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/umtxvar.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 __read_mostly 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_PICKCPU TDF_SCHED0 /* Thread should pick new CPU. */ 200 #define TDF_SLICEEND TDF_SCHED2 /* Thread time slice is over. */ 201 202 /* 203 * tickincr: Converts a stathz tick into a hz domain scaled by 204 * the shift factor. Without the shift the error rate 205 * due to rounding would be unacceptably high. 206 * realstathz: stathz is sometimes 0 and run off of hz. 207 * sched_slice: Runtime of each thread before rescheduling. 208 * preempt_thresh: Priority threshold for preemption and remote IPIs. 209 */ 210 static u_int __read_mostly sched_interact = SCHED_INTERACT_THRESH; 211 static int __read_mostly tickincr = 8 << SCHED_TICK_SHIFT; 212 static int __read_mostly realstathz = 127; /* reset during boot. */ 213 static int __read_mostly sched_slice = 10; /* reset during boot. */ 214 static int __read_mostly sched_slice_min = 1; /* reset during boot. */ 215 #ifdef PREEMPTION 216 #ifdef FULL_PREEMPTION 217 static int __read_mostly preempt_thresh = PRI_MAX_IDLE; 218 #else 219 static int __read_mostly preempt_thresh = PRI_MIN_KERN; 220 #endif 221 #else 222 static int __read_mostly preempt_thresh = 0; 223 #endif 224 static int __read_mostly static_boost = PRI_MIN_BATCH; 225 static int __read_mostly sched_idlespins = 10000; 226 static int __read_mostly sched_idlespinthresh = -1; 227 228 /* 229 * tdq - per processor runqs and statistics. All fields are protected by the 230 * tdq_lock. The load and lowpri may be accessed without to avoid excess 231 * locking in sched_pickcpu(); 232 */ 233 struct tdq { 234 /* 235 * Ordered to improve efficiency of cpu_search() and switch(). 236 * tdq_lock is padded to avoid false sharing with tdq_load and 237 * tdq_cpu_idle. 238 */ 239 struct mtx_padalign tdq_lock; /* run queue lock. */ 240 struct cpu_group *tdq_cg; /* Pointer to cpu topology. */ 241 struct thread *tdq_curthread; /* Current executing thread. */ 242 volatile int tdq_load; /* Aggregate load. */ 243 volatile int tdq_cpu_idle; /* cpu_idle() is active. */ 244 int tdq_sysload; /* For loadavg, !ITHD load. */ 245 volatile int tdq_transferable; /* Transferable thread count. */ 246 volatile short tdq_switchcnt; /* Switches this tick. */ 247 volatile short tdq_oldswitchcnt; /* Switches last tick. */ 248 u_char tdq_lowpri; /* Lowest priority thread. */ 249 u_char tdq_owepreempt; /* Remote preemption pending. */ 250 u_char tdq_idx; /* Current insert index. */ 251 u_char tdq_ridx; /* Current removal index. */ 252 int tdq_id; /* cpuid. */ 253 struct runq tdq_realtime; /* real-time run queue. */ 254 struct runq tdq_timeshare; /* timeshare run queue. */ 255 struct runq tdq_idle; /* Queue of IDLE threads. */ 256 char tdq_name[TDQ_NAME_LEN]; 257 #ifdef KTR 258 char tdq_loadname[TDQ_LOADNAME_LEN]; 259 #endif 260 } __aligned(64); 261 262 /* Idle thread states and config. */ 263 #define TDQ_RUNNING 1 264 #define TDQ_IDLE 2 265 266 #ifdef SMP 267 struct cpu_group __read_mostly *cpu_top; /* CPU topology */ 268 269 #define SCHED_AFFINITY_DEFAULT (max(1, hz / 1000)) 270 #define SCHED_AFFINITY(ts, t) ((ts)->ts_rltick > ticks - ((t) * affinity)) 271 272 /* 273 * Run-time tunables. 274 */ 275 static int rebalance = 1; 276 static int balance_interval = 128; /* Default set in sched_initticks(). */ 277 static int __read_mostly affinity; 278 static int __read_mostly steal_idle = 1; 279 static int __read_mostly steal_thresh = 2; 280 static int __read_mostly always_steal = 0; 281 static int __read_mostly trysteal_limit = 2; 282 283 /* 284 * One thread queue per processor. 285 */ 286 static struct tdq __read_mostly *balance_tdq; 287 static int balance_ticks; 288 DPCPU_DEFINE_STATIC(struct tdq, tdq); 289 DPCPU_DEFINE_STATIC(uint32_t, randomval); 290 291 #define TDQ_SELF() ((struct tdq *)PCPU_GET(sched)) 292 #define TDQ_CPU(x) (DPCPU_ID_PTR((x), tdq)) 293 #define TDQ_ID(x) ((x)->tdq_id) 294 #else /* !SMP */ 295 static struct tdq tdq_cpu; 296 297 #define TDQ_ID(x) (0) 298 #define TDQ_SELF() (&tdq_cpu) 299 #define TDQ_CPU(x) (&tdq_cpu) 300 #endif 301 302 #define TDQ_LOCK_ASSERT(t, type) mtx_assert(TDQ_LOCKPTR((t)), (type)) 303 #define TDQ_LOCK(t) mtx_lock_spin(TDQ_LOCKPTR((t))) 304 #define TDQ_LOCK_FLAGS(t, f) mtx_lock_spin_flags(TDQ_LOCKPTR((t)), (f)) 305 #define TDQ_TRYLOCK(t) mtx_trylock_spin(TDQ_LOCKPTR((t))) 306 #define TDQ_TRYLOCK_FLAGS(t, f) mtx_trylock_spin_flags(TDQ_LOCKPTR((t)), (f)) 307 #define TDQ_UNLOCK(t) mtx_unlock_spin(TDQ_LOCKPTR((t))) 308 #define TDQ_LOCKPTR(t) ((struct mtx *)(&(t)->tdq_lock)) 309 310 static void sched_priority(struct thread *); 311 static void sched_thread_priority(struct thread *, u_char); 312 static int sched_interact_score(struct thread *); 313 static void sched_interact_update(struct thread *); 314 static void sched_interact_fork(struct thread *); 315 static void sched_pctcpu_update(struct td_sched *, int); 316 317 /* Operations on per processor queues */ 318 static struct thread *tdq_choose(struct tdq *); 319 static void tdq_setup(struct tdq *, int i); 320 static void tdq_load_add(struct tdq *, struct thread *); 321 static void tdq_load_rem(struct tdq *, struct thread *); 322 static __inline void tdq_runq_add(struct tdq *, struct thread *, int); 323 static __inline void tdq_runq_rem(struct tdq *, struct thread *); 324 static inline int sched_shouldpreempt(int, int, int); 325 void tdq_print(int cpu); 326 static void runq_print(struct runq *rq); 327 static int tdq_add(struct tdq *, struct thread *, int); 328 #ifdef SMP 329 static int tdq_move(struct tdq *, struct tdq *); 330 static int tdq_idled(struct tdq *); 331 static void tdq_notify(struct tdq *, int lowpri); 332 static struct thread *tdq_steal(struct tdq *, int); 333 static struct thread *runq_steal(struct runq *, int); 334 static int sched_pickcpu(struct thread *, int); 335 static void sched_balance(void); 336 static bool sched_balance_pair(struct tdq *, struct tdq *); 337 static inline struct tdq *sched_setcpu(struct thread *, int, int); 338 static inline void thread_unblock_switch(struct thread *, struct mtx *); 339 static int sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS); 340 static int sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, 341 struct cpu_group *cg, int indent); 342 #endif 343 344 static void sched_setup(void *dummy); 345 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL); 346 347 static void sched_initticks(void *dummy); 348 SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks, 349 NULL); 350 351 SDT_PROVIDER_DEFINE(sched); 352 353 SDT_PROBE_DEFINE3(sched, , , change__pri, "struct thread *", 354 "struct proc *", "uint8_t"); 355 SDT_PROBE_DEFINE3(sched, , , dequeue, "struct thread *", 356 "struct proc *", "void *"); 357 SDT_PROBE_DEFINE4(sched, , , enqueue, "struct thread *", 358 "struct proc *", "void *", "int"); 359 SDT_PROBE_DEFINE4(sched, , , lend__pri, "struct thread *", 360 "struct proc *", "uint8_t", "struct thread *"); 361 SDT_PROBE_DEFINE2(sched, , , load__change, "int", "int"); 362 SDT_PROBE_DEFINE2(sched, , , off__cpu, "struct thread *", 363 "struct proc *"); 364 SDT_PROBE_DEFINE(sched, , , on__cpu); 365 SDT_PROBE_DEFINE(sched, , , remain__cpu); 366 SDT_PROBE_DEFINE2(sched, , , surrender, "struct thread *", 367 "struct proc *"); 368 369 /* 370 * Print the threads waiting on a run-queue. 371 */ 372 static void 373 runq_print(struct runq *rq) 374 { 375 struct rqhead *rqh; 376 struct thread *td; 377 int pri; 378 int j; 379 int i; 380 381 for (i = 0; i < RQB_LEN; i++) { 382 printf("\t\trunq bits %d 0x%zx\n", 383 i, rq->rq_status.rqb_bits[i]); 384 for (j = 0; j < RQB_BPW; j++) 385 if (rq->rq_status.rqb_bits[i] & (1ul << j)) { 386 pri = j + (i << RQB_L2BPW); 387 rqh = &rq->rq_queues[pri]; 388 TAILQ_FOREACH(td, rqh, td_runq) { 389 printf("\t\t\ttd %p(%s) priority %d rqindex %d pri %d\n", 390 td, td->td_name, td->td_priority, 391 td->td_rqindex, pri); 392 } 393 } 394 } 395 } 396 397 /* 398 * Print the status of a per-cpu thread queue. Should be a ddb show cmd. 399 */ 400 void 401 tdq_print(int cpu) 402 { 403 struct tdq *tdq; 404 405 tdq = TDQ_CPU(cpu); 406 407 printf("tdq %d:\n", TDQ_ID(tdq)); 408 printf("\tlock %p\n", TDQ_LOCKPTR(tdq)); 409 printf("\tLock name: %s\n", tdq->tdq_name); 410 printf("\tload: %d\n", tdq->tdq_load); 411 printf("\tswitch cnt: %d\n", tdq->tdq_switchcnt); 412 printf("\told switch cnt: %d\n", tdq->tdq_oldswitchcnt); 413 printf("\ttimeshare idx: %d\n", tdq->tdq_idx); 414 printf("\ttimeshare ridx: %d\n", tdq->tdq_ridx); 415 printf("\tload transferable: %d\n", tdq->tdq_transferable); 416 printf("\tlowest priority: %d\n", tdq->tdq_lowpri); 417 printf("\trealtime runq:\n"); 418 runq_print(&tdq->tdq_realtime); 419 printf("\ttimeshare runq:\n"); 420 runq_print(&tdq->tdq_timeshare); 421 printf("\tidle runq:\n"); 422 runq_print(&tdq->tdq_idle); 423 } 424 425 static inline int 426 sched_shouldpreempt(int pri, int cpri, int remote) 427 { 428 /* 429 * If the new priority is not better than the current priority there is 430 * nothing to do. 431 */ 432 if (pri >= cpri) 433 return (0); 434 /* 435 * Always preempt idle. 436 */ 437 if (cpri >= PRI_MIN_IDLE) 438 return (1); 439 /* 440 * If preemption is disabled don't preempt others. 441 */ 442 if (preempt_thresh == 0) 443 return (0); 444 /* 445 * Preempt if we exceed the threshold. 446 */ 447 if (pri <= preempt_thresh) 448 return (1); 449 /* 450 * If we're interactive or better and there is non-interactive 451 * or worse running preempt only remote processors. 452 */ 453 if (remote && pri <= PRI_MAX_INTERACT && cpri > PRI_MAX_INTERACT) 454 return (1); 455 return (0); 456 } 457 458 /* 459 * Add a thread to the actual run-queue. Keeps transferable counts up to 460 * date with what is actually on the run-queue. Selects the correct 461 * queue position for timeshare threads. 462 */ 463 static __inline void 464 tdq_runq_add(struct tdq *tdq, struct thread *td, int flags) 465 { 466 struct td_sched *ts; 467 u_char pri; 468 469 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 470 THREAD_LOCK_BLOCKED_ASSERT(td, MA_OWNED); 471 472 pri = td->td_priority; 473 ts = td_get_sched(td); 474 TD_SET_RUNQ(td); 475 if (THREAD_CAN_MIGRATE(td)) { 476 tdq->tdq_transferable++; 477 ts->ts_flags |= TSF_XFERABLE; 478 } 479 if (pri < PRI_MIN_BATCH) { 480 ts->ts_runq = &tdq->tdq_realtime; 481 } else if (pri <= PRI_MAX_BATCH) { 482 ts->ts_runq = &tdq->tdq_timeshare; 483 KASSERT(pri <= PRI_MAX_BATCH && pri >= PRI_MIN_BATCH, 484 ("Invalid priority %d on timeshare runq", pri)); 485 /* 486 * This queue contains only priorities between MIN and MAX 487 * batch. Use the whole queue to represent these values. 488 */ 489 if ((flags & (SRQ_BORROWING|SRQ_PREEMPTED)) == 0) { 490 pri = RQ_NQS * (pri - PRI_MIN_BATCH) / PRI_BATCH_RANGE; 491 pri = (pri + tdq->tdq_idx) % RQ_NQS; 492 /* 493 * This effectively shortens the queue by one so we 494 * can have a one slot difference between idx and 495 * ridx while we wait for threads to drain. 496 */ 497 if (tdq->tdq_ridx != tdq->tdq_idx && 498 pri == tdq->tdq_ridx) 499 pri = (unsigned char)(pri - 1) % RQ_NQS; 500 } else 501 pri = tdq->tdq_ridx; 502 runq_add_pri(ts->ts_runq, td, pri, flags); 503 return; 504 } else 505 ts->ts_runq = &tdq->tdq_idle; 506 runq_add(ts->ts_runq, td, flags); 507 } 508 509 /* 510 * Remove a thread from a run-queue. This typically happens when a thread 511 * is selected to run. Running threads are not on the queue and the 512 * transferable count does not reflect them. 513 */ 514 static __inline void 515 tdq_runq_rem(struct tdq *tdq, struct thread *td) 516 { 517 struct td_sched *ts; 518 519 ts = td_get_sched(td); 520 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 521 THREAD_LOCK_BLOCKED_ASSERT(td, MA_OWNED); 522 KASSERT(ts->ts_runq != NULL, 523 ("tdq_runq_remove: thread %p null ts_runq", td)); 524 if (ts->ts_flags & TSF_XFERABLE) { 525 tdq->tdq_transferable--; 526 ts->ts_flags &= ~TSF_XFERABLE; 527 } 528 if (ts->ts_runq == &tdq->tdq_timeshare) { 529 if (tdq->tdq_idx != tdq->tdq_ridx) 530 runq_remove_idx(ts->ts_runq, td, &tdq->tdq_ridx); 531 else 532 runq_remove_idx(ts->ts_runq, td, NULL); 533 } else 534 runq_remove(ts->ts_runq, td); 535 } 536 537 /* 538 * Load is maintained for all threads RUNNING and ON_RUNQ. Add the load 539 * for this thread to the referenced thread queue. 540 */ 541 static void 542 tdq_load_add(struct tdq *tdq, struct thread *td) 543 { 544 545 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 546 THREAD_LOCK_BLOCKED_ASSERT(td, MA_OWNED); 547 548 tdq->tdq_load++; 549 if ((td->td_flags & TDF_NOLOAD) == 0) 550 tdq->tdq_sysload++; 551 KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load); 552 SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load); 553 } 554 555 /* 556 * Remove the load from a thread that is transitioning to a sleep state or 557 * exiting. 558 */ 559 static void 560 tdq_load_rem(struct tdq *tdq, struct thread *td) 561 { 562 563 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 564 THREAD_LOCK_BLOCKED_ASSERT(td, MA_OWNED); 565 KASSERT(tdq->tdq_load != 0, 566 ("tdq_load_rem: Removing with 0 load on queue %d", TDQ_ID(tdq))); 567 568 tdq->tdq_load--; 569 if ((td->td_flags & TDF_NOLOAD) == 0) 570 tdq->tdq_sysload--; 571 KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load); 572 SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load); 573 } 574 575 /* 576 * Bound timeshare latency by decreasing slice size as load increases. We 577 * consider the maximum latency as the sum of the threads waiting to run 578 * aside from curthread and target no more than sched_slice latency but 579 * no less than sched_slice_min runtime. 580 */ 581 static inline int 582 tdq_slice(struct tdq *tdq) 583 { 584 int load; 585 586 /* 587 * It is safe to use sys_load here because this is called from 588 * contexts where timeshare threads are running and so there 589 * cannot be higher priority load in the system. 590 */ 591 load = tdq->tdq_sysload - 1; 592 if (load >= SCHED_SLICE_MIN_DIVISOR) 593 return (sched_slice_min); 594 if (load <= 1) 595 return (sched_slice); 596 return (sched_slice / load); 597 } 598 599 /* 600 * Set lowpri to its exact value by searching the run-queue and 601 * evaluating curthread. curthread may be passed as an optimization. 602 */ 603 static void 604 tdq_setlowpri(struct tdq *tdq, struct thread *ctd) 605 { 606 struct thread *td; 607 608 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 609 if (ctd == NULL) 610 ctd = atomic_load_ptr(&tdq->tdq_curthread); 611 td = tdq_choose(tdq); 612 if (td == NULL || td->td_priority > ctd->td_priority) 613 tdq->tdq_lowpri = ctd->td_priority; 614 else 615 tdq->tdq_lowpri = td->td_priority; 616 } 617 618 #ifdef SMP 619 /* 620 * We need some randomness. Implement a classic Linear Congruential 621 * Generator X_{n+1}=(aX_n+c) mod m. These values are optimized for 622 * m = 2^32, a = 69069 and c = 5. We only return the upper 16 bits 623 * of the random state (in the low bits of our answer) to keep 624 * the maximum randomness. 625 */ 626 static uint32_t 627 sched_random(void) 628 { 629 uint32_t *rndptr; 630 631 rndptr = DPCPU_PTR(randomval); 632 *rndptr = *rndptr * 69069 + 5; 633 634 return (*rndptr >> 16); 635 } 636 637 struct cpu_search { 638 cpuset_t *cs_mask; /* The mask of allowed CPUs to choose from. */ 639 int cs_prefer; /* Prefer this CPU and groups including it. */ 640 int cs_running; /* The thread is now running at cs_prefer. */ 641 int cs_pri; /* Min priority for low. */ 642 int cs_load; /* Max load for low, min load for high. */ 643 int cs_trans; /* Min transferable load for high. */ 644 }; 645 646 struct cpu_search_res { 647 int csr_cpu; /* The best CPU found. */ 648 int csr_load; /* The load of cs_cpu. */ 649 }; 650 651 /* 652 * Search the tree of cpu_groups for the lowest or highest loaded CPU. 653 * These routines actually compare the load on all paths through the tree 654 * and find the least loaded cpu on the least loaded path, which may differ 655 * from the least loaded cpu in the system. This balances work among caches 656 * and buses. 657 */ 658 static int 659 cpu_search_lowest(const struct cpu_group *cg, const struct cpu_search *s, 660 struct cpu_search_res *r) 661 { 662 struct cpu_search_res lr; 663 struct tdq *tdq; 664 int c, bload, l, load, p, total; 665 666 total = 0; 667 bload = INT_MAX; 668 r->csr_cpu = -1; 669 670 /* Loop through children CPU groups if there are any. */ 671 if (cg->cg_children > 0) { 672 for (c = cg->cg_children - 1; c >= 0; c--) { 673 load = cpu_search_lowest(&cg->cg_child[c], s, &lr); 674 total += load; 675 676 /* 677 * When balancing do not prefer SMT groups with load >1. 678 * It allows round-robin between SMT groups with equal 679 * load within parent group for more fair scheduling. 680 */ 681 if (__predict_false(s->cs_running) && 682 (cg->cg_child[c].cg_flags & CG_FLAG_THREAD) && 683 load >= 128 && (load & 128) != 0) 684 load += 128; 685 686 if (lr.csr_cpu >= 0 && (load < bload || 687 (load == bload && lr.csr_load < r->csr_load))) { 688 bload = load; 689 r->csr_cpu = lr.csr_cpu; 690 r->csr_load = lr.csr_load; 691 } 692 } 693 return (total); 694 } 695 696 /* Loop through children CPUs otherwise. */ 697 for (c = cg->cg_last; c >= cg->cg_first; c--) { 698 if (!CPU_ISSET(c, &cg->cg_mask)) 699 continue; 700 tdq = TDQ_CPU(c); 701 l = tdq->tdq_load; 702 if (c == s->cs_prefer) { 703 if (__predict_false(s->cs_running)) 704 l--; 705 p = 128; 706 } else 707 p = 0; 708 load = l * 256; 709 total += load - p; 710 711 /* 712 * Check this CPU is acceptable. 713 * If the threads is already on the CPU, don't look on the TDQ 714 * priority, since it can be the priority of the thread itself. 715 */ 716 if (l > s->cs_load || (tdq->tdq_lowpri <= s->cs_pri && 717 (!s->cs_running || c != s->cs_prefer)) || 718 !CPU_ISSET(c, s->cs_mask)) 719 continue; 720 721 /* 722 * When balancing do not prefer CPUs with load > 1. 723 * It allows round-robin between CPUs with equal load 724 * within the CPU group for more fair scheduling. 725 */ 726 if (__predict_false(s->cs_running) && l > 0) 727 p = 0; 728 729 load -= sched_random() % 128; 730 if (bload > load - p) { 731 bload = load - p; 732 r->csr_cpu = c; 733 r->csr_load = load; 734 } 735 } 736 return (total); 737 } 738 739 static int 740 cpu_search_highest(const struct cpu_group *cg, const struct cpu_search *s, 741 struct cpu_search_res *r) 742 { 743 struct cpu_search_res lr; 744 struct tdq *tdq; 745 int c, bload, l, load, total; 746 747 total = 0; 748 bload = INT_MIN; 749 r->csr_cpu = -1; 750 751 /* Loop through children CPU groups if there are any. */ 752 if (cg->cg_children > 0) { 753 for (c = cg->cg_children - 1; c >= 0; c--) { 754 load = cpu_search_highest(&cg->cg_child[c], s, &lr); 755 total += load; 756 if (lr.csr_cpu >= 0 && (load > bload || 757 (load == bload && lr.csr_load > r->csr_load))) { 758 bload = load; 759 r->csr_cpu = lr.csr_cpu; 760 r->csr_load = lr.csr_load; 761 } 762 } 763 return (total); 764 } 765 766 /* Loop through children CPUs otherwise. */ 767 for (c = cg->cg_last; c >= cg->cg_first; c--) { 768 if (!CPU_ISSET(c, &cg->cg_mask)) 769 continue; 770 tdq = TDQ_CPU(c); 771 l = tdq->tdq_load; 772 load = l * 256; 773 total += load; 774 775 /* 776 * Check this CPU is acceptable. 777 */ 778 if (l < s->cs_load || (tdq->tdq_transferable < s->cs_trans) || 779 !CPU_ISSET(c, s->cs_mask)) 780 continue; 781 782 load -= sched_random() % 256; 783 if (load > bload) { 784 bload = load; 785 r->csr_cpu = c; 786 } 787 } 788 r->csr_load = bload; 789 return (total); 790 } 791 792 /* 793 * Find the cpu with the least load via the least loaded path that has a 794 * lowpri greater than pri pri. A pri of -1 indicates any priority is 795 * acceptable. 796 */ 797 static inline int 798 sched_lowest(const struct cpu_group *cg, cpuset_t *mask, int pri, int maxload, 799 int prefer, int running) 800 { 801 struct cpu_search s; 802 struct cpu_search_res r; 803 804 s.cs_prefer = prefer; 805 s.cs_running = running; 806 s.cs_mask = mask; 807 s.cs_pri = pri; 808 s.cs_load = maxload; 809 cpu_search_lowest(cg, &s, &r); 810 return (r.csr_cpu); 811 } 812 813 /* 814 * Find the cpu with the highest load via the highest loaded path. 815 */ 816 static inline int 817 sched_highest(const struct cpu_group *cg, cpuset_t *mask, int minload, 818 int mintrans) 819 { 820 struct cpu_search s; 821 struct cpu_search_res r; 822 823 s.cs_mask = mask; 824 s.cs_load = minload; 825 s.cs_trans = mintrans; 826 cpu_search_highest(cg, &s, &r); 827 return (r.csr_cpu); 828 } 829 830 static void 831 sched_balance_group(struct cpu_group *cg) 832 { 833 struct tdq *tdq; 834 struct thread *td; 835 cpuset_t hmask, lmask; 836 int high, low, anylow; 837 838 CPU_FILL(&hmask); 839 for (;;) { 840 high = sched_highest(cg, &hmask, 1, 0); 841 /* Stop if there is no more CPU with transferrable threads. */ 842 if (high == -1) 843 break; 844 CPU_CLR(high, &hmask); 845 CPU_COPY(&hmask, &lmask); 846 /* Stop if there is no more CPU left for low. */ 847 if (CPU_EMPTY(&lmask)) 848 break; 849 tdq = TDQ_CPU(high); 850 if (tdq->tdq_load == 1) { 851 /* 852 * There is only one running thread. We can't move 853 * it from here, so tell it to pick new CPU by itself. 854 */ 855 TDQ_LOCK(tdq); 856 td = atomic_load_ptr(&tdq->tdq_curthread); 857 if ((td->td_flags & TDF_IDLETD) == 0 && 858 THREAD_CAN_MIGRATE(td)) { 859 td->td_flags |= TDF_NEEDRESCHED | TDF_PICKCPU; 860 if (high != curcpu) 861 ipi_cpu(high, IPI_AST); 862 } 863 TDQ_UNLOCK(tdq); 864 break; 865 } 866 anylow = 1; 867 nextlow: 868 if (tdq->tdq_transferable == 0) 869 continue; 870 low = sched_lowest(cg, &lmask, -1, tdq->tdq_load - 1, high, 1); 871 /* Stop if we looked well and found no less loaded CPU. */ 872 if (anylow && low == -1) 873 break; 874 /* Go to next high if we found no less loaded CPU. */ 875 if (low == -1) 876 continue; 877 /* Transfer thread from high to low. */ 878 if (sched_balance_pair(tdq, TDQ_CPU(low))) { 879 /* CPU that got thread can no longer be a donor. */ 880 CPU_CLR(low, &hmask); 881 } else { 882 /* 883 * If failed, then there is no threads on high 884 * that can run on this low. Drop low from low 885 * mask and look for different one. 886 */ 887 CPU_CLR(low, &lmask); 888 anylow = 0; 889 goto nextlow; 890 } 891 } 892 } 893 894 static void 895 sched_balance(void) 896 { 897 struct tdq *tdq; 898 899 balance_ticks = max(balance_interval / 2, 1) + 900 (sched_random() % balance_interval); 901 tdq = TDQ_SELF(); 902 TDQ_UNLOCK(tdq); 903 sched_balance_group(cpu_top); 904 TDQ_LOCK(tdq); 905 } 906 907 /* 908 * Lock two thread queues using their address to maintain lock order. 909 */ 910 static void 911 tdq_lock_pair(struct tdq *one, struct tdq *two) 912 { 913 if (one < two) { 914 TDQ_LOCK(one); 915 TDQ_LOCK_FLAGS(two, MTX_DUPOK); 916 } else { 917 TDQ_LOCK(two); 918 TDQ_LOCK_FLAGS(one, MTX_DUPOK); 919 } 920 } 921 922 /* 923 * Unlock two thread queues. Order is not important here. 924 */ 925 static void 926 tdq_unlock_pair(struct tdq *one, struct tdq *two) 927 { 928 TDQ_UNLOCK(one); 929 TDQ_UNLOCK(two); 930 } 931 932 /* 933 * Transfer load between two imbalanced thread queues. Returns true if a thread 934 * was moved between the queues, and false otherwise. 935 */ 936 static bool 937 sched_balance_pair(struct tdq *high, struct tdq *low) 938 { 939 int cpu, lowpri; 940 bool ret; 941 942 ret = false; 943 tdq_lock_pair(high, low); 944 945 /* 946 * Transfer a thread from high to low. 947 */ 948 if (high->tdq_transferable != 0 && high->tdq_load > low->tdq_load) { 949 lowpri = tdq_move(high, low); 950 if (lowpri != -1) { 951 /* 952 * In case the target isn't the current cpu notify it of 953 * the new load, possibly sending an IPI to force it to 954 * reschedule. 955 */ 956 cpu = TDQ_ID(low); 957 if (cpu != PCPU_GET(cpuid)) 958 tdq_notify(low, lowpri); 959 ret = true; 960 } 961 } 962 tdq_unlock_pair(high, low); 963 return (ret); 964 } 965 966 /* 967 * Move a thread from one thread queue to another. Returns -1 if the source 968 * queue was empty, else returns the maximum priority of all threads in 969 * the destination queue prior to the addition of the new thread. In the latter 970 * case, this priority can be used to determine whether an IPI needs to be 971 * delivered. 972 */ 973 static int 974 tdq_move(struct tdq *from, struct tdq *to) 975 { 976 struct thread *td; 977 int cpu; 978 979 TDQ_LOCK_ASSERT(from, MA_OWNED); 980 TDQ_LOCK_ASSERT(to, MA_OWNED); 981 982 cpu = TDQ_ID(to); 983 td = tdq_steal(from, cpu); 984 if (td == NULL) 985 return (-1); 986 987 /* 988 * Although the run queue is locked the thread may be 989 * blocked. We can not set the lock until it is unblocked. 990 */ 991 thread_lock_block_wait(td); 992 sched_rem(td); 993 THREAD_LOCKPTR_ASSERT(td, TDQ_LOCKPTR(from)); 994 td->td_lock = TDQ_LOCKPTR(to); 995 td_get_sched(td)->ts_cpu = cpu; 996 return (tdq_add(to, td, SRQ_YIELDING)); 997 } 998 999 /* 1000 * This tdq has idled. Try to steal a thread from another cpu and switch 1001 * to it. 1002 */ 1003 static int 1004 tdq_idled(struct tdq *tdq) 1005 { 1006 struct cpu_group *cg, *parent; 1007 struct tdq *steal; 1008 cpuset_t mask; 1009 int cpu, switchcnt, goup; 1010 1011 if (smp_started == 0 || steal_idle == 0 || tdq->tdq_cg == NULL) 1012 return (1); 1013 CPU_FILL(&mask); 1014 CPU_CLR(PCPU_GET(cpuid), &mask); 1015 restart: 1016 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 1017 for (cg = tdq->tdq_cg, goup = 0; ; ) { 1018 cpu = sched_highest(cg, &mask, steal_thresh, 1); 1019 /* 1020 * We were assigned a thread but not preempted. Returning 1021 * 0 here will cause our caller to switch to it. 1022 */ 1023 if (tdq->tdq_load) 1024 return (0); 1025 1026 /* 1027 * We found no CPU to steal from in this group. Escalate to 1028 * the parent and repeat. But if parent has only two children 1029 * groups we can avoid searching this group again by searching 1030 * the other one specifically and then escalating two levels. 1031 */ 1032 if (cpu == -1) { 1033 if (goup) { 1034 cg = cg->cg_parent; 1035 goup = 0; 1036 } 1037 parent = cg->cg_parent; 1038 if (parent == NULL) 1039 return (1); 1040 if (parent->cg_children == 2) { 1041 if (cg == &parent->cg_child[0]) 1042 cg = &parent->cg_child[1]; 1043 else 1044 cg = &parent->cg_child[0]; 1045 goup = 1; 1046 } else 1047 cg = parent; 1048 continue; 1049 } 1050 steal = TDQ_CPU(cpu); 1051 /* 1052 * The data returned by sched_highest() is stale and 1053 * the chosen CPU no longer has an eligible thread. 1054 * 1055 * Testing this ahead of tdq_lock_pair() only catches 1056 * this situation about 20% of the time on an 8 core 1057 * 16 thread Ryzen 7, but it still helps performance. 1058 */ 1059 if (steal->tdq_load < steal_thresh || 1060 steal->tdq_transferable == 0) 1061 goto restart; 1062 /* 1063 * Try to lock both queues. If we are assigned a thread while 1064 * waited for the lock, switch to it now instead of stealing. 1065 * If we can't get the lock, then somebody likely got there 1066 * first so continue searching. 1067 */ 1068 TDQ_LOCK(tdq); 1069 if (tdq->tdq_load > 0) { 1070 mi_switch(SW_VOL | SWT_IDLE); 1071 return (0); 1072 } 1073 if (TDQ_TRYLOCK_FLAGS(steal, MTX_DUPOK) == 0) { 1074 TDQ_UNLOCK(tdq); 1075 CPU_CLR(cpu, &mask); 1076 continue; 1077 } 1078 /* 1079 * The data returned by sched_highest() is stale and 1080 * the chosen CPU no longer has an eligible thread, or 1081 * we were preempted and the CPU loading info may be out 1082 * of date. The latter is rare. In either case restart 1083 * the search. 1084 */ 1085 if (steal->tdq_load < steal_thresh || 1086 steal->tdq_transferable == 0 || 1087 switchcnt != tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt) { 1088 tdq_unlock_pair(tdq, steal); 1089 goto restart; 1090 } 1091 /* 1092 * Steal the thread and switch to it. 1093 */ 1094 if (tdq_move(steal, tdq) != -1) 1095 break; 1096 /* 1097 * We failed to acquire a thread even though it looked 1098 * like one was available. This could be due to affinity 1099 * restrictions or for other reasons. Loop again after 1100 * removing this CPU from the set. The restart logic 1101 * above does not restore this CPU to the set due to the 1102 * likelyhood of failing here again. 1103 */ 1104 CPU_CLR(cpu, &mask); 1105 tdq_unlock_pair(tdq, steal); 1106 } 1107 TDQ_UNLOCK(steal); 1108 mi_switch(SW_VOL | SWT_IDLE); 1109 return (0); 1110 } 1111 1112 /* 1113 * Notify a remote cpu of new work. Sends an IPI if criteria are met. 1114 * 1115 * "lowpri" is the minimum scheduling priority among all threads on 1116 * the queue prior to the addition of the new thread. 1117 */ 1118 static void 1119 tdq_notify(struct tdq *tdq, int lowpri) 1120 { 1121 int cpu; 1122 1123 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1124 KASSERT(tdq->tdq_lowpri <= lowpri, 1125 ("tdq_notify: lowpri %d > tdq_lowpri %d", lowpri, tdq->tdq_lowpri)); 1126 1127 if (tdq->tdq_owepreempt) 1128 return; 1129 1130 /* 1131 * Check to see if the newly added thread should preempt the one 1132 * currently running. 1133 */ 1134 if (!sched_shouldpreempt(tdq->tdq_lowpri, lowpri, 1)) 1135 return; 1136 1137 /* 1138 * Make sure that our caller's earlier update to tdq_load is 1139 * globally visible before we read tdq_cpu_idle. Idle thread 1140 * accesses both of them without locks, and the order is important. 1141 */ 1142 atomic_thread_fence_seq_cst(); 1143 1144 /* 1145 * Try to figure out if we can signal the idle thread instead of sending 1146 * an IPI. This check is racy; at worst, we will deliever an IPI 1147 * unnecessarily. 1148 */ 1149 cpu = TDQ_ID(tdq); 1150 if (TD_IS_IDLETHREAD(tdq->tdq_curthread) && 1151 (tdq->tdq_cpu_idle == 0 || cpu_idle_wakeup(cpu))) 1152 return; 1153 1154 /* 1155 * The run queues have been updated, so any switch on the remote CPU 1156 * will satisfy the preemption request. 1157 */ 1158 tdq->tdq_owepreempt = 1; 1159 ipi_cpu(cpu, IPI_PREEMPT); 1160 } 1161 1162 /* 1163 * Steals load from a timeshare queue. Honors the rotating queue head 1164 * index. 1165 */ 1166 static struct thread * 1167 runq_steal_from(struct runq *rq, int cpu, u_char start) 1168 { 1169 struct rqbits *rqb; 1170 struct rqhead *rqh; 1171 struct thread *td, *first; 1172 int bit; 1173 int i; 1174 1175 rqb = &rq->rq_status; 1176 bit = start & (RQB_BPW -1); 1177 first = NULL; 1178 again: 1179 for (i = RQB_WORD(start); i < RQB_LEN; bit = 0, i++) { 1180 if (rqb->rqb_bits[i] == 0) 1181 continue; 1182 if (bit == 0) 1183 bit = RQB_FFS(rqb->rqb_bits[i]); 1184 for (; bit < RQB_BPW; bit++) { 1185 if ((rqb->rqb_bits[i] & (1ul << bit)) == 0) 1186 continue; 1187 rqh = &rq->rq_queues[bit + (i << RQB_L2BPW)]; 1188 TAILQ_FOREACH(td, rqh, td_runq) { 1189 if (first) { 1190 if (THREAD_CAN_MIGRATE(td) && 1191 THREAD_CAN_SCHED(td, cpu)) 1192 return (td); 1193 } else 1194 first = td; 1195 } 1196 } 1197 } 1198 if (start != 0) { 1199 start = 0; 1200 goto again; 1201 } 1202 1203 if (first && THREAD_CAN_MIGRATE(first) && 1204 THREAD_CAN_SCHED(first, cpu)) 1205 return (first); 1206 return (NULL); 1207 } 1208 1209 /* 1210 * Steals load from a standard linear queue. 1211 */ 1212 static struct thread * 1213 runq_steal(struct runq *rq, int cpu) 1214 { 1215 struct rqhead *rqh; 1216 struct rqbits *rqb; 1217 struct thread *td; 1218 int word; 1219 int bit; 1220 1221 rqb = &rq->rq_status; 1222 for (word = 0; word < RQB_LEN; word++) { 1223 if (rqb->rqb_bits[word] == 0) 1224 continue; 1225 for (bit = 0; bit < RQB_BPW; bit++) { 1226 if ((rqb->rqb_bits[word] & (1ul << bit)) == 0) 1227 continue; 1228 rqh = &rq->rq_queues[bit + (word << RQB_L2BPW)]; 1229 TAILQ_FOREACH(td, rqh, td_runq) 1230 if (THREAD_CAN_MIGRATE(td) && 1231 THREAD_CAN_SCHED(td, cpu)) 1232 return (td); 1233 } 1234 } 1235 return (NULL); 1236 } 1237 1238 /* 1239 * Attempt to steal a thread in priority order from a thread queue. 1240 */ 1241 static struct thread * 1242 tdq_steal(struct tdq *tdq, int cpu) 1243 { 1244 struct thread *td; 1245 1246 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1247 if ((td = runq_steal(&tdq->tdq_realtime, cpu)) != NULL) 1248 return (td); 1249 if ((td = runq_steal_from(&tdq->tdq_timeshare, 1250 cpu, tdq->tdq_ridx)) != NULL) 1251 return (td); 1252 return (runq_steal(&tdq->tdq_idle, cpu)); 1253 } 1254 1255 /* 1256 * Sets the thread lock and ts_cpu to match the requested cpu. Unlocks the 1257 * current lock and returns with the assigned queue locked. 1258 */ 1259 static inline struct tdq * 1260 sched_setcpu(struct thread *td, int cpu, int flags) 1261 { 1262 1263 struct tdq *tdq; 1264 struct mtx *mtx; 1265 1266 THREAD_LOCK_ASSERT(td, MA_OWNED); 1267 tdq = TDQ_CPU(cpu); 1268 td_get_sched(td)->ts_cpu = cpu; 1269 /* 1270 * If the lock matches just return the queue. 1271 */ 1272 if (td->td_lock == TDQ_LOCKPTR(tdq)) { 1273 KASSERT((flags & SRQ_HOLD) == 0, 1274 ("sched_setcpu: Invalid lock for SRQ_HOLD")); 1275 return (tdq); 1276 } 1277 1278 /* 1279 * The hard case, migration, we need to block the thread first to 1280 * prevent order reversals with other cpus locks. 1281 */ 1282 spinlock_enter(); 1283 mtx = thread_lock_block(td); 1284 if ((flags & SRQ_HOLD) == 0) 1285 mtx_unlock_spin(mtx); 1286 TDQ_LOCK(tdq); 1287 thread_lock_unblock(td, TDQ_LOCKPTR(tdq)); 1288 spinlock_exit(); 1289 return (tdq); 1290 } 1291 1292 SCHED_STAT_DEFINE(pickcpu_intrbind, "Soft interrupt binding"); 1293 SCHED_STAT_DEFINE(pickcpu_idle_affinity, "Picked idle cpu based on affinity"); 1294 SCHED_STAT_DEFINE(pickcpu_affinity, "Picked cpu based on affinity"); 1295 SCHED_STAT_DEFINE(pickcpu_lowest, "Selected lowest load"); 1296 SCHED_STAT_DEFINE(pickcpu_local, "Migrated to current cpu"); 1297 SCHED_STAT_DEFINE(pickcpu_migration, "Selection may have caused migration"); 1298 1299 static int 1300 sched_pickcpu(struct thread *td, int flags) 1301 { 1302 struct cpu_group *cg, *ccg; 1303 struct td_sched *ts; 1304 struct tdq *tdq; 1305 cpuset_t *mask; 1306 int cpu, pri, r, self, intr; 1307 1308 self = PCPU_GET(cpuid); 1309 ts = td_get_sched(td); 1310 KASSERT(!CPU_ABSENT(ts->ts_cpu), ("sched_pickcpu: Start scheduler on " 1311 "absent CPU %d for thread %s.", ts->ts_cpu, td->td_name)); 1312 if (smp_started == 0) 1313 return (self); 1314 /* 1315 * Don't migrate a running thread from sched_switch(). 1316 */ 1317 if ((flags & SRQ_OURSELF) || !THREAD_CAN_MIGRATE(td)) 1318 return (ts->ts_cpu); 1319 /* 1320 * Prefer to run interrupt threads on the processors that generate 1321 * the interrupt. 1322 */ 1323 if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_SCHED(td, self) && 1324 curthread->td_intr_nesting_level) { 1325 tdq = TDQ_SELF(); 1326 if (tdq->tdq_lowpri >= PRI_MIN_IDLE) { 1327 SCHED_STAT_INC(pickcpu_idle_affinity); 1328 return (self); 1329 } 1330 ts->ts_cpu = self; 1331 intr = 1; 1332 cg = tdq->tdq_cg; 1333 goto llc; 1334 } else { 1335 intr = 0; 1336 tdq = TDQ_CPU(ts->ts_cpu); 1337 cg = tdq->tdq_cg; 1338 } 1339 /* 1340 * If the thread can run on the last cpu and the affinity has not 1341 * expired and it is idle, run it there. 1342 */ 1343 if (THREAD_CAN_SCHED(td, ts->ts_cpu) && 1344 tdq->tdq_lowpri >= PRI_MIN_IDLE && 1345 SCHED_AFFINITY(ts, CG_SHARE_L2)) { 1346 if (cg->cg_flags & CG_FLAG_THREAD) { 1347 /* Check all SMT threads for being idle. */ 1348 for (cpu = cg->cg_first; cpu <= cg->cg_last; cpu++) { 1349 if (CPU_ISSET(cpu, &cg->cg_mask) && 1350 TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE) 1351 break; 1352 } 1353 if (cpu > cg->cg_last) { 1354 SCHED_STAT_INC(pickcpu_idle_affinity); 1355 return (ts->ts_cpu); 1356 } 1357 } else { 1358 SCHED_STAT_INC(pickcpu_idle_affinity); 1359 return (ts->ts_cpu); 1360 } 1361 } 1362 llc: 1363 /* 1364 * Search for the last level cache CPU group in the tree. 1365 * Skip SMT, identical groups and caches with expired affinity. 1366 * Interrupt threads affinity is explicit and never expires. 1367 */ 1368 for (ccg = NULL; cg != NULL; cg = cg->cg_parent) { 1369 if (cg->cg_flags & CG_FLAG_THREAD) 1370 continue; 1371 if (cg->cg_children == 1 || cg->cg_count == 1) 1372 continue; 1373 if (cg->cg_level == CG_SHARE_NONE || 1374 (!intr && !SCHED_AFFINITY(ts, cg->cg_level))) 1375 continue; 1376 ccg = cg; 1377 } 1378 /* Found LLC shared by all CPUs, so do a global search. */ 1379 if (ccg == cpu_top) 1380 ccg = NULL; 1381 cpu = -1; 1382 mask = &td->td_cpuset->cs_mask; 1383 pri = td->td_priority; 1384 r = TD_IS_RUNNING(td); 1385 /* 1386 * Try hard to keep interrupts within found LLC. Search the LLC for 1387 * the least loaded CPU we can run now. For NUMA systems it should 1388 * be within target domain, and it also reduces scheduling overhead. 1389 */ 1390 if (ccg != NULL && intr) { 1391 cpu = sched_lowest(ccg, mask, pri, INT_MAX, ts->ts_cpu, r); 1392 if (cpu >= 0) 1393 SCHED_STAT_INC(pickcpu_intrbind); 1394 } else 1395 /* Search the LLC for the least loaded idle CPU we can run now. */ 1396 if (ccg != NULL) { 1397 cpu = sched_lowest(ccg, mask, max(pri, PRI_MAX_TIMESHARE), 1398 INT_MAX, ts->ts_cpu, r); 1399 if (cpu >= 0) 1400 SCHED_STAT_INC(pickcpu_affinity); 1401 } 1402 /* Search globally for the least loaded CPU we can run now. */ 1403 if (cpu < 0) { 1404 cpu = sched_lowest(cpu_top, mask, pri, INT_MAX, ts->ts_cpu, r); 1405 if (cpu >= 0) 1406 SCHED_STAT_INC(pickcpu_lowest); 1407 } 1408 /* Search globally for the least loaded CPU. */ 1409 if (cpu < 0) { 1410 cpu = sched_lowest(cpu_top, mask, -1, INT_MAX, ts->ts_cpu, r); 1411 if (cpu >= 0) 1412 SCHED_STAT_INC(pickcpu_lowest); 1413 } 1414 KASSERT(cpu >= 0, ("sched_pickcpu: Failed to find a cpu.")); 1415 KASSERT(!CPU_ABSENT(cpu), ("sched_pickcpu: Picked absent CPU %d.", cpu)); 1416 /* 1417 * Compare the lowest loaded cpu to current cpu. 1418 */ 1419 tdq = TDQ_CPU(cpu); 1420 if (THREAD_CAN_SCHED(td, self) && TDQ_SELF()->tdq_lowpri > pri && 1421 tdq->tdq_lowpri < PRI_MIN_IDLE && 1422 TDQ_SELF()->tdq_load <= tdq->tdq_load + 1) { 1423 SCHED_STAT_INC(pickcpu_local); 1424 cpu = self; 1425 } 1426 if (cpu != ts->ts_cpu) 1427 SCHED_STAT_INC(pickcpu_migration); 1428 return (cpu); 1429 } 1430 #endif 1431 1432 /* 1433 * Pick the highest priority task we have and return it. 1434 */ 1435 static struct thread * 1436 tdq_choose(struct tdq *tdq) 1437 { 1438 struct thread *td; 1439 1440 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1441 td = runq_choose(&tdq->tdq_realtime); 1442 if (td != NULL) 1443 return (td); 1444 td = runq_choose_from(&tdq->tdq_timeshare, tdq->tdq_ridx); 1445 if (td != NULL) { 1446 KASSERT(td->td_priority >= PRI_MIN_BATCH, 1447 ("tdq_choose: Invalid priority on timeshare queue %d", 1448 td->td_priority)); 1449 return (td); 1450 } 1451 td = runq_choose(&tdq->tdq_idle); 1452 if (td != NULL) { 1453 KASSERT(td->td_priority >= PRI_MIN_IDLE, 1454 ("tdq_choose: Invalid priority on idle queue %d", 1455 td->td_priority)); 1456 return (td); 1457 } 1458 1459 return (NULL); 1460 } 1461 1462 /* 1463 * Initialize a thread queue. 1464 */ 1465 static void 1466 tdq_setup(struct tdq *tdq, int id) 1467 { 1468 1469 if (bootverbose) 1470 printf("ULE: setup cpu %d\n", id); 1471 runq_init(&tdq->tdq_realtime); 1472 runq_init(&tdq->tdq_timeshare); 1473 runq_init(&tdq->tdq_idle); 1474 tdq->tdq_id = id; 1475 snprintf(tdq->tdq_name, sizeof(tdq->tdq_name), 1476 "sched lock %d", (int)TDQ_ID(tdq)); 1477 mtx_init(&tdq->tdq_lock, tdq->tdq_name, "sched lock", MTX_SPIN); 1478 #ifdef KTR 1479 snprintf(tdq->tdq_loadname, sizeof(tdq->tdq_loadname), 1480 "CPU %d load", (int)TDQ_ID(tdq)); 1481 #endif 1482 } 1483 1484 #ifdef SMP 1485 static void 1486 sched_setup_smp(void) 1487 { 1488 struct tdq *tdq; 1489 int i; 1490 1491 cpu_top = smp_topo(); 1492 CPU_FOREACH(i) { 1493 tdq = DPCPU_ID_PTR(i, tdq); 1494 tdq_setup(tdq, i); 1495 tdq->tdq_cg = smp_topo_find(cpu_top, i); 1496 if (tdq->tdq_cg == NULL) 1497 panic("Can't find cpu group for %d\n", i); 1498 DPCPU_ID_SET(i, randomval, i * 69069 + 5); 1499 } 1500 PCPU_SET(sched, DPCPU_PTR(tdq)); 1501 balance_tdq = TDQ_SELF(); 1502 } 1503 #endif 1504 1505 /* 1506 * Setup the thread queues and initialize the topology based on MD 1507 * information. 1508 */ 1509 static void 1510 sched_setup(void *dummy) 1511 { 1512 struct tdq *tdq; 1513 1514 #ifdef SMP 1515 sched_setup_smp(); 1516 #else 1517 tdq_setup(TDQ_SELF(), 0); 1518 #endif 1519 tdq = TDQ_SELF(); 1520 1521 /* Add thread0's load since it's running. */ 1522 TDQ_LOCK(tdq); 1523 thread0.td_lock = TDQ_LOCKPTR(tdq); 1524 tdq_load_add(tdq, &thread0); 1525 tdq->tdq_curthread = &thread0; 1526 tdq->tdq_lowpri = thread0.td_priority; 1527 TDQ_UNLOCK(tdq); 1528 } 1529 1530 /* 1531 * This routine determines time constants after stathz and hz are setup. 1532 */ 1533 /* ARGSUSED */ 1534 static void 1535 sched_initticks(void *dummy) 1536 { 1537 int incr; 1538 1539 realstathz = stathz ? stathz : hz; 1540 sched_slice = realstathz / SCHED_SLICE_DEFAULT_DIVISOR; 1541 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 1542 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 1543 realstathz); 1544 1545 /* 1546 * tickincr is shifted out by 10 to avoid rounding errors due to 1547 * hz not being evenly divisible by stathz on all platforms. 1548 */ 1549 incr = (hz << SCHED_TICK_SHIFT) / realstathz; 1550 /* 1551 * This does not work for values of stathz that are more than 1552 * 1 << SCHED_TICK_SHIFT * hz. In practice this does not happen. 1553 */ 1554 if (incr == 0) 1555 incr = 1; 1556 tickincr = incr; 1557 #ifdef SMP 1558 /* 1559 * Set the default balance interval now that we know 1560 * what realstathz is. 1561 */ 1562 balance_interval = realstathz; 1563 balance_ticks = balance_interval; 1564 affinity = SCHED_AFFINITY_DEFAULT; 1565 #endif 1566 if (sched_idlespinthresh < 0) 1567 sched_idlespinthresh = 2 * max(10000, 6 * hz) / realstathz; 1568 } 1569 1570 /* 1571 * This is the core of the interactivity algorithm. Determines a score based 1572 * on past behavior. It is the ratio of sleep time to run time scaled to 1573 * a [0, 100] integer. This is the voluntary sleep time of a process, which 1574 * differs from the cpu usage because it does not account for time spent 1575 * waiting on a run-queue. Would be prettier if we had floating point. 1576 * 1577 * When a thread's sleep time is greater than its run time the 1578 * calculation is: 1579 * 1580 * scaling factor 1581 * interactivity score = --------------------- 1582 * sleep time / run time 1583 * 1584 * 1585 * When a thread's run time is greater than its sleep time the 1586 * calculation is: 1587 * 1588 * scaling factor 1589 * interactivity score = 2 * scaling factor - --------------------- 1590 * run time / sleep time 1591 */ 1592 static int 1593 sched_interact_score(struct thread *td) 1594 { 1595 struct td_sched *ts; 1596 int div; 1597 1598 ts = td_get_sched(td); 1599 /* 1600 * The score is only needed if this is likely to be an interactive 1601 * task. Don't go through the expense of computing it if there's 1602 * no chance. 1603 */ 1604 if (sched_interact <= SCHED_INTERACT_HALF && 1605 ts->ts_runtime >= ts->ts_slptime) 1606 return (SCHED_INTERACT_HALF); 1607 1608 if (ts->ts_runtime > ts->ts_slptime) { 1609 div = max(1, ts->ts_runtime / SCHED_INTERACT_HALF); 1610 return (SCHED_INTERACT_HALF + 1611 (SCHED_INTERACT_HALF - (ts->ts_slptime / div))); 1612 } 1613 if (ts->ts_slptime > ts->ts_runtime) { 1614 div = max(1, ts->ts_slptime / SCHED_INTERACT_HALF); 1615 return (ts->ts_runtime / div); 1616 } 1617 /* runtime == slptime */ 1618 if (ts->ts_runtime) 1619 return (SCHED_INTERACT_HALF); 1620 1621 /* 1622 * This can happen if slptime and runtime are 0. 1623 */ 1624 return (0); 1625 1626 } 1627 1628 /* 1629 * Scale the scheduling priority according to the "interactivity" of this 1630 * process. 1631 */ 1632 static void 1633 sched_priority(struct thread *td) 1634 { 1635 u_int pri, score; 1636 1637 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 1638 return; 1639 /* 1640 * If the score is interactive we place the thread in the realtime 1641 * queue with a priority that is less than kernel and interrupt 1642 * priorities. These threads are not subject to nice restrictions. 1643 * 1644 * Scores greater than this are placed on the normal timeshare queue 1645 * where the priority is partially decided by the most recent cpu 1646 * utilization and the rest is decided by nice value. 1647 * 1648 * The nice value of the process has a linear effect on the calculated 1649 * score. Negative nice values make it easier for a thread to be 1650 * considered interactive. 1651 */ 1652 score = imax(0, sched_interact_score(td) + td->td_proc->p_nice); 1653 if (score < sched_interact) { 1654 pri = PRI_MIN_INTERACT; 1655 pri += (PRI_MAX_INTERACT - PRI_MIN_INTERACT + 1) * score / 1656 sched_interact; 1657 KASSERT(pri >= PRI_MIN_INTERACT && pri <= PRI_MAX_INTERACT, 1658 ("sched_priority: invalid interactive priority %u score %u", 1659 pri, score)); 1660 } else { 1661 pri = SCHED_PRI_MIN; 1662 if (td_get_sched(td)->ts_ticks) 1663 pri += min(SCHED_PRI_TICKS(td_get_sched(td)), 1664 SCHED_PRI_RANGE - 1); 1665 pri += SCHED_PRI_NICE(td->td_proc->p_nice); 1666 KASSERT(pri >= PRI_MIN_BATCH && pri <= PRI_MAX_BATCH, 1667 ("sched_priority: invalid priority %u: nice %d, " 1668 "ticks %d ftick %d ltick %d tick pri %d", 1669 pri, td->td_proc->p_nice, td_get_sched(td)->ts_ticks, 1670 td_get_sched(td)->ts_ftick, td_get_sched(td)->ts_ltick, 1671 SCHED_PRI_TICKS(td_get_sched(td)))); 1672 } 1673 sched_user_prio(td, pri); 1674 1675 return; 1676 } 1677 1678 /* 1679 * This routine enforces a maximum limit on the amount of scheduling history 1680 * kept. It is called after either the slptime or runtime is adjusted. This 1681 * function is ugly due to integer math. 1682 */ 1683 static void 1684 sched_interact_update(struct thread *td) 1685 { 1686 struct td_sched *ts; 1687 u_int sum; 1688 1689 ts = td_get_sched(td); 1690 sum = ts->ts_runtime + ts->ts_slptime; 1691 if (sum < SCHED_SLP_RUN_MAX) 1692 return; 1693 /* 1694 * This only happens from two places: 1695 * 1) We have added an unusual amount of run time from fork_exit. 1696 * 2) We have added an unusual amount of sleep time from sched_sleep(). 1697 */ 1698 if (sum > SCHED_SLP_RUN_MAX * 2) { 1699 if (ts->ts_runtime > ts->ts_slptime) { 1700 ts->ts_runtime = SCHED_SLP_RUN_MAX; 1701 ts->ts_slptime = 1; 1702 } else { 1703 ts->ts_slptime = SCHED_SLP_RUN_MAX; 1704 ts->ts_runtime = 1; 1705 } 1706 return; 1707 } 1708 /* 1709 * If we have exceeded by more than 1/5th then the algorithm below 1710 * will not bring us back into range. Dividing by two here forces 1711 * us into the range of [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX] 1712 */ 1713 if (sum > (SCHED_SLP_RUN_MAX / 5) * 6) { 1714 ts->ts_runtime /= 2; 1715 ts->ts_slptime /= 2; 1716 return; 1717 } 1718 ts->ts_runtime = (ts->ts_runtime / 5) * 4; 1719 ts->ts_slptime = (ts->ts_slptime / 5) * 4; 1720 } 1721 1722 /* 1723 * Scale back the interactivity history when a child thread is created. The 1724 * history is inherited from the parent but the thread may behave totally 1725 * differently. For example, a shell spawning a compiler process. We want 1726 * to learn that the compiler is behaving badly very quickly. 1727 */ 1728 static void 1729 sched_interact_fork(struct thread *td) 1730 { 1731 struct td_sched *ts; 1732 int ratio; 1733 int sum; 1734 1735 ts = td_get_sched(td); 1736 sum = ts->ts_runtime + ts->ts_slptime; 1737 if (sum > SCHED_SLP_RUN_FORK) { 1738 ratio = sum / SCHED_SLP_RUN_FORK; 1739 ts->ts_runtime /= ratio; 1740 ts->ts_slptime /= ratio; 1741 } 1742 } 1743 1744 /* 1745 * Called from proc0_init() to setup the scheduler fields. 1746 */ 1747 void 1748 schedinit(void) 1749 { 1750 struct td_sched *ts0; 1751 1752 /* 1753 * Set up the scheduler specific parts of thread0. 1754 */ 1755 ts0 = td_get_sched(&thread0); 1756 ts0->ts_ltick = ticks; 1757 ts0->ts_ftick = ticks; 1758 ts0->ts_slice = 0; 1759 ts0->ts_cpu = curcpu; /* set valid CPU number */ 1760 } 1761 1762 /* 1763 * schedinit_ap() is needed prior to calling sched_throw(NULL) to ensure that 1764 * the pcpu requirements are met for any calls in the period between curthread 1765 * initialization and sched_throw(). One can safely add threads to the queue 1766 * before sched_throw(), for instance, as long as the thread lock is setup 1767 * correctly. 1768 * 1769 * TDQ_SELF() relies on the below sched pcpu setting; it may be used only 1770 * after schedinit_ap(). 1771 */ 1772 void 1773 schedinit_ap(void) 1774 { 1775 1776 #ifdef SMP 1777 PCPU_SET(sched, DPCPU_PTR(tdq)); 1778 #endif 1779 PCPU_GET(idlethread)->td_lock = TDQ_LOCKPTR(TDQ_SELF()); 1780 } 1781 1782 /* 1783 * This is only somewhat accurate since given many processes of the same 1784 * priority they will switch when their slices run out, which will be 1785 * at most sched_slice stathz ticks. 1786 */ 1787 int 1788 sched_rr_interval(void) 1789 { 1790 1791 /* Convert sched_slice from stathz to hz. */ 1792 return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz)); 1793 } 1794 1795 /* 1796 * Update the percent cpu tracking information when it is requested or 1797 * the total history exceeds the maximum. We keep a sliding history of 1798 * tick counts that slowly decays. This is less precise than the 4BSD 1799 * mechanism since it happens with less regular and frequent events. 1800 */ 1801 static void 1802 sched_pctcpu_update(struct td_sched *ts, int run) 1803 { 1804 int t = ticks; 1805 1806 /* 1807 * The signed difference may be negative if the thread hasn't run for 1808 * over half of the ticks rollover period. 1809 */ 1810 if ((u_int)(t - ts->ts_ltick) >= SCHED_TICK_TARG) { 1811 ts->ts_ticks = 0; 1812 ts->ts_ftick = t - SCHED_TICK_TARG; 1813 } else if (t - ts->ts_ftick >= SCHED_TICK_MAX) { 1814 ts->ts_ticks = (ts->ts_ticks / (ts->ts_ltick - ts->ts_ftick)) * 1815 (ts->ts_ltick - (t - SCHED_TICK_TARG)); 1816 ts->ts_ftick = t - SCHED_TICK_TARG; 1817 } 1818 if (run) 1819 ts->ts_ticks += (t - ts->ts_ltick) << SCHED_TICK_SHIFT; 1820 ts->ts_ltick = t; 1821 } 1822 1823 /* 1824 * Adjust the priority of a thread. Move it to the appropriate run-queue 1825 * if necessary. This is the back-end for several priority related 1826 * functions. 1827 */ 1828 static void 1829 sched_thread_priority(struct thread *td, u_char prio) 1830 { 1831 struct tdq *tdq; 1832 int oldpri; 1833 1834 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "prio", 1835 "prio:%d", td->td_priority, "new prio:%d", prio, 1836 KTR_ATTR_LINKED, sched_tdname(curthread)); 1837 SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio); 1838 if (td != curthread && prio < td->td_priority) { 1839 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread), 1840 "lend prio", "prio:%d", td->td_priority, "new prio:%d", 1841 prio, KTR_ATTR_LINKED, sched_tdname(td)); 1842 SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio, 1843 curthread); 1844 } 1845 THREAD_LOCK_ASSERT(td, MA_OWNED); 1846 if (td->td_priority == prio) 1847 return; 1848 /* 1849 * If the priority has been elevated due to priority 1850 * propagation, we may have to move ourselves to a new 1851 * queue. This could be optimized to not re-add in some 1852 * cases. 1853 */ 1854 if (TD_ON_RUNQ(td) && prio < td->td_priority) { 1855 sched_rem(td); 1856 td->td_priority = prio; 1857 sched_add(td, SRQ_BORROWING | SRQ_HOLDTD); 1858 return; 1859 } 1860 /* 1861 * If the thread is currently running we may have to adjust the lowpri 1862 * information so other cpus are aware of our current priority. 1863 */ 1864 if (TD_IS_RUNNING(td)) { 1865 tdq = TDQ_CPU(td_get_sched(td)->ts_cpu); 1866 oldpri = td->td_priority; 1867 td->td_priority = prio; 1868 if (prio < tdq->tdq_lowpri) 1869 tdq->tdq_lowpri = prio; 1870 else if (tdq->tdq_lowpri == oldpri) 1871 tdq_setlowpri(tdq, td); 1872 return; 1873 } 1874 td->td_priority = prio; 1875 } 1876 1877 /* 1878 * Update a thread's priority when it is lent another thread's 1879 * priority. 1880 */ 1881 void 1882 sched_lend_prio(struct thread *td, u_char prio) 1883 { 1884 1885 td->td_flags |= TDF_BORROWING; 1886 sched_thread_priority(td, prio); 1887 } 1888 1889 /* 1890 * Restore a thread's priority when priority propagation is 1891 * over. The prio argument is the minimum priority the thread 1892 * needs to have to satisfy other possible priority lending 1893 * requests. If the thread's regular priority is less 1894 * important than prio, the thread will keep a priority boost 1895 * of prio. 1896 */ 1897 void 1898 sched_unlend_prio(struct thread *td, u_char prio) 1899 { 1900 u_char base_pri; 1901 1902 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 1903 td->td_base_pri <= PRI_MAX_TIMESHARE) 1904 base_pri = td->td_user_pri; 1905 else 1906 base_pri = td->td_base_pri; 1907 if (prio >= base_pri) { 1908 td->td_flags &= ~TDF_BORROWING; 1909 sched_thread_priority(td, base_pri); 1910 } else 1911 sched_lend_prio(td, prio); 1912 } 1913 1914 /* 1915 * Standard entry for setting the priority to an absolute value. 1916 */ 1917 void 1918 sched_prio(struct thread *td, u_char prio) 1919 { 1920 u_char oldprio; 1921 1922 /* First, update the base priority. */ 1923 td->td_base_pri = prio; 1924 1925 /* 1926 * If the thread is borrowing another thread's priority, don't 1927 * ever lower the priority. 1928 */ 1929 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 1930 return; 1931 1932 /* Change the real priority. */ 1933 oldprio = td->td_priority; 1934 sched_thread_priority(td, prio); 1935 1936 /* 1937 * If the thread is on a turnstile, then let the turnstile update 1938 * its state. 1939 */ 1940 if (TD_ON_LOCK(td) && oldprio != prio) 1941 turnstile_adjust(td, oldprio); 1942 } 1943 1944 /* 1945 * Set the base user priority, does not effect current running priority. 1946 */ 1947 void 1948 sched_user_prio(struct thread *td, u_char prio) 1949 { 1950 1951 td->td_base_user_pri = prio; 1952 if (td->td_lend_user_pri <= prio) 1953 return; 1954 td->td_user_pri = prio; 1955 } 1956 1957 void 1958 sched_lend_user_prio(struct thread *td, u_char prio) 1959 { 1960 1961 THREAD_LOCK_ASSERT(td, MA_OWNED); 1962 td->td_lend_user_pri = prio; 1963 td->td_user_pri = min(prio, td->td_base_user_pri); 1964 if (td->td_priority > td->td_user_pri) 1965 sched_prio(td, td->td_user_pri); 1966 else if (td->td_priority != td->td_user_pri) 1967 td->td_flags |= TDF_NEEDRESCHED; 1968 } 1969 1970 /* 1971 * Like the above but first check if there is anything to do. 1972 */ 1973 void 1974 sched_lend_user_prio_cond(struct thread *td, u_char prio) 1975 { 1976 1977 if (td->td_lend_user_pri != prio) 1978 goto lend; 1979 if (td->td_user_pri != min(prio, td->td_base_user_pri)) 1980 goto lend; 1981 if (td->td_priority != td->td_user_pri) 1982 goto lend; 1983 return; 1984 1985 lend: 1986 thread_lock(td); 1987 sched_lend_user_prio(td, prio); 1988 thread_unlock(td); 1989 } 1990 1991 #ifdef SMP 1992 /* 1993 * This tdq is about to idle. Try to steal a thread from another CPU before 1994 * choosing the idle thread. 1995 */ 1996 static void 1997 tdq_trysteal(struct tdq *tdq) 1998 { 1999 struct cpu_group *cg, *parent; 2000 struct tdq *steal; 2001 cpuset_t mask; 2002 int cpu, i, goup; 2003 2004 if (smp_started == 0 || steal_idle == 0 || trysteal_limit == 0 || 2005 tdq->tdq_cg == NULL) 2006 return; 2007 CPU_FILL(&mask); 2008 CPU_CLR(PCPU_GET(cpuid), &mask); 2009 /* We don't want to be preempted while we're iterating. */ 2010 spinlock_enter(); 2011 TDQ_UNLOCK(tdq); 2012 for (i = 1, cg = tdq->tdq_cg, goup = 0; ; ) { 2013 cpu = sched_highest(cg, &mask, steal_thresh, 1); 2014 /* 2015 * If a thread was added while interrupts were disabled don't 2016 * steal one here. 2017 */ 2018 if (tdq->tdq_load > 0) { 2019 TDQ_LOCK(tdq); 2020 break; 2021 } 2022 2023 /* 2024 * We found no CPU to steal from in this group. Escalate to 2025 * the parent and repeat. But if parent has only two children 2026 * groups we can avoid searching this group again by searching 2027 * the other one specifically and then escalating two levels. 2028 */ 2029 if (cpu == -1) { 2030 if (goup) { 2031 cg = cg->cg_parent; 2032 goup = 0; 2033 } 2034 if (++i > trysteal_limit) { 2035 TDQ_LOCK(tdq); 2036 break; 2037 } 2038 parent = cg->cg_parent; 2039 if (parent == NULL) { 2040 TDQ_LOCK(tdq); 2041 break; 2042 } 2043 if (parent->cg_children == 2) { 2044 if (cg == &parent->cg_child[0]) 2045 cg = &parent->cg_child[1]; 2046 else 2047 cg = &parent->cg_child[0]; 2048 goup = 1; 2049 } else 2050 cg = parent; 2051 continue; 2052 } 2053 steal = TDQ_CPU(cpu); 2054 /* 2055 * The data returned by sched_highest() is stale and 2056 * the chosen CPU no longer has an eligible thread. 2057 * At this point unconditionally exit the loop to bound 2058 * the time spent in the critcal section. 2059 */ 2060 if (steal->tdq_load < steal_thresh || 2061 steal->tdq_transferable == 0) 2062 continue; 2063 /* 2064 * Try to lock both queues. If we are assigned a thread while 2065 * waited for the lock, switch to it now instead of stealing. 2066 * If we can't get the lock, then somebody likely got there 2067 * first. 2068 */ 2069 TDQ_LOCK(tdq); 2070 if (tdq->tdq_load > 0) 2071 break; 2072 if (TDQ_TRYLOCK_FLAGS(steal, MTX_DUPOK) == 0) 2073 break; 2074 /* 2075 * The data returned by sched_highest() is stale and 2076 * the chosen CPU no longer has an eligible thread. 2077 */ 2078 if (steal->tdq_load < steal_thresh || 2079 steal->tdq_transferable == 0) { 2080 TDQ_UNLOCK(steal); 2081 break; 2082 } 2083 /* 2084 * If we fail to acquire one due to affinity restrictions, 2085 * bail out and let the idle thread to a more complete search 2086 * outside of a critical section. 2087 */ 2088 if (tdq_move(steal, tdq) == -1) { 2089 TDQ_UNLOCK(steal); 2090 break; 2091 } 2092 TDQ_UNLOCK(steal); 2093 break; 2094 } 2095 spinlock_exit(); 2096 } 2097 #endif 2098 2099 /* 2100 * Handle migration from sched_switch(). This happens only for 2101 * cpu binding. 2102 */ 2103 static struct mtx * 2104 sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags) 2105 { 2106 struct tdq *tdn; 2107 int lowpri; 2108 2109 KASSERT(THREAD_CAN_MIGRATE(td) || 2110 (td_get_sched(td)->ts_flags & TSF_BOUND) != 0, 2111 ("Thread %p shouldn't migrate", td)); 2112 KASSERT(!CPU_ABSENT(td_get_sched(td)->ts_cpu), ("sched_switch_migrate: " 2113 "thread %s queued on absent CPU %d.", td->td_name, 2114 td_get_sched(td)->ts_cpu)); 2115 tdn = TDQ_CPU(td_get_sched(td)->ts_cpu); 2116 #ifdef SMP 2117 tdq_load_rem(tdq, td); 2118 /* 2119 * Do the lock dance required to avoid LOR. We have an 2120 * extra spinlock nesting from sched_switch() which will 2121 * prevent preemption while we're holding neither run-queue lock. 2122 */ 2123 TDQ_UNLOCK(tdq); 2124 TDQ_LOCK(tdn); 2125 lowpri = tdq_add(tdn, td, flags); 2126 tdq_notify(tdn, lowpri); 2127 TDQ_UNLOCK(tdn); 2128 TDQ_LOCK(tdq); 2129 #endif 2130 return (TDQ_LOCKPTR(tdn)); 2131 } 2132 2133 /* 2134 * thread_lock_unblock() that does not assume td_lock is blocked. 2135 */ 2136 static inline void 2137 thread_unblock_switch(struct thread *td, struct mtx *mtx) 2138 { 2139 atomic_store_rel_ptr((volatile uintptr_t *)&td->td_lock, 2140 (uintptr_t)mtx); 2141 } 2142 2143 /* 2144 * Switch threads. This function has to handle threads coming in while 2145 * blocked for some reason, running, or idle. It also must deal with 2146 * migrating a thread from one queue to another as running threads may 2147 * be assigned elsewhere via binding. 2148 */ 2149 void 2150 sched_switch(struct thread *td, int flags) 2151 { 2152 struct thread *newtd; 2153 struct tdq *tdq; 2154 struct td_sched *ts; 2155 struct mtx *mtx; 2156 int srqflag; 2157 int cpuid, preempted; 2158 #ifdef SMP 2159 int pickcpu; 2160 #endif 2161 2162 THREAD_LOCK_ASSERT(td, MA_OWNED); 2163 2164 cpuid = PCPU_GET(cpuid); 2165 tdq = TDQ_SELF(); 2166 ts = td_get_sched(td); 2167 sched_pctcpu_update(ts, 1); 2168 #ifdef SMP 2169 pickcpu = (td->td_flags & TDF_PICKCPU) != 0; 2170 if (pickcpu) 2171 ts->ts_rltick = ticks - affinity * MAX_CACHE_LEVELS; 2172 else 2173 ts->ts_rltick = ticks; 2174 #endif 2175 td->td_lastcpu = td->td_oncpu; 2176 preempted = (td->td_flags & TDF_SLICEEND) == 0 && 2177 (flags & SW_PREEMPT) != 0; 2178 td->td_flags &= ~(TDF_NEEDRESCHED | TDF_PICKCPU | TDF_SLICEEND); 2179 td->td_owepreempt = 0; 2180 tdq->tdq_owepreempt = 0; 2181 if (!TD_IS_IDLETHREAD(td)) 2182 tdq->tdq_switchcnt++; 2183 2184 /* 2185 * Always block the thread lock so we can drop the tdq lock early. 2186 */ 2187 mtx = thread_lock_block(td); 2188 spinlock_enter(); 2189 if (TD_IS_IDLETHREAD(td)) { 2190 MPASS(mtx == TDQ_LOCKPTR(tdq)); 2191 TD_SET_CAN_RUN(td); 2192 } else if (TD_IS_RUNNING(td)) { 2193 MPASS(mtx == TDQ_LOCKPTR(tdq)); 2194 srqflag = preempted ? 2195 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 2196 SRQ_OURSELF|SRQ_YIELDING; 2197 #ifdef SMP 2198 if (THREAD_CAN_MIGRATE(td) && (!THREAD_CAN_SCHED(td, ts->ts_cpu) 2199 || pickcpu)) 2200 ts->ts_cpu = sched_pickcpu(td, 0); 2201 #endif 2202 if (ts->ts_cpu == cpuid) 2203 tdq_runq_add(tdq, td, srqflag); 2204 else 2205 mtx = sched_switch_migrate(tdq, td, srqflag); 2206 } else { 2207 /* This thread must be going to sleep. */ 2208 if (mtx != TDQ_LOCKPTR(tdq)) { 2209 mtx_unlock_spin(mtx); 2210 TDQ_LOCK(tdq); 2211 } 2212 tdq_load_rem(tdq, td); 2213 #ifdef SMP 2214 if (tdq->tdq_load == 0) 2215 tdq_trysteal(tdq); 2216 #endif 2217 } 2218 2219 #if (KTR_COMPILE & KTR_SCHED) != 0 2220 if (TD_IS_IDLETHREAD(td)) 2221 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "idle", 2222 "prio:%d", td->td_priority); 2223 else 2224 KTR_STATE3(KTR_SCHED, "thread", sched_tdname(td), KTDSTATE(td), 2225 "prio:%d", td->td_priority, "wmesg:\"%s\"", td->td_wmesg, 2226 "lockname:\"%s\"", td->td_lockname); 2227 #endif 2228 2229 /* 2230 * We enter here with the thread blocked and assigned to the 2231 * appropriate cpu run-queue or sleep-queue and with the current 2232 * thread-queue locked. 2233 */ 2234 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 2235 MPASS(td == tdq->tdq_curthread); 2236 newtd = choosethread(); 2237 sched_pctcpu_update(td_get_sched(newtd), 0); 2238 TDQ_UNLOCK(tdq); 2239 2240 /* 2241 * Call the MD code to switch contexts if necessary. 2242 */ 2243 if (td != newtd) { 2244 #ifdef HWPMC_HOOKS 2245 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 2246 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 2247 #endif 2248 SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc); 2249 2250 #ifdef KDTRACE_HOOKS 2251 /* 2252 * If DTrace has set the active vtime enum to anything 2253 * other than INACTIVE (0), then it should have set the 2254 * function to call. 2255 */ 2256 if (dtrace_vtime_active) 2257 (*dtrace_vtime_switch_func)(newtd); 2258 #endif 2259 td->td_oncpu = NOCPU; 2260 cpu_switch(td, newtd, mtx); 2261 cpuid = td->td_oncpu = PCPU_GET(cpuid); 2262 2263 SDT_PROBE0(sched, , , on__cpu); 2264 #ifdef HWPMC_HOOKS 2265 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 2266 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 2267 #endif 2268 } else { 2269 thread_unblock_switch(td, mtx); 2270 SDT_PROBE0(sched, , , remain__cpu); 2271 } 2272 KASSERT(curthread->td_md.md_spinlock_count == 1, 2273 ("invalid count %d", curthread->td_md.md_spinlock_count)); 2274 2275 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running", 2276 "prio:%d", td->td_priority); 2277 } 2278 2279 /* 2280 * Adjust thread priorities as a result of a nice request. 2281 */ 2282 void 2283 sched_nice(struct proc *p, int nice) 2284 { 2285 struct thread *td; 2286 2287 PROC_LOCK_ASSERT(p, MA_OWNED); 2288 2289 p->p_nice = nice; 2290 FOREACH_THREAD_IN_PROC(p, td) { 2291 thread_lock(td); 2292 sched_priority(td); 2293 sched_prio(td, td->td_base_user_pri); 2294 thread_unlock(td); 2295 } 2296 } 2297 2298 /* 2299 * Record the sleep time for the interactivity scorer. 2300 */ 2301 void 2302 sched_sleep(struct thread *td, int prio) 2303 { 2304 2305 THREAD_LOCK_ASSERT(td, MA_OWNED); 2306 2307 td->td_slptick = ticks; 2308 if (TD_IS_SUSPENDED(td) || prio >= PSOCK) 2309 td->td_flags |= TDF_CANSWAP; 2310 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 2311 return; 2312 if (static_boost == 1 && prio) 2313 sched_prio(td, prio); 2314 else if (static_boost && td->td_priority > static_boost) 2315 sched_prio(td, static_boost); 2316 } 2317 2318 /* 2319 * Schedule a thread to resume execution and record how long it voluntarily 2320 * slept. We also update the pctcpu, interactivity, and priority. 2321 * 2322 * Requires the thread lock on entry, drops on exit. 2323 */ 2324 void 2325 sched_wakeup(struct thread *td, int srqflags) 2326 { 2327 struct td_sched *ts; 2328 int slptick; 2329 2330 THREAD_LOCK_ASSERT(td, MA_OWNED); 2331 ts = td_get_sched(td); 2332 td->td_flags &= ~TDF_CANSWAP; 2333 2334 /* 2335 * If we slept for more than a tick update our interactivity and 2336 * priority. 2337 */ 2338 slptick = td->td_slptick; 2339 td->td_slptick = 0; 2340 if (slptick && slptick != ticks) { 2341 ts->ts_slptime += (ticks - slptick) << SCHED_TICK_SHIFT; 2342 sched_interact_update(td); 2343 sched_pctcpu_update(ts, 0); 2344 } 2345 /* 2346 * Reset the slice value since we slept and advanced the round-robin. 2347 */ 2348 ts->ts_slice = 0; 2349 sched_add(td, SRQ_BORING | srqflags); 2350 } 2351 2352 /* 2353 * Penalize the parent for creating a new child and initialize the child's 2354 * priority. 2355 */ 2356 void 2357 sched_fork(struct thread *td, struct thread *child) 2358 { 2359 THREAD_LOCK_ASSERT(td, MA_OWNED); 2360 sched_pctcpu_update(td_get_sched(td), 1); 2361 sched_fork_thread(td, child); 2362 /* 2363 * Penalize the parent and child for forking. 2364 */ 2365 sched_interact_fork(child); 2366 sched_priority(child); 2367 td_get_sched(td)->ts_runtime += tickincr; 2368 sched_interact_update(td); 2369 sched_priority(td); 2370 } 2371 2372 /* 2373 * Fork a new thread, may be within the same process. 2374 */ 2375 void 2376 sched_fork_thread(struct thread *td, struct thread *child) 2377 { 2378 struct td_sched *ts; 2379 struct td_sched *ts2; 2380 struct tdq *tdq; 2381 2382 tdq = TDQ_SELF(); 2383 THREAD_LOCK_ASSERT(td, MA_OWNED); 2384 /* 2385 * Initialize child. 2386 */ 2387 ts = td_get_sched(td); 2388 ts2 = td_get_sched(child); 2389 child->td_oncpu = NOCPU; 2390 child->td_lastcpu = NOCPU; 2391 child->td_lock = TDQ_LOCKPTR(tdq); 2392 child->td_cpuset = cpuset_ref(td->td_cpuset); 2393 child->td_domain.dr_policy = td->td_cpuset->cs_domain; 2394 ts2->ts_cpu = ts->ts_cpu; 2395 ts2->ts_flags = 0; 2396 /* 2397 * Grab our parents cpu estimation information. 2398 */ 2399 ts2->ts_ticks = ts->ts_ticks; 2400 ts2->ts_ltick = ts->ts_ltick; 2401 ts2->ts_ftick = ts->ts_ftick; 2402 /* 2403 * Do not inherit any borrowed priority from the parent. 2404 */ 2405 child->td_priority = child->td_base_pri; 2406 /* 2407 * And update interactivity score. 2408 */ 2409 ts2->ts_slptime = ts->ts_slptime; 2410 ts2->ts_runtime = ts->ts_runtime; 2411 /* Attempt to quickly learn interactivity. */ 2412 ts2->ts_slice = tdq_slice(tdq) - sched_slice_min; 2413 #ifdef KTR 2414 bzero(ts2->ts_name, sizeof(ts2->ts_name)); 2415 #endif 2416 } 2417 2418 /* 2419 * Adjust the priority class of a thread. 2420 */ 2421 void 2422 sched_class(struct thread *td, int class) 2423 { 2424 2425 THREAD_LOCK_ASSERT(td, MA_OWNED); 2426 if (td->td_pri_class == class) 2427 return; 2428 td->td_pri_class = class; 2429 } 2430 2431 /* 2432 * Return some of the child's priority and interactivity to the parent. 2433 */ 2434 void 2435 sched_exit(struct proc *p, struct thread *child) 2436 { 2437 struct thread *td; 2438 2439 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "proc exit", 2440 "prio:%d", child->td_priority); 2441 PROC_LOCK_ASSERT(p, MA_OWNED); 2442 td = FIRST_THREAD_IN_PROC(p); 2443 sched_exit_thread(td, child); 2444 } 2445 2446 /* 2447 * Penalize another thread for the time spent on this one. This helps to 2448 * worsen the priority and interactivity of processes which schedule batch 2449 * jobs such as make. This has little effect on the make process itself but 2450 * causes new processes spawned by it to receive worse scores immediately. 2451 */ 2452 void 2453 sched_exit_thread(struct thread *td, struct thread *child) 2454 { 2455 2456 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "thread exit", 2457 "prio:%d", child->td_priority); 2458 /* 2459 * Give the child's runtime to the parent without returning the 2460 * sleep time as a penalty to the parent. This causes shells that 2461 * launch expensive things to mark their children as expensive. 2462 */ 2463 thread_lock(td); 2464 td_get_sched(td)->ts_runtime += td_get_sched(child)->ts_runtime; 2465 sched_interact_update(td); 2466 sched_priority(td); 2467 thread_unlock(td); 2468 } 2469 2470 void 2471 sched_preempt(struct thread *td) 2472 { 2473 struct tdq *tdq; 2474 int flags; 2475 2476 SDT_PROBE2(sched, , , surrender, td, td->td_proc); 2477 2478 thread_lock(td); 2479 tdq = TDQ_SELF(); 2480 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2481 if (td->td_priority > tdq->tdq_lowpri) { 2482 if (td->td_critnest == 1) { 2483 flags = SW_INVOL | SW_PREEMPT; 2484 flags |= TD_IS_IDLETHREAD(td) ? SWT_REMOTEWAKEIDLE : 2485 SWT_REMOTEPREEMPT; 2486 mi_switch(flags); 2487 /* Switch dropped thread lock. */ 2488 return; 2489 } 2490 td->td_owepreempt = 1; 2491 } else { 2492 tdq->tdq_owepreempt = 0; 2493 } 2494 thread_unlock(td); 2495 } 2496 2497 /* 2498 * Fix priorities on return to user-space. Priorities may be elevated due 2499 * to static priorities in msleep() or similar. 2500 */ 2501 void 2502 sched_userret_slowpath(struct thread *td) 2503 { 2504 2505 thread_lock(td); 2506 td->td_priority = td->td_user_pri; 2507 td->td_base_pri = td->td_user_pri; 2508 tdq_setlowpri(TDQ_SELF(), td); 2509 thread_unlock(td); 2510 } 2511 2512 /* 2513 * Handle a stathz tick. This is really only relevant for timeshare 2514 * threads. 2515 */ 2516 void 2517 sched_clock(struct thread *td, int cnt) 2518 { 2519 struct tdq *tdq; 2520 struct td_sched *ts; 2521 2522 THREAD_LOCK_ASSERT(td, MA_OWNED); 2523 tdq = TDQ_SELF(); 2524 #ifdef SMP 2525 /* 2526 * We run the long term load balancer infrequently on the first cpu. 2527 */ 2528 if (balance_tdq == tdq && smp_started != 0 && rebalance != 0 && 2529 balance_ticks != 0) { 2530 balance_ticks -= cnt; 2531 if (balance_ticks <= 0) 2532 sched_balance(); 2533 } 2534 #endif 2535 /* 2536 * Save the old switch count so we have a record of the last ticks 2537 * activity. Initialize the new switch count based on our load. 2538 * If there is some activity seed it to reflect that. 2539 */ 2540 tdq->tdq_oldswitchcnt = tdq->tdq_switchcnt; 2541 tdq->tdq_switchcnt = tdq->tdq_load; 2542 /* 2543 * Advance the insert index once for each tick to ensure that all 2544 * threads get a chance to run. 2545 */ 2546 if (tdq->tdq_idx == tdq->tdq_ridx) { 2547 tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS; 2548 if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx])) 2549 tdq->tdq_ridx = tdq->tdq_idx; 2550 } 2551 ts = td_get_sched(td); 2552 sched_pctcpu_update(ts, 1); 2553 if ((td->td_pri_class & PRI_FIFO_BIT) || TD_IS_IDLETHREAD(td)) 2554 return; 2555 2556 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) { 2557 /* 2558 * We used a tick; charge it to the thread so 2559 * that we can compute our interactivity. 2560 */ 2561 td_get_sched(td)->ts_runtime += tickincr * cnt; 2562 sched_interact_update(td); 2563 sched_priority(td); 2564 } 2565 2566 /* 2567 * Force a context switch if the current thread has used up a full 2568 * time slice (default is 100ms). 2569 */ 2570 ts->ts_slice += cnt; 2571 if (ts->ts_slice >= tdq_slice(tdq)) { 2572 ts->ts_slice = 0; 2573 td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND; 2574 } 2575 } 2576 2577 u_int 2578 sched_estcpu(struct thread *td __unused) 2579 { 2580 2581 return (0); 2582 } 2583 2584 /* 2585 * Return whether the current CPU has runnable tasks. Used for in-kernel 2586 * cooperative idle threads. 2587 */ 2588 int 2589 sched_runnable(void) 2590 { 2591 struct tdq *tdq; 2592 int load; 2593 2594 load = 1; 2595 2596 tdq = TDQ_SELF(); 2597 if ((curthread->td_flags & TDF_IDLETD) != 0) { 2598 if (tdq->tdq_load > 0) 2599 goto out; 2600 } else 2601 if (tdq->tdq_load - 1 > 0) 2602 goto out; 2603 load = 0; 2604 out: 2605 return (load); 2606 } 2607 2608 /* 2609 * Choose the highest priority thread to run. The thread is removed from 2610 * the run-queue while running however the load remains. 2611 */ 2612 struct thread * 2613 sched_choose(void) 2614 { 2615 struct thread *td; 2616 struct tdq *tdq; 2617 2618 tdq = TDQ_SELF(); 2619 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2620 td = tdq_choose(tdq); 2621 if (td != NULL) { 2622 tdq_runq_rem(tdq, td); 2623 tdq->tdq_lowpri = td->td_priority; 2624 } else { 2625 tdq->tdq_lowpri = PRI_MAX_IDLE; 2626 td = PCPU_GET(idlethread); 2627 } 2628 tdq->tdq_curthread = td; 2629 return (td); 2630 } 2631 2632 /* 2633 * Set owepreempt if necessary. Preemption never happens directly in ULE, 2634 * we always request it once we exit a critical section. 2635 */ 2636 static inline void 2637 sched_setpreempt(struct thread *td) 2638 { 2639 struct thread *ctd; 2640 int cpri; 2641 int pri; 2642 2643 THREAD_LOCK_ASSERT(curthread, MA_OWNED); 2644 2645 ctd = curthread; 2646 pri = td->td_priority; 2647 cpri = ctd->td_priority; 2648 if (pri < cpri) 2649 ctd->td_flags |= TDF_NEEDRESCHED; 2650 if (KERNEL_PANICKED() || pri >= cpri || cold || TD_IS_INHIBITED(ctd)) 2651 return; 2652 if (!sched_shouldpreempt(pri, cpri, 0)) 2653 return; 2654 ctd->td_owepreempt = 1; 2655 } 2656 2657 /* 2658 * Add a thread to a thread queue. Select the appropriate runq and add the 2659 * thread to it. This is the internal function called when the tdq is 2660 * predetermined. 2661 */ 2662 static int 2663 tdq_add(struct tdq *tdq, struct thread *td, int flags) 2664 { 2665 int lowpri; 2666 2667 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2668 THREAD_LOCK_BLOCKED_ASSERT(td, MA_OWNED); 2669 KASSERT((td->td_inhibitors == 0), 2670 ("sched_add: trying to run inhibited thread")); 2671 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 2672 ("sched_add: bad thread state")); 2673 KASSERT(td->td_flags & TDF_INMEM, 2674 ("sched_add: thread swapped out")); 2675 2676 lowpri = tdq->tdq_lowpri; 2677 if (td->td_priority < lowpri) 2678 tdq->tdq_lowpri = td->td_priority; 2679 tdq_runq_add(tdq, td, flags); 2680 tdq_load_add(tdq, td); 2681 return (lowpri); 2682 } 2683 2684 /* 2685 * Select the target thread queue and add a thread to it. Request 2686 * preemption or IPI a remote processor if required. 2687 * 2688 * Requires the thread lock on entry, drops on exit. 2689 */ 2690 void 2691 sched_add(struct thread *td, int flags) 2692 { 2693 struct tdq *tdq; 2694 #ifdef SMP 2695 int cpu, lowpri; 2696 #endif 2697 2698 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 2699 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 2700 sched_tdname(curthread)); 2701 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 2702 KTR_ATTR_LINKED, sched_tdname(td)); 2703 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 2704 flags & SRQ_PREEMPTED); 2705 THREAD_LOCK_ASSERT(td, MA_OWNED); 2706 /* 2707 * Recalculate the priority before we select the target cpu or 2708 * run-queue. 2709 */ 2710 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 2711 sched_priority(td); 2712 #ifdef SMP 2713 /* 2714 * Pick the destination cpu and if it isn't ours transfer to the 2715 * target cpu. 2716 */ 2717 cpu = sched_pickcpu(td, flags); 2718 tdq = sched_setcpu(td, cpu, flags); 2719 lowpri = tdq_add(tdq, td, flags); 2720 if (cpu != PCPU_GET(cpuid)) 2721 tdq_notify(tdq, lowpri); 2722 else if (!(flags & SRQ_YIELDING)) 2723 sched_setpreempt(td); 2724 #else 2725 tdq = TDQ_SELF(); 2726 /* 2727 * Now that the thread is moving to the run-queue, set the lock 2728 * to the scheduler's lock. 2729 */ 2730 if (td->td_lock != TDQ_LOCKPTR(tdq)) { 2731 TDQ_LOCK(tdq); 2732 if ((flags & SRQ_HOLD) != 0) 2733 td->td_lock = TDQ_LOCKPTR(tdq); 2734 else 2735 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 2736 } 2737 (void)tdq_add(tdq, td, flags); 2738 if (!(flags & SRQ_YIELDING)) 2739 sched_setpreempt(td); 2740 #endif 2741 if (!(flags & SRQ_HOLDTD)) 2742 thread_unlock(td); 2743 } 2744 2745 /* 2746 * Remove a thread from a run-queue without running it. This is used 2747 * when we're stealing a thread from a remote queue. Otherwise all threads 2748 * exit by calling sched_exit_thread() and sched_throw() themselves. 2749 */ 2750 void 2751 sched_rem(struct thread *td) 2752 { 2753 struct tdq *tdq; 2754 2755 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "runq rem", 2756 "prio:%d", td->td_priority); 2757 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL); 2758 tdq = TDQ_CPU(td_get_sched(td)->ts_cpu); 2759 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2760 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2761 KASSERT(TD_ON_RUNQ(td), 2762 ("sched_rem: thread not on run queue")); 2763 tdq_runq_rem(tdq, td); 2764 tdq_load_rem(tdq, td); 2765 TD_SET_CAN_RUN(td); 2766 if (td->td_priority == tdq->tdq_lowpri) 2767 tdq_setlowpri(tdq, NULL); 2768 } 2769 2770 /* 2771 * Fetch cpu utilization information. Updates on demand. 2772 */ 2773 fixpt_t 2774 sched_pctcpu(struct thread *td) 2775 { 2776 fixpt_t pctcpu; 2777 struct td_sched *ts; 2778 2779 pctcpu = 0; 2780 ts = td_get_sched(td); 2781 2782 THREAD_LOCK_ASSERT(td, MA_OWNED); 2783 sched_pctcpu_update(ts, TD_IS_RUNNING(td)); 2784 if (ts->ts_ticks) { 2785 int rtick; 2786 2787 /* How many rtick per second ? */ 2788 rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz); 2789 pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT; 2790 } 2791 2792 return (pctcpu); 2793 } 2794 2795 /* 2796 * Enforce affinity settings for a thread. Called after adjustments to 2797 * cpumask. 2798 */ 2799 void 2800 sched_affinity(struct thread *td) 2801 { 2802 #ifdef SMP 2803 struct td_sched *ts; 2804 2805 THREAD_LOCK_ASSERT(td, MA_OWNED); 2806 ts = td_get_sched(td); 2807 if (THREAD_CAN_SCHED(td, ts->ts_cpu)) 2808 return; 2809 if (TD_ON_RUNQ(td)) { 2810 sched_rem(td); 2811 sched_add(td, SRQ_BORING | SRQ_HOLDTD); 2812 return; 2813 } 2814 if (!TD_IS_RUNNING(td)) 2815 return; 2816 /* 2817 * Force a switch before returning to userspace. If the 2818 * target thread is not running locally send an ipi to force 2819 * the issue. 2820 */ 2821 td->td_flags |= TDF_NEEDRESCHED; 2822 if (td != curthread) 2823 ipi_cpu(ts->ts_cpu, IPI_PREEMPT); 2824 #endif 2825 } 2826 2827 /* 2828 * Bind a thread to a target cpu. 2829 */ 2830 void 2831 sched_bind(struct thread *td, int cpu) 2832 { 2833 struct td_sched *ts; 2834 2835 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 2836 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 2837 ts = td_get_sched(td); 2838 if (ts->ts_flags & TSF_BOUND) 2839 sched_unbind(td); 2840 KASSERT(THREAD_CAN_MIGRATE(td), ("%p must be migratable", td)); 2841 ts->ts_flags |= TSF_BOUND; 2842 sched_pin(); 2843 if (PCPU_GET(cpuid) == cpu) 2844 return; 2845 ts->ts_cpu = cpu; 2846 /* When we return from mi_switch we'll be on the correct cpu. */ 2847 mi_switch(SW_VOL); 2848 thread_lock(td); 2849 } 2850 2851 /* 2852 * Release a bound thread. 2853 */ 2854 void 2855 sched_unbind(struct thread *td) 2856 { 2857 struct td_sched *ts; 2858 2859 THREAD_LOCK_ASSERT(td, MA_OWNED); 2860 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 2861 ts = td_get_sched(td); 2862 if ((ts->ts_flags & TSF_BOUND) == 0) 2863 return; 2864 ts->ts_flags &= ~TSF_BOUND; 2865 sched_unpin(); 2866 } 2867 2868 int 2869 sched_is_bound(struct thread *td) 2870 { 2871 THREAD_LOCK_ASSERT(td, MA_OWNED); 2872 return (td_get_sched(td)->ts_flags & TSF_BOUND); 2873 } 2874 2875 /* 2876 * Basic yield call. 2877 */ 2878 void 2879 sched_relinquish(struct thread *td) 2880 { 2881 thread_lock(td); 2882 mi_switch(SW_VOL | SWT_RELINQUISH); 2883 } 2884 2885 /* 2886 * Return the total system load. 2887 */ 2888 int 2889 sched_load(void) 2890 { 2891 #ifdef SMP 2892 int total; 2893 int i; 2894 2895 total = 0; 2896 CPU_FOREACH(i) 2897 total += TDQ_CPU(i)->tdq_sysload; 2898 return (total); 2899 #else 2900 return (TDQ_SELF()->tdq_sysload); 2901 #endif 2902 } 2903 2904 int 2905 sched_sizeof_proc(void) 2906 { 2907 return (sizeof(struct proc)); 2908 } 2909 2910 int 2911 sched_sizeof_thread(void) 2912 { 2913 return (sizeof(struct thread) + sizeof(struct td_sched)); 2914 } 2915 2916 #ifdef SMP 2917 #define TDQ_IDLESPIN(tdq) \ 2918 ((tdq)->tdq_cg != NULL && ((tdq)->tdq_cg->cg_flags & CG_FLAG_THREAD) == 0) 2919 #else 2920 #define TDQ_IDLESPIN(tdq) 1 2921 #endif 2922 2923 /* 2924 * The actual idle process. 2925 */ 2926 void 2927 sched_idletd(void *dummy) 2928 { 2929 struct thread *td; 2930 struct tdq *tdq; 2931 int oldswitchcnt, switchcnt; 2932 int i; 2933 2934 mtx_assert(&Giant, MA_NOTOWNED); 2935 td = curthread; 2936 tdq = TDQ_SELF(); 2937 THREAD_NO_SLEEPING(); 2938 oldswitchcnt = -1; 2939 for (;;) { 2940 if (tdq->tdq_load) { 2941 thread_lock(td); 2942 mi_switch(SW_VOL | SWT_IDLE); 2943 } 2944 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2945 #ifdef SMP 2946 if (always_steal || switchcnt != oldswitchcnt) { 2947 oldswitchcnt = switchcnt; 2948 if (tdq_idled(tdq) == 0) 2949 continue; 2950 } 2951 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2952 #else 2953 oldswitchcnt = switchcnt; 2954 #endif 2955 /* 2956 * If we're switching very frequently, spin while checking 2957 * for load rather than entering a low power state that 2958 * may require an IPI. However, don't do any busy 2959 * loops while on SMT machines as this simply steals 2960 * cycles from cores doing useful work. 2961 */ 2962 if (TDQ_IDLESPIN(tdq) && switchcnt > sched_idlespinthresh) { 2963 for (i = 0; i < sched_idlespins; i++) { 2964 if (tdq->tdq_load) 2965 break; 2966 cpu_spinwait(); 2967 } 2968 } 2969 2970 /* If there was context switch during spin, restart it. */ 2971 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2972 if (tdq->tdq_load != 0 || switchcnt != oldswitchcnt) 2973 continue; 2974 2975 /* Run main MD idle handler. */ 2976 tdq->tdq_cpu_idle = 1; 2977 /* 2978 * Make sure that the tdq_cpu_idle update is globally visible 2979 * before cpu_idle() reads tdq_load. The order is important 2980 * to avoid races with tdq_notify(). 2981 */ 2982 atomic_thread_fence_seq_cst(); 2983 /* 2984 * Checking for again after the fence picks up assigned 2985 * threads often enough to make it worthwhile to do so in 2986 * order to avoid calling cpu_idle(). 2987 */ 2988 if (tdq->tdq_load != 0) { 2989 tdq->tdq_cpu_idle = 0; 2990 continue; 2991 } 2992 cpu_idle(switchcnt * 4 > sched_idlespinthresh); 2993 tdq->tdq_cpu_idle = 0; 2994 2995 /* 2996 * Account thread-less hardware interrupts and 2997 * other wakeup reasons equal to context switches. 2998 */ 2999 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 3000 if (switchcnt != oldswitchcnt) 3001 continue; 3002 tdq->tdq_switchcnt++; 3003 oldswitchcnt++; 3004 } 3005 } 3006 3007 /* 3008 * sched_throw_grab() chooses a thread from the queue to switch to 3009 * next. It returns with the tdq lock dropped in a spinlock section to 3010 * keep interrupts disabled until the CPU is running in a proper threaded 3011 * context. 3012 */ 3013 static struct thread * 3014 sched_throw_grab(struct tdq *tdq) 3015 { 3016 struct thread *newtd; 3017 3018 newtd = choosethread(); 3019 spinlock_enter(); 3020 TDQ_UNLOCK(tdq); 3021 KASSERT(curthread->td_md.md_spinlock_count == 1, 3022 ("invalid count %d", curthread->td_md.md_spinlock_count)); 3023 return (newtd); 3024 } 3025 3026 /* 3027 * A CPU is entering for the first time. 3028 */ 3029 void 3030 sched_ap_entry(void) 3031 { 3032 struct thread *newtd; 3033 struct tdq *tdq; 3034 3035 tdq = TDQ_SELF(); 3036 3037 /* This should have been setup in schedinit_ap(). */ 3038 THREAD_LOCKPTR_ASSERT(curthread, TDQ_LOCKPTR(tdq)); 3039 3040 TDQ_LOCK(tdq); 3041 /* Correct spinlock nesting. */ 3042 spinlock_exit(); 3043 PCPU_SET(switchtime, cpu_ticks()); 3044 PCPU_SET(switchticks, ticks); 3045 3046 newtd = sched_throw_grab(tdq); 3047 3048 /* doesn't return */ 3049 cpu_throw(NULL, newtd); 3050 } 3051 3052 /* 3053 * A thread is exiting. 3054 */ 3055 void 3056 sched_throw(struct thread *td) 3057 { 3058 struct thread *newtd; 3059 struct tdq *tdq; 3060 3061 tdq = TDQ_SELF(); 3062 3063 MPASS(td != NULL); 3064 THREAD_LOCK_ASSERT(td, MA_OWNED); 3065 THREAD_LOCKPTR_ASSERT(td, TDQ_LOCKPTR(tdq)); 3066 3067 tdq_load_rem(tdq, td); 3068 td->td_lastcpu = td->td_oncpu; 3069 td->td_oncpu = NOCPU; 3070 thread_lock_block(td); 3071 3072 newtd = sched_throw_grab(tdq); 3073 3074 /* doesn't return */ 3075 cpu_switch(td, newtd, TDQ_LOCKPTR(tdq)); 3076 } 3077 3078 /* 3079 * This is called from fork_exit(). Just acquire the correct locks and 3080 * let fork do the rest of the work. 3081 */ 3082 void 3083 sched_fork_exit(struct thread *td) 3084 { 3085 struct tdq *tdq; 3086 int cpuid; 3087 3088 /* 3089 * Finish setting up thread glue so that it begins execution in a 3090 * non-nested critical section with the scheduler lock held. 3091 */ 3092 KASSERT(curthread->td_md.md_spinlock_count == 1, 3093 ("invalid count %d", curthread->td_md.md_spinlock_count)); 3094 cpuid = PCPU_GET(cpuid); 3095 tdq = TDQ_SELF(); 3096 TDQ_LOCK(tdq); 3097 spinlock_exit(); 3098 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 3099 td->td_oncpu = cpuid; 3100 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running", 3101 "prio:%d", td->td_priority); 3102 SDT_PROBE0(sched, , , on__cpu); 3103 } 3104 3105 /* 3106 * Create on first use to catch odd startup conditions. 3107 */ 3108 char * 3109 sched_tdname(struct thread *td) 3110 { 3111 #ifdef KTR 3112 struct td_sched *ts; 3113 3114 ts = td_get_sched(td); 3115 if (ts->ts_name[0] == '\0') 3116 snprintf(ts->ts_name, sizeof(ts->ts_name), 3117 "%s tid %d", td->td_name, td->td_tid); 3118 return (ts->ts_name); 3119 #else 3120 return (td->td_name); 3121 #endif 3122 } 3123 3124 #ifdef KTR 3125 void 3126 sched_clear_tdname(struct thread *td) 3127 { 3128 struct td_sched *ts; 3129 3130 ts = td_get_sched(td); 3131 ts->ts_name[0] = '\0'; 3132 } 3133 #endif 3134 3135 #ifdef SMP 3136 3137 /* 3138 * Build the CPU topology dump string. Is recursively called to collect 3139 * the topology tree. 3140 */ 3141 static int 3142 sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, struct cpu_group *cg, 3143 int indent) 3144 { 3145 char cpusetbuf[CPUSETBUFSIZ]; 3146 int i, first; 3147 3148 sbuf_printf(sb, "%*s<group level=\"%d\" cache-level=\"%d\">\n", indent, 3149 "", 1 + indent / 2, cg->cg_level); 3150 sbuf_printf(sb, "%*s <cpu count=\"%d\" mask=\"%s\">", indent, "", 3151 cg->cg_count, cpusetobj_strprint(cpusetbuf, &cg->cg_mask)); 3152 first = TRUE; 3153 for (i = cg->cg_first; i <= cg->cg_last; i++) { 3154 if (CPU_ISSET(i, &cg->cg_mask)) { 3155 if (!first) 3156 sbuf_printf(sb, ", "); 3157 else 3158 first = FALSE; 3159 sbuf_printf(sb, "%d", i); 3160 } 3161 } 3162 sbuf_printf(sb, "</cpu>\n"); 3163 3164 if (cg->cg_flags != 0) { 3165 sbuf_printf(sb, "%*s <flags>", indent, ""); 3166 if ((cg->cg_flags & CG_FLAG_HTT) != 0) 3167 sbuf_printf(sb, "<flag name=\"HTT\">HTT group</flag>"); 3168 if ((cg->cg_flags & CG_FLAG_THREAD) != 0) 3169 sbuf_printf(sb, "<flag name=\"THREAD\">THREAD group</flag>"); 3170 if ((cg->cg_flags & CG_FLAG_SMT) != 0) 3171 sbuf_printf(sb, "<flag name=\"SMT\">SMT group</flag>"); 3172 if ((cg->cg_flags & CG_FLAG_NODE) != 0) 3173 sbuf_printf(sb, "<flag name=\"NODE\">NUMA node</flag>"); 3174 sbuf_printf(sb, "</flags>\n"); 3175 } 3176 3177 if (cg->cg_children > 0) { 3178 sbuf_printf(sb, "%*s <children>\n", indent, ""); 3179 for (i = 0; i < cg->cg_children; i++) 3180 sysctl_kern_sched_topology_spec_internal(sb, 3181 &cg->cg_child[i], indent+2); 3182 sbuf_printf(sb, "%*s </children>\n", indent, ""); 3183 } 3184 sbuf_printf(sb, "%*s</group>\n", indent, ""); 3185 return (0); 3186 } 3187 3188 /* 3189 * Sysctl handler for retrieving topology dump. It's a wrapper for 3190 * the recursive sysctl_kern_smp_topology_spec_internal(). 3191 */ 3192 static int 3193 sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS) 3194 { 3195 struct sbuf *topo; 3196 int err; 3197 3198 KASSERT(cpu_top != NULL, ("cpu_top isn't initialized")); 3199 3200 topo = sbuf_new_for_sysctl(NULL, NULL, 512, req); 3201 if (topo == NULL) 3202 return (ENOMEM); 3203 3204 sbuf_printf(topo, "<groups>\n"); 3205 err = sysctl_kern_sched_topology_spec_internal(topo, cpu_top, 1); 3206 sbuf_printf(topo, "</groups>\n"); 3207 3208 if (err == 0) { 3209 err = sbuf_finish(topo); 3210 } 3211 sbuf_delete(topo); 3212 return (err); 3213 } 3214 3215 #endif 3216 3217 static int 3218 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 3219 { 3220 int error, new_val, period; 3221 3222 period = 1000000 / realstathz; 3223 new_val = period * sched_slice; 3224 error = sysctl_handle_int(oidp, &new_val, 0, req); 3225 if (error != 0 || req->newptr == NULL) 3226 return (error); 3227 if (new_val <= 0) 3228 return (EINVAL); 3229 sched_slice = imax(1, (new_val + period / 2) / period); 3230 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 3231 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 3232 realstathz); 3233 return (0); 3234 } 3235 3236 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 3237 "Scheduler"); 3238 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0, 3239 "Scheduler name"); 3240 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, 3241 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 0, 3242 sysctl_kern_quantum, "I", 3243 "Quantum for timeshare threads in microseconds"); 3244 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, 3245 "Quantum for timeshare threads in stathz ticks"); 3246 SYSCTL_UINT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0, 3247 "Interactivity score threshold"); 3248 SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW, 3249 &preempt_thresh, 0, 3250 "Maximal (lowest) priority for preemption"); 3251 SYSCTL_INT(_kern_sched, OID_AUTO, static_boost, CTLFLAG_RW, &static_boost, 0, 3252 "Assign static kernel priorities to sleeping threads"); 3253 SYSCTL_INT(_kern_sched, OID_AUTO, idlespins, CTLFLAG_RW, &sched_idlespins, 0, 3254 "Number of times idle thread will spin waiting for new work"); 3255 SYSCTL_INT(_kern_sched, OID_AUTO, idlespinthresh, CTLFLAG_RW, 3256 &sched_idlespinthresh, 0, 3257 "Threshold before we will permit idle thread spinning"); 3258 #ifdef SMP 3259 SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0, 3260 "Number of hz ticks to keep thread affinity for"); 3261 SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0, 3262 "Enables the long-term load balancer"); 3263 SYSCTL_INT(_kern_sched, OID_AUTO, balance_interval, CTLFLAG_RW, 3264 &balance_interval, 0, 3265 "Average period in stathz ticks to run the long-term balancer"); 3266 SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0, 3267 "Attempts to steal work from other cores before idling"); 3268 SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0, 3269 "Minimum load on remote CPU before we'll steal"); 3270 SYSCTL_INT(_kern_sched, OID_AUTO, trysteal_limit, CTLFLAG_RW, &trysteal_limit, 3271 0, "Topological distance limit for stealing threads in sched_switch()"); 3272 SYSCTL_INT(_kern_sched, OID_AUTO, always_steal, CTLFLAG_RW, &always_steal, 0, 3273 "Always run the stealer from the idle thread"); 3274 SYSCTL_PROC(_kern_sched, OID_AUTO, topology_spec, CTLTYPE_STRING | 3275 CTLFLAG_MPSAFE | CTLFLAG_RD, NULL, 0, sysctl_kern_sched_topology_spec, "A", 3276 "XML dump of detected CPU topology"); 3277 #endif 3278 3279 /* ps compat. All cpu percentages from ULE are weighted. */ 3280 static int ccpu = 0; 3281 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, 3282 "Decay factor used for updating %CPU in 4BSD scheduler"); 3283