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 * When a thread's sleep time is greater than its run time the 1455 * calculation is: 1456 * 1457 * scaling factor 1458 * interactivity score = --------------------- 1459 * sleep time / run time 1460 * 1461 * 1462 * When a thread's run time is greater than its sleep time the 1463 * calculation is: 1464 * 1465 * scaling factor 1466 * interactivity score = --------------------- + scaling factor 1467 * run time / sleep time 1468 */ 1469 static int 1470 sched_interact_score(struct thread *td) 1471 { 1472 struct td_sched *ts; 1473 int div; 1474 1475 ts = td->td_sched; 1476 /* 1477 * The score is only needed if this is likely to be an interactive 1478 * task. Don't go through the expense of computing it if there's 1479 * no chance. 1480 */ 1481 if (sched_interact <= SCHED_INTERACT_HALF && 1482 ts->ts_runtime >= ts->ts_slptime) 1483 return (SCHED_INTERACT_HALF); 1484 1485 if (ts->ts_runtime > ts->ts_slptime) { 1486 div = max(1, ts->ts_runtime / SCHED_INTERACT_HALF); 1487 return (SCHED_INTERACT_HALF + 1488 (SCHED_INTERACT_HALF - (ts->ts_slptime / div))); 1489 } 1490 if (ts->ts_slptime > ts->ts_runtime) { 1491 div = max(1, ts->ts_slptime / SCHED_INTERACT_HALF); 1492 return (ts->ts_runtime / div); 1493 } 1494 /* runtime == slptime */ 1495 if (ts->ts_runtime) 1496 return (SCHED_INTERACT_HALF); 1497 1498 /* 1499 * This can happen if slptime and runtime are 0. 1500 */ 1501 return (0); 1502 1503 } 1504 1505 /* 1506 * Scale the scheduling priority according to the "interactivity" of this 1507 * process. 1508 */ 1509 static void 1510 sched_priority(struct thread *td) 1511 { 1512 int score; 1513 int pri; 1514 1515 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 1516 return; 1517 /* 1518 * If the score is interactive we place the thread in the realtime 1519 * queue with a priority that is less than kernel and interrupt 1520 * priorities. These threads are not subject to nice restrictions. 1521 * 1522 * Scores greater than this are placed on the normal timeshare queue 1523 * where the priority is partially decided by the most recent cpu 1524 * utilization and the rest is decided by nice value. 1525 * 1526 * The nice value of the process has a linear effect on the calculated 1527 * score. Negative nice values make it easier for a thread to be 1528 * considered interactive. 1529 */ 1530 score = imax(0, sched_interact_score(td) + td->td_proc->p_nice); 1531 if (score < sched_interact) { 1532 pri = PRI_MIN_INTERACT; 1533 pri += ((PRI_MAX_INTERACT - PRI_MIN_INTERACT + 1) / 1534 sched_interact) * score; 1535 KASSERT(pri >= PRI_MIN_INTERACT && pri <= PRI_MAX_INTERACT, 1536 ("sched_priority: invalid interactive priority %d score %d", 1537 pri, score)); 1538 } else { 1539 pri = SCHED_PRI_MIN; 1540 if (td->td_sched->ts_ticks) 1541 pri += min(SCHED_PRI_TICKS(td->td_sched), 1542 SCHED_PRI_RANGE - 1); 1543 pri += SCHED_PRI_NICE(td->td_proc->p_nice); 1544 KASSERT(pri >= PRI_MIN_BATCH && pri <= PRI_MAX_BATCH, 1545 ("sched_priority: invalid priority %d: nice %d, " 1546 "ticks %d ftick %d ltick %d tick pri %d", 1547 pri, td->td_proc->p_nice, td->td_sched->ts_ticks, 1548 td->td_sched->ts_ftick, td->td_sched->ts_ltick, 1549 SCHED_PRI_TICKS(td->td_sched))); 1550 } 1551 sched_user_prio(td, pri); 1552 1553 return; 1554 } 1555 1556 /* 1557 * This routine enforces a maximum limit on the amount of scheduling history 1558 * kept. It is called after either the slptime or runtime is adjusted. This 1559 * function is ugly due to integer math. 1560 */ 1561 static void 1562 sched_interact_update(struct thread *td) 1563 { 1564 struct td_sched *ts; 1565 u_int sum; 1566 1567 ts = td->td_sched; 1568 sum = ts->ts_runtime + ts->ts_slptime; 1569 if (sum < SCHED_SLP_RUN_MAX) 1570 return; 1571 /* 1572 * This only happens from two places: 1573 * 1) We have added an unusual amount of run time from fork_exit. 1574 * 2) We have added an unusual amount of sleep time from sched_sleep(). 1575 */ 1576 if (sum > SCHED_SLP_RUN_MAX * 2) { 1577 if (ts->ts_runtime > ts->ts_slptime) { 1578 ts->ts_runtime = SCHED_SLP_RUN_MAX; 1579 ts->ts_slptime = 1; 1580 } else { 1581 ts->ts_slptime = SCHED_SLP_RUN_MAX; 1582 ts->ts_runtime = 1; 1583 } 1584 return; 1585 } 1586 /* 1587 * If we have exceeded by more than 1/5th then the algorithm below 1588 * will not bring us back into range. Dividing by two here forces 1589 * us into the range of [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX] 1590 */ 1591 if (sum > (SCHED_SLP_RUN_MAX / 5) * 6) { 1592 ts->ts_runtime /= 2; 1593 ts->ts_slptime /= 2; 1594 return; 1595 } 1596 ts->ts_runtime = (ts->ts_runtime / 5) * 4; 1597 ts->ts_slptime = (ts->ts_slptime / 5) * 4; 1598 } 1599 1600 /* 1601 * Scale back the interactivity history when a child thread is created. The 1602 * history is inherited from the parent but the thread may behave totally 1603 * differently. For example, a shell spawning a compiler process. We want 1604 * to learn that the compiler is behaving badly very quickly. 1605 */ 1606 static void 1607 sched_interact_fork(struct thread *td) 1608 { 1609 int ratio; 1610 int sum; 1611 1612 sum = td->td_sched->ts_runtime + td->td_sched->ts_slptime; 1613 if (sum > SCHED_SLP_RUN_FORK) { 1614 ratio = sum / SCHED_SLP_RUN_FORK; 1615 td->td_sched->ts_runtime /= ratio; 1616 td->td_sched->ts_slptime /= ratio; 1617 } 1618 } 1619 1620 /* 1621 * Called from proc0_init() to setup the scheduler fields. 1622 */ 1623 void 1624 schedinit(void) 1625 { 1626 1627 /* 1628 * Set up the scheduler specific parts of proc0. 1629 */ 1630 proc0.p_sched = NULL; /* XXX */ 1631 thread0.td_sched = &td_sched0; 1632 td_sched0.ts_ltick = ticks; 1633 td_sched0.ts_ftick = ticks; 1634 td_sched0.ts_slice = 0; 1635 } 1636 1637 /* 1638 * This is only somewhat accurate since given many processes of the same 1639 * priority they will switch when their slices run out, which will be 1640 * at most sched_slice stathz ticks. 1641 */ 1642 int 1643 sched_rr_interval(void) 1644 { 1645 1646 /* Convert sched_slice from stathz to hz. */ 1647 return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz)); 1648 } 1649 1650 /* 1651 * Update the percent cpu tracking information when it is requested or 1652 * the total history exceeds the maximum. We keep a sliding history of 1653 * tick counts that slowly decays. This is less precise than the 4BSD 1654 * mechanism since it happens with less regular and frequent events. 1655 */ 1656 static void 1657 sched_pctcpu_update(struct td_sched *ts, int run) 1658 { 1659 int t = ticks; 1660 1661 if (t - ts->ts_ltick >= SCHED_TICK_TARG) { 1662 ts->ts_ticks = 0; 1663 ts->ts_ftick = t - SCHED_TICK_TARG; 1664 } else if (t - ts->ts_ftick >= SCHED_TICK_MAX) { 1665 ts->ts_ticks = (ts->ts_ticks / (ts->ts_ltick - ts->ts_ftick)) * 1666 (ts->ts_ltick - (t - SCHED_TICK_TARG)); 1667 ts->ts_ftick = t - SCHED_TICK_TARG; 1668 } 1669 if (run) 1670 ts->ts_ticks += (t - ts->ts_ltick) << SCHED_TICK_SHIFT; 1671 ts->ts_ltick = t; 1672 } 1673 1674 /* 1675 * Adjust the priority of a thread. Move it to the appropriate run-queue 1676 * if necessary. This is the back-end for several priority related 1677 * functions. 1678 */ 1679 static void 1680 sched_thread_priority(struct thread *td, u_char prio) 1681 { 1682 struct td_sched *ts; 1683 struct tdq *tdq; 1684 int oldpri; 1685 1686 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "prio", 1687 "prio:%d", td->td_priority, "new prio:%d", prio, 1688 KTR_ATTR_LINKED, sched_tdname(curthread)); 1689 SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio); 1690 if (td != curthread && prio < td->td_priority) { 1691 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread), 1692 "lend prio", "prio:%d", td->td_priority, "new prio:%d", 1693 prio, KTR_ATTR_LINKED, sched_tdname(td)); 1694 SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio, 1695 curthread); 1696 } 1697 ts = td->td_sched; 1698 THREAD_LOCK_ASSERT(td, MA_OWNED); 1699 if (td->td_priority == prio) 1700 return; 1701 /* 1702 * If the priority has been elevated due to priority 1703 * propagation, we may have to move ourselves to a new 1704 * queue. This could be optimized to not re-add in some 1705 * cases. 1706 */ 1707 if (TD_ON_RUNQ(td) && prio < td->td_priority) { 1708 sched_rem(td); 1709 td->td_priority = prio; 1710 sched_add(td, SRQ_BORROWING); 1711 return; 1712 } 1713 /* 1714 * If the thread is currently running we may have to adjust the lowpri 1715 * information so other cpus are aware of our current priority. 1716 */ 1717 if (TD_IS_RUNNING(td)) { 1718 tdq = TDQ_CPU(ts->ts_cpu); 1719 oldpri = td->td_priority; 1720 td->td_priority = prio; 1721 if (prio < tdq->tdq_lowpri) 1722 tdq->tdq_lowpri = prio; 1723 else if (tdq->tdq_lowpri == oldpri) 1724 tdq_setlowpri(tdq, td); 1725 return; 1726 } 1727 td->td_priority = prio; 1728 } 1729 1730 /* 1731 * Update a thread's priority when it is lent another thread's 1732 * priority. 1733 */ 1734 void 1735 sched_lend_prio(struct thread *td, u_char prio) 1736 { 1737 1738 td->td_flags |= TDF_BORROWING; 1739 sched_thread_priority(td, prio); 1740 } 1741 1742 /* 1743 * Restore a thread's priority when priority propagation is 1744 * over. The prio argument is the minimum priority the thread 1745 * needs to have to satisfy other possible priority lending 1746 * requests. If the thread's regular priority is less 1747 * important than prio, the thread will keep a priority boost 1748 * of prio. 1749 */ 1750 void 1751 sched_unlend_prio(struct thread *td, u_char prio) 1752 { 1753 u_char base_pri; 1754 1755 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 1756 td->td_base_pri <= PRI_MAX_TIMESHARE) 1757 base_pri = td->td_user_pri; 1758 else 1759 base_pri = td->td_base_pri; 1760 if (prio >= base_pri) { 1761 td->td_flags &= ~TDF_BORROWING; 1762 sched_thread_priority(td, base_pri); 1763 } else 1764 sched_lend_prio(td, prio); 1765 } 1766 1767 /* 1768 * Standard entry for setting the priority to an absolute value. 1769 */ 1770 void 1771 sched_prio(struct thread *td, u_char prio) 1772 { 1773 u_char oldprio; 1774 1775 /* First, update the base priority. */ 1776 td->td_base_pri = prio; 1777 1778 /* 1779 * If the thread is borrowing another thread's priority, don't 1780 * ever lower the priority. 1781 */ 1782 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 1783 return; 1784 1785 /* Change the real priority. */ 1786 oldprio = td->td_priority; 1787 sched_thread_priority(td, prio); 1788 1789 /* 1790 * If the thread is on a turnstile, then let the turnstile update 1791 * its state. 1792 */ 1793 if (TD_ON_LOCK(td) && oldprio != prio) 1794 turnstile_adjust(td, oldprio); 1795 } 1796 1797 /* 1798 * Set the base user priority, does not effect current running priority. 1799 */ 1800 void 1801 sched_user_prio(struct thread *td, u_char prio) 1802 { 1803 1804 td->td_base_user_pri = prio; 1805 if (td->td_lend_user_pri <= prio) 1806 return; 1807 td->td_user_pri = prio; 1808 } 1809 1810 void 1811 sched_lend_user_prio(struct thread *td, u_char prio) 1812 { 1813 1814 THREAD_LOCK_ASSERT(td, MA_OWNED); 1815 td->td_lend_user_pri = prio; 1816 td->td_user_pri = min(prio, td->td_base_user_pri); 1817 if (td->td_priority > td->td_user_pri) 1818 sched_prio(td, td->td_user_pri); 1819 else if (td->td_priority != td->td_user_pri) 1820 td->td_flags |= TDF_NEEDRESCHED; 1821 } 1822 1823 /* 1824 * Handle migration from sched_switch(). This happens only for 1825 * cpu binding. 1826 */ 1827 static struct mtx * 1828 sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags) 1829 { 1830 struct tdq *tdn; 1831 1832 tdn = TDQ_CPU(td->td_sched->ts_cpu); 1833 #ifdef SMP 1834 tdq_load_rem(tdq, td); 1835 /* 1836 * Do the lock dance required to avoid LOR. We grab an extra 1837 * spinlock nesting to prevent preemption while we're 1838 * not holding either run-queue lock. 1839 */ 1840 spinlock_enter(); 1841 thread_lock_block(td); /* This releases the lock on tdq. */ 1842 1843 /* 1844 * Acquire both run-queue locks before placing the thread on the new 1845 * run-queue to avoid deadlocks created by placing a thread with a 1846 * blocked lock on the run-queue of a remote processor. The deadlock 1847 * occurs when a third processor attempts to lock the two queues in 1848 * question while the target processor is spinning with its own 1849 * run-queue lock held while waiting for the blocked lock to clear. 1850 */ 1851 tdq_lock_pair(tdn, tdq); 1852 tdq_add(tdn, td, flags); 1853 tdq_notify(tdn, td); 1854 TDQ_UNLOCK(tdn); 1855 spinlock_exit(); 1856 #endif 1857 return (TDQ_LOCKPTR(tdn)); 1858 } 1859 1860 /* 1861 * Variadic version of thread_lock_unblock() that does not assume td_lock 1862 * is blocked. 1863 */ 1864 static inline void 1865 thread_unblock_switch(struct thread *td, struct mtx *mtx) 1866 { 1867 atomic_store_rel_ptr((volatile uintptr_t *)&td->td_lock, 1868 (uintptr_t)mtx); 1869 } 1870 1871 /* 1872 * Switch threads. This function has to handle threads coming in while 1873 * blocked for some reason, running, or idle. It also must deal with 1874 * migrating a thread from one queue to another as running threads may 1875 * be assigned elsewhere via binding. 1876 */ 1877 void 1878 sched_switch(struct thread *td, struct thread *newtd, int flags) 1879 { 1880 struct tdq *tdq; 1881 struct td_sched *ts; 1882 struct mtx *mtx; 1883 int srqflag; 1884 int cpuid, preempted; 1885 1886 THREAD_LOCK_ASSERT(td, MA_OWNED); 1887 KASSERT(newtd == NULL, ("sched_switch: Unsupported newtd argument")); 1888 1889 cpuid = PCPU_GET(cpuid); 1890 tdq = TDQ_CPU(cpuid); 1891 ts = td->td_sched; 1892 mtx = td->td_lock; 1893 sched_pctcpu_update(ts, 1); 1894 ts->ts_rltick = ticks; 1895 td->td_lastcpu = td->td_oncpu; 1896 td->td_oncpu = NOCPU; 1897 preempted = !((td->td_flags & TDF_SLICEEND) || 1898 (flags & SWT_RELINQUISH)); 1899 td->td_flags &= ~(TDF_NEEDRESCHED | TDF_SLICEEND); 1900 td->td_owepreempt = 0; 1901 if (!TD_IS_IDLETHREAD(td)) 1902 tdq->tdq_switchcnt++; 1903 /* 1904 * The lock pointer in an idle thread should never change. Reset it 1905 * to CAN_RUN as well. 1906 */ 1907 if (TD_IS_IDLETHREAD(td)) { 1908 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1909 TD_SET_CAN_RUN(td); 1910 } else if (TD_IS_RUNNING(td)) { 1911 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1912 srqflag = preempted ? 1913 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 1914 SRQ_OURSELF|SRQ_YIELDING; 1915 #ifdef SMP 1916 if (THREAD_CAN_MIGRATE(td) && !THREAD_CAN_SCHED(td, ts->ts_cpu)) 1917 ts->ts_cpu = sched_pickcpu(td, 0); 1918 #endif 1919 if (ts->ts_cpu == cpuid) 1920 tdq_runq_add(tdq, td, srqflag); 1921 else { 1922 KASSERT(THREAD_CAN_MIGRATE(td) || 1923 (ts->ts_flags & TSF_BOUND) != 0, 1924 ("Thread %p shouldn't migrate", td)); 1925 mtx = sched_switch_migrate(tdq, td, srqflag); 1926 } 1927 } else { 1928 /* This thread must be going to sleep. */ 1929 TDQ_LOCK(tdq); 1930 mtx = thread_lock_block(td); 1931 tdq_load_rem(tdq, td); 1932 } 1933 /* 1934 * We enter here with the thread blocked and assigned to the 1935 * appropriate cpu run-queue or sleep-queue and with the current 1936 * thread-queue locked. 1937 */ 1938 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 1939 newtd = choosethread(); 1940 /* 1941 * Call the MD code to switch contexts if necessary. 1942 */ 1943 if (td != newtd) { 1944 #ifdef HWPMC_HOOKS 1945 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1946 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 1947 #endif 1948 SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc); 1949 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 1950 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 1951 sched_pctcpu_update(newtd->td_sched, 0); 1952 1953 #ifdef KDTRACE_HOOKS 1954 /* 1955 * If DTrace has set the active vtime enum to anything 1956 * other than INACTIVE (0), then it should have set the 1957 * function to call. 1958 */ 1959 if (dtrace_vtime_active) 1960 (*dtrace_vtime_switch_func)(newtd); 1961 #endif 1962 1963 cpu_switch(td, newtd, mtx); 1964 /* 1965 * We may return from cpu_switch on a different cpu. However, 1966 * we always return with td_lock pointing to the current cpu's 1967 * run queue lock. 1968 */ 1969 cpuid = PCPU_GET(cpuid); 1970 tdq = TDQ_CPU(cpuid); 1971 lock_profile_obtain_lock_success( 1972 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 1973 1974 SDT_PROBE0(sched, , , on__cpu); 1975 #ifdef HWPMC_HOOKS 1976 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1977 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 1978 #endif 1979 } else { 1980 thread_unblock_switch(td, mtx); 1981 SDT_PROBE0(sched, , , remain__cpu); 1982 } 1983 /* 1984 * Assert that all went well and return. 1985 */ 1986 TDQ_LOCK_ASSERT(tdq, MA_OWNED|MA_NOTRECURSED); 1987 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1988 td->td_oncpu = cpuid; 1989 } 1990 1991 /* 1992 * Adjust thread priorities as a result of a nice request. 1993 */ 1994 void 1995 sched_nice(struct proc *p, int nice) 1996 { 1997 struct thread *td; 1998 1999 PROC_LOCK_ASSERT(p, MA_OWNED); 2000 2001 p->p_nice = nice; 2002 FOREACH_THREAD_IN_PROC(p, td) { 2003 thread_lock(td); 2004 sched_priority(td); 2005 sched_prio(td, td->td_base_user_pri); 2006 thread_unlock(td); 2007 } 2008 } 2009 2010 /* 2011 * Record the sleep time for the interactivity scorer. 2012 */ 2013 void 2014 sched_sleep(struct thread *td, int prio) 2015 { 2016 2017 THREAD_LOCK_ASSERT(td, MA_OWNED); 2018 2019 td->td_slptick = ticks; 2020 if (TD_IS_SUSPENDED(td) || prio >= PSOCK) 2021 td->td_flags |= TDF_CANSWAP; 2022 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 2023 return; 2024 if (static_boost == 1 && prio) 2025 sched_prio(td, prio); 2026 else if (static_boost && td->td_priority > static_boost) 2027 sched_prio(td, static_boost); 2028 } 2029 2030 /* 2031 * Schedule a thread to resume execution and record how long it voluntarily 2032 * slept. We also update the pctcpu, interactivity, and priority. 2033 */ 2034 void 2035 sched_wakeup(struct thread *td) 2036 { 2037 struct td_sched *ts; 2038 int slptick; 2039 2040 THREAD_LOCK_ASSERT(td, MA_OWNED); 2041 ts = td->td_sched; 2042 td->td_flags &= ~TDF_CANSWAP; 2043 /* 2044 * If we slept for more than a tick update our interactivity and 2045 * priority. 2046 */ 2047 slptick = td->td_slptick; 2048 td->td_slptick = 0; 2049 if (slptick && slptick != ticks) { 2050 ts->ts_slptime += (ticks - slptick) << SCHED_TICK_SHIFT; 2051 sched_interact_update(td); 2052 sched_pctcpu_update(ts, 0); 2053 } 2054 /* 2055 * Reset the slice value since we slept and advanced the round-robin. 2056 */ 2057 ts->ts_slice = 0; 2058 sched_add(td, SRQ_BORING); 2059 } 2060 2061 /* 2062 * Penalize the parent for creating a new child and initialize the child's 2063 * priority. 2064 */ 2065 void 2066 sched_fork(struct thread *td, struct thread *child) 2067 { 2068 THREAD_LOCK_ASSERT(td, MA_OWNED); 2069 sched_pctcpu_update(td->td_sched, 1); 2070 sched_fork_thread(td, child); 2071 /* 2072 * Penalize the parent and child for forking. 2073 */ 2074 sched_interact_fork(child); 2075 sched_priority(child); 2076 td->td_sched->ts_runtime += tickincr; 2077 sched_interact_update(td); 2078 sched_priority(td); 2079 } 2080 2081 /* 2082 * Fork a new thread, may be within the same process. 2083 */ 2084 void 2085 sched_fork_thread(struct thread *td, struct thread *child) 2086 { 2087 struct td_sched *ts; 2088 struct td_sched *ts2; 2089 struct tdq *tdq; 2090 2091 tdq = TDQ_SELF(); 2092 THREAD_LOCK_ASSERT(td, MA_OWNED); 2093 /* 2094 * Initialize child. 2095 */ 2096 ts = td->td_sched; 2097 ts2 = child->td_sched; 2098 child->td_oncpu = NOCPU; 2099 child->td_lastcpu = NOCPU; 2100 child->td_lock = TDQ_LOCKPTR(tdq); 2101 child->td_cpuset = cpuset_ref(td->td_cpuset); 2102 ts2->ts_cpu = ts->ts_cpu; 2103 ts2->ts_flags = 0; 2104 /* 2105 * Grab our parents cpu estimation information. 2106 */ 2107 ts2->ts_ticks = ts->ts_ticks; 2108 ts2->ts_ltick = ts->ts_ltick; 2109 ts2->ts_ftick = ts->ts_ftick; 2110 /* 2111 * Do not inherit any borrowed priority from the parent. 2112 */ 2113 child->td_priority = child->td_base_pri; 2114 /* 2115 * And update interactivity score. 2116 */ 2117 ts2->ts_slptime = ts->ts_slptime; 2118 ts2->ts_runtime = ts->ts_runtime; 2119 /* Attempt to quickly learn interactivity. */ 2120 ts2->ts_slice = tdq_slice(tdq) - sched_slice_min; 2121 #ifdef KTR 2122 bzero(ts2->ts_name, sizeof(ts2->ts_name)); 2123 #endif 2124 } 2125 2126 /* 2127 * Adjust the priority class of a thread. 2128 */ 2129 void 2130 sched_class(struct thread *td, int class) 2131 { 2132 2133 THREAD_LOCK_ASSERT(td, MA_OWNED); 2134 if (td->td_pri_class == class) 2135 return; 2136 td->td_pri_class = class; 2137 } 2138 2139 /* 2140 * Return some of the child's priority and interactivity to the parent. 2141 */ 2142 void 2143 sched_exit(struct proc *p, struct thread *child) 2144 { 2145 struct thread *td; 2146 2147 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "proc exit", 2148 "prio:%d", child->td_priority); 2149 PROC_LOCK_ASSERT(p, MA_OWNED); 2150 td = FIRST_THREAD_IN_PROC(p); 2151 sched_exit_thread(td, child); 2152 } 2153 2154 /* 2155 * Penalize another thread for the time spent on this one. This helps to 2156 * worsen the priority and interactivity of processes which schedule batch 2157 * jobs such as make. This has little effect on the make process itself but 2158 * causes new processes spawned by it to receive worse scores immediately. 2159 */ 2160 void 2161 sched_exit_thread(struct thread *td, struct thread *child) 2162 { 2163 2164 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "thread exit", 2165 "prio:%d", child->td_priority); 2166 /* 2167 * Give the child's runtime to the parent without returning the 2168 * sleep time as a penalty to the parent. This causes shells that 2169 * launch expensive things to mark their children as expensive. 2170 */ 2171 thread_lock(td); 2172 td->td_sched->ts_runtime += child->td_sched->ts_runtime; 2173 sched_interact_update(td); 2174 sched_priority(td); 2175 thread_unlock(td); 2176 } 2177 2178 void 2179 sched_preempt(struct thread *td) 2180 { 2181 struct tdq *tdq; 2182 2183 SDT_PROBE2(sched, , , surrender, td, td->td_proc); 2184 2185 thread_lock(td); 2186 tdq = TDQ_SELF(); 2187 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2188 tdq->tdq_ipipending = 0; 2189 if (td->td_priority > tdq->tdq_lowpri) { 2190 int flags; 2191 2192 flags = SW_INVOL | SW_PREEMPT; 2193 if (td->td_critnest > 1) 2194 td->td_owepreempt = 1; 2195 else if (TD_IS_IDLETHREAD(td)) 2196 mi_switch(flags | SWT_REMOTEWAKEIDLE, NULL); 2197 else 2198 mi_switch(flags | SWT_REMOTEPREEMPT, NULL); 2199 } 2200 thread_unlock(td); 2201 } 2202 2203 /* 2204 * Fix priorities on return to user-space. Priorities may be elevated due 2205 * to static priorities in msleep() or similar. 2206 */ 2207 void 2208 sched_userret(struct thread *td) 2209 { 2210 /* 2211 * XXX we cheat slightly on the locking here to avoid locking in 2212 * the usual case. Setting td_priority here is essentially an 2213 * incomplete workaround for not setting it properly elsewhere. 2214 * Now that some interrupt handlers are threads, not setting it 2215 * properly elsewhere can clobber it in the window between setting 2216 * it here and returning to user mode, so don't waste time setting 2217 * it perfectly here. 2218 */ 2219 KASSERT((td->td_flags & TDF_BORROWING) == 0, 2220 ("thread with borrowed priority returning to userland")); 2221 if (td->td_priority != td->td_user_pri) { 2222 thread_lock(td); 2223 td->td_priority = td->td_user_pri; 2224 td->td_base_pri = td->td_user_pri; 2225 tdq_setlowpri(TDQ_SELF(), td); 2226 thread_unlock(td); 2227 } 2228 } 2229 2230 /* 2231 * Handle a stathz tick. This is really only relevant for timeshare 2232 * threads. 2233 */ 2234 void 2235 sched_clock(struct thread *td) 2236 { 2237 struct tdq *tdq; 2238 struct td_sched *ts; 2239 2240 THREAD_LOCK_ASSERT(td, MA_OWNED); 2241 tdq = TDQ_SELF(); 2242 #ifdef SMP 2243 /* 2244 * We run the long term load balancer infrequently on the first cpu. 2245 */ 2246 if (balance_tdq == tdq) { 2247 if (balance_ticks && --balance_ticks == 0) 2248 sched_balance(); 2249 } 2250 #endif 2251 /* 2252 * Save the old switch count so we have a record of the last ticks 2253 * activity. Initialize the new switch count based on our load. 2254 * If there is some activity seed it to reflect that. 2255 */ 2256 tdq->tdq_oldswitchcnt = tdq->tdq_switchcnt; 2257 tdq->tdq_switchcnt = tdq->tdq_load; 2258 /* 2259 * Advance the insert index once for each tick to ensure that all 2260 * threads get a chance to run. 2261 */ 2262 if (tdq->tdq_idx == tdq->tdq_ridx) { 2263 tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS; 2264 if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx])) 2265 tdq->tdq_ridx = tdq->tdq_idx; 2266 } 2267 ts = td->td_sched; 2268 sched_pctcpu_update(ts, 1); 2269 if (td->td_pri_class & PRI_FIFO_BIT) 2270 return; 2271 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) { 2272 /* 2273 * We used a tick; charge it to the thread so 2274 * that we can compute our interactivity. 2275 */ 2276 td->td_sched->ts_runtime += tickincr; 2277 sched_interact_update(td); 2278 sched_priority(td); 2279 } 2280 2281 /* 2282 * Force a context switch if the current thread has used up a full 2283 * time slice (default is 100ms). 2284 */ 2285 if (!TD_IS_IDLETHREAD(td) && ++ts->ts_slice >= tdq_slice(tdq)) { 2286 ts->ts_slice = 0; 2287 td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND; 2288 } 2289 } 2290 2291 /* 2292 * Called once per hz tick. 2293 */ 2294 void 2295 sched_tick(int cnt) 2296 { 2297 2298 } 2299 2300 /* 2301 * Return whether the current CPU has runnable tasks. Used for in-kernel 2302 * cooperative idle threads. 2303 */ 2304 int 2305 sched_runnable(void) 2306 { 2307 struct tdq *tdq; 2308 int load; 2309 2310 load = 1; 2311 2312 tdq = TDQ_SELF(); 2313 if ((curthread->td_flags & TDF_IDLETD) != 0) { 2314 if (tdq->tdq_load > 0) 2315 goto out; 2316 } else 2317 if (tdq->tdq_load - 1 > 0) 2318 goto out; 2319 load = 0; 2320 out: 2321 return (load); 2322 } 2323 2324 /* 2325 * Choose the highest priority thread to run. The thread is removed from 2326 * the run-queue while running however the load remains. For SMP we set 2327 * the tdq in the global idle bitmask if it idles here. 2328 */ 2329 struct thread * 2330 sched_choose(void) 2331 { 2332 struct thread *td; 2333 struct tdq *tdq; 2334 2335 tdq = TDQ_SELF(); 2336 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2337 td = tdq_choose(tdq); 2338 if (td) { 2339 tdq_runq_rem(tdq, td); 2340 tdq->tdq_lowpri = td->td_priority; 2341 return (td); 2342 } 2343 tdq->tdq_lowpri = PRI_MAX_IDLE; 2344 return (PCPU_GET(idlethread)); 2345 } 2346 2347 /* 2348 * Set owepreempt if necessary. Preemption never happens directly in ULE, 2349 * we always request it once we exit a critical section. 2350 */ 2351 static inline void 2352 sched_setpreempt(struct thread *td) 2353 { 2354 struct thread *ctd; 2355 int cpri; 2356 int pri; 2357 2358 THREAD_LOCK_ASSERT(curthread, MA_OWNED); 2359 2360 ctd = curthread; 2361 pri = td->td_priority; 2362 cpri = ctd->td_priority; 2363 if (pri < cpri) 2364 ctd->td_flags |= TDF_NEEDRESCHED; 2365 if (panicstr != NULL || pri >= cpri || cold || TD_IS_INHIBITED(ctd)) 2366 return; 2367 if (!sched_shouldpreempt(pri, cpri, 0)) 2368 return; 2369 ctd->td_owepreempt = 1; 2370 } 2371 2372 /* 2373 * Add a thread to a thread queue. Select the appropriate runq and add the 2374 * thread to it. This is the internal function called when the tdq is 2375 * predetermined. 2376 */ 2377 void 2378 tdq_add(struct tdq *tdq, struct thread *td, int flags) 2379 { 2380 2381 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2382 KASSERT((td->td_inhibitors == 0), 2383 ("sched_add: trying to run inhibited thread")); 2384 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 2385 ("sched_add: bad thread state")); 2386 KASSERT(td->td_flags & TDF_INMEM, 2387 ("sched_add: thread swapped out")); 2388 2389 if (td->td_priority < tdq->tdq_lowpri) 2390 tdq->tdq_lowpri = td->td_priority; 2391 tdq_runq_add(tdq, td, flags); 2392 tdq_load_add(tdq, td); 2393 } 2394 2395 /* 2396 * Select the target thread queue and add a thread to it. Request 2397 * preemption or IPI a remote processor if required. 2398 */ 2399 void 2400 sched_add(struct thread *td, int flags) 2401 { 2402 struct tdq *tdq; 2403 #ifdef SMP 2404 int cpu; 2405 #endif 2406 2407 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 2408 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 2409 sched_tdname(curthread)); 2410 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 2411 KTR_ATTR_LINKED, sched_tdname(td)); 2412 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 2413 flags & SRQ_PREEMPTED); 2414 THREAD_LOCK_ASSERT(td, MA_OWNED); 2415 /* 2416 * Recalculate the priority before we select the target cpu or 2417 * run-queue. 2418 */ 2419 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 2420 sched_priority(td); 2421 #ifdef SMP 2422 /* 2423 * Pick the destination cpu and if it isn't ours transfer to the 2424 * target cpu. 2425 */ 2426 cpu = sched_pickcpu(td, flags); 2427 tdq = sched_setcpu(td, cpu, flags); 2428 tdq_add(tdq, td, flags); 2429 if (cpu != PCPU_GET(cpuid)) { 2430 tdq_notify(tdq, td); 2431 return; 2432 } 2433 #else 2434 tdq = TDQ_SELF(); 2435 TDQ_LOCK(tdq); 2436 /* 2437 * Now that the thread is moving to the run-queue, set the lock 2438 * to the scheduler's lock. 2439 */ 2440 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 2441 tdq_add(tdq, td, flags); 2442 #endif 2443 if (!(flags & SRQ_YIELDING)) 2444 sched_setpreempt(td); 2445 } 2446 2447 /* 2448 * Remove a thread from a run-queue without running it. This is used 2449 * when we're stealing a thread from a remote queue. Otherwise all threads 2450 * exit by calling sched_exit_thread() and sched_throw() themselves. 2451 */ 2452 void 2453 sched_rem(struct thread *td) 2454 { 2455 struct tdq *tdq; 2456 2457 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "runq rem", 2458 "prio:%d", td->td_priority); 2459 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL); 2460 tdq = TDQ_CPU(td->td_sched->ts_cpu); 2461 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2462 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2463 KASSERT(TD_ON_RUNQ(td), 2464 ("sched_rem: thread not on run queue")); 2465 tdq_runq_rem(tdq, td); 2466 tdq_load_rem(tdq, td); 2467 TD_SET_CAN_RUN(td); 2468 if (td->td_priority == tdq->tdq_lowpri) 2469 tdq_setlowpri(tdq, NULL); 2470 } 2471 2472 /* 2473 * Fetch cpu utilization information. Updates on demand. 2474 */ 2475 fixpt_t 2476 sched_pctcpu(struct thread *td) 2477 { 2478 fixpt_t pctcpu; 2479 struct td_sched *ts; 2480 2481 pctcpu = 0; 2482 ts = td->td_sched; 2483 if (ts == NULL) 2484 return (0); 2485 2486 THREAD_LOCK_ASSERT(td, MA_OWNED); 2487 sched_pctcpu_update(ts, TD_IS_RUNNING(td)); 2488 if (ts->ts_ticks) { 2489 int rtick; 2490 2491 /* How many rtick per second ? */ 2492 rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz); 2493 pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT; 2494 } 2495 2496 return (pctcpu); 2497 } 2498 2499 /* 2500 * Enforce affinity settings for a thread. Called after adjustments to 2501 * cpumask. 2502 */ 2503 void 2504 sched_affinity(struct thread *td) 2505 { 2506 #ifdef SMP 2507 struct td_sched *ts; 2508 2509 THREAD_LOCK_ASSERT(td, MA_OWNED); 2510 ts = td->td_sched; 2511 if (THREAD_CAN_SCHED(td, ts->ts_cpu)) 2512 return; 2513 if (TD_ON_RUNQ(td)) { 2514 sched_rem(td); 2515 sched_add(td, SRQ_BORING); 2516 return; 2517 } 2518 if (!TD_IS_RUNNING(td)) 2519 return; 2520 /* 2521 * Force a switch before returning to userspace. If the 2522 * target thread is not running locally send an ipi to force 2523 * the issue. 2524 */ 2525 td->td_flags |= TDF_NEEDRESCHED; 2526 if (td != curthread) 2527 ipi_cpu(ts->ts_cpu, IPI_PREEMPT); 2528 #endif 2529 } 2530 2531 /* 2532 * Bind a thread to a target cpu. 2533 */ 2534 void 2535 sched_bind(struct thread *td, int cpu) 2536 { 2537 struct td_sched *ts; 2538 2539 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 2540 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 2541 ts = td->td_sched; 2542 if (ts->ts_flags & TSF_BOUND) 2543 sched_unbind(td); 2544 KASSERT(THREAD_CAN_MIGRATE(td), ("%p must be migratable", td)); 2545 ts->ts_flags |= TSF_BOUND; 2546 sched_pin(); 2547 if (PCPU_GET(cpuid) == cpu) 2548 return; 2549 ts->ts_cpu = cpu; 2550 /* When we return from mi_switch we'll be on the correct cpu. */ 2551 mi_switch(SW_VOL, NULL); 2552 } 2553 2554 /* 2555 * Release a bound thread. 2556 */ 2557 void 2558 sched_unbind(struct thread *td) 2559 { 2560 struct td_sched *ts; 2561 2562 THREAD_LOCK_ASSERT(td, MA_OWNED); 2563 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 2564 ts = td->td_sched; 2565 if ((ts->ts_flags & TSF_BOUND) == 0) 2566 return; 2567 ts->ts_flags &= ~TSF_BOUND; 2568 sched_unpin(); 2569 } 2570 2571 int 2572 sched_is_bound(struct thread *td) 2573 { 2574 THREAD_LOCK_ASSERT(td, MA_OWNED); 2575 return (td->td_sched->ts_flags & TSF_BOUND); 2576 } 2577 2578 /* 2579 * Basic yield call. 2580 */ 2581 void 2582 sched_relinquish(struct thread *td) 2583 { 2584 thread_lock(td); 2585 mi_switch(SW_VOL | SWT_RELINQUISH, NULL); 2586 thread_unlock(td); 2587 } 2588 2589 /* 2590 * Return the total system load. 2591 */ 2592 int 2593 sched_load(void) 2594 { 2595 #ifdef SMP 2596 int total; 2597 int i; 2598 2599 total = 0; 2600 CPU_FOREACH(i) 2601 total += TDQ_CPU(i)->tdq_sysload; 2602 return (total); 2603 #else 2604 return (TDQ_SELF()->tdq_sysload); 2605 #endif 2606 } 2607 2608 int 2609 sched_sizeof_proc(void) 2610 { 2611 return (sizeof(struct proc)); 2612 } 2613 2614 int 2615 sched_sizeof_thread(void) 2616 { 2617 return (sizeof(struct thread) + sizeof(struct td_sched)); 2618 } 2619 2620 #ifdef SMP 2621 #define TDQ_IDLESPIN(tdq) \ 2622 ((tdq)->tdq_cg != NULL && ((tdq)->tdq_cg->cg_flags & CG_FLAG_THREAD) == 0) 2623 #else 2624 #define TDQ_IDLESPIN(tdq) 1 2625 #endif 2626 2627 /* 2628 * The actual idle process. 2629 */ 2630 void 2631 sched_idletd(void *dummy) 2632 { 2633 struct thread *td; 2634 struct tdq *tdq; 2635 int oldswitchcnt, switchcnt; 2636 int i; 2637 2638 mtx_assert(&Giant, MA_NOTOWNED); 2639 td = curthread; 2640 tdq = TDQ_SELF(); 2641 THREAD_NO_SLEEPING(); 2642 oldswitchcnt = -1; 2643 for (;;) { 2644 if (tdq->tdq_load) { 2645 thread_lock(td); 2646 mi_switch(SW_VOL | SWT_IDLE, NULL); 2647 thread_unlock(td); 2648 } 2649 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2650 #ifdef SMP 2651 if (switchcnt != oldswitchcnt) { 2652 oldswitchcnt = switchcnt; 2653 if (tdq_idled(tdq) == 0) 2654 continue; 2655 } 2656 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2657 #else 2658 oldswitchcnt = switchcnt; 2659 #endif 2660 /* 2661 * If we're switching very frequently, spin while checking 2662 * for load rather than entering a low power state that 2663 * may require an IPI. However, don't do any busy 2664 * loops while on SMT machines as this simply steals 2665 * cycles from cores doing useful work. 2666 */ 2667 if (TDQ_IDLESPIN(tdq) && switchcnt > sched_idlespinthresh) { 2668 for (i = 0; i < sched_idlespins; i++) { 2669 if (tdq->tdq_load) 2670 break; 2671 cpu_spinwait(); 2672 } 2673 } 2674 2675 /* If there was context switch during spin, restart it. */ 2676 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2677 if (tdq->tdq_load != 0 || switchcnt != oldswitchcnt) 2678 continue; 2679 2680 /* Run main MD idle handler. */ 2681 tdq->tdq_cpu_idle = 1; 2682 /* 2683 * Make sure that tdq_cpu_idle update is globally visible 2684 * before cpu_idle() read tdq_load. The order is important 2685 * to avoid race with tdq_notify. 2686 */ 2687 atomic_thread_fence_seq_cst(); 2688 cpu_idle(switchcnt * 4 > sched_idlespinthresh); 2689 tdq->tdq_cpu_idle = 0; 2690 2691 /* 2692 * Account thread-less hardware interrupts and 2693 * other wakeup reasons equal to context switches. 2694 */ 2695 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2696 if (switchcnt != oldswitchcnt) 2697 continue; 2698 tdq->tdq_switchcnt++; 2699 oldswitchcnt++; 2700 } 2701 } 2702 2703 /* 2704 * A CPU is entering for the first time or a thread is exiting. 2705 */ 2706 void 2707 sched_throw(struct thread *td) 2708 { 2709 struct thread *newtd; 2710 struct tdq *tdq; 2711 2712 tdq = TDQ_SELF(); 2713 if (td == NULL) { 2714 /* Correct spinlock nesting and acquire the correct lock. */ 2715 TDQ_LOCK(tdq); 2716 spinlock_exit(); 2717 PCPU_SET(switchtime, cpu_ticks()); 2718 PCPU_SET(switchticks, ticks); 2719 } else { 2720 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2721 tdq_load_rem(tdq, td); 2722 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 2723 td->td_lastcpu = td->td_oncpu; 2724 td->td_oncpu = NOCPU; 2725 } 2726 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 2727 newtd = choosethread(); 2728 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 2729 cpu_throw(td, newtd); /* doesn't return */ 2730 } 2731 2732 /* 2733 * This is called from fork_exit(). Just acquire the correct locks and 2734 * let fork do the rest of the work. 2735 */ 2736 void 2737 sched_fork_exit(struct thread *td) 2738 { 2739 struct tdq *tdq; 2740 int cpuid; 2741 2742 /* 2743 * Finish setting up thread glue so that it begins execution in a 2744 * non-nested critical section with the scheduler lock held. 2745 */ 2746 cpuid = PCPU_GET(cpuid); 2747 tdq = TDQ_CPU(cpuid); 2748 if (TD_IS_IDLETHREAD(td)) 2749 td->td_lock = TDQ_LOCKPTR(tdq); 2750 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2751 td->td_oncpu = cpuid; 2752 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 2753 lock_profile_obtain_lock_success( 2754 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 2755 } 2756 2757 /* 2758 * Create on first use to catch odd startup conditons. 2759 */ 2760 char * 2761 sched_tdname(struct thread *td) 2762 { 2763 #ifdef KTR 2764 struct td_sched *ts; 2765 2766 ts = td->td_sched; 2767 if (ts->ts_name[0] == '\0') 2768 snprintf(ts->ts_name, sizeof(ts->ts_name), 2769 "%s tid %d", td->td_name, td->td_tid); 2770 return (ts->ts_name); 2771 #else 2772 return (td->td_name); 2773 #endif 2774 } 2775 2776 #ifdef KTR 2777 void 2778 sched_clear_tdname(struct thread *td) 2779 { 2780 struct td_sched *ts; 2781 2782 ts = td->td_sched; 2783 ts->ts_name[0] = '\0'; 2784 } 2785 #endif 2786 2787 #ifdef SMP 2788 2789 /* 2790 * Build the CPU topology dump string. Is recursively called to collect 2791 * the topology tree. 2792 */ 2793 static int 2794 sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, struct cpu_group *cg, 2795 int indent) 2796 { 2797 char cpusetbuf[CPUSETBUFSIZ]; 2798 int i, first; 2799 2800 sbuf_printf(sb, "%*s<group level=\"%d\" cache-level=\"%d\">\n", indent, 2801 "", 1 + indent / 2, cg->cg_level); 2802 sbuf_printf(sb, "%*s <cpu count=\"%d\" mask=\"%s\">", indent, "", 2803 cg->cg_count, cpusetobj_strprint(cpusetbuf, &cg->cg_mask)); 2804 first = TRUE; 2805 for (i = 0; i < MAXCPU; i++) { 2806 if (CPU_ISSET(i, &cg->cg_mask)) { 2807 if (!first) 2808 sbuf_printf(sb, ", "); 2809 else 2810 first = FALSE; 2811 sbuf_printf(sb, "%d", i); 2812 } 2813 } 2814 sbuf_printf(sb, "</cpu>\n"); 2815 2816 if (cg->cg_flags != 0) { 2817 sbuf_printf(sb, "%*s <flags>", indent, ""); 2818 if ((cg->cg_flags & CG_FLAG_HTT) != 0) 2819 sbuf_printf(sb, "<flag name=\"HTT\">HTT group</flag>"); 2820 if ((cg->cg_flags & CG_FLAG_THREAD) != 0) 2821 sbuf_printf(sb, "<flag name=\"THREAD\">THREAD group</flag>"); 2822 if ((cg->cg_flags & CG_FLAG_SMT) != 0) 2823 sbuf_printf(sb, "<flag name=\"SMT\">SMT group</flag>"); 2824 sbuf_printf(sb, "</flags>\n"); 2825 } 2826 2827 if (cg->cg_children > 0) { 2828 sbuf_printf(sb, "%*s <children>\n", indent, ""); 2829 for (i = 0; i < cg->cg_children; i++) 2830 sysctl_kern_sched_topology_spec_internal(sb, 2831 &cg->cg_child[i], indent+2); 2832 sbuf_printf(sb, "%*s </children>\n", indent, ""); 2833 } 2834 sbuf_printf(sb, "%*s</group>\n", indent, ""); 2835 return (0); 2836 } 2837 2838 /* 2839 * Sysctl handler for retrieving topology dump. It's a wrapper for 2840 * the recursive sysctl_kern_smp_topology_spec_internal(). 2841 */ 2842 static int 2843 sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS) 2844 { 2845 struct sbuf *topo; 2846 int err; 2847 2848 KASSERT(cpu_top != NULL, ("cpu_top isn't initialized")); 2849 2850 topo = sbuf_new_for_sysctl(NULL, NULL, 512, req); 2851 if (topo == NULL) 2852 return (ENOMEM); 2853 2854 sbuf_printf(topo, "<groups>\n"); 2855 err = sysctl_kern_sched_topology_spec_internal(topo, cpu_top, 1); 2856 sbuf_printf(topo, "</groups>\n"); 2857 2858 if (err == 0) { 2859 err = sbuf_finish(topo); 2860 } 2861 sbuf_delete(topo); 2862 return (err); 2863 } 2864 2865 #endif 2866 2867 static int 2868 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 2869 { 2870 int error, new_val, period; 2871 2872 period = 1000000 / realstathz; 2873 new_val = period * sched_slice; 2874 error = sysctl_handle_int(oidp, &new_val, 0, req); 2875 if (error != 0 || req->newptr == NULL) 2876 return (error); 2877 if (new_val <= 0) 2878 return (EINVAL); 2879 sched_slice = imax(1, (new_val + period / 2) / period); 2880 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 2881 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 2882 realstathz); 2883 return (0); 2884 } 2885 2886 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0, "Scheduler"); 2887 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0, 2888 "Scheduler name"); 2889 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW, 2890 NULL, 0, sysctl_kern_quantum, "I", 2891 "Quantum for timeshare threads in microseconds"); 2892 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, 2893 "Quantum for timeshare threads in stathz ticks"); 2894 SYSCTL_INT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0, 2895 "Interactivity score threshold"); 2896 SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW, 2897 &preempt_thresh, 0, 2898 "Maximal (lowest) priority for preemption"); 2899 SYSCTL_INT(_kern_sched, OID_AUTO, static_boost, CTLFLAG_RW, &static_boost, 0, 2900 "Assign static kernel priorities to sleeping threads"); 2901 SYSCTL_INT(_kern_sched, OID_AUTO, idlespins, CTLFLAG_RW, &sched_idlespins, 0, 2902 "Number of times idle thread will spin waiting for new work"); 2903 SYSCTL_INT(_kern_sched, OID_AUTO, idlespinthresh, CTLFLAG_RW, 2904 &sched_idlespinthresh, 0, 2905 "Threshold before we will permit idle thread spinning"); 2906 #ifdef SMP 2907 SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0, 2908 "Number of hz ticks to keep thread affinity for"); 2909 SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0, 2910 "Enables the long-term load balancer"); 2911 SYSCTL_INT(_kern_sched, OID_AUTO, balance_interval, CTLFLAG_RW, 2912 &balance_interval, 0, 2913 "Average period in stathz ticks to run the long-term balancer"); 2914 SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0, 2915 "Attempts to steal work from other cores before idling"); 2916 SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0, 2917 "Minimum load on remote CPU before we'll steal"); 2918 SYSCTL_PROC(_kern_sched, OID_AUTO, topology_spec, CTLTYPE_STRING | 2919 CTLFLAG_RD, NULL, 0, sysctl_kern_sched_topology_spec, "A", 2920 "XML dump of detected CPU topology"); 2921 #endif 2922 2923 /* ps compat. All cpu percentages from ULE are weighted. */ 2924 static int ccpu = 0; 2925 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 2926