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/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/umtx.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 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 static struct td_sched td_sched0; 110 111 #define THREAD_CAN_MIGRATE(td) ((td)->td_pinned == 0) 112 #define THREAD_CAN_SCHED(td, cpu) \ 113 CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask) 114 115 /* 116 * Priority ranges used for interactive and non-interactive timeshare 117 * threads. The timeshare priorities are split up into four ranges. 118 * The first range handles interactive threads. The last three ranges 119 * (NHALF, x, and NHALF) handle non-interactive threads with the outer 120 * ranges supporting nice values. 121 */ 122 #define PRI_TIMESHARE_RANGE (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE + 1) 123 #define PRI_INTERACT_RANGE ((PRI_TIMESHARE_RANGE - SCHED_PRI_NRESV) / 2) 124 #define PRI_BATCH_RANGE (PRI_TIMESHARE_RANGE - PRI_INTERACT_RANGE) 125 126 #define PRI_MIN_INTERACT PRI_MIN_TIMESHARE 127 #define PRI_MAX_INTERACT (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE - 1) 128 #define PRI_MIN_BATCH (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE) 129 #define PRI_MAX_BATCH PRI_MAX_TIMESHARE 130 131 /* 132 * Cpu percentage computation macros and defines. 133 * 134 * SCHED_TICK_SECS: Number of seconds to average the cpu usage across. 135 * SCHED_TICK_TARG: Number of hz ticks to average the cpu usage across. 136 * SCHED_TICK_MAX: Maximum number of ticks before scaling back. 137 * SCHED_TICK_SHIFT: Shift factor to avoid rounding away results. 138 * SCHED_TICK_HZ: Compute the number of hz ticks for a given ticks count. 139 * SCHED_TICK_TOTAL: Gives the amount of time we've been recording ticks. 140 */ 141 #define SCHED_TICK_SECS 10 142 #define SCHED_TICK_TARG (hz * SCHED_TICK_SECS) 143 #define SCHED_TICK_MAX (SCHED_TICK_TARG + hz) 144 #define SCHED_TICK_SHIFT 10 145 #define SCHED_TICK_HZ(ts) ((ts)->ts_ticks >> SCHED_TICK_SHIFT) 146 #define SCHED_TICK_TOTAL(ts) (max((ts)->ts_ltick - (ts)->ts_ftick, hz)) 147 148 /* 149 * These macros determine priorities for non-interactive threads. They are 150 * assigned a priority based on their recent cpu utilization as expressed 151 * by the ratio of ticks to the tick total. NHALF priorities at the start 152 * and end of the MIN to MAX timeshare range are only reachable with negative 153 * or positive nice respectively. 154 * 155 * PRI_RANGE: Priority range for utilization dependent priorities. 156 * PRI_NRESV: Number of nice values. 157 * PRI_TICKS: Compute a priority in PRI_RANGE from the ticks count and total. 158 * PRI_NICE: Determines the part of the priority inherited from nice. 159 */ 160 #define SCHED_PRI_NRESV (PRIO_MAX - PRIO_MIN) 161 #define SCHED_PRI_NHALF (SCHED_PRI_NRESV / 2) 162 #define SCHED_PRI_MIN (PRI_MIN_BATCH + SCHED_PRI_NHALF) 163 #define SCHED_PRI_MAX (PRI_MAX_BATCH - SCHED_PRI_NHALF) 164 #define SCHED_PRI_RANGE (SCHED_PRI_MAX - SCHED_PRI_MIN + 1) 165 #define SCHED_PRI_TICKS(ts) \ 166 (SCHED_TICK_HZ((ts)) / \ 167 (roundup(SCHED_TICK_TOTAL((ts)), SCHED_PRI_RANGE) / SCHED_PRI_RANGE)) 168 #define SCHED_PRI_NICE(nice) (nice) 169 170 /* 171 * These determine the interactivity of a process. Interactivity differs from 172 * cpu utilization in that it expresses the voluntary time slept vs time ran 173 * while cpu utilization includes all time not running. This more accurately 174 * models the intent of the thread. 175 * 176 * SLP_RUN_MAX: Maximum amount of sleep time + run time we'll accumulate 177 * before throttling back. 178 * SLP_RUN_FORK: Maximum slp+run time to inherit at fork time. 179 * INTERACT_MAX: Maximum interactivity value. Smaller is better. 180 * INTERACT_THRESH: Threshold for placement on the current runq. 181 */ 182 #define SCHED_SLP_RUN_MAX ((hz * 5) << SCHED_TICK_SHIFT) 183 #define SCHED_SLP_RUN_FORK ((hz / 2) << SCHED_TICK_SHIFT) 184 #define SCHED_INTERACT_MAX (100) 185 #define SCHED_INTERACT_HALF (SCHED_INTERACT_MAX / 2) 186 #define SCHED_INTERACT_THRESH (30) 187 188 /* 189 * These parameters determine the slice behavior for batch work. 190 */ 191 #define SCHED_SLICE_DEFAULT_DIVISOR 10 /* ~94 ms, 12 stathz ticks. */ 192 #define SCHED_SLICE_MIN_DIVISOR 6 /* DEFAULT/MIN = ~16 ms. */ 193 194 /* Flags kept in td_flags. */ 195 #define TDF_SLICEEND TDF_SCHED2 /* Thread time slice is over. */ 196 197 /* 198 * tickincr: Converts a stathz tick into a hz domain scaled by 199 * the shift factor. Without the shift the error rate 200 * due to rounding would be unacceptably high. 201 * realstathz: stathz is sometimes 0 and run off of hz. 202 * sched_slice: Runtime of each thread before rescheduling. 203 * preempt_thresh: Priority threshold for preemption and remote IPIs. 204 */ 205 static int sched_interact = SCHED_INTERACT_THRESH; 206 static int tickincr = 8 << SCHED_TICK_SHIFT; 207 static int realstathz = 127; /* reset during boot. */ 208 static int sched_slice = 10; /* reset during boot. */ 209 static int sched_slice_min = 1; /* reset during boot. */ 210 #ifdef PREEMPTION 211 #ifdef FULL_PREEMPTION 212 static int preempt_thresh = PRI_MAX_IDLE; 213 #else 214 static int preempt_thresh = PRI_MIN_KERN; 215 #endif 216 #else 217 static int preempt_thresh = 0; 218 #endif 219 static int static_boost = PRI_MIN_BATCH; 220 static int sched_idlespins = 10000; 221 static int sched_idlespinthresh = -1; 222 223 /* 224 * tdq - per processor runqs and statistics. All fields are protected by the 225 * tdq_lock. The load and lowpri may be accessed without to avoid excess 226 * locking in sched_pickcpu(); 227 */ 228 struct tdq { 229 /* 230 * Ordered to improve efficiency of cpu_search() and switch(). 231 * tdq_lock is padded to avoid false sharing with tdq_load and 232 * tdq_cpu_idle. 233 */ 234 struct mtx_padalign tdq_lock; /* run queue lock. */ 235 struct cpu_group *tdq_cg; /* Pointer to cpu topology. */ 236 volatile int tdq_load; /* Aggregate load. */ 237 volatile int tdq_cpu_idle; /* cpu_idle() is active. */ 238 int tdq_sysload; /* For loadavg, !ITHD load. */ 239 int tdq_transferable; /* Transferable thread count. */ 240 short tdq_switchcnt; /* Switches this tick. */ 241 short tdq_oldswitchcnt; /* Switches last tick. */ 242 u_char tdq_lowpri; /* Lowest priority thread. */ 243 u_char tdq_ipipending; /* IPI pending. */ 244 u_char tdq_idx; /* Current insert index. */ 245 u_char tdq_ridx; /* Current removal index. */ 246 struct runq tdq_realtime; /* real-time run queue. */ 247 struct runq tdq_timeshare; /* timeshare run queue. */ 248 struct runq tdq_idle; /* Queue of IDLE threads. */ 249 char tdq_name[TDQ_NAME_LEN]; 250 #ifdef KTR 251 char tdq_loadname[TDQ_LOADNAME_LEN]; 252 #endif 253 } __aligned(64); 254 255 /* Idle thread states and config. */ 256 #define TDQ_RUNNING 1 257 #define TDQ_IDLE 2 258 259 #ifdef SMP 260 struct cpu_group *cpu_top; /* CPU topology */ 261 262 #define SCHED_AFFINITY_DEFAULT (max(1, hz / 1000)) 263 #define SCHED_AFFINITY(ts, t) ((ts)->ts_rltick > ticks - ((t) * affinity)) 264 265 /* 266 * Run-time tunables. 267 */ 268 static int rebalance = 1; 269 static int balance_interval = 128; /* Default set in sched_initticks(). */ 270 static int affinity; 271 static int steal_idle = 1; 272 static int steal_thresh = 2; 273 274 /* 275 * One thread queue per processor. 276 */ 277 static struct tdq tdq_cpu[MAXCPU]; 278 static struct tdq *balance_tdq; 279 static int balance_ticks; 280 static DPCPU_DEFINE(uint32_t, randomval); 281 282 #define TDQ_SELF() (&tdq_cpu[PCPU_GET(cpuid)]) 283 #define TDQ_CPU(x) (&tdq_cpu[(x)]) 284 #define TDQ_ID(x) ((int)((x) - tdq_cpu)) 285 #else /* !SMP */ 286 static struct tdq tdq_cpu; 287 288 #define TDQ_ID(x) (0) 289 #define TDQ_SELF() (&tdq_cpu) 290 #define TDQ_CPU(x) (&tdq_cpu) 291 #endif 292 293 #define TDQ_LOCK_ASSERT(t, type) mtx_assert(TDQ_LOCKPTR((t)), (type)) 294 #define TDQ_LOCK(t) mtx_lock_spin(TDQ_LOCKPTR((t))) 295 #define TDQ_LOCK_FLAGS(t, f) mtx_lock_spin_flags(TDQ_LOCKPTR((t)), (f)) 296 #define TDQ_UNLOCK(t) mtx_unlock_spin(TDQ_LOCKPTR((t))) 297 #define TDQ_LOCKPTR(t) ((struct mtx *)(&(t)->tdq_lock)) 298 299 static void sched_priority(struct thread *); 300 static void sched_thread_priority(struct thread *, u_char); 301 static int sched_interact_score(struct thread *); 302 static void sched_interact_update(struct thread *); 303 static void sched_interact_fork(struct thread *); 304 static void sched_pctcpu_update(struct td_sched *, int); 305 306 /* Operations on per processor queues */ 307 static struct thread *tdq_choose(struct tdq *); 308 static void tdq_setup(struct tdq *); 309 static void tdq_load_add(struct tdq *, struct thread *); 310 static void tdq_load_rem(struct tdq *, struct thread *); 311 static __inline void tdq_runq_add(struct tdq *, struct thread *, int); 312 static __inline void tdq_runq_rem(struct tdq *, struct thread *); 313 static inline int sched_shouldpreempt(int, int, int); 314 void tdq_print(int cpu); 315 static void runq_print(struct runq *rq); 316 static void tdq_add(struct tdq *, struct thread *, int); 317 #ifdef SMP 318 static int tdq_move(struct tdq *, struct tdq *); 319 static int tdq_idled(struct tdq *); 320 static void tdq_notify(struct tdq *, struct thread *); 321 static struct thread *tdq_steal(struct tdq *, int); 322 static struct thread *runq_steal(struct runq *, int); 323 static int sched_pickcpu(struct thread *, int); 324 static void sched_balance(void); 325 static int sched_balance_pair(struct tdq *, struct tdq *); 326 static inline struct tdq *sched_setcpu(struct thread *, int, int); 327 static inline void thread_unblock_switch(struct thread *, struct mtx *); 328 static struct mtx *sched_switch_migrate(struct tdq *, struct thread *, int); 329 static int sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS); 330 static int sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, 331 struct cpu_group *cg, int indent); 332 #endif 333 334 static void sched_setup(void *dummy); 335 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL); 336 337 static void sched_initticks(void *dummy); 338 SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks, 339 NULL); 340 341 SDT_PROVIDER_DEFINE(sched); 342 343 SDT_PROBE_DEFINE3(sched, , , change__pri, "struct thread *", 344 "struct proc *", "uint8_t"); 345 SDT_PROBE_DEFINE3(sched, , , dequeue, "struct thread *", 346 "struct proc *", "void *"); 347 SDT_PROBE_DEFINE4(sched, , , enqueue, "struct thread *", 348 "struct proc *", "void *", "int"); 349 SDT_PROBE_DEFINE4(sched, , , lend__pri, "struct thread *", 350 "struct proc *", "uint8_t", "struct thread *"); 351 SDT_PROBE_DEFINE2(sched, , , load__change, "int", "int"); 352 SDT_PROBE_DEFINE2(sched, , , off__cpu, "struct thread *", 353 "struct proc *"); 354 SDT_PROBE_DEFINE(sched, , , on__cpu); 355 SDT_PROBE_DEFINE(sched, , , remain__cpu); 356 SDT_PROBE_DEFINE2(sched, , , surrender, "struct thread *", 357 "struct proc *"); 358 359 /* 360 * Print the threads waiting on a run-queue. 361 */ 362 static void 363 runq_print(struct runq *rq) 364 { 365 struct rqhead *rqh; 366 struct thread *td; 367 int pri; 368 int j; 369 int i; 370 371 for (i = 0; i < RQB_LEN; i++) { 372 printf("\t\trunq bits %d 0x%zx\n", 373 i, rq->rq_status.rqb_bits[i]); 374 for (j = 0; j < RQB_BPW; j++) 375 if (rq->rq_status.rqb_bits[i] & (1ul << j)) { 376 pri = j + (i << RQB_L2BPW); 377 rqh = &rq->rq_queues[pri]; 378 TAILQ_FOREACH(td, rqh, td_runq) { 379 printf("\t\t\ttd %p(%s) priority %d rqindex %d pri %d\n", 380 td, td->td_name, td->td_priority, 381 td->td_rqindex, pri); 382 } 383 } 384 } 385 } 386 387 /* 388 * Print the status of a per-cpu thread queue. Should be a ddb show cmd. 389 */ 390 void 391 tdq_print(int cpu) 392 { 393 struct tdq *tdq; 394 395 tdq = TDQ_CPU(cpu); 396 397 printf("tdq %d:\n", TDQ_ID(tdq)); 398 printf("\tlock %p\n", TDQ_LOCKPTR(tdq)); 399 printf("\tLock name: %s\n", tdq->tdq_name); 400 printf("\tload: %d\n", tdq->tdq_load); 401 printf("\tswitch cnt: %d\n", tdq->tdq_switchcnt); 402 printf("\told switch cnt: %d\n", tdq->tdq_oldswitchcnt); 403 printf("\ttimeshare idx: %d\n", tdq->tdq_idx); 404 printf("\ttimeshare ridx: %d\n", tdq->tdq_ridx); 405 printf("\tload transferable: %d\n", tdq->tdq_transferable); 406 printf("\tlowest priority: %d\n", tdq->tdq_lowpri); 407 printf("\trealtime runq:\n"); 408 runq_print(&tdq->tdq_realtime); 409 printf("\ttimeshare runq:\n"); 410 runq_print(&tdq->tdq_timeshare); 411 printf("\tidle runq:\n"); 412 runq_print(&tdq->tdq_idle); 413 } 414 415 static inline int 416 sched_shouldpreempt(int pri, int cpri, int remote) 417 { 418 /* 419 * If the new priority is not better than the current priority there is 420 * nothing to do. 421 */ 422 if (pri >= cpri) 423 return (0); 424 /* 425 * Always preempt idle. 426 */ 427 if (cpri >= PRI_MIN_IDLE) 428 return (1); 429 /* 430 * If preemption is disabled don't preempt others. 431 */ 432 if (preempt_thresh == 0) 433 return (0); 434 /* 435 * Preempt if we exceed the threshold. 436 */ 437 if (pri <= preempt_thresh) 438 return (1); 439 /* 440 * If we're interactive or better and there is non-interactive 441 * or worse running preempt only remote processors. 442 */ 443 if (remote && pri <= PRI_MAX_INTERACT && cpri > PRI_MAX_INTERACT) 444 return (1); 445 return (0); 446 } 447 448 /* 449 * Add a thread to the actual run-queue. Keeps transferable counts up to 450 * date with what is actually on the run-queue. Selects the correct 451 * queue position for timeshare threads. 452 */ 453 static __inline void 454 tdq_runq_add(struct tdq *tdq, struct thread *td, int flags) 455 { 456 struct td_sched *ts; 457 u_char pri; 458 459 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 460 THREAD_LOCK_ASSERT(td, MA_OWNED); 461 462 pri = td->td_priority; 463 ts = td->td_sched; 464 TD_SET_RUNQ(td); 465 if (THREAD_CAN_MIGRATE(td)) { 466 tdq->tdq_transferable++; 467 ts->ts_flags |= TSF_XFERABLE; 468 } 469 if (pri < PRI_MIN_BATCH) { 470 ts->ts_runq = &tdq->tdq_realtime; 471 } else if (pri <= PRI_MAX_BATCH) { 472 ts->ts_runq = &tdq->tdq_timeshare; 473 KASSERT(pri <= PRI_MAX_BATCH && pri >= PRI_MIN_BATCH, 474 ("Invalid priority %d on timeshare runq", pri)); 475 /* 476 * This queue contains only priorities between MIN and MAX 477 * realtime. Use the whole queue to represent these values. 478 */ 479 if ((flags & (SRQ_BORROWING|SRQ_PREEMPTED)) == 0) { 480 pri = RQ_NQS * (pri - PRI_MIN_BATCH) / PRI_BATCH_RANGE; 481 pri = (pri + tdq->tdq_idx) % RQ_NQS; 482 /* 483 * This effectively shortens the queue by one so we 484 * can have a one slot difference between idx and 485 * ridx while we wait for threads to drain. 486 */ 487 if (tdq->tdq_ridx != tdq->tdq_idx && 488 pri == tdq->tdq_ridx) 489 pri = (unsigned char)(pri - 1) % RQ_NQS; 490 } else 491 pri = tdq->tdq_ridx; 492 runq_add_pri(ts->ts_runq, td, pri, flags); 493 return; 494 } else 495 ts->ts_runq = &tdq->tdq_idle; 496 runq_add(ts->ts_runq, td, flags); 497 } 498 499 /* 500 * Remove a thread from a run-queue. This typically happens when a thread 501 * is selected to run. Running threads are not on the queue and the 502 * transferable count does not reflect them. 503 */ 504 static __inline void 505 tdq_runq_rem(struct tdq *tdq, struct thread *td) 506 { 507 struct td_sched *ts; 508 509 ts = td->td_sched; 510 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 511 KASSERT(ts->ts_runq != NULL, 512 ("tdq_runq_remove: thread %p null ts_runq", td)); 513 if (ts->ts_flags & TSF_XFERABLE) { 514 tdq->tdq_transferable--; 515 ts->ts_flags &= ~TSF_XFERABLE; 516 } 517 if (ts->ts_runq == &tdq->tdq_timeshare) { 518 if (tdq->tdq_idx != tdq->tdq_ridx) 519 runq_remove_idx(ts->ts_runq, td, &tdq->tdq_ridx); 520 else 521 runq_remove_idx(ts->ts_runq, td, NULL); 522 } else 523 runq_remove(ts->ts_runq, td); 524 } 525 526 /* 527 * Load is maintained for all threads RUNNING and ON_RUNQ. Add the load 528 * for this thread to the referenced thread queue. 529 */ 530 static void 531 tdq_load_add(struct tdq *tdq, struct thread *td) 532 { 533 534 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 535 THREAD_LOCK_ASSERT(td, MA_OWNED); 536 537 tdq->tdq_load++; 538 if ((td->td_flags & TDF_NOLOAD) == 0) 539 tdq->tdq_sysload++; 540 KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load); 541 SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load); 542 } 543 544 /* 545 * Remove the load from a thread that is transitioning to a sleep state or 546 * exiting. 547 */ 548 static void 549 tdq_load_rem(struct tdq *tdq, struct thread *td) 550 { 551 552 THREAD_LOCK_ASSERT(td, MA_OWNED); 553 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 554 KASSERT(tdq->tdq_load != 0, 555 ("tdq_load_rem: Removing with 0 load on queue %d", TDQ_ID(tdq))); 556 557 tdq->tdq_load--; 558 if ((td->td_flags & TDF_NOLOAD) == 0) 559 tdq->tdq_sysload--; 560 KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load); 561 SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load); 562 } 563 564 /* 565 * Bound timeshare latency by decreasing slice size as load increases. We 566 * consider the maximum latency as the sum of the threads waiting to run 567 * aside from curthread and target no more than sched_slice latency but 568 * no less than sched_slice_min runtime. 569 */ 570 static inline int 571 tdq_slice(struct tdq *tdq) 572 { 573 int load; 574 575 /* 576 * It is safe to use sys_load here because this is called from 577 * contexts where timeshare threads are running and so there 578 * cannot be higher priority load in the system. 579 */ 580 load = tdq->tdq_sysload - 1; 581 if (load >= SCHED_SLICE_MIN_DIVISOR) 582 return (sched_slice_min); 583 if (load <= 1) 584 return (sched_slice); 585 return (sched_slice / load); 586 } 587 588 /* 589 * Set lowpri to its exact value by searching the run-queue and 590 * evaluating curthread. curthread may be passed as an optimization. 591 */ 592 static void 593 tdq_setlowpri(struct tdq *tdq, struct thread *ctd) 594 { 595 struct thread *td; 596 597 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 598 if (ctd == NULL) 599 ctd = pcpu_find(TDQ_ID(tdq))->pc_curthread; 600 td = tdq_choose(tdq); 601 if (td == NULL || td->td_priority > ctd->td_priority) 602 tdq->tdq_lowpri = ctd->td_priority; 603 else 604 tdq->tdq_lowpri = td->td_priority; 605 } 606 607 #ifdef SMP 608 struct cpu_search { 609 cpuset_t cs_mask; 610 u_int cs_prefer; 611 int cs_pri; /* Min priority for low. */ 612 int cs_limit; /* Max load for low, min load for high. */ 613 int cs_cpu; 614 int cs_load; 615 }; 616 617 #define CPU_SEARCH_LOWEST 0x1 618 #define CPU_SEARCH_HIGHEST 0x2 619 #define CPU_SEARCH_BOTH (CPU_SEARCH_LOWEST|CPU_SEARCH_HIGHEST) 620 621 #define CPUSET_FOREACH(cpu, mask) \ 622 for ((cpu) = 0; (cpu) <= mp_maxid; (cpu)++) \ 623 if (CPU_ISSET(cpu, &mask)) 624 625 static __always_inline int cpu_search(const struct cpu_group *cg, 626 struct cpu_search *low, struct cpu_search *high, const int match); 627 int __noinline cpu_search_lowest(const struct cpu_group *cg, 628 struct cpu_search *low); 629 int __noinline cpu_search_highest(const struct cpu_group *cg, 630 struct cpu_search *high); 631 int __noinline cpu_search_both(const struct cpu_group *cg, 632 struct cpu_search *low, struct cpu_search *high); 633 634 /* 635 * Search the tree of cpu_groups for the lowest or highest loaded cpu 636 * according to the match argument. This routine actually compares the 637 * load on all paths through the tree and finds the least loaded cpu on 638 * the least loaded path, which may differ from the least loaded cpu in 639 * the system. This balances work among caches and busses. 640 * 641 * This inline is instantiated in three forms below using constants for the 642 * match argument. It is reduced to the minimum set for each case. It is 643 * also recursive to the depth of the tree. 644 */ 645 static __always_inline int 646 cpu_search(const struct cpu_group *cg, struct cpu_search *low, 647 struct cpu_search *high, const int match) 648 { 649 struct cpu_search lgroup; 650 struct cpu_search hgroup; 651 cpuset_t cpumask; 652 struct cpu_group *child; 653 struct tdq *tdq; 654 int cpu, i, hload, lload, load, total, rnd, *rndptr; 655 656 total = 0; 657 cpumask = cg->cg_mask; 658 if (match & CPU_SEARCH_LOWEST) { 659 lload = INT_MAX; 660 lgroup = *low; 661 } 662 if (match & CPU_SEARCH_HIGHEST) { 663 hload = INT_MIN; 664 hgroup = *high; 665 } 666 667 /* Iterate through the child CPU groups and then remaining CPUs. */ 668 for (i = cg->cg_children, cpu = mp_maxid; ; ) { 669 if (i == 0) { 670 #ifdef HAVE_INLINE_FFSL 671 cpu = CPU_FFS(&cpumask) - 1; 672 #else 673 while (cpu >= 0 && !CPU_ISSET(cpu, &cpumask)) 674 cpu--; 675 #endif 676 if (cpu < 0) 677 break; 678 child = NULL; 679 } else 680 child = &cg->cg_child[i - 1]; 681 682 if (match & CPU_SEARCH_LOWEST) 683 lgroup.cs_cpu = -1; 684 if (match & CPU_SEARCH_HIGHEST) 685 hgroup.cs_cpu = -1; 686 if (child) { /* Handle child CPU group. */ 687 CPU_NAND(&cpumask, &child->cg_mask); 688 switch (match) { 689 case CPU_SEARCH_LOWEST: 690 load = cpu_search_lowest(child, &lgroup); 691 break; 692 case CPU_SEARCH_HIGHEST: 693 load = cpu_search_highest(child, &hgroup); 694 break; 695 case CPU_SEARCH_BOTH: 696 load = cpu_search_both(child, &lgroup, &hgroup); 697 break; 698 } 699 } else { /* Handle child CPU. */ 700 CPU_CLR(cpu, &cpumask); 701 tdq = TDQ_CPU(cpu); 702 load = tdq->tdq_load * 256; 703 rndptr = DPCPU_PTR(randomval); 704 rnd = (*rndptr = *rndptr * 69069 + 5) >> 26; 705 if (match & CPU_SEARCH_LOWEST) { 706 if (cpu == low->cs_prefer) 707 load -= 64; 708 /* If that CPU is allowed and get data. */ 709 if (tdq->tdq_lowpri > lgroup.cs_pri && 710 tdq->tdq_load <= lgroup.cs_limit && 711 CPU_ISSET(cpu, &lgroup.cs_mask)) { 712 lgroup.cs_cpu = cpu; 713 lgroup.cs_load = load - rnd; 714 } 715 } 716 if (match & CPU_SEARCH_HIGHEST) 717 if (tdq->tdq_load >= hgroup.cs_limit && 718 tdq->tdq_transferable && 719 CPU_ISSET(cpu, &hgroup.cs_mask)) { 720 hgroup.cs_cpu = cpu; 721 hgroup.cs_load = load - rnd; 722 } 723 } 724 total += load; 725 726 /* We have info about child item. Compare it. */ 727 if (match & CPU_SEARCH_LOWEST) { 728 if (lgroup.cs_cpu >= 0 && 729 (load < lload || 730 (load == lload && lgroup.cs_load < low->cs_load))) { 731 lload = load; 732 low->cs_cpu = lgroup.cs_cpu; 733 low->cs_load = lgroup.cs_load; 734 } 735 } 736 if (match & CPU_SEARCH_HIGHEST) 737 if (hgroup.cs_cpu >= 0 && 738 (load > hload || 739 (load == hload && hgroup.cs_load > high->cs_load))) { 740 hload = load; 741 high->cs_cpu = hgroup.cs_cpu; 742 high->cs_load = hgroup.cs_load; 743 } 744 if (child) { 745 i--; 746 if (i == 0 && CPU_EMPTY(&cpumask)) 747 break; 748 } 749 #ifndef HAVE_INLINE_FFSL 750 else 751 cpu--; 752 #endif 753 } 754 return (total); 755 } 756 757 /* 758 * cpu_search instantiations must pass constants to maintain the inline 759 * optimization. 760 */ 761 int 762 cpu_search_lowest(const struct cpu_group *cg, struct cpu_search *low) 763 { 764 return cpu_search(cg, low, NULL, CPU_SEARCH_LOWEST); 765 } 766 767 int 768 cpu_search_highest(const struct cpu_group *cg, struct cpu_search *high) 769 { 770 return cpu_search(cg, NULL, high, CPU_SEARCH_HIGHEST); 771 } 772 773 int 774 cpu_search_both(const struct cpu_group *cg, struct cpu_search *low, 775 struct cpu_search *high) 776 { 777 return cpu_search(cg, low, high, CPU_SEARCH_BOTH); 778 } 779 780 /* 781 * Find the cpu with the least load via the least loaded path that has a 782 * lowpri greater than pri pri. A pri of -1 indicates any priority is 783 * acceptable. 784 */ 785 static inline int 786 sched_lowest(const struct cpu_group *cg, cpuset_t mask, int pri, int maxload, 787 int prefer) 788 { 789 struct cpu_search low; 790 791 low.cs_cpu = -1; 792 low.cs_prefer = prefer; 793 low.cs_mask = mask; 794 low.cs_pri = pri; 795 low.cs_limit = maxload; 796 cpu_search_lowest(cg, &low); 797 return low.cs_cpu; 798 } 799 800 /* 801 * Find the cpu with the highest load via the highest loaded path. 802 */ 803 static inline int 804 sched_highest(const struct cpu_group *cg, cpuset_t mask, int minload) 805 { 806 struct cpu_search high; 807 808 high.cs_cpu = -1; 809 high.cs_mask = mask; 810 high.cs_limit = minload; 811 cpu_search_highest(cg, &high); 812 return high.cs_cpu; 813 } 814 815 static void 816 sched_balance_group(struct cpu_group *cg) 817 { 818 cpuset_t hmask, lmask; 819 int high, low, anylow; 820 821 CPU_FILL(&hmask); 822 for (;;) { 823 high = sched_highest(cg, hmask, 1); 824 /* Stop if there is no more CPU with transferrable threads. */ 825 if (high == -1) 826 break; 827 CPU_CLR(high, &hmask); 828 CPU_COPY(&hmask, &lmask); 829 /* Stop if there is no more CPU left for low. */ 830 if (CPU_EMPTY(&lmask)) 831 break; 832 anylow = 1; 833 nextlow: 834 low = sched_lowest(cg, lmask, -1, 835 TDQ_CPU(high)->tdq_load - 1, high); 836 /* Stop if we looked well and found no less loaded CPU. */ 837 if (anylow && low == -1) 838 break; 839 /* Go to next high if we found no less loaded CPU. */ 840 if (low == -1) 841 continue; 842 /* Transfer thread from high to low. */ 843 if (sched_balance_pair(TDQ_CPU(high), TDQ_CPU(low))) { 844 /* CPU that got thread can no longer be a donor. */ 845 CPU_CLR(low, &hmask); 846 } else { 847 /* 848 * If failed, then there is no threads on high 849 * that can run on this low. Drop low from low 850 * mask and look for different one. 851 */ 852 CPU_CLR(low, &lmask); 853 anylow = 0; 854 goto nextlow; 855 } 856 } 857 } 858 859 static void 860 sched_balance(void) 861 { 862 struct tdq *tdq; 863 864 /* 865 * Select a random time between .5 * balance_interval and 866 * 1.5 * balance_interval. 867 */ 868 balance_ticks = max(balance_interval / 2, 1); 869 balance_ticks += random() % balance_interval; 870 if (smp_started == 0 || rebalance == 0) 871 return; 872 tdq = TDQ_SELF(); 873 TDQ_UNLOCK(tdq); 874 sched_balance_group(cpu_top); 875 TDQ_LOCK(tdq); 876 } 877 878 /* 879 * Lock two thread queues using their address to maintain lock order. 880 */ 881 static void 882 tdq_lock_pair(struct tdq *one, struct tdq *two) 883 { 884 if (one < two) { 885 TDQ_LOCK(one); 886 TDQ_LOCK_FLAGS(two, MTX_DUPOK); 887 } else { 888 TDQ_LOCK(two); 889 TDQ_LOCK_FLAGS(one, MTX_DUPOK); 890 } 891 } 892 893 /* 894 * Unlock two thread queues. Order is not important here. 895 */ 896 static void 897 tdq_unlock_pair(struct tdq *one, struct tdq *two) 898 { 899 TDQ_UNLOCK(one); 900 TDQ_UNLOCK(two); 901 } 902 903 /* 904 * Transfer load between two imbalanced thread queues. 905 */ 906 static int 907 sched_balance_pair(struct tdq *high, struct tdq *low) 908 { 909 int moved; 910 int cpu; 911 912 tdq_lock_pair(high, low); 913 moved = 0; 914 /* 915 * Determine what the imbalance is and then adjust that to how many 916 * threads we actually have to give up (transferable). 917 */ 918 if (high->tdq_transferable != 0 && high->tdq_load > low->tdq_load && 919 (moved = tdq_move(high, low)) > 0) { 920 /* 921 * In case the target isn't the current cpu IPI it to force a 922 * reschedule with the new workload. 923 */ 924 cpu = TDQ_ID(low); 925 if (cpu != PCPU_GET(cpuid)) 926 ipi_cpu(cpu, IPI_PREEMPT); 927 } 928 tdq_unlock_pair(high, low); 929 return (moved); 930 } 931 932 /* 933 * Move a thread from one thread queue to another. 934 */ 935 static int 936 tdq_move(struct tdq *from, struct tdq *to) 937 { 938 struct td_sched *ts; 939 struct thread *td; 940 struct tdq *tdq; 941 int cpu; 942 943 TDQ_LOCK_ASSERT(from, MA_OWNED); 944 TDQ_LOCK_ASSERT(to, MA_OWNED); 945 946 tdq = from; 947 cpu = TDQ_ID(to); 948 td = tdq_steal(tdq, cpu); 949 if (td == NULL) 950 return (0); 951 ts = td->td_sched; 952 /* 953 * Although the run queue is locked the thread may be blocked. Lock 954 * it to clear this and acquire the run-queue lock. 955 */ 956 thread_lock(td); 957 /* Drop recursive lock on from acquired via thread_lock(). */ 958 TDQ_UNLOCK(from); 959 sched_rem(td); 960 ts->ts_cpu = cpu; 961 td->td_lock = TDQ_LOCKPTR(to); 962 tdq_add(to, td, SRQ_YIELDING); 963 return (1); 964 } 965 966 /* 967 * This tdq has idled. Try to steal a thread from another cpu and switch 968 * to it. 969 */ 970 static int 971 tdq_idled(struct tdq *tdq) 972 { 973 struct cpu_group *cg; 974 struct tdq *steal; 975 cpuset_t mask; 976 int thresh; 977 int cpu; 978 979 if (smp_started == 0 || steal_idle == 0) 980 return (1); 981 CPU_FILL(&mask); 982 CPU_CLR(PCPU_GET(cpuid), &mask); 983 /* We don't want to be preempted while we're iterating. */ 984 spinlock_enter(); 985 for (cg = tdq->tdq_cg; cg != NULL; ) { 986 if ((cg->cg_flags & CG_FLAG_THREAD) == 0) 987 thresh = steal_thresh; 988 else 989 thresh = 1; 990 cpu = sched_highest(cg, mask, thresh); 991 if (cpu == -1) { 992 cg = cg->cg_parent; 993 continue; 994 } 995 steal = TDQ_CPU(cpu); 996 CPU_CLR(cpu, &mask); 997 tdq_lock_pair(tdq, steal); 998 if (steal->tdq_load < thresh || steal->tdq_transferable == 0) { 999 tdq_unlock_pair(tdq, steal); 1000 continue; 1001 } 1002 /* 1003 * If a thread was added while interrupts were disabled don't 1004 * steal one here. If we fail to acquire one due to affinity 1005 * restrictions loop again with this cpu removed from the 1006 * set. 1007 */ 1008 if (tdq->tdq_load == 0 && tdq_move(steal, tdq) == 0) { 1009 tdq_unlock_pair(tdq, steal); 1010 continue; 1011 } 1012 spinlock_exit(); 1013 TDQ_UNLOCK(steal); 1014 mi_switch(SW_VOL | SWT_IDLE, NULL); 1015 thread_unlock(curthread); 1016 1017 return (0); 1018 } 1019 spinlock_exit(); 1020 return (1); 1021 } 1022 1023 /* 1024 * Notify a remote cpu of new work. Sends an IPI if criteria are met. 1025 */ 1026 static void 1027 tdq_notify(struct tdq *tdq, struct thread *td) 1028 { 1029 struct thread *ctd; 1030 int pri; 1031 int cpu; 1032 1033 if (tdq->tdq_ipipending) 1034 return; 1035 cpu = td->td_sched->ts_cpu; 1036 pri = td->td_priority; 1037 ctd = pcpu_find(cpu)->pc_curthread; 1038 if (!sched_shouldpreempt(pri, ctd->td_priority, 1)) 1039 return; 1040 1041 /* 1042 * Make sure that our caller's earlier update to tdq_load is 1043 * globally visible before we read tdq_cpu_idle. Idle thread 1044 * accesses both of them without locks, and the order is important. 1045 */ 1046 mb(); 1047 1048 if (TD_IS_IDLETHREAD(ctd)) { 1049 /* 1050 * If the MD code has an idle wakeup routine try that before 1051 * falling back to IPI. 1052 */ 1053 if (!tdq->tdq_cpu_idle || cpu_idle_wakeup(cpu)) 1054 return; 1055 } 1056 tdq->tdq_ipipending = 1; 1057 ipi_cpu(cpu, IPI_PREEMPT); 1058 } 1059 1060 /* 1061 * Steals load from a timeshare queue. Honors the rotating queue head 1062 * index. 1063 */ 1064 static struct thread * 1065 runq_steal_from(struct runq *rq, int cpu, u_char start) 1066 { 1067 struct rqbits *rqb; 1068 struct rqhead *rqh; 1069 struct thread *td, *first; 1070 int bit; 1071 int i; 1072 1073 rqb = &rq->rq_status; 1074 bit = start & (RQB_BPW -1); 1075 first = NULL; 1076 again: 1077 for (i = RQB_WORD(start); i < RQB_LEN; bit = 0, i++) { 1078 if (rqb->rqb_bits[i] == 0) 1079 continue; 1080 if (bit == 0) 1081 bit = RQB_FFS(rqb->rqb_bits[i]); 1082 for (; bit < RQB_BPW; bit++) { 1083 if ((rqb->rqb_bits[i] & (1ul << bit)) == 0) 1084 continue; 1085 rqh = &rq->rq_queues[bit + (i << RQB_L2BPW)]; 1086 TAILQ_FOREACH(td, rqh, td_runq) { 1087 if (first && THREAD_CAN_MIGRATE(td) && 1088 THREAD_CAN_SCHED(td, cpu)) 1089 return (td); 1090 first = td; 1091 } 1092 } 1093 } 1094 if (start != 0) { 1095 start = 0; 1096 goto again; 1097 } 1098 1099 if (first && THREAD_CAN_MIGRATE(first) && 1100 THREAD_CAN_SCHED(first, cpu)) 1101 return (first); 1102 return (NULL); 1103 } 1104 1105 /* 1106 * Steals load from a standard linear queue. 1107 */ 1108 static struct thread * 1109 runq_steal(struct runq *rq, int cpu) 1110 { 1111 struct rqhead *rqh; 1112 struct rqbits *rqb; 1113 struct thread *td; 1114 int word; 1115 int bit; 1116 1117 rqb = &rq->rq_status; 1118 for (word = 0; word < RQB_LEN; word++) { 1119 if (rqb->rqb_bits[word] == 0) 1120 continue; 1121 for (bit = 0; bit < RQB_BPW; bit++) { 1122 if ((rqb->rqb_bits[word] & (1ul << bit)) == 0) 1123 continue; 1124 rqh = &rq->rq_queues[bit + (word << RQB_L2BPW)]; 1125 TAILQ_FOREACH(td, rqh, td_runq) 1126 if (THREAD_CAN_MIGRATE(td) && 1127 THREAD_CAN_SCHED(td, cpu)) 1128 return (td); 1129 } 1130 } 1131 return (NULL); 1132 } 1133 1134 /* 1135 * Attempt to steal a thread in priority order from a thread queue. 1136 */ 1137 static struct thread * 1138 tdq_steal(struct tdq *tdq, int cpu) 1139 { 1140 struct thread *td; 1141 1142 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1143 if ((td = runq_steal(&tdq->tdq_realtime, cpu)) != NULL) 1144 return (td); 1145 if ((td = runq_steal_from(&tdq->tdq_timeshare, 1146 cpu, tdq->tdq_ridx)) != NULL) 1147 return (td); 1148 return (runq_steal(&tdq->tdq_idle, cpu)); 1149 } 1150 1151 /* 1152 * Sets the thread lock and ts_cpu to match the requested cpu. Unlocks the 1153 * current lock and returns with the assigned queue locked. 1154 */ 1155 static inline struct tdq * 1156 sched_setcpu(struct thread *td, int cpu, int flags) 1157 { 1158 1159 struct tdq *tdq; 1160 1161 THREAD_LOCK_ASSERT(td, MA_OWNED); 1162 tdq = TDQ_CPU(cpu); 1163 td->td_sched->ts_cpu = cpu; 1164 /* 1165 * If the lock matches just return the queue. 1166 */ 1167 if (td->td_lock == TDQ_LOCKPTR(tdq)) 1168 return (tdq); 1169 #ifdef notyet 1170 /* 1171 * If the thread isn't running its lockptr is a 1172 * turnstile or a sleepqueue. We can just lock_set without 1173 * blocking. 1174 */ 1175 if (TD_CAN_RUN(td)) { 1176 TDQ_LOCK(tdq); 1177 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 1178 return (tdq); 1179 } 1180 #endif 1181 /* 1182 * The hard case, migration, we need to block the thread first to 1183 * prevent order reversals with other cpus locks. 1184 */ 1185 spinlock_enter(); 1186 thread_lock_block(td); 1187 TDQ_LOCK(tdq); 1188 thread_lock_unblock(td, TDQ_LOCKPTR(tdq)); 1189 spinlock_exit(); 1190 return (tdq); 1191 } 1192 1193 SCHED_STAT_DEFINE(pickcpu_intrbind, "Soft interrupt binding"); 1194 SCHED_STAT_DEFINE(pickcpu_idle_affinity, "Picked idle cpu based on affinity"); 1195 SCHED_STAT_DEFINE(pickcpu_affinity, "Picked cpu based on affinity"); 1196 SCHED_STAT_DEFINE(pickcpu_lowest, "Selected lowest load"); 1197 SCHED_STAT_DEFINE(pickcpu_local, "Migrated to current cpu"); 1198 SCHED_STAT_DEFINE(pickcpu_migration, "Selection may have caused migration"); 1199 1200 static int 1201 sched_pickcpu(struct thread *td, int flags) 1202 { 1203 struct cpu_group *cg, *ccg; 1204 struct td_sched *ts; 1205 struct tdq *tdq; 1206 cpuset_t mask; 1207 int cpu, pri, self; 1208 1209 self = PCPU_GET(cpuid); 1210 ts = td->td_sched; 1211 if (smp_started == 0) 1212 return (self); 1213 /* 1214 * Don't migrate a running thread from sched_switch(). 1215 */ 1216 if ((flags & SRQ_OURSELF) || !THREAD_CAN_MIGRATE(td)) 1217 return (ts->ts_cpu); 1218 /* 1219 * Prefer to run interrupt threads on the processors that generate 1220 * the interrupt. 1221 */ 1222 pri = td->td_priority; 1223 if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_SCHED(td, self) && 1224 curthread->td_intr_nesting_level && ts->ts_cpu != self) { 1225 SCHED_STAT_INC(pickcpu_intrbind); 1226 ts->ts_cpu = self; 1227 if (TDQ_CPU(self)->tdq_lowpri > pri) { 1228 SCHED_STAT_INC(pickcpu_affinity); 1229 return (ts->ts_cpu); 1230 } 1231 } 1232 /* 1233 * If the thread can run on the last cpu and the affinity has not 1234 * expired or it is idle run it there. 1235 */ 1236 tdq = TDQ_CPU(ts->ts_cpu); 1237 cg = tdq->tdq_cg; 1238 if (THREAD_CAN_SCHED(td, ts->ts_cpu) && 1239 tdq->tdq_lowpri >= PRI_MIN_IDLE && 1240 SCHED_AFFINITY(ts, CG_SHARE_L2)) { 1241 if (cg->cg_flags & CG_FLAG_THREAD) { 1242 CPUSET_FOREACH(cpu, cg->cg_mask) { 1243 if (TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE) 1244 break; 1245 } 1246 } else 1247 cpu = INT_MAX; 1248 if (cpu > mp_maxid) { 1249 SCHED_STAT_INC(pickcpu_idle_affinity); 1250 return (ts->ts_cpu); 1251 } 1252 } 1253 /* 1254 * Search for the last level cache CPU group in the tree. 1255 * Skip caches with expired affinity time and SMT groups. 1256 * Affinity to higher level caches will be handled less aggressively. 1257 */ 1258 for (ccg = NULL; cg != NULL; cg = cg->cg_parent) { 1259 if (cg->cg_flags & CG_FLAG_THREAD) 1260 continue; 1261 if (!SCHED_AFFINITY(ts, cg->cg_level)) 1262 continue; 1263 ccg = cg; 1264 } 1265 if (ccg != NULL) 1266 cg = ccg; 1267 cpu = -1; 1268 /* Search the group for the less loaded idle CPU we can run now. */ 1269 mask = td->td_cpuset->cs_mask; 1270 if (cg != NULL && cg != cpu_top && 1271 CPU_CMP(&cg->cg_mask, &cpu_top->cg_mask) != 0) 1272 cpu = sched_lowest(cg, mask, max(pri, PRI_MAX_TIMESHARE), 1273 INT_MAX, ts->ts_cpu); 1274 /* Search globally for the less loaded CPU we can run now. */ 1275 if (cpu == -1) 1276 cpu = sched_lowest(cpu_top, mask, pri, INT_MAX, ts->ts_cpu); 1277 /* Search globally for the less loaded CPU. */ 1278 if (cpu == -1) 1279 cpu = sched_lowest(cpu_top, mask, -1, INT_MAX, ts->ts_cpu); 1280 KASSERT(cpu != -1, ("sched_pickcpu: Failed to find a cpu.")); 1281 /* 1282 * Compare the lowest loaded cpu to current cpu. 1283 */ 1284 if (THREAD_CAN_SCHED(td, self) && TDQ_CPU(self)->tdq_lowpri > pri && 1285 TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE && 1286 TDQ_CPU(self)->tdq_load <= TDQ_CPU(cpu)->tdq_load + 1) { 1287 SCHED_STAT_INC(pickcpu_local); 1288 cpu = self; 1289 } else 1290 SCHED_STAT_INC(pickcpu_lowest); 1291 if (cpu != ts->ts_cpu) 1292 SCHED_STAT_INC(pickcpu_migration); 1293 return (cpu); 1294 } 1295 #endif 1296 1297 /* 1298 * Pick the highest priority task we have and return it. 1299 */ 1300 static struct thread * 1301 tdq_choose(struct tdq *tdq) 1302 { 1303 struct thread *td; 1304 1305 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1306 td = runq_choose(&tdq->tdq_realtime); 1307 if (td != NULL) 1308 return (td); 1309 td = runq_choose_from(&tdq->tdq_timeshare, tdq->tdq_ridx); 1310 if (td != NULL) { 1311 KASSERT(td->td_priority >= PRI_MIN_BATCH, 1312 ("tdq_choose: Invalid priority on timeshare queue %d", 1313 td->td_priority)); 1314 return (td); 1315 } 1316 td = runq_choose(&tdq->tdq_idle); 1317 if (td != NULL) { 1318 KASSERT(td->td_priority >= PRI_MIN_IDLE, 1319 ("tdq_choose: Invalid priority on idle queue %d", 1320 td->td_priority)); 1321 return (td); 1322 } 1323 1324 return (NULL); 1325 } 1326 1327 /* 1328 * Initialize a thread queue. 1329 */ 1330 static void 1331 tdq_setup(struct tdq *tdq) 1332 { 1333 1334 if (bootverbose) 1335 printf("ULE: setup cpu %d\n", TDQ_ID(tdq)); 1336 runq_init(&tdq->tdq_realtime); 1337 runq_init(&tdq->tdq_timeshare); 1338 runq_init(&tdq->tdq_idle); 1339 snprintf(tdq->tdq_name, sizeof(tdq->tdq_name), 1340 "sched lock %d", (int)TDQ_ID(tdq)); 1341 mtx_init(&tdq->tdq_lock, tdq->tdq_name, "sched lock", 1342 MTX_SPIN | MTX_RECURSE); 1343 #ifdef KTR 1344 snprintf(tdq->tdq_loadname, sizeof(tdq->tdq_loadname), 1345 "CPU %d load", (int)TDQ_ID(tdq)); 1346 #endif 1347 } 1348 1349 #ifdef SMP 1350 static void 1351 sched_setup_smp(void) 1352 { 1353 struct tdq *tdq; 1354 int i; 1355 1356 cpu_top = smp_topo(); 1357 CPU_FOREACH(i) { 1358 tdq = TDQ_CPU(i); 1359 tdq_setup(tdq); 1360 tdq->tdq_cg = smp_topo_find(cpu_top, i); 1361 if (tdq->tdq_cg == NULL) 1362 panic("Can't find cpu group for %d\n", i); 1363 } 1364 balance_tdq = TDQ_SELF(); 1365 sched_balance(); 1366 } 1367 #endif 1368 1369 /* 1370 * Setup the thread queues and initialize the topology based on MD 1371 * information. 1372 */ 1373 static void 1374 sched_setup(void *dummy) 1375 { 1376 struct tdq *tdq; 1377 1378 tdq = TDQ_SELF(); 1379 #ifdef SMP 1380 sched_setup_smp(); 1381 #else 1382 tdq_setup(tdq); 1383 #endif 1384 1385 /* Add thread0's load since it's running. */ 1386 TDQ_LOCK(tdq); 1387 thread0.td_lock = TDQ_LOCKPTR(TDQ_SELF()); 1388 tdq_load_add(tdq, &thread0); 1389 tdq->tdq_lowpri = thread0.td_priority; 1390 TDQ_UNLOCK(tdq); 1391 } 1392 1393 /* 1394 * This routine determines time constants after stathz and hz are setup. 1395 */ 1396 /* ARGSUSED */ 1397 static void 1398 sched_initticks(void *dummy) 1399 { 1400 int incr; 1401 1402 realstathz = stathz ? stathz : hz; 1403 sched_slice = realstathz / SCHED_SLICE_DEFAULT_DIVISOR; 1404 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 1405 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 1406 realstathz); 1407 1408 /* 1409 * tickincr is shifted out by 10 to avoid rounding errors due to 1410 * hz not being evenly divisible by stathz on all platforms. 1411 */ 1412 incr = (hz << SCHED_TICK_SHIFT) / realstathz; 1413 /* 1414 * This does not work for values of stathz that are more than 1415 * 1 << SCHED_TICK_SHIFT * hz. In practice this does not happen. 1416 */ 1417 if (incr == 0) 1418 incr = 1; 1419 tickincr = incr; 1420 #ifdef SMP 1421 /* 1422 * Set the default balance interval now that we know 1423 * what realstathz is. 1424 */ 1425 balance_interval = realstathz; 1426 affinity = SCHED_AFFINITY_DEFAULT; 1427 #endif 1428 if (sched_idlespinthresh < 0) 1429 sched_idlespinthresh = 2 * max(10000, 6 * hz) / realstathz; 1430 } 1431 1432 1433 /* 1434 * This is the core of the interactivity algorithm. Determines a score based 1435 * on past behavior. It is the ratio of sleep time to run time scaled to 1436 * a [0, 100] integer. This is the voluntary sleep time of a process, which 1437 * differs from the cpu usage because it does not account for time spent 1438 * waiting on a run-queue. Would be prettier if we had floating point. 1439 */ 1440 static int 1441 sched_interact_score(struct thread *td) 1442 { 1443 struct td_sched *ts; 1444 int div; 1445 1446 ts = td->td_sched; 1447 /* 1448 * The score is only needed if this is likely to be an interactive 1449 * task. Don't go through the expense of computing it if there's 1450 * no chance. 1451 */ 1452 if (sched_interact <= SCHED_INTERACT_HALF && 1453 ts->ts_runtime >= ts->ts_slptime) 1454 return (SCHED_INTERACT_HALF); 1455 1456 if (ts->ts_runtime > ts->ts_slptime) { 1457 div = max(1, ts->ts_runtime / SCHED_INTERACT_HALF); 1458 return (SCHED_INTERACT_HALF + 1459 (SCHED_INTERACT_HALF - (ts->ts_slptime / div))); 1460 } 1461 if (ts->ts_slptime > ts->ts_runtime) { 1462 div = max(1, ts->ts_slptime / SCHED_INTERACT_HALF); 1463 return (ts->ts_runtime / div); 1464 } 1465 /* runtime == slptime */ 1466 if (ts->ts_runtime) 1467 return (SCHED_INTERACT_HALF); 1468 1469 /* 1470 * This can happen if slptime and runtime are 0. 1471 */ 1472 return (0); 1473 1474 } 1475 1476 /* 1477 * Scale the scheduling priority according to the "interactivity" of this 1478 * process. 1479 */ 1480 static void 1481 sched_priority(struct thread *td) 1482 { 1483 int score; 1484 int pri; 1485 1486 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 1487 return; 1488 /* 1489 * If the score is interactive we place the thread in the realtime 1490 * queue with a priority that is less than kernel and interrupt 1491 * priorities. These threads are not subject to nice restrictions. 1492 * 1493 * Scores greater than this are placed on the normal timeshare queue 1494 * where the priority is partially decided by the most recent cpu 1495 * utilization and the rest is decided by nice value. 1496 * 1497 * The nice value of the process has a linear effect on the calculated 1498 * score. Negative nice values make it easier for a thread to be 1499 * considered interactive. 1500 */ 1501 score = imax(0, sched_interact_score(td) + td->td_proc->p_nice); 1502 if (score < sched_interact) { 1503 pri = PRI_MIN_INTERACT; 1504 pri += ((PRI_MAX_INTERACT - PRI_MIN_INTERACT + 1) / 1505 sched_interact) * score; 1506 KASSERT(pri >= PRI_MIN_INTERACT && pri <= PRI_MAX_INTERACT, 1507 ("sched_priority: invalid interactive priority %d score %d", 1508 pri, score)); 1509 } else { 1510 pri = SCHED_PRI_MIN; 1511 if (td->td_sched->ts_ticks) 1512 pri += min(SCHED_PRI_TICKS(td->td_sched), 1513 SCHED_PRI_RANGE - 1); 1514 pri += SCHED_PRI_NICE(td->td_proc->p_nice); 1515 KASSERT(pri >= PRI_MIN_BATCH && pri <= PRI_MAX_BATCH, 1516 ("sched_priority: invalid priority %d: nice %d, " 1517 "ticks %d ftick %d ltick %d tick pri %d", 1518 pri, td->td_proc->p_nice, td->td_sched->ts_ticks, 1519 td->td_sched->ts_ftick, td->td_sched->ts_ltick, 1520 SCHED_PRI_TICKS(td->td_sched))); 1521 } 1522 sched_user_prio(td, pri); 1523 1524 return; 1525 } 1526 1527 /* 1528 * This routine enforces a maximum limit on the amount of scheduling history 1529 * kept. It is called after either the slptime or runtime is adjusted. This 1530 * function is ugly due to integer math. 1531 */ 1532 static void 1533 sched_interact_update(struct thread *td) 1534 { 1535 struct td_sched *ts; 1536 u_int sum; 1537 1538 ts = td->td_sched; 1539 sum = ts->ts_runtime + ts->ts_slptime; 1540 if (sum < SCHED_SLP_RUN_MAX) 1541 return; 1542 /* 1543 * This only happens from two places: 1544 * 1) We have added an unusual amount of run time from fork_exit. 1545 * 2) We have added an unusual amount of sleep time from sched_sleep(). 1546 */ 1547 if (sum > SCHED_SLP_RUN_MAX * 2) { 1548 if (ts->ts_runtime > ts->ts_slptime) { 1549 ts->ts_runtime = SCHED_SLP_RUN_MAX; 1550 ts->ts_slptime = 1; 1551 } else { 1552 ts->ts_slptime = SCHED_SLP_RUN_MAX; 1553 ts->ts_runtime = 1; 1554 } 1555 return; 1556 } 1557 /* 1558 * If we have exceeded by more than 1/5th then the algorithm below 1559 * will not bring us back into range. Dividing by two here forces 1560 * us into the range of [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX] 1561 */ 1562 if (sum > (SCHED_SLP_RUN_MAX / 5) * 6) { 1563 ts->ts_runtime /= 2; 1564 ts->ts_slptime /= 2; 1565 return; 1566 } 1567 ts->ts_runtime = (ts->ts_runtime / 5) * 4; 1568 ts->ts_slptime = (ts->ts_slptime / 5) * 4; 1569 } 1570 1571 /* 1572 * Scale back the interactivity history when a child thread is created. The 1573 * history is inherited from the parent but the thread may behave totally 1574 * differently. For example, a shell spawning a compiler process. We want 1575 * to learn that the compiler is behaving badly very quickly. 1576 */ 1577 static void 1578 sched_interact_fork(struct thread *td) 1579 { 1580 int ratio; 1581 int sum; 1582 1583 sum = td->td_sched->ts_runtime + td->td_sched->ts_slptime; 1584 if (sum > SCHED_SLP_RUN_FORK) { 1585 ratio = sum / SCHED_SLP_RUN_FORK; 1586 td->td_sched->ts_runtime /= ratio; 1587 td->td_sched->ts_slptime /= ratio; 1588 } 1589 } 1590 1591 /* 1592 * Called from proc0_init() to setup the scheduler fields. 1593 */ 1594 void 1595 schedinit(void) 1596 { 1597 1598 /* 1599 * Set up the scheduler specific parts of proc0. 1600 */ 1601 proc0.p_sched = NULL; /* XXX */ 1602 thread0.td_sched = &td_sched0; 1603 td_sched0.ts_ltick = ticks; 1604 td_sched0.ts_ftick = ticks; 1605 td_sched0.ts_slice = 0; 1606 } 1607 1608 /* 1609 * This is only somewhat accurate since given many processes of the same 1610 * priority they will switch when their slices run out, which will be 1611 * at most sched_slice stathz ticks. 1612 */ 1613 int 1614 sched_rr_interval(void) 1615 { 1616 1617 /* Convert sched_slice from stathz to hz. */ 1618 return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz)); 1619 } 1620 1621 /* 1622 * Update the percent cpu tracking information when it is requested or 1623 * the total history exceeds the maximum. We keep a sliding history of 1624 * tick counts that slowly decays. This is less precise than the 4BSD 1625 * mechanism since it happens with less regular and frequent events. 1626 */ 1627 static void 1628 sched_pctcpu_update(struct td_sched *ts, int run) 1629 { 1630 int t = ticks; 1631 1632 if (t - ts->ts_ltick >= SCHED_TICK_TARG) { 1633 ts->ts_ticks = 0; 1634 ts->ts_ftick = t - SCHED_TICK_TARG; 1635 } else if (t - ts->ts_ftick >= SCHED_TICK_MAX) { 1636 ts->ts_ticks = (ts->ts_ticks / (ts->ts_ltick - ts->ts_ftick)) * 1637 (ts->ts_ltick - (t - SCHED_TICK_TARG)); 1638 ts->ts_ftick = t - SCHED_TICK_TARG; 1639 } 1640 if (run) 1641 ts->ts_ticks += (t - ts->ts_ltick) << SCHED_TICK_SHIFT; 1642 ts->ts_ltick = t; 1643 } 1644 1645 /* 1646 * Adjust the priority of a thread. Move it to the appropriate run-queue 1647 * if necessary. This is the back-end for several priority related 1648 * functions. 1649 */ 1650 static void 1651 sched_thread_priority(struct thread *td, u_char prio) 1652 { 1653 struct td_sched *ts; 1654 struct tdq *tdq; 1655 int oldpri; 1656 1657 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "prio", 1658 "prio:%d", td->td_priority, "new prio:%d", prio, 1659 KTR_ATTR_LINKED, sched_tdname(curthread)); 1660 SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio); 1661 if (td != curthread && prio < td->td_priority) { 1662 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread), 1663 "lend prio", "prio:%d", td->td_priority, "new prio:%d", 1664 prio, KTR_ATTR_LINKED, sched_tdname(td)); 1665 SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio, 1666 curthread); 1667 } 1668 ts = td->td_sched; 1669 THREAD_LOCK_ASSERT(td, MA_OWNED); 1670 if (td->td_priority == prio) 1671 return; 1672 /* 1673 * If the priority has been elevated due to priority 1674 * propagation, we may have to move ourselves to a new 1675 * queue. This could be optimized to not re-add in some 1676 * cases. 1677 */ 1678 if (TD_ON_RUNQ(td) && prio < td->td_priority) { 1679 sched_rem(td); 1680 td->td_priority = prio; 1681 sched_add(td, SRQ_BORROWING); 1682 return; 1683 } 1684 /* 1685 * If the thread is currently running we may have to adjust the lowpri 1686 * information so other cpus are aware of our current priority. 1687 */ 1688 if (TD_IS_RUNNING(td)) { 1689 tdq = TDQ_CPU(ts->ts_cpu); 1690 oldpri = td->td_priority; 1691 td->td_priority = prio; 1692 if (prio < tdq->tdq_lowpri) 1693 tdq->tdq_lowpri = prio; 1694 else if (tdq->tdq_lowpri == oldpri) 1695 tdq_setlowpri(tdq, td); 1696 return; 1697 } 1698 td->td_priority = prio; 1699 } 1700 1701 /* 1702 * Update a thread's priority when it is lent another thread's 1703 * priority. 1704 */ 1705 void 1706 sched_lend_prio(struct thread *td, u_char prio) 1707 { 1708 1709 td->td_flags |= TDF_BORROWING; 1710 sched_thread_priority(td, prio); 1711 } 1712 1713 /* 1714 * Restore a thread's priority when priority propagation is 1715 * over. The prio argument is the minimum priority the thread 1716 * needs to have to satisfy other possible priority lending 1717 * requests. If the thread's regular priority is less 1718 * important than prio, the thread will keep a priority boost 1719 * of prio. 1720 */ 1721 void 1722 sched_unlend_prio(struct thread *td, u_char prio) 1723 { 1724 u_char base_pri; 1725 1726 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 1727 td->td_base_pri <= PRI_MAX_TIMESHARE) 1728 base_pri = td->td_user_pri; 1729 else 1730 base_pri = td->td_base_pri; 1731 if (prio >= base_pri) { 1732 td->td_flags &= ~TDF_BORROWING; 1733 sched_thread_priority(td, base_pri); 1734 } else 1735 sched_lend_prio(td, prio); 1736 } 1737 1738 /* 1739 * Standard entry for setting the priority to an absolute value. 1740 */ 1741 void 1742 sched_prio(struct thread *td, u_char prio) 1743 { 1744 u_char oldprio; 1745 1746 /* First, update the base priority. */ 1747 td->td_base_pri = prio; 1748 1749 /* 1750 * If the thread is borrowing another thread's priority, don't 1751 * ever lower the priority. 1752 */ 1753 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 1754 return; 1755 1756 /* Change the real priority. */ 1757 oldprio = td->td_priority; 1758 sched_thread_priority(td, prio); 1759 1760 /* 1761 * If the thread is on a turnstile, then let the turnstile update 1762 * its state. 1763 */ 1764 if (TD_ON_LOCK(td) && oldprio != prio) 1765 turnstile_adjust(td, oldprio); 1766 } 1767 1768 /* 1769 * Set the base user priority, does not effect current running priority. 1770 */ 1771 void 1772 sched_user_prio(struct thread *td, u_char prio) 1773 { 1774 1775 td->td_base_user_pri = prio; 1776 if (td->td_lend_user_pri <= prio) 1777 return; 1778 td->td_user_pri = prio; 1779 } 1780 1781 void 1782 sched_lend_user_prio(struct thread *td, u_char prio) 1783 { 1784 1785 THREAD_LOCK_ASSERT(td, MA_OWNED); 1786 td->td_lend_user_pri = prio; 1787 td->td_user_pri = min(prio, td->td_base_user_pri); 1788 if (td->td_priority > td->td_user_pri) 1789 sched_prio(td, td->td_user_pri); 1790 else if (td->td_priority != td->td_user_pri) 1791 td->td_flags |= TDF_NEEDRESCHED; 1792 } 1793 1794 /* 1795 * Handle migration from sched_switch(). This happens only for 1796 * cpu binding. 1797 */ 1798 static struct mtx * 1799 sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags) 1800 { 1801 struct tdq *tdn; 1802 1803 tdn = TDQ_CPU(td->td_sched->ts_cpu); 1804 #ifdef SMP 1805 tdq_load_rem(tdq, td); 1806 /* 1807 * Do the lock dance required to avoid LOR. We grab an extra 1808 * spinlock nesting to prevent preemption while we're 1809 * not holding either run-queue lock. 1810 */ 1811 spinlock_enter(); 1812 thread_lock_block(td); /* This releases the lock on tdq. */ 1813 1814 /* 1815 * Acquire both run-queue locks before placing the thread on the new 1816 * run-queue to avoid deadlocks created by placing a thread with a 1817 * blocked lock on the run-queue of a remote processor. The deadlock 1818 * occurs when a third processor attempts to lock the two queues in 1819 * question while the target processor is spinning with its own 1820 * run-queue lock held while waiting for the blocked lock to clear. 1821 */ 1822 tdq_lock_pair(tdn, tdq); 1823 tdq_add(tdn, td, flags); 1824 tdq_notify(tdn, td); 1825 TDQ_UNLOCK(tdn); 1826 spinlock_exit(); 1827 #endif 1828 return (TDQ_LOCKPTR(tdn)); 1829 } 1830 1831 /* 1832 * Variadic version of thread_lock_unblock() that does not assume td_lock 1833 * is blocked. 1834 */ 1835 static inline void 1836 thread_unblock_switch(struct thread *td, struct mtx *mtx) 1837 { 1838 atomic_store_rel_ptr((volatile uintptr_t *)&td->td_lock, 1839 (uintptr_t)mtx); 1840 } 1841 1842 /* 1843 * Switch threads. This function has to handle threads coming in while 1844 * blocked for some reason, running, or idle. It also must deal with 1845 * migrating a thread from one queue to another as running threads may 1846 * be assigned elsewhere via binding. 1847 */ 1848 void 1849 sched_switch(struct thread *td, struct thread *newtd, int flags) 1850 { 1851 struct tdq *tdq; 1852 struct td_sched *ts; 1853 struct mtx *mtx; 1854 int srqflag; 1855 int cpuid, preempted; 1856 1857 THREAD_LOCK_ASSERT(td, MA_OWNED); 1858 KASSERT(newtd == NULL, ("sched_switch: Unsupported newtd argument")); 1859 1860 cpuid = PCPU_GET(cpuid); 1861 tdq = TDQ_CPU(cpuid); 1862 ts = td->td_sched; 1863 mtx = td->td_lock; 1864 sched_pctcpu_update(ts, 1); 1865 ts->ts_rltick = ticks; 1866 td->td_lastcpu = td->td_oncpu; 1867 td->td_oncpu = NOCPU; 1868 preempted = !((td->td_flags & TDF_SLICEEND) || 1869 (flags & SWT_RELINQUISH)); 1870 td->td_flags &= ~(TDF_NEEDRESCHED | TDF_SLICEEND); 1871 td->td_owepreempt = 0; 1872 if (!TD_IS_IDLETHREAD(td)) 1873 tdq->tdq_switchcnt++; 1874 /* 1875 * The lock pointer in an idle thread should never change. Reset it 1876 * to CAN_RUN as well. 1877 */ 1878 if (TD_IS_IDLETHREAD(td)) { 1879 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1880 TD_SET_CAN_RUN(td); 1881 } else if (TD_IS_RUNNING(td)) { 1882 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1883 srqflag = preempted ? 1884 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 1885 SRQ_OURSELF|SRQ_YIELDING; 1886 #ifdef SMP 1887 if (THREAD_CAN_MIGRATE(td) && !THREAD_CAN_SCHED(td, ts->ts_cpu)) 1888 ts->ts_cpu = sched_pickcpu(td, 0); 1889 #endif 1890 if (ts->ts_cpu == cpuid) 1891 tdq_runq_add(tdq, td, srqflag); 1892 else { 1893 KASSERT(THREAD_CAN_MIGRATE(td) || 1894 (ts->ts_flags & TSF_BOUND) != 0, 1895 ("Thread %p shouldn't migrate", td)); 1896 mtx = sched_switch_migrate(tdq, td, srqflag); 1897 } 1898 } else { 1899 /* This thread must be going to sleep. */ 1900 TDQ_LOCK(tdq); 1901 mtx = thread_lock_block(td); 1902 tdq_load_rem(tdq, td); 1903 } 1904 /* 1905 * We enter here with the thread blocked and assigned to the 1906 * appropriate cpu run-queue or sleep-queue and with the current 1907 * thread-queue locked. 1908 */ 1909 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 1910 newtd = choosethread(); 1911 /* 1912 * Call the MD code to switch contexts if necessary. 1913 */ 1914 if (td != newtd) { 1915 #ifdef HWPMC_HOOKS 1916 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1917 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 1918 #endif 1919 SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc); 1920 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 1921 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 1922 sched_pctcpu_update(newtd->td_sched, 0); 1923 1924 #ifdef KDTRACE_HOOKS 1925 /* 1926 * If DTrace has set the active vtime enum to anything 1927 * other than INACTIVE (0), then it should have set the 1928 * function to call. 1929 */ 1930 if (dtrace_vtime_active) 1931 (*dtrace_vtime_switch_func)(newtd); 1932 #endif 1933 1934 cpu_switch(td, newtd, mtx); 1935 /* 1936 * We may return from cpu_switch on a different cpu. However, 1937 * we always return with td_lock pointing to the current cpu's 1938 * run queue lock. 1939 */ 1940 cpuid = PCPU_GET(cpuid); 1941 tdq = TDQ_CPU(cpuid); 1942 lock_profile_obtain_lock_success( 1943 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 1944 1945 SDT_PROBE0(sched, , , on__cpu); 1946 #ifdef HWPMC_HOOKS 1947 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1948 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 1949 #endif 1950 } else { 1951 thread_unblock_switch(td, mtx); 1952 SDT_PROBE0(sched, , , remain__cpu); 1953 } 1954 /* 1955 * Assert that all went well and return. 1956 */ 1957 TDQ_LOCK_ASSERT(tdq, MA_OWNED|MA_NOTRECURSED); 1958 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1959 td->td_oncpu = cpuid; 1960 } 1961 1962 /* 1963 * Adjust thread priorities as a result of a nice request. 1964 */ 1965 void 1966 sched_nice(struct proc *p, int nice) 1967 { 1968 struct thread *td; 1969 1970 PROC_LOCK_ASSERT(p, MA_OWNED); 1971 1972 p->p_nice = nice; 1973 FOREACH_THREAD_IN_PROC(p, td) { 1974 thread_lock(td); 1975 sched_priority(td); 1976 sched_prio(td, td->td_base_user_pri); 1977 thread_unlock(td); 1978 } 1979 } 1980 1981 /* 1982 * Record the sleep time for the interactivity scorer. 1983 */ 1984 void 1985 sched_sleep(struct thread *td, int prio) 1986 { 1987 1988 THREAD_LOCK_ASSERT(td, MA_OWNED); 1989 1990 td->td_slptick = ticks; 1991 if (TD_IS_SUSPENDED(td) || prio >= PSOCK) 1992 td->td_flags |= TDF_CANSWAP; 1993 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 1994 return; 1995 if (static_boost == 1 && prio) 1996 sched_prio(td, prio); 1997 else if (static_boost && td->td_priority > static_boost) 1998 sched_prio(td, static_boost); 1999 } 2000 2001 /* 2002 * Schedule a thread to resume execution and record how long it voluntarily 2003 * slept. We also update the pctcpu, interactivity, and priority. 2004 */ 2005 void 2006 sched_wakeup(struct thread *td) 2007 { 2008 struct td_sched *ts; 2009 int slptick; 2010 2011 THREAD_LOCK_ASSERT(td, MA_OWNED); 2012 ts = td->td_sched; 2013 td->td_flags &= ~TDF_CANSWAP; 2014 /* 2015 * If we slept for more than a tick update our interactivity and 2016 * priority. 2017 */ 2018 slptick = td->td_slptick; 2019 td->td_slptick = 0; 2020 if (slptick && slptick != ticks) { 2021 ts->ts_slptime += (ticks - slptick) << SCHED_TICK_SHIFT; 2022 sched_interact_update(td); 2023 sched_pctcpu_update(ts, 0); 2024 } 2025 /* 2026 * Reset the slice value since we slept and advanced the round-robin. 2027 */ 2028 ts->ts_slice = 0; 2029 sched_add(td, SRQ_BORING); 2030 } 2031 2032 /* 2033 * Penalize the parent for creating a new child and initialize the child's 2034 * priority. 2035 */ 2036 void 2037 sched_fork(struct thread *td, struct thread *child) 2038 { 2039 THREAD_LOCK_ASSERT(td, MA_OWNED); 2040 sched_pctcpu_update(td->td_sched, 1); 2041 sched_fork_thread(td, child); 2042 /* 2043 * Penalize the parent and child for forking. 2044 */ 2045 sched_interact_fork(child); 2046 sched_priority(child); 2047 td->td_sched->ts_runtime += tickincr; 2048 sched_interact_update(td); 2049 sched_priority(td); 2050 } 2051 2052 /* 2053 * Fork a new thread, may be within the same process. 2054 */ 2055 void 2056 sched_fork_thread(struct thread *td, struct thread *child) 2057 { 2058 struct td_sched *ts; 2059 struct td_sched *ts2; 2060 struct tdq *tdq; 2061 2062 tdq = TDQ_SELF(); 2063 THREAD_LOCK_ASSERT(td, MA_OWNED); 2064 /* 2065 * Initialize child. 2066 */ 2067 ts = td->td_sched; 2068 ts2 = child->td_sched; 2069 child->td_lock = TDQ_LOCKPTR(tdq); 2070 child->td_cpuset = cpuset_ref(td->td_cpuset); 2071 ts2->ts_cpu = ts->ts_cpu; 2072 ts2->ts_flags = 0; 2073 /* 2074 * Grab our parents cpu estimation information. 2075 */ 2076 ts2->ts_ticks = ts->ts_ticks; 2077 ts2->ts_ltick = ts->ts_ltick; 2078 ts2->ts_ftick = ts->ts_ftick; 2079 /* 2080 * Do not inherit any borrowed priority from the parent. 2081 */ 2082 child->td_priority = child->td_base_pri; 2083 /* 2084 * And update interactivity score. 2085 */ 2086 ts2->ts_slptime = ts->ts_slptime; 2087 ts2->ts_runtime = ts->ts_runtime; 2088 /* Attempt to quickly learn interactivity. */ 2089 ts2->ts_slice = tdq_slice(tdq) - sched_slice_min; 2090 #ifdef KTR 2091 bzero(ts2->ts_name, sizeof(ts2->ts_name)); 2092 #endif 2093 } 2094 2095 /* 2096 * Adjust the priority class of a thread. 2097 */ 2098 void 2099 sched_class(struct thread *td, int class) 2100 { 2101 2102 THREAD_LOCK_ASSERT(td, MA_OWNED); 2103 if (td->td_pri_class == class) 2104 return; 2105 td->td_pri_class = class; 2106 } 2107 2108 /* 2109 * Return some of the child's priority and interactivity to the parent. 2110 */ 2111 void 2112 sched_exit(struct proc *p, struct thread *child) 2113 { 2114 struct thread *td; 2115 2116 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "proc exit", 2117 "prio:%d", child->td_priority); 2118 PROC_LOCK_ASSERT(p, MA_OWNED); 2119 td = FIRST_THREAD_IN_PROC(p); 2120 sched_exit_thread(td, child); 2121 } 2122 2123 /* 2124 * Penalize another thread for the time spent on this one. This helps to 2125 * worsen the priority and interactivity of processes which schedule batch 2126 * jobs such as make. This has little effect on the make process itself but 2127 * causes new processes spawned by it to receive worse scores immediately. 2128 */ 2129 void 2130 sched_exit_thread(struct thread *td, struct thread *child) 2131 { 2132 2133 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "thread exit", 2134 "prio:%d", child->td_priority); 2135 /* 2136 * Give the child's runtime to the parent without returning the 2137 * sleep time as a penalty to the parent. This causes shells that 2138 * launch expensive things to mark their children as expensive. 2139 */ 2140 thread_lock(td); 2141 td->td_sched->ts_runtime += child->td_sched->ts_runtime; 2142 sched_interact_update(td); 2143 sched_priority(td); 2144 thread_unlock(td); 2145 } 2146 2147 void 2148 sched_preempt(struct thread *td) 2149 { 2150 struct tdq *tdq; 2151 2152 SDT_PROBE2(sched, , , surrender, td, td->td_proc); 2153 2154 thread_lock(td); 2155 tdq = TDQ_SELF(); 2156 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2157 tdq->tdq_ipipending = 0; 2158 if (td->td_priority > tdq->tdq_lowpri) { 2159 int flags; 2160 2161 flags = SW_INVOL | SW_PREEMPT; 2162 if (td->td_critnest > 1) 2163 td->td_owepreempt = 1; 2164 else if (TD_IS_IDLETHREAD(td)) 2165 mi_switch(flags | SWT_REMOTEWAKEIDLE, NULL); 2166 else 2167 mi_switch(flags | SWT_REMOTEPREEMPT, NULL); 2168 } 2169 thread_unlock(td); 2170 } 2171 2172 /* 2173 * Fix priorities on return to user-space. Priorities may be elevated due 2174 * to static priorities in msleep() or similar. 2175 */ 2176 void 2177 sched_userret(struct thread *td) 2178 { 2179 /* 2180 * XXX we cheat slightly on the locking here to avoid locking in 2181 * the usual case. Setting td_priority here is essentially an 2182 * incomplete workaround for not setting it properly elsewhere. 2183 * Now that some interrupt handlers are threads, not setting it 2184 * properly elsewhere can clobber it in the window between setting 2185 * it here and returning to user mode, so don't waste time setting 2186 * it perfectly here. 2187 */ 2188 KASSERT((td->td_flags & TDF_BORROWING) == 0, 2189 ("thread with borrowed priority returning to userland")); 2190 if (td->td_priority != td->td_user_pri) { 2191 thread_lock(td); 2192 td->td_priority = td->td_user_pri; 2193 td->td_base_pri = td->td_user_pri; 2194 tdq_setlowpri(TDQ_SELF(), td); 2195 thread_unlock(td); 2196 } 2197 } 2198 2199 /* 2200 * Handle a stathz tick. This is really only relevant for timeshare 2201 * threads. 2202 */ 2203 void 2204 sched_clock(struct thread *td) 2205 { 2206 struct tdq *tdq; 2207 struct td_sched *ts; 2208 2209 THREAD_LOCK_ASSERT(td, MA_OWNED); 2210 tdq = TDQ_SELF(); 2211 #ifdef SMP 2212 /* 2213 * We run the long term load balancer infrequently on the first cpu. 2214 */ 2215 if (balance_tdq == tdq) { 2216 if (balance_ticks && --balance_ticks == 0) 2217 sched_balance(); 2218 } 2219 #endif 2220 /* 2221 * Save the old switch count so we have a record of the last ticks 2222 * activity. Initialize the new switch count based on our load. 2223 * If there is some activity seed it to reflect that. 2224 */ 2225 tdq->tdq_oldswitchcnt = tdq->tdq_switchcnt; 2226 tdq->tdq_switchcnt = tdq->tdq_load; 2227 /* 2228 * Advance the insert index once for each tick to ensure that all 2229 * threads get a chance to run. 2230 */ 2231 if (tdq->tdq_idx == tdq->tdq_ridx) { 2232 tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS; 2233 if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx])) 2234 tdq->tdq_ridx = tdq->tdq_idx; 2235 } 2236 ts = td->td_sched; 2237 sched_pctcpu_update(ts, 1); 2238 if (td->td_pri_class & PRI_FIFO_BIT) 2239 return; 2240 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) { 2241 /* 2242 * We used a tick; charge it to the thread so 2243 * that we can compute our interactivity. 2244 */ 2245 td->td_sched->ts_runtime += tickincr; 2246 sched_interact_update(td); 2247 sched_priority(td); 2248 } 2249 2250 /* 2251 * Force a context switch if the current thread has used up a full 2252 * time slice (default is 100ms). 2253 */ 2254 if (!TD_IS_IDLETHREAD(td) && ++ts->ts_slice >= tdq_slice(tdq)) { 2255 ts->ts_slice = 0; 2256 td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND; 2257 } 2258 } 2259 2260 /* 2261 * Called once per hz tick. 2262 */ 2263 void 2264 sched_tick(int cnt) 2265 { 2266 2267 } 2268 2269 /* 2270 * Return whether the current CPU has runnable tasks. Used for in-kernel 2271 * cooperative idle threads. 2272 */ 2273 int 2274 sched_runnable(void) 2275 { 2276 struct tdq *tdq; 2277 int load; 2278 2279 load = 1; 2280 2281 tdq = TDQ_SELF(); 2282 if ((curthread->td_flags & TDF_IDLETD) != 0) { 2283 if (tdq->tdq_load > 0) 2284 goto out; 2285 } else 2286 if (tdq->tdq_load - 1 > 0) 2287 goto out; 2288 load = 0; 2289 out: 2290 return (load); 2291 } 2292 2293 /* 2294 * Choose the highest priority thread to run. The thread is removed from 2295 * the run-queue while running however the load remains. For SMP we set 2296 * the tdq in the global idle bitmask if it idles here. 2297 */ 2298 struct thread * 2299 sched_choose(void) 2300 { 2301 struct thread *td; 2302 struct tdq *tdq; 2303 2304 tdq = TDQ_SELF(); 2305 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2306 td = tdq_choose(tdq); 2307 if (td) { 2308 tdq_runq_rem(tdq, td); 2309 tdq->tdq_lowpri = td->td_priority; 2310 return (td); 2311 } 2312 tdq->tdq_lowpri = PRI_MAX_IDLE; 2313 return (PCPU_GET(idlethread)); 2314 } 2315 2316 /* 2317 * Set owepreempt if necessary. Preemption never happens directly in ULE, 2318 * we always request it once we exit a critical section. 2319 */ 2320 static inline void 2321 sched_setpreempt(struct thread *td) 2322 { 2323 struct thread *ctd; 2324 int cpri; 2325 int pri; 2326 2327 THREAD_LOCK_ASSERT(curthread, MA_OWNED); 2328 2329 ctd = curthread; 2330 pri = td->td_priority; 2331 cpri = ctd->td_priority; 2332 if (pri < cpri) 2333 ctd->td_flags |= TDF_NEEDRESCHED; 2334 if (panicstr != NULL || pri >= cpri || cold || TD_IS_INHIBITED(ctd)) 2335 return; 2336 if (!sched_shouldpreempt(pri, cpri, 0)) 2337 return; 2338 ctd->td_owepreempt = 1; 2339 } 2340 2341 /* 2342 * Add a thread to a thread queue. Select the appropriate runq and add the 2343 * thread to it. This is the internal function called when the tdq is 2344 * predetermined. 2345 */ 2346 void 2347 tdq_add(struct tdq *tdq, struct thread *td, int flags) 2348 { 2349 2350 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2351 KASSERT((td->td_inhibitors == 0), 2352 ("sched_add: trying to run inhibited thread")); 2353 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 2354 ("sched_add: bad thread state")); 2355 KASSERT(td->td_flags & TDF_INMEM, 2356 ("sched_add: thread swapped out")); 2357 2358 if (td->td_priority < tdq->tdq_lowpri) 2359 tdq->tdq_lowpri = td->td_priority; 2360 tdq_runq_add(tdq, td, flags); 2361 tdq_load_add(tdq, td); 2362 } 2363 2364 /* 2365 * Select the target thread queue and add a thread to it. Request 2366 * preemption or IPI a remote processor if required. 2367 */ 2368 void 2369 sched_add(struct thread *td, int flags) 2370 { 2371 struct tdq *tdq; 2372 #ifdef SMP 2373 int cpu; 2374 #endif 2375 2376 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 2377 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 2378 sched_tdname(curthread)); 2379 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 2380 KTR_ATTR_LINKED, sched_tdname(td)); 2381 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 2382 flags & SRQ_PREEMPTED); 2383 THREAD_LOCK_ASSERT(td, MA_OWNED); 2384 /* 2385 * Recalculate the priority before we select the target cpu or 2386 * run-queue. 2387 */ 2388 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 2389 sched_priority(td); 2390 #ifdef SMP 2391 /* 2392 * Pick the destination cpu and if it isn't ours transfer to the 2393 * target cpu. 2394 */ 2395 cpu = sched_pickcpu(td, flags); 2396 tdq = sched_setcpu(td, cpu, flags); 2397 tdq_add(tdq, td, flags); 2398 if (cpu != PCPU_GET(cpuid)) { 2399 tdq_notify(tdq, td); 2400 return; 2401 } 2402 #else 2403 tdq = TDQ_SELF(); 2404 TDQ_LOCK(tdq); 2405 /* 2406 * Now that the thread is moving to the run-queue, set the lock 2407 * to the scheduler's lock. 2408 */ 2409 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 2410 tdq_add(tdq, td, flags); 2411 #endif 2412 if (!(flags & SRQ_YIELDING)) 2413 sched_setpreempt(td); 2414 } 2415 2416 /* 2417 * Remove a thread from a run-queue without running it. This is used 2418 * when we're stealing a thread from a remote queue. Otherwise all threads 2419 * exit by calling sched_exit_thread() and sched_throw() themselves. 2420 */ 2421 void 2422 sched_rem(struct thread *td) 2423 { 2424 struct tdq *tdq; 2425 2426 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "runq rem", 2427 "prio:%d", td->td_priority); 2428 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL); 2429 tdq = TDQ_CPU(td->td_sched->ts_cpu); 2430 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2431 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2432 KASSERT(TD_ON_RUNQ(td), 2433 ("sched_rem: thread not on run queue")); 2434 tdq_runq_rem(tdq, td); 2435 tdq_load_rem(tdq, td); 2436 TD_SET_CAN_RUN(td); 2437 if (td->td_priority == tdq->tdq_lowpri) 2438 tdq_setlowpri(tdq, NULL); 2439 } 2440 2441 /* 2442 * Fetch cpu utilization information. Updates on demand. 2443 */ 2444 fixpt_t 2445 sched_pctcpu(struct thread *td) 2446 { 2447 fixpt_t pctcpu; 2448 struct td_sched *ts; 2449 2450 pctcpu = 0; 2451 ts = td->td_sched; 2452 if (ts == NULL) 2453 return (0); 2454 2455 THREAD_LOCK_ASSERT(td, MA_OWNED); 2456 sched_pctcpu_update(ts, TD_IS_RUNNING(td)); 2457 if (ts->ts_ticks) { 2458 int rtick; 2459 2460 /* How many rtick per second ? */ 2461 rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz); 2462 pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT; 2463 } 2464 2465 return (pctcpu); 2466 } 2467 2468 /* 2469 * Enforce affinity settings for a thread. Called after adjustments to 2470 * cpumask. 2471 */ 2472 void 2473 sched_affinity(struct thread *td) 2474 { 2475 #ifdef SMP 2476 struct td_sched *ts; 2477 2478 THREAD_LOCK_ASSERT(td, MA_OWNED); 2479 ts = td->td_sched; 2480 if (THREAD_CAN_SCHED(td, ts->ts_cpu)) 2481 return; 2482 if (TD_ON_RUNQ(td)) { 2483 sched_rem(td); 2484 sched_add(td, SRQ_BORING); 2485 return; 2486 } 2487 if (!TD_IS_RUNNING(td)) 2488 return; 2489 /* 2490 * Force a switch before returning to userspace. If the 2491 * target thread is not running locally send an ipi to force 2492 * the issue. 2493 */ 2494 td->td_flags |= TDF_NEEDRESCHED; 2495 if (td != curthread) 2496 ipi_cpu(ts->ts_cpu, IPI_PREEMPT); 2497 #endif 2498 } 2499 2500 /* 2501 * Bind a thread to a target cpu. 2502 */ 2503 void 2504 sched_bind(struct thread *td, int cpu) 2505 { 2506 struct td_sched *ts; 2507 2508 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 2509 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 2510 ts = td->td_sched; 2511 if (ts->ts_flags & TSF_BOUND) 2512 sched_unbind(td); 2513 KASSERT(THREAD_CAN_MIGRATE(td), ("%p must be migratable", td)); 2514 ts->ts_flags |= TSF_BOUND; 2515 sched_pin(); 2516 if (PCPU_GET(cpuid) == cpu) 2517 return; 2518 ts->ts_cpu = cpu; 2519 /* When we return from mi_switch we'll be on the correct cpu. */ 2520 mi_switch(SW_VOL, NULL); 2521 } 2522 2523 /* 2524 * Release a bound thread. 2525 */ 2526 void 2527 sched_unbind(struct thread *td) 2528 { 2529 struct td_sched *ts; 2530 2531 THREAD_LOCK_ASSERT(td, MA_OWNED); 2532 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 2533 ts = td->td_sched; 2534 if ((ts->ts_flags & TSF_BOUND) == 0) 2535 return; 2536 ts->ts_flags &= ~TSF_BOUND; 2537 sched_unpin(); 2538 } 2539 2540 int 2541 sched_is_bound(struct thread *td) 2542 { 2543 THREAD_LOCK_ASSERT(td, MA_OWNED); 2544 return (td->td_sched->ts_flags & TSF_BOUND); 2545 } 2546 2547 /* 2548 * Basic yield call. 2549 */ 2550 void 2551 sched_relinquish(struct thread *td) 2552 { 2553 thread_lock(td); 2554 mi_switch(SW_VOL | SWT_RELINQUISH, NULL); 2555 thread_unlock(td); 2556 } 2557 2558 /* 2559 * Return the total system load. 2560 */ 2561 int 2562 sched_load(void) 2563 { 2564 #ifdef SMP 2565 int total; 2566 int i; 2567 2568 total = 0; 2569 CPU_FOREACH(i) 2570 total += TDQ_CPU(i)->tdq_sysload; 2571 return (total); 2572 #else 2573 return (TDQ_SELF()->tdq_sysload); 2574 #endif 2575 } 2576 2577 int 2578 sched_sizeof_proc(void) 2579 { 2580 return (sizeof(struct proc)); 2581 } 2582 2583 int 2584 sched_sizeof_thread(void) 2585 { 2586 return (sizeof(struct thread) + sizeof(struct td_sched)); 2587 } 2588 2589 #ifdef SMP 2590 #define TDQ_IDLESPIN(tdq) \ 2591 ((tdq)->tdq_cg != NULL && ((tdq)->tdq_cg->cg_flags & CG_FLAG_THREAD) == 0) 2592 #else 2593 #define TDQ_IDLESPIN(tdq) 1 2594 #endif 2595 2596 /* 2597 * The actual idle process. 2598 */ 2599 void 2600 sched_idletd(void *dummy) 2601 { 2602 struct thread *td; 2603 struct tdq *tdq; 2604 int oldswitchcnt, switchcnt; 2605 int i; 2606 2607 mtx_assert(&Giant, MA_NOTOWNED); 2608 td = curthread; 2609 tdq = TDQ_SELF(); 2610 THREAD_NO_SLEEPING(); 2611 oldswitchcnt = -1; 2612 for (;;) { 2613 if (tdq->tdq_load) { 2614 thread_lock(td); 2615 mi_switch(SW_VOL | SWT_IDLE, NULL); 2616 thread_unlock(td); 2617 } 2618 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2619 #ifdef SMP 2620 if (switchcnt != oldswitchcnt) { 2621 oldswitchcnt = switchcnt; 2622 if (tdq_idled(tdq) == 0) 2623 continue; 2624 } 2625 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2626 #else 2627 oldswitchcnt = switchcnt; 2628 #endif 2629 /* 2630 * If we're switching very frequently, spin while checking 2631 * for load rather than entering a low power state that 2632 * may require an IPI. However, don't do any busy 2633 * loops while on SMT machines as this simply steals 2634 * cycles from cores doing useful work. 2635 */ 2636 if (TDQ_IDLESPIN(tdq) && switchcnt > sched_idlespinthresh) { 2637 for (i = 0; i < sched_idlespins; i++) { 2638 if (tdq->tdq_load) 2639 break; 2640 cpu_spinwait(); 2641 } 2642 } 2643 2644 /* If there was context switch during spin, restart it. */ 2645 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2646 if (tdq->tdq_load != 0 || switchcnt != oldswitchcnt) 2647 continue; 2648 2649 /* Run main MD idle handler. */ 2650 tdq->tdq_cpu_idle = 1; 2651 /* 2652 * Make sure that tdq_cpu_idle update is globally visible 2653 * before cpu_idle() read tdq_load. The order is important 2654 * to avoid race with tdq_notify. 2655 */ 2656 mb(); 2657 cpu_idle(switchcnt * 4 > sched_idlespinthresh); 2658 tdq->tdq_cpu_idle = 0; 2659 2660 /* 2661 * Account thread-less hardware interrupts and 2662 * other wakeup reasons equal to context switches. 2663 */ 2664 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2665 if (switchcnt != oldswitchcnt) 2666 continue; 2667 tdq->tdq_switchcnt++; 2668 oldswitchcnt++; 2669 } 2670 } 2671 2672 /* 2673 * A CPU is entering for the first time or a thread is exiting. 2674 */ 2675 void 2676 sched_throw(struct thread *td) 2677 { 2678 struct thread *newtd; 2679 struct tdq *tdq; 2680 2681 tdq = TDQ_SELF(); 2682 if (td == NULL) { 2683 /* Correct spinlock nesting and acquire the correct lock. */ 2684 TDQ_LOCK(tdq); 2685 spinlock_exit(); 2686 PCPU_SET(switchtime, cpu_ticks()); 2687 PCPU_SET(switchticks, ticks); 2688 } else { 2689 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2690 tdq_load_rem(tdq, td); 2691 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 2692 } 2693 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 2694 newtd = choosethread(); 2695 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 2696 cpu_throw(td, newtd); /* doesn't return */ 2697 } 2698 2699 /* 2700 * This is called from fork_exit(). Just acquire the correct locks and 2701 * let fork do the rest of the work. 2702 */ 2703 void 2704 sched_fork_exit(struct thread *td) 2705 { 2706 struct tdq *tdq; 2707 int cpuid; 2708 2709 /* 2710 * Finish setting up thread glue so that it begins execution in a 2711 * non-nested critical section with the scheduler lock held. 2712 */ 2713 cpuid = PCPU_GET(cpuid); 2714 tdq = TDQ_CPU(cpuid); 2715 if (TD_IS_IDLETHREAD(td)) 2716 td->td_lock = TDQ_LOCKPTR(tdq); 2717 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2718 td->td_oncpu = cpuid; 2719 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 2720 lock_profile_obtain_lock_success( 2721 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 2722 } 2723 2724 /* 2725 * Create on first use to catch odd startup conditons. 2726 */ 2727 char * 2728 sched_tdname(struct thread *td) 2729 { 2730 #ifdef KTR 2731 struct td_sched *ts; 2732 2733 ts = td->td_sched; 2734 if (ts->ts_name[0] == '\0') 2735 snprintf(ts->ts_name, sizeof(ts->ts_name), 2736 "%s tid %d", td->td_name, td->td_tid); 2737 return (ts->ts_name); 2738 #else 2739 return (td->td_name); 2740 #endif 2741 } 2742 2743 #ifdef KTR 2744 void 2745 sched_clear_tdname(struct thread *td) 2746 { 2747 struct td_sched *ts; 2748 2749 ts = td->td_sched; 2750 ts->ts_name[0] = '\0'; 2751 } 2752 #endif 2753 2754 #ifdef SMP 2755 2756 /* 2757 * Build the CPU topology dump string. Is recursively called to collect 2758 * the topology tree. 2759 */ 2760 static int 2761 sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, struct cpu_group *cg, 2762 int indent) 2763 { 2764 char cpusetbuf[CPUSETBUFSIZ]; 2765 int i, first; 2766 2767 sbuf_printf(sb, "%*s<group level=\"%d\" cache-level=\"%d\">\n", indent, 2768 "", 1 + indent / 2, cg->cg_level); 2769 sbuf_printf(sb, "%*s <cpu count=\"%d\" mask=\"%s\">", indent, "", 2770 cg->cg_count, cpusetobj_strprint(cpusetbuf, &cg->cg_mask)); 2771 first = TRUE; 2772 for (i = 0; i < MAXCPU; i++) { 2773 if (CPU_ISSET(i, &cg->cg_mask)) { 2774 if (!first) 2775 sbuf_printf(sb, ", "); 2776 else 2777 first = FALSE; 2778 sbuf_printf(sb, "%d", i); 2779 } 2780 } 2781 sbuf_printf(sb, "</cpu>\n"); 2782 2783 if (cg->cg_flags != 0) { 2784 sbuf_printf(sb, "%*s <flags>", indent, ""); 2785 if ((cg->cg_flags & CG_FLAG_HTT) != 0) 2786 sbuf_printf(sb, "<flag name=\"HTT\">HTT group</flag>"); 2787 if ((cg->cg_flags & CG_FLAG_THREAD) != 0) 2788 sbuf_printf(sb, "<flag name=\"THREAD\">THREAD group</flag>"); 2789 if ((cg->cg_flags & CG_FLAG_SMT) != 0) 2790 sbuf_printf(sb, "<flag name=\"SMT\">SMT group</flag>"); 2791 sbuf_printf(sb, "</flags>\n"); 2792 } 2793 2794 if (cg->cg_children > 0) { 2795 sbuf_printf(sb, "%*s <children>\n", indent, ""); 2796 for (i = 0; i < cg->cg_children; i++) 2797 sysctl_kern_sched_topology_spec_internal(sb, 2798 &cg->cg_child[i], indent+2); 2799 sbuf_printf(sb, "%*s </children>\n", indent, ""); 2800 } 2801 sbuf_printf(sb, "%*s</group>\n", indent, ""); 2802 return (0); 2803 } 2804 2805 /* 2806 * Sysctl handler for retrieving topology dump. It's a wrapper for 2807 * the recursive sysctl_kern_smp_topology_spec_internal(). 2808 */ 2809 static int 2810 sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS) 2811 { 2812 struct sbuf *topo; 2813 int err; 2814 2815 KASSERT(cpu_top != NULL, ("cpu_top isn't initialized")); 2816 2817 topo = sbuf_new(NULL, NULL, 500, SBUF_AUTOEXTEND); 2818 if (topo == NULL) 2819 return (ENOMEM); 2820 2821 sbuf_printf(topo, "<groups>\n"); 2822 err = sysctl_kern_sched_topology_spec_internal(topo, cpu_top, 1); 2823 sbuf_printf(topo, "</groups>\n"); 2824 2825 if (err == 0) { 2826 sbuf_finish(topo); 2827 err = SYSCTL_OUT(req, sbuf_data(topo), sbuf_len(topo)); 2828 } 2829 sbuf_delete(topo); 2830 return (err); 2831 } 2832 2833 #endif 2834 2835 static int 2836 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 2837 { 2838 int error, new_val, period; 2839 2840 period = 1000000 / realstathz; 2841 new_val = period * sched_slice; 2842 error = sysctl_handle_int(oidp, &new_val, 0, req); 2843 if (error != 0 || req->newptr == NULL) 2844 return (error); 2845 if (new_val <= 0) 2846 return (EINVAL); 2847 sched_slice = imax(1, (new_val + period / 2) / period); 2848 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 2849 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 2850 realstathz); 2851 return (0); 2852 } 2853 2854 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0, "Scheduler"); 2855 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0, 2856 "Scheduler name"); 2857 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW, 2858 NULL, 0, sysctl_kern_quantum, "I", 2859 "Quantum for timeshare threads in microseconds"); 2860 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, 2861 "Quantum for timeshare threads in stathz ticks"); 2862 SYSCTL_INT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0, 2863 "Interactivity score threshold"); 2864 SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW, 2865 &preempt_thresh, 0, 2866 "Maximal (lowest) priority for preemption"); 2867 SYSCTL_INT(_kern_sched, OID_AUTO, static_boost, CTLFLAG_RW, &static_boost, 0, 2868 "Assign static kernel priorities to sleeping threads"); 2869 SYSCTL_INT(_kern_sched, OID_AUTO, idlespins, CTLFLAG_RW, &sched_idlespins, 0, 2870 "Number of times idle thread will spin waiting for new work"); 2871 SYSCTL_INT(_kern_sched, OID_AUTO, idlespinthresh, CTLFLAG_RW, 2872 &sched_idlespinthresh, 0, 2873 "Threshold before we will permit idle thread spinning"); 2874 #ifdef SMP 2875 SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0, 2876 "Number of hz ticks to keep thread affinity for"); 2877 SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0, 2878 "Enables the long-term load balancer"); 2879 SYSCTL_INT(_kern_sched, OID_AUTO, balance_interval, CTLFLAG_RW, 2880 &balance_interval, 0, 2881 "Average period in stathz ticks to run the long-term balancer"); 2882 SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0, 2883 "Attempts to steal work from other cores before idling"); 2884 SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0, 2885 "Minimum load on remote CPU before we'll steal"); 2886 SYSCTL_PROC(_kern_sched, OID_AUTO, topology_spec, CTLTYPE_STRING | 2887 CTLFLAG_RD, NULL, 0, sysctl_kern_sched_topology_spec, "A", 2888 "XML dump of detected CPU topology"); 2889 #endif 2890 2891 /* ps compat. All cpu percentages from ULE are weighted. */ 2892 static int ccpu = 0; 2893 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 2894