1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 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 #include "opt_hwpmc_hooks.h" 42 #include "opt_sched.h" 43 44 #include <sys/param.h> 45 #include <sys/systm.h> 46 #include <sys/kdb.h> 47 #include <sys/kernel.h> 48 #include <sys/ktr.h> 49 #include <sys/limits.h> 50 #include <sys/lock.h> 51 #include <sys/mutex.h> 52 #include <sys/proc.h> 53 #include <sys/resource.h> 54 #include <sys/resourcevar.h> 55 #include <sys/sched.h> 56 #include <sys/sdt.h> 57 #include <sys/smp.h> 58 #include <sys/sx.h> 59 #include <sys/sysctl.h> 60 #include <sys/sysproto.h> 61 #include <sys/turnstile.h> 62 #include <sys/umtxvar.h> 63 #include <sys/vmmeter.h> 64 #include <sys/cpuset.h> 65 #include <sys/sbuf.h> 66 67 #ifdef HWPMC_HOOKS 68 #include <sys/pmckern.h> 69 #endif 70 71 #ifdef KDTRACE_HOOKS 72 #include <sys/dtrace_bsd.h> 73 int __read_mostly dtrace_vtime_active; 74 dtrace_vtime_switch_func_t dtrace_vtime_switch_func; 75 #endif 76 77 #include <machine/cpu.h> 78 #include <machine/smp.h> 79 80 #define KTR_ULE 0 81 82 #define TS_NAME_LEN (MAXCOMLEN + sizeof(" td ") + sizeof(__XSTRING(UINT_MAX))) 83 #define TDQ_NAME_LEN (sizeof("sched lock ") + sizeof(__XSTRING(MAXCPU))) 84 #define TDQ_LOADNAME_LEN (sizeof("CPU ") + sizeof(__XSTRING(MAXCPU)) - 1 + sizeof(" load")) 85 86 /* 87 * Thread scheduler specific section. All fields are protected 88 * by the thread lock. 89 */ 90 struct td_sched { 91 struct runq *ts_runq; /* Run-queue we're queued on. */ 92 short ts_flags; /* TSF_* flags. */ 93 int ts_cpu; /* CPU that we have affinity for. */ 94 int ts_rltick; /* Real last tick, for affinity. */ 95 int ts_slice; /* Ticks of slice remaining. */ 96 u_int ts_slptime; /* Number of ticks we vol. slept */ 97 u_int ts_runtime; /* Number of ticks we were running */ 98 int ts_ltick; /* Last tick that we were running on */ 99 int ts_ftick; /* First tick that we were running on */ 100 int ts_ticks; /* Tick count */ 101 #ifdef KTR 102 char ts_name[TS_NAME_LEN]; 103 #endif 104 }; 105 /* flags kept in ts_flags */ 106 #define TSF_BOUND 0x0001 /* Thread can not migrate. */ 107 #define TSF_XFERABLE 0x0002 /* Thread was added as transferable. */ 108 109 #define THREAD_CAN_MIGRATE(td) ((td)->td_pinned == 0) 110 #define THREAD_CAN_SCHED(td, cpu) \ 111 CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask) 112 113 _Static_assert(sizeof(struct thread) + sizeof(struct td_sched) <= 114 sizeof(struct thread0_storage), 115 "increase struct thread0_storage.t0st_sched size"); 116 117 /* 118 * Priority ranges used for interactive and non-interactive timeshare 119 * threads. The timeshare priorities are split up into four ranges. 120 * The first range handles interactive threads. The last three ranges 121 * (NHALF, x, and NHALF) handle non-interactive threads with the outer 122 * ranges supporting nice values. 123 */ 124 #define PRI_TIMESHARE_RANGE (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE + 1) 125 #define PRI_INTERACT_RANGE ((PRI_TIMESHARE_RANGE - SCHED_PRI_NRESV) / 2) 126 #define PRI_BATCH_RANGE (PRI_TIMESHARE_RANGE - PRI_INTERACT_RANGE) 127 128 #define PRI_MIN_INTERACT PRI_MIN_TIMESHARE 129 #define PRI_MAX_INTERACT (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE - 1) 130 #define PRI_MIN_BATCH (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE) 131 #define PRI_MAX_BATCH PRI_MAX_TIMESHARE 132 133 /* 134 * Cpu percentage computation macros and defines. 135 * 136 * SCHED_TICK_SECS: Number of seconds to average the cpu usage across. 137 * SCHED_TICK_TARG: Number of hz ticks to average the cpu usage across. 138 * SCHED_TICK_MAX: Maximum number of ticks before scaling back. 139 * SCHED_TICK_SHIFT: Shift factor to avoid rounding away results. 140 * SCHED_TICK_HZ: Compute the number of hz ticks for a given ticks count. 141 * SCHED_TICK_TOTAL: Gives the amount of time we've been recording ticks. 142 */ 143 #define SCHED_TICK_SECS 10 144 #define SCHED_TICK_TARG (hz * SCHED_TICK_SECS) 145 #define SCHED_TICK_MAX (SCHED_TICK_TARG + hz) 146 #define SCHED_TICK_SHIFT 10 147 #define SCHED_TICK_HZ(ts) ((ts)->ts_ticks >> SCHED_TICK_SHIFT) 148 #define SCHED_TICK_TOTAL(ts) (max((ts)->ts_ltick - (ts)->ts_ftick, hz)) 149 150 /* 151 * These macros determine priorities for non-interactive threads. They are 152 * assigned a priority based on their recent cpu utilization as expressed 153 * by the ratio of ticks to the tick total. NHALF priorities at the start 154 * and end of the MIN to MAX timeshare range are only reachable with negative 155 * or positive nice respectively. 156 * 157 * PRI_RANGE: Priority range for utilization dependent priorities. 158 * PRI_NRESV: Number of nice values. 159 * PRI_TICKS: Compute a priority in PRI_RANGE from the ticks count and total. 160 * PRI_NICE: Determines the part of the priority inherited from nice. 161 */ 162 #define SCHED_PRI_NRESV (PRIO_MAX - PRIO_MIN) 163 #define SCHED_PRI_NHALF (SCHED_PRI_NRESV / 2) 164 #define SCHED_PRI_MIN (PRI_MIN_BATCH + SCHED_PRI_NHALF) 165 #define SCHED_PRI_MAX (PRI_MAX_BATCH - SCHED_PRI_NHALF) 166 #define SCHED_PRI_RANGE (SCHED_PRI_MAX - SCHED_PRI_MIN + 1) 167 #define SCHED_PRI_TICKS(ts) \ 168 (SCHED_TICK_HZ((ts)) / \ 169 (roundup(SCHED_TICK_TOTAL((ts)), SCHED_PRI_RANGE) / SCHED_PRI_RANGE)) 170 #define SCHED_PRI_NICE(nice) (nice) 171 172 /* 173 * These determine the interactivity of a process. Interactivity differs from 174 * cpu utilization in that it expresses the voluntary time slept vs time ran 175 * while cpu utilization includes all time not running. This more accurately 176 * models the intent of the thread. 177 * 178 * SLP_RUN_MAX: Maximum amount of sleep time + run time we'll accumulate 179 * before throttling back. 180 * SLP_RUN_FORK: Maximum slp+run time to inherit at fork time. 181 * INTERACT_MAX: Maximum interactivity value. Smaller is better. 182 * INTERACT_THRESH: Threshold for placement on the current runq. 183 */ 184 #define SCHED_SLP_RUN_MAX ((hz * 5) << SCHED_TICK_SHIFT) 185 #define SCHED_SLP_RUN_FORK ((hz / 2) << SCHED_TICK_SHIFT) 186 #define SCHED_INTERACT_MAX (100) 187 #define SCHED_INTERACT_HALF (SCHED_INTERACT_MAX / 2) 188 #define SCHED_INTERACT_THRESH (30) 189 190 /* 191 * These parameters determine the slice behavior for batch work. 192 */ 193 #define SCHED_SLICE_DEFAULT_DIVISOR 10 /* ~94 ms, 12 stathz ticks. */ 194 #define SCHED_SLICE_MIN_DIVISOR 6 /* DEFAULT/MIN = ~16 ms. */ 195 196 /* Flags kept in td_flags. */ 197 #define TDF_PICKCPU TDF_SCHED0 /* Thread should pick new CPU. */ 198 #define TDF_SLICEEND TDF_SCHED2 /* Thread time slice is over. */ 199 200 /* 201 * tickincr: Converts a stathz tick into a hz domain scaled by 202 * the shift factor. Without the shift the error rate 203 * due to rounding would be unacceptably high. 204 * realstathz: stathz is sometimes 0 and run off of hz. 205 * sched_slice: Runtime of each thread before rescheduling. 206 * preempt_thresh: Priority threshold for preemption and remote IPIs. 207 */ 208 static u_int __read_mostly sched_interact = SCHED_INTERACT_THRESH; 209 static int __read_mostly tickincr = 8 << SCHED_TICK_SHIFT; 210 static int __read_mostly realstathz = 127; /* reset during boot. */ 211 static int __read_mostly sched_slice = 10; /* reset during boot. */ 212 static int __read_mostly sched_slice_min = 1; /* reset during boot. */ 213 #ifdef PREEMPTION 214 #ifdef FULL_PREEMPTION 215 static int __read_mostly preempt_thresh = PRI_MAX_IDLE; 216 #else 217 static int __read_mostly preempt_thresh = PRI_MIN_KERN; 218 #endif 219 #else 220 static int __read_mostly preempt_thresh = 0; 221 #endif 222 static int __read_mostly static_boost = PRI_MIN_BATCH; 223 static int __read_mostly sched_idlespins = 10000; 224 static int __read_mostly sched_idlespinthresh = -1; 225 226 /* 227 * tdq - per processor runqs and statistics. A mutex synchronizes access to 228 * most fields. Some fields are loaded or modified without the mutex. 229 * 230 * Locking protocols: 231 * (c) constant after initialization 232 * (f) flag, set with the tdq lock held, cleared on local CPU 233 * (l) all accesses are CPU-local 234 * (ls) stores are performed by the local CPU, loads may be lockless 235 * (t) all accesses are protected by the tdq mutex 236 * (ts) stores are serialized by the tdq mutex, loads may be lockless 237 */ 238 struct tdq { 239 /* 240 * Ordered to improve efficiency of cpu_search() and switch(). 241 * tdq_lock is padded to avoid false sharing with tdq_load and 242 * tdq_cpu_idle. 243 */ 244 struct mtx_padalign tdq_lock; /* run queue lock. */ 245 struct cpu_group *tdq_cg; /* (c) Pointer to cpu topology. */ 246 struct thread *tdq_curthread; /* (t) Current executing thread. */ 247 int tdq_load; /* (ts) Aggregate load. */ 248 int tdq_sysload; /* (ts) For loadavg, !ITHD load. */ 249 int tdq_cpu_idle; /* (ls) cpu_idle() is active. */ 250 int tdq_transferable; /* (ts) Transferable thread count. */ 251 short tdq_switchcnt; /* (l) Switches this tick. */ 252 short tdq_oldswitchcnt; /* (l) Switches last tick. */ 253 u_char tdq_lowpri; /* (ts) Lowest priority thread. */ 254 u_char tdq_owepreempt; /* (f) Remote preemption pending. */ 255 u_char tdq_idx; /* (t) Current insert index. */ 256 u_char tdq_ridx; /* (t) Current removal index. */ 257 int tdq_id; /* (c) cpuid. */ 258 struct runq tdq_realtime; /* (t) real-time run queue. */ 259 struct runq tdq_timeshare; /* (t) timeshare run queue. */ 260 struct runq tdq_idle; /* (t) Queue of IDLE threads. */ 261 char tdq_name[TDQ_NAME_LEN]; 262 #ifdef KTR 263 char tdq_loadname[TDQ_LOADNAME_LEN]; 264 #endif 265 }; 266 267 /* Idle thread states and config. */ 268 #define TDQ_RUNNING 1 269 #define TDQ_IDLE 2 270 271 /* Lockless accessors. */ 272 #define TDQ_LOAD(tdq) atomic_load_int(&(tdq)->tdq_load) 273 #define TDQ_TRANSFERABLE(tdq) atomic_load_int(&(tdq)->tdq_transferable) 274 #define TDQ_SWITCHCNT(tdq) (atomic_load_short(&(tdq)->tdq_switchcnt) + \ 275 atomic_load_short(&(tdq)->tdq_oldswitchcnt)) 276 #define TDQ_SWITCHCNT_INC(tdq) (atomic_store_short(&(tdq)->tdq_switchcnt, \ 277 atomic_load_short(&(tdq)->tdq_switchcnt) + 1)) 278 279 #ifdef SMP 280 struct cpu_group __read_mostly *cpu_top; /* CPU topology */ 281 282 #define SCHED_AFFINITY_DEFAULT (max(1, hz / 1000)) 283 #define SCHED_AFFINITY(ts, t) ((ts)->ts_rltick > ticks - ((t) * affinity)) 284 285 /* 286 * Run-time tunables. 287 */ 288 static int rebalance = 1; 289 static int balance_interval = 128; /* Default set in sched_initticks(). */ 290 static int __read_mostly affinity; 291 static int __read_mostly steal_idle = 1; 292 static int __read_mostly steal_thresh = 2; 293 static int __read_mostly always_steal = 0; 294 static int __read_mostly trysteal_limit = 2; 295 296 /* 297 * One thread queue per processor. 298 */ 299 static struct tdq __read_mostly *balance_tdq; 300 static int balance_ticks; 301 DPCPU_DEFINE_STATIC(struct tdq, tdq); 302 DPCPU_DEFINE_STATIC(uint32_t, randomval); 303 304 #define TDQ_SELF() ((struct tdq *)PCPU_GET(sched)) 305 #define TDQ_CPU(x) (DPCPU_ID_PTR((x), tdq)) 306 #define TDQ_ID(x) ((x)->tdq_id) 307 #else /* !SMP */ 308 static struct tdq tdq_cpu; 309 310 #define TDQ_ID(x) (0) 311 #define TDQ_SELF() (&tdq_cpu) 312 #define TDQ_CPU(x) (&tdq_cpu) 313 #endif 314 315 #define TDQ_LOCK_ASSERT(t, type) mtx_assert(TDQ_LOCKPTR((t)), (type)) 316 #define TDQ_LOCK(t) mtx_lock_spin(TDQ_LOCKPTR((t))) 317 #define TDQ_LOCK_FLAGS(t, f) mtx_lock_spin_flags(TDQ_LOCKPTR((t)), (f)) 318 #define TDQ_TRYLOCK(t) mtx_trylock_spin(TDQ_LOCKPTR((t))) 319 #define TDQ_TRYLOCK_FLAGS(t, f) mtx_trylock_spin_flags(TDQ_LOCKPTR((t)), (f)) 320 #define TDQ_UNLOCK(t) mtx_unlock_spin(TDQ_LOCKPTR((t))) 321 #define TDQ_LOCKPTR(t) ((struct mtx *)(&(t)->tdq_lock)) 322 323 static void sched_setpreempt(int); 324 static void sched_priority(struct thread *); 325 static void sched_thread_priority(struct thread *, u_char); 326 static int sched_interact_score(struct thread *); 327 static void sched_interact_update(struct thread *); 328 static void sched_interact_fork(struct thread *); 329 static void sched_pctcpu_update(struct td_sched *, int); 330 331 /* Operations on per processor queues */ 332 static struct thread *tdq_choose(struct tdq *); 333 static void tdq_setup(struct tdq *, int i); 334 static void tdq_load_add(struct tdq *, struct thread *); 335 static void tdq_load_rem(struct tdq *, struct thread *); 336 static __inline void tdq_runq_add(struct tdq *, struct thread *, int); 337 static __inline void tdq_runq_rem(struct tdq *, struct thread *); 338 static inline int sched_shouldpreempt(int, int, int); 339 static void tdq_print(int cpu); 340 static void runq_print(struct runq *rq); 341 static int tdq_add(struct tdq *, struct thread *, int); 342 #ifdef SMP 343 static int tdq_move(struct tdq *, struct tdq *); 344 static int tdq_idled(struct tdq *); 345 static void tdq_notify(struct tdq *, int lowpri); 346 static struct thread *tdq_steal(struct tdq *, int); 347 static struct thread *runq_steal(struct runq *, int); 348 static int sched_pickcpu(struct thread *, int); 349 static void sched_balance(void); 350 static bool sched_balance_pair(struct tdq *, struct tdq *); 351 static inline struct tdq *sched_setcpu(struct thread *, int, int); 352 static inline void thread_unblock_switch(struct thread *, struct mtx *); 353 static int sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS); 354 static int sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, 355 struct cpu_group *cg, int indent); 356 #endif 357 358 static void sched_setup(void *dummy); 359 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL); 360 361 static void sched_initticks(void *dummy); 362 SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks, 363 NULL); 364 365 SDT_PROVIDER_DEFINE(sched); 366 367 SDT_PROBE_DEFINE3(sched, , , change__pri, "struct thread *", 368 "struct proc *", "uint8_t"); 369 SDT_PROBE_DEFINE3(sched, , , dequeue, "struct thread *", 370 "struct proc *", "void *"); 371 SDT_PROBE_DEFINE4(sched, , , enqueue, "struct thread *", 372 "struct proc *", "void *", "int"); 373 SDT_PROBE_DEFINE4(sched, , , lend__pri, "struct thread *", 374 "struct proc *", "uint8_t", "struct thread *"); 375 SDT_PROBE_DEFINE2(sched, , , load__change, "int", "int"); 376 SDT_PROBE_DEFINE2(sched, , , off__cpu, "struct thread *", 377 "struct proc *"); 378 SDT_PROBE_DEFINE(sched, , , on__cpu); 379 SDT_PROBE_DEFINE(sched, , , remain__cpu); 380 SDT_PROBE_DEFINE2(sched, , , surrender, "struct thread *", 381 "struct proc *"); 382 383 /* 384 * Print the threads waiting on a run-queue. 385 */ 386 static void 387 runq_print(struct runq *rq) 388 { 389 struct rqhead *rqh; 390 struct thread *td; 391 int pri; 392 int j; 393 int i; 394 395 for (i = 0; i < RQB_LEN; i++) { 396 printf("\t\trunq bits %d 0x%zx\n", 397 i, rq->rq_status.rqb_bits[i]); 398 for (j = 0; j < RQB_BPW; j++) 399 if (rq->rq_status.rqb_bits[i] & (1ul << j)) { 400 pri = j + (i << RQB_L2BPW); 401 rqh = &rq->rq_queues[pri]; 402 TAILQ_FOREACH(td, rqh, td_runq) { 403 printf("\t\t\ttd %p(%s) priority %d rqindex %d pri %d\n", 404 td, td->td_name, td->td_priority, 405 td->td_rqindex, pri); 406 } 407 } 408 } 409 } 410 411 /* 412 * Print the status of a per-cpu thread queue. Should be a ddb show cmd. 413 */ 414 static void __unused 415 tdq_print(int cpu) 416 { 417 struct tdq *tdq; 418 419 tdq = TDQ_CPU(cpu); 420 421 printf("tdq %d:\n", TDQ_ID(tdq)); 422 printf("\tlock %p\n", TDQ_LOCKPTR(tdq)); 423 printf("\tLock name: %s\n", tdq->tdq_name); 424 printf("\tload: %d\n", tdq->tdq_load); 425 printf("\tswitch cnt: %d\n", tdq->tdq_switchcnt); 426 printf("\told switch cnt: %d\n", tdq->tdq_oldswitchcnt); 427 printf("\ttimeshare idx: %d\n", tdq->tdq_idx); 428 printf("\ttimeshare ridx: %d\n", tdq->tdq_ridx); 429 printf("\tload transferable: %d\n", tdq->tdq_transferable); 430 printf("\tlowest priority: %d\n", tdq->tdq_lowpri); 431 printf("\trealtime runq:\n"); 432 runq_print(&tdq->tdq_realtime); 433 printf("\ttimeshare runq:\n"); 434 runq_print(&tdq->tdq_timeshare); 435 printf("\tidle runq:\n"); 436 runq_print(&tdq->tdq_idle); 437 } 438 439 static inline int 440 sched_shouldpreempt(int pri, int cpri, int remote) 441 { 442 /* 443 * If the new priority is not better than the current priority there is 444 * nothing to do. 445 */ 446 if (pri >= cpri) 447 return (0); 448 /* 449 * Always preempt idle. 450 */ 451 if (cpri >= PRI_MIN_IDLE) 452 return (1); 453 /* 454 * If preemption is disabled don't preempt others. 455 */ 456 if (preempt_thresh == 0) 457 return (0); 458 /* 459 * Preempt if we exceed the threshold. 460 */ 461 if (pri <= preempt_thresh) 462 return (1); 463 /* 464 * If we're interactive or better and there is non-interactive 465 * or worse running preempt only remote processors. 466 */ 467 if (remote && pri <= PRI_MAX_INTERACT && cpri > PRI_MAX_INTERACT) 468 return (1); 469 return (0); 470 } 471 472 /* 473 * Add a thread to the actual run-queue. Keeps transferable counts up to 474 * date with what is actually on the run-queue. Selects the correct 475 * queue position for timeshare threads. 476 */ 477 static __inline void 478 tdq_runq_add(struct tdq *tdq, struct thread *td, int flags) 479 { 480 struct td_sched *ts; 481 u_char pri; 482 483 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 484 THREAD_LOCK_BLOCKED_ASSERT(td, MA_OWNED); 485 486 pri = td->td_priority; 487 ts = td_get_sched(td); 488 TD_SET_RUNQ(td); 489 if (THREAD_CAN_MIGRATE(td)) { 490 tdq->tdq_transferable++; 491 ts->ts_flags |= TSF_XFERABLE; 492 } 493 if (pri < PRI_MIN_BATCH) { 494 ts->ts_runq = &tdq->tdq_realtime; 495 } else if (pri <= PRI_MAX_BATCH) { 496 ts->ts_runq = &tdq->tdq_timeshare; 497 KASSERT(pri <= PRI_MAX_BATCH && pri >= PRI_MIN_BATCH, 498 ("Invalid priority %d on timeshare runq", pri)); 499 /* 500 * This queue contains only priorities between MIN and MAX 501 * batch. Use the whole queue to represent these values. 502 */ 503 if ((flags & (SRQ_BORROWING|SRQ_PREEMPTED)) == 0) { 504 pri = RQ_NQS * (pri - PRI_MIN_BATCH) / PRI_BATCH_RANGE; 505 pri = (pri + tdq->tdq_idx) % RQ_NQS; 506 /* 507 * This effectively shortens the queue by one so we 508 * can have a one slot difference between idx and 509 * ridx while we wait for threads to drain. 510 */ 511 if (tdq->tdq_ridx != tdq->tdq_idx && 512 pri == tdq->tdq_ridx) 513 pri = (unsigned char)(pri - 1) % RQ_NQS; 514 } else 515 pri = tdq->tdq_ridx; 516 runq_add_pri(ts->ts_runq, td, pri, flags); 517 return; 518 } else 519 ts->ts_runq = &tdq->tdq_idle; 520 runq_add(ts->ts_runq, td, flags); 521 } 522 523 /* 524 * Remove a thread from a run-queue. This typically happens when a thread 525 * is selected to run. Running threads are not on the queue and the 526 * transferable count does not reflect them. 527 */ 528 static __inline void 529 tdq_runq_rem(struct tdq *tdq, struct thread *td) 530 { 531 struct td_sched *ts; 532 533 ts = td_get_sched(td); 534 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 535 THREAD_LOCK_BLOCKED_ASSERT(td, MA_OWNED); 536 KASSERT(ts->ts_runq != NULL, 537 ("tdq_runq_remove: thread %p null ts_runq", td)); 538 if (ts->ts_flags & TSF_XFERABLE) { 539 tdq->tdq_transferable--; 540 ts->ts_flags &= ~TSF_XFERABLE; 541 } 542 if (ts->ts_runq == &tdq->tdq_timeshare) { 543 if (tdq->tdq_idx != tdq->tdq_ridx) 544 runq_remove_idx(ts->ts_runq, td, &tdq->tdq_ridx); 545 else 546 runq_remove_idx(ts->ts_runq, td, NULL); 547 } else 548 runq_remove(ts->ts_runq, td); 549 } 550 551 /* 552 * Load is maintained for all threads RUNNING and ON_RUNQ. Add the load 553 * for this thread to the referenced thread queue. 554 */ 555 static void 556 tdq_load_add(struct tdq *tdq, struct thread *td) 557 { 558 559 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 560 THREAD_LOCK_BLOCKED_ASSERT(td, MA_OWNED); 561 562 tdq->tdq_load++; 563 if ((td->td_flags & TDF_NOLOAD) == 0) 564 tdq->tdq_sysload++; 565 KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load); 566 SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load); 567 } 568 569 /* 570 * Remove the load from a thread that is transitioning to a sleep state or 571 * exiting. 572 */ 573 static void 574 tdq_load_rem(struct tdq *tdq, struct thread *td) 575 { 576 577 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 578 THREAD_LOCK_BLOCKED_ASSERT(td, MA_OWNED); 579 KASSERT(tdq->tdq_load != 0, 580 ("tdq_load_rem: Removing with 0 load on queue %d", TDQ_ID(tdq))); 581 582 tdq->tdq_load--; 583 if ((td->td_flags & TDF_NOLOAD) == 0) 584 tdq->tdq_sysload--; 585 KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load); 586 SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load); 587 } 588 589 /* 590 * Bound timeshare latency by decreasing slice size as load increases. We 591 * consider the maximum latency as the sum of the threads waiting to run 592 * aside from curthread and target no more than sched_slice latency but 593 * no less than sched_slice_min runtime. 594 */ 595 static inline int 596 tdq_slice(struct tdq *tdq) 597 { 598 int load; 599 600 /* 601 * It is safe to use sys_load here because this is called from 602 * contexts where timeshare threads are running and so there 603 * cannot be higher priority load in the system. 604 */ 605 load = tdq->tdq_sysload - 1; 606 if (load >= SCHED_SLICE_MIN_DIVISOR) 607 return (sched_slice_min); 608 if (load <= 1) 609 return (sched_slice); 610 return (sched_slice / load); 611 } 612 613 /* 614 * Set lowpri to its exact value by searching the run-queue and 615 * evaluating curthread. curthread may be passed as an optimization. 616 */ 617 static void 618 tdq_setlowpri(struct tdq *tdq, struct thread *ctd) 619 { 620 struct thread *td; 621 622 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 623 if (ctd == NULL) 624 ctd = tdq->tdq_curthread; 625 td = tdq_choose(tdq); 626 if (td == NULL || td->td_priority > ctd->td_priority) 627 tdq->tdq_lowpri = ctd->td_priority; 628 else 629 tdq->tdq_lowpri = td->td_priority; 630 } 631 632 #ifdef SMP 633 /* 634 * We need some randomness. Implement a classic Linear Congruential 635 * Generator X_{n+1}=(aX_n+c) mod m. These values are optimized for 636 * m = 2^32, a = 69069 and c = 5. We only return the upper 16 bits 637 * of the random state (in the low bits of our answer) to keep 638 * the maximum randomness. 639 */ 640 static uint32_t 641 sched_random(void) 642 { 643 uint32_t *rndptr; 644 645 rndptr = DPCPU_PTR(randomval); 646 *rndptr = *rndptr * 69069 + 5; 647 648 return (*rndptr >> 16); 649 } 650 651 struct cpu_search { 652 cpuset_t *cs_mask; /* The mask of allowed CPUs to choose from. */ 653 int cs_prefer; /* Prefer this CPU and groups including it. */ 654 int cs_running; /* The thread is now running at cs_prefer. */ 655 int cs_pri; /* Min priority for low. */ 656 int cs_load; /* Max load for low, min load for high. */ 657 int cs_trans; /* Min transferable load for high. */ 658 }; 659 660 struct cpu_search_res { 661 int csr_cpu; /* The best CPU found. */ 662 int csr_load; /* The load of cs_cpu. */ 663 }; 664 665 /* 666 * Search the tree of cpu_groups for the lowest or highest loaded CPU. 667 * These routines actually compare the load on all paths through the tree 668 * and find the least loaded cpu on the least loaded path, which may differ 669 * from the least loaded cpu in the system. This balances work among caches 670 * and buses. 671 */ 672 static int 673 cpu_search_lowest(const struct cpu_group *cg, const struct cpu_search *s, 674 struct cpu_search_res *r) 675 { 676 struct cpu_search_res lr; 677 struct tdq *tdq; 678 int c, bload, l, load, p, total; 679 680 total = 0; 681 bload = INT_MAX; 682 r->csr_cpu = -1; 683 684 /* Loop through children CPU groups if there are any. */ 685 if (cg->cg_children > 0) { 686 for (c = cg->cg_children - 1; c >= 0; c--) { 687 load = cpu_search_lowest(&cg->cg_child[c], s, &lr); 688 total += load; 689 690 /* 691 * When balancing do not prefer SMT groups with load >1. 692 * It allows round-robin between SMT groups with equal 693 * load within parent group for more fair scheduling. 694 */ 695 if (__predict_false(s->cs_running) && 696 (cg->cg_child[c].cg_flags & CG_FLAG_THREAD) && 697 load >= 128 && (load & 128) != 0) 698 load += 128; 699 700 if (lr.csr_cpu >= 0 && (load < bload || 701 (load == bload && lr.csr_load < r->csr_load))) { 702 bload = load; 703 r->csr_cpu = lr.csr_cpu; 704 r->csr_load = lr.csr_load; 705 } 706 } 707 return (total); 708 } 709 710 /* Loop through children CPUs otherwise. */ 711 for (c = cg->cg_last; c >= cg->cg_first; c--) { 712 if (!CPU_ISSET(c, &cg->cg_mask)) 713 continue; 714 tdq = TDQ_CPU(c); 715 l = TDQ_LOAD(tdq); 716 if (c == s->cs_prefer) { 717 if (__predict_false(s->cs_running)) 718 l--; 719 p = 128; 720 } else 721 p = 0; 722 load = l * 256; 723 total += load - p; 724 725 /* 726 * Check this CPU is acceptable. 727 * If the threads is already on the CPU, don't look on the TDQ 728 * priority, since it can be the priority of the thread itself. 729 */ 730 if (l > s->cs_load || 731 (atomic_load_char(&tdq->tdq_lowpri) <= s->cs_pri && 732 (!s->cs_running || c != s->cs_prefer)) || 733 !CPU_ISSET(c, s->cs_mask)) 734 continue; 735 736 /* 737 * When balancing do not prefer CPUs with load > 1. 738 * It allows round-robin between CPUs with equal load 739 * within the CPU group for more fair scheduling. 740 */ 741 if (__predict_false(s->cs_running) && l > 0) 742 p = 0; 743 744 load -= sched_random() % 128; 745 if (bload > load - p) { 746 bload = load - p; 747 r->csr_cpu = c; 748 r->csr_load = load; 749 } 750 } 751 return (total); 752 } 753 754 static int 755 cpu_search_highest(const struct cpu_group *cg, const struct cpu_search *s, 756 struct cpu_search_res *r) 757 { 758 struct cpu_search_res lr; 759 struct tdq *tdq; 760 int c, bload, l, load, total; 761 762 total = 0; 763 bload = INT_MIN; 764 r->csr_cpu = -1; 765 766 /* Loop through children CPU groups if there are any. */ 767 if (cg->cg_children > 0) { 768 for (c = cg->cg_children - 1; c >= 0; c--) { 769 load = cpu_search_highest(&cg->cg_child[c], s, &lr); 770 total += load; 771 if (lr.csr_cpu >= 0 && (load > bload || 772 (load == bload && lr.csr_load > r->csr_load))) { 773 bload = load; 774 r->csr_cpu = lr.csr_cpu; 775 r->csr_load = lr.csr_load; 776 } 777 } 778 return (total); 779 } 780 781 /* Loop through children CPUs otherwise. */ 782 for (c = cg->cg_last; c >= cg->cg_first; c--) { 783 if (!CPU_ISSET(c, &cg->cg_mask)) 784 continue; 785 tdq = TDQ_CPU(c); 786 l = TDQ_LOAD(tdq); 787 load = l * 256; 788 total += load; 789 790 /* 791 * Check this CPU is acceptable. 792 */ 793 if (l < s->cs_load || TDQ_TRANSFERABLE(tdq) < s->cs_trans || 794 !CPU_ISSET(c, s->cs_mask)) 795 continue; 796 797 load -= sched_random() % 256; 798 if (load > bload) { 799 bload = load; 800 r->csr_cpu = c; 801 } 802 } 803 r->csr_load = bload; 804 return (total); 805 } 806 807 /* 808 * Find the cpu with the least load via the least loaded path that has a 809 * lowpri greater than pri pri. A pri of -1 indicates any priority is 810 * acceptable. 811 */ 812 static inline int 813 sched_lowest(const struct cpu_group *cg, cpuset_t *mask, int pri, int maxload, 814 int prefer, int running) 815 { 816 struct cpu_search s; 817 struct cpu_search_res r; 818 819 s.cs_prefer = prefer; 820 s.cs_running = running; 821 s.cs_mask = mask; 822 s.cs_pri = pri; 823 s.cs_load = maxload; 824 cpu_search_lowest(cg, &s, &r); 825 return (r.csr_cpu); 826 } 827 828 /* 829 * Find the cpu with the highest load via the highest loaded path. 830 */ 831 static inline int 832 sched_highest(const struct cpu_group *cg, cpuset_t *mask, int minload, 833 int mintrans) 834 { 835 struct cpu_search s; 836 struct cpu_search_res r; 837 838 s.cs_mask = mask; 839 s.cs_load = minload; 840 s.cs_trans = mintrans; 841 cpu_search_highest(cg, &s, &r); 842 return (r.csr_cpu); 843 } 844 845 static void 846 sched_balance_group(struct cpu_group *cg) 847 { 848 struct tdq *tdq; 849 struct thread *td; 850 cpuset_t hmask, lmask; 851 int high, low, anylow; 852 853 CPU_FILL(&hmask); 854 for (;;) { 855 high = sched_highest(cg, &hmask, 1, 0); 856 /* Stop if there is no more CPU with transferrable threads. */ 857 if (high == -1) 858 break; 859 CPU_CLR(high, &hmask); 860 CPU_COPY(&hmask, &lmask); 861 /* Stop if there is no more CPU left for low. */ 862 if (CPU_EMPTY(&lmask)) 863 break; 864 tdq = TDQ_CPU(high); 865 if (TDQ_LOAD(tdq) == 1) { 866 /* 867 * There is only one running thread. We can't move 868 * it from here, so tell it to pick new CPU by itself. 869 */ 870 TDQ_LOCK(tdq); 871 td = tdq->tdq_curthread; 872 if (td->td_lock == TDQ_LOCKPTR(tdq) && 873 (td->td_flags & TDF_IDLETD) == 0 && 874 THREAD_CAN_MIGRATE(td)) { 875 td->td_flags |= TDF_PICKCPU; 876 ast_sched_locked(td, TDA_SCHED); 877 if (high != curcpu) 878 ipi_cpu(high, IPI_AST); 879 } 880 TDQ_UNLOCK(tdq); 881 break; 882 } 883 anylow = 1; 884 nextlow: 885 if (TDQ_TRANSFERABLE(tdq) == 0) 886 continue; 887 low = sched_lowest(cg, &lmask, -1, TDQ_LOAD(tdq) - 1, high, 1); 888 /* Stop if we looked well and found no less loaded CPU. */ 889 if (anylow && low == -1) 890 break; 891 /* Go to next high if we found no less loaded CPU. */ 892 if (low == -1) 893 continue; 894 /* Transfer thread from high to low. */ 895 if (sched_balance_pair(tdq, TDQ_CPU(low))) { 896 /* CPU that got thread can no longer be a donor. */ 897 CPU_CLR(low, &hmask); 898 } else { 899 /* 900 * If failed, then there is no threads on high 901 * that can run on this low. Drop low from low 902 * mask and look for different one. 903 */ 904 CPU_CLR(low, &lmask); 905 anylow = 0; 906 goto nextlow; 907 } 908 } 909 } 910 911 static void 912 sched_balance(void) 913 { 914 struct tdq *tdq; 915 916 balance_ticks = max(balance_interval / 2, 1) + 917 (sched_random() % balance_interval); 918 tdq = TDQ_SELF(); 919 TDQ_UNLOCK(tdq); 920 sched_balance_group(cpu_top); 921 TDQ_LOCK(tdq); 922 } 923 924 /* 925 * Lock two thread queues using their address to maintain lock order. 926 */ 927 static void 928 tdq_lock_pair(struct tdq *one, struct tdq *two) 929 { 930 if (one < two) { 931 TDQ_LOCK(one); 932 TDQ_LOCK_FLAGS(two, MTX_DUPOK); 933 } else { 934 TDQ_LOCK(two); 935 TDQ_LOCK_FLAGS(one, MTX_DUPOK); 936 } 937 } 938 939 /* 940 * Unlock two thread queues. Order is not important here. 941 */ 942 static void 943 tdq_unlock_pair(struct tdq *one, struct tdq *two) 944 { 945 TDQ_UNLOCK(one); 946 TDQ_UNLOCK(two); 947 } 948 949 /* 950 * Transfer load between two imbalanced thread queues. Returns true if a thread 951 * was moved between the queues, and false otherwise. 952 */ 953 static bool 954 sched_balance_pair(struct tdq *high, struct tdq *low) 955 { 956 int cpu, lowpri; 957 bool ret; 958 959 ret = false; 960 tdq_lock_pair(high, low); 961 962 /* 963 * Transfer a thread from high to low. 964 */ 965 if (high->tdq_transferable != 0 && high->tdq_load > low->tdq_load) { 966 lowpri = tdq_move(high, low); 967 if (lowpri != -1) { 968 /* 969 * In case the target isn't the current CPU notify it of 970 * the new load, possibly sending an IPI to force it to 971 * reschedule. Otherwise maybe schedule a preemption. 972 */ 973 cpu = TDQ_ID(low); 974 if (cpu != PCPU_GET(cpuid)) 975 tdq_notify(low, lowpri); 976 else 977 sched_setpreempt(low->tdq_lowpri); 978 ret = true; 979 } 980 } 981 tdq_unlock_pair(high, low); 982 return (ret); 983 } 984 985 /* 986 * Move a thread from one thread queue to another. Returns -1 if the source 987 * queue was empty, else returns the maximum priority of all threads in 988 * the destination queue prior to the addition of the new thread. In the latter 989 * case, this priority can be used to determine whether an IPI needs to be 990 * delivered. 991 */ 992 static int 993 tdq_move(struct tdq *from, struct tdq *to) 994 { 995 struct thread *td; 996 int cpu; 997 998 TDQ_LOCK_ASSERT(from, MA_OWNED); 999 TDQ_LOCK_ASSERT(to, MA_OWNED); 1000 1001 cpu = TDQ_ID(to); 1002 td = tdq_steal(from, cpu); 1003 if (td == NULL) 1004 return (-1); 1005 1006 /* 1007 * Although the run queue is locked the thread may be 1008 * blocked. We can not set the lock until it is unblocked. 1009 */ 1010 thread_lock_block_wait(td); 1011 sched_rem(td); 1012 THREAD_LOCKPTR_ASSERT(td, TDQ_LOCKPTR(from)); 1013 td->td_lock = TDQ_LOCKPTR(to); 1014 td_get_sched(td)->ts_cpu = cpu; 1015 return (tdq_add(to, td, SRQ_YIELDING)); 1016 } 1017 1018 /* 1019 * This tdq has idled. Try to steal a thread from another cpu and switch 1020 * to it. 1021 */ 1022 static int 1023 tdq_idled(struct tdq *tdq) 1024 { 1025 struct cpu_group *cg, *parent; 1026 struct tdq *steal; 1027 cpuset_t mask; 1028 int cpu, switchcnt, goup; 1029 1030 if (smp_started == 0 || steal_idle == 0 || tdq->tdq_cg == NULL) 1031 return (1); 1032 CPU_FILL(&mask); 1033 CPU_CLR(PCPU_GET(cpuid), &mask); 1034 restart: 1035 switchcnt = TDQ_SWITCHCNT(tdq); 1036 for (cg = tdq->tdq_cg, goup = 0; ; ) { 1037 cpu = sched_highest(cg, &mask, steal_thresh, 1); 1038 /* 1039 * We were assigned a thread but not preempted. Returning 1040 * 0 here will cause our caller to switch to it. 1041 */ 1042 if (TDQ_LOAD(tdq)) 1043 return (0); 1044 1045 /* 1046 * We found no CPU to steal from in this group. Escalate to 1047 * the parent and repeat. But if parent has only two children 1048 * groups we can avoid searching this group again by searching 1049 * the other one specifically and then escalating two levels. 1050 */ 1051 if (cpu == -1) { 1052 if (goup) { 1053 cg = cg->cg_parent; 1054 goup = 0; 1055 } 1056 parent = cg->cg_parent; 1057 if (parent == NULL) 1058 return (1); 1059 if (parent->cg_children == 2) { 1060 if (cg == &parent->cg_child[0]) 1061 cg = &parent->cg_child[1]; 1062 else 1063 cg = &parent->cg_child[0]; 1064 goup = 1; 1065 } else 1066 cg = parent; 1067 continue; 1068 } 1069 steal = TDQ_CPU(cpu); 1070 /* 1071 * The data returned by sched_highest() is stale and 1072 * the chosen CPU no longer has an eligible thread. 1073 * 1074 * Testing this ahead of tdq_lock_pair() only catches 1075 * this situation about 20% of the time on an 8 core 1076 * 16 thread Ryzen 7, but it still helps performance. 1077 */ 1078 if (TDQ_LOAD(steal) < steal_thresh || 1079 TDQ_TRANSFERABLE(steal) == 0) 1080 goto restart; 1081 /* 1082 * Try to lock both queues. If we are assigned a thread while 1083 * waited for the lock, switch to it now instead of stealing. 1084 * If we can't get the lock, then somebody likely got there 1085 * first so continue searching. 1086 */ 1087 TDQ_LOCK(tdq); 1088 if (tdq->tdq_load > 0) { 1089 mi_switch(SW_VOL | SWT_IDLE); 1090 return (0); 1091 } 1092 if (TDQ_TRYLOCK_FLAGS(steal, MTX_DUPOK) == 0) { 1093 TDQ_UNLOCK(tdq); 1094 CPU_CLR(cpu, &mask); 1095 continue; 1096 } 1097 /* 1098 * The data returned by sched_highest() is stale and 1099 * the chosen CPU no longer has an eligible thread, or 1100 * we were preempted and the CPU loading info may be out 1101 * of date. The latter is rare. In either case restart 1102 * the search. 1103 */ 1104 if (TDQ_LOAD(steal) < steal_thresh || 1105 TDQ_TRANSFERABLE(steal) == 0 || 1106 switchcnt != TDQ_SWITCHCNT(tdq)) { 1107 tdq_unlock_pair(tdq, steal); 1108 goto restart; 1109 } 1110 /* 1111 * Steal the thread and switch to it. 1112 */ 1113 if (tdq_move(steal, tdq) != -1) 1114 break; 1115 /* 1116 * We failed to acquire a thread even though it looked 1117 * like one was available. This could be due to affinity 1118 * restrictions or for other reasons. Loop again after 1119 * removing this CPU from the set. The restart logic 1120 * above does not restore this CPU to the set due to the 1121 * likelyhood of failing here again. 1122 */ 1123 CPU_CLR(cpu, &mask); 1124 tdq_unlock_pair(tdq, steal); 1125 } 1126 TDQ_UNLOCK(steal); 1127 mi_switch(SW_VOL | SWT_IDLE); 1128 return (0); 1129 } 1130 1131 /* 1132 * Notify a remote cpu of new work. Sends an IPI if criteria are met. 1133 * 1134 * "lowpri" is the minimum scheduling priority among all threads on 1135 * the queue prior to the addition of the new thread. 1136 */ 1137 static void 1138 tdq_notify(struct tdq *tdq, int lowpri) 1139 { 1140 int cpu; 1141 1142 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1143 KASSERT(tdq->tdq_lowpri <= lowpri, 1144 ("tdq_notify: lowpri %d > tdq_lowpri %d", lowpri, tdq->tdq_lowpri)); 1145 1146 if (tdq->tdq_owepreempt) 1147 return; 1148 1149 /* 1150 * Check to see if the newly added thread should preempt the one 1151 * currently running. 1152 */ 1153 if (!sched_shouldpreempt(tdq->tdq_lowpri, lowpri, 1)) 1154 return; 1155 1156 /* 1157 * Make sure that our caller's earlier update to tdq_load is 1158 * globally visible before we read tdq_cpu_idle. Idle thread 1159 * accesses both of them without locks, and the order is important. 1160 */ 1161 atomic_thread_fence_seq_cst(); 1162 1163 /* 1164 * Try to figure out if we can signal the idle thread instead of sending 1165 * an IPI. This check is racy; at worst, we will deliever an IPI 1166 * unnecessarily. 1167 */ 1168 cpu = TDQ_ID(tdq); 1169 if (TD_IS_IDLETHREAD(tdq->tdq_curthread) && 1170 (atomic_load_int(&tdq->tdq_cpu_idle) == 0 || cpu_idle_wakeup(cpu))) 1171 return; 1172 1173 /* 1174 * The run queues have been updated, so any switch on the remote CPU 1175 * will satisfy the preemption request. 1176 */ 1177 tdq->tdq_owepreempt = 1; 1178 ipi_cpu(cpu, IPI_PREEMPT); 1179 } 1180 1181 /* 1182 * Steals load from a timeshare queue. Honors the rotating queue head 1183 * index. 1184 */ 1185 static struct thread * 1186 runq_steal_from(struct runq *rq, int cpu, u_char start) 1187 { 1188 struct rqbits *rqb; 1189 struct rqhead *rqh; 1190 struct thread *td, *first; 1191 int bit; 1192 int i; 1193 1194 rqb = &rq->rq_status; 1195 bit = start & (RQB_BPW -1); 1196 first = NULL; 1197 again: 1198 for (i = RQB_WORD(start); i < RQB_LEN; bit = 0, i++) { 1199 if (rqb->rqb_bits[i] == 0) 1200 continue; 1201 if (bit == 0) 1202 bit = RQB_FFS(rqb->rqb_bits[i]); 1203 for (; bit < RQB_BPW; bit++) { 1204 if ((rqb->rqb_bits[i] & (1ul << bit)) == 0) 1205 continue; 1206 rqh = &rq->rq_queues[bit + (i << RQB_L2BPW)]; 1207 TAILQ_FOREACH(td, rqh, td_runq) { 1208 if (first) { 1209 if (THREAD_CAN_MIGRATE(td) && 1210 THREAD_CAN_SCHED(td, cpu)) 1211 return (td); 1212 } else 1213 first = td; 1214 } 1215 } 1216 } 1217 if (start != 0) { 1218 start = 0; 1219 goto again; 1220 } 1221 1222 if (first && THREAD_CAN_MIGRATE(first) && 1223 THREAD_CAN_SCHED(first, cpu)) 1224 return (first); 1225 return (NULL); 1226 } 1227 1228 /* 1229 * Steals load from a standard linear queue. 1230 */ 1231 static struct thread * 1232 runq_steal(struct runq *rq, int cpu) 1233 { 1234 struct rqhead *rqh; 1235 struct rqbits *rqb; 1236 struct thread *td; 1237 int word; 1238 int bit; 1239 1240 rqb = &rq->rq_status; 1241 for (word = 0; word < RQB_LEN; word++) { 1242 if (rqb->rqb_bits[word] == 0) 1243 continue; 1244 for (bit = 0; bit < RQB_BPW; bit++) { 1245 if ((rqb->rqb_bits[word] & (1ul << bit)) == 0) 1246 continue; 1247 rqh = &rq->rq_queues[bit + (word << RQB_L2BPW)]; 1248 TAILQ_FOREACH(td, rqh, td_runq) 1249 if (THREAD_CAN_MIGRATE(td) && 1250 THREAD_CAN_SCHED(td, cpu)) 1251 return (td); 1252 } 1253 } 1254 return (NULL); 1255 } 1256 1257 /* 1258 * Attempt to steal a thread in priority order from a thread queue. 1259 */ 1260 static struct thread * 1261 tdq_steal(struct tdq *tdq, int cpu) 1262 { 1263 struct thread *td; 1264 1265 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1266 if ((td = runq_steal(&tdq->tdq_realtime, cpu)) != NULL) 1267 return (td); 1268 if ((td = runq_steal_from(&tdq->tdq_timeshare, 1269 cpu, tdq->tdq_ridx)) != NULL) 1270 return (td); 1271 return (runq_steal(&tdq->tdq_idle, cpu)); 1272 } 1273 1274 /* 1275 * Sets the thread lock and ts_cpu to match the requested cpu. Unlocks the 1276 * current lock and returns with the assigned queue locked. 1277 */ 1278 static inline struct tdq * 1279 sched_setcpu(struct thread *td, int cpu, int flags) 1280 { 1281 1282 struct tdq *tdq; 1283 struct mtx *mtx; 1284 1285 THREAD_LOCK_ASSERT(td, MA_OWNED); 1286 tdq = TDQ_CPU(cpu); 1287 td_get_sched(td)->ts_cpu = cpu; 1288 /* 1289 * If the lock matches just return the queue. 1290 */ 1291 if (td->td_lock == TDQ_LOCKPTR(tdq)) { 1292 KASSERT((flags & SRQ_HOLD) == 0, 1293 ("sched_setcpu: Invalid lock for SRQ_HOLD")); 1294 return (tdq); 1295 } 1296 1297 /* 1298 * The hard case, migration, we need to block the thread first to 1299 * prevent order reversals with other cpus locks. 1300 */ 1301 spinlock_enter(); 1302 mtx = thread_lock_block(td); 1303 if ((flags & SRQ_HOLD) == 0) 1304 mtx_unlock_spin(mtx); 1305 TDQ_LOCK(tdq); 1306 thread_lock_unblock(td, TDQ_LOCKPTR(tdq)); 1307 spinlock_exit(); 1308 return (tdq); 1309 } 1310 1311 SCHED_STAT_DEFINE(pickcpu_intrbind, "Soft interrupt binding"); 1312 SCHED_STAT_DEFINE(pickcpu_idle_affinity, "Picked idle cpu based on affinity"); 1313 SCHED_STAT_DEFINE(pickcpu_affinity, "Picked cpu based on affinity"); 1314 SCHED_STAT_DEFINE(pickcpu_lowest, "Selected lowest load"); 1315 SCHED_STAT_DEFINE(pickcpu_local, "Migrated to current cpu"); 1316 SCHED_STAT_DEFINE(pickcpu_migration, "Selection may have caused migration"); 1317 1318 static int 1319 sched_pickcpu(struct thread *td, int flags) 1320 { 1321 struct cpu_group *cg, *ccg; 1322 struct td_sched *ts; 1323 struct tdq *tdq; 1324 cpuset_t *mask; 1325 int cpu, pri, r, self, intr; 1326 1327 self = PCPU_GET(cpuid); 1328 ts = td_get_sched(td); 1329 KASSERT(!CPU_ABSENT(ts->ts_cpu), ("sched_pickcpu: Start scheduler on " 1330 "absent CPU %d for thread %s.", ts->ts_cpu, td->td_name)); 1331 if (smp_started == 0) 1332 return (self); 1333 /* 1334 * Don't migrate a running thread from sched_switch(). 1335 */ 1336 if ((flags & SRQ_OURSELF) || !THREAD_CAN_MIGRATE(td)) 1337 return (ts->ts_cpu); 1338 /* 1339 * Prefer to run interrupt threads on the processors that generate 1340 * the interrupt. 1341 */ 1342 if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_SCHED(td, self) && 1343 curthread->td_intr_nesting_level) { 1344 tdq = TDQ_SELF(); 1345 if (tdq->tdq_lowpri >= PRI_MIN_IDLE) { 1346 SCHED_STAT_INC(pickcpu_idle_affinity); 1347 return (self); 1348 } 1349 ts->ts_cpu = self; 1350 intr = 1; 1351 cg = tdq->tdq_cg; 1352 goto llc; 1353 } else { 1354 intr = 0; 1355 tdq = TDQ_CPU(ts->ts_cpu); 1356 cg = tdq->tdq_cg; 1357 } 1358 /* 1359 * If the thread can run on the last cpu and the affinity has not 1360 * expired and it is idle, run it there. 1361 */ 1362 if (THREAD_CAN_SCHED(td, ts->ts_cpu) && 1363 atomic_load_char(&tdq->tdq_lowpri) >= PRI_MIN_IDLE && 1364 SCHED_AFFINITY(ts, CG_SHARE_L2)) { 1365 if (cg->cg_flags & CG_FLAG_THREAD) { 1366 /* Check all SMT threads for being idle. */ 1367 for (cpu = cg->cg_first; cpu <= cg->cg_last; cpu++) { 1368 pri = 1369 atomic_load_char(&TDQ_CPU(cpu)->tdq_lowpri); 1370 if (CPU_ISSET(cpu, &cg->cg_mask) && 1371 pri < PRI_MIN_IDLE) 1372 break; 1373 } 1374 if (cpu > cg->cg_last) { 1375 SCHED_STAT_INC(pickcpu_idle_affinity); 1376 return (ts->ts_cpu); 1377 } 1378 } else { 1379 SCHED_STAT_INC(pickcpu_idle_affinity); 1380 return (ts->ts_cpu); 1381 } 1382 } 1383 llc: 1384 /* 1385 * Search for the last level cache CPU group in the tree. 1386 * Skip SMT, identical groups and caches with expired affinity. 1387 * Interrupt threads affinity is explicit and never expires. 1388 */ 1389 for (ccg = NULL; cg != NULL; cg = cg->cg_parent) { 1390 if (cg->cg_flags & CG_FLAG_THREAD) 1391 continue; 1392 if (cg->cg_children == 1 || cg->cg_count == 1) 1393 continue; 1394 if (cg->cg_level == CG_SHARE_NONE || 1395 (!intr && !SCHED_AFFINITY(ts, cg->cg_level))) 1396 continue; 1397 ccg = cg; 1398 } 1399 /* Found LLC shared by all CPUs, so do a global search. */ 1400 if (ccg == cpu_top) 1401 ccg = NULL; 1402 cpu = -1; 1403 mask = &td->td_cpuset->cs_mask; 1404 pri = td->td_priority; 1405 r = TD_IS_RUNNING(td); 1406 /* 1407 * Try hard to keep interrupts within found LLC. Search the LLC for 1408 * the least loaded CPU we can run now. For NUMA systems it should 1409 * be within target domain, and it also reduces scheduling overhead. 1410 */ 1411 if (ccg != NULL && intr) { 1412 cpu = sched_lowest(ccg, mask, pri, INT_MAX, ts->ts_cpu, r); 1413 if (cpu >= 0) 1414 SCHED_STAT_INC(pickcpu_intrbind); 1415 } else 1416 /* Search the LLC for the least loaded idle CPU we can run now. */ 1417 if (ccg != NULL) { 1418 cpu = sched_lowest(ccg, mask, max(pri, PRI_MAX_TIMESHARE), 1419 INT_MAX, ts->ts_cpu, r); 1420 if (cpu >= 0) 1421 SCHED_STAT_INC(pickcpu_affinity); 1422 } 1423 /* Search globally for the least loaded CPU we can run now. */ 1424 if (cpu < 0) { 1425 cpu = sched_lowest(cpu_top, mask, pri, INT_MAX, ts->ts_cpu, r); 1426 if (cpu >= 0) 1427 SCHED_STAT_INC(pickcpu_lowest); 1428 } 1429 /* Search globally for the least loaded CPU. */ 1430 if (cpu < 0) { 1431 cpu = sched_lowest(cpu_top, mask, -1, INT_MAX, ts->ts_cpu, r); 1432 if (cpu >= 0) 1433 SCHED_STAT_INC(pickcpu_lowest); 1434 } 1435 KASSERT(cpu >= 0, ("sched_pickcpu: Failed to find a cpu.")); 1436 KASSERT(!CPU_ABSENT(cpu), ("sched_pickcpu: Picked absent CPU %d.", cpu)); 1437 /* 1438 * Compare the lowest loaded cpu to current cpu. 1439 */ 1440 tdq = TDQ_CPU(cpu); 1441 if (THREAD_CAN_SCHED(td, self) && TDQ_SELF()->tdq_lowpri > pri && 1442 atomic_load_char(&tdq->tdq_lowpri) < PRI_MIN_IDLE && 1443 TDQ_LOAD(TDQ_SELF()) <= TDQ_LOAD(tdq) + 1) { 1444 SCHED_STAT_INC(pickcpu_local); 1445 cpu = self; 1446 } 1447 if (cpu != ts->ts_cpu) 1448 SCHED_STAT_INC(pickcpu_migration); 1449 return (cpu); 1450 } 1451 #endif 1452 1453 /* 1454 * Pick the highest priority task we have and return it. 1455 */ 1456 static struct thread * 1457 tdq_choose(struct tdq *tdq) 1458 { 1459 struct thread *td; 1460 1461 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1462 td = runq_choose(&tdq->tdq_realtime); 1463 if (td != NULL) 1464 return (td); 1465 td = runq_choose_from(&tdq->tdq_timeshare, tdq->tdq_ridx); 1466 if (td != NULL) { 1467 KASSERT(td->td_priority >= PRI_MIN_BATCH, 1468 ("tdq_choose: Invalid priority on timeshare queue %d", 1469 td->td_priority)); 1470 return (td); 1471 } 1472 td = runq_choose(&tdq->tdq_idle); 1473 if (td != NULL) { 1474 KASSERT(td->td_priority >= PRI_MIN_IDLE, 1475 ("tdq_choose: Invalid priority on idle queue %d", 1476 td->td_priority)); 1477 return (td); 1478 } 1479 1480 return (NULL); 1481 } 1482 1483 /* 1484 * Initialize a thread queue. 1485 */ 1486 static void 1487 tdq_setup(struct tdq *tdq, int id) 1488 { 1489 1490 if (bootverbose) 1491 printf("ULE: setup cpu %d\n", id); 1492 runq_init(&tdq->tdq_realtime); 1493 runq_init(&tdq->tdq_timeshare); 1494 runq_init(&tdq->tdq_idle); 1495 tdq->tdq_id = id; 1496 snprintf(tdq->tdq_name, sizeof(tdq->tdq_name), 1497 "sched lock %d", (int)TDQ_ID(tdq)); 1498 mtx_init(&tdq->tdq_lock, tdq->tdq_name, "sched lock", MTX_SPIN); 1499 #ifdef KTR 1500 snprintf(tdq->tdq_loadname, sizeof(tdq->tdq_loadname), 1501 "CPU %d load", (int)TDQ_ID(tdq)); 1502 #endif 1503 } 1504 1505 #ifdef SMP 1506 static void 1507 sched_setup_smp(void) 1508 { 1509 struct tdq *tdq; 1510 int i; 1511 1512 cpu_top = smp_topo(); 1513 CPU_FOREACH(i) { 1514 tdq = DPCPU_ID_PTR(i, tdq); 1515 tdq_setup(tdq, i); 1516 tdq->tdq_cg = smp_topo_find(cpu_top, i); 1517 if (tdq->tdq_cg == NULL) 1518 panic("Can't find cpu group for %d\n", i); 1519 DPCPU_ID_SET(i, randomval, i * 69069 + 5); 1520 } 1521 PCPU_SET(sched, DPCPU_PTR(tdq)); 1522 balance_tdq = TDQ_SELF(); 1523 } 1524 #endif 1525 1526 /* 1527 * Setup the thread queues and initialize the topology based on MD 1528 * information. 1529 */ 1530 static void 1531 sched_setup(void *dummy) 1532 { 1533 struct tdq *tdq; 1534 1535 #ifdef SMP 1536 sched_setup_smp(); 1537 #else 1538 tdq_setup(TDQ_SELF(), 0); 1539 #endif 1540 tdq = TDQ_SELF(); 1541 1542 /* Add thread0's load since it's running. */ 1543 TDQ_LOCK(tdq); 1544 thread0.td_lock = TDQ_LOCKPTR(tdq); 1545 tdq_load_add(tdq, &thread0); 1546 tdq->tdq_curthread = &thread0; 1547 tdq->tdq_lowpri = thread0.td_priority; 1548 TDQ_UNLOCK(tdq); 1549 } 1550 1551 /* 1552 * This routine determines time constants after stathz and hz are setup. 1553 */ 1554 /* ARGSUSED */ 1555 static void 1556 sched_initticks(void *dummy) 1557 { 1558 int incr; 1559 1560 realstathz = stathz ? stathz : hz; 1561 sched_slice = realstathz / SCHED_SLICE_DEFAULT_DIVISOR; 1562 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 1563 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 1564 realstathz); 1565 1566 /* 1567 * tickincr is shifted out by 10 to avoid rounding errors due to 1568 * hz not being evenly divisible by stathz on all platforms. 1569 */ 1570 incr = (hz << SCHED_TICK_SHIFT) / realstathz; 1571 /* 1572 * This does not work for values of stathz that are more than 1573 * 1 << SCHED_TICK_SHIFT * hz. In practice this does not happen. 1574 */ 1575 if (incr == 0) 1576 incr = 1; 1577 tickincr = incr; 1578 #ifdef SMP 1579 /* 1580 * Set the default balance interval now that we know 1581 * what realstathz is. 1582 */ 1583 balance_interval = realstathz; 1584 balance_ticks = balance_interval; 1585 affinity = SCHED_AFFINITY_DEFAULT; 1586 #endif 1587 if (sched_idlespinthresh < 0) 1588 sched_idlespinthresh = 2 * max(10000, 6 * hz) / realstathz; 1589 } 1590 1591 /* 1592 * This is the core of the interactivity algorithm. Determines a score based 1593 * on past behavior. It is the ratio of sleep time to run time scaled to 1594 * a [0, 100] integer. This is the voluntary sleep time of a process, which 1595 * differs from the cpu usage because it does not account for time spent 1596 * waiting on a run-queue. Would be prettier if we had floating point. 1597 * 1598 * When a thread's sleep time is greater than its run time the 1599 * calculation is: 1600 * 1601 * scaling factor 1602 * interactivity score = --------------------- 1603 * sleep time / run time 1604 * 1605 * 1606 * When a thread's run time is greater than its sleep time the 1607 * calculation is: 1608 * 1609 * scaling factor 1610 * interactivity score = 2 * scaling factor - --------------------- 1611 * run time / sleep time 1612 */ 1613 static int 1614 sched_interact_score(struct thread *td) 1615 { 1616 struct td_sched *ts; 1617 int div; 1618 1619 ts = td_get_sched(td); 1620 /* 1621 * The score is only needed if this is likely to be an interactive 1622 * task. Don't go through the expense of computing it if there's 1623 * no chance. 1624 */ 1625 if (sched_interact <= SCHED_INTERACT_HALF && 1626 ts->ts_runtime >= ts->ts_slptime) 1627 return (SCHED_INTERACT_HALF); 1628 1629 if (ts->ts_runtime > ts->ts_slptime) { 1630 div = max(1, ts->ts_runtime / SCHED_INTERACT_HALF); 1631 return (SCHED_INTERACT_HALF + 1632 (SCHED_INTERACT_HALF - (ts->ts_slptime / div))); 1633 } 1634 if (ts->ts_slptime > ts->ts_runtime) { 1635 div = max(1, ts->ts_slptime / SCHED_INTERACT_HALF); 1636 return (ts->ts_runtime / div); 1637 } 1638 /* runtime == slptime */ 1639 if (ts->ts_runtime) 1640 return (SCHED_INTERACT_HALF); 1641 1642 /* 1643 * This can happen if slptime and runtime are 0. 1644 */ 1645 return (0); 1646 1647 } 1648 1649 /* 1650 * Scale the scheduling priority according to the "interactivity" of this 1651 * process. 1652 */ 1653 static void 1654 sched_priority(struct thread *td) 1655 { 1656 u_int pri, score; 1657 1658 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 1659 return; 1660 /* 1661 * If the score is interactive we place the thread in the realtime 1662 * queue with a priority that is less than kernel and interrupt 1663 * priorities. These threads are not subject to nice restrictions. 1664 * 1665 * Scores greater than this are placed on the normal timeshare queue 1666 * where the priority is partially decided by the most recent cpu 1667 * utilization and the rest is decided by nice value. 1668 * 1669 * The nice value of the process has a linear effect on the calculated 1670 * score. Negative nice values make it easier for a thread to be 1671 * considered interactive. 1672 */ 1673 score = imax(0, sched_interact_score(td) + td->td_proc->p_nice); 1674 if (score < sched_interact) { 1675 pri = PRI_MIN_INTERACT; 1676 pri += (PRI_MAX_INTERACT - PRI_MIN_INTERACT + 1) * score / 1677 sched_interact; 1678 KASSERT(pri >= PRI_MIN_INTERACT && pri <= PRI_MAX_INTERACT, 1679 ("sched_priority: invalid interactive priority %u score %u", 1680 pri, score)); 1681 } else { 1682 pri = SCHED_PRI_MIN; 1683 if (td_get_sched(td)->ts_ticks) 1684 pri += min(SCHED_PRI_TICKS(td_get_sched(td)), 1685 SCHED_PRI_RANGE - 1); 1686 pri += SCHED_PRI_NICE(td->td_proc->p_nice); 1687 KASSERT(pri >= PRI_MIN_BATCH && pri <= PRI_MAX_BATCH, 1688 ("sched_priority: invalid priority %u: nice %d, " 1689 "ticks %d ftick %d ltick %d tick pri %d", 1690 pri, td->td_proc->p_nice, td_get_sched(td)->ts_ticks, 1691 td_get_sched(td)->ts_ftick, td_get_sched(td)->ts_ltick, 1692 SCHED_PRI_TICKS(td_get_sched(td)))); 1693 } 1694 sched_user_prio(td, pri); 1695 1696 return; 1697 } 1698 1699 /* 1700 * This routine enforces a maximum limit on the amount of scheduling history 1701 * kept. It is called after either the slptime or runtime is adjusted. This 1702 * function is ugly due to integer math. 1703 */ 1704 static void 1705 sched_interact_update(struct thread *td) 1706 { 1707 struct td_sched *ts; 1708 u_int sum; 1709 1710 ts = td_get_sched(td); 1711 sum = ts->ts_runtime + ts->ts_slptime; 1712 if (sum < SCHED_SLP_RUN_MAX) 1713 return; 1714 /* 1715 * This only happens from two places: 1716 * 1) We have added an unusual amount of run time from fork_exit. 1717 * 2) We have added an unusual amount of sleep time from sched_sleep(). 1718 */ 1719 if (sum > SCHED_SLP_RUN_MAX * 2) { 1720 if (ts->ts_runtime > ts->ts_slptime) { 1721 ts->ts_runtime = SCHED_SLP_RUN_MAX; 1722 ts->ts_slptime = 1; 1723 } else { 1724 ts->ts_slptime = SCHED_SLP_RUN_MAX; 1725 ts->ts_runtime = 1; 1726 } 1727 return; 1728 } 1729 /* 1730 * If we have exceeded by more than 1/5th then the algorithm below 1731 * will not bring us back into range. Dividing by two here forces 1732 * us into the range of [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX] 1733 */ 1734 if (sum > (SCHED_SLP_RUN_MAX / 5) * 6) { 1735 ts->ts_runtime /= 2; 1736 ts->ts_slptime /= 2; 1737 return; 1738 } 1739 ts->ts_runtime = (ts->ts_runtime / 5) * 4; 1740 ts->ts_slptime = (ts->ts_slptime / 5) * 4; 1741 } 1742 1743 /* 1744 * Scale back the interactivity history when a child thread is created. The 1745 * history is inherited from the parent but the thread may behave totally 1746 * differently. For example, a shell spawning a compiler process. We want 1747 * to learn that the compiler is behaving badly very quickly. 1748 */ 1749 static void 1750 sched_interact_fork(struct thread *td) 1751 { 1752 struct td_sched *ts; 1753 int ratio; 1754 int sum; 1755 1756 ts = td_get_sched(td); 1757 sum = ts->ts_runtime + ts->ts_slptime; 1758 if (sum > SCHED_SLP_RUN_FORK) { 1759 ratio = sum / SCHED_SLP_RUN_FORK; 1760 ts->ts_runtime /= ratio; 1761 ts->ts_slptime /= ratio; 1762 } 1763 } 1764 1765 /* 1766 * Called from proc0_init() to setup the scheduler fields. 1767 */ 1768 void 1769 schedinit(void) 1770 { 1771 struct td_sched *ts0; 1772 1773 /* 1774 * Set up the scheduler specific parts of thread0. 1775 */ 1776 ts0 = td_get_sched(&thread0); 1777 ts0->ts_ltick = ticks; 1778 ts0->ts_ftick = ticks; 1779 ts0->ts_slice = 0; 1780 ts0->ts_cpu = curcpu; /* set valid CPU number */ 1781 } 1782 1783 /* 1784 * schedinit_ap() is needed prior to calling sched_throw(NULL) to ensure that 1785 * the pcpu requirements are met for any calls in the period between curthread 1786 * initialization and sched_throw(). One can safely add threads to the queue 1787 * before sched_throw(), for instance, as long as the thread lock is setup 1788 * correctly. 1789 * 1790 * TDQ_SELF() relies on the below sched pcpu setting; it may be used only 1791 * after schedinit_ap(). 1792 */ 1793 void 1794 schedinit_ap(void) 1795 { 1796 1797 #ifdef SMP 1798 PCPU_SET(sched, DPCPU_PTR(tdq)); 1799 #endif 1800 PCPU_GET(idlethread)->td_lock = TDQ_LOCKPTR(TDQ_SELF()); 1801 } 1802 1803 /* 1804 * This is only somewhat accurate since given many processes of the same 1805 * priority they will switch when their slices run out, which will be 1806 * at most sched_slice stathz ticks. 1807 */ 1808 int 1809 sched_rr_interval(void) 1810 { 1811 1812 /* Convert sched_slice from stathz to hz. */ 1813 return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz)); 1814 } 1815 1816 /* 1817 * Update the percent cpu tracking information when it is requested or 1818 * the total history exceeds the maximum. We keep a sliding history of 1819 * tick counts that slowly decays. This is less precise than the 4BSD 1820 * mechanism since it happens with less regular and frequent events. 1821 */ 1822 static void 1823 sched_pctcpu_update(struct td_sched *ts, int run) 1824 { 1825 int t = ticks; 1826 1827 /* 1828 * The signed difference may be negative if the thread hasn't run for 1829 * over half of the ticks rollover period. 1830 */ 1831 if ((u_int)(t - ts->ts_ltick) >= SCHED_TICK_TARG) { 1832 ts->ts_ticks = 0; 1833 ts->ts_ftick = t - SCHED_TICK_TARG; 1834 } else if (t - ts->ts_ftick >= SCHED_TICK_MAX) { 1835 ts->ts_ticks = (ts->ts_ticks / (ts->ts_ltick - ts->ts_ftick)) * 1836 (ts->ts_ltick - (t - SCHED_TICK_TARG)); 1837 ts->ts_ftick = t - SCHED_TICK_TARG; 1838 } 1839 if (run) 1840 ts->ts_ticks += (t - ts->ts_ltick) << SCHED_TICK_SHIFT; 1841 ts->ts_ltick = t; 1842 } 1843 1844 /* 1845 * Adjust the priority of a thread. Move it to the appropriate run-queue 1846 * if necessary. This is the back-end for several priority related 1847 * functions. 1848 */ 1849 static void 1850 sched_thread_priority(struct thread *td, u_char prio) 1851 { 1852 struct tdq *tdq; 1853 int oldpri; 1854 1855 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "prio", 1856 "prio:%d", td->td_priority, "new prio:%d", prio, 1857 KTR_ATTR_LINKED, sched_tdname(curthread)); 1858 SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio); 1859 if (td != curthread && prio < td->td_priority) { 1860 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread), 1861 "lend prio", "prio:%d", td->td_priority, "new prio:%d", 1862 prio, KTR_ATTR_LINKED, sched_tdname(td)); 1863 SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio, 1864 curthread); 1865 } 1866 THREAD_LOCK_ASSERT(td, MA_OWNED); 1867 if (td->td_priority == prio) 1868 return; 1869 /* 1870 * If the priority has been elevated due to priority 1871 * propagation, we may have to move ourselves to a new 1872 * queue. This could be optimized to not re-add in some 1873 * cases. 1874 */ 1875 if (TD_ON_RUNQ(td) && prio < td->td_priority) { 1876 sched_rem(td); 1877 td->td_priority = prio; 1878 sched_add(td, SRQ_BORROWING | SRQ_HOLDTD); 1879 return; 1880 } 1881 /* 1882 * If the thread is currently running we may have to adjust the lowpri 1883 * information so other cpus are aware of our current priority. 1884 */ 1885 if (TD_IS_RUNNING(td)) { 1886 tdq = TDQ_CPU(td_get_sched(td)->ts_cpu); 1887 oldpri = td->td_priority; 1888 td->td_priority = prio; 1889 if (prio < tdq->tdq_lowpri) 1890 tdq->tdq_lowpri = prio; 1891 else if (tdq->tdq_lowpri == oldpri) 1892 tdq_setlowpri(tdq, td); 1893 return; 1894 } 1895 td->td_priority = prio; 1896 } 1897 1898 /* 1899 * Update a thread's priority when it is lent another thread's 1900 * priority. 1901 */ 1902 void 1903 sched_lend_prio(struct thread *td, u_char prio) 1904 { 1905 1906 td->td_flags |= TDF_BORROWING; 1907 sched_thread_priority(td, prio); 1908 } 1909 1910 /* 1911 * Restore a thread's priority when priority propagation is 1912 * over. The prio argument is the minimum priority the thread 1913 * needs to have to satisfy other possible priority lending 1914 * requests. If the thread's regular priority is less 1915 * important than prio, the thread will keep a priority boost 1916 * of prio. 1917 */ 1918 void 1919 sched_unlend_prio(struct thread *td, u_char prio) 1920 { 1921 u_char base_pri; 1922 1923 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 1924 td->td_base_pri <= PRI_MAX_TIMESHARE) 1925 base_pri = td->td_user_pri; 1926 else 1927 base_pri = td->td_base_pri; 1928 if (prio >= base_pri) { 1929 td->td_flags &= ~TDF_BORROWING; 1930 sched_thread_priority(td, base_pri); 1931 } else 1932 sched_lend_prio(td, prio); 1933 } 1934 1935 /* 1936 * Standard entry for setting the priority to an absolute value. 1937 */ 1938 void 1939 sched_prio(struct thread *td, u_char prio) 1940 { 1941 u_char oldprio; 1942 1943 /* First, update the base priority. */ 1944 td->td_base_pri = prio; 1945 1946 /* 1947 * If the thread is borrowing another thread's priority, don't 1948 * ever lower the priority. 1949 */ 1950 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 1951 return; 1952 1953 /* Change the real priority. */ 1954 oldprio = td->td_priority; 1955 sched_thread_priority(td, prio); 1956 1957 /* 1958 * If the thread is on a turnstile, then let the turnstile update 1959 * its state. 1960 */ 1961 if (TD_ON_LOCK(td) && oldprio != prio) 1962 turnstile_adjust(td, oldprio); 1963 } 1964 1965 /* 1966 * Set the base interrupt thread priority. 1967 */ 1968 void 1969 sched_ithread_prio(struct thread *td, u_char prio) 1970 { 1971 THREAD_LOCK_ASSERT(td, MA_OWNED); 1972 MPASS(td->td_pri_class == PRI_ITHD); 1973 td->td_base_ithread_pri = prio; 1974 sched_prio(td, prio); 1975 } 1976 1977 /* 1978 * Set the base user priority, does not effect current running priority. 1979 */ 1980 void 1981 sched_user_prio(struct thread *td, u_char prio) 1982 { 1983 1984 td->td_base_user_pri = prio; 1985 if (td->td_lend_user_pri <= prio) 1986 return; 1987 td->td_user_pri = prio; 1988 } 1989 1990 void 1991 sched_lend_user_prio(struct thread *td, u_char prio) 1992 { 1993 1994 THREAD_LOCK_ASSERT(td, MA_OWNED); 1995 td->td_lend_user_pri = prio; 1996 td->td_user_pri = min(prio, td->td_base_user_pri); 1997 if (td->td_priority > td->td_user_pri) 1998 sched_prio(td, td->td_user_pri); 1999 else if (td->td_priority != td->td_user_pri) 2000 ast_sched_locked(td, TDA_SCHED); 2001 } 2002 2003 /* 2004 * Like the above but first check if there is anything to do. 2005 */ 2006 void 2007 sched_lend_user_prio_cond(struct thread *td, u_char prio) 2008 { 2009 2010 if (td->td_lend_user_pri == prio) 2011 return; 2012 2013 thread_lock(td); 2014 sched_lend_user_prio(td, prio); 2015 thread_unlock(td); 2016 } 2017 2018 #ifdef SMP 2019 /* 2020 * This tdq is about to idle. Try to steal a thread from another CPU before 2021 * choosing the idle thread. 2022 */ 2023 static void 2024 tdq_trysteal(struct tdq *tdq) 2025 { 2026 struct cpu_group *cg, *parent; 2027 struct tdq *steal; 2028 cpuset_t mask; 2029 int cpu, i, goup; 2030 2031 if (smp_started == 0 || steal_idle == 0 || trysteal_limit == 0 || 2032 tdq->tdq_cg == NULL) 2033 return; 2034 CPU_FILL(&mask); 2035 CPU_CLR(PCPU_GET(cpuid), &mask); 2036 /* We don't want to be preempted while we're iterating. */ 2037 spinlock_enter(); 2038 TDQ_UNLOCK(tdq); 2039 for (i = 1, cg = tdq->tdq_cg, goup = 0; ; ) { 2040 cpu = sched_highest(cg, &mask, steal_thresh, 1); 2041 /* 2042 * If a thread was added while interrupts were disabled don't 2043 * steal one here. 2044 */ 2045 if (TDQ_LOAD(tdq) > 0) { 2046 TDQ_LOCK(tdq); 2047 break; 2048 } 2049 2050 /* 2051 * We found no CPU to steal from in this group. Escalate to 2052 * the parent and repeat. But if parent has only two children 2053 * groups we can avoid searching this group again by searching 2054 * the other one specifically and then escalating two levels. 2055 */ 2056 if (cpu == -1) { 2057 if (goup) { 2058 cg = cg->cg_parent; 2059 goup = 0; 2060 } 2061 if (++i > trysteal_limit) { 2062 TDQ_LOCK(tdq); 2063 break; 2064 } 2065 parent = cg->cg_parent; 2066 if (parent == NULL) { 2067 TDQ_LOCK(tdq); 2068 break; 2069 } 2070 if (parent->cg_children == 2) { 2071 if (cg == &parent->cg_child[0]) 2072 cg = &parent->cg_child[1]; 2073 else 2074 cg = &parent->cg_child[0]; 2075 goup = 1; 2076 } else 2077 cg = parent; 2078 continue; 2079 } 2080 steal = TDQ_CPU(cpu); 2081 /* 2082 * The data returned by sched_highest() is stale and 2083 * the chosen CPU no longer has an eligible thread. 2084 * At this point unconditionally exit the loop to bound 2085 * the time spent in the critcal section. 2086 */ 2087 if (TDQ_LOAD(steal) < steal_thresh || 2088 TDQ_TRANSFERABLE(steal) == 0) 2089 continue; 2090 /* 2091 * Try to lock both queues. If we are assigned a thread while 2092 * waited for the lock, switch to it now instead of stealing. 2093 * If we can't get the lock, then somebody likely got there 2094 * first. 2095 */ 2096 TDQ_LOCK(tdq); 2097 if (tdq->tdq_load > 0) 2098 break; 2099 if (TDQ_TRYLOCK_FLAGS(steal, MTX_DUPOK) == 0) 2100 break; 2101 /* 2102 * The data returned by sched_highest() is stale and 2103 * the chosen CPU no longer has an eligible thread. 2104 */ 2105 if (TDQ_LOAD(steal) < steal_thresh || 2106 TDQ_TRANSFERABLE(steal) == 0) { 2107 TDQ_UNLOCK(steal); 2108 break; 2109 } 2110 /* 2111 * If we fail to acquire one due to affinity restrictions, 2112 * bail out and let the idle thread to a more complete search 2113 * outside of a critical section. 2114 */ 2115 if (tdq_move(steal, tdq) == -1) { 2116 TDQ_UNLOCK(steal); 2117 break; 2118 } 2119 TDQ_UNLOCK(steal); 2120 break; 2121 } 2122 spinlock_exit(); 2123 } 2124 #endif 2125 2126 /* 2127 * Handle migration from sched_switch(). This happens only for 2128 * cpu binding. 2129 */ 2130 static struct mtx * 2131 sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags) 2132 { 2133 struct tdq *tdn; 2134 #ifdef SMP 2135 int lowpri; 2136 #endif 2137 2138 KASSERT(THREAD_CAN_MIGRATE(td) || 2139 (td_get_sched(td)->ts_flags & TSF_BOUND) != 0, 2140 ("Thread %p shouldn't migrate", td)); 2141 KASSERT(!CPU_ABSENT(td_get_sched(td)->ts_cpu), ("sched_switch_migrate: " 2142 "thread %s queued on absent CPU %d.", td->td_name, 2143 td_get_sched(td)->ts_cpu)); 2144 tdn = TDQ_CPU(td_get_sched(td)->ts_cpu); 2145 #ifdef SMP 2146 tdq_load_rem(tdq, td); 2147 /* 2148 * Do the lock dance required to avoid LOR. We have an 2149 * extra spinlock nesting from sched_switch() which will 2150 * prevent preemption while we're holding neither run-queue lock. 2151 */ 2152 TDQ_UNLOCK(tdq); 2153 TDQ_LOCK(tdn); 2154 lowpri = tdq_add(tdn, td, flags); 2155 tdq_notify(tdn, lowpri); 2156 TDQ_UNLOCK(tdn); 2157 TDQ_LOCK(tdq); 2158 #endif 2159 return (TDQ_LOCKPTR(tdn)); 2160 } 2161 2162 /* 2163 * thread_lock_unblock() that does not assume td_lock is blocked. 2164 */ 2165 static inline void 2166 thread_unblock_switch(struct thread *td, struct mtx *mtx) 2167 { 2168 atomic_store_rel_ptr((volatile uintptr_t *)&td->td_lock, 2169 (uintptr_t)mtx); 2170 } 2171 2172 /* 2173 * Switch threads. This function has to handle threads coming in while 2174 * blocked for some reason, running, or idle. It also must deal with 2175 * migrating a thread from one queue to another as running threads may 2176 * be assigned elsewhere via binding. 2177 */ 2178 void 2179 sched_switch(struct thread *td, int flags) 2180 { 2181 struct thread *newtd; 2182 struct tdq *tdq; 2183 struct td_sched *ts; 2184 struct mtx *mtx; 2185 int srqflag; 2186 int cpuid, preempted; 2187 #ifdef SMP 2188 int pickcpu; 2189 #endif 2190 2191 THREAD_LOCK_ASSERT(td, MA_OWNED); 2192 2193 cpuid = PCPU_GET(cpuid); 2194 tdq = TDQ_SELF(); 2195 ts = td_get_sched(td); 2196 sched_pctcpu_update(ts, 1); 2197 #ifdef SMP 2198 pickcpu = (td->td_flags & TDF_PICKCPU) != 0; 2199 if (pickcpu) 2200 ts->ts_rltick = ticks - affinity * MAX_CACHE_LEVELS; 2201 else 2202 ts->ts_rltick = ticks; 2203 #endif 2204 td->td_lastcpu = td->td_oncpu; 2205 preempted = (td->td_flags & TDF_SLICEEND) == 0 && 2206 (flags & SW_PREEMPT) != 0; 2207 td->td_flags &= ~(TDF_PICKCPU | TDF_SLICEEND); 2208 ast_unsched_locked(td, TDA_SCHED); 2209 td->td_owepreempt = 0; 2210 atomic_store_char(&tdq->tdq_owepreempt, 0); 2211 if (!TD_IS_IDLETHREAD(td)) 2212 TDQ_SWITCHCNT_INC(tdq); 2213 2214 /* 2215 * Always block the thread lock so we can drop the tdq lock early. 2216 */ 2217 mtx = thread_lock_block(td); 2218 spinlock_enter(); 2219 if (TD_IS_IDLETHREAD(td)) { 2220 MPASS(mtx == TDQ_LOCKPTR(tdq)); 2221 TD_SET_CAN_RUN(td); 2222 } else if (TD_IS_RUNNING(td)) { 2223 MPASS(mtx == TDQ_LOCKPTR(tdq)); 2224 srqflag = SRQ_OURSELF | SRQ_YIELDING | 2225 (preempted ? SRQ_PREEMPTED : 0); 2226 #ifdef SMP 2227 if (THREAD_CAN_MIGRATE(td) && (!THREAD_CAN_SCHED(td, ts->ts_cpu) 2228 || pickcpu)) 2229 ts->ts_cpu = sched_pickcpu(td, 0); 2230 #endif 2231 if (ts->ts_cpu == cpuid) 2232 tdq_runq_add(tdq, td, srqflag); 2233 else 2234 mtx = sched_switch_migrate(tdq, td, srqflag); 2235 } else { 2236 /* This thread must be going to sleep. */ 2237 if (mtx != TDQ_LOCKPTR(tdq)) { 2238 mtx_unlock_spin(mtx); 2239 TDQ_LOCK(tdq); 2240 } 2241 tdq_load_rem(tdq, td); 2242 #ifdef SMP 2243 if (tdq->tdq_load == 0) 2244 tdq_trysteal(tdq); 2245 #endif 2246 } 2247 2248 #if (KTR_COMPILE & KTR_SCHED) != 0 2249 if (TD_IS_IDLETHREAD(td)) 2250 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "idle", 2251 "prio:%d", td->td_priority); 2252 else 2253 KTR_STATE3(KTR_SCHED, "thread", sched_tdname(td), KTDSTATE(td), 2254 "prio:%d", td->td_priority, "wmesg:\"%s\"", td->td_wmesg, 2255 "lockname:\"%s\"", td->td_lockname); 2256 #endif 2257 2258 /* 2259 * We enter here with the thread blocked and assigned to the 2260 * appropriate cpu run-queue or sleep-queue and with the current 2261 * thread-queue locked. 2262 */ 2263 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 2264 MPASS(td == tdq->tdq_curthread); 2265 newtd = choosethread(); 2266 sched_pctcpu_update(td_get_sched(newtd), 0); 2267 TDQ_UNLOCK(tdq); 2268 2269 /* 2270 * Call the MD code to switch contexts if necessary. 2271 */ 2272 if (td != newtd) { 2273 #ifdef HWPMC_HOOKS 2274 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 2275 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 2276 #endif 2277 SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc); 2278 2279 #ifdef KDTRACE_HOOKS 2280 /* 2281 * If DTrace has set the active vtime enum to anything 2282 * other than INACTIVE (0), then it should have set the 2283 * function to call. 2284 */ 2285 if (dtrace_vtime_active) 2286 (*dtrace_vtime_switch_func)(newtd); 2287 #endif 2288 td->td_oncpu = NOCPU; 2289 cpu_switch(td, newtd, mtx); 2290 cpuid = td->td_oncpu = PCPU_GET(cpuid); 2291 2292 SDT_PROBE0(sched, , , on__cpu); 2293 #ifdef HWPMC_HOOKS 2294 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 2295 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 2296 #endif 2297 } else { 2298 thread_unblock_switch(td, mtx); 2299 SDT_PROBE0(sched, , , remain__cpu); 2300 } 2301 KASSERT(curthread->td_md.md_spinlock_count == 1, 2302 ("invalid count %d", curthread->td_md.md_spinlock_count)); 2303 2304 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running", 2305 "prio:%d", td->td_priority); 2306 } 2307 2308 /* 2309 * Adjust thread priorities as a result of a nice request. 2310 */ 2311 void 2312 sched_nice(struct proc *p, int nice) 2313 { 2314 struct thread *td; 2315 2316 PROC_LOCK_ASSERT(p, MA_OWNED); 2317 2318 p->p_nice = nice; 2319 FOREACH_THREAD_IN_PROC(p, td) { 2320 thread_lock(td); 2321 sched_priority(td); 2322 sched_prio(td, td->td_base_user_pri); 2323 thread_unlock(td); 2324 } 2325 } 2326 2327 /* 2328 * Record the sleep time for the interactivity scorer. 2329 */ 2330 void 2331 sched_sleep(struct thread *td, int prio) 2332 { 2333 2334 THREAD_LOCK_ASSERT(td, MA_OWNED); 2335 2336 td->td_slptick = ticks; 2337 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 2338 return; 2339 if (static_boost == 1 && prio) 2340 sched_prio(td, prio); 2341 else if (static_boost && td->td_priority > static_boost) 2342 sched_prio(td, static_boost); 2343 } 2344 2345 /* 2346 * Schedule a thread to resume execution and record how long it voluntarily 2347 * slept. We also update the pctcpu, interactivity, and priority. 2348 * 2349 * Requires the thread lock on entry, drops on exit. 2350 */ 2351 void 2352 sched_wakeup(struct thread *td, int srqflags) 2353 { 2354 struct td_sched *ts; 2355 int slptick; 2356 2357 THREAD_LOCK_ASSERT(td, MA_OWNED); 2358 ts = td_get_sched(td); 2359 2360 /* 2361 * If we slept for more than a tick update our interactivity and 2362 * priority. 2363 */ 2364 slptick = td->td_slptick; 2365 td->td_slptick = 0; 2366 if (slptick && slptick != ticks) { 2367 ts->ts_slptime += (ticks - slptick) << SCHED_TICK_SHIFT; 2368 sched_interact_update(td); 2369 sched_pctcpu_update(ts, 0); 2370 } 2371 2372 /* 2373 * When resuming an idle ithread, restore its base ithread 2374 * priority. 2375 */ 2376 if (PRI_BASE(td->td_pri_class) == PRI_ITHD && 2377 td->td_priority != td->td_base_ithread_pri) 2378 sched_prio(td, td->td_base_ithread_pri); 2379 2380 /* 2381 * Reset the slice value since we slept and advanced the round-robin. 2382 */ 2383 ts->ts_slice = 0; 2384 sched_add(td, SRQ_BORING | srqflags); 2385 } 2386 2387 /* 2388 * Penalize the parent for creating a new child and initialize the child's 2389 * priority. 2390 */ 2391 void 2392 sched_fork(struct thread *td, struct thread *child) 2393 { 2394 THREAD_LOCK_ASSERT(td, MA_OWNED); 2395 sched_pctcpu_update(td_get_sched(td), 1); 2396 sched_fork_thread(td, child); 2397 /* 2398 * Penalize the parent and child for forking. 2399 */ 2400 sched_interact_fork(child); 2401 sched_priority(child); 2402 td_get_sched(td)->ts_runtime += tickincr; 2403 sched_interact_update(td); 2404 sched_priority(td); 2405 } 2406 2407 /* 2408 * Fork a new thread, may be within the same process. 2409 */ 2410 void 2411 sched_fork_thread(struct thread *td, struct thread *child) 2412 { 2413 struct td_sched *ts; 2414 struct td_sched *ts2; 2415 struct tdq *tdq; 2416 2417 tdq = TDQ_SELF(); 2418 THREAD_LOCK_ASSERT(td, MA_OWNED); 2419 /* 2420 * Initialize child. 2421 */ 2422 ts = td_get_sched(td); 2423 ts2 = td_get_sched(child); 2424 child->td_oncpu = NOCPU; 2425 child->td_lastcpu = NOCPU; 2426 child->td_lock = TDQ_LOCKPTR(tdq); 2427 child->td_cpuset = cpuset_ref(td->td_cpuset); 2428 child->td_domain.dr_policy = td->td_cpuset->cs_domain; 2429 ts2->ts_cpu = ts->ts_cpu; 2430 ts2->ts_flags = 0; 2431 /* 2432 * Grab our parents cpu estimation information. 2433 */ 2434 ts2->ts_ticks = ts->ts_ticks; 2435 ts2->ts_ltick = ts->ts_ltick; 2436 ts2->ts_ftick = ts->ts_ftick; 2437 /* 2438 * Do not inherit any borrowed priority from the parent. 2439 */ 2440 child->td_priority = child->td_base_pri; 2441 /* 2442 * And update interactivity score. 2443 */ 2444 ts2->ts_slptime = ts->ts_slptime; 2445 ts2->ts_runtime = ts->ts_runtime; 2446 /* Attempt to quickly learn interactivity. */ 2447 ts2->ts_slice = tdq_slice(tdq) - sched_slice_min; 2448 #ifdef KTR 2449 bzero(ts2->ts_name, sizeof(ts2->ts_name)); 2450 #endif 2451 } 2452 2453 /* 2454 * Adjust the priority class of a thread. 2455 */ 2456 void 2457 sched_class(struct thread *td, int class) 2458 { 2459 2460 THREAD_LOCK_ASSERT(td, MA_OWNED); 2461 if (td->td_pri_class == class) 2462 return; 2463 td->td_pri_class = class; 2464 } 2465 2466 /* 2467 * Return some of the child's priority and interactivity to the parent. 2468 */ 2469 void 2470 sched_exit(struct proc *p, struct thread *child) 2471 { 2472 struct thread *td; 2473 2474 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "proc exit", 2475 "prio:%d", child->td_priority); 2476 PROC_LOCK_ASSERT(p, MA_OWNED); 2477 td = FIRST_THREAD_IN_PROC(p); 2478 sched_exit_thread(td, child); 2479 } 2480 2481 /* 2482 * Penalize another thread for the time spent on this one. This helps to 2483 * worsen the priority and interactivity of processes which schedule batch 2484 * jobs such as make. This has little effect on the make process itself but 2485 * causes new processes spawned by it to receive worse scores immediately. 2486 */ 2487 void 2488 sched_exit_thread(struct thread *td, struct thread *child) 2489 { 2490 2491 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "thread exit", 2492 "prio:%d", child->td_priority); 2493 /* 2494 * Give the child's runtime to the parent without returning the 2495 * sleep time as a penalty to the parent. This causes shells that 2496 * launch expensive things to mark their children as expensive. 2497 */ 2498 thread_lock(td); 2499 td_get_sched(td)->ts_runtime += td_get_sched(child)->ts_runtime; 2500 sched_interact_update(td); 2501 sched_priority(td); 2502 thread_unlock(td); 2503 } 2504 2505 void 2506 sched_preempt(struct thread *td) 2507 { 2508 struct tdq *tdq; 2509 int flags; 2510 2511 SDT_PROBE2(sched, , , surrender, td, td->td_proc); 2512 2513 thread_lock(td); 2514 tdq = TDQ_SELF(); 2515 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2516 if (td->td_priority > tdq->tdq_lowpri) { 2517 if (td->td_critnest == 1) { 2518 flags = SW_INVOL | SW_PREEMPT; 2519 flags |= TD_IS_IDLETHREAD(td) ? SWT_REMOTEWAKEIDLE : 2520 SWT_REMOTEPREEMPT; 2521 mi_switch(flags); 2522 /* Switch dropped thread lock. */ 2523 return; 2524 } 2525 td->td_owepreempt = 1; 2526 } else { 2527 tdq->tdq_owepreempt = 0; 2528 } 2529 thread_unlock(td); 2530 } 2531 2532 /* 2533 * Fix priorities on return to user-space. Priorities may be elevated due 2534 * to static priorities in msleep() or similar. 2535 */ 2536 void 2537 sched_userret_slowpath(struct thread *td) 2538 { 2539 2540 thread_lock(td); 2541 td->td_priority = td->td_user_pri; 2542 td->td_base_pri = td->td_user_pri; 2543 tdq_setlowpri(TDQ_SELF(), td); 2544 thread_unlock(td); 2545 } 2546 2547 SCHED_STAT_DEFINE(ithread_demotions, "Interrupt thread priority demotions"); 2548 SCHED_STAT_DEFINE(ithread_preemptions, 2549 "Interrupt thread preemptions due to time-sharing"); 2550 2551 /* 2552 * Return time slice for a given thread. For ithreads this is 2553 * sched_slice. For other threads it is tdq_slice(tdq). 2554 */ 2555 static inline int 2556 td_slice(struct thread *td, struct tdq *tdq) 2557 { 2558 if (PRI_BASE(td->td_pri_class) == PRI_ITHD) 2559 return (sched_slice); 2560 return (tdq_slice(tdq)); 2561 } 2562 2563 /* 2564 * Handle a stathz tick. This is really only relevant for timeshare 2565 * and interrupt threads. 2566 */ 2567 void 2568 sched_clock(struct thread *td, int cnt) 2569 { 2570 struct tdq *tdq; 2571 struct td_sched *ts; 2572 2573 THREAD_LOCK_ASSERT(td, MA_OWNED); 2574 tdq = TDQ_SELF(); 2575 #ifdef SMP 2576 /* 2577 * We run the long term load balancer infrequently on the first cpu. 2578 */ 2579 if (balance_tdq == tdq && smp_started != 0 && rebalance != 0 && 2580 balance_ticks != 0) { 2581 balance_ticks -= cnt; 2582 if (balance_ticks <= 0) 2583 sched_balance(); 2584 } 2585 #endif 2586 /* 2587 * Save the old switch count so we have a record of the last ticks 2588 * activity. Initialize the new switch count based on our load. 2589 * If there is some activity seed it to reflect that. 2590 */ 2591 tdq->tdq_oldswitchcnt = tdq->tdq_switchcnt; 2592 tdq->tdq_switchcnt = tdq->tdq_load; 2593 2594 /* 2595 * Advance the insert index once for each tick to ensure that all 2596 * threads get a chance to run. 2597 */ 2598 if (tdq->tdq_idx == tdq->tdq_ridx) { 2599 tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS; 2600 if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx])) 2601 tdq->tdq_ridx = tdq->tdq_idx; 2602 } 2603 ts = td_get_sched(td); 2604 sched_pctcpu_update(ts, 1); 2605 if ((td->td_pri_class & PRI_FIFO_BIT) || TD_IS_IDLETHREAD(td)) 2606 return; 2607 2608 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) { 2609 /* 2610 * We used a tick; charge it to the thread so 2611 * that we can compute our interactivity. 2612 */ 2613 td_get_sched(td)->ts_runtime += tickincr * cnt; 2614 sched_interact_update(td); 2615 sched_priority(td); 2616 } 2617 2618 /* 2619 * Force a context switch if the current thread has used up a full 2620 * time slice (default is 100ms). 2621 */ 2622 ts->ts_slice += cnt; 2623 if (ts->ts_slice >= td_slice(td, tdq)) { 2624 ts->ts_slice = 0; 2625 2626 /* 2627 * If an ithread uses a full quantum, demote its 2628 * priority and preempt it. 2629 */ 2630 if (PRI_BASE(td->td_pri_class) == PRI_ITHD) { 2631 SCHED_STAT_INC(ithread_preemptions); 2632 td->td_owepreempt = 1; 2633 if (td->td_base_pri + RQ_PPQ < PRI_MAX_ITHD) { 2634 SCHED_STAT_INC(ithread_demotions); 2635 sched_prio(td, td->td_base_pri + RQ_PPQ); 2636 } 2637 } else { 2638 ast_sched_locked(td, TDA_SCHED); 2639 td->td_flags |= TDF_SLICEEND; 2640 } 2641 } 2642 } 2643 2644 u_int 2645 sched_estcpu(struct thread *td __unused) 2646 { 2647 2648 return (0); 2649 } 2650 2651 /* 2652 * Return whether the current CPU has runnable tasks. Used for in-kernel 2653 * cooperative idle threads. 2654 */ 2655 int 2656 sched_runnable(void) 2657 { 2658 struct tdq *tdq; 2659 int load; 2660 2661 load = 1; 2662 2663 tdq = TDQ_SELF(); 2664 if ((curthread->td_flags & TDF_IDLETD) != 0) { 2665 if (TDQ_LOAD(tdq) > 0) 2666 goto out; 2667 } else 2668 if (TDQ_LOAD(tdq) - 1 > 0) 2669 goto out; 2670 load = 0; 2671 out: 2672 return (load); 2673 } 2674 2675 /* 2676 * Choose the highest priority thread to run. The thread is removed from 2677 * the run-queue while running however the load remains. 2678 */ 2679 struct thread * 2680 sched_choose(void) 2681 { 2682 struct thread *td; 2683 struct tdq *tdq; 2684 2685 tdq = TDQ_SELF(); 2686 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2687 td = tdq_choose(tdq); 2688 if (td != NULL) { 2689 tdq_runq_rem(tdq, td); 2690 tdq->tdq_lowpri = td->td_priority; 2691 } else { 2692 tdq->tdq_lowpri = PRI_MAX_IDLE; 2693 td = PCPU_GET(idlethread); 2694 } 2695 tdq->tdq_curthread = td; 2696 return (td); 2697 } 2698 2699 /* 2700 * Set owepreempt if the currently running thread has lower priority than "pri". 2701 * Preemption never happens directly in ULE, we always request it once we exit a 2702 * critical section. 2703 */ 2704 static void 2705 sched_setpreempt(int pri) 2706 { 2707 struct thread *ctd; 2708 int cpri; 2709 2710 ctd = curthread; 2711 THREAD_LOCK_ASSERT(ctd, MA_OWNED); 2712 2713 cpri = ctd->td_priority; 2714 if (pri < cpri) 2715 ast_sched_locked(ctd, TDA_SCHED); 2716 if (KERNEL_PANICKED() || pri >= cpri || cold || TD_IS_INHIBITED(ctd)) 2717 return; 2718 if (!sched_shouldpreempt(pri, cpri, 0)) 2719 return; 2720 ctd->td_owepreempt = 1; 2721 } 2722 2723 /* 2724 * Add a thread to a thread queue. Select the appropriate runq and add the 2725 * thread to it. This is the internal function called when the tdq is 2726 * predetermined. 2727 */ 2728 static int 2729 tdq_add(struct tdq *tdq, struct thread *td, int flags) 2730 { 2731 int lowpri; 2732 2733 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2734 THREAD_LOCK_BLOCKED_ASSERT(td, MA_OWNED); 2735 KASSERT((td->td_inhibitors == 0), 2736 ("sched_add: trying to run inhibited thread")); 2737 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 2738 ("sched_add: bad thread state")); 2739 KASSERT(td->td_flags & TDF_INMEM, 2740 ("sched_add: thread swapped out")); 2741 2742 lowpri = tdq->tdq_lowpri; 2743 if (td->td_priority < lowpri) 2744 tdq->tdq_lowpri = td->td_priority; 2745 tdq_runq_add(tdq, td, flags); 2746 tdq_load_add(tdq, td); 2747 return (lowpri); 2748 } 2749 2750 /* 2751 * Select the target thread queue and add a thread to it. Request 2752 * preemption or IPI a remote processor if required. 2753 * 2754 * Requires the thread lock on entry, drops on exit. 2755 */ 2756 void 2757 sched_add(struct thread *td, int flags) 2758 { 2759 struct tdq *tdq; 2760 #ifdef SMP 2761 int cpu, lowpri; 2762 #endif 2763 2764 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 2765 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 2766 sched_tdname(curthread)); 2767 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 2768 KTR_ATTR_LINKED, sched_tdname(td)); 2769 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 2770 flags & SRQ_PREEMPTED); 2771 THREAD_LOCK_ASSERT(td, MA_OWNED); 2772 /* 2773 * Recalculate the priority before we select the target cpu or 2774 * run-queue. 2775 */ 2776 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 2777 sched_priority(td); 2778 #ifdef SMP 2779 /* 2780 * Pick the destination cpu and if it isn't ours transfer to the 2781 * target cpu. 2782 */ 2783 cpu = sched_pickcpu(td, flags); 2784 tdq = sched_setcpu(td, cpu, flags); 2785 lowpri = tdq_add(tdq, td, flags); 2786 if (cpu != PCPU_GET(cpuid)) 2787 tdq_notify(tdq, lowpri); 2788 else if (!(flags & SRQ_YIELDING)) 2789 sched_setpreempt(td->td_priority); 2790 #else 2791 tdq = TDQ_SELF(); 2792 /* 2793 * Now that the thread is moving to the run-queue, set the lock 2794 * to the scheduler's lock. 2795 */ 2796 if (td->td_lock != TDQ_LOCKPTR(tdq)) { 2797 TDQ_LOCK(tdq); 2798 if ((flags & SRQ_HOLD) != 0) 2799 td->td_lock = TDQ_LOCKPTR(tdq); 2800 else 2801 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 2802 } 2803 (void)tdq_add(tdq, td, flags); 2804 if (!(flags & SRQ_YIELDING)) 2805 sched_setpreempt(td->td_priority); 2806 #endif 2807 if (!(flags & SRQ_HOLDTD)) 2808 thread_unlock(td); 2809 } 2810 2811 /* 2812 * Remove a thread from a run-queue without running it. This is used 2813 * when we're stealing a thread from a remote queue. Otherwise all threads 2814 * exit by calling sched_exit_thread() and sched_throw() themselves. 2815 */ 2816 void 2817 sched_rem(struct thread *td) 2818 { 2819 struct tdq *tdq; 2820 2821 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "runq rem", 2822 "prio:%d", td->td_priority); 2823 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL); 2824 tdq = TDQ_CPU(td_get_sched(td)->ts_cpu); 2825 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2826 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2827 KASSERT(TD_ON_RUNQ(td), 2828 ("sched_rem: thread not on run queue")); 2829 tdq_runq_rem(tdq, td); 2830 tdq_load_rem(tdq, td); 2831 TD_SET_CAN_RUN(td); 2832 if (td->td_priority == tdq->tdq_lowpri) 2833 tdq_setlowpri(tdq, NULL); 2834 } 2835 2836 /* 2837 * Fetch cpu utilization information. Updates on demand. 2838 */ 2839 fixpt_t 2840 sched_pctcpu(struct thread *td) 2841 { 2842 fixpt_t pctcpu; 2843 struct td_sched *ts; 2844 2845 pctcpu = 0; 2846 ts = td_get_sched(td); 2847 2848 THREAD_LOCK_ASSERT(td, MA_OWNED); 2849 sched_pctcpu_update(ts, TD_IS_RUNNING(td)); 2850 if (ts->ts_ticks) { 2851 int rtick; 2852 2853 /* How many rtick per second ? */ 2854 rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz); 2855 pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT; 2856 } 2857 2858 return (pctcpu); 2859 } 2860 2861 /* 2862 * Enforce affinity settings for a thread. Called after adjustments to 2863 * cpumask. 2864 */ 2865 void 2866 sched_affinity(struct thread *td) 2867 { 2868 #ifdef SMP 2869 struct td_sched *ts; 2870 2871 THREAD_LOCK_ASSERT(td, MA_OWNED); 2872 ts = td_get_sched(td); 2873 if (THREAD_CAN_SCHED(td, ts->ts_cpu)) 2874 return; 2875 if (TD_ON_RUNQ(td)) { 2876 sched_rem(td); 2877 sched_add(td, SRQ_BORING | SRQ_HOLDTD); 2878 return; 2879 } 2880 if (!TD_IS_RUNNING(td)) 2881 return; 2882 /* 2883 * Force a switch before returning to userspace. If the 2884 * target thread is not running locally send an ipi to force 2885 * the issue. 2886 */ 2887 ast_sched_locked(td, TDA_SCHED); 2888 if (td != curthread) 2889 ipi_cpu(ts->ts_cpu, IPI_PREEMPT); 2890 #endif 2891 } 2892 2893 /* 2894 * Bind a thread to a target cpu. 2895 */ 2896 void 2897 sched_bind(struct thread *td, int cpu) 2898 { 2899 struct td_sched *ts; 2900 2901 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 2902 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 2903 ts = td_get_sched(td); 2904 if (ts->ts_flags & TSF_BOUND) 2905 sched_unbind(td); 2906 KASSERT(THREAD_CAN_MIGRATE(td), ("%p must be migratable", td)); 2907 ts->ts_flags |= TSF_BOUND; 2908 sched_pin(); 2909 if (PCPU_GET(cpuid) == cpu) 2910 return; 2911 ts->ts_cpu = cpu; 2912 /* When we return from mi_switch we'll be on the correct cpu. */ 2913 mi_switch(SW_VOL | SWT_BIND); 2914 thread_lock(td); 2915 } 2916 2917 /* 2918 * Release a bound thread. 2919 */ 2920 void 2921 sched_unbind(struct thread *td) 2922 { 2923 struct td_sched *ts; 2924 2925 THREAD_LOCK_ASSERT(td, MA_OWNED); 2926 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 2927 ts = td_get_sched(td); 2928 if ((ts->ts_flags & TSF_BOUND) == 0) 2929 return; 2930 ts->ts_flags &= ~TSF_BOUND; 2931 sched_unpin(); 2932 } 2933 2934 int 2935 sched_is_bound(struct thread *td) 2936 { 2937 THREAD_LOCK_ASSERT(td, MA_OWNED); 2938 return (td_get_sched(td)->ts_flags & TSF_BOUND); 2939 } 2940 2941 /* 2942 * Basic yield call. 2943 */ 2944 void 2945 sched_relinquish(struct thread *td) 2946 { 2947 thread_lock(td); 2948 mi_switch(SW_VOL | SWT_RELINQUISH); 2949 } 2950 2951 /* 2952 * Return the total system load. 2953 */ 2954 int 2955 sched_load(void) 2956 { 2957 #ifdef SMP 2958 int total; 2959 int i; 2960 2961 total = 0; 2962 CPU_FOREACH(i) 2963 total += atomic_load_int(&TDQ_CPU(i)->tdq_sysload); 2964 return (total); 2965 #else 2966 return (atomic_load_int(&TDQ_SELF()->tdq_sysload)); 2967 #endif 2968 } 2969 2970 int 2971 sched_sizeof_proc(void) 2972 { 2973 return (sizeof(struct proc)); 2974 } 2975 2976 int 2977 sched_sizeof_thread(void) 2978 { 2979 return (sizeof(struct thread) + sizeof(struct td_sched)); 2980 } 2981 2982 #ifdef SMP 2983 #define TDQ_IDLESPIN(tdq) \ 2984 ((tdq)->tdq_cg != NULL && ((tdq)->tdq_cg->cg_flags & CG_FLAG_THREAD) == 0) 2985 #else 2986 #define TDQ_IDLESPIN(tdq) 1 2987 #endif 2988 2989 /* 2990 * The actual idle process. 2991 */ 2992 void 2993 sched_idletd(void *dummy) 2994 { 2995 struct thread *td; 2996 struct tdq *tdq; 2997 int oldswitchcnt, switchcnt; 2998 int i; 2999 3000 mtx_assert(&Giant, MA_NOTOWNED); 3001 td = curthread; 3002 tdq = TDQ_SELF(); 3003 THREAD_NO_SLEEPING(); 3004 oldswitchcnt = -1; 3005 for (;;) { 3006 if (TDQ_LOAD(tdq)) { 3007 thread_lock(td); 3008 mi_switch(SW_VOL | SWT_IDLE); 3009 } 3010 switchcnt = TDQ_SWITCHCNT(tdq); 3011 #ifdef SMP 3012 if (always_steal || switchcnt != oldswitchcnt) { 3013 oldswitchcnt = switchcnt; 3014 if (tdq_idled(tdq) == 0) 3015 continue; 3016 } 3017 switchcnt = TDQ_SWITCHCNT(tdq); 3018 #else 3019 oldswitchcnt = switchcnt; 3020 #endif 3021 /* 3022 * If we're switching very frequently, spin while checking 3023 * for load rather than entering a low power state that 3024 * may require an IPI. However, don't do any busy 3025 * loops while on SMT machines as this simply steals 3026 * cycles from cores doing useful work. 3027 */ 3028 if (TDQ_IDLESPIN(tdq) && switchcnt > sched_idlespinthresh) { 3029 for (i = 0; i < sched_idlespins; i++) { 3030 if (TDQ_LOAD(tdq)) 3031 break; 3032 cpu_spinwait(); 3033 } 3034 } 3035 3036 /* If there was context switch during spin, restart it. */ 3037 switchcnt = TDQ_SWITCHCNT(tdq); 3038 if (TDQ_LOAD(tdq) != 0 || switchcnt != oldswitchcnt) 3039 continue; 3040 3041 /* Run main MD idle handler. */ 3042 atomic_store_int(&tdq->tdq_cpu_idle, 1); 3043 /* 3044 * Make sure that the tdq_cpu_idle update is globally visible 3045 * before cpu_idle() reads tdq_load. The order is important 3046 * to avoid races with tdq_notify(). 3047 */ 3048 atomic_thread_fence_seq_cst(); 3049 /* 3050 * Checking for again after the fence picks up assigned 3051 * threads often enough to make it worthwhile to do so in 3052 * order to avoid calling cpu_idle(). 3053 */ 3054 if (TDQ_LOAD(tdq) != 0) { 3055 atomic_store_int(&tdq->tdq_cpu_idle, 0); 3056 continue; 3057 } 3058 cpu_idle(switchcnt * 4 > sched_idlespinthresh); 3059 atomic_store_int(&tdq->tdq_cpu_idle, 0); 3060 3061 /* 3062 * Account thread-less hardware interrupts and 3063 * other wakeup reasons equal to context switches. 3064 */ 3065 switchcnt = TDQ_SWITCHCNT(tdq); 3066 if (switchcnt != oldswitchcnt) 3067 continue; 3068 TDQ_SWITCHCNT_INC(tdq); 3069 oldswitchcnt++; 3070 } 3071 } 3072 3073 /* 3074 * sched_throw_grab() chooses a thread from the queue to switch to 3075 * next. It returns with the tdq lock dropped in a spinlock section to 3076 * keep interrupts disabled until the CPU is running in a proper threaded 3077 * context. 3078 */ 3079 static struct thread * 3080 sched_throw_grab(struct tdq *tdq) 3081 { 3082 struct thread *newtd; 3083 3084 newtd = choosethread(); 3085 spinlock_enter(); 3086 TDQ_UNLOCK(tdq); 3087 KASSERT(curthread->td_md.md_spinlock_count == 1, 3088 ("invalid count %d", curthread->td_md.md_spinlock_count)); 3089 return (newtd); 3090 } 3091 3092 /* 3093 * A CPU is entering for the first time. 3094 */ 3095 void 3096 sched_ap_entry(void) 3097 { 3098 struct thread *newtd; 3099 struct tdq *tdq; 3100 3101 tdq = TDQ_SELF(); 3102 3103 /* This should have been setup in schedinit_ap(). */ 3104 THREAD_LOCKPTR_ASSERT(curthread, TDQ_LOCKPTR(tdq)); 3105 3106 TDQ_LOCK(tdq); 3107 /* Correct spinlock nesting. */ 3108 spinlock_exit(); 3109 PCPU_SET(switchtime, cpu_ticks()); 3110 PCPU_SET(switchticks, ticks); 3111 3112 newtd = sched_throw_grab(tdq); 3113 3114 /* doesn't return */ 3115 cpu_throw(NULL, newtd); 3116 } 3117 3118 /* 3119 * A thread is exiting. 3120 */ 3121 void 3122 sched_throw(struct thread *td) 3123 { 3124 struct thread *newtd; 3125 struct tdq *tdq; 3126 3127 tdq = TDQ_SELF(); 3128 3129 MPASS(td != NULL); 3130 THREAD_LOCK_ASSERT(td, MA_OWNED); 3131 THREAD_LOCKPTR_ASSERT(td, TDQ_LOCKPTR(tdq)); 3132 3133 tdq_load_rem(tdq, td); 3134 td->td_lastcpu = td->td_oncpu; 3135 td->td_oncpu = NOCPU; 3136 thread_lock_block(td); 3137 3138 newtd = sched_throw_grab(tdq); 3139 3140 /* doesn't return */ 3141 cpu_switch(td, newtd, TDQ_LOCKPTR(tdq)); 3142 } 3143 3144 /* 3145 * This is called from fork_exit(). Just acquire the correct locks and 3146 * let fork do the rest of the work. 3147 */ 3148 void 3149 sched_fork_exit(struct thread *td) 3150 { 3151 struct tdq *tdq; 3152 int cpuid; 3153 3154 /* 3155 * Finish setting up thread glue so that it begins execution in a 3156 * non-nested critical section with the scheduler lock held. 3157 */ 3158 KASSERT(curthread->td_md.md_spinlock_count == 1, 3159 ("invalid count %d", curthread->td_md.md_spinlock_count)); 3160 cpuid = PCPU_GET(cpuid); 3161 tdq = TDQ_SELF(); 3162 TDQ_LOCK(tdq); 3163 spinlock_exit(); 3164 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 3165 td->td_oncpu = cpuid; 3166 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running", 3167 "prio:%d", td->td_priority); 3168 SDT_PROBE0(sched, , , on__cpu); 3169 } 3170 3171 /* 3172 * Create on first use to catch odd startup conditions. 3173 */ 3174 char * 3175 sched_tdname(struct thread *td) 3176 { 3177 #ifdef KTR 3178 struct td_sched *ts; 3179 3180 ts = td_get_sched(td); 3181 if (ts->ts_name[0] == '\0') 3182 snprintf(ts->ts_name, sizeof(ts->ts_name), 3183 "%s tid %d", td->td_name, td->td_tid); 3184 return (ts->ts_name); 3185 #else 3186 return (td->td_name); 3187 #endif 3188 } 3189 3190 #ifdef KTR 3191 void 3192 sched_clear_tdname(struct thread *td) 3193 { 3194 struct td_sched *ts; 3195 3196 ts = td_get_sched(td); 3197 ts->ts_name[0] = '\0'; 3198 } 3199 #endif 3200 3201 #ifdef SMP 3202 3203 /* 3204 * Build the CPU topology dump string. Is recursively called to collect 3205 * the topology tree. 3206 */ 3207 static int 3208 sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, struct cpu_group *cg, 3209 int indent) 3210 { 3211 char cpusetbuf[CPUSETBUFSIZ]; 3212 int i, first; 3213 3214 sbuf_printf(sb, "%*s<group level=\"%d\" cache-level=\"%d\">\n", indent, 3215 "", 1 + indent / 2, cg->cg_level); 3216 sbuf_printf(sb, "%*s <cpu count=\"%d\" mask=\"%s\">", indent, "", 3217 cg->cg_count, cpusetobj_strprint(cpusetbuf, &cg->cg_mask)); 3218 first = TRUE; 3219 for (i = cg->cg_first; i <= cg->cg_last; i++) { 3220 if (CPU_ISSET(i, &cg->cg_mask)) { 3221 if (!first) 3222 sbuf_cat(sb, ", "); 3223 else 3224 first = FALSE; 3225 sbuf_printf(sb, "%d", i); 3226 } 3227 } 3228 sbuf_cat(sb, "</cpu>\n"); 3229 3230 if (cg->cg_flags != 0) { 3231 sbuf_printf(sb, "%*s <flags>", indent, ""); 3232 if ((cg->cg_flags & CG_FLAG_HTT) != 0) 3233 sbuf_cat(sb, "<flag name=\"HTT\">HTT group</flag>"); 3234 if ((cg->cg_flags & CG_FLAG_THREAD) != 0) 3235 sbuf_cat(sb, "<flag name=\"THREAD\">THREAD group</flag>"); 3236 if ((cg->cg_flags & CG_FLAG_SMT) != 0) 3237 sbuf_cat(sb, "<flag name=\"SMT\">SMT group</flag>"); 3238 if ((cg->cg_flags & CG_FLAG_NODE) != 0) 3239 sbuf_cat(sb, "<flag name=\"NODE\">NUMA node</flag>"); 3240 sbuf_cat(sb, "</flags>\n"); 3241 } 3242 3243 if (cg->cg_children > 0) { 3244 sbuf_printf(sb, "%*s <children>\n", indent, ""); 3245 for (i = 0; i < cg->cg_children; i++) 3246 sysctl_kern_sched_topology_spec_internal(sb, 3247 &cg->cg_child[i], indent+2); 3248 sbuf_printf(sb, "%*s </children>\n", indent, ""); 3249 } 3250 sbuf_printf(sb, "%*s</group>\n", indent, ""); 3251 return (0); 3252 } 3253 3254 /* 3255 * Sysctl handler for retrieving topology dump. It's a wrapper for 3256 * the recursive sysctl_kern_smp_topology_spec_internal(). 3257 */ 3258 static int 3259 sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS) 3260 { 3261 struct sbuf *topo; 3262 int err; 3263 3264 KASSERT(cpu_top != NULL, ("cpu_top isn't initialized")); 3265 3266 topo = sbuf_new_for_sysctl(NULL, NULL, 512, req); 3267 if (topo == NULL) 3268 return (ENOMEM); 3269 3270 sbuf_cat(topo, "<groups>\n"); 3271 err = sysctl_kern_sched_topology_spec_internal(topo, cpu_top, 1); 3272 sbuf_cat(topo, "</groups>\n"); 3273 3274 if (err == 0) { 3275 err = sbuf_finish(topo); 3276 } 3277 sbuf_delete(topo); 3278 return (err); 3279 } 3280 3281 #endif 3282 3283 static int 3284 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 3285 { 3286 int error, new_val, period; 3287 3288 period = 1000000 / realstathz; 3289 new_val = period * sched_slice; 3290 error = sysctl_handle_int(oidp, &new_val, 0, req); 3291 if (error != 0 || req->newptr == NULL) 3292 return (error); 3293 if (new_val <= 0) 3294 return (EINVAL); 3295 sched_slice = imax(1, (new_val + period / 2) / period); 3296 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 3297 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 3298 realstathz); 3299 return (0); 3300 } 3301 3302 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 3303 "Scheduler"); 3304 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0, 3305 "Scheduler name"); 3306 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, 3307 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 0, 3308 sysctl_kern_quantum, "I", 3309 "Quantum for timeshare threads in microseconds"); 3310 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, 3311 "Quantum for timeshare threads in stathz ticks"); 3312 SYSCTL_UINT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0, 3313 "Interactivity score threshold"); 3314 SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW, 3315 &preempt_thresh, 0, 3316 "Maximal (lowest) priority for preemption"); 3317 SYSCTL_INT(_kern_sched, OID_AUTO, static_boost, CTLFLAG_RW, &static_boost, 0, 3318 "Assign static kernel priorities to sleeping threads"); 3319 SYSCTL_INT(_kern_sched, OID_AUTO, idlespins, CTLFLAG_RW, &sched_idlespins, 0, 3320 "Number of times idle thread will spin waiting for new work"); 3321 SYSCTL_INT(_kern_sched, OID_AUTO, idlespinthresh, CTLFLAG_RW, 3322 &sched_idlespinthresh, 0, 3323 "Threshold before we will permit idle thread spinning"); 3324 #ifdef SMP 3325 SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0, 3326 "Number of hz ticks to keep thread affinity for"); 3327 SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0, 3328 "Enables the long-term load balancer"); 3329 SYSCTL_INT(_kern_sched, OID_AUTO, balance_interval, CTLFLAG_RW, 3330 &balance_interval, 0, 3331 "Average period in stathz ticks to run the long-term balancer"); 3332 SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0, 3333 "Attempts to steal work from other cores before idling"); 3334 SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0, 3335 "Minimum load on remote CPU before we'll steal"); 3336 SYSCTL_INT(_kern_sched, OID_AUTO, trysteal_limit, CTLFLAG_RW, &trysteal_limit, 3337 0, "Topological distance limit for stealing threads in sched_switch()"); 3338 SYSCTL_INT(_kern_sched, OID_AUTO, always_steal, CTLFLAG_RW, &always_steal, 0, 3339 "Always run the stealer from the idle thread"); 3340 SYSCTL_PROC(_kern_sched, OID_AUTO, topology_spec, CTLTYPE_STRING | 3341 CTLFLAG_MPSAFE | CTLFLAG_RD, NULL, 0, sysctl_kern_sched_topology_spec, "A", 3342 "XML dump of detected CPU topology"); 3343 #endif 3344 3345 /* ps compat. All cpu percentages from ULE are weighted. */ 3346 static int ccpu = 0; 3347 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, 3348 "Decay factor used for updating %CPU in 4BSD scheduler"); 3349