1 /*- 2 * Copyright (c) 2002-2007, Jeffrey Roberson <jeff@freebsd.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice unmodified, this list of conditions, and the following 10 * disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 /* 28 * This file implements the ULE scheduler. ULE supports independent CPU 29 * run queues and fine grain locking. It has superior interactive 30 * performance under load even on uni-processor systems. 31 * 32 * etymology: 33 * ULE is the last three letters in schedule. It owes its name to a 34 * generic user created for a scheduling system by Paul Mikesell at 35 * Isilon Systems and a general lack of creativity on the part of the author. 36 */ 37 38 #include <sys/cdefs.h> 39 __FBSDID("$FreeBSD$"); 40 41 #include "opt_hwpmc_hooks.h" 42 #include "opt_kdtrace.h" 43 #include "opt_sched.h" 44 45 #include <sys/param.h> 46 #include <sys/systm.h> 47 #include <sys/kdb.h> 48 #include <sys/kernel.h> 49 #include <sys/ktr.h> 50 #include <sys/lock.h> 51 #include <sys/mutex.h> 52 #include <sys/proc.h> 53 #include <sys/resource.h> 54 #include <sys/resourcevar.h> 55 #include <sys/sched.h> 56 #include <sys/sdt.h> 57 #include <sys/smp.h> 58 #include <sys/sx.h> 59 #include <sys/sysctl.h> 60 #include <sys/sysproto.h> 61 #include <sys/turnstile.h> 62 #include <sys/umtx.h> 63 #include <sys/vmmeter.h> 64 #include <sys/cpuset.h> 65 #include <sys/sbuf.h> 66 67 #ifdef HWPMC_HOOKS 68 #include <sys/pmckern.h> 69 #endif 70 71 #ifdef KDTRACE_HOOKS 72 #include <sys/dtrace_bsd.h> 73 int dtrace_vtime_active; 74 dtrace_vtime_switch_func_t dtrace_vtime_switch_func; 75 #endif 76 77 #include <machine/cpu.h> 78 #include <machine/smp.h> 79 80 #if defined(__powerpc__) && defined(BOOKE_E500) 81 #error "This architecture is not currently compatible with ULE" 82 #endif 83 84 #define KTR_ULE 0 85 86 #define TS_NAME_LEN (MAXCOMLEN + sizeof(" td ") + sizeof(__XSTRING(UINT_MAX))) 87 #define TDQ_NAME_LEN (sizeof("sched lock ") + sizeof(__XSTRING(MAXCPU))) 88 #define TDQ_LOADNAME_LEN (sizeof("CPU ") + sizeof(__XSTRING(MAXCPU)) - 1 + sizeof(" load")) 89 90 /* 91 * Thread scheduler specific section. All fields are protected 92 * by the thread lock. 93 */ 94 struct td_sched { 95 struct runq *ts_runq; /* Run-queue we're queued on. */ 96 short ts_flags; /* TSF_* flags. */ 97 u_char ts_cpu; /* CPU that we have affinity for. */ 98 int ts_rltick; /* Real last tick, for affinity. */ 99 int ts_slice; /* Ticks of slice remaining. */ 100 u_int ts_slptime; /* Number of ticks we vol. slept */ 101 u_int ts_runtime; /* Number of ticks we were running */ 102 int ts_ltick; /* Last tick that we were running on */ 103 int ts_ftick; /* First tick that we were running on */ 104 int ts_ticks; /* Tick count */ 105 #ifdef KTR 106 char ts_name[TS_NAME_LEN]; 107 #endif 108 }; 109 /* flags kept in ts_flags */ 110 #define TSF_BOUND 0x0001 /* Thread can not migrate. */ 111 #define TSF_XFERABLE 0x0002 /* Thread was added as transferable. */ 112 113 static struct td_sched td_sched0; 114 115 #define THREAD_CAN_MIGRATE(td) ((td)->td_pinned == 0) 116 #define THREAD_CAN_SCHED(td, cpu) \ 117 CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask) 118 119 /* 120 * Priority ranges used for interactive and non-interactive timeshare 121 * threads. The timeshare priorities are split up into four ranges. 122 * The first range handles interactive threads. The last three ranges 123 * (NHALF, x, and NHALF) handle non-interactive threads with the outer 124 * ranges supporting nice values. 125 */ 126 #define PRI_TIMESHARE_RANGE (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE + 1) 127 #define PRI_INTERACT_RANGE ((PRI_TIMESHARE_RANGE - SCHED_PRI_NRESV) / 2) 128 #define PRI_BATCH_RANGE (PRI_TIMESHARE_RANGE - PRI_INTERACT_RANGE) 129 130 #define PRI_MIN_INTERACT PRI_MIN_TIMESHARE 131 #define PRI_MAX_INTERACT (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE - 1) 132 #define PRI_MIN_BATCH (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE) 133 #define PRI_MAX_BATCH PRI_MAX_TIMESHARE 134 135 /* 136 * Cpu percentage computation macros and defines. 137 * 138 * SCHED_TICK_SECS: Number of seconds to average the cpu usage across. 139 * SCHED_TICK_TARG: Number of hz ticks to average the cpu usage across. 140 * SCHED_TICK_MAX: Maximum number of ticks before scaling back. 141 * SCHED_TICK_SHIFT: Shift factor to avoid rounding away results. 142 * SCHED_TICK_HZ: Compute the number of hz ticks for a given ticks count. 143 * SCHED_TICK_TOTAL: Gives the amount of time we've been recording ticks. 144 */ 145 #define SCHED_TICK_SECS 10 146 #define SCHED_TICK_TARG (hz * SCHED_TICK_SECS) 147 #define SCHED_TICK_MAX (SCHED_TICK_TARG + hz) 148 #define SCHED_TICK_SHIFT 10 149 #define SCHED_TICK_HZ(ts) ((ts)->ts_ticks >> SCHED_TICK_SHIFT) 150 #define SCHED_TICK_TOTAL(ts) (max((ts)->ts_ltick - (ts)->ts_ftick, hz)) 151 152 /* 153 * These macros determine priorities for non-interactive threads. They are 154 * assigned a priority based on their recent cpu utilization as expressed 155 * by the ratio of ticks to the tick total. NHALF priorities at the start 156 * and end of the MIN to MAX timeshare range are only reachable with negative 157 * or positive nice respectively. 158 * 159 * PRI_RANGE: Priority range for utilization dependent priorities. 160 * PRI_NRESV: Number of nice values. 161 * PRI_TICKS: Compute a priority in PRI_RANGE from the ticks count and total. 162 * PRI_NICE: Determines the part of the priority inherited from nice. 163 */ 164 #define SCHED_PRI_NRESV (PRIO_MAX - PRIO_MIN) 165 #define SCHED_PRI_NHALF (SCHED_PRI_NRESV / 2) 166 #define SCHED_PRI_MIN (PRI_MIN_BATCH + SCHED_PRI_NHALF) 167 #define SCHED_PRI_MAX (PRI_MAX_BATCH - SCHED_PRI_NHALF) 168 #define SCHED_PRI_RANGE (SCHED_PRI_MAX - SCHED_PRI_MIN + 1) 169 #define SCHED_PRI_TICKS(ts) \ 170 (SCHED_TICK_HZ((ts)) / \ 171 (roundup(SCHED_TICK_TOTAL((ts)), SCHED_PRI_RANGE) / SCHED_PRI_RANGE)) 172 #define SCHED_PRI_NICE(nice) (nice) 173 174 /* 175 * These determine the interactivity of a process. Interactivity differs from 176 * cpu utilization in that it expresses the voluntary time slept vs time ran 177 * while cpu utilization includes all time not running. This more accurately 178 * models the intent of the thread. 179 * 180 * SLP_RUN_MAX: Maximum amount of sleep time + run time we'll accumulate 181 * before throttling back. 182 * SLP_RUN_FORK: Maximum slp+run time to inherit at fork time. 183 * INTERACT_MAX: Maximum interactivity value. Smaller is better. 184 * INTERACT_THRESH: Threshold for placement on the current runq. 185 */ 186 #define SCHED_SLP_RUN_MAX ((hz * 5) << SCHED_TICK_SHIFT) 187 #define SCHED_SLP_RUN_FORK ((hz / 2) << SCHED_TICK_SHIFT) 188 #define SCHED_INTERACT_MAX (100) 189 #define SCHED_INTERACT_HALF (SCHED_INTERACT_MAX / 2) 190 #define SCHED_INTERACT_THRESH (30) 191 192 /* 193 * tickincr: Converts a stathz tick into a hz domain scaled by 194 * the shift factor. Without the shift the error rate 195 * due to rounding would be unacceptably high. 196 * realstathz: stathz is sometimes 0 and run off of hz. 197 * sched_slice: Runtime of each thread before rescheduling. 198 * preempt_thresh: Priority threshold for preemption and remote IPIs. 199 */ 200 static int sched_interact = SCHED_INTERACT_THRESH; 201 static int realstathz; 202 static int tickincr; 203 static int sched_slice = 1; 204 #ifdef PREEMPTION 205 #ifdef FULL_PREEMPTION 206 static int preempt_thresh = PRI_MAX_IDLE; 207 #else 208 static int preempt_thresh = PRI_MIN_KERN; 209 #endif 210 #else 211 static int preempt_thresh = 0; 212 #endif 213 static int static_boost = PRI_MIN_BATCH; 214 static int sched_idlespins = 10000; 215 static int sched_idlespinthresh = -1; 216 217 /* 218 * tdq - per processor runqs and statistics. All fields are protected by the 219 * tdq_lock. The load and lowpri may be accessed without to avoid excess 220 * locking in sched_pickcpu(); 221 */ 222 struct tdq { 223 /* Ordered to improve efficiency of cpu_search() and switch(). */ 224 struct mtx tdq_lock; /* run queue lock. */ 225 struct cpu_group *tdq_cg; /* Pointer to cpu topology. */ 226 volatile int tdq_load; /* Aggregate load. */ 227 volatile int tdq_cpu_idle; /* cpu_idle() is active. */ 228 int tdq_sysload; /* For loadavg, !ITHD load. */ 229 int tdq_transferable; /* Transferable thread count. */ 230 short tdq_switchcnt; /* Switches this tick. */ 231 short tdq_oldswitchcnt; /* Switches last tick. */ 232 u_char tdq_lowpri; /* Lowest priority thread. */ 233 u_char tdq_ipipending; /* IPI pending. */ 234 u_char tdq_idx; /* Current insert index. */ 235 u_char tdq_ridx; /* Current removal index. */ 236 struct runq tdq_realtime; /* real-time run queue. */ 237 struct runq tdq_timeshare; /* timeshare run queue. */ 238 struct runq tdq_idle; /* Queue of IDLE threads. */ 239 char tdq_name[TDQ_NAME_LEN]; 240 #ifdef KTR 241 char tdq_loadname[TDQ_LOADNAME_LEN]; 242 #endif 243 } __aligned(64); 244 245 /* Idle thread states and config. */ 246 #define TDQ_RUNNING 1 247 #define TDQ_IDLE 2 248 249 #ifdef SMP 250 struct cpu_group *cpu_top; /* CPU topology */ 251 252 #define SCHED_AFFINITY_DEFAULT (max(1, hz / 1000)) 253 #define SCHED_AFFINITY(ts, t) ((ts)->ts_rltick > ticks - ((t) * affinity)) 254 255 /* 256 * Run-time tunables. 257 */ 258 static int rebalance = 1; 259 static int balance_interval = 128; /* Default set in sched_initticks(). */ 260 static int affinity; 261 static int steal_idle = 1; 262 static int steal_thresh = 2; 263 264 /* 265 * One thread queue per processor. 266 */ 267 static struct tdq tdq_cpu[MAXCPU]; 268 static struct tdq *balance_tdq; 269 static int balance_ticks; 270 static DPCPU_DEFINE(uint32_t, randomval); 271 272 #define TDQ_SELF() (&tdq_cpu[PCPU_GET(cpuid)]) 273 #define TDQ_CPU(x) (&tdq_cpu[(x)]) 274 #define TDQ_ID(x) ((int)((x) - tdq_cpu)) 275 #else /* !SMP */ 276 static struct tdq tdq_cpu; 277 278 #define TDQ_ID(x) (0) 279 #define TDQ_SELF() (&tdq_cpu) 280 #define TDQ_CPU(x) (&tdq_cpu) 281 #endif 282 283 #define TDQ_LOCK_ASSERT(t, type) mtx_assert(TDQ_LOCKPTR((t)), (type)) 284 #define TDQ_LOCK(t) mtx_lock_spin(TDQ_LOCKPTR((t))) 285 #define TDQ_LOCK_FLAGS(t, f) mtx_lock_spin_flags(TDQ_LOCKPTR((t)), (f)) 286 #define TDQ_UNLOCK(t) mtx_unlock_spin(TDQ_LOCKPTR((t))) 287 #define TDQ_LOCKPTR(t) (&(t)->tdq_lock) 288 289 static void sched_priority(struct thread *); 290 static void sched_thread_priority(struct thread *, u_char); 291 static int sched_interact_score(struct thread *); 292 static void sched_interact_update(struct thread *); 293 static void sched_interact_fork(struct thread *); 294 static void sched_pctcpu_update(struct td_sched *, int); 295 296 /* Operations on per processor queues */ 297 static struct thread *tdq_choose(struct tdq *); 298 static void tdq_setup(struct tdq *); 299 static void tdq_load_add(struct tdq *, struct thread *); 300 static void tdq_load_rem(struct tdq *, struct thread *); 301 static __inline void tdq_runq_add(struct tdq *, struct thread *, int); 302 static __inline void tdq_runq_rem(struct tdq *, struct thread *); 303 static inline int sched_shouldpreempt(int, int, int); 304 void tdq_print(int cpu); 305 static void runq_print(struct runq *rq); 306 static void tdq_add(struct tdq *, struct thread *, int); 307 #ifdef SMP 308 static int tdq_move(struct tdq *, struct tdq *); 309 static int tdq_idled(struct tdq *); 310 static void tdq_notify(struct tdq *, struct thread *); 311 static struct thread *tdq_steal(struct tdq *, int); 312 static struct thread *runq_steal(struct runq *, int); 313 static int sched_pickcpu(struct thread *, int); 314 static void sched_balance(void); 315 static int sched_balance_pair(struct tdq *, struct tdq *); 316 static inline struct tdq *sched_setcpu(struct thread *, int, int); 317 static inline void thread_unblock_switch(struct thread *, struct mtx *); 318 static struct mtx *sched_switch_migrate(struct tdq *, struct thread *, int); 319 static int sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS); 320 static int sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, 321 struct cpu_group *cg, int indent); 322 #endif 323 324 static void sched_setup(void *dummy); 325 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL); 326 327 static void sched_initticks(void *dummy); 328 SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks, 329 NULL); 330 331 SDT_PROVIDER_DEFINE(sched); 332 333 SDT_PROBE_DEFINE3(sched, , , change_pri, change-pri, "struct thread *", 334 "struct proc *", "uint8_t"); 335 SDT_PROBE_DEFINE3(sched, , , dequeue, dequeue, "struct thread *", 336 "struct proc *", "void *"); 337 SDT_PROBE_DEFINE4(sched, , , enqueue, enqueue, "struct thread *", 338 "struct proc *", "void *", "int"); 339 SDT_PROBE_DEFINE4(sched, , , lend_pri, lend-pri, "struct thread *", 340 "struct proc *", "uint8_t", "struct thread *"); 341 SDT_PROBE_DEFINE2(sched, , , load_change, load-change, "int", "int"); 342 SDT_PROBE_DEFINE2(sched, , , off_cpu, off-cpu, "struct thread *", 343 "struct proc *"); 344 SDT_PROBE_DEFINE(sched, , , on_cpu, on-cpu); 345 SDT_PROBE_DEFINE(sched, , , remain_cpu, remain-cpu); 346 SDT_PROBE_DEFINE2(sched, , , surrender, surrender, "struct thread *", 347 "struct proc *"); 348 349 /* 350 * Print the threads waiting on a run-queue. 351 */ 352 static void 353 runq_print(struct runq *rq) 354 { 355 struct rqhead *rqh; 356 struct thread *td; 357 int pri; 358 int j; 359 int i; 360 361 for (i = 0; i < RQB_LEN; i++) { 362 printf("\t\trunq bits %d 0x%zx\n", 363 i, rq->rq_status.rqb_bits[i]); 364 for (j = 0; j < RQB_BPW; j++) 365 if (rq->rq_status.rqb_bits[i] & (1ul << j)) { 366 pri = j + (i << RQB_L2BPW); 367 rqh = &rq->rq_queues[pri]; 368 TAILQ_FOREACH(td, rqh, td_runq) { 369 printf("\t\t\ttd %p(%s) priority %d rqindex %d pri %d\n", 370 td, td->td_name, td->td_priority, 371 td->td_rqindex, pri); 372 } 373 } 374 } 375 } 376 377 /* 378 * Print the status of a per-cpu thread queue. Should be a ddb show cmd. 379 */ 380 void 381 tdq_print(int cpu) 382 { 383 struct tdq *tdq; 384 385 tdq = TDQ_CPU(cpu); 386 387 printf("tdq %d:\n", TDQ_ID(tdq)); 388 printf("\tlock %p\n", TDQ_LOCKPTR(tdq)); 389 printf("\tLock name: %s\n", tdq->tdq_name); 390 printf("\tload: %d\n", tdq->tdq_load); 391 printf("\tswitch cnt: %d\n", tdq->tdq_switchcnt); 392 printf("\told switch cnt: %d\n", tdq->tdq_oldswitchcnt); 393 printf("\ttimeshare idx: %d\n", tdq->tdq_idx); 394 printf("\ttimeshare ridx: %d\n", tdq->tdq_ridx); 395 printf("\tload transferable: %d\n", tdq->tdq_transferable); 396 printf("\tlowest priority: %d\n", tdq->tdq_lowpri); 397 printf("\trealtime runq:\n"); 398 runq_print(&tdq->tdq_realtime); 399 printf("\ttimeshare runq:\n"); 400 runq_print(&tdq->tdq_timeshare); 401 printf("\tidle runq:\n"); 402 runq_print(&tdq->tdq_idle); 403 } 404 405 static inline int 406 sched_shouldpreempt(int pri, int cpri, int remote) 407 { 408 /* 409 * If the new priority is not better than the current priority there is 410 * nothing to do. 411 */ 412 if (pri >= cpri) 413 return (0); 414 /* 415 * Always preempt idle. 416 */ 417 if (cpri >= PRI_MIN_IDLE) 418 return (1); 419 /* 420 * If preemption is disabled don't preempt others. 421 */ 422 if (preempt_thresh == 0) 423 return (0); 424 /* 425 * Preempt if we exceed the threshold. 426 */ 427 if (pri <= preempt_thresh) 428 return (1); 429 /* 430 * If we're interactive or better and there is non-interactive 431 * or worse running preempt only remote processors. 432 */ 433 if (remote && pri <= PRI_MAX_INTERACT && cpri > PRI_MAX_INTERACT) 434 return (1); 435 return (0); 436 } 437 438 /* 439 * Add a thread to the actual run-queue. Keeps transferable counts up to 440 * date with what is actually on the run-queue. Selects the correct 441 * queue position for timeshare threads. 442 */ 443 static __inline void 444 tdq_runq_add(struct tdq *tdq, struct thread *td, int flags) 445 { 446 struct td_sched *ts; 447 u_char pri; 448 449 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 450 THREAD_LOCK_ASSERT(td, MA_OWNED); 451 452 pri = td->td_priority; 453 ts = td->td_sched; 454 TD_SET_RUNQ(td); 455 if (THREAD_CAN_MIGRATE(td)) { 456 tdq->tdq_transferable++; 457 ts->ts_flags |= TSF_XFERABLE; 458 } 459 if (pri < PRI_MIN_BATCH) { 460 ts->ts_runq = &tdq->tdq_realtime; 461 } else if (pri <= PRI_MAX_BATCH) { 462 ts->ts_runq = &tdq->tdq_timeshare; 463 KASSERT(pri <= PRI_MAX_BATCH && pri >= PRI_MIN_BATCH, 464 ("Invalid priority %d on timeshare runq", pri)); 465 /* 466 * This queue contains only priorities between MIN and MAX 467 * realtime. Use the whole queue to represent these values. 468 */ 469 if ((flags & (SRQ_BORROWING|SRQ_PREEMPTED)) == 0) { 470 pri = RQ_NQS * (pri - PRI_MIN_BATCH) / PRI_BATCH_RANGE; 471 pri = (pri + tdq->tdq_idx) % RQ_NQS; 472 /* 473 * This effectively shortens the queue by one so we 474 * can have a one slot difference between idx and 475 * ridx while we wait for threads to drain. 476 */ 477 if (tdq->tdq_ridx != tdq->tdq_idx && 478 pri == tdq->tdq_ridx) 479 pri = (unsigned char)(pri - 1) % RQ_NQS; 480 } else 481 pri = tdq->tdq_ridx; 482 runq_add_pri(ts->ts_runq, td, pri, flags); 483 return; 484 } else 485 ts->ts_runq = &tdq->tdq_idle; 486 runq_add(ts->ts_runq, td, flags); 487 } 488 489 /* 490 * Remove a thread from a run-queue. This typically happens when a thread 491 * is selected to run. Running threads are not on the queue and the 492 * transferable count does not reflect them. 493 */ 494 static __inline void 495 tdq_runq_rem(struct tdq *tdq, struct thread *td) 496 { 497 struct td_sched *ts; 498 499 ts = td->td_sched; 500 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 501 KASSERT(ts->ts_runq != NULL, 502 ("tdq_runq_remove: thread %p null ts_runq", td)); 503 if (ts->ts_flags & TSF_XFERABLE) { 504 tdq->tdq_transferable--; 505 ts->ts_flags &= ~TSF_XFERABLE; 506 } 507 if (ts->ts_runq == &tdq->tdq_timeshare) { 508 if (tdq->tdq_idx != tdq->tdq_ridx) 509 runq_remove_idx(ts->ts_runq, td, &tdq->tdq_ridx); 510 else 511 runq_remove_idx(ts->ts_runq, td, NULL); 512 } else 513 runq_remove(ts->ts_runq, td); 514 } 515 516 /* 517 * Load is maintained for all threads RUNNING and ON_RUNQ. Add the load 518 * for this thread to the referenced thread queue. 519 */ 520 static void 521 tdq_load_add(struct tdq *tdq, struct thread *td) 522 { 523 524 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 525 THREAD_LOCK_ASSERT(td, MA_OWNED); 526 527 tdq->tdq_load++; 528 if ((td->td_flags & TDF_NOLOAD) == 0) 529 tdq->tdq_sysload++; 530 KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load); 531 SDT_PROBE2(sched, , , load_change, (int)TDQ_ID(tdq), tdq->tdq_load); 532 } 533 534 /* 535 * Remove the load from a thread that is transitioning to a sleep state or 536 * exiting. 537 */ 538 static void 539 tdq_load_rem(struct tdq *tdq, struct thread *td) 540 { 541 542 THREAD_LOCK_ASSERT(td, MA_OWNED); 543 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 544 KASSERT(tdq->tdq_load != 0, 545 ("tdq_load_rem: Removing with 0 load on queue %d", TDQ_ID(tdq))); 546 547 tdq->tdq_load--; 548 if ((td->td_flags & TDF_NOLOAD) == 0) 549 tdq->tdq_sysload--; 550 KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load); 551 SDT_PROBE2(sched, , , load_change, (int)TDQ_ID(tdq), tdq->tdq_load); 552 } 553 554 /* 555 * Set lowpri to its exact value by searching the run-queue and 556 * evaluating curthread. curthread may be passed as an optimization. 557 */ 558 static void 559 tdq_setlowpri(struct tdq *tdq, struct thread *ctd) 560 { 561 struct thread *td; 562 563 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 564 if (ctd == NULL) 565 ctd = pcpu_find(TDQ_ID(tdq))->pc_curthread; 566 td = tdq_choose(tdq); 567 if (td == NULL || td->td_priority > ctd->td_priority) 568 tdq->tdq_lowpri = ctd->td_priority; 569 else 570 tdq->tdq_lowpri = td->td_priority; 571 } 572 573 #ifdef SMP 574 struct cpu_search { 575 cpuset_t cs_mask; 576 u_int cs_prefer; 577 int cs_pri; /* Min priority for low. */ 578 int cs_limit; /* Max load for low, min load for high. */ 579 int cs_cpu; 580 int cs_load; 581 }; 582 583 #define CPU_SEARCH_LOWEST 0x1 584 #define CPU_SEARCH_HIGHEST 0x2 585 #define CPU_SEARCH_BOTH (CPU_SEARCH_LOWEST|CPU_SEARCH_HIGHEST) 586 587 #define CPUSET_FOREACH(cpu, mask) \ 588 for ((cpu) = 0; (cpu) <= mp_maxid; (cpu)++) \ 589 if (CPU_ISSET(cpu, &mask)) 590 591 static __inline int cpu_search(const struct cpu_group *cg, struct cpu_search *low, 592 struct cpu_search *high, const int match); 593 int cpu_search_lowest(const struct cpu_group *cg, struct cpu_search *low); 594 int cpu_search_highest(const struct cpu_group *cg, struct cpu_search *high); 595 int cpu_search_both(const struct cpu_group *cg, struct cpu_search *low, 596 struct cpu_search *high); 597 598 /* 599 * Search the tree of cpu_groups for the lowest or highest loaded cpu 600 * according to the match argument. This routine actually compares the 601 * load on all paths through the tree and finds the least loaded cpu on 602 * the least loaded path, which may differ from the least loaded cpu in 603 * the system. This balances work among caches and busses. 604 * 605 * This inline is instantiated in three forms below using constants for the 606 * match argument. It is reduced to the minimum set for each case. It is 607 * also recursive to the depth of the tree. 608 */ 609 static __inline int 610 cpu_search(const struct cpu_group *cg, struct cpu_search *low, 611 struct cpu_search *high, const int match) 612 { 613 struct cpu_search lgroup; 614 struct cpu_search hgroup; 615 cpuset_t cpumask; 616 struct cpu_group *child; 617 struct tdq *tdq; 618 int cpu, i, hload, lload, load, total, rnd, *rndptr; 619 620 total = 0; 621 cpumask = cg->cg_mask; 622 if (match & CPU_SEARCH_LOWEST) { 623 lload = INT_MAX; 624 lgroup = *low; 625 } 626 if (match & CPU_SEARCH_HIGHEST) { 627 hload = INT_MIN; 628 hgroup = *high; 629 } 630 631 /* Iterate through the child CPU groups and then remaining CPUs. */ 632 for (i = cg->cg_children, cpu = mp_maxid; i >= 0; ) { 633 if (i == 0) { 634 while (cpu >= 0 && !CPU_ISSET(cpu, &cpumask)) 635 cpu--; 636 if (cpu < 0) 637 break; 638 child = NULL; 639 } else 640 child = &cg->cg_child[i - 1]; 641 642 if (match & CPU_SEARCH_LOWEST) 643 lgroup.cs_cpu = -1; 644 if (match & CPU_SEARCH_HIGHEST) 645 hgroup.cs_cpu = -1; 646 if (child) { /* Handle child CPU group. */ 647 CPU_NAND(&cpumask, &child->cg_mask); 648 switch (match) { 649 case CPU_SEARCH_LOWEST: 650 load = cpu_search_lowest(child, &lgroup); 651 break; 652 case CPU_SEARCH_HIGHEST: 653 load = cpu_search_highest(child, &hgroup); 654 break; 655 case CPU_SEARCH_BOTH: 656 load = cpu_search_both(child, &lgroup, &hgroup); 657 break; 658 } 659 } else { /* Handle child CPU. */ 660 tdq = TDQ_CPU(cpu); 661 load = tdq->tdq_load * 256; 662 rndptr = DPCPU_PTR(randomval); 663 rnd = (*rndptr = *rndptr * 69069 + 5) >> 26; 664 if (match & CPU_SEARCH_LOWEST) { 665 if (cpu == low->cs_prefer) 666 load -= 64; 667 /* If that CPU is allowed and get data. */ 668 if (tdq->tdq_lowpri > lgroup.cs_pri && 669 tdq->tdq_load <= lgroup.cs_limit && 670 CPU_ISSET(cpu, &lgroup.cs_mask)) { 671 lgroup.cs_cpu = cpu; 672 lgroup.cs_load = load - rnd; 673 } 674 } 675 if (match & CPU_SEARCH_HIGHEST) 676 if (tdq->tdq_load >= hgroup.cs_limit && 677 tdq->tdq_transferable && 678 CPU_ISSET(cpu, &hgroup.cs_mask)) { 679 hgroup.cs_cpu = cpu; 680 hgroup.cs_load = load - rnd; 681 } 682 } 683 total += load; 684 685 /* We have info about child item. Compare it. */ 686 if (match & CPU_SEARCH_LOWEST) { 687 if (lgroup.cs_cpu >= 0 && 688 (load < lload || 689 (load == lload && lgroup.cs_load < low->cs_load))) { 690 lload = load; 691 low->cs_cpu = lgroup.cs_cpu; 692 low->cs_load = lgroup.cs_load; 693 } 694 } 695 if (match & CPU_SEARCH_HIGHEST) 696 if (hgroup.cs_cpu >= 0 && 697 (load > hload || 698 (load == hload && hgroup.cs_load > high->cs_load))) { 699 hload = load; 700 high->cs_cpu = hgroup.cs_cpu; 701 high->cs_load = hgroup.cs_load; 702 } 703 if (child) { 704 i--; 705 if (i == 0 && CPU_EMPTY(&cpumask)) 706 break; 707 } else 708 cpu--; 709 } 710 return (total); 711 } 712 713 /* 714 * cpu_search instantiations must pass constants to maintain the inline 715 * optimization. 716 */ 717 int 718 cpu_search_lowest(const struct cpu_group *cg, struct cpu_search *low) 719 { 720 return cpu_search(cg, low, NULL, CPU_SEARCH_LOWEST); 721 } 722 723 int 724 cpu_search_highest(const struct cpu_group *cg, struct cpu_search *high) 725 { 726 return cpu_search(cg, NULL, high, CPU_SEARCH_HIGHEST); 727 } 728 729 int 730 cpu_search_both(const struct cpu_group *cg, struct cpu_search *low, 731 struct cpu_search *high) 732 { 733 return cpu_search(cg, low, high, CPU_SEARCH_BOTH); 734 } 735 736 /* 737 * Find the cpu with the least load via the least loaded path that has a 738 * lowpri greater than pri pri. A pri of -1 indicates any priority is 739 * acceptable. 740 */ 741 static inline int 742 sched_lowest(const struct cpu_group *cg, cpuset_t mask, int pri, int maxload, 743 int prefer) 744 { 745 struct cpu_search low; 746 747 low.cs_cpu = -1; 748 low.cs_prefer = prefer; 749 low.cs_mask = mask; 750 low.cs_pri = pri; 751 low.cs_limit = maxload; 752 cpu_search_lowest(cg, &low); 753 return low.cs_cpu; 754 } 755 756 /* 757 * Find the cpu with the highest load via the highest loaded path. 758 */ 759 static inline int 760 sched_highest(const struct cpu_group *cg, cpuset_t mask, int minload) 761 { 762 struct cpu_search high; 763 764 high.cs_cpu = -1; 765 high.cs_mask = mask; 766 high.cs_limit = minload; 767 cpu_search_highest(cg, &high); 768 return high.cs_cpu; 769 } 770 771 /* 772 * Simultaneously find the highest and lowest loaded cpu reachable via 773 * cg. 774 */ 775 static inline void 776 sched_both(const struct cpu_group *cg, cpuset_t mask, int *lowcpu, int *highcpu) 777 { 778 struct cpu_search high; 779 struct cpu_search low; 780 781 low.cs_cpu = -1; 782 low.cs_prefer = -1; 783 low.cs_pri = -1; 784 low.cs_limit = INT_MAX; 785 low.cs_mask = mask; 786 high.cs_cpu = -1; 787 high.cs_limit = -1; 788 high.cs_mask = mask; 789 cpu_search_both(cg, &low, &high); 790 *lowcpu = low.cs_cpu; 791 *highcpu = high.cs_cpu; 792 return; 793 } 794 795 static void 796 sched_balance_group(struct cpu_group *cg) 797 { 798 cpuset_t hmask, lmask; 799 int high, low, anylow; 800 801 CPU_FILL(&hmask); 802 for (;;) { 803 high = sched_highest(cg, hmask, 1); 804 /* Stop if there is no more CPU with transferrable threads. */ 805 if (high == -1) 806 break; 807 CPU_CLR(high, &hmask); 808 CPU_COPY(&hmask, &lmask); 809 /* Stop if there is no more CPU left for low. */ 810 if (CPU_EMPTY(&lmask)) 811 break; 812 anylow = 1; 813 nextlow: 814 low = sched_lowest(cg, lmask, -1, 815 TDQ_CPU(high)->tdq_load - 1, high); 816 /* Stop if we looked well and found no less loaded CPU. */ 817 if (anylow && low == -1) 818 break; 819 /* Go to next high if we found no less loaded CPU. */ 820 if (low == -1) 821 continue; 822 /* Transfer thread from high to low. */ 823 if (sched_balance_pair(TDQ_CPU(high), TDQ_CPU(low))) { 824 /* CPU that got thread can no longer be a donor. */ 825 CPU_CLR(low, &hmask); 826 } else { 827 /* 828 * If failed, then there is no threads on high 829 * that can run on this low. Drop low from low 830 * mask and look for different one. 831 */ 832 CPU_CLR(low, &lmask); 833 anylow = 0; 834 goto nextlow; 835 } 836 } 837 } 838 839 static void 840 sched_balance(void) 841 { 842 struct tdq *tdq; 843 844 /* 845 * Select a random time between .5 * balance_interval and 846 * 1.5 * balance_interval. 847 */ 848 balance_ticks = max(balance_interval / 2, 1); 849 balance_ticks += random() % balance_interval; 850 if (smp_started == 0 || rebalance == 0) 851 return; 852 tdq = TDQ_SELF(); 853 TDQ_UNLOCK(tdq); 854 sched_balance_group(cpu_top); 855 TDQ_LOCK(tdq); 856 } 857 858 /* 859 * Lock two thread queues using their address to maintain lock order. 860 */ 861 static void 862 tdq_lock_pair(struct tdq *one, struct tdq *two) 863 { 864 if (one < two) { 865 TDQ_LOCK(one); 866 TDQ_LOCK_FLAGS(two, MTX_DUPOK); 867 } else { 868 TDQ_LOCK(two); 869 TDQ_LOCK_FLAGS(one, MTX_DUPOK); 870 } 871 } 872 873 /* 874 * Unlock two thread queues. Order is not important here. 875 */ 876 static void 877 tdq_unlock_pair(struct tdq *one, struct tdq *two) 878 { 879 TDQ_UNLOCK(one); 880 TDQ_UNLOCK(two); 881 } 882 883 /* 884 * Transfer load between two imbalanced thread queues. 885 */ 886 static int 887 sched_balance_pair(struct tdq *high, struct tdq *low) 888 { 889 int moved; 890 int cpu; 891 892 tdq_lock_pair(high, low); 893 moved = 0; 894 /* 895 * Determine what the imbalance is and then adjust that to how many 896 * threads we actually have to give up (transferable). 897 */ 898 if (high->tdq_transferable != 0 && high->tdq_load > low->tdq_load && 899 (moved = tdq_move(high, low)) > 0) { 900 /* 901 * In case the target isn't the current cpu IPI it to force a 902 * reschedule with the new workload. 903 */ 904 cpu = TDQ_ID(low); 905 sched_pin(); 906 if (cpu != PCPU_GET(cpuid)) 907 ipi_cpu(cpu, IPI_PREEMPT); 908 sched_unpin(); 909 } 910 tdq_unlock_pair(high, low); 911 return (moved); 912 } 913 914 /* 915 * Move a thread from one thread queue to another. 916 */ 917 static int 918 tdq_move(struct tdq *from, struct tdq *to) 919 { 920 struct td_sched *ts; 921 struct thread *td; 922 struct tdq *tdq; 923 int cpu; 924 925 TDQ_LOCK_ASSERT(from, MA_OWNED); 926 TDQ_LOCK_ASSERT(to, MA_OWNED); 927 928 tdq = from; 929 cpu = TDQ_ID(to); 930 td = tdq_steal(tdq, cpu); 931 if (td == NULL) 932 return (0); 933 ts = td->td_sched; 934 /* 935 * Although the run queue is locked the thread may be blocked. Lock 936 * it to clear this and acquire the run-queue lock. 937 */ 938 thread_lock(td); 939 /* Drop recursive lock on from acquired via thread_lock(). */ 940 TDQ_UNLOCK(from); 941 sched_rem(td); 942 ts->ts_cpu = cpu; 943 td->td_lock = TDQ_LOCKPTR(to); 944 tdq_add(to, td, SRQ_YIELDING); 945 return (1); 946 } 947 948 /* 949 * This tdq has idled. Try to steal a thread from another cpu and switch 950 * to it. 951 */ 952 static int 953 tdq_idled(struct tdq *tdq) 954 { 955 struct cpu_group *cg; 956 struct tdq *steal; 957 cpuset_t mask; 958 int thresh; 959 int cpu; 960 961 if (smp_started == 0 || steal_idle == 0) 962 return (1); 963 CPU_FILL(&mask); 964 CPU_CLR(PCPU_GET(cpuid), &mask); 965 /* We don't want to be preempted while we're iterating. */ 966 spinlock_enter(); 967 for (cg = tdq->tdq_cg; cg != NULL; ) { 968 if ((cg->cg_flags & CG_FLAG_THREAD) == 0) 969 thresh = steal_thresh; 970 else 971 thresh = 1; 972 cpu = sched_highest(cg, mask, thresh); 973 if (cpu == -1) { 974 cg = cg->cg_parent; 975 continue; 976 } 977 steal = TDQ_CPU(cpu); 978 CPU_CLR(cpu, &mask); 979 tdq_lock_pair(tdq, steal); 980 if (steal->tdq_load < thresh || steal->tdq_transferable == 0) { 981 tdq_unlock_pair(tdq, steal); 982 continue; 983 } 984 /* 985 * If a thread was added while interrupts were disabled don't 986 * steal one here. If we fail to acquire one due to affinity 987 * restrictions loop again with this cpu removed from the 988 * set. 989 */ 990 if (tdq->tdq_load == 0 && tdq_move(steal, tdq) == 0) { 991 tdq_unlock_pair(tdq, steal); 992 continue; 993 } 994 spinlock_exit(); 995 TDQ_UNLOCK(steal); 996 mi_switch(SW_VOL | SWT_IDLE, NULL); 997 thread_unlock(curthread); 998 999 return (0); 1000 } 1001 spinlock_exit(); 1002 return (1); 1003 } 1004 1005 /* 1006 * Notify a remote cpu of new work. Sends an IPI if criteria are met. 1007 */ 1008 static void 1009 tdq_notify(struct tdq *tdq, struct thread *td) 1010 { 1011 struct thread *ctd; 1012 int pri; 1013 int cpu; 1014 1015 if (tdq->tdq_ipipending) 1016 return; 1017 cpu = td->td_sched->ts_cpu; 1018 pri = td->td_priority; 1019 ctd = pcpu_find(cpu)->pc_curthread; 1020 if (!sched_shouldpreempt(pri, ctd->td_priority, 1)) 1021 return; 1022 if (TD_IS_IDLETHREAD(ctd)) { 1023 /* 1024 * If the MD code has an idle wakeup routine try that before 1025 * falling back to IPI. 1026 */ 1027 if (!tdq->tdq_cpu_idle || cpu_idle_wakeup(cpu)) 1028 return; 1029 } 1030 tdq->tdq_ipipending = 1; 1031 ipi_cpu(cpu, IPI_PREEMPT); 1032 } 1033 1034 /* 1035 * Steals load from a timeshare queue. Honors the rotating queue head 1036 * index. 1037 */ 1038 static struct thread * 1039 runq_steal_from(struct runq *rq, int cpu, u_char start) 1040 { 1041 struct rqbits *rqb; 1042 struct rqhead *rqh; 1043 struct thread *td, *first; 1044 int bit; 1045 int pri; 1046 int i; 1047 1048 rqb = &rq->rq_status; 1049 bit = start & (RQB_BPW -1); 1050 pri = 0; 1051 first = NULL; 1052 again: 1053 for (i = RQB_WORD(start); i < RQB_LEN; bit = 0, i++) { 1054 if (rqb->rqb_bits[i] == 0) 1055 continue; 1056 if (bit != 0) { 1057 for (pri = bit; pri < RQB_BPW; pri++) 1058 if (rqb->rqb_bits[i] & (1ul << pri)) 1059 break; 1060 if (pri >= RQB_BPW) 1061 continue; 1062 } else 1063 pri = RQB_FFS(rqb->rqb_bits[i]); 1064 pri += (i << RQB_L2BPW); 1065 rqh = &rq->rq_queues[pri]; 1066 TAILQ_FOREACH(td, rqh, td_runq) { 1067 if (first && THREAD_CAN_MIGRATE(td) && 1068 THREAD_CAN_SCHED(td, cpu)) 1069 return (td); 1070 first = td; 1071 } 1072 } 1073 if (start != 0) { 1074 start = 0; 1075 goto again; 1076 } 1077 1078 if (first && THREAD_CAN_MIGRATE(first) && 1079 THREAD_CAN_SCHED(first, cpu)) 1080 return (first); 1081 return (NULL); 1082 } 1083 1084 /* 1085 * Steals load from a standard linear queue. 1086 */ 1087 static struct thread * 1088 runq_steal(struct runq *rq, int cpu) 1089 { 1090 struct rqhead *rqh; 1091 struct rqbits *rqb; 1092 struct thread *td; 1093 int word; 1094 int bit; 1095 1096 rqb = &rq->rq_status; 1097 for (word = 0; word < RQB_LEN; word++) { 1098 if (rqb->rqb_bits[word] == 0) 1099 continue; 1100 for (bit = 0; bit < RQB_BPW; bit++) { 1101 if ((rqb->rqb_bits[word] & (1ul << bit)) == 0) 1102 continue; 1103 rqh = &rq->rq_queues[bit + (word << RQB_L2BPW)]; 1104 TAILQ_FOREACH(td, rqh, td_runq) 1105 if (THREAD_CAN_MIGRATE(td) && 1106 THREAD_CAN_SCHED(td, cpu)) 1107 return (td); 1108 } 1109 } 1110 return (NULL); 1111 } 1112 1113 /* 1114 * Attempt to steal a thread in priority order from a thread queue. 1115 */ 1116 static struct thread * 1117 tdq_steal(struct tdq *tdq, int cpu) 1118 { 1119 struct thread *td; 1120 1121 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1122 if ((td = runq_steal(&tdq->tdq_realtime, cpu)) != NULL) 1123 return (td); 1124 if ((td = runq_steal_from(&tdq->tdq_timeshare, 1125 cpu, tdq->tdq_ridx)) != NULL) 1126 return (td); 1127 return (runq_steal(&tdq->tdq_idle, cpu)); 1128 } 1129 1130 /* 1131 * Sets the thread lock and ts_cpu to match the requested cpu. Unlocks the 1132 * current lock and returns with the assigned queue locked. 1133 */ 1134 static inline struct tdq * 1135 sched_setcpu(struct thread *td, int cpu, int flags) 1136 { 1137 1138 struct tdq *tdq; 1139 1140 THREAD_LOCK_ASSERT(td, MA_OWNED); 1141 tdq = TDQ_CPU(cpu); 1142 td->td_sched->ts_cpu = cpu; 1143 /* 1144 * If the lock matches just return the queue. 1145 */ 1146 if (td->td_lock == TDQ_LOCKPTR(tdq)) 1147 return (tdq); 1148 #ifdef notyet 1149 /* 1150 * If the thread isn't running its lockptr is a 1151 * turnstile or a sleepqueue. We can just lock_set without 1152 * blocking. 1153 */ 1154 if (TD_CAN_RUN(td)) { 1155 TDQ_LOCK(tdq); 1156 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 1157 return (tdq); 1158 } 1159 #endif 1160 /* 1161 * The hard case, migration, we need to block the thread first to 1162 * prevent order reversals with other cpus locks. 1163 */ 1164 spinlock_enter(); 1165 thread_lock_block(td); 1166 TDQ_LOCK(tdq); 1167 thread_lock_unblock(td, TDQ_LOCKPTR(tdq)); 1168 spinlock_exit(); 1169 return (tdq); 1170 } 1171 1172 SCHED_STAT_DEFINE(pickcpu_intrbind, "Soft interrupt binding"); 1173 SCHED_STAT_DEFINE(pickcpu_idle_affinity, "Picked idle cpu based on affinity"); 1174 SCHED_STAT_DEFINE(pickcpu_affinity, "Picked cpu based on affinity"); 1175 SCHED_STAT_DEFINE(pickcpu_lowest, "Selected lowest load"); 1176 SCHED_STAT_DEFINE(pickcpu_local, "Migrated to current cpu"); 1177 SCHED_STAT_DEFINE(pickcpu_migration, "Selection may have caused migration"); 1178 1179 static int 1180 sched_pickcpu(struct thread *td, int flags) 1181 { 1182 struct cpu_group *cg, *ccg; 1183 struct td_sched *ts; 1184 struct tdq *tdq; 1185 cpuset_t mask; 1186 int cpu, pri, self; 1187 1188 self = PCPU_GET(cpuid); 1189 ts = td->td_sched; 1190 if (smp_started == 0) 1191 return (self); 1192 /* 1193 * Don't migrate a running thread from sched_switch(). 1194 */ 1195 if ((flags & SRQ_OURSELF) || !THREAD_CAN_MIGRATE(td)) 1196 return (ts->ts_cpu); 1197 /* 1198 * Prefer to run interrupt threads on the processors that generate 1199 * the interrupt. 1200 */ 1201 pri = td->td_priority; 1202 if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_SCHED(td, self) && 1203 curthread->td_intr_nesting_level && ts->ts_cpu != self) { 1204 SCHED_STAT_INC(pickcpu_intrbind); 1205 ts->ts_cpu = self; 1206 if (TDQ_CPU(self)->tdq_lowpri > pri) { 1207 SCHED_STAT_INC(pickcpu_affinity); 1208 return (ts->ts_cpu); 1209 } 1210 } 1211 /* 1212 * If the thread can run on the last cpu and the affinity has not 1213 * expired or it is idle run it there. 1214 */ 1215 tdq = TDQ_CPU(ts->ts_cpu); 1216 cg = tdq->tdq_cg; 1217 if (THREAD_CAN_SCHED(td, ts->ts_cpu) && 1218 tdq->tdq_lowpri >= PRI_MIN_IDLE && 1219 SCHED_AFFINITY(ts, CG_SHARE_L2)) { 1220 if (cg->cg_flags & CG_FLAG_THREAD) { 1221 CPUSET_FOREACH(cpu, cg->cg_mask) { 1222 if (TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE) 1223 break; 1224 } 1225 } else 1226 cpu = INT_MAX; 1227 if (cpu > mp_maxid) { 1228 SCHED_STAT_INC(pickcpu_idle_affinity); 1229 return (ts->ts_cpu); 1230 } 1231 } 1232 /* 1233 * Search for the last level cache CPU group in the tree. 1234 * Skip caches with expired affinity time and SMT groups. 1235 * Affinity to higher level caches will be handled less aggressively. 1236 */ 1237 for (ccg = NULL; cg != NULL; cg = cg->cg_parent) { 1238 if (cg->cg_flags & CG_FLAG_THREAD) 1239 continue; 1240 if (!SCHED_AFFINITY(ts, cg->cg_level)) 1241 continue; 1242 ccg = cg; 1243 } 1244 if (ccg != NULL) 1245 cg = ccg; 1246 cpu = -1; 1247 /* Search the group for the less loaded idle CPU we can run now. */ 1248 mask = td->td_cpuset->cs_mask; 1249 if (cg != NULL && cg != cpu_top && 1250 CPU_CMP(&cg->cg_mask, &cpu_top->cg_mask) != 0) 1251 cpu = sched_lowest(cg, mask, max(pri, PRI_MAX_TIMESHARE), 1252 INT_MAX, ts->ts_cpu); 1253 /* Search globally for the less loaded CPU we can run now. */ 1254 if (cpu == -1) 1255 cpu = sched_lowest(cpu_top, mask, pri, INT_MAX, ts->ts_cpu); 1256 /* Search globally for the less loaded CPU. */ 1257 if (cpu == -1) 1258 cpu = sched_lowest(cpu_top, mask, -1, INT_MAX, ts->ts_cpu); 1259 KASSERT(cpu != -1, ("sched_pickcpu: Failed to find a cpu.")); 1260 /* 1261 * Compare the lowest loaded cpu to current cpu. 1262 */ 1263 if (THREAD_CAN_SCHED(td, self) && TDQ_CPU(self)->tdq_lowpri > pri && 1264 TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE && 1265 TDQ_CPU(self)->tdq_load <= TDQ_CPU(cpu)->tdq_load + 1) { 1266 SCHED_STAT_INC(pickcpu_local); 1267 cpu = self; 1268 } else 1269 SCHED_STAT_INC(pickcpu_lowest); 1270 if (cpu != ts->ts_cpu) 1271 SCHED_STAT_INC(pickcpu_migration); 1272 return (cpu); 1273 } 1274 #endif 1275 1276 /* 1277 * Pick the highest priority task we have and return it. 1278 */ 1279 static struct thread * 1280 tdq_choose(struct tdq *tdq) 1281 { 1282 struct thread *td; 1283 1284 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1285 td = runq_choose(&tdq->tdq_realtime); 1286 if (td != NULL) 1287 return (td); 1288 td = runq_choose_from(&tdq->tdq_timeshare, tdq->tdq_ridx); 1289 if (td != NULL) { 1290 KASSERT(td->td_priority >= PRI_MIN_BATCH, 1291 ("tdq_choose: Invalid priority on timeshare queue %d", 1292 td->td_priority)); 1293 return (td); 1294 } 1295 td = runq_choose(&tdq->tdq_idle); 1296 if (td != NULL) { 1297 KASSERT(td->td_priority >= PRI_MIN_IDLE, 1298 ("tdq_choose: Invalid priority on idle queue %d", 1299 td->td_priority)); 1300 return (td); 1301 } 1302 1303 return (NULL); 1304 } 1305 1306 /* 1307 * Initialize a thread queue. 1308 */ 1309 static void 1310 tdq_setup(struct tdq *tdq) 1311 { 1312 1313 if (bootverbose) 1314 printf("ULE: setup cpu %d\n", TDQ_ID(tdq)); 1315 runq_init(&tdq->tdq_realtime); 1316 runq_init(&tdq->tdq_timeshare); 1317 runq_init(&tdq->tdq_idle); 1318 snprintf(tdq->tdq_name, sizeof(tdq->tdq_name), 1319 "sched lock %d", (int)TDQ_ID(tdq)); 1320 mtx_init(&tdq->tdq_lock, tdq->tdq_name, "sched lock", 1321 MTX_SPIN | MTX_RECURSE); 1322 #ifdef KTR 1323 snprintf(tdq->tdq_loadname, sizeof(tdq->tdq_loadname), 1324 "CPU %d load", (int)TDQ_ID(tdq)); 1325 #endif 1326 } 1327 1328 #ifdef SMP 1329 static void 1330 sched_setup_smp(void) 1331 { 1332 struct tdq *tdq; 1333 int i; 1334 1335 cpu_top = smp_topo(); 1336 CPU_FOREACH(i) { 1337 tdq = TDQ_CPU(i); 1338 tdq_setup(tdq); 1339 tdq->tdq_cg = smp_topo_find(cpu_top, i); 1340 if (tdq->tdq_cg == NULL) 1341 panic("Can't find cpu group for %d\n", i); 1342 } 1343 balance_tdq = TDQ_SELF(); 1344 sched_balance(); 1345 } 1346 #endif 1347 1348 /* 1349 * Setup the thread queues and initialize the topology based on MD 1350 * information. 1351 */ 1352 static void 1353 sched_setup(void *dummy) 1354 { 1355 struct tdq *tdq; 1356 1357 tdq = TDQ_SELF(); 1358 #ifdef SMP 1359 sched_setup_smp(); 1360 #else 1361 tdq_setup(tdq); 1362 #endif 1363 /* 1364 * To avoid divide-by-zero, we set realstathz a dummy value 1365 * in case which sched_clock() called before sched_initticks(). 1366 */ 1367 realstathz = hz; 1368 sched_slice = (realstathz/10); /* ~100ms */ 1369 tickincr = 1 << SCHED_TICK_SHIFT; 1370 1371 /* Add thread0's load since it's running. */ 1372 TDQ_LOCK(tdq); 1373 thread0.td_lock = TDQ_LOCKPTR(TDQ_SELF()); 1374 tdq_load_add(tdq, &thread0); 1375 tdq->tdq_lowpri = thread0.td_priority; 1376 TDQ_UNLOCK(tdq); 1377 } 1378 1379 /* 1380 * This routine determines the tickincr after stathz and hz are setup. 1381 */ 1382 /* ARGSUSED */ 1383 static void 1384 sched_initticks(void *dummy) 1385 { 1386 int incr; 1387 1388 realstathz = stathz ? stathz : hz; 1389 sched_slice = (realstathz/10); /* ~100ms */ 1390 1391 /* 1392 * tickincr is shifted out by 10 to avoid rounding errors due to 1393 * hz not being evenly divisible by stathz on all platforms. 1394 */ 1395 incr = (hz << SCHED_TICK_SHIFT) / realstathz; 1396 /* 1397 * This does not work for values of stathz that are more than 1398 * 1 << SCHED_TICK_SHIFT * hz. In practice this does not happen. 1399 */ 1400 if (incr == 0) 1401 incr = 1; 1402 tickincr = incr; 1403 #ifdef SMP 1404 /* 1405 * Set the default balance interval now that we know 1406 * what realstathz is. 1407 */ 1408 balance_interval = realstathz; 1409 /* 1410 * Set steal thresh to roughly log2(mp_ncpu) but no greater than 4. 1411 * This prevents excess thrashing on large machines and excess idle 1412 * on smaller machines. 1413 */ 1414 steal_thresh = min(fls(mp_ncpus) - 1, 3); 1415 affinity = SCHED_AFFINITY_DEFAULT; 1416 #endif 1417 if (sched_idlespinthresh < 0) 1418 sched_idlespinthresh = max(16, 2 * hz / realstathz); 1419 } 1420 1421 1422 /* 1423 * This is the core of the interactivity algorithm. Determines a score based 1424 * on past behavior. It is the ratio of sleep time to run time scaled to 1425 * a [0, 100] integer. This is the voluntary sleep time of a process, which 1426 * differs from the cpu usage because it does not account for time spent 1427 * waiting on a run-queue. Would be prettier if we had floating point. 1428 */ 1429 static int 1430 sched_interact_score(struct thread *td) 1431 { 1432 struct td_sched *ts; 1433 int div; 1434 1435 ts = td->td_sched; 1436 /* 1437 * The score is only needed if this is likely to be an interactive 1438 * task. Don't go through the expense of computing it if there's 1439 * no chance. 1440 */ 1441 if (sched_interact <= SCHED_INTERACT_HALF && 1442 ts->ts_runtime >= ts->ts_slptime) 1443 return (SCHED_INTERACT_HALF); 1444 1445 if (ts->ts_runtime > ts->ts_slptime) { 1446 div = max(1, ts->ts_runtime / SCHED_INTERACT_HALF); 1447 return (SCHED_INTERACT_HALF + 1448 (SCHED_INTERACT_HALF - (ts->ts_slptime / div))); 1449 } 1450 if (ts->ts_slptime > ts->ts_runtime) { 1451 div = max(1, ts->ts_slptime / SCHED_INTERACT_HALF); 1452 return (ts->ts_runtime / div); 1453 } 1454 /* runtime == slptime */ 1455 if (ts->ts_runtime) 1456 return (SCHED_INTERACT_HALF); 1457 1458 /* 1459 * This can happen if slptime and runtime are 0. 1460 */ 1461 return (0); 1462 1463 } 1464 1465 /* 1466 * Scale the scheduling priority according to the "interactivity" of this 1467 * process. 1468 */ 1469 static void 1470 sched_priority(struct thread *td) 1471 { 1472 int score; 1473 int pri; 1474 1475 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 1476 return; 1477 /* 1478 * If the score is interactive we place the thread in the realtime 1479 * queue with a priority that is less than kernel and interrupt 1480 * priorities. These threads are not subject to nice restrictions. 1481 * 1482 * Scores greater than this are placed on the normal timeshare queue 1483 * where the priority is partially decided by the most recent cpu 1484 * utilization and the rest is decided by nice value. 1485 * 1486 * The nice value of the process has a linear effect on the calculated 1487 * score. Negative nice values make it easier for a thread to be 1488 * considered interactive. 1489 */ 1490 score = imax(0, sched_interact_score(td) + td->td_proc->p_nice); 1491 if (score < sched_interact) { 1492 pri = PRI_MIN_INTERACT; 1493 pri += ((PRI_MAX_INTERACT - PRI_MIN_INTERACT + 1) / 1494 sched_interact) * score; 1495 KASSERT(pri >= PRI_MIN_INTERACT && pri <= PRI_MAX_INTERACT, 1496 ("sched_priority: invalid interactive priority %d score %d", 1497 pri, score)); 1498 } else { 1499 pri = SCHED_PRI_MIN; 1500 if (td->td_sched->ts_ticks) 1501 pri += min(SCHED_PRI_TICKS(td->td_sched), 1502 SCHED_PRI_RANGE); 1503 pri += SCHED_PRI_NICE(td->td_proc->p_nice); 1504 KASSERT(pri >= PRI_MIN_BATCH && pri <= PRI_MAX_BATCH, 1505 ("sched_priority: invalid priority %d: nice %d, " 1506 "ticks %d ftick %d ltick %d tick pri %d", 1507 pri, td->td_proc->p_nice, td->td_sched->ts_ticks, 1508 td->td_sched->ts_ftick, td->td_sched->ts_ltick, 1509 SCHED_PRI_TICKS(td->td_sched))); 1510 } 1511 sched_user_prio(td, pri); 1512 1513 return; 1514 } 1515 1516 /* 1517 * This routine enforces a maximum limit on the amount of scheduling history 1518 * kept. It is called after either the slptime or runtime is adjusted. This 1519 * function is ugly due to integer math. 1520 */ 1521 static void 1522 sched_interact_update(struct thread *td) 1523 { 1524 struct td_sched *ts; 1525 u_int sum; 1526 1527 ts = td->td_sched; 1528 sum = ts->ts_runtime + ts->ts_slptime; 1529 if (sum < SCHED_SLP_RUN_MAX) 1530 return; 1531 /* 1532 * This only happens from two places: 1533 * 1) We have added an unusual amount of run time from fork_exit. 1534 * 2) We have added an unusual amount of sleep time from sched_sleep(). 1535 */ 1536 if (sum > SCHED_SLP_RUN_MAX * 2) { 1537 if (ts->ts_runtime > ts->ts_slptime) { 1538 ts->ts_runtime = SCHED_SLP_RUN_MAX; 1539 ts->ts_slptime = 1; 1540 } else { 1541 ts->ts_slptime = SCHED_SLP_RUN_MAX; 1542 ts->ts_runtime = 1; 1543 } 1544 return; 1545 } 1546 /* 1547 * If we have exceeded by more than 1/5th then the algorithm below 1548 * will not bring us back into range. Dividing by two here forces 1549 * us into the range of [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX] 1550 */ 1551 if (sum > (SCHED_SLP_RUN_MAX / 5) * 6) { 1552 ts->ts_runtime /= 2; 1553 ts->ts_slptime /= 2; 1554 return; 1555 } 1556 ts->ts_runtime = (ts->ts_runtime / 5) * 4; 1557 ts->ts_slptime = (ts->ts_slptime / 5) * 4; 1558 } 1559 1560 /* 1561 * Scale back the interactivity history when a child thread is created. The 1562 * history is inherited from the parent but the thread may behave totally 1563 * differently. For example, a shell spawning a compiler process. We want 1564 * to learn that the compiler is behaving badly very quickly. 1565 */ 1566 static void 1567 sched_interact_fork(struct thread *td) 1568 { 1569 int ratio; 1570 int sum; 1571 1572 sum = td->td_sched->ts_runtime + td->td_sched->ts_slptime; 1573 if (sum > SCHED_SLP_RUN_FORK) { 1574 ratio = sum / SCHED_SLP_RUN_FORK; 1575 td->td_sched->ts_runtime /= ratio; 1576 td->td_sched->ts_slptime /= ratio; 1577 } 1578 } 1579 1580 /* 1581 * Called from proc0_init() to setup the scheduler fields. 1582 */ 1583 void 1584 schedinit(void) 1585 { 1586 1587 /* 1588 * Set up the scheduler specific parts of proc0. 1589 */ 1590 proc0.p_sched = NULL; /* XXX */ 1591 thread0.td_sched = &td_sched0; 1592 td_sched0.ts_ltick = ticks; 1593 td_sched0.ts_ftick = ticks; 1594 td_sched0.ts_slice = sched_slice; 1595 } 1596 1597 /* 1598 * This is only somewhat accurate since given many processes of the same 1599 * priority they will switch when their slices run out, which will be 1600 * at most sched_slice stathz ticks. 1601 */ 1602 int 1603 sched_rr_interval(void) 1604 { 1605 1606 /* Convert sched_slice to hz */ 1607 return (hz/(realstathz/sched_slice)); 1608 } 1609 1610 /* 1611 * Update the percent cpu tracking information when it is requested or 1612 * the total history exceeds the maximum. We keep a sliding history of 1613 * tick counts that slowly decays. This is less precise than the 4BSD 1614 * mechanism since it happens with less regular and frequent events. 1615 */ 1616 static void 1617 sched_pctcpu_update(struct td_sched *ts, int run) 1618 { 1619 int t = ticks; 1620 1621 if (t - ts->ts_ltick >= SCHED_TICK_TARG) { 1622 ts->ts_ticks = 0; 1623 ts->ts_ftick = t - SCHED_TICK_TARG; 1624 } else if (t - ts->ts_ftick >= SCHED_TICK_MAX) { 1625 ts->ts_ticks = (ts->ts_ticks / (ts->ts_ltick - ts->ts_ftick)) * 1626 (ts->ts_ltick - (t - SCHED_TICK_TARG)); 1627 ts->ts_ftick = t - SCHED_TICK_TARG; 1628 } 1629 if (run) 1630 ts->ts_ticks += (t - ts->ts_ltick) << SCHED_TICK_SHIFT; 1631 ts->ts_ltick = t; 1632 } 1633 1634 /* 1635 * Adjust the priority of a thread. Move it to the appropriate run-queue 1636 * if necessary. This is the back-end for several priority related 1637 * functions. 1638 */ 1639 static void 1640 sched_thread_priority(struct thread *td, u_char prio) 1641 { 1642 struct td_sched *ts; 1643 struct tdq *tdq; 1644 int oldpri; 1645 1646 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "prio", 1647 "prio:%d", td->td_priority, "new prio:%d", prio, 1648 KTR_ATTR_LINKED, sched_tdname(curthread)); 1649 SDT_PROBE3(sched, , , change_pri, td, td->td_proc, prio); 1650 if (td != curthread && prio > td->td_priority) { 1651 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread), 1652 "lend prio", "prio:%d", td->td_priority, "new prio:%d", 1653 prio, KTR_ATTR_LINKED, sched_tdname(td)); 1654 SDT_PROBE4(sched, , , lend_pri, td, td->td_proc, prio, 1655 curthread); 1656 } 1657 ts = td->td_sched; 1658 THREAD_LOCK_ASSERT(td, MA_OWNED); 1659 if (td->td_priority == prio) 1660 return; 1661 /* 1662 * If the priority has been elevated due to priority 1663 * propagation, we may have to move ourselves to a new 1664 * queue. This could be optimized to not re-add in some 1665 * cases. 1666 */ 1667 if (TD_ON_RUNQ(td) && prio < td->td_priority) { 1668 sched_rem(td); 1669 td->td_priority = prio; 1670 sched_add(td, SRQ_BORROWING); 1671 return; 1672 } 1673 /* 1674 * If the thread is currently running we may have to adjust the lowpri 1675 * information so other cpus are aware of our current priority. 1676 */ 1677 if (TD_IS_RUNNING(td)) { 1678 tdq = TDQ_CPU(ts->ts_cpu); 1679 oldpri = td->td_priority; 1680 td->td_priority = prio; 1681 if (prio < tdq->tdq_lowpri) 1682 tdq->tdq_lowpri = prio; 1683 else if (tdq->tdq_lowpri == oldpri) 1684 tdq_setlowpri(tdq, td); 1685 return; 1686 } 1687 td->td_priority = prio; 1688 } 1689 1690 /* 1691 * Update a thread's priority when it is lent another thread's 1692 * priority. 1693 */ 1694 void 1695 sched_lend_prio(struct thread *td, u_char prio) 1696 { 1697 1698 td->td_flags |= TDF_BORROWING; 1699 sched_thread_priority(td, prio); 1700 } 1701 1702 /* 1703 * Restore a thread's priority when priority propagation is 1704 * over. The prio argument is the minimum priority the thread 1705 * needs to have to satisfy other possible priority lending 1706 * requests. If the thread's regular priority is less 1707 * important than prio, the thread will keep a priority boost 1708 * of prio. 1709 */ 1710 void 1711 sched_unlend_prio(struct thread *td, u_char prio) 1712 { 1713 u_char base_pri; 1714 1715 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 1716 td->td_base_pri <= PRI_MAX_TIMESHARE) 1717 base_pri = td->td_user_pri; 1718 else 1719 base_pri = td->td_base_pri; 1720 if (prio >= base_pri) { 1721 td->td_flags &= ~TDF_BORROWING; 1722 sched_thread_priority(td, base_pri); 1723 } else 1724 sched_lend_prio(td, prio); 1725 } 1726 1727 /* 1728 * Standard entry for setting the priority to an absolute value. 1729 */ 1730 void 1731 sched_prio(struct thread *td, u_char prio) 1732 { 1733 u_char oldprio; 1734 1735 /* First, update the base priority. */ 1736 td->td_base_pri = prio; 1737 1738 /* 1739 * If the thread is borrowing another thread's priority, don't 1740 * ever lower the priority. 1741 */ 1742 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 1743 return; 1744 1745 /* Change the real priority. */ 1746 oldprio = td->td_priority; 1747 sched_thread_priority(td, prio); 1748 1749 /* 1750 * If the thread is on a turnstile, then let the turnstile update 1751 * its state. 1752 */ 1753 if (TD_ON_LOCK(td) && oldprio != prio) 1754 turnstile_adjust(td, oldprio); 1755 } 1756 1757 /* 1758 * Set the base user priority, does not effect current running priority. 1759 */ 1760 void 1761 sched_user_prio(struct thread *td, u_char prio) 1762 { 1763 1764 td->td_base_user_pri = prio; 1765 if (td->td_lend_user_pri <= prio) 1766 return; 1767 td->td_user_pri = prio; 1768 } 1769 1770 void 1771 sched_lend_user_prio(struct thread *td, u_char prio) 1772 { 1773 1774 THREAD_LOCK_ASSERT(td, MA_OWNED); 1775 td->td_lend_user_pri = prio; 1776 td->td_user_pri = min(prio, td->td_base_user_pri); 1777 if (td->td_priority > td->td_user_pri) 1778 sched_prio(td, td->td_user_pri); 1779 else if (td->td_priority != td->td_user_pri) 1780 td->td_flags |= TDF_NEEDRESCHED; 1781 } 1782 1783 /* 1784 * Handle migration from sched_switch(). This happens only for 1785 * cpu binding. 1786 */ 1787 static struct mtx * 1788 sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags) 1789 { 1790 struct tdq *tdn; 1791 1792 tdn = TDQ_CPU(td->td_sched->ts_cpu); 1793 #ifdef SMP 1794 tdq_load_rem(tdq, td); 1795 /* 1796 * Do the lock dance required to avoid LOR. We grab an extra 1797 * spinlock nesting to prevent preemption while we're 1798 * not holding either run-queue lock. 1799 */ 1800 spinlock_enter(); 1801 thread_lock_block(td); /* This releases the lock on tdq. */ 1802 1803 /* 1804 * Acquire both run-queue locks before placing the thread on the new 1805 * run-queue to avoid deadlocks created by placing a thread with a 1806 * blocked lock on the run-queue of a remote processor. The deadlock 1807 * occurs when a third processor attempts to lock the two queues in 1808 * question while the target processor is spinning with its own 1809 * run-queue lock held while waiting for the blocked lock to clear. 1810 */ 1811 tdq_lock_pair(tdn, tdq); 1812 tdq_add(tdn, td, flags); 1813 tdq_notify(tdn, td); 1814 TDQ_UNLOCK(tdn); 1815 spinlock_exit(); 1816 #endif 1817 return (TDQ_LOCKPTR(tdn)); 1818 } 1819 1820 /* 1821 * Variadic version of thread_lock_unblock() that does not assume td_lock 1822 * is blocked. 1823 */ 1824 static inline void 1825 thread_unblock_switch(struct thread *td, struct mtx *mtx) 1826 { 1827 atomic_store_rel_ptr((volatile uintptr_t *)&td->td_lock, 1828 (uintptr_t)mtx); 1829 } 1830 1831 /* 1832 * Switch threads. This function has to handle threads coming in while 1833 * blocked for some reason, running, or idle. It also must deal with 1834 * migrating a thread from one queue to another as running threads may 1835 * be assigned elsewhere via binding. 1836 */ 1837 void 1838 sched_switch(struct thread *td, struct thread *newtd, int flags) 1839 { 1840 struct tdq *tdq; 1841 struct td_sched *ts; 1842 struct mtx *mtx; 1843 int srqflag; 1844 int cpuid; 1845 1846 THREAD_LOCK_ASSERT(td, MA_OWNED); 1847 KASSERT(newtd == NULL, ("sched_switch: Unsupported newtd argument")); 1848 1849 cpuid = PCPU_GET(cpuid); 1850 tdq = TDQ_CPU(cpuid); 1851 ts = td->td_sched; 1852 mtx = td->td_lock; 1853 sched_pctcpu_update(ts, 1); 1854 ts->ts_rltick = ticks; 1855 td->td_lastcpu = td->td_oncpu; 1856 td->td_oncpu = NOCPU; 1857 if (!(flags & SW_PREEMPT)) 1858 td->td_flags &= ~TDF_NEEDRESCHED; 1859 td->td_owepreempt = 0; 1860 tdq->tdq_switchcnt++; 1861 /* 1862 * The lock pointer in an idle thread should never change. Reset it 1863 * to CAN_RUN as well. 1864 */ 1865 if (TD_IS_IDLETHREAD(td)) { 1866 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1867 TD_SET_CAN_RUN(td); 1868 } else if (TD_IS_RUNNING(td)) { 1869 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1870 srqflag = (flags & SW_PREEMPT) ? 1871 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 1872 SRQ_OURSELF|SRQ_YIELDING; 1873 #ifdef SMP 1874 if (THREAD_CAN_MIGRATE(td) && !THREAD_CAN_SCHED(td, ts->ts_cpu)) 1875 ts->ts_cpu = sched_pickcpu(td, 0); 1876 #endif 1877 if (ts->ts_cpu == cpuid) 1878 tdq_runq_add(tdq, td, srqflag); 1879 else { 1880 KASSERT(THREAD_CAN_MIGRATE(td) || 1881 (ts->ts_flags & TSF_BOUND) != 0, 1882 ("Thread %p shouldn't migrate", td)); 1883 mtx = sched_switch_migrate(tdq, td, srqflag); 1884 } 1885 } else { 1886 /* This thread must be going to sleep. */ 1887 TDQ_LOCK(tdq); 1888 mtx = thread_lock_block(td); 1889 tdq_load_rem(tdq, td); 1890 } 1891 /* 1892 * We enter here with the thread blocked and assigned to the 1893 * appropriate cpu run-queue or sleep-queue and with the current 1894 * thread-queue locked. 1895 */ 1896 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 1897 newtd = choosethread(); 1898 /* 1899 * Call the MD code to switch contexts if necessary. 1900 */ 1901 if (td != newtd) { 1902 #ifdef HWPMC_HOOKS 1903 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1904 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 1905 #endif 1906 SDT_PROBE2(sched, , , off_cpu, td, td->td_proc); 1907 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 1908 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 1909 sched_pctcpu_update(newtd->td_sched, 0); 1910 1911 #ifdef KDTRACE_HOOKS 1912 /* 1913 * If DTrace has set the active vtime enum to anything 1914 * other than INACTIVE (0), then it should have set the 1915 * function to call. 1916 */ 1917 if (dtrace_vtime_active) 1918 (*dtrace_vtime_switch_func)(newtd); 1919 #endif 1920 1921 cpu_switch(td, newtd, mtx); 1922 /* 1923 * We may return from cpu_switch on a different cpu. However, 1924 * we always return with td_lock pointing to the current cpu's 1925 * run queue lock. 1926 */ 1927 cpuid = PCPU_GET(cpuid); 1928 tdq = TDQ_CPU(cpuid); 1929 lock_profile_obtain_lock_success( 1930 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 1931 1932 SDT_PROBE0(sched, , , on_cpu); 1933 #ifdef HWPMC_HOOKS 1934 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1935 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 1936 #endif 1937 } else { 1938 thread_unblock_switch(td, mtx); 1939 SDT_PROBE0(sched, , , remain_cpu); 1940 } 1941 /* 1942 * Assert that all went well and return. 1943 */ 1944 TDQ_LOCK_ASSERT(tdq, MA_OWNED|MA_NOTRECURSED); 1945 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1946 td->td_oncpu = cpuid; 1947 } 1948 1949 /* 1950 * Adjust thread priorities as a result of a nice request. 1951 */ 1952 void 1953 sched_nice(struct proc *p, int nice) 1954 { 1955 struct thread *td; 1956 1957 PROC_LOCK_ASSERT(p, MA_OWNED); 1958 1959 p->p_nice = nice; 1960 FOREACH_THREAD_IN_PROC(p, td) { 1961 thread_lock(td); 1962 sched_priority(td); 1963 sched_prio(td, td->td_base_user_pri); 1964 thread_unlock(td); 1965 } 1966 } 1967 1968 /* 1969 * Record the sleep time for the interactivity scorer. 1970 */ 1971 void 1972 sched_sleep(struct thread *td, int prio) 1973 { 1974 1975 THREAD_LOCK_ASSERT(td, MA_OWNED); 1976 1977 td->td_slptick = ticks; 1978 if (TD_IS_SUSPENDED(td) || prio >= PSOCK) 1979 td->td_flags |= TDF_CANSWAP; 1980 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 1981 return; 1982 if (static_boost == 1 && prio) 1983 sched_prio(td, prio); 1984 else if (static_boost && td->td_priority > static_boost) 1985 sched_prio(td, static_boost); 1986 } 1987 1988 /* 1989 * Schedule a thread to resume execution and record how long it voluntarily 1990 * slept. We also update the pctcpu, interactivity, and priority. 1991 */ 1992 void 1993 sched_wakeup(struct thread *td) 1994 { 1995 struct td_sched *ts; 1996 int slptick; 1997 1998 THREAD_LOCK_ASSERT(td, MA_OWNED); 1999 ts = td->td_sched; 2000 td->td_flags &= ~TDF_CANSWAP; 2001 /* 2002 * If we slept for more than a tick update our interactivity and 2003 * priority. 2004 */ 2005 slptick = td->td_slptick; 2006 td->td_slptick = 0; 2007 if (slptick && slptick != ticks) { 2008 ts->ts_slptime += (ticks - slptick) << SCHED_TICK_SHIFT; 2009 sched_interact_update(td); 2010 sched_pctcpu_update(ts, 0); 2011 } 2012 /* Reset the slice value after we sleep. */ 2013 ts->ts_slice = sched_slice; 2014 sched_add(td, SRQ_BORING); 2015 } 2016 2017 /* 2018 * Penalize the parent for creating a new child and initialize the child's 2019 * priority. 2020 */ 2021 void 2022 sched_fork(struct thread *td, struct thread *child) 2023 { 2024 THREAD_LOCK_ASSERT(td, MA_OWNED); 2025 sched_pctcpu_update(td->td_sched, 1); 2026 sched_fork_thread(td, child); 2027 /* 2028 * Penalize the parent and child for forking. 2029 */ 2030 sched_interact_fork(child); 2031 sched_priority(child); 2032 td->td_sched->ts_runtime += tickincr; 2033 sched_interact_update(td); 2034 sched_priority(td); 2035 } 2036 2037 /* 2038 * Fork a new thread, may be within the same process. 2039 */ 2040 void 2041 sched_fork_thread(struct thread *td, struct thread *child) 2042 { 2043 struct td_sched *ts; 2044 struct td_sched *ts2; 2045 2046 THREAD_LOCK_ASSERT(td, MA_OWNED); 2047 /* 2048 * Initialize child. 2049 */ 2050 ts = td->td_sched; 2051 ts2 = child->td_sched; 2052 child->td_lock = TDQ_LOCKPTR(TDQ_SELF()); 2053 child->td_cpuset = cpuset_ref(td->td_cpuset); 2054 ts2->ts_cpu = ts->ts_cpu; 2055 ts2->ts_flags = 0; 2056 /* 2057 * Grab our parents cpu estimation information. 2058 */ 2059 ts2->ts_ticks = ts->ts_ticks; 2060 ts2->ts_ltick = ts->ts_ltick; 2061 ts2->ts_ftick = ts->ts_ftick; 2062 /* 2063 * Do not inherit any borrowed priority from the parent. 2064 */ 2065 child->td_priority = child->td_base_pri; 2066 /* 2067 * And update interactivity score. 2068 */ 2069 ts2->ts_slptime = ts->ts_slptime; 2070 ts2->ts_runtime = ts->ts_runtime; 2071 ts2->ts_slice = 1; /* Attempt to quickly learn interactivity. */ 2072 #ifdef KTR 2073 bzero(ts2->ts_name, sizeof(ts2->ts_name)); 2074 #endif 2075 } 2076 2077 /* 2078 * Adjust the priority class of a thread. 2079 */ 2080 void 2081 sched_class(struct thread *td, int class) 2082 { 2083 2084 THREAD_LOCK_ASSERT(td, MA_OWNED); 2085 if (td->td_pri_class == class) 2086 return; 2087 td->td_pri_class = class; 2088 } 2089 2090 /* 2091 * Return some of the child's priority and interactivity to the parent. 2092 */ 2093 void 2094 sched_exit(struct proc *p, struct thread *child) 2095 { 2096 struct thread *td; 2097 2098 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "proc exit", 2099 "prio:%d", child->td_priority); 2100 PROC_LOCK_ASSERT(p, MA_OWNED); 2101 td = FIRST_THREAD_IN_PROC(p); 2102 sched_exit_thread(td, child); 2103 } 2104 2105 /* 2106 * Penalize another thread for the time spent on this one. This helps to 2107 * worsen the priority and interactivity of processes which schedule batch 2108 * jobs such as make. This has little effect on the make process itself but 2109 * causes new processes spawned by it to receive worse scores immediately. 2110 */ 2111 void 2112 sched_exit_thread(struct thread *td, struct thread *child) 2113 { 2114 2115 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "thread exit", 2116 "prio:%d", child->td_priority); 2117 /* 2118 * Give the child's runtime to the parent without returning the 2119 * sleep time as a penalty to the parent. This causes shells that 2120 * launch expensive things to mark their children as expensive. 2121 */ 2122 thread_lock(td); 2123 td->td_sched->ts_runtime += child->td_sched->ts_runtime; 2124 sched_interact_update(td); 2125 sched_priority(td); 2126 thread_unlock(td); 2127 } 2128 2129 void 2130 sched_preempt(struct thread *td) 2131 { 2132 struct tdq *tdq; 2133 2134 SDT_PROBE2(sched, , , surrender, td, td->td_proc); 2135 2136 thread_lock(td); 2137 tdq = TDQ_SELF(); 2138 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2139 tdq->tdq_ipipending = 0; 2140 if (td->td_priority > tdq->tdq_lowpri) { 2141 int flags; 2142 2143 flags = SW_INVOL | SW_PREEMPT; 2144 if (td->td_critnest > 1) 2145 td->td_owepreempt = 1; 2146 else if (TD_IS_IDLETHREAD(td)) 2147 mi_switch(flags | SWT_REMOTEWAKEIDLE, NULL); 2148 else 2149 mi_switch(flags | SWT_REMOTEPREEMPT, NULL); 2150 } 2151 thread_unlock(td); 2152 } 2153 2154 /* 2155 * Fix priorities on return to user-space. Priorities may be elevated due 2156 * to static priorities in msleep() or similar. 2157 */ 2158 void 2159 sched_userret(struct thread *td) 2160 { 2161 /* 2162 * XXX we cheat slightly on the locking here to avoid locking in 2163 * the usual case. Setting td_priority here is essentially an 2164 * incomplete workaround for not setting it properly elsewhere. 2165 * Now that some interrupt handlers are threads, not setting it 2166 * properly elsewhere can clobber it in the window between setting 2167 * it here and returning to user mode, so don't waste time setting 2168 * it perfectly here. 2169 */ 2170 KASSERT((td->td_flags & TDF_BORROWING) == 0, 2171 ("thread with borrowed priority returning to userland")); 2172 if (td->td_priority != td->td_user_pri) { 2173 thread_lock(td); 2174 td->td_priority = td->td_user_pri; 2175 td->td_base_pri = td->td_user_pri; 2176 tdq_setlowpri(TDQ_SELF(), td); 2177 thread_unlock(td); 2178 } 2179 } 2180 2181 /* 2182 * Handle a stathz tick. This is really only relevant for timeshare 2183 * threads. 2184 */ 2185 void 2186 sched_clock(struct thread *td) 2187 { 2188 struct tdq *tdq; 2189 struct td_sched *ts; 2190 2191 THREAD_LOCK_ASSERT(td, MA_OWNED); 2192 tdq = TDQ_SELF(); 2193 #ifdef SMP 2194 /* 2195 * We run the long term load balancer infrequently on the first cpu. 2196 */ 2197 if (balance_tdq == tdq) { 2198 if (balance_ticks && --balance_ticks == 0) 2199 sched_balance(); 2200 } 2201 #endif 2202 /* 2203 * Save the old switch count so we have a record of the last ticks 2204 * activity. Initialize the new switch count based on our load. 2205 * If there is some activity seed it to reflect that. 2206 */ 2207 tdq->tdq_oldswitchcnt = tdq->tdq_switchcnt; 2208 tdq->tdq_switchcnt = tdq->tdq_load; 2209 /* 2210 * Advance the insert index once for each tick to ensure that all 2211 * threads get a chance to run. 2212 */ 2213 if (tdq->tdq_idx == tdq->tdq_ridx) { 2214 tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS; 2215 if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx])) 2216 tdq->tdq_ridx = tdq->tdq_idx; 2217 } 2218 ts = td->td_sched; 2219 sched_pctcpu_update(ts, 1); 2220 if (td->td_pri_class & PRI_FIFO_BIT) 2221 return; 2222 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) { 2223 /* 2224 * We used a tick; charge it to the thread so 2225 * that we can compute our interactivity. 2226 */ 2227 td->td_sched->ts_runtime += tickincr; 2228 sched_interact_update(td); 2229 sched_priority(td); 2230 } 2231 /* 2232 * We used up one time slice. 2233 */ 2234 if (--ts->ts_slice > 0) 2235 return; 2236 /* 2237 * We're out of time, force a requeue at userret(). 2238 */ 2239 ts->ts_slice = sched_slice; 2240 td->td_flags |= TDF_NEEDRESCHED; 2241 } 2242 2243 /* 2244 * Called once per hz tick. 2245 */ 2246 void 2247 sched_tick(int cnt) 2248 { 2249 2250 } 2251 2252 /* 2253 * Return whether the current CPU has runnable tasks. Used for in-kernel 2254 * cooperative idle threads. 2255 */ 2256 int 2257 sched_runnable(void) 2258 { 2259 struct tdq *tdq; 2260 int load; 2261 2262 load = 1; 2263 2264 tdq = TDQ_SELF(); 2265 if ((curthread->td_flags & TDF_IDLETD) != 0) { 2266 if (tdq->tdq_load > 0) 2267 goto out; 2268 } else 2269 if (tdq->tdq_load - 1 > 0) 2270 goto out; 2271 load = 0; 2272 out: 2273 return (load); 2274 } 2275 2276 /* 2277 * Choose the highest priority thread to run. The thread is removed from 2278 * the run-queue while running however the load remains. For SMP we set 2279 * the tdq in the global idle bitmask if it idles here. 2280 */ 2281 struct thread * 2282 sched_choose(void) 2283 { 2284 struct thread *td; 2285 struct tdq *tdq; 2286 2287 tdq = TDQ_SELF(); 2288 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2289 td = tdq_choose(tdq); 2290 if (td) { 2291 tdq_runq_rem(tdq, td); 2292 tdq->tdq_lowpri = td->td_priority; 2293 return (td); 2294 } 2295 tdq->tdq_lowpri = PRI_MAX_IDLE; 2296 return (PCPU_GET(idlethread)); 2297 } 2298 2299 /* 2300 * Set owepreempt if necessary. Preemption never happens directly in ULE, 2301 * we always request it once we exit a critical section. 2302 */ 2303 static inline void 2304 sched_setpreempt(struct thread *td) 2305 { 2306 struct thread *ctd; 2307 int cpri; 2308 int pri; 2309 2310 THREAD_LOCK_ASSERT(curthread, MA_OWNED); 2311 2312 ctd = curthread; 2313 pri = td->td_priority; 2314 cpri = ctd->td_priority; 2315 if (pri < cpri) 2316 ctd->td_flags |= TDF_NEEDRESCHED; 2317 if (panicstr != NULL || pri >= cpri || cold || TD_IS_INHIBITED(ctd)) 2318 return; 2319 if (!sched_shouldpreempt(pri, cpri, 0)) 2320 return; 2321 ctd->td_owepreempt = 1; 2322 } 2323 2324 /* 2325 * Add a thread to a thread queue. Select the appropriate runq and add the 2326 * thread to it. This is the internal function called when the tdq is 2327 * predetermined. 2328 */ 2329 void 2330 tdq_add(struct tdq *tdq, struct thread *td, int flags) 2331 { 2332 2333 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2334 KASSERT((td->td_inhibitors == 0), 2335 ("sched_add: trying to run inhibited thread")); 2336 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 2337 ("sched_add: bad thread state")); 2338 KASSERT(td->td_flags & TDF_INMEM, 2339 ("sched_add: thread swapped out")); 2340 2341 if (td->td_priority < tdq->tdq_lowpri) 2342 tdq->tdq_lowpri = td->td_priority; 2343 tdq_runq_add(tdq, td, flags); 2344 tdq_load_add(tdq, td); 2345 } 2346 2347 /* 2348 * Select the target thread queue and add a thread to it. Request 2349 * preemption or IPI a remote processor if required. 2350 */ 2351 void 2352 sched_add(struct thread *td, int flags) 2353 { 2354 struct tdq *tdq; 2355 #ifdef SMP 2356 int cpu; 2357 #endif 2358 2359 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 2360 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 2361 sched_tdname(curthread)); 2362 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 2363 KTR_ATTR_LINKED, sched_tdname(td)); 2364 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 2365 flags & SRQ_PREEMPTED); 2366 THREAD_LOCK_ASSERT(td, MA_OWNED); 2367 /* 2368 * Recalculate the priority before we select the target cpu or 2369 * run-queue. 2370 */ 2371 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 2372 sched_priority(td); 2373 #ifdef SMP 2374 /* 2375 * Pick the destination cpu and if it isn't ours transfer to the 2376 * target cpu. 2377 */ 2378 cpu = sched_pickcpu(td, flags); 2379 tdq = sched_setcpu(td, cpu, flags); 2380 tdq_add(tdq, td, flags); 2381 if (cpu != PCPU_GET(cpuid)) { 2382 tdq_notify(tdq, td); 2383 return; 2384 } 2385 #else 2386 tdq = TDQ_SELF(); 2387 TDQ_LOCK(tdq); 2388 /* 2389 * Now that the thread is moving to the run-queue, set the lock 2390 * to the scheduler's lock. 2391 */ 2392 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 2393 tdq_add(tdq, td, flags); 2394 #endif 2395 if (!(flags & SRQ_YIELDING)) 2396 sched_setpreempt(td); 2397 } 2398 2399 /* 2400 * Remove a thread from a run-queue without running it. This is used 2401 * when we're stealing a thread from a remote queue. Otherwise all threads 2402 * exit by calling sched_exit_thread() and sched_throw() themselves. 2403 */ 2404 void 2405 sched_rem(struct thread *td) 2406 { 2407 struct tdq *tdq; 2408 2409 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "runq rem", 2410 "prio:%d", td->td_priority); 2411 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL); 2412 tdq = TDQ_CPU(td->td_sched->ts_cpu); 2413 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2414 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2415 KASSERT(TD_ON_RUNQ(td), 2416 ("sched_rem: thread not on run queue")); 2417 tdq_runq_rem(tdq, td); 2418 tdq_load_rem(tdq, td); 2419 TD_SET_CAN_RUN(td); 2420 if (td->td_priority == tdq->tdq_lowpri) 2421 tdq_setlowpri(tdq, NULL); 2422 } 2423 2424 /* 2425 * Fetch cpu utilization information. Updates on demand. 2426 */ 2427 fixpt_t 2428 sched_pctcpu(struct thread *td) 2429 { 2430 fixpt_t pctcpu; 2431 struct td_sched *ts; 2432 2433 pctcpu = 0; 2434 ts = td->td_sched; 2435 if (ts == NULL) 2436 return (0); 2437 2438 THREAD_LOCK_ASSERT(td, MA_OWNED); 2439 sched_pctcpu_update(ts, TD_IS_RUNNING(td)); 2440 if (ts->ts_ticks) { 2441 int rtick; 2442 2443 /* How many rtick per second ? */ 2444 rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz); 2445 pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT; 2446 } 2447 2448 return (pctcpu); 2449 } 2450 2451 /* 2452 * Enforce affinity settings for a thread. Called after adjustments to 2453 * cpumask. 2454 */ 2455 void 2456 sched_affinity(struct thread *td) 2457 { 2458 #ifdef SMP 2459 struct td_sched *ts; 2460 2461 THREAD_LOCK_ASSERT(td, MA_OWNED); 2462 ts = td->td_sched; 2463 if (THREAD_CAN_SCHED(td, ts->ts_cpu)) 2464 return; 2465 if (TD_ON_RUNQ(td)) { 2466 sched_rem(td); 2467 sched_add(td, SRQ_BORING); 2468 return; 2469 } 2470 if (!TD_IS_RUNNING(td)) 2471 return; 2472 /* 2473 * Force a switch before returning to userspace. If the 2474 * target thread is not running locally send an ipi to force 2475 * the issue. 2476 */ 2477 td->td_flags |= TDF_NEEDRESCHED; 2478 if (td != curthread) 2479 ipi_cpu(ts->ts_cpu, IPI_PREEMPT); 2480 #endif 2481 } 2482 2483 /* 2484 * Bind a thread to a target cpu. 2485 */ 2486 void 2487 sched_bind(struct thread *td, int cpu) 2488 { 2489 struct td_sched *ts; 2490 2491 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 2492 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 2493 ts = td->td_sched; 2494 if (ts->ts_flags & TSF_BOUND) 2495 sched_unbind(td); 2496 KASSERT(THREAD_CAN_MIGRATE(td), ("%p must be migratable", td)); 2497 ts->ts_flags |= TSF_BOUND; 2498 sched_pin(); 2499 if (PCPU_GET(cpuid) == cpu) 2500 return; 2501 ts->ts_cpu = cpu; 2502 /* When we return from mi_switch we'll be on the correct cpu. */ 2503 mi_switch(SW_VOL, NULL); 2504 } 2505 2506 /* 2507 * Release a bound thread. 2508 */ 2509 void 2510 sched_unbind(struct thread *td) 2511 { 2512 struct td_sched *ts; 2513 2514 THREAD_LOCK_ASSERT(td, MA_OWNED); 2515 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 2516 ts = td->td_sched; 2517 if ((ts->ts_flags & TSF_BOUND) == 0) 2518 return; 2519 ts->ts_flags &= ~TSF_BOUND; 2520 sched_unpin(); 2521 } 2522 2523 int 2524 sched_is_bound(struct thread *td) 2525 { 2526 THREAD_LOCK_ASSERT(td, MA_OWNED); 2527 return (td->td_sched->ts_flags & TSF_BOUND); 2528 } 2529 2530 /* 2531 * Basic yield call. 2532 */ 2533 void 2534 sched_relinquish(struct thread *td) 2535 { 2536 thread_lock(td); 2537 mi_switch(SW_VOL | SWT_RELINQUISH, NULL); 2538 thread_unlock(td); 2539 } 2540 2541 /* 2542 * Return the total system load. 2543 */ 2544 int 2545 sched_load(void) 2546 { 2547 #ifdef SMP 2548 int total; 2549 int i; 2550 2551 total = 0; 2552 CPU_FOREACH(i) 2553 total += TDQ_CPU(i)->tdq_sysload; 2554 return (total); 2555 #else 2556 return (TDQ_SELF()->tdq_sysload); 2557 #endif 2558 } 2559 2560 int 2561 sched_sizeof_proc(void) 2562 { 2563 return (sizeof(struct proc)); 2564 } 2565 2566 int 2567 sched_sizeof_thread(void) 2568 { 2569 return (sizeof(struct thread) + sizeof(struct td_sched)); 2570 } 2571 2572 #ifdef SMP 2573 #define TDQ_IDLESPIN(tdq) \ 2574 ((tdq)->tdq_cg != NULL && ((tdq)->tdq_cg->cg_flags & CG_FLAG_THREAD) == 0) 2575 #else 2576 #define TDQ_IDLESPIN(tdq) 1 2577 #endif 2578 2579 /* 2580 * The actual idle process. 2581 */ 2582 void 2583 sched_idletd(void *dummy) 2584 { 2585 struct thread *td; 2586 struct tdq *tdq; 2587 int switchcnt; 2588 int i; 2589 2590 mtx_assert(&Giant, MA_NOTOWNED); 2591 td = curthread; 2592 tdq = TDQ_SELF(); 2593 for (;;) { 2594 #ifdef SMP 2595 if (tdq_idled(tdq) == 0) 2596 continue; 2597 #endif 2598 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2599 /* 2600 * If we're switching very frequently, spin while checking 2601 * for load rather than entering a low power state that 2602 * may require an IPI. However, don't do any busy 2603 * loops while on SMT machines as this simply steals 2604 * cycles from cores doing useful work. 2605 */ 2606 if (TDQ_IDLESPIN(tdq) && switchcnt > sched_idlespinthresh) { 2607 for (i = 0; i < sched_idlespins; i++) { 2608 if (tdq->tdq_load) 2609 break; 2610 cpu_spinwait(); 2611 } 2612 } 2613 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2614 if (tdq->tdq_load == 0) { 2615 tdq->tdq_cpu_idle = 1; 2616 if (tdq->tdq_load == 0) { 2617 cpu_idle(switchcnt > sched_idlespinthresh * 4); 2618 tdq->tdq_switchcnt++; 2619 } 2620 tdq->tdq_cpu_idle = 0; 2621 } 2622 if (tdq->tdq_load) { 2623 thread_lock(td); 2624 mi_switch(SW_VOL | SWT_IDLE, NULL); 2625 thread_unlock(td); 2626 } 2627 } 2628 } 2629 2630 /* 2631 * A CPU is entering for the first time or a thread is exiting. 2632 */ 2633 void 2634 sched_throw(struct thread *td) 2635 { 2636 struct thread *newtd; 2637 struct tdq *tdq; 2638 2639 tdq = TDQ_SELF(); 2640 if (td == NULL) { 2641 /* Correct spinlock nesting and acquire the correct lock. */ 2642 TDQ_LOCK(tdq); 2643 spinlock_exit(); 2644 PCPU_SET(switchtime, cpu_ticks()); 2645 PCPU_SET(switchticks, ticks); 2646 } else { 2647 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2648 tdq_load_rem(tdq, td); 2649 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 2650 } 2651 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 2652 newtd = choosethread(); 2653 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 2654 cpu_throw(td, newtd); /* doesn't return */ 2655 } 2656 2657 /* 2658 * This is called from fork_exit(). Just acquire the correct locks and 2659 * let fork do the rest of the work. 2660 */ 2661 void 2662 sched_fork_exit(struct thread *td) 2663 { 2664 struct td_sched *ts; 2665 struct tdq *tdq; 2666 int cpuid; 2667 2668 /* 2669 * Finish setting up thread glue so that it begins execution in a 2670 * non-nested critical section with the scheduler lock held. 2671 */ 2672 cpuid = PCPU_GET(cpuid); 2673 tdq = TDQ_CPU(cpuid); 2674 ts = td->td_sched; 2675 if (TD_IS_IDLETHREAD(td)) 2676 td->td_lock = TDQ_LOCKPTR(tdq); 2677 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2678 td->td_oncpu = cpuid; 2679 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 2680 lock_profile_obtain_lock_success( 2681 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 2682 } 2683 2684 /* 2685 * Create on first use to catch odd startup conditons. 2686 */ 2687 char * 2688 sched_tdname(struct thread *td) 2689 { 2690 #ifdef KTR 2691 struct td_sched *ts; 2692 2693 ts = td->td_sched; 2694 if (ts->ts_name[0] == '\0') 2695 snprintf(ts->ts_name, sizeof(ts->ts_name), 2696 "%s tid %d", td->td_name, td->td_tid); 2697 return (ts->ts_name); 2698 #else 2699 return (td->td_name); 2700 #endif 2701 } 2702 2703 #ifdef KTR 2704 void 2705 sched_clear_tdname(struct thread *td) 2706 { 2707 struct td_sched *ts; 2708 2709 ts = td->td_sched; 2710 ts->ts_name[0] = '\0'; 2711 } 2712 #endif 2713 2714 #ifdef SMP 2715 2716 /* 2717 * Build the CPU topology dump string. Is recursively called to collect 2718 * the topology tree. 2719 */ 2720 static int 2721 sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, struct cpu_group *cg, 2722 int indent) 2723 { 2724 char cpusetbuf[CPUSETBUFSIZ]; 2725 int i, first; 2726 2727 sbuf_printf(sb, "%*s<group level=\"%d\" cache-level=\"%d\">\n", indent, 2728 "", 1 + indent / 2, cg->cg_level); 2729 sbuf_printf(sb, "%*s <cpu count=\"%d\" mask=\"%s\">", indent, "", 2730 cg->cg_count, cpusetobj_strprint(cpusetbuf, &cg->cg_mask)); 2731 first = TRUE; 2732 for (i = 0; i < MAXCPU; i++) { 2733 if (CPU_ISSET(i, &cg->cg_mask)) { 2734 if (!first) 2735 sbuf_printf(sb, ", "); 2736 else 2737 first = FALSE; 2738 sbuf_printf(sb, "%d", i); 2739 } 2740 } 2741 sbuf_printf(sb, "</cpu>\n"); 2742 2743 if (cg->cg_flags != 0) { 2744 sbuf_printf(sb, "%*s <flags>", indent, ""); 2745 if ((cg->cg_flags & CG_FLAG_HTT) != 0) 2746 sbuf_printf(sb, "<flag name=\"HTT\">HTT group</flag>"); 2747 if ((cg->cg_flags & CG_FLAG_THREAD) != 0) 2748 sbuf_printf(sb, "<flag name=\"THREAD\">THREAD group</flag>"); 2749 if ((cg->cg_flags & CG_FLAG_SMT) != 0) 2750 sbuf_printf(sb, "<flag name=\"SMT\">SMT group</flag>"); 2751 sbuf_printf(sb, "</flags>\n"); 2752 } 2753 2754 if (cg->cg_children > 0) { 2755 sbuf_printf(sb, "%*s <children>\n", indent, ""); 2756 for (i = 0; i < cg->cg_children; i++) 2757 sysctl_kern_sched_topology_spec_internal(sb, 2758 &cg->cg_child[i], indent+2); 2759 sbuf_printf(sb, "%*s </children>\n", indent, ""); 2760 } 2761 sbuf_printf(sb, "%*s</group>\n", indent, ""); 2762 return (0); 2763 } 2764 2765 /* 2766 * Sysctl handler for retrieving topology dump. It's a wrapper for 2767 * the recursive sysctl_kern_smp_topology_spec_internal(). 2768 */ 2769 static int 2770 sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS) 2771 { 2772 struct sbuf *topo; 2773 int err; 2774 2775 KASSERT(cpu_top != NULL, ("cpu_top isn't initialized")); 2776 2777 topo = sbuf_new(NULL, NULL, 500, SBUF_AUTOEXTEND); 2778 if (topo == NULL) 2779 return (ENOMEM); 2780 2781 sbuf_printf(topo, "<groups>\n"); 2782 err = sysctl_kern_sched_topology_spec_internal(topo, cpu_top, 1); 2783 sbuf_printf(topo, "</groups>\n"); 2784 2785 if (err == 0) { 2786 sbuf_finish(topo); 2787 err = SYSCTL_OUT(req, sbuf_data(topo), sbuf_len(topo)); 2788 } 2789 sbuf_delete(topo); 2790 return (err); 2791 } 2792 2793 #endif 2794 2795 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0, "Scheduler"); 2796 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0, 2797 "Scheduler name"); 2798 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, 2799 "Slice size for timeshare threads"); 2800 SYSCTL_INT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0, 2801 "Interactivity score threshold"); 2802 SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW, &preempt_thresh, 2803 0,"Min priority for preemption, lower priorities have greater precedence"); 2804 SYSCTL_INT(_kern_sched, OID_AUTO, static_boost, CTLFLAG_RW, &static_boost, 2805 0,"Controls whether static kernel priorities are assigned to sleeping threads."); 2806 SYSCTL_INT(_kern_sched, OID_AUTO, idlespins, CTLFLAG_RW, &sched_idlespins, 2807 0,"Number of times idle will spin waiting for new work."); 2808 SYSCTL_INT(_kern_sched, OID_AUTO, idlespinthresh, CTLFLAG_RW, &sched_idlespinthresh, 2809 0,"Threshold before we will permit idle spinning."); 2810 #ifdef SMP 2811 SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0, 2812 "Number of hz ticks to keep thread affinity for"); 2813 SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0, 2814 "Enables the long-term load balancer"); 2815 SYSCTL_INT(_kern_sched, OID_AUTO, balance_interval, CTLFLAG_RW, 2816 &balance_interval, 0, 2817 "Average frequency in stathz ticks to run the long-term balancer"); 2818 SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0, 2819 "Attempts to steal work from other cores before idling"); 2820 SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0, 2821 "Minimum load on remote cpu before we'll steal"); 2822 2823 /* Retrieve SMP topology */ 2824 SYSCTL_PROC(_kern_sched, OID_AUTO, topology_spec, CTLTYPE_STRING | 2825 CTLFLAG_RD, NULL, 0, sysctl_kern_sched_topology_spec, "A", 2826 "XML dump of detected CPU topology"); 2827 2828 #endif 2829 2830 /* ps compat. All cpu percentages from ULE are weighted. */ 2831 static int ccpu = 0; 2832 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 2833