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 __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 if (TD_IS_IDLETHREAD(ctd)) { 1041 /* 1042 * If the MD code has an idle wakeup routine try that before 1043 * falling back to IPI. 1044 */ 1045 if (!tdq->tdq_cpu_idle || cpu_idle_wakeup(cpu)) 1046 return; 1047 } 1048 tdq->tdq_ipipending = 1; 1049 ipi_cpu(cpu, IPI_PREEMPT); 1050 } 1051 1052 /* 1053 * Steals load from a timeshare queue. Honors the rotating queue head 1054 * index. 1055 */ 1056 static struct thread * 1057 runq_steal_from(struct runq *rq, int cpu, u_char start) 1058 { 1059 struct rqbits *rqb; 1060 struct rqhead *rqh; 1061 struct thread *td, *first; 1062 int bit; 1063 int i; 1064 1065 rqb = &rq->rq_status; 1066 bit = start & (RQB_BPW -1); 1067 first = NULL; 1068 again: 1069 for (i = RQB_WORD(start); i < RQB_LEN; bit = 0, i++) { 1070 if (rqb->rqb_bits[i] == 0) 1071 continue; 1072 if (bit == 0) 1073 bit = RQB_FFS(rqb->rqb_bits[i]); 1074 for (; bit < RQB_BPW; bit++) { 1075 if ((rqb->rqb_bits[i] & (1ul << bit)) == 0) 1076 continue; 1077 rqh = &rq->rq_queues[bit + (i << RQB_L2BPW)]; 1078 TAILQ_FOREACH(td, rqh, td_runq) { 1079 if (first && THREAD_CAN_MIGRATE(td) && 1080 THREAD_CAN_SCHED(td, cpu)) 1081 return (td); 1082 first = td; 1083 } 1084 } 1085 } 1086 if (start != 0) { 1087 start = 0; 1088 goto again; 1089 } 1090 1091 if (first && THREAD_CAN_MIGRATE(first) && 1092 THREAD_CAN_SCHED(first, cpu)) 1093 return (first); 1094 return (NULL); 1095 } 1096 1097 /* 1098 * Steals load from a standard linear queue. 1099 */ 1100 static struct thread * 1101 runq_steal(struct runq *rq, int cpu) 1102 { 1103 struct rqhead *rqh; 1104 struct rqbits *rqb; 1105 struct thread *td; 1106 int word; 1107 int bit; 1108 1109 rqb = &rq->rq_status; 1110 for (word = 0; word < RQB_LEN; word++) { 1111 if (rqb->rqb_bits[word] == 0) 1112 continue; 1113 for (bit = 0; bit < RQB_BPW; bit++) { 1114 if ((rqb->rqb_bits[word] & (1ul << bit)) == 0) 1115 continue; 1116 rqh = &rq->rq_queues[bit + (word << RQB_L2BPW)]; 1117 TAILQ_FOREACH(td, rqh, td_runq) 1118 if (THREAD_CAN_MIGRATE(td) && 1119 THREAD_CAN_SCHED(td, cpu)) 1120 return (td); 1121 } 1122 } 1123 return (NULL); 1124 } 1125 1126 /* 1127 * Attempt to steal a thread in priority order from a thread queue. 1128 */ 1129 static struct thread * 1130 tdq_steal(struct tdq *tdq, int cpu) 1131 { 1132 struct thread *td; 1133 1134 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1135 if ((td = runq_steal(&tdq->tdq_realtime, cpu)) != NULL) 1136 return (td); 1137 if ((td = runq_steal_from(&tdq->tdq_timeshare, 1138 cpu, tdq->tdq_ridx)) != NULL) 1139 return (td); 1140 return (runq_steal(&tdq->tdq_idle, cpu)); 1141 } 1142 1143 /* 1144 * Sets the thread lock and ts_cpu to match the requested cpu. Unlocks the 1145 * current lock and returns with the assigned queue locked. 1146 */ 1147 static inline struct tdq * 1148 sched_setcpu(struct thread *td, int cpu, int flags) 1149 { 1150 1151 struct tdq *tdq; 1152 1153 THREAD_LOCK_ASSERT(td, MA_OWNED); 1154 tdq = TDQ_CPU(cpu); 1155 td->td_sched->ts_cpu = cpu; 1156 /* 1157 * If the lock matches just return the queue. 1158 */ 1159 if (td->td_lock == TDQ_LOCKPTR(tdq)) 1160 return (tdq); 1161 #ifdef notyet 1162 /* 1163 * If the thread isn't running its lockptr is a 1164 * turnstile or a sleepqueue. We can just lock_set without 1165 * blocking. 1166 */ 1167 if (TD_CAN_RUN(td)) { 1168 TDQ_LOCK(tdq); 1169 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 1170 return (tdq); 1171 } 1172 #endif 1173 /* 1174 * The hard case, migration, we need to block the thread first to 1175 * prevent order reversals with other cpus locks. 1176 */ 1177 spinlock_enter(); 1178 thread_lock_block(td); 1179 TDQ_LOCK(tdq); 1180 thread_lock_unblock(td, TDQ_LOCKPTR(tdq)); 1181 spinlock_exit(); 1182 return (tdq); 1183 } 1184 1185 SCHED_STAT_DEFINE(pickcpu_intrbind, "Soft interrupt binding"); 1186 SCHED_STAT_DEFINE(pickcpu_idle_affinity, "Picked idle cpu based on affinity"); 1187 SCHED_STAT_DEFINE(pickcpu_affinity, "Picked cpu based on affinity"); 1188 SCHED_STAT_DEFINE(pickcpu_lowest, "Selected lowest load"); 1189 SCHED_STAT_DEFINE(pickcpu_local, "Migrated to current cpu"); 1190 SCHED_STAT_DEFINE(pickcpu_migration, "Selection may have caused migration"); 1191 1192 static int 1193 sched_pickcpu(struct thread *td, int flags) 1194 { 1195 struct cpu_group *cg, *ccg; 1196 struct td_sched *ts; 1197 struct tdq *tdq; 1198 cpuset_t mask; 1199 int cpu, pri, self; 1200 1201 self = PCPU_GET(cpuid); 1202 ts = td->td_sched; 1203 if (smp_started == 0) 1204 return (self); 1205 /* 1206 * Don't migrate a running thread from sched_switch(). 1207 */ 1208 if ((flags & SRQ_OURSELF) || !THREAD_CAN_MIGRATE(td)) 1209 return (ts->ts_cpu); 1210 /* 1211 * Prefer to run interrupt threads on the processors that generate 1212 * the interrupt. 1213 */ 1214 pri = td->td_priority; 1215 if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_SCHED(td, self) && 1216 curthread->td_intr_nesting_level && ts->ts_cpu != self) { 1217 SCHED_STAT_INC(pickcpu_intrbind); 1218 ts->ts_cpu = self; 1219 if (TDQ_CPU(self)->tdq_lowpri > pri) { 1220 SCHED_STAT_INC(pickcpu_affinity); 1221 return (ts->ts_cpu); 1222 } 1223 } 1224 /* 1225 * If the thread can run on the last cpu and the affinity has not 1226 * expired or it is idle run it there. 1227 */ 1228 tdq = TDQ_CPU(ts->ts_cpu); 1229 cg = tdq->tdq_cg; 1230 if (THREAD_CAN_SCHED(td, ts->ts_cpu) && 1231 tdq->tdq_lowpri >= PRI_MIN_IDLE && 1232 SCHED_AFFINITY(ts, CG_SHARE_L2)) { 1233 if (cg->cg_flags & CG_FLAG_THREAD) { 1234 CPUSET_FOREACH(cpu, cg->cg_mask) { 1235 if (TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE) 1236 break; 1237 } 1238 } else 1239 cpu = INT_MAX; 1240 if (cpu > mp_maxid) { 1241 SCHED_STAT_INC(pickcpu_idle_affinity); 1242 return (ts->ts_cpu); 1243 } 1244 } 1245 /* 1246 * Search for the last level cache CPU group in the tree. 1247 * Skip caches with expired affinity time and SMT groups. 1248 * Affinity to higher level caches will be handled less aggressively. 1249 */ 1250 for (ccg = NULL; cg != NULL; cg = cg->cg_parent) { 1251 if (cg->cg_flags & CG_FLAG_THREAD) 1252 continue; 1253 if (!SCHED_AFFINITY(ts, cg->cg_level)) 1254 continue; 1255 ccg = cg; 1256 } 1257 if (ccg != NULL) 1258 cg = ccg; 1259 cpu = -1; 1260 /* Search the group for the less loaded idle CPU we can run now. */ 1261 mask = td->td_cpuset->cs_mask; 1262 if (cg != NULL && cg != cpu_top && 1263 CPU_CMP(&cg->cg_mask, &cpu_top->cg_mask) != 0) 1264 cpu = sched_lowest(cg, mask, max(pri, PRI_MAX_TIMESHARE), 1265 INT_MAX, ts->ts_cpu); 1266 /* Search globally for the less loaded CPU we can run now. */ 1267 if (cpu == -1) 1268 cpu = sched_lowest(cpu_top, mask, pri, INT_MAX, ts->ts_cpu); 1269 /* Search globally for the less loaded CPU. */ 1270 if (cpu == -1) 1271 cpu = sched_lowest(cpu_top, mask, -1, INT_MAX, ts->ts_cpu); 1272 KASSERT(cpu != -1, ("sched_pickcpu: Failed to find a cpu.")); 1273 /* 1274 * Compare the lowest loaded cpu to current cpu. 1275 */ 1276 if (THREAD_CAN_SCHED(td, self) && TDQ_CPU(self)->tdq_lowpri > pri && 1277 TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE && 1278 TDQ_CPU(self)->tdq_load <= TDQ_CPU(cpu)->tdq_load + 1) { 1279 SCHED_STAT_INC(pickcpu_local); 1280 cpu = self; 1281 } else 1282 SCHED_STAT_INC(pickcpu_lowest); 1283 if (cpu != ts->ts_cpu) 1284 SCHED_STAT_INC(pickcpu_migration); 1285 return (cpu); 1286 } 1287 #endif 1288 1289 /* 1290 * Pick the highest priority task we have and return it. 1291 */ 1292 static struct thread * 1293 tdq_choose(struct tdq *tdq) 1294 { 1295 struct thread *td; 1296 1297 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1298 td = runq_choose(&tdq->tdq_realtime); 1299 if (td != NULL) 1300 return (td); 1301 td = runq_choose_from(&tdq->tdq_timeshare, tdq->tdq_ridx); 1302 if (td != NULL) { 1303 KASSERT(td->td_priority >= PRI_MIN_BATCH, 1304 ("tdq_choose: Invalid priority on timeshare queue %d", 1305 td->td_priority)); 1306 return (td); 1307 } 1308 td = runq_choose(&tdq->tdq_idle); 1309 if (td != NULL) { 1310 KASSERT(td->td_priority >= PRI_MIN_IDLE, 1311 ("tdq_choose: Invalid priority on idle queue %d", 1312 td->td_priority)); 1313 return (td); 1314 } 1315 1316 return (NULL); 1317 } 1318 1319 /* 1320 * Initialize a thread queue. 1321 */ 1322 static void 1323 tdq_setup(struct tdq *tdq) 1324 { 1325 1326 if (bootverbose) 1327 printf("ULE: setup cpu %d\n", TDQ_ID(tdq)); 1328 runq_init(&tdq->tdq_realtime); 1329 runq_init(&tdq->tdq_timeshare); 1330 runq_init(&tdq->tdq_idle); 1331 snprintf(tdq->tdq_name, sizeof(tdq->tdq_name), 1332 "sched lock %d", (int)TDQ_ID(tdq)); 1333 mtx_init(&tdq->tdq_lock, tdq->tdq_name, "sched lock", 1334 MTX_SPIN | MTX_RECURSE); 1335 #ifdef KTR 1336 snprintf(tdq->tdq_loadname, sizeof(tdq->tdq_loadname), 1337 "CPU %d load", (int)TDQ_ID(tdq)); 1338 #endif 1339 } 1340 1341 #ifdef SMP 1342 static void 1343 sched_setup_smp(void) 1344 { 1345 struct tdq *tdq; 1346 int i; 1347 1348 cpu_top = smp_topo(); 1349 CPU_FOREACH(i) { 1350 tdq = TDQ_CPU(i); 1351 tdq_setup(tdq); 1352 tdq->tdq_cg = smp_topo_find(cpu_top, i); 1353 if (tdq->tdq_cg == NULL) 1354 panic("Can't find cpu group for %d\n", i); 1355 } 1356 balance_tdq = TDQ_SELF(); 1357 sched_balance(); 1358 } 1359 #endif 1360 1361 /* 1362 * Setup the thread queues and initialize the topology based on MD 1363 * information. 1364 */ 1365 static void 1366 sched_setup(void *dummy) 1367 { 1368 struct tdq *tdq; 1369 1370 tdq = TDQ_SELF(); 1371 #ifdef SMP 1372 sched_setup_smp(); 1373 #else 1374 tdq_setup(tdq); 1375 #endif 1376 1377 /* Add thread0's load since it's running. */ 1378 TDQ_LOCK(tdq); 1379 thread0.td_lock = TDQ_LOCKPTR(TDQ_SELF()); 1380 tdq_load_add(tdq, &thread0); 1381 tdq->tdq_lowpri = thread0.td_priority; 1382 TDQ_UNLOCK(tdq); 1383 } 1384 1385 /* 1386 * This routine determines time constants after stathz and hz are setup. 1387 */ 1388 /* ARGSUSED */ 1389 static void 1390 sched_initticks(void *dummy) 1391 { 1392 int incr; 1393 1394 realstathz = stathz ? stathz : hz; 1395 sched_slice = realstathz / SCHED_SLICE_DEFAULT_DIVISOR; 1396 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 1397 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 1398 realstathz); 1399 1400 /* 1401 * tickincr is shifted out by 10 to avoid rounding errors due to 1402 * hz not being evenly divisible by stathz on all platforms. 1403 */ 1404 incr = (hz << SCHED_TICK_SHIFT) / realstathz; 1405 /* 1406 * This does not work for values of stathz that are more than 1407 * 1 << SCHED_TICK_SHIFT * hz. In practice this does not happen. 1408 */ 1409 if (incr == 0) 1410 incr = 1; 1411 tickincr = incr; 1412 #ifdef SMP 1413 /* 1414 * Set the default balance interval now that we know 1415 * what realstathz is. 1416 */ 1417 balance_interval = realstathz; 1418 affinity = SCHED_AFFINITY_DEFAULT; 1419 #endif 1420 if (sched_idlespinthresh < 0) 1421 sched_idlespinthresh = 2 * max(10000, 6 * hz) / realstathz; 1422 } 1423 1424 1425 /* 1426 * This is the core of the interactivity algorithm. Determines a score based 1427 * on past behavior. It is the ratio of sleep time to run time scaled to 1428 * a [0, 100] integer. This is the voluntary sleep time of a process, which 1429 * differs from the cpu usage because it does not account for time spent 1430 * waiting on a run-queue. Would be prettier if we had floating point. 1431 */ 1432 static int 1433 sched_interact_score(struct thread *td) 1434 { 1435 struct td_sched *ts; 1436 int div; 1437 1438 ts = td->td_sched; 1439 /* 1440 * The score is only needed if this is likely to be an interactive 1441 * task. Don't go through the expense of computing it if there's 1442 * no chance. 1443 */ 1444 if (sched_interact <= SCHED_INTERACT_HALF && 1445 ts->ts_runtime >= ts->ts_slptime) 1446 return (SCHED_INTERACT_HALF); 1447 1448 if (ts->ts_runtime > ts->ts_slptime) { 1449 div = max(1, ts->ts_runtime / SCHED_INTERACT_HALF); 1450 return (SCHED_INTERACT_HALF + 1451 (SCHED_INTERACT_HALF - (ts->ts_slptime / div))); 1452 } 1453 if (ts->ts_slptime > ts->ts_runtime) { 1454 div = max(1, ts->ts_slptime / SCHED_INTERACT_HALF); 1455 return (ts->ts_runtime / div); 1456 } 1457 /* runtime == slptime */ 1458 if (ts->ts_runtime) 1459 return (SCHED_INTERACT_HALF); 1460 1461 /* 1462 * This can happen if slptime and runtime are 0. 1463 */ 1464 return (0); 1465 1466 } 1467 1468 /* 1469 * Scale the scheduling priority according to the "interactivity" of this 1470 * process. 1471 */ 1472 static void 1473 sched_priority(struct thread *td) 1474 { 1475 int score; 1476 int pri; 1477 1478 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 1479 return; 1480 /* 1481 * If the score is interactive we place the thread in the realtime 1482 * queue with a priority that is less than kernel and interrupt 1483 * priorities. These threads are not subject to nice restrictions. 1484 * 1485 * Scores greater than this are placed on the normal timeshare queue 1486 * where the priority is partially decided by the most recent cpu 1487 * utilization and the rest is decided by nice value. 1488 * 1489 * The nice value of the process has a linear effect on the calculated 1490 * score. Negative nice values make it easier for a thread to be 1491 * considered interactive. 1492 */ 1493 score = imax(0, sched_interact_score(td) + td->td_proc->p_nice); 1494 if (score < sched_interact) { 1495 pri = PRI_MIN_INTERACT; 1496 pri += ((PRI_MAX_INTERACT - PRI_MIN_INTERACT + 1) / 1497 sched_interact) * score; 1498 KASSERT(pri >= PRI_MIN_INTERACT && pri <= PRI_MAX_INTERACT, 1499 ("sched_priority: invalid interactive priority %d score %d", 1500 pri, score)); 1501 } else { 1502 pri = SCHED_PRI_MIN; 1503 if (td->td_sched->ts_ticks) 1504 pri += min(SCHED_PRI_TICKS(td->td_sched), 1505 SCHED_PRI_RANGE - 1); 1506 pri += SCHED_PRI_NICE(td->td_proc->p_nice); 1507 KASSERT(pri >= PRI_MIN_BATCH && pri <= PRI_MAX_BATCH, 1508 ("sched_priority: invalid priority %d: nice %d, " 1509 "ticks %d ftick %d ltick %d tick pri %d", 1510 pri, td->td_proc->p_nice, td->td_sched->ts_ticks, 1511 td->td_sched->ts_ftick, td->td_sched->ts_ltick, 1512 SCHED_PRI_TICKS(td->td_sched))); 1513 } 1514 sched_user_prio(td, pri); 1515 1516 return; 1517 } 1518 1519 /* 1520 * This routine enforces a maximum limit on the amount of scheduling history 1521 * kept. It is called after either the slptime or runtime is adjusted. This 1522 * function is ugly due to integer math. 1523 */ 1524 static void 1525 sched_interact_update(struct thread *td) 1526 { 1527 struct td_sched *ts; 1528 u_int sum; 1529 1530 ts = td->td_sched; 1531 sum = ts->ts_runtime + ts->ts_slptime; 1532 if (sum < SCHED_SLP_RUN_MAX) 1533 return; 1534 /* 1535 * This only happens from two places: 1536 * 1) We have added an unusual amount of run time from fork_exit. 1537 * 2) We have added an unusual amount of sleep time from sched_sleep(). 1538 */ 1539 if (sum > SCHED_SLP_RUN_MAX * 2) { 1540 if (ts->ts_runtime > ts->ts_slptime) { 1541 ts->ts_runtime = SCHED_SLP_RUN_MAX; 1542 ts->ts_slptime = 1; 1543 } else { 1544 ts->ts_slptime = SCHED_SLP_RUN_MAX; 1545 ts->ts_runtime = 1; 1546 } 1547 return; 1548 } 1549 /* 1550 * If we have exceeded by more than 1/5th then the algorithm below 1551 * will not bring us back into range. Dividing by two here forces 1552 * us into the range of [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX] 1553 */ 1554 if (sum > (SCHED_SLP_RUN_MAX / 5) * 6) { 1555 ts->ts_runtime /= 2; 1556 ts->ts_slptime /= 2; 1557 return; 1558 } 1559 ts->ts_runtime = (ts->ts_runtime / 5) * 4; 1560 ts->ts_slptime = (ts->ts_slptime / 5) * 4; 1561 } 1562 1563 /* 1564 * Scale back the interactivity history when a child thread is created. The 1565 * history is inherited from the parent but the thread may behave totally 1566 * differently. For example, a shell spawning a compiler process. We want 1567 * to learn that the compiler is behaving badly very quickly. 1568 */ 1569 static void 1570 sched_interact_fork(struct thread *td) 1571 { 1572 int ratio; 1573 int sum; 1574 1575 sum = td->td_sched->ts_runtime + td->td_sched->ts_slptime; 1576 if (sum > SCHED_SLP_RUN_FORK) { 1577 ratio = sum / SCHED_SLP_RUN_FORK; 1578 td->td_sched->ts_runtime /= ratio; 1579 td->td_sched->ts_slptime /= ratio; 1580 } 1581 } 1582 1583 /* 1584 * Called from proc0_init() to setup the scheduler fields. 1585 */ 1586 void 1587 schedinit(void) 1588 { 1589 1590 /* 1591 * Set up the scheduler specific parts of proc0. 1592 */ 1593 proc0.p_sched = NULL; /* XXX */ 1594 thread0.td_sched = &td_sched0; 1595 td_sched0.ts_ltick = ticks; 1596 td_sched0.ts_ftick = ticks; 1597 td_sched0.ts_slice = 0; 1598 } 1599 1600 /* 1601 * This is only somewhat accurate since given many processes of the same 1602 * priority they will switch when their slices run out, which will be 1603 * at most sched_slice stathz ticks. 1604 */ 1605 int 1606 sched_rr_interval(void) 1607 { 1608 1609 /* Convert sched_slice from stathz to hz. */ 1610 return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz)); 1611 } 1612 1613 /* 1614 * Update the percent cpu tracking information when it is requested or 1615 * the total history exceeds the maximum. We keep a sliding history of 1616 * tick counts that slowly decays. This is less precise than the 4BSD 1617 * mechanism since it happens with less regular and frequent events. 1618 */ 1619 static void 1620 sched_pctcpu_update(struct td_sched *ts, int run) 1621 { 1622 int t = ticks; 1623 1624 if (t - ts->ts_ltick >= SCHED_TICK_TARG) { 1625 ts->ts_ticks = 0; 1626 ts->ts_ftick = t - SCHED_TICK_TARG; 1627 } else if (t - ts->ts_ftick >= SCHED_TICK_MAX) { 1628 ts->ts_ticks = (ts->ts_ticks / (ts->ts_ltick - ts->ts_ftick)) * 1629 (ts->ts_ltick - (t - SCHED_TICK_TARG)); 1630 ts->ts_ftick = t - SCHED_TICK_TARG; 1631 } 1632 if (run) 1633 ts->ts_ticks += (t - ts->ts_ltick) << SCHED_TICK_SHIFT; 1634 ts->ts_ltick = t; 1635 } 1636 1637 /* 1638 * Adjust the priority of a thread. Move it to the appropriate run-queue 1639 * if necessary. This is the back-end for several priority related 1640 * functions. 1641 */ 1642 static void 1643 sched_thread_priority(struct thread *td, u_char prio) 1644 { 1645 struct td_sched *ts; 1646 struct tdq *tdq; 1647 int oldpri; 1648 1649 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "prio", 1650 "prio:%d", td->td_priority, "new prio:%d", prio, 1651 KTR_ATTR_LINKED, sched_tdname(curthread)); 1652 SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio); 1653 if (td != curthread && prio < td->td_priority) { 1654 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread), 1655 "lend prio", "prio:%d", td->td_priority, "new prio:%d", 1656 prio, KTR_ATTR_LINKED, sched_tdname(td)); 1657 SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio, 1658 curthread); 1659 } 1660 ts = td->td_sched; 1661 THREAD_LOCK_ASSERT(td, MA_OWNED); 1662 if (td->td_priority == prio) 1663 return; 1664 /* 1665 * If the priority has been elevated due to priority 1666 * propagation, we may have to move ourselves to a new 1667 * queue. This could be optimized to not re-add in some 1668 * cases. 1669 */ 1670 if (TD_ON_RUNQ(td) && prio < td->td_priority) { 1671 sched_rem(td); 1672 td->td_priority = prio; 1673 sched_add(td, SRQ_BORROWING); 1674 return; 1675 } 1676 /* 1677 * If the thread is currently running we may have to adjust the lowpri 1678 * information so other cpus are aware of our current priority. 1679 */ 1680 if (TD_IS_RUNNING(td)) { 1681 tdq = TDQ_CPU(ts->ts_cpu); 1682 oldpri = td->td_priority; 1683 td->td_priority = prio; 1684 if (prio < tdq->tdq_lowpri) 1685 tdq->tdq_lowpri = prio; 1686 else if (tdq->tdq_lowpri == oldpri) 1687 tdq_setlowpri(tdq, td); 1688 return; 1689 } 1690 td->td_priority = prio; 1691 } 1692 1693 /* 1694 * Update a thread's priority when it is lent another thread's 1695 * priority. 1696 */ 1697 void 1698 sched_lend_prio(struct thread *td, u_char prio) 1699 { 1700 1701 td->td_flags |= TDF_BORROWING; 1702 sched_thread_priority(td, prio); 1703 } 1704 1705 /* 1706 * Restore a thread's priority when priority propagation is 1707 * over. The prio argument is the minimum priority the thread 1708 * needs to have to satisfy other possible priority lending 1709 * requests. If the thread's regular priority is less 1710 * important than prio, the thread will keep a priority boost 1711 * of prio. 1712 */ 1713 void 1714 sched_unlend_prio(struct thread *td, u_char prio) 1715 { 1716 u_char base_pri; 1717 1718 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 1719 td->td_base_pri <= PRI_MAX_TIMESHARE) 1720 base_pri = td->td_user_pri; 1721 else 1722 base_pri = td->td_base_pri; 1723 if (prio >= base_pri) { 1724 td->td_flags &= ~TDF_BORROWING; 1725 sched_thread_priority(td, base_pri); 1726 } else 1727 sched_lend_prio(td, prio); 1728 } 1729 1730 /* 1731 * Standard entry for setting the priority to an absolute value. 1732 */ 1733 void 1734 sched_prio(struct thread *td, u_char prio) 1735 { 1736 u_char oldprio; 1737 1738 /* First, update the base priority. */ 1739 td->td_base_pri = prio; 1740 1741 /* 1742 * If the thread is borrowing another thread's priority, don't 1743 * ever lower the priority. 1744 */ 1745 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 1746 return; 1747 1748 /* Change the real priority. */ 1749 oldprio = td->td_priority; 1750 sched_thread_priority(td, prio); 1751 1752 /* 1753 * If the thread is on a turnstile, then let the turnstile update 1754 * its state. 1755 */ 1756 if (TD_ON_LOCK(td) && oldprio != prio) 1757 turnstile_adjust(td, oldprio); 1758 } 1759 1760 /* 1761 * Set the base user priority, does not effect current running priority. 1762 */ 1763 void 1764 sched_user_prio(struct thread *td, u_char prio) 1765 { 1766 1767 td->td_base_user_pri = prio; 1768 if (td->td_lend_user_pri <= prio) 1769 return; 1770 td->td_user_pri = prio; 1771 } 1772 1773 void 1774 sched_lend_user_prio(struct thread *td, u_char prio) 1775 { 1776 1777 THREAD_LOCK_ASSERT(td, MA_OWNED); 1778 td->td_lend_user_pri = prio; 1779 td->td_user_pri = min(prio, td->td_base_user_pri); 1780 if (td->td_priority > td->td_user_pri) 1781 sched_prio(td, td->td_user_pri); 1782 else if (td->td_priority != td->td_user_pri) 1783 td->td_flags |= TDF_NEEDRESCHED; 1784 } 1785 1786 /* 1787 * Handle migration from sched_switch(). This happens only for 1788 * cpu binding. 1789 */ 1790 static struct mtx * 1791 sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags) 1792 { 1793 struct tdq *tdn; 1794 1795 tdn = TDQ_CPU(td->td_sched->ts_cpu); 1796 #ifdef SMP 1797 tdq_load_rem(tdq, td); 1798 /* 1799 * Do the lock dance required to avoid LOR. We grab an extra 1800 * spinlock nesting to prevent preemption while we're 1801 * not holding either run-queue lock. 1802 */ 1803 spinlock_enter(); 1804 thread_lock_block(td); /* This releases the lock on tdq. */ 1805 1806 /* 1807 * Acquire both run-queue locks before placing the thread on the new 1808 * run-queue to avoid deadlocks created by placing a thread with a 1809 * blocked lock on the run-queue of a remote processor. The deadlock 1810 * occurs when a third processor attempts to lock the two queues in 1811 * question while the target processor is spinning with its own 1812 * run-queue lock held while waiting for the blocked lock to clear. 1813 */ 1814 tdq_lock_pair(tdn, tdq); 1815 tdq_add(tdn, td, flags); 1816 tdq_notify(tdn, td); 1817 TDQ_UNLOCK(tdn); 1818 spinlock_exit(); 1819 #endif 1820 return (TDQ_LOCKPTR(tdn)); 1821 } 1822 1823 /* 1824 * Variadic version of thread_lock_unblock() that does not assume td_lock 1825 * is blocked. 1826 */ 1827 static inline void 1828 thread_unblock_switch(struct thread *td, struct mtx *mtx) 1829 { 1830 atomic_store_rel_ptr((volatile uintptr_t *)&td->td_lock, 1831 (uintptr_t)mtx); 1832 } 1833 1834 /* 1835 * Switch threads. This function has to handle threads coming in while 1836 * blocked for some reason, running, or idle. It also must deal with 1837 * migrating a thread from one queue to another as running threads may 1838 * be assigned elsewhere via binding. 1839 */ 1840 void 1841 sched_switch(struct thread *td, struct thread *newtd, int flags) 1842 { 1843 struct tdq *tdq; 1844 struct td_sched *ts; 1845 struct mtx *mtx; 1846 int srqflag; 1847 int cpuid, preempted; 1848 1849 THREAD_LOCK_ASSERT(td, MA_OWNED); 1850 KASSERT(newtd == NULL, ("sched_switch: Unsupported newtd argument")); 1851 1852 cpuid = PCPU_GET(cpuid); 1853 tdq = TDQ_CPU(cpuid); 1854 ts = td->td_sched; 1855 mtx = td->td_lock; 1856 sched_pctcpu_update(ts, 1); 1857 ts->ts_rltick = ticks; 1858 td->td_lastcpu = td->td_oncpu; 1859 td->td_oncpu = NOCPU; 1860 preempted = !(td->td_flags & TDF_SLICEEND); 1861 td->td_flags &= ~(TDF_NEEDRESCHED | TDF_SLICEEND); 1862 td->td_owepreempt = 0; 1863 if (!TD_IS_IDLETHREAD(td)) 1864 tdq->tdq_switchcnt++; 1865 /* 1866 * The lock pointer in an idle thread should never change. Reset it 1867 * to CAN_RUN as well. 1868 */ 1869 if (TD_IS_IDLETHREAD(td)) { 1870 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1871 TD_SET_CAN_RUN(td); 1872 } else if (TD_IS_RUNNING(td)) { 1873 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1874 srqflag = preempted ? 1875 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 1876 SRQ_OURSELF|SRQ_YIELDING; 1877 #ifdef SMP 1878 if (THREAD_CAN_MIGRATE(td) && !THREAD_CAN_SCHED(td, ts->ts_cpu)) 1879 ts->ts_cpu = sched_pickcpu(td, 0); 1880 #endif 1881 if (ts->ts_cpu == cpuid) 1882 tdq_runq_add(tdq, td, srqflag); 1883 else { 1884 KASSERT(THREAD_CAN_MIGRATE(td) || 1885 (ts->ts_flags & TSF_BOUND) != 0, 1886 ("Thread %p shouldn't migrate", td)); 1887 mtx = sched_switch_migrate(tdq, td, srqflag); 1888 } 1889 } else { 1890 /* This thread must be going to sleep. */ 1891 TDQ_LOCK(tdq); 1892 mtx = thread_lock_block(td); 1893 tdq_load_rem(tdq, td); 1894 } 1895 /* 1896 * We enter here with the thread blocked and assigned to the 1897 * appropriate cpu run-queue or sleep-queue and with the current 1898 * thread-queue locked. 1899 */ 1900 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 1901 newtd = choosethread(); 1902 /* 1903 * Call the MD code to switch contexts if necessary. 1904 */ 1905 if (td != newtd) { 1906 #ifdef HWPMC_HOOKS 1907 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1908 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 1909 #endif 1910 SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc); 1911 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 1912 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 1913 sched_pctcpu_update(newtd->td_sched, 0); 1914 1915 #ifdef KDTRACE_HOOKS 1916 /* 1917 * If DTrace has set the active vtime enum to anything 1918 * other than INACTIVE (0), then it should have set the 1919 * function to call. 1920 */ 1921 if (dtrace_vtime_active) 1922 (*dtrace_vtime_switch_func)(newtd); 1923 #endif 1924 1925 cpu_switch(td, newtd, mtx); 1926 /* 1927 * We may return from cpu_switch on a different cpu. However, 1928 * we always return with td_lock pointing to the current cpu's 1929 * run queue lock. 1930 */ 1931 cpuid = PCPU_GET(cpuid); 1932 tdq = TDQ_CPU(cpuid); 1933 lock_profile_obtain_lock_success( 1934 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 1935 1936 SDT_PROBE0(sched, , , on__cpu); 1937 #ifdef HWPMC_HOOKS 1938 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1939 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 1940 #endif 1941 } else { 1942 thread_unblock_switch(td, mtx); 1943 SDT_PROBE0(sched, , , remain__cpu); 1944 } 1945 /* 1946 * Assert that all went well and return. 1947 */ 1948 TDQ_LOCK_ASSERT(tdq, MA_OWNED|MA_NOTRECURSED); 1949 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1950 td->td_oncpu = cpuid; 1951 } 1952 1953 /* 1954 * Adjust thread priorities as a result of a nice request. 1955 */ 1956 void 1957 sched_nice(struct proc *p, int nice) 1958 { 1959 struct thread *td; 1960 1961 PROC_LOCK_ASSERT(p, MA_OWNED); 1962 1963 p->p_nice = nice; 1964 FOREACH_THREAD_IN_PROC(p, td) { 1965 thread_lock(td); 1966 sched_priority(td); 1967 sched_prio(td, td->td_base_user_pri); 1968 thread_unlock(td); 1969 } 1970 } 1971 1972 /* 1973 * Record the sleep time for the interactivity scorer. 1974 */ 1975 void 1976 sched_sleep(struct thread *td, int prio) 1977 { 1978 1979 THREAD_LOCK_ASSERT(td, MA_OWNED); 1980 1981 td->td_slptick = ticks; 1982 if (TD_IS_SUSPENDED(td) || prio >= PSOCK) 1983 td->td_flags |= TDF_CANSWAP; 1984 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 1985 return; 1986 if (static_boost == 1 && prio) 1987 sched_prio(td, prio); 1988 else if (static_boost && td->td_priority > static_boost) 1989 sched_prio(td, static_boost); 1990 } 1991 1992 /* 1993 * Schedule a thread to resume execution and record how long it voluntarily 1994 * slept. We also update the pctcpu, interactivity, and priority. 1995 */ 1996 void 1997 sched_wakeup(struct thread *td) 1998 { 1999 struct td_sched *ts; 2000 int slptick; 2001 2002 THREAD_LOCK_ASSERT(td, MA_OWNED); 2003 ts = td->td_sched; 2004 td->td_flags &= ~TDF_CANSWAP; 2005 /* 2006 * If we slept for more than a tick update our interactivity and 2007 * priority. 2008 */ 2009 slptick = td->td_slptick; 2010 td->td_slptick = 0; 2011 if (slptick && slptick != ticks) { 2012 ts->ts_slptime += (ticks - slptick) << SCHED_TICK_SHIFT; 2013 sched_interact_update(td); 2014 sched_pctcpu_update(ts, 0); 2015 } 2016 /* 2017 * Reset the slice value since we slept and advanced the round-robin. 2018 */ 2019 ts->ts_slice = 0; 2020 sched_add(td, SRQ_BORING); 2021 } 2022 2023 /* 2024 * Penalize the parent for creating a new child and initialize the child's 2025 * priority. 2026 */ 2027 void 2028 sched_fork(struct thread *td, struct thread *child) 2029 { 2030 THREAD_LOCK_ASSERT(td, MA_OWNED); 2031 sched_pctcpu_update(td->td_sched, 1); 2032 sched_fork_thread(td, child); 2033 /* 2034 * Penalize the parent and child for forking. 2035 */ 2036 sched_interact_fork(child); 2037 sched_priority(child); 2038 td->td_sched->ts_runtime += tickincr; 2039 sched_interact_update(td); 2040 sched_priority(td); 2041 } 2042 2043 /* 2044 * Fork a new thread, may be within the same process. 2045 */ 2046 void 2047 sched_fork_thread(struct thread *td, struct thread *child) 2048 { 2049 struct td_sched *ts; 2050 struct td_sched *ts2; 2051 struct tdq *tdq; 2052 2053 tdq = TDQ_SELF(); 2054 THREAD_LOCK_ASSERT(td, MA_OWNED); 2055 /* 2056 * Initialize child. 2057 */ 2058 ts = td->td_sched; 2059 ts2 = child->td_sched; 2060 child->td_lock = TDQ_LOCKPTR(tdq); 2061 child->td_cpuset = cpuset_ref(td->td_cpuset); 2062 ts2->ts_cpu = ts->ts_cpu; 2063 ts2->ts_flags = 0; 2064 /* 2065 * Grab our parents cpu estimation information. 2066 */ 2067 ts2->ts_ticks = ts->ts_ticks; 2068 ts2->ts_ltick = ts->ts_ltick; 2069 ts2->ts_ftick = ts->ts_ftick; 2070 /* 2071 * Do not inherit any borrowed priority from the parent. 2072 */ 2073 child->td_priority = child->td_base_pri; 2074 /* 2075 * And update interactivity score. 2076 */ 2077 ts2->ts_slptime = ts->ts_slptime; 2078 ts2->ts_runtime = ts->ts_runtime; 2079 /* Attempt to quickly learn interactivity. */ 2080 ts2->ts_slice = tdq_slice(tdq) - sched_slice_min; 2081 #ifdef KTR 2082 bzero(ts2->ts_name, sizeof(ts2->ts_name)); 2083 #endif 2084 } 2085 2086 /* 2087 * Adjust the priority class of a thread. 2088 */ 2089 void 2090 sched_class(struct thread *td, int class) 2091 { 2092 2093 THREAD_LOCK_ASSERT(td, MA_OWNED); 2094 if (td->td_pri_class == class) 2095 return; 2096 td->td_pri_class = class; 2097 } 2098 2099 /* 2100 * Return some of the child's priority and interactivity to the parent. 2101 */ 2102 void 2103 sched_exit(struct proc *p, struct thread *child) 2104 { 2105 struct thread *td; 2106 2107 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "proc exit", 2108 "prio:%d", child->td_priority); 2109 PROC_LOCK_ASSERT(p, MA_OWNED); 2110 td = FIRST_THREAD_IN_PROC(p); 2111 sched_exit_thread(td, child); 2112 } 2113 2114 /* 2115 * Penalize another thread for the time spent on this one. This helps to 2116 * worsen the priority and interactivity of processes which schedule batch 2117 * jobs such as make. This has little effect on the make process itself but 2118 * causes new processes spawned by it to receive worse scores immediately. 2119 */ 2120 void 2121 sched_exit_thread(struct thread *td, struct thread *child) 2122 { 2123 2124 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "thread exit", 2125 "prio:%d", child->td_priority); 2126 /* 2127 * Give the child's runtime to the parent without returning the 2128 * sleep time as a penalty to the parent. This causes shells that 2129 * launch expensive things to mark their children as expensive. 2130 */ 2131 thread_lock(td); 2132 td->td_sched->ts_runtime += child->td_sched->ts_runtime; 2133 sched_interact_update(td); 2134 sched_priority(td); 2135 thread_unlock(td); 2136 } 2137 2138 void 2139 sched_preempt(struct thread *td) 2140 { 2141 struct tdq *tdq; 2142 2143 SDT_PROBE2(sched, , , surrender, td, td->td_proc); 2144 2145 thread_lock(td); 2146 tdq = TDQ_SELF(); 2147 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2148 tdq->tdq_ipipending = 0; 2149 if (td->td_priority > tdq->tdq_lowpri) { 2150 int flags; 2151 2152 flags = SW_INVOL | SW_PREEMPT; 2153 if (td->td_critnest > 1) 2154 td->td_owepreempt = 1; 2155 else if (TD_IS_IDLETHREAD(td)) 2156 mi_switch(flags | SWT_REMOTEWAKEIDLE, NULL); 2157 else 2158 mi_switch(flags | SWT_REMOTEPREEMPT, NULL); 2159 } 2160 thread_unlock(td); 2161 } 2162 2163 /* 2164 * Fix priorities on return to user-space. Priorities may be elevated due 2165 * to static priorities in msleep() or similar. 2166 */ 2167 void 2168 sched_userret(struct thread *td) 2169 { 2170 /* 2171 * XXX we cheat slightly on the locking here to avoid locking in 2172 * the usual case. Setting td_priority here is essentially an 2173 * incomplete workaround for not setting it properly elsewhere. 2174 * Now that some interrupt handlers are threads, not setting it 2175 * properly elsewhere can clobber it in the window between setting 2176 * it here and returning to user mode, so don't waste time setting 2177 * it perfectly here. 2178 */ 2179 KASSERT((td->td_flags & TDF_BORROWING) == 0, 2180 ("thread with borrowed priority returning to userland")); 2181 if (td->td_priority != td->td_user_pri) { 2182 thread_lock(td); 2183 td->td_priority = td->td_user_pri; 2184 td->td_base_pri = td->td_user_pri; 2185 tdq_setlowpri(TDQ_SELF(), td); 2186 thread_unlock(td); 2187 } 2188 } 2189 2190 /* 2191 * Handle a stathz tick. This is really only relevant for timeshare 2192 * threads. 2193 */ 2194 void 2195 sched_clock(struct thread *td) 2196 { 2197 struct tdq *tdq; 2198 struct td_sched *ts; 2199 2200 THREAD_LOCK_ASSERT(td, MA_OWNED); 2201 tdq = TDQ_SELF(); 2202 #ifdef SMP 2203 /* 2204 * We run the long term load balancer infrequently on the first cpu. 2205 */ 2206 if (balance_tdq == tdq) { 2207 if (balance_ticks && --balance_ticks == 0) 2208 sched_balance(); 2209 } 2210 #endif 2211 /* 2212 * Save the old switch count so we have a record of the last ticks 2213 * activity. Initialize the new switch count based on our load. 2214 * If there is some activity seed it to reflect that. 2215 */ 2216 tdq->tdq_oldswitchcnt = tdq->tdq_switchcnt; 2217 tdq->tdq_switchcnt = tdq->tdq_load; 2218 /* 2219 * Advance the insert index once for each tick to ensure that all 2220 * threads get a chance to run. 2221 */ 2222 if (tdq->tdq_idx == tdq->tdq_ridx) { 2223 tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS; 2224 if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx])) 2225 tdq->tdq_ridx = tdq->tdq_idx; 2226 } 2227 ts = td->td_sched; 2228 sched_pctcpu_update(ts, 1); 2229 if (td->td_pri_class & PRI_FIFO_BIT) 2230 return; 2231 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) { 2232 /* 2233 * We used a tick; charge it to the thread so 2234 * that we can compute our interactivity. 2235 */ 2236 td->td_sched->ts_runtime += tickincr; 2237 sched_interact_update(td); 2238 sched_priority(td); 2239 } 2240 2241 /* 2242 * Force a context switch if the current thread has used up a full 2243 * time slice (default is 100ms). 2244 */ 2245 if (!TD_IS_IDLETHREAD(td) && ++ts->ts_slice >= tdq_slice(tdq)) { 2246 ts->ts_slice = 0; 2247 td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND; 2248 } 2249 } 2250 2251 /* 2252 * Called once per hz tick. 2253 */ 2254 void 2255 sched_tick(int cnt) 2256 { 2257 2258 } 2259 2260 /* 2261 * Return whether the current CPU has runnable tasks. Used for in-kernel 2262 * cooperative idle threads. 2263 */ 2264 int 2265 sched_runnable(void) 2266 { 2267 struct tdq *tdq; 2268 int load; 2269 2270 load = 1; 2271 2272 tdq = TDQ_SELF(); 2273 if ((curthread->td_flags & TDF_IDLETD) != 0) { 2274 if (tdq->tdq_load > 0) 2275 goto out; 2276 } else 2277 if (tdq->tdq_load - 1 > 0) 2278 goto out; 2279 load = 0; 2280 out: 2281 return (load); 2282 } 2283 2284 /* 2285 * Choose the highest priority thread to run. The thread is removed from 2286 * the run-queue while running however the load remains. For SMP we set 2287 * the tdq in the global idle bitmask if it idles here. 2288 */ 2289 struct thread * 2290 sched_choose(void) 2291 { 2292 struct thread *td; 2293 struct tdq *tdq; 2294 2295 tdq = TDQ_SELF(); 2296 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2297 td = tdq_choose(tdq); 2298 if (td) { 2299 tdq_runq_rem(tdq, td); 2300 tdq->tdq_lowpri = td->td_priority; 2301 return (td); 2302 } 2303 tdq->tdq_lowpri = PRI_MAX_IDLE; 2304 return (PCPU_GET(idlethread)); 2305 } 2306 2307 /* 2308 * Set owepreempt if necessary. Preemption never happens directly in ULE, 2309 * we always request it once we exit a critical section. 2310 */ 2311 static inline void 2312 sched_setpreempt(struct thread *td) 2313 { 2314 struct thread *ctd; 2315 int cpri; 2316 int pri; 2317 2318 THREAD_LOCK_ASSERT(curthread, MA_OWNED); 2319 2320 ctd = curthread; 2321 pri = td->td_priority; 2322 cpri = ctd->td_priority; 2323 if (pri < cpri) 2324 ctd->td_flags |= TDF_NEEDRESCHED; 2325 if (panicstr != NULL || pri >= cpri || cold || TD_IS_INHIBITED(ctd)) 2326 return; 2327 if (!sched_shouldpreempt(pri, cpri, 0)) 2328 return; 2329 ctd->td_owepreempt = 1; 2330 } 2331 2332 /* 2333 * Add a thread to a thread queue. Select the appropriate runq and add the 2334 * thread to it. This is the internal function called when the tdq is 2335 * predetermined. 2336 */ 2337 void 2338 tdq_add(struct tdq *tdq, struct thread *td, int flags) 2339 { 2340 2341 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2342 KASSERT((td->td_inhibitors == 0), 2343 ("sched_add: trying to run inhibited thread")); 2344 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 2345 ("sched_add: bad thread state")); 2346 KASSERT(td->td_flags & TDF_INMEM, 2347 ("sched_add: thread swapped out")); 2348 2349 if (td->td_priority < tdq->tdq_lowpri) 2350 tdq->tdq_lowpri = td->td_priority; 2351 tdq_runq_add(tdq, td, flags); 2352 tdq_load_add(tdq, td); 2353 } 2354 2355 /* 2356 * Select the target thread queue and add a thread to it. Request 2357 * preemption or IPI a remote processor if required. 2358 */ 2359 void 2360 sched_add(struct thread *td, int flags) 2361 { 2362 struct tdq *tdq; 2363 #ifdef SMP 2364 int cpu; 2365 #endif 2366 2367 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 2368 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 2369 sched_tdname(curthread)); 2370 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 2371 KTR_ATTR_LINKED, sched_tdname(td)); 2372 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 2373 flags & SRQ_PREEMPTED); 2374 THREAD_LOCK_ASSERT(td, MA_OWNED); 2375 /* 2376 * Recalculate the priority before we select the target cpu or 2377 * run-queue. 2378 */ 2379 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 2380 sched_priority(td); 2381 #ifdef SMP 2382 /* 2383 * Pick the destination cpu and if it isn't ours transfer to the 2384 * target cpu. 2385 */ 2386 cpu = sched_pickcpu(td, flags); 2387 tdq = sched_setcpu(td, cpu, flags); 2388 tdq_add(tdq, td, flags); 2389 if (cpu != PCPU_GET(cpuid)) { 2390 tdq_notify(tdq, td); 2391 return; 2392 } 2393 #else 2394 tdq = TDQ_SELF(); 2395 TDQ_LOCK(tdq); 2396 /* 2397 * Now that the thread is moving to the run-queue, set the lock 2398 * to the scheduler's lock. 2399 */ 2400 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 2401 tdq_add(tdq, td, flags); 2402 #endif 2403 if (!(flags & SRQ_YIELDING)) 2404 sched_setpreempt(td); 2405 } 2406 2407 /* 2408 * Remove a thread from a run-queue without running it. This is used 2409 * when we're stealing a thread from a remote queue. Otherwise all threads 2410 * exit by calling sched_exit_thread() and sched_throw() themselves. 2411 */ 2412 void 2413 sched_rem(struct thread *td) 2414 { 2415 struct tdq *tdq; 2416 2417 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "runq rem", 2418 "prio:%d", td->td_priority); 2419 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL); 2420 tdq = TDQ_CPU(td->td_sched->ts_cpu); 2421 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2422 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2423 KASSERT(TD_ON_RUNQ(td), 2424 ("sched_rem: thread not on run queue")); 2425 tdq_runq_rem(tdq, td); 2426 tdq_load_rem(tdq, td); 2427 TD_SET_CAN_RUN(td); 2428 if (td->td_priority == tdq->tdq_lowpri) 2429 tdq_setlowpri(tdq, NULL); 2430 } 2431 2432 /* 2433 * Fetch cpu utilization information. Updates on demand. 2434 */ 2435 fixpt_t 2436 sched_pctcpu(struct thread *td) 2437 { 2438 fixpt_t pctcpu; 2439 struct td_sched *ts; 2440 2441 pctcpu = 0; 2442 ts = td->td_sched; 2443 if (ts == NULL) 2444 return (0); 2445 2446 THREAD_LOCK_ASSERT(td, MA_OWNED); 2447 sched_pctcpu_update(ts, TD_IS_RUNNING(td)); 2448 if (ts->ts_ticks) { 2449 int rtick; 2450 2451 /* How many rtick per second ? */ 2452 rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz); 2453 pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT; 2454 } 2455 2456 return (pctcpu); 2457 } 2458 2459 /* 2460 * Enforce affinity settings for a thread. Called after adjustments to 2461 * cpumask. 2462 */ 2463 void 2464 sched_affinity(struct thread *td) 2465 { 2466 #ifdef SMP 2467 struct td_sched *ts; 2468 2469 THREAD_LOCK_ASSERT(td, MA_OWNED); 2470 ts = td->td_sched; 2471 if (THREAD_CAN_SCHED(td, ts->ts_cpu)) 2472 return; 2473 if (TD_ON_RUNQ(td)) { 2474 sched_rem(td); 2475 sched_add(td, SRQ_BORING); 2476 return; 2477 } 2478 if (!TD_IS_RUNNING(td)) 2479 return; 2480 /* 2481 * Force a switch before returning to userspace. If the 2482 * target thread is not running locally send an ipi to force 2483 * the issue. 2484 */ 2485 td->td_flags |= TDF_NEEDRESCHED; 2486 if (td != curthread) 2487 ipi_cpu(ts->ts_cpu, IPI_PREEMPT); 2488 #endif 2489 } 2490 2491 /* 2492 * Bind a thread to a target cpu. 2493 */ 2494 void 2495 sched_bind(struct thread *td, int cpu) 2496 { 2497 struct td_sched *ts; 2498 2499 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 2500 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 2501 ts = td->td_sched; 2502 if (ts->ts_flags & TSF_BOUND) 2503 sched_unbind(td); 2504 KASSERT(THREAD_CAN_MIGRATE(td), ("%p must be migratable", td)); 2505 ts->ts_flags |= TSF_BOUND; 2506 sched_pin(); 2507 if (PCPU_GET(cpuid) == cpu) 2508 return; 2509 ts->ts_cpu = cpu; 2510 /* When we return from mi_switch we'll be on the correct cpu. */ 2511 mi_switch(SW_VOL, NULL); 2512 } 2513 2514 /* 2515 * Release a bound thread. 2516 */ 2517 void 2518 sched_unbind(struct thread *td) 2519 { 2520 struct td_sched *ts; 2521 2522 THREAD_LOCK_ASSERT(td, MA_OWNED); 2523 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 2524 ts = td->td_sched; 2525 if ((ts->ts_flags & TSF_BOUND) == 0) 2526 return; 2527 ts->ts_flags &= ~TSF_BOUND; 2528 sched_unpin(); 2529 } 2530 2531 int 2532 sched_is_bound(struct thread *td) 2533 { 2534 THREAD_LOCK_ASSERT(td, MA_OWNED); 2535 return (td->td_sched->ts_flags & TSF_BOUND); 2536 } 2537 2538 /* 2539 * Basic yield call. 2540 */ 2541 void 2542 sched_relinquish(struct thread *td) 2543 { 2544 thread_lock(td); 2545 mi_switch(SW_VOL | SWT_RELINQUISH, NULL); 2546 thread_unlock(td); 2547 } 2548 2549 /* 2550 * Return the total system load. 2551 */ 2552 int 2553 sched_load(void) 2554 { 2555 #ifdef SMP 2556 int total; 2557 int i; 2558 2559 total = 0; 2560 CPU_FOREACH(i) 2561 total += TDQ_CPU(i)->tdq_sysload; 2562 return (total); 2563 #else 2564 return (TDQ_SELF()->tdq_sysload); 2565 #endif 2566 } 2567 2568 int 2569 sched_sizeof_proc(void) 2570 { 2571 return (sizeof(struct proc)); 2572 } 2573 2574 int 2575 sched_sizeof_thread(void) 2576 { 2577 return (sizeof(struct thread) + sizeof(struct td_sched)); 2578 } 2579 2580 #ifdef SMP 2581 #define TDQ_IDLESPIN(tdq) \ 2582 ((tdq)->tdq_cg != NULL && ((tdq)->tdq_cg->cg_flags & CG_FLAG_THREAD) == 0) 2583 #else 2584 #define TDQ_IDLESPIN(tdq) 1 2585 #endif 2586 2587 /* 2588 * The actual idle process. 2589 */ 2590 void 2591 sched_idletd(void *dummy) 2592 { 2593 struct thread *td; 2594 struct tdq *tdq; 2595 int oldswitchcnt, switchcnt; 2596 int i; 2597 2598 mtx_assert(&Giant, MA_NOTOWNED); 2599 td = curthread; 2600 tdq = TDQ_SELF(); 2601 THREAD_NO_SLEEPING(); 2602 oldswitchcnt = -1; 2603 for (;;) { 2604 if (tdq->tdq_load) { 2605 thread_lock(td); 2606 mi_switch(SW_VOL | SWT_IDLE, NULL); 2607 thread_unlock(td); 2608 } 2609 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2610 #ifdef SMP 2611 if (switchcnt != oldswitchcnt) { 2612 oldswitchcnt = switchcnt; 2613 if (tdq_idled(tdq) == 0) 2614 continue; 2615 } 2616 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2617 #else 2618 oldswitchcnt = switchcnt; 2619 #endif 2620 /* 2621 * If we're switching very frequently, spin while checking 2622 * for load rather than entering a low power state that 2623 * may require an IPI. However, don't do any busy 2624 * loops while on SMT machines as this simply steals 2625 * cycles from cores doing useful work. 2626 */ 2627 if (TDQ_IDLESPIN(tdq) && switchcnt > sched_idlespinthresh) { 2628 for (i = 0; i < sched_idlespins; i++) { 2629 if (tdq->tdq_load) 2630 break; 2631 cpu_spinwait(); 2632 } 2633 } 2634 2635 /* If there was context switch during spin, restart it. */ 2636 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2637 if (tdq->tdq_load != 0 || switchcnt != oldswitchcnt) 2638 continue; 2639 2640 /* Run main MD idle handler. */ 2641 tdq->tdq_cpu_idle = 1; 2642 cpu_idle(switchcnt * 4 > sched_idlespinthresh); 2643 tdq->tdq_cpu_idle = 0; 2644 2645 /* 2646 * Account thread-less hardware interrupts and 2647 * other wakeup reasons equal to context switches. 2648 */ 2649 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2650 if (switchcnt != oldswitchcnt) 2651 continue; 2652 tdq->tdq_switchcnt++; 2653 oldswitchcnt++; 2654 } 2655 } 2656 2657 /* 2658 * A CPU is entering for the first time or a thread is exiting. 2659 */ 2660 void 2661 sched_throw(struct thread *td) 2662 { 2663 struct thread *newtd; 2664 struct tdq *tdq; 2665 2666 tdq = TDQ_SELF(); 2667 if (td == NULL) { 2668 /* Correct spinlock nesting and acquire the correct lock. */ 2669 TDQ_LOCK(tdq); 2670 spinlock_exit(); 2671 PCPU_SET(switchtime, cpu_ticks()); 2672 PCPU_SET(switchticks, ticks); 2673 } else { 2674 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2675 tdq_load_rem(tdq, td); 2676 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 2677 } 2678 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 2679 newtd = choosethread(); 2680 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 2681 cpu_throw(td, newtd); /* doesn't return */ 2682 } 2683 2684 /* 2685 * This is called from fork_exit(). Just acquire the correct locks and 2686 * let fork do the rest of the work. 2687 */ 2688 void 2689 sched_fork_exit(struct thread *td) 2690 { 2691 struct tdq *tdq; 2692 int cpuid; 2693 2694 /* 2695 * Finish setting up thread glue so that it begins execution in a 2696 * non-nested critical section with the scheduler lock held. 2697 */ 2698 cpuid = PCPU_GET(cpuid); 2699 tdq = TDQ_CPU(cpuid); 2700 if (TD_IS_IDLETHREAD(td)) 2701 td->td_lock = TDQ_LOCKPTR(tdq); 2702 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2703 td->td_oncpu = cpuid; 2704 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 2705 lock_profile_obtain_lock_success( 2706 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 2707 } 2708 2709 /* 2710 * Create on first use to catch odd startup conditons. 2711 */ 2712 char * 2713 sched_tdname(struct thread *td) 2714 { 2715 #ifdef KTR 2716 struct td_sched *ts; 2717 2718 ts = td->td_sched; 2719 if (ts->ts_name[0] == '\0') 2720 snprintf(ts->ts_name, sizeof(ts->ts_name), 2721 "%s tid %d", td->td_name, td->td_tid); 2722 return (ts->ts_name); 2723 #else 2724 return (td->td_name); 2725 #endif 2726 } 2727 2728 #ifdef KTR 2729 void 2730 sched_clear_tdname(struct thread *td) 2731 { 2732 struct td_sched *ts; 2733 2734 ts = td->td_sched; 2735 ts->ts_name[0] = '\0'; 2736 } 2737 #endif 2738 2739 #ifdef SMP 2740 2741 /* 2742 * Build the CPU topology dump string. Is recursively called to collect 2743 * the topology tree. 2744 */ 2745 static int 2746 sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, struct cpu_group *cg, 2747 int indent) 2748 { 2749 char cpusetbuf[CPUSETBUFSIZ]; 2750 int i, first; 2751 2752 sbuf_printf(sb, "%*s<group level=\"%d\" cache-level=\"%d\">\n", indent, 2753 "", 1 + indent / 2, cg->cg_level); 2754 sbuf_printf(sb, "%*s <cpu count=\"%d\" mask=\"%s\">", indent, "", 2755 cg->cg_count, cpusetobj_strprint(cpusetbuf, &cg->cg_mask)); 2756 first = TRUE; 2757 for (i = 0; i < MAXCPU; i++) { 2758 if (CPU_ISSET(i, &cg->cg_mask)) { 2759 if (!first) 2760 sbuf_printf(sb, ", "); 2761 else 2762 first = FALSE; 2763 sbuf_printf(sb, "%d", i); 2764 } 2765 } 2766 sbuf_printf(sb, "</cpu>\n"); 2767 2768 if (cg->cg_flags != 0) { 2769 sbuf_printf(sb, "%*s <flags>", indent, ""); 2770 if ((cg->cg_flags & CG_FLAG_HTT) != 0) 2771 sbuf_printf(sb, "<flag name=\"HTT\">HTT group</flag>"); 2772 if ((cg->cg_flags & CG_FLAG_THREAD) != 0) 2773 sbuf_printf(sb, "<flag name=\"THREAD\">THREAD group</flag>"); 2774 if ((cg->cg_flags & CG_FLAG_SMT) != 0) 2775 sbuf_printf(sb, "<flag name=\"SMT\">SMT group</flag>"); 2776 sbuf_printf(sb, "</flags>\n"); 2777 } 2778 2779 if (cg->cg_children > 0) { 2780 sbuf_printf(sb, "%*s <children>\n", indent, ""); 2781 for (i = 0; i < cg->cg_children; i++) 2782 sysctl_kern_sched_topology_spec_internal(sb, 2783 &cg->cg_child[i], indent+2); 2784 sbuf_printf(sb, "%*s </children>\n", indent, ""); 2785 } 2786 sbuf_printf(sb, "%*s</group>\n", indent, ""); 2787 return (0); 2788 } 2789 2790 /* 2791 * Sysctl handler for retrieving topology dump. It's a wrapper for 2792 * the recursive sysctl_kern_smp_topology_spec_internal(). 2793 */ 2794 static int 2795 sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS) 2796 { 2797 struct sbuf *topo; 2798 int err; 2799 2800 KASSERT(cpu_top != NULL, ("cpu_top isn't initialized")); 2801 2802 topo = sbuf_new(NULL, NULL, 500, SBUF_AUTOEXTEND); 2803 if (topo == NULL) 2804 return (ENOMEM); 2805 2806 sbuf_printf(topo, "<groups>\n"); 2807 err = sysctl_kern_sched_topology_spec_internal(topo, cpu_top, 1); 2808 sbuf_printf(topo, "</groups>\n"); 2809 2810 if (err == 0) { 2811 sbuf_finish(topo); 2812 err = SYSCTL_OUT(req, sbuf_data(topo), sbuf_len(topo)); 2813 } 2814 sbuf_delete(topo); 2815 return (err); 2816 } 2817 2818 #endif 2819 2820 static int 2821 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 2822 { 2823 int error, new_val, period; 2824 2825 period = 1000000 / realstathz; 2826 new_val = period * sched_slice; 2827 error = sysctl_handle_int(oidp, &new_val, 0, req); 2828 if (error != 0 || req->newptr == NULL) 2829 return (error); 2830 if (new_val <= 0) 2831 return (EINVAL); 2832 sched_slice = imax(1, (new_val + period / 2) / period); 2833 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 2834 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 2835 realstathz); 2836 return (0); 2837 } 2838 2839 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0, "Scheduler"); 2840 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0, 2841 "Scheduler name"); 2842 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW, 2843 NULL, 0, sysctl_kern_quantum, "I", 2844 "Quantum for timeshare threads in microseconds"); 2845 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, 2846 "Quantum for timeshare threads in stathz ticks"); 2847 SYSCTL_INT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0, 2848 "Interactivity score threshold"); 2849 SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW, 2850 &preempt_thresh, 0, 2851 "Maximal (lowest) priority for preemption"); 2852 SYSCTL_INT(_kern_sched, OID_AUTO, static_boost, CTLFLAG_RW, &static_boost, 0, 2853 "Assign static kernel priorities to sleeping threads"); 2854 SYSCTL_INT(_kern_sched, OID_AUTO, idlespins, CTLFLAG_RW, &sched_idlespins, 0, 2855 "Number of times idle thread will spin waiting for new work"); 2856 SYSCTL_INT(_kern_sched, OID_AUTO, idlespinthresh, CTLFLAG_RW, 2857 &sched_idlespinthresh, 0, 2858 "Threshold before we will permit idle thread spinning"); 2859 #ifdef SMP 2860 SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0, 2861 "Number of hz ticks to keep thread affinity for"); 2862 SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0, 2863 "Enables the long-term load balancer"); 2864 SYSCTL_INT(_kern_sched, OID_AUTO, balance_interval, CTLFLAG_RW, 2865 &balance_interval, 0, 2866 "Average period in stathz ticks to run the long-term balancer"); 2867 SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0, 2868 "Attempts to steal work from other cores before idling"); 2869 SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0, 2870 "Minimum load on remote CPU before we'll steal"); 2871 SYSCTL_PROC(_kern_sched, OID_AUTO, topology_spec, CTLTYPE_STRING | 2872 CTLFLAG_RD, NULL, 0, sysctl_kern_sched_topology_spec, "A", 2873 "XML dump of detected CPU topology"); 2874 #endif 2875 2876 /* ps compat. All cpu percentages from ULE are weighted. */ 2877 static int ccpu = 0; 2878 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 2879