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("$FreeBSD$"); 40 41 #include "opt_hwpmc_hooks.h" 42 #include "opt_kdtrace.h" 43 #include "opt_sched.h" 44 45 #include <sys/param.h> 46 #include <sys/systm.h> 47 #include <sys/kdb.h> 48 #include <sys/kernel.h> 49 #include <sys/ktr.h> 50 #include <sys/lock.h> 51 #include <sys/mutex.h> 52 #include <sys/proc.h> 53 #include <sys/resource.h> 54 #include <sys/resourcevar.h> 55 #include <sys/sched.h> 56 #include <sys/smp.h> 57 #include <sys/sx.h> 58 #include <sys/sysctl.h> 59 #include <sys/sysproto.h> 60 #include <sys/turnstile.h> 61 #include <sys/umtx.h> 62 #include <sys/vmmeter.h> 63 #include <sys/cpuset.h> 64 #ifdef KTRACE 65 #include <sys/uio.h> 66 #include <sys/ktrace.h> 67 #endif 68 69 #ifdef HWPMC_HOOKS 70 #include <sys/pmckern.h> 71 #endif 72 73 #ifdef KDTRACE_HOOKS 74 #include <sys/dtrace_bsd.h> 75 int dtrace_vtime_active; 76 dtrace_vtime_switch_func_t dtrace_vtime_switch_func; 77 #endif 78 79 #include <machine/cpu.h> 80 #include <machine/smp.h> 81 82 #if defined(__sparc64__) || defined(__mips__) 83 #error "This architecture is not currently compatible with ULE" 84 #endif 85 86 #define KTR_ULE 0 87 88 /* 89 * Thread scheduler specific section. All fields are protected 90 * by the thread lock. 91 */ 92 struct td_sched { 93 struct runq *ts_runq; /* Run-queue we're queued on. */ 94 short ts_flags; /* TSF_* flags. */ 95 u_char ts_cpu; /* CPU that we have affinity for. */ 96 int ts_rltick; /* Real last tick, for affinity. */ 97 int ts_slice; /* Ticks of slice remaining. */ 98 u_int ts_slptime; /* Number of ticks we vol. slept */ 99 u_int ts_runtime; /* Number of ticks we were running */ 100 int ts_ltick; /* Last tick that we were running on */ 101 int ts_ftick; /* First tick that we were running on */ 102 int ts_ticks; /* Tick count */ 103 }; 104 /* flags kept in ts_flags */ 105 #define TSF_BOUND 0x0001 /* Thread can not migrate. */ 106 #define TSF_XFERABLE 0x0002 /* Thread was added as transferable. */ 107 108 static struct td_sched td_sched0; 109 110 #define THREAD_CAN_MIGRATE(td) ((td)->td_pinned == 0) 111 #define THREAD_CAN_SCHED(td, cpu) \ 112 CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask) 113 114 /* 115 * Cpu percentage computation macros and defines. 116 * 117 * SCHED_TICK_SECS: Number of seconds to average the cpu usage across. 118 * SCHED_TICK_TARG: Number of hz ticks to average the cpu usage across. 119 * SCHED_TICK_MAX: Maximum number of ticks before scaling back. 120 * SCHED_TICK_SHIFT: Shift factor to avoid rounding away results. 121 * SCHED_TICK_HZ: Compute the number of hz ticks for a given ticks count. 122 * SCHED_TICK_TOTAL: Gives the amount of time we've been recording ticks. 123 */ 124 #define SCHED_TICK_SECS 10 125 #define SCHED_TICK_TARG (hz * SCHED_TICK_SECS) 126 #define SCHED_TICK_MAX (SCHED_TICK_TARG + hz) 127 #define SCHED_TICK_SHIFT 10 128 #define SCHED_TICK_HZ(ts) ((ts)->ts_ticks >> SCHED_TICK_SHIFT) 129 #define SCHED_TICK_TOTAL(ts) (max((ts)->ts_ltick - (ts)->ts_ftick, hz)) 130 131 /* 132 * These macros determine priorities for non-interactive threads. They are 133 * assigned a priority based on their recent cpu utilization as expressed 134 * by the ratio of ticks to the tick total. NHALF priorities at the start 135 * and end of the MIN to MAX timeshare range are only reachable with negative 136 * or positive nice respectively. 137 * 138 * PRI_RANGE: Priority range for utilization dependent priorities. 139 * PRI_NRESV: Number of nice values. 140 * PRI_TICKS: Compute a priority in PRI_RANGE from the ticks count and total. 141 * PRI_NICE: Determines the part of the priority inherited from nice. 142 */ 143 #define SCHED_PRI_NRESV (PRIO_MAX - PRIO_MIN) 144 #define SCHED_PRI_NHALF (SCHED_PRI_NRESV / 2) 145 #define SCHED_PRI_MIN (PRI_MIN_TIMESHARE + SCHED_PRI_NHALF) 146 #define SCHED_PRI_MAX (PRI_MAX_TIMESHARE - SCHED_PRI_NHALF) 147 #define SCHED_PRI_RANGE (SCHED_PRI_MAX - SCHED_PRI_MIN) 148 #define SCHED_PRI_TICKS(ts) \ 149 (SCHED_TICK_HZ((ts)) / \ 150 (roundup(SCHED_TICK_TOTAL((ts)), SCHED_PRI_RANGE) / SCHED_PRI_RANGE)) 151 #define SCHED_PRI_NICE(nice) (nice) 152 153 /* 154 * These determine the interactivity of a process. Interactivity differs from 155 * cpu utilization in that it expresses the voluntary time slept vs time ran 156 * while cpu utilization includes all time not running. This more accurately 157 * models the intent of the thread. 158 * 159 * SLP_RUN_MAX: Maximum amount of sleep time + run time we'll accumulate 160 * before throttling back. 161 * SLP_RUN_FORK: Maximum slp+run time to inherit at fork time. 162 * INTERACT_MAX: Maximum interactivity value. Smaller is better. 163 * INTERACT_THRESH: Threshhold for placement on the current runq. 164 */ 165 #define SCHED_SLP_RUN_MAX ((hz * 5) << SCHED_TICK_SHIFT) 166 #define SCHED_SLP_RUN_FORK ((hz / 2) << SCHED_TICK_SHIFT) 167 #define SCHED_INTERACT_MAX (100) 168 #define SCHED_INTERACT_HALF (SCHED_INTERACT_MAX / 2) 169 #define SCHED_INTERACT_THRESH (30) 170 171 /* 172 * tickincr: Converts a stathz tick into a hz domain scaled by 173 * the shift factor. Without the shift the error rate 174 * due to rounding would be unacceptably high. 175 * realstathz: stathz is sometimes 0 and run off of hz. 176 * sched_slice: Runtime of each thread before rescheduling. 177 * preempt_thresh: Priority threshold for preemption and remote IPIs. 178 */ 179 static int sched_interact = SCHED_INTERACT_THRESH; 180 static int realstathz; 181 static int tickincr; 182 static int sched_slice = 1; 183 #ifdef PREEMPTION 184 #ifdef FULL_PREEMPTION 185 static int preempt_thresh = PRI_MAX_IDLE; 186 #else 187 static int preempt_thresh = PRI_MIN_KERN; 188 #endif 189 #else 190 static int preempt_thresh = 0; 191 #endif 192 static int static_boost = PRI_MIN_TIMESHARE; 193 static int sched_idlespins = 10000; 194 static int sched_idlespinthresh = 4; 195 196 /* 197 * tdq - per processor runqs and statistics. All fields are protected by the 198 * tdq_lock. The load and lowpri may be accessed without to avoid excess 199 * locking in sched_pickcpu(); 200 */ 201 struct tdq { 202 /* Ordered to improve efficiency of cpu_search() and switch(). */ 203 struct mtx tdq_lock; /* run queue lock. */ 204 struct cpu_group *tdq_cg; /* Pointer to cpu topology. */ 205 volatile int tdq_load; /* Aggregate load. */ 206 int tdq_sysload; /* For loadavg, !ITHD load. */ 207 int tdq_transferable; /* Transferable thread count. */ 208 volatile int tdq_idlestate; /* State of the idle thread. */ 209 short tdq_switchcnt; /* Switches this tick. */ 210 short tdq_oldswitchcnt; /* Switches last tick. */ 211 u_char tdq_lowpri; /* Lowest priority thread. */ 212 u_char tdq_ipipending; /* IPI pending. */ 213 u_char tdq_idx; /* Current insert index. */ 214 u_char tdq_ridx; /* Current removal index. */ 215 struct runq tdq_realtime; /* real-time run queue. */ 216 struct runq tdq_timeshare; /* timeshare run queue. */ 217 struct runq tdq_idle; /* Queue of IDLE threads. */ 218 char tdq_name[sizeof("sched lock") + 6]; 219 } __aligned(64); 220 221 /* Idle thread states and config. */ 222 #define TDQ_RUNNING 1 223 #define TDQ_IDLE 2 224 225 #ifdef SMP 226 struct cpu_group *cpu_top; 227 228 #define SCHED_AFFINITY_DEFAULT (max(1, hz / 1000)) 229 #define SCHED_AFFINITY(ts, t) ((ts)->ts_rltick > ticks - ((t) * affinity)) 230 231 /* 232 * Run-time tunables. 233 */ 234 static int rebalance = 1; 235 static int balance_interval = 128; /* Default set in sched_initticks(). */ 236 static int affinity; 237 static int steal_htt = 1; 238 static int steal_idle = 1; 239 static int steal_thresh = 2; 240 241 /* 242 * One thread queue per processor. 243 */ 244 static struct tdq tdq_cpu[MAXCPU]; 245 static struct tdq *balance_tdq; 246 static int balance_ticks; 247 248 #define TDQ_SELF() (&tdq_cpu[PCPU_GET(cpuid)]) 249 #define TDQ_CPU(x) (&tdq_cpu[(x)]) 250 #define TDQ_ID(x) ((int)((x) - tdq_cpu)) 251 #else /* !SMP */ 252 static struct tdq tdq_cpu; 253 254 #define TDQ_ID(x) (0) 255 #define TDQ_SELF() (&tdq_cpu) 256 #define TDQ_CPU(x) (&tdq_cpu) 257 #endif 258 259 #define TDQ_LOCK_ASSERT(t, type) mtx_assert(TDQ_LOCKPTR((t)), (type)) 260 #define TDQ_LOCK(t) mtx_lock_spin(TDQ_LOCKPTR((t))) 261 #define TDQ_LOCK_FLAGS(t, f) mtx_lock_spin_flags(TDQ_LOCKPTR((t)), (f)) 262 #define TDQ_UNLOCK(t) mtx_unlock_spin(TDQ_LOCKPTR((t))) 263 #define TDQ_LOCKPTR(t) (&(t)->tdq_lock) 264 265 static void sched_priority(struct thread *); 266 static void sched_thread_priority(struct thread *, u_char); 267 static int sched_interact_score(struct thread *); 268 static void sched_interact_update(struct thread *); 269 static void sched_interact_fork(struct thread *); 270 static void sched_pctcpu_update(struct td_sched *); 271 272 /* Operations on per processor queues */ 273 static struct thread *tdq_choose(struct tdq *); 274 static void tdq_setup(struct tdq *); 275 static void tdq_load_add(struct tdq *, struct thread *); 276 static void tdq_load_rem(struct tdq *, struct thread *); 277 static __inline void tdq_runq_add(struct tdq *, struct thread *, int); 278 static __inline void tdq_runq_rem(struct tdq *, struct thread *); 279 static inline int sched_shouldpreempt(int, int, int); 280 void tdq_print(int cpu); 281 static void runq_print(struct runq *rq); 282 static void tdq_add(struct tdq *, struct thread *, int); 283 #ifdef SMP 284 static int tdq_move(struct tdq *, struct tdq *); 285 static int tdq_idled(struct tdq *); 286 static void tdq_notify(struct tdq *, struct thread *); 287 static struct thread *tdq_steal(struct tdq *, int); 288 static struct thread *runq_steal(struct runq *, int); 289 static int sched_pickcpu(struct thread *, int); 290 static void sched_balance(void); 291 static int sched_balance_pair(struct tdq *, struct tdq *); 292 static inline struct tdq *sched_setcpu(struct thread *, int, int); 293 static inline struct mtx *thread_block_switch(struct thread *); 294 static inline void thread_unblock_switch(struct thread *, struct mtx *); 295 static struct mtx *sched_switch_migrate(struct tdq *, struct thread *, int); 296 #endif 297 298 static void sched_setup(void *dummy); 299 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL); 300 301 static void sched_initticks(void *dummy); 302 SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks, 303 NULL); 304 305 /* 306 * Print the threads waiting on a run-queue. 307 */ 308 static void 309 runq_print(struct runq *rq) 310 { 311 struct rqhead *rqh; 312 struct thread *td; 313 int pri; 314 int j; 315 int i; 316 317 for (i = 0; i < RQB_LEN; i++) { 318 printf("\t\trunq bits %d 0x%zx\n", 319 i, rq->rq_status.rqb_bits[i]); 320 for (j = 0; j < RQB_BPW; j++) 321 if (rq->rq_status.rqb_bits[i] & (1ul << j)) { 322 pri = j + (i << RQB_L2BPW); 323 rqh = &rq->rq_queues[pri]; 324 TAILQ_FOREACH(td, rqh, td_runq) { 325 printf("\t\t\ttd %p(%s) priority %d rqindex %d pri %d\n", 326 td, td->td_name, td->td_priority, 327 td->td_rqindex, pri); 328 } 329 } 330 } 331 } 332 333 /* 334 * Print the status of a per-cpu thread queue. Should be a ddb show cmd. 335 */ 336 void 337 tdq_print(int cpu) 338 { 339 struct tdq *tdq; 340 341 tdq = TDQ_CPU(cpu); 342 343 printf("tdq %d:\n", TDQ_ID(tdq)); 344 printf("\tlock %p\n", TDQ_LOCKPTR(tdq)); 345 printf("\tLock name: %s\n", tdq->tdq_name); 346 printf("\tload: %d\n", tdq->tdq_load); 347 printf("\tswitch cnt: %d\n", tdq->tdq_switchcnt); 348 printf("\told switch cnt: %d\n", tdq->tdq_oldswitchcnt); 349 printf("\tidle state: %d\n", tdq->tdq_idlestate); 350 printf("\ttimeshare idx: %d\n", tdq->tdq_idx); 351 printf("\ttimeshare ridx: %d\n", tdq->tdq_ridx); 352 printf("\tload transferable: %d\n", tdq->tdq_transferable); 353 printf("\tlowest priority: %d\n", tdq->tdq_lowpri); 354 printf("\trealtime runq:\n"); 355 runq_print(&tdq->tdq_realtime); 356 printf("\ttimeshare runq:\n"); 357 runq_print(&tdq->tdq_timeshare); 358 printf("\tidle runq:\n"); 359 runq_print(&tdq->tdq_idle); 360 } 361 362 static inline int 363 sched_shouldpreempt(int pri, int cpri, int remote) 364 { 365 /* 366 * If the new priority is not better than the current priority there is 367 * nothing to do. 368 */ 369 if (pri >= cpri) 370 return (0); 371 /* 372 * Always preempt idle. 373 */ 374 if (cpri >= PRI_MIN_IDLE) 375 return (1); 376 /* 377 * If preemption is disabled don't preempt others. 378 */ 379 if (preempt_thresh == 0) 380 return (0); 381 /* 382 * Preempt if we exceed the threshold. 383 */ 384 if (pri <= preempt_thresh) 385 return (1); 386 /* 387 * If we're realtime or better and there is timeshare or worse running 388 * preempt only remote processors. 389 */ 390 if (remote && pri <= PRI_MAX_REALTIME && cpri > PRI_MAX_REALTIME) 391 return (1); 392 return (0); 393 } 394 395 #define TS_RQ_PPQ (((PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE) + 1) / RQ_NQS) 396 /* 397 * Add a thread to the actual run-queue. Keeps transferable counts up to 398 * date with what is actually on the run-queue. Selects the correct 399 * queue position for timeshare threads. 400 */ 401 static __inline void 402 tdq_runq_add(struct tdq *tdq, struct thread *td, int flags) 403 { 404 struct td_sched *ts; 405 u_char pri; 406 407 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 408 THREAD_LOCK_ASSERT(td, MA_OWNED); 409 410 pri = td->td_priority; 411 ts = td->td_sched; 412 TD_SET_RUNQ(td); 413 if (THREAD_CAN_MIGRATE(td)) { 414 tdq->tdq_transferable++; 415 ts->ts_flags |= TSF_XFERABLE; 416 } 417 if (pri <= PRI_MAX_REALTIME) { 418 ts->ts_runq = &tdq->tdq_realtime; 419 } else if (pri <= PRI_MAX_TIMESHARE) { 420 ts->ts_runq = &tdq->tdq_timeshare; 421 KASSERT(pri <= PRI_MAX_TIMESHARE && pri >= PRI_MIN_TIMESHARE, 422 ("Invalid priority %d on timeshare runq", pri)); 423 /* 424 * This queue contains only priorities between MIN and MAX 425 * realtime. Use the whole queue to represent these values. 426 */ 427 if ((flags & (SRQ_BORROWING|SRQ_PREEMPTED)) == 0) { 428 pri = (pri - PRI_MIN_TIMESHARE) / TS_RQ_PPQ; 429 pri = (pri + tdq->tdq_idx) % RQ_NQS; 430 /* 431 * This effectively shortens the queue by one so we 432 * can have a one slot difference between idx and 433 * ridx while we wait for threads to drain. 434 */ 435 if (tdq->tdq_ridx != tdq->tdq_idx && 436 pri == tdq->tdq_ridx) 437 pri = (unsigned char)(pri - 1) % RQ_NQS; 438 } else 439 pri = tdq->tdq_ridx; 440 runq_add_pri(ts->ts_runq, td, pri, flags); 441 return; 442 } else 443 ts->ts_runq = &tdq->tdq_idle; 444 runq_add(ts->ts_runq, td, flags); 445 } 446 447 /* 448 * Remove a thread from a run-queue. This typically happens when a thread 449 * is selected to run. Running threads are not on the queue and the 450 * transferable count does not reflect them. 451 */ 452 static __inline void 453 tdq_runq_rem(struct tdq *tdq, struct thread *td) 454 { 455 struct td_sched *ts; 456 457 ts = td->td_sched; 458 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 459 KASSERT(ts->ts_runq != NULL, 460 ("tdq_runq_remove: thread %p null ts_runq", td)); 461 if (ts->ts_flags & TSF_XFERABLE) { 462 tdq->tdq_transferable--; 463 ts->ts_flags &= ~TSF_XFERABLE; 464 } 465 if (ts->ts_runq == &tdq->tdq_timeshare) { 466 if (tdq->tdq_idx != tdq->tdq_ridx) 467 runq_remove_idx(ts->ts_runq, td, &tdq->tdq_ridx); 468 else 469 runq_remove_idx(ts->ts_runq, td, NULL); 470 } else 471 runq_remove(ts->ts_runq, td); 472 } 473 474 /* 475 * Load is maintained for all threads RUNNING and ON_RUNQ. Add the load 476 * for this thread to the referenced thread queue. 477 */ 478 static void 479 tdq_load_add(struct tdq *tdq, struct thread *td) 480 { 481 482 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 483 THREAD_LOCK_ASSERT(td, MA_OWNED); 484 485 tdq->tdq_load++; 486 if ((td->td_proc->p_flag & P_NOLOAD) == 0) 487 tdq->tdq_sysload++; 488 CTR2(KTR_SCHED, "cpu %d load: %d", TDQ_ID(tdq), tdq->tdq_load); 489 } 490 491 /* 492 * Remove the load from a thread that is transitioning to a sleep state or 493 * exiting. 494 */ 495 static void 496 tdq_load_rem(struct tdq *tdq, struct thread *td) 497 { 498 499 THREAD_LOCK_ASSERT(td, MA_OWNED); 500 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 501 KASSERT(tdq->tdq_load != 0, 502 ("tdq_load_rem: Removing with 0 load on queue %d", TDQ_ID(tdq))); 503 504 tdq->tdq_load--; 505 if ((td->td_proc->p_flag & P_NOLOAD) == 0) 506 tdq->tdq_sysload--; 507 CTR1(KTR_SCHED, "load: %d", tdq->tdq_load); 508 } 509 510 /* 511 * Set lowpri to its exact value by searching the run-queue and 512 * evaluating curthread. curthread may be passed as an optimization. 513 */ 514 static void 515 tdq_setlowpri(struct tdq *tdq, struct thread *ctd) 516 { 517 struct thread *td; 518 519 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 520 if (ctd == NULL) 521 ctd = pcpu_find(TDQ_ID(tdq))->pc_curthread; 522 td = tdq_choose(tdq); 523 if (td == NULL || td->td_priority > ctd->td_priority) 524 tdq->tdq_lowpri = ctd->td_priority; 525 else 526 tdq->tdq_lowpri = td->td_priority; 527 } 528 529 #ifdef SMP 530 struct cpu_search { 531 cpumask_t cs_mask; /* Mask of valid cpus. */ 532 u_int cs_load; 533 u_int cs_cpu; 534 int cs_limit; /* Min priority for low min load for high. */ 535 }; 536 537 #define CPU_SEARCH_LOWEST 0x1 538 #define CPU_SEARCH_HIGHEST 0x2 539 #define CPU_SEARCH_BOTH (CPU_SEARCH_LOWEST|CPU_SEARCH_HIGHEST) 540 541 #define CPUMASK_FOREACH(cpu, mask) \ 542 for ((cpu) = 0; (cpu) < sizeof((mask)) * 8; (cpu)++) \ 543 if ((mask) & 1 << (cpu)) 544 545 static __inline int cpu_search(struct cpu_group *cg, struct cpu_search *low, 546 struct cpu_search *high, const int match); 547 int cpu_search_lowest(struct cpu_group *cg, struct cpu_search *low); 548 int cpu_search_highest(struct cpu_group *cg, struct cpu_search *high); 549 int cpu_search_both(struct cpu_group *cg, struct cpu_search *low, 550 struct cpu_search *high); 551 552 /* 553 * This routine compares according to the match argument and should be 554 * reduced in actual instantiations via constant propagation and dead code 555 * elimination. 556 */ 557 static __inline int 558 cpu_compare(int cpu, struct cpu_search *low, struct cpu_search *high, 559 const int match) 560 { 561 struct tdq *tdq; 562 563 tdq = TDQ_CPU(cpu); 564 if (match & CPU_SEARCH_LOWEST) 565 if (low->cs_mask & (1 << cpu) && 566 tdq->tdq_load < low->cs_load && 567 tdq->tdq_lowpri > low->cs_limit) { 568 low->cs_cpu = cpu; 569 low->cs_load = tdq->tdq_load; 570 } 571 if (match & CPU_SEARCH_HIGHEST) 572 if (high->cs_mask & (1 << cpu) && 573 tdq->tdq_load >= high->cs_limit && 574 tdq->tdq_load > high->cs_load && 575 tdq->tdq_transferable) { 576 high->cs_cpu = cpu; 577 high->cs_load = tdq->tdq_load; 578 } 579 return (tdq->tdq_load); 580 } 581 582 /* 583 * Search the tree of cpu_groups for the lowest or highest loaded cpu 584 * according to the match argument. This routine actually compares the 585 * load on all paths through the tree and finds the least loaded cpu on 586 * the least loaded path, which may differ from the least loaded cpu in 587 * the system. This balances work among caches and busses. 588 * 589 * This inline is instantiated in three forms below using constants for the 590 * match argument. It is reduced to the minimum set for each case. It is 591 * also recursive to the depth of the tree. 592 */ 593 static __inline int 594 cpu_search(struct cpu_group *cg, struct cpu_search *low, 595 struct cpu_search *high, const int match) 596 { 597 int total; 598 599 total = 0; 600 if (cg->cg_children) { 601 struct cpu_search lgroup; 602 struct cpu_search hgroup; 603 struct cpu_group *child; 604 u_int lload; 605 int hload; 606 int load; 607 int i; 608 609 lload = -1; 610 hload = -1; 611 for (i = 0; i < cg->cg_children; i++) { 612 child = &cg->cg_child[i]; 613 if (match & CPU_SEARCH_LOWEST) { 614 lgroup = *low; 615 lgroup.cs_load = -1; 616 } 617 if (match & CPU_SEARCH_HIGHEST) { 618 hgroup = *high; 619 lgroup.cs_load = 0; 620 } 621 switch (match) { 622 case CPU_SEARCH_LOWEST: 623 load = cpu_search_lowest(child, &lgroup); 624 break; 625 case CPU_SEARCH_HIGHEST: 626 load = cpu_search_highest(child, &hgroup); 627 break; 628 case CPU_SEARCH_BOTH: 629 load = cpu_search_both(child, &lgroup, &hgroup); 630 break; 631 } 632 total += load; 633 if (match & CPU_SEARCH_LOWEST) 634 if (load < lload || low->cs_cpu == -1) { 635 *low = lgroup; 636 lload = load; 637 } 638 if (match & CPU_SEARCH_HIGHEST) 639 if (load > hload || high->cs_cpu == -1) { 640 hload = load; 641 *high = hgroup; 642 } 643 } 644 } else { 645 int cpu; 646 647 CPUMASK_FOREACH(cpu, cg->cg_mask) 648 total += cpu_compare(cpu, low, high, match); 649 } 650 return (total); 651 } 652 653 /* 654 * cpu_search instantiations must pass constants to maintain the inline 655 * optimization. 656 */ 657 int 658 cpu_search_lowest(struct cpu_group *cg, struct cpu_search *low) 659 { 660 return cpu_search(cg, low, NULL, CPU_SEARCH_LOWEST); 661 } 662 663 int 664 cpu_search_highest(struct cpu_group *cg, struct cpu_search *high) 665 { 666 return cpu_search(cg, NULL, high, CPU_SEARCH_HIGHEST); 667 } 668 669 int 670 cpu_search_both(struct cpu_group *cg, struct cpu_search *low, 671 struct cpu_search *high) 672 { 673 return cpu_search(cg, low, high, CPU_SEARCH_BOTH); 674 } 675 676 /* 677 * Find the cpu with the least load via the least loaded path that has a 678 * lowpri greater than pri pri. A pri of -1 indicates any priority is 679 * acceptable. 680 */ 681 static inline int 682 sched_lowest(struct cpu_group *cg, cpumask_t mask, int pri) 683 { 684 struct cpu_search low; 685 686 low.cs_cpu = -1; 687 low.cs_load = -1; 688 low.cs_mask = mask; 689 low.cs_limit = pri; 690 cpu_search_lowest(cg, &low); 691 return low.cs_cpu; 692 } 693 694 /* 695 * Find the cpu with the highest load via the highest loaded path. 696 */ 697 static inline int 698 sched_highest(struct cpu_group *cg, cpumask_t mask, int minload) 699 { 700 struct cpu_search high; 701 702 high.cs_cpu = -1; 703 high.cs_load = 0; 704 high.cs_mask = mask; 705 high.cs_limit = minload; 706 cpu_search_highest(cg, &high); 707 return high.cs_cpu; 708 } 709 710 /* 711 * Simultaneously find the highest and lowest loaded cpu reachable via 712 * cg. 713 */ 714 static inline void 715 sched_both(struct cpu_group *cg, cpumask_t mask, int *lowcpu, int *highcpu) 716 { 717 struct cpu_search high; 718 struct cpu_search low; 719 720 low.cs_cpu = -1; 721 low.cs_limit = -1; 722 low.cs_load = -1; 723 low.cs_mask = mask; 724 high.cs_load = 0; 725 high.cs_cpu = -1; 726 high.cs_limit = -1; 727 high.cs_mask = mask; 728 cpu_search_both(cg, &low, &high); 729 *lowcpu = low.cs_cpu; 730 *highcpu = high.cs_cpu; 731 return; 732 } 733 734 static void 735 sched_balance_group(struct cpu_group *cg) 736 { 737 cpumask_t mask; 738 int high; 739 int low; 740 int i; 741 742 mask = -1; 743 for (;;) { 744 sched_both(cg, mask, &low, &high); 745 if (low == high || low == -1 || high == -1) 746 break; 747 if (sched_balance_pair(TDQ_CPU(high), TDQ_CPU(low))) 748 break; 749 /* 750 * If we failed to move any threads determine which cpu 751 * to kick out of the set and try again. 752 */ 753 if (TDQ_CPU(high)->tdq_transferable == 0) 754 mask &= ~(1 << high); 755 else 756 mask &= ~(1 << low); 757 } 758 759 for (i = 0; i < cg->cg_children; i++) 760 sched_balance_group(&cg->cg_child[i]); 761 } 762 763 static void 764 sched_balance() 765 { 766 struct tdq *tdq; 767 768 /* 769 * Select a random time between .5 * balance_interval and 770 * 1.5 * balance_interval. 771 */ 772 balance_ticks = max(balance_interval / 2, 1); 773 balance_ticks += random() % balance_interval; 774 if (smp_started == 0 || rebalance == 0) 775 return; 776 tdq = TDQ_SELF(); 777 TDQ_UNLOCK(tdq); 778 sched_balance_group(cpu_top); 779 TDQ_LOCK(tdq); 780 } 781 782 /* 783 * Lock two thread queues using their address to maintain lock order. 784 */ 785 static void 786 tdq_lock_pair(struct tdq *one, struct tdq *two) 787 { 788 if (one < two) { 789 TDQ_LOCK(one); 790 TDQ_LOCK_FLAGS(two, MTX_DUPOK); 791 } else { 792 TDQ_LOCK(two); 793 TDQ_LOCK_FLAGS(one, MTX_DUPOK); 794 } 795 } 796 797 /* 798 * Unlock two thread queues. Order is not important here. 799 */ 800 static void 801 tdq_unlock_pair(struct tdq *one, struct tdq *two) 802 { 803 TDQ_UNLOCK(one); 804 TDQ_UNLOCK(two); 805 } 806 807 /* 808 * Transfer load between two imbalanced thread queues. 809 */ 810 static int 811 sched_balance_pair(struct tdq *high, struct tdq *low) 812 { 813 int transferable; 814 int high_load; 815 int low_load; 816 int moved; 817 int move; 818 int diff; 819 int i; 820 821 tdq_lock_pair(high, low); 822 transferable = high->tdq_transferable; 823 high_load = high->tdq_load; 824 low_load = low->tdq_load; 825 moved = 0; 826 /* 827 * Determine what the imbalance is and then adjust that to how many 828 * threads we actually have to give up (transferable). 829 */ 830 if (transferable != 0) { 831 diff = high_load - low_load; 832 move = diff / 2; 833 if (diff & 0x1) 834 move++; 835 move = min(move, transferable); 836 for (i = 0; i < move; i++) 837 moved += tdq_move(high, low); 838 /* 839 * IPI the target cpu to force it to reschedule with the new 840 * workload. 841 */ 842 ipi_selected(1 << TDQ_ID(low), IPI_PREEMPT); 843 } 844 tdq_unlock_pair(high, low); 845 return (moved); 846 } 847 848 /* 849 * Move a thread from one thread queue to another. 850 */ 851 static int 852 tdq_move(struct tdq *from, struct tdq *to) 853 { 854 struct td_sched *ts; 855 struct thread *td; 856 struct tdq *tdq; 857 int cpu; 858 859 TDQ_LOCK_ASSERT(from, MA_OWNED); 860 TDQ_LOCK_ASSERT(to, MA_OWNED); 861 862 tdq = from; 863 cpu = TDQ_ID(to); 864 td = tdq_steal(tdq, cpu); 865 if (td == NULL) 866 return (0); 867 ts = td->td_sched; 868 /* 869 * Although the run queue is locked the thread may be blocked. Lock 870 * it to clear this and acquire the run-queue lock. 871 */ 872 thread_lock(td); 873 /* Drop recursive lock on from acquired via thread_lock(). */ 874 TDQ_UNLOCK(from); 875 sched_rem(td); 876 ts->ts_cpu = cpu; 877 td->td_lock = TDQ_LOCKPTR(to); 878 tdq_add(to, td, SRQ_YIELDING); 879 return (1); 880 } 881 882 /* 883 * This tdq has idled. Try to steal a thread from another cpu and switch 884 * to it. 885 */ 886 static int 887 tdq_idled(struct tdq *tdq) 888 { 889 struct cpu_group *cg; 890 struct tdq *steal; 891 cpumask_t mask; 892 int thresh; 893 int cpu; 894 895 if (smp_started == 0 || steal_idle == 0) 896 return (1); 897 mask = -1; 898 mask &= ~PCPU_GET(cpumask); 899 /* We don't want to be preempted while we're iterating. */ 900 spinlock_enter(); 901 for (cg = tdq->tdq_cg; cg != NULL; ) { 902 if ((cg->cg_flags & (CG_FLAG_HTT | CG_FLAG_THREAD)) == 0) 903 thresh = steal_thresh; 904 else 905 thresh = 1; 906 cpu = sched_highest(cg, mask, thresh); 907 if (cpu == -1) { 908 cg = cg->cg_parent; 909 continue; 910 } 911 steal = TDQ_CPU(cpu); 912 mask &= ~(1 << cpu); 913 tdq_lock_pair(tdq, steal); 914 if (steal->tdq_load < thresh || steal->tdq_transferable == 0) { 915 tdq_unlock_pair(tdq, steal); 916 continue; 917 } 918 /* 919 * If a thread was added while interrupts were disabled don't 920 * steal one here. If we fail to acquire one due to affinity 921 * restrictions loop again with this cpu removed from the 922 * set. 923 */ 924 if (tdq->tdq_load == 0 && tdq_move(steal, tdq) == 0) { 925 tdq_unlock_pair(tdq, steal); 926 continue; 927 } 928 spinlock_exit(); 929 TDQ_UNLOCK(steal); 930 mi_switch(SW_VOL | SWT_IDLE, NULL); 931 thread_unlock(curthread); 932 933 return (0); 934 } 935 spinlock_exit(); 936 return (1); 937 } 938 939 /* 940 * Notify a remote cpu of new work. Sends an IPI if criteria are met. 941 */ 942 static void 943 tdq_notify(struct tdq *tdq, struct thread *td) 944 { 945 int cpri; 946 int pri; 947 int cpu; 948 949 if (tdq->tdq_ipipending) 950 return; 951 cpu = td->td_sched->ts_cpu; 952 pri = td->td_priority; 953 cpri = pcpu_find(cpu)->pc_curthread->td_priority; 954 if (!sched_shouldpreempt(pri, cpri, 1)) 955 return; 956 if (TD_IS_IDLETHREAD(td)) { 957 /* 958 * If the idle thread is still 'running' it's probably 959 * waiting on us to release the tdq spinlock already. No 960 * need to ipi. 961 */ 962 if (tdq->tdq_idlestate == TDQ_RUNNING) 963 return; 964 /* 965 * If the MD code has an idle wakeup routine try that before 966 * falling back to IPI. 967 */ 968 if (cpu_idle_wakeup(cpu)) 969 return; 970 } 971 tdq->tdq_ipipending = 1; 972 ipi_selected(1 << cpu, IPI_PREEMPT); 973 } 974 975 /* 976 * Steals load from a timeshare queue. Honors the rotating queue head 977 * index. 978 */ 979 static struct thread * 980 runq_steal_from(struct runq *rq, int cpu, u_char start) 981 { 982 struct rqbits *rqb; 983 struct rqhead *rqh; 984 struct thread *td; 985 int first; 986 int bit; 987 int pri; 988 int i; 989 990 rqb = &rq->rq_status; 991 bit = start & (RQB_BPW -1); 992 pri = 0; 993 first = 0; 994 again: 995 for (i = RQB_WORD(start); i < RQB_LEN; bit = 0, i++) { 996 if (rqb->rqb_bits[i] == 0) 997 continue; 998 if (bit != 0) { 999 for (pri = bit; pri < RQB_BPW; pri++) 1000 if (rqb->rqb_bits[i] & (1ul << pri)) 1001 break; 1002 if (pri >= RQB_BPW) 1003 continue; 1004 } else 1005 pri = RQB_FFS(rqb->rqb_bits[i]); 1006 pri += (i << RQB_L2BPW); 1007 rqh = &rq->rq_queues[pri]; 1008 TAILQ_FOREACH(td, rqh, td_runq) { 1009 if (first && THREAD_CAN_MIGRATE(td) && 1010 THREAD_CAN_SCHED(td, cpu)) 1011 return (td); 1012 first = 1; 1013 } 1014 } 1015 if (start != 0) { 1016 start = 0; 1017 goto again; 1018 } 1019 1020 return (NULL); 1021 } 1022 1023 /* 1024 * Steals load from a standard linear queue. 1025 */ 1026 static struct thread * 1027 runq_steal(struct runq *rq, int cpu) 1028 { 1029 struct rqhead *rqh; 1030 struct rqbits *rqb; 1031 struct thread *td; 1032 int word; 1033 int bit; 1034 1035 rqb = &rq->rq_status; 1036 for (word = 0; word < RQB_LEN; word++) { 1037 if (rqb->rqb_bits[word] == 0) 1038 continue; 1039 for (bit = 0; bit < RQB_BPW; bit++) { 1040 if ((rqb->rqb_bits[word] & (1ul << bit)) == 0) 1041 continue; 1042 rqh = &rq->rq_queues[bit + (word << RQB_L2BPW)]; 1043 TAILQ_FOREACH(td, rqh, td_runq) 1044 if (THREAD_CAN_MIGRATE(td) && 1045 THREAD_CAN_SCHED(td, cpu)) 1046 return (td); 1047 } 1048 } 1049 return (NULL); 1050 } 1051 1052 /* 1053 * Attempt to steal a thread in priority order from a thread queue. 1054 */ 1055 static struct thread * 1056 tdq_steal(struct tdq *tdq, int cpu) 1057 { 1058 struct thread *td; 1059 1060 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1061 if ((td = runq_steal(&tdq->tdq_realtime, cpu)) != NULL) 1062 return (td); 1063 if ((td = runq_steal_from(&tdq->tdq_timeshare, 1064 cpu, tdq->tdq_ridx)) != NULL) 1065 return (td); 1066 return (runq_steal(&tdq->tdq_idle, cpu)); 1067 } 1068 1069 /* 1070 * Sets the thread lock and ts_cpu to match the requested cpu. Unlocks the 1071 * current lock and returns with the assigned queue locked. 1072 */ 1073 static inline struct tdq * 1074 sched_setcpu(struct thread *td, int cpu, int flags) 1075 { 1076 1077 struct tdq *tdq; 1078 1079 THREAD_LOCK_ASSERT(td, MA_OWNED); 1080 tdq = TDQ_CPU(cpu); 1081 td->td_sched->ts_cpu = cpu; 1082 /* 1083 * If the lock matches just return the queue. 1084 */ 1085 if (td->td_lock == TDQ_LOCKPTR(tdq)) 1086 return (tdq); 1087 #ifdef notyet 1088 /* 1089 * If the thread isn't running its lockptr is a 1090 * turnstile or a sleepqueue. We can just lock_set without 1091 * blocking. 1092 */ 1093 if (TD_CAN_RUN(td)) { 1094 TDQ_LOCK(tdq); 1095 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 1096 return (tdq); 1097 } 1098 #endif 1099 /* 1100 * The hard case, migration, we need to block the thread first to 1101 * prevent order reversals with other cpus locks. 1102 */ 1103 thread_lock_block(td); 1104 TDQ_LOCK(tdq); 1105 thread_lock_unblock(td, TDQ_LOCKPTR(tdq)); 1106 return (tdq); 1107 } 1108 1109 SCHED_STAT_DEFINE(pickcpu_intrbind, "Soft interrupt binding"); 1110 SCHED_STAT_DEFINE(pickcpu_idle_affinity, "Picked idle cpu based on affinity"); 1111 SCHED_STAT_DEFINE(pickcpu_affinity, "Picked cpu based on affinity"); 1112 SCHED_STAT_DEFINE(pickcpu_lowest, "Selected lowest load"); 1113 SCHED_STAT_DEFINE(pickcpu_local, "Migrated to current cpu"); 1114 SCHED_STAT_DEFINE(pickcpu_migration, "Selection may have caused migration"); 1115 1116 static int 1117 sched_pickcpu(struct thread *td, int flags) 1118 { 1119 struct cpu_group *cg; 1120 struct td_sched *ts; 1121 struct tdq *tdq; 1122 cpumask_t mask; 1123 int self; 1124 int pri; 1125 int cpu; 1126 1127 self = PCPU_GET(cpuid); 1128 ts = td->td_sched; 1129 if (smp_started == 0) 1130 return (self); 1131 /* 1132 * Don't migrate a running thread from sched_switch(). 1133 */ 1134 if ((flags & SRQ_OURSELF) || !THREAD_CAN_MIGRATE(td)) 1135 return (ts->ts_cpu); 1136 /* 1137 * Prefer to run interrupt threads on the processors that generate 1138 * the interrupt. 1139 */ 1140 if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_SCHED(td, self) && 1141 curthread->td_intr_nesting_level && ts->ts_cpu != self) { 1142 SCHED_STAT_INC(pickcpu_intrbind); 1143 ts->ts_cpu = self; 1144 } 1145 /* 1146 * If the thread can run on the last cpu and the affinity has not 1147 * expired or it is idle run it there. 1148 */ 1149 pri = td->td_priority; 1150 tdq = TDQ_CPU(ts->ts_cpu); 1151 if (THREAD_CAN_SCHED(td, ts->ts_cpu)) { 1152 if (tdq->tdq_lowpri > PRI_MIN_IDLE) { 1153 SCHED_STAT_INC(pickcpu_idle_affinity); 1154 return (ts->ts_cpu); 1155 } 1156 if (SCHED_AFFINITY(ts, CG_SHARE_L2) && tdq->tdq_lowpri > pri) { 1157 SCHED_STAT_INC(pickcpu_affinity); 1158 return (ts->ts_cpu); 1159 } 1160 } 1161 /* 1162 * Search for the highest level in the tree that still has affinity. 1163 */ 1164 cg = NULL; 1165 for (cg = tdq->tdq_cg; cg != NULL; cg = cg->cg_parent) 1166 if (SCHED_AFFINITY(ts, cg->cg_level)) 1167 break; 1168 cpu = -1; 1169 mask = td->td_cpuset->cs_mask.__bits[0]; 1170 if (cg) 1171 cpu = sched_lowest(cg, mask, pri); 1172 if (cpu == -1) 1173 cpu = sched_lowest(cpu_top, mask, -1); 1174 /* 1175 * Compare the lowest loaded cpu to current cpu. 1176 */ 1177 if (THREAD_CAN_SCHED(td, self) && TDQ_CPU(self)->tdq_lowpri > pri && 1178 TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE) { 1179 SCHED_STAT_INC(pickcpu_local); 1180 cpu = self; 1181 } else 1182 SCHED_STAT_INC(pickcpu_lowest); 1183 if (cpu != ts->ts_cpu) 1184 SCHED_STAT_INC(pickcpu_migration); 1185 KASSERT(cpu != -1, ("sched_pickcpu: Failed to find a cpu.")); 1186 return (cpu); 1187 } 1188 #endif 1189 1190 /* 1191 * Pick the highest priority task we have and return it. 1192 */ 1193 static struct thread * 1194 tdq_choose(struct tdq *tdq) 1195 { 1196 struct thread *td; 1197 1198 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1199 td = runq_choose(&tdq->tdq_realtime); 1200 if (td != NULL) 1201 return (td); 1202 td = runq_choose_from(&tdq->tdq_timeshare, tdq->tdq_ridx); 1203 if (td != NULL) { 1204 KASSERT(td->td_priority >= PRI_MIN_TIMESHARE, 1205 ("tdq_choose: Invalid priority on timeshare queue %d", 1206 td->td_priority)); 1207 return (td); 1208 } 1209 td = runq_choose(&tdq->tdq_idle); 1210 if (td != NULL) { 1211 KASSERT(td->td_priority >= PRI_MIN_IDLE, 1212 ("tdq_choose: Invalid priority on idle queue %d", 1213 td->td_priority)); 1214 return (td); 1215 } 1216 1217 return (NULL); 1218 } 1219 1220 /* 1221 * Initialize a thread queue. 1222 */ 1223 static void 1224 tdq_setup(struct tdq *tdq) 1225 { 1226 1227 if (bootverbose) 1228 printf("ULE: setup cpu %d\n", TDQ_ID(tdq)); 1229 runq_init(&tdq->tdq_realtime); 1230 runq_init(&tdq->tdq_timeshare); 1231 runq_init(&tdq->tdq_idle); 1232 snprintf(tdq->tdq_name, sizeof(tdq->tdq_name), 1233 "sched lock %d", (int)TDQ_ID(tdq)); 1234 mtx_init(&tdq->tdq_lock, tdq->tdq_name, "sched lock", 1235 MTX_SPIN | MTX_RECURSE); 1236 } 1237 1238 #ifdef SMP 1239 static void 1240 sched_setup_smp(void) 1241 { 1242 struct tdq *tdq; 1243 int i; 1244 1245 cpu_top = smp_topo(); 1246 for (i = 0; i < MAXCPU; i++) { 1247 if (CPU_ABSENT(i)) 1248 continue; 1249 tdq = TDQ_CPU(i); 1250 tdq_setup(tdq); 1251 tdq->tdq_cg = smp_topo_find(cpu_top, i); 1252 if (tdq->tdq_cg == NULL) 1253 panic("Can't find cpu group for %d\n", i); 1254 } 1255 balance_tdq = TDQ_SELF(); 1256 sched_balance(); 1257 } 1258 #endif 1259 1260 /* 1261 * Setup the thread queues and initialize the topology based on MD 1262 * information. 1263 */ 1264 static void 1265 sched_setup(void *dummy) 1266 { 1267 struct tdq *tdq; 1268 1269 tdq = TDQ_SELF(); 1270 #ifdef SMP 1271 sched_setup_smp(); 1272 #else 1273 tdq_setup(tdq); 1274 #endif 1275 /* 1276 * To avoid divide-by-zero, we set realstathz a dummy value 1277 * in case which sched_clock() called before sched_initticks(). 1278 */ 1279 realstathz = hz; 1280 sched_slice = (realstathz/10); /* ~100ms */ 1281 tickincr = 1 << SCHED_TICK_SHIFT; 1282 1283 /* Add thread0's load since it's running. */ 1284 TDQ_LOCK(tdq); 1285 thread0.td_lock = TDQ_LOCKPTR(TDQ_SELF()); 1286 tdq_load_add(tdq, &thread0); 1287 tdq->tdq_lowpri = thread0.td_priority; 1288 TDQ_UNLOCK(tdq); 1289 } 1290 1291 /* 1292 * This routine determines the tickincr after stathz and hz are setup. 1293 */ 1294 /* ARGSUSED */ 1295 static void 1296 sched_initticks(void *dummy) 1297 { 1298 int incr; 1299 1300 realstathz = stathz ? stathz : hz; 1301 sched_slice = (realstathz/10); /* ~100ms */ 1302 1303 /* 1304 * tickincr is shifted out by 10 to avoid rounding errors due to 1305 * hz not being evenly divisible by stathz on all platforms. 1306 */ 1307 incr = (hz << SCHED_TICK_SHIFT) / realstathz; 1308 /* 1309 * This does not work for values of stathz that are more than 1310 * 1 << SCHED_TICK_SHIFT * hz. In practice this does not happen. 1311 */ 1312 if (incr == 0) 1313 incr = 1; 1314 tickincr = incr; 1315 #ifdef SMP 1316 /* 1317 * Set the default balance interval now that we know 1318 * what realstathz is. 1319 */ 1320 balance_interval = realstathz; 1321 /* 1322 * Set steal thresh to log2(mp_ncpu) but no greater than 4. This 1323 * prevents excess thrashing on large machines and excess idle on 1324 * smaller machines. 1325 */ 1326 steal_thresh = min(ffs(mp_ncpus) - 1, 3); 1327 affinity = SCHED_AFFINITY_DEFAULT; 1328 #endif 1329 } 1330 1331 1332 /* 1333 * This is the core of the interactivity algorithm. Determines a score based 1334 * on past behavior. It is the ratio of sleep time to run time scaled to 1335 * a [0, 100] integer. This is the voluntary sleep time of a process, which 1336 * differs from the cpu usage because it does not account for time spent 1337 * waiting on a run-queue. Would be prettier if we had floating point. 1338 */ 1339 static int 1340 sched_interact_score(struct thread *td) 1341 { 1342 struct td_sched *ts; 1343 int div; 1344 1345 ts = td->td_sched; 1346 /* 1347 * The score is only needed if this is likely to be an interactive 1348 * task. Don't go through the expense of computing it if there's 1349 * no chance. 1350 */ 1351 if (sched_interact <= SCHED_INTERACT_HALF && 1352 ts->ts_runtime >= ts->ts_slptime) 1353 return (SCHED_INTERACT_HALF); 1354 1355 if (ts->ts_runtime > ts->ts_slptime) { 1356 div = max(1, ts->ts_runtime / SCHED_INTERACT_HALF); 1357 return (SCHED_INTERACT_HALF + 1358 (SCHED_INTERACT_HALF - (ts->ts_slptime / div))); 1359 } 1360 if (ts->ts_slptime > ts->ts_runtime) { 1361 div = max(1, ts->ts_slptime / SCHED_INTERACT_HALF); 1362 return (ts->ts_runtime / div); 1363 } 1364 /* runtime == slptime */ 1365 if (ts->ts_runtime) 1366 return (SCHED_INTERACT_HALF); 1367 1368 /* 1369 * This can happen if slptime and runtime are 0. 1370 */ 1371 return (0); 1372 1373 } 1374 1375 /* 1376 * Scale the scheduling priority according to the "interactivity" of this 1377 * process. 1378 */ 1379 static void 1380 sched_priority(struct thread *td) 1381 { 1382 int score; 1383 int pri; 1384 1385 if (td->td_pri_class != PRI_TIMESHARE) 1386 return; 1387 /* 1388 * If the score is interactive we place the thread in the realtime 1389 * queue with a priority that is less than kernel and interrupt 1390 * priorities. These threads are not subject to nice restrictions. 1391 * 1392 * Scores greater than this are placed on the normal timeshare queue 1393 * where the priority is partially decided by the most recent cpu 1394 * utilization and the rest is decided by nice value. 1395 * 1396 * The nice value of the process has a linear effect on the calculated 1397 * score. Negative nice values make it easier for a thread to be 1398 * considered interactive. 1399 */ 1400 score = imax(0, sched_interact_score(td) - td->td_proc->p_nice); 1401 if (score < sched_interact) { 1402 pri = PRI_MIN_REALTIME; 1403 pri += ((PRI_MAX_REALTIME - PRI_MIN_REALTIME) / sched_interact) 1404 * score; 1405 KASSERT(pri >= PRI_MIN_REALTIME && pri <= PRI_MAX_REALTIME, 1406 ("sched_priority: invalid interactive priority %d score %d", 1407 pri, score)); 1408 } else { 1409 pri = SCHED_PRI_MIN; 1410 if (td->td_sched->ts_ticks) 1411 pri += SCHED_PRI_TICKS(td->td_sched); 1412 pri += SCHED_PRI_NICE(td->td_proc->p_nice); 1413 KASSERT(pri >= PRI_MIN_TIMESHARE && pri <= PRI_MAX_TIMESHARE, 1414 ("sched_priority: invalid priority %d: nice %d, " 1415 "ticks %d ftick %d ltick %d tick pri %d", 1416 pri, td->td_proc->p_nice, td->td_sched->ts_ticks, 1417 td->td_sched->ts_ftick, td->td_sched->ts_ltick, 1418 SCHED_PRI_TICKS(td->td_sched))); 1419 } 1420 sched_user_prio(td, pri); 1421 1422 return; 1423 } 1424 1425 /* 1426 * This routine enforces a maximum limit on the amount of scheduling history 1427 * kept. It is called after either the slptime or runtime is adjusted. This 1428 * function is ugly due to integer math. 1429 */ 1430 static void 1431 sched_interact_update(struct thread *td) 1432 { 1433 struct td_sched *ts; 1434 u_int sum; 1435 1436 ts = td->td_sched; 1437 sum = ts->ts_runtime + ts->ts_slptime; 1438 if (sum < SCHED_SLP_RUN_MAX) 1439 return; 1440 /* 1441 * This only happens from two places: 1442 * 1) We have added an unusual amount of run time from fork_exit. 1443 * 2) We have added an unusual amount of sleep time from sched_sleep(). 1444 */ 1445 if (sum > SCHED_SLP_RUN_MAX * 2) { 1446 if (ts->ts_runtime > ts->ts_slptime) { 1447 ts->ts_runtime = SCHED_SLP_RUN_MAX; 1448 ts->ts_slptime = 1; 1449 } else { 1450 ts->ts_slptime = SCHED_SLP_RUN_MAX; 1451 ts->ts_runtime = 1; 1452 } 1453 return; 1454 } 1455 /* 1456 * If we have exceeded by more than 1/5th then the algorithm below 1457 * will not bring us back into range. Dividing by two here forces 1458 * us into the range of [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX] 1459 */ 1460 if (sum > (SCHED_SLP_RUN_MAX / 5) * 6) { 1461 ts->ts_runtime /= 2; 1462 ts->ts_slptime /= 2; 1463 return; 1464 } 1465 ts->ts_runtime = (ts->ts_runtime / 5) * 4; 1466 ts->ts_slptime = (ts->ts_slptime / 5) * 4; 1467 } 1468 1469 /* 1470 * Scale back the interactivity history when a child thread is created. The 1471 * history is inherited from the parent but the thread may behave totally 1472 * differently. For example, a shell spawning a compiler process. We want 1473 * to learn that the compiler is behaving badly very quickly. 1474 */ 1475 static void 1476 sched_interact_fork(struct thread *td) 1477 { 1478 int ratio; 1479 int sum; 1480 1481 sum = td->td_sched->ts_runtime + td->td_sched->ts_slptime; 1482 if (sum > SCHED_SLP_RUN_FORK) { 1483 ratio = sum / SCHED_SLP_RUN_FORK; 1484 td->td_sched->ts_runtime /= ratio; 1485 td->td_sched->ts_slptime /= ratio; 1486 } 1487 } 1488 1489 /* 1490 * Called from proc0_init() to setup the scheduler fields. 1491 */ 1492 void 1493 schedinit(void) 1494 { 1495 1496 /* 1497 * Set up the scheduler specific parts of proc0. 1498 */ 1499 proc0.p_sched = NULL; /* XXX */ 1500 thread0.td_sched = &td_sched0; 1501 td_sched0.ts_ltick = ticks; 1502 td_sched0.ts_ftick = ticks; 1503 td_sched0.ts_slice = sched_slice; 1504 } 1505 1506 /* 1507 * This is only somewhat accurate since given many processes of the same 1508 * priority they will switch when their slices run out, which will be 1509 * at most sched_slice stathz ticks. 1510 */ 1511 int 1512 sched_rr_interval(void) 1513 { 1514 1515 /* Convert sched_slice to hz */ 1516 return (hz/(realstathz/sched_slice)); 1517 } 1518 1519 /* 1520 * Update the percent cpu tracking information when it is requested or 1521 * the total history exceeds the maximum. We keep a sliding history of 1522 * tick counts that slowly decays. This is less precise than the 4BSD 1523 * mechanism since it happens with less regular and frequent events. 1524 */ 1525 static void 1526 sched_pctcpu_update(struct td_sched *ts) 1527 { 1528 1529 if (ts->ts_ticks == 0) 1530 return; 1531 if (ticks - (hz / 10) < ts->ts_ltick && 1532 SCHED_TICK_TOTAL(ts) < SCHED_TICK_MAX) 1533 return; 1534 /* 1535 * Adjust counters and watermark for pctcpu calc. 1536 */ 1537 if (ts->ts_ltick > ticks - SCHED_TICK_TARG) 1538 ts->ts_ticks = (ts->ts_ticks / (ticks - ts->ts_ftick)) * 1539 SCHED_TICK_TARG; 1540 else 1541 ts->ts_ticks = 0; 1542 ts->ts_ltick = ticks; 1543 ts->ts_ftick = ts->ts_ltick - SCHED_TICK_TARG; 1544 } 1545 1546 /* 1547 * Adjust the priority of a thread. Move it to the appropriate run-queue 1548 * if necessary. This is the back-end for several priority related 1549 * functions. 1550 */ 1551 static void 1552 sched_thread_priority(struct thread *td, u_char prio) 1553 { 1554 struct td_sched *ts; 1555 struct tdq *tdq; 1556 int oldpri; 1557 1558 CTR6(KTR_SCHED, "sched_prio: %p(%s) prio %d newprio %d by %p(%s)", 1559 td, td->td_name, td->td_priority, prio, curthread, 1560 curthread->td_name); 1561 ts = td->td_sched; 1562 THREAD_LOCK_ASSERT(td, MA_OWNED); 1563 if (td->td_priority == prio) 1564 return; 1565 /* 1566 * If the priority has been elevated due to priority 1567 * propagation, we may have to move ourselves to a new 1568 * queue. This could be optimized to not re-add in some 1569 * cases. 1570 */ 1571 if (TD_ON_RUNQ(td) && prio < td->td_priority) { 1572 sched_rem(td); 1573 td->td_priority = prio; 1574 sched_add(td, SRQ_BORROWING); 1575 return; 1576 } 1577 /* 1578 * If the thread is currently running we may have to adjust the lowpri 1579 * information so other cpus are aware of our current priority. 1580 */ 1581 if (TD_IS_RUNNING(td)) { 1582 tdq = TDQ_CPU(ts->ts_cpu); 1583 oldpri = td->td_priority; 1584 td->td_priority = prio; 1585 if (prio < tdq->tdq_lowpri) 1586 tdq->tdq_lowpri = prio; 1587 else if (tdq->tdq_lowpri == oldpri) 1588 tdq_setlowpri(tdq, td); 1589 return; 1590 } 1591 td->td_priority = prio; 1592 } 1593 1594 /* 1595 * Update a thread's priority when it is lent another thread's 1596 * priority. 1597 */ 1598 void 1599 sched_lend_prio(struct thread *td, u_char prio) 1600 { 1601 1602 td->td_flags |= TDF_BORROWING; 1603 sched_thread_priority(td, prio); 1604 } 1605 1606 /* 1607 * Restore a thread's priority when priority propagation is 1608 * over. The prio argument is the minimum priority the thread 1609 * needs to have to satisfy other possible priority lending 1610 * requests. If the thread's regular priority is less 1611 * important than prio, the thread will keep a priority boost 1612 * of prio. 1613 */ 1614 void 1615 sched_unlend_prio(struct thread *td, u_char prio) 1616 { 1617 u_char base_pri; 1618 1619 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 1620 td->td_base_pri <= PRI_MAX_TIMESHARE) 1621 base_pri = td->td_user_pri; 1622 else 1623 base_pri = td->td_base_pri; 1624 if (prio >= base_pri) { 1625 td->td_flags &= ~TDF_BORROWING; 1626 sched_thread_priority(td, base_pri); 1627 } else 1628 sched_lend_prio(td, prio); 1629 } 1630 1631 /* 1632 * Standard entry for setting the priority to an absolute value. 1633 */ 1634 void 1635 sched_prio(struct thread *td, u_char prio) 1636 { 1637 u_char oldprio; 1638 1639 /* First, update the base priority. */ 1640 td->td_base_pri = prio; 1641 1642 /* 1643 * If the thread is borrowing another thread's priority, don't 1644 * ever lower the priority. 1645 */ 1646 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 1647 return; 1648 1649 /* Change the real priority. */ 1650 oldprio = td->td_priority; 1651 sched_thread_priority(td, prio); 1652 1653 /* 1654 * If the thread is on a turnstile, then let the turnstile update 1655 * its state. 1656 */ 1657 if (TD_ON_LOCK(td) && oldprio != prio) 1658 turnstile_adjust(td, oldprio); 1659 } 1660 1661 /* 1662 * Set the base user priority, does not effect current running priority. 1663 */ 1664 void 1665 sched_user_prio(struct thread *td, u_char prio) 1666 { 1667 u_char oldprio; 1668 1669 td->td_base_user_pri = prio; 1670 if (td->td_flags & TDF_UBORROWING && td->td_user_pri <= prio) 1671 return; 1672 oldprio = td->td_user_pri; 1673 td->td_user_pri = prio; 1674 } 1675 1676 void 1677 sched_lend_user_prio(struct thread *td, u_char prio) 1678 { 1679 u_char oldprio; 1680 1681 THREAD_LOCK_ASSERT(td, MA_OWNED); 1682 td->td_flags |= TDF_UBORROWING; 1683 oldprio = td->td_user_pri; 1684 td->td_user_pri = prio; 1685 } 1686 1687 void 1688 sched_unlend_user_prio(struct thread *td, u_char prio) 1689 { 1690 u_char base_pri; 1691 1692 THREAD_LOCK_ASSERT(td, MA_OWNED); 1693 base_pri = td->td_base_user_pri; 1694 if (prio >= base_pri) { 1695 td->td_flags &= ~TDF_UBORROWING; 1696 sched_user_prio(td, base_pri); 1697 } else { 1698 sched_lend_user_prio(td, prio); 1699 } 1700 } 1701 1702 /* 1703 * Block a thread for switching. Similar to thread_block() but does not 1704 * bump the spin count. 1705 */ 1706 static inline struct mtx * 1707 thread_block_switch(struct thread *td) 1708 { 1709 struct mtx *lock; 1710 1711 THREAD_LOCK_ASSERT(td, MA_OWNED); 1712 lock = td->td_lock; 1713 td->td_lock = &blocked_lock; 1714 mtx_unlock_spin(lock); 1715 1716 return (lock); 1717 } 1718 1719 /* 1720 * Handle migration from sched_switch(). This happens only for 1721 * cpu binding. 1722 */ 1723 static struct mtx * 1724 sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags) 1725 { 1726 struct tdq *tdn; 1727 1728 tdn = TDQ_CPU(td->td_sched->ts_cpu); 1729 #ifdef SMP 1730 tdq_load_rem(tdq, td); 1731 /* 1732 * Do the lock dance required to avoid LOR. We grab an extra 1733 * spinlock nesting to prevent preemption while we're 1734 * not holding either run-queue lock. 1735 */ 1736 spinlock_enter(); 1737 thread_block_switch(td); /* This releases the lock on tdq. */ 1738 TDQ_LOCK(tdn); 1739 tdq_add(tdn, td, flags); 1740 tdq_notify(tdn, td); 1741 /* 1742 * After we unlock tdn the new cpu still can't switch into this 1743 * thread until we've unblocked it in cpu_switch(). The lock 1744 * pointers may match in the case of HTT cores. Don't unlock here 1745 * or we can deadlock when the other CPU runs the IPI handler. 1746 */ 1747 if (TDQ_LOCKPTR(tdn) != TDQ_LOCKPTR(tdq)) { 1748 TDQ_UNLOCK(tdn); 1749 TDQ_LOCK(tdq); 1750 } 1751 spinlock_exit(); 1752 #endif 1753 return (TDQ_LOCKPTR(tdn)); 1754 } 1755 1756 /* 1757 * Release a thread that was blocked with thread_block_switch(). 1758 */ 1759 static inline void 1760 thread_unblock_switch(struct thread *td, struct mtx *mtx) 1761 { 1762 atomic_store_rel_ptr((volatile uintptr_t *)&td->td_lock, 1763 (uintptr_t)mtx); 1764 } 1765 1766 /* 1767 * Switch threads. This function has to handle threads coming in while 1768 * blocked for some reason, running, or idle. It also must deal with 1769 * migrating a thread from one queue to another as running threads may 1770 * be assigned elsewhere via binding. 1771 */ 1772 void 1773 sched_switch(struct thread *td, struct thread *newtd, int flags) 1774 { 1775 struct tdq *tdq; 1776 struct td_sched *ts; 1777 struct mtx *mtx; 1778 int srqflag; 1779 int cpuid; 1780 1781 THREAD_LOCK_ASSERT(td, MA_OWNED); 1782 KASSERT(newtd == NULL, ("sched_switch: Unsupported newtd argument")); 1783 1784 cpuid = PCPU_GET(cpuid); 1785 tdq = TDQ_CPU(cpuid); 1786 ts = td->td_sched; 1787 mtx = td->td_lock; 1788 ts->ts_rltick = ticks; 1789 td->td_lastcpu = td->td_oncpu; 1790 td->td_oncpu = NOCPU; 1791 td->td_flags &= ~TDF_NEEDRESCHED; 1792 td->td_owepreempt = 0; 1793 tdq->tdq_switchcnt++; 1794 /* 1795 * The lock pointer in an idle thread should never change. Reset it 1796 * to CAN_RUN as well. 1797 */ 1798 if (TD_IS_IDLETHREAD(td)) { 1799 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1800 TD_SET_CAN_RUN(td); 1801 } else if (TD_IS_RUNNING(td)) { 1802 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1803 srqflag = (flags & SW_PREEMPT) ? 1804 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 1805 SRQ_OURSELF|SRQ_YIELDING; 1806 if (ts->ts_cpu == cpuid) 1807 tdq_runq_add(tdq, td, srqflag); 1808 else 1809 mtx = sched_switch_migrate(tdq, td, srqflag); 1810 } else { 1811 /* This thread must be going to sleep. */ 1812 TDQ_LOCK(tdq); 1813 mtx = thread_block_switch(td); 1814 tdq_load_rem(tdq, td); 1815 } 1816 /* 1817 * We enter here with the thread blocked and assigned to the 1818 * appropriate cpu run-queue or sleep-queue and with the current 1819 * thread-queue locked. 1820 */ 1821 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 1822 newtd = choosethread(); 1823 /* 1824 * Call the MD code to switch contexts if necessary. 1825 */ 1826 if (td != newtd) { 1827 #ifdef HWPMC_HOOKS 1828 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1829 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 1830 #endif 1831 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 1832 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 1833 1834 #ifdef KDTRACE_HOOKS 1835 /* 1836 * If DTrace has set the active vtime enum to anything 1837 * other than INACTIVE (0), then it should have set the 1838 * function to call. 1839 */ 1840 if (dtrace_vtime_active) 1841 (*dtrace_vtime_switch_func)(newtd); 1842 #endif 1843 1844 cpu_switch(td, newtd, mtx); 1845 /* 1846 * We may return from cpu_switch on a different cpu. However, 1847 * we always return with td_lock pointing to the current cpu's 1848 * run queue lock. 1849 */ 1850 cpuid = PCPU_GET(cpuid); 1851 tdq = TDQ_CPU(cpuid); 1852 lock_profile_obtain_lock_success( 1853 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 1854 #ifdef HWPMC_HOOKS 1855 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1856 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 1857 #endif 1858 } else 1859 thread_unblock_switch(td, mtx); 1860 /* 1861 * Assert that all went well and return. 1862 */ 1863 TDQ_LOCK_ASSERT(tdq, MA_OWNED|MA_NOTRECURSED); 1864 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1865 td->td_oncpu = cpuid; 1866 } 1867 1868 /* 1869 * Adjust thread priorities as a result of a nice request. 1870 */ 1871 void 1872 sched_nice(struct proc *p, int nice) 1873 { 1874 struct thread *td; 1875 1876 PROC_LOCK_ASSERT(p, MA_OWNED); 1877 1878 p->p_nice = nice; 1879 FOREACH_THREAD_IN_PROC(p, td) { 1880 thread_lock(td); 1881 sched_priority(td); 1882 sched_prio(td, td->td_base_user_pri); 1883 thread_unlock(td); 1884 } 1885 } 1886 1887 /* 1888 * Record the sleep time for the interactivity scorer. 1889 */ 1890 void 1891 sched_sleep(struct thread *td, int prio) 1892 { 1893 1894 THREAD_LOCK_ASSERT(td, MA_OWNED); 1895 1896 td->td_slptick = ticks; 1897 if (TD_IS_SUSPENDED(td) || prio <= PSOCK) 1898 td->td_flags |= TDF_CANSWAP; 1899 if (static_boost == 1 && prio) 1900 sched_prio(td, prio); 1901 else if (static_boost && td->td_priority > static_boost) 1902 sched_prio(td, static_boost); 1903 } 1904 1905 /* 1906 * Schedule a thread to resume execution and record how long it voluntarily 1907 * slept. We also update the pctcpu, interactivity, and priority. 1908 */ 1909 void 1910 sched_wakeup(struct thread *td) 1911 { 1912 struct td_sched *ts; 1913 int slptick; 1914 1915 THREAD_LOCK_ASSERT(td, MA_OWNED); 1916 ts = td->td_sched; 1917 td->td_flags &= ~TDF_CANSWAP; 1918 /* 1919 * If we slept for more than a tick update our interactivity and 1920 * priority. 1921 */ 1922 slptick = td->td_slptick; 1923 td->td_slptick = 0; 1924 if (slptick && slptick != ticks) { 1925 u_int hzticks; 1926 1927 hzticks = (ticks - slptick) << SCHED_TICK_SHIFT; 1928 ts->ts_slptime += hzticks; 1929 sched_interact_update(td); 1930 sched_pctcpu_update(ts); 1931 } 1932 /* Reset the slice value after we sleep. */ 1933 ts->ts_slice = sched_slice; 1934 sched_add(td, SRQ_BORING); 1935 } 1936 1937 /* 1938 * Penalize the parent for creating a new child and initialize the child's 1939 * priority. 1940 */ 1941 void 1942 sched_fork(struct thread *td, struct thread *child) 1943 { 1944 THREAD_LOCK_ASSERT(td, MA_OWNED); 1945 sched_fork_thread(td, child); 1946 /* 1947 * Penalize the parent and child for forking. 1948 */ 1949 sched_interact_fork(child); 1950 sched_priority(child); 1951 td->td_sched->ts_runtime += tickincr; 1952 sched_interact_update(td); 1953 sched_priority(td); 1954 } 1955 1956 /* 1957 * Fork a new thread, may be within the same process. 1958 */ 1959 void 1960 sched_fork_thread(struct thread *td, struct thread *child) 1961 { 1962 struct td_sched *ts; 1963 struct td_sched *ts2; 1964 1965 THREAD_LOCK_ASSERT(td, MA_OWNED); 1966 /* 1967 * Initialize child. 1968 */ 1969 ts = td->td_sched; 1970 ts2 = child->td_sched; 1971 child->td_lock = TDQ_LOCKPTR(TDQ_SELF()); 1972 child->td_cpuset = cpuset_ref(td->td_cpuset); 1973 ts2->ts_cpu = ts->ts_cpu; 1974 ts2->ts_flags = 0; 1975 /* 1976 * Grab our parents cpu estimation information and priority. 1977 */ 1978 ts2->ts_ticks = ts->ts_ticks; 1979 ts2->ts_ltick = ts->ts_ltick; 1980 ts2->ts_ftick = ts->ts_ftick; 1981 child->td_user_pri = td->td_user_pri; 1982 child->td_base_user_pri = td->td_base_user_pri; 1983 /* 1984 * And update interactivity score. 1985 */ 1986 ts2->ts_slptime = ts->ts_slptime; 1987 ts2->ts_runtime = ts->ts_runtime; 1988 ts2->ts_slice = 1; /* Attempt to quickly learn interactivity. */ 1989 } 1990 1991 /* 1992 * Adjust the priority class of a thread. 1993 */ 1994 void 1995 sched_class(struct thread *td, int class) 1996 { 1997 1998 THREAD_LOCK_ASSERT(td, MA_OWNED); 1999 if (td->td_pri_class == class) 2000 return; 2001 td->td_pri_class = class; 2002 } 2003 2004 /* 2005 * Return some of the child's priority and interactivity to the parent. 2006 */ 2007 void 2008 sched_exit(struct proc *p, struct thread *child) 2009 { 2010 struct thread *td; 2011 2012 CTR3(KTR_SCHED, "sched_exit: %p(%s) prio %d", 2013 child, child->td_name, child->td_priority); 2014 2015 PROC_LOCK_ASSERT(p, MA_OWNED); 2016 td = FIRST_THREAD_IN_PROC(p); 2017 sched_exit_thread(td, child); 2018 } 2019 2020 /* 2021 * Penalize another thread for the time spent on this one. This helps to 2022 * worsen the priority and interactivity of processes which schedule batch 2023 * jobs such as make. This has little effect on the make process itself but 2024 * causes new processes spawned by it to receive worse scores immediately. 2025 */ 2026 void 2027 sched_exit_thread(struct thread *td, struct thread *child) 2028 { 2029 2030 CTR3(KTR_SCHED, "sched_exit_thread: %p(%s) prio %d", 2031 child, child->td_name, child->td_priority); 2032 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 2045 void 2046 sched_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 int flags; 2056 2057 flags = SW_INVOL | SW_PREEMPT; 2058 if (td->td_critnest > 1) 2059 td->td_owepreempt = 1; 2060 else if (TD_IS_IDLETHREAD(td)) 2061 mi_switch(flags | SWT_REMOTEWAKEIDLE, NULL); 2062 else 2063 mi_switch(flags | SWT_REMOTEPREEMPT, NULL); 2064 } 2065 thread_unlock(td); 2066 } 2067 2068 /* 2069 * Fix priorities on return to user-space. Priorities may be elevated due 2070 * to static priorities in msleep() or similar. 2071 */ 2072 void 2073 sched_userret(struct thread *td) 2074 { 2075 /* 2076 * XXX we cheat slightly on the locking here to avoid locking in 2077 * the usual case. Setting td_priority here is essentially an 2078 * incomplete workaround for not setting it properly elsewhere. 2079 * Now that some interrupt handlers are threads, not setting it 2080 * properly elsewhere can clobber it in the window between setting 2081 * it here and returning to user mode, so don't waste time setting 2082 * it perfectly here. 2083 */ 2084 KASSERT((td->td_flags & TDF_BORROWING) == 0, 2085 ("thread with borrowed priority returning to userland")); 2086 if (td->td_priority != td->td_user_pri) { 2087 thread_lock(td); 2088 td->td_priority = td->td_user_pri; 2089 td->td_base_pri = td->td_user_pri; 2090 tdq_setlowpri(TDQ_SELF(), td); 2091 thread_unlock(td); 2092 } 2093 } 2094 2095 /* 2096 * Handle a stathz tick. This is really only relevant for timeshare 2097 * threads. 2098 */ 2099 void 2100 sched_clock(struct thread *td) 2101 { 2102 struct tdq *tdq; 2103 struct td_sched *ts; 2104 2105 THREAD_LOCK_ASSERT(td, MA_OWNED); 2106 tdq = TDQ_SELF(); 2107 #ifdef SMP 2108 /* 2109 * We run the long term load balancer infrequently on the first cpu. 2110 */ 2111 if (balance_tdq == tdq) { 2112 if (balance_ticks && --balance_ticks == 0) 2113 sched_balance(); 2114 } 2115 #endif 2116 /* 2117 * Save the old switch count so we have a record of the last ticks 2118 * activity. Initialize the new switch count based on our load. 2119 * If there is some activity seed it to reflect that. 2120 */ 2121 tdq->tdq_oldswitchcnt = tdq->tdq_switchcnt; 2122 tdq->tdq_switchcnt = tdq->tdq_load; 2123 /* 2124 * Advance the insert index once for each tick to ensure that all 2125 * threads get a chance to run. 2126 */ 2127 if (tdq->tdq_idx == tdq->tdq_ridx) { 2128 tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS; 2129 if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx])) 2130 tdq->tdq_ridx = tdq->tdq_idx; 2131 } 2132 ts = td->td_sched; 2133 if (td->td_pri_class & PRI_FIFO_BIT) 2134 return; 2135 if (td->td_pri_class == PRI_TIMESHARE) { 2136 /* 2137 * We used a tick; charge it to the thread so 2138 * that we can compute our interactivity. 2139 */ 2140 td->td_sched->ts_runtime += tickincr; 2141 sched_interact_update(td); 2142 sched_priority(td); 2143 } 2144 /* 2145 * We used up one time slice. 2146 */ 2147 if (--ts->ts_slice > 0) 2148 return; 2149 /* 2150 * We're out of time, force a requeue at userret(). 2151 */ 2152 ts->ts_slice = sched_slice; 2153 td->td_flags |= TDF_NEEDRESCHED; 2154 } 2155 2156 /* 2157 * Called once per hz tick. Used for cpu utilization information. This 2158 * is easier than trying to scale based on stathz. 2159 */ 2160 void 2161 sched_tick(void) 2162 { 2163 struct td_sched *ts; 2164 2165 ts = curthread->td_sched; 2166 /* 2167 * Ticks is updated asynchronously on a single cpu. Check here to 2168 * avoid incrementing ts_ticks multiple times in a single tick. 2169 */ 2170 if (ts->ts_ltick == ticks) 2171 return; 2172 /* Adjust ticks for pctcpu */ 2173 ts->ts_ticks += 1 << SCHED_TICK_SHIFT; 2174 ts->ts_ltick = ticks; 2175 /* 2176 * Update if we've exceeded our desired tick threshhold by over one 2177 * second. 2178 */ 2179 if (ts->ts_ftick + SCHED_TICK_MAX < ts->ts_ltick) 2180 sched_pctcpu_update(ts); 2181 } 2182 2183 /* 2184 * Return whether the current CPU has runnable tasks. Used for in-kernel 2185 * cooperative idle threads. 2186 */ 2187 int 2188 sched_runnable(void) 2189 { 2190 struct tdq *tdq; 2191 int load; 2192 2193 load = 1; 2194 2195 tdq = TDQ_SELF(); 2196 if ((curthread->td_flags & TDF_IDLETD) != 0) { 2197 if (tdq->tdq_load > 0) 2198 goto out; 2199 } else 2200 if (tdq->tdq_load - 1 > 0) 2201 goto out; 2202 load = 0; 2203 out: 2204 return (load); 2205 } 2206 2207 /* 2208 * Choose the highest priority thread to run. The thread is removed from 2209 * the run-queue while running however the load remains. For SMP we set 2210 * the tdq in the global idle bitmask if it idles here. 2211 */ 2212 struct thread * 2213 sched_choose(void) 2214 { 2215 struct thread *td; 2216 struct tdq *tdq; 2217 2218 tdq = TDQ_SELF(); 2219 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2220 td = tdq_choose(tdq); 2221 if (td) { 2222 td->td_sched->ts_ltick = ticks; 2223 tdq_runq_rem(tdq, td); 2224 tdq->tdq_lowpri = td->td_priority; 2225 return (td); 2226 } 2227 tdq->tdq_lowpri = PRI_MAX_IDLE; 2228 return (PCPU_GET(idlethread)); 2229 } 2230 2231 /* 2232 * Set owepreempt if necessary. Preemption never happens directly in ULE, 2233 * we always request it once we exit a critical section. 2234 */ 2235 static inline void 2236 sched_setpreempt(struct thread *td) 2237 { 2238 struct thread *ctd; 2239 int cpri; 2240 int pri; 2241 2242 THREAD_LOCK_ASSERT(curthread, MA_OWNED); 2243 2244 ctd = curthread; 2245 pri = td->td_priority; 2246 cpri = ctd->td_priority; 2247 if (pri < cpri) 2248 ctd->td_flags |= TDF_NEEDRESCHED; 2249 if (panicstr != NULL || pri >= cpri || cold || TD_IS_INHIBITED(ctd)) 2250 return; 2251 if (!sched_shouldpreempt(pri, cpri, 0)) 2252 return; 2253 ctd->td_owepreempt = 1; 2254 } 2255 2256 /* 2257 * Add a thread to a thread queue. Select the appropriate runq and add the 2258 * thread to it. This is the internal function called when the tdq is 2259 * predetermined. 2260 */ 2261 void 2262 tdq_add(struct tdq *tdq, struct thread *td, int flags) 2263 { 2264 2265 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2266 KASSERT((td->td_inhibitors == 0), 2267 ("sched_add: trying to run inhibited thread")); 2268 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 2269 ("sched_add: bad thread state")); 2270 KASSERT(td->td_flags & TDF_INMEM, 2271 ("sched_add: thread swapped out")); 2272 2273 if (td->td_priority < tdq->tdq_lowpri) 2274 tdq->tdq_lowpri = td->td_priority; 2275 tdq_runq_add(tdq, td, flags); 2276 tdq_load_add(tdq, td); 2277 } 2278 2279 /* 2280 * Select the target thread queue and add a thread to it. Request 2281 * preemption or IPI a remote processor if required. 2282 */ 2283 void 2284 sched_add(struct thread *td, int flags) 2285 { 2286 struct tdq *tdq; 2287 #ifdef SMP 2288 int cpu; 2289 #endif 2290 CTR5(KTR_SCHED, "sched_add: %p(%s) prio %d by %p(%s)", 2291 td, td->td_name, td->td_priority, curthread, 2292 curthread->td_name); 2293 THREAD_LOCK_ASSERT(td, MA_OWNED); 2294 /* 2295 * Recalculate the priority before we select the target cpu or 2296 * run-queue. 2297 */ 2298 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 2299 sched_priority(td); 2300 #ifdef SMP 2301 /* 2302 * Pick the destination cpu and if it isn't ours transfer to the 2303 * target cpu. 2304 */ 2305 cpu = sched_pickcpu(td, flags); 2306 tdq = sched_setcpu(td, cpu, flags); 2307 tdq_add(tdq, td, flags); 2308 if (cpu != PCPU_GET(cpuid)) { 2309 tdq_notify(tdq, td); 2310 return; 2311 } 2312 #else 2313 tdq = TDQ_SELF(); 2314 TDQ_LOCK(tdq); 2315 /* 2316 * Now that the thread is moving to the run-queue, set the lock 2317 * to the scheduler's lock. 2318 */ 2319 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 2320 tdq_add(tdq, td, flags); 2321 #endif 2322 if (!(flags & SRQ_YIELDING)) 2323 sched_setpreempt(td); 2324 } 2325 2326 /* 2327 * Remove a thread from a run-queue without running it. This is used 2328 * when we're stealing a thread from a remote queue. Otherwise all threads 2329 * exit by calling sched_exit_thread() and sched_throw() themselves. 2330 */ 2331 void 2332 sched_rem(struct thread *td) 2333 { 2334 struct tdq *tdq; 2335 2336 CTR5(KTR_SCHED, "sched_rem: %p(%s) prio %d by %p(%s)", 2337 td, td->td_name, td->td_priority, curthread, 2338 curthread->td_name); 2339 tdq = TDQ_CPU(td->td_sched->ts_cpu); 2340 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2341 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2342 KASSERT(TD_ON_RUNQ(td), 2343 ("sched_rem: thread not on run queue")); 2344 tdq_runq_rem(tdq, td); 2345 tdq_load_rem(tdq, td); 2346 TD_SET_CAN_RUN(td); 2347 if (td->td_priority == tdq->tdq_lowpri) 2348 tdq_setlowpri(tdq, NULL); 2349 } 2350 2351 /* 2352 * Fetch cpu utilization information. Updates on demand. 2353 */ 2354 fixpt_t 2355 sched_pctcpu(struct thread *td) 2356 { 2357 fixpt_t pctcpu; 2358 struct td_sched *ts; 2359 2360 pctcpu = 0; 2361 ts = td->td_sched; 2362 if (ts == NULL) 2363 return (0); 2364 2365 thread_lock(td); 2366 if (ts->ts_ticks) { 2367 int rtick; 2368 2369 sched_pctcpu_update(ts); 2370 /* How many rtick per second ? */ 2371 rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz); 2372 pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT; 2373 } 2374 thread_unlock(td); 2375 2376 return (pctcpu); 2377 } 2378 2379 /* 2380 * Enforce affinity settings for a thread. Called after adjustments to 2381 * cpumask. 2382 */ 2383 void 2384 sched_affinity(struct thread *td) 2385 { 2386 #ifdef SMP 2387 struct td_sched *ts; 2388 int cpu; 2389 2390 THREAD_LOCK_ASSERT(td, MA_OWNED); 2391 ts = td->td_sched; 2392 if (THREAD_CAN_SCHED(td, ts->ts_cpu)) 2393 return; 2394 if (!TD_IS_RUNNING(td)) 2395 return; 2396 td->td_flags |= TDF_NEEDRESCHED; 2397 if (!THREAD_CAN_MIGRATE(td)) 2398 return; 2399 /* 2400 * Assign the new cpu and force a switch before returning to 2401 * userspace. If the target thread is not running locally send 2402 * an ipi to force the issue. 2403 */ 2404 cpu = ts->ts_cpu; 2405 ts->ts_cpu = sched_pickcpu(td, 0); 2406 if (cpu != PCPU_GET(cpuid)) 2407 ipi_selected(1 << cpu, IPI_PREEMPT); 2408 #endif 2409 } 2410 2411 /* 2412 * Bind a thread to a target cpu. 2413 */ 2414 void 2415 sched_bind(struct thread *td, int cpu) 2416 { 2417 struct td_sched *ts; 2418 2419 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 2420 ts = td->td_sched; 2421 if (ts->ts_flags & TSF_BOUND) 2422 sched_unbind(td); 2423 ts->ts_flags |= TSF_BOUND; 2424 sched_pin(); 2425 if (PCPU_GET(cpuid) == cpu) 2426 return; 2427 ts->ts_cpu = cpu; 2428 /* When we return from mi_switch we'll be on the correct cpu. */ 2429 mi_switch(SW_VOL, NULL); 2430 } 2431 2432 /* 2433 * Release a bound thread. 2434 */ 2435 void 2436 sched_unbind(struct thread *td) 2437 { 2438 struct td_sched *ts; 2439 2440 THREAD_LOCK_ASSERT(td, MA_OWNED); 2441 ts = td->td_sched; 2442 if ((ts->ts_flags & TSF_BOUND) == 0) 2443 return; 2444 ts->ts_flags &= ~TSF_BOUND; 2445 sched_unpin(); 2446 } 2447 2448 int 2449 sched_is_bound(struct thread *td) 2450 { 2451 THREAD_LOCK_ASSERT(td, MA_OWNED); 2452 return (td->td_sched->ts_flags & TSF_BOUND); 2453 } 2454 2455 /* 2456 * Basic yield call. 2457 */ 2458 void 2459 sched_relinquish(struct thread *td) 2460 { 2461 thread_lock(td); 2462 mi_switch(SW_VOL | SWT_RELINQUISH, NULL); 2463 thread_unlock(td); 2464 } 2465 2466 /* 2467 * Return the total system load. 2468 */ 2469 int 2470 sched_load(void) 2471 { 2472 #ifdef SMP 2473 int total; 2474 int i; 2475 2476 total = 0; 2477 for (i = 0; i <= mp_maxid; i++) 2478 total += TDQ_CPU(i)->tdq_sysload; 2479 return (total); 2480 #else 2481 return (TDQ_SELF()->tdq_sysload); 2482 #endif 2483 } 2484 2485 int 2486 sched_sizeof_proc(void) 2487 { 2488 return (sizeof(struct proc)); 2489 } 2490 2491 int 2492 sched_sizeof_thread(void) 2493 { 2494 return (sizeof(struct thread) + sizeof(struct td_sched)); 2495 } 2496 2497 /* 2498 * The actual idle process. 2499 */ 2500 void 2501 sched_idletd(void *dummy) 2502 { 2503 struct thread *td; 2504 struct tdq *tdq; 2505 int switchcnt; 2506 int i; 2507 2508 td = curthread; 2509 tdq = TDQ_SELF(); 2510 mtx_assert(&Giant, MA_NOTOWNED); 2511 /* ULE relies on preemption for idle interruption. */ 2512 for (;;) { 2513 tdq->tdq_idlestate = TDQ_RUNNING; 2514 #ifdef SMP 2515 if (tdq_idled(tdq) == 0) 2516 continue; 2517 #endif 2518 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2519 /* 2520 * If we're switching very frequently, spin while checking 2521 * for load rather than entering a low power state that 2522 * requires an IPI. 2523 */ 2524 if (switchcnt > sched_idlespinthresh) { 2525 for (i = 0; i < sched_idlespins; i++) { 2526 if (tdq->tdq_load) 2527 break; 2528 cpu_spinwait(); 2529 } 2530 } 2531 /* 2532 * We must set our state to IDLE before checking 2533 * tdq_load for the last time to avoid a race with 2534 * tdq_notify(). 2535 */ 2536 if (tdq->tdq_load == 0) { 2537 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2538 tdq->tdq_idlestate = TDQ_IDLE; 2539 if (tdq->tdq_load == 0) 2540 cpu_idle(switchcnt > 1); 2541 } 2542 if (tdq->tdq_load) { 2543 thread_lock(td); 2544 mi_switch(SW_VOL | SWT_IDLE, NULL); 2545 thread_unlock(td); 2546 } 2547 } 2548 } 2549 2550 /* 2551 * A CPU is entering for the first time or a thread is exiting. 2552 */ 2553 void 2554 sched_throw(struct thread *td) 2555 { 2556 struct thread *newtd; 2557 struct tdq *tdq; 2558 2559 tdq = TDQ_SELF(); 2560 if (td == NULL) { 2561 /* Correct spinlock nesting and acquire the correct lock. */ 2562 TDQ_LOCK(tdq); 2563 spinlock_exit(); 2564 } else { 2565 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2566 tdq_load_rem(tdq, td); 2567 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 2568 } 2569 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 2570 newtd = choosethread(); 2571 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 2572 PCPU_SET(switchtime, cpu_ticks()); 2573 PCPU_SET(switchticks, ticks); 2574 cpu_throw(td, newtd); /* doesn't return */ 2575 } 2576 2577 /* 2578 * This is called from fork_exit(). Just acquire the correct locks and 2579 * let fork do the rest of the work. 2580 */ 2581 void 2582 sched_fork_exit(struct thread *td) 2583 { 2584 struct td_sched *ts; 2585 struct tdq *tdq; 2586 int cpuid; 2587 2588 /* 2589 * Finish setting up thread glue so that it begins execution in a 2590 * non-nested critical section with the scheduler lock held. 2591 */ 2592 cpuid = PCPU_GET(cpuid); 2593 tdq = TDQ_CPU(cpuid); 2594 ts = td->td_sched; 2595 if (TD_IS_IDLETHREAD(td)) 2596 td->td_lock = TDQ_LOCKPTR(tdq); 2597 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2598 td->td_oncpu = cpuid; 2599 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 2600 lock_profile_obtain_lock_success( 2601 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 2602 } 2603 2604 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0, "Scheduler"); 2605 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0, 2606 "Scheduler name"); 2607 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, 2608 "Slice size for timeshare threads"); 2609 SYSCTL_INT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0, 2610 "Interactivity score threshold"); 2611 SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW, &preempt_thresh, 2612 0,"Min priority for preemption, lower priorities have greater precedence"); 2613 SYSCTL_INT(_kern_sched, OID_AUTO, static_boost, CTLFLAG_RW, &static_boost, 2614 0,"Controls whether static kernel priorities are assigned to sleeping threads."); 2615 SYSCTL_INT(_kern_sched, OID_AUTO, idlespins, CTLFLAG_RW, &sched_idlespins, 2616 0,"Number of times idle will spin waiting for new work."); 2617 SYSCTL_INT(_kern_sched, OID_AUTO, idlespinthresh, CTLFLAG_RW, &sched_idlespinthresh, 2618 0,"Threshold before we will permit idle spinning."); 2619 #ifdef SMP 2620 SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0, 2621 "Number of hz ticks to keep thread affinity for"); 2622 SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0, 2623 "Enables the long-term load balancer"); 2624 SYSCTL_INT(_kern_sched, OID_AUTO, balance_interval, CTLFLAG_RW, 2625 &balance_interval, 0, 2626 "Average frequency in stathz ticks to run the long-term balancer"); 2627 SYSCTL_INT(_kern_sched, OID_AUTO, steal_htt, CTLFLAG_RW, &steal_htt, 0, 2628 "Steals work from another hyper-threaded core on idle"); 2629 SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0, 2630 "Attempts to steal work from other cores before idling"); 2631 SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0, 2632 "Minimum load on remote cpu before we'll steal"); 2633 #endif 2634 2635 /* ps compat. All cpu percentages from ULE are weighted. */ 2636 static int ccpu = 0; 2637 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 2638