1 /*- 2 * Copyright (c) 2002-2007, Jeffrey Roberson <jeff@freebsd.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice unmodified, this list of conditions, and the following 10 * disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 /* 28 * This file implements the ULE scheduler. ULE supports independent CPU 29 * run queues and fine grain locking. It has superior interactive 30 * performance under load even on uni-processor systems. 31 * 32 * etymology: 33 * ULE is the last three letters in schedule. It owes its name to a 34 * generic user created for a scheduling system by Paul Mikesell at 35 * Isilon Systems and a general lack of creativity on the part of the author. 36 */ 37 38 #include <sys/cdefs.h> 39 __FBSDID("$FreeBSD$"); 40 41 #include "opt_hwpmc_hooks.h" 42 #include "opt_sched.h" 43 44 #include <sys/param.h> 45 #include <sys/systm.h> 46 #include <sys/kdb.h> 47 #include <sys/kernel.h> 48 #include <sys/ktr.h> 49 #include <sys/lock.h> 50 #include <sys/mutex.h> 51 #include <sys/proc.h> 52 #include <sys/resource.h> 53 #include <sys/resourcevar.h> 54 #include <sys/sched.h> 55 #include <sys/sdt.h> 56 #include <sys/smp.h> 57 #include <sys/sx.h> 58 #include <sys/sysctl.h> 59 #include <sys/sysproto.h> 60 #include <sys/turnstile.h> 61 #include <sys/umtx.h> 62 #include <sys/vmmeter.h> 63 #include <sys/cpuset.h> 64 #include <sys/sbuf.h> 65 66 #ifdef HWPMC_HOOKS 67 #include <sys/pmckern.h> 68 #endif 69 70 #ifdef KDTRACE_HOOKS 71 #include <sys/dtrace_bsd.h> 72 int dtrace_vtime_active; 73 dtrace_vtime_switch_func_t dtrace_vtime_switch_func; 74 #endif 75 76 #include <machine/cpu.h> 77 #include <machine/smp.h> 78 79 #define KTR_ULE 0 80 81 #define TS_NAME_LEN (MAXCOMLEN + sizeof(" td ") + sizeof(__XSTRING(UINT_MAX))) 82 #define TDQ_NAME_LEN (sizeof("sched lock ") + sizeof(__XSTRING(MAXCPU))) 83 #define TDQ_LOADNAME_LEN (sizeof("CPU ") + sizeof(__XSTRING(MAXCPU)) - 1 + sizeof(" load")) 84 85 /* 86 * Thread scheduler specific section. All fields are protected 87 * by the thread lock. 88 */ 89 struct td_sched { 90 struct runq *ts_runq; /* Run-queue we're queued on. */ 91 short ts_flags; /* TSF_* flags. */ 92 u_char ts_cpu; /* CPU that we have affinity for. */ 93 int ts_rltick; /* Real last tick, for affinity. */ 94 int ts_slice; /* Ticks of slice remaining. */ 95 u_int ts_slptime; /* Number of ticks we vol. slept */ 96 u_int ts_runtime; /* Number of ticks we were running */ 97 int ts_ltick; /* Last tick that we were running on */ 98 int ts_ftick; /* First tick that we were running on */ 99 int ts_ticks; /* Tick count */ 100 #ifdef KTR 101 char ts_name[TS_NAME_LEN]; 102 #endif 103 }; 104 /* flags kept in ts_flags */ 105 #define TSF_BOUND 0x0001 /* Thread can not migrate. */ 106 #define TSF_XFERABLE 0x0002 /* Thread was added as transferable. */ 107 108 static struct td_sched td_sched0; 109 110 #define THREAD_CAN_MIGRATE(td) ((td)->td_pinned == 0) 111 #define THREAD_CAN_SCHED(td, cpu) \ 112 CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask) 113 114 /* 115 * Priority ranges used for interactive and non-interactive timeshare 116 * threads. The timeshare priorities are split up into four ranges. 117 * The first range handles interactive threads. The last three ranges 118 * (NHALF, x, and NHALF) handle non-interactive threads with the outer 119 * ranges supporting nice values. 120 */ 121 #define PRI_TIMESHARE_RANGE (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE + 1) 122 #define PRI_INTERACT_RANGE ((PRI_TIMESHARE_RANGE - SCHED_PRI_NRESV) / 2) 123 #define PRI_BATCH_RANGE (PRI_TIMESHARE_RANGE - PRI_INTERACT_RANGE) 124 125 #define PRI_MIN_INTERACT PRI_MIN_TIMESHARE 126 #define PRI_MAX_INTERACT (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE - 1) 127 #define PRI_MIN_BATCH (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE) 128 #define PRI_MAX_BATCH PRI_MAX_TIMESHARE 129 130 /* 131 * Cpu percentage computation macros and defines. 132 * 133 * SCHED_TICK_SECS: Number of seconds to average the cpu usage across. 134 * SCHED_TICK_TARG: Number of hz ticks to average the cpu usage across. 135 * SCHED_TICK_MAX: Maximum number of ticks before scaling back. 136 * SCHED_TICK_SHIFT: Shift factor to avoid rounding away results. 137 * SCHED_TICK_HZ: Compute the number of hz ticks for a given ticks count. 138 * SCHED_TICK_TOTAL: Gives the amount of time we've been recording ticks. 139 */ 140 #define SCHED_TICK_SECS 10 141 #define SCHED_TICK_TARG (hz * SCHED_TICK_SECS) 142 #define SCHED_TICK_MAX (SCHED_TICK_TARG + hz) 143 #define SCHED_TICK_SHIFT 10 144 #define SCHED_TICK_HZ(ts) ((ts)->ts_ticks >> SCHED_TICK_SHIFT) 145 #define SCHED_TICK_TOTAL(ts) (max((ts)->ts_ltick - (ts)->ts_ftick, hz)) 146 147 /* 148 * These macros determine priorities for non-interactive threads. They are 149 * assigned a priority based on their recent cpu utilization as expressed 150 * by the ratio of ticks to the tick total. NHALF priorities at the start 151 * and end of the MIN to MAX timeshare range are only reachable with negative 152 * or positive nice respectively. 153 * 154 * PRI_RANGE: Priority range for utilization dependent priorities. 155 * PRI_NRESV: Number of nice values. 156 * PRI_TICKS: Compute a priority in PRI_RANGE from the ticks count and total. 157 * PRI_NICE: Determines the part of the priority inherited from nice. 158 */ 159 #define SCHED_PRI_NRESV (PRIO_MAX - PRIO_MIN) 160 #define SCHED_PRI_NHALF (SCHED_PRI_NRESV / 2) 161 #define SCHED_PRI_MIN (PRI_MIN_BATCH + SCHED_PRI_NHALF) 162 #define SCHED_PRI_MAX (PRI_MAX_BATCH - SCHED_PRI_NHALF) 163 #define SCHED_PRI_RANGE (SCHED_PRI_MAX - SCHED_PRI_MIN + 1) 164 #define SCHED_PRI_TICKS(ts) \ 165 (SCHED_TICK_HZ((ts)) / \ 166 (roundup(SCHED_TICK_TOTAL((ts)), SCHED_PRI_RANGE) / SCHED_PRI_RANGE)) 167 #define SCHED_PRI_NICE(nice) (nice) 168 169 /* 170 * These determine the interactivity of a process. Interactivity differs from 171 * cpu utilization in that it expresses the voluntary time slept vs time ran 172 * while cpu utilization includes all time not running. This more accurately 173 * models the intent of the thread. 174 * 175 * SLP_RUN_MAX: Maximum amount of sleep time + run time we'll accumulate 176 * before throttling back. 177 * SLP_RUN_FORK: Maximum slp+run time to inherit at fork time. 178 * INTERACT_MAX: Maximum interactivity value. Smaller is better. 179 * INTERACT_THRESH: Threshold for placement on the current runq. 180 */ 181 #define SCHED_SLP_RUN_MAX ((hz * 5) << SCHED_TICK_SHIFT) 182 #define SCHED_SLP_RUN_FORK ((hz / 2) << SCHED_TICK_SHIFT) 183 #define SCHED_INTERACT_MAX (100) 184 #define SCHED_INTERACT_HALF (SCHED_INTERACT_MAX / 2) 185 #define SCHED_INTERACT_THRESH (30) 186 187 /* 188 * These parameters determine the slice behavior for batch work. 189 */ 190 #define SCHED_SLICE_DEFAULT_DIVISOR 10 /* ~94 ms, 12 stathz ticks. */ 191 #define SCHED_SLICE_MIN_DIVISOR 6 /* DEFAULT/MIN = ~16 ms. */ 192 193 /* Flags kept in td_flags. */ 194 #define TDF_SLICEEND TDF_SCHED2 /* Thread time slice is over. */ 195 196 /* 197 * tickincr: Converts a stathz tick into a hz domain scaled by 198 * the shift factor. Without the shift the error rate 199 * due to rounding would be unacceptably high. 200 * realstathz: stathz is sometimes 0 and run off of hz. 201 * sched_slice: Runtime of each thread before rescheduling. 202 * preempt_thresh: Priority threshold for preemption and remote IPIs. 203 */ 204 static int sched_interact = SCHED_INTERACT_THRESH; 205 static int tickincr = 8 << SCHED_TICK_SHIFT; 206 static int realstathz = 127; /* reset during boot. */ 207 static int sched_slice = 10; /* reset during boot. */ 208 static int sched_slice_min = 1; /* reset during boot. */ 209 #ifdef PREEMPTION 210 #ifdef FULL_PREEMPTION 211 static int preempt_thresh = PRI_MAX_IDLE; 212 #else 213 static int preempt_thresh = PRI_MIN_KERN; 214 #endif 215 #else 216 static int preempt_thresh = 0; 217 #endif 218 static int static_boost = PRI_MIN_BATCH; 219 static int sched_idlespins = 10000; 220 static int sched_idlespinthresh = -1; 221 222 /* 223 * tdq - per processor runqs and statistics. All fields are protected by the 224 * tdq_lock. The load and lowpri may be accessed without to avoid excess 225 * locking in sched_pickcpu(); 226 */ 227 struct tdq { 228 /* 229 * Ordered to improve efficiency of cpu_search() and switch(). 230 * tdq_lock is padded to avoid false sharing with tdq_load and 231 * tdq_cpu_idle. 232 */ 233 struct mtx_padalign tdq_lock; /* run queue lock. */ 234 struct cpu_group *tdq_cg; /* Pointer to cpu topology. */ 235 volatile int tdq_load; /* Aggregate load. */ 236 volatile int tdq_cpu_idle; /* cpu_idle() is active. */ 237 int tdq_sysload; /* For loadavg, !ITHD load. */ 238 int tdq_transferable; /* Transferable thread count. */ 239 short tdq_switchcnt; /* Switches this tick. */ 240 short tdq_oldswitchcnt; /* Switches last tick. */ 241 u_char tdq_lowpri; /* Lowest priority thread. */ 242 u_char tdq_ipipending; /* IPI pending. */ 243 u_char tdq_idx; /* Current insert index. */ 244 u_char tdq_ridx; /* Current removal index. */ 245 struct runq tdq_realtime; /* real-time run queue. */ 246 struct runq tdq_timeshare; /* timeshare run queue. */ 247 struct runq tdq_idle; /* Queue of IDLE threads. */ 248 char tdq_name[TDQ_NAME_LEN]; 249 #ifdef KTR 250 char tdq_loadname[TDQ_LOADNAME_LEN]; 251 #endif 252 } __aligned(64); 253 254 /* Idle thread states and config. */ 255 #define TDQ_RUNNING 1 256 #define TDQ_IDLE 2 257 258 #ifdef SMP 259 struct cpu_group *cpu_top; /* CPU topology */ 260 261 #define SCHED_AFFINITY_DEFAULT (max(1, hz / 1000)) 262 #define SCHED_AFFINITY(ts, t) ((ts)->ts_rltick > ticks - ((t) * affinity)) 263 264 /* 265 * Run-time tunables. 266 */ 267 static int rebalance = 1; 268 static int balance_interval = 128; /* Default set in sched_initticks(). */ 269 static int affinity; 270 static int steal_idle = 1; 271 static int steal_thresh = 2; 272 273 /* 274 * One thread queue per processor. 275 */ 276 static struct tdq tdq_cpu[MAXCPU]; 277 static struct tdq *balance_tdq; 278 static int balance_ticks; 279 static DPCPU_DEFINE(uint32_t, randomval); 280 281 #define TDQ_SELF() (&tdq_cpu[PCPU_GET(cpuid)]) 282 #define TDQ_CPU(x) (&tdq_cpu[(x)]) 283 #define TDQ_ID(x) ((int)((x) - tdq_cpu)) 284 #else /* !SMP */ 285 static struct tdq tdq_cpu; 286 287 #define TDQ_ID(x) (0) 288 #define TDQ_SELF() (&tdq_cpu) 289 #define TDQ_CPU(x) (&tdq_cpu) 290 #endif 291 292 #define TDQ_LOCK_ASSERT(t, type) mtx_assert(TDQ_LOCKPTR((t)), (type)) 293 #define TDQ_LOCK(t) mtx_lock_spin(TDQ_LOCKPTR((t))) 294 #define TDQ_LOCK_FLAGS(t, f) mtx_lock_spin_flags(TDQ_LOCKPTR((t)), (f)) 295 #define TDQ_UNLOCK(t) mtx_unlock_spin(TDQ_LOCKPTR((t))) 296 #define TDQ_LOCKPTR(t) ((struct mtx *)(&(t)->tdq_lock)) 297 298 static void sched_priority(struct thread *); 299 static void sched_thread_priority(struct thread *, u_char); 300 static int sched_interact_score(struct thread *); 301 static void sched_interact_update(struct thread *); 302 static void sched_interact_fork(struct thread *); 303 static void sched_pctcpu_update(struct td_sched *, int); 304 305 /* Operations on per processor queues */ 306 static struct thread *tdq_choose(struct tdq *); 307 static void tdq_setup(struct tdq *); 308 static void tdq_load_add(struct tdq *, struct thread *); 309 static void tdq_load_rem(struct tdq *, struct thread *); 310 static __inline void tdq_runq_add(struct tdq *, struct thread *, int); 311 static __inline void tdq_runq_rem(struct tdq *, struct thread *); 312 static inline int sched_shouldpreempt(int, int, int); 313 void tdq_print(int cpu); 314 static void runq_print(struct runq *rq); 315 static void tdq_add(struct tdq *, struct thread *, int); 316 #ifdef SMP 317 static int tdq_move(struct tdq *, struct tdq *); 318 static int tdq_idled(struct tdq *); 319 static void tdq_notify(struct tdq *, struct thread *); 320 static struct thread *tdq_steal(struct tdq *, int); 321 static struct thread *runq_steal(struct runq *, int); 322 static int sched_pickcpu(struct thread *, int); 323 static void sched_balance(void); 324 static int sched_balance_pair(struct tdq *, struct tdq *); 325 static inline struct tdq *sched_setcpu(struct thread *, int, int); 326 static inline void thread_unblock_switch(struct thread *, struct mtx *); 327 static struct mtx *sched_switch_migrate(struct tdq *, struct thread *, int); 328 static int sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS); 329 static int sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, 330 struct cpu_group *cg, int indent); 331 #endif 332 333 static void sched_setup(void *dummy); 334 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL); 335 336 static void sched_initticks(void *dummy); 337 SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks, 338 NULL); 339 340 SDT_PROVIDER_DEFINE(sched); 341 342 SDT_PROBE_DEFINE3(sched, , , change__pri, "struct thread *", 343 "struct proc *", "uint8_t"); 344 SDT_PROBE_DEFINE3(sched, , , dequeue, "struct thread *", 345 "struct proc *", "void *"); 346 SDT_PROBE_DEFINE4(sched, , , enqueue, "struct thread *", 347 "struct proc *", "void *", "int"); 348 SDT_PROBE_DEFINE4(sched, , , lend__pri, "struct thread *", 349 "struct proc *", "uint8_t", "struct thread *"); 350 SDT_PROBE_DEFINE2(sched, , , load__change, "int", "int"); 351 SDT_PROBE_DEFINE2(sched, , , off__cpu, "struct thread *", 352 "struct proc *"); 353 SDT_PROBE_DEFINE(sched, , , on__cpu); 354 SDT_PROBE_DEFINE(sched, , , remain__cpu); 355 SDT_PROBE_DEFINE2(sched, , , surrender, "struct thread *", 356 "struct proc *"); 357 358 /* 359 * Print the threads waiting on a run-queue. 360 */ 361 static void 362 runq_print(struct runq *rq) 363 { 364 struct rqhead *rqh; 365 struct thread *td; 366 int pri; 367 int j; 368 int i; 369 370 for (i = 0; i < RQB_LEN; i++) { 371 printf("\t\trunq bits %d 0x%zx\n", 372 i, rq->rq_status.rqb_bits[i]); 373 for (j = 0; j < RQB_BPW; j++) 374 if (rq->rq_status.rqb_bits[i] & (1ul << j)) { 375 pri = j + (i << RQB_L2BPW); 376 rqh = &rq->rq_queues[pri]; 377 TAILQ_FOREACH(td, rqh, td_runq) { 378 printf("\t\t\ttd %p(%s) priority %d rqindex %d pri %d\n", 379 td, td->td_name, td->td_priority, 380 td->td_rqindex, pri); 381 } 382 } 383 } 384 } 385 386 /* 387 * Print the status of a per-cpu thread queue. Should be a ddb show cmd. 388 */ 389 void 390 tdq_print(int cpu) 391 { 392 struct tdq *tdq; 393 394 tdq = TDQ_CPU(cpu); 395 396 printf("tdq %d:\n", TDQ_ID(tdq)); 397 printf("\tlock %p\n", TDQ_LOCKPTR(tdq)); 398 printf("\tLock name: %s\n", tdq->tdq_name); 399 printf("\tload: %d\n", tdq->tdq_load); 400 printf("\tswitch cnt: %d\n", tdq->tdq_switchcnt); 401 printf("\told switch cnt: %d\n", tdq->tdq_oldswitchcnt); 402 printf("\ttimeshare idx: %d\n", tdq->tdq_idx); 403 printf("\ttimeshare ridx: %d\n", tdq->tdq_ridx); 404 printf("\tload transferable: %d\n", tdq->tdq_transferable); 405 printf("\tlowest priority: %d\n", tdq->tdq_lowpri); 406 printf("\trealtime runq:\n"); 407 runq_print(&tdq->tdq_realtime); 408 printf("\ttimeshare runq:\n"); 409 runq_print(&tdq->tdq_timeshare); 410 printf("\tidle runq:\n"); 411 runq_print(&tdq->tdq_idle); 412 } 413 414 static inline int 415 sched_shouldpreempt(int pri, int cpri, int remote) 416 { 417 /* 418 * If the new priority is not better than the current priority there is 419 * nothing to do. 420 */ 421 if (pri >= cpri) 422 return (0); 423 /* 424 * Always preempt idle. 425 */ 426 if (cpri >= PRI_MIN_IDLE) 427 return (1); 428 /* 429 * If preemption is disabled don't preempt others. 430 */ 431 if (preempt_thresh == 0) 432 return (0); 433 /* 434 * Preempt if we exceed the threshold. 435 */ 436 if (pri <= preempt_thresh) 437 return (1); 438 /* 439 * If we're interactive or better and there is non-interactive 440 * or worse running preempt only remote processors. 441 */ 442 if (remote && pri <= PRI_MAX_INTERACT && cpri > PRI_MAX_INTERACT) 443 return (1); 444 return (0); 445 } 446 447 /* 448 * Add a thread to the actual run-queue. Keeps transferable counts up to 449 * date with what is actually on the run-queue. Selects the correct 450 * queue position for timeshare threads. 451 */ 452 static __inline void 453 tdq_runq_add(struct tdq *tdq, struct thread *td, int flags) 454 { 455 struct td_sched *ts; 456 u_char pri; 457 458 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 459 THREAD_LOCK_ASSERT(td, MA_OWNED); 460 461 pri = td->td_priority; 462 ts = td->td_sched; 463 TD_SET_RUNQ(td); 464 if (THREAD_CAN_MIGRATE(td)) { 465 tdq->tdq_transferable++; 466 ts->ts_flags |= TSF_XFERABLE; 467 } 468 if (pri < PRI_MIN_BATCH) { 469 ts->ts_runq = &tdq->tdq_realtime; 470 } else if (pri <= PRI_MAX_BATCH) { 471 ts->ts_runq = &tdq->tdq_timeshare; 472 KASSERT(pri <= PRI_MAX_BATCH && pri >= PRI_MIN_BATCH, 473 ("Invalid priority %d on timeshare runq", pri)); 474 /* 475 * This queue contains only priorities between MIN and MAX 476 * realtime. Use the whole queue to represent these values. 477 */ 478 if ((flags & (SRQ_BORROWING|SRQ_PREEMPTED)) == 0) { 479 pri = RQ_NQS * (pri - PRI_MIN_BATCH) / PRI_BATCH_RANGE; 480 pri = (pri + tdq->tdq_idx) % RQ_NQS; 481 /* 482 * This effectively shortens the queue by one so we 483 * can have a one slot difference between idx and 484 * ridx while we wait for threads to drain. 485 */ 486 if (tdq->tdq_ridx != tdq->tdq_idx && 487 pri == tdq->tdq_ridx) 488 pri = (unsigned char)(pri - 1) % RQ_NQS; 489 } else 490 pri = tdq->tdq_ridx; 491 runq_add_pri(ts->ts_runq, td, pri, flags); 492 return; 493 } else 494 ts->ts_runq = &tdq->tdq_idle; 495 runq_add(ts->ts_runq, td, flags); 496 } 497 498 /* 499 * Remove a thread from a run-queue. This typically happens when a thread 500 * is selected to run. Running threads are not on the queue and the 501 * transferable count does not reflect them. 502 */ 503 static __inline void 504 tdq_runq_rem(struct tdq *tdq, struct thread *td) 505 { 506 struct td_sched *ts; 507 508 ts = td->td_sched; 509 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 510 KASSERT(ts->ts_runq != NULL, 511 ("tdq_runq_remove: thread %p null ts_runq", td)); 512 if (ts->ts_flags & TSF_XFERABLE) { 513 tdq->tdq_transferable--; 514 ts->ts_flags &= ~TSF_XFERABLE; 515 } 516 if (ts->ts_runq == &tdq->tdq_timeshare) { 517 if (tdq->tdq_idx != tdq->tdq_ridx) 518 runq_remove_idx(ts->ts_runq, td, &tdq->tdq_ridx); 519 else 520 runq_remove_idx(ts->ts_runq, td, NULL); 521 } else 522 runq_remove(ts->ts_runq, td); 523 } 524 525 /* 526 * Load is maintained for all threads RUNNING and ON_RUNQ. Add the load 527 * for this thread to the referenced thread queue. 528 */ 529 static void 530 tdq_load_add(struct tdq *tdq, struct thread *td) 531 { 532 533 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 534 THREAD_LOCK_ASSERT(td, MA_OWNED); 535 536 tdq->tdq_load++; 537 if ((td->td_flags & TDF_NOLOAD) == 0) 538 tdq->tdq_sysload++; 539 KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load); 540 SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load); 541 } 542 543 /* 544 * Remove the load from a thread that is transitioning to a sleep state or 545 * exiting. 546 */ 547 static void 548 tdq_load_rem(struct tdq *tdq, struct thread *td) 549 { 550 551 THREAD_LOCK_ASSERT(td, MA_OWNED); 552 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 553 KASSERT(tdq->tdq_load != 0, 554 ("tdq_load_rem: Removing with 0 load on queue %d", TDQ_ID(tdq))); 555 556 tdq->tdq_load--; 557 if ((td->td_flags & TDF_NOLOAD) == 0) 558 tdq->tdq_sysload--; 559 KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load); 560 SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load); 561 } 562 563 /* 564 * Bound timeshare latency by decreasing slice size as load increases. We 565 * consider the maximum latency as the sum of the threads waiting to run 566 * aside from curthread and target no more than sched_slice latency but 567 * no less than sched_slice_min runtime. 568 */ 569 static inline int 570 tdq_slice(struct tdq *tdq) 571 { 572 int load; 573 574 /* 575 * It is safe to use sys_load here because this is called from 576 * contexts where timeshare threads are running and so there 577 * cannot be higher priority load in the system. 578 */ 579 load = tdq->tdq_sysload - 1; 580 if (load >= SCHED_SLICE_MIN_DIVISOR) 581 return (sched_slice_min); 582 if (load <= 1) 583 return (sched_slice); 584 return (sched_slice / load); 585 } 586 587 /* 588 * Set lowpri to its exact value by searching the run-queue and 589 * evaluating curthread. curthread may be passed as an optimization. 590 */ 591 static void 592 tdq_setlowpri(struct tdq *tdq, struct thread *ctd) 593 { 594 struct thread *td; 595 596 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 597 if (ctd == NULL) 598 ctd = pcpu_find(TDQ_ID(tdq))->pc_curthread; 599 td = tdq_choose(tdq); 600 if (td == NULL || td->td_priority > ctd->td_priority) 601 tdq->tdq_lowpri = ctd->td_priority; 602 else 603 tdq->tdq_lowpri = td->td_priority; 604 } 605 606 #ifdef SMP 607 struct cpu_search { 608 cpuset_t cs_mask; 609 u_int cs_prefer; 610 int cs_pri; /* Min priority for low. */ 611 int cs_limit; /* Max load for low, min load for high. */ 612 int cs_cpu; 613 int cs_load; 614 }; 615 616 #define CPU_SEARCH_LOWEST 0x1 617 #define CPU_SEARCH_HIGHEST 0x2 618 #define CPU_SEARCH_BOTH (CPU_SEARCH_LOWEST|CPU_SEARCH_HIGHEST) 619 620 #define CPUSET_FOREACH(cpu, mask) \ 621 for ((cpu) = 0; (cpu) <= mp_maxid; (cpu)++) \ 622 if (CPU_ISSET(cpu, &mask)) 623 624 static __inline int cpu_search(const struct cpu_group *cg, struct cpu_search *low, 625 struct cpu_search *high, const int match); 626 int cpu_search_lowest(const struct cpu_group *cg, struct cpu_search *low); 627 int cpu_search_highest(const struct cpu_group *cg, struct cpu_search *high); 628 int cpu_search_both(const struct cpu_group *cg, struct cpu_search *low, 629 struct cpu_search *high); 630 631 /* 632 * Search the tree of cpu_groups for the lowest or highest loaded cpu 633 * according to the match argument. This routine actually compares the 634 * load on all paths through the tree and finds the least loaded cpu on 635 * the least loaded path, which may differ from the least loaded cpu in 636 * the system. This balances work among caches and busses. 637 * 638 * This inline is instantiated in three forms below using constants for the 639 * match argument. It is reduced to the minimum set for each case. It is 640 * also recursive to the depth of the tree. 641 */ 642 static __inline int 643 cpu_search(const struct cpu_group *cg, struct cpu_search *low, 644 struct cpu_search *high, const int match) 645 { 646 struct cpu_search lgroup; 647 struct cpu_search hgroup; 648 cpuset_t cpumask; 649 struct cpu_group *child; 650 struct tdq *tdq; 651 int cpu, i, hload, lload, load, total, rnd, *rndptr; 652 653 total = 0; 654 cpumask = cg->cg_mask; 655 if (match & CPU_SEARCH_LOWEST) { 656 lload = INT_MAX; 657 lgroup = *low; 658 } 659 if (match & CPU_SEARCH_HIGHEST) { 660 hload = INT_MIN; 661 hgroup = *high; 662 } 663 664 /* Iterate through the child CPU groups and then remaining CPUs. */ 665 for (i = cg->cg_children, cpu = mp_maxid; ; ) { 666 if (i == 0) { 667 #ifdef HAVE_INLINE_FFSL 668 cpu = CPU_FFS(&cpumask) - 1; 669 #else 670 while (cpu >= 0 && !CPU_ISSET(cpu, &cpumask)) 671 cpu--; 672 #endif 673 if (cpu < 0) 674 break; 675 child = NULL; 676 } else 677 child = &cg->cg_child[i - 1]; 678 679 if (match & CPU_SEARCH_LOWEST) 680 lgroup.cs_cpu = -1; 681 if (match & CPU_SEARCH_HIGHEST) 682 hgroup.cs_cpu = -1; 683 if (child) { /* Handle child CPU group. */ 684 CPU_NAND(&cpumask, &child->cg_mask); 685 switch (match) { 686 case CPU_SEARCH_LOWEST: 687 load = cpu_search_lowest(child, &lgroup); 688 break; 689 case CPU_SEARCH_HIGHEST: 690 load = cpu_search_highest(child, &hgroup); 691 break; 692 case CPU_SEARCH_BOTH: 693 load = cpu_search_both(child, &lgroup, &hgroup); 694 break; 695 } 696 } else { /* Handle child CPU. */ 697 CPU_CLR(cpu, &cpumask); 698 tdq = TDQ_CPU(cpu); 699 load = tdq->tdq_load * 256; 700 rndptr = DPCPU_PTR(randomval); 701 rnd = (*rndptr = *rndptr * 69069 + 5) >> 26; 702 if (match & CPU_SEARCH_LOWEST) { 703 if (cpu == low->cs_prefer) 704 load -= 64; 705 /* If that CPU is allowed and get data. */ 706 if (tdq->tdq_lowpri > lgroup.cs_pri && 707 tdq->tdq_load <= lgroup.cs_limit && 708 CPU_ISSET(cpu, &lgroup.cs_mask)) { 709 lgroup.cs_cpu = cpu; 710 lgroup.cs_load = load - rnd; 711 } 712 } 713 if (match & CPU_SEARCH_HIGHEST) 714 if (tdq->tdq_load >= hgroup.cs_limit && 715 tdq->tdq_transferable && 716 CPU_ISSET(cpu, &hgroup.cs_mask)) { 717 hgroup.cs_cpu = cpu; 718 hgroup.cs_load = load - rnd; 719 } 720 } 721 total += load; 722 723 /* We have info about child item. Compare it. */ 724 if (match & CPU_SEARCH_LOWEST) { 725 if (lgroup.cs_cpu >= 0 && 726 (load < lload || 727 (load == lload && lgroup.cs_load < low->cs_load))) { 728 lload = load; 729 low->cs_cpu = lgroup.cs_cpu; 730 low->cs_load = lgroup.cs_load; 731 } 732 } 733 if (match & CPU_SEARCH_HIGHEST) 734 if (hgroup.cs_cpu >= 0 && 735 (load > hload || 736 (load == hload && hgroup.cs_load > high->cs_load))) { 737 hload = load; 738 high->cs_cpu = hgroup.cs_cpu; 739 high->cs_load = hgroup.cs_load; 740 } 741 if (child) { 742 i--; 743 if (i == 0 && CPU_EMPTY(&cpumask)) 744 break; 745 } 746 #ifndef HAVE_INLINE_FFSL 747 else 748 cpu--; 749 #endif 750 } 751 return (total); 752 } 753 754 /* 755 * cpu_search instantiations must pass constants to maintain the inline 756 * optimization. 757 */ 758 int 759 cpu_search_lowest(const struct cpu_group *cg, struct cpu_search *low) 760 { 761 return cpu_search(cg, low, NULL, CPU_SEARCH_LOWEST); 762 } 763 764 int 765 cpu_search_highest(const struct cpu_group *cg, struct cpu_search *high) 766 { 767 return cpu_search(cg, NULL, high, CPU_SEARCH_HIGHEST); 768 } 769 770 int 771 cpu_search_both(const struct cpu_group *cg, struct cpu_search *low, 772 struct cpu_search *high) 773 { 774 return cpu_search(cg, low, high, CPU_SEARCH_BOTH); 775 } 776 777 /* 778 * Find the cpu with the least load via the least loaded path that has a 779 * lowpri greater than pri pri. A pri of -1 indicates any priority is 780 * acceptable. 781 */ 782 static inline int 783 sched_lowest(const struct cpu_group *cg, cpuset_t mask, int pri, int maxload, 784 int prefer) 785 { 786 struct cpu_search low; 787 788 low.cs_cpu = -1; 789 low.cs_prefer = prefer; 790 low.cs_mask = mask; 791 low.cs_pri = pri; 792 low.cs_limit = maxload; 793 cpu_search_lowest(cg, &low); 794 return low.cs_cpu; 795 } 796 797 /* 798 * Find the cpu with the highest load via the highest loaded path. 799 */ 800 static inline int 801 sched_highest(const struct cpu_group *cg, cpuset_t mask, int minload) 802 { 803 struct cpu_search high; 804 805 high.cs_cpu = -1; 806 high.cs_mask = mask; 807 high.cs_limit = minload; 808 cpu_search_highest(cg, &high); 809 return high.cs_cpu; 810 } 811 812 static void 813 sched_balance_group(struct cpu_group *cg) 814 { 815 cpuset_t hmask, lmask; 816 int high, low, anylow; 817 818 CPU_FILL(&hmask); 819 for (;;) { 820 high = sched_highest(cg, hmask, 1); 821 /* Stop if there is no more CPU with transferrable threads. */ 822 if (high == -1) 823 break; 824 CPU_CLR(high, &hmask); 825 CPU_COPY(&hmask, &lmask); 826 /* Stop if there is no more CPU left for low. */ 827 if (CPU_EMPTY(&lmask)) 828 break; 829 anylow = 1; 830 nextlow: 831 low = sched_lowest(cg, lmask, -1, 832 TDQ_CPU(high)->tdq_load - 1, high); 833 /* Stop if we looked well and found no less loaded CPU. */ 834 if (anylow && low == -1) 835 break; 836 /* Go to next high if we found no less loaded CPU. */ 837 if (low == -1) 838 continue; 839 /* Transfer thread from high to low. */ 840 if (sched_balance_pair(TDQ_CPU(high), TDQ_CPU(low))) { 841 /* CPU that got thread can no longer be a donor. */ 842 CPU_CLR(low, &hmask); 843 } else { 844 /* 845 * If failed, then there is no threads on high 846 * that can run on this low. Drop low from low 847 * mask and look for different one. 848 */ 849 CPU_CLR(low, &lmask); 850 anylow = 0; 851 goto nextlow; 852 } 853 } 854 } 855 856 static void 857 sched_balance(void) 858 { 859 struct tdq *tdq; 860 861 /* 862 * Select a random time between .5 * balance_interval and 863 * 1.5 * balance_interval. 864 */ 865 balance_ticks = max(balance_interval / 2, 1); 866 balance_ticks += random() % balance_interval; 867 if (smp_started == 0 || rebalance == 0) 868 return; 869 tdq = TDQ_SELF(); 870 TDQ_UNLOCK(tdq); 871 sched_balance_group(cpu_top); 872 TDQ_LOCK(tdq); 873 } 874 875 /* 876 * Lock two thread queues using their address to maintain lock order. 877 */ 878 static void 879 tdq_lock_pair(struct tdq *one, struct tdq *two) 880 { 881 if (one < two) { 882 TDQ_LOCK(one); 883 TDQ_LOCK_FLAGS(two, MTX_DUPOK); 884 } else { 885 TDQ_LOCK(two); 886 TDQ_LOCK_FLAGS(one, MTX_DUPOK); 887 } 888 } 889 890 /* 891 * Unlock two thread queues. Order is not important here. 892 */ 893 static void 894 tdq_unlock_pair(struct tdq *one, struct tdq *two) 895 { 896 TDQ_UNLOCK(one); 897 TDQ_UNLOCK(two); 898 } 899 900 /* 901 * Transfer load between two imbalanced thread queues. 902 */ 903 static int 904 sched_balance_pair(struct tdq *high, struct tdq *low) 905 { 906 int moved; 907 int cpu; 908 909 tdq_lock_pair(high, low); 910 moved = 0; 911 /* 912 * Determine what the imbalance is and then adjust that to how many 913 * threads we actually have to give up (transferable). 914 */ 915 if (high->tdq_transferable != 0 && high->tdq_load > low->tdq_load && 916 (moved = tdq_move(high, low)) > 0) { 917 /* 918 * In case the target isn't the current cpu IPI it to force a 919 * reschedule with the new workload. 920 */ 921 cpu = TDQ_ID(low); 922 if (cpu != PCPU_GET(cpuid)) 923 ipi_cpu(cpu, IPI_PREEMPT); 924 } 925 tdq_unlock_pair(high, low); 926 return (moved); 927 } 928 929 /* 930 * Move a thread from one thread queue to another. 931 */ 932 static int 933 tdq_move(struct tdq *from, struct tdq *to) 934 { 935 struct td_sched *ts; 936 struct thread *td; 937 struct tdq *tdq; 938 int cpu; 939 940 TDQ_LOCK_ASSERT(from, MA_OWNED); 941 TDQ_LOCK_ASSERT(to, MA_OWNED); 942 943 tdq = from; 944 cpu = TDQ_ID(to); 945 td = tdq_steal(tdq, cpu); 946 if (td == NULL) 947 return (0); 948 ts = td->td_sched; 949 /* 950 * Although the run queue is locked the thread may be blocked. Lock 951 * it to clear this and acquire the run-queue lock. 952 */ 953 thread_lock(td); 954 /* Drop recursive lock on from acquired via thread_lock(). */ 955 TDQ_UNLOCK(from); 956 sched_rem(td); 957 ts->ts_cpu = cpu; 958 td->td_lock = TDQ_LOCKPTR(to); 959 tdq_add(to, td, SRQ_YIELDING); 960 return (1); 961 } 962 963 /* 964 * This tdq has idled. Try to steal a thread from another cpu and switch 965 * to it. 966 */ 967 static int 968 tdq_idled(struct tdq *tdq) 969 { 970 struct cpu_group *cg; 971 struct tdq *steal; 972 cpuset_t mask; 973 int thresh; 974 int cpu; 975 976 if (smp_started == 0 || steal_idle == 0) 977 return (1); 978 CPU_FILL(&mask); 979 CPU_CLR(PCPU_GET(cpuid), &mask); 980 /* We don't want to be preempted while we're iterating. */ 981 spinlock_enter(); 982 for (cg = tdq->tdq_cg; cg != NULL; ) { 983 if ((cg->cg_flags & CG_FLAG_THREAD) == 0) 984 thresh = steal_thresh; 985 else 986 thresh = 1; 987 cpu = sched_highest(cg, mask, thresh); 988 if (cpu == -1) { 989 cg = cg->cg_parent; 990 continue; 991 } 992 steal = TDQ_CPU(cpu); 993 CPU_CLR(cpu, &mask); 994 tdq_lock_pair(tdq, steal); 995 if (steal->tdq_load < thresh || steal->tdq_transferable == 0) { 996 tdq_unlock_pair(tdq, steal); 997 continue; 998 } 999 /* 1000 * If a thread was added while interrupts were disabled don't 1001 * steal one here. If we fail to acquire one due to affinity 1002 * restrictions loop again with this cpu removed from the 1003 * set. 1004 */ 1005 if (tdq->tdq_load == 0 && tdq_move(steal, tdq) == 0) { 1006 tdq_unlock_pair(tdq, steal); 1007 continue; 1008 } 1009 spinlock_exit(); 1010 TDQ_UNLOCK(steal); 1011 mi_switch(SW_VOL | SWT_IDLE, NULL); 1012 thread_unlock(curthread); 1013 1014 return (0); 1015 } 1016 spinlock_exit(); 1017 return (1); 1018 } 1019 1020 /* 1021 * Notify a remote cpu of new work. Sends an IPI if criteria are met. 1022 */ 1023 static void 1024 tdq_notify(struct tdq *tdq, struct thread *td) 1025 { 1026 struct thread *ctd; 1027 int pri; 1028 int cpu; 1029 1030 if (tdq->tdq_ipipending) 1031 return; 1032 cpu = td->td_sched->ts_cpu; 1033 pri = td->td_priority; 1034 ctd = pcpu_find(cpu)->pc_curthread; 1035 if (!sched_shouldpreempt(pri, ctd->td_priority, 1)) 1036 return; 1037 if (TD_IS_IDLETHREAD(ctd)) { 1038 /* 1039 * If the MD code has an idle wakeup routine try that before 1040 * falling back to IPI. 1041 */ 1042 if (!tdq->tdq_cpu_idle || cpu_idle_wakeup(cpu)) 1043 return; 1044 } 1045 tdq->tdq_ipipending = 1; 1046 ipi_cpu(cpu, IPI_PREEMPT); 1047 } 1048 1049 /* 1050 * Steals load from a timeshare queue. Honors the rotating queue head 1051 * index. 1052 */ 1053 static struct thread * 1054 runq_steal_from(struct runq *rq, int cpu, u_char start) 1055 { 1056 struct rqbits *rqb; 1057 struct rqhead *rqh; 1058 struct thread *td, *first; 1059 int bit; 1060 int i; 1061 1062 rqb = &rq->rq_status; 1063 bit = start & (RQB_BPW -1); 1064 first = NULL; 1065 again: 1066 for (i = RQB_WORD(start); i < RQB_LEN; bit = 0, i++) { 1067 if (rqb->rqb_bits[i] == 0) 1068 continue; 1069 if (bit == 0) 1070 bit = RQB_FFS(rqb->rqb_bits[i]); 1071 for (; bit < RQB_BPW; bit++) { 1072 if ((rqb->rqb_bits[i] & (1ul << bit)) == 0) 1073 continue; 1074 rqh = &rq->rq_queues[bit + (i << RQB_L2BPW)]; 1075 TAILQ_FOREACH(td, rqh, td_runq) { 1076 if (first && THREAD_CAN_MIGRATE(td) && 1077 THREAD_CAN_SCHED(td, cpu)) 1078 return (td); 1079 first = td; 1080 } 1081 } 1082 } 1083 if (start != 0) { 1084 start = 0; 1085 goto again; 1086 } 1087 1088 if (first && THREAD_CAN_MIGRATE(first) && 1089 THREAD_CAN_SCHED(first, cpu)) 1090 return (first); 1091 return (NULL); 1092 } 1093 1094 /* 1095 * Steals load from a standard linear queue. 1096 */ 1097 static struct thread * 1098 runq_steal(struct runq *rq, int cpu) 1099 { 1100 struct rqhead *rqh; 1101 struct rqbits *rqb; 1102 struct thread *td; 1103 int word; 1104 int bit; 1105 1106 rqb = &rq->rq_status; 1107 for (word = 0; word < RQB_LEN; word++) { 1108 if (rqb->rqb_bits[word] == 0) 1109 continue; 1110 for (bit = 0; bit < RQB_BPW; bit++) { 1111 if ((rqb->rqb_bits[word] & (1ul << bit)) == 0) 1112 continue; 1113 rqh = &rq->rq_queues[bit + (word << RQB_L2BPW)]; 1114 TAILQ_FOREACH(td, rqh, td_runq) 1115 if (THREAD_CAN_MIGRATE(td) && 1116 THREAD_CAN_SCHED(td, cpu)) 1117 return (td); 1118 } 1119 } 1120 return (NULL); 1121 } 1122 1123 /* 1124 * Attempt to steal a thread in priority order from a thread queue. 1125 */ 1126 static struct thread * 1127 tdq_steal(struct tdq *tdq, int cpu) 1128 { 1129 struct thread *td; 1130 1131 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1132 if ((td = runq_steal(&tdq->tdq_realtime, cpu)) != NULL) 1133 return (td); 1134 if ((td = runq_steal_from(&tdq->tdq_timeshare, 1135 cpu, tdq->tdq_ridx)) != NULL) 1136 return (td); 1137 return (runq_steal(&tdq->tdq_idle, cpu)); 1138 } 1139 1140 /* 1141 * Sets the thread lock and ts_cpu to match the requested cpu. Unlocks the 1142 * current lock and returns with the assigned queue locked. 1143 */ 1144 static inline struct tdq * 1145 sched_setcpu(struct thread *td, int cpu, int flags) 1146 { 1147 1148 struct tdq *tdq; 1149 1150 THREAD_LOCK_ASSERT(td, MA_OWNED); 1151 tdq = TDQ_CPU(cpu); 1152 td->td_sched->ts_cpu = cpu; 1153 /* 1154 * If the lock matches just return the queue. 1155 */ 1156 if (td->td_lock == TDQ_LOCKPTR(tdq)) 1157 return (tdq); 1158 #ifdef notyet 1159 /* 1160 * If the thread isn't running its lockptr is a 1161 * turnstile or a sleepqueue. We can just lock_set without 1162 * blocking. 1163 */ 1164 if (TD_CAN_RUN(td)) { 1165 TDQ_LOCK(tdq); 1166 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 1167 return (tdq); 1168 } 1169 #endif 1170 /* 1171 * The hard case, migration, we need to block the thread first to 1172 * prevent order reversals with other cpus locks. 1173 */ 1174 spinlock_enter(); 1175 thread_lock_block(td); 1176 TDQ_LOCK(tdq); 1177 thread_lock_unblock(td, TDQ_LOCKPTR(tdq)); 1178 spinlock_exit(); 1179 return (tdq); 1180 } 1181 1182 SCHED_STAT_DEFINE(pickcpu_intrbind, "Soft interrupt binding"); 1183 SCHED_STAT_DEFINE(pickcpu_idle_affinity, "Picked idle cpu based on affinity"); 1184 SCHED_STAT_DEFINE(pickcpu_affinity, "Picked cpu based on affinity"); 1185 SCHED_STAT_DEFINE(pickcpu_lowest, "Selected lowest load"); 1186 SCHED_STAT_DEFINE(pickcpu_local, "Migrated to current cpu"); 1187 SCHED_STAT_DEFINE(pickcpu_migration, "Selection may have caused migration"); 1188 1189 static int 1190 sched_pickcpu(struct thread *td, int flags) 1191 { 1192 struct cpu_group *cg, *ccg; 1193 struct td_sched *ts; 1194 struct tdq *tdq; 1195 cpuset_t mask; 1196 int cpu, pri, self; 1197 1198 self = PCPU_GET(cpuid); 1199 ts = td->td_sched; 1200 if (smp_started == 0) 1201 return (self); 1202 /* 1203 * Don't migrate a running thread from sched_switch(). 1204 */ 1205 if ((flags & SRQ_OURSELF) || !THREAD_CAN_MIGRATE(td)) 1206 return (ts->ts_cpu); 1207 /* 1208 * Prefer to run interrupt threads on the processors that generate 1209 * the interrupt. 1210 */ 1211 pri = td->td_priority; 1212 if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_SCHED(td, self) && 1213 curthread->td_intr_nesting_level && ts->ts_cpu != self) { 1214 SCHED_STAT_INC(pickcpu_intrbind); 1215 ts->ts_cpu = self; 1216 if (TDQ_CPU(self)->tdq_lowpri > pri) { 1217 SCHED_STAT_INC(pickcpu_affinity); 1218 return (ts->ts_cpu); 1219 } 1220 } 1221 /* 1222 * If the thread can run on the last cpu and the affinity has not 1223 * expired or it is idle run it there. 1224 */ 1225 tdq = TDQ_CPU(ts->ts_cpu); 1226 cg = tdq->tdq_cg; 1227 if (THREAD_CAN_SCHED(td, ts->ts_cpu) && 1228 tdq->tdq_lowpri >= PRI_MIN_IDLE && 1229 SCHED_AFFINITY(ts, CG_SHARE_L2)) { 1230 if (cg->cg_flags & CG_FLAG_THREAD) { 1231 CPUSET_FOREACH(cpu, cg->cg_mask) { 1232 if (TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE) 1233 break; 1234 } 1235 } else 1236 cpu = INT_MAX; 1237 if (cpu > mp_maxid) { 1238 SCHED_STAT_INC(pickcpu_idle_affinity); 1239 return (ts->ts_cpu); 1240 } 1241 } 1242 /* 1243 * Search for the last level cache CPU group in the tree. 1244 * Skip caches with expired affinity time and SMT groups. 1245 * Affinity to higher level caches will be handled less aggressively. 1246 */ 1247 for (ccg = NULL; cg != NULL; cg = cg->cg_parent) { 1248 if (cg->cg_flags & CG_FLAG_THREAD) 1249 continue; 1250 if (!SCHED_AFFINITY(ts, cg->cg_level)) 1251 continue; 1252 ccg = cg; 1253 } 1254 if (ccg != NULL) 1255 cg = ccg; 1256 cpu = -1; 1257 /* Search the group for the less loaded idle CPU we can run now. */ 1258 mask = td->td_cpuset->cs_mask; 1259 if (cg != NULL && cg != cpu_top && 1260 CPU_CMP(&cg->cg_mask, &cpu_top->cg_mask) != 0) 1261 cpu = sched_lowest(cg, mask, max(pri, PRI_MAX_TIMESHARE), 1262 INT_MAX, ts->ts_cpu); 1263 /* Search globally for the less loaded CPU we can run now. */ 1264 if (cpu == -1) 1265 cpu = sched_lowest(cpu_top, mask, pri, INT_MAX, ts->ts_cpu); 1266 /* Search globally for the less loaded CPU. */ 1267 if (cpu == -1) 1268 cpu = sched_lowest(cpu_top, mask, -1, INT_MAX, ts->ts_cpu); 1269 KASSERT(cpu != -1, ("sched_pickcpu: Failed to find a cpu.")); 1270 /* 1271 * Compare the lowest loaded cpu to current cpu. 1272 */ 1273 if (THREAD_CAN_SCHED(td, self) && TDQ_CPU(self)->tdq_lowpri > pri && 1274 TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE && 1275 TDQ_CPU(self)->tdq_load <= TDQ_CPU(cpu)->tdq_load + 1) { 1276 SCHED_STAT_INC(pickcpu_local); 1277 cpu = self; 1278 } else 1279 SCHED_STAT_INC(pickcpu_lowest); 1280 if (cpu != ts->ts_cpu) 1281 SCHED_STAT_INC(pickcpu_migration); 1282 return (cpu); 1283 } 1284 #endif 1285 1286 /* 1287 * Pick the highest priority task we have and return it. 1288 */ 1289 static struct thread * 1290 tdq_choose(struct tdq *tdq) 1291 { 1292 struct thread *td; 1293 1294 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1295 td = runq_choose(&tdq->tdq_realtime); 1296 if (td != NULL) 1297 return (td); 1298 td = runq_choose_from(&tdq->tdq_timeshare, tdq->tdq_ridx); 1299 if (td != NULL) { 1300 KASSERT(td->td_priority >= PRI_MIN_BATCH, 1301 ("tdq_choose: Invalid priority on timeshare queue %d", 1302 td->td_priority)); 1303 return (td); 1304 } 1305 td = runq_choose(&tdq->tdq_idle); 1306 if (td != NULL) { 1307 KASSERT(td->td_priority >= PRI_MIN_IDLE, 1308 ("tdq_choose: Invalid priority on idle queue %d", 1309 td->td_priority)); 1310 return (td); 1311 } 1312 1313 return (NULL); 1314 } 1315 1316 /* 1317 * Initialize a thread queue. 1318 */ 1319 static void 1320 tdq_setup(struct tdq *tdq) 1321 { 1322 1323 if (bootverbose) 1324 printf("ULE: setup cpu %d\n", TDQ_ID(tdq)); 1325 runq_init(&tdq->tdq_realtime); 1326 runq_init(&tdq->tdq_timeshare); 1327 runq_init(&tdq->tdq_idle); 1328 snprintf(tdq->tdq_name, sizeof(tdq->tdq_name), 1329 "sched lock %d", (int)TDQ_ID(tdq)); 1330 mtx_init(&tdq->tdq_lock, tdq->tdq_name, "sched lock", 1331 MTX_SPIN | MTX_RECURSE); 1332 #ifdef KTR 1333 snprintf(tdq->tdq_loadname, sizeof(tdq->tdq_loadname), 1334 "CPU %d load", (int)TDQ_ID(tdq)); 1335 #endif 1336 } 1337 1338 #ifdef SMP 1339 static void 1340 sched_setup_smp(void) 1341 { 1342 struct tdq *tdq; 1343 int i; 1344 1345 cpu_top = smp_topo(); 1346 CPU_FOREACH(i) { 1347 tdq = TDQ_CPU(i); 1348 tdq_setup(tdq); 1349 tdq->tdq_cg = smp_topo_find(cpu_top, i); 1350 if (tdq->tdq_cg == NULL) 1351 panic("Can't find cpu group for %d\n", i); 1352 } 1353 balance_tdq = TDQ_SELF(); 1354 sched_balance(); 1355 } 1356 #endif 1357 1358 /* 1359 * Setup the thread queues and initialize the topology based on MD 1360 * information. 1361 */ 1362 static void 1363 sched_setup(void *dummy) 1364 { 1365 struct tdq *tdq; 1366 1367 tdq = TDQ_SELF(); 1368 #ifdef SMP 1369 sched_setup_smp(); 1370 #else 1371 tdq_setup(tdq); 1372 #endif 1373 1374 /* Add thread0's load since it's running. */ 1375 TDQ_LOCK(tdq); 1376 thread0.td_lock = TDQ_LOCKPTR(TDQ_SELF()); 1377 tdq_load_add(tdq, &thread0); 1378 tdq->tdq_lowpri = thread0.td_priority; 1379 TDQ_UNLOCK(tdq); 1380 } 1381 1382 /* 1383 * This routine determines time constants after stathz and hz are setup. 1384 */ 1385 /* ARGSUSED */ 1386 static void 1387 sched_initticks(void *dummy) 1388 { 1389 int incr; 1390 1391 realstathz = stathz ? stathz : hz; 1392 sched_slice = realstathz / SCHED_SLICE_DEFAULT_DIVISOR; 1393 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 1394 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 1395 realstathz); 1396 1397 /* 1398 * tickincr is shifted out by 10 to avoid rounding errors due to 1399 * hz not being evenly divisible by stathz on all platforms. 1400 */ 1401 incr = (hz << SCHED_TICK_SHIFT) / realstathz; 1402 /* 1403 * This does not work for values of stathz that are more than 1404 * 1 << SCHED_TICK_SHIFT * hz. In practice this does not happen. 1405 */ 1406 if (incr == 0) 1407 incr = 1; 1408 tickincr = incr; 1409 #ifdef SMP 1410 /* 1411 * Set the default balance interval now that we know 1412 * what realstathz is. 1413 */ 1414 balance_interval = realstathz; 1415 affinity = SCHED_AFFINITY_DEFAULT; 1416 #endif 1417 if (sched_idlespinthresh < 0) 1418 sched_idlespinthresh = 2 * max(10000, 6 * hz) / realstathz; 1419 } 1420 1421 1422 /* 1423 * This is the core of the interactivity algorithm. Determines a score based 1424 * on past behavior. It is the ratio of sleep time to run time scaled to 1425 * a [0, 100] integer. This is the voluntary sleep time of a process, which 1426 * differs from the cpu usage because it does not account for time spent 1427 * waiting on a run-queue. Would be prettier if we had floating point. 1428 */ 1429 static int 1430 sched_interact_score(struct thread *td) 1431 { 1432 struct td_sched *ts; 1433 int div; 1434 1435 ts = td->td_sched; 1436 /* 1437 * The score is only needed if this is likely to be an interactive 1438 * task. Don't go through the expense of computing it if there's 1439 * no chance. 1440 */ 1441 if (sched_interact <= SCHED_INTERACT_HALF && 1442 ts->ts_runtime >= ts->ts_slptime) 1443 return (SCHED_INTERACT_HALF); 1444 1445 if (ts->ts_runtime > ts->ts_slptime) { 1446 div = max(1, ts->ts_runtime / SCHED_INTERACT_HALF); 1447 return (SCHED_INTERACT_HALF + 1448 (SCHED_INTERACT_HALF - (ts->ts_slptime / div))); 1449 } 1450 if (ts->ts_slptime > ts->ts_runtime) { 1451 div = max(1, ts->ts_slptime / SCHED_INTERACT_HALF); 1452 return (ts->ts_runtime / div); 1453 } 1454 /* runtime == slptime */ 1455 if (ts->ts_runtime) 1456 return (SCHED_INTERACT_HALF); 1457 1458 /* 1459 * This can happen if slptime and runtime are 0. 1460 */ 1461 return (0); 1462 1463 } 1464 1465 /* 1466 * Scale the scheduling priority according to the "interactivity" of this 1467 * process. 1468 */ 1469 static void 1470 sched_priority(struct thread *td) 1471 { 1472 int score; 1473 int pri; 1474 1475 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 1476 return; 1477 /* 1478 * If the score is interactive we place the thread in the realtime 1479 * queue with a priority that is less than kernel and interrupt 1480 * priorities. These threads are not subject to nice restrictions. 1481 * 1482 * Scores greater than this are placed on the normal timeshare queue 1483 * where the priority is partially decided by the most recent cpu 1484 * utilization and the rest is decided by nice value. 1485 * 1486 * The nice value of the process has a linear effect on the calculated 1487 * score. Negative nice values make it easier for a thread to be 1488 * considered interactive. 1489 */ 1490 score = imax(0, sched_interact_score(td) + td->td_proc->p_nice); 1491 if (score < sched_interact) { 1492 pri = PRI_MIN_INTERACT; 1493 pri += ((PRI_MAX_INTERACT - PRI_MIN_INTERACT + 1) / 1494 sched_interact) * score; 1495 KASSERT(pri >= PRI_MIN_INTERACT && pri <= PRI_MAX_INTERACT, 1496 ("sched_priority: invalid interactive priority %d score %d", 1497 pri, score)); 1498 } else { 1499 pri = SCHED_PRI_MIN; 1500 if (td->td_sched->ts_ticks) 1501 pri += min(SCHED_PRI_TICKS(td->td_sched), 1502 SCHED_PRI_RANGE - 1); 1503 pri += SCHED_PRI_NICE(td->td_proc->p_nice); 1504 KASSERT(pri >= PRI_MIN_BATCH && pri <= PRI_MAX_BATCH, 1505 ("sched_priority: invalid priority %d: nice %d, " 1506 "ticks %d ftick %d ltick %d tick pri %d", 1507 pri, td->td_proc->p_nice, td->td_sched->ts_ticks, 1508 td->td_sched->ts_ftick, td->td_sched->ts_ltick, 1509 SCHED_PRI_TICKS(td->td_sched))); 1510 } 1511 sched_user_prio(td, pri); 1512 1513 return; 1514 } 1515 1516 /* 1517 * This routine enforces a maximum limit on the amount of scheduling history 1518 * kept. It is called after either the slptime or runtime is adjusted. This 1519 * function is ugly due to integer math. 1520 */ 1521 static void 1522 sched_interact_update(struct thread *td) 1523 { 1524 struct td_sched *ts; 1525 u_int sum; 1526 1527 ts = td->td_sched; 1528 sum = ts->ts_runtime + ts->ts_slptime; 1529 if (sum < SCHED_SLP_RUN_MAX) 1530 return; 1531 /* 1532 * This only happens from two places: 1533 * 1) We have added an unusual amount of run time from fork_exit. 1534 * 2) We have added an unusual amount of sleep time from sched_sleep(). 1535 */ 1536 if (sum > SCHED_SLP_RUN_MAX * 2) { 1537 if (ts->ts_runtime > ts->ts_slptime) { 1538 ts->ts_runtime = SCHED_SLP_RUN_MAX; 1539 ts->ts_slptime = 1; 1540 } else { 1541 ts->ts_slptime = SCHED_SLP_RUN_MAX; 1542 ts->ts_runtime = 1; 1543 } 1544 return; 1545 } 1546 /* 1547 * If we have exceeded by more than 1/5th then the algorithm below 1548 * will not bring us back into range. Dividing by two here forces 1549 * us into the range of [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX] 1550 */ 1551 if (sum > (SCHED_SLP_RUN_MAX / 5) * 6) { 1552 ts->ts_runtime /= 2; 1553 ts->ts_slptime /= 2; 1554 return; 1555 } 1556 ts->ts_runtime = (ts->ts_runtime / 5) * 4; 1557 ts->ts_slptime = (ts->ts_slptime / 5) * 4; 1558 } 1559 1560 /* 1561 * Scale back the interactivity history when a child thread is created. The 1562 * history is inherited from the parent but the thread may behave totally 1563 * differently. For example, a shell spawning a compiler process. We want 1564 * to learn that the compiler is behaving badly very quickly. 1565 */ 1566 static void 1567 sched_interact_fork(struct thread *td) 1568 { 1569 int ratio; 1570 int sum; 1571 1572 sum = td->td_sched->ts_runtime + td->td_sched->ts_slptime; 1573 if (sum > SCHED_SLP_RUN_FORK) { 1574 ratio = sum / SCHED_SLP_RUN_FORK; 1575 td->td_sched->ts_runtime /= ratio; 1576 td->td_sched->ts_slptime /= ratio; 1577 } 1578 } 1579 1580 /* 1581 * Called from proc0_init() to setup the scheduler fields. 1582 */ 1583 void 1584 schedinit(void) 1585 { 1586 1587 /* 1588 * Set up the scheduler specific parts of proc0. 1589 */ 1590 proc0.p_sched = NULL; /* XXX */ 1591 thread0.td_sched = &td_sched0; 1592 td_sched0.ts_ltick = ticks; 1593 td_sched0.ts_ftick = ticks; 1594 td_sched0.ts_slice = 0; 1595 } 1596 1597 /* 1598 * This is only somewhat accurate since given many processes of the same 1599 * priority they will switch when their slices run out, which will be 1600 * at most sched_slice stathz ticks. 1601 */ 1602 int 1603 sched_rr_interval(void) 1604 { 1605 1606 /* Convert sched_slice from stathz to hz. */ 1607 return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz)); 1608 } 1609 1610 /* 1611 * Update the percent cpu tracking information when it is requested or 1612 * the total history exceeds the maximum. We keep a sliding history of 1613 * tick counts that slowly decays. This is less precise than the 4BSD 1614 * mechanism since it happens with less regular and frequent events. 1615 */ 1616 static void 1617 sched_pctcpu_update(struct td_sched *ts, int run) 1618 { 1619 int t = ticks; 1620 1621 if (t - ts->ts_ltick >= SCHED_TICK_TARG) { 1622 ts->ts_ticks = 0; 1623 ts->ts_ftick = t - SCHED_TICK_TARG; 1624 } else if (t - ts->ts_ftick >= SCHED_TICK_MAX) { 1625 ts->ts_ticks = (ts->ts_ticks / (ts->ts_ltick - ts->ts_ftick)) * 1626 (ts->ts_ltick - (t - SCHED_TICK_TARG)); 1627 ts->ts_ftick = t - SCHED_TICK_TARG; 1628 } 1629 if (run) 1630 ts->ts_ticks += (t - ts->ts_ltick) << SCHED_TICK_SHIFT; 1631 ts->ts_ltick = t; 1632 } 1633 1634 /* 1635 * Adjust the priority of a thread. Move it to the appropriate run-queue 1636 * if necessary. This is the back-end for several priority related 1637 * functions. 1638 */ 1639 static void 1640 sched_thread_priority(struct thread *td, u_char prio) 1641 { 1642 struct td_sched *ts; 1643 struct tdq *tdq; 1644 int oldpri; 1645 1646 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "prio", 1647 "prio:%d", td->td_priority, "new prio:%d", prio, 1648 KTR_ATTR_LINKED, sched_tdname(curthread)); 1649 SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio); 1650 if (td != curthread && prio < td->td_priority) { 1651 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread), 1652 "lend prio", "prio:%d", td->td_priority, "new prio:%d", 1653 prio, KTR_ATTR_LINKED, sched_tdname(td)); 1654 SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio, 1655 curthread); 1656 } 1657 ts = td->td_sched; 1658 THREAD_LOCK_ASSERT(td, MA_OWNED); 1659 if (td->td_priority == prio) 1660 return; 1661 /* 1662 * If the priority has been elevated due to priority 1663 * propagation, we may have to move ourselves to a new 1664 * queue. This could be optimized to not re-add in some 1665 * cases. 1666 */ 1667 if (TD_ON_RUNQ(td) && prio < td->td_priority) { 1668 sched_rem(td); 1669 td->td_priority = prio; 1670 sched_add(td, SRQ_BORROWING); 1671 return; 1672 } 1673 /* 1674 * If the thread is currently running we may have to adjust the lowpri 1675 * information so other cpus are aware of our current priority. 1676 */ 1677 if (TD_IS_RUNNING(td)) { 1678 tdq = TDQ_CPU(ts->ts_cpu); 1679 oldpri = td->td_priority; 1680 td->td_priority = prio; 1681 if (prio < tdq->tdq_lowpri) 1682 tdq->tdq_lowpri = prio; 1683 else if (tdq->tdq_lowpri == oldpri) 1684 tdq_setlowpri(tdq, td); 1685 return; 1686 } 1687 td->td_priority = prio; 1688 } 1689 1690 /* 1691 * Update a thread's priority when it is lent another thread's 1692 * priority. 1693 */ 1694 void 1695 sched_lend_prio(struct thread *td, u_char prio) 1696 { 1697 1698 td->td_flags |= TDF_BORROWING; 1699 sched_thread_priority(td, prio); 1700 } 1701 1702 /* 1703 * Restore a thread's priority when priority propagation is 1704 * over. The prio argument is the minimum priority the thread 1705 * needs to have to satisfy other possible priority lending 1706 * requests. If the thread's regular priority is less 1707 * important than prio, the thread will keep a priority boost 1708 * of prio. 1709 */ 1710 void 1711 sched_unlend_prio(struct thread *td, u_char prio) 1712 { 1713 u_char base_pri; 1714 1715 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 1716 td->td_base_pri <= PRI_MAX_TIMESHARE) 1717 base_pri = td->td_user_pri; 1718 else 1719 base_pri = td->td_base_pri; 1720 if (prio >= base_pri) { 1721 td->td_flags &= ~TDF_BORROWING; 1722 sched_thread_priority(td, base_pri); 1723 } else 1724 sched_lend_prio(td, prio); 1725 } 1726 1727 /* 1728 * Standard entry for setting the priority to an absolute value. 1729 */ 1730 void 1731 sched_prio(struct thread *td, u_char prio) 1732 { 1733 u_char oldprio; 1734 1735 /* First, update the base priority. */ 1736 td->td_base_pri = prio; 1737 1738 /* 1739 * If the thread is borrowing another thread's priority, don't 1740 * ever lower the priority. 1741 */ 1742 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 1743 return; 1744 1745 /* Change the real priority. */ 1746 oldprio = td->td_priority; 1747 sched_thread_priority(td, prio); 1748 1749 /* 1750 * If the thread is on a turnstile, then let the turnstile update 1751 * its state. 1752 */ 1753 if (TD_ON_LOCK(td) && oldprio != prio) 1754 turnstile_adjust(td, oldprio); 1755 } 1756 1757 /* 1758 * Set the base user priority, does not effect current running priority. 1759 */ 1760 void 1761 sched_user_prio(struct thread *td, u_char prio) 1762 { 1763 1764 td->td_base_user_pri = prio; 1765 if (td->td_lend_user_pri <= prio) 1766 return; 1767 td->td_user_pri = prio; 1768 } 1769 1770 void 1771 sched_lend_user_prio(struct thread *td, u_char prio) 1772 { 1773 1774 THREAD_LOCK_ASSERT(td, MA_OWNED); 1775 td->td_lend_user_pri = prio; 1776 td->td_user_pri = min(prio, td->td_base_user_pri); 1777 if (td->td_priority > td->td_user_pri) 1778 sched_prio(td, td->td_user_pri); 1779 else if (td->td_priority != td->td_user_pri) 1780 td->td_flags |= TDF_NEEDRESCHED; 1781 } 1782 1783 /* 1784 * Handle migration from sched_switch(). This happens only for 1785 * cpu binding. 1786 */ 1787 static struct mtx * 1788 sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags) 1789 { 1790 struct tdq *tdn; 1791 1792 tdn = TDQ_CPU(td->td_sched->ts_cpu); 1793 #ifdef SMP 1794 tdq_load_rem(tdq, td); 1795 /* 1796 * Do the lock dance required to avoid LOR. We grab an extra 1797 * spinlock nesting to prevent preemption while we're 1798 * not holding either run-queue lock. 1799 */ 1800 spinlock_enter(); 1801 thread_lock_block(td); /* This releases the lock on tdq. */ 1802 1803 /* 1804 * Acquire both run-queue locks before placing the thread on the new 1805 * run-queue to avoid deadlocks created by placing a thread with a 1806 * blocked lock on the run-queue of a remote processor. The deadlock 1807 * occurs when a third processor attempts to lock the two queues in 1808 * question while the target processor is spinning with its own 1809 * run-queue lock held while waiting for the blocked lock to clear. 1810 */ 1811 tdq_lock_pair(tdn, tdq); 1812 tdq_add(tdn, td, flags); 1813 tdq_notify(tdn, td); 1814 TDQ_UNLOCK(tdn); 1815 spinlock_exit(); 1816 #endif 1817 return (TDQ_LOCKPTR(tdn)); 1818 } 1819 1820 /* 1821 * Variadic version of thread_lock_unblock() that does not assume td_lock 1822 * is blocked. 1823 */ 1824 static inline void 1825 thread_unblock_switch(struct thread *td, struct mtx *mtx) 1826 { 1827 atomic_store_rel_ptr((volatile uintptr_t *)&td->td_lock, 1828 (uintptr_t)mtx); 1829 } 1830 1831 /* 1832 * Switch threads. This function has to handle threads coming in while 1833 * blocked for some reason, running, or idle. It also must deal with 1834 * migrating a thread from one queue to another as running threads may 1835 * be assigned elsewhere via binding. 1836 */ 1837 void 1838 sched_switch(struct thread *td, struct thread *newtd, int flags) 1839 { 1840 struct tdq *tdq; 1841 struct td_sched *ts; 1842 struct mtx *mtx; 1843 int srqflag; 1844 int cpuid, preempted; 1845 1846 THREAD_LOCK_ASSERT(td, MA_OWNED); 1847 KASSERT(newtd == NULL, ("sched_switch: Unsupported newtd argument")); 1848 1849 cpuid = PCPU_GET(cpuid); 1850 tdq = TDQ_CPU(cpuid); 1851 ts = td->td_sched; 1852 mtx = td->td_lock; 1853 sched_pctcpu_update(ts, 1); 1854 ts->ts_rltick = ticks; 1855 td->td_lastcpu = td->td_oncpu; 1856 td->td_oncpu = NOCPU; 1857 preempted = !(td->td_flags & TDF_SLICEEND); 1858 td->td_flags &= ~(TDF_NEEDRESCHED | TDF_SLICEEND); 1859 td->td_owepreempt = 0; 1860 if (!TD_IS_IDLETHREAD(td)) 1861 tdq->tdq_switchcnt++; 1862 /* 1863 * The lock pointer in an idle thread should never change. Reset it 1864 * to CAN_RUN as well. 1865 */ 1866 if (TD_IS_IDLETHREAD(td)) { 1867 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1868 TD_SET_CAN_RUN(td); 1869 } else if (TD_IS_RUNNING(td)) { 1870 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1871 srqflag = preempted ? 1872 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 1873 SRQ_OURSELF|SRQ_YIELDING; 1874 #ifdef SMP 1875 if (THREAD_CAN_MIGRATE(td) && !THREAD_CAN_SCHED(td, ts->ts_cpu)) 1876 ts->ts_cpu = sched_pickcpu(td, 0); 1877 #endif 1878 if (ts->ts_cpu == cpuid) 1879 tdq_runq_add(tdq, td, srqflag); 1880 else { 1881 KASSERT(THREAD_CAN_MIGRATE(td) || 1882 (ts->ts_flags & TSF_BOUND) != 0, 1883 ("Thread %p shouldn't migrate", td)); 1884 mtx = sched_switch_migrate(tdq, td, srqflag); 1885 } 1886 } else { 1887 /* This thread must be going to sleep. */ 1888 TDQ_LOCK(tdq); 1889 mtx = thread_lock_block(td); 1890 tdq_load_rem(tdq, td); 1891 } 1892 /* 1893 * We enter here with the thread blocked and assigned to the 1894 * appropriate cpu run-queue or sleep-queue and with the current 1895 * thread-queue locked. 1896 */ 1897 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 1898 newtd = choosethread(); 1899 /* 1900 * Call the MD code to switch contexts if necessary. 1901 */ 1902 if (td != newtd) { 1903 #ifdef HWPMC_HOOKS 1904 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1905 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 1906 #endif 1907 SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc); 1908 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 1909 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 1910 sched_pctcpu_update(newtd->td_sched, 0); 1911 1912 #ifdef KDTRACE_HOOKS 1913 /* 1914 * If DTrace has set the active vtime enum to anything 1915 * other than INACTIVE (0), then it should have set the 1916 * function to call. 1917 */ 1918 if (dtrace_vtime_active) 1919 (*dtrace_vtime_switch_func)(newtd); 1920 #endif 1921 1922 cpu_switch(td, newtd, mtx); 1923 /* 1924 * We may return from cpu_switch on a different cpu. However, 1925 * we always return with td_lock pointing to the current cpu's 1926 * run queue lock. 1927 */ 1928 cpuid = PCPU_GET(cpuid); 1929 tdq = TDQ_CPU(cpuid); 1930 lock_profile_obtain_lock_success( 1931 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 1932 1933 SDT_PROBE0(sched, , , on__cpu); 1934 #ifdef HWPMC_HOOKS 1935 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1936 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 1937 #endif 1938 } else { 1939 thread_unblock_switch(td, mtx); 1940 SDT_PROBE0(sched, , , remain__cpu); 1941 } 1942 /* 1943 * Assert that all went well and return. 1944 */ 1945 TDQ_LOCK_ASSERT(tdq, MA_OWNED|MA_NOTRECURSED); 1946 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1947 td->td_oncpu = cpuid; 1948 } 1949 1950 /* 1951 * Adjust thread priorities as a result of a nice request. 1952 */ 1953 void 1954 sched_nice(struct proc *p, int nice) 1955 { 1956 struct thread *td; 1957 1958 PROC_LOCK_ASSERT(p, MA_OWNED); 1959 1960 p->p_nice = nice; 1961 FOREACH_THREAD_IN_PROC(p, td) { 1962 thread_lock(td); 1963 sched_priority(td); 1964 sched_prio(td, td->td_base_user_pri); 1965 thread_unlock(td); 1966 } 1967 } 1968 1969 /* 1970 * Record the sleep time for the interactivity scorer. 1971 */ 1972 void 1973 sched_sleep(struct thread *td, int prio) 1974 { 1975 1976 THREAD_LOCK_ASSERT(td, MA_OWNED); 1977 1978 td->td_slptick = ticks; 1979 if (TD_IS_SUSPENDED(td) || prio >= PSOCK) 1980 td->td_flags |= TDF_CANSWAP; 1981 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 1982 return; 1983 if (static_boost == 1 && prio) 1984 sched_prio(td, prio); 1985 else if (static_boost && td->td_priority > static_boost) 1986 sched_prio(td, static_boost); 1987 } 1988 1989 /* 1990 * Schedule a thread to resume execution and record how long it voluntarily 1991 * slept. We also update the pctcpu, interactivity, and priority. 1992 */ 1993 void 1994 sched_wakeup(struct thread *td) 1995 { 1996 struct td_sched *ts; 1997 int slptick; 1998 1999 THREAD_LOCK_ASSERT(td, MA_OWNED); 2000 ts = td->td_sched; 2001 td->td_flags &= ~TDF_CANSWAP; 2002 /* 2003 * If we slept for more than a tick update our interactivity and 2004 * priority. 2005 */ 2006 slptick = td->td_slptick; 2007 td->td_slptick = 0; 2008 if (slptick && slptick != ticks) { 2009 ts->ts_slptime += (ticks - slptick) << SCHED_TICK_SHIFT; 2010 sched_interact_update(td); 2011 sched_pctcpu_update(ts, 0); 2012 } 2013 /* 2014 * Reset the slice value since we slept and advanced the round-robin. 2015 */ 2016 ts->ts_slice = 0; 2017 sched_add(td, SRQ_BORING); 2018 } 2019 2020 /* 2021 * Penalize the parent for creating a new child and initialize the child's 2022 * priority. 2023 */ 2024 void 2025 sched_fork(struct thread *td, struct thread *child) 2026 { 2027 THREAD_LOCK_ASSERT(td, MA_OWNED); 2028 sched_pctcpu_update(td->td_sched, 1); 2029 sched_fork_thread(td, child); 2030 /* 2031 * Penalize the parent and child for forking. 2032 */ 2033 sched_interact_fork(child); 2034 sched_priority(child); 2035 td->td_sched->ts_runtime += tickincr; 2036 sched_interact_update(td); 2037 sched_priority(td); 2038 } 2039 2040 /* 2041 * Fork a new thread, may be within the same process. 2042 */ 2043 void 2044 sched_fork_thread(struct thread *td, struct thread *child) 2045 { 2046 struct td_sched *ts; 2047 struct td_sched *ts2; 2048 struct tdq *tdq; 2049 2050 tdq = TDQ_SELF(); 2051 THREAD_LOCK_ASSERT(td, MA_OWNED); 2052 /* 2053 * Initialize child. 2054 */ 2055 ts = td->td_sched; 2056 ts2 = child->td_sched; 2057 child->td_lock = TDQ_LOCKPTR(tdq); 2058 child->td_cpuset = cpuset_ref(td->td_cpuset); 2059 ts2->ts_cpu = ts->ts_cpu; 2060 ts2->ts_flags = 0; 2061 /* 2062 * Grab our parents cpu estimation information. 2063 */ 2064 ts2->ts_ticks = ts->ts_ticks; 2065 ts2->ts_ltick = ts->ts_ltick; 2066 ts2->ts_ftick = ts->ts_ftick; 2067 /* 2068 * Do not inherit any borrowed priority from the parent. 2069 */ 2070 child->td_priority = child->td_base_pri; 2071 /* 2072 * And update interactivity score. 2073 */ 2074 ts2->ts_slptime = ts->ts_slptime; 2075 ts2->ts_runtime = ts->ts_runtime; 2076 /* Attempt to quickly learn interactivity. */ 2077 ts2->ts_slice = tdq_slice(tdq) - sched_slice_min; 2078 #ifdef KTR 2079 bzero(ts2->ts_name, sizeof(ts2->ts_name)); 2080 #endif 2081 } 2082 2083 /* 2084 * Adjust the priority class of a thread. 2085 */ 2086 void 2087 sched_class(struct thread *td, int class) 2088 { 2089 2090 THREAD_LOCK_ASSERT(td, MA_OWNED); 2091 if (td->td_pri_class == class) 2092 return; 2093 td->td_pri_class = class; 2094 } 2095 2096 /* 2097 * Return some of the child's priority and interactivity to the parent. 2098 */ 2099 void 2100 sched_exit(struct proc *p, struct thread *child) 2101 { 2102 struct thread *td; 2103 2104 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "proc exit", 2105 "prio:%d", child->td_priority); 2106 PROC_LOCK_ASSERT(p, MA_OWNED); 2107 td = FIRST_THREAD_IN_PROC(p); 2108 sched_exit_thread(td, child); 2109 } 2110 2111 /* 2112 * Penalize another thread for the time spent on this one. This helps to 2113 * worsen the priority and interactivity of processes which schedule batch 2114 * jobs such as make. This has little effect on the make process itself but 2115 * causes new processes spawned by it to receive worse scores immediately. 2116 */ 2117 void 2118 sched_exit_thread(struct thread *td, struct thread *child) 2119 { 2120 2121 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "thread exit", 2122 "prio:%d", child->td_priority); 2123 /* 2124 * Give the child's runtime to the parent without returning the 2125 * sleep time as a penalty to the parent. This causes shells that 2126 * launch expensive things to mark their children as expensive. 2127 */ 2128 thread_lock(td); 2129 td->td_sched->ts_runtime += child->td_sched->ts_runtime; 2130 sched_interact_update(td); 2131 sched_priority(td); 2132 thread_unlock(td); 2133 } 2134 2135 void 2136 sched_preempt(struct thread *td) 2137 { 2138 struct tdq *tdq; 2139 2140 SDT_PROBE2(sched, , , surrender, td, td->td_proc); 2141 2142 thread_lock(td); 2143 tdq = TDQ_SELF(); 2144 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2145 tdq->tdq_ipipending = 0; 2146 if (td->td_priority > tdq->tdq_lowpri) { 2147 int flags; 2148 2149 flags = SW_INVOL | SW_PREEMPT; 2150 if (td->td_critnest > 1) 2151 td->td_owepreempt = 1; 2152 else if (TD_IS_IDLETHREAD(td)) 2153 mi_switch(flags | SWT_REMOTEWAKEIDLE, NULL); 2154 else 2155 mi_switch(flags | SWT_REMOTEPREEMPT, NULL); 2156 } 2157 thread_unlock(td); 2158 } 2159 2160 /* 2161 * Fix priorities on return to user-space. Priorities may be elevated due 2162 * to static priorities in msleep() or similar. 2163 */ 2164 void 2165 sched_userret(struct thread *td) 2166 { 2167 /* 2168 * XXX we cheat slightly on the locking here to avoid locking in 2169 * the usual case. Setting td_priority here is essentially an 2170 * incomplete workaround for not setting it properly elsewhere. 2171 * Now that some interrupt handlers are threads, not setting it 2172 * properly elsewhere can clobber it in the window between setting 2173 * it here and returning to user mode, so don't waste time setting 2174 * it perfectly here. 2175 */ 2176 KASSERT((td->td_flags & TDF_BORROWING) == 0, 2177 ("thread with borrowed priority returning to userland")); 2178 if (td->td_priority != td->td_user_pri) { 2179 thread_lock(td); 2180 td->td_priority = td->td_user_pri; 2181 td->td_base_pri = td->td_user_pri; 2182 tdq_setlowpri(TDQ_SELF(), td); 2183 thread_unlock(td); 2184 } 2185 } 2186 2187 /* 2188 * Handle a stathz tick. This is really only relevant for timeshare 2189 * threads. 2190 */ 2191 void 2192 sched_clock(struct thread *td) 2193 { 2194 struct tdq *tdq; 2195 struct td_sched *ts; 2196 2197 THREAD_LOCK_ASSERT(td, MA_OWNED); 2198 tdq = TDQ_SELF(); 2199 #ifdef SMP 2200 /* 2201 * We run the long term load balancer infrequently on the first cpu. 2202 */ 2203 if (balance_tdq == tdq) { 2204 if (balance_ticks && --balance_ticks == 0) 2205 sched_balance(); 2206 } 2207 #endif 2208 /* 2209 * Save the old switch count so we have a record of the last ticks 2210 * activity. Initialize the new switch count based on our load. 2211 * If there is some activity seed it to reflect that. 2212 */ 2213 tdq->tdq_oldswitchcnt = tdq->tdq_switchcnt; 2214 tdq->tdq_switchcnt = tdq->tdq_load; 2215 /* 2216 * Advance the insert index once for each tick to ensure that all 2217 * threads get a chance to run. 2218 */ 2219 if (tdq->tdq_idx == tdq->tdq_ridx) { 2220 tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS; 2221 if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx])) 2222 tdq->tdq_ridx = tdq->tdq_idx; 2223 } 2224 ts = td->td_sched; 2225 sched_pctcpu_update(ts, 1); 2226 if (td->td_pri_class & PRI_FIFO_BIT) 2227 return; 2228 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) { 2229 /* 2230 * We used a tick; charge it to the thread so 2231 * that we can compute our interactivity. 2232 */ 2233 td->td_sched->ts_runtime += tickincr; 2234 sched_interact_update(td); 2235 sched_priority(td); 2236 } 2237 2238 /* 2239 * Force a context switch if the current thread has used up a full 2240 * time slice (default is 100ms). 2241 */ 2242 if (!TD_IS_IDLETHREAD(td) && ++ts->ts_slice >= tdq_slice(tdq)) { 2243 ts->ts_slice = 0; 2244 td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND; 2245 } 2246 } 2247 2248 /* 2249 * Called once per hz tick. 2250 */ 2251 void 2252 sched_tick(int cnt) 2253 { 2254 2255 } 2256 2257 /* 2258 * Return whether the current CPU has runnable tasks. Used for in-kernel 2259 * cooperative idle threads. 2260 */ 2261 int 2262 sched_runnable(void) 2263 { 2264 struct tdq *tdq; 2265 int load; 2266 2267 load = 1; 2268 2269 tdq = TDQ_SELF(); 2270 if ((curthread->td_flags & TDF_IDLETD) != 0) { 2271 if (tdq->tdq_load > 0) 2272 goto out; 2273 } else 2274 if (tdq->tdq_load - 1 > 0) 2275 goto out; 2276 load = 0; 2277 out: 2278 return (load); 2279 } 2280 2281 /* 2282 * Choose the highest priority thread to run. The thread is removed from 2283 * the run-queue while running however the load remains. For SMP we set 2284 * the tdq in the global idle bitmask if it idles here. 2285 */ 2286 struct thread * 2287 sched_choose(void) 2288 { 2289 struct thread *td; 2290 struct tdq *tdq; 2291 2292 tdq = TDQ_SELF(); 2293 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2294 td = tdq_choose(tdq); 2295 if (td) { 2296 tdq_runq_rem(tdq, td); 2297 tdq->tdq_lowpri = td->td_priority; 2298 return (td); 2299 } 2300 tdq->tdq_lowpri = PRI_MAX_IDLE; 2301 return (PCPU_GET(idlethread)); 2302 } 2303 2304 /* 2305 * Set owepreempt if necessary. Preemption never happens directly in ULE, 2306 * we always request it once we exit a critical section. 2307 */ 2308 static inline void 2309 sched_setpreempt(struct thread *td) 2310 { 2311 struct thread *ctd; 2312 int cpri; 2313 int pri; 2314 2315 THREAD_LOCK_ASSERT(curthread, MA_OWNED); 2316 2317 ctd = curthread; 2318 pri = td->td_priority; 2319 cpri = ctd->td_priority; 2320 if (pri < cpri) 2321 ctd->td_flags |= TDF_NEEDRESCHED; 2322 if (panicstr != NULL || pri >= cpri || cold || TD_IS_INHIBITED(ctd)) 2323 return; 2324 if (!sched_shouldpreempt(pri, cpri, 0)) 2325 return; 2326 ctd->td_owepreempt = 1; 2327 } 2328 2329 /* 2330 * Add a thread to a thread queue. Select the appropriate runq and add the 2331 * thread to it. This is the internal function called when the tdq is 2332 * predetermined. 2333 */ 2334 void 2335 tdq_add(struct tdq *tdq, struct thread *td, int flags) 2336 { 2337 2338 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2339 KASSERT((td->td_inhibitors == 0), 2340 ("sched_add: trying to run inhibited thread")); 2341 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 2342 ("sched_add: bad thread state")); 2343 KASSERT(td->td_flags & TDF_INMEM, 2344 ("sched_add: thread swapped out")); 2345 2346 if (td->td_priority < tdq->tdq_lowpri) 2347 tdq->tdq_lowpri = td->td_priority; 2348 tdq_runq_add(tdq, td, flags); 2349 tdq_load_add(tdq, td); 2350 } 2351 2352 /* 2353 * Select the target thread queue and add a thread to it. Request 2354 * preemption or IPI a remote processor if required. 2355 */ 2356 void 2357 sched_add(struct thread *td, int flags) 2358 { 2359 struct tdq *tdq; 2360 #ifdef SMP 2361 int cpu; 2362 #endif 2363 2364 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 2365 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 2366 sched_tdname(curthread)); 2367 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 2368 KTR_ATTR_LINKED, sched_tdname(td)); 2369 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 2370 flags & SRQ_PREEMPTED); 2371 THREAD_LOCK_ASSERT(td, MA_OWNED); 2372 /* 2373 * Recalculate the priority before we select the target cpu or 2374 * run-queue. 2375 */ 2376 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 2377 sched_priority(td); 2378 #ifdef SMP 2379 /* 2380 * Pick the destination cpu and if it isn't ours transfer to the 2381 * target cpu. 2382 */ 2383 cpu = sched_pickcpu(td, flags); 2384 tdq = sched_setcpu(td, cpu, flags); 2385 tdq_add(tdq, td, flags); 2386 if (cpu != PCPU_GET(cpuid)) { 2387 tdq_notify(tdq, td); 2388 return; 2389 } 2390 #else 2391 tdq = TDQ_SELF(); 2392 TDQ_LOCK(tdq); 2393 /* 2394 * Now that the thread is moving to the run-queue, set the lock 2395 * to the scheduler's lock. 2396 */ 2397 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 2398 tdq_add(tdq, td, flags); 2399 #endif 2400 if (!(flags & SRQ_YIELDING)) 2401 sched_setpreempt(td); 2402 } 2403 2404 /* 2405 * Remove a thread from a run-queue without running it. This is used 2406 * when we're stealing a thread from a remote queue. Otherwise all threads 2407 * exit by calling sched_exit_thread() and sched_throw() themselves. 2408 */ 2409 void 2410 sched_rem(struct thread *td) 2411 { 2412 struct tdq *tdq; 2413 2414 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "runq rem", 2415 "prio:%d", td->td_priority); 2416 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL); 2417 tdq = TDQ_CPU(td->td_sched->ts_cpu); 2418 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2419 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2420 KASSERT(TD_ON_RUNQ(td), 2421 ("sched_rem: thread not on run queue")); 2422 tdq_runq_rem(tdq, td); 2423 tdq_load_rem(tdq, td); 2424 TD_SET_CAN_RUN(td); 2425 if (td->td_priority == tdq->tdq_lowpri) 2426 tdq_setlowpri(tdq, NULL); 2427 } 2428 2429 /* 2430 * Fetch cpu utilization information. Updates on demand. 2431 */ 2432 fixpt_t 2433 sched_pctcpu(struct thread *td) 2434 { 2435 fixpt_t pctcpu; 2436 struct td_sched *ts; 2437 2438 pctcpu = 0; 2439 ts = td->td_sched; 2440 if (ts == NULL) 2441 return (0); 2442 2443 THREAD_LOCK_ASSERT(td, MA_OWNED); 2444 sched_pctcpu_update(ts, TD_IS_RUNNING(td)); 2445 if (ts->ts_ticks) { 2446 int rtick; 2447 2448 /* How many rtick per second ? */ 2449 rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz); 2450 pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT; 2451 } 2452 2453 return (pctcpu); 2454 } 2455 2456 /* 2457 * Enforce affinity settings for a thread. Called after adjustments to 2458 * cpumask. 2459 */ 2460 void 2461 sched_affinity(struct thread *td) 2462 { 2463 #ifdef SMP 2464 struct td_sched *ts; 2465 2466 THREAD_LOCK_ASSERT(td, MA_OWNED); 2467 ts = td->td_sched; 2468 if (THREAD_CAN_SCHED(td, ts->ts_cpu)) 2469 return; 2470 if (TD_ON_RUNQ(td)) { 2471 sched_rem(td); 2472 sched_add(td, SRQ_BORING); 2473 return; 2474 } 2475 if (!TD_IS_RUNNING(td)) 2476 return; 2477 /* 2478 * Force a switch before returning to userspace. If the 2479 * target thread is not running locally send an ipi to force 2480 * the issue. 2481 */ 2482 td->td_flags |= TDF_NEEDRESCHED; 2483 if (td != curthread) 2484 ipi_cpu(ts->ts_cpu, IPI_PREEMPT); 2485 #endif 2486 } 2487 2488 /* 2489 * Bind a thread to a target cpu. 2490 */ 2491 void 2492 sched_bind(struct thread *td, int cpu) 2493 { 2494 struct td_sched *ts; 2495 2496 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 2497 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 2498 ts = td->td_sched; 2499 if (ts->ts_flags & TSF_BOUND) 2500 sched_unbind(td); 2501 KASSERT(THREAD_CAN_MIGRATE(td), ("%p must be migratable", td)); 2502 ts->ts_flags |= TSF_BOUND; 2503 sched_pin(); 2504 if (PCPU_GET(cpuid) == cpu) 2505 return; 2506 ts->ts_cpu = cpu; 2507 /* When we return from mi_switch we'll be on the correct cpu. */ 2508 mi_switch(SW_VOL, NULL); 2509 } 2510 2511 /* 2512 * Release a bound thread. 2513 */ 2514 void 2515 sched_unbind(struct thread *td) 2516 { 2517 struct td_sched *ts; 2518 2519 THREAD_LOCK_ASSERT(td, MA_OWNED); 2520 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 2521 ts = td->td_sched; 2522 if ((ts->ts_flags & TSF_BOUND) == 0) 2523 return; 2524 ts->ts_flags &= ~TSF_BOUND; 2525 sched_unpin(); 2526 } 2527 2528 int 2529 sched_is_bound(struct thread *td) 2530 { 2531 THREAD_LOCK_ASSERT(td, MA_OWNED); 2532 return (td->td_sched->ts_flags & TSF_BOUND); 2533 } 2534 2535 /* 2536 * Basic yield call. 2537 */ 2538 void 2539 sched_relinquish(struct thread *td) 2540 { 2541 thread_lock(td); 2542 mi_switch(SW_VOL | SWT_RELINQUISH, NULL); 2543 thread_unlock(td); 2544 } 2545 2546 /* 2547 * Return the total system load. 2548 */ 2549 int 2550 sched_load(void) 2551 { 2552 #ifdef SMP 2553 int total; 2554 int i; 2555 2556 total = 0; 2557 CPU_FOREACH(i) 2558 total += TDQ_CPU(i)->tdq_sysload; 2559 return (total); 2560 #else 2561 return (TDQ_SELF()->tdq_sysload); 2562 #endif 2563 } 2564 2565 int 2566 sched_sizeof_proc(void) 2567 { 2568 return (sizeof(struct proc)); 2569 } 2570 2571 int 2572 sched_sizeof_thread(void) 2573 { 2574 return (sizeof(struct thread) + sizeof(struct td_sched)); 2575 } 2576 2577 #ifdef SMP 2578 #define TDQ_IDLESPIN(tdq) \ 2579 ((tdq)->tdq_cg != NULL && ((tdq)->tdq_cg->cg_flags & CG_FLAG_THREAD) == 0) 2580 #else 2581 #define TDQ_IDLESPIN(tdq) 1 2582 #endif 2583 2584 /* 2585 * The actual idle process. 2586 */ 2587 void 2588 sched_idletd(void *dummy) 2589 { 2590 struct thread *td; 2591 struct tdq *tdq; 2592 int oldswitchcnt, switchcnt; 2593 int i; 2594 2595 mtx_assert(&Giant, MA_NOTOWNED); 2596 td = curthread; 2597 tdq = TDQ_SELF(); 2598 THREAD_NO_SLEEPING(); 2599 oldswitchcnt = -1; 2600 for (;;) { 2601 if (tdq->tdq_load) { 2602 thread_lock(td); 2603 mi_switch(SW_VOL | SWT_IDLE, NULL); 2604 thread_unlock(td); 2605 } 2606 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2607 #ifdef SMP 2608 if (switchcnt != oldswitchcnt) { 2609 oldswitchcnt = switchcnt; 2610 if (tdq_idled(tdq) == 0) 2611 continue; 2612 } 2613 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2614 #else 2615 oldswitchcnt = switchcnt; 2616 #endif 2617 /* 2618 * If we're switching very frequently, spin while checking 2619 * for load rather than entering a low power state that 2620 * may require an IPI. However, don't do any busy 2621 * loops while on SMT machines as this simply steals 2622 * cycles from cores doing useful work. 2623 */ 2624 if (TDQ_IDLESPIN(tdq) && switchcnt > sched_idlespinthresh) { 2625 for (i = 0; i < sched_idlespins; i++) { 2626 if (tdq->tdq_load) 2627 break; 2628 cpu_spinwait(); 2629 } 2630 } 2631 2632 /* If there was context switch during spin, restart it. */ 2633 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2634 if (tdq->tdq_load != 0 || switchcnt != oldswitchcnt) 2635 continue; 2636 2637 /* Run main MD idle handler. */ 2638 tdq->tdq_cpu_idle = 1; 2639 cpu_idle(switchcnt * 4 > sched_idlespinthresh); 2640 tdq->tdq_cpu_idle = 0; 2641 2642 /* 2643 * Account thread-less hardware interrupts and 2644 * other wakeup reasons equal to context switches. 2645 */ 2646 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2647 if (switchcnt != oldswitchcnt) 2648 continue; 2649 tdq->tdq_switchcnt++; 2650 oldswitchcnt++; 2651 } 2652 } 2653 2654 /* 2655 * A CPU is entering for the first time or a thread is exiting. 2656 */ 2657 void 2658 sched_throw(struct thread *td) 2659 { 2660 struct thread *newtd; 2661 struct tdq *tdq; 2662 2663 tdq = TDQ_SELF(); 2664 if (td == NULL) { 2665 /* Correct spinlock nesting and acquire the correct lock. */ 2666 TDQ_LOCK(tdq); 2667 spinlock_exit(); 2668 PCPU_SET(switchtime, cpu_ticks()); 2669 PCPU_SET(switchticks, ticks); 2670 } else { 2671 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2672 tdq_load_rem(tdq, td); 2673 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 2674 } 2675 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 2676 newtd = choosethread(); 2677 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 2678 cpu_throw(td, newtd); /* doesn't return */ 2679 } 2680 2681 /* 2682 * This is called from fork_exit(). Just acquire the correct locks and 2683 * let fork do the rest of the work. 2684 */ 2685 void 2686 sched_fork_exit(struct thread *td) 2687 { 2688 struct td_sched *ts; 2689 struct tdq *tdq; 2690 int cpuid; 2691 2692 /* 2693 * Finish setting up thread glue so that it begins execution in a 2694 * non-nested critical section with the scheduler lock held. 2695 */ 2696 cpuid = PCPU_GET(cpuid); 2697 tdq = TDQ_CPU(cpuid); 2698 ts = td->td_sched; 2699 if (TD_IS_IDLETHREAD(td)) 2700 td->td_lock = TDQ_LOCKPTR(tdq); 2701 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2702 td->td_oncpu = cpuid; 2703 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 2704 lock_profile_obtain_lock_success( 2705 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 2706 } 2707 2708 /* 2709 * Create on first use to catch odd startup conditons. 2710 */ 2711 char * 2712 sched_tdname(struct thread *td) 2713 { 2714 #ifdef KTR 2715 struct td_sched *ts; 2716 2717 ts = td->td_sched; 2718 if (ts->ts_name[0] == '\0') 2719 snprintf(ts->ts_name, sizeof(ts->ts_name), 2720 "%s tid %d", td->td_name, td->td_tid); 2721 return (ts->ts_name); 2722 #else 2723 return (td->td_name); 2724 #endif 2725 } 2726 2727 #ifdef KTR 2728 void 2729 sched_clear_tdname(struct thread *td) 2730 { 2731 struct td_sched *ts; 2732 2733 ts = td->td_sched; 2734 ts->ts_name[0] = '\0'; 2735 } 2736 #endif 2737 2738 #ifdef SMP 2739 2740 /* 2741 * Build the CPU topology dump string. Is recursively called to collect 2742 * the topology tree. 2743 */ 2744 static int 2745 sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, struct cpu_group *cg, 2746 int indent) 2747 { 2748 char cpusetbuf[CPUSETBUFSIZ]; 2749 int i, first; 2750 2751 sbuf_printf(sb, "%*s<group level=\"%d\" cache-level=\"%d\">\n", indent, 2752 "", 1 + indent / 2, cg->cg_level); 2753 sbuf_printf(sb, "%*s <cpu count=\"%d\" mask=\"%s\">", indent, "", 2754 cg->cg_count, cpusetobj_strprint(cpusetbuf, &cg->cg_mask)); 2755 first = TRUE; 2756 for (i = 0; i < MAXCPU; i++) { 2757 if (CPU_ISSET(i, &cg->cg_mask)) { 2758 if (!first) 2759 sbuf_printf(sb, ", "); 2760 else 2761 first = FALSE; 2762 sbuf_printf(sb, "%d", i); 2763 } 2764 } 2765 sbuf_printf(sb, "</cpu>\n"); 2766 2767 if (cg->cg_flags != 0) { 2768 sbuf_printf(sb, "%*s <flags>", indent, ""); 2769 if ((cg->cg_flags & CG_FLAG_HTT) != 0) 2770 sbuf_printf(sb, "<flag name=\"HTT\">HTT group</flag>"); 2771 if ((cg->cg_flags & CG_FLAG_THREAD) != 0) 2772 sbuf_printf(sb, "<flag name=\"THREAD\">THREAD group</flag>"); 2773 if ((cg->cg_flags & CG_FLAG_SMT) != 0) 2774 sbuf_printf(sb, "<flag name=\"SMT\">SMT group</flag>"); 2775 sbuf_printf(sb, "</flags>\n"); 2776 } 2777 2778 if (cg->cg_children > 0) { 2779 sbuf_printf(sb, "%*s <children>\n", indent, ""); 2780 for (i = 0; i < cg->cg_children; i++) 2781 sysctl_kern_sched_topology_spec_internal(sb, 2782 &cg->cg_child[i], indent+2); 2783 sbuf_printf(sb, "%*s </children>\n", indent, ""); 2784 } 2785 sbuf_printf(sb, "%*s</group>\n", indent, ""); 2786 return (0); 2787 } 2788 2789 /* 2790 * Sysctl handler for retrieving topology dump. It's a wrapper for 2791 * the recursive sysctl_kern_smp_topology_spec_internal(). 2792 */ 2793 static int 2794 sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS) 2795 { 2796 struct sbuf *topo; 2797 int err; 2798 2799 KASSERT(cpu_top != NULL, ("cpu_top isn't initialized")); 2800 2801 topo = sbuf_new(NULL, NULL, 500, SBUF_AUTOEXTEND); 2802 if (topo == NULL) 2803 return (ENOMEM); 2804 2805 sbuf_printf(topo, "<groups>\n"); 2806 err = sysctl_kern_sched_topology_spec_internal(topo, cpu_top, 1); 2807 sbuf_printf(topo, "</groups>\n"); 2808 2809 if (err == 0) { 2810 sbuf_finish(topo); 2811 err = SYSCTL_OUT(req, sbuf_data(topo), sbuf_len(topo)); 2812 } 2813 sbuf_delete(topo); 2814 return (err); 2815 } 2816 2817 #endif 2818 2819 static int 2820 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 2821 { 2822 int error, new_val, period; 2823 2824 period = 1000000 / realstathz; 2825 new_val = period * sched_slice; 2826 error = sysctl_handle_int(oidp, &new_val, 0, req); 2827 if (error != 0 || req->newptr == NULL) 2828 return (error); 2829 if (new_val <= 0) 2830 return (EINVAL); 2831 sched_slice = imax(1, (new_val + period / 2) / period); 2832 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 2833 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 2834 realstathz); 2835 return (0); 2836 } 2837 2838 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0, "Scheduler"); 2839 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0, 2840 "Scheduler name"); 2841 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW, 2842 NULL, 0, sysctl_kern_quantum, "I", 2843 "Quantum for timeshare threads in microseconds"); 2844 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, 2845 "Quantum for timeshare threads in stathz ticks"); 2846 SYSCTL_INT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0, 2847 "Interactivity score threshold"); 2848 SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW, 2849 &preempt_thresh, 0, 2850 "Maximal (lowest) priority for preemption"); 2851 SYSCTL_INT(_kern_sched, OID_AUTO, static_boost, CTLFLAG_RW, &static_boost, 0, 2852 "Assign static kernel priorities to sleeping threads"); 2853 SYSCTL_INT(_kern_sched, OID_AUTO, idlespins, CTLFLAG_RW, &sched_idlespins, 0, 2854 "Number of times idle thread will spin waiting for new work"); 2855 SYSCTL_INT(_kern_sched, OID_AUTO, idlespinthresh, CTLFLAG_RW, 2856 &sched_idlespinthresh, 0, 2857 "Threshold before we will permit idle thread spinning"); 2858 #ifdef SMP 2859 SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0, 2860 "Number of hz ticks to keep thread affinity for"); 2861 SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0, 2862 "Enables the long-term load balancer"); 2863 SYSCTL_INT(_kern_sched, OID_AUTO, balance_interval, CTLFLAG_RW, 2864 &balance_interval, 0, 2865 "Average period in stathz ticks to run the long-term balancer"); 2866 SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0, 2867 "Attempts to steal work from other cores before idling"); 2868 SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0, 2869 "Minimum load on remote CPU before we'll steal"); 2870 SYSCTL_PROC(_kern_sched, OID_AUTO, topology_spec, CTLTYPE_STRING | 2871 CTLFLAG_RD, NULL, 0, sysctl_kern_sched_topology_spec, "A", 2872 "XML dump of detected CPU topology"); 2873 #endif 2874 2875 /* ps compat. All cpu percentages from ULE are weighted. */ 2876 static int ccpu = 0; 2877 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 2878