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 static __always_inline int cpu_search(const struct cpu_group *cg, 647 struct cpu_search *low, struct cpu_search *high, const int match); 648 int __noinline cpu_search_lowest(const struct cpu_group *cg, 649 struct cpu_search *low); 650 int __noinline cpu_search_highest(const struct cpu_group *cg, 651 struct cpu_search *high); 652 int __noinline cpu_search_both(const struct cpu_group *cg, 653 struct cpu_search *low, struct cpu_search *high); 654 655 /* 656 * Search the tree of cpu_groups for the lowest or highest loaded cpu 657 * according to the match argument. This routine actually compares the 658 * load on all paths through the tree and finds the least loaded cpu on 659 * the least loaded path, which may differ from the least loaded cpu in 660 * the system. This balances work among caches and buses. 661 * 662 * This inline is instantiated in three forms below using constants for the 663 * match argument. It is reduced to the minimum set for each case. It is 664 * also recursive to the depth of the tree. 665 */ 666 static __always_inline int 667 cpu_search(const struct cpu_group *cg, struct cpu_search *low, 668 struct cpu_search *high, const int match) 669 { 670 struct cpu_search lgroup; 671 struct cpu_search hgroup; 672 cpuset_t cpumask; 673 struct cpu_group *child; 674 struct tdq *tdq; 675 int cpu, i, hload, lload, load, total, rnd; 676 677 total = 0; 678 cpumask = cg->cg_mask; 679 if (match & CPU_SEARCH_LOWEST) { 680 lload = INT_MAX; 681 lgroup = *low; 682 } 683 if (match & CPU_SEARCH_HIGHEST) { 684 hload = INT_MIN; 685 hgroup = *high; 686 } 687 688 /* Iterate through the child CPU groups and then remaining CPUs. */ 689 for (i = cg->cg_children, cpu = mp_maxid; ; ) { 690 if (i == 0) { 691 #ifdef HAVE_INLINE_FFSL 692 cpu = CPU_FFS(&cpumask) - 1; 693 #else 694 while (cpu >= 0 && !CPU_ISSET(cpu, &cpumask)) 695 cpu--; 696 #endif 697 if (cpu < 0) 698 break; 699 child = NULL; 700 } else 701 child = &cg->cg_child[i - 1]; 702 703 if (match & CPU_SEARCH_LOWEST) 704 lgroup.cs_cpu = -1; 705 if (match & CPU_SEARCH_HIGHEST) 706 hgroup.cs_cpu = -1; 707 if (child) { /* Handle child CPU group. */ 708 CPU_NAND(&cpumask, &child->cg_mask); 709 switch (match) { 710 case CPU_SEARCH_LOWEST: 711 load = cpu_search_lowest(child, &lgroup); 712 break; 713 case CPU_SEARCH_HIGHEST: 714 load = cpu_search_highest(child, &hgroup); 715 break; 716 case CPU_SEARCH_BOTH: 717 load = cpu_search_both(child, &lgroup, &hgroup); 718 break; 719 } 720 } else { /* Handle child CPU. */ 721 CPU_CLR(cpu, &cpumask); 722 tdq = TDQ_CPU(cpu); 723 load = tdq->tdq_load * 256; 724 rnd = sched_random() % 32; 725 if (match & CPU_SEARCH_LOWEST) { 726 if (cpu == low->cs_prefer) 727 load -= 64; 728 /* If that CPU is allowed and get data. */ 729 if (tdq->tdq_lowpri > lgroup.cs_pri && 730 tdq->tdq_load <= lgroup.cs_limit && 731 CPU_ISSET(cpu, &lgroup.cs_mask)) { 732 lgroup.cs_cpu = cpu; 733 lgroup.cs_load = load - rnd; 734 } 735 } 736 if (match & CPU_SEARCH_HIGHEST) 737 if (tdq->tdq_load >= hgroup.cs_limit && 738 tdq->tdq_transferable && 739 CPU_ISSET(cpu, &hgroup.cs_mask)) { 740 hgroup.cs_cpu = cpu; 741 hgroup.cs_load = load - rnd; 742 } 743 } 744 total += load; 745 746 /* We have info about child item. Compare it. */ 747 if (match & CPU_SEARCH_LOWEST) { 748 if (lgroup.cs_cpu >= 0 && 749 (load < lload || 750 (load == lload && lgroup.cs_load < low->cs_load))) { 751 lload = load; 752 low->cs_cpu = lgroup.cs_cpu; 753 low->cs_load = lgroup.cs_load; 754 } 755 } 756 if (match & CPU_SEARCH_HIGHEST) 757 if (hgroup.cs_cpu >= 0 && 758 (load > hload || 759 (load == hload && hgroup.cs_load > high->cs_load))) { 760 hload = load; 761 high->cs_cpu = hgroup.cs_cpu; 762 high->cs_load = hgroup.cs_load; 763 } 764 if (child) { 765 i--; 766 if (i == 0 && CPU_EMPTY(&cpumask)) 767 break; 768 } 769 #ifndef HAVE_INLINE_FFSL 770 else 771 cpu--; 772 #endif 773 } 774 return (total); 775 } 776 777 /* 778 * cpu_search instantiations must pass constants to maintain the inline 779 * optimization. 780 */ 781 int 782 cpu_search_lowest(const struct cpu_group *cg, struct cpu_search *low) 783 { 784 return cpu_search(cg, low, NULL, CPU_SEARCH_LOWEST); 785 } 786 787 int 788 cpu_search_highest(const struct cpu_group *cg, struct cpu_search *high) 789 { 790 return cpu_search(cg, NULL, high, CPU_SEARCH_HIGHEST); 791 } 792 793 int 794 cpu_search_both(const struct cpu_group *cg, struct cpu_search *low, 795 struct cpu_search *high) 796 { 797 return cpu_search(cg, low, high, CPU_SEARCH_BOTH); 798 } 799 800 /* 801 * Find the cpu with the least load via the least loaded path that has a 802 * lowpri greater than pri pri. A pri of -1 indicates any priority is 803 * acceptable. 804 */ 805 static inline int 806 sched_lowest(const struct cpu_group *cg, cpuset_t mask, int pri, int maxload, 807 int prefer) 808 { 809 struct cpu_search low; 810 811 low.cs_cpu = -1; 812 low.cs_prefer = prefer; 813 low.cs_mask = mask; 814 low.cs_pri = pri; 815 low.cs_limit = maxload; 816 cpu_search_lowest(cg, &low); 817 return low.cs_cpu; 818 } 819 820 /* 821 * Find the cpu with the highest load via the highest loaded path. 822 */ 823 static inline int 824 sched_highest(const struct cpu_group *cg, cpuset_t mask, int minload) 825 { 826 struct cpu_search high; 827 828 high.cs_cpu = -1; 829 high.cs_mask = mask; 830 high.cs_limit = minload; 831 cpu_search_highest(cg, &high); 832 return high.cs_cpu; 833 } 834 835 static void 836 sched_balance_group(struct cpu_group *cg) 837 { 838 struct tdq *tdq; 839 cpuset_t hmask, lmask; 840 int high, low, anylow; 841 842 CPU_FILL(&hmask); 843 for (;;) { 844 high = sched_highest(cg, hmask, 2); 845 /* Stop if there is no more CPU with transferrable threads. */ 846 if (high == -1) 847 break; 848 CPU_CLR(high, &hmask); 849 CPU_COPY(&hmask, &lmask); 850 /* Stop if there is no more CPU left for low. */ 851 if (CPU_EMPTY(&lmask)) 852 break; 853 anylow = 1; 854 tdq = TDQ_CPU(high); 855 nextlow: 856 low = sched_lowest(cg, lmask, -1, tdq->tdq_load - 1, high); 857 /* Stop if we looked well and found no less loaded CPU. */ 858 if (anylow && low == -1) 859 break; 860 /* Go to next high if we found no less loaded CPU. */ 861 if (low == -1) 862 continue; 863 /* Transfer thread from high to low. */ 864 if (sched_balance_pair(tdq, TDQ_CPU(low))) { 865 /* CPU that got thread can no longer be a donor. */ 866 CPU_CLR(low, &hmask); 867 } else { 868 /* 869 * If failed, then there is no threads on high 870 * that can run on this low. Drop low from low 871 * mask and look for different one. 872 */ 873 CPU_CLR(low, &lmask); 874 anylow = 0; 875 goto nextlow; 876 } 877 } 878 } 879 880 static void 881 sched_balance(void) 882 { 883 struct tdq *tdq; 884 885 balance_ticks = max(balance_interval / 2, 1) + 886 (sched_random() % balance_interval); 887 tdq = TDQ_SELF(); 888 TDQ_UNLOCK(tdq); 889 sched_balance_group(cpu_top); 890 TDQ_LOCK(tdq); 891 } 892 893 /* 894 * Lock two thread queues using their address to maintain lock order. 895 */ 896 static void 897 tdq_lock_pair(struct tdq *one, struct tdq *two) 898 { 899 if (one < two) { 900 TDQ_LOCK(one); 901 TDQ_LOCK_FLAGS(two, MTX_DUPOK); 902 } else { 903 TDQ_LOCK(two); 904 TDQ_LOCK_FLAGS(one, MTX_DUPOK); 905 } 906 } 907 908 /* 909 * Unlock two thread queues. Order is not important here. 910 */ 911 static void 912 tdq_unlock_pair(struct tdq *one, struct tdq *two) 913 { 914 TDQ_UNLOCK(one); 915 TDQ_UNLOCK(two); 916 } 917 918 /* 919 * Transfer load between two imbalanced thread queues. 920 */ 921 static int 922 sched_balance_pair(struct tdq *high, struct tdq *low) 923 { 924 struct thread *td; 925 int cpu; 926 927 tdq_lock_pair(high, low); 928 td = NULL; 929 /* 930 * Transfer a thread from high to low. 931 */ 932 if (high->tdq_transferable != 0 && high->tdq_load > low->tdq_load && 933 (td = tdq_move(high, low)) != NULL) { 934 /* 935 * In case the target isn't the current cpu notify it of the 936 * new load, possibly sending an IPI to force it to reschedule. 937 */ 938 cpu = TDQ_ID(low); 939 if (cpu != PCPU_GET(cpuid)) 940 tdq_notify(low, td); 941 } 942 tdq_unlock_pair(high, low); 943 return (td != NULL); 944 } 945 946 /* 947 * Move a thread from one thread queue to another. 948 */ 949 static struct thread * 950 tdq_move(struct tdq *from, struct tdq *to) 951 { 952 struct td_sched *ts; 953 struct thread *td; 954 struct tdq *tdq; 955 int cpu; 956 957 TDQ_LOCK_ASSERT(from, MA_OWNED); 958 TDQ_LOCK_ASSERT(to, MA_OWNED); 959 960 tdq = from; 961 cpu = TDQ_ID(to); 962 td = tdq_steal(tdq, cpu); 963 if (td == NULL) 964 return (NULL); 965 ts = td_get_sched(td); 966 /* 967 * Although the run queue is locked the thread may be blocked. Lock 968 * it to clear this and acquire the run-queue lock. 969 */ 970 thread_lock(td); 971 /* Drop recursive lock on from acquired via thread_lock(). */ 972 TDQ_UNLOCK(from); 973 sched_rem(td); 974 ts->ts_cpu = cpu; 975 td->td_lock = TDQ_LOCKPTR(to); 976 tdq_add(to, td, SRQ_YIELDING); 977 return (td); 978 } 979 980 /* 981 * This tdq has idled. Try to steal a thread from another cpu and switch 982 * to it. 983 */ 984 static int 985 tdq_idled(struct tdq *tdq) 986 { 987 struct cpu_group *cg; 988 struct tdq *steal; 989 cpuset_t mask; 990 int cpu, switchcnt; 991 992 if (smp_started == 0 || steal_idle == 0 || tdq->tdq_cg == NULL) 993 return (1); 994 CPU_FILL(&mask); 995 CPU_CLR(PCPU_GET(cpuid), &mask); 996 restart: 997 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 998 for (cg = tdq->tdq_cg; ; ) { 999 cpu = sched_highest(cg, mask, steal_thresh); 1000 /* 1001 * We were assigned a thread but not preempted. Returning 1002 * 0 here will cause our caller to switch to it. 1003 */ 1004 if (tdq->tdq_load) 1005 return (0); 1006 if (cpu == -1) { 1007 cg = cg->cg_parent; 1008 if (cg == NULL) 1009 return (1); 1010 continue; 1011 } 1012 steal = TDQ_CPU(cpu); 1013 /* 1014 * The data returned by sched_highest() is stale and 1015 * the chosen CPU no longer has an eligible thread. 1016 * 1017 * Testing this ahead of tdq_lock_pair() only catches 1018 * this situation about 20% of the time on an 8 core 1019 * 16 thread Ryzen 7, but it still helps performance. 1020 */ 1021 if (steal->tdq_load < steal_thresh || 1022 steal->tdq_transferable == 0) 1023 goto restart; 1024 tdq_lock_pair(tdq, steal); 1025 /* 1026 * We were assigned a thread while waiting for the locks. 1027 * Switch to it now instead of stealing a thread. 1028 */ 1029 if (tdq->tdq_load) 1030 break; 1031 /* 1032 * The data returned by sched_highest() is stale and 1033 * the chosen CPU no longer has an eligible thread, or 1034 * we were preempted and the CPU loading info may be out 1035 * of date. The latter is rare. In either case restart 1036 * the search. 1037 */ 1038 if (steal->tdq_load < steal_thresh || 1039 steal->tdq_transferable == 0 || 1040 switchcnt != tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt) { 1041 tdq_unlock_pair(tdq, steal); 1042 goto restart; 1043 } 1044 /* 1045 * Steal the thread and switch to it. 1046 */ 1047 if (tdq_move(steal, tdq) != NULL) 1048 break; 1049 /* 1050 * We failed to acquire a thread even though it looked 1051 * like one was available. This could be due to affinity 1052 * restrictions or for other reasons. Loop again after 1053 * removing this CPU from the set. The restart logic 1054 * above does not restore this CPU to the set due to the 1055 * likelyhood of failing here again. 1056 */ 1057 CPU_CLR(cpu, &mask); 1058 tdq_unlock_pair(tdq, steal); 1059 } 1060 TDQ_UNLOCK(steal); 1061 mi_switch(SW_VOL | SWT_IDLE, NULL); 1062 thread_unlock(curthread); 1063 return (0); 1064 } 1065 1066 /* 1067 * Notify a remote cpu of new work. Sends an IPI if criteria are met. 1068 */ 1069 static void 1070 tdq_notify(struct tdq *tdq, struct thread *td) 1071 { 1072 struct thread *ctd; 1073 int pri; 1074 int cpu; 1075 1076 if (tdq->tdq_ipipending) 1077 return; 1078 cpu = td_get_sched(td)->ts_cpu; 1079 pri = td->td_priority; 1080 ctd = pcpu_find(cpu)->pc_curthread; 1081 if (!sched_shouldpreempt(pri, ctd->td_priority, 1)) 1082 return; 1083 1084 /* 1085 * Make sure that our caller's earlier update to tdq_load is 1086 * globally visible before we read tdq_cpu_idle. Idle thread 1087 * accesses both of them without locks, and the order is important. 1088 */ 1089 atomic_thread_fence_seq_cst(); 1090 1091 if (TD_IS_IDLETHREAD(ctd)) { 1092 /* 1093 * If the MD code has an idle wakeup routine try that before 1094 * falling back to IPI. 1095 */ 1096 if (!tdq->tdq_cpu_idle || cpu_idle_wakeup(cpu)) 1097 return; 1098 } 1099 tdq->tdq_ipipending = 1; 1100 ipi_cpu(cpu, IPI_PREEMPT); 1101 } 1102 1103 /* 1104 * Steals load from a timeshare queue. Honors the rotating queue head 1105 * index. 1106 */ 1107 static struct thread * 1108 runq_steal_from(struct runq *rq, int cpu, u_char start) 1109 { 1110 struct rqbits *rqb; 1111 struct rqhead *rqh; 1112 struct thread *td, *first; 1113 int bit; 1114 int i; 1115 1116 rqb = &rq->rq_status; 1117 bit = start & (RQB_BPW -1); 1118 first = NULL; 1119 again: 1120 for (i = RQB_WORD(start); i < RQB_LEN; bit = 0, i++) { 1121 if (rqb->rqb_bits[i] == 0) 1122 continue; 1123 if (bit == 0) 1124 bit = RQB_FFS(rqb->rqb_bits[i]); 1125 for (; bit < RQB_BPW; bit++) { 1126 if ((rqb->rqb_bits[i] & (1ul << bit)) == 0) 1127 continue; 1128 rqh = &rq->rq_queues[bit + (i << RQB_L2BPW)]; 1129 TAILQ_FOREACH(td, rqh, td_runq) { 1130 if (first && THREAD_CAN_MIGRATE(td) && 1131 THREAD_CAN_SCHED(td, cpu)) 1132 return (td); 1133 first = td; 1134 } 1135 } 1136 } 1137 if (start != 0) { 1138 start = 0; 1139 goto again; 1140 } 1141 1142 if (first && THREAD_CAN_MIGRATE(first) && 1143 THREAD_CAN_SCHED(first, cpu)) 1144 return (first); 1145 return (NULL); 1146 } 1147 1148 /* 1149 * Steals load from a standard linear queue. 1150 */ 1151 static struct thread * 1152 runq_steal(struct runq *rq, int cpu) 1153 { 1154 struct rqhead *rqh; 1155 struct rqbits *rqb; 1156 struct thread *td; 1157 int word; 1158 int bit; 1159 1160 rqb = &rq->rq_status; 1161 for (word = 0; word < RQB_LEN; word++) { 1162 if (rqb->rqb_bits[word] == 0) 1163 continue; 1164 for (bit = 0; bit < RQB_BPW; bit++) { 1165 if ((rqb->rqb_bits[word] & (1ul << bit)) == 0) 1166 continue; 1167 rqh = &rq->rq_queues[bit + (word << RQB_L2BPW)]; 1168 TAILQ_FOREACH(td, rqh, td_runq) 1169 if (THREAD_CAN_MIGRATE(td) && 1170 THREAD_CAN_SCHED(td, cpu)) 1171 return (td); 1172 } 1173 } 1174 return (NULL); 1175 } 1176 1177 /* 1178 * Attempt to steal a thread in priority order from a thread queue. 1179 */ 1180 static struct thread * 1181 tdq_steal(struct tdq *tdq, int cpu) 1182 { 1183 struct thread *td; 1184 1185 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1186 if ((td = runq_steal(&tdq->tdq_realtime, cpu)) != NULL) 1187 return (td); 1188 if ((td = runq_steal_from(&tdq->tdq_timeshare, 1189 cpu, tdq->tdq_ridx)) != NULL) 1190 return (td); 1191 return (runq_steal(&tdq->tdq_idle, cpu)); 1192 } 1193 1194 /* 1195 * Sets the thread lock and ts_cpu to match the requested cpu. Unlocks the 1196 * current lock and returns with the assigned queue locked. 1197 */ 1198 static inline struct tdq * 1199 sched_setcpu(struct thread *td, int cpu, int flags) 1200 { 1201 1202 struct tdq *tdq; 1203 1204 THREAD_LOCK_ASSERT(td, MA_OWNED); 1205 tdq = TDQ_CPU(cpu); 1206 td_get_sched(td)->ts_cpu = cpu; 1207 /* 1208 * If the lock matches just return the queue. 1209 */ 1210 if (td->td_lock == TDQ_LOCKPTR(tdq)) 1211 return (tdq); 1212 #ifdef notyet 1213 /* 1214 * If the thread isn't running its lockptr is a 1215 * turnstile or a sleepqueue. We can just lock_set without 1216 * blocking. 1217 */ 1218 if (TD_CAN_RUN(td)) { 1219 TDQ_LOCK(tdq); 1220 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 1221 return (tdq); 1222 } 1223 #endif 1224 /* 1225 * The hard case, migration, we need to block the thread first to 1226 * prevent order reversals with other cpus locks. 1227 */ 1228 spinlock_enter(); 1229 thread_lock_block(td); 1230 TDQ_LOCK(tdq); 1231 thread_lock_unblock(td, TDQ_LOCKPTR(tdq)); 1232 spinlock_exit(); 1233 return (tdq); 1234 } 1235 1236 SCHED_STAT_DEFINE(pickcpu_intrbind, "Soft interrupt binding"); 1237 SCHED_STAT_DEFINE(pickcpu_idle_affinity, "Picked idle cpu based on affinity"); 1238 SCHED_STAT_DEFINE(pickcpu_affinity, "Picked cpu based on affinity"); 1239 SCHED_STAT_DEFINE(pickcpu_lowest, "Selected lowest load"); 1240 SCHED_STAT_DEFINE(pickcpu_local, "Migrated to current cpu"); 1241 SCHED_STAT_DEFINE(pickcpu_migration, "Selection may have caused migration"); 1242 1243 static int 1244 sched_pickcpu(struct thread *td, int flags) 1245 { 1246 struct cpu_group *cg, *ccg; 1247 struct td_sched *ts; 1248 struct tdq *tdq; 1249 cpuset_t mask; 1250 int cpu, pri, self, intr; 1251 1252 self = PCPU_GET(cpuid); 1253 ts = td_get_sched(td); 1254 KASSERT(!CPU_ABSENT(ts->ts_cpu), ("sched_pickcpu: Start scheduler on " 1255 "absent CPU %d for thread %s.", ts->ts_cpu, td->td_name)); 1256 if (smp_started == 0) 1257 return (self); 1258 /* 1259 * Don't migrate a running thread from sched_switch(). 1260 */ 1261 if ((flags & SRQ_OURSELF) || !THREAD_CAN_MIGRATE(td)) 1262 return (ts->ts_cpu); 1263 /* 1264 * Prefer to run interrupt threads on the processors that generate 1265 * the interrupt. 1266 */ 1267 if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_SCHED(td, self) && 1268 curthread->td_intr_nesting_level) { 1269 tdq = TDQ_SELF(); 1270 if (tdq->tdq_lowpri >= PRI_MIN_IDLE) { 1271 SCHED_STAT_INC(pickcpu_idle_affinity); 1272 return (self); 1273 } 1274 ts->ts_cpu = self; 1275 intr = 1; 1276 cg = tdq->tdq_cg; 1277 goto llc; 1278 } else { 1279 intr = 0; 1280 tdq = TDQ_CPU(ts->ts_cpu); 1281 cg = tdq->tdq_cg; 1282 } 1283 /* 1284 * If the thread can run on the last cpu and the affinity has not 1285 * expired and it is idle, run it there. 1286 */ 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 /* Check all SMT threads for being idle. */ 1292 for (cpu = CPU_FFS(&cg->cg_mask) - 1; ; cpu++) { 1293 if (CPU_ISSET(cpu, &cg->cg_mask) && 1294 TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE) 1295 break; 1296 if (cpu >= mp_maxid) { 1297 SCHED_STAT_INC(pickcpu_idle_affinity); 1298 return (ts->ts_cpu); 1299 } 1300 } 1301 } else { 1302 SCHED_STAT_INC(pickcpu_idle_affinity); 1303 return (ts->ts_cpu); 1304 } 1305 } 1306 llc: 1307 /* 1308 * Search for the last level cache CPU group in the tree. 1309 * Skip SMT, identical groups and caches with expired affinity. 1310 * Interrupt threads affinity is explicit and never expires. 1311 */ 1312 for (ccg = NULL; cg != NULL; cg = cg->cg_parent) { 1313 if (cg->cg_flags & CG_FLAG_THREAD) 1314 continue; 1315 if (cg->cg_children == 1 || cg->cg_count == 1) 1316 continue; 1317 if (cg->cg_level == CG_SHARE_NONE || 1318 (!intr && !SCHED_AFFINITY(ts, cg->cg_level))) 1319 continue; 1320 ccg = cg; 1321 } 1322 /* Found LLC shared by all CPUs, so do a global search. */ 1323 if (ccg == cpu_top) 1324 ccg = NULL; 1325 cpu = -1; 1326 mask = td->td_cpuset->cs_mask; 1327 pri = td->td_priority; 1328 /* 1329 * Try hard to keep interrupts within found LLC. Search the LLC for 1330 * the least loaded CPU we can run now. For NUMA systems it should 1331 * be within target domain, and it also reduces scheduling overhead. 1332 */ 1333 if (ccg != NULL && intr) { 1334 cpu = sched_lowest(ccg, mask, pri, INT_MAX, ts->ts_cpu); 1335 if (cpu >= 0) 1336 SCHED_STAT_INC(pickcpu_intrbind); 1337 } else 1338 /* Search the LLC for the least loaded idle CPU we can run now. */ 1339 if (ccg != NULL) { 1340 cpu = sched_lowest(ccg, mask, max(pri, PRI_MAX_TIMESHARE), 1341 INT_MAX, ts->ts_cpu); 1342 if (cpu >= 0) 1343 SCHED_STAT_INC(pickcpu_affinity); 1344 } 1345 /* Search globally for the least loaded CPU we can run now. */ 1346 if (cpu < 0) { 1347 cpu = sched_lowest(cpu_top, mask, pri, INT_MAX, ts->ts_cpu); 1348 if (cpu >= 0) 1349 SCHED_STAT_INC(pickcpu_lowest); 1350 } 1351 /* Search globally for the least loaded CPU. */ 1352 if (cpu < 0) { 1353 cpu = sched_lowest(cpu_top, mask, -1, INT_MAX, ts->ts_cpu); 1354 if (cpu >= 0) 1355 SCHED_STAT_INC(pickcpu_lowest); 1356 } 1357 KASSERT(cpu >= 0, ("sched_pickcpu: Failed to find a cpu.")); 1358 KASSERT(!CPU_ABSENT(cpu), ("sched_pickcpu: Picked absent CPU %d.", cpu)); 1359 /* 1360 * Compare the lowest loaded cpu to current cpu. 1361 */ 1362 tdq = TDQ_CPU(cpu); 1363 if (THREAD_CAN_SCHED(td, self) && TDQ_SELF()->tdq_lowpri > pri && 1364 tdq->tdq_lowpri < PRI_MIN_IDLE && 1365 TDQ_SELF()->tdq_load <= tdq->tdq_load + 1) { 1366 SCHED_STAT_INC(pickcpu_local); 1367 cpu = self; 1368 } 1369 if (cpu != ts->ts_cpu) 1370 SCHED_STAT_INC(pickcpu_migration); 1371 return (cpu); 1372 } 1373 #endif 1374 1375 /* 1376 * Pick the highest priority task we have and return it. 1377 */ 1378 static struct thread * 1379 tdq_choose(struct tdq *tdq) 1380 { 1381 struct thread *td; 1382 1383 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1384 td = runq_choose(&tdq->tdq_realtime); 1385 if (td != NULL) 1386 return (td); 1387 td = runq_choose_from(&tdq->tdq_timeshare, tdq->tdq_ridx); 1388 if (td != NULL) { 1389 KASSERT(td->td_priority >= PRI_MIN_BATCH, 1390 ("tdq_choose: Invalid priority on timeshare queue %d", 1391 td->td_priority)); 1392 return (td); 1393 } 1394 td = runq_choose(&tdq->tdq_idle); 1395 if (td != NULL) { 1396 KASSERT(td->td_priority >= PRI_MIN_IDLE, 1397 ("tdq_choose: Invalid priority on idle queue %d", 1398 td->td_priority)); 1399 return (td); 1400 } 1401 1402 return (NULL); 1403 } 1404 1405 /* 1406 * Initialize a thread queue. 1407 */ 1408 static void 1409 tdq_setup(struct tdq *tdq, int id) 1410 { 1411 1412 if (bootverbose) 1413 printf("ULE: setup cpu %d\n", id); 1414 runq_init(&tdq->tdq_realtime); 1415 runq_init(&tdq->tdq_timeshare); 1416 runq_init(&tdq->tdq_idle); 1417 tdq->tdq_id = id; 1418 snprintf(tdq->tdq_name, sizeof(tdq->tdq_name), 1419 "sched lock %d", (int)TDQ_ID(tdq)); 1420 mtx_init(&tdq->tdq_lock, tdq->tdq_name, "sched lock", 1421 MTX_SPIN | MTX_RECURSE); 1422 #ifdef KTR 1423 snprintf(tdq->tdq_loadname, sizeof(tdq->tdq_loadname), 1424 "CPU %d load", (int)TDQ_ID(tdq)); 1425 #endif 1426 } 1427 1428 #ifdef SMP 1429 static void 1430 sched_setup_smp(void) 1431 { 1432 struct tdq *tdq; 1433 int i; 1434 1435 cpu_top = smp_topo(); 1436 CPU_FOREACH(i) { 1437 tdq = DPCPU_ID_PTR(i, tdq); 1438 tdq_setup(tdq, i); 1439 tdq->tdq_cg = smp_topo_find(cpu_top, i); 1440 if (tdq->tdq_cg == NULL) 1441 panic("Can't find cpu group for %d\n", i); 1442 } 1443 PCPU_SET(sched, DPCPU_PTR(tdq)); 1444 balance_tdq = TDQ_SELF(); 1445 } 1446 #endif 1447 1448 /* 1449 * Setup the thread queues and initialize the topology based on MD 1450 * information. 1451 */ 1452 static void 1453 sched_setup(void *dummy) 1454 { 1455 struct tdq *tdq; 1456 1457 #ifdef SMP 1458 sched_setup_smp(); 1459 #else 1460 tdq_setup(TDQ_SELF(), 0); 1461 #endif 1462 tdq = TDQ_SELF(); 1463 1464 /* Add thread0's load since it's running. */ 1465 TDQ_LOCK(tdq); 1466 thread0.td_lock = TDQ_LOCKPTR(tdq); 1467 tdq_load_add(tdq, &thread0); 1468 tdq->tdq_lowpri = thread0.td_priority; 1469 TDQ_UNLOCK(tdq); 1470 } 1471 1472 /* 1473 * This routine determines time constants after stathz and hz are setup. 1474 */ 1475 /* ARGSUSED */ 1476 static void 1477 sched_initticks(void *dummy) 1478 { 1479 int incr; 1480 1481 realstathz = stathz ? stathz : hz; 1482 sched_slice = realstathz / SCHED_SLICE_DEFAULT_DIVISOR; 1483 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 1484 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 1485 realstathz); 1486 1487 /* 1488 * tickincr is shifted out by 10 to avoid rounding errors due to 1489 * hz not being evenly divisible by stathz on all platforms. 1490 */ 1491 incr = (hz << SCHED_TICK_SHIFT) / realstathz; 1492 /* 1493 * This does not work for values of stathz that are more than 1494 * 1 << SCHED_TICK_SHIFT * hz. In practice this does not happen. 1495 */ 1496 if (incr == 0) 1497 incr = 1; 1498 tickincr = incr; 1499 #ifdef SMP 1500 /* 1501 * Set the default balance interval now that we know 1502 * what realstathz is. 1503 */ 1504 balance_interval = realstathz; 1505 balance_ticks = balance_interval; 1506 affinity = SCHED_AFFINITY_DEFAULT; 1507 #endif 1508 if (sched_idlespinthresh < 0) 1509 sched_idlespinthresh = 2 * max(10000, 6 * hz) / realstathz; 1510 } 1511 1512 1513 /* 1514 * This is the core of the interactivity algorithm. Determines a score based 1515 * on past behavior. It is the ratio of sleep time to run time scaled to 1516 * a [0, 100] integer. This is the voluntary sleep time of a process, which 1517 * differs from the cpu usage because it does not account for time spent 1518 * waiting on a run-queue. Would be prettier if we had floating point. 1519 * 1520 * When a thread's sleep time is greater than its run time the 1521 * calculation is: 1522 * 1523 * scaling factor 1524 * interactivity score = --------------------- 1525 * sleep time / run time 1526 * 1527 * 1528 * When a thread's run time is greater than its sleep time the 1529 * calculation is: 1530 * 1531 * scaling factor 1532 * interactivity score = --------------------- + scaling factor 1533 * run time / sleep time 1534 */ 1535 static int 1536 sched_interact_score(struct thread *td) 1537 { 1538 struct td_sched *ts; 1539 int div; 1540 1541 ts = td_get_sched(td); 1542 /* 1543 * The score is only needed if this is likely to be an interactive 1544 * task. Don't go through the expense of computing it if there's 1545 * no chance. 1546 */ 1547 if (sched_interact <= SCHED_INTERACT_HALF && 1548 ts->ts_runtime >= ts->ts_slptime) 1549 return (SCHED_INTERACT_HALF); 1550 1551 if (ts->ts_runtime > ts->ts_slptime) { 1552 div = max(1, ts->ts_runtime / SCHED_INTERACT_HALF); 1553 return (SCHED_INTERACT_HALF + 1554 (SCHED_INTERACT_HALF - (ts->ts_slptime / div))); 1555 } 1556 if (ts->ts_slptime > ts->ts_runtime) { 1557 div = max(1, ts->ts_slptime / SCHED_INTERACT_HALF); 1558 return (ts->ts_runtime / div); 1559 } 1560 /* runtime == slptime */ 1561 if (ts->ts_runtime) 1562 return (SCHED_INTERACT_HALF); 1563 1564 /* 1565 * This can happen if slptime and runtime are 0. 1566 */ 1567 return (0); 1568 1569 } 1570 1571 /* 1572 * Scale the scheduling priority according to the "interactivity" of this 1573 * process. 1574 */ 1575 static void 1576 sched_priority(struct thread *td) 1577 { 1578 int score; 1579 int pri; 1580 1581 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 1582 return; 1583 /* 1584 * If the score is interactive we place the thread in the realtime 1585 * queue with a priority that is less than kernel and interrupt 1586 * priorities. These threads are not subject to nice restrictions. 1587 * 1588 * Scores greater than this are placed on the normal timeshare queue 1589 * where the priority is partially decided by the most recent cpu 1590 * utilization and the rest is decided by nice value. 1591 * 1592 * The nice value of the process has a linear effect on the calculated 1593 * score. Negative nice values make it easier for a thread to be 1594 * considered interactive. 1595 */ 1596 score = imax(0, sched_interact_score(td) + td->td_proc->p_nice); 1597 if (score < sched_interact) { 1598 pri = PRI_MIN_INTERACT; 1599 pri += ((PRI_MAX_INTERACT - PRI_MIN_INTERACT + 1) / 1600 sched_interact) * score; 1601 KASSERT(pri >= PRI_MIN_INTERACT && pri <= PRI_MAX_INTERACT, 1602 ("sched_priority: invalid interactive priority %d score %d", 1603 pri, score)); 1604 } else { 1605 pri = SCHED_PRI_MIN; 1606 if (td_get_sched(td)->ts_ticks) 1607 pri += min(SCHED_PRI_TICKS(td_get_sched(td)), 1608 SCHED_PRI_RANGE - 1); 1609 pri += SCHED_PRI_NICE(td->td_proc->p_nice); 1610 KASSERT(pri >= PRI_MIN_BATCH && pri <= PRI_MAX_BATCH, 1611 ("sched_priority: invalid priority %d: nice %d, " 1612 "ticks %d ftick %d ltick %d tick pri %d", 1613 pri, td->td_proc->p_nice, td_get_sched(td)->ts_ticks, 1614 td_get_sched(td)->ts_ftick, td_get_sched(td)->ts_ltick, 1615 SCHED_PRI_TICKS(td_get_sched(td)))); 1616 } 1617 sched_user_prio(td, pri); 1618 1619 return; 1620 } 1621 1622 /* 1623 * This routine enforces a maximum limit on the amount of scheduling history 1624 * kept. It is called after either the slptime or runtime is adjusted. This 1625 * function is ugly due to integer math. 1626 */ 1627 static void 1628 sched_interact_update(struct thread *td) 1629 { 1630 struct td_sched *ts; 1631 u_int sum; 1632 1633 ts = td_get_sched(td); 1634 sum = ts->ts_runtime + ts->ts_slptime; 1635 if (sum < SCHED_SLP_RUN_MAX) 1636 return; 1637 /* 1638 * This only happens from two places: 1639 * 1) We have added an unusual amount of run time from fork_exit. 1640 * 2) We have added an unusual amount of sleep time from sched_sleep(). 1641 */ 1642 if (sum > SCHED_SLP_RUN_MAX * 2) { 1643 if (ts->ts_runtime > ts->ts_slptime) { 1644 ts->ts_runtime = SCHED_SLP_RUN_MAX; 1645 ts->ts_slptime = 1; 1646 } else { 1647 ts->ts_slptime = SCHED_SLP_RUN_MAX; 1648 ts->ts_runtime = 1; 1649 } 1650 return; 1651 } 1652 /* 1653 * If we have exceeded by more than 1/5th then the algorithm below 1654 * will not bring us back into range. Dividing by two here forces 1655 * us into the range of [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX] 1656 */ 1657 if (sum > (SCHED_SLP_RUN_MAX / 5) * 6) { 1658 ts->ts_runtime /= 2; 1659 ts->ts_slptime /= 2; 1660 return; 1661 } 1662 ts->ts_runtime = (ts->ts_runtime / 5) * 4; 1663 ts->ts_slptime = (ts->ts_slptime / 5) * 4; 1664 } 1665 1666 /* 1667 * Scale back the interactivity history when a child thread is created. The 1668 * history is inherited from the parent but the thread may behave totally 1669 * differently. For example, a shell spawning a compiler process. We want 1670 * to learn that the compiler is behaving badly very quickly. 1671 */ 1672 static void 1673 sched_interact_fork(struct thread *td) 1674 { 1675 struct td_sched *ts; 1676 int ratio; 1677 int sum; 1678 1679 ts = td_get_sched(td); 1680 sum = ts->ts_runtime + ts->ts_slptime; 1681 if (sum > SCHED_SLP_RUN_FORK) { 1682 ratio = sum / SCHED_SLP_RUN_FORK; 1683 ts->ts_runtime /= ratio; 1684 ts->ts_slptime /= ratio; 1685 } 1686 } 1687 1688 /* 1689 * Called from proc0_init() to setup the scheduler fields. 1690 */ 1691 void 1692 schedinit(void) 1693 { 1694 struct td_sched *ts0; 1695 1696 /* 1697 * Set up the scheduler specific parts of thread0. 1698 */ 1699 ts0 = td_get_sched(&thread0); 1700 ts0->ts_ltick = ticks; 1701 ts0->ts_ftick = ticks; 1702 ts0->ts_slice = 0; 1703 ts0->ts_cpu = curcpu; /* set valid CPU number */ 1704 } 1705 1706 /* 1707 * This is only somewhat accurate since given many processes of the same 1708 * priority they will switch when their slices run out, which will be 1709 * at most sched_slice stathz ticks. 1710 */ 1711 int 1712 sched_rr_interval(void) 1713 { 1714 1715 /* Convert sched_slice from stathz to hz. */ 1716 return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz)); 1717 } 1718 1719 /* 1720 * Update the percent cpu tracking information when it is requested or 1721 * the total history exceeds the maximum. We keep a sliding history of 1722 * tick counts that slowly decays. This is less precise than the 4BSD 1723 * mechanism since it happens with less regular and frequent events. 1724 */ 1725 static void 1726 sched_pctcpu_update(struct td_sched *ts, int run) 1727 { 1728 int t = ticks; 1729 1730 /* 1731 * The signed difference may be negative if the thread hasn't run for 1732 * over half of the ticks rollover period. 1733 */ 1734 if ((u_int)(t - ts->ts_ltick) >= SCHED_TICK_TARG) { 1735 ts->ts_ticks = 0; 1736 ts->ts_ftick = t - SCHED_TICK_TARG; 1737 } else if (t - ts->ts_ftick >= SCHED_TICK_MAX) { 1738 ts->ts_ticks = (ts->ts_ticks / (ts->ts_ltick - ts->ts_ftick)) * 1739 (ts->ts_ltick - (t - SCHED_TICK_TARG)); 1740 ts->ts_ftick = t - SCHED_TICK_TARG; 1741 } 1742 if (run) 1743 ts->ts_ticks += (t - ts->ts_ltick) << SCHED_TICK_SHIFT; 1744 ts->ts_ltick = t; 1745 } 1746 1747 /* 1748 * Adjust the priority of a thread. Move it to the appropriate run-queue 1749 * if necessary. This is the back-end for several priority related 1750 * functions. 1751 */ 1752 static void 1753 sched_thread_priority(struct thread *td, u_char prio) 1754 { 1755 struct td_sched *ts; 1756 struct tdq *tdq; 1757 int oldpri; 1758 1759 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "prio", 1760 "prio:%d", td->td_priority, "new prio:%d", prio, 1761 KTR_ATTR_LINKED, sched_tdname(curthread)); 1762 SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio); 1763 if (td != curthread && prio < td->td_priority) { 1764 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread), 1765 "lend prio", "prio:%d", td->td_priority, "new prio:%d", 1766 prio, KTR_ATTR_LINKED, sched_tdname(td)); 1767 SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio, 1768 curthread); 1769 } 1770 ts = td_get_sched(td); 1771 THREAD_LOCK_ASSERT(td, MA_OWNED); 1772 if (td->td_priority == prio) 1773 return; 1774 /* 1775 * If the priority has been elevated due to priority 1776 * propagation, we may have to move ourselves to a new 1777 * queue. This could be optimized to not re-add in some 1778 * cases. 1779 */ 1780 if (TD_ON_RUNQ(td) && prio < td->td_priority) { 1781 sched_rem(td); 1782 td->td_priority = prio; 1783 sched_add(td, SRQ_BORROWING); 1784 return; 1785 } 1786 /* 1787 * If the thread is currently running we may have to adjust the lowpri 1788 * information so other cpus are aware of our current priority. 1789 */ 1790 if (TD_IS_RUNNING(td)) { 1791 tdq = TDQ_CPU(ts->ts_cpu); 1792 oldpri = td->td_priority; 1793 td->td_priority = prio; 1794 if (prio < tdq->tdq_lowpri) 1795 tdq->tdq_lowpri = prio; 1796 else if (tdq->tdq_lowpri == oldpri) 1797 tdq_setlowpri(tdq, td); 1798 return; 1799 } 1800 td->td_priority = prio; 1801 } 1802 1803 /* 1804 * Update a thread's priority when it is lent another thread's 1805 * priority. 1806 */ 1807 void 1808 sched_lend_prio(struct thread *td, u_char prio) 1809 { 1810 1811 td->td_flags |= TDF_BORROWING; 1812 sched_thread_priority(td, prio); 1813 } 1814 1815 /* 1816 * Restore a thread's priority when priority propagation is 1817 * over. The prio argument is the minimum priority the thread 1818 * needs to have to satisfy other possible priority lending 1819 * requests. If the thread's regular priority is less 1820 * important than prio, the thread will keep a priority boost 1821 * of prio. 1822 */ 1823 void 1824 sched_unlend_prio(struct thread *td, u_char prio) 1825 { 1826 u_char base_pri; 1827 1828 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 1829 td->td_base_pri <= PRI_MAX_TIMESHARE) 1830 base_pri = td->td_user_pri; 1831 else 1832 base_pri = td->td_base_pri; 1833 if (prio >= base_pri) { 1834 td->td_flags &= ~TDF_BORROWING; 1835 sched_thread_priority(td, base_pri); 1836 } else 1837 sched_lend_prio(td, prio); 1838 } 1839 1840 /* 1841 * Standard entry for setting the priority to an absolute value. 1842 */ 1843 void 1844 sched_prio(struct thread *td, u_char prio) 1845 { 1846 u_char oldprio; 1847 1848 /* First, update the base priority. */ 1849 td->td_base_pri = prio; 1850 1851 /* 1852 * If the thread is borrowing another thread's priority, don't 1853 * ever lower the priority. 1854 */ 1855 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 1856 return; 1857 1858 /* Change the real priority. */ 1859 oldprio = td->td_priority; 1860 sched_thread_priority(td, prio); 1861 1862 /* 1863 * If the thread is on a turnstile, then let the turnstile update 1864 * its state. 1865 */ 1866 if (TD_ON_LOCK(td) && oldprio != prio) 1867 turnstile_adjust(td, oldprio); 1868 } 1869 1870 /* 1871 * Set the base user priority, does not effect current running priority. 1872 */ 1873 void 1874 sched_user_prio(struct thread *td, u_char prio) 1875 { 1876 1877 td->td_base_user_pri = prio; 1878 if (td->td_lend_user_pri <= prio) 1879 return; 1880 td->td_user_pri = prio; 1881 } 1882 1883 void 1884 sched_lend_user_prio(struct thread *td, u_char prio) 1885 { 1886 1887 THREAD_LOCK_ASSERT(td, MA_OWNED); 1888 td->td_lend_user_pri = prio; 1889 td->td_user_pri = min(prio, td->td_base_user_pri); 1890 if (td->td_priority > td->td_user_pri) 1891 sched_prio(td, td->td_user_pri); 1892 else if (td->td_priority != td->td_user_pri) 1893 td->td_flags |= TDF_NEEDRESCHED; 1894 } 1895 1896 /* 1897 * Like the above but first check if there is anything to do. 1898 */ 1899 void 1900 sched_lend_user_prio_cond(struct thread *td, u_char prio) 1901 { 1902 1903 if (td->td_lend_user_pri != prio) 1904 goto lend; 1905 if (td->td_user_pri != min(prio, td->td_base_user_pri)) 1906 goto lend; 1907 if (td->td_priority >= td->td_user_pri) 1908 goto lend; 1909 return; 1910 1911 lend: 1912 thread_lock(td); 1913 sched_lend_user_prio(td, prio); 1914 thread_unlock(td); 1915 } 1916 1917 #ifdef SMP 1918 /* 1919 * This tdq is about to idle. Try to steal a thread from another CPU before 1920 * choosing the idle thread. 1921 */ 1922 static void 1923 tdq_trysteal(struct tdq *tdq) 1924 { 1925 struct cpu_group *cg; 1926 struct tdq *steal; 1927 cpuset_t mask; 1928 int cpu, i; 1929 1930 if (smp_started == 0 || trysteal_limit == 0 || tdq->tdq_cg == NULL) 1931 return; 1932 CPU_FILL(&mask); 1933 CPU_CLR(PCPU_GET(cpuid), &mask); 1934 /* We don't want to be preempted while we're iterating. */ 1935 spinlock_enter(); 1936 TDQ_UNLOCK(tdq); 1937 for (i = 1, cg = tdq->tdq_cg; ; ) { 1938 cpu = sched_highest(cg, mask, steal_thresh); 1939 /* 1940 * If a thread was added while interrupts were disabled don't 1941 * steal one here. 1942 */ 1943 if (tdq->tdq_load > 0) { 1944 TDQ_LOCK(tdq); 1945 break; 1946 } 1947 if (cpu == -1) { 1948 i++; 1949 cg = cg->cg_parent; 1950 if (cg == NULL || i > trysteal_limit) { 1951 TDQ_LOCK(tdq); 1952 break; 1953 } 1954 continue; 1955 } 1956 steal = TDQ_CPU(cpu); 1957 /* 1958 * The data returned by sched_highest() is stale and 1959 * the chosen CPU no longer has an eligible thread. 1960 */ 1961 if (steal->tdq_load < steal_thresh || 1962 steal->tdq_transferable == 0) 1963 continue; 1964 tdq_lock_pair(tdq, steal); 1965 /* 1966 * If we get to this point, unconditonally exit the loop 1967 * to bound the time spent in the critcal section. 1968 * 1969 * If a thread was added while interrupts were disabled don't 1970 * steal one here. 1971 */ 1972 if (tdq->tdq_load > 0) { 1973 TDQ_UNLOCK(steal); 1974 break; 1975 } 1976 /* 1977 * The data returned by sched_highest() is stale and 1978 * the chosen CPU no longer has an eligible thread. 1979 */ 1980 if (steal->tdq_load < steal_thresh || 1981 steal->tdq_transferable == 0) { 1982 TDQ_UNLOCK(steal); 1983 break; 1984 } 1985 /* 1986 * If we fail to acquire one due to affinity restrictions, 1987 * bail out and let the idle thread to a more complete search 1988 * outside of a critical section. 1989 */ 1990 if (tdq_move(steal, tdq) == NULL) { 1991 TDQ_UNLOCK(steal); 1992 break; 1993 } 1994 TDQ_UNLOCK(steal); 1995 break; 1996 } 1997 spinlock_exit(); 1998 } 1999 #endif 2000 2001 /* 2002 * Handle migration from sched_switch(). This happens only for 2003 * cpu binding. 2004 */ 2005 static struct mtx * 2006 sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags) 2007 { 2008 struct tdq *tdn; 2009 2010 KASSERT(!CPU_ABSENT(td_get_sched(td)->ts_cpu), ("sched_switch_migrate: " 2011 "thread %s queued on absent CPU %d.", td->td_name, 2012 td_get_sched(td)->ts_cpu)); 2013 tdn = TDQ_CPU(td_get_sched(td)->ts_cpu); 2014 #ifdef SMP 2015 tdq_load_rem(tdq, td); 2016 /* 2017 * Do the lock dance required to avoid LOR. We grab an extra 2018 * spinlock nesting to prevent preemption while we're 2019 * not holding either run-queue lock. 2020 */ 2021 spinlock_enter(); 2022 thread_lock_block(td); /* This releases the lock on tdq. */ 2023 2024 /* 2025 * Acquire both run-queue locks before placing the thread on the new 2026 * run-queue to avoid deadlocks created by placing a thread with a 2027 * blocked lock on the run-queue of a remote processor. The deadlock 2028 * occurs when a third processor attempts to lock the two queues in 2029 * question while the target processor is spinning with its own 2030 * run-queue lock held while waiting for the blocked lock to clear. 2031 */ 2032 tdq_lock_pair(tdn, tdq); 2033 tdq_add(tdn, td, flags); 2034 tdq_notify(tdn, td); 2035 TDQ_UNLOCK(tdn); 2036 spinlock_exit(); 2037 #endif 2038 return (TDQ_LOCKPTR(tdn)); 2039 } 2040 2041 /* 2042 * Variadic version of thread_lock_unblock() that does not assume td_lock 2043 * is blocked. 2044 */ 2045 static inline void 2046 thread_unblock_switch(struct thread *td, struct mtx *mtx) 2047 { 2048 atomic_store_rel_ptr((volatile uintptr_t *)&td->td_lock, 2049 (uintptr_t)mtx); 2050 } 2051 2052 /* 2053 * Switch threads. This function has to handle threads coming in while 2054 * blocked for some reason, running, or idle. It also must deal with 2055 * migrating a thread from one queue to another as running threads may 2056 * be assigned elsewhere via binding. 2057 */ 2058 void 2059 sched_switch(struct thread *td, struct thread *newtd, int flags) 2060 { 2061 struct tdq *tdq; 2062 struct td_sched *ts; 2063 struct mtx *mtx; 2064 int srqflag; 2065 int cpuid, preempted; 2066 2067 THREAD_LOCK_ASSERT(td, MA_OWNED); 2068 KASSERT(newtd == NULL, ("sched_switch: Unsupported newtd argument")); 2069 2070 cpuid = PCPU_GET(cpuid); 2071 tdq = TDQ_SELF(); 2072 ts = td_get_sched(td); 2073 mtx = td->td_lock; 2074 sched_pctcpu_update(ts, 1); 2075 ts->ts_rltick = ticks; 2076 td->td_lastcpu = td->td_oncpu; 2077 td->td_oncpu = NOCPU; 2078 preempted = (td->td_flags & TDF_SLICEEND) == 0 && 2079 (flags & SW_PREEMPT) != 0; 2080 td->td_flags &= ~(TDF_NEEDRESCHED | TDF_SLICEEND); 2081 td->td_owepreempt = 0; 2082 if (!TD_IS_IDLETHREAD(td)) 2083 tdq->tdq_switchcnt++; 2084 /* 2085 * The lock pointer in an idle thread should never change. Reset it 2086 * to CAN_RUN as well. 2087 */ 2088 if (TD_IS_IDLETHREAD(td)) { 2089 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2090 TD_SET_CAN_RUN(td); 2091 } else if (TD_IS_RUNNING(td)) { 2092 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2093 srqflag = preempted ? 2094 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 2095 SRQ_OURSELF|SRQ_YIELDING; 2096 #ifdef SMP 2097 if (THREAD_CAN_MIGRATE(td) && !THREAD_CAN_SCHED(td, ts->ts_cpu)) 2098 ts->ts_cpu = sched_pickcpu(td, 0); 2099 #endif 2100 if (ts->ts_cpu == cpuid) 2101 tdq_runq_add(tdq, td, srqflag); 2102 else { 2103 KASSERT(THREAD_CAN_MIGRATE(td) || 2104 (ts->ts_flags & TSF_BOUND) != 0, 2105 ("Thread %p shouldn't migrate", td)); 2106 mtx = sched_switch_migrate(tdq, td, srqflag); 2107 } 2108 } else { 2109 /* This thread must be going to sleep. */ 2110 TDQ_LOCK(tdq); 2111 mtx = thread_lock_block(td); 2112 tdq_load_rem(tdq, td); 2113 #ifdef SMP 2114 if (tdq->tdq_load == 0) 2115 tdq_trysteal(tdq); 2116 #endif 2117 } 2118 2119 #if (KTR_COMPILE & KTR_SCHED) != 0 2120 if (TD_IS_IDLETHREAD(td)) 2121 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "idle", 2122 "prio:%d", td->td_priority); 2123 else 2124 KTR_STATE3(KTR_SCHED, "thread", sched_tdname(td), KTDSTATE(td), 2125 "prio:%d", td->td_priority, "wmesg:\"%s\"", td->td_wmesg, 2126 "lockname:\"%s\"", td->td_lockname); 2127 #endif 2128 2129 /* 2130 * We enter here with the thread blocked and assigned to the 2131 * appropriate cpu run-queue or sleep-queue and with the current 2132 * thread-queue locked. 2133 */ 2134 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 2135 newtd = choosethread(); 2136 /* 2137 * Call the MD code to switch contexts if necessary. 2138 */ 2139 if (td != newtd) { 2140 #ifdef HWPMC_HOOKS 2141 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 2142 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 2143 #endif 2144 SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc); 2145 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 2146 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 2147 sched_pctcpu_update(td_get_sched(newtd), 0); 2148 2149 #ifdef KDTRACE_HOOKS 2150 /* 2151 * If DTrace has set the active vtime enum to anything 2152 * other than INACTIVE (0), then it should have set the 2153 * function to call. 2154 */ 2155 if (dtrace_vtime_active) 2156 (*dtrace_vtime_switch_func)(newtd); 2157 #endif 2158 2159 cpu_switch(td, newtd, mtx); 2160 /* 2161 * We may return from cpu_switch on a different cpu. However, 2162 * we always return with td_lock pointing to the current cpu's 2163 * run queue lock. 2164 */ 2165 cpuid = PCPU_GET(cpuid); 2166 tdq = TDQ_SELF(); 2167 lock_profile_obtain_lock_success( 2168 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 2169 2170 SDT_PROBE0(sched, , , on__cpu); 2171 #ifdef HWPMC_HOOKS 2172 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 2173 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 2174 #endif 2175 } else { 2176 thread_unblock_switch(td, mtx); 2177 SDT_PROBE0(sched, , , remain__cpu); 2178 } 2179 2180 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running", 2181 "prio:%d", td->td_priority); 2182 2183 /* 2184 * Assert that all went well and return. 2185 */ 2186 TDQ_LOCK_ASSERT(tdq, MA_OWNED|MA_NOTRECURSED); 2187 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2188 td->td_oncpu = cpuid; 2189 } 2190 2191 /* 2192 * Adjust thread priorities as a result of a nice request. 2193 */ 2194 void 2195 sched_nice(struct proc *p, int nice) 2196 { 2197 struct thread *td; 2198 2199 PROC_LOCK_ASSERT(p, MA_OWNED); 2200 2201 p->p_nice = nice; 2202 FOREACH_THREAD_IN_PROC(p, td) { 2203 thread_lock(td); 2204 sched_priority(td); 2205 sched_prio(td, td->td_base_user_pri); 2206 thread_unlock(td); 2207 } 2208 } 2209 2210 /* 2211 * Record the sleep time for the interactivity scorer. 2212 */ 2213 void 2214 sched_sleep(struct thread *td, int prio) 2215 { 2216 2217 THREAD_LOCK_ASSERT(td, MA_OWNED); 2218 2219 td->td_slptick = ticks; 2220 if (TD_IS_SUSPENDED(td) || prio >= PSOCK) 2221 td->td_flags |= TDF_CANSWAP; 2222 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 2223 return; 2224 if (static_boost == 1 && prio) 2225 sched_prio(td, prio); 2226 else if (static_boost && td->td_priority > static_boost) 2227 sched_prio(td, static_boost); 2228 } 2229 2230 /* 2231 * Schedule a thread to resume execution and record how long it voluntarily 2232 * slept. We also update the pctcpu, interactivity, and priority. 2233 */ 2234 void 2235 sched_wakeup(struct thread *td) 2236 { 2237 struct td_sched *ts; 2238 int slptick; 2239 2240 THREAD_LOCK_ASSERT(td, MA_OWNED); 2241 ts = td_get_sched(td); 2242 td->td_flags &= ~TDF_CANSWAP; 2243 /* 2244 * If we slept for more than a tick update our interactivity and 2245 * priority. 2246 */ 2247 slptick = td->td_slptick; 2248 td->td_slptick = 0; 2249 if (slptick && slptick != ticks) { 2250 ts->ts_slptime += (ticks - slptick) << SCHED_TICK_SHIFT; 2251 sched_interact_update(td); 2252 sched_pctcpu_update(ts, 0); 2253 } 2254 /* 2255 * Reset the slice value since we slept and advanced the round-robin. 2256 */ 2257 ts->ts_slice = 0; 2258 sched_add(td, SRQ_BORING); 2259 } 2260 2261 /* 2262 * Penalize the parent for creating a new child and initialize the child's 2263 * priority. 2264 */ 2265 void 2266 sched_fork(struct thread *td, struct thread *child) 2267 { 2268 THREAD_LOCK_ASSERT(td, MA_OWNED); 2269 sched_pctcpu_update(td_get_sched(td), 1); 2270 sched_fork_thread(td, child); 2271 /* 2272 * Penalize the parent and child for forking. 2273 */ 2274 sched_interact_fork(child); 2275 sched_priority(child); 2276 td_get_sched(td)->ts_runtime += tickincr; 2277 sched_interact_update(td); 2278 sched_priority(td); 2279 } 2280 2281 /* 2282 * Fork a new thread, may be within the same process. 2283 */ 2284 void 2285 sched_fork_thread(struct thread *td, struct thread *child) 2286 { 2287 struct td_sched *ts; 2288 struct td_sched *ts2; 2289 struct tdq *tdq; 2290 2291 tdq = TDQ_SELF(); 2292 THREAD_LOCK_ASSERT(td, MA_OWNED); 2293 /* 2294 * Initialize child. 2295 */ 2296 ts = td_get_sched(td); 2297 ts2 = td_get_sched(child); 2298 child->td_oncpu = NOCPU; 2299 child->td_lastcpu = NOCPU; 2300 child->td_lock = TDQ_LOCKPTR(tdq); 2301 child->td_cpuset = cpuset_ref(td->td_cpuset); 2302 child->td_domain.dr_policy = td->td_cpuset->cs_domain; 2303 ts2->ts_cpu = ts->ts_cpu; 2304 ts2->ts_flags = 0; 2305 /* 2306 * Grab our parents cpu estimation information. 2307 */ 2308 ts2->ts_ticks = ts->ts_ticks; 2309 ts2->ts_ltick = ts->ts_ltick; 2310 ts2->ts_ftick = ts->ts_ftick; 2311 /* 2312 * Do not inherit any borrowed priority from the parent. 2313 */ 2314 child->td_priority = child->td_base_pri; 2315 /* 2316 * And update interactivity score. 2317 */ 2318 ts2->ts_slptime = ts->ts_slptime; 2319 ts2->ts_runtime = ts->ts_runtime; 2320 /* Attempt to quickly learn interactivity. */ 2321 ts2->ts_slice = tdq_slice(tdq) - sched_slice_min; 2322 #ifdef KTR 2323 bzero(ts2->ts_name, sizeof(ts2->ts_name)); 2324 #endif 2325 } 2326 2327 /* 2328 * Adjust the priority class of a thread. 2329 */ 2330 void 2331 sched_class(struct thread *td, int class) 2332 { 2333 2334 THREAD_LOCK_ASSERT(td, MA_OWNED); 2335 if (td->td_pri_class == class) 2336 return; 2337 td->td_pri_class = class; 2338 } 2339 2340 /* 2341 * Return some of the child's priority and interactivity to the parent. 2342 */ 2343 void 2344 sched_exit(struct proc *p, struct thread *child) 2345 { 2346 struct thread *td; 2347 2348 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "proc exit", 2349 "prio:%d", child->td_priority); 2350 PROC_LOCK_ASSERT(p, MA_OWNED); 2351 td = FIRST_THREAD_IN_PROC(p); 2352 sched_exit_thread(td, child); 2353 } 2354 2355 /* 2356 * Penalize another thread for the time spent on this one. This helps to 2357 * worsen the priority and interactivity of processes which schedule batch 2358 * jobs such as make. This has little effect on the make process itself but 2359 * causes new processes spawned by it to receive worse scores immediately. 2360 */ 2361 void 2362 sched_exit_thread(struct thread *td, struct thread *child) 2363 { 2364 2365 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "thread exit", 2366 "prio:%d", child->td_priority); 2367 /* 2368 * Give the child's runtime to the parent without returning the 2369 * sleep time as a penalty to the parent. This causes shells that 2370 * launch expensive things to mark their children as expensive. 2371 */ 2372 thread_lock(td); 2373 td_get_sched(td)->ts_runtime += td_get_sched(child)->ts_runtime; 2374 sched_interact_update(td); 2375 sched_priority(td); 2376 thread_unlock(td); 2377 } 2378 2379 void 2380 sched_preempt(struct thread *td) 2381 { 2382 struct tdq *tdq; 2383 2384 SDT_PROBE2(sched, , , surrender, td, td->td_proc); 2385 2386 thread_lock(td); 2387 tdq = TDQ_SELF(); 2388 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2389 tdq->tdq_ipipending = 0; 2390 if (td->td_priority > tdq->tdq_lowpri) { 2391 int flags; 2392 2393 flags = SW_INVOL | SW_PREEMPT; 2394 if (td->td_critnest > 1) 2395 td->td_owepreempt = 1; 2396 else if (TD_IS_IDLETHREAD(td)) 2397 mi_switch(flags | SWT_REMOTEWAKEIDLE, NULL); 2398 else 2399 mi_switch(flags | SWT_REMOTEPREEMPT, NULL); 2400 } 2401 thread_unlock(td); 2402 } 2403 2404 /* 2405 * Fix priorities on return to user-space. Priorities may be elevated due 2406 * to static priorities in msleep() or similar. 2407 */ 2408 void 2409 sched_userret_slowpath(struct thread *td) 2410 { 2411 2412 thread_lock(td); 2413 td->td_priority = td->td_user_pri; 2414 td->td_base_pri = td->td_user_pri; 2415 tdq_setlowpri(TDQ_SELF(), td); 2416 thread_unlock(td); 2417 } 2418 2419 /* 2420 * Handle a stathz tick. This is really only relevant for timeshare 2421 * threads. 2422 */ 2423 void 2424 sched_clock(struct thread *td) 2425 { 2426 struct tdq *tdq; 2427 struct td_sched *ts; 2428 2429 THREAD_LOCK_ASSERT(td, MA_OWNED); 2430 tdq = TDQ_SELF(); 2431 #ifdef SMP 2432 /* 2433 * We run the long term load balancer infrequently on the first cpu. 2434 */ 2435 if (balance_tdq == tdq && smp_started != 0 && rebalance != 0) { 2436 if (balance_ticks && --balance_ticks == 0) 2437 sched_balance(); 2438 } 2439 #endif 2440 /* 2441 * Save the old switch count so we have a record of the last ticks 2442 * activity. Initialize the new switch count based on our load. 2443 * If there is some activity seed it to reflect that. 2444 */ 2445 tdq->tdq_oldswitchcnt = tdq->tdq_switchcnt; 2446 tdq->tdq_switchcnt = tdq->tdq_load; 2447 /* 2448 * Advance the insert index once for each tick to ensure that all 2449 * threads get a chance to run. 2450 */ 2451 if (tdq->tdq_idx == tdq->tdq_ridx) { 2452 tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS; 2453 if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx])) 2454 tdq->tdq_ridx = tdq->tdq_idx; 2455 } 2456 ts = td_get_sched(td); 2457 sched_pctcpu_update(ts, 1); 2458 if (td->td_pri_class & PRI_FIFO_BIT) 2459 return; 2460 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) { 2461 /* 2462 * We used a tick; charge it to the thread so 2463 * that we can compute our interactivity. 2464 */ 2465 td_get_sched(td)->ts_runtime += tickincr; 2466 sched_interact_update(td); 2467 sched_priority(td); 2468 } 2469 2470 /* 2471 * Force a context switch if the current thread has used up a full 2472 * time slice (default is 100ms). 2473 */ 2474 if (!TD_IS_IDLETHREAD(td) && ++ts->ts_slice >= tdq_slice(tdq)) { 2475 ts->ts_slice = 0; 2476 td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND; 2477 } 2478 } 2479 2480 u_int 2481 sched_estcpu(struct thread *td __unused) 2482 { 2483 2484 return (0); 2485 } 2486 2487 /* 2488 * Return whether the current CPU has runnable tasks. Used for in-kernel 2489 * cooperative idle threads. 2490 */ 2491 int 2492 sched_runnable(void) 2493 { 2494 struct tdq *tdq; 2495 int load; 2496 2497 load = 1; 2498 2499 tdq = TDQ_SELF(); 2500 if ((curthread->td_flags & TDF_IDLETD) != 0) { 2501 if (tdq->tdq_load > 0) 2502 goto out; 2503 } else 2504 if (tdq->tdq_load - 1 > 0) 2505 goto out; 2506 load = 0; 2507 out: 2508 return (load); 2509 } 2510 2511 /* 2512 * Choose the highest priority thread to run. The thread is removed from 2513 * the run-queue while running however the load remains. For SMP we set 2514 * the tdq in the global idle bitmask if it idles here. 2515 */ 2516 struct thread * 2517 sched_choose(void) 2518 { 2519 struct thread *td; 2520 struct tdq *tdq; 2521 2522 tdq = TDQ_SELF(); 2523 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2524 td = tdq_choose(tdq); 2525 if (td) { 2526 tdq_runq_rem(tdq, td); 2527 tdq->tdq_lowpri = td->td_priority; 2528 return (td); 2529 } 2530 tdq->tdq_lowpri = PRI_MAX_IDLE; 2531 return (PCPU_GET(idlethread)); 2532 } 2533 2534 /* 2535 * Set owepreempt if necessary. Preemption never happens directly in ULE, 2536 * we always request it once we exit a critical section. 2537 */ 2538 static inline void 2539 sched_setpreempt(struct thread *td) 2540 { 2541 struct thread *ctd; 2542 int cpri; 2543 int pri; 2544 2545 THREAD_LOCK_ASSERT(curthread, MA_OWNED); 2546 2547 ctd = curthread; 2548 pri = td->td_priority; 2549 cpri = ctd->td_priority; 2550 if (pri < cpri) 2551 ctd->td_flags |= TDF_NEEDRESCHED; 2552 if (panicstr != NULL || pri >= cpri || cold || TD_IS_INHIBITED(ctd)) 2553 return; 2554 if (!sched_shouldpreempt(pri, cpri, 0)) 2555 return; 2556 ctd->td_owepreempt = 1; 2557 } 2558 2559 /* 2560 * Add a thread to a thread queue. Select the appropriate runq and add the 2561 * thread to it. This is the internal function called when the tdq is 2562 * predetermined. 2563 */ 2564 void 2565 tdq_add(struct tdq *tdq, struct thread *td, int flags) 2566 { 2567 2568 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2569 KASSERT((td->td_inhibitors == 0), 2570 ("sched_add: trying to run inhibited thread")); 2571 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 2572 ("sched_add: bad thread state")); 2573 KASSERT(td->td_flags & TDF_INMEM, 2574 ("sched_add: thread swapped out")); 2575 2576 if (td->td_priority < tdq->tdq_lowpri) 2577 tdq->tdq_lowpri = td->td_priority; 2578 tdq_runq_add(tdq, td, flags); 2579 tdq_load_add(tdq, td); 2580 } 2581 2582 /* 2583 * Select the target thread queue and add a thread to it. Request 2584 * preemption or IPI a remote processor if required. 2585 */ 2586 void 2587 sched_add(struct thread *td, int flags) 2588 { 2589 struct tdq *tdq; 2590 #ifdef SMP 2591 int cpu; 2592 #endif 2593 2594 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 2595 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 2596 sched_tdname(curthread)); 2597 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 2598 KTR_ATTR_LINKED, sched_tdname(td)); 2599 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 2600 flags & SRQ_PREEMPTED); 2601 THREAD_LOCK_ASSERT(td, MA_OWNED); 2602 /* 2603 * Recalculate the priority before we select the target cpu or 2604 * run-queue. 2605 */ 2606 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 2607 sched_priority(td); 2608 #ifdef SMP 2609 /* 2610 * Pick the destination cpu and if it isn't ours transfer to the 2611 * target cpu. 2612 */ 2613 cpu = sched_pickcpu(td, flags); 2614 tdq = sched_setcpu(td, cpu, flags); 2615 tdq_add(tdq, td, flags); 2616 if (cpu != PCPU_GET(cpuid)) { 2617 tdq_notify(tdq, td); 2618 return; 2619 } 2620 #else 2621 tdq = TDQ_SELF(); 2622 TDQ_LOCK(tdq); 2623 /* 2624 * Now that the thread is moving to the run-queue, set the lock 2625 * to the scheduler's lock. 2626 */ 2627 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 2628 tdq_add(tdq, td, flags); 2629 #endif 2630 if (!(flags & SRQ_YIELDING)) 2631 sched_setpreempt(td); 2632 } 2633 2634 /* 2635 * Remove a thread from a run-queue without running it. This is used 2636 * when we're stealing a thread from a remote queue. Otherwise all threads 2637 * exit by calling sched_exit_thread() and sched_throw() themselves. 2638 */ 2639 void 2640 sched_rem(struct thread *td) 2641 { 2642 struct tdq *tdq; 2643 2644 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "runq rem", 2645 "prio:%d", td->td_priority); 2646 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL); 2647 tdq = TDQ_CPU(td_get_sched(td)->ts_cpu); 2648 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2649 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2650 KASSERT(TD_ON_RUNQ(td), 2651 ("sched_rem: thread not on run queue")); 2652 tdq_runq_rem(tdq, td); 2653 tdq_load_rem(tdq, td); 2654 TD_SET_CAN_RUN(td); 2655 if (td->td_priority == tdq->tdq_lowpri) 2656 tdq_setlowpri(tdq, NULL); 2657 } 2658 2659 /* 2660 * Fetch cpu utilization information. Updates on demand. 2661 */ 2662 fixpt_t 2663 sched_pctcpu(struct thread *td) 2664 { 2665 fixpt_t pctcpu; 2666 struct td_sched *ts; 2667 2668 pctcpu = 0; 2669 ts = td_get_sched(td); 2670 2671 THREAD_LOCK_ASSERT(td, MA_OWNED); 2672 sched_pctcpu_update(ts, TD_IS_RUNNING(td)); 2673 if (ts->ts_ticks) { 2674 int rtick; 2675 2676 /* How many rtick per second ? */ 2677 rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz); 2678 pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT; 2679 } 2680 2681 return (pctcpu); 2682 } 2683 2684 /* 2685 * Enforce affinity settings for a thread. Called after adjustments to 2686 * cpumask. 2687 */ 2688 void 2689 sched_affinity(struct thread *td) 2690 { 2691 #ifdef SMP 2692 struct td_sched *ts; 2693 2694 THREAD_LOCK_ASSERT(td, MA_OWNED); 2695 ts = td_get_sched(td); 2696 if (THREAD_CAN_SCHED(td, ts->ts_cpu)) 2697 return; 2698 if (TD_ON_RUNQ(td)) { 2699 sched_rem(td); 2700 sched_add(td, SRQ_BORING); 2701 return; 2702 } 2703 if (!TD_IS_RUNNING(td)) 2704 return; 2705 /* 2706 * Force a switch before returning to userspace. If the 2707 * target thread is not running locally send an ipi to force 2708 * the issue. 2709 */ 2710 td->td_flags |= TDF_NEEDRESCHED; 2711 if (td != curthread) 2712 ipi_cpu(ts->ts_cpu, IPI_PREEMPT); 2713 #endif 2714 } 2715 2716 /* 2717 * Bind a thread to a target cpu. 2718 */ 2719 void 2720 sched_bind(struct thread *td, int cpu) 2721 { 2722 struct td_sched *ts; 2723 2724 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 2725 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 2726 ts = td_get_sched(td); 2727 if (ts->ts_flags & TSF_BOUND) 2728 sched_unbind(td); 2729 KASSERT(THREAD_CAN_MIGRATE(td), ("%p must be migratable", td)); 2730 ts->ts_flags |= TSF_BOUND; 2731 sched_pin(); 2732 if (PCPU_GET(cpuid) == cpu) 2733 return; 2734 ts->ts_cpu = cpu; 2735 /* When we return from mi_switch we'll be on the correct cpu. */ 2736 mi_switch(SW_VOL, NULL); 2737 } 2738 2739 /* 2740 * Release a bound thread. 2741 */ 2742 void 2743 sched_unbind(struct thread *td) 2744 { 2745 struct td_sched *ts; 2746 2747 THREAD_LOCK_ASSERT(td, MA_OWNED); 2748 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 2749 ts = td_get_sched(td); 2750 if ((ts->ts_flags & TSF_BOUND) == 0) 2751 return; 2752 ts->ts_flags &= ~TSF_BOUND; 2753 sched_unpin(); 2754 } 2755 2756 int 2757 sched_is_bound(struct thread *td) 2758 { 2759 THREAD_LOCK_ASSERT(td, MA_OWNED); 2760 return (td_get_sched(td)->ts_flags & TSF_BOUND); 2761 } 2762 2763 /* 2764 * Basic yield call. 2765 */ 2766 void 2767 sched_relinquish(struct thread *td) 2768 { 2769 thread_lock(td); 2770 mi_switch(SW_VOL | SWT_RELINQUISH, NULL); 2771 thread_unlock(td); 2772 } 2773 2774 /* 2775 * Return the total system load. 2776 */ 2777 int 2778 sched_load(void) 2779 { 2780 #ifdef SMP 2781 int total; 2782 int i; 2783 2784 total = 0; 2785 CPU_FOREACH(i) 2786 total += TDQ_CPU(i)->tdq_sysload; 2787 return (total); 2788 #else 2789 return (TDQ_SELF()->tdq_sysload); 2790 #endif 2791 } 2792 2793 int 2794 sched_sizeof_proc(void) 2795 { 2796 return (sizeof(struct proc)); 2797 } 2798 2799 int 2800 sched_sizeof_thread(void) 2801 { 2802 return (sizeof(struct thread) + sizeof(struct td_sched)); 2803 } 2804 2805 #ifdef SMP 2806 #define TDQ_IDLESPIN(tdq) \ 2807 ((tdq)->tdq_cg != NULL && ((tdq)->tdq_cg->cg_flags & CG_FLAG_THREAD) == 0) 2808 #else 2809 #define TDQ_IDLESPIN(tdq) 1 2810 #endif 2811 2812 /* 2813 * The actual idle process. 2814 */ 2815 void 2816 sched_idletd(void *dummy) 2817 { 2818 struct thread *td; 2819 struct tdq *tdq; 2820 int oldswitchcnt, switchcnt; 2821 int i; 2822 2823 mtx_assert(&Giant, MA_NOTOWNED); 2824 td = curthread; 2825 tdq = TDQ_SELF(); 2826 THREAD_NO_SLEEPING(); 2827 oldswitchcnt = -1; 2828 for (;;) { 2829 if (tdq->tdq_load) { 2830 thread_lock(td); 2831 mi_switch(SW_VOL | SWT_IDLE, NULL); 2832 thread_unlock(td); 2833 } 2834 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2835 #ifdef SMP 2836 if (always_steal || switchcnt != oldswitchcnt) { 2837 oldswitchcnt = switchcnt; 2838 if (tdq_idled(tdq) == 0) 2839 continue; 2840 } 2841 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2842 #else 2843 oldswitchcnt = switchcnt; 2844 #endif 2845 /* 2846 * If we're switching very frequently, spin while checking 2847 * for load rather than entering a low power state that 2848 * may require an IPI. However, don't do any busy 2849 * loops while on SMT machines as this simply steals 2850 * cycles from cores doing useful work. 2851 */ 2852 if (TDQ_IDLESPIN(tdq) && switchcnt > sched_idlespinthresh) { 2853 for (i = 0; i < sched_idlespins; i++) { 2854 if (tdq->tdq_load) 2855 break; 2856 cpu_spinwait(); 2857 } 2858 } 2859 2860 /* If there was context switch during spin, restart it. */ 2861 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2862 if (tdq->tdq_load != 0 || switchcnt != oldswitchcnt) 2863 continue; 2864 2865 /* Run main MD idle handler. */ 2866 tdq->tdq_cpu_idle = 1; 2867 /* 2868 * Make sure that tdq_cpu_idle update is globally visible 2869 * before cpu_idle() read tdq_load. The order is important 2870 * to avoid race with tdq_notify. 2871 */ 2872 atomic_thread_fence_seq_cst(); 2873 /* 2874 * Checking for again after the fence picks up assigned 2875 * threads often enough to make it worthwhile to do so in 2876 * order to avoid calling cpu_idle(). 2877 */ 2878 if (tdq->tdq_load != 0) { 2879 tdq->tdq_cpu_idle = 0; 2880 continue; 2881 } 2882 cpu_idle(switchcnt * 4 > sched_idlespinthresh); 2883 tdq->tdq_cpu_idle = 0; 2884 2885 /* 2886 * Account thread-less hardware interrupts and 2887 * other wakeup reasons equal to context switches. 2888 */ 2889 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2890 if (switchcnt != oldswitchcnt) 2891 continue; 2892 tdq->tdq_switchcnt++; 2893 oldswitchcnt++; 2894 } 2895 } 2896 2897 /* 2898 * A CPU is entering for the first time or a thread is exiting. 2899 */ 2900 void 2901 sched_throw(struct thread *td) 2902 { 2903 struct thread *newtd; 2904 struct tdq *tdq; 2905 2906 if (td == NULL) { 2907 #ifdef SMP 2908 PCPU_SET(sched, DPCPU_PTR(tdq)); 2909 #endif 2910 /* Correct spinlock nesting and acquire the correct lock. */ 2911 tdq = TDQ_SELF(); 2912 TDQ_LOCK(tdq); 2913 spinlock_exit(); 2914 PCPU_SET(switchtime, cpu_ticks()); 2915 PCPU_SET(switchticks, ticks); 2916 PCPU_GET(idlethread)->td_lock = TDQ_LOCKPTR(tdq); 2917 } else { 2918 tdq = TDQ_SELF(); 2919 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2920 tdq_load_rem(tdq, td); 2921 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 2922 td->td_lastcpu = td->td_oncpu; 2923 td->td_oncpu = NOCPU; 2924 } 2925 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 2926 newtd = choosethread(); 2927 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 2928 cpu_throw(td, newtd); /* doesn't return */ 2929 } 2930 2931 /* 2932 * This is called from fork_exit(). Just acquire the correct locks and 2933 * let fork do the rest of the work. 2934 */ 2935 void 2936 sched_fork_exit(struct thread *td) 2937 { 2938 struct tdq *tdq; 2939 int cpuid; 2940 2941 /* 2942 * Finish setting up thread glue so that it begins execution in a 2943 * non-nested critical section with the scheduler lock held. 2944 */ 2945 cpuid = PCPU_GET(cpuid); 2946 tdq = TDQ_SELF(); 2947 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2948 td->td_oncpu = cpuid; 2949 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 2950 lock_profile_obtain_lock_success( 2951 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 2952 2953 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running", 2954 "prio:%d", td->td_priority); 2955 SDT_PROBE0(sched, , , on__cpu); 2956 } 2957 2958 /* 2959 * Create on first use to catch odd startup conditons. 2960 */ 2961 char * 2962 sched_tdname(struct thread *td) 2963 { 2964 #ifdef KTR 2965 struct td_sched *ts; 2966 2967 ts = td_get_sched(td); 2968 if (ts->ts_name[0] == '\0') 2969 snprintf(ts->ts_name, sizeof(ts->ts_name), 2970 "%s tid %d", td->td_name, td->td_tid); 2971 return (ts->ts_name); 2972 #else 2973 return (td->td_name); 2974 #endif 2975 } 2976 2977 #ifdef KTR 2978 void 2979 sched_clear_tdname(struct thread *td) 2980 { 2981 struct td_sched *ts; 2982 2983 ts = td_get_sched(td); 2984 ts->ts_name[0] = '\0'; 2985 } 2986 #endif 2987 2988 #ifdef SMP 2989 2990 /* 2991 * Build the CPU topology dump string. Is recursively called to collect 2992 * the topology tree. 2993 */ 2994 static int 2995 sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, struct cpu_group *cg, 2996 int indent) 2997 { 2998 char cpusetbuf[CPUSETBUFSIZ]; 2999 int i, first; 3000 3001 sbuf_printf(sb, "%*s<group level=\"%d\" cache-level=\"%d\">\n", indent, 3002 "", 1 + indent / 2, cg->cg_level); 3003 sbuf_printf(sb, "%*s <cpu count=\"%d\" mask=\"%s\">", indent, "", 3004 cg->cg_count, cpusetobj_strprint(cpusetbuf, &cg->cg_mask)); 3005 first = TRUE; 3006 for (i = 0; i < MAXCPU; i++) { 3007 if (CPU_ISSET(i, &cg->cg_mask)) { 3008 if (!first) 3009 sbuf_printf(sb, ", "); 3010 else 3011 first = FALSE; 3012 sbuf_printf(sb, "%d", i); 3013 } 3014 } 3015 sbuf_printf(sb, "</cpu>\n"); 3016 3017 if (cg->cg_flags != 0) { 3018 sbuf_printf(sb, "%*s <flags>", indent, ""); 3019 if ((cg->cg_flags & CG_FLAG_HTT) != 0) 3020 sbuf_printf(sb, "<flag name=\"HTT\">HTT group</flag>"); 3021 if ((cg->cg_flags & CG_FLAG_THREAD) != 0) 3022 sbuf_printf(sb, "<flag name=\"THREAD\">THREAD group</flag>"); 3023 if ((cg->cg_flags & CG_FLAG_SMT) != 0) 3024 sbuf_printf(sb, "<flag name=\"SMT\">SMT group</flag>"); 3025 sbuf_printf(sb, "</flags>\n"); 3026 } 3027 3028 if (cg->cg_children > 0) { 3029 sbuf_printf(sb, "%*s <children>\n", indent, ""); 3030 for (i = 0; i < cg->cg_children; i++) 3031 sysctl_kern_sched_topology_spec_internal(sb, 3032 &cg->cg_child[i], indent+2); 3033 sbuf_printf(sb, "%*s </children>\n", indent, ""); 3034 } 3035 sbuf_printf(sb, "%*s</group>\n", indent, ""); 3036 return (0); 3037 } 3038 3039 /* 3040 * Sysctl handler for retrieving topology dump. It's a wrapper for 3041 * the recursive sysctl_kern_smp_topology_spec_internal(). 3042 */ 3043 static int 3044 sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS) 3045 { 3046 struct sbuf *topo; 3047 int err; 3048 3049 KASSERT(cpu_top != NULL, ("cpu_top isn't initialized")); 3050 3051 topo = sbuf_new_for_sysctl(NULL, NULL, 512, req); 3052 if (topo == NULL) 3053 return (ENOMEM); 3054 3055 sbuf_printf(topo, "<groups>\n"); 3056 err = sysctl_kern_sched_topology_spec_internal(topo, cpu_top, 1); 3057 sbuf_printf(topo, "</groups>\n"); 3058 3059 if (err == 0) { 3060 err = sbuf_finish(topo); 3061 } 3062 sbuf_delete(topo); 3063 return (err); 3064 } 3065 3066 #endif 3067 3068 static int 3069 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 3070 { 3071 int error, new_val, period; 3072 3073 period = 1000000 / realstathz; 3074 new_val = period * sched_slice; 3075 error = sysctl_handle_int(oidp, &new_val, 0, req); 3076 if (error != 0 || req->newptr == NULL) 3077 return (error); 3078 if (new_val <= 0) 3079 return (EINVAL); 3080 sched_slice = imax(1, (new_val + period / 2) / period); 3081 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 3082 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 3083 realstathz); 3084 return (0); 3085 } 3086 3087 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0, "Scheduler"); 3088 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0, 3089 "Scheduler name"); 3090 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW, 3091 NULL, 0, sysctl_kern_quantum, "I", 3092 "Quantum for timeshare threads in microseconds"); 3093 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, 3094 "Quantum for timeshare threads in stathz ticks"); 3095 SYSCTL_INT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0, 3096 "Interactivity score threshold"); 3097 SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW, 3098 &preempt_thresh, 0, 3099 "Maximal (lowest) priority for preemption"); 3100 SYSCTL_INT(_kern_sched, OID_AUTO, static_boost, CTLFLAG_RW, &static_boost, 0, 3101 "Assign static kernel priorities to sleeping threads"); 3102 SYSCTL_INT(_kern_sched, OID_AUTO, idlespins, CTLFLAG_RW, &sched_idlespins, 0, 3103 "Number of times idle thread will spin waiting for new work"); 3104 SYSCTL_INT(_kern_sched, OID_AUTO, idlespinthresh, CTLFLAG_RW, 3105 &sched_idlespinthresh, 0, 3106 "Threshold before we will permit idle thread spinning"); 3107 #ifdef SMP 3108 SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0, 3109 "Number of hz ticks to keep thread affinity for"); 3110 SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0, 3111 "Enables the long-term load balancer"); 3112 SYSCTL_INT(_kern_sched, OID_AUTO, balance_interval, CTLFLAG_RW, 3113 &balance_interval, 0, 3114 "Average period in stathz ticks to run the long-term balancer"); 3115 SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0, 3116 "Attempts to steal work from other cores before idling"); 3117 SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0, 3118 "Minimum load on remote CPU before we'll steal"); 3119 SYSCTL_INT(_kern_sched, OID_AUTO, trysteal_limit, CTLFLAG_RW, &trysteal_limit, 3120 0, "Topological distance limit for stealing threads in sched_switch()"); 3121 SYSCTL_INT(_kern_sched, OID_AUTO, always_steal, CTLFLAG_RW, &always_steal, 0, 3122 "Always run the stealer from the idle thread"); 3123 SYSCTL_PROC(_kern_sched, OID_AUTO, topology_spec, CTLTYPE_STRING | 3124 CTLFLAG_MPSAFE | CTLFLAG_RD, NULL, 0, sysctl_kern_sched_topology_spec, "A", 3125 "XML dump of detected CPU topology"); 3126 #endif 3127 3128 /* ps compat. All cpu percentages from ULE are weighted. */ 3129 static int ccpu = 0; 3130 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 3131