1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2002-2007, Jeffrey Roberson <jeff@freebsd.org> 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice unmodified, this list of conditions, and the following 12 * disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 /* 30 * This file implements the ULE scheduler. ULE supports independent CPU 31 * run queues and fine grain locking. It has superior interactive 32 * performance under load even on uni-processor systems. 33 * 34 * etymology: 35 * ULE is the last three letters in schedule. It owes its name to a 36 * generic user created for a scheduling system by Paul Mikesell at 37 * Isilon Systems and a general lack of creativity on the part of the author. 38 */ 39 40 #include <sys/cdefs.h> 41 __FBSDID("$FreeBSD$"); 42 43 #include "opt_hwpmc_hooks.h" 44 #include "opt_sched.h" 45 46 #include <sys/param.h> 47 #include <sys/systm.h> 48 #include <sys/kdb.h> 49 #include <sys/kernel.h> 50 #include <sys/ktr.h> 51 #include <sys/limits.h> 52 #include <sys/lock.h> 53 #include <sys/mutex.h> 54 #include <sys/proc.h> 55 #include <sys/resource.h> 56 #include <sys/resourcevar.h> 57 #include <sys/sched.h> 58 #include <sys/sdt.h> 59 #include <sys/smp.h> 60 #include <sys/sx.h> 61 #include <sys/sysctl.h> 62 #include <sys/sysproto.h> 63 #include <sys/turnstile.h> 64 #include <sys/umtx.h> 65 #include <sys/vmmeter.h> 66 #include <sys/cpuset.h> 67 #include <sys/sbuf.h> 68 69 #ifdef HWPMC_HOOKS 70 #include <sys/pmckern.h> 71 #endif 72 73 #ifdef KDTRACE_HOOKS 74 #include <sys/dtrace_bsd.h> 75 int dtrace_vtime_active; 76 dtrace_vtime_switch_func_t dtrace_vtime_switch_func; 77 #endif 78 79 #include <machine/cpu.h> 80 #include <machine/smp.h> 81 82 #define KTR_ULE 0 83 84 #define TS_NAME_LEN (MAXCOMLEN + sizeof(" td ") + sizeof(__XSTRING(UINT_MAX))) 85 #define TDQ_NAME_LEN (sizeof("sched lock ") + sizeof(__XSTRING(MAXCPU))) 86 #define TDQ_LOADNAME_LEN (sizeof("CPU ") + sizeof(__XSTRING(MAXCPU)) - 1 + sizeof(" load")) 87 88 /* 89 * Thread scheduler specific section. All fields are protected 90 * by the thread lock. 91 */ 92 struct td_sched { 93 struct runq *ts_runq; /* Run-queue we're queued on. */ 94 short ts_flags; /* TSF_* flags. */ 95 int ts_cpu; /* CPU that we have affinity for. */ 96 int ts_rltick; /* Real last tick, for affinity. */ 97 int ts_slice; /* Ticks of slice remaining. */ 98 u_int ts_slptime; /* Number of ticks we vol. slept */ 99 u_int ts_runtime; /* Number of ticks we were running */ 100 int ts_ltick; /* Last tick that we were running on */ 101 int ts_ftick; /* First tick that we were running on */ 102 int ts_ticks; /* Tick count */ 103 #ifdef KTR 104 char ts_name[TS_NAME_LEN]; 105 #endif 106 }; 107 /* flags kept in ts_flags */ 108 #define TSF_BOUND 0x0001 /* Thread can not migrate. */ 109 #define TSF_XFERABLE 0x0002 /* Thread was added as transferable. */ 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 _Static_assert(sizeof(struct thread) + sizeof(struct td_sched) <= 116 sizeof(struct thread0_storage), 117 "increase struct thread0_storage.t0st_sched size"); 118 119 /* 120 * Priority ranges used for interactive and non-interactive timeshare 121 * threads. The timeshare priorities are split up into four ranges. 122 * The first range handles interactive threads. The last three ranges 123 * (NHALF, x, and NHALF) handle non-interactive threads with the outer 124 * ranges supporting nice values. 125 */ 126 #define PRI_TIMESHARE_RANGE (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE + 1) 127 #define PRI_INTERACT_RANGE ((PRI_TIMESHARE_RANGE - SCHED_PRI_NRESV) / 2) 128 #define PRI_BATCH_RANGE (PRI_TIMESHARE_RANGE - PRI_INTERACT_RANGE) 129 130 #define PRI_MIN_INTERACT PRI_MIN_TIMESHARE 131 #define PRI_MAX_INTERACT (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE - 1) 132 #define PRI_MIN_BATCH (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE) 133 #define PRI_MAX_BATCH PRI_MAX_TIMESHARE 134 135 /* 136 * Cpu percentage computation macros and defines. 137 * 138 * SCHED_TICK_SECS: Number of seconds to average the cpu usage across. 139 * SCHED_TICK_TARG: Number of hz ticks to average the cpu usage across. 140 * SCHED_TICK_MAX: Maximum number of ticks before scaling back. 141 * SCHED_TICK_SHIFT: Shift factor to avoid rounding away results. 142 * SCHED_TICK_HZ: Compute the number of hz ticks for a given ticks count. 143 * SCHED_TICK_TOTAL: Gives the amount of time we've been recording ticks. 144 */ 145 #define SCHED_TICK_SECS 10 146 #define SCHED_TICK_TARG (hz * SCHED_TICK_SECS) 147 #define SCHED_TICK_MAX (SCHED_TICK_TARG + hz) 148 #define SCHED_TICK_SHIFT 10 149 #define SCHED_TICK_HZ(ts) ((ts)->ts_ticks >> SCHED_TICK_SHIFT) 150 #define SCHED_TICK_TOTAL(ts) (max((ts)->ts_ltick - (ts)->ts_ftick, hz)) 151 152 /* 153 * These macros determine priorities for non-interactive threads. They are 154 * assigned a priority based on their recent cpu utilization as expressed 155 * by the ratio of ticks to the tick total. NHALF priorities at the start 156 * and end of the MIN to MAX timeshare range are only reachable with negative 157 * or positive nice respectively. 158 * 159 * PRI_RANGE: Priority range for utilization dependent priorities. 160 * PRI_NRESV: Number of nice values. 161 * PRI_TICKS: Compute a priority in PRI_RANGE from the ticks count and total. 162 * PRI_NICE: Determines the part of the priority inherited from nice. 163 */ 164 #define SCHED_PRI_NRESV (PRIO_MAX - PRIO_MIN) 165 #define SCHED_PRI_NHALF (SCHED_PRI_NRESV / 2) 166 #define SCHED_PRI_MIN (PRI_MIN_BATCH + SCHED_PRI_NHALF) 167 #define SCHED_PRI_MAX (PRI_MAX_BATCH - SCHED_PRI_NHALF) 168 #define SCHED_PRI_RANGE (SCHED_PRI_MAX - SCHED_PRI_MIN + 1) 169 #define SCHED_PRI_TICKS(ts) \ 170 (SCHED_TICK_HZ((ts)) / \ 171 (roundup(SCHED_TICK_TOTAL((ts)), SCHED_PRI_RANGE) / SCHED_PRI_RANGE)) 172 #define SCHED_PRI_NICE(nice) (nice) 173 174 /* 175 * These determine the interactivity of a process. Interactivity differs from 176 * cpu utilization in that it expresses the voluntary time slept vs time ran 177 * while cpu utilization includes all time not running. This more accurately 178 * models the intent of the thread. 179 * 180 * SLP_RUN_MAX: Maximum amount of sleep time + run time we'll accumulate 181 * before throttling back. 182 * SLP_RUN_FORK: Maximum slp+run time to inherit at fork time. 183 * INTERACT_MAX: Maximum interactivity value. Smaller is better. 184 * INTERACT_THRESH: Threshold for placement on the current runq. 185 */ 186 #define SCHED_SLP_RUN_MAX ((hz * 5) << SCHED_TICK_SHIFT) 187 #define SCHED_SLP_RUN_FORK ((hz / 2) << SCHED_TICK_SHIFT) 188 #define SCHED_INTERACT_MAX (100) 189 #define SCHED_INTERACT_HALF (SCHED_INTERACT_MAX / 2) 190 #define SCHED_INTERACT_THRESH (30) 191 192 /* 193 * These parameters determine the slice behavior for batch work. 194 */ 195 #define SCHED_SLICE_DEFAULT_DIVISOR 10 /* ~94 ms, 12 stathz ticks. */ 196 #define SCHED_SLICE_MIN_DIVISOR 6 /* DEFAULT/MIN = ~16 ms. */ 197 198 /* Flags kept in td_flags. */ 199 #define TDF_SLICEEND TDF_SCHED2 /* Thread time slice is over. */ 200 201 /* 202 * tickincr: Converts a stathz tick into a hz domain scaled by 203 * the shift factor. Without the shift the error rate 204 * due to rounding would be unacceptably high. 205 * realstathz: stathz is sometimes 0 and run off of hz. 206 * sched_slice: Runtime of each thread before rescheduling. 207 * preempt_thresh: Priority threshold for preemption and remote IPIs. 208 */ 209 static int sched_interact = SCHED_INTERACT_THRESH; 210 static int tickincr = 8 << SCHED_TICK_SHIFT; 211 static int realstathz = 127; /* reset during boot. */ 212 static int sched_slice = 10; /* reset during boot. */ 213 static int sched_slice_min = 1; /* reset during boot. */ 214 #ifdef PREEMPTION 215 #ifdef FULL_PREEMPTION 216 static int preempt_thresh = PRI_MAX_IDLE; 217 #else 218 static int preempt_thresh = PRI_MIN_KERN; 219 #endif 220 #else 221 static int preempt_thresh = 0; 222 #endif 223 static int static_boost = PRI_MIN_BATCH; 224 static int sched_idlespins = 10000; 225 static int sched_idlespinthresh = -1; 226 227 /* 228 * tdq - per processor runqs and statistics. All fields are protected by the 229 * tdq_lock. The load and lowpri may be accessed without to avoid excess 230 * locking in sched_pickcpu(); 231 */ 232 struct tdq { 233 /* 234 * Ordered to improve efficiency of cpu_search() and switch(). 235 * tdq_lock is padded to avoid false sharing with tdq_load and 236 * tdq_cpu_idle. 237 */ 238 struct mtx_padalign tdq_lock; /* run queue lock. */ 239 struct cpu_group *tdq_cg; /* Pointer to cpu topology. */ 240 volatile int tdq_load; /* Aggregate load. */ 241 volatile int tdq_cpu_idle; /* cpu_idle() is active. */ 242 int tdq_sysload; /* For loadavg, !ITHD load. */ 243 volatile int tdq_transferable; /* Transferable thread count. */ 244 volatile short tdq_switchcnt; /* Switches this tick. */ 245 volatile short tdq_oldswitchcnt; /* Switches last tick. */ 246 u_char tdq_lowpri; /* Lowest priority thread. */ 247 u_char tdq_ipipending; /* IPI pending. */ 248 u_char tdq_idx; /* Current insert index. */ 249 u_char tdq_ridx; /* Current removal index. */ 250 int tdq_id; /* cpuid. */ 251 struct runq tdq_realtime; /* real-time run queue. */ 252 struct runq tdq_timeshare; /* timeshare run queue. */ 253 struct runq tdq_idle; /* Queue of IDLE threads. */ 254 char tdq_name[TDQ_NAME_LEN]; 255 #ifdef KTR 256 char tdq_loadname[TDQ_LOADNAME_LEN]; 257 #endif 258 } __aligned(64); 259 260 /* Idle thread states and config. */ 261 #define TDQ_RUNNING 1 262 #define TDQ_IDLE 2 263 264 #ifdef SMP 265 struct cpu_group *cpu_top; /* CPU topology */ 266 267 #define SCHED_AFFINITY_DEFAULT (max(1, hz / 1000)) 268 #define SCHED_AFFINITY(ts, t) ((ts)->ts_rltick > ticks - ((t) * affinity)) 269 270 /* 271 * Run-time tunables. 272 */ 273 static int rebalance = 1; 274 static int balance_interval = 128; /* Default set in sched_initticks(). */ 275 static int affinity; 276 static int steal_idle = 1; 277 static int steal_thresh = 2; 278 static int always_steal = 0; 279 static int trysteal_limit = 2; 280 281 /* 282 * One thread queue per processor. 283 */ 284 static struct tdq *balance_tdq; 285 static int balance_ticks; 286 DPCPU_DEFINE_STATIC(struct tdq, tdq); 287 DPCPU_DEFINE_STATIC(uint32_t, randomval); 288 289 #define TDQ_SELF() ((struct tdq *)PCPU_GET(sched)) 290 #define TDQ_CPU(x) (DPCPU_ID_PTR((x), tdq)) 291 #define TDQ_ID(x) ((x)->tdq_id) 292 #else /* !SMP */ 293 static struct tdq tdq_cpu; 294 295 #define TDQ_ID(x) (0) 296 #define TDQ_SELF() (&tdq_cpu) 297 #define TDQ_CPU(x) (&tdq_cpu) 298 #endif 299 300 #define TDQ_LOCK_ASSERT(t, type) mtx_assert(TDQ_LOCKPTR((t)), (type)) 301 #define TDQ_LOCK(t) mtx_lock_spin(TDQ_LOCKPTR((t))) 302 #define TDQ_LOCK_FLAGS(t, f) mtx_lock_spin_flags(TDQ_LOCKPTR((t)), (f)) 303 #define TDQ_UNLOCK(t) mtx_unlock_spin(TDQ_LOCKPTR((t))) 304 #define TDQ_LOCKPTR(t) ((struct mtx *)(&(t)->tdq_lock)) 305 306 static void sched_priority(struct thread *); 307 static void sched_thread_priority(struct thread *, u_char); 308 static int sched_interact_score(struct thread *); 309 static void sched_interact_update(struct thread *); 310 static void sched_interact_fork(struct thread *); 311 static void sched_pctcpu_update(struct td_sched *, int); 312 313 /* Operations on per processor queues */ 314 static struct thread *tdq_choose(struct tdq *); 315 static void tdq_setup(struct tdq *, int i); 316 static void tdq_load_add(struct tdq *, struct thread *); 317 static void tdq_load_rem(struct tdq *, struct thread *); 318 static __inline void tdq_runq_add(struct tdq *, struct thread *, int); 319 static __inline void tdq_runq_rem(struct tdq *, struct thread *); 320 static inline int sched_shouldpreempt(int, int, int); 321 void tdq_print(int cpu); 322 static void runq_print(struct runq *rq); 323 static void tdq_add(struct tdq *, struct thread *, int); 324 #ifdef SMP 325 static struct thread *tdq_move(struct tdq *, struct tdq *); 326 static int tdq_idled(struct tdq *); 327 static void tdq_notify(struct tdq *, struct thread *); 328 static struct thread *tdq_steal(struct tdq *, int); 329 static struct thread *runq_steal(struct runq *, int); 330 static int sched_pickcpu(struct thread *, int); 331 static void sched_balance(void); 332 static int sched_balance_pair(struct tdq *, struct tdq *); 333 static inline struct tdq *sched_setcpu(struct thread *, int, int); 334 static inline void thread_unblock_switch(struct thread *, struct mtx *); 335 static struct mtx *sched_switch_migrate(struct tdq *, struct thread *, int); 336 static int sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS); 337 static int sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, 338 struct cpu_group *cg, int indent); 339 #endif 340 341 static void sched_setup(void *dummy); 342 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL); 343 344 static void sched_initticks(void *dummy); 345 SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks, 346 NULL); 347 348 SDT_PROVIDER_DEFINE(sched); 349 350 SDT_PROBE_DEFINE3(sched, , , change__pri, "struct thread *", 351 "struct proc *", "uint8_t"); 352 SDT_PROBE_DEFINE3(sched, , , dequeue, "struct thread *", 353 "struct proc *", "void *"); 354 SDT_PROBE_DEFINE4(sched, , , enqueue, "struct thread *", 355 "struct proc *", "void *", "int"); 356 SDT_PROBE_DEFINE4(sched, , , lend__pri, "struct thread *", 357 "struct proc *", "uint8_t", "struct thread *"); 358 SDT_PROBE_DEFINE2(sched, , , load__change, "int", "int"); 359 SDT_PROBE_DEFINE2(sched, , , off__cpu, "struct thread *", 360 "struct proc *"); 361 SDT_PROBE_DEFINE(sched, , , on__cpu); 362 SDT_PROBE_DEFINE(sched, , , remain__cpu); 363 SDT_PROBE_DEFINE2(sched, , , surrender, "struct thread *", 364 "struct proc *"); 365 366 /* 367 * Print the threads waiting on a run-queue. 368 */ 369 static void 370 runq_print(struct runq *rq) 371 { 372 struct rqhead *rqh; 373 struct thread *td; 374 int pri; 375 int j; 376 int i; 377 378 for (i = 0; i < RQB_LEN; i++) { 379 printf("\t\trunq bits %d 0x%zx\n", 380 i, rq->rq_status.rqb_bits[i]); 381 for (j = 0; j < RQB_BPW; j++) 382 if (rq->rq_status.rqb_bits[i] & (1ul << j)) { 383 pri = j + (i << RQB_L2BPW); 384 rqh = &rq->rq_queues[pri]; 385 TAILQ_FOREACH(td, rqh, td_runq) { 386 printf("\t\t\ttd %p(%s) priority %d rqindex %d pri %d\n", 387 td, td->td_name, td->td_priority, 388 td->td_rqindex, pri); 389 } 390 } 391 } 392 } 393 394 /* 395 * Print the status of a per-cpu thread queue. Should be a ddb show cmd. 396 */ 397 void 398 tdq_print(int cpu) 399 { 400 struct tdq *tdq; 401 402 tdq = TDQ_CPU(cpu); 403 404 printf("tdq %d:\n", TDQ_ID(tdq)); 405 printf("\tlock %p\n", TDQ_LOCKPTR(tdq)); 406 printf("\tLock name: %s\n", tdq->tdq_name); 407 printf("\tload: %d\n", tdq->tdq_load); 408 printf("\tswitch cnt: %d\n", tdq->tdq_switchcnt); 409 printf("\told switch cnt: %d\n", tdq->tdq_oldswitchcnt); 410 printf("\ttimeshare idx: %d\n", tdq->tdq_idx); 411 printf("\ttimeshare ridx: %d\n", tdq->tdq_ridx); 412 printf("\tload transferable: %d\n", tdq->tdq_transferable); 413 printf("\tlowest priority: %d\n", tdq->tdq_lowpri); 414 printf("\trealtime runq:\n"); 415 runq_print(&tdq->tdq_realtime); 416 printf("\ttimeshare runq:\n"); 417 runq_print(&tdq->tdq_timeshare); 418 printf("\tidle runq:\n"); 419 runq_print(&tdq->tdq_idle); 420 } 421 422 static inline int 423 sched_shouldpreempt(int pri, int cpri, int remote) 424 { 425 /* 426 * If the new priority is not better than the current priority there is 427 * nothing to do. 428 */ 429 if (pri >= cpri) 430 return (0); 431 /* 432 * Always preempt idle. 433 */ 434 if (cpri >= PRI_MIN_IDLE) 435 return (1); 436 /* 437 * If preemption is disabled don't preempt others. 438 */ 439 if (preempt_thresh == 0) 440 return (0); 441 /* 442 * Preempt if we exceed the threshold. 443 */ 444 if (pri <= preempt_thresh) 445 return (1); 446 /* 447 * If we're interactive or better and there is non-interactive 448 * or worse running preempt only remote processors. 449 */ 450 if (remote && pri <= PRI_MAX_INTERACT && cpri > PRI_MAX_INTERACT) 451 return (1); 452 return (0); 453 } 454 455 /* 456 * Add a thread to the actual run-queue. Keeps transferable counts up to 457 * date with what is actually on the run-queue. Selects the correct 458 * queue position for timeshare threads. 459 */ 460 static __inline void 461 tdq_runq_add(struct tdq *tdq, struct thread *td, int flags) 462 { 463 struct td_sched *ts; 464 u_char pri; 465 466 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 467 THREAD_LOCK_ASSERT(td, MA_OWNED); 468 469 pri = td->td_priority; 470 ts = td_get_sched(td); 471 TD_SET_RUNQ(td); 472 if (THREAD_CAN_MIGRATE(td)) { 473 tdq->tdq_transferable++; 474 ts->ts_flags |= TSF_XFERABLE; 475 } 476 if (pri < PRI_MIN_BATCH) { 477 ts->ts_runq = &tdq->tdq_realtime; 478 } else if (pri <= PRI_MAX_BATCH) { 479 ts->ts_runq = &tdq->tdq_timeshare; 480 KASSERT(pri <= PRI_MAX_BATCH && pri >= PRI_MIN_BATCH, 481 ("Invalid priority %d on timeshare runq", pri)); 482 /* 483 * This queue contains only priorities between MIN and MAX 484 * realtime. Use the whole queue to represent these values. 485 */ 486 if ((flags & (SRQ_BORROWING|SRQ_PREEMPTED)) == 0) { 487 pri = RQ_NQS * (pri - PRI_MIN_BATCH) / PRI_BATCH_RANGE; 488 pri = (pri + tdq->tdq_idx) % RQ_NQS; 489 /* 490 * This effectively shortens the queue by one so we 491 * can have a one slot difference between idx and 492 * ridx while we wait for threads to drain. 493 */ 494 if (tdq->tdq_ridx != tdq->tdq_idx && 495 pri == tdq->tdq_ridx) 496 pri = (unsigned char)(pri - 1) % RQ_NQS; 497 } else 498 pri = tdq->tdq_ridx; 499 runq_add_pri(ts->ts_runq, td, pri, flags); 500 return; 501 } else 502 ts->ts_runq = &tdq->tdq_idle; 503 runq_add(ts->ts_runq, td, flags); 504 } 505 506 /* 507 * Remove a thread from a run-queue. This typically happens when a thread 508 * is selected to run. Running threads are not on the queue and the 509 * transferable count does not reflect them. 510 */ 511 static __inline void 512 tdq_runq_rem(struct tdq *tdq, struct thread *td) 513 { 514 struct td_sched *ts; 515 516 ts = td_get_sched(td); 517 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 518 KASSERT(ts->ts_runq != NULL, 519 ("tdq_runq_remove: thread %p null ts_runq", td)); 520 if (ts->ts_flags & TSF_XFERABLE) { 521 tdq->tdq_transferable--; 522 ts->ts_flags &= ~TSF_XFERABLE; 523 } 524 if (ts->ts_runq == &tdq->tdq_timeshare) { 525 if (tdq->tdq_idx != tdq->tdq_ridx) 526 runq_remove_idx(ts->ts_runq, td, &tdq->tdq_ridx); 527 else 528 runq_remove_idx(ts->ts_runq, td, NULL); 529 } else 530 runq_remove(ts->ts_runq, td); 531 } 532 533 /* 534 * Load is maintained for all threads RUNNING and ON_RUNQ. Add the load 535 * for this thread to the referenced thread queue. 536 */ 537 static void 538 tdq_load_add(struct tdq *tdq, struct thread *td) 539 { 540 541 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 542 THREAD_LOCK_ASSERT(td, MA_OWNED); 543 544 tdq->tdq_load++; 545 if ((td->td_flags & TDF_NOLOAD) == 0) 546 tdq->tdq_sysload++; 547 KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load); 548 SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load); 549 } 550 551 /* 552 * Remove the load from a thread that is transitioning to a sleep state or 553 * exiting. 554 */ 555 static void 556 tdq_load_rem(struct tdq *tdq, struct thread *td) 557 { 558 559 THREAD_LOCK_ASSERT(td, MA_OWNED); 560 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 561 KASSERT(tdq->tdq_load != 0, 562 ("tdq_load_rem: Removing with 0 load on queue %d", TDQ_ID(tdq))); 563 564 tdq->tdq_load--; 565 if ((td->td_flags & TDF_NOLOAD) == 0) 566 tdq->tdq_sysload--; 567 KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load); 568 SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load); 569 } 570 571 /* 572 * Bound timeshare latency by decreasing slice size as load increases. We 573 * consider the maximum latency as the sum of the threads waiting to run 574 * aside from curthread and target no more than sched_slice latency but 575 * no less than sched_slice_min runtime. 576 */ 577 static inline int 578 tdq_slice(struct tdq *tdq) 579 { 580 int load; 581 582 /* 583 * It is safe to use sys_load here because this is called from 584 * contexts where timeshare threads are running and so there 585 * cannot be higher priority load in the system. 586 */ 587 load = tdq->tdq_sysload - 1; 588 if (load >= SCHED_SLICE_MIN_DIVISOR) 589 return (sched_slice_min); 590 if (load <= 1) 591 return (sched_slice); 592 return (sched_slice / load); 593 } 594 595 /* 596 * Set lowpri to its exact value by searching the run-queue and 597 * evaluating curthread. curthread may be passed as an optimization. 598 */ 599 static void 600 tdq_setlowpri(struct tdq *tdq, struct thread *ctd) 601 { 602 struct thread *td; 603 604 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 605 if (ctd == NULL) 606 ctd = pcpu_find(TDQ_ID(tdq))->pc_curthread; 607 td = tdq_choose(tdq); 608 if (td == NULL || td->td_priority > ctd->td_priority) 609 tdq->tdq_lowpri = ctd->td_priority; 610 else 611 tdq->tdq_lowpri = td->td_priority; 612 } 613 614 #ifdef SMP 615 /* 616 * We need some randomness. Implement a classic Linear Congruential 617 * Generator X_{n+1}=(aX_n+c) mod m. These values are optimized for 618 * m = 2^32, a = 69069 and c = 5. We only return the upper 16 bits 619 * of the random state (in the low bits of our answer) to keep 620 * the maximum randomness. 621 */ 622 static uint32_t 623 sched_random(void) 624 { 625 uint32_t *rndptr; 626 627 rndptr = DPCPU_PTR(randomval); 628 *rndptr = *rndptr * 69069 + 5; 629 630 return (*rndptr >> 16); 631 } 632 633 struct cpu_search { 634 cpuset_t cs_mask; 635 u_int cs_prefer; 636 int cs_pri; /* Min priority for low. */ 637 int cs_limit; /* Max load for low, min load for high. */ 638 int cs_cpu; 639 int cs_load; 640 }; 641 642 #define CPU_SEARCH_LOWEST 0x1 643 #define CPU_SEARCH_HIGHEST 0x2 644 #define CPU_SEARCH_BOTH (CPU_SEARCH_LOWEST|CPU_SEARCH_HIGHEST) 645 646 #define CPUSET_FOREACH(cpu, mask) \ 647 for ((cpu) = 0; (cpu) <= mp_maxid; (cpu)++) \ 648 if (CPU_ISSET(cpu, &mask)) 649 650 static __always_inline int cpu_search(const struct cpu_group *cg, 651 struct cpu_search *low, struct cpu_search *high, const int match); 652 int __noinline cpu_search_lowest(const struct cpu_group *cg, 653 struct cpu_search *low); 654 int __noinline cpu_search_highest(const struct cpu_group *cg, 655 struct cpu_search *high); 656 int __noinline cpu_search_both(const struct cpu_group *cg, 657 struct cpu_search *low, struct cpu_search *high); 658 659 /* 660 * Search the tree of cpu_groups for the lowest or highest loaded cpu 661 * according to the match argument. This routine actually compares the 662 * load on all paths through the tree and finds the least loaded cpu on 663 * the least loaded path, which may differ from the least loaded cpu in 664 * the system. This balances work among caches and buses. 665 * 666 * This inline is instantiated in three forms below using constants for the 667 * match argument. It is reduced to the minimum set for each case. It is 668 * also recursive to the depth of the tree. 669 */ 670 static __always_inline int 671 cpu_search(const struct cpu_group *cg, struct cpu_search *low, 672 struct cpu_search *high, const int match) 673 { 674 struct cpu_search lgroup; 675 struct cpu_search hgroup; 676 cpuset_t cpumask; 677 struct cpu_group *child; 678 struct tdq *tdq; 679 int cpu, i, hload, lload, load, total, rnd; 680 681 total = 0; 682 cpumask = cg->cg_mask; 683 if (match & CPU_SEARCH_LOWEST) { 684 lload = INT_MAX; 685 lgroup = *low; 686 } 687 if (match & CPU_SEARCH_HIGHEST) { 688 hload = INT_MIN; 689 hgroup = *high; 690 } 691 692 /* Iterate through the child CPU groups and then remaining CPUs. */ 693 for (i = cg->cg_children, cpu = mp_maxid; ; ) { 694 if (i == 0) { 695 #ifdef HAVE_INLINE_FFSL 696 cpu = CPU_FFS(&cpumask) - 1; 697 #else 698 while (cpu >= 0 && !CPU_ISSET(cpu, &cpumask)) 699 cpu--; 700 #endif 701 if (cpu < 0) 702 break; 703 child = NULL; 704 } else 705 child = &cg->cg_child[i - 1]; 706 707 if (match & CPU_SEARCH_LOWEST) 708 lgroup.cs_cpu = -1; 709 if (match & CPU_SEARCH_HIGHEST) 710 hgroup.cs_cpu = -1; 711 if (child) { /* Handle child CPU group. */ 712 CPU_NAND(&cpumask, &child->cg_mask); 713 switch (match) { 714 case CPU_SEARCH_LOWEST: 715 load = cpu_search_lowest(child, &lgroup); 716 break; 717 case CPU_SEARCH_HIGHEST: 718 load = cpu_search_highest(child, &hgroup); 719 break; 720 case CPU_SEARCH_BOTH: 721 load = cpu_search_both(child, &lgroup, &hgroup); 722 break; 723 } 724 } else { /* Handle child CPU. */ 725 CPU_CLR(cpu, &cpumask); 726 tdq = TDQ_CPU(cpu); 727 load = tdq->tdq_load * 256; 728 rnd = sched_random() % 32; 729 if (match & CPU_SEARCH_LOWEST) { 730 if (cpu == low->cs_prefer) 731 load -= 64; 732 /* If that CPU is allowed and get data. */ 733 if (tdq->tdq_lowpri > lgroup.cs_pri && 734 tdq->tdq_load <= lgroup.cs_limit && 735 CPU_ISSET(cpu, &lgroup.cs_mask)) { 736 lgroup.cs_cpu = cpu; 737 lgroup.cs_load = load - rnd; 738 } 739 } 740 if (match & CPU_SEARCH_HIGHEST) 741 if (tdq->tdq_load >= hgroup.cs_limit && 742 tdq->tdq_transferable && 743 CPU_ISSET(cpu, &hgroup.cs_mask)) { 744 hgroup.cs_cpu = cpu; 745 hgroup.cs_load = load - rnd; 746 } 747 } 748 total += load; 749 750 /* We have info about child item. Compare it. */ 751 if (match & CPU_SEARCH_LOWEST) { 752 if (lgroup.cs_cpu >= 0 && 753 (load < lload || 754 (load == lload && lgroup.cs_load < low->cs_load))) { 755 lload = load; 756 low->cs_cpu = lgroup.cs_cpu; 757 low->cs_load = lgroup.cs_load; 758 } 759 } 760 if (match & CPU_SEARCH_HIGHEST) 761 if (hgroup.cs_cpu >= 0 && 762 (load > hload || 763 (load == hload && hgroup.cs_load > high->cs_load))) { 764 hload = load; 765 high->cs_cpu = hgroup.cs_cpu; 766 high->cs_load = hgroup.cs_load; 767 } 768 if (child) { 769 i--; 770 if (i == 0 && CPU_EMPTY(&cpumask)) 771 break; 772 } 773 #ifndef HAVE_INLINE_FFSL 774 else 775 cpu--; 776 #endif 777 } 778 return (total); 779 } 780 781 /* 782 * cpu_search instantiations must pass constants to maintain the inline 783 * optimization. 784 */ 785 int 786 cpu_search_lowest(const struct cpu_group *cg, struct cpu_search *low) 787 { 788 return cpu_search(cg, low, NULL, CPU_SEARCH_LOWEST); 789 } 790 791 int 792 cpu_search_highest(const struct cpu_group *cg, struct cpu_search *high) 793 { 794 return cpu_search(cg, NULL, high, CPU_SEARCH_HIGHEST); 795 } 796 797 int 798 cpu_search_both(const struct cpu_group *cg, struct cpu_search *low, 799 struct cpu_search *high) 800 { 801 return cpu_search(cg, low, high, CPU_SEARCH_BOTH); 802 } 803 804 /* 805 * Find the cpu with the least load via the least loaded path that has a 806 * lowpri greater than pri pri. A pri of -1 indicates any priority is 807 * acceptable. 808 */ 809 static inline int 810 sched_lowest(const struct cpu_group *cg, cpuset_t mask, int pri, int maxload, 811 int prefer) 812 { 813 struct cpu_search low; 814 815 low.cs_cpu = -1; 816 low.cs_prefer = prefer; 817 low.cs_mask = mask; 818 low.cs_pri = pri; 819 low.cs_limit = maxload; 820 cpu_search_lowest(cg, &low); 821 return low.cs_cpu; 822 } 823 824 /* 825 * Find the cpu with the highest load via the highest loaded path. 826 */ 827 static inline int 828 sched_highest(const struct cpu_group *cg, cpuset_t mask, int minload) 829 { 830 struct cpu_search high; 831 832 high.cs_cpu = -1; 833 high.cs_mask = mask; 834 high.cs_limit = minload; 835 cpu_search_highest(cg, &high); 836 return high.cs_cpu; 837 } 838 839 static void 840 sched_balance_group(struct cpu_group *cg) 841 { 842 struct tdq *tdq; 843 cpuset_t hmask, lmask; 844 int high, low, anylow; 845 846 CPU_FILL(&hmask); 847 for (;;) { 848 high = sched_highest(cg, hmask, 2); 849 /* Stop if there is no more CPU with transferrable threads. */ 850 if (high == -1) 851 break; 852 CPU_CLR(high, &hmask); 853 CPU_COPY(&hmask, &lmask); 854 /* Stop if there is no more CPU left for low. */ 855 if (CPU_EMPTY(&lmask)) 856 break; 857 anylow = 1; 858 tdq = TDQ_CPU(high); 859 nextlow: 860 low = sched_lowest(cg, lmask, -1, tdq->tdq_load - 1, high); 861 /* Stop if we looked well and found no less loaded CPU. */ 862 if (anylow && low == -1) 863 break; 864 /* Go to next high if we found no less loaded CPU. */ 865 if (low == -1) 866 continue; 867 /* Transfer thread from high to low. */ 868 if (sched_balance_pair(tdq, TDQ_CPU(low))) { 869 /* CPU that got thread can no longer be a donor. */ 870 CPU_CLR(low, &hmask); 871 } else { 872 /* 873 * If failed, then there is no threads on high 874 * that can run on this low. Drop low from low 875 * mask and look for different one. 876 */ 877 CPU_CLR(low, &lmask); 878 anylow = 0; 879 goto nextlow; 880 } 881 } 882 } 883 884 static void 885 sched_balance(void) 886 { 887 struct tdq *tdq; 888 889 balance_ticks = max(balance_interval / 2, 1) + 890 (sched_random() % balance_interval); 891 tdq = TDQ_SELF(); 892 TDQ_UNLOCK(tdq); 893 sched_balance_group(cpu_top); 894 TDQ_LOCK(tdq); 895 } 896 897 /* 898 * Lock two thread queues using their address to maintain lock order. 899 */ 900 static void 901 tdq_lock_pair(struct tdq *one, struct tdq *two) 902 { 903 if (one < two) { 904 TDQ_LOCK(one); 905 TDQ_LOCK_FLAGS(two, MTX_DUPOK); 906 } else { 907 TDQ_LOCK(two); 908 TDQ_LOCK_FLAGS(one, MTX_DUPOK); 909 } 910 } 911 912 /* 913 * Unlock two thread queues. Order is not important here. 914 */ 915 static void 916 tdq_unlock_pair(struct tdq *one, struct tdq *two) 917 { 918 TDQ_UNLOCK(one); 919 TDQ_UNLOCK(two); 920 } 921 922 /* 923 * Transfer load between two imbalanced thread queues. 924 */ 925 static int 926 sched_balance_pair(struct tdq *high, struct tdq *low) 927 { 928 struct thread *td; 929 int cpu; 930 931 tdq_lock_pair(high, low); 932 td = NULL; 933 /* 934 * Transfer a thread from high to low. 935 */ 936 if (high->tdq_transferable != 0 && high->tdq_load > low->tdq_load && 937 (td = tdq_move(high, low)) != NULL) { 938 /* 939 * In case the target isn't the current cpu notify it of the 940 * new load, possibly sending an IPI to force it to reschedule. 941 */ 942 cpu = TDQ_ID(low); 943 if (cpu != PCPU_GET(cpuid)) 944 tdq_notify(low, td); 945 } 946 tdq_unlock_pair(high, low); 947 return (td != NULL); 948 } 949 950 /* 951 * Move a thread from one thread queue to another. 952 */ 953 static struct thread * 954 tdq_move(struct tdq *from, struct tdq *to) 955 { 956 struct td_sched *ts; 957 struct thread *td; 958 struct tdq *tdq; 959 int cpu; 960 961 TDQ_LOCK_ASSERT(from, MA_OWNED); 962 TDQ_LOCK_ASSERT(to, MA_OWNED); 963 964 tdq = from; 965 cpu = TDQ_ID(to); 966 td = tdq_steal(tdq, cpu); 967 if (td == NULL) 968 return (NULL); 969 ts = td_get_sched(td); 970 /* 971 * Although the run queue is locked the thread may be blocked. Lock 972 * it to clear this and acquire the run-queue lock. 973 */ 974 thread_lock(td); 975 /* Drop recursive lock on from acquired via thread_lock(). */ 976 TDQ_UNLOCK(from); 977 sched_rem(td); 978 ts->ts_cpu = cpu; 979 td->td_lock = TDQ_LOCKPTR(to); 980 tdq_add(to, td, SRQ_YIELDING); 981 return (td); 982 } 983 984 /* 985 * This tdq has idled. Try to steal a thread from another cpu and switch 986 * to it. 987 */ 988 static int 989 tdq_idled(struct tdq *tdq) 990 { 991 struct cpu_group *cg; 992 struct tdq *steal; 993 cpuset_t mask; 994 int cpu, switchcnt; 995 996 if (smp_started == 0 || steal_idle == 0 || tdq->tdq_cg == NULL) 997 return (1); 998 CPU_FILL(&mask); 999 CPU_CLR(PCPU_GET(cpuid), &mask); 1000 restart: 1001 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 1002 for (cg = tdq->tdq_cg; ; ) { 1003 cpu = sched_highest(cg, mask, steal_thresh); 1004 /* 1005 * We were assigned a thread but not preempted. Returning 1006 * 0 here will cause our caller to switch to it. 1007 */ 1008 if (tdq->tdq_load) 1009 return (0); 1010 if (cpu == -1) { 1011 cg = cg->cg_parent; 1012 if (cg == NULL) 1013 return (1); 1014 continue; 1015 } 1016 steal = TDQ_CPU(cpu); 1017 /* 1018 * The data returned by sched_highest() is stale and 1019 * the chosen CPU no longer has an eligible thread. 1020 * 1021 * Testing this ahead of tdq_lock_pair() only catches 1022 * this situation about 20% of the time on an 8 core 1023 * 16 thread Ryzen 7, but it still helps performance. 1024 */ 1025 if (steal->tdq_load < steal_thresh || 1026 steal->tdq_transferable == 0) 1027 goto restart; 1028 tdq_lock_pair(tdq, steal); 1029 /* 1030 * We were assigned a thread while waiting for the locks. 1031 * Switch to it now instead of stealing a thread. 1032 */ 1033 if (tdq->tdq_load) 1034 break; 1035 /* 1036 * The data returned by sched_highest() is stale and 1037 * the chosen CPU no longer has an eligible thread, or 1038 * we were preempted and the CPU loading info may be out 1039 * of date. The latter is rare. In either case restart 1040 * the search. 1041 */ 1042 if (steal->tdq_load < steal_thresh || 1043 steal->tdq_transferable == 0 || 1044 switchcnt != tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt) { 1045 tdq_unlock_pair(tdq, steal); 1046 goto restart; 1047 } 1048 /* 1049 * Steal the thread and switch to it. 1050 */ 1051 if (tdq_move(steal, tdq) != NULL) 1052 break; 1053 /* 1054 * We failed to acquire a thread even though it looked 1055 * like one was available. This could be due to affinity 1056 * restrictions or for other reasons. Loop again after 1057 * removing this CPU from the set. The restart logic 1058 * above does not restore this CPU to the set due to the 1059 * likelyhood of failing here again. 1060 */ 1061 CPU_CLR(cpu, &mask); 1062 tdq_unlock_pair(tdq, steal); 1063 } 1064 TDQ_UNLOCK(steal); 1065 mi_switch(SW_VOL | SWT_IDLE, NULL); 1066 thread_unlock(curthread); 1067 return (0); 1068 } 1069 1070 /* 1071 * Notify a remote cpu of new work. Sends an IPI if criteria are met. 1072 */ 1073 static void 1074 tdq_notify(struct tdq *tdq, struct thread *td) 1075 { 1076 struct thread *ctd; 1077 int pri; 1078 int cpu; 1079 1080 if (tdq->tdq_ipipending) 1081 return; 1082 cpu = td_get_sched(td)->ts_cpu; 1083 pri = td->td_priority; 1084 ctd = pcpu_find(cpu)->pc_curthread; 1085 if (!sched_shouldpreempt(pri, ctd->td_priority, 1)) 1086 return; 1087 1088 /* 1089 * Make sure that our caller's earlier update to tdq_load is 1090 * globally visible before we read tdq_cpu_idle. Idle thread 1091 * accesses both of them without locks, and the order is important. 1092 */ 1093 atomic_thread_fence_seq_cst(); 1094 1095 if (TD_IS_IDLETHREAD(ctd)) { 1096 /* 1097 * If the MD code has an idle wakeup routine try that before 1098 * falling back to IPI. 1099 */ 1100 if (!tdq->tdq_cpu_idle || cpu_idle_wakeup(cpu)) 1101 return; 1102 } 1103 tdq->tdq_ipipending = 1; 1104 ipi_cpu(cpu, IPI_PREEMPT); 1105 } 1106 1107 /* 1108 * Steals load from a timeshare queue. Honors the rotating queue head 1109 * index. 1110 */ 1111 static struct thread * 1112 runq_steal_from(struct runq *rq, int cpu, u_char start) 1113 { 1114 struct rqbits *rqb; 1115 struct rqhead *rqh; 1116 struct thread *td, *first; 1117 int bit; 1118 int i; 1119 1120 rqb = &rq->rq_status; 1121 bit = start & (RQB_BPW -1); 1122 first = NULL; 1123 again: 1124 for (i = RQB_WORD(start); i < RQB_LEN; bit = 0, i++) { 1125 if (rqb->rqb_bits[i] == 0) 1126 continue; 1127 if (bit == 0) 1128 bit = RQB_FFS(rqb->rqb_bits[i]); 1129 for (; bit < RQB_BPW; bit++) { 1130 if ((rqb->rqb_bits[i] & (1ul << bit)) == 0) 1131 continue; 1132 rqh = &rq->rq_queues[bit + (i << RQB_L2BPW)]; 1133 TAILQ_FOREACH(td, rqh, td_runq) { 1134 if (first && THREAD_CAN_MIGRATE(td) && 1135 THREAD_CAN_SCHED(td, cpu)) 1136 return (td); 1137 first = td; 1138 } 1139 } 1140 } 1141 if (start != 0) { 1142 start = 0; 1143 goto again; 1144 } 1145 1146 if (first && THREAD_CAN_MIGRATE(first) && 1147 THREAD_CAN_SCHED(first, cpu)) 1148 return (first); 1149 return (NULL); 1150 } 1151 1152 /* 1153 * Steals load from a standard linear queue. 1154 */ 1155 static struct thread * 1156 runq_steal(struct runq *rq, int cpu) 1157 { 1158 struct rqhead *rqh; 1159 struct rqbits *rqb; 1160 struct thread *td; 1161 int word; 1162 int bit; 1163 1164 rqb = &rq->rq_status; 1165 for (word = 0; word < RQB_LEN; word++) { 1166 if (rqb->rqb_bits[word] == 0) 1167 continue; 1168 for (bit = 0; bit < RQB_BPW; bit++) { 1169 if ((rqb->rqb_bits[word] & (1ul << bit)) == 0) 1170 continue; 1171 rqh = &rq->rq_queues[bit + (word << RQB_L2BPW)]; 1172 TAILQ_FOREACH(td, rqh, td_runq) 1173 if (THREAD_CAN_MIGRATE(td) && 1174 THREAD_CAN_SCHED(td, cpu)) 1175 return (td); 1176 } 1177 } 1178 return (NULL); 1179 } 1180 1181 /* 1182 * Attempt to steal a thread in priority order from a thread queue. 1183 */ 1184 static struct thread * 1185 tdq_steal(struct tdq *tdq, int cpu) 1186 { 1187 struct thread *td; 1188 1189 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1190 if ((td = runq_steal(&tdq->tdq_realtime, cpu)) != NULL) 1191 return (td); 1192 if ((td = runq_steal_from(&tdq->tdq_timeshare, 1193 cpu, tdq->tdq_ridx)) != NULL) 1194 return (td); 1195 return (runq_steal(&tdq->tdq_idle, cpu)); 1196 } 1197 1198 /* 1199 * Sets the thread lock and ts_cpu to match the requested cpu. Unlocks the 1200 * current lock and returns with the assigned queue locked. 1201 */ 1202 static inline struct tdq * 1203 sched_setcpu(struct thread *td, int cpu, int flags) 1204 { 1205 1206 struct tdq *tdq; 1207 1208 THREAD_LOCK_ASSERT(td, MA_OWNED); 1209 tdq = TDQ_CPU(cpu); 1210 td_get_sched(td)->ts_cpu = cpu; 1211 /* 1212 * If the lock matches just return the queue. 1213 */ 1214 if (td->td_lock == TDQ_LOCKPTR(tdq)) 1215 return (tdq); 1216 #ifdef notyet 1217 /* 1218 * If the thread isn't running its lockptr is a 1219 * turnstile or a sleepqueue. We can just lock_set without 1220 * blocking. 1221 */ 1222 if (TD_CAN_RUN(td)) { 1223 TDQ_LOCK(tdq); 1224 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 1225 return (tdq); 1226 } 1227 #endif 1228 /* 1229 * The hard case, migration, we need to block the thread first to 1230 * prevent order reversals with other cpus locks. 1231 */ 1232 spinlock_enter(); 1233 thread_lock_block(td); 1234 TDQ_LOCK(tdq); 1235 thread_lock_unblock(td, TDQ_LOCKPTR(tdq)); 1236 spinlock_exit(); 1237 return (tdq); 1238 } 1239 1240 SCHED_STAT_DEFINE(pickcpu_intrbind, "Soft interrupt binding"); 1241 SCHED_STAT_DEFINE(pickcpu_idle_affinity, "Picked idle cpu based on affinity"); 1242 SCHED_STAT_DEFINE(pickcpu_affinity, "Picked cpu based on affinity"); 1243 SCHED_STAT_DEFINE(pickcpu_lowest, "Selected lowest load"); 1244 SCHED_STAT_DEFINE(pickcpu_local, "Migrated to current cpu"); 1245 SCHED_STAT_DEFINE(pickcpu_migration, "Selection may have caused migration"); 1246 1247 static int 1248 sched_pickcpu(struct thread *td, int flags) 1249 { 1250 struct cpu_group *cg, *ccg; 1251 struct td_sched *ts; 1252 struct tdq *tdq; 1253 cpuset_t mask; 1254 int cpu, pri, self; 1255 1256 self = PCPU_GET(cpuid); 1257 ts = td_get_sched(td); 1258 KASSERT(!CPU_ABSENT(ts->ts_cpu), ("sched_pickcpu: Start scheduler on " 1259 "absent CPU %d for thread %s.", ts->ts_cpu, td->td_name)); 1260 if (smp_started == 0) 1261 return (self); 1262 /* 1263 * Don't migrate a running thread from sched_switch(). 1264 */ 1265 if ((flags & SRQ_OURSELF) || !THREAD_CAN_MIGRATE(td)) 1266 return (ts->ts_cpu); 1267 /* 1268 * Prefer to run interrupt threads on the processors that generate 1269 * the interrupt. 1270 */ 1271 pri = td->td_priority; 1272 if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_SCHED(td, self) && 1273 curthread->td_intr_nesting_level && ts->ts_cpu != self) { 1274 SCHED_STAT_INC(pickcpu_intrbind); 1275 ts->ts_cpu = self; 1276 if (TDQ_SELF()->tdq_lowpri > pri) { 1277 SCHED_STAT_INC(pickcpu_affinity); 1278 return (ts->ts_cpu); 1279 } 1280 } 1281 /* 1282 * If the thread can run on the last cpu and the affinity has not 1283 * expired and it is idle, run it there. 1284 */ 1285 tdq = TDQ_CPU(ts->ts_cpu); 1286 cg = tdq->tdq_cg; 1287 if (THREAD_CAN_SCHED(td, ts->ts_cpu) && 1288 tdq->tdq_lowpri >= PRI_MIN_IDLE && 1289 SCHED_AFFINITY(ts, CG_SHARE_L2)) { 1290 if (cg->cg_flags & CG_FLAG_THREAD) { 1291 CPUSET_FOREACH(cpu, cg->cg_mask) { 1292 if (TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE) 1293 break; 1294 } 1295 } else 1296 cpu = INT_MAX; 1297 if (cpu > mp_maxid) { 1298 SCHED_STAT_INC(pickcpu_idle_affinity); 1299 return (ts->ts_cpu); 1300 } 1301 } 1302 /* 1303 * Search for the last level cache CPU group in the tree. 1304 * Skip caches with expired affinity time and SMT groups. 1305 * Affinity to higher level caches will be handled less aggressively. 1306 */ 1307 for (ccg = NULL; cg != NULL; cg = cg->cg_parent) { 1308 if (cg->cg_flags & CG_FLAG_THREAD) 1309 continue; 1310 if (!SCHED_AFFINITY(ts, cg->cg_level)) 1311 continue; 1312 ccg = cg; 1313 } 1314 if (ccg != NULL) 1315 cg = ccg; 1316 cpu = -1; 1317 /* Search the group for the less loaded idle CPU we can run now. */ 1318 mask = td->td_cpuset->cs_mask; 1319 if (cg != NULL && cg != cpu_top && 1320 CPU_CMP(&cg->cg_mask, &cpu_top->cg_mask) != 0) 1321 cpu = sched_lowest(cg, mask, max(pri, PRI_MAX_TIMESHARE), 1322 INT_MAX, ts->ts_cpu); 1323 /* Search globally for the less loaded CPU we can run now. */ 1324 if (cpu == -1) 1325 cpu = sched_lowest(cpu_top, mask, pri, INT_MAX, ts->ts_cpu); 1326 /* Search globally for the less loaded CPU. */ 1327 if (cpu == -1) 1328 cpu = sched_lowest(cpu_top, mask, -1, INT_MAX, ts->ts_cpu); 1329 KASSERT(cpu != -1, ("sched_pickcpu: Failed to find a cpu.")); 1330 KASSERT(!CPU_ABSENT(cpu), ("sched_pickcpu: Picked absent CPU %d.", cpu)); 1331 /* 1332 * Compare the lowest loaded cpu to current cpu. 1333 */ 1334 tdq = TDQ_CPU(cpu); 1335 if (THREAD_CAN_SCHED(td, self) && TDQ_SELF()->tdq_lowpri > pri && 1336 tdq->tdq_lowpri < PRI_MIN_IDLE && 1337 TDQ_SELF()->tdq_load <= tdq->tdq_load + 1) { 1338 SCHED_STAT_INC(pickcpu_local); 1339 cpu = self; 1340 } else 1341 SCHED_STAT_INC(pickcpu_lowest); 1342 if (cpu != ts->ts_cpu) 1343 SCHED_STAT_INC(pickcpu_migration); 1344 return (cpu); 1345 } 1346 #endif 1347 1348 /* 1349 * Pick the highest priority task we have and return it. 1350 */ 1351 static struct thread * 1352 tdq_choose(struct tdq *tdq) 1353 { 1354 struct thread *td; 1355 1356 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1357 td = runq_choose(&tdq->tdq_realtime); 1358 if (td != NULL) 1359 return (td); 1360 td = runq_choose_from(&tdq->tdq_timeshare, tdq->tdq_ridx); 1361 if (td != NULL) { 1362 KASSERT(td->td_priority >= PRI_MIN_BATCH, 1363 ("tdq_choose: Invalid priority on timeshare queue %d", 1364 td->td_priority)); 1365 return (td); 1366 } 1367 td = runq_choose(&tdq->tdq_idle); 1368 if (td != NULL) { 1369 KASSERT(td->td_priority >= PRI_MIN_IDLE, 1370 ("tdq_choose: Invalid priority on idle queue %d", 1371 td->td_priority)); 1372 return (td); 1373 } 1374 1375 return (NULL); 1376 } 1377 1378 /* 1379 * Initialize a thread queue. 1380 */ 1381 static void 1382 tdq_setup(struct tdq *tdq, int id) 1383 { 1384 1385 if (bootverbose) 1386 printf("ULE: setup cpu %d\n", id); 1387 runq_init(&tdq->tdq_realtime); 1388 runq_init(&tdq->tdq_timeshare); 1389 runq_init(&tdq->tdq_idle); 1390 tdq->tdq_id = id; 1391 snprintf(tdq->tdq_name, sizeof(tdq->tdq_name), 1392 "sched lock %d", (int)TDQ_ID(tdq)); 1393 mtx_init(&tdq->tdq_lock, tdq->tdq_name, "sched lock", 1394 MTX_SPIN | MTX_RECURSE); 1395 #ifdef KTR 1396 snprintf(tdq->tdq_loadname, sizeof(tdq->tdq_loadname), 1397 "CPU %d load", (int)TDQ_ID(tdq)); 1398 #endif 1399 } 1400 1401 #ifdef SMP 1402 static void 1403 sched_setup_smp(void) 1404 { 1405 struct tdq *tdq; 1406 int i; 1407 1408 cpu_top = smp_topo(); 1409 CPU_FOREACH(i) { 1410 tdq = DPCPU_ID_PTR(i, tdq); 1411 tdq_setup(tdq, i); 1412 tdq->tdq_cg = smp_topo_find(cpu_top, i); 1413 if (tdq->tdq_cg == NULL) 1414 panic("Can't find cpu group for %d\n", i); 1415 } 1416 PCPU_SET(sched, DPCPU_PTR(tdq)); 1417 balance_tdq = TDQ_SELF(); 1418 } 1419 #endif 1420 1421 /* 1422 * Setup the thread queues and initialize the topology based on MD 1423 * information. 1424 */ 1425 static void 1426 sched_setup(void *dummy) 1427 { 1428 struct tdq *tdq; 1429 1430 #ifdef SMP 1431 sched_setup_smp(); 1432 #else 1433 tdq_setup(TDQ_SELF(), 0); 1434 #endif 1435 tdq = TDQ_SELF(); 1436 1437 /* Add thread0's load since it's running. */ 1438 TDQ_LOCK(tdq); 1439 thread0.td_lock = TDQ_LOCKPTR(TDQ_SELF()); 1440 tdq_load_add(tdq, &thread0); 1441 tdq->tdq_lowpri = thread0.td_priority; 1442 TDQ_UNLOCK(tdq); 1443 } 1444 1445 /* 1446 * This routine determines time constants after stathz and hz are setup. 1447 */ 1448 /* ARGSUSED */ 1449 static void 1450 sched_initticks(void *dummy) 1451 { 1452 int incr; 1453 1454 realstathz = stathz ? stathz : hz; 1455 sched_slice = realstathz / SCHED_SLICE_DEFAULT_DIVISOR; 1456 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 1457 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 1458 realstathz); 1459 1460 /* 1461 * tickincr is shifted out by 10 to avoid rounding errors due to 1462 * hz not being evenly divisible by stathz on all platforms. 1463 */ 1464 incr = (hz << SCHED_TICK_SHIFT) / realstathz; 1465 /* 1466 * This does not work for values of stathz that are more than 1467 * 1 << SCHED_TICK_SHIFT * hz. In practice this does not happen. 1468 */ 1469 if (incr == 0) 1470 incr = 1; 1471 tickincr = incr; 1472 #ifdef SMP 1473 /* 1474 * Set the default balance interval now that we know 1475 * what realstathz is. 1476 */ 1477 balance_interval = realstathz; 1478 balance_ticks = balance_interval; 1479 affinity = SCHED_AFFINITY_DEFAULT; 1480 #endif 1481 if (sched_idlespinthresh < 0) 1482 sched_idlespinthresh = 2 * max(10000, 6 * hz) / realstathz; 1483 } 1484 1485 1486 /* 1487 * This is the core of the interactivity algorithm. Determines a score based 1488 * on past behavior. It is the ratio of sleep time to run time scaled to 1489 * a [0, 100] integer. This is the voluntary sleep time of a process, which 1490 * differs from the cpu usage because it does not account for time spent 1491 * waiting on a run-queue. Would be prettier if we had floating point. 1492 * 1493 * When a thread's sleep time is greater than its run time the 1494 * calculation is: 1495 * 1496 * scaling factor 1497 * interactivity score = --------------------- 1498 * sleep time / run time 1499 * 1500 * 1501 * When a thread's run time is greater than its sleep time the 1502 * calculation is: 1503 * 1504 * scaling factor 1505 * interactivity score = --------------------- + scaling factor 1506 * run time / sleep time 1507 */ 1508 static int 1509 sched_interact_score(struct thread *td) 1510 { 1511 struct td_sched *ts; 1512 int div; 1513 1514 ts = td_get_sched(td); 1515 /* 1516 * The score is only needed if this is likely to be an interactive 1517 * task. Don't go through the expense of computing it if there's 1518 * no chance. 1519 */ 1520 if (sched_interact <= SCHED_INTERACT_HALF && 1521 ts->ts_runtime >= ts->ts_slptime) 1522 return (SCHED_INTERACT_HALF); 1523 1524 if (ts->ts_runtime > ts->ts_slptime) { 1525 div = max(1, ts->ts_runtime / SCHED_INTERACT_HALF); 1526 return (SCHED_INTERACT_HALF + 1527 (SCHED_INTERACT_HALF - (ts->ts_slptime / div))); 1528 } 1529 if (ts->ts_slptime > ts->ts_runtime) { 1530 div = max(1, ts->ts_slptime / SCHED_INTERACT_HALF); 1531 return (ts->ts_runtime / div); 1532 } 1533 /* runtime == slptime */ 1534 if (ts->ts_runtime) 1535 return (SCHED_INTERACT_HALF); 1536 1537 /* 1538 * This can happen if slptime and runtime are 0. 1539 */ 1540 return (0); 1541 1542 } 1543 1544 /* 1545 * Scale the scheduling priority according to the "interactivity" of this 1546 * process. 1547 */ 1548 static void 1549 sched_priority(struct thread *td) 1550 { 1551 int score; 1552 int pri; 1553 1554 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 1555 return; 1556 /* 1557 * If the score is interactive we place the thread in the realtime 1558 * queue with a priority that is less than kernel and interrupt 1559 * priorities. These threads are not subject to nice restrictions. 1560 * 1561 * Scores greater than this are placed on the normal timeshare queue 1562 * where the priority is partially decided by the most recent cpu 1563 * utilization and the rest is decided by nice value. 1564 * 1565 * The nice value of the process has a linear effect on the calculated 1566 * score. Negative nice values make it easier for a thread to be 1567 * considered interactive. 1568 */ 1569 score = imax(0, sched_interact_score(td) + td->td_proc->p_nice); 1570 if (score < sched_interact) { 1571 pri = PRI_MIN_INTERACT; 1572 pri += ((PRI_MAX_INTERACT - PRI_MIN_INTERACT + 1) / 1573 sched_interact) * score; 1574 KASSERT(pri >= PRI_MIN_INTERACT && pri <= PRI_MAX_INTERACT, 1575 ("sched_priority: invalid interactive priority %d score %d", 1576 pri, score)); 1577 } else { 1578 pri = SCHED_PRI_MIN; 1579 if (td_get_sched(td)->ts_ticks) 1580 pri += min(SCHED_PRI_TICKS(td_get_sched(td)), 1581 SCHED_PRI_RANGE - 1); 1582 pri += SCHED_PRI_NICE(td->td_proc->p_nice); 1583 KASSERT(pri >= PRI_MIN_BATCH && pri <= PRI_MAX_BATCH, 1584 ("sched_priority: invalid priority %d: nice %d, " 1585 "ticks %d ftick %d ltick %d tick pri %d", 1586 pri, td->td_proc->p_nice, td_get_sched(td)->ts_ticks, 1587 td_get_sched(td)->ts_ftick, td_get_sched(td)->ts_ltick, 1588 SCHED_PRI_TICKS(td_get_sched(td)))); 1589 } 1590 sched_user_prio(td, pri); 1591 1592 return; 1593 } 1594 1595 /* 1596 * This routine enforces a maximum limit on the amount of scheduling history 1597 * kept. It is called after either the slptime or runtime is adjusted. This 1598 * function is ugly due to integer math. 1599 */ 1600 static void 1601 sched_interact_update(struct thread *td) 1602 { 1603 struct td_sched *ts; 1604 u_int sum; 1605 1606 ts = td_get_sched(td); 1607 sum = ts->ts_runtime + ts->ts_slptime; 1608 if (sum < SCHED_SLP_RUN_MAX) 1609 return; 1610 /* 1611 * This only happens from two places: 1612 * 1) We have added an unusual amount of run time from fork_exit. 1613 * 2) We have added an unusual amount of sleep time from sched_sleep(). 1614 */ 1615 if (sum > SCHED_SLP_RUN_MAX * 2) { 1616 if (ts->ts_runtime > ts->ts_slptime) { 1617 ts->ts_runtime = SCHED_SLP_RUN_MAX; 1618 ts->ts_slptime = 1; 1619 } else { 1620 ts->ts_slptime = SCHED_SLP_RUN_MAX; 1621 ts->ts_runtime = 1; 1622 } 1623 return; 1624 } 1625 /* 1626 * If we have exceeded by more than 1/5th then the algorithm below 1627 * will not bring us back into range. Dividing by two here forces 1628 * us into the range of [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX] 1629 */ 1630 if (sum > (SCHED_SLP_RUN_MAX / 5) * 6) { 1631 ts->ts_runtime /= 2; 1632 ts->ts_slptime /= 2; 1633 return; 1634 } 1635 ts->ts_runtime = (ts->ts_runtime / 5) * 4; 1636 ts->ts_slptime = (ts->ts_slptime / 5) * 4; 1637 } 1638 1639 /* 1640 * Scale back the interactivity history when a child thread is created. The 1641 * history is inherited from the parent but the thread may behave totally 1642 * differently. For example, a shell spawning a compiler process. We want 1643 * to learn that the compiler is behaving badly very quickly. 1644 */ 1645 static void 1646 sched_interact_fork(struct thread *td) 1647 { 1648 struct td_sched *ts; 1649 int ratio; 1650 int sum; 1651 1652 ts = td_get_sched(td); 1653 sum = ts->ts_runtime + ts->ts_slptime; 1654 if (sum > SCHED_SLP_RUN_FORK) { 1655 ratio = sum / SCHED_SLP_RUN_FORK; 1656 ts->ts_runtime /= ratio; 1657 ts->ts_slptime /= ratio; 1658 } 1659 } 1660 1661 /* 1662 * Called from proc0_init() to setup the scheduler fields. 1663 */ 1664 void 1665 schedinit(void) 1666 { 1667 struct td_sched *ts0; 1668 1669 /* 1670 * Set up the scheduler specific parts of thread0. 1671 */ 1672 ts0 = td_get_sched(&thread0); 1673 ts0->ts_ltick = ticks; 1674 ts0->ts_ftick = ticks; 1675 ts0->ts_slice = 0; 1676 ts0->ts_cpu = curcpu; /* set valid CPU number */ 1677 } 1678 1679 /* 1680 * This is only somewhat accurate since given many processes of the same 1681 * priority they will switch when their slices run out, which will be 1682 * at most sched_slice stathz ticks. 1683 */ 1684 int 1685 sched_rr_interval(void) 1686 { 1687 1688 /* Convert sched_slice from stathz to hz. */ 1689 return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz)); 1690 } 1691 1692 /* 1693 * Update the percent cpu tracking information when it is requested or 1694 * the total history exceeds the maximum. We keep a sliding history of 1695 * tick counts that slowly decays. This is less precise than the 4BSD 1696 * mechanism since it happens with less regular and frequent events. 1697 */ 1698 static void 1699 sched_pctcpu_update(struct td_sched *ts, int run) 1700 { 1701 int t = ticks; 1702 1703 /* 1704 * The signed difference may be negative if the thread hasn't run for 1705 * over half of the ticks rollover period. 1706 */ 1707 if ((u_int)(t - ts->ts_ltick) >= SCHED_TICK_TARG) { 1708 ts->ts_ticks = 0; 1709 ts->ts_ftick = t - SCHED_TICK_TARG; 1710 } else if (t - ts->ts_ftick >= SCHED_TICK_MAX) { 1711 ts->ts_ticks = (ts->ts_ticks / (ts->ts_ltick - ts->ts_ftick)) * 1712 (ts->ts_ltick - (t - SCHED_TICK_TARG)); 1713 ts->ts_ftick = t - SCHED_TICK_TARG; 1714 } 1715 if (run) 1716 ts->ts_ticks += (t - ts->ts_ltick) << SCHED_TICK_SHIFT; 1717 ts->ts_ltick = t; 1718 } 1719 1720 /* 1721 * Adjust the priority of a thread. Move it to the appropriate run-queue 1722 * if necessary. This is the back-end for several priority related 1723 * functions. 1724 */ 1725 static void 1726 sched_thread_priority(struct thread *td, u_char prio) 1727 { 1728 struct td_sched *ts; 1729 struct tdq *tdq; 1730 int oldpri; 1731 1732 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "prio", 1733 "prio:%d", td->td_priority, "new prio:%d", prio, 1734 KTR_ATTR_LINKED, sched_tdname(curthread)); 1735 SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio); 1736 if (td != curthread && prio < td->td_priority) { 1737 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread), 1738 "lend prio", "prio:%d", td->td_priority, "new prio:%d", 1739 prio, KTR_ATTR_LINKED, sched_tdname(td)); 1740 SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio, 1741 curthread); 1742 } 1743 ts = td_get_sched(td); 1744 THREAD_LOCK_ASSERT(td, MA_OWNED); 1745 if (td->td_priority == prio) 1746 return; 1747 /* 1748 * If the priority has been elevated due to priority 1749 * propagation, we may have to move ourselves to a new 1750 * queue. This could be optimized to not re-add in some 1751 * cases. 1752 */ 1753 if (TD_ON_RUNQ(td) && prio < td->td_priority) { 1754 sched_rem(td); 1755 td->td_priority = prio; 1756 sched_add(td, SRQ_BORROWING); 1757 return; 1758 } 1759 /* 1760 * If the thread is currently running we may have to adjust the lowpri 1761 * information so other cpus are aware of our current priority. 1762 */ 1763 if (TD_IS_RUNNING(td)) { 1764 tdq = TDQ_CPU(ts->ts_cpu); 1765 oldpri = td->td_priority; 1766 td->td_priority = prio; 1767 if (prio < tdq->tdq_lowpri) 1768 tdq->tdq_lowpri = prio; 1769 else if (tdq->tdq_lowpri == oldpri) 1770 tdq_setlowpri(tdq, td); 1771 return; 1772 } 1773 td->td_priority = prio; 1774 } 1775 1776 /* 1777 * Update a thread's priority when it is lent another thread's 1778 * priority. 1779 */ 1780 void 1781 sched_lend_prio(struct thread *td, u_char prio) 1782 { 1783 1784 td->td_flags |= TDF_BORROWING; 1785 sched_thread_priority(td, prio); 1786 } 1787 1788 /* 1789 * Restore a thread's priority when priority propagation is 1790 * over. The prio argument is the minimum priority the thread 1791 * needs to have to satisfy other possible priority lending 1792 * requests. If the thread's regular priority is less 1793 * important than prio, the thread will keep a priority boost 1794 * of prio. 1795 */ 1796 void 1797 sched_unlend_prio(struct thread *td, u_char prio) 1798 { 1799 u_char base_pri; 1800 1801 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 1802 td->td_base_pri <= PRI_MAX_TIMESHARE) 1803 base_pri = td->td_user_pri; 1804 else 1805 base_pri = td->td_base_pri; 1806 if (prio >= base_pri) { 1807 td->td_flags &= ~TDF_BORROWING; 1808 sched_thread_priority(td, base_pri); 1809 } else 1810 sched_lend_prio(td, prio); 1811 } 1812 1813 /* 1814 * Standard entry for setting the priority to an absolute value. 1815 */ 1816 void 1817 sched_prio(struct thread *td, u_char prio) 1818 { 1819 u_char oldprio; 1820 1821 /* First, update the base priority. */ 1822 td->td_base_pri = prio; 1823 1824 /* 1825 * If the thread is borrowing another thread's priority, don't 1826 * ever lower the priority. 1827 */ 1828 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 1829 return; 1830 1831 /* Change the real priority. */ 1832 oldprio = td->td_priority; 1833 sched_thread_priority(td, prio); 1834 1835 /* 1836 * If the thread is on a turnstile, then let the turnstile update 1837 * its state. 1838 */ 1839 if (TD_ON_LOCK(td) && oldprio != prio) 1840 turnstile_adjust(td, oldprio); 1841 } 1842 1843 /* 1844 * Set the base user priority, does not effect current running priority. 1845 */ 1846 void 1847 sched_user_prio(struct thread *td, u_char prio) 1848 { 1849 1850 td->td_base_user_pri = prio; 1851 if (td->td_lend_user_pri <= prio) 1852 return; 1853 td->td_user_pri = prio; 1854 } 1855 1856 void 1857 sched_lend_user_prio(struct thread *td, u_char prio) 1858 { 1859 1860 THREAD_LOCK_ASSERT(td, MA_OWNED); 1861 td->td_lend_user_pri = prio; 1862 td->td_user_pri = min(prio, td->td_base_user_pri); 1863 if (td->td_priority > td->td_user_pri) 1864 sched_prio(td, td->td_user_pri); 1865 else if (td->td_priority != td->td_user_pri) 1866 td->td_flags |= TDF_NEEDRESCHED; 1867 } 1868 1869 /* 1870 * Like the above but first check if there is anything to do. 1871 */ 1872 void 1873 sched_lend_user_prio_cond(struct thread *td, u_char prio) 1874 { 1875 1876 if (td->td_lend_user_pri != prio) 1877 goto lend; 1878 if (td->td_user_pri != min(prio, td->td_base_user_pri)) 1879 goto lend; 1880 if (td->td_priority >= td->td_user_pri) 1881 goto lend; 1882 return; 1883 1884 lend: 1885 thread_lock(td); 1886 sched_lend_user_prio(td, prio); 1887 thread_unlock(td); 1888 } 1889 1890 #ifdef SMP 1891 /* 1892 * This tdq is about to idle. Try to steal a thread from another CPU before 1893 * choosing the idle thread. 1894 */ 1895 static void 1896 tdq_trysteal(struct tdq *tdq) 1897 { 1898 struct cpu_group *cg; 1899 struct tdq *steal; 1900 cpuset_t mask; 1901 int cpu, i; 1902 1903 if (smp_started == 0 || trysteal_limit == 0 || tdq->tdq_cg == NULL) 1904 return; 1905 CPU_FILL(&mask); 1906 CPU_CLR(PCPU_GET(cpuid), &mask); 1907 /* We don't want to be preempted while we're iterating. */ 1908 spinlock_enter(); 1909 TDQ_UNLOCK(tdq); 1910 for (i = 1, cg = tdq->tdq_cg; ; ) { 1911 cpu = sched_highest(cg, mask, steal_thresh); 1912 /* 1913 * If a thread was added while interrupts were disabled don't 1914 * steal one here. 1915 */ 1916 if (tdq->tdq_load > 0) { 1917 TDQ_LOCK(tdq); 1918 break; 1919 } 1920 if (cpu == -1) { 1921 i++; 1922 cg = cg->cg_parent; 1923 if (cg == NULL || i > trysteal_limit) { 1924 TDQ_LOCK(tdq); 1925 break; 1926 } 1927 continue; 1928 } 1929 steal = TDQ_CPU(cpu); 1930 /* 1931 * The data returned by sched_highest() is stale and 1932 * the chosen CPU no longer has an eligible thread. 1933 */ 1934 if (steal->tdq_load < steal_thresh || 1935 steal->tdq_transferable == 0) 1936 continue; 1937 tdq_lock_pair(tdq, steal); 1938 /* 1939 * If we get to this point, unconditonally exit the loop 1940 * to bound the time spent in the critcal section. 1941 * 1942 * If a thread was added while interrupts were disabled don't 1943 * steal one here. 1944 */ 1945 if (tdq->tdq_load > 0) { 1946 TDQ_UNLOCK(steal); 1947 break; 1948 } 1949 /* 1950 * The data returned by sched_highest() is stale and 1951 * the chosen CPU no longer has an eligible thread. 1952 */ 1953 if (steal->tdq_load < steal_thresh || 1954 steal->tdq_transferable == 0) { 1955 TDQ_UNLOCK(steal); 1956 break; 1957 } 1958 /* 1959 * If we fail to acquire one due to affinity restrictions, 1960 * bail out and let the idle thread to a more complete search 1961 * outside of a critical section. 1962 */ 1963 if (tdq_move(steal, tdq) == NULL) { 1964 TDQ_UNLOCK(steal); 1965 break; 1966 } 1967 TDQ_UNLOCK(steal); 1968 break; 1969 } 1970 spinlock_exit(); 1971 } 1972 #endif 1973 1974 /* 1975 * Handle migration from sched_switch(). This happens only for 1976 * cpu binding. 1977 */ 1978 static struct mtx * 1979 sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags) 1980 { 1981 struct tdq *tdn; 1982 1983 KASSERT(!CPU_ABSENT(td_get_sched(td)->ts_cpu), ("sched_switch_migrate: " 1984 "thread %s queued on absent CPU %d.", td->td_name, 1985 td_get_sched(td)->ts_cpu)); 1986 tdn = TDQ_CPU(td_get_sched(td)->ts_cpu); 1987 #ifdef SMP 1988 tdq_load_rem(tdq, td); 1989 /* 1990 * Do the lock dance required to avoid LOR. We grab an extra 1991 * spinlock nesting to prevent preemption while we're 1992 * not holding either run-queue lock. 1993 */ 1994 spinlock_enter(); 1995 thread_lock_block(td); /* This releases the lock on tdq. */ 1996 1997 /* 1998 * Acquire both run-queue locks before placing the thread on the new 1999 * run-queue to avoid deadlocks created by placing a thread with a 2000 * blocked lock on the run-queue of a remote processor. The deadlock 2001 * occurs when a third processor attempts to lock the two queues in 2002 * question while the target processor is spinning with its own 2003 * run-queue lock held while waiting for the blocked lock to clear. 2004 */ 2005 tdq_lock_pair(tdn, tdq); 2006 tdq_add(tdn, td, flags); 2007 tdq_notify(tdn, td); 2008 TDQ_UNLOCK(tdn); 2009 spinlock_exit(); 2010 #endif 2011 return (TDQ_LOCKPTR(tdn)); 2012 } 2013 2014 /* 2015 * Variadic version of thread_lock_unblock() that does not assume td_lock 2016 * is blocked. 2017 */ 2018 static inline void 2019 thread_unblock_switch(struct thread *td, struct mtx *mtx) 2020 { 2021 atomic_store_rel_ptr((volatile uintptr_t *)&td->td_lock, 2022 (uintptr_t)mtx); 2023 } 2024 2025 /* 2026 * Switch threads. This function has to handle threads coming in while 2027 * blocked for some reason, running, or idle. It also must deal with 2028 * migrating a thread from one queue to another as running threads may 2029 * be assigned elsewhere via binding. 2030 */ 2031 void 2032 sched_switch(struct thread *td, struct thread *newtd, int flags) 2033 { 2034 struct tdq *tdq; 2035 struct td_sched *ts; 2036 struct mtx *mtx; 2037 int srqflag; 2038 int cpuid, preempted; 2039 2040 THREAD_LOCK_ASSERT(td, MA_OWNED); 2041 KASSERT(newtd == NULL, ("sched_switch: Unsupported newtd argument")); 2042 2043 cpuid = PCPU_GET(cpuid); 2044 tdq = TDQ_SELF(); 2045 ts = td_get_sched(td); 2046 mtx = td->td_lock; 2047 sched_pctcpu_update(ts, 1); 2048 ts->ts_rltick = ticks; 2049 td->td_lastcpu = td->td_oncpu; 2050 td->td_oncpu = NOCPU; 2051 preempted = (td->td_flags & TDF_SLICEEND) == 0 && 2052 (flags & SW_PREEMPT) != 0; 2053 td->td_flags &= ~(TDF_NEEDRESCHED | TDF_SLICEEND); 2054 td->td_owepreempt = 0; 2055 if (!TD_IS_IDLETHREAD(td)) 2056 tdq->tdq_switchcnt++; 2057 /* 2058 * The lock pointer in an idle thread should never change. Reset it 2059 * to CAN_RUN as well. 2060 */ 2061 if (TD_IS_IDLETHREAD(td)) { 2062 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2063 TD_SET_CAN_RUN(td); 2064 } else if (TD_IS_RUNNING(td)) { 2065 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2066 srqflag = preempted ? 2067 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 2068 SRQ_OURSELF|SRQ_YIELDING; 2069 #ifdef SMP 2070 if (THREAD_CAN_MIGRATE(td) && !THREAD_CAN_SCHED(td, ts->ts_cpu)) 2071 ts->ts_cpu = sched_pickcpu(td, 0); 2072 #endif 2073 if (ts->ts_cpu == cpuid) 2074 tdq_runq_add(tdq, td, srqflag); 2075 else { 2076 KASSERT(THREAD_CAN_MIGRATE(td) || 2077 (ts->ts_flags & TSF_BOUND) != 0, 2078 ("Thread %p shouldn't migrate", td)); 2079 mtx = sched_switch_migrate(tdq, td, srqflag); 2080 } 2081 } else { 2082 /* This thread must be going to sleep. */ 2083 TDQ_LOCK(tdq); 2084 mtx = thread_lock_block(td); 2085 tdq_load_rem(tdq, td); 2086 #ifdef SMP 2087 if (tdq->tdq_load == 0) 2088 tdq_trysteal(tdq); 2089 #endif 2090 } 2091 2092 #if (KTR_COMPILE & KTR_SCHED) != 0 2093 if (TD_IS_IDLETHREAD(td)) 2094 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "idle", 2095 "prio:%d", td->td_priority); 2096 else 2097 KTR_STATE3(KTR_SCHED, "thread", sched_tdname(td), KTDSTATE(td), 2098 "prio:%d", td->td_priority, "wmesg:\"%s\"", td->td_wmesg, 2099 "lockname:\"%s\"", td->td_lockname); 2100 #endif 2101 2102 /* 2103 * We enter here with the thread blocked and assigned to the 2104 * appropriate cpu run-queue or sleep-queue and with the current 2105 * thread-queue locked. 2106 */ 2107 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 2108 newtd = choosethread(); 2109 /* 2110 * Call the MD code to switch contexts if necessary. 2111 */ 2112 if (td != newtd) { 2113 #ifdef HWPMC_HOOKS 2114 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 2115 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 2116 #endif 2117 SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc); 2118 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 2119 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 2120 sched_pctcpu_update(td_get_sched(newtd), 0); 2121 2122 #ifdef KDTRACE_HOOKS 2123 /* 2124 * If DTrace has set the active vtime enum to anything 2125 * other than INACTIVE (0), then it should have set the 2126 * function to call. 2127 */ 2128 if (dtrace_vtime_active) 2129 (*dtrace_vtime_switch_func)(newtd); 2130 #endif 2131 2132 cpu_switch(td, newtd, mtx); 2133 /* 2134 * We may return from cpu_switch on a different cpu. However, 2135 * we always return with td_lock pointing to the current cpu's 2136 * run queue lock. 2137 */ 2138 cpuid = PCPU_GET(cpuid); 2139 tdq = TDQ_SELF(); 2140 lock_profile_obtain_lock_success( 2141 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 2142 2143 SDT_PROBE0(sched, , , on__cpu); 2144 #ifdef HWPMC_HOOKS 2145 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 2146 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 2147 #endif 2148 } else { 2149 thread_unblock_switch(td, mtx); 2150 SDT_PROBE0(sched, , , remain__cpu); 2151 } 2152 2153 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running", 2154 "prio:%d", td->td_priority); 2155 2156 /* 2157 * Assert that all went well and return. 2158 */ 2159 TDQ_LOCK_ASSERT(tdq, MA_OWNED|MA_NOTRECURSED); 2160 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2161 td->td_oncpu = cpuid; 2162 } 2163 2164 /* 2165 * Adjust thread priorities as a result of a nice request. 2166 */ 2167 void 2168 sched_nice(struct proc *p, int nice) 2169 { 2170 struct thread *td; 2171 2172 PROC_LOCK_ASSERT(p, MA_OWNED); 2173 2174 p->p_nice = nice; 2175 FOREACH_THREAD_IN_PROC(p, td) { 2176 thread_lock(td); 2177 sched_priority(td); 2178 sched_prio(td, td->td_base_user_pri); 2179 thread_unlock(td); 2180 } 2181 } 2182 2183 /* 2184 * Record the sleep time for the interactivity scorer. 2185 */ 2186 void 2187 sched_sleep(struct thread *td, int prio) 2188 { 2189 2190 THREAD_LOCK_ASSERT(td, MA_OWNED); 2191 2192 td->td_slptick = ticks; 2193 if (TD_IS_SUSPENDED(td) || prio >= PSOCK) 2194 td->td_flags |= TDF_CANSWAP; 2195 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 2196 return; 2197 if (static_boost == 1 && prio) 2198 sched_prio(td, prio); 2199 else if (static_boost && td->td_priority > static_boost) 2200 sched_prio(td, static_boost); 2201 } 2202 2203 /* 2204 * Schedule a thread to resume execution and record how long it voluntarily 2205 * slept. We also update the pctcpu, interactivity, and priority. 2206 */ 2207 void 2208 sched_wakeup(struct thread *td) 2209 { 2210 struct td_sched *ts; 2211 int slptick; 2212 2213 THREAD_LOCK_ASSERT(td, MA_OWNED); 2214 ts = td_get_sched(td); 2215 td->td_flags &= ~TDF_CANSWAP; 2216 /* 2217 * If we slept for more than a tick update our interactivity and 2218 * priority. 2219 */ 2220 slptick = td->td_slptick; 2221 td->td_slptick = 0; 2222 if (slptick && slptick != ticks) { 2223 ts->ts_slptime += (ticks - slptick) << SCHED_TICK_SHIFT; 2224 sched_interact_update(td); 2225 sched_pctcpu_update(ts, 0); 2226 } 2227 /* 2228 * Reset the slice value since we slept and advanced the round-robin. 2229 */ 2230 ts->ts_slice = 0; 2231 sched_add(td, SRQ_BORING); 2232 } 2233 2234 /* 2235 * Penalize the parent for creating a new child and initialize the child's 2236 * priority. 2237 */ 2238 void 2239 sched_fork(struct thread *td, struct thread *child) 2240 { 2241 THREAD_LOCK_ASSERT(td, MA_OWNED); 2242 sched_pctcpu_update(td_get_sched(td), 1); 2243 sched_fork_thread(td, child); 2244 /* 2245 * Penalize the parent and child for forking. 2246 */ 2247 sched_interact_fork(child); 2248 sched_priority(child); 2249 td_get_sched(td)->ts_runtime += tickincr; 2250 sched_interact_update(td); 2251 sched_priority(td); 2252 } 2253 2254 /* 2255 * Fork a new thread, may be within the same process. 2256 */ 2257 void 2258 sched_fork_thread(struct thread *td, struct thread *child) 2259 { 2260 struct td_sched *ts; 2261 struct td_sched *ts2; 2262 struct tdq *tdq; 2263 2264 tdq = TDQ_SELF(); 2265 THREAD_LOCK_ASSERT(td, MA_OWNED); 2266 /* 2267 * Initialize child. 2268 */ 2269 ts = td_get_sched(td); 2270 ts2 = td_get_sched(child); 2271 child->td_oncpu = NOCPU; 2272 child->td_lastcpu = NOCPU; 2273 child->td_lock = TDQ_LOCKPTR(tdq); 2274 child->td_cpuset = cpuset_ref(td->td_cpuset); 2275 child->td_domain.dr_policy = td->td_cpuset->cs_domain; 2276 ts2->ts_cpu = ts->ts_cpu; 2277 ts2->ts_flags = 0; 2278 /* 2279 * Grab our parents cpu estimation information. 2280 */ 2281 ts2->ts_ticks = ts->ts_ticks; 2282 ts2->ts_ltick = ts->ts_ltick; 2283 ts2->ts_ftick = ts->ts_ftick; 2284 /* 2285 * Do not inherit any borrowed priority from the parent. 2286 */ 2287 child->td_priority = child->td_base_pri; 2288 /* 2289 * And update interactivity score. 2290 */ 2291 ts2->ts_slptime = ts->ts_slptime; 2292 ts2->ts_runtime = ts->ts_runtime; 2293 /* Attempt to quickly learn interactivity. */ 2294 ts2->ts_slice = tdq_slice(tdq) - sched_slice_min; 2295 #ifdef KTR 2296 bzero(ts2->ts_name, sizeof(ts2->ts_name)); 2297 #endif 2298 } 2299 2300 /* 2301 * Adjust the priority class of a thread. 2302 */ 2303 void 2304 sched_class(struct thread *td, int class) 2305 { 2306 2307 THREAD_LOCK_ASSERT(td, MA_OWNED); 2308 if (td->td_pri_class == class) 2309 return; 2310 td->td_pri_class = class; 2311 } 2312 2313 /* 2314 * Return some of the child's priority and interactivity to the parent. 2315 */ 2316 void 2317 sched_exit(struct proc *p, struct thread *child) 2318 { 2319 struct thread *td; 2320 2321 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "proc exit", 2322 "prio:%d", child->td_priority); 2323 PROC_LOCK_ASSERT(p, MA_OWNED); 2324 td = FIRST_THREAD_IN_PROC(p); 2325 sched_exit_thread(td, child); 2326 } 2327 2328 /* 2329 * Penalize another thread for the time spent on this one. This helps to 2330 * worsen the priority and interactivity of processes which schedule batch 2331 * jobs such as make. This has little effect on the make process itself but 2332 * causes new processes spawned by it to receive worse scores immediately. 2333 */ 2334 void 2335 sched_exit_thread(struct thread *td, struct thread *child) 2336 { 2337 2338 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "thread exit", 2339 "prio:%d", child->td_priority); 2340 /* 2341 * Give the child's runtime to the parent without returning the 2342 * sleep time as a penalty to the parent. This causes shells that 2343 * launch expensive things to mark their children as expensive. 2344 */ 2345 thread_lock(td); 2346 td_get_sched(td)->ts_runtime += td_get_sched(child)->ts_runtime; 2347 sched_interact_update(td); 2348 sched_priority(td); 2349 thread_unlock(td); 2350 } 2351 2352 void 2353 sched_preempt(struct thread *td) 2354 { 2355 struct tdq *tdq; 2356 2357 SDT_PROBE2(sched, , , surrender, td, td->td_proc); 2358 2359 thread_lock(td); 2360 tdq = TDQ_SELF(); 2361 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2362 tdq->tdq_ipipending = 0; 2363 if (td->td_priority > tdq->tdq_lowpri) { 2364 int flags; 2365 2366 flags = SW_INVOL | SW_PREEMPT; 2367 if (td->td_critnest > 1) 2368 td->td_owepreempt = 1; 2369 else if (TD_IS_IDLETHREAD(td)) 2370 mi_switch(flags | SWT_REMOTEWAKEIDLE, NULL); 2371 else 2372 mi_switch(flags | SWT_REMOTEPREEMPT, NULL); 2373 } 2374 thread_unlock(td); 2375 } 2376 2377 /* 2378 * Fix priorities on return to user-space. Priorities may be elevated due 2379 * to static priorities in msleep() or similar. 2380 */ 2381 void 2382 sched_userret_slowpath(struct thread *td) 2383 { 2384 2385 thread_lock(td); 2386 td->td_priority = td->td_user_pri; 2387 td->td_base_pri = td->td_user_pri; 2388 tdq_setlowpri(TDQ_SELF(), td); 2389 thread_unlock(td); 2390 } 2391 2392 /* 2393 * Handle a stathz tick. This is really only relevant for timeshare 2394 * threads. 2395 */ 2396 void 2397 sched_clock(struct thread *td) 2398 { 2399 struct tdq *tdq; 2400 struct td_sched *ts; 2401 2402 THREAD_LOCK_ASSERT(td, MA_OWNED); 2403 tdq = TDQ_SELF(); 2404 #ifdef SMP 2405 /* 2406 * We run the long term load balancer infrequently on the first cpu. 2407 */ 2408 if (balance_tdq == tdq && smp_started != 0 && rebalance != 0) { 2409 if (balance_ticks && --balance_ticks == 0) 2410 sched_balance(); 2411 } 2412 #endif 2413 /* 2414 * Save the old switch count so we have a record of the last ticks 2415 * activity. Initialize the new switch count based on our load. 2416 * If there is some activity seed it to reflect that. 2417 */ 2418 tdq->tdq_oldswitchcnt = tdq->tdq_switchcnt; 2419 tdq->tdq_switchcnt = tdq->tdq_load; 2420 /* 2421 * Advance the insert index once for each tick to ensure that all 2422 * threads get a chance to run. 2423 */ 2424 if (tdq->tdq_idx == tdq->tdq_ridx) { 2425 tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS; 2426 if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx])) 2427 tdq->tdq_ridx = tdq->tdq_idx; 2428 } 2429 ts = td_get_sched(td); 2430 sched_pctcpu_update(ts, 1); 2431 if (td->td_pri_class & PRI_FIFO_BIT) 2432 return; 2433 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) { 2434 /* 2435 * We used a tick; charge it to the thread so 2436 * that we can compute our interactivity. 2437 */ 2438 td_get_sched(td)->ts_runtime += tickincr; 2439 sched_interact_update(td); 2440 sched_priority(td); 2441 } 2442 2443 /* 2444 * Force a context switch if the current thread has used up a full 2445 * time slice (default is 100ms). 2446 */ 2447 if (!TD_IS_IDLETHREAD(td) && ++ts->ts_slice >= tdq_slice(tdq)) { 2448 ts->ts_slice = 0; 2449 td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND; 2450 } 2451 } 2452 2453 u_int 2454 sched_estcpu(struct thread *td __unused) 2455 { 2456 2457 return (0); 2458 } 2459 2460 /* 2461 * Return whether the current CPU has runnable tasks. Used for in-kernel 2462 * cooperative idle threads. 2463 */ 2464 int 2465 sched_runnable(void) 2466 { 2467 struct tdq *tdq; 2468 int load; 2469 2470 load = 1; 2471 2472 tdq = TDQ_SELF(); 2473 if ((curthread->td_flags & TDF_IDLETD) != 0) { 2474 if (tdq->tdq_load > 0) 2475 goto out; 2476 } else 2477 if (tdq->tdq_load - 1 > 0) 2478 goto out; 2479 load = 0; 2480 out: 2481 return (load); 2482 } 2483 2484 /* 2485 * Choose the highest priority thread to run. The thread is removed from 2486 * the run-queue while running however the load remains. For SMP we set 2487 * the tdq in the global idle bitmask if it idles here. 2488 */ 2489 struct thread * 2490 sched_choose(void) 2491 { 2492 struct thread *td; 2493 struct tdq *tdq; 2494 2495 tdq = TDQ_SELF(); 2496 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2497 td = tdq_choose(tdq); 2498 if (td) { 2499 tdq_runq_rem(tdq, td); 2500 tdq->tdq_lowpri = td->td_priority; 2501 return (td); 2502 } 2503 tdq->tdq_lowpri = PRI_MAX_IDLE; 2504 return (PCPU_GET(idlethread)); 2505 } 2506 2507 /* 2508 * Set owepreempt if necessary. Preemption never happens directly in ULE, 2509 * we always request it once we exit a critical section. 2510 */ 2511 static inline void 2512 sched_setpreempt(struct thread *td) 2513 { 2514 struct thread *ctd; 2515 int cpri; 2516 int pri; 2517 2518 THREAD_LOCK_ASSERT(curthread, MA_OWNED); 2519 2520 ctd = curthread; 2521 pri = td->td_priority; 2522 cpri = ctd->td_priority; 2523 if (pri < cpri) 2524 ctd->td_flags |= TDF_NEEDRESCHED; 2525 if (panicstr != NULL || pri >= cpri || cold || TD_IS_INHIBITED(ctd)) 2526 return; 2527 if (!sched_shouldpreempt(pri, cpri, 0)) 2528 return; 2529 ctd->td_owepreempt = 1; 2530 } 2531 2532 /* 2533 * Add a thread to a thread queue. Select the appropriate runq and add the 2534 * thread to it. This is the internal function called when the tdq is 2535 * predetermined. 2536 */ 2537 void 2538 tdq_add(struct tdq *tdq, struct thread *td, int flags) 2539 { 2540 2541 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2542 KASSERT((td->td_inhibitors == 0), 2543 ("sched_add: trying to run inhibited thread")); 2544 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 2545 ("sched_add: bad thread state")); 2546 KASSERT(td->td_flags & TDF_INMEM, 2547 ("sched_add: thread swapped out")); 2548 2549 if (td->td_priority < tdq->tdq_lowpri) 2550 tdq->tdq_lowpri = td->td_priority; 2551 tdq_runq_add(tdq, td, flags); 2552 tdq_load_add(tdq, td); 2553 } 2554 2555 /* 2556 * Select the target thread queue and add a thread to it. Request 2557 * preemption or IPI a remote processor if required. 2558 */ 2559 void 2560 sched_add(struct thread *td, int flags) 2561 { 2562 struct tdq *tdq; 2563 #ifdef SMP 2564 int cpu; 2565 #endif 2566 2567 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 2568 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 2569 sched_tdname(curthread)); 2570 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 2571 KTR_ATTR_LINKED, sched_tdname(td)); 2572 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 2573 flags & SRQ_PREEMPTED); 2574 THREAD_LOCK_ASSERT(td, MA_OWNED); 2575 /* 2576 * Recalculate the priority before we select the target cpu or 2577 * run-queue. 2578 */ 2579 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 2580 sched_priority(td); 2581 #ifdef SMP 2582 /* 2583 * Pick the destination cpu and if it isn't ours transfer to the 2584 * target cpu. 2585 */ 2586 cpu = sched_pickcpu(td, flags); 2587 tdq = sched_setcpu(td, cpu, flags); 2588 tdq_add(tdq, td, flags); 2589 if (cpu != PCPU_GET(cpuid)) { 2590 tdq_notify(tdq, td); 2591 return; 2592 } 2593 #else 2594 tdq = TDQ_SELF(); 2595 TDQ_LOCK(tdq); 2596 /* 2597 * Now that the thread is moving to the run-queue, set the lock 2598 * to the scheduler's lock. 2599 */ 2600 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 2601 tdq_add(tdq, td, flags); 2602 #endif 2603 if (!(flags & SRQ_YIELDING)) 2604 sched_setpreempt(td); 2605 } 2606 2607 /* 2608 * Remove a thread from a run-queue without running it. This is used 2609 * when we're stealing a thread from a remote queue. Otherwise all threads 2610 * exit by calling sched_exit_thread() and sched_throw() themselves. 2611 */ 2612 void 2613 sched_rem(struct thread *td) 2614 { 2615 struct tdq *tdq; 2616 2617 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "runq rem", 2618 "prio:%d", td->td_priority); 2619 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL); 2620 tdq = TDQ_CPU(td_get_sched(td)->ts_cpu); 2621 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2622 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2623 KASSERT(TD_ON_RUNQ(td), 2624 ("sched_rem: thread not on run queue")); 2625 tdq_runq_rem(tdq, td); 2626 tdq_load_rem(tdq, td); 2627 TD_SET_CAN_RUN(td); 2628 if (td->td_priority == tdq->tdq_lowpri) 2629 tdq_setlowpri(tdq, NULL); 2630 } 2631 2632 /* 2633 * Fetch cpu utilization information. Updates on demand. 2634 */ 2635 fixpt_t 2636 sched_pctcpu(struct thread *td) 2637 { 2638 fixpt_t pctcpu; 2639 struct td_sched *ts; 2640 2641 pctcpu = 0; 2642 ts = td_get_sched(td); 2643 2644 THREAD_LOCK_ASSERT(td, MA_OWNED); 2645 sched_pctcpu_update(ts, TD_IS_RUNNING(td)); 2646 if (ts->ts_ticks) { 2647 int rtick; 2648 2649 /* How many rtick per second ? */ 2650 rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz); 2651 pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT; 2652 } 2653 2654 return (pctcpu); 2655 } 2656 2657 /* 2658 * Enforce affinity settings for a thread. Called after adjustments to 2659 * cpumask. 2660 */ 2661 void 2662 sched_affinity(struct thread *td) 2663 { 2664 #ifdef SMP 2665 struct td_sched *ts; 2666 2667 THREAD_LOCK_ASSERT(td, MA_OWNED); 2668 ts = td_get_sched(td); 2669 if (THREAD_CAN_SCHED(td, ts->ts_cpu)) 2670 return; 2671 if (TD_ON_RUNQ(td)) { 2672 sched_rem(td); 2673 sched_add(td, SRQ_BORING); 2674 return; 2675 } 2676 if (!TD_IS_RUNNING(td)) 2677 return; 2678 /* 2679 * Force a switch before returning to userspace. If the 2680 * target thread is not running locally send an ipi to force 2681 * the issue. 2682 */ 2683 td->td_flags |= TDF_NEEDRESCHED; 2684 if (td != curthread) 2685 ipi_cpu(ts->ts_cpu, IPI_PREEMPT); 2686 #endif 2687 } 2688 2689 /* 2690 * Bind a thread to a target cpu. 2691 */ 2692 void 2693 sched_bind(struct thread *td, int cpu) 2694 { 2695 struct td_sched *ts; 2696 2697 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 2698 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 2699 ts = td_get_sched(td); 2700 if (ts->ts_flags & TSF_BOUND) 2701 sched_unbind(td); 2702 KASSERT(THREAD_CAN_MIGRATE(td), ("%p must be migratable", td)); 2703 ts->ts_flags |= TSF_BOUND; 2704 sched_pin(); 2705 if (PCPU_GET(cpuid) == cpu) 2706 return; 2707 ts->ts_cpu = cpu; 2708 /* When we return from mi_switch we'll be on the correct cpu. */ 2709 mi_switch(SW_VOL, NULL); 2710 } 2711 2712 /* 2713 * Release a bound thread. 2714 */ 2715 void 2716 sched_unbind(struct thread *td) 2717 { 2718 struct td_sched *ts; 2719 2720 THREAD_LOCK_ASSERT(td, MA_OWNED); 2721 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 2722 ts = td_get_sched(td); 2723 if ((ts->ts_flags & TSF_BOUND) == 0) 2724 return; 2725 ts->ts_flags &= ~TSF_BOUND; 2726 sched_unpin(); 2727 } 2728 2729 int 2730 sched_is_bound(struct thread *td) 2731 { 2732 THREAD_LOCK_ASSERT(td, MA_OWNED); 2733 return (td_get_sched(td)->ts_flags & TSF_BOUND); 2734 } 2735 2736 /* 2737 * Basic yield call. 2738 */ 2739 void 2740 sched_relinquish(struct thread *td) 2741 { 2742 thread_lock(td); 2743 mi_switch(SW_VOL | SWT_RELINQUISH, NULL); 2744 thread_unlock(td); 2745 } 2746 2747 /* 2748 * Return the total system load. 2749 */ 2750 int 2751 sched_load(void) 2752 { 2753 #ifdef SMP 2754 int total; 2755 int i; 2756 2757 total = 0; 2758 CPU_FOREACH(i) 2759 total += TDQ_CPU(i)->tdq_sysload; 2760 return (total); 2761 #else 2762 return (TDQ_SELF()->tdq_sysload); 2763 #endif 2764 } 2765 2766 int 2767 sched_sizeof_proc(void) 2768 { 2769 return (sizeof(struct proc)); 2770 } 2771 2772 int 2773 sched_sizeof_thread(void) 2774 { 2775 return (sizeof(struct thread) + sizeof(struct td_sched)); 2776 } 2777 2778 #ifdef SMP 2779 #define TDQ_IDLESPIN(tdq) \ 2780 ((tdq)->tdq_cg != NULL && ((tdq)->tdq_cg->cg_flags & CG_FLAG_THREAD) == 0) 2781 #else 2782 #define TDQ_IDLESPIN(tdq) 1 2783 #endif 2784 2785 /* 2786 * The actual idle process. 2787 */ 2788 void 2789 sched_idletd(void *dummy) 2790 { 2791 struct thread *td; 2792 struct tdq *tdq; 2793 int oldswitchcnt, switchcnt; 2794 int i; 2795 2796 mtx_assert(&Giant, MA_NOTOWNED); 2797 td = curthread; 2798 tdq = TDQ_SELF(); 2799 THREAD_NO_SLEEPING(); 2800 oldswitchcnt = -1; 2801 for (;;) { 2802 if (tdq->tdq_load) { 2803 thread_lock(td); 2804 mi_switch(SW_VOL | SWT_IDLE, NULL); 2805 thread_unlock(td); 2806 } 2807 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2808 #ifdef SMP 2809 if (always_steal || switchcnt != oldswitchcnt) { 2810 oldswitchcnt = switchcnt; 2811 if (tdq_idled(tdq) == 0) 2812 continue; 2813 } 2814 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2815 #else 2816 oldswitchcnt = switchcnt; 2817 #endif 2818 /* 2819 * If we're switching very frequently, spin while checking 2820 * for load rather than entering a low power state that 2821 * may require an IPI. However, don't do any busy 2822 * loops while on SMT machines as this simply steals 2823 * cycles from cores doing useful work. 2824 */ 2825 if (TDQ_IDLESPIN(tdq) && switchcnt > sched_idlespinthresh) { 2826 for (i = 0; i < sched_idlespins; i++) { 2827 if (tdq->tdq_load) 2828 break; 2829 cpu_spinwait(); 2830 } 2831 } 2832 2833 /* If there was context switch during spin, restart it. */ 2834 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2835 if (tdq->tdq_load != 0 || switchcnt != oldswitchcnt) 2836 continue; 2837 2838 /* Run main MD idle handler. */ 2839 tdq->tdq_cpu_idle = 1; 2840 /* 2841 * Make sure that tdq_cpu_idle update is globally visible 2842 * before cpu_idle() read tdq_load. The order is important 2843 * to avoid race with tdq_notify. 2844 */ 2845 atomic_thread_fence_seq_cst(); 2846 /* 2847 * Checking for again after the fence picks up assigned 2848 * threads often enough to make it worthwhile to do so in 2849 * order to avoid calling cpu_idle(). 2850 */ 2851 if (tdq->tdq_load != 0) { 2852 tdq->tdq_cpu_idle = 0; 2853 continue; 2854 } 2855 cpu_idle(switchcnt * 4 > sched_idlespinthresh); 2856 tdq->tdq_cpu_idle = 0; 2857 2858 /* 2859 * Account thread-less hardware interrupts and 2860 * other wakeup reasons equal to context switches. 2861 */ 2862 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2863 if (switchcnt != oldswitchcnt) 2864 continue; 2865 tdq->tdq_switchcnt++; 2866 oldswitchcnt++; 2867 } 2868 } 2869 2870 /* 2871 * A CPU is entering for the first time or a thread is exiting. 2872 */ 2873 void 2874 sched_throw(struct thread *td) 2875 { 2876 struct thread *newtd; 2877 struct tdq *tdq; 2878 2879 if (td == NULL) { 2880 #ifdef SMP 2881 PCPU_SET(sched, DPCPU_PTR(tdq)); 2882 #endif 2883 /* Correct spinlock nesting and acquire the correct lock. */ 2884 tdq = TDQ_SELF(); 2885 TDQ_LOCK(tdq); 2886 spinlock_exit(); 2887 PCPU_SET(switchtime, cpu_ticks()); 2888 PCPU_SET(switchticks, ticks); 2889 } else { 2890 tdq = TDQ_SELF(); 2891 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2892 tdq_load_rem(tdq, td); 2893 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 2894 td->td_lastcpu = td->td_oncpu; 2895 td->td_oncpu = NOCPU; 2896 } 2897 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 2898 newtd = choosethread(); 2899 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 2900 cpu_throw(td, newtd); /* doesn't return */ 2901 } 2902 2903 /* 2904 * This is called from fork_exit(). Just acquire the correct locks and 2905 * let fork do the rest of the work. 2906 */ 2907 void 2908 sched_fork_exit(struct thread *td) 2909 { 2910 struct tdq *tdq; 2911 int cpuid; 2912 2913 /* 2914 * Finish setting up thread glue so that it begins execution in a 2915 * non-nested critical section with the scheduler lock held. 2916 */ 2917 cpuid = PCPU_GET(cpuid); 2918 tdq = TDQ_SELF(); 2919 if (TD_IS_IDLETHREAD(td)) 2920 td->td_lock = TDQ_LOCKPTR(tdq); 2921 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2922 td->td_oncpu = cpuid; 2923 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 2924 lock_profile_obtain_lock_success( 2925 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 2926 2927 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running", 2928 "prio:%d", td->td_priority); 2929 SDT_PROBE0(sched, , , on__cpu); 2930 } 2931 2932 /* 2933 * Create on first use to catch odd startup conditons. 2934 */ 2935 char * 2936 sched_tdname(struct thread *td) 2937 { 2938 #ifdef KTR 2939 struct td_sched *ts; 2940 2941 ts = td_get_sched(td); 2942 if (ts->ts_name[0] == '\0') 2943 snprintf(ts->ts_name, sizeof(ts->ts_name), 2944 "%s tid %d", td->td_name, td->td_tid); 2945 return (ts->ts_name); 2946 #else 2947 return (td->td_name); 2948 #endif 2949 } 2950 2951 #ifdef KTR 2952 void 2953 sched_clear_tdname(struct thread *td) 2954 { 2955 struct td_sched *ts; 2956 2957 ts = td_get_sched(td); 2958 ts->ts_name[0] = '\0'; 2959 } 2960 #endif 2961 2962 #ifdef SMP 2963 2964 /* 2965 * Build the CPU topology dump string. Is recursively called to collect 2966 * the topology tree. 2967 */ 2968 static int 2969 sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, struct cpu_group *cg, 2970 int indent) 2971 { 2972 char cpusetbuf[CPUSETBUFSIZ]; 2973 int i, first; 2974 2975 sbuf_printf(sb, "%*s<group level=\"%d\" cache-level=\"%d\">\n", indent, 2976 "", 1 + indent / 2, cg->cg_level); 2977 sbuf_printf(sb, "%*s <cpu count=\"%d\" mask=\"%s\">", indent, "", 2978 cg->cg_count, cpusetobj_strprint(cpusetbuf, &cg->cg_mask)); 2979 first = TRUE; 2980 for (i = 0; i < MAXCPU; i++) { 2981 if (CPU_ISSET(i, &cg->cg_mask)) { 2982 if (!first) 2983 sbuf_printf(sb, ", "); 2984 else 2985 first = FALSE; 2986 sbuf_printf(sb, "%d", i); 2987 } 2988 } 2989 sbuf_printf(sb, "</cpu>\n"); 2990 2991 if (cg->cg_flags != 0) { 2992 sbuf_printf(sb, "%*s <flags>", indent, ""); 2993 if ((cg->cg_flags & CG_FLAG_HTT) != 0) 2994 sbuf_printf(sb, "<flag name=\"HTT\">HTT group</flag>"); 2995 if ((cg->cg_flags & CG_FLAG_THREAD) != 0) 2996 sbuf_printf(sb, "<flag name=\"THREAD\">THREAD group</flag>"); 2997 if ((cg->cg_flags & CG_FLAG_SMT) != 0) 2998 sbuf_printf(sb, "<flag name=\"SMT\">SMT group</flag>"); 2999 sbuf_printf(sb, "</flags>\n"); 3000 } 3001 3002 if (cg->cg_children > 0) { 3003 sbuf_printf(sb, "%*s <children>\n", indent, ""); 3004 for (i = 0; i < cg->cg_children; i++) 3005 sysctl_kern_sched_topology_spec_internal(sb, 3006 &cg->cg_child[i], indent+2); 3007 sbuf_printf(sb, "%*s </children>\n", indent, ""); 3008 } 3009 sbuf_printf(sb, "%*s</group>\n", indent, ""); 3010 return (0); 3011 } 3012 3013 /* 3014 * Sysctl handler for retrieving topology dump. It's a wrapper for 3015 * the recursive sysctl_kern_smp_topology_spec_internal(). 3016 */ 3017 static int 3018 sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS) 3019 { 3020 struct sbuf *topo; 3021 int err; 3022 3023 KASSERT(cpu_top != NULL, ("cpu_top isn't initialized")); 3024 3025 topo = sbuf_new_for_sysctl(NULL, NULL, 512, req); 3026 if (topo == NULL) 3027 return (ENOMEM); 3028 3029 sbuf_printf(topo, "<groups>\n"); 3030 err = sysctl_kern_sched_topology_spec_internal(topo, cpu_top, 1); 3031 sbuf_printf(topo, "</groups>\n"); 3032 3033 if (err == 0) { 3034 err = sbuf_finish(topo); 3035 } 3036 sbuf_delete(topo); 3037 return (err); 3038 } 3039 3040 #endif 3041 3042 static int 3043 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 3044 { 3045 int error, new_val, period; 3046 3047 period = 1000000 / realstathz; 3048 new_val = period * sched_slice; 3049 error = sysctl_handle_int(oidp, &new_val, 0, req); 3050 if (error != 0 || req->newptr == NULL) 3051 return (error); 3052 if (new_val <= 0) 3053 return (EINVAL); 3054 sched_slice = imax(1, (new_val + period / 2) / period); 3055 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 3056 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 3057 realstathz); 3058 return (0); 3059 } 3060 3061 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0, "Scheduler"); 3062 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0, 3063 "Scheduler name"); 3064 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW, 3065 NULL, 0, sysctl_kern_quantum, "I", 3066 "Quantum for timeshare threads in microseconds"); 3067 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, 3068 "Quantum for timeshare threads in stathz ticks"); 3069 SYSCTL_INT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0, 3070 "Interactivity score threshold"); 3071 SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW, 3072 &preempt_thresh, 0, 3073 "Maximal (lowest) priority for preemption"); 3074 SYSCTL_INT(_kern_sched, OID_AUTO, static_boost, CTLFLAG_RW, &static_boost, 0, 3075 "Assign static kernel priorities to sleeping threads"); 3076 SYSCTL_INT(_kern_sched, OID_AUTO, idlespins, CTLFLAG_RW, &sched_idlespins, 0, 3077 "Number of times idle thread will spin waiting for new work"); 3078 SYSCTL_INT(_kern_sched, OID_AUTO, idlespinthresh, CTLFLAG_RW, 3079 &sched_idlespinthresh, 0, 3080 "Threshold before we will permit idle thread spinning"); 3081 #ifdef SMP 3082 SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0, 3083 "Number of hz ticks to keep thread affinity for"); 3084 SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0, 3085 "Enables the long-term load balancer"); 3086 SYSCTL_INT(_kern_sched, OID_AUTO, balance_interval, CTLFLAG_RW, 3087 &balance_interval, 0, 3088 "Average period in stathz ticks to run the long-term balancer"); 3089 SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0, 3090 "Attempts to steal work from other cores before idling"); 3091 SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0, 3092 "Minimum load on remote CPU before we'll steal"); 3093 SYSCTL_INT(_kern_sched, OID_AUTO, trysteal_limit, CTLFLAG_RW, &trysteal_limit, 3094 0, "Topological distance limit for stealing threads in sched_switch()"); 3095 SYSCTL_INT(_kern_sched, OID_AUTO, always_steal, CTLFLAG_RW, &always_steal, 0, 3096 "Always run the stealer from the idle thread"); 3097 SYSCTL_PROC(_kern_sched, OID_AUTO, topology_spec, CTLTYPE_STRING | 3098 CTLFLAG_MPSAFE | CTLFLAG_RD, NULL, 0, sysctl_kern_sched_topology_spec, "A", 3099 "XML dump of detected CPU topology"); 3100 #endif 3101 3102 /* ps compat. All cpu percentages from ULE are weighted. */ 3103 static int ccpu = 0; 3104 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 3105