sched_ule.c revision 177009
1/*- 2 * Copyright (c) 2002-2007, Jeffrey Roberson <jeff@freebsd.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice unmodified, this list of conditions, and the following 10 * disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27/* 28 * This file implements the ULE scheduler. ULE supports independent CPU 29 * run queues and fine grain locking. It has superior interactive 30 * performance under load even on uni-processor systems. 31 * 32 * etymology: 33 * ULE is the last three letters in schedule. It owes its name to a 34 * generic user created for a scheduling system by Paul Mikesell at 35 * Isilon Systems and a general lack of creativity on the part of the author. 36 */ 37 38#include <sys/cdefs.h> 39__FBSDID("$FreeBSD: head/sys/kern/sched_ule.c 177009 2008-03-10 03:15:19Z jeff $"); 40 41#include "opt_hwpmc_hooks.h" 42#include "opt_sched.h" 43 44#include <sys/param.h> 45#include <sys/systm.h> 46#include <sys/kdb.h> 47#include <sys/kernel.h> 48#include <sys/ktr.h> 49#include <sys/lock.h> 50#include <sys/mutex.h> 51#include <sys/proc.h> 52#include <sys/resource.h> 53#include <sys/resourcevar.h> 54#include <sys/sched.h> 55#include <sys/smp.h> 56#include <sys/sx.h> 57#include <sys/sysctl.h> 58#include <sys/sysproto.h> 59#include <sys/turnstile.h> 60#include <sys/umtx.h> 61#include <sys/vmmeter.h> 62#include <sys/cpuset.h> 63#ifdef KTRACE 64#include <sys/uio.h> 65#include <sys/ktrace.h> 66#endif 67 68#ifdef HWPMC_HOOKS 69#include <sys/pmckern.h> 70#endif 71 72#include <machine/cpu.h> 73#include <machine/smp.h> 74 75#if !defined(__i386__) && !defined(__amd64__) && !defined(__powerpc__) && !defined(__arm__) 76#error "This architecture is not currently compatible with ULE" 77#endif 78 79#define KTR_ULE 0 80 81/* 82 * Thread scheduler specific section. All fields are protected 83 * by the thread lock. 84 */ 85struct td_sched { 86 TAILQ_ENTRY(td_sched) ts_procq; /* Run queue. */ 87 struct thread *ts_thread; /* Active associated thread. */ 88 struct runq *ts_runq; /* Run-queue we're queued on. */ 89 short ts_flags; /* TSF_* flags. */ 90 u_char ts_rqindex; /* Run queue index. */ 91 u_char ts_cpu; /* CPU that we have affinity for. */ 92 int ts_rltick; /* Real last tick, for affinity. */ 93 int ts_slice; /* Ticks of slice remaining. */ 94 u_int ts_slptime; /* Number of ticks we vol. slept */ 95 u_int ts_runtime; /* Number of ticks we were running */ 96 int ts_ltick; /* Last tick that we were running on */ 97 int ts_ftick; /* First tick that we were running on */ 98 int ts_ticks; /* Tick count */ 99}; 100/* flags kept in ts_flags */ 101#define TSF_BOUND 0x0001 /* Thread can not migrate. */ 102#define TSF_XFERABLE 0x0002 /* Thread was added as transferable. */ 103 104static struct td_sched td_sched0; 105 106#define THREAD_CAN_MIGRATE(td) ((td)->td_pinned == 0) 107#define THREAD_CAN_SCHED(td, cpu) \ 108 CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask) 109 110/* 111 * Cpu percentage computation macros and defines. 112 * 113 * SCHED_TICK_SECS: Number of seconds to average the cpu usage across. 114 * SCHED_TICK_TARG: Number of hz ticks to average the cpu usage across. 115 * SCHED_TICK_MAX: Maximum number of ticks before scaling back. 116 * SCHED_TICK_SHIFT: Shift factor to avoid rounding away results. 117 * SCHED_TICK_HZ: Compute the number of hz ticks for a given ticks count. 118 * SCHED_TICK_TOTAL: Gives the amount of time we've been recording ticks. 119 */ 120#define SCHED_TICK_SECS 10 121#define SCHED_TICK_TARG (hz * SCHED_TICK_SECS) 122#define SCHED_TICK_MAX (SCHED_TICK_TARG + hz) 123#define SCHED_TICK_SHIFT 10 124#define SCHED_TICK_HZ(ts) ((ts)->ts_ticks >> SCHED_TICK_SHIFT) 125#define SCHED_TICK_TOTAL(ts) (max((ts)->ts_ltick - (ts)->ts_ftick, hz)) 126 127/* 128 * These macros determine priorities for non-interactive threads. They are 129 * assigned a priority based on their recent cpu utilization as expressed 130 * by the ratio of ticks to the tick total. NHALF priorities at the start 131 * and end of the MIN to MAX timeshare range are only reachable with negative 132 * or positive nice respectively. 133 * 134 * PRI_RANGE: Priority range for utilization dependent priorities. 135 * PRI_NRESV: Number of nice values. 136 * PRI_TICKS: Compute a priority in PRI_RANGE from the ticks count and total. 137 * PRI_NICE: Determines the part of the priority inherited from nice. 138 */ 139#define SCHED_PRI_NRESV (PRIO_MAX - PRIO_MIN) 140#define SCHED_PRI_NHALF (SCHED_PRI_NRESV / 2) 141#define SCHED_PRI_MIN (PRI_MIN_TIMESHARE + SCHED_PRI_NHALF) 142#define SCHED_PRI_MAX (PRI_MAX_TIMESHARE - SCHED_PRI_NHALF) 143#define SCHED_PRI_RANGE (SCHED_PRI_MAX - SCHED_PRI_MIN) 144#define SCHED_PRI_TICKS(ts) \ 145 (SCHED_TICK_HZ((ts)) / \ 146 (roundup(SCHED_TICK_TOTAL((ts)), SCHED_PRI_RANGE) / SCHED_PRI_RANGE)) 147#define SCHED_PRI_NICE(nice) (nice) 148 149/* 150 * These determine the interactivity of a process. Interactivity differs from 151 * cpu utilization in that it expresses the voluntary time slept vs time ran 152 * while cpu utilization includes all time not running. This more accurately 153 * models the intent of the thread. 154 * 155 * SLP_RUN_MAX: Maximum amount of sleep time + run time we'll accumulate 156 * before throttling back. 157 * SLP_RUN_FORK: Maximum slp+run time to inherit at fork time. 158 * INTERACT_MAX: Maximum interactivity value. Smaller is better. 159 * INTERACT_THRESH: Threshhold for placement on the current runq. 160 */ 161#define SCHED_SLP_RUN_MAX ((hz * 5) << SCHED_TICK_SHIFT) 162#define SCHED_SLP_RUN_FORK ((hz / 2) << SCHED_TICK_SHIFT) 163#define SCHED_INTERACT_MAX (100) 164#define SCHED_INTERACT_HALF (SCHED_INTERACT_MAX / 2) 165#define SCHED_INTERACT_THRESH (30) 166 167/* 168 * tickincr: Converts a stathz tick into a hz domain scaled by 169 * the shift factor. Without the shift the error rate 170 * due to rounding would be unacceptably high. 171 * realstathz: stathz is sometimes 0 and run off of hz. 172 * sched_slice: Runtime of each thread before rescheduling. 173 * preempt_thresh: Priority threshold for preemption and remote IPIs. 174 */ 175static int sched_interact = SCHED_INTERACT_THRESH; 176static int realstathz; 177static int tickincr; 178static int sched_slice = 1; 179#ifdef PREEMPTION 180#ifdef FULL_PREEMPTION 181static int preempt_thresh = PRI_MAX_IDLE; 182#else 183static int preempt_thresh = PRI_MIN_KERN; 184#endif 185#else 186static int preempt_thresh = 0; 187#endif 188 189/* 190 * tdq - per processor runqs and statistics. All fields are protected by the 191 * tdq_lock. The load and lowpri may be accessed without to avoid excess 192 * locking in sched_pickcpu(); 193 */ 194struct tdq { 195 /* Ordered to improve efficiency of cpu_search() and switch(). */ 196 struct mtx tdq_lock; /* run queue lock. */ 197 struct cpu_group *tdq_cg; /* Pointer to cpu topology. */ 198 int tdq_load; /* Aggregate load. */ 199 int tdq_sysload; /* For loadavg, !ITHD load. */ 200 int tdq_transferable; /* Transferable thread count. */ 201 u_char tdq_lowpri; /* Lowest priority thread. */ 202 u_char tdq_ipipending; /* IPI pending. */ 203 u_char tdq_idx; /* Current insert index. */ 204 u_char tdq_ridx; /* Current removal index. */ 205 struct runq tdq_realtime; /* real-time run queue. */ 206 struct runq tdq_timeshare; /* timeshare run queue. */ 207 struct runq tdq_idle; /* Queue of IDLE threads. */ 208 char tdq_name[sizeof("sched lock") + 6]; 209} __aligned(64); 210 211 212#ifdef SMP 213struct cpu_group *cpu_top; 214 215#define SCHED_AFFINITY_DEFAULT (max(1, hz / 1000)) 216#define SCHED_AFFINITY(ts, t) ((ts)->ts_rltick > ticks - ((t) * affinity)) 217 218/* 219 * Run-time tunables. 220 */ 221static int rebalance = 1; 222static int balance_interval = 128; /* Default set in sched_initticks(). */ 223static int affinity; 224static int steal_htt = 1; 225static int steal_idle = 1; 226static int steal_thresh = 2; 227 228/* 229 * One thread queue per processor. 230 */ 231static struct tdq tdq_cpu[MAXCPU]; 232static struct tdq *balance_tdq; 233static int balance_ticks; 234 235#define TDQ_SELF() (&tdq_cpu[PCPU_GET(cpuid)]) 236#define TDQ_CPU(x) (&tdq_cpu[(x)]) 237#define TDQ_ID(x) ((int)((x) - tdq_cpu)) 238#else /* !SMP */ 239static struct tdq tdq_cpu; 240 241#define TDQ_ID(x) (0) 242#define TDQ_SELF() (&tdq_cpu) 243#define TDQ_CPU(x) (&tdq_cpu) 244#endif 245 246#define TDQ_LOCK_ASSERT(t, type) mtx_assert(TDQ_LOCKPTR((t)), (type)) 247#define TDQ_LOCK(t) mtx_lock_spin(TDQ_LOCKPTR((t))) 248#define TDQ_LOCK_FLAGS(t, f) mtx_lock_spin_flags(TDQ_LOCKPTR((t)), (f)) 249#define TDQ_UNLOCK(t) mtx_unlock_spin(TDQ_LOCKPTR((t))) 250#define TDQ_LOCKPTR(t) (&(t)->tdq_lock) 251 252static void sched_priority(struct thread *); 253static void sched_thread_priority(struct thread *, u_char); 254static int sched_interact_score(struct thread *); 255static void sched_interact_update(struct thread *); 256static void sched_interact_fork(struct thread *); 257static void sched_pctcpu_update(struct td_sched *); 258 259/* Operations on per processor queues */ 260static struct td_sched * tdq_choose(struct tdq *); 261static void tdq_setup(struct tdq *); 262static void tdq_load_add(struct tdq *, struct td_sched *); 263static void tdq_load_rem(struct tdq *, struct td_sched *); 264static __inline void tdq_runq_add(struct tdq *, struct td_sched *, int); 265static __inline void tdq_runq_rem(struct tdq *, struct td_sched *); 266static inline int sched_shouldpreempt(int, int, int); 267void tdq_print(int cpu); 268static void runq_print(struct runq *rq); 269static void tdq_add(struct tdq *, struct thread *, int); 270#ifdef SMP 271static int tdq_move(struct tdq *, struct tdq *); 272static int tdq_idled(struct tdq *); 273static void tdq_notify(struct tdq *, struct td_sched *); 274static struct td_sched *tdq_steal(struct tdq *, int); 275static struct td_sched *runq_steal(struct runq *, int); 276static int sched_pickcpu(struct td_sched *, int); 277static void sched_balance(void); 278static int sched_balance_pair(struct tdq *, struct tdq *); 279static inline struct tdq *sched_setcpu(struct td_sched *, int, int); 280static inline struct mtx *thread_block_switch(struct thread *); 281static inline void thread_unblock_switch(struct thread *, struct mtx *); 282static struct mtx *sched_switch_migrate(struct tdq *, struct thread *, int); 283#endif 284 285static void sched_setup(void *dummy); 286SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL) 287 288static void sched_initticks(void *dummy); 289SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks, NULL) 290 291/* 292 * Print the threads waiting on a run-queue. 293 */ 294static void 295runq_print(struct runq *rq) 296{ 297 struct rqhead *rqh; 298 struct td_sched *ts; 299 int pri; 300 int j; 301 int i; 302 303 for (i = 0; i < RQB_LEN; i++) { 304 printf("\t\trunq bits %d 0x%zx\n", 305 i, rq->rq_status.rqb_bits[i]); 306 for (j = 0; j < RQB_BPW; j++) 307 if (rq->rq_status.rqb_bits[i] & (1ul << j)) { 308 pri = j + (i << RQB_L2BPW); 309 rqh = &rq->rq_queues[pri]; 310 TAILQ_FOREACH(ts, rqh, ts_procq) { 311 printf("\t\t\ttd %p(%s) priority %d rqindex %d pri %d\n", 312 ts->ts_thread, ts->ts_thread->td_name, ts->ts_thread->td_priority, ts->ts_rqindex, pri); 313 } 314 } 315 } 316} 317 318/* 319 * Print the status of a per-cpu thread queue. Should be a ddb show cmd. 320 */ 321void 322tdq_print(int cpu) 323{ 324 struct tdq *tdq; 325 326 tdq = TDQ_CPU(cpu); 327 328 printf("tdq %d:\n", TDQ_ID(tdq)); 329 printf("\tlock %p\n", TDQ_LOCKPTR(tdq)); 330 printf("\tLock name: %s\n", tdq->tdq_name); 331 printf("\tload: %d\n", tdq->tdq_load); 332 printf("\ttimeshare idx: %d\n", tdq->tdq_idx); 333 printf("\ttimeshare ridx: %d\n", tdq->tdq_ridx); 334 printf("\trealtime runq:\n"); 335 runq_print(&tdq->tdq_realtime); 336 printf("\ttimeshare runq:\n"); 337 runq_print(&tdq->tdq_timeshare); 338 printf("\tidle runq:\n"); 339 runq_print(&tdq->tdq_idle); 340 printf("\tload transferable: %d\n", tdq->tdq_transferable); 341 printf("\tlowest priority: %d\n", tdq->tdq_lowpri); 342} 343 344static inline int 345sched_shouldpreempt(int pri, int cpri, int remote) 346{ 347 /* 348 * If the new priority is not better than the current priority there is 349 * nothing to do. 350 */ 351 if (pri >= cpri) 352 return (0); 353 /* 354 * Always preempt idle. 355 */ 356 if (cpri >= PRI_MIN_IDLE) 357 return (1); 358 /* 359 * If preemption is disabled don't preempt others. 360 */ 361 if (preempt_thresh == 0) 362 return (0); 363 /* 364 * Preempt if we exceed the threshold. 365 */ 366 if (pri <= preempt_thresh) 367 return (1); 368 /* 369 * If we're realtime or better and there is timeshare or worse running 370 * preempt only remote processors. 371 */ 372 if (remote && pri <= PRI_MAX_REALTIME && cpri > PRI_MAX_REALTIME) 373 return (1); 374 return (0); 375} 376 377#define TS_RQ_PPQ (((PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE) + 1) / RQ_NQS) 378/* 379 * Add a thread to the actual run-queue. Keeps transferable counts up to 380 * date with what is actually on the run-queue. Selects the correct 381 * queue position for timeshare threads. 382 */ 383static __inline void 384tdq_runq_add(struct tdq *tdq, struct td_sched *ts, int flags) 385{ 386 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 387 THREAD_LOCK_ASSERT(ts->ts_thread, MA_OWNED); 388 389 TD_SET_RUNQ(ts->ts_thread); 390 if (THREAD_CAN_MIGRATE(ts->ts_thread)) { 391 tdq->tdq_transferable++; 392 ts->ts_flags |= TSF_XFERABLE; 393 } 394 if (ts->ts_runq == &tdq->tdq_timeshare) { 395 u_char pri; 396 397 pri = ts->ts_thread->td_priority; 398 KASSERT(pri <= PRI_MAX_TIMESHARE && pri >= PRI_MIN_TIMESHARE, 399 ("Invalid priority %d on timeshare runq", pri)); 400 /* 401 * This queue contains only priorities between MIN and MAX 402 * realtime. Use the whole queue to represent these values. 403 */ 404 if ((flags & (SRQ_BORROWING|SRQ_PREEMPTED)) == 0) { 405 pri = (pri - PRI_MIN_TIMESHARE) / TS_RQ_PPQ; 406 pri = (pri + tdq->tdq_idx) % RQ_NQS; 407 /* 408 * This effectively shortens the queue by one so we 409 * can have a one slot difference between idx and 410 * ridx while we wait for threads to drain. 411 */ 412 if (tdq->tdq_ridx != tdq->tdq_idx && 413 pri == tdq->tdq_ridx) 414 pri = (unsigned char)(pri - 1) % RQ_NQS; 415 } else 416 pri = tdq->tdq_ridx; 417 runq_add_pri(ts->ts_runq, ts, pri, flags); 418 } else 419 runq_add(ts->ts_runq, ts, flags); 420} 421 422/* 423 * Pick the run queue based on priority. 424 */ 425static __inline void 426tdq_runq_pick(struct tdq *tdq, struct td_sched *ts) 427{ 428 int pri; 429 430 pri = ts->ts_thread->td_priority; 431 if (pri <= PRI_MAX_REALTIME) 432 ts->ts_runq = &tdq->tdq_realtime; 433 else if (pri <= PRI_MAX_TIMESHARE) 434 ts->ts_runq = &tdq->tdq_timeshare; 435 else 436 ts->ts_runq = &tdq->tdq_idle; 437} 438 439/* 440 * Remove a thread from a run-queue. This typically happens when a thread 441 * is selected to run. Running threads are not on the queue and the 442 * transferable count does not reflect them. 443 */ 444static __inline void 445tdq_runq_rem(struct tdq *tdq, struct td_sched *ts) 446{ 447 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 448 KASSERT(ts->ts_runq != NULL, 449 ("tdq_runq_remove: thread %p null ts_runq", ts->ts_thread)); 450 if (ts->ts_flags & TSF_XFERABLE) { 451 tdq->tdq_transferable--; 452 ts->ts_flags &= ~TSF_XFERABLE; 453 } 454 if (ts->ts_runq == &tdq->tdq_timeshare) { 455 if (tdq->tdq_idx != tdq->tdq_ridx) 456 runq_remove_idx(ts->ts_runq, ts, &tdq->tdq_ridx); 457 else 458 runq_remove_idx(ts->ts_runq, ts, NULL); 459 ts->ts_ltick = ticks; 460 } else 461 runq_remove(ts->ts_runq, ts); 462} 463 464/* 465 * Load is maintained for all threads RUNNING and ON_RUNQ. Add the load 466 * for this thread to the referenced thread queue. 467 */ 468static void 469tdq_load_add(struct tdq *tdq, struct td_sched *ts) 470{ 471 int class; 472 473 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 474 THREAD_LOCK_ASSERT(ts->ts_thread, MA_OWNED); 475 class = PRI_BASE(ts->ts_thread->td_pri_class); 476 tdq->tdq_load++; 477 CTR2(KTR_SCHED, "cpu %d load: %d", TDQ_ID(tdq), tdq->tdq_load); 478 if (class != PRI_ITHD && 479 (ts->ts_thread->td_proc->p_flag & P_NOLOAD) == 0) 480 tdq->tdq_sysload++; 481} 482 483/* 484 * Remove the load from a thread that is transitioning to a sleep state or 485 * exiting. 486 */ 487static void 488tdq_load_rem(struct tdq *tdq, struct td_sched *ts) 489{ 490 int class; 491 492 THREAD_LOCK_ASSERT(ts->ts_thread, MA_OWNED); 493 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 494 class = PRI_BASE(ts->ts_thread->td_pri_class); 495 if (class != PRI_ITHD && 496 (ts->ts_thread->td_proc->p_flag & P_NOLOAD) == 0) 497 tdq->tdq_sysload--; 498 KASSERT(tdq->tdq_load != 0, 499 ("tdq_load_rem: Removing with 0 load on queue %d", TDQ_ID(tdq))); 500 tdq->tdq_load--; 501 CTR1(KTR_SCHED, "load: %d", tdq->tdq_load); 502 ts->ts_runq = NULL; 503} 504 505/* 506 * Set lowpri to its exact value by searching the run-queue and 507 * evaluating curthread. curthread may be passed as an optimization. 508 */ 509static void 510tdq_setlowpri(struct tdq *tdq, struct thread *ctd) 511{ 512 struct td_sched *ts; 513 struct thread *td; 514 515 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 516 if (ctd == NULL) 517 ctd = pcpu_find(TDQ_ID(tdq))->pc_curthread; 518 ts = tdq_choose(tdq); 519 if (ts) 520 td = ts->ts_thread; 521 if (ts == NULL || td->td_priority > ctd->td_priority) 522 tdq->tdq_lowpri = ctd->td_priority; 523 else 524 tdq->tdq_lowpri = td->td_priority; 525} 526 527#ifdef SMP 528struct cpu_search { 529 cpumask_t cs_mask; /* Mask of valid cpus. */ 530 u_int cs_load; 531 u_int cs_cpu; 532 int cs_limit; /* Min priority for low min load for high. */ 533}; 534 535#define CPU_SEARCH_LOWEST 0x1 536#define CPU_SEARCH_HIGHEST 0x2 537#define CPU_SEARCH_BOTH (CPU_SEARCH_LOWEST|CPU_SEARCH_HIGHEST) 538 539#define CPUMASK_FOREACH(cpu, mask) \ 540 for ((cpu) = 0; (cpu) < sizeof((mask)) * 8; (cpu)++) \ 541 if ((mask) & 1 << (cpu)) 542 543__inline int cpu_search(struct cpu_group *cg, struct cpu_search *low, 544 struct cpu_search *high, const int match); 545int cpu_search_lowest(struct cpu_group *cg, struct cpu_search *low); 546int cpu_search_highest(struct cpu_group *cg, struct cpu_search *high); 547int cpu_search_both(struct cpu_group *cg, struct cpu_search *low, 548 struct cpu_search *high); 549 550/* 551 * This routine compares according to the match argument and should be 552 * reduced in actual instantiations via constant propagation and dead code 553 * elimination. 554 */ 555static __inline int 556cpu_compare(int cpu, struct cpu_search *low, struct cpu_search *high, 557 const int match) 558{ 559 struct tdq *tdq; 560 561 tdq = TDQ_CPU(cpu); 562 if (match & CPU_SEARCH_LOWEST) 563 if (low->cs_mask & (1 << cpu) && 564 tdq->tdq_load < low->cs_load && 565 tdq->tdq_lowpri > low->cs_limit) { 566 low->cs_cpu = cpu; 567 low->cs_load = tdq->tdq_load; 568 } 569 if (match & CPU_SEARCH_HIGHEST) 570 if (high->cs_mask & (1 << cpu) && 571 tdq->tdq_load >= high->cs_limit && 572 tdq->tdq_load > high->cs_load && 573 tdq->tdq_transferable) { 574 high->cs_cpu = cpu; 575 high->cs_load = tdq->tdq_load; 576 } 577 return (tdq->tdq_load); 578} 579 580/* 581 * Search the tree of cpu_groups for the lowest or highest loaded cpu 582 * according to the match argument. This routine actually compares the 583 * load on all paths through the tree and finds the least loaded cpu on 584 * the least loaded path, which may differ from the least loaded cpu in 585 * the system. This balances work among caches and busses. 586 * 587 * This inline is instantiated in three forms below using constants for the 588 * match argument. It is reduced to the minimum set for each case. It is 589 * also recursive to the depth of the tree. 590 */ 591static inline int 592cpu_search(struct cpu_group *cg, struct cpu_search *low, 593 struct cpu_search *high, const int match) 594{ 595 int total; 596 597 total = 0; 598 if (cg->cg_children) { 599 struct cpu_search lgroup; 600 struct cpu_search hgroup; 601 struct cpu_group *child; 602 u_int lload; 603 int hload; 604 int load; 605 int i; 606 607 lload = -1; 608 hload = -1; 609 for (i = 0; i < cg->cg_children; i++) { 610 child = &cg->cg_child[i]; 611 if (match & CPU_SEARCH_LOWEST) { 612 lgroup = *low; 613 lgroup.cs_load = -1; 614 } 615 if (match & CPU_SEARCH_HIGHEST) { 616 hgroup = *high; 617 lgroup.cs_load = 0; 618 } 619 switch (match) { 620 case CPU_SEARCH_LOWEST: 621 load = cpu_search_lowest(child, &lgroup); 622 break; 623 case CPU_SEARCH_HIGHEST: 624 load = cpu_search_highest(child, &hgroup); 625 break; 626 case CPU_SEARCH_BOTH: 627 load = cpu_search_both(child, &lgroup, &hgroup); 628 break; 629 } 630 total += load; 631 if (match & CPU_SEARCH_LOWEST) 632 if (load < lload || low->cs_cpu == -1) { 633 *low = lgroup; 634 lload = load; 635 } 636 if (match & CPU_SEARCH_HIGHEST) 637 if (load > hload || high->cs_cpu == -1) { 638 hload = load; 639 *high = hgroup; 640 } 641 } 642 } else { 643 int cpu; 644 645 CPUMASK_FOREACH(cpu, cg->cg_mask) 646 total += cpu_compare(cpu, low, high, match); 647 } 648 return (total); 649} 650 651/* 652 * cpu_search instantiations must pass constants to maintain the inline 653 * optimization. 654 */ 655int 656cpu_search_lowest(struct cpu_group *cg, struct cpu_search *low) 657{ 658 return cpu_search(cg, low, NULL, CPU_SEARCH_LOWEST); 659} 660 661int 662cpu_search_highest(struct cpu_group *cg, struct cpu_search *high) 663{ 664 return cpu_search(cg, NULL, high, CPU_SEARCH_HIGHEST); 665} 666 667int 668cpu_search_both(struct cpu_group *cg, struct cpu_search *low, 669 struct cpu_search *high) 670{ 671 return cpu_search(cg, low, high, CPU_SEARCH_BOTH); 672} 673 674/* 675 * Find the cpu with the least load via the least loaded path that has a 676 * lowpri greater than pri pri. A pri of -1 indicates any priority is 677 * acceptable. 678 */ 679static inline int 680sched_lowest(struct cpu_group *cg, cpumask_t mask, int pri) 681{ 682 struct cpu_search low; 683 684 low.cs_cpu = -1; 685 low.cs_load = -1; 686 low.cs_mask = mask; 687 low.cs_limit = pri; 688 cpu_search_lowest(cg, &low); 689 return low.cs_cpu; 690} 691 692/* 693 * Find the cpu with the highest load via the highest loaded path. 694 */ 695static inline int 696sched_highest(struct cpu_group *cg, cpumask_t mask, int minload) 697{ 698 struct cpu_search high; 699 700 high.cs_cpu = -1; 701 high.cs_load = 0; 702 high.cs_mask = mask; 703 high.cs_limit = minload; 704 cpu_search_highest(cg, &high); 705 return high.cs_cpu; 706} 707 708/* 709 * Simultaneously find the highest and lowest loaded cpu reachable via 710 * cg. 711 */ 712static inline void 713sched_both(struct cpu_group *cg, cpumask_t mask, int *lowcpu, int *highcpu) 714{ 715 struct cpu_search high; 716 struct cpu_search low; 717 718 low.cs_cpu = -1; 719 low.cs_limit = -1; 720 low.cs_load = -1; 721 low.cs_mask = mask; 722 high.cs_load = 0; 723 high.cs_cpu = -1; 724 high.cs_limit = -1; 725 high.cs_mask = mask; 726 cpu_search_both(cg, &low, &high); 727 *lowcpu = low.cs_cpu; 728 *highcpu = high.cs_cpu; 729 return; 730} 731 732static void 733sched_balance_group(struct cpu_group *cg) 734{ 735 cpumask_t mask; 736 int high; 737 int low; 738 int i; 739 740 mask = -1; 741 for (;;) { 742 sched_both(cg, mask, &low, &high); 743 if (low == high || low == -1 || high == -1) 744 break; 745 if (sched_balance_pair(TDQ_CPU(high), TDQ_CPU(low))) 746 break; 747 /* 748 * If we failed to move any threads determine which cpu 749 * to kick out of the set and try again. 750 */ 751 if (TDQ_CPU(high)->tdq_transferable == 0) 752 mask &= ~(1 << high); 753 else 754 mask &= ~(1 << low); 755 } 756 757 for (i = 0; i < cg->cg_children; i++) 758 sched_balance_group(&cg->cg_child[i]); 759} 760 761static void 762sched_balance() 763{ 764 struct tdq *tdq; 765 766 /* 767 * Select a random time between .5 * balance_interval and 768 * 1.5 * balance_interval. 769 */ 770 balance_ticks = max(balance_interval / 2, 1); 771 balance_ticks += random() % balance_interval; 772 if (smp_started == 0 || rebalance == 0) 773 return; 774 tdq = TDQ_SELF(); 775 TDQ_UNLOCK(tdq); 776 sched_balance_group(cpu_top); 777 TDQ_LOCK(tdq); 778} 779 780/* 781 * Lock two thread queues using their address to maintain lock order. 782 */ 783static void 784tdq_lock_pair(struct tdq *one, struct tdq *two) 785{ 786 if (one < two) { 787 TDQ_LOCK(one); 788 TDQ_LOCK_FLAGS(two, MTX_DUPOK); 789 } else { 790 TDQ_LOCK(two); 791 TDQ_LOCK_FLAGS(one, MTX_DUPOK); 792 } 793} 794 795/* 796 * Unlock two thread queues. Order is not important here. 797 */ 798static void 799tdq_unlock_pair(struct tdq *one, struct tdq *two) 800{ 801 TDQ_UNLOCK(one); 802 TDQ_UNLOCK(two); 803} 804 805/* 806 * Transfer load between two imbalanced thread queues. 807 */ 808static int 809sched_balance_pair(struct tdq *high, struct tdq *low) 810{ 811 int transferable; 812 int high_load; 813 int low_load; 814 int moved; 815 int move; 816 int diff; 817 int i; 818 819 tdq_lock_pair(high, low); 820 transferable = high->tdq_transferable; 821 high_load = high->tdq_load; 822 low_load = low->tdq_load; 823 moved = 0; 824 /* 825 * Determine what the imbalance is and then adjust that to how many 826 * threads we actually have to give up (transferable). 827 */ 828 if (transferable != 0) { 829 diff = high_load - low_load; 830 move = diff / 2; 831 if (diff & 0x1) 832 move++; 833 move = min(move, transferable); 834 for (i = 0; i < move; i++) 835 moved += tdq_move(high, low); 836 /* 837 * IPI the target cpu to force it to reschedule with the new 838 * workload. 839 */ 840 ipi_selected(1 << TDQ_ID(low), IPI_PREEMPT); 841 } 842 tdq_unlock_pair(high, low); 843 return (moved); 844} 845 846/* 847 * Move a thread from one thread queue to another. 848 */ 849static int 850tdq_move(struct tdq *from, struct tdq *to) 851{ 852 struct td_sched *ts; 853 struct thread *td; 854 struct tdq *tdq; 855 int cpu; 856 857 TDQ_LOCK_ASSERT(from, MA_OWNED); 858 TDQ_LOCK_ASSERT(to, MA_OWNED); 859 860 tdq = from; 861 cpu = TDQ_ID(to); 862 ts = tdq_steal(tdq, cpu); 863 if (ts == NULL) 864 return (0); 865 td = ts->ts_thread; 866 /* 867 * Although the run queue is locked the thread may be blocked. Lock 868 * it to clear this and acquire the run-queue lock. 869 */ 870 thread_lock(td); 871 /* Drop recursive lock on from acquired via thread_lock(). */ 872 TDQ_UNLOCK(from); 873 sched_rem(td); 874 ts->ts_cpu = cpu; 875 td->td_lock = TDQ_LOCKPTR(to); 876 tdq_add(to, td, SRQ_YIELDING); 877 return (1); 878} 879 880/* 881 * This tdq has idled. Try to steal a thread from another cpu and switch 882 * to it. 883 */ 884static int 885tdq_idled(struct tdq *tdq) 886{ 887 struct cpu_group *cg; 888 struct tdq *steal; 889 cpumask_t mask; 890 int thresh; 891 int cpu; 892 893 if (smp_started == 0 || steal_idle == 0) 894 return (1); 895 mask = -1; 896 mask &= ~PCPU_GET(cpumask); 897 /* We don't want to be preempted while we're iterating. */ 898 spinlock_enter(); 899 for (cg = tdq->tdq_cg; cg != NULL; ) { 900 if ((cg->cg_flags & (CG_FLAG_HTT | CG_FLAG_THREAD)) == 0) 901 thresh = steal_thresh; 902 else 903 thresh = 1; 904 cpu = sched_highest(cg, mask, thresh); 905 if (cpu == -1) { 906 cg = cg->cg_parent; 907 continue; 908 } 909 steal = TDQ_CPU(cpu); 910 mask &= ~(1 << cpu); 911 tdq_lock_pair(tdq, steal); 912 if (steal->tdq_load < thresh || steal->tdq_transferable == 0) { 913 tdq_unlock_pair(tdq, steal); 914 continue; 915 } 916 /* 917 * If a thread was added while interrupts were disabled don't 918 * steal one here. If we fail to acquire one due to affinity 919 * restrictions loop again with this cpu removed from the 920 * set. 921 */ 922 if (tdq->tdq_load == 0 && tdq_move(steal, tdq) == 0) { 923 tdq_unlock_pair(tdq, steal); 924 continue; 925 } 926 spinlock_exit(); 927 TDQ_UNLOCK(steal); 928 mi_switch(SW_VOL, NULL); 929 thread_unlock(curthread); 930 931 return (0); 932 } 933 spinlock_exit(); 934 return (1); 935} 936 937/* 938 * Notify a remote cpu of new work. Sends an IPI if criteria are met. 939 */ 940static void 941tdq_notify(struct tdq *tdq, struct td_sched *ts) 942{ 943 int cpri; 944 int pri; 945 int cpu; 946 947 if (tdq->tdq_ipipending) 948 return; 949 cpu = ts->ts_cpu; 950 pri = ts->ts_thread->td_priority; 951 cpri = pcpu_find(cpu)->pc_curthread->td_priority; 952 if (!sched_shouldpreempt(pri, cpri, 1)) 953 return; 954 tdq->tdq_ipipending = 1; 955 ipi_selected(1 << cpu, IPI_PREEMPT); 956} 957 958/* 959 * Steals load from a timeshare queue. Honors the rotating queue head 960 * index. 961 */ 962static struct td_sched * 963runq_steal_from(struct runq *rq, int cpu, u_char start) 964{ 965 struct td_sched *ts; 966 struct rqbits *rqb; 967 struct rqhead *rqh; 968 int first; 969 int bit; 970 int pri; 971 int i; 972 973 rqb = &rq->rq_status; 974 bit = start & (RQB_BPW -1); 975 pri = 0; 976 first = 0; 977again: 978 for (i = RQB_WORD(start); i < RQB_LEN; bit = 0, i++) { 979 if (rqb->rqb_bits[i] == 0) 980 continue; 981 if (bit != 0) { 982 for (pri = bit; pri < RQB_BPW; pri++) 983 if (rqb->rqb_bits[i] & (1ul << pri)) 984 break; 985 if (pri >= RQB_BPW) 986 continue; 987 } else 988 pri = RQB_FFS(rqb->rqb_bits[i]); 989 pri += (i << RQB_L2BPW); 990 rqh = &rq->rq_queues[pri]; 991 TAILQ_FOREACH(ts, rqh, ts_procq) { 992 if (first && THREAD_CAN_MIGRATE(ts->ts_thread) && 993 THREAD_CAN_SCHED(ts->ts_thread, cpu)) 994 return (ts); 995 first = 1; 996 } 997 } 998 if (start != 0) { 999 start = 0; 1000 goto again; 1001 } 1002 1003 return (NULL); 1004} 1005 1006/* 1007 * Steals load from a standard linear queue. 1008 */ 1009static struct td_sched * 1010runq_steal(struct runq *rq, int cpu) 1011{ 1012 struct rqhead *rqh; 1013 struct rqbits *rqb; 1014 struct td_sched *ts; 1015 int word; 1016 int bit; 1017 1018 rqb = &rq->rq_status; 1019 for (word = 0; word < RQB_LEN; word++) { 1020 if (rqb->rqb_bits[word] == 0) 1021 continue; 1022 for (bit = 0; bit < RQB_BPW; bit++) { 1023 if ((rqb->rqb_bits[word] & (1ul << bit)) == 0) 1024 continue; 1025 rqh = &rq->rq_queues[bit + (word << RQB_L2BPW)]; 1026 TAILQ_FOREACH(ts, rqh, ts_procq) 1027 if (THREAD_CAN_MIGRATE(ts->ts_thread) && 1028 THREAD_CAN_SCHED(ts->ts_thread, cpu)) 1029 return (ts); 1030 } 1031 } 1032 return (NULL); 1033} 1034 1035/* 1036 * Attempt to steal a thread in priority order from a thread queue. 1037 */ 1038static struct td_sched * 1039tdq_steal(struct tdq *tdq, int cpu) 1040{ 1041 struct td_sched *ts; 1042 1043 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1044 if ((ts = runq_steal(&tdq->tdq_realtime, cpu)) != NULL) 1045 return (ts); 1046 if ((ts = runq_steal_from(&tdq->tdq_timeshare, cpu, tdq->tdq_ridx)) 1047 != NULL) 1048 return (ts); 1049 return (runq_steal(&tdq->tdq_idle, cpu)); 1050} 1051 1052/* 1053 * Sets the thread lock and ts_cpu to match the requested cpu. Unlocks the 1054 * current lock and returns with the assigned queue locked. 1055 */ 1056static inline struct tdq * 1057sched_setcpu(struct td_sched *ts, int cpu, int flags) 1058{ 1059 struct thread *td; 1060 struct tdq *tdq; 1061 1062 THREAD_LOCK_ASSERT(ts->ts_thread, MA_OWNED); 1063 1064 tdq = TDQ_CPU(cpu); 1065 td = ts->ts_thread; 1066 ts->ts_cpu = cpu; 1067 1068 /* If the lock matches just return the queue. */ 1069 if (td->td_lock == TDQ_LOCKPTR(tdq)) 1070 return (tdq); 1071#ifdef notyet 1072 /* 1073 * If the thread isn't running its lockptr is a 1074 * turnstile or a sleepqueue. We can just lock_set without 1075 * blocking. 1076 */ 1077 if (TD_CAN_RUN(td)) { 1078 TDQ_LOCK(tdq); 1079 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 1080 return (tdq); 1081 } 1082#endif 1083 /* 1084 * The hard case, migration, we need to block the thread first to 1085 * prevent order reversals with other cpus locks. 1086 */ 1087 thread_lock_block(td); 1088 TDQ_LOCK(tdq); 1089 thread_lock_unblock(td, TDQ_LOCKPTR(tdq)); 1090 return (tdq); 1091} 1092 1093static int 1094sched_pickcpu(struct td_sched *ts, int flags) 1095{ 1096 struct cpu_group *cg; 1097 struct thread *td; 1098 struct tdq *tdq; 1099 cpumask_t mask; 1100 int self; 1101 int pri; 1102 int cpu; 1103 1104 self = PCPU_GET(cpuid); 1105 td = ts->ts_thread; 1106 if (smp_started == 0) 1107 return (self); 1108 /* 1109 * Don't migrate a running thread from sched_switch(). 1110 */ 1111 if ((flags & SRQ_OURSELF) || !THREAD_CAN_MIGRATE(td)) 1112 return (ts->ts_cpu); 1113 /* 1114 * Prefer to run interrupt threads on the processors that generate 1115 * the interrupt. 1116 */ 1117 if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_SCHED(td, self) && 1118 curthread->td_intr_nesting_level) 1119 ts->ts_cpu = self; 1120 /* 1121 * If the thread can run on the last cpu and the affinity has not 1122 * expired or it is idle run it there. 1123 */ 1124 pri = td->td_priority; 1125 tdq = TDQ_CPU(ts->ts_cpu); 1126 if (THREAD_CAN_SCHED(td, ts->ts_cpu)) { 1127 if (tdq->tdq_lowpri > PRI_MIN_IDLE) 1128 return (ts->ts_cpu); 1129 if (SCHED_AFFINITY(ts, CG_SHARE_L2) && tdq->tdq_lowpri > pri) 1130 return (ts->ts_cpu); 1131 } 1132 /* 1133 * Search for the highest level in the tree that still has affinity. 1134 */ 1135 cg = NULL; 1136 for (cg = tdq->tdq_cg; cg != NULL; cg = cg->cg_parent) 1137 if (SCHED_AFFINITY(ts, cg->cg_level)) 1138 break; 1139 cpu = -1; 1140 mask = td->td_cpuset->cs_mask.__bits[0]; 1141 if (cg) 1142 cpu = sched_lowest(cg, mask, pri); 1143 if (cpu == -1) 1144 cpu = sched_lowest(cpu_top, mask, -1); 1145 /* 1146 * Compare the lowest loaded cpu to current cpu. 1147 */ 1148 if (THREAD_CAN_SCHED(td, self) && TDQ_CPU(self)->tdq_lowpri > pri && 1149 TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE) 1150 cpu = self; 1151 KASSERT(cpu != -1, ("sched_pickcpu: Failed to find a cpu.")); 1152 return (cpu); 1153} 1154#endif 1155 1156/* 1157 * Pick the highest priority task we have and return it. 1158 */ 1159static struct td_sched * 1160tdq_choose(struct tdq *tdq) 1161{ 1162 struct td_sched *ts; 1163 1164 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1165 ts = runq_choose(&tdq->tdq_realtime); 1166 if (ts != NULL) 1167 return (ts); 1168 ts = runq_choose_from(&tdq->tdq_timeshare, tdq->tdq_ridx); 1169 if (ts != NULL) { 1170 KASSERT(ts->ts_thread->td_priority >= PRI_MIN_TIMESHARE, 1171 ("tdq_choose: Invalid priority on timeshare queue %d", 1172 ts->ts_thread->td_priority)); 1173 return (ts); 1174 } 1175 1176 ts = runq_choose(&tdq->tdq_idle); 1177 if (ts != NULL) { 1178 KASSERT(ts->ts_thread->td_priority >= PRI_MIN_IDLE, 1179 ("tdq_choose: Invalid priority on idle queue %d", 1180 ts->ts_thread->td_priority)); 1181 return (ts); 1182 } 1183 1184 return (NULL); 1185} 1186 1187/* 1188 * Initialize a thread queue. 1189 */ 1190static void 1191tdq_setup(struct tdq *tdq) 1192{ 1193 1194 if (bootverbose) 1195 printf("ULE: setup cpu %d\n", TDQ_ID(tdq)); 1196 runq_init(&tdq->tdq_realtime); 1197 runq_init(&tdq->tdq_timeshare); 1198 runq_init(&tdq->tdq_idle); 1199 snprintf(tdq->tdq_name, sizeof(tdq->tdq_name), 1200 "sched lock %d", (int)TDQ_ID(tdq)); 1201 mtx_init(&tdq->tdq_lock, tdq->tdq_name, "sched lock", 1202 MTX_SPIN | MTX_RECURSE); 1203} 1204 1205#ifdef SMP 1206static void 1207sched_setup_smp(void) 1208{ 1209 struct tdq *tdq; 1210 int i; 1211 1212 cpu_top = smp_topo(); 1213 for (i = 0; i < MAXCPU; i++) { 1214 if (CPU_ABSENT(i)) 1215 continue; 1216 tdq = TDQ_CPU(i); 1217 tdq_setup(tdq); 1218 tdq->tdq_cg = smp_topo_find(cpu_top, i); 1219 if (tdq->tdq_cg == NULL) 1220 panic("Can't find cpu group for %d\n", i); 1221 } 1222 balance_tdq = TDQ_SELF(); 1223 sched_balance(); 1224} 1225#endif 1226 1227/* 1228 * Setup the thread queues and initialize the topology based on MD 1229 * information. 1230 */ 1231static void 1232sched_setup(void *dummy) 1233{ 1234 struct tdq *tdq; 1235 1236 tdq = TDQ_SELF(); 1237#ifdef SMP 1238 sched_setup_smp(); 1239#else 1240 tdq_setup(tdq); 1241#endif 1242 /* 1243 * To avoid divide-by-zero, we set realstathz a dummy value 1244 * in case which sched_clock() called before sched_initticks(). 1245 */ 1246 realstathz = hz; 1247 sched_slice = (realstathz/10); /* ~100ms */ 1248 tickincr = 1 << SCHED_TICK_SHIFT; 1249 1250 /* Add thread0's load since it's running. */ 1251 TDQ_LOCK(tdq); 1252 thread0.td_lock = TDQ_LOCKPTR(TDQ_SELF()); 1253 tdq_load_add(tdq, &td_sched0); 1254 tdq->tdq_lowpri = thread0.td_priority; 1255 TDQ_UNLOCK(tdq); 1256} 1257 1258/* 1259 * This routine determines the tickincr after stathz and hz are setup. 1260 */ 1261/* ARGSUSED */ 1262static void 1263sched_initticks(void *dummy) 1264{ 1265 int incr; 1266 1267 realstathz = stathz ? stathz : hz; 1268 sched_slice = (realstathz/10); /* ~100ms */ 1269 1270 /* 1271 * tickincr is shifted out by 10 to avoid rounding errors due to 1272 * hz not being evenly divisible by stathz on all platforms. 1273 */ 1274 incr = (hz << SCHED_TICK_SHIFT) / realstathz; 1275 /* 1276 * This does not work for values of stathz that are more than 1277 * 1 << SCHED_TICK_SHIFT * hz. In practice this does not happen. 1278 */ 1279 if (incr == 0) 1280 incr = 1; 1281 tickincr = incr; 1282#ifdef SMP 1283 /* 1284 * Set the default balance interval now that we know 1285 * what realstathz is. 1286 */ 1287 balance_interval = realstathz; 1288 /* 1289 * Set steal thresh to log2(mp_ncpu) but no greater than 4. This 1290 * prevents excess thrashing on large machines and excess idle on 1291 * smaller machines. 1292 */ 1293 steal_thresh = min(ffs(mp_ncpus) - 1, 3); 1294 affinity = SCHED_AFFINITY_DEFAULT; 1295#endif 1296} 1297 1298 1299/* 1300 * This is the core of the interactivity algorithm. Determines a score based 1301 * on past behavior. It is the ratio of sleep time to run time scaled to 1302 * a [0, 100] integer. This is the voluntary sleep time of a process, which 1303 * differs from the cpu usage because it does not account for time spent 1304 * waiting on a run-queue. Would be prettier if we had floating point. 1305 */ 1306static int 1307sched_interact_score(struct thread *td) 1308{ 1309 struct td_sched *ts; 1310 int div; 1311 1312 ts = td->td_sched; 1313 /* 1314 * The score is only needed if this is likely to be an interactive 1315 * task. Don't go through the expense of computing it if there's 1316 * no chance. 1317 */ 1318 if (sched_interact <= SCHED_INTERACT_HALF && 1319 ts->ts_runtime >= ts->ts_slptime) 1320 return (SCHED_INTERACT_HALF); 1321 1322 if (ts->ts_runtime > ts->ts_slptime) { 1323 div = max(1, ts->ts_runtime / SCHED_INTERACT_HALF); 1324 return (SCHED_INTERACT_HALF + 1325 (SCHED_INTERACT_HALF - (ts->ts_slptime / div))); 1326 } 1327 if (ts->ts_slptime > ts->ts_runtime) { 1328 div = max(1, ts->ts_slptime / SCHED_INTERACT_HALF); 1329 return (ts->ts_runtime / div); 1330 } 1331 /* runtime == slptime */ 1332 if (ts->ts_runtime) 1333 return (SCHED_INTERACT_HALF); 1334 1335 /* 1336 * This can happen if slptime and runtime are 0. 1337 */ 1338 return (0); 1339 1340} 1341 1342/* 1343 * Scale the scheduling priority according to the "interactivity" of this 1344 * process. 1345 */ 1346static void 1347sched_priority(struct thread *td) 1348{ 1349 int score; 1350 int pri; 1351 1352 if (td->td_pri_class != PRI_TIMESHARE) 1353 return; 1354 /* 1355 * If the score is interactive we place the thread in the realtime 1356 * queue with a priority that is less than kernel and interrupt 1357 * priorities. These threads are not subject to nice restrictions. 1358 * 1359 * Scores greater than this are placed on the normal timeshare queue 1360 * where the priority is partially decided by the most recent cpu 1361 * utilization and the rest is decided by nice value. 1362 * 1363 * The nice value of the process has a linear effect on the calculated 1364 * score. Negative nice values make it easier for a thread to be 1365 * considered interactive. 1366 */ 1367 score = imax(0, sched_interact_score(td) - td->td_proc->p_nice); 1368 if (score < sched_interact) { 1369 pri = PRI_MIN_REALTIME; 1370 pri += ((PRI_MAX_REALTIME - PRI_MIN_REALTIME) / sched_interact) 1371 * score; 1372 KASSERT(pri >= PRI_MIN_REALTIME && pri <= PRI_MAX_REALTIME, 1373 ("sched_priority: invalid interactive priority %d score %d", 1374 pri, score)); 1375 } else { 1376 pri = SCHED_PRI_MIN; 1377 if (td->td_sched->ts_ticks) 1378 pri += SCHED_PRI_TICKS(td->td_sched); 1379 pri += SCHED_PRI_NICE(td->td_proc->p_nice); 1380 KASSERT(pri >= PRI_MIN_TIMESHARE && pri <= PRI_MAX_TIMESHARE, 1381 ("sched_priority: invalid priority %d: nice %d, " 1382 "ticks %d ftick %d ltick %d tick pri %d", 1383 pri, td->td_proc->p_nice, td->td_sched->ts_ticks, 1384 td->td_sched->ts_ftick, td->td_sched->ts_ltick, 1385 SCHED_PRI_TICKS(td->td_sched))); 1386 } 1387 sched_user_prio(td, pri); 1388 1389 return; 1390} 1391 1392/* 1393 * This routine enforces a maximum limit on the amount of scheduling history 1394 * kept. It is called after either the slptime or runtime is adjusted. This 1395 * function is ugly due to integer math. 1396 */ 1397static void 1398sched_interact_update(struct thread *td) 1399{ 1400 struct td_sched *ts; 1401 u_int sum; 1402 1403 ts = td->td_sched; 1404 sum = ts->ts_runtime + ts->ts_slptime; 1405 if (sum < SCHED_SLP_RUN_MAX) 1406 return; 1407 /* 1408 * This only happens from two places: 1409 * 1) We have added an unusual amount of run time from fork_exit. 1410 * 2) We have added an unusual amount of sleep time from sched_sleep(). 1411 */ 1412 if (sum > SCHED_SLP_RUN_MAX * 2) { 1413 if (ts->ts_runtime > ts->ts_slptime) { 1414 ts->ts_runtime = SCHED_SLP_RUN_MAX; 1415 ts->ts_slptime = 1; 1416 } else { 1417 ts->ts_slptime = SCHED_SLP_RUN_MAX; 1418 ts->ts_runtime = 1; 1419 } 1420 return; 1421 } 1422 /* 1423 * If we have exceeded by more than 1/5th then the algorithm below 1424 * will not bring us back into range. Dividing by two here forces 1425 * us into the range of [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX] 1426 */ 1427 if (sum > (SCHED_SLP_RUN_MAX / 5) * 6) { 1428 ts->ts_runtime /= 2; 1429 ts->ts_slptime /= 2; 1430 return; 1431 } 1432 ts->ts_runtime = (ts->ts_runtime / 5) * 4; 1433 ts->ts_slptime = (ts->ts_slptime / 5) * 4; 1434} 1435 1436/* 1437 * Scale back the interactivity history when a child thread is created. The 1438 * history is inherited from the parent but the thread may behave totally 1439 * differently. For example, a shell spawning a compiler process. We want 1440 * to learn that the compiler is behaving badly very quickly. 1441 */ 1442static void 1443sched_interact_fork(struct thread *td) 1444{ 1445 int ratio; 1446 int sum; 1447 1448 sum = td->td_sched->ts_runtime + td->td_sched->ts_slptime; 1449 if (sum > SCHED_SLP_RUN_FORK) { 1450 ratio = sum / SCHED_SLP_RUN_FORK; 1451 td->td_sched->ts_runtime /= ratio; 1452 td->td_sched->ts_slptime /= ratio; 1453 } 1454} 1455 1456/* 1457 * Called from proc0_init() to setup the scheduler fields. 1458 */ 1459void 1460schedinit(void) 1461{ 1462 1463 /* 1464 * Set up the scheduler specific parts of proc0. 1465 */ 1466 proc0.p_sched = NULL; /* XXX */ 1467 thread0.td_sched = &td_sched0; 1468 td_sched0.ts_ltick = ticks; 1469 td_sched0.ts_ftick = ticks; 1470 td_sched0.ts_thread = &thread0; 1471 td_sched0.ts_slice = sched_slice; 1472} 1473 1474/* 1475 * This is only somewhat accurate since given many processes of the same 1476 * priority they will switch when their slices run out, which will be 1477 * at most sched_slice stathz ticks. 1478 */ 1479int 1480sched_rr_interval(void) 1481{ 1482 1483 /* Convert sched_slice to hz */ 1484 return (hz/(realstathz/sched_slice)); 1485} 1486 1487/* 1488 * Update the percent cpu tracking information when it is requested or 1489 * the total history exceeds the maximum. We keep a sliding history of 1490 * tick counts that slowly decays. This is less precise than the 4BSD 1491 * mechanism since it happens with less regular and frequent events. 1492 */ 1493static void 1494sched_pctcpu_update(struct td_sched *ts) 1495{ 1496 1497 if (ts->ts_ticks == 0) 1498 return; 1499 if (ticks - (hz / 10) < ts->ts_ltick && 1500 SCHED_TICK_TOTAL(ts) < SCHED_TICK_MAX) 1501 return; 1502 /* 1503 * Adjust counters and watermark for pctcpu calc. 1504 */ 1505 if (ts->ts_ltick > ticks - SCHED_TICK_TARG) 1506 ts->ts_ticks = (ts->ts_ticks / (ticks - ts->ts_ftick)) * 1507 SCHED_TICK_TARG; 1508 else 1509 ts->ts_ticks = 0; 1510 ts->ts_ltick = ticks; 1511 ts->ts_ftick = ts->ts_ltick - SCHED_TICK_TARG; 1512} 1513 1514/* 1515 * Adjust the priority of a thread. Move it to the appropriate run-queue 1516 * if necessary. This is the back-end for several priority related 1517 * functions. 1518 */ 1519static void 1520sched_thread_priority(struct thread *td, u_char prio) 1521{ 1522 struct td_sched *ts; 1523 struct tdq *tdq; 1524 int oldpri; 1525 1526 CTR6(KTR_SCHED, "sched_prio: %p(%s) prio %d newprio %d by %p(%s)", 1527 td, td->td_name, td->td_priority, prio, curthread, 1528 curthread->td_name); 1529 ts = td->td_sched; 1530 THREAD_LOCK_ASSERT(td, MA_OWNED); 1531 if (td->td_priority == prio) 1532 return; 1533 1534 if (TD_ON_RUNQ(td) && prio < td->td_priority) { 1535 /* 1536 * If the priority has been elevated due to priority 1537 * propagation, we may have to move ourselves to a new 1538 * queue. This could be optimized to not re-add in some 1539 * cases. 1540 */ 1541 sched_rem(td); 1542 td->td_priority = prio; 1543 sched_add(td, SRQ_BORROWING); 1544 return; 1545 } 1546 tdq = TDQ_CPU(ts->ts_cpu); 1547 oldpri = td->td_priority; 1548 td->td_priority = prio; 1549 tdq_runq_pick(tdq, ts); 1550 if (TD_IS_RUNNING(td)) { 1551 if (prio < tdq->tdq_lowpri) 1552 tdq->tdq_lowpri = prio; 1553 else if (tdq->tdq_lowpri == oldpri) 1554 tdq_setlowpri(tdq, td); 1555 } 1556} 1557 1558/* 1559 * Update a thread's priority when it is lent another thread's 1560 * priority. 1561 */ 1562void 1563sched_lend_prio(struct thread *td, u_char prio) 1564{ 1565 1566 td->td_flags |= TDF_BORROWING; 1567 sched_thread_priority(td, prio); 1568} 1569 1570/* 1571 * Restore a thread's priority when priority propagation is 1572 * over. The prio argument is the minimum priority the thread 1573 * needs to have to satisfy other possible priority lending 1574 * requests. If the thread's regular priority is less 1575 * important than prio, the thread will keep a priority boost 1576 * of prio. 1577 */ 1578void 1579sched_unlend_prio(struct thread *td, u_char prio) 1580{ 1581 u_char base_pri; 1582 1583 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 1584 td->td_base_pri <= PRI_MAX_TIMESHARE) 1585 base_pri = td->td_user_pri; 1586 else 1587 base_pri = td->td_base_pri; 1588 if (prio >= base_pri) { 1589 td->td_flags &= ~TDF_BORROWING; 1590 sched_thread_priority(td, base_pri); 1591 } else 1592 sched_lend_prio(td, prio); 1593} 1594 1595/* 1596 * Standard entry for setting the priority to an absolute value. 1597 */ 1598void 1599sched_prio(struct thread *td, u_char prio) 1600{ 1601 u_char oldprio; 1602 1603 /* First, update the base priority. */ 1604 td->td_base_pri = prio; 1605 1606 /* 1607 * If the thread is borrowing another thread's priority, don't 1608 * ever lower the priority. 1609 */ 1610 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 1611 return; 1612 1613 /* Change the real priority. */ 1614 oldprio = td->td_priority; 1615 sched_thread_priority(td, prio); 1616 1617 /* 1618 * If the thread is on a turnstile, then let the turnstile update 1619 * its state. 1620 */ 1621 if (TD_ON_LOCK(td) && oldprio != prio) 1622 turnstile_adjust(td, oldprio); 1623} 1624 1625/* 1626 * Set the base user priority, does not effect current running priority. 1627 */ 1628void 1629sched_user_prio(struct thread *td, u_char prio) 1630{ 1631 u_char oldprio; 1632 1633 td->td_base_user_pri = prio; 1634 if (td->td_flags & TDF_UBORROWING && td->td_user_pri <= prio) 1635 return; 1636 oldprio = td->td_user_pri; 1637 td->td_user_pri = prio; 1638} 1639 1640void 1641sched_lend_user_prio(struct thread *td, u_char prio) 1642{ 1643 u_char oldprio; 1644 1645 THREAD_LOCK_ASSERT(td, MA_OWNED); 1646 td->td_flags |= TDF_UBORROWING; 1647 oldprio = td->td_user_pri; 1648 td->td_user_pri = prio; 1649} 1650 1651void 1652sched_unlend_user_prio(struct thread *td, u_char prio) 1653{ 1654 u_char base_pri; 1655 1656 THREAD_LOCK_ASSERT(td, MA_OWNED); 1657 base_pri = td->td_base_user_pri; 1658 if (prio >= base_pri) { 1659 td->td_flags &= ~TDF_UBORROWING; 1660 sched_user_prio(td, base_pri); 1661 } else { 1662 sched_lend_user_prio(td, prio); 1663 } 1664} 1665 1666/* 1667 * Add the thread passed as 'newtd' to the run queue before selecting 1668 * the next thread to run. This is only used for KSE. 1669 */ 1670static void 1671sched_switchin(struct tdq *tdq, struct thread *td) 1672{ 1673#ifdef SMP 1674 spinlock_enter(); 1675 TDQ_UNLOCK(tdq); 1676 thread_lock(td); 1677 spinlock_exit(); 1678 sched_setcpu(td->td_sched, TDQ_ID(tdq), SRQ_YIELDING); 1679#else 1680 td->td_lock = TDQ_LOCKPTR(tdq); 1681#endif 1682 tdq_add(tdq, td, SRQ_YIELDING); 1683 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1684} 1685 1686/* 1687 * Block a thread for switching. Similar to thread_block() but does not 1688 * bump the spin count. 1689 */ 1690static inline struct mtx * 1691thread_block_switch(struct thread *td) 1692{ 1693 struct mtx *lock; 1694 1695 THREAD_LOCK_ASSERT(td, MA_OWNED); 1696 lock = td->td_lock; 1697 td->td_lock = &blocked_lock; 1698 mtx_unlock_spin(lock); 1699 1700 return (lock); 1701} 1702 1703/* 1704 * Handle migration from sched_switch(). This happens only for 1705 * cpu binding. 1706 */ 1707static struct mtx * 1708sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags) 1709{ 1710 struct tdq *tdn; 1711 1712 tdn = TDQ_CPU(td->td_sched->ts_cpu); 1713#ifdef SMP 1714 tdq_load_rem(tdq, td->td_sched); 1715 /* 1716 * Do the lock dance required to avoid LOR. We grab an extra 1717 * spinlock nesting to prevent preemption while we're 1718 * not holding either run-queue lock. 1719 */ 1720 spinlock_enter(); 1721 thread_block_switch(td); /* This releases the lock on tdq. */ 1722 TDQ_LOCK(tdn); 1723 tdq_add(tdn, td, flags); 1724 tdq_notify(tdn, td->td_sched); 1725 /* 1726 * After we unlock tdn the new cpu still can't switch into this 1727 * thread until we've unblocked it in cpu_switch(). The lock 1728 * pointers may match in the case of HTT cores. Don't unlock here 1729 * or we can deadlock when the other CPU runs the IPI handler. 1730 */ 1731 if (TDQ_LOCKPTR(tdn) != TDQ_LOCKPTR(tdq)) { 1732 TDQ_UNLOCK(tdn); 1733 TDQ_LOCK(tdq); 1734 } 1735 spinlock_exit(); 1736#endif 1737 return (TDQ_LOCKPTR(tdn)); 1738} 1739 1740/* 1741 * Release a thread that was blocked with thread_block_switch(). 1742 */ 1743static inline void 1744thread_unblock_switch(struct thread *td, struct mtx *mtx) 1745{ 1746 atomic_store_rel_ptr((volatile uintptr_t *)&td->td_lock, 1747 (uintptr_t)mtx); 1748} 1749 1750/* 1751 * Switch threads. This function has to handle threads coming in while 1752 * blocked for some reason, running, or idle. It also must deal with 1753 * migrating a thread from one queue to another as running threads may 1754 * be assigned elsewhere via binding. 1755 */ 1756void 1757sched_switch(struct thread *td, struct thread *newtd, int flags) 1758{ 1759 struct tdq *tdq; 1760 struct td_sched *ts; 1761 struct mtx *mtx; 1762 int srqflag; 1763 int cpuid; 1764 1765 THREAD_LOCK_ASSERT(td, MA_OWNED); 1766 1767 cpuid = PCPU_GET(cpuid); 1768 tdq = TDQ_CPU(cpuid); 1769 ts = td->td_sched; 1770 mtx = td->td_lock; 1771 ts->ts_rltick = ticks; 1772 td->td_lastcpu = td->td_oncpu; 1773 td->td_oncpu = NOCPU; 1774 td->td_flags &= ~TDF_NEEDRESCHED; 1775 td->td_owepreempt = 0; 1776 /* 1777 * The lock pointer in an idle thread should never change. Reset it 1778 * to CAN_RUN as well. 1779 */ 1780 if (TD_IS_IDLETHREAD(td)) { 1781 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1782 TD_SET_CAN_RUN(td); 1783 } else if (TD_IS_RUNNING(td)) { 1784 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1785 srqflag = (flags & SW_PREEMPT) ? 1786 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 1787 SRQ_OURSELF|SRQ_YIELDING; 1788 if (ts->ts_cpu == cpuid) 1789 tdq_runq_add(tdq, ts, srqflag); 1790 else 1791 mtx = sched_switch_migrate(tdq, td, srqflag); 1792 } else { 1793 /* This thread must be going to sleep. */ 1794 TDQ_LOCK(tdq); 1795 mtx = thread_block_switch(td); 1796 tdq_load_rem(tdq, ts); 1797 } 1798 /* 1799 * We enter here with the thread blocked and assigned to the 1800 * appropriate cpu run-queue or sleep-queue and with the current 1801 * thread-queue locked. 1802 */ 1803 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 1804 /* 1805 * If KSE assigned a new thread just add it here and let choosethread 1806 * select the best one. 1807 */ 1808 if (newtd != NULL) 1809 sched_switchin(tdq, newtd); 1810 newtd = choosethread(); 1811 /* 1812 * Call the MD code to switch contexts if necessary. 1813 */ 1814 if (td != newtd) { 1815#ifdef HWPMC_HOOKS 1816 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1817 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 1818#endif 1819 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 1820 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 1821 cpu_switch(td, newtd, mtx); 1822 /* 1823 * We may return from cpu_switch on a different cpu. However, 1824 * we always return with td_lock pointing to the current cpu's 1825 * run queue lock. 1826 */ 1827 cpuid = PCPU_GET(cpuid); 1828 tdq = TDQ_CPU(cpuid); 1829 lock_profile_obtain_lock_success( 1830 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 1831#ifdef HWPMC_HOOKS 1832 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1833 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 1834#endif 1835 } else 1836 thread_unblock_switch(td, mtx); 1837 /* 1838 * We should always get here with the lowest priority td possible. 1839 */ 1840 tdq->tdq_lowpri = td->td_priority; 1841 /* 1842 * Assert that all went well and return. 1843 */ 1844 TDQ_LOCK_ASSERT(tdq, MA_OWNED|MA_NOTRECURSED); 1845 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1846 td->td_oncpu = cpuid; 1847} 1848 1849/* 1850 * Adjust thread priorities as a result of a nice request. 1851 */ 1852void 1853sched_nice(struct proc *p, int nice) 1854{ 1855 struct thread *td; 1856 1857 PROC_LOCK_ASSERT(p, MA_OWNED); 1858 PROC_SLOCK_ASSERT(p, MA_OWNED); 1859 1860 p->p_nice = nice; 1861 FOREACH_THREAD_IN_PROC(p, td) { 1862 thread_lock(td); 1863 sched_priority(td); 1864 sched_prio(td, td->td_base_user_pri); 1865 thread_unlock(td); 1866 } 1867} 1868 1869/* 1870 * Record the sleep time for the interactivity scorer. 1871 */ 1872void 1873sched_sleep(struct thread *td) 1874{ 1875 1876 THREAD_LOCK_ASSERT(td, MA_OWNED); 1877 1878 td->td_slptick = ticks; 1879} 1880 1881/* 1882 * Schedule a thread to resume execution and record how long it voluntarily 1883 * slept. We also update the pctcpu, interactivity, and priority. 1884 */ 1885void 1886sched_wakeup(struct thread *td) 1887{ 1888 struct td_sched *ts; 1889 int slptick; 1890 1891 THREAD_LOCK_ASSERT(td, MA_OWNED); 1892 ts = td->td_sched; 1893 /* 1894 * If we slept for more than a tick update our interactivity and 1895 * priority. 1896 */ 1897 slptick = td->td_slptick; 1898 td->td_slptick = 0; 1899 if (slptick && slptick != ticks) { 1900 u_int hzticks; 1901 1902 hzticks = (ticks - slptick) << SCHED_TICK_SHIFT; 1903 ts->ts_slptime += hzticks; 1904 sched_interact_update(td); 1905 sched_pctcpu_update(ts); 1906 } 1907 /* Reset the slice value after we sleep. */ 1908 ts->ts_slice = sched_slice; 1909 sched_add(td, SRQ_BORING); 1910} 1911 1912/* 1913 * Penalize the parent for creating a new child and initialize the child's 1914 * priority. 1915 */ 1916void 1917sched_fork(struct thread *td, struct thread *child) 1918{ 1919 THREAD_LOCK_ASSERT(td, MA_OWNED); 1920 sched_fork_thread(td, child); 1921 /* 1922 * Penalize the parent and child for forking. 1923 */ 1924 sched_interact_fork(child); 1925 sched_priority(child); 1926 td->td_sched->ts_runtime += tickincr; 1927 sched_interact_update(td); 1928 sched_priority(td); 1929} 1930 1931/* 1932 * Fork a new thread, may be within the same process. 1933 */ 1934void 1935sched_fork_thread(struct thread *td, struct thread *child) 1936{ 1937 struct td_sched *ts; 1938 struct td_sched *ts2; 1939 1940 /* 1941 * Initialize child. 1942 */ 1943 THREAD_LOCK_ASSERT(td, MA_OWNED); 1944 sched_newthread(child); 1945 child->td_lock = TDQ_LOCKPTR(TDQ_SELF()); 1946 child->td_cpuset = cpuset_ref(td->td_cpuset); 1947 ts = td->td_sched; 1948 ts2 = child->td_sched; 1949 ts2->ts_cpu = ts->ts_cpu; 1950 ts2->ts_runq = NULL; 1951 /* 1952 * Grab our parents cpu estimation information and priority. 1953 */ 1954 ts2->ts_ticks = ts->ts_ticks; 1955 ts2->ts_ltick = ts->ts_ltick; 1956 ts2->ts_ftick = ts->ts_ftick; 1957 child->td_user_pri = td->td_user_pri; 1958 child->td_base_user_pri = td->td_base_user_pri; 1959 /* 1960 * And update interactivity score. 1961 */ 1962 ts2->ts_slptime = ts->ts_slptime; 1963 ts2->ts_runtime = ts->ts_runtime; 1964 ts2->ts_slice = 1; /* Attempt to quickly learn interactivity. */ 1965} 1966 1967/* 1968 * Adjust the priority class of a thread. 1969 */ 1970void 1971sched_class(struct thread *td, int class) 1972{ 1973 1974 THREAD_LOCK_ASSERT(td, MA_OWNED); 1975 if (td->td_pri_class == class) 1976 return; 1977 /* 1978 * On SMP if we're on the RUNQ we must adjust the transferable 1979 * count because could be changing to or from an interrupt 1980 * class. 1981 */ 1982 if (TD_ON_RUNQ(td)) { 1983 struct tdq *tdq; 1984 1985 tdq = TDQ_CPU(td->td_sched->ts_cpu); 1986 if (THREAD_CAN_MIGRATE(td)) 1987 tdq->tdq_transferable--; 1988 td->td_pri_class = class; 1989 if (THREAD_CAN_MIGRATE(td)) 1990 tdq->tdq_transferable++; 1991 } 1992 td->td_pri_class = class; 1993} 1994 1995/* 1996 * Return some of the child's priority and interactivity to the parent. 1997 */ 1998void 1999sched_exit(struct proc *p, struct thread *child) 2000{ 2001 struct thread *td; 2002 2003 CTR3(KTR_SCHED, "sched_exit: %p(%s) prio %d", 2004 child, child->td_name, child->td_priority); 2005 2006 PROC_SLOCK_ASSERT(p, MA_OWNED); 2007 td = FIRST_THREAD_IN_PROC(p); 2008 sched_exit_thread(td, child); 2009} 2010 2011/* 2012 * Penalize another thread for the time spent on this one. This helps to 2013 * worsen the priority and interactivity of processes which schedule batch 2014 * jobs such as make. This has little effect on the make process itself but 2015 * causes new processes spawned by it to receive worse scores immediately. 2016 */ 2017void 2018sched_exit_thread(struct thread *td, struct thread *child) 2019{ 2020 2021 CTR3(KTR_SCHED, "sched_exit_thread: %p(%s) prio %d", 2022 child, child->td_name, child->td_priority); 2023 2024#ifdef KSE 2025 /* 2026 * KSE forks and exits so often that this penalty causes short-lived 2027 * threads to always be non-interactive. This causes mozilla to 2028 * crawl under load. 2029 */ 2030 if ((td->td_pflags & TDP_SA) && td->td_proc == child->td_proc) 2031 return; 2032#endif 2033 /* 2034 * Give the child's runtime to the parent without returning the 2035 * sleep time as a penalty to the parent. This causes shells that 2036 * launch expensive things to mark their children as expensive. 2037 */ 2038 thread_lock(td); 2039 td->td_sched->ts_runtime += child->td_sched->ts_runtime; 2040 sched_interact_update(td); 2041 sched_priority(td); 2042 thread_unlock(td); 2043} 2044 2045void 2046sched_preempt(struct thread *td) 2047{ 2048 struct tdq *tdq; 2049 2050 thread_lock(td); 2051 tdq = TDQ_SELF(); 2052 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2053 tdq->tdq_ipipending = 0; 2054 if (td->td_priority > tdq->tdq_lowpri) { 2055 if (td->td_critnest > 1) 2056 td->td_owepreempt = 1; 2057 else 2058 mi_switch(SW_INVOL | SW_PREEMPT, NULL); 2059 } 2060 thread_unlock(td); 2061} 2062 2063/* 2064 * Fix priorities on return to user-space. Priorities may be elevated due 2065 * to static priorities in msleep() or similar. 2066 */ 2067void 2068sched_userret(struct thread *td) 2069{ 2070 /* 2071 * XXX we cheat slightly on the locking here to avoid locking in 2072 * the usual case. Setting td_priority here is essentially an 2073 * incomplete workaround for not setting it properly elsewhere. 2074 * Now that some interrupt handlers are threads, not setting it 2075 * properly elsewhere can clobber it in the window between setting 2076 * it here and returning to user mode, so don't waste time setting 2077 * it perfectly here. 2078 */ 2079 KASSERT((td->td_flags & TDF_BORROWING) == 0, 2080 ("thread with borrowed priority returning to userland")); 2081 if (td->td_priority != td->td_user_pri) { 2082 thread_lock(td); 2083 td->td_priority = td->td_user_pri; 2084 td->td_base_pri = td->td_user_pri; 2085 tdq_setlowpri(TDQ_SELF(), td); 2086 thread_unlock(td); 2087 } 2088} 2089 2090/* 2091 * Handle a stathz tick. This is really only relevant for timeshare 2092 * threads. 2093 */ 2094void 2095sched_clock(struct thread *td) 2096{ 2097 struct tdq *tdq; 2098 struct td_sched *ts; 2099 2100 THREAD_LOCK_ASSERT(td, MA_OWNED); 2101 tdq = TDQ_SELF(); 2102#ifdef SMP 2103 /* 2104 * We run the long term load balancer infrequently on the first cpu. 2105 */ 2106 if (balance_tdq == tdq) { 2107 if (balance_ticks && --balance_ticks == 0) 2108 sched_balance(); 2109 } 2110#endif 2111 /* 2112 * Advance the insert index once for each tick to ensure that all 2113 * threads get a chance to run. 2114 */ 2115 if (tdq->tdq_idx == tdq->tdq_ridx) { 2116 tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS; 2117 if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx])) 2118 tdq->tdq_ridx = tdq->tdq_idx; 2119 } 2120 ts = td->td_sched; 2121 if (td->td_pri_class & PRI_FIFO_BIT) 2122 return; 2123 if (td->td_pri_class == PRI_TIMESHARE) { 2124 /* 2125 * We used a tick; charge it to the thread so 2126 * that we can compute our interactivity. 2127 */ 2128 td->td_sched->ts_runtime += tickincr; 2129 sched_interact_update(td); 2130 sched_priority(td); 2131 } 2132 /* 2133 * We used up one time slice. 2134 */ 2135 if (--ts->ts_slice > 0) 2136 return; 2137 /* 2138 * We're out of time, force a requeue at userret(). 2139 */ 2140 ts->ts_slice = sched_slice; 2141 td->td_flags |= TDF_NEEDRESCHED; 2142} 2143 2144/* 2145 * Called once per hz tick. Used for cpu utilization information. This 2146 * is easier than trying to scale based on stathz. 2147 */ 2148void 2149sched_tick(void) 2150{ 2151 struct td_sched *ts; 2152 2153 ts = curthread->td_sched; 2154 /* Adjust ticks for pctcpu */ 2155 ts->ts_ticks += 1 << SCHED_TICK_SHIFT; 2156 ts->ts_ltick = ticks; 2157 /* 2158 * Update if we've exceeded our desired tick threshhold by over one 2159 * second. 2160 */ 2161 if (ts->ts_ftick + SCHED_TICK_MAX < ts->ts_ltick) 2162 sched_pctcpu_update(ts); 2163} 2164 2165/* 2166 * Return whether the current CPU has runnable tasks. Used for in-kernel 2167 * cooperative idle threads. 2168 */ 2169int 2170sched_runnable(void) 2171{ 2172 struct tdq *tdq; 2173 int load; 2174 2175 load = 1; 2176 2177 tdq = TDQ_SELF(); 2178 if ((curthread->td_flags & TDF_IDLETD) != 0) { 2179 if (tdq->tdq_load > 0) 2180 goto out; 2181 } else 2182 if (tdq->tdq_load - 1 > 0) 2183 goto out; 2184 load = 0; 2185out: 2186 return (load); 2187} 2188 2189/* 2190 * Choose the highest priority thread to run. The thread is removed from 2191 * the run-queue while running however the load remains. For SMP we set 2192 * the tdq in the global idle bitmask if it idles here. 2193 */ 2194struct thread * 2195sched_choose(void) 2196{ 2197 struct td_sched *ts; 2198 struct tdq *tdq; 2199 2200 tdq = TDQ_SELF(); 2201 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2202 ts = tdq_choose(tdq); 2203 if (ts) { 2204 tdq_runq_rem(tdq, ts); 2205 return (ts->ts_thread); 2206 } 2207 return (PCPU_GET(idlethread)); 2208} 2209 2210/* 2211 * Set owepreempt if necessary. Preemption never happens directly in ULE, 2212 * we always request it once we exit a critical section. 2213 */ 2214static inline void 2215sched_setpreempt(struct thread *td) 2216{ 2217 struct thread *ctd; 2218 int cpri; 2219 int pri; 2220 2221 THREAD_LOCK_ASSERT(curthread, MA_OWNED); 2222 2223 ctd = curthread; 2224 pri = td->td_priority; 2225 cpri = ctd->td_priority; 2226 if (pri < cpri) 2227 ctd->td_flags |= TDF_NEEDRESCHED; 2228 if (panicstr != NULL || pri >= cpri || cold || TD_IS_INHIBITED(ctd)) 2229 return; 2230 if (!sched_shouldpreempt(pri, cpri, 0)) 2231 return; 2232 ctd->td_owepreempt = 1; 2233} 2234 2235/* 2236 * Add a thread to a thread queue. Select the appropriate runq and add the 2237 * thread to it. This is the internal function called when the tdq is 2238 * predetermined. 2239 */ 2240void 2241tdq_add(struct tdq *tdq, struct thread *td, int flags) 2242{ 2243 struct td_sched *ts; 2244 2245 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2246 KASSERT((td->td_inhibitors == 0), 2247 ("sched_add: trying to run inhibited thread")); 2248 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 2249 ("sched_add: bad thread state")); 2250 KASSERT(td->td_flags & TDF_INMEM, 2251 ("sched_add: thread swapped out")); 2252 2253 ts = td->td_sched; 2254 if (td->td_priority < tdq->tdq_lowpri) 2255 tdq->tdq_lowpri = td->td_priority; 2256 tdq_runq_pick(tdq, ts); 2257 tdq_runq_add(tdq, ts, flags); 2258 tdq_load_add(tdq, ts); 2259} 2260 2261/* 2262 * Select the target thread queue and add a thread to it. Request 2263 * preemption or IPI a remote processor if required. 2264 */ 2265void 2266sched_add(struct thread *td, int flags) 2267{ 2268 struct tdq *tdq; 2269#ifdef SMP 2270 struct td_sched *ts; 2271 int cpu; 2272#endif 2273 CTR5(KTR_SCHED, "sched_add: %p(%s) prio %d by %p(%s)", 2274 td, td->td_name, td->td_priority, curthread, 2275 curthread->td_name); 2276 THREAD_LOCK_ASSERT(td, MA_OWNED); 2277 /* 2278 * Recalculate the priority before we select the target cpu or 2279 * run-queue. 2280 */ 2281 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 2282 sched_priority(td); 2283#ifdef SMP 2284 /* 2285 * Pick the destination cpu and if it isn't ours transfer to the 2286 * target cpu. 2287 */ 2288 ts = td->td_sched; 2289 cpu = sched_pickcpu(ts, flags); 2290 tdq = sched_setcpu(ts, cpu, flags); 2291 tdq_add(tdq, td, flags); 2292 if (cpu != PCPU_GET(cpuid)) { 2293 tdq_notify(tdq, ts); 2294 return; 2295 } 2296#else 2297 tdq = TDQ_SELF(); 2298 TDQ_LOCK(tdq); 2299 /* 2300 * Now that the thread is moving to the run-queue, set the lock 2301 * to the scheduler's lock. 2302 */ 2303 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 2304 tdq_add(tdq, td, flags); 2305#endif 2306 if (!(flags & SRQ_YIELDING)) 2307 sched_setpreempt(td); 2308} 2309 2310/* 2311 * Remove a thread from a run-queue without running it. This is used 2312 * when we're stealing a thread from a remote queue. Otherwise all threads 2313 * exit by calling sched_exit_thread() and sched_throw() themselves. 2314 */ 2315void 2316sched_rem(struct thread *td) 2317{ 2318 struct tdq *tdq; 2319 struct td_sched *ts; 2320 2321 CTR5(KTR_SCHED, "sched_rem: %p(%s) prio %d by %p(%s)", 2322 td, td->td_name, td->td_priority, curthread, 2323 curthread->td_name); 2324 ts = td->td_sched; 2325 tdq = TDQ_CPU(ts->ts_cpu); 2326 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2327 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2328 KASSERT(TD_ON_RUNQ(td), 2329 ("sched_rem: thread not on run queue")); 2330 tdq_runq_rem(tdq, ts); 2331 tdq_load_rem(tdq, ts); 2332 TD_SET_CAN_RUN(td); 2333 if (td->td_priority == tdq->tdq_lowpri) 2334 tdq_setlowpri(tdq, NULL); 2335} 2336 2337/* 2338 * Fetch cpu utilization information. Updates on demand. 2339 */ 2340fixpt_t 2341sched_pctcpu(struct thread *td) 2342{ 2343 fixpt_t pctcpu; 2344 struct td_sched *ts; 2345 2346 pctcpu = 0; 2347 ts = td->td_sched; 2348 if (ts == NULL) 2349 return (0); 2350 2351 thread_lock(td); 2352 if (ts->ts_ticks) { 2353 int rtick; 2354 2355 sched_pctcpu_update(ts); 2356 /* How many rtick per second ? */ 2357 rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz); 2358 pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT; 2359 } 2360 thread_unlock(td); 2361 2362 return (pctcpu); 2363} 2364 2365/* 2366 * Enforce affinity settings for a thread. Called after adjustments to 2367 * cpumask. 2368 */ 2369void 2370sched_affinity(struct thread *td) 2371{ 2372#ifdef SMP 2373 struct td_sched *ts; 2374 int cpu; 2375 2376 THREAD_LOCK_ASSERT(td, MA_OWNED); 2377 ts = td->td_sched; 2378 if (THREAD_CAN_SCHED(td, ts->ts_cpu)) 2379 return; 2380 if (!TD_IS_RUNNING(td)) 2381 return; 2382 td->td_flags |= TDF_NEEDRESCHED; 2383 if (!THREAD_CAN_MIGRATE(td)) 2384 return; 2385 /* 2386 * Assign the new cpu and force a switch before returning to 2387 * userspace. If the target thread is not running locally send 2388 * an ipi to force the issue. 2389 */ 2390 cpu = ts->ts_cpu; 2391 ts->ts_cpu = sched_pickcpu(ts, 0); 2392 if (cpu != PCPU_GET(cpuid)) 2393 ipi_selected(1 << cpu, IPI_PREEMPT); 2394#endif 2395} 2396 2397/* 2398 * Bind a thread to a target cpu. 2399 */ 2400void 2401sched_bind(struct thread *td, int cpu) 2402{ 2403 struct td_sched *ts; 2404 2405 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 2406 ts = td->td_sched; 2407 if (ts->ts_flags & TSF_BOUND) 2408 sched_unbind(td); 2409 ts->ts_flags |= TSF_BOUND; 2410 sched_pin(); 2411 if (PCPU_GET(cpuid) == cpu) 2412 return; 2413 ts->ts_cpu = cpu; 2414 /* When we return from mi_switch we'll be on the correct cpu. */ 2415 mi_switch(SW_VOL, NULL); 2416} 2417 2418/* 2419 * Release a bound thread. 2420 */ 2421void 2422sched_unbind(struct thread *td) 2423{ 2424 struct td_sched *ts; 2425 2426 THREAD_LOCK_ASSERT(td, MA_OWNED); 2427 ts = td->td_sched; 2428 if ((ts->ts_flags & TSF_BOUND) == 0) 2429 return; 2430 ts->ts_flags &= ~TSF_BOUND; 2431 sched_unpin(); 2432} 2433 2434int 2435sched_is_bound(struct thread *td) 2436{ 2437 THREAD_LOCK_ASSERT(td, MA_OWNED); 2438 return (td->td_sched->ts_flags & TSF_BOUND); 2439} 2440 2441/* 2442 * Basic yield call. 2443 */ 2444void 2445sched_relinquish(struct thread *td) 2446{ 2447 thread_lock(td); 2448 SCHED_STAT_INC(switch_relinquish); 2449 mi_switch(SW_VOL, NULL); 2450 thread_unlock(td); 2451} 2452 2453/* 2454 * Return the total system load. 2455 */ 2456int 2457sched_load(void) 2458{ 2459#ifdef SMP 2460 int total; 2461 int i; 2462 2463 total = 0; 2464 for (i = 0; i <= mp_maxid; i++) 2465 total += TDQ_CPU(i)->tdq_sysload; 2466 return (total); 2467#else 2468 return (TDQ_SELF()->tdq_sysload); 2469#endif 2470} 2471 2472int 2473sched_sizeof_proc(void) 2474{ 2475 return (sizeof(struct proc)); 2476} 2477 2478int 2479sched_sizeof_thread(void) 2480{ 2481 return (sizeof(struct thread) + sizeof(struct td_sched)); 2482} 2483 2484/* 2485 * The actual idle process. 2486 */ 2487void 2488sched_idletd(void *dummy) 2489{ 2490 struct thread *td; 2491 struct tdq *tdq; 2492 2493 td = curthread; 2494 tdq = TDQ_SELF(); 2495 mtx_assert(&Giant, MA_NOTOWNED); 2496 /* ULE relies on preemption for idle interruption. */ 2497 for (;;) { 2498#ifdef SMP 2499 if (tdq_idled(tdq)) 2500 cpu_idle(); 2501#else 2502 cpu_idle(); 2503#endif 2504 } 2505} 2506 2507/* 2508 * A CPU is entering for the first time or a thread is exiting. 2509 */ 2510void 2511sched_throw(struct thread *td) 2512{ 2513 struct thread *newtd; 2514 struct tdq *tdq; 2515 2516 tdq = TDQ_SELF(); 2517 if (td == NULL) { 2518 /* Correct spinlock nesting and acquire the correct lock. */ 2519 TDQ_LOCK(tdq); 2520 spinlock_exit(); 2521 } else { 2522 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2523 tdq_load_rem(tdq, td->td_sched); 2524 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 2525 } 2526 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 2527 newtd = choosethread(); 2528 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 2529 PCPU_SET(switchtime, cpu_ticks()); 2530 PCPU_SET(switchticks, ticks); 2531 cpu_throw(td, newtd); /* doesn't return */ 2532} 2533 2534/* 2535 * This is called from fork_exit(). Just acquire the correct locks and 2536 * let fork do the rest of the work. 2537 */ 2538void 2539sched_fork_exit(struct thread *td) 2540{ 2541 struct td_sched *ts; 2542 struct tdq *tdq; 2543 int cpuid; 2544 2545 /* 2546 * Finish setting up thread glue so that it begins execution in a 2547 * non-nested critical section with the scheduler lock held. 2548 */ 2549 cpuid = PCPU_GET(cpuid); 2550 tdq = TDQ_CPU(cpuid); 2551 ts = td->td_sched; 2552 if (TD_IS_IDLETHREAD(td)) 2553 td->td_lock = TDQ_LOCKPTR(tdq); 2554 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2555 td->td_oncpu = cpuid; 2556 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 2557 lock_profile_obtain_lock_success( 2558 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 2559 tdq->tdq_lowpri = td->td_priority; 2560} 2561 2562static SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0, 2563 "Scheduler"); 2564SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0, 2565 "Scheduler name"); 2566SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, 2567 "Slice size for timeshare threads"); 2568SYSCTL_INT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0, 2569 "Interactivity score threshold"); 2570SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW, &preempt_thresh, 2571 0,"Min priority for preemption, lower priorities have greater precedence"); 2572#ifdef SMP 2573SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0, 2574 "Number of hz ticks to keep thread affinity for"); 2575SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0, 2576 "Enables the long-term load balancer"); 2577SYSCTL_INT(_kern_sched, OID_AUTO, balance_interval, CTLFLAG_RW, 2578 &balance_interval, 0, 2579 "Average frequency in stathz ticks to run the long-term balancer"); 2580SYSCTL_INT(_kern_sched, OID_AUTO, steal_htt, CTLFLAG_RW, &steal_htt, 0, 2581 "Steals work from another hyper-threaded core on idle"); 2582SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0, 2583 "Attempts to steal work from other cores before idling"); 2584SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0, 2585 "Minimum load on remote cpu before we'll steal"); 2586#endif 2587 2588/* ps compat. All cpu percentages from ULE are weighted. */ 2589static int ccpu = 0; 2590SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 2591 2592 2593#define KERN_SWITCH_INCLUDE 1 2594#include "kern/kern_switch.c" 2595