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