REASON_MASK) { 404 if (sched_flags & TH_SFLAG_RW_PROMOTED) { 405 priority = MAX(priority, MINPRI_RWLOCK); 406 } 407 408 if (sched_flags & TH_SFLAG_WAITQ_PROMOTED) { 409 priority = MAX(priority, MINPRI_WAITQ); 410 } 411 412 if (sched_flags & TH_SFLAG_EXEC_PROMOTED) { 413 priority = MAX(priority, MINPRI_EXEC); 414 } 415 } 416 } 417 418 set_sched_pri(thread, priority, options); 419 } 420 421 void 422 sched_default_quantum_expire(thread_t thread __unused) 423 { 424 /* 425 * No special behavior when a timeshare, fixed, or realtime thread 426 * uses up its entire quantum 427 */ 428 } 429 430 int smt_timeshare_enabled = 1; 431 int smt_sched_bonus_16ths = 8; 432 433 #if defined(CONFIG_SCHED_TIMESHARE_CORE) 434 435 /* 436 * lightweight_update_priority: 437 * 438 * Update the scheduled priority for 439 * a timesharing thread. 440 * 441 * Only for use on the current thread. 442 * 443 * Called with the thread locked. 444 */ 445 void 446 lightweight_update_priority(thread_t thread) 447 { 448 assert(thread->runq == PROCESSOR_NULL); 449 assert(thread == current_thread()); 450 451 if (thread->sched_mode == TH_MODE_TIMESHARE) { 452 int priority; 453 uint32_t delta; 454 455 thread_timer_delta(thread, delta); 456 457 /* 458 * Accumulate timesharing usage only 459 * during contention for processor 460 * resources. 461 */ 462 if (thread->pri_shift < INT8_MAX) { 463 if (thread_no_smt(thread) && smt_timeshare_enabled) { 464 thread->sched_usage += (delta + ((delta * smt_sched_bonus_16ths) >> 4)); 465 } else { 466 thread->sched_usage += delta; 467 } 468 } 469 470 thread->cpu_delta += delta; 471 472 #if CONFIG_SCHED_CLUTCH 473 /* 474 * Update the CPU usage for the thread group to which the thread belongs. 475 * The implementation assumes that the thread ran for the entire delta 476 * as part of the same thread group. 477 */ 478 sched_clutch_cpu_usage_update(thread, delta); 479 #endif /* CONFIG_SCHED_CLUTCH */ 480 481 priority = sched_compute_timeshare_priority(thread); 482 483 if (priority != thread->sched_pri) { 484 thread_recompute_sched_pri(thread, SETPRI_LAZY); 485 } 486 } 487 } 488 489 /* 490 * Define shifts for simulating (5/8) ** n 491 * 492 * Shift structures for holding update shifts. Actual computation 493 * is usage = (usage >> shift1) +/- (usage >> abs(shift2)) where the 494 * +/- is determined by the sign of shift 2. 495 */ 496 497 const struct shift_data sched_decay_shifts[SCHED_DECAY_TICKS] = { 498 { .shift1 = 1, .shift2 = 1 }, 499 { .shift1 = 1, .shift2 = 3 }, 500 { .shift1 = 1, .shift2 = -3 }, 501 { .shift1 = 2, .shift2 = -7 }, 502 { .shift1 = 3, .shift2 = 5 }, 503 { .shift1 = 3, .shift2 = -5 }, 504 { .shift1 = 4, .shift2 = -8 }, 505 { .shift1 = 5, .shift2 = 7 }, 506 { .shift1 = 5, .shift2 = -7 }, 507 { .shift1 = 6, .shift2 = -10 }, 508 { .shift1 = 7, .shift2 = 10 }, 509 { .shift1 = 7, .shift2 = -9 }, 510 { .shift1 = 8, .shift2 = -11 }, 511 { .shift1 = 9, .shift2 = 12 }, 512 { .shift1 = 9, .shift2 = -11 }, 513 { .shift1 = 10, .shift2 = -13 }, 514 { .shift1 = 11, .shift2 = 14 }, 515 { .shift1 = 11, .shift2 = -13 }, 516 { .shift1 = 12, .shift2 = -15 }, 517 { .shift1 = 13, .shift2 = 17 }, 518 { .shift1 = 13, .shift2 = -15 }, 519 { .shift1 = 14, .shift2 = -17 }, 520 { .shift1 = 15, .shift2 = 19 }, 521 { .shift1 = 16, .shift2 = 18 }, 522 { .shift1 = 16, .shift2 = -19 }, 523 { .shift1 = 17, .shift2 = 22 }, 524 { .shift1 = 18, .shift2 = 20 }, 525 { .shift1 = 18, .shift2 = -20 }, 526 { .shift1 = 19, .shift2 = 26 }, 527 { .shift1 = 20, .shift2 = 22 }, 528 { .shift1 = 20, .shift2 = -22 }, 529 { .shift1 = 21, .shift2 = -27 } 530 }; 531 532 /* 533 * sched_compute_timeshare_priority: 534 * 535 * Calculate the timesharing priority based upon usage and load. 536 */ 537 extern int sched_pri_decay_band_limit; 538 539 540 /* Only use the decay floor logic on non-macOS and non-clutch schedulers */ 541 #if !defined(XNU_TARGET_OS_OSX) && !CONFIG_SCHED_CLUTCH 542 543 int 544 sched_compute_timeshare_priority(thread_t thread) 545 { 546 int decay_amount; 547 int decay_limit = sched_pri_decay_band_limit; 548 549 if (thread->base_pri > BASEPRI_FOREGROUND) { 550 decay_limit += (thread->base_pri - BASEPRI_FOREGROUND); 551 } 552 553 if (thread->pri_shift == INT8_MAX) { 554 decay_amount = 0; 555 } else { 556 decay_amount = (thread->sched_usage >> thread->pri_shift); 557 } 558 559 if (decay_amount > decay_limit) { 560 decay_amount = decay_limit; 561 } 562 563 /* start with base priority */ 564 int priority = thread->base_pri - decay_amount; 565 566 if (priority < MAXPRI_THROTTLE) { 567 if (thread->task->max_priority > MAXPRI_THROTTLE) { 568 priority = MAXPRI_THROTTLE; 569 } else if (priority < MINPRI_USER) { 570 priority = MINPRI_USER; 571 } 572 } else if (priority > MAXPRI_KERNEL) { 573 priority = MAXPRI_KERNEL; 574 } 575 576 return priority; 577 } 578 579 #else /* !defined(XNU_TARGET_OS_OSX) && !CONFIG_SCHED_CLUTCH */ 580 581 int 582 sched_compute_timeshare_priority(thread_t thread) 583 { 584 /* start with base priority */ 585 int priority = thread->base_pri; 586 587 if (thread->pri_shift != INT8_MAX) { 588 priority -= (thread->sched_usage >> thread->pri_shift); 589 } 590 591 if (priority < MINPRI_USER) { 592 priority = MINPRI_USER; 593 } else if (priority > MAXPRI_KERNEL) { 594 priority = MAXPRI_KERNEL; 595 } 596 597 return priority; 598 } 599 600 #endif /* !defined(XNU_TARGET_OS_OSX) && !CONFIG_SCHED_CLUTCH */ 601 602 /* 603 * can_update_priority 604 * 605 * Make sure we don't do re-dispatches more frequently than a scheduler tick. 606 * 607 * Called with the thread locked. 608 */ 609 boolean_t 610 can_update_priority( 611 thread_t thread) 612 { 613 if (sched_tick == thread->sched_stamp) { 614 return FALSE; 615 } else { 616 return TRUE; 617 } 618 } 619 620 /* 621 * update_priority 622 * 623 * Perform housekeeping operations driven by scheduler tick. 624 * 625 * Called with the thread locked. 626 */ 627 void 628 update_priority( 629 thread_t thread) 630 { 631 uint32_t ticks, delta; 632 633 ticks = sched_tick - thread->sched_stamp; 634 assert(ticks != 0); 635 636 thread->sched_stamp += ticks; 637 638 /* If requested, accelerate aging of sched_usage */ 639 if (sched_decay_usage_age_factor > 1) { 640 ticks *= sched_decay_usage_age_factor; 641 } 642 643 /* 644 * Gather cpu usage data. 645 */ 646 thread_timer_delta(thread, delta); 647 if (ticks < SCHED_DECAY_TICKS) { 648 /* 649 * Accumulate timesharing usage only during contention for processor 650 * resources. Use the pri_shift from the previous tick window to 651 * determine if the system was in a contended state. 652 */ 653 if (thread->pri_shift < INT8_MAX) { 654 if (thread_no_smt(thread) && smt_timeshare_enabled) { 655 thread->sched_usage += (delta + ((delta * smt_sched_bonus_16ths) >> 4)); 656 } else { 657 thread->sched_usage += delta; 658 } 659 } 660 661 thread->cpu_usage += delta + thread->cpu_delta; 662 thread->cpu_delta = 0; 663 664 #if CONFIG_SCHED_CLUTCH 665 /* 666 * Update the CPU usage for the thread group to which the thread belongs. 667 * The implementation assumes that the thread ran for the entire delta 668 * as part of the same thread group. 669 */ 670 sched_clutch_cpu_usage_update(thread, delta); 671 #endif /* CONFIG_SCHED_CLUTCH */ 672 673 const struct shift_data *shiftp = &sched_decay_shifts[ticks]; 674 675 if (shiftp->shift2 > 0) { 676 thread->cpu_usage = (thread->cpu_usage >> shiftp->shift1) + 677 (thread->cpu_usage >> shiftp->shift2); 678 thread->sched_usage = (thread->sched_usage >> shiftp->shift1) + 679 (thread->sched_usage >> shiftp->shift2); 680 } else { 681 thread->cpu_usage = (thread->cpu_usage >> shiftp->shift1) - 682 (thread->cpu_usage >> -(shiftp->shift2)); 683 thread->sched_usage = (thread->sched_usage >> shiftp->shift1) - 684 (thread->sched_usage >> -(shiftp->shift2)); 685 } 686 } else { 687 thread->cpu_usage = thread->cpu_delta = 0; 688 thread->sched_usage = 0; 689 } 690 691 /* 692 * Check for fail-safe release. 693 */ 694 if ((thread->sched_flags & TH_SFLAG_FAILSAFE) && 695 mach_absolute_time() >= thread->safe_release) { 696 sched_thread_mode_undemote(thread, TH_SFLAG_FAILSAFE); 697 } 698 699 /* 700 * Now that the thread's CPU usage has been accumulated and aged 701 * based on contention of the previous tick window, update the 702 * pri_shift of the thread to match the current global load/shift 703 * values. The updated pri_shift would be used to calculate the 704 * new priority of the thread. 705 */ 706 #if CONFIG_SCHED_CLUTCH 707 thread->pri_shift = sched_clutch_thread_pri_shift(thread, thread->th_sched_bucket); 708 #else /* CONFIG_SCHED_CLUTCH */ 709 thread->pri_shift = sched_pri_shifts[thread->th_sched_bucket]; 710 #endif /* CONFIG_SCHED_CLUTCH */ 711 712 /* Recompute scheduled priority if appropriate. */ 713 if (thread->sched_mode == TH_MODE_TIMESHARE) { 714 thread_recompute_sched_pri(thread, SETPRI_LAZY); 715 } 716 } 717 718 #endif /* CONFIG_SCHED_TIMESHARE_CORE */ 719 720 721 /* 722 * TH_BUCKET_RUN is a count of *all* runnable non-idle threads. 723 * Each other bucket is a count of the runnable non-idle threads 724 * with that property. All updates to these counts should be 725 * performed with os_atomic_* operations. 726 * 727 * For the clutch scheduler, this global bucket is used only for 728 * keeping the total global run count. 729 */ 730 uint32_t sched_run_buckets[TH_BUCKET_MAX]; 731 732 static void 733 sched_incr_bucket(sched_bucket_t bucket) 734 { 735 assert(bucket >= TH_BUCKET_FIXPRI && 736 bucket <= TH_BUCKET_SHARE_BG); 737 738 os_atomic_inc(&sched_run_buckets[bucket], relaxed); 739 } 740 741 static void 742 sched_decr_bucket(sched_bucket_t bucket) 743 { 744 assert(bucket >= TH_BUCKET_FIXPRI && 745 bucket <= TH_BUCKET_SHARE_BG); 746 747 assert(os_atomic_load(&sched_run_buckets[bucket], relaxed) > 0); 748 749 os_atomic_dec(&sched_run_buckets[bucket], relaxed); 750 } 751 752 static void 753 sched_add_bucket(sched_bucket_t bucket, uint8_t run_weight) 754 { 755 assert(bucket >= TH_BUCKET_FIXPRI && 756 bucket <= TH_BUCKET_SHARE_BG); 757 758 os_atomic_add(&sched_run_buckets[bucket], run_weight, relaxed); 759 } 760 761 static void 762 sched_sub_bucket(sched_bucket_t bucket, uint8_t run_weight) 763 { 764 assert(bucket >= TH_BUCKET_FIXPRI && 765 bucket <= TH_BUCKET_SHARE_BG); 766 767 assert(os_atomic_load(&sched_run_buckets[bucket], relaxed) > 0); 768 769 os_atomic_sub(&sched_run_buckets[bucket], run_weight, relaxed); 770 } 771 772 uint32_t 773 sched_run_incr(thread_t thread) 774 { 775 assert((thread->state & (TH_RUN | TH_IDLE)) == TH_RUN); 776 777 uint32_t new_count = os_atomic_inc(&sched_run_buckets[TH_BUCKET_RUN], relaxed); 778 779 sched_incr_bucket(thread->th_sched_bucket); 780 781 return new_count; 782 } 783 784 uint32_t 785 sched_run_decr(thread_t thread) 786 { 787 assert((thread->state & (TH_RUN | TH_IDLE)) != TH_RUN); 788 789 sched_decr_bucket(thread->th_sched_bucket); 790 791 uint32_t new_count = os_atomic_dec(&sched_run_buckets[TH_BUCKET_RUN], relaxed); 792 793 return new_count; 794 } 795 796 uint32_t 797 sched_smt_run_incr(thread_t thread) 798 { 799 assert((thread->state & (TH_RUN | TH_IDLE)) == TH_RUN); 800 801 uint8_t run_weight = (thread_no_smt(thread) && smt_timeshare_enabled) ? 2 : 1; 802 thread->sched_saved_run_weight = run_weight; 803 804 uint32_t new_count = os_atomic_add(&sched_run_buckets[TH_BUCKET_RUN], run_weight, relaxed); 805 806 sched_add_bucket(thread->th_sched_bucket, run_weight); 807 808 return new_count; 809 } 810 811 uint32_t 812 sched_smt_run_decr(thread_t thread) 813 { 814 assert((thread->state & (TH_RUN | TH_IDLE)) != TH_RUN); 815 816 uint8_t run_weight = thread->sched_saved_run_weight; 817 818 sched_sub_bucket(thread->th_sched_bucket, run_weight); 819 820 uint32_t new_count = os_atomic_sub(&sched_run_buckets[TH_BUCKET_RUN], run_weight, relaxed); 821 822 return new_count; 823 } 824 825 void 826 sched_update_thread_bucket(thread_t thread) 827 { 828 sched_bucket_t old_bucket = thread->th_sched_bucket; 829 sched_bucket_t new_bucket = TH_BUCKET_RUN; 830 831 switch (thread->sched_mode) { 832 case TH_MODE_FIXED: 833 case TH_MODE_REALTIME: 834 new_bucket = TH_BUCKET_FIXPRI; 835 break; 836 837 case TH_MODE_TIMESHARE: 838 if (thread->base_pri > BASEPRI_DEFAULT) { 839 new_bucket = TH_BUCKET_SHARE_FG; 840 } else if (thread->base_pri > BASEPRI_UTILITY) { 841 new_bucket = TH_BUCKET_SHARE_DF; 842 } else if (thread->base_pri > MAXPRI_THROTTLE) { 843 new_bucket = TH_BUCKET_SHARE_UT; 844 } else { 845 new_bucket = TH_BUCKET_SHARE_BG; 846 } 847 break; 848 849 default: 850 panic("unexpected mode: %d", thread->sched_mode); 851 break; 852 } 853 854 if (old_bucket != new_bucket) { 855 thread->th_sched_bucket = new_bucket; 856 thread->pri_shift = sched_pri_shifts[new_bucket]; 857 858 if ((thread->state & (TH_RUN | TH_IDLE)) == TH_RUN) { 859 sched_decr_bucket(old_bucket); 860 sched_incr_bucket(new_bucket); 861 } 862 } 863 } 864 865 void 866 sched_smt_update_thread_bucket(thread_t thread) 867 { 868 sched_bucket_t old_bucket = thread->th_sched_bucket; 869 sched_bucket_t new_bucket = TH_BUCKET_RUN; 870 871 switch (thread->sched_mode) { 872 case TH_MODE_FIXED: 873 case TH_MODE_REALTIME: 874 new_bucket = TH_BUCKET_FIXPRI; 875 break; 876 877 case TH_MODE_TIMESHARE: 878 if (thread->base_pri > BASEPRI_DEFAULT) { 879 new_bucket = TH_BUCKET_SHARE_FG; 880 } else if (thread->base_pri > BASEPRI_UTILITY) { 881 new_bucket = TH_BUCKET_SHARE_DF; 882 } else if (thread->base_pri > MAXPRI_THROTTLE) { 883 new_bucket = TH_BUCKET_SHARE_UT; 884 } else { 885 new_bucket = TH_BUCKET_SHARE_BG; 886 } 887 break; 888 889 default: 890 panic("unexpected mode: %d", thread->sched_mode); 891 break; 892 } 893 894 if (old_bucket != new_bucket) { 895 thread->th_sched_bucket = new_bucket; 896 thread->pri_shift = sched_pri_shifts[new_bucket]; 897 898 if ((thread->state & (TH_RUN | TH_IDLE)) == TH_RUN) { 899 sched_sub_bucket(old_bucket, thread->sched_saved_run_weight); 900 sched_add_bucket(new_bucket, thread->sched_saved_run_weight); 901 } 902 } 903 } 904 905 /* 906 * Set the thread's true scheduling mode 907 * Called with thread mutex and thread locked 908 * The thread has already been removed from the runqueue. 909 * 910 * (saved_mode is handled before this point) 911 */ 912 void 913 sched_set_thread_mode(thread_t thread, sched_mode_t new_mode) 914 { 915 assert(thread->runq == PROCESSOR_NULL); 916 917 switch (new_mode) { 918 case TH_MODE_FIXED: 919 case TH_MODE_REALTIME: 920 case TH_MODE_TIMESHARE: 921 break; 922 923 default: 924 panic("unexpected mode: %d", new_mode); 925 break; 926 } 927 928 #if CONFIG_SCHED_AUTO_JOIN 929 /* 930 * Realtime threads might have auto-joined a work interval based on 931 * make runnable relationships. If such an RT thread is now being demoted 932 * to non-RT, unjoin the thread from the work interval. 933 */ 934 if ((thread->sched_flags & TH_SFLAG_THREAD_GROUP_AUTO_JOIN) && (new_mode != TH_MODE_REALTIME)) { 935 assert((thread->sched_mode == TH_MODE_REALTIME) || (thread->th_work_interval_flags & TH_WORK_INTERVAL_FLAGS_AUTO_JOIN_LEAK)); 936 work_interval_auto_join_demote(thread); 937 } 938 #endif /* CONFIG_SCHED_AUTO_JOIN */ 939 940 thread->sched_mode = new_mode; 941 942 SCHED(update_thread_bucket)(thread); 943 } 944 945 /* 946 * Demote the true scheduler mode to timeshare (called with the thread locked) 947 */ 948 void 949 sched_thread_mode_demote(thread_t thread, uint32_t reason) 950 { 951 assert(reason & TH_SFLAG_DEMOTED_MASK); 952 assert((thread->sched_flags & reason) != reason); 953 954 if (thread->policy_reset) { 955 return; 956 } 957 958 if (thread->sched_flags & TH_SFLAG_DEMOTED_MASK) { 959 /* Another demotion reason is already active */ 960 thread->sched_flags |= reason; 961 return; 962 } 963 964 assert(thread->saved_mode == TH_MODE_NONE); 965 966 boolean_t removed = thread_run_queue_remove(thread); 967 968 thread->sched_flags |= reason; 969 970 thread->saved_mode = thread->sched_mode; 971 972 sched_set_thread_mode(thread, TH_MODE_TIMESHARE); 973 974 thread_recompute_priority(thread); 975 976 if (removed) { 977 thread_run_queue_reinsert(thread, SCHED_TAILQ); 978 } 979 } 980 981 /* 982 * Un-demote the true scheduler mode back to the saved mode (called with the thread locked) 983 */ 984 void 985 sched_thread_mode_undemote(thread_t thread, uint32_t reason) 986 { 987 assert(reason & TH_SFLAG_DEMOTED_MASK); 988 assert((thread->sched_flags & reason) == reason); 989 assert(thread->saved_mode != TH_MODE_NONE); 990 assert(thread->sched_mode == TH_MODE_TIMESHARE); 991 assert(thread->policy_reset == 0); 992 993 thread->sched_flags &= ~reason; 994 995 if (thread->sched_flags & TH_SFLAG_DEMOTED_MASK) { 996 /* Another demotion reason is still active */ 997 return; 998 } 999 1000 boolean_t removed = thread_run_queue_remove(thread); 1001 1002 sched_set_thread_mode(thread, thread->saved_mode); 1003 1004 thread->saved_mode = TH_MODE_NONE; 1005 1006 thread_recompute_priority(thread); 1007 1008 if (removed) { 1009 thread_run_queue_reinsert(thread, SCHED_TAILQ); 1010 } 1011 } 1012 1013 /* 1014 * Promote thread to have a sched pri floor for a specific reason 1015 * 1016 * Promotion must not last past syscall boundary 1017 * Clients must always pair promote and demote 1:1, 1018 * Handling nesting of the same promote reason is the client's responsibility 1019 * 1020 * Called at splsched with thread locked 1021 */ 1022 void 1023 sched_thread_promote_reason(thread_t thread, 1024 uint32_t reason, 1025 __kdebug_only uintptr_t trace_obj /* already unslid */) 1026 { 1027 assert(reason & TH_SFLAG_PROMOTE_REASON_MASK); 1028 assert((thread->sched_flags & reason) != reason); 1029 1030 switch (reason) { 1031 case TH_SFLAG_RW_PROMOTED: 1032 KDBG(MACHDBG_CODE(DBG_MACH_SCHED, MACH_RW_PROMOTE), 1033 thread_tid(thread), thread->sched_pri, 1034 thread->base_pri, trace_obj); 1035 break; 1036 case TH_SFLAG_WAITQ_PROMOTED: 1037 KDBG(MACHDBG_CODE(DBG_MACH_SCHED, MACH_WAITQ_PROMOTE), 1038 thread_tid(thread), thread->sched_pri, 1039 thread->base_pri, trace_obj); 1040 break; 1041 case TH_SFLAG_EXEC_PROMOTED: 1042 KDBG(MACHDBG_CODE(DBG_MACH_SCHED, MACH_EXEC_PROMOTE), 1043 thread_tid(thread), thread->sched_pri, 1044 thread->base_pri, trace_obj); 1045 break; 1046 } 1047 1048 thread->sched_flags |= reason; 1049 1050 thread_recompute_sched_pri(thread, SETPRI_DEFAULT); 1051 } 1052 1053 /* 1054 * End a specific promotion reason 1055 * Demotes a thread back to its expected priority without the promotion in place 1056 * 1057 * Called at splsched with thread locked 1058 */ 1059 void 1060 sched_thread_unpromote_reason(thread_t thread, 1061 uint32_t reason, 1062 __kdebug_only uintptr_t trace_obj /* already unslid */) 1063 { 1064 assert(reason & TH_SFLAG_PROMOTE_REASON_MASK); 1065 assert((thread->sched_flags & reason) == reason); 1066 1067 switch (reason) { 1068 case TH_SFLAG_RW_PROMOTED: 1069 KDBG(MACHDBG_CODE(DBG_MACH_SCHED, MACH_RW_DEMOTE), 1070 thread_tid(thread), thread->sched_pri, 1071 thread->base_pri, trace_obj); 1072 break; 1073 case TH_SFLAG_WAITQ_PROMOTED: 1074 KDBG(MACHDBG_CODE(DBG_MACH_SCHED, MACH_WAITQ_DEMOTE), 1075 thread_tid(thread), thread->sched_pri, 1076 thread->base_pri, trace_obj); 1077 break; 1078 case TH_SFLAG_EXEC_PROMOTED: 1079 KDBG(MACHDBG_CODE(DBG_MACH_SCHED, MACH_EXEC_DEMOTE), 1080 thread_tid(thread), thread->sched_pri, 1081 thread->base_pri, trace_obj); 1082 break; 1083 } 1084 1085 thread->sched_flags &= ~reason; 1086 1087 thread_recompute_sched_pri(thread, SETPRI_DEFAULT); 1088 }