1 /*- 2 * Copyright (c) 2002-2007, Jeffrey Roberson <jeff@freebsd.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice unmodified, this list of conditions, and the following 10 * disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 /* 28 * This file implements the ULE scheduler. ULE supports independent CPU 29 * run queues and fine grain locking. It has superior interactive 30 * performance under load even on uni-processor systems. 31 * 32 * etymology: 33 * ULE is the last three letters in schedule. It owes its name to a 34 * generic user created for a scheduling system by Paul Mikesell at 35 * Isilon Systems and a general lack of creativity on the part of the author. 36 */ 37 38 #include <sys/cdefs.h> 39 __FBSDID("$FreeBSD$"); 40 41 #include "opt_hwpmc_hooks.h" 42 #include "opt_sched.h" 43 44 #include <sys/param.h> 45 #include <sys/systm.h> 46 #include <sys/kdb.h> 47 #include <sys/kernel.h> 48 #include <sys/ktr.h> 49 #include <sys/limits.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 #define KTR_ULE 0 81 82 #define TS_NAME_LEN (MAXCOMLEN + sizeof(" td ") + sizeof(__XSTRING(UINT_MAX))) 83 #define TDQ_NAME_LEN (sizeof("sched lock ") + sizeof(__XSTRING(MAXCPU))) 84 #define TDQ_LOADNAME_LEN (sizeof("CPU ") + sizeof(__XSTRING(MAXCPU)) - 1 + sizeof(" load")) 85 86 /* 87 * Thread scheduler specific section. All fields are protected 88 * by the thread lock. 89 */ 90 struct td_sched { 91 struct runq *ts_runq; /* Run-queue we're queued on. */ 92 short ts_flags; /* TSF_* flags. */ 93 int ts_cpu; /* CPU that we have affinity for. */ 94 int ts_rltick; /* Real last tick, for affinity. */ 95 int ts_slice; /* Ticks of slice remaining. */ 96 u_int ts_slptime; /* Number of ticks we vol. slept */ 97 u_int ts_runtime; /* Number of ticks we were running */ 98 int ts_ltick; /* Last tick that we were running on */ 99 int ts_ftick; /* First tick that we were running on */ 100 int ts_ticks; /* Tick count */ 101 #ifdef KTR 102 char ts_name[TS_NAME_LEN]; 103 #endif 104 }; 105 /* flags kept in ts_flags */ 106 #define TSF_BOUND 0x0001 /* Thread can not migrate. */ 107 #define TSF_XFERABLE 0x0002 /* Thread was added as transferable. */ 108 109 static struct td_sched td_sched0; 110 111 #define THREAD_CAN_MIGRATE(td) ((td)->td_pinned == 0) 112 #define THREAD_CAN_SCHED(td, cpu) \ 113 CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask) 114 115 /* 116 * Priority ranges used for interactive and non-interactive timeshare 117 * threads. The timeshare priorities are split up into four ranges. 118 * The first range handles interactive threads. The last three ranges 119 * (NHALF, x, and NHALF) handle non-interactive threads with the outer 120 * ranges supporting nice values. 121 */ 122 #define PRI_TIMESHARE_RANGE (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE + 1) 123 #define PRI_INTERACT_RANGE ((PRI_TIMESHARE_RANGE - SCHED_PRI_NRESV) / 2) 124 #define PRI_BATCH_RANGE (PRI_TIMESHARE_RANGE - PRI_INTERACT_RANGE) 125 126 #define PRI_MIN_INTERACT PRI_MIN_TIMESHARE 127 #define PRI_MAX_INTERACT (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE - 1) 128 #define PRI_MIN_BATCH (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE) 129 #define PRI_MAX_BATCH PRI_MAX_TIMESHARE 130 131 /* 132 * Cpu percentage computation macros and defines. 133 * 134 * SCHED_TICK_SECS: Number of seconds to average the cpu usage across. 135 * SCHED_TICK_TARG: Number of hz ticks to average the cpu usage across. 136 * SCHED_TICK_MAX: Maximum number of ticks before scaling back. 137 * SCHED_TICK_SHIFT: Shift factor to avoid rounding away results. 138 * SCHED_TICK_HZ: Compute the number of hz ticks for a given ticks count. 139 * SCHED_TICK_TOTAL: Gives the amount of time we've been recording ticks. 140 */ 141 #define SCHED_TICK_SECS 10 142 #define SCHED_TICK_TARG (hz * SCHED_TICK_SECS) 143 #define SCHED_TICK_MAX (SCHED_TICK_TARG + hz) 144 #define SCHED_TICK_SHIFT 10 145 #define SCHED_TICK_HZ(ts) ((ts)->ts_ticks >> SCHED_TICK_SHIFT) 146 #define SCHED_TICK_TOTAL(ts) (max((ts)->ts_ltick - (ts)->ts_ftick, hz)) 147 148 /* 149 * These macros determine priorities for non-interactive threads. They are 150 * assigned a priority based on their recent cpu utilization as expressed 151 * by the ratio of ticks to the tick total. NHALF priorities at the start 152 * and end of the MIN to MAX timeshare range are only reachable with negative 153 * or positive nice respectively. 154 * 155 * PRI_RANGE: Priority range for utilization dependent priorities. 156 * PRI_NRESV: Number of nice values. 157 * PRI_TICKS: Compute a priority in PRI_RANGE from the ticks count and total. 158 * PRI_NICE: Determines the part of the priority inherited from nice. 159 */ 160 #define SCHED_PRI_NRESV (PRIO_MAX - PRIO_MIN) 161 #define SCHED_PRI_NHALF (SCHED_PRI_NRESV / 2) 162 #define SCHED_PRI_MIN (PRI_MIN_BATCH + SCHED_PRI_NHALF) 163 #define SCHED_PRI_MAX (PRI_MAX_BATCH - SCHED_PRI_NHALF) 164 #define SCHED_PRI_RANGE (SCHED_PRI_MAX - SCHED_PRI_MIN + 1) 165 #define SCHED_PRI_TICKS(ts) \ 166 (SCHED_TICK_HZ((ts)) / \ 167 (roundup(SCHED_TICK_TOTAL((ts)), SCHED_PRI_RANGE) / SCHED_PRI_RANGE)) 168 #define SCHED_PRI_NICE(nice) (nice) 169 170 /* 171 * These determine the interactivity of a process. Interactivity differs from 172 * cpu utilization in that it expresses the voluntary time slept vs time ran 173 * while cpu utilization includes all time not running. This more accurately 174 * models the intent of the thread. 175 * 176 * SLP_RUN_MAX: Maximum amount of sleep time + run time we'll accumulate 177 * before throttling back. 178 * SLP_RUN_FORK: Maximum slp+run time to inherit at fork time. 179 * INTERACT_MAX: Maximum interactivity value. Smaller is better. 180 * INTERACT_THRESH: Threshold for placement on the current runq. 181 */ 182 #define SCHED_SLP_RUN_MAX ((hz * 5) << SCHED_TICK_SHIFT) 183 #define SCHED_SLP_RUN_FORK ((hz / 2) << SCHED_TICK_SHIFT) 184 #define SCHED_INTERACT_MAX (100) 185 #define SCHED_INTERACT_HALF (SCHED_INTERACT_MAX / 2) 186 #define SCHED_INTERACT_THRESH (30) 187 188 /* 189 * These parameters determine the slice behavior for batch work. 190 */ 191 #define SCHED_SLICE_DEFAULT_DIVISOR 10 /* ~94 ms, 12 stathz ticks. */ 192 #define SCHED_SLICE_MIN_DIVISOR 6 /* DEFAULT/MIN = ~16 ms. */ 193 194 /* Flags kept in td_flags. */ 195 #define TDF_SLICEEND TDF_SCHED2 /* Thread time slice is over. */ 196 197 /* 198 * tickincr: Converts a stathz tick into a hz domain scaled by 199 * the shift factor. Without the shift the error rate 200 * due to rounding would be unacceptably high. 201 * realstathz: stathz is sometimes 0 and run off of hz. 202 * sched_slice: Runtime of each thread before rescheduling. 203 * preempt_thresh: Priority threshold for preemption and remote IPIs. 204 */ 205 static int sched_interact = SCHED_INTERACT_THRESH; 206 static int tickincr = 8 << SCHED_TICK_SHIFT; 207 static int realstathz = 127; /* reset during boot. */ 208 static int sched_slice = 10; /* reset during boot. */ 209 static int sched_slice_min = 1; /* reset during boot. */ 210 #ifdef PREEMPTION 211 #ifdef FULL_PREEMPTION 212 static int preempt_thresh = PRI_MAX_IDLE; 213 #else 214 static int preempt_thresh = PRI_MIN_KERN; 215 #endif 216 #else 217 static int preempt_thresh = 0; 218 #endif 219 static int static_boost = PRI_MIN_BATCH; 220 static int sched_idlespins = 10000; 221 static int sched_idlespinthresh = -1; 222 223 /* 224 * tdq - per processor runqs and statistics. All fields are protected by the 225 * tdq_lock. The load and lowpri may be accessed without to avoid excess 226 * locking in sched_pickcpu(); 227 */ 228 struct tdq { 229 /* 230 * Ordered to improve efficiency of cpu_search() and switch(). 231 * tdq_lock is padded to avoid false sharing with tdq_load and 232 * tdq_cpu_idle. 233 */ 234 struct mtx_padalign tdq_lock; /* run queue lock. */ 235 struct cpu_group *tdq_cg; /* Pointer to cpu topology. */ 236 volatile int tdq_load; /* Aggregate load. */ 237 volatile int tdq_cpu_idle; /* cpu_idle() is active. */ 238 int tdq_sysload; /* For loadavg, !ITHD load. */ 239 int tdq_transferable; /* Transferable thread count. */ 240 short tdq_switchcnt; /* Switches this tick. */ 241 short tdq_oldswitchcnt; /* Switches last tick. */ 242 u_char tdq_lowpri; /* Lowest priority thread. */ 243 u_char tdq_ipipending; /* IPI pending. */ 244 u_char tdq_idx; /* Current insert index. */ 245 u_char tdq_ridx; /* Current removal index. */ 246 struct runq tdq_realtime; /* real-time run queue. */ 247 struct runq tdq_timeshare; /* timeshare run queue. */ 248 struct runq tdq_idle; /* Queue of IDLE threads. */ 249 char tdq_name[TDQ_NAME_LEN]; 250 #ifdef KTR 251 char tdq_loadname[TDQ_LOADNAME_LEN]; 252 #endif 253 } __aligned(64); 254 255 /* Idle thread states and config. */ 256 #define TDQ_RUNNING 1 257 #define TDQ_IDLE 2 258 259 #ifdef SMP 260 struct cpu_group *cpu_top; /* CPU topology */ 261 262 #define SCHED_AFFINITY_DEFAULT (max(1, hz / 1000)) 263 #define SCHED_AFFINITY(ts, t) ((ts)->ts_rltick > ticks - ((t) * affinity)) 264 265 /* 266 * Run-time tunables. 267 */ 268 static int rebalance = 1; 269 static int balance_interval = 128; /* Default set in sched_initticks(). */ 270 static int affinity; 271 static int steal_idle = 1; 272 static int steal_thresh = 2; 273 274 /* 275 * One thread queue per processor. 276 */ 277 static struct tdq tdq_cpu[MAXCPU]; 278 static struct tdq *balance_tdq; 279 static int balance_ticks; 280 static DPCPU_DEFINE(uint32_t, randomval); 281 282 #define TDQ_SELF() (&tdq_cpu[PCPU_GET(cpuid)]) 283 #define TDQ_CPU(x) (&tdq_cpu[(x)]) 284 #define TDQ_ID(x) ((int)((x) - tdq_cpu)) 285 #else /* !SMP */ 286 static struct tdq tdq_cpu; 287 288 #define TDQ_ID(x) (0) 289 #define TDQ_SELF() (&tdq_cpu) 290 #define TDQ_CPU(x) (&tdq_cpu) 291 #endif 292 293 #define TDQ_LOCK_ASSERT(t, type) mtx_assert(TDQ_LOCKPTR((t)), (type)) 294 #define TDQ_LOCK(t) mtx_lock_spin(TDQ_LOCKPTR((t))) 295 #define TDQ_LOCK_FLAGS(t, f) mtx_lock_spin_flags(TDQ_LOCKPTR((t)), (f)) 296 #define TDQ_UNLOCK(t) mtx_unlock_spin(TDQ_LOCKPTR((t))) 297 #define TDQ_LOCKPTR(t) ((struct mtx *)(&(t)->tdq_lock)) 298 299 static void sched_priority(struct thread *); 300 static void sched_thread_priority(struct thread *, u_char); 301 static int sched_interact_score(struct thread *); 302 static void sched_interact_update(struct thread *); 303 static void sched_interact_fork(struct thread *); 304 static void sched_pctcpu_update(struct td_sched *, int); 305 306 /* Operations on per processor queues */ 307 static struct thread *tdq_choose(struct tdq *); 308 static void tdq_setup(struct tdq *); 309 static void tdq_load_add(struct tdq *, struct thread *); 310 static void tdq_load_rem(struct tdq *, struct thread *); 311 static __inline void tdq_runq_add(struct tdq *, struct thread *, int); 312 static __inline void tdq_runq_rem(struct tdq *, struct thread *); 313 static inline int sched_shouldpreempt(int, int, int); 314 void tdq_print(int cpu); 315 static void runq_print(struct runq *rq); 316 static void tdq_add(struct tdq *, struct thread *, int); 317 #ifdef SMP 318 static int tdq_move(struct tdq *, struct tdq *); 319 static int tdq_idled(struct tdq *); 320 static void tdq_notify(struct tdq *, struct thread *); 321 static struct thread *tdq_steal(struct tdq *, int); 322 static struct thread *runq_steal(struct runq *, int); 323 static int sched_pickcpu(struct thread *, int); 324 static void sched_balance(void); 325 static int sched_balance_pair(struct tdq *, struct tdq *); 326 static inline struct tdq *sched_setcpu(struct thread *, int, int); 327 static inline void thread_unblock_switch(struct thread *, struct mtx *); 328 static struct mtx *sched_switch_migrate(struct tdq *, struct thread *, int); 329 static int sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS); 330 static int sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, 331 struct cpu_group *cg, int indent); 332 #endif 333 334 static void sched_setup(void *dummy); 335 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL); 336 337 static void sched_initticks(void *dummy); 338 SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks, 339 NULL); 340 341 SDT_PROVIDER_DEFINE(sched); 342 343 SDT_PROBE_DEFINE3(sched, , , change__pri, "struct thread *", 344 "struct proc *", "uint8_t"); 345 SDT_PROBE_DEFINE3(sched, , , dequeue, "struct thread *", 346 "struct proc *", "void *"); 347 SDT_PROBE_DEFINE4(sched, , , enqueue, "struct thread *", 348 "struct proc *", "void *", "int"); 349 SDT_PROBE_DEFINE4(sched, , , lend__pri, "struct thread *", 350 "struct proc *", "uint8_t", "struct thread *"); 351 SDT_PROBE_DEFINE2(sched, , , load__change, "int", "int"); 352 SDT_PROBE_DEFINE2(sched, , , off__cpu, "struct thread *", 353 "struct proc *"); 354 SDT_PROBE_DEFINE(sched, , , on__cpu); 355 SDT_PROBE_DEFINE(sched, , , remain__cpu); 356 SDT_PROBE_DEFINE2(sched, , , surrender, "struct thread *", 357 "struct proc *"); 358 359 /* 360 * Print the threads waiting on a run-queue. 361 */ 362 static void 363 runq_print(struct runq *rq) 364 { 365 struct rqhead *rqh; 366 struct thread *td; 367 int pri; 368 int j; 369 int i; 370 371 for (i = 0; i < RQB_LEN; i++) { 372 printf("\t\trunq bits %d 0x%zx\n", 373 i, rq->rq_status.rqb_bits[i]); 374 for (j = 0; j < RQB_BPW; j++) 375 if (rq->rq_status.rqb_bits[i] & (1ul << j)) { 376 pri = j + (i << RQB_L2BPW); 377 rqh = &rq->rq_queues[pri]; 378 TAILQ_FOREACH(td, rqh, td_runq) { 379 printf("\t\t\ttd %p(%s) priority %d rqindex %d pri %d\n", 380 td, td->td_name, td->td_priority, 381 td->td_rqindex, pri); 382 } 383 } 384 } 385 } 386 387 /* 388 * Print the status of a per-cpu thread queue. Should be a ddb show cmd. 389 */ 390 void 391 tdq_print(int cpu) 392 { 393 struct tdq *tdq; 394 395 tdq = TDQ_CPU(cpu); 396 397 printf("tdq %d:\n", TDQ_ID(tdq)); 398 printf("\tlock %p\n", TDQ_LOCKPTR(tdq)); 399 printf("\tLock name: %s\n", tdq->tdq_name); 400 printf("\tload: %d\n", tdq->tdq_load); 401 printf("\tswitch cnt: %d\n", tdq->tdq_switchcnt); 402 printf("\told switch cnt: %d\n", tdq->tdq_oldswitchcnt); 403 printf("\ttimeshare idx: %d\n", tdq->tdq_idx); 404 printf("\ttimeshare ridx: %d\n", tdq->tdq_ridx); 405 printf("\tload transferable: %d\n", tdq->tdq_transferable); 406 printf("\tlowest priority: %d\n", tdq->tdq_lowpri); 407 printf("\trealtime runq:\n"); 408 runq_print(&tdq->tdq_realtime); 409 printf("\ttimeshare runq:\n"); 410 runq_print(&tdq->tdq_timeshare); 411 printf("\tidle runq:\n"); 412 runq_print(&tdq->tdq_idle); 413 } 414 415 static inline int 416 sched_shouldpreempt(int pri, int cpri, int remote) 417 { 418 /* 419 * If the new priority is not better than the current priority there is 420 * nothing to do. 421 */ 422 if (pri >= cpri) 423 return (0); 424 /* 425 * Always preempt idle. 426 */ 427 if (cpri >= PRI_MIN_IDLE) 428 return (1); 429 /* 430 * If preemption is disabled don't preempt others. 431 */ 432 if (preempt_thresh == 0) 433 return (0); 434 /* 435 * Preempt if we exceed the threshold. 436 */ 437 if (pri <= preempt_thresh) 438 return (1); 439 /* 440 * If we're interactive or better and there is non-interactive 441 * or worse running preempt only remote processors. 442 */ 443 if (remote && pri <= PRI_MAX_INTERACT && cpri > PRI_MAX_INTERACT) 444 return (1); 445 return (0); 446 } 447 448 /* 449 * Add a thread to the actual run-queue. Keeps transferable counts up to 450 * date with what is actually on the run-queue. Selects the correct 451 * queue position for timeshare threads. 452 */ 453 static __inline void 454 tdq_runq_add(struct tdq *tdq, struct thread *td, int flags) 455 { 456 struct td_sched *ts; 457 u_char pri; 458 459 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 460 THREAD_LOCK_ASSERT(td, MA_OWNED); 461 462 pri = td->td_priority; 463 ts = td->td_sched; 464 TD_SET_RUNQ(td); 465 if (THREAD_CAN_MIGRATE(td)) { 466 tdq->tdq_transferable++; 467 ts->ts_flags |= TSF_XFERABLE; 468 } 469 if (pri < PRI_MIN_BATCH) { 470 ts->ts_runq = &tdq->tdq_realtime; 471 } else if (pri <= PRI_MAX_BATCH) { 472 ts->ts_runq = &tdq->tdq_timeshare; 473 KASSERT(pri <= PRI_MAX_BATCH && pri >= PRI_MIN_BATCH, 474 ("Invalid priority %d on timeshare runq", pri)); 475 /* 476 * This queue contains only priorities between MIN and MAX 477 * realtime. Use the whole queue to represent these values. 478 */ 479 if ((flags & (SRQ_BORROWING|SRQ_PREEMPTED)) == 0) { 480 pri = RQ_NQS * (pri - PRI_MIN_BATCH) / PRI_BATCH_RANGE; 481 pri = (pri + tdq->tdq_idx) % RQ_NQS; 482 /* 483 * This effectively shortens the queue by one so we 484 * can have a one slot difference between idx and 485 * ridx while we wait for threads to drain. 486 */ 487 if (tdq->tdq_ridx != tdq->tdq_idx && 488 pri == tdq->tdq_ridx) 489 pri = (unsigned char)(pri - 1) % RQ_NQS; 490 } else 491 pri = tdq->tdq_ridx; 492 runq_add_pri(ts->ts_runq, td, pri, flags); 493 return; 494 } else 495 ts->ts_runq = &tdq->tdq_idle; 496 runq_add(ts->ts_runq, td, flags); 497 } 498 499 /* 500 * Remove a thread from a run-queue. This typically happens when a thread 501 * is selected to run. Running threads are not on the queue and the 502 * transferable count does not reflect them. 503 */ 504 static __inline void 505 tdq_runq_rem(struct tdq *tdq, struct thread *td) 506 { 507 struct td_sched *ts; 508 509 ts = td->td_sched; 510 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 511 KASSERT(ts->ts_runq != NULL, 512 ("tdq_runq_remove: thread %p null ts_runq", td)); 513 if (ts->ts_flags & TSF_XFERABLE) { 514 tdq->tdq_transferable--; 515 ts->ts_flags &= ~TSF_XFERABLE; 516 } 517 if (ts->ts_runq == &tdq->tdq_timeshare) { 518 if (tdq->tdq_idx != tdq->tdq_ridx) 519 runq_remove_idx(ts->ts_runq, td, &tdq->tdq_ridx); 520 else 521 runq_remove_idx(ts->ts_runq, td, NULL); 522 } else 523 runq_remove(ts->ts_runq, td); 524 } 525 526 /* 527 * Load is maintained for all threads RUNNING and ON_RUNQ. Add the load 528 * for this thread to the referenced thread queue. 529 */ 530 static void 531 tdq_load_add(struct tdq *tdq, struct thread *td) 532 { 533 534 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 535 THREAD_LOCK_ASSERT(td, MA_OWNED); 536 537 tdq->tdq_load++; 538 if ((td->td_flags & TDF_NOLOAD) == 0) 539 tdq->tdq_sysload++; 540 KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load); 541 SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load); 542 } 543 544 /* 545 * Remove the load from a thread that is transitioning to a sleep state or 546 * exiting. 547 */ 548 static void 549 tdq_load_rem(struct tdq *tdq, struct thread *td) 550 { 551 552 THREAD_LOCK_ASSERT(td, MA_OWNED); 553 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 554 KASSERT(tdq->tdq_load != 0, 555 ("tdq_load_rem: Removing with 0 load on queue %d", TDQ_ID(tdq))); 556 557 tdq->tdq_load--; 558 if ((td->td_flags & TDF_NOLOAD) == 0) 559 tdq->tdq_sysload--; 560 KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load); 561 SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load); 562 } 563 564 /* 565 * Bound timeshare latency by decreasing slice size as load increases. We 566 * consider the maximum latency as the sum of the threads waiting to run 567 * aside from curthread and target no more than sched_slice latency but 568 * no less than sched_slice_min runtime. 569 */ 570 static inline int 571 tdq_slice(struct tdq *tdq) 572 { 573 int load; 574 575 /* 576 * It is safe to use sys_load here because this is called from 577 * contexts where timeshare threads are running and so there 578 * cannot be higher priority load in the system. 579 */ 580 load = tdq->tdq_sysload - 1; 581 if (load >= SCHED_SLICE_MIN_DIVISOR) 582 return (sched_slice_min); 583 if (load <= 1) 584 return (sched_slice); 585 return (sched_slice / load); 586 } 587 588 /* 589 * Set lowpri to its exact value by searching the run-queue and 590 * evaluating curthread. curthread may be passed as an optimization. 591 */ 592 static void 593 tdq_setlowpri(struct tdq *tdq, struct thread *ctd) 594 { 595 struct thread *td; 596 597 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 598 if (ctd == NULL) 599 ctd = pcpu_find(TDQ_ID(tdq))->pc_curthread; 600 td = tdq_choose(tdq); 601 if (td == NULL || td->td_priority > ctd->td_priority) 602 tdq->tdq_lowpri = ctd->td_priority; 603 else 604 tdq->tdq_lowpri = td->td_priority; 605 } 606 607 #ifdef SMP 608 /* 609 * We need some randomness. Implement a classic Linear Congruential 610 * Generator X_{n+1}=(aX_n+c) mod m. These values are optimized for 611 * m = 2^32, a = 69069 and c = 5. We only return the upper 16 bits 612 * of the random state (in the low bits of our answer) to keep 613 * the maximum randomness. 614 */ 615 static uint32_t 616 sched_random(void) 617 { 618 uint32_t *rndptr; 619 620 rndptr = DPCPU_PTR(randomval); 621 *rndptr = *rndptr * 69069 + 5; 622 623 return (*rndptr >> 16); 624 } 625 626 struct cpu_search { 627 cpuset_t cs_mask; 628 u_int cs_prefer; 629 int cs_pri; /* Min priority for low. */ 630 int cs_limit; /* Max load for low, min load for high. */ 631 int cs_cpu; 632 int cs_load; 633 }; 634 635 #define CPU_SEARCH_LOWEST 0x1 636 #define CPU_SEARCH_HIGHEST 0x2 637 #define CPU_SEARCH_BOTH (CPU_SEARCH_LOWEST|CPU_SEARCH_HIGHEST) 638 639 #define CPUSET_FOREACH(cpu, mask) \ 640 for ((cpu) = 0; (cpu) <= mp_maxid; (cpu)++) \ 641 if (CPU_ISSET(cpu, &mask)) 642 643 static __always_inline int cpu_search(const struct cpu_group *cg, 644 struct cpu_search *low, struct cpu_search *high, const int match); 645 int __noinline cpu_search_lowest(const struct cpu_group *cg, 646 struct cpu_search *low); 647 int __noinline cpu_search_highest(const struct cpu_group *cg, 648 struct cpu_search *high); 649 int __noinline cpu_search_both(const struct cpu_group *cg, 650 struct cpu_search *low, struct cpu_search *high); 651 652 /* 653 * Search the tree of cpu_groups for the lowest or highest loaded cpu 654 * according to the match argument. This routine actually compares the 655 * load on all paths through the tree and finds the least loaded cpu on 656 * the least loaded path, which may differ from the least loaded cpu in 657 * the system. This balances work among caches and busses. 658 * 659 * This inline is instantiated in three forms below using constants for the 660 * match argument. It is reduced to the minimum set for each case. It is 661 * also recursive to the depth of the tree. 662 */ 663 static __always_inline int 664 cpu_search(const struct cpu_group *cg, struct cpu_search *low, 665 struct cpu_search *high, const int match) 666 { 667 struct cpu_search lgroup; 668 struct cpu_search hgroup; 669 cpuset_t cpumask; 670 struct cpu_group *child; 671 struct tdq *tdq; 672 int cpu, i, hload, lload, load, total, rnd; 673 674 total = 0; 675 cpumask = cg->cg_mask; 676 if (match & CPU_SEARCH_LOWEST) { 677 lload = INT_MAX; 678 lgroup = *low; 679 } 680 if (match & CPU_SEARCH_HIGHEST) { 681 hload = INT_MIN; 682 hgroup = *high; 683 } 684 685 /* Iterate through the child CPU groups and then remaining CPUs. */ 686 for (i = cg->cg_children, cpu = mp_maxid; ; ) { 687 if (i == 0) { 688 #ifdef HAVE_INLINE_FFSL 689 cpu = CPU_FFS(&cpumask) - 1; 690 #else 691 while (cpu >= 0 && !CPU_ISSET(cpu, &cpumask)) 692 cpu--; 693 #endif 694 if (cpu < 0) 695 break; 696 child = NULL; 697 } else 698 child = &cg->cg_child[i - 1]; 699 700 if (match & CPU_SEARCH_LOWEST) 701 lgroup.cs_cpu = -1; 702 if (match & CPU_SEARCH_HIGHEST) 703 hgroup.cs_cpu = -1; 704 if (child) { /* Handle child CPU group. */ 705 CPU_NAND(&cpumask, &child->cg_mask); 706 switch (match) { 707 case CPU_SEARCH_LOWEST: 708 load = cpu_search_lowest(child, &lgroup); 709 break; 710 case CPU_SEARCH_HIGHEST: 711 load = cpu_search_highest(child, &hgroup); 712 break; 713 case CPU_SEARCH_BOTH: 714 load = cpu_search_both(child, &lgroup, &hgroup); 715 break; 716 } 717 } else { /* Handle child CPU. */ 718 CPU_CLR(cpu, &cpumask); 719 tdq = TDQ_CPU(cpu); 720 load = tdq->tdq_load * 256; 721 rnd = sched_random() % 32; 722 if (match & CPU_SEARCH_LOWEST) { 723 if (cpu == low->cs_prefer) 724 load -= 64; 725 /* If that CPU is allowed and get data. */ 726 if (tdq->tdq_lowpri > lgroup.cs_pri && 727 tdq->tdq_load <= lgroup.cs_limit && 728 CPU_ISSET(cpu, &lgroup.cs_mask)) { 729 lgroup.cs_cpu = cpu; 730 lgroup.cs_load = load - rnd; 731 } 732 } 733 if (match & CPU_SEARCH_HIGHEST) 734 if (tdq->tdq_load >= hgroup.cs_limit && 735 tdq->tdq_transferable && 736 CPU_ISSET(cpu, &hgroup.cs_mask)) { 737 hgroup.cs_cpu = cpu; 738 hgroup.cs_load = load - rnd; 739 } 740 } 741 total += load; 742 743 /* We have info about child item. Compare it. */ 744 if (match & CPU_SEARCH_LOWEST) { 745 if (lgroup.cs_cpu >= 0 && 746 (load < lload || 747 (load == lload && lgroup.cs_load < low->cs_load))) { 748 lload = load; 749 low->cs_cpu = lgroup.cs_cpu; 750 low->cs_load = lgroup.cs_load; 751 } 752 } 753 if (match & CPU_SEARCH_HIGHEST) 754 if (hgroup.cs_cpu >= 0 && 755 (load > hload || 756 (load == hload && hgroup.cs_load > high->cs_load))) { 757 hload = load; 758 high->cs_cpu = hgroup.cs_cpu; 759 high->cs_load = hgroup.cs_load; 760 } 761 if (child) { 762 i--; 763 if (i == 0 && CPU_EMPTY(&cpumask)) 764 break; 765 } 766 #ifndef HAVE_INLINE_FFSL 767 else 768 cpu--; 769 #endif 770 } 771 return (total); 772 } 773 774 /* 775 * cpu_search instantiations must pass constants to maintain the inline 776 * optimization. 777 */ 778 int 779 cpu_search_lowest(const struct cpu_group *cg, struct cpu_search *low) 780 { 781 return cpu_search(cg, low, NULL, CPU_SEARCH_LOWEST); 782 } 783 784 int 785 cpu_search_highest(const struct cpu_group *cg, struct cpu_search *high) 786 { 787 return cpu_search(cg, NULL, high, CPU_SEARCH_HIGHEST); 788 } 789 790 int 791 cpu_search_both(const struct cpu_group *cg, struct cpu_search *low, 792 struct cpu_search *high) 793 { 794 return cpu_search(cg, low, high, CPU_SEARCH_BOTH); 795 } 796 797 /* 798 * Find the cpu with the least load via the least loaded path that has a 799 * lowpri greater than pri pri. A pri of -1 indicates any priority is 800 * acceptable. 801 */ 802 static inline int 803 sched_lowest(const struct cpu_group *cg, cpuset_t mask, int pri, int maxload, 804 int prefer) 805 { 806 struct cpu_search low; 807 808 low.cs_cpu = -1; 809 low.cs_prefer = prefer; 810 low.cs_mask = mask; 811 low.cs_pri = pri; 812 low.cs_limit = maxload; 813 cpu_search_lowest(cg, &low); 814 return low.cs_cpu; 815 } 816 817 /* 818 * Find the cpu with the highest load via the highest loaded path. 819 */ 820 static inline int 821 sched_highest(const struct cpu_group *cg, cpuset_t mask, int minload) 822 { 823 struct cpu_search high; 824 825 high.cs_cpu = -1; 826 high.cs_mask = mask; 827 high.cs_limit = minload; 828 cpu_search_highest(cg, &high); 829 return high.cs_cpu; 830 } 831 832 static void 833 sched_balance_group(struct cpu_group *cg) 834 { 835 cpuset_t hmask, lmask; 836 int high, low, anylow; 837 838 CPU_FILL(&hmask); 839 for (;;) { 840 high = sched_highest(cg, hmask, 1); 841 /* Stop if there is no more CPU with transferrable threads. */ 842 if (high == -1) 843 break; 844 CPU_CLR(high, &hmask); 845 CPU_COPY(&hmask, &lmask); 846 /* Stop if there is no more CPU left for low. */ 847 if (CPU_EMPTY(&lmask)) 848 break; 849 anylow = 1; 850 nextlow: 851 low = sched_lowest(cg, lmask, -1, 852 TDQ_CPU(high)->tdq_load - 1, high); 853 /* Stop if we looked well and found no less loaded CPU. */ 854 if (anylow && low == -1) 855 break; 856 /* Go to next high if we found no less loaded CPU. */ 857 if (low == -1) 858 continue; 859 /* Transfer thread from high to low. */ 860 if (sched_balance_pair(TDQ_CPU(high), TDQ_CPU(low))) { 861 /* CPU that got thread can no longer be a donor. */ 862 CPU_CLR(low, &hmask); 863 } else { 864 /* 865 * If failed, then there is no threads on high 866 * that can run on this low. Drop low from low 867 * mask and look for different one. 868 */ 869 CPU_CLR(low, &lmask); 870 anylow = 0; 871 goto nextlow; 872 } 873 } 874 } 875 876 static void 877 sched_balance(void) 878 { 879 struct tdq *tdq; 880 881 if (smp_started == 0 || rebalance == 0) 882 return; 883 884 balance_ticks = max(balance_interval / 2, 1) + 885 (sched_random() % balance_interval); 886 tdq = TDQ_SELF(); 887 TDQ_UNLOCK(tdq); 888 sched_balance_group(cpu_top); 889 TDQ_LOCK(tdq); 890 } 891 892 /* 893 * Lock two thread queues using their address to maintain lock order. 894 */ 895 static void 896 tdq_lock_pair(struct tdq *one, struct tdq *two) 897 { 898 if (one < two) { 899 TDQ_LOCK(one); 900 TDQ_LOCK_FLAGS(two, MTX_DUPOK); 901 } else { 902 TDQ_LOCK(two); 903 TDQ_LOCK_FLAGS(one, MTX_DUPOK); 904 } 905 } 906 907 /* 908 * Unlock two thread queues. Order is not important here. 909 */ 910 static void 911 tdq_unlock_pair(struct tdq *one, struct tdq *two) 912 { 913 TDQ_UNLOCK(one); 914 TDQ_UNLOCK(two); 915 } 916 917 /* 918 * Transfer load between two imbalanced thread queues. 919 */ 920 static int 921 sched_balance_pair(struct tdq *high, struct tdq *low) 922 { 923 int moved; 924 int cpu; 925 926 tdq_lock_pair(high, low); 927 moved = 0; 928 /* 929 * Determine what the imbalance is and then adjust that to how many 930 * threads we actually have to give up (transferable). 931 */ 932 if (high->tdq_transferable != 0 && high->tdq_load > low->tdq_load && 933 (moved = tdq_move(high, low)) > 0) { 934 /* 935 * In case the target isn't the current cpu IPI it to force a 936 * reschedule with the new workload. 937 */ 938 cpu = TDQ_ID(low); 939 if (cpu != PCPU_GET(cpuid)) 940 ipi_cpu(cpu, IPI_PREEMPT); 941 } 942 tdq_unlock_pair(high, low); 943 return (moved); 944 } 945 946 /* 947 * Move a thread from one thread queue to another. 948 */ 949 static int 950 tdq_move(struct tdq *from, struct tdq *to) 951 { 952 struct td_sched *ts; 953 struct thread *td; 954 struct tdq *tdq; 955 int cpu; 956 957 TDQ_LOCK_ASSERT(from, MA_OWNED); 958 TDQ_LOCK_ASSERT(to, MA_OWNED); 959 960 tdq = from; 961 cpu = TDQ_ID(to); 962 td = tdq_steal(tdq, cpu); 963 if (td == NULL) 964 return (0); 965 ts = td->td_sched; 966 /* 967 * Although the run queue is locked the thread may be blocked. Lock 968 * it to clear this and acquire the run-queue lock. 969 */ 970 thread_lock(td); 971 /* Drop recursive lock on from acquired via thread_lock(). */ 972 TDQ_UNLOCK(from); 973 sched_rem(td); 974 ts->ts_cpu = cpu; 975 td->td_lock = TDQ_LOCKPTR(to); 976 tdq_add(to, td, SRQ_YIELDING); 977 return (1); 978 } 979 980 /* 981 * This tdq has idled. Try to steal a thread from another cpu and switch 982 * to it. 983 */ 984 static int 985 tdq_idled(struct tdq *tdq) 986 { 987 struct cpu_group *cg; 988 struct tdq *steal; 989 cpuset_t mask; 990 int thresh; 991 int cpu; 992 993 if (smp_started == 0 || steal_idle == 0) 994 return (1); 995 CPU_FILL(&mask); 996 CPU_CLR(PCPU_GET(cpuid), &mask); 997 /* We don't want to be preempted while we're iterating. */ 998 spinlock_enter(); 999 for (cg = tdq->tdq_cg; cg != NULL; ) { 1000 if ((cg->cg_flags & CG_FLAG_THREAD) == 0) 1001 thresh = steal_thresh; 1002 else 1003 thresh = 1; 1004 cpu = sched_highest(cg, mask, thresh); 1005 if (cpu == -1) { 1006 cg = cg->cg_parent; 1007 continue; 1008 } 1009 steal = TDQ_CPU(cpu); 1010 CPU_CLR(cpu, &mask); 1011 tdq_lock_pair(tdq, steal); 1012 if (steal->tdq_load < thresh || steal->tdq_transferable == 0) { 1013 tdq_unlock_pair(tdq, steal); 1014 continue; 1015 } 1016 /* 1017 * If a thread was added while interrupts were disabled don't 1018 * steal one here. If we fail to acquire one due to affinity 1019 * restrictions loop again with this cpu removed from the 1020 * set. 1021 */ 1022 if (tdq->tdq_load == 0 && tdq_move(steal, tdq) == 0) { 1023 tdq_unlock_pair(tdq, steal); 1024 continue; 1025 } 1026 spinlock_exit(); 1027 TDQ_UNLOCK(steal); 1028 mi_switch(SW_VOL | SWT_IDLE, NULL); 1029 thread_unlock(curthread); 1030 1031 return (0); 1032 } 1033 spinlock_exit(); 1034 return (1); 1035 } 1036 1037 /* 1038 * Notify a remote cpu of new work. Sends an IPI if criteria are met. 1039 */ 1040 static void 1041 tdq_notify(struct tdq *tdq, struct thread *td) 1042 { 1043 struct thread *ctd; 1044 int pri; 1045 int cpu; 1046 1047 if (tdq->tdq_ipipending) 1048 return; 1049 cpu = td->td_sched->ts_cpu; 1050 pri = td->td_priority; 1051 ctd = pcpu_find(cpu)->pc_curthread; 1052 if (!sched_shouldpreempt(pri, ctd->td_priority, 1)) 1053 return; 1054 1055 /* 1056 * Make sure that our caller's earlier update to tdq_load is 1057 * globally visible before we read tdq_cpu_idle. Idle thread 1058 * accesses both of them without locks, and the order is important. 1059 */ 1060 atomic_thread_fence_seq_cst(); 1061 1062 if (TD_IS_IDLETHREAD(ctd)) { 1063 /* 1064 * If the MD code has an idle wakeup routine try that before 1065 * falling back to IPI. 1066 */ 1067 if (!tdq->tdq_cpu_idle || cpu_idle_wakeup(cpu)) 1068 return; 1069 } 1070 tdq->tdq_ipipending = 1; 1071 ipi_cpu(cpu, IPI_PREEMPT); 1072 } 1073 1074 /* 1075 * Steals load from a timeshare queue. Honors the rotating queue head 1076 * index. 1077 */ 1078 static struct thread * 1079 runq_steal_from(struct runq *rq, int cpu, u_char start) 1080 { 1081 struct rqbits *rqb; 1082 struct rqhead *rqh; 1083 struct thread *td, *first; 1084 int bit; 1085 int i; 1086 1087 rqb = &rq->rq_status; 1088 bit = start & (RQB_BPW -1); 1089 first = NULL; 1090 again: 1091 for (i = RQB_WORD(start); i < RQB_LEN; bit = 0, i++) { 1092 if (rqb->rqb_bits[i] == 0) 1093 continue; 1094 if (bit == 0) 1095 bit = RQB_FFS(rqb->rqb_bits[i]); 1096 for (; bit < RQB_BPW; bit++) { 1097 if ((rqb->rqb_bits[i] & (1ul << bit)) == 0) 1098 continue; 1099 rqh = &rq->rq_queues[bit + (i << RQB_L2BPW)]; 1100 TAILQ_FOREACH(td, rqh, td_runq) { 1101 if (first && THREAD_CAN_MIGRATE(td) && 1102 THREAD_CAN_SCHED(td, cpu)) 1103 return (td); 1104 first = td; 1105 } 1106 } 1107 } 1108 if (start != 0) { 1109 start = 0; 1110 goto again; 1111 } 1112 1113 if (first && THREAD_CAN_MIGRATE(first) && 1114 THREAD_CAN_SCHED(first, cpu)) 1115 return (first); 1116 return (NULL); 1117 } 1118 1119 /* 1120 * Steals load from a standard linear queue. 1121 */ 1122 static struct thread * 1123 runq_steal(struct runq *rq, int cpu) 1124 { 1125 struct rqhead *rqh; 1126 struct rqbits *rqb; 1127 struct thread *td; 1128 int word; 1129 int bit; 1130 1131 rqb = &rq->rq_status; 1132 for (word = 0; word < RQB_LEN; word++) { 1133 if (rqb->rqb_bits[word] == 0) 1134 continue; 1135 for (bit = 0; bit < RQB_BPW; bit++) { 1136 if ((rqb->rqb_bits[word] & (1ul << bit)) == 0) 1137 continue; 1138 rqh = &rq->rq_queues[bit + (word << RQB_L2BPW)]; 1139 TAILQ_FOREACH(td, rqh, td_runq) 1140 if (THREAD_CAN_MIGRATE(td) && 1141 THREAD_CAN_SCHED(td, cpu)) 1142 return (td); 1143 } 1144 } 1145 return (NULL); 1146 } 1147 1148 /* 1149 * Attempt to steal a thread in priority order from a thread queue. 1150 */ 1151 static struct thread * 1152 tdq_steal(struct tdq *tdq, int cpu) 1153 { 1154 struct thread *td; 1155 1156 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1157 if ((td = runq_steal(&tdq->tdq_realtime, cpu)) != NULL) 1158 return (td); 1159 if ((td = runq_steal_from(&tdq->tdq_timeshare, 1160 cpu, tdq->tdq_ridx)) != NULL) 1161 return (td); 1162 return (runq_steal(&tdq->tdq_idle, cpu)); 1163 } 1164 1165 /* 1166 * Sets the thread lock and ts_cpu to match the requested cpu. Unlocks the 1167 * current lock and returns with the assigned queue locked. 1168 */ 1169 static inline struct tdq * 1170 sched_setcpu(struct thread *td, int cpu, int flags) 1171 { 1172 1173 struct tdq *tdq; 1174 1175 THREAD_LOCK_ASSERT(td, MA_OWNED); 1176 tdq = TDQ_CPU(cpu); 1177 td->td_sched->ts_cpu = cpu; 1178 /* 1179 * If the lock matches just return the queue. 1180 */ 1181 if (td->td_lock == TDQ_LOCKPTR(tdq)) 1182 return (tdq); 1183 #ifdef notyet 1184 /* 1185 * If the thread isn't running its lockptr is a 1186 * turnstile or a sleepqueue. We can just lock_set without 1187 * blocking. 1188 */ 1189 if (TD_CAN_RUN(td)) { 1190 TDQ_LOCK(tdq); 1191 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 1192 return (tdq); 1193 } 1194 #endif 1195 /* 1196 * The hard case, migration, we need to block the thread first to 1197 * prevent order reversals with other cpus locks. 1198 */ 1199 spinlock_enter(); 1200 thread_lock_block(td); 1201 TDQ_LOCK(tdq); 1202 thread_lock_unblock(td, TDQ_LOCKPTR(tdq)); 1203 spinlock_exit(); 1204 return (tdq); 1205 } 1206 1207 SCHED_STAT_DEFINE(pickcpu_intrbind, "Soft interrupt binding"); 1208 SCHED_STAT_DEFINE(pickcpu_idle_affinity, "Picked idle cpu based on affinity"); 1209 SCHED_STAT_DEFINE(pickcpu_affinity, "Picked cpu based on affinity"); 1210 SCHED_STAT_DEFINE(pickcpu_lowest, "Selected lowest load"); 1211 SCHED_STAT_DEFINE(pickcpu_local, "Migrated to current cpu"); 1212 SCHED_STAT_DEFINE(pickcpu_migration, "Selection may have caused migration"); 1213 1214 static int 1215 sched_pickcpu(struct thread *td, int flags) 1216 { 1217 struct cpu_group *cg, *ccg; 1218 struct td_sched *ts; 1219 struct tdq *tdq; 1220 cpuset_t mask; 1221 int cpu, pri, self; 1222 1223 self = PCPU_GET(cpuid); 1224 ts = td->td_sched; 1225 if (smp_started == 0) 1226 return (self); 1227 /* 1228 * Don't migrate a running thread from sched_switch(). 1229 */ 1230 if ((flags & SRQ_OURSELF) || !THREAD_CAN_MIGRATE(td)) 1231 return (ts->ts_cpu); 1232 /* 1233 * Prefer to run interrupt threads on the processors that generate 1234 * the interrupt. 1235 */ 1236 pri = td->td_priority; 1237 if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_SCHED(td, self) && 1238 curthread->td_intr_nesting_level && ts->ts_cpu != self) { 1239 SCHED_STAT_INC(pickcpu_intrbind); 1240 ts->ts_cpu = self; 1241 if (TDQ_CPU(self)->tdq_lowpri > pri) { 1242 SCHED_STAT_INC(pickcpu_affinity); 1243 return (ts->ts_cpu); 1244 } 1245 } 1246 /* 1247 * If the thread can run on the last cpu and the affinity has not 1248 * expired or it is idle run it there. 1249 */ 1250 tdq = TDQ_CPU(ts->ts_cpu); 1251 cg = tdq->tdq_cg; 1252 if (THREAD_CAN_SCHED(td, ts->ts_cpu) && 1253 tdq->tdq_lowpri >= PRI_MIN_IDLE && 1254 SCHED_AFFINITY(ts, CG_SHARE_L2)) { 1255 if (cg->cg_flags & CG_FLAG_THREAD) { 1256 CPUSET_FOREACH(cpu, cg->cg_mask) { 1257 if (TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE) 1258 break; 1259 } 1260 } else 1261 cpu = INT_MAX; 1262 if (cpu > mp_maxid) { 1263 SCHED_STAT_INC(pickcpu_idle_affinity); 1264 return (ts->ts_cpu); 1265 } 1266 } 1267 /* 1268 * Search for the last level cache CPU group in the tree. 1269 * Skip caches with expired affinity time and SMT groups. 1270 * Affinity to higher level caches will be handled less aggressively. 1271 */ 1272 for (ccg = NULL; cg != NULL; cg = cg->cg_parent) { 1273 if (cg->cg_flags & CG_FLAG_THREAD) 1274 continue; 1275 if (!SCHED_AFFINITY(ts, cg->cg_level)) 1276 continue; 1277 ccg = cg; 1278 } 1279 if (ccg != NULL) 1280 cg = ccg; 1281 cpu = -1; 1282 /* Search the group for the less loaded idle CPU we can run now. */ 1283 mask = td->td_cpuset->cs_mask; 1284 if (cg != NULL && cg != cpu_top && 1285 CPU_CMP(&cg->cg_mask, &cpu_top->cg_mask) != 0) 1286 cpu = sched_lowest(cg, mask, max(pri, PRI_MAX_TIMESHARE), 1287 INT_MAX, ts->ts_cpu); 1288 /* Search globally for the less loaded CPU we can run now. */ 1289 if (cpu == -1) 1290 cpu = sched_lowest(cpu_top, mask, pri, INT_MAX, ts->ts_cpu); 1291 /* Search globally for the less loaded CPU. */ 1292 if (cpu == -1) 1293 cpu = sched_lowest(cpu_top, mask, -1, INT_MAX, ts->ts_cpu); 1294 KASSERT(cpu != -1, ("sched_pickcpu: Failed to find a cpu.")); 1295 /* 1296 * Compare the lowest loaded cpu to current cpu. 1297 */ 1298 if (THREAD_CAN_SCHED(td, self) && TDQ_CPU(self)->tdq_lowpri > pri && 1299 TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE && 1300 TDQ_CPU(self)->tdq_load <= TDQ_CPU(cpu)->tdq_load + 1) { 1301 SCHED_STAT_INC(pickcpu_local); 1302 cpu = self; 1303 } else 1304 SCHED_STAT_INC(pickcpu_lowest); 1305 if (cpu != ts->ts_cpu) 1306 SCHED_STAT_INC(pickcpu_migration); 1307 return (cpu); 1308 } 1309 #endif 1310 1311 /* 1312 * Pick the highest priority task we have and return it. 1313 */ 1314 static struct thread * 1315 tdq_choose(struct tdq *tdq) 1316 { 1317 struct thread *td; 1318 1319 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1320 td = runq_choose(&tdq->tdq_realtime); 1321 if (td != NULL) 1322 return (td); 1323 td = runq_choose_from(&tdq->tdq_timeshare, tdq->tdq_ridx); 1324 if (td != NULL) { 1325 KASSERT(td->td_priority >= PRI_MIN_BATCH, 1326 ("tdq_choose: Invalid priority on timeshare queue %d", 1327 td->td_priority)); 1328 return (td); 1329 } 1330 td = runq_choose(&tdq->tdq_idle); 1331 if (td != NULL) { 1332 KASSERT(td->td_priority >= PRI_MIN_IDLE, 1333 ("tdq_choose: Invalid priority on idle queue %d", 1334 td->td_priority)); 1335 return (td); 1336 } 1337 1338 return (NULL); 1339 } 1340 1341 /* 1342 * Initialize a thread queue. 1343 */ 1344 static void 1345 tdq_setup(struct tdq *tdq) 1346 { 1347 1348 if (bootverbose) 1349 printf("ULE: setup cpu %d\n", TDQ_ID(tdq)); 1350 runq_init(&tdq->tdq_realtime); 1351 runq_init(&tdq->tdq_timeshare); 1352 runq_init(&tdq->tdq_idle); 1353 snprintf(tdq->tdq_name, sizeof(tdq->tdq_name), 1354 "sched lock %d", (int)TDQ_ID(tdq)); 1355 mtx_init(&tdq->tdq_lock, tdq->tdq_name, "sched lock", 1356 MTX_SPIN | MTX_RECURSE); 1357 #ifdef KTR 1358 snprintf(tdq->tdq_loadname, sizeof(tdq->tdq_loadname), 1359 "CPU %d load", (int)TDQ_ID(tdq)); 1360 #endif 1361 } 1362 1363 #ifdef SMP 1364 static void 1365 sched_setup_smp(void) 1366 { 1367 struct tdq *tdq; 1368 int i; 1369 1370 cpu_top = smp_topo(); 1371 CPU_FOREACH(i) { 1372 tdq = TDQ_CPU(i); 1373 tdq_setup(tdq); 1374 tdq->tdq_cg = smp_topo_find(cpu_top, i); 1375 if (tdq->tdq_cg == NULL) 1376 panic("Can't find cpu group for %d\n", i); 1377 } 1378 balance_tdq = TDQ_SELF(); 1379 sched_balance(); 1380 } 1381 #endif 1382 1383 /* 1384 * Setup the thread queues and initialize the topology based on MD 1385 * information. 1386 */ 1387 static void 1388 sched_setup(void *dummy) 1389 { 1390 struct tdq *tdq; 1391 1392 tdq = TDQ_SELF(); 1393 #ifdef SMP 1394 sched_setup_smp(); 1395 #else 1396 tdq_setup(tdq); 1397 #endif 1398 1399 /* Add thread0's load since it's running. */ 1400 TDQ_LOCK(tdq); 1401 thread0.td_lock = TDQ_LOCKPTR(TDQ_SELF()); 1402 tdq_load_add(tdq, &thread0); 1403 tdq->tdq_lowpri = thread0.td_priority; 1404 TDQ_UNLOCK(tdq); 1405 } 1406 1407 /* 1408 * This routine determines time constants after stathz and hz are setup. 1409 */ 1410 /* ARGSUSED */ 1411 static void 1412 sched_initticks(void *dummy) 1413 { 1414 int incr; 1415 1416 realstathz = stathz ? stathz : hz; 1417 sched_slice = realstathz / SCHED_SLICE_DEFAULT_DIVISOR; 1418 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 1419 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 1420 realstathz); 1421 1422 /* 1423 * tickincr is shifted out by 10 to avoid rounding errors due to 1424 * hz not being evenly divisible by stathz on all platforms. 1425 */ 1426 incr = (hz << SCHED_TICK_SHIFT) / realstathz; 1427 /* 1428 * This does not work for values of stathz that are more than 1429 * 1 << SCHED_TICK_SHIFT * hz. In practice this does not happen. 1430 */ 1431 if (incr == 0) 1432 incr = 1; 1433 tickincr = incr; 1434 #ifdef SMP 1435 /* 1436 * Set the default balance interval now that we know 1437 * what realstathz is. 1438 */ 1439 balance_interval = realstathz; 1440 affinity = SCHED_AFFINITY_DEFAULT; 1441 #endif 1442 if (sched_idlespinthresh < 0) 1443 sched_idlespinthresh = 2 * max(10000, 6 * hz) / realstathz; 1444 } 1445 1446 1447 /* 1448 * This is the core of the interactivity algorithm. Determines a score based 1449 * on past behavior. It is the ratio of sleep time to run time scaled to 1450 * a [0, 100] integer. This is the voluntary sleep time of a process, which 1451 * differs from the cpu usage because it does not account for time spent 1452 * waiting on a run-queue. Would be prettier if we had floating point. 1453 */ 1454 static int 1455 sched_interact_score(struct thread *td) 1456 { 1457 struct td_sched *ts; 1458 int div; 1459 1460 ts = td->td_sched; 1461 /* 1462 * The score is only needed if this is likely to be an interactive 1463 * task. Don't go through the expense of computing it if there's 1464 * no chance. 1465 */ 1466 if (sched_interact <= SCHED_INTERACT_HALF && 1467 ts->ts_runtime >= ts->ts_slptime) 1468 return (SCHED_INTERACT_HALF); 1469 1470 if (ts->ts_runtime > ts->ts_slptime) { 1471 div = max(1, ts->ts_runtime / SCHED_INTERACT_HALF); 1472 return (SCHED_INTERACT_HALF + 1473 (SCHED_INTERACT_HALF - (ts->ts_slptime / div))); 1474 } 1475 if (ts->ts_slptime > ts->ts_runtime) { 1476 div = max(1, ts->ts_slptime / SCHED_INTERACT_HALF); 1477 return (ts->ts_runtime / div); 1478 } 1479 /* runtime == slptime */ 1480 if (ts->ts_runtime) 1481 return (SCHED_INTERACT_HALF); 1482 1483 /* 1484 * This can happen if slptime and runtime are 0. 1485 */ 1486 return (0); 1487 1488 } 1489 1490 /* 1491 * Scale the scheduling priority according to the "interactivity" of this 1492 * process. 1493 */ 1494 static void 1495 sched_priority(struct thread *td) 1496 { 1497 int score; 1498 int pri; 1499 1500 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 1501 return; 1502 /* 1503 * If the score is interactive we place the thread in the realtime 1504 * queue with a priority that is less than kernel and interrupt 1505 * priorities. These threads are not subject to nice restrictions. 1506 * 1507 * Scores greater than this are placed on the normal timeshare queue 1508 * where the priority is partially decided by the most recent cpu 1509 * utilization and the rest is decided by nice value. 1510 * 1511 * The nice value of the process has a linear effect on the calculated 1512 * score. Negative nice values make it easier for a thread to be 1513 * considered interactive. 1514 */ 1515 score = imax(0, sched_interact_score(td) + td->td_proc->p_nice); 1516 if (score < sched_interact) { 1517 pri = PRI_MIN_INTERACT; 1518 pri += ((PRI_MAX_INTERACT - PRI_MIN_INTERACT + 1) / 1519 sched_interact) * score; 1520 KASSERT(pri >= PRI_MIN_INTERACT && pri <= PRI_MAX_INTERACT, 1521 ("sched_priority: invalid interactive priority %d score %d", 1522 pri, score)); 1523 } else { 1524 pri = SCHED_PRI_MIN; 1525 if (td->td_sched->ts_ticks) 1526 pri += min(SCHED_PRI_TICKS(td->td_sched), 1527 SCHED_PRI_RANGE - 1); 1528 pri += SCHED_PRI_NICE(td->td_proc->p_nice); 1529 KASSERT(pri >= PRI_MIN_BATCH && pri <= PRI_MAX_BATCH, 1530 ("sched_priority: invalid priority %d: nice %d, " 1531 "ticks %d ftick %d ltick %d tick pri %d", 1532 pri, td->td_proc->p_nice, td->td_sched->ts_ticks, 1533 td->td_sched->ts_ftick, td->td_sched->ts_ltick, 1534 SCHED_PRI_TICKS(td->td_sched))); 1535 } 1536 sched_user_prio(td, pri); 1537 1538 return; 1539 } 1540 1541 /* 1542 * This routine enforces a maximum limit on the amount of scheduling history 1543 * kept. It is called after either the slptime or runtime is adjusted. This 1544 * function is ugly due to integer math. 1545 */ 1546 static void 1547 sched_interact_update(struct thread *td) 1548 { 1549 struct td_sched *ts; 1550 u_int sum; 1551 1552 ts = td->td_sched; 1553 sum = ts->ts_runtime + ts->ts_slptime; 1554 if (sum < SCHED_SLP_RUN_MAX) 1555 return; 1556 /* 1557 * This only happens from two places: 1558 * 1) We have added an unusual amount of run time from fork_exit. 1559 * 2) We have added an unusual amount of sleep time from sched_sleep(). 1560 */ 1561 if (sum > SCHED_SLP_RUN_MAX * 2) { 1562 if (ts->ts_runtime > ts->ts_slptime) { 1563 ts->ts_runtime = SCHED_SLP_RUN_MAX; 1564 ts->ts_slptime = 1; 1565 } else { 1566 ts->ts_slptime = SCHED_SLP_RUN_MAX; 1567 ts->ts_runtime = 1; 1568 } 1569 return; 1570 } 1571 /* 1572 * If we have exceeded by more than 1/5th then the algorithm below 1573 * will not bring us back into range. Dividing by two here forces 1574 * us into the range of [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX] 1575 */ 1576 if (sum > (SCHED_SLP_RUN_MAX / 5) * 6) { 1577 ts->ts_runtime /= 2; 1578 ts->ts_slptime /= 2; 1579 return; 1580 } 1581 ts->ts_runtime = (ts->ts_runtime / 5) * 4; 1582 ts->ts_slptime = (ts->ts_slptime / 5) * 4; 1583 } 1584 1585 /* 1586 * Scale back the interactivity history when a child thread is created. The 1587 * history is inherited from the parent but the thread may behave totally 1588 * differently. For example, a shell spawning a compiler process. We want 1589 * to learn that the compiler is behaving badly very quickly. 1590 */ 1591 static void 1592 sched_interact_fork(struct thread *td) 1593 { 1594 int ratio; 1595 int sum; 1596 1597 sum = td->td_sched->ts_runtime + td->td_sched->ts_slptime; 1598 if (sum > SCHED_SLP_RUN_FORK) { 1599 ratio = sum / SCHED_SLP_RUN_FORK; 1600 td->td_sched->ts_runtime /= ratio; 1601 td->td_sched->ts_slptime /= ratio; 1602 } 1603 } 1604 1605 /* 1606 * Called from proc0_init() to setup the scheduler fields. 1607 */ 1608 void 1609 schedinit(void) 1610 { 1611 1612 /* 1613 * Set up the scheduler specific parts of proc0. 1614 */ 1615 proc0.p_sched = NULL; /* XXX */ 1616 thread0.td_sched = &td_sched0; 1617 td_sched0.ts_ltick = ticks; 1618 td_sched0.ts_ftick = ticks; 1619 td_sched0.ts_slice = 0; 1620 } 1621 1622 /* 1623 * This is only somewhat accurate since given many processes of the same 1624 * priority they will switch when their slices run out, which will be 1625 * at most sched_slice stathz ticks. 1626 */ 1627 int 1628 sched_rr_interval(void) 1629 { 1630 1631 /* Convert sched_slice from stathz to hz. */ 1632 return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz)); 1633 } 1634 1635 /* 1636 * Update the percent cpu tracking information when it is requested or 1637 * the total history exceeds the maximum. We keep a sliding history of 1638 * tick counts that slowly decays. This is less precise than the 4BSD 1639 * mechanism since it happens with less regular and frequent events. 1640 */ 1641 static void 1642 sched_pctcpu_update(struct td_sched *ts, int run) 1643 { 1644 int t = ticks; 1645 1646 if (t - ts->ts_ltick >= SCHED_TICK_TARG) { 1647 ts->ts_ticks = 0; 1648 ts->ts_ftick = t - SCHED_TICK_TARG; 1649 } else if (t - ts->ts_ftick >= SCHED_TICK_MAX) { 1650 ts->ts_ticks = (ts->ts_ticks / (ts->ts_ltick - ts->ts_ftick)) * 1651 (ts->ts_ltick - (t - SCHED_TICK_TARG)); 1652 ts->ts_ftick = t - SCHED_TICK_TARG; 1653 } 1654 if (run) 1655 ts->ts_ticks += (t - ts->ts_ltick) << SCHED_TICK_SHIFT; 1656 ts->ts_ltick = t; 1657 } 1658 1659 /* 1660 * Adjust the priority of a thread. Move it to the appropriate run-queue 1661 * if necessary. This is the back-end for several priority related 1662 * functions. 1663 */ 1664 static void 1665 sched_thread_priority(struct thread *td, u_char prio) 1666 { 1667 struct td_sched *ts; 1668 struct tdq *tdq; 1669 int oldpri; 1670 1671 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "prio", 1672 "prio:%d", td->td_priority, "new prio:%d", prio, 1673 KTR_ATTR_LINKED, sched_tdname(curthread)); 1674 SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio); 1675 if (td != curthread && prio < td->td_priority) { 1676 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread), 1677 "lend prio", "prio:%d", td->td_priority, "new prio:%d", 1678 prio, KTR_ATTR_LINKED, sched_tdname(td)); 1679 SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio, 1680 curthread); 1681 } 1682 ts = td->td_sched; 1683 THREAD_LOCK_ASSERT(td, MA_OWNED); 1684 if (td->td_priority == prio) 1685 return; 1686 /* 1687 * If the priority has been elevated due to priority 1688 * propagation, we may have to move ourselves to a new 1689 * queue. This could be optimized to not re-add in some 1690 * cases. 1691 */ 1692 if (TD_ON_RUNQ(td) && prio < td->td_priority) { 1693 sched_rem(td); 1694 td->td_priority = prio; 1695 sched_add(td, SRQ_BORROWING); 1696 return; 1697 } 1698 /* 1699 * If the thread is currently running we may have to adjust the lowpri 1700 * information so other cpus are aware of our current priority. 1701 */ 1702 if (TD_IS_RUNNING(td)) { 1703 tdq = TDQ_CPU(ts->ts_cpu); 1704 oldpri = td->td_priority; 1705 td->td_priority = prio; 1706 if (prio < tdq->tdq_lowpri) 1707 tdq->tdq_lowpri = prio; 1708 else if (tdq->tdq_lowpri == oldpri) 1709 tdq_setlowpri(tdq, td); 1710 return; 1711 } 1712 td->td_priority = prio; 1713 } 1714 1715 /* 1716 * Update a thread's priority when it is lent another thread's 1717 * priority. 1718 */ 1719 void 1720 sched_lend_prio(struct thread *td, u_char prio) 1721 { 1722 1723 td->td_flags |= TDF_BORROWING; 1724 sched_thread_priority(td, prio); 1725 } 1726 1727 /* 1728 * Restore a thread's priority when priority propagation is 1729 * over. The prio argument is the minimum priority the thread 1730 * needs to have to satisfy other possible priority lending 1731 * requests. If the thread's regular priority is less 1732 * important than prio, the thread will keep a priority boost 1733 * of prio. 1734 */ 1735 void 1736 sched_unlend_prio(struct thread *td, u_char prio) 1737 { 1738 u_char base_pri; 1739 1740 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 1741 td->td_base_pri <= PRI_MAX_TIMESHARE) 1742 base_pri = td->td_user_pri; 1743 else 1744 base_pri = td->td_base_pri; 1745 if (prio >= base_pri) { 1746 td->td_flags &= ~TDF_BORROWING; 1747 sched_thread_priority(td, base_pri); 1748 } else 1749 sched_lend_prio(td, prio); 1750 } 1751 1752 /* 1753 * Standard entry for setting the priority to an absolute value. 1754 */ 1755 void 1756 sched_prio(struct thread *td, u_char prio) 1757 { 1758 u_char oldprio; 1759 1760 /* First, update the base priority. */ 1761 td->td_base_pri = prio; 1762 1763 /* 1764 * If the thread is borrowing another thread's priority, don't 1765 * ever lower the priority. 1766 */ 1767 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 1768 return; 1769 1770 /* Change the real priority. */ 1771 oldprio = td->td_priority; 1772 sched_thread_priority(td, prio); 1773 1774 /* 1775 * If the thread is on a turnstile, then let the turnstile update 1776 * its state. 1777 */ 1778 if (TD_ON_LOCK(td) && oldprio != prio) 1779 turnstile_adjust(td, oldprio); 1780 } 1781 1782 /* 1783 * Set the base user priority, does not effect current running priority. 1784 */ 1785 void 1786 sched_user_prio(struct thread *td, u_char prio) 1787 { 1788 1789 td->td_base_user_pri = prio; 1790 if (td->td_lend_user_pri <= prio) 1791 return; 1792 td->td_user_pri = prio; 1793 } 1794 1795 void 1796 sched_lend_user_prio(struct thread *td, u_char prio) 1797 { 1798 1799 THREAD_LOCK_ASSERT(td, MA_OWNED); 1800 td->td_lend_user_pri = prio; 1801 td->td_user_pri = min(prio, td->td_base_user_pri); 1802 if (td->td_priority > td->td_user_pri) 1803 sched_prio(td, td->td_user_pri); 1804 else if (td->td_priority != td->td_user_pri) 1805 td->td_flags |= TDF_NEEDRESCHED; 1806 } 1807 1808 /* 1809 * Handle migration from sched_switch(). This happens only for 1810 * cpu binding. 1811 */ 1812 static struct mtx * 1813 sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags) 1814 { 1815 struct tdq *tdn; 1816 1817 tdn = TDQ_CPU(td->td_sched->ts_cpu); 1818 #ifdef SMP 1819 tdq_load_rem(tdq, td); 1820 /* 1821 * Do the lock dance required to avoid LOR. We grab an extra 1822 * spinlock nesting to prevent preemption while we're 1823 * not holding either run-queue lock. 1824 */ 1825 spinlock_enter(); 1826 thread_lock_block(td); /* This releases the lock on tdq. */ 1827 1828 /* 1829 * Acquire both run-queue locks before placing the thread on the new 1830 * run-queue to avoid deadlocks created by placing a thread with a 1831 * blocked lock on the run-queue of a remote processor. The deadlock 1832 * occurs when a third processor attempts to lock the two queues in 1833 * question while the target processor is spinning with its own 1834 * run-queue lock held while waiting for the blocked lock to clear. 1835 */ 1836 tdq_lock_pair(tdn, tdq); 1837 tdq_add(tdn, td, flags); 1838 tdq_notify(tdn, td); 1839 TDQ_UNLOCK(tdn); 1840 spinlock_exit(); 1841 #endif 1842 return (TDQ_LOCKPTR(tdn)); 1843 } 1844 1845 /* 1846 * Variadic version of thread_lock_unblock() that does not assume td_lock 1847 * is blocked. 1848 */ 1849 static inline void 1850 thread_unblock_switch(struct thread *td, struct mtx *mtx) 1851 { 1852 atomic_store_rel_ptr((volatile uintptr_t *)&td->td_lock, 1853 (uintptr_t)mtx); 1854 } 1855 1856 /* 1857 * Switch threads. This function has to handle threads coming in while 1858 * blocked for some reason, running, or idle. It also must deal with 1859 * migrating a thread from one queue to another as running threads may 1860 * be assigned elsewhere via binding. 1861 */ 1862 void 1863 sched_switch(struct thread *td, struct thread *newtd, int flags) 1864 { 1865 struct tdq *tdq; 1866 struct td_sched *ts; 1867 struct mtx *mtx; 1868 int srqflag; 1869 int cpuid, preempted; 1870 1871 THREAD_LOCK_ASSERT(td, MA_OWNED); 1872 KASSERT(newtd == NULL, ("sched_switch: Unsupported newtd argument")); 1873 1874 cpuid = PCPU_GET(cpuid); 1875 tdq = TDQ_CPU(cpuid); 1876 ts = td->td_sched; 1877 mtx = td->td_lock; 1878 sched_pctcpu_update(ts, 1); 1879 ts->ts_rltick = ticks; 1880 td->td_lastcpu = td->td_oncpu; 1881 td->td_oncpu = NOCPU; 1882 preempted = !((td->td_flags & TDF_SLICEEND) || 1883 (flags & SWT_RELINQUISH)); 1884 td->td_flags &= ~(TDF_NEEDRESCHED | TDF_SLICEEND); 1885 td->td_owepreempt = 0; 1886 if (!TD_IS_IDLETHREAD(td)) 1887 tdq->tdq_switchcnt++; 1888 /* 1889 * The lock pointer in an idle thread should never change. Reset it 1890 * to CAN_RUN as well. 1891 */ 1892 if (TD_IS_IDLETHREAD(td)) { 1893 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1894 TD_SET_CAN_RUN(td); 1895 } else if (TD_IS_RUNNING(td)) { 1896 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1897 srqflag = preempted ? 1898 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 1899 SRQ_OURSELF|SRQ_YIELDING; 1900 #ifdef SMP 1901 if (THREAD_CAN_MIGRATE(td) && !THREAD_CAN_SCHED(td, ts->ts_cpu)) 1902 ts->ts_cpu = sched_pickcpu(td, 0); 1903 #endif 1904 if (ts->ts_cpu == cpuid) 1905 tdq_runq_add(tdq, td, srqflag); 1906 else { 1907 KASSERT(THREAD_CAN_MIGRATE(td) || 1908 (ts->ts_flags & TSF_BOUND) != 0, 1909 ("Thread %p shouldn't migrate", td)); 1910 mtx = sched_switch_migrate(tdq, td, srqflag); 1911 } 1912 } else { 1913 /* This thread must be going to sleep. */ 1914 TDQ_LOCK(tdq); 1915 mtx = thread_lock_block(td); 1916 tdq_load_rem(tdq, td); 1917 } 1918 /* 1919 * We enter here with the thread blocked and assigned to the 1920 * appropriate cpu run-queue or sleep-queue and with the current 1921 * thread-queue locked. 1922 */ 1923 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 1924 newtd = choosethread(); 1925 /* 1926 * Call the MD code to switch contexts if necessary. 1927 */ 1928 if (td != newtd) { 1929 #ifdef HWPMC_HOOKS 1930 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1931 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 1932 #endif 1933 SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc); 1934 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 1935 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 1936 sched_pctcpu_update(newtd->td_sched, 0); 1937 1938 #ifdef KDTRACE_HOOKS 1939 /* 1940 * If DTrace has set the active vtime enum to anything 1941 * other than INACTIVE (0), then it should have set the 1942 * function to call. 1943 */ 1944 if (dtrace_vtime_active) 1945 (*dtrace_vtime_switch_func)(newtd); 1946 #endif 1947 1948 cpu_switch(td, newtd, mtx); 1949 /* 1950 * We may return from cpu_switch on a different cpu. However, 1951 * we always return with td_lock pointing to the current cpu's 1952 * run queue lock. 1953 */ 1954 cpuid = PCPU_GET(cpuid); 1955 tdq = TDQ_CPU(cpuid); 1956 lock_profile_obtain_lock_success( 1957 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 1958 1959 SDT_PROBE0(sched, , , on__cpu); 1960 #ifdef HWPMC_HOOKS 1961 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1962 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 1963 #endif 1964 } else { 1965 thread_unblock_switch(td, mtx); 1966 SDT_PROBE0(sched, , , remain__cpu); 1967 } 1968 /* 1969 * Assert that all went well and return. 1970 */ 1971 TDQ_LOCK_ASSERT(tdq, MA_OWNED|MA_NOTRECURSED); 1972 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1973 td->td_oncpu = cpuid; 1974 } 1975 1976 /* 1977 * Adjust thread priorities as a result of a nice request. 1978 */ 1979 void 1980 sched_nice(struct proc *p, int nice) 1981 { 1982 struct thread *td; 1983 1984 PROC_LOCK_ASSERT(p, MA_OWNED); 1985 1986 p->p_nice = nice; 1987 FOREACH_THREAD_IN_PROC(p, td) { 1988 thread_lock(td); 1989 sched_priority(td); 1990 sched_prio(td, td->td_base_user_pri); 1991 thread_unlock(td); 1992 } 1993 } 1994 1995 /* 1996 * Record the sleep time for the interactivity scorer. 1997 */ 1998 void 1999 sched_sleep(struct thread *td, int prio) 2000 { 2001 2002 THREAD_LOCK_ASSERT(td, MA_OWNED); 2003 2004 td->td_slptick = ticks; 2005 if (TD_IS_SUSPENDED(td) || prio >= PSOCK) 2006 td->td_flags |= TDF_CANSWAP; 2007 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 2008 return; 2009 if (static_boost == 1 && prio) 2010 sched_prio(td, prio); 2011 else if (static_boost && td->td_priority > static_boost) 2012 sched_prio(td, static_boost); 2013 } 2014 2015 /* 2016 * Schedule a thread to resume execution and record how long it voluntarily 2017 * slept. We also update the pctcpu, interactivity, and priority. 2018 */ 2019 void 2020 sched_wakeup(struct thread *td) 2021 { 2022 struct td_sched *ts; 2023 int slptick; 2024 2025 THREAD_LOCK_ASSERT(td, MA_OWNED); 2026 ts = td->td_sched; 2027 td->td_flags &= ~TDF_CANSWAP; 2028 /* 2029 * If we slept for more than a tick update our interactivity and 2030 * priority. 2031 */ 2032 slptick = td->td_slptick; 2033 td->td_slptick = 0; 2034 if (slptick && slptick != ticks) { 2035 ts->ts_slptime += (ticks - slptick) << SCHED_TICK_SHIFT; 2036 sched_interact_update(td); 2037 sched_pctcpu_update(ts, 0); 2038 } 2039 /* 2040 * Reset the slice value since we slept and advanced the round-robin. 2041 */ 2042 ts->ts_slice = 0; 2043 sched_add(td, SRQ_BORING); 2044 } 2045 2046 /* 2047 * Penalize the parent for creating a new child and initialize the child's 2048 * priority. 2049 */ 2050 void 2051 sched_fork(struct thread *td, struct thread *child) 2052 { 2053 THREAD_LOCK_ASSERT(td, MA_OWNED); 2054 sched_pctcpu_update(td->td_sched, 1); 2055 sched_fork_thread(td, child); 2056 /* 2057 * Penalize the parent and child for forking. 2058 */ 2059 sched_interact_fork(child); 2060 sched_priority(child); 2061 td->td_sched->ts_runtime += tickincr; 2062 sched_interact_update(td); 2063 sched_priority(td); 2064 } 2065 2066 /* 2067 * Fork a new thread, may be within the same process. 2068 */ 2069 void 2070 sched_fork_thread(struct thread *td, struct thread *child) 2071 { 2072 struct td_sched *ts; 2073 struct td_sched *ts2; 2074 struct tdq *tdq; 2075 2076 tdq = TDQ_SELF(); 2077 THREAD_LOCK_ASSERT(td, MA_OWNED); 2078 /* 2079 * Initialize child. 2080 */ 2081 ts = td->td_sched; 2082 ts2 = child->td_sched; 2083 child->td_lock = TDQ_LOCKPTR(tdq); 2084 child->td_cpuset = cpuset_ref(td->td_cpuset); 2085 ts2->ts_cpu = ts->ts_cpu; 2086 ts2->ts_flags = 0; 2087 /* 2088 * Grab our parents cpu estimation information. 2089 */ 2090 ts2->ts_ticks = ts->ts_ticks; 2091 ts2->ts_ltick = ts->ts_ltick; 2092 ts2->ts_ftick = ts->ts_ftick; 2093 /* 2094 * Do not inherit any borrowed priority from the parent. 2095 */ 2096 child->td_priority = child->td_base_pri; 2097 /* 2098 * And update interactivity score. 2099 */ 2100 ts2->ts_slptime = ts->ts_slptime; 2101 ts2->ts_runtime = ts->ts_runtime; 2102 /* Attempt to quickly learn interactivity. */ 2103 ts2->ts_slice = tdq_slice(tdq) - sched_slice_min; 2104 #ifdef KTR 2105 bzero(ts2->ts_name, sizeof(ts2->ts_name)); 2106 #endif 2107 } 2108 2109 /* 2110 * Adjust the priority class of a thread. 2111 */ 2112 void 2113 sched_class(struct thread *td, int class) 2114 { 2115 2116 THREAD_LOCK_ASSERT(td, MA_OWNED); 2117 if (td->td_pri_class == class) 2118 return; 2119 td->td_pri_class = class; 2120 } 2121 2122 /* 2123 * Return some of the child's priority and interactivity to the parent. 2124 */ 2125 void 2126 sched_exit(struct proc *p, struct thread *child) 2127 { 2128 struct thread *td; 2129 2130 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "proc exit", 2131 "prio:%d", child->td_priority); 2132 PROC_LOCK_ASSERT(p, MA_OWNED); 2133 td = FIRST_THREAD_IN_PROC(p); 2134 sched_exit_thread(td, child); 2135 } 2136 2137 /* 2138 * Penalize another thread for the time spent on this one. This helps to 2139 * worsen the priority and interactivity of processes which schedule batch 2140 * jobs such as make. This has little effect on the make process itself but 2141 * causes new processes spawned by it to receive worse scores immediately. 2142 */ 2143 void 2144 sched_exit_thread(struct thread *td, struct thread *child) 2145 { 2146 2147 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "thread exit", 2148 "prio:%d", child->td_priority); 2149 /* 2150 * Give the child's runtime to the parent without returning the 2151 * sleep time as a penalty to the parent. This causes shells that 2152 * launch expensive things to mark their children as expensive. 2153 */ 2154 thread_lock(td); 2155 td->td_sched->ts_runtime += child->td_sched->ts_runtime; 2156 sched_interact_update(td); 2157 sched_priority(td); 2158 thread_unlock(td); 2159 } 2160 2161 void 2162 sched_preempt(struct thread *td) 2163 { 2164 struct tdq *tdq; 2165 2166 SDT_PROBE2(sched, , , surrender, td, td->td_proc); 2167 2168 thread_lock(td); 2169 tdq = TDQ_SELF(); 2170 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2171 tdq->tdq_ipipending = 0; 2172 if (td->td_priority > tdq->tdq_lowpri) { 2173 int flags; 2174 2175 flags = SW_INVOL | SW_PREEMPT; 2176 if (td->td_critnest > 1) 2177 td->td_owepreempt = 1; 2178 else if (TD_IS_IDLETHREAD(td)) 2179 mi_switch(flags | SWT_REMOTEWAKEIDLE, NULL); 2180 else 2181 mi_switch(flags | SWT_REMOTEPREEMPT, NULL); 2182 } 2183 thread_unlock(td); 2184 } 2185 2186 /* 2187 * Fix priorities on return to user-space. Priorities may be elevated due 2188 * to static priorities in msleep() or similar. 2189 */ 2190 void 2191 sched_userret(struct thread *td) 2192 { 2193 /* 2194 * XXX we cheat slightly on the locking here to avoid locking in 2195 * the usual case. Setting td_priority here is essentially an 2196 * incomplete workaround for not setting it properly elsewhere. 2197 * Now that some interrupt handlers are threads, not setting it 2198 * properly elsewhere can clobber it in the window between setting 2199 * it here and returning to user mode, so don't waste time setting 2200 * it perfectly here. 2201 */ 2202 KASSERT((td->td_flags & TDF_BORROWING) == 0, 2203 ("thread with borrowed priority returning to userland")); 2204 if (td->td_priority != td->td_user_pri) { 2205 thread_lock(td); 2206 td->td_priority = td->td_user_pri; 2207 td->td_base_pri = td->td_user_pri; 2208 tdq_setlowpri(TDQ_SELF(), td); 2209 thread_unlock(td); 2210 } 2211 } 2212 2213 /* 2214 * Handle a stathz tick. This is really only relevant for timeshare 2215 * threads. 2216 */ 2217 void 2218 sched_clock(struct thread *td) 2219 { 2220 struct tdq *tdq; 2221 struct td_sched *ts; 2222 2223 THREAD_LOCK_ASSERT(td, MA_OWNED); 2224 tdq = TDQ_SELF(); 2225 #ifdef SMP 2226 /* 2227 * We run the long term load balancer infrequently on the first cpu. 2228 */ 2229 if (balance_tdq == tdq) { 2230 if (balance_ticks && --balance_ticks == 0) 2231 sched_balance(); 2232 } 2233 #endif 2234 /* 2235 * Save the old switch count so we have a record of the last ticks 2236 * activity. Initialize the new switch count based on our load. 2237 * If there is some activity seed it to reflect that. 2238 */ 2239 tdq->tdq_oldswitchcnt = tdq->tdq_switchcnt; 2240 tdq->tdq_switchcnt = tdq->tdq_load; 2241 /* 2242 * Advance the insert index once for each tick to ensure that all 2243 * threads get a chance to run. 2244 */ 2245 if (tdq->tdq_idx == tdq->tdq_ridx) { 2246 tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS; 2247 if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx])) 2248 tdq->tdq_ridx = tdq->tdq_idx; 2249 } 2250 ts = td->td_sched; 2251 sched_pctcpu_update(ts, 1); 2252 if (td->td_pri_class & PRI_FIFO_BIT) 2253 return; 2254 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) { 2255 /* 2256 * We used a tick; charge it to the thread so 2257 * that we can compute our interactivity. 2258 */ 2259 td->td_sched->ts_runtime += tickincr; 2260 sched_interact_update(td); 2261 sched_priority(td); 2262 } 2263 2264 /* 2265 * Force a context switch if the current thread has used up a full 2266 * time slice (default is 100ms). 2267 */ 2268 if (!TD_IS_IDLETHREAD(td) && ++ts->ts_slice >= tdq_slice(tdq)) { 2269 ts->ts_slice = 0; 2270 td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND; 2271 } 2272 } 2273 2274 /* 2275 * Called once per hz tick. 2276 */ 2277 void 2278 sched_tick(int cnt) 2279 { 2280 2281 } 2282 2283 /* 2284 * Return whether the current CPU has runnable tasks. Used for in-kernel 2285 * cooperative idle threads. 2286 */ 2287 int 2288 sched_runnable(void) 2289 { 2290 struct tdq *tdq; 2291 int load; 2292 2293 load = 1; 2294 2295 tdq = TDQ_SELF(); 2296 if ((curthread->td_flags & TDF_IDLETD) != 0) { 2297 if (tdq->tdq_load > 0) 2298 goto out; 2299 } else 2300 if (tdq->tdq_load - 1 > 0) 2301 goto out; 2302 load = 0; 2303 out: 2304 return (load); 2305 } 2306 2307 /* 2308 * Choose the highest priority thread to run. The thread is removed from 2309 * the run-queue while running however the load remains. For SMP we set 2310 * the tdq in the global idle bitmask if it idles here. 2311 */ 2312 struct thread * 2313 sched_choose(void) 2314 { 2315 struct thread *td; 2316 struct tdq *tdq; 2317 2318 tdq = TDQ_SELF(); 2319 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2320 td = tdq_choose(tdq); 2321 if (td) { 2322 tdq_runq_rem(tdq, td); 2323 tdq->tdq_lowpri = td->td_priority; 2324 return (td); 2325 } 2326 tdq->tdq_lowpri = PRI_MAX_IDLE; 2327 return (PCPU_GET(idlethread)); 2328 } 2329 2330 /* 2331 * Set owepreempt if necessary. Preemption never happens directly in ULE, 2332 * we always request it once we exit a critical section. 2333 */ 2334 static inline void 2335 sched_setpreempt(struct thread *td) 2336 { 2337 struct thread *ctd; 2338 int cpri; 2339 int pri; 2340 2341 THREAD_LOCK_ASSERT(curthread, MA_OWNED); 2342 2343 ctd = curthread; 2344 pri = td->td_priority; 2345 cpri = ctd->td_priority; 2346 if (pri < cpri) 2347 ctd->td_flags |= TDF_NEEDRESCHED; 2348 if (panicstr != NULL || pri >= cpri || cold || TD_IS_INHIBITED(ctd)) 2349 return; 2350 if (!sched_shouldpreempt(pri, cpri, 0)) 2351 return; 2352 ctd->td_owepreempt = 1; 2353 } 2354 2355 /* 2356 * Add a thread to a thread queue. Select the appropriate runq and add the 2357 * thread to it. This is the internal function called when the tdq is 2358 * predetermined. 2359 */ 2360 void 2361 tdq_add(struct tdq *tdq, struct thread *td, int flags) 2362 { 2363 2364 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2365 KASSERT((td->td_inhibitors == 0), 2366 ("sched_add: trying to run inhibited thread")); 2367 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 2368 ("sched_add: bad thread state")); 2369 KASSERT(td->td_flags & TDF_INMEM, 2370 ("sched_add: thread swapped out")); 2371 2372 if (td->td_priority < tdq->tdq_lowpri) 2373 tdq->tdq_lowpri = td->td_priority; 2374 tdq_runq_add(tdq, td, flags); 2375 tdq_load_add(tdq, td); 2376 } 2377 2378 /* 2379 * Select the target thread queue and add a thread to it. Request 2380 * preemption or IPI a remote processor if required. 2381 */ 2382 void 2383 sched_add(struct thread *td, int flags) 2384 { 2385 struct tdq *tdq; 2386 #ifdef SMP 2387 int cpu; 2388 #endif 2389 2390 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 2391 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 2392 sched_tdname(curthread)); 2393 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 2394 KTR_ATTR_LINKED, sched_tdname(td)); 2395 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 2396 flags & SRQ_PREEMPTED); 2397 THREAD_LOCK_ASSERT(td, MA_OWNED); 2398 /* 2399 * Recalculate the priority before we select the target cpu or 2400 * run-queue. 2401 */ 2402 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 2403 sched_priority(td); 2404 #ifdef SMP 2405 /* 2406 * Pick the destination cpu and if it isn't ours transfer to the 2407 * target cpu. 2408 */ 2409 cpu = sched_pickcpu(td, flags); 2410 tdq = sched_setcpu(td, cpu, flags); 2411 tdq_add(tdq, td, flags); 2412 if (cpu != PCPU_GET(cpuid)) { 2413 tdq_notify(tdq, td); 2414 return; 2415 } 2416 #else 2417 tdq = TDQ_SELF(); 2418 TDQ_LOCK(tdq); 2419 /* 2420 * Now that the thread is moving to the run-queue, set the lock 2421 * to the scheduler's lock. 2422 */ 2423 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 2424 tdq_add(tdq, td, flags); 2425 #endif 2426 if (!(flags & SRQ_YIELDING)) 2427 sched_setpreempt(td); 2428 } 2429 2430 /* 2431 * Remove a thread from a run-queue without running it. This is used 2432 * when we're stealing a thread from a remote queue. Otherwise all threads 2433 * exit by calling sched_exit_thread() and sched_throw() themselves. 2434 */ 2435 void 2436 sched_rem(struct thread *td) 2437 { 2438 struct tdq *tdq; 2439 2440 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "runq rem", 2441 "prio:%d", td->td_priority); 2442 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL); 2443 tdq = TDQ_CPU(td->td_sched->ts_cpu); 2444 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2445 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2446 KASSERT(TD_ON_RUNQ(td), 2447 ("sched_rem: thread not on run queue")); 2448 tdq_runq_rem(tdq, td); 2449 tdq_load_rem(tdq, td); 2450 TD_SET_CAN_RUN(td); 2451 if (td->td_priority == tdq->tdq_lowpri) 2452 tdq_setlowpri(tdq, NULL); 2453 } 2454 2455 /* 2456 * Fetch cpu utilization information. Updates on demand. 2457 */ 2458 fixpt_t 2459 sched_pctcpu(struct thread *td) 2460 { 2461 fixpt_t pctcpu; 2462 struct td_sched *ts; 2463 2464 pctcpu = 0; 2465 ts = td->td_sched; 2466 if (ts == NULL) 2467 return (0); 2468 2469 THREAD_LOCK_ASSERT(td, MA_OWNED); 2470 sched_pctcpu_update(ts, TD_IS_RUNNING(td)); 2471 if (ts->ts_ticks) { 2472 int rtick; 2473 2474 /* How many rtick per second ? */ 2475 rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz); 2476 pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT; 2477 } 2478 2479 return (pctcpu); 2480 } 2481 2482 /* 2483 * Enforce affinity settings for a thread. Called after adjustments to 2484 * cpumask. 2485 */ 2486 void 2487 sched_affinity(struct thread *td) 2488 { 2489 #ifdef SMP 2490 struct td_sched *ts; 2491 2492 THREAD_LOCK_ASSERT(td, MA_OWNED); 2493 ts = td->td_sched; 2494 if (THREAD_CAN_SCHED(td, ts->ts_cpu)) 2495 return; 2496 if (TD_ON_RUNQ(td)) { 2497 sched_rem(td); 2498 sched_add(td, SRQ_BORING); 2499 return; 2500 } 2501 if (!TD_IS_RUNNING(td)) 2502 return; 2503 /* 2504 * Force a switch before returning to userspace. If the 2505 * target thread is not running locally send an ipi to force 2506 * the issue. 2507 */ 2508 td->td_flags |= TDF_NEEDRESCHED; 2509 if (td != curthread) 2510 ipi_cpu(ts->ts_cpu, IPI_PREEMPT); 2511 #endif 2512 } 2513 2514 /* 2515 * Bind a thread to a target cpu. 2516 */ 2517 void 2518 sched_bind(struct thread *td, int cpu) 2519 { 2520 struct td_sched *ts; 2521 2522 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 2523 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 2524 ts = td->td_sched; 2525 if (ts->ts_flags & TSF_BOUND) 2526 sched_unbind(td); 2527 KASSERT(THREAD_CAN_MIGRATE(td), ("%p must be migratable", td)); 2528 ts->ts_flags |= TSF_BOUND; 2529 sched_pin(); 2530 if (PCPU_GET(cpuid) == cpu) 2531 return; 2532 ts->ts_cpu = cpu; 2533 /* When we return from mi_switch we'll be on the correct cpu. */ 2534 mi_switch(SW_VOL, NULL); 2535 } 2536 2537 /* 2538 * Release a bound thread. 2539 */ 2540 void 2541 sched_unbind(struct thread *td) 2542 { 2543 struct td_sched *ts; 2544 2545 THREAD_LOCK_ASSERT(td, MA_OWNED); 2546 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 2547 ts = td->td_sched; 2548 if ((ts->ts_flags & TSF_BOUND) == 0) 2549 return; 2550 ts->ts_flags &= ~TSF_BOUND; 2551 sched_unpin(); 2552 } 2553 2554 int 2555 sched_is_bound(struct thread *td) 2556 { 2557 THREAD_LOCK_ASSERT(td, MA_OWNED); 2558 return (td->td_sched->ts_flags & TSF_BOUND); 2559 } 2560 2561 /* 2562 * Basic yield call. 2563 */ 2564 void 2565 sched_relinquish(struct thread *td) 2566 { 2567 thread_lock(td); 2568 mi_switch(SW_VOL | SWT_RELINQUISH, NULL); 2569 thread_unlock(td); 2570 } 2571 2572 /* 2573 * Return the total system load. 2574 */ 2575 int 2576 sched_load(void) 2577 { 2578 #ifdef SMP 2579 int total; 2580 int i; 2581 2582 total = 0; 2583 CPU_FOREACH(i) 2584 total += TDQ_CPU(i)->tdq_sysload; 2585 return (total); 2586 #else 2587 return (TDQ_SELF()->tdq_sysload); 2588 #endif 2589 } 2590 2591 int 2592 sched_sizeof_proc(void) 2593 { 2594 return (sizeof(struct proc)); 2595 } 2596 2597 int 2598 sched_sizeof_thread(void) 2599 { 2600 return (sizeof(struct thread) + sizeof(struct td_sched)); 2601 } 2602 2603 #ifdef SMP 2604 #define TDQ_IDLESPIN(tdq) \ 2605 ((tdq)->tdq_cg != NULL && ((tdq)->tdq_cg->cg_flags & CG_FLAG_THREAD) == 0) 2606 #else 2607 #define TDQ_IDLESPIN(tdq) 1 2608 #endif 2609 2610 /* 2611 * The actual idle process. 2612 */ 2613 void 2614 sched_idletd(void *dummy) 2615 { 2616 struct thread *td; 2617 struct tdq *tdq; 2618 int oldswitchcnt, switchcnt; 2619 int i; 2620 2621 mtx_assert(&Giant, MA_NOTOWNED); 2622 td = curthread; 2623 tdq = TDQ_SELF(); 2624 THREAD_NO_SLEEPING(); 2625 oldswitchcnt = -1; 2626 for (;;) { 2627 if (tdq->tdq_load) { 2628 thread_lock(td); 2629 mi_switch(SW_VOL | SWT_IDLE, NULL); 2630 thread_unlock(td); 2631 } 2632 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2633 #ifdef SMP 2634 if (switchcnt != oldswitchcnt) { 2635 oldswitchcnt = switchcnt; 2636 if (tdq_idled(tdq) == 0) 2637 continue; 2638 } 2639 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2640 #else 2641 oldswitchcnt = switchcnt; 2642 #endif 2643 /* 2644 * If we're switching very frequently, spin while checking 2645 * for load rather than entering a low power state that 2646 * may require an IPI. However, don't do any busy 2647 * loops while on SMT machines as this simply steals 2648 * cycles from cores doing useful work. 2649 */ 2650 if (TDQ_IDLESPIN(tdq) && switchcnt > sched_idlespinthresh) { 2651 for (i = 0; i < sched_idlespins; i++) { 2652 if (tdq->tdq_load) 2653 break; 2654 cpu_spinwait(); 2655 } 2656 } 2657 2658 /* If there was context switch during spin, restart it. */ 2659 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2660 if (tdq->tdq_load != 0 || switchcnt != oldswitchcnt) 2661 continue; 2662 2663 /* Run main MD idle handler. */ 2664 tdq->tdq_cpu_idle = 1; 2665 /* 2666 * Make sure that tdq_cpu_idle update is globally visible 2667 * before cpu_idle() read tdq_load. The order is important 2668 * to avoid race with tdq_notify. 2669 */ 2670 atomic_thread_fence_seq_cst(); 2671 cpu_idle(switchcnt * 4 > sched_idlespinthresh); 2672 tdq->tdq_cpu_idle = 0; 2673 2674 /* 2675 * Account thread-less hardware interrupts and 2676 * other wakeup reasons equal to context switches. 2677 */ 2678 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2679 if (switchcnt != oldswitchcnt) 2680 continue; 2681 tdq->tdq_switchcnt++; 2682 oldswitchcnt++; 2683 } 2684 } 2685 2686 /* 2687 * A CPU is entering for the first time or a thread is exiting. 2688 */ 2689 void 2690 sched_throw(struct thread *td) 2691 { 2692 struct thread *newtd; 2693 struct tdq *tdq; 2694 2695 tdq = TDQ_SELF(); 2696 if (td == NULL) { 2697 /* Correct spinlock nesting and acquire the correct lock. */ 2698 TDQ_LOCK(tdq); 2699 spinlock_exit(); 2700 PCPU_SET(switchtime, cpu_ticks()); 2701 PCPU_SET(switchticks, ticks); 2702 } else { 2703 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2704 tdq_load_rem(tdq, td); 2705 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 2706 } 2707 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 2708 newtd = choosethread(); 2709 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 2710 cpu_throw(td, newtd); /* doesn't return */ 2711 } 2712 2713 /* 2714 * This is called from fork_exit(). Just acquire the correct locks and 2715 * let fork do the rest of the work. 2716 */ 2717 void 2718 sched_fork_exit(struct thread *td) 2719 { 2720 struct tdq *tdq; 2721 int cpuid; 2722 2723 /* 2724 * Finish setting up thread glue so that it begins execution in a 2725 * non-nested critical section with the scheduler lock held. 2726 */ 2727 cpuid = PCPU_GET(cpuid); 2728 tdq = TDQ_CPU(cpuid); 2729 if (TD_IS_IDLETHREAD(td)) 2730 td->td_lock = TDQ_LOCKPTR(tdq); 2731 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2732 td->td_oncpu = cpuid; 2733 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 2734 lock_profile_obtain_lock_success( 2735 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 2736 } 2737 2738 /* 2739 * Create on first use to catch odd startup conditons. 2740 */ 2741 char * 2742 sched_tdname(struct thread *td) 2743 { 2744 #ifdef KTR 2745 struct td_sched *ts; 2746 2747 ts = td->td_sched; 2748 if (ts->ts_name[0] == '\0') 2749 snprintf(ts->ts_name, sizeof(ts->ts_name), 2750 "%s tid %d", td->td_name, td->td_tid); 2751 return (ts->ts_name); 2752 #else 2753 return (td->td_name); 2754 #endif 2755 } 2756 2757 #ifdef KTR 2758 void 2759 sched_clear_tdname(struct thread *td) 2760 { 2761 struct td_sched *ts; 2762 2763 ts = td->td_sched; 2764 ts->ts_name[0] = '\0'; 2765 } 2766 #endif 2767 2768 #ifdef SMP 2769 2770 /* 2771 * Build the CPU topology dump string. Is recursively called to collect 2772 * the topology tree. 2773 */ 2774 static int 2775 sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, struct cpu_group *cg, 2776 int indent) 2777 { 2778 char cpusetbuf[CPUSETBUFSIZ]; 2779 int i, first; 2780 2781 sbuf_printf(sb, "%*s<group level=\"%d\" cache-level=\"%d\">\n", indent, 2782 "", 1 + indent / 2, cg->cg_level); 2783 sbuf_printf(sb, "%*s <cpu count=\"%d\" mask=\"%s\">", indent, "", 2784 cg->cg_count, cpusetobj_strprint(cpusetbuf, &cg->cg_mask)); 2785 first = TRUE; 2786 for (i = 0; i < MAXCPU; i++) { 2787 if (CPU_ISSET(i, &cg->cg_mask)) { 2788 if (!first) 2789 sbuf_printf(sb, ", "); 2790 else 2791 first = FALSE; 2792 sbuf_printf(sb, "%d", i); 2793 } 2794 } 2795 sbuf_printf(sb, "</cpu>\n"); 2796 2797 if (cg->cg_flags != 0) { 2798 sbuf_printf(sb, "%*s <flags>", indent, ""); 2799 if ((cg->cg_flags & CG_FLAG_HTT) != 0) 2800 sbuf_printf(sb, "<flag name=\"HTT\">HTT group</flag>"); 2801 if ((cg->cg_flags & CG_FLAG_THREAD) != 0) 2802 sbuf_printf(sb, "<flag name=\"THREAD\">THREAD group</flag>"); 2803 if ((cg->cg_flags & CG_FLAG_SMT) != 0) 2804 sbuf_printf(sb, "<flag name=\"SMT\">SMT group</flag>"); 2805 sbuf_printf(sb, "</flags>\n"); 2806 } 2807 2808 if (cg->cg_children > 0) { 2809 sbuf_printf(sb, "%*s <children>\n", indent, ""); 2810 for (i = 0; i < cg->cg_children; i++) 2811 sysctl_kern_sched_topology_spec_internal(sb, 2812 &cg->cg_child[i], indent+2); 2813 sbuf_printf(sb, "%*s </children>\n", indent, ""); 2814 } 2815 sbuf_printf(sb, "%*s</group>\n", indent, ""); 2816 return (0); 2817 } 2818 2819 /* 2820 * Sysctl handler for retrieving topology dump. It's a wrapper for 2821 * the recursive sysctl_kern_smp_topology_spec_internal(). 2822 */ 2823 static int 2824 sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS) 2825 { 2826 struct sbuf *topo; 2827 int err; 2828 2829 KASSERT(cpu_top != NULL, ("cpu_top isn't initialized")); 2830 2831 topo = sbuf_new_for_sysctl(NULL, NULL, 512, req); 2832 if (topo == NULL) 2833 return (ENOMEM); 2834 2835 sbuf_printf(topo, "<groups>\n"); 2836 err = sysctl_kern_sched_topology_spec_internal(topo, cpu_top, 1); 2837 sbuf_printf(topo, "</groups>\n"); 2838 2839 if (err == 0) { 2840 err = sbuf_finish(topo); 2841 } 2842 sbuf_delete(topo); 2843 return (err); 2844 } 2845 2846 #endif 2847 2848 static int 2849 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 2850 { 2851 int error, new_val, period; 2852 2853 period = 1000000 / realstathz; 2854 new_val = period * sched_slice; 2855 error = sysctl_handle_int(oidp, &new_val, 0, req); 2856 if (error != 0 || req->newptr == NULL) 2857 return (error); 2858 if (new_val <= 0) 2859 return (EINVAL); 2860 sched_slice = imax(1, (new_val + period / 2) / period); 2861 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 2862 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 2863 realstathz); 2864 return (0); 2865 } 2866 2867 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0, "Scheduler"); 2868 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0, 2869 "Scheduler name"); 2870 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW, 2871 NULL, 0, sysctl_kern_quantum, "I", 2872 "Quantum for timeshare threads in microseconds"); 2873 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, 2874 "Quantum for timeshare threads in stathz ticks"); 2875 SYSCTL_INT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0, 2876 "Interactivity score threshold"); 2877 SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW, 2878 &preempt_thresh, 0, 2879 "Maximal (lowest) priority for preemption"); 2880 SYSCTL_INT(_kern_sched, OID_AUTO, static_boost, CTLFLAG_RW, &static_boost, 0, 2881 "Assign static kernel priorities to sleeping threads"); 2882 SYSCTL_INT(_kern_sched, OID_AUTO, idlespins, CTLFLAG_RW, &sched_idlespins, 0, 2883 "Number of times idle thread will spin waiting for new work"); 2884 SYSCTL_INT(_kern_sched, OID_AUTO, idlespinthresh, CTLFLAG_RW, 2885 &sched_idlespinthresh, 0, 2886 "Threshold before we will permit idle thread spinning"); 2887 #ifdef SMP 2888 SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0, 2889 "Number of hz ticks to keep thread affinity for"); 2890 SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0, 2891 "Enables the long-term load balancer"); 2892 SYSCTL_INT(_kern_sched, OID_AUTO, balance_interval, CTLFLAG_RW, 2893 &balance_interval, 0, 2894 "Average period in stathz ticks to run the long-term balancer"); 2895 SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0, 2896 "Attempts to steal work from other cores before idling"); 2897 SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0, 2898 "Minimum load on remote CPU before we'll steal"); 2899 SYSCTL_PROC(_kern_sched, OID_AUTO, topology_spec, CTLTYPE_STRING | 2900 CTLFLAG_RD, NULL, 0, sysctl_kern_sched_topology_spec, "A", 2901 "XML dump of detected CPU topology"); 2902 #endif 2903 2904 /* ps compat. All cpu percentages from ULE are weighted. */ 2905 static int ccpu = 0; 2906 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 2907