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