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 it's 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 #ifdef KTRACE 63 #include <sys/uio.h> 64 #include <sys/ktrace.h> 65 #endif 66 67 #ifdef HWPMC_HOOKS 68 #include <sys/pmckern.h> 69 #endif 70 71 #include <machine/cpu.h> 72 #include <machine/smp.h> 73 74 #ifndef PREEMPTION 75 #error "SCHED_ULE requires options PREEMPTION" 76 #endif 77 78 #define KTR_ULE 0 79 80 /* 81 * Thread scheduler specific section. All fields are protected 82 * by the thread lock. 83 */ 84 struct td_sched { 85 TAILQ_ENTRY(td_sched) ts_procq; /* Run queue. */ 86 struct thread *ts_thread; /* Active associated thread. */ 87 struct runq *ts_runq; /* Run-queue we're queued on. */ 88 short ts_flags; /* TSF_* flags. */ 89 u_char ts_rqindex; /* Run queue index. */ 90 u_char ts_cpu; /* CPU that we have affinity for. */ 91 int ts_slptick; /* Tick when we went to sleep. */ 92 int ts_slice; /* Ticks of slice remaining. */ 93 u_int ts_slptime; /* Number of ticks we vol. slept */ 94 u_int ts_runtime; /* Number of ticks we were running */ 95 /* The following variables are only used for pctcpu calculation */ 96 int ts_ltick; /* Last tick that we were running on */ 97 int ts_ftick; /* First tick that we were running on */ 98 int ts_ticks; /* Tick count */ 99 #ifdef SMP 100 int ts_rltick; /* Real last tick, for affinity. */ 101 #endif 102 }; 103 /* flags kept in ts_flags */ 104 #define TSF_BOUND 0x0001 /* Thread can not migrate. */ 105 #define TSF_XFERABLE 0x0002 /* Thread was added as transferable. */ 106 107 static struct td_sched td_sched0; 108 109 /* 110 * Cpu percentage computation macros and defines. 111 * 112 * SCHED_TICK_SECS: Number of seconds to average the cpu usage across. 113 * SCHED_TICK_TARG: Number of hz ticks to average the cpu usage across. 114 * SCHED_TICK_MAX: Maximum number of ticks before scaling back. 115 * SCHED_TICK_SHIFT: Shift factor to avoid rounding away results. 116 * SCHED_TICK_HZ: Compute the number of hz ticks for a given ticks count. 117 * SCHED_TICK_TOTAL: Gives the amount of time we've been recording ticks. 118 */ 119 #define SCHED_TICK_SECS 10 120 #define SCHED_TICK_TARG (hz * SCHED_TICK_SECS) 121 #define SCHED_TICK_MAX (SCHED_TICK_TARG + hz) 122 #define SCHED_TICK_SHIFT 10 123 #define SCHED_TICK_HZ(ts) ((ts)->ts_ticks >> SCHED_TICK_SHIFT) 124 #define SCHED_TICK_TOTAL(ts) (max((ts)->ts_ltick - (ts)->ts_ftick, hz)) 125 126 /* 127 * These macros determine priorities for non-interactive threads. They are 128 * assigned a priority based on their recent cpu utilization as expressed 129 * by the ratio of ticks to the tick total. NHALF priorities at the start 130 * and end of the MIN to MAX timeshare range are only reachable with negative 131 * or positive nice respectively. 132 * 133 * PRI_RANGE: Priority range for utilization dependent priorities. 134 * PRI_NRESV: Number of nice values. 135 * PRI_TICKS: Compute a priority in PRI_RANGE from the ticks count and total. 136 * PRI_NICE: Determines the part of the priority inherited from nice. 137 */ 138 #define SCHED_PRI_NRESV (PRIO_MAX - PRIO_MIN) 139 #define SCHED_PRI_NHALF (SCHED_PRI_NRESV / 2) 140 #define SCHED_PRI_MIN (PRI_MIN_TIMESHARE + SCHED_PRI_NHALF) 141 #define SCHED_PRI_MAX (PRI_MAX_TIMESHARE - SCHED_PRI_NHALF) 142 #define SCHED_PRI_RANGE (SCHED_PRI_MAX - SCHED_PRI_MIN) 143 #define SCHED_PRI_TICKS(ts) \ 144 (SCHED_TICK_HZ((ts)) / \ 145 (roundup(SCHED_TICK_TOTAL((ts)), SCHED_PRI_RANGE) / SCHED_PRI_RANGE)) 146 #define SCHED_PRI_NICE(nice) (nice) 147 148 /* 149 * These determine the interactivity of a process. Interactivity differs from 150 * cpu utilization in that it expresses the voluntary time slept vs time ran 151 * while cpu utilization includes all time not running. This more accurately 152 * models the intent of the thread. 153 * 154 * SLP_RUN_MAX: Maximum amount of sleep time + run time we'll accumulate 155 * before throttling back. 156 * SLP_RUN_FORK: Maximum slp+run time to inherit at fork time. 157 * INTERACT_MAX: Maximum interactivity value. Smaller is better. 158 * INTERACT_THRESH: Threshhold for placement on the current runq. 159 */ 160 #define SCHED_SLP_RUN_MAX ((hz * 5) << SCHED_TICK_SHIFT) 161 #define SCHED_SLP_RUN_FORK ((hz / 2) << SCHED_TICK_SHIFT) 162 #define SCHED_INTERACT_MAX (100) 163 #define SCHED_INTERACT_HALF (SCHED_INTERACT_MAX / 2) 164 #define SCHED_INTERACT_THRESH (30) 165 166 /* 167 * tickincr: Converts a stathz tick into a hz domain scaled by 168 * the shift factor. Without the shift the error rate 169 * due to rounding would be unacceptably high. 170 * realstathz: stathz is sometimes 0 and run off of hz. 171 * sched_slice: Runtime of each thread before rescheduling. 172 * preempt_thresh: Priority threshold for preemption and remote IPIs. 173 */ 174 static int sched_interact = SCHED_INTERACT_THRESH; 175 static int realstathz; 176 static int tickincr; 177 static int sched_slice; 178 static int preempt_thresh = PRI_MIN_KERN; 179 180 /* 181 * tdq - per processor runqs and statistics. All fields are protected by the 182 * tdq_lock. The load and lowpri may be accessed without to avoid excess 183 * locking in sched_pickcpu(); 184 */ 185 struct tdq { 186 struct mtx tdq_lock; /* Protects all fields below. */ 187 struct runq tdq_realtime; /* real-time run queue. */ 188 struct runq tdq_timeshare; /* timeshare run queue. */ 189 struct runq tdq_idle; /* Queue of IDLE threads. */ 190 int tdq_load; /* Aggregate load. */ 191 u_char tdq_idx; /* Current insert index. */ 192 u_char tdq_ridx; /* Current removal index. */ 193 #ifdef SMP 194 u_char tdq_lowpri; /* Lowest priority thread. */ 195 int tdq_transferable; /* Transferable thread count. */ 196 LIST_ENTRY(tdq) tdq_siblings; /* Next in tdq group. */ 197 struct tdq_group *tdq_group; /* Our processor group. */ 198 #else 199 int tdq_sysload; /* For loadavg, !ITHD load. */ 200 #endif 201 char tdq_name[16]; /* lock name. */ 202 } __aligned(64); 203 204 205 #ifdef SMP 206 /* 207 * tdq groups are groups of processors which can cheaply share threads. When 208 * one processor in the group goes idle it will check the runqs of the other 209 * processors in its group prior to halting and waiting for an interrupt. 210 * These groups are suitable for SMT (Symetric Multi-Threading) and not NUMA. 211 * In a numa environment we'd want an idle bitmap per group and a two tiered 212 * load balancer. 213 */ 214 struct tdq_group { 215 int tdg_cpus; /* Count of CPUs in this tdq group. */ 216 cpumask_t tdg_cpumask; /* Mask of cpus in this group. */ 217 cpumask_t tdg_idlemask; /* Idle cpus in this group. */ 218 cpumask_t tdg_mask; /* Bit mask for first cpu. */ 219 int tdg_load; /* Total load of this group. */ 220 int tdg_transferable; /* Transferable load of this group. */ 221 LIST_HEAD(, tdq) tdg_members; /* Linked list of all members. */ 222 } __aligned(64); 223 224 #define SCHED_AFFINITY_DEFAULT (max(1, hz / 300)) 225 #define SCHED_AFFINITY(ts) ((ts)->ts_rltick > ticks - affinity) 226 227 /* 228 * Run-time tunables. 229 */ 230 static int rebalance = 1; 231 static int balance_secs = 1; 232 static int pick_pri = 1; 233 static int affinity; 234 static int tryself = 1; 235 static int steal_htt = 0; 236 static int steal_idle = 1; 237 static int steal_thresh = 2; 238 static int topology = 0; 239 240 /* 241 * One thread queue per processor. 242 */ 243 static volatile cpumask_t tdq_idle; 244 static int tdg_maxid; 245 static struct tdq tdq_cpu[MAXCPU]; 246 static struct tdq_group tdq_groups[MAXCPU]; 247 static struct callout balco; 248 static struct callout gbalco; 249 250 #define TDQ_SELF() (&tdq_cpu[PCPU_GET(cpuid)]) 251 #define TDQ_CPU(x) (&tdq_cpu[(x)]) 252 #define TDQ_ID(x) ((x) - tdq_cpu) 253 #define TDQ_GROUP(x) (&tdq_groups[(x)]) 254 #else /* !SMP */ 255 static struct tdq tdq_cpu; 256 257 #define TDQ_ID(x) (0) 258 #define TDQ_SELF() (&tdq_cpu) 259 #define TDQ_CPU(x) (&tdq_cpu) 260 #endif 261 262 #define TDQ_LOCK_ASSERT(t, type) mtx_assert(TDQ_LOCKPTR((t)), (type)) 263 #define TDQ_LOCK(t) mtx_lock_spin(TDQ_LOCKPTR((t))) 264 #define TDQ_LOCK_FLAGS(t, f) mtx_lock_spin_flags(TDQ_LOCKPTR((t)), (f)) 265 #define TDQ_UNLOCK(t) mtx_unlock_spin(TDQ_LOCKPTR((t))) 266 #define TDQ_LOCKPTR(t) (&(t)->tdq_lock) 267 268 static void sched_priority(struct thread *); 269 static void sched_thread_priority(struct thread *, u_char); 270 static int sched_interact_score(struct thread *); 271 static void sched_interact_update(struct thread *); 272 static void sched_interact_fork(struct thread *); 273 static void sched_pctcpu_update(struct td_sched *); 274 275 /* Operations on per processor queues */ 276 static struct td_sched * tdq_choose(struct tdq *); 277 static void tdq_setup(struct tdq *); 278 static void tdq_load_add(struct tdq *, struct td_sched *); 279 static void tdq_load_rem(struct tdq *, struct td_sched *); 280 static __inline void tdq_runq_add(struct tdq *, struct td_sched *, int); 281 static __inline void tdq_runq_rem(struct tdq *, struct td_sched *); 282 void tdq_print(int cpu); 283 static void runq_print(struct runq *rq); 284 static void tdq_add(struct tdq *, struct thread *, int); 285 #ifdef SMP 286 static void tdq_move(struct tdq *, struct tdq *); 287 static int tdq_idled(struct tdq *); 288 static void tdq_notify(struct td_sched *); 289 static struct td_sched *tdq_steal(struct tdq *, int); 290 static struct td_sched *runq_steal(struct runq *); 291 static int sched_pickcpu(struct td_sched *, int); 292 static void sched_balance(void *); 293 static void sched_balance_groups(void *); 294 static void sched_balance_group(struct tdq_group *); 295 static void sched_balance_pair(struct tdq *, struct tdq *); 296 static inline struct tdq *sched_setcpu(struct td_sched *, int, int); 297 static inline struct mtx *thread_block_switch(struct thread *); 298 static inline void thread_unblock_switch(struct thread *, struct mtx *); 299 300 #define THREAD_CAN_MIGRATE(td) ((td)->td_pinned == 0) 301 #endif 302 303 static void sched_setup(void *dummy); 304 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL) 305 306 static void sched_initticks(void *dummy); 307 SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks, NULL) 308 309 /* 310 * Print the threads waiting on a run-queue. 311 */ 312 static void 313 runq_print(struct runq *rq) 314 { 315 struct rqhead *rqh; 316 struct td_sched *ts; 317 int pri; 318 int j; 319 int i; 320 321 for (i = 0; i < RQB_LEN; i++) { 322 printf("\t\trunq bits %d 0x%zx\n", 323 i, rq->rq_status.rqb_bits[i]); 324 for (j = 0; j < RQB_BPW; j++) 325 if (rq->rq_status.rqb_bits[i] & (1ul << j)) { 326 pri = j + (i << RQB_L2BPW); 327 rqh = &rq->rq_queues[pri]; 328 TAILQ_FOREACH(ts, rqh, ts_procq) { 329 printf("\t\t\ttd %p(%s) priority %d rqindex %d pri %d\n", 330 ts->ts_thread, ts->ts_thread->td_proc->p_comm, ts->ts_thread->td_priority, ts->ts_rqindex, pri); 331 } 332 } 333 } 334 } 335 336 /* 337 * Print the status of a per-cpu thread queue. Should be a ddb show cmd. 338 */ 339 void 340 tdq_print(int cpu) 341 { 342 struct tdq *tdq; 343 344 tdq = TDQ_CPU(cpu); 345 346 printf("tdq:\n"); 347 printf("\tlockptr %p\n", TDQ_LOCKPTR(tdq)); 348 printf("\tlock name %s\n", tdq->tdq_name); 349 printf("\tload: %d\n", tdq->tdq_load); 350 printf("\ttimeshare idx: %d\n", tdq->tdq_idx); 351 printf("\ttimeshare ridx: %d\n", tdq->tdq_ridx); 352 printf("\trealtime runq:\n"); 353 runq_print(&tdq->tdq_realtime); 354 printf("\ttimeshare runq:\n"); 355 runq_print(&tdq->tdq_timeshare); 356 printf("\tidle runq:\n"); 357 runq_print(&tdq->tdq_idle); 358 #ifdef SMP 359 printf("\tload transferable: %d\n", tdq->tdq_transferable); 360 printf("\tlowest priority: %d\n", tdq->tdq_lowpri); 361 #endif 362 } 363 364 #define TS_RQ_PPQ (((PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE) + 1) / RQ_NQS) 365 /* 366 * Add a thread to the actual run-queue. Keeps transferable counts up to 367 * date with what is actually on the run-queue. Selects the correct 368 * queue position for timeshare threads. 369 */ 370 static __inline void 371 tdq_runq_add(struct tdq *tdq, struct td_sched *ts, int flags) 372 { 373 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 374 THREAD_LOCK_ASSERT(ts->ts_thread, MA_OWNED); 375 #ifdef SMP 376 if (THREAD_CAN_MIGRATE(ts->ts_thread)) { 377 tdq->tdq_transferable++; 378 tdq->tdq_group->tdg_transferable++; 379 ts->ts_flags |= TSF_XFERABLE; 380 } 381 #endif 382 if (ts->ts_runq == &tdq->tdq_timeshare) { 383 u_char pri; 384 385 pri = ts->ts_thread->td_priority; 386 KASSERT(pri <= PRI_MAX_TIMESHARE && pri >= PRI_MIN_TIMESHARE, 387 ("Invalid priority %d on timeshare runq", pri)); 388 /* 389 * This queue contains only priorities between MIN and MAX 390 * realtime. Use the whole queue to represent these values. 391 */ 392 if ((flags & SRQ_BORROWING) == 0) { 393 pri = (pri - PRI_MIN_TIMESHARE) / TS_RQ_PPQ; 394 pri = (pri + tdq->tdq_idx) % RQ_NQS; 395 /* 396 * This effectively shortens the queue by one so we 397 * can have a one slot difference between idx and 398 * ridx while we wait for threads to drain. 399 */ 400 if (tdq->tdq_ridx != tdq->tdq_idx && 401 pri == tdq->tdq_ridx) 402 pri = (unsigned char)(pri - 1) % RQ_NQS; 403 } else 404 pri = tdq->tdq_ridx; 405 runq_add_pri(ts->ts_runq, ts, pri, flags); 406 } else 407 runq_add(ts->ts_runq, ts, flags); 408 } 409 410 /* 411 * Remove a thread from a run-queue. This typically happens when a thread 412 * is selected to run. Running threads are not on the queue and the 413 * transferable count does not reflect them. 414 */ 415 static __inline void 416 tdq_runq_rem(struct tdq *tdq, struct td_sched *ts) 417 { 418 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 419 KASSERT(ts->ts_runq != NULL, 420 ("tdq_runq_remove: thread %p null ts_runq", ts->ts_thread)); 421 #ifdef SMP 422 if (ts->ts_flags & TSF_XFERABLE) { 423 tdq->tdq_transferable--; 424 tdq->tdq_group->tdg_transferable--; 425 ts->ts_flags &= ~TSF_XFERABLE; 426 } 427 #endif 428 if (ts->ts_runq == &tdq->tdq_timeshare) { 429 if (tdq->tdq_idx != tdq->tdq_ridx) 430 runq_remove_idx(ts->ts_runq, ts, &tdq->tdq_ridx); 431 else 432 runq_remove_idx(ts->ts_runq, ts, NULL); 433 /* 434 * For timeshare threads we update the priority here so 435 * the priority reflects the time we've been sleeping. 436 */ 437 ts->ts_ltick = ticks; 438 sched_pctcpu_update(ts); 439 sched_priority(ts->ts_thread); 440 } else 441 runq_remove(ts->ts_runq, ts); 442 } 443 444 /* 445 * Load is maintained for all threads RUNNING and ON_RUNQ. Add the load 446 * for this thread to the referenced thread queue. 447 */ 448 static void 449 tdq_load_add(struct tdq *tdq, struct td_sched *ts) 450 { 451 int class; 452 453 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 454 THREAD_LOCK_ASSERT(ts->ts_thread, MA_OWNED); 455 class = PRI_BASE(ts->ts_thread->td_pri_class); 456 tdq->tdq_load++; 457 CTR2(KTR_SCHED, "cpu %jd load: %d", TDQ_ID(tdq), tdq->tdq_load); 458 if (class != PRI_ITHD && 459 (ts->ts_thread->td_proc->p_flag & P_NOLOAD) == 0) 460 #ifdef SMP 461 tdq->tdq_group->tdg_load++; 462 #else 463 tdq->tdq_sysload++; 464 #endif 465 } 466 467 /* 468 * Remove the load from a thread that is transitioning to a sleep state or 469 * exiting. 470 */ 471 static void 472 tdq_load_rem(struct tdq *tdq, struct td_sched *ts) 473 { 474 int class; 475 476 THREAD_LOCK_ASSERT(ts->ts_thread, MA_OWNED); 477 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 478 class = PRI_BASE(ts->ts_thread->td_pri_class); 479 if (class != PRI_ITHD && 480 (ts->ts_thread->td_proc->p_flag & P_NOLOAD) == 0) 481 #ifdef SMP 482 tdq->tdq_group->tdg_load--; 483 #else 484 tdq->tdq_sysload--; 485 #endif 486 KASSERT(tdq->tdq_load != 0, 487 ("tdq_load_rem: Removing with 0 load on queue %d", (int)TDQ_ID(tdq))); 488 tdq->tdq_load--; 489 CTR1(KTR_SCHED, "load: %d", tdq->tdq_load); 490 ts->ts_runq = NULL; 491 } 492 493 #ifdef SMP 494 /* 495 * sched_balance is a simple CPU load balancing algorithm. It operates by 496 * finding the least loaded and most loaded cpu and equalizing their load 497 * by migrating some processes. 498 * 499 * Dealing only with two CPUs at a time has two advantages. Firstly, most 500 * installations will only have 2 cpus. Secondly, load balancing too much at 501 * once can have an unpleasant effect on the system. The scheduler rarely has 502 * enough information to make perfect decisions. So this algorithm chooses 503 * simplicity and more gradual effects on load in larger systems. 504 * 505 */ 506 static void 507 sched_balance(void *arg) 508 { 509 struct tdq_group *high; 510 struct tdq_group *low; 511 struct tdq_group *tdg; 512 int cnt; 513 int i; 514 515 callout_reset(&balco, max(hz / 2, random() % (hz * balance_secs)), 516 sched_balance, NULL); 517 if (smp_started == 0 || rebalance == 0) 518 return; 519 low = high = NULL; 520 i = random() % (tdg_maxid + 1); 521 for (cnt = 0; cnt <= tdg_maxid; cnt++) { 522 tdg = TDQ_GROUP(i); 523 /* 524 * Find the CPU with the highest load that has some 525 * threads to transfer. 526 */ 527 if ((high == NULL || tdg->tdg_load > high->tdg_load) 528 && tdg->tdg_transferable) 529 high = tdg; 530 if (low == NULL || tdg->tdg_load < low->tdg_load) 531 low = tdg; 532 if (++i > tdg_maxid) 533 i = 0; 534 } 535 if (low != NULL && high != NULL && high != low) 536 sched_balance_pair(LIST_FIRST(&high->tdg_members), 537 LIST_FIRST(&low->tdg_members)); 538 } 539 540 /* 541 * Balance load between CPUs in a group. Will only migrate within the group. 542 */ 543 static void 544 sched_balance_groups(void *arg) 545 { 546 int i; 547 548 callout_reset(&gbalco, max(hz / 2, random() % (hz * balance_secs)), 549 sched_balance_groups, NULL); 550 if (smp_started == 0 || rebalance == 0) 551 return; 552 for (i = 0; i <= tdg_maxid; i++) 553 sched_balance_group(TDQ_GROUP(i)); 554 } 555 556 /* 557 * Finds the greatest imbalance between two tdqs in a group. 558 */ 559 static void 560 sched_balance_group(struct tdq_group *tdg) 561 { 562 struct tdq *tdq; 563 struct tdq *high; 564 struct tdq *low; 565 int load; 566 567 if (tdg->tdg_transferable == 0) 568 return; 569 low = NULL; 570 high = NULL; 571 LIST_FOREACH(tdq, &tdg->tdg_members, tdq_siblings) { 572 load = tdq->tdq_load; 573 if (high == NULL || load > high->tdq_load) 574 high = tdq; 575 if (low == NULL || load < low->tdq_load) 576 low = tdq; 577 } 578 if (high != NULL && low != NULL && high != low) 579 sched_balance_pair(high, low); 580 } 581 582 /* 583 * Lock two thread queues using their address to maintain lock order. 584 */ 585 static void 586 tdq_lock_pair(struct tdq *one, struct tdq *two) 587 { 588 if (one < two) { 589 TDQ_LOCK(one); 590 TDQ_LOCK_FLAGS(two, MTX_DUPOK); 591 } else { 592 TDQ_LOCK(two); 593 TDQ_LOCK_FLAGS(one, MTX_DUPOK); 594 } 595 } 596 597 /* 598 * Transfer load between two imbalanced thread queues. 599 */ 600 static void 601 sched_balance_pair(struct tdq *high, struct tdq *low) 602 { 603 int transferable; 604 int high_load; 605 int low_load; 606 int move; 607 int diff; 608 int i; 609 610 tdq_lock_pair(high, low); 611 /* 612 * If we're transfering within a group we have to use this specific 613 * tdq's transferable count, otherwise we can steal from other members 614 * of the group. 615 */ 616 if (high->tdq_group == low->tdq_group) { 617 transferable = high->tdq_transferable; 618 high_load = high->tdq_load; 619 low_load = low->tdq_load; 620 } else { 621 transferable = high->tdq_group->tdg_transferable; 622 high_load = high->tdq_group->tdg_load; 623 low_load = low->tdq_group->tdg_load; 624 } 625 /* 626 * Determine what the imbalance is and then adjust that to how many 627 * threads we actually have to give up (transferable). 628 */ 629 if (transferable != 0) { 630 diff = high_load - low_load; 631 move = diff / 2; 632 if (diff & 0x1) 633 move++; 634 move = min(move, transferable); 635 for (i = 0; i < move; i++) 636 tdq_move(high, low); 637 } 638 TDQ_UNLOCK(high); 639 TDQ_UNLOCK(low); 640 return; 641 } 642 643 /* 644 * Move a thread from one thread queue to another. 645 */ 646 static void 647 tdq_move(struct tdq *from, struct tdq *to) 648 { 649 struct td_sched *ts; 650 struct thread *td; 651 struct tdq *tdq; 652 int cpu; 653 654 tdq = from; 655 cpu = TDQ_ID(to); 656 ts = tdq_steal(tdq, 1); 657 if (ts == NULL) { 658 struct tdq_group *tdg; 659 660 tdg = tdq->tdq_group; 661 LIST_FOREACH(tdq, &tdg->tdg_members, tdq_siblings) { 662 if (tdq == from || tdq->tdq_transferable == 0) 663 continue; 664 ts = tdq_steal(tdq, 1); 665 break; 666 } 667 if (ts == NULL) 668 return; 669 } 670 if (tdq == to) 671 return; 672 td = ts->ts_thread; 673 /* 674 * Although the run queue is locked the thread may be blocked. Lock 675 * it to clear this. 676 */ 677 thread_lock(td); 678 /* Drop recursive lock on from. */ 679 TDQ_UNLOCK(from); 680 sched_rem(td); 681 ts->ts_cpu = cpu; 682 td->td_lock = TDQ_LOCKPTR(to); 683 tdq_add(to, td, SRQ_YIELDING); 684 tdq_notify(ts); 685 } 686 687 /* 688 * This tdq has idled. Try to steal a thread from another cpu and switch 689 * to it. 690 */ 691 static int 692 tdq_idled(struct tdq *tdq) 693 { 694 struct tdq_group *tdg; 695 struct tdq *steal; 696 struct td_sched *ts; 697 struct thread *td; 698 int highload; 699 int highcpu; 700 int load; 701 int cpu; 702 703 /* We don't want to be preempted while we're iterating over tdqs */ 704 spinlock_enter(); 705 tdg = tdq->tdq_group; 706 /* 707 * If we're in a cpu group, try and steal threads from another cpu in 708 * the group before idling. 709 */ 710 if (steal_htt && tdg->tdg_cpus > 1 && tdg->tdg_transferable) { 711 LIST_FOREACH(steal, &tdg->tdg_members, tdq_siblings) { 712 if (steal == tdq || steal->tdq_transferable == 0) 713 continue; 714 TDQ_LOCK(steal); 715 ts = tdq_steal(steal, 0); 716 if (ts) 717 goto steal; 718 TDQ_UNLOCK(steal); 719 } 720 } 721 for (;;) { 722 if (steal_idle == 0) 723 break; 724 highcpu = 0; 725 highload = 0; 726 for (cpu = 0; cpu <= mp_maxid; cpu++) { 727 if (CPU_ABSENT(cpu)) 728 continue; 729 steal = TDQ_CPU(cpu); 730 load = TDQ_CPU(cpu)->tdq_transferable; 731 if (load < highload) 732 continue; 733 highload = load; 734 highcpu = cpu; 735 } 736 if (highload < steal_thresh) 737 break; 738 steal = TDQ_CPU(highcpu); 739 TDQ_LOCK(steal); 740 if (steal->tdq_transferable >= steal_thresh && 741 (ts = tdq_steal(steal, 1)) != NULL) 742 goto steal; 743 TDQ_UNLOCK(steal); 744 break; 745 } 746 spinlock_exit(); 747 return (1); 748 steal: 749 td = ts->ts_thread; 750 thread_lock(td); 751 spinlock_exit(); 752 MPASS(td->td_lock == TDQ_LOCKPTR(steal)); 753 TDQ_UNLOCK(steal); 754 sched_rem(td); 755 sched_setcpu(ts, PCPU_GET(cpuid), SRQ_YIELDING); 756 tdq_add(tdq, td, SRQ_YIELDING); 757 MPASS(td->td_lock == curthread->td_lock); 758 mi_switch(SW_VOL, NULL); 759 thread_unlock(curthread); 760 761 return (0); 762 } 763 764 /* 765 * Notify a remote cpu of new work. Sends an IPI if criteria are met. 766 */ 767 static void 768 tdq_notify(struct td_sched *ts) 769 { 770 struct thread *ctd; 771 struct pcpu *pcpu; 772 int cpri; 773 int pri; 774 int cpu; 775 776 cpu = ts->ts_cpu; 777 pri = ts->ts_thread->td_priority; 778 pcpu = pcpu_find(cpu); 779 ctd = pcpu->pc_curthread; 780 cpri = ctd->td_priority; 781 782 /* 783 * If our priority is not better than the current priority there is 784 * nothing to do. 785 */ 786 if (pri > cpri) 787 return; 788 /* 789 * Always IPI idle. 790 */ 791 if (cpri > PRI_MIN_IDLE) 792 goto sendipi; 793 /* 794 * If we're realtime or better and there is timeshare or worse running 795 * send an IPI. 796 */ 797 if (pri < PRI_MAX_REALTIME && cpri > PRI_MAX_REALTIME) 798 goto sendipi; 799 /* 800 * Otherwise only IPI if we exceed the threshold. 801 */ 802 if (pri > preempt_thresh) 803 return; 804 sendipi: 805 ctd->td_flags |= TDF_NEEDRESCHED; 806 ipi_selected(1 << cpu, IPI_PREEMPT); 807 } 808 809 /* 810 * Steals load from a timeshare queue. Honors the rotating queue head 811 * index. 812 */ 813 static struct td_sched * 814 runq_steal_from(struct runq *rq, u_char start) 815 { 816 struct td_sched *ts; 817 struct rqbits *rqb; 818 struct rqhead *rqh; 819 int first; 820 int bit; 821 int pri; 822 int i; 823 824 rqb = &rq->rq_status; 825 bit = start & (RQB_BPW -1); 826 pri = 0; 827 first = 0; 828 again: 829 for (i = RQB_WORD(start); i < RQB_LEN; bit = 0, i++) { 830 if (rqb->rqb_bits[i] == 0) 831 continue; 832 if (bit != 0) { 833 for (pri = bit; pri < RQB_BPW; pri++) 834 if (rqb->rqb_bits[i] & (1ul << pri)) 835 break; 836 if (pri >= RQB_BPW) 837 continue; 838 } else 839 pri = RQB_FFS(rqb->rqb_bits[i]); 840 pri += (i << RQB_L2BPW); 841 rqh = &rq->rq_queues[pri]; 842 TAILQ_FOREACH(ts, rqh, ts_procq) { 843 if (first && THREAD_CAN_MIGRATE(ts->ts_thread)) 844 return (ts); 845 first = 1; 846 } 847 } 848 if (start != 0) { 849 start = 0; 850 goto again; 851 } 852 853 return (NULL); 854 } 855 856 /* 857 * Steals load from a standard linear queue. 858 */ 859 static struct td_sched * 860 runq_steal(struct runq *rq) 861 { 862 struct rqhead *rqh; 863 struct rqbits *rqb; 864 struct td_sched *ts; 865 int word; 866 int bit; 867 868 rqb = &rq->rq_status; 869 for (word = 0; word < RQB_LEN; word++) { 870 if (rqb->rqb_bits[word] == 0) 871 continue; 872 for (bit = 0; bit < RQB_BPW; bit++) { 873 if ((rqb->rqb_bits[word] & (1ul << bit)) == 0) 874 continue; 875 rqh = &rq->rq_queues[bit + (word << RQB_L2BPW)]; 876 TAILQ_FOREACH(ts, rqh, ts_procq) 877 if (THREAD_CAN_MIGRATE(ts->ts_thread)) 878 return (ts); 879 } 880 } 881 return (NULL); 882 } 883 884 /* 885 * Attempt to steal a thread in priority order from a thread queue. 886 */ 887 static struct td_sched * 888 tdq_steal(struct tdq *tdq, int stealidle) 889 { 890 struct td_sched *ts; 891 892 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 893 if ((ts = runq_steal(&tdq->tdq_realtime)) != NULL) 894 return (ts); 895 if ((ts = runq_steal_from(&tdq->tdq_timeshare, tdq->tdq_ridx)) != NULL) 896 return (ts); 897 if (stealidle) 898 return (runq_steal(&tdq->tdq_idle)); 899 return (NULL); 900 } 901 902 /* 903 * Sets the thread lock and ts_cpu to match the requested cpu. Unlocks the 904 * current lock and returns with the assigned queue locked. If this is 905 * via sched_switch() we leave the thread in a blocked state as an 906 * optimization. 907 */ 908 static inline struct tdq * 909 sched_setcpu(struct td_sched *ts, int cpu, int flags) 910 { 911 struct thread *td; 912 struct tdq *tdq; 913 914 THREAD_LOCK_ASSERT(ts->ts_thread, MA_OWNED); 915 916 tdq = TDQ_CPU(cpu); 917 td = ts->ts_thread; 918 ts->ts_cpu = cpu; 919 if (td->td_lock == TDQ_LOCKPTR(tdq)) 920 return (tdq); 921 #ifdef notyet 922 /* 923 * If the thread isn't running it's lockptr is a 924 * turnstile or a sleepqueue. We can just lock_set without 925 * blocking. 926 */ 927 if (TD_CAN_RUN(td)) { 928 TDQ_LOCK(tdq); 929 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 930 return (tdq); 931 } 932 #endif 933 /* 934 * The hard case, migration, we need to block the thread first to 935 * prevent order reversals with other cpus locks. 936 */ 937 thread_lock_block(td); 938 TDQ_LOCK(tdq); 939 /* Return to sched_switch() with the lock still blocked */ 940 if ((flags & SRQ_OURSELF) == 0) 941 thread_lock_unblock(td, TDQ_LOCKPTR(tdq)); 942 return (tdq); 943 } 944 945 /* 946 * Find the thread queue running the lowest priority thread. 947 */ 948 static int 949 tdq_lowestpri(void) 950 { 951 struct tdq *tdq; 952 int lowpri; 953 int lowcpu; 954 int lowload; 955 int load; 956 int cpu; 957 int pri; 958 959 lowload = 0; 960 lowpri = lowcpu = 0; 961 for (cpu = 0; cpu <= mp_maxid; cpu++) { 962 if (CPU_ABSENT(cpu)) 963 continue; 964 tdq = TDQ_CPU(cpu); 965 pri = tdq->tdq_lowpri; 966 load = TDQ_CPU(cpu)->tdq_load; 967 CTR4(KTR_ULE, 968 "cpu %d pri %d lowcpu %d lowpri %d", 969 cpu, pri, lowcpu, lowpri); 970 if (pri < lowpri) 971 continue; 972 if (lowpri && lowpri == pri && load > lowload) 973 continue; 974 lowpri = pri; 975 lowcpu = cpu; 976 lowload = load; 977 } 978 979 return (lowcpu); 980 } 981 982 /* 983 * Find the thread queue with the least load. 984 */ 985 static int 986 tdq_lowestload(void) 987 { 988 struct tdq *tdq; 989 int lowload; 990 int lowpri; 991 int lowcpu; 992 int load; 993 int cpu; 994 int pri; 995 996 lowcpu = 0; 997 lowload = TDQ_CPU(0)->tdq_load; 998 lowpri = TDQ_CPU(0)->tdq_lowpri; 999 for (cpu = 1; cpu <= mp_maxid; cpu++) { 1000 if (CPU_ABSENT(cpu)) 1001 continue; 1002 tdq = TDQ_CPU(cpu); 1003 load = tdq->tdq_load; 1004 pri = tdq->tdq_lowpri; 1005 CTR4(KTR_ULE, "cpu %d load %d lowcpu %d lowload %d", 1006 cpu, load, lowcpu, lowload); 1007 if (load > lowload) 1008 continue; 1009 if (load == lowload && pri < lowpri) 1010 continue; 1011 lowcpu = cpu; 1012 lowload = load; 1013 lowpri = pri; 1014 } 1015 1016 return (lowcpu); 1017 } 1018 1019 /* 1020 * Pick the destination cpu for sched_add(). Respects affinity and makes 1021 * a determination based on load or priority of available processors. 1022 */ 1023 static int 1024 sched_pickcpu(struct td_sched *ts, int flags) 1025 { 1026 struct tdq *tdq; 1027 int self; 1028 int pri; 1029 int cpu; 1030 1031 cpu = self = PCPU_GET(cpuid); 1032 if (smp_started == 0) 1033 return (self); 1034 /* 1035 * Don't migrate a running thread from sched_switch(). 1036 */ 1037 if (flags & SRQ_OURSELF) { 1038 CTR1(KTR_ULE, "YIELDING %d", 1039 curthread->td_priority); 1040 return (self); 1041 } 1042 pri = ts->ts_thread->td_priority; 1043 cpu = ts->ts_cpu; 1044 /* 1045 * Regardless of affinity, if the last cpu is idle send it there. 1046 */ 1047 tdq = TDQ_CPU(cpu); 1048 if (tdq->tdq_lowpri > PRI_MIN_IDLE) { 1049 CTR5(KTR_ULE, 1050 "ts_cpu %d idle, ltick %d ticks %d pri %d curthread %d", 1051 ts->ts_cpu, ts->ts_rltick, ticks, pri, 1052 tdq->tdq_lowpri); 1053 return (ts->ts_cpu); 1054 } 1055 /* 1056 * If we have affinity, try to place it on the cpu we last ran on. 1057 */ 1058 if (SCHED_AFFINITY(ts) && tdq->tdq_lowpri > pri) { 1059 CTR5(KTR_ULE, 1060 "affinity for %d, ltick %d ticks %d pri %d curthread %d", 1061 ts->ts_cpu, ts->ts_rltick, ticks, pri, 1062 tdq->tdq_lowpri); 1063 return (ts->ts_cpu); 1064 } 1065 /* 1066 * Look for an idle group. 1067 */ 1068 CTR1(KTR_ULE, "tdq_idle %X", tdq_idle); 1069 cpu = ffs(tdq_idle); 1070 if (cpu) 1071 return (--cpu); 1072 /* 1073 * If there are no idle cores see if we can run the thread locally. This may 1074 * improve locality among sleepers and wakers when there is shared data. 1075 */ 1076 if (tryself && pri < curthread->td_priority) { 1077 CTR1(KTR_ULE, "tryself %d", 1078 curthread->td_priority); 1079 return (self); 1080 } 1081 /* 1082 * Now search for the cpu running the lowest priority thread with 1083 * the least load. 1084 */ 1085 if (pick_pri) 1086 cpu = tdq_lowestpri(); 1087 else 1088 cpu = tdq_lowestload(); 1089 return (cpu); 1090 } 1091 1092 #endif /* SMP */ 1093 1094 /* 1095 * Pick the highest priority task we have and return it. 1096 */ 1097 static struct td_sched * 1098 tdq_choose(struct tdq *tdq) 1099 { 1100 struct td_sched *ts; 1101 1102 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1103 ts = runq_choose(&tdq->tdq_realtime); 1104 if (ts != NULL) 1105 return (ts); 1106 ts = runq_choose_from(&tdq->tdq_timeshare, tdq->tdq_ridx); 1107 if (ts != NULL) { 1108 KASSERT(ts->ts_thread->td_priority >= PRI_MIN_TIMESHARE, 1109 ("tdq_choose: Invalid priority on timeshare queue %d", 1110 ts->ts_thread->td_priority)); 1111 return (ts); 1112 } 1113 1114 ts = runq_choose(&tdq->tdq_idle); 1115 if (ts != NULL) { 1116 KASSERT(ts->ts_thread->td_priority >= PRI_MIN_IDLE, 1117 ("tdq_choose: Invalid priority on idle queue %d", 1118 ts->ts_thread->td_priority)); 1119 return (ts); 1120 } 1121 1122 return (NULL); 1123 } 1124 1125 /* 1126 * Initialize a thread queue. 1127 */ 1128 static void 1129 tdq_setup(struct tdq *tdq) 1130 { 1131 1132 snprintf(tdq->tdq_name, sizeof(tdq->tdq_name), 1133 "sched lock %d", (int)TDQ_ID(tdq)); 1134 mtx_init(&tdq->tdq_lock, tdq->tdq_name, "sched lock", 1135 MTX_SPIN | MTX_RECURSE); 1136 runq_init(&tdq->tdq_realtime); 1137 runq_init(&tdq->tdq_timeshare); 1138 runq_init(&tdq->tdq_idle); 1139 tdq->tdq_load = 0; 1140 } 1141 1142 /* 1143 * Setup the thread queues and initialize the topology based on MD 1144 * information. 1145 */ 1146 static void 1147 sched_setup(void *dummy) 1148 { 1149 struct tdq *tdq; 1150 #ifdef SMP 1151 int balance_groups; 1152 int i; 1153 1154 balance_groups = 0; 1155 /* 1156 * Initialize the tdqs. 1157 */ 1158 for (i = 0; i < MAXCPU; i++) { 1159 tdq = &tdq_cpu[i]; 1160 tdq_setup(&tdq_cpu[i]); 1161 } 1162 if (smp_topology == NULL) { 1163 struct tdq_group *tdg; 1164 int cpus; 1165 1166 for (cpus = 0, i = 0; i < MAXCPU; i++) { 1167 if (CPU_ABSENT(i)) 1168 continue; 1169 tdq = &tdq_cpu[i]; 1170 tdg = &tdq_groups[cpus]; 1171 /* 1172 * Setup a tdq group with one member. 1173 */ 1174 tdq->tdq_transferable = 0; 1175 tdq->tdq_group = tdg; 1176 tdg->tdg_cpus = 1; 1177 tdg->tdg_idlemask = 0; 1178 tdg->tdg_cpumask = tdg->tdg_mask = 1 << i; 1179 tdg->tdg_load = 0; 1180 tdg->tdg_transferable = 0; 1181 LIST_INIT(&tdg->tdg_members); 1182 LIST_INSERT_HEAD(&tdg->tdg_members, tdq, tdq_siblings); 1183 cpus++; 1184 } 1185 tdg_maxid = cpus - 1; 1186 } else { 1187 struct tdq_group *tdg; 1188 struct cpu_group *cg; 1189 int j; 1190 1191 topology = 1; 1192 for (i = 0; i < smp_topology->ct_count; i++) { 1193 cg = &smp_topology->ct_group[i]; 1194 tdg = &tdq_groups[i]; 1195 /* 1196 * Initialize the group. 1197 */ 1198 tdg->tdg_idlemask = 0; 1199 tdg->tdg_load = 0; 1200 tdg->tdg_transferable = 0; 1201 tdg->tdg_cpus = cg->cg_count; 1202 tdg->tdg_cpumask = cg->cg_mask; 1203 LIST_INIT(&tdg->tdg_members); 1204 /* 1205 * Find all of the group members and add them. 1206 */ 1207 for (j = 0; j < MAXCPU; j++) { 1208 if ((cg->cg_mask & (1 << j)) != 0) { 1209 if (tdg->tdg_mask == 0) 1210 tdg->tdg_mask = 1 << j; 1211 tdq_cpu[j].tdq_transferable = 0; 1212 tdq_cpu[j].tdq_group = tdg; 1213 LIST_INSERT_HEAD(&tdg->tdg_members, 1214 &tdq_cpu[j], tdq_siblings); 1215 } 1216 } 1217 if (tdg->tdg_cpus > 1) 1218 balance_groups = 1; 1219 } 1220 tdg_maxid = smp_topology->ct_count - 1; 1221 } 1222 /* 1223 * Initialize long-term cpu balancing algorithm. 1224 */ 1225 callout_init(&balco, CALLOUT_MPSAFE); 1226 callout_init(&gbalco, CALLOUT_MPSAFE); 1227 sched_balance(NULL); 1228 if (balance_groups) 1229 sched_balance_groups(NULL); 1230 1231 #else 1232 tdq_setup(TDQ_SELF()); 1233 #endif 1234 /* 1235 * To avoid divide-by-zero, we set realstathz a dummy value 1236 * in case which sched_clock() called before sched_initticks(). 1237 */ 1238 realstathz = hz; 1239 sched_slice = (realstathz/10); /* ~100ms */ 1240 tickincr = 1 << SCHED_TICK_SHIFT; 1241 1242 /* Add thread0's load since it's running. */ 1243 tdq = TDQ_SELF(); 1244 TDQ_LOCK(tdq); 1245 tdq_load_add(tdq, &td_sched0); 1246 TDQ_UNLOCK(tdq); 1247 } 1248 1249 /* 1250 * This routine determines the tickincr after stathz and hz are setup. 1251 */ 1252 /* ARGSUSED */ 1253 static void 1254 sched_initticks(void *dummy) 1255 { 1256 int incr; 1257 1258 realstathz = stathz ? stathz : hz; 1259 sched_slice = (realstathz/10); /* ~100ms */ 1260 1261 /* 1262 * tickincr is shifted out by 10 to avoid rounding errors due to 1263 * hz not being evenly divisible by stathz on all platforms. 1264 */ 1265 incr = (hz << SCHED_TICK_SHIFT) / realstathz; 1266 /* 1267 * This does not work for values of stathz that are more than 1268 * 1 << SCHED_TICK_SHIFT * hz. In practice this does not happen. 1269 */ 1270 if (incr == 0) 1271 incr = 1; 1272 tickincr = incr; 1273 #ifdef SMP 1274 affinity = SCHED_AFFINITY_DEFAULT; 1275 #endif 1276 } 1277 1278 1279 /* 1280 * This is the core of the interactivity algorithm. Determines a score based 1281 * on past behavior. It is the ratio of sleep time to run time scaled to 1282 * a [0, 100] integer. This is the voluntary sleep time of a process, which 1283 * differs from the cpu usage because it does not account for time spent 1284 * waiting on a run-queue. Would be prettier if we had floating point. 1285 */ 1286 static int 1287 sched_interact_score(struct thread *td) 1288 { 1289 struct td_sched *ts; 1290 int div; 1291 1292 ts = td->td_sched; 1293 /* 1294 * The score is only needed if this is likely to be an interactive 1295 * task. Don't go through the expense of computing it if there's 1296 * no chance. 1297 */ 1298 if (sched_interact <= SCHED_INTERACT_HALF && 1299 ts->ts_runtime >= ts->ts_slptime) 1300 return (SCHED_INTERACT_HALF); 1301 1302 if (ts->ts_runtime > ts->ts_slptime) { 1303 div = max(1, ts->ts_runtime / SCHED_INTERACT_HALF); 1304 return (SCHED_INTERACT_HALF + 1305 (SCHED_INTERACT_HALF - (ts->ts_slptime / div))); 1306 } 1307 if (ts->ts_slptime > ts->ts_runtime) { 1308 div = max(1, ts->ts_slptime / SCHED_INTERACT_HALF); 1309 return (ts->ts_runtime / div); 1310 } 1311 /* runtime == slptime */ 1312 if (ts->ts_runtime) 1313 return (SCHED_INTERACT_HALF); 1314 1315 /* 1316 * This can happen if slptime and runtime are 0. 1317 */ 1318 return (0); 1319 1320 } 1321 1322 /* 1323 * Scale the scheduling priority according to the "interactivity" of this 1324 * process. 1325 */ 1326 static void 1327 sched_priority(struct thread *td) 1328 { 1329 int score; 1330 int pri; 1331 1332 if (td->td_pri_class != PRI_TIMESHARE) 1333 return; 1334 /* 1335 * If the score is interactive we place the thread in the realtime 1336 * queue with a priority that is less than kernel and interrupt 1337 * priorities. These threads are not subject to nice restrictions. 1338 * 1339 * Scores greater than this are placed on the normal timeshare queue 1340 * where the priority is partially decided by the most recent cpu 1341 * utilization and the rest is decided by nice value. 1342 */ 1343 score = sched_interact_score(td); 1344 if (score < sched_interact) { 1345 pri = PRI_MIN_REALTIME; 1346 pri += ((PRI_MAX_REALTIME - PRI_MIN_REALTIME) / sched_interact) 1347 * score; 1348 KASSERT(pri >= PRI_MIN_REALTIME && pri <= PRI_MAX_REALTIME, 1349 ("sched_priority: invalid interactive priority %d score %d", 1350 pri, score)); 1351 } else { 1352 pri = SCHED_PRI_MIN; 1353 if (td->td_sched->ts_ticks) 1354 pri += SCHED_PRI_TICKS(td->td_sched); 1355 pri += SCHED_PRI_NICE(td->td_proc->p_nice); 1356 KASSERT(pri >= PRI_MIN_TIMESHARE && pri <= PRI_MAX_TIMESHARE, 1357 ("sched_priority: invalid priority %d: nice %d, " 1358 "ticks %d ftick %d ltick %d tick pri %d", 1359 pri, td->td_proc->p_nice, td->td_sched->ts_ticks, 1360 td->td_sched->ts_ftick, td->td_sched->ts_ltick, 1361 SCHED_PRI_TICKS(td->td_sched))); 1362 } 1363 sched_user_prio(td, pri); 1364 1365 return; 1366 } 1367 1368 /* 1369 * This routine enforces a maximum limit on the amount of scheduling history 1370 * kept. It is called after either the slptime or runtime is adjusted. This 1371 * function is ugly due to integer math. 1372 */ 1373 static void 1374 sched_interact_update(struct thread *td) 1375 { 1376 struct td_sched *ts; 1377 u_int sum; 1378 1379 ts = td->td_sched; 1380 sum = ts->ts_runtime + ts->ts_slptime; 1381 if (sum < SCHED_SLP_RUN_MAX) 1382 return; 1383 /* 1384 * This only happens from two places: 1385 * 1) We have added an unusual amount of run time from fork_exit. 1386 * 2) We have added an unusual amount of sleep time from sched_sleep(). 1387 */ 1388 if (sum > SCHED_SLP_RUN_MAX * 2) { 1389 if (ts->ts_runtime > ts->ts_slptime) { 1390 ts->ts_runtime = SCHED_SLP_RUN_MAX; 1391 ts->ts_slptime = 1; 1392 } else { 1393 ts->ts_slptime = SCHED_SLP_RUN_MAX; 1394 ts->ts_runtime = 1; 1395 } 1396 return; 1397 } 1398 /* 1399 * If we have exceeded by more than 1/5th then the algorithm below 1400 * will not bring us back into range. Dividing by two here forces 1401 * us into the range of [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX] 1402 */ 1403 if (sum > (SCHED_SLP_RUN_MAX / 5) * 6) { 1404 ts->ts_runtime /= 2; 1405 ts->ts_slptime /= 2; 1406 return; 1407 } 1408 ts->ts_runtime = (ts->ts_runtime / 5) * 4; 1409 ts->ts_slptime = (ts->ts_slptime / 5) * 4; 1410 } 1411 1412 /* 1413 * Scale back the interactivity history when a child thread is created. The 1414 * history is inherited from the parent but the thread may behave totally 1415 * differently. For example, a shell spawning a compiler process. We want 1416 * to learn that the compiler is behaving badly very quickly. 1417 */ 1418 static void 1419 sched_interact_fork(struct thread *td) 1420 { 1421 int ratio; 1422 int sum; 1423 1424 sum = td->td_sched->ts_runtime + td->td_sched->ts_slptime; 1425 if (sum > SCHED_SLP_RUN_FORK) { 1426 ratio = sum / SCHED_SLP_RUN_FORK; 1427 td->td_sched->ts_runtime /= ratio; 1428 td->td_sched->ts_slptime /= ratio; 1429 } 1430 } 1431 1432 /* 1433 * Called from proc0_init() to setup the scheduler fields. 1434 */ 1435 void 1436 schedinit(void) 1437 { 1438 1439 /* 1440 * Set up the scheduler specific parts of proc0. 1441 */ 1442 proc0.p_sched = NULL; /* XXX */ 1443 thread0.td_sched = &td_sched0; 1444 thread0.td_lock = TDQ_LOCKPTR(TDQ_SELF()); 1445 td_sched0.ts_ltick = ticks; 1446 td_sched0.ts_ftick = ticks; 1447 td_sched0.ts_thread = &thread0; 1448 } 1449 1450 /* 1451 * This is only somewhat accurate since given many processes of the same 1452 * priority they will switch when their slices run out, which will be 1453 * at most sched_slice stathz ticks. 1454 */ 1455 int 1456 sched_rr_interval(void) 1457 { 1458 1459 /* Convert sched_slice to hz */ 1460 return (hz/(realstathz/sched_slice)); 1461 } 1462 1463 /* 1464 * Update the percent cpu tracking information when it is requested or 1465 * the total history exceeds the maximum. We keep a sliding history of 1466 * tick counts that slowly decays. This is less precise than the 4BSD 1467 * mechanism since it happens with less regular and frequent events. 1468 */ 1469 static void 1470 sched_pctcpu_update(struct td_sched *ts) 1471 { 1472 1473 if (ts->ts_ticks == 0) 1474 return; 1475 if (ticks - (hz / 10) < ts->ts_ltick && 1476 SCHED_TICK_TOTAL(ts) < SCHED_TICK_MAX) 1477 return; 1478 /* 1479 * Adjust counters and watermark for pctcpu calc. 1480 */ 1481 if (ts->ts_ltick > ticks - SCHED_TICK_TARG) 1482 ts->ts_ticks = (ts->ts_ticks / (ticks - ts->ts_ftick)) * 1483 SCHED_TICK_TARG; 1484 else 1485 ts->ts_ticks = 0; 1486 ts->ts_ltick = ticks; 1487 ts->ts_ftick = ts->ts_ltick - SCHED_TICK_TARG; 1488 } 1489 1490 /* 1491 * Adjust the priority of a thread. Move it to the appropriate run-queue 1492 * if necessary. This is the back-end for several priority related 1493 * functions. 1494 */ 1495 static void 1496 sched_thread_priority(struct thread *td, u_char prio) 1497 { 1498 struct td_sched *ts; 1499 1500 CTR6(KTR_SCHED, "sched_prio: %p(%s) prio %d newprio %d by %p(%s)", 1501 td, td->td_proc->p_comm, td->td_priority, prio, curthread, 1502 curthread->td_proc->p_comm); 1503 ts = td->td_sched; 1504 THREAD_LOCK_ASSERT(td, MA_OWNED); 1505 if (td->td_priority == prio) 1506 return; 1507 1508 if (TD_ON_RUNQ(td) && prio < td->td_priority) { 1509 /* 1510 * If the priority has been elevated due to priority 1511 * propagation, we may have to move ourselves to a new 1512 * queue. This could be optimized to not re-add in some 1513 * cases. 1514 */ 1515 sched_rem(td); 1516 td->td_priority = prio; 1517 sched_add(td, SRQ_BORROWING); 1518 } else { 1519 #ifdef SMP 1520 struct tdq *tdq; 1521 1522 tdq = TDQ_CPU(ts->ts_cpu); 1523 if (prio < tdq->tdq_lowpri) 1524 tdq->tdq_lowpri = prio; 1525 #endif 1526 td->td_priority = prio; 1527 } 1528 } 1529 1530 /* 1531 * Update a thread's priority when it is lent another thread's 1532 * priority. 1533 */ 1534 void 1535 sched_lend_prio(struct thread *td, u_char prio) 1536 { 1537 1538 td->td_flags |= TDF_BORROWING; 1539 sched_thread_priority(td, prio); 1540 } 1541 1542 /* 1543 * Restore a thread's priority when priority propagation is 1544 * over. The prio argument is the minimum priority the thread 1545 * needs to have to satisfy other possible priority lending 1546 * requests. If the thread's regular priority is less 1547 * important than prio, the thread will keep a priority boost 1548 * of prio. 1549 */ 1550 void 1551 sched_unlend_prio(struct thread *td, u_char prio) 1552 { 1553 u_char base_pri; 1554 1555 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 1556 td->td_base_pri <= PRI_MAX_TIMESHARE) 1557 base_pri = td->td_user_pri; 1558 else 1559 base_pri = td->td_base_pri; 1560 if (prio >= base_pri) { 1561 td->td_flags &= ~TDF_BORROWING; 1562 sched_thread_priority(td, base_pri); 1563 } else 1564 sched_lend_prio(td, prio); 1565 } 1566 1567 /* 1568 * Standard entry for setting the priority to an absolute value. 1569 */ 1570 void 1571 sched_prio(struct thread *td, u_char prio) 1572 { 1573 u_char oldprio; 1574 1575 /* First, update the base priority. */ 1576 td->td_base_pri = prio; 1577 1578 /* 1579 * If the thread is borrowing another thread's priority, don't 1580 * ever lower the priority. 1581 */ 1582 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 1583 return; 1584 1585 /* Change the real priority. */ 1586 oldprio = td->td_priority; 1587 sched_thread_priority(td, prio); 1588 1589 /* 1590 * If the thread is on a turnstile, then let the turnstile update 1591 * its state. 1592 */ 1593 if (TD_ON_LOCK(td) && oldprio != prio) 1594 turnstile_adjust(td, oldprio); 1595 } 1596 1597 /* 1598 * Set the base user priority, does not effect current running priority. 1599 */ 1600 void 1601 sched_user_prio(struct thread *td, u_char prio) 1602 { 1603 u_char oldprio; 1604 1605 td->td_base_user_pri = prio; 1606 if (td->td_flags & TDF_UBORROWING && td->td_user_pri <= prio) 1607 return; 1608 oldprio = td->td_user_pri; 1609 td->td_user_pri = prio; 1610 1611 if (TD_ON_UPILOCK(td) && oldprio != prio) 1612 umtx_pi_adjust(td, oldprio); 1613 } 1614 1615 void 1616 sched_lend_user_prio(struct thread *td, u_char prio) 1617 { 1618 u_char oldprio; 1619 1620 td->td_flags |= TDF_UBORROWING; 1621 1622 oldprio = td->td_user_pri; 1623 td->td_user_pri = prio; 1624 1625 if (TD_ON_UPILOCK(td) && oldprio != prio) 1626 umtx_pi_adjust(td, oldprio); 1627 } 1628 1629 void 1630 sched_unlend_user_prio(struct thread *td, u_char prio) 1631 { 1632 u_char base_pri; 1633 1634 base_pri = td->td_base_user_pri; 1635 if (prio >= base_pri) { 1636 td->td_flags &= ~TDF_UBORROWING; 1637 sched_user_prio(td, base_pri); 1638 } else 1639 sched_lend_user_prio(td, prio); 1640 } 1641 1642 /* 1643 * Add the thread passed as 'newtd' to the run queue before selecting 1644 * the next thread to run. This is only used for KSE. 1645 */ 1646 static void 1647 sched_switchin(struct tdq *tdq, struct thread *td) 1648 { 1649 #ifdef SMP 1650 spinlock_enter(); 1651 TDQ_UNLOCK(tdq); 1652 thread_lock(td); 1653 spinlock_exit(); 1654 sched_setcpu(td->td_sched, TDQ_ID(tdq), SRQ_YIELDING); 1655 #else 1656 td->td_lock = TDQ_LOCKPTR(tdq); 1657 #endif 1658 tdq_add(tdq, td, SRQ_YIELDING); 1659 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1660 } 1661 1662 /* 1663 * Block a thread for switching. Similar to thread_block() but does not 1664 * bump the spin count. 1665 */ 1666 static inline struct mtx * 1667 thread_block_switch(struct thread *td) 1668 { 1669 struct mtx *lock; 1670 1671 THREAD_LOCK_ASSERT(td, MA_OWNED); 1672 lock = td->td_lock; 1673 td->td_lock = &blocked_lock; 1674 mtx_unlock_spin(lock); 1675 1676 return (lock); 1677 } 1678 1679 /* 1680 * Release a thread that was blocked with thread_block_switch(). 1681 */ 1682 static inline void 1683 thread_unblock_switch(struct thread *td, struct mtx *mtx) 1684 { 1685 atomic_store_rel_ptr((volatile uintptr_t *)&td->td_lock, 1686 (uintptr_t)mtx); 1687 } 1688 1689 /* 1690 * Switch threads. This function has to handle threads coming in while 1691 * blocked for some reason, running, or idle. It also must deal with 1692 * migrating a thread from one queue to another as running threads may 1693 * be assigned elsewhere via binding. 1694 */ 1695 void 1696 sched_switch(struct thread *td, struct thread *newtd, int flags) 1697 { 1698 struct tdq *tdq; 1699 struct td_sched *ts; 1700 struct mtx *mtx; 1701 int cpuid; 1702 1703 THREAD_LOCK_ASSERT(td, MA_OWNED); 1704 1705 cpuid = PCPU_GET(cpuid); 1706 tdq = TDQ_CPU(cpuid); 1707 ts = td->td_sched; 1708 mtx = TDQ_LOCKPTR(tdq); 1709 #ifdef SMP 1710 ts->ts_rltick = ticks; 1711 if (newtd && newtd->td_priority < tdq->tdq_lowpri) 1712 tdq->tdq_lowpri = newtd->td_priority; 1713 #endif 1714 td->td_lastcpu = td->td_oncpu; 1715 td->td_oncpu = NOCPU; 1716 td->td_flags &= ~TDF_NEEDRESCHED; 1717 td->td_owepreempt = 0; 1718 /* 1719 * The lock pointer in an idle thread should never change. Reset it 1720 * to CAN_RUN as well. 1721 */ 1722 if (TD_IS_IDLETHREAD(td)) { 1723 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1724 TD_SET_CAN_RUN(td); 1725 } else if (TD_IS_RUNNING(td)) { 1726 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1727 /* Remove our load so the selection algorithm is not biased. */ 1728 tdq_load_rem(tdq, ts); 1729 sched_add(td, (flags & SW_PREEMPT) ? 1730 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 1731 SRQ_OURSELF|SRQ_YIELDING); 1732 /* 1733 * When migrating we return from sched_add with an extra 1734 * spinlock nesting, the tdq locked, and a blocked thread. 1735 * This is to optimize out an extra block/unblock cycle here. 1736 */ 1737 if (ts->ts_cpu != cpuid) { 1738 mtx = TDQ_LOCKPTR(TDQ_CPU(ts->ts_cpu)); 1739 mtx_unlock_spin(mtx); 1740 TDQ_LOCK(tdq); 1741 spinlock_exit(); 1742 } 1743 } else { 1744 /* This thread must be going to sleep. */ 1745 TDQ_LOCK(tdq); 1746 mtx = thread_block_switch(td); 1747 tdq_load_rem(tdq, ts); 1748 } 1749 /* 1750 * We enter here with the thread blocked and assigned to the 1751 * appropriate cpu run-queue or sleep-queue and with the current 1752 * thread-queue locked. 1753 */ 1754 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 1755 /* 1756 * If KSE assigned a new thread just add it here and let choosethread 1757 * select the best one. 1758 */ 1759 if (newtd != NULL) 1760 sched_switchin(tdq, newtd); 1761 newtd = choosethread(); 1762 /* 1763 * Call the MD code to switch contexts if necessary. 1764 */ 1765 if (td != newtd) { 1766 #ifdef HWPMC_HOOKS 1767 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1768 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 1769 #endif 1770 cpu_switch(td, newtd, mtx); 1771 /* 1772 * We may return from cpu_switch on a different cpu. However, 1773 * we always return with td_lock pointing to the current cpu's 1774 * run queue lock. 1775 */ 1776 cpuid = PCPU_GET(cpuid); 1777 tdq = TDQ_CPU(cpuid); 1778 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)td; 1779 #ifdef HWPMC_HOOKS 1780 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1781 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 1782 #endif 1783 } else 1784 thread_unblock_switch(td, mtx); 1785 /* 1786 * Assert that all went well and return. 1787 */ 1788 #ifdef SMP 1789 /* We should always get here with the lowest priority td possible */ 1790 tdq->tdq_lowpri = td->td_priority; 1791 #endif 1792 TDQ_LOCK_ASSERT(tdq, MA_OWNED|MA_NOTRECURSED); 1793 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1794 td->td_oncpu = cpuid; 1795 } 1796 1797 /* 1798 * Adjust thread priorities as a result of a nice request. 1799 */ 1800 void 1801 sched_nice(struct proc *p, int nice) 1802 { 1803 struct thread *td; 1804 1805 PROC_LOCK_ASSERT(p, MA_OWNED); 1806 PROC_SLOCK_ASSERT(p, MA_OWNED); 1807 1808 p->p_nice = nice; 1809 FOREACH_THREAD_IN_PROC(p, td) { 1810 thread_lock(td); 1811 sched_priority(td); 1812 sched_prio(td, td->td_base_user_pri); 1813 thread_unlock(td); 1814 } 1815 } 1816 1817 /* 1818 * Record the sleep time for the interactivity scorer. 1819 */ 1820 void 1821 sched_sleep(struct thread *td) 1822 { 1823 1824 THREAD_LOCK_ASSERT(td, MA_OWNED); 1825 1826 td->td_sched->ts_slptick = ticks; 1827 } 1828 1829 /* 1830 * Schedule a thread to resume execution and record how long it voluntarily 1831 * slept. We also update the pctcpu, interactivity, and priority. 1832 */ 1833 void 1834 sched_wakeup(struct thread *td) 1835 { 1836 struct td_sched *ts; 1837 int slptick; 1838 1839 THREAD_LOCK_ASSERT(td, MA_OWNED); 1840 ts = td->td_sched; 1841 /* 1842 * If we slept for more than a tick update our interactivity and 1843 * priority. 1844 */ 1845 slptick = ts->ts_slptick; 1846 ts->ts_slptick = 0; 1847 if (slptick && slptick != ticks) { 1848 u_int hzticks; 1849 1850 hzticks = (ticks - slptick) << SCHED_TICK_SHIFT; 1851 ts->ts_slptime += hzticks; 1852 sched_interact_update(td); 1853 sched_pctcpu_update(ts); 1854 sched_priority(td); 1855 } 1856 /* Reset the slice value after we sleep. */ 1857 ts->ts_slice = sched_slice; 1858 sched_add(td, SRQ_BORING); 1859 } 1860 1861 /* 1862 * Penalize the parent for creating a new child and initialize the child's 1863 * priority. 1864 */ 1865 void 1866 sched_fork(struct thread *td, struct thread *child) 1867 { 1868 THREAD_LOCK_ASSERT(td, MA_OWNED); 1869 sched_fork_thread(td, child); 1870 /* 1871 * Penalize the parent and child for forking. 1872 */ 1873 sched_interact_fork(child); 1874 sched_priority(child); 1875 td->td_sched->ts_runtime += tickincr; 1876 sched_interact_update(td); 1877 sched_priority(td); 1878 } 1879 1880 /* 1881 * Fork a new thread, may be within the same process. 1882 */ 1883 void 1884 sched_fork_thread(struct thread *td, struct thread *child) 1885 { 1886 struct td_sched *ts; 1887 struct td_sched *ts2; 1888 1889 /* 1890 * Initialize child. 1891 */ 1892 THREAD_LOCK_ASSERT(td, MA_OWNED); 1893 sched_newthread(child); 1894 child->td_lock = TDQ_LOCKPTR(TDQ_SELF()); 1895 ts = td->td_sched; 1896 ts2 = child->td_sched; 1897 ts2->ts_cpu = ts->ts_cpu; 1898 ts2->ts_runq = NULL; 1899 /* 1900 * Grab our parents cpu estimation information and priority. 1901 */ 1902 ts2->ts_ticks = ts->ts_ticks; 1903 ts2->ts_ltick = ts->ts_ltick; 1904 ts2->ts_ftick = ts->ts_ftick; 1905 child->td_user_pri = td->td_user_pri; 1906 child->td_base_user_pri = td->td_base_user_pri; 1907 /* 1908 * And update interactivity score. 1909 */ 1910 ts2->ts_slptime = ts->ts_slptime; 1911 ts2->ts_runtime = ts->ts_runtime; 1912 ts2->ts_slice = 1; /* Attempt to quickly learn interactivity. */ 1913 } 1914 1915 /* 1916 * Adjust the priority class of a thread. 1917 */ 1918 void 1919 sched_class(struct thread *td, int class) 1920 { 1921 1922 THREAD_LOCK_ASSERT(td, MA_OWNED); 1923 if (td->td_pri_class == class) 1924 return; 1925 1926 #ifdef SMP 1927 /* 1928 * On SMP if we're on the RUNQ we must adjust the transferable 1929 * count because could be changing to or from an interrupt 1930 * class. 1931 */ 1932 if (TD_ON_RUNQ(td)) { 1933 struct tdq *tdq; 1934 1935 tdq = TDQ_CPU(td->td_sched->ts_cpu); 1936 if (THREAD_CAN_MIGRATE(td)) { 1937 tdq->tdq_transferable--; 1938 tdq->tdq_group->tdg_transferable--; 1939 } 1940 td->td_pri_class = class; 1941 if (THREAD_CAN_MIGRATE(td)) { 1942 tdq->tdq_transferable++; 1943 tdq->tdq_group->tdg_transferable++; 1944 } 1945 } 1946 #endif 1947 td->td_pri_class = class; 1948 } 1949 1950 /* 1951 * Return some of the child's priority and interactivity to the parent. 1952 */ 1953 void 1954 sched_exit(struct proc *p, struct thread *child) 1955 { 1956 struct thread *td; 1957 1958 CTR3(KTR_SCHED, "sched_exit: %p(%s) prio %d", 1959 child, child->td_proc->p_comm, child->td_priority); 1960 1961 PROC_SLOCK_ASSERT(p, MA_OWNED); 1962 td = FIRST_THREAD_IN_PROC(p); 1963 sched_exit_thread(td, child); 1964 } 1965 1966 /* 1967 * Penalize another thread for the time spent on this one. This helps to 1968 * worsen the priority and interactivity of processes which schedule batch 1969 * jobs such as make. This has little effect on the make process itself but 1970 * causes new processes spawned by it to receive worse scores immediately. 1971 */ 1972 void 1973 sched_exit_thread(struct thread *td, struct thread *child) 1974 { 1975 1976 CTR3(KTR_SCHED, "sched_exit_thread: %p(%s) prio %d", 1977 child, child->td_proc->p_comm, child->td_priority); 1978 1979 #ifdef KSE 1980 /* 1981 * KSE forks and exits so often that this penalty causes short-lived 1982 * threads to always be non-interactive. This causes mozilla to 1983 * crawl under load. 1984 */ 1985 if ((td->td_pflags & TDP_SA) && td->td_proc == child->td_proc) 1986 return; 1987 #endif 1988 /* 1989 * Give the child's runtime to the parent without returning the 1990 * sleep time as a penalty to the parent. This causes shells that 1991 * launch expensive things to mark their children as expensive. 1992 */ 1993 thread_lock(td); 1994 td->td_sched->ts_runtime += child->td_sched->ts_runtime; 1995 sched_interact_update(td); 1996 sched_priority(td); 1997 thread_unlock(td); 1998 } 1999 2000 /* 2001 * Fix priorities on return to user-space. Priorities may be elevated due 2002 * to static priorities in msleep() or similar. 2003 */ 2004 void 2005 sched_userret(struct thread *td) 2006 { 2007 /* 2008 * XXX we cheat slightly on the locking here to avoid locking in 2009 * the usual case. Setting td_priority here is essentially an 2010 * incomplete workaround for not setting it properly elsewhere. 2011 * Now that some interrupt handlers are threads, not setting it 2012 * properly elsewhere can clobber it in the window between setting 2013 * it here and returning to user mode, so don't waste time setting 2014 * it perfectly here. 2015 */ 2016 KASSERT((td->td_flags & TDF_BORROWING) == 0, 2017 ("thread with borrowed priority returning to userland")); 2018 if (td->td_priority != td->td_user_pri) { 2019 thread_lock(td); 2020 td->td_priority = td->td_user_pri; 2021 td->td_base_pri = td->td_user_pri; 2022 thread_unlock(td); 2023 } 2024 } 2025 2026 /* 2027 * Handle a stathz tick. This is really only relevant for timeshare 2028 * threads. 2029 */ 2030 void 2031 sched_clock(struct thread *td) 2032 { 2033 struct tdq *tdq; 2034 struct td_sched *ts; 2035 2036 THREAD_LOCK_ASSERT(td, MA_OWNED); 2037 tdq = TDQ_SELF(); 2038 /* 2039 * Advance the insert index once for each tick to ensure that all 2040 * threads get a chance to run. 2041 */ 2042 if (tdq->tdq_idx == tdq->tdq_ridx) { 2043 tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS; 2044 if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx])) 2045 tdq->tdq_ridx = tdq->tdq_idx; 2046 } 2047 ts = td->td_sched; 2048 /* 2049 * We only do slicing code for TIMESHARE threads. 2050 */ 2051 if (td->td_pri_class != PRI_TIMESHARE) 2052 return; 2053 /* 2054 * We used a tick; charge it to the thread so that we can compute our 2055 * interactivity. 2056 */ 2057 td->td_sched->ts_runtime += tickincr; 2058 sched_interact_update(td); 2059 /* 2060 * We used up one time slice. 2061 */ 2062 if (--ts->ts_slice > 0) 2063 return; 2064 /* 2065 * We're out of time, recompute priorities and requeue. 2066 */ 2067 sched_priority(td); 2068 td->td_flags |= TDF_NEEDRESCHED; 2069 } 2070 2071 /* 2072 * Called once per hz tick. Used for cpu utilization information. This 2073 * is easier than trying to scale based on stathz. 2074 */ 2075 void 2076 sched_tick(void) 2077 { 2078 struct td_sched *ts; 2079 2080 ts = curthread->td_sched; 2081 /* Adjust ticks for pctcpu */ 2082 ts->ts_ticks += 1 << SCHED_TICK_SHIFT; 2083 ts->ts_ltick = ticks; 2084 /* 2085 * Update if we've exceeded our desired tick threshhold by over one 2086 * second. 2087 */ 2088 if (ts->ts_ftick + SCHED_TICK_MAX < ts->ts_ltick) 2089 sched_pctcpu_update(ts); 2090 } 2091 2092 /* 2093 * Return whether the current CPU has runnable tasks. Used for in-kernel 2094 * cooperative idle threads. 2095 */ 2096 int 2097 sched_runnable(void) 2098 { 2099 struct tdq *tdq; 2100 int load; 2101 2102 load = 1; 2103 2104 tdq = TDQ_SELF(); 2105 if ((curthread->td_flags & TDF_IDLETD) != 0) { 2106 if (tdq->tdq_load > 0) 2107 goto out; 2108 } else 2109 if (tdq->tdq_load - 1 > 0) 2110 goto out; 2111 load = 0; 2112 out: 2113 return (load); 2114 } 2115 2116 /* 2117 * Choose the highest priority thread to run. The thread is removed from 2118 * the run-queue while running however the load remains. For SMP we set 2119 * the tdq in the global idle bitmask if it idles here. 2120 */ 2121 struct thread * 2122 sched_choose(void) 2123 { 2124 #ifdef SMP 2125 struct tdq_group *tdg; 2126 #endif 2127 struct td_sched *ts; 2128 struct tdq *tdq; 2129 2130 tdq = TDQ_SELF(); 2131 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2132 ts = tdq_choose(tdq); 2133 if (ts) { 2134 tdq_runq_rem(tdq, ts); 2135 return (ts->ts_thread); 2136 } 2137 #ifdef SMP 2138 /* 2139 * We only set the idled bit when all of the cpus in the group are 2140 * idle. Otherwise we could get into a situation where a thread bounces 2141 * back and forth between two idle cores on seperate physical CPUs. 2142 */ 2143 tdg = tdq->tdq_group; 2144 tdg->tdg_idlemask |= PCPU_GET(cpumask); 2145 if (tdg->tdg_idlemask == tdg->tdg_cpumask) 2146 atomic_set_int(&tdq_idle, tdg->tdg_mask); 2147 tdq->tdq_lowpri = PRI_MAX_IDLE; 2148 #endif 2149 return (PCPU_GET(idlethread)); 2150 } 2151 2152 /* 2153 * Set owepreempt if necessary. Preemption never happens directly in ULE, 2154 * we always request it once we exit a critical section. 2155 */ 2156 static inline void 2157 sched_setpreempt(struct thread *td) 2158 { 2159 struct thread *ctd; 2160 int cpri; 2161 int pri; 2162 2163 ctd = curthread; 2164 pri = td->td_priority; 2165 cpri = ctd->td_priority; 2166 if (td->td_priority < ctd->td_priority) 2167 curthread->td_flags |= TDF_NEEDRESCHED; 2168 if (panicstr != NULL || pri >= cpri || cold || TD_IS_INHIBITED(ctd)) 2169 return; 2170 /* 2171 * Always preempt IDLE threads. Otherwise only if the preempting 2172 * thread is an ithread. 2173 */ 2174 if (pri > preempt_thresh && cpri < PRI_MIN_IDLE) 2175 return; 2176 ctd->td_owepreempt = 1; 2177 return; 2178 } 2179 2180 /* 2181 * Add a thread to a thread queue. Initializes priority, slice, runq, and 2182 * add it to the appropriate queue. This is the internal function called 2183 * when the tdq is predetermined. 2184 */ 2185 void 2186 tdq_add(struct tdq *tdq, struct thread *td, int flags) 2187 { 2188 struct td_sched *ts; 2189 int class; 2190 #ifdef SMP 2191 int cpumask; 2192 #endif 2193 2194 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2195 KASSERT((td->td_inhibitors == 0), 2196 ("sched_add: trying to run inhibited thread")); 2197 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 2198 ("sched_add: bad thread state")); 2199 KASSERT(td->td_proc->p_sflag & PS_INMEM, 2200 ("sched_add: process swapped out")); 2201 2202 ts = td->td_sched; 2203 class = PRI_BASE(td->td_pri_class); 2204 TD_SET_RUNQ(td); 2205 if (ts->ts_slice == 0) 2206 ts->ts_slice = sched_slice; 2207 /* 2208 * Pick the run queue based on priority. 2209 */ 2210 if (td->td_priority <= PRI_MAX_REALTIME) 2211 ts->ts_runq = &tdq->tdq_realtime; 2212 else if (td->td_priority <= PRI_MAX_TIMESHARE) 2213 ts->ts_runq = &tdq->tdq_timeshare; 2214 else 2215 ts->ts_runq = &tdq->tdq_idle; 2216 #ifdef SMP 2217 cpumask = 1 << ts->ts_cpu; 2218 /* 2219 * If we had been idle, clear our bit in the group and potentially 2220 * the global bitmap. 2221 */ 2222 if ((class != PRI_IDLE && class != PRI_ITHD) && 2223 (tdq->tdq_group->tdg_idlemask & cpumask) != 0) { 2224 /* 2225 * Check to see if our group is unidling, and if so, remove it 2226 * from the global idle mask. 2227 */ 2228 if (tdq->tdq_group->tdg_idlemask == 2229 tdq->tdq_group->tdg_cpumask) 2230 atomic_clear_int(&tdq_idle, tdq->tdq_group->tdg_mask); 2231 /* 2232 * Now remove ourselves from the group specific idle mask. 2233 */ 2234 tdq->tdq_group->tdg_idlemask &= ~cpumask; 2235 } 2236 if (td->td_priority < tdq->tdq_lowpri) 2237 tdq->tdq_lowpri = td->td_priority; 2238 #endif 2239 tdq_runq_add(tdq, ts, flags); 2240 tdq_load_add(tdq, ts); 2241 } 2242 2243 /* 2244 * Select the target thread queue and add a thread to it. Request 2245 * preemption or IPI a remote processor if required. 2246 */ 2247 void 2248 sched_add(struct thread *td, int flags) 2249 { 2250 struct td_sched *ts; 2251 struct tdq *tdq; 2252 #ifdef SMP 2253 int cpuid; 2254 int cpu; 2255 #endif 2256 CTR5(KTR_SCHED, "sched_add: %p(%s) prio %d by %p(%s)", 2257 td, td->td_proc->p_comm, td->td_priority, curthread, 2258 curthread->td_proc->p_comm); 2259 THREAD_LOCK_ASSERT(td, MA_OWNED); 2260 ts = td->td_sched; 2261 /* 2262 * Recalculate the priority before we select the target cpu or 2263 * run-queue. 2264 */ 2265 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 2266 sched_priority(td); 2267 #ifdef SMP 2268 cpuid = PCPU_GET(cpuid); 2269 /* 2270 * Pick the destination cpu and if it isn't ours transfer to the 2271 * target cpu. 2272 */ 2273 if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_MIGRATE(td)) 2274 cpu = cpuid; 2275 else if (!THREAD_CAN_MIGRATE(td)) 2276 cpu = ts->ts_cpu; 2277 else 2278 cpu = sched_pickcpu(ts, flags); 2279 tdq = sched_setcpu(ts, cpu, flags); 2280 tdq_add(tdq, td, flags); 2281 if (cpu != cpuid) { 2282 tdq_notify(ts); 2283 return; 2284 } 2285 #else 2286 tdq = TDQ_SELF(); 2287 TDQ_LOCK(tdq); 2288 /* 2289 * Now that the thread is moving to the run-queue, set the lock 2290 * to the scheduler's lock. 2291 */ 2292 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 2293 tdq_add(tdq, td, flags); 2294 #endif 2295 if (!(flags & SRQ_YIELDING)) 2296 sched_setpreempt(td); 2297 } 2298 2299 /* 2300 * Remove a thread from a run-queue without running it. This is used 2301 * when we're stealing a thread from a remote queue. Otherwise all threads 2302 * exit by calling sched_exit_thread() and sched_throw() themselves. 2303 */ 2304 void 2305 sched_rem(struct thread *td) 2306 { 2307 struct tdq *tdq; 2308 struct td_sched *ts; 2309 2310 CTR5(KTR_SCHED, "sched_rem: %p(%s) prio %d by %p(%s)", 2311 td, td->td_proc->p_comm, td->td_priority, curthread, 2312 curthread->td_proc->p_comm); 2313 ts = td->td_sched; 2314 tdq = TDQ_CPU(ts->ts_cpu); 2315 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2316 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2317 KASSERT(TD_ON_RUNQ(td), 2318 ("sched_rem: thread not on run queue")); 2319 tdq_runq_rem(tdq, ts); 2320 tdq_load_rem(tdq, ts); 2321 TD_SET_CAN_RUN(td); 2322 } 2323 2324 /* 2325 * Fetch cpu utilization information. Updates on demand. 2326 */ 2327 fixpt_t 2328 sched_pctcpu(struct thread *td) 2329 { 2330 fixpt_t pctcpu; 2331 struct td_sched *ts; 2332 2333 pctcpu = 0; 2334 ts = td->td_sched; 2335 if (ts == NULL) 2336 return (0); 2337 2338 thread_lock(td); 2339 if (ts->ts_ticks) { 2340 int rtick; 2341 2342 sched_pctcpu_update(ts); 2343 /* How many rtick per second ? */ 2344 rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz); 2345 pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT; 2346 } 2347 td->td_proc->p_swtime = ts->ts_ltick - ts->ts_ftick; 2348 thread_unlock(td); 2349 2350 return (pctcpu); 2351 } 2352 2353 /* 2354 * Bind a thread to a target cpu. 2355 */ 2356 void 2357 sched_bind(struct thread *td, int cpu) 2358 { 2359 struct td_sched *ts; 2360 2361 THREAD_LOCK_ASSERT(td, MA_OWNED); 2362 ts = td->td_sched; 2363 if (ts->ts_flags & TSF_BOUND) 2364 sched_unbind(td); 2365 ts->ts_flags |= TSF_BOUND; 2366 #ifdef SMP 2367 sched_pin(); 2368 if (PCPU_GET(cpuid) == cpu) 2369 return; 2370 ts->ts_cpu = cpu; 2371 /* When we return from mi_switch we'll be on the correct cpu. */ 2372 mi_switch(SW_VOL, NULL); 2373 #endif 2374 } 2375 2376 /* 2377 * Release a bound thread. 2378 */ 2379 void 2380 sched_unbind(struct thread *td) 2381 { 2382 struct td_sched *ts; 2383 2384 THREAD_LOCK_ASSERT(td, MA_OWNED); 2385 ts = td->td_sched; 2386 if ((ts->ts_flags & TSF_BOUND) == 0) 2387 return; 2388 ts->ts_flags &= ~TSF_BOUND; 2389 #ifdef SMP 2390 sched_unpin(); 2391 #endif 2392 } 2393 2394 int 2395 sched_is_bound(struct thread *td) 2396 { 2397 THREAD_LOCK_ASSERT(td, MA_OWNED); 2398 return (td->td_sched->ts_flags & TSF_BOUND); 2399 } 2400 2401 /* 2402 * Basic yield call. 2403 */ 2404 void 2405 sched_relinquish(struct thread *td) 2406 { 2407 thread_lock(td); 2408 if (td->td_pri_class == PRI_TIMESHARE) 2409 sched_prio(td, PRI_MAX_TIMESHARE); 2410 SCHED_STAT_INC(switch_relinquish); 2411 mi_switch(SW_VOL, NULL); 2412 thread_unlock(td); 2413 } 2414 2415 /* 2416 * Return the total system load. 2417 */ 2418 int 2419 sched_load(void) 2420 { 2421 #ifdef SMP 2422 int total; 2423 int i; 2424 2425 total = 0; 2426 for (i = 0; i <= tdg_maxid; i++) 2427 total += TDQ_GROUP(i)->tdg_load; 2428 return (total); 2429 #else 2430 return (TDQ_SELF()->tdq_sysload); 2431 #endif 2432 } 2433 2434 int 2435 sched_sizeof_proc(void) 2436 { 2437 return (sizeof(struct proc)); 2438 } 2439 2440 int 2441 sched_sizeof_thread(void) 2442 { 2443 return (sizeof(struct thread) + sizeof(struct td_sched)); 2444 } 2445 2446 /* 2447 * The actual idle process. 2448 */ 2449 void 2450 sched_idletd(void *dummy) 2451 { 2452 struct thread *td; 2453 struct tdq *tdq; 2454 2455 td = curthread; 2456 tdq = TDQ_SELF(); 2457 mtx_assert(&Giant, MA_NOTOWNED); 2458 /* ULE relies on preemption for idle interruption. */ 2459 for (;;) { 2460 #ifdef SMP 2461 if (tdq_idled(tdq)) 2462 cpu_idle(); 2463 #else 2464 cpu_idle(); 2465 #endif 2466 } 2467 } 2468 2469 /* 2470 * A CPU is entering for the first time or a thread is exiting. 2471 */ 2472 void 2473 sched_throw(struct thread *td) 2474 { 2475 struct tdq *tdq; 2476 2477 tdq = TDQ_SELF(); 2478 if (td == NULL) { 2479 /* Correct spinlock nesting and acquire the correct lock. */ 2480 TDQ_LOCK(tdq); 2481 spinlock_exit(); 2482 } else { 2483 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2484 tdq_load_rem(tdq, td->td_sched); 2485 } 2486 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 2487 PCPU_SET(switchtime, cpu_ticks()); 2488 PCPU_SET(switchticks, ticks); 2489 cpu_throw(td, choosethread()); /* doesn't return */ 2490 } 2491 2492 /* 2493 * This is called from fork_exit(). Just acquire the correct locks and 2494 * let fork do the rest of the work. 2495 */ 2496 void 2497 sched_fork_exit(struct thread *td) 2498 { 2499 struct td_sched *ts; 2500 struct tdq *tdq; 2501 int cpuid; 2502 2503 /* 2504 * Finish setting up thread glue so that it begins execution in a 2505 * non-nested critical section with the scheduler lock held. 2506 */ 2507 cpuid = PCPU_GET(cpuid); 2508 tdq = TDQ_CPU(cpuid); 2509 ts = td->td_sched; 2510 if (TD_IS_IDLETHREAD(td)) 2511 td->td_lock = TDQ_LOCKPTR(tdq); 2512 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2513 td->td_oncpu = cpuid; 2514 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)td; 2515 THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED); 2516 } 2517 2518 static SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0, 2519 "Scheduler"); 2520 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0, 2521 "Scheduler name"); 2522 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, 2523 "Slice size for timeshare threads"); 2524 SYSCTL_INT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0, 2525 "Interactivity score threshold"); 2526 SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW, &preempt_thresh, 2527 0,"Min priority for preemption, lower priorities have greater precedence"); 2528 #ifdef SMP 2529 SYSCTL_INT(_kern_sched, OID_AUTO, pick_pri, CTLFLAG_RW, &pick_pri, 0, 2530 "Pick the target cpu based on priority rather than load."); 2531 SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0, 2532 "Number of hz ticks to keep thread affinity for"); 2533 SYSCTL_INT(_kern_sched, OID_AUTO, tryself, CTLFLAG_RW, &tryself, 0, ""); 2534 SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0, 2535 "Enables the long-term load balancer"); 2536 SYSCTL_INT(_kern_sched, OID_AUTO, balance_secs, CTLFLAG_RW, &balance_secs, 0, 2537 "Average frequence in seconds to run the long-term balancer"); 2538 SYSCTL_INT(_kern_sched, OID_AUTO, steal_htt, CTLFLAG_RW, &steal_htt, 0, 2539 "Steals work from another hyper-threaded core on idle"); 2540 SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0, 2541 "Attempts to steal work from other cores before idling"); 2542 SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0, 2543 "Minimum load on remote cpu before we'll steal"); 2544 SYSCTL_INT(_kern_sched, OID_AUTO, topology, CTLFLAG_RD, &topology, 0, 2545 "True when a topology has been specified by the MD code."); 2546 #endif 2547 2548 /* ps compat */ 2549 static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */ 2550 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 2551 2552 2553 #define KERN_SWITCH_INCLUDE 1 2554 #include "kern/kern_switch.c" 2555