1 /*- 2 * Copyright (c) 2002-2007, Jeffrey Roberson <jeff@freebsd.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice unmodified, this list of conditions, and the following 10 * disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 /* 28 * This file implements the ULE scheduler. ULE supports independent CPU 29 * run queues and fine grain locking. It has superior interactive 30 * performance under load even on uni-processor systems. 31 * 32 * etymology: 33 * ULE is the last three letters in schedule. It owes its name to a 34 * generic user created for a scheduling system by Paul Mikesell at 35 * Isilon Systems and a general lack of creativity on the part of the author. 36 */ 37 38 #include <sys/cdefs.h> 39 __FBSDID("$FreeBSD$"); 40 41 #include "opt_hwpmc_hooks.h" 42 #include "opt_sched.h" 43 44 #include <sys/param.h> 45 #include <sys/systm.h> 46 #include <sys/kdb.h> 47 #include <sys/kernel.h> 48 #include <sys/ktr.h> 49 #include <sys/lock.h> 50 #include <sys/mutex.h> 51 #include <sys/proc.h> 52 #include <sys/resource.h> 53 #include <sys/resourcevar.h> 54 #include <sys/sched.h> 55 #include <sys/sdt.h> 56 #include <sys/smp.h> 57 #include <sys/sx.h> 58 #include <sys/sysctl.h> 59 #include <sys/sysproto.h> 60 #include <sys/turnstile.h> 61 #include <sys/umtx.h> 62 #include <sys/vmmeter.h> 63 #include <sys/cpuset.h> 64 #include <sys/sbuf.h> 65 66 #ifdef HWPMC_HOOKS 67 #include <sys/pmckern.h> 68 #endif 69 70 #ifdef KDTRACE_HOOKS 71 #include <sys/dtrace_bsd.h> 72 int dtrace_vtime_active; 73 dtrace_vtime_switch_func_t dtrace_vtime_switch_func; 74 #endif 75 76 #include <machine/cpu.h> 77 #include <machine/smp.h> 78 79 #if defined(__powerpc__) && defined(BOOKE_E500) 80 #error "This architecture is not currently compatible with ULE" 81 #endif 82 83 #define KTR_ULE 0 84 85 #define TS_NAME_LEN (MAXCOMLEN + sizeof(" td ") + sizeof(__XSTRING(UINT_MAX))) 86 #define TDQ_NAME_LEN (sizeof("sched lock ") + sizeof(__XSTRING(MAXCPU))) 87 #define TDQ_LOADNAME_LEN (sizeof("CPU ") + sizeof(__XSTRING(MAXCPU)) - 1 + sizeof(" load")) 88 89 /* 90 * Thread scheduler specific section. All fields are protected 91 * by the thread lock. 92 */ 93 struct td_sched { 94 struct runq *ts_runq; /* Run-queue we're queued on. */ 95 short ts_flags; /* TSF_* flags. */ 96 u_char ts_cpu; /* CPU that we have affinity for. */ 97 int ts_rltick; /* Real last tick, for affinity. */ 98 int ts_slice; /* Ticks of slice remaining. */ 99 u_int ts_slptime; /* Number of ticks we vol. slept */ 100 u_int ts_runtime; /* Number of ticks we were running */ 101 int ts_ltick; /* Last tick that we were running on */ 102 int ts_ftick; /* First tick that we were running on */ 103 int ts_ticks; /* Tick count */ 104 #ifdef KTR 105 char ts_name[TS_NAME_LEN]; 106 #endif 107 }; 108 /* flags kept in ts_flags */ 109 #define TSF_BOUND 0x0001 /* Thread can not migrate. */ 110 #define TSF_XFERABLE 0x0002 /* Thread was added as transferable. */ 111 112 static struct td_sched td_sched0; 113 114 #define THREAD_CAN_MIGRATE(td) ((td)->td_pinned == 0) 115 #define THREAD_CAN_SCHED(td, cpu) \ 116 CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask) 117 118 /* 119 * Priority ranges used for interactive and non-interactive timeshare 120 * threads. The timeshare priorities are split up into four ranges. 121 * The first range handles interactive threads. The last three ranges 122 * (NHALF, x, and NHALF) handle non-interactive threads with the outer 123 * ranges supporting nice values. 124 */ 125 #define PRI_TIMESHARE_RANGE (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE + 1) 126 #define PRI_INTERACT_RANGE ((PRI_TIMESHARE_RANGE - SCHED_PRI_NRESV) / 2) 127 #define PRI_BATCH_RANGE (PRI_TIMESHARE_RANGE - PRI_INTERACT_RANGE) 128 129 #define PRI_MIN_INTERACT PRI_MIN_TIMESHARE 130 #define PRI_MAX_INTERACT (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE - 1) 131 #define PRI_MIN_BATCH (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE) 132 #define PRI_MAX_BATCH PRI_MAX_TIMESHARE 133 134 /* 135 * Cpu percentage computation macros and defines. 136 * 137 * SCHED_TICK_SECS: Number of seconds to average the cpu usage across. 138 * SCHED_TICK_TARG: Number of hz ticks to average the cpu usage across. 139 * SCHED_TICK_MAX: Maximum number of ticks before scaling back. 140 * SCHED_TICK_SHIFT: Shift factor to avoid rounding away results. 141 * SCHED_TICK_HZ: Compute the number of hz ticks for a given ticks count. 142 * SCHED_TICK_TOTAL: Gives the amount of time we've been recording ticks. 143 */ 144 #define SCHED_TICK_SECS 10 145 #define SCHED_TICK_TARG (hz * SCHED_TICK_SECS) 146 #define SCHED_TICK_MAX (SCHED_TICK_TARG + hz) 147 #define SCHED_TICK_SHIFT 10 148 #define SCHED_TICK_HZ(ts) ((ts)->ts_ticks >> SCHED_TICK_SHIFT) 149 #define SCHED_TICK_TOTAL(ts) (max((ts)->ts_ltick - (ts)->ts_ftick, hz)) 150 151 /* 152 * These macros determine priorities for non-interactive threads. They are 153 * assigned a priority based on their recent cpu utilization as expressed 154 * by the ratio of ticks to the tick total. NHALF priorities at the start 155 * and end of the MIN to MAX timeshare range are only reachable with negative 156 * or positive nice respectively. 157 * 158 * PRI_RANGE: Priority range for utilization dependent priorities. 159 * PRI_NRESV: Number of nice values. 160 * PRI_TICKS: Compute a priority in PRI_RANGE from the ticks count and total. 161 * PRI_NICE: Determines the part of the priority inherited from nice. 162 */ 163 #define SCHED_PRI_NRESV (PRIO_MAX - PRIO_MIN) 164 #define SCHED_PRI_NHALF (SCHED_PRI_NRESV / 2) 165 #define SCHED_PRI_MIN (PRI_MIN_BATCH + SCHED_PRI_NHALF) 166 #define SCHED_PRI_MAX (PRI_MAX_BATCH - SCHED_PRI_NHALF) 167 #define SCHED_PRI_RANGE (SCHED_PRI_MAX - SCHED_PRI_MIN + 1) 168 #define SCHED_PRI_TICKS(ts) \ 169 (SCHED_TICK_HZ((ts)) / \ 170 (roundup(SCHED_TICK_TOTAL((ts)), SCHED_PRI_RANGE) / SCHED_PRI_RANGE)) 171 #define SCHED_PRI_NICE(nice) (nice) 172 173 /* 174 * These determine the interactivity of a process. Interactivity differs from 175 * cpu utilization in that it expresses the voluntary time slept vs time ran 176 * while cpu utilization includes all time not running. This more accurately 177 * models the intent of the thread. 178 * 179 * SLP_RUN_MAX: Maximum amount of sleep time + run time we'll accumulate 180 * before throttling back. 181 * SLP_RUN_FORK: Maximum slp+run time to inherit at fork time. 182 * INTERACT_MAX: Maximum interactivity value. Smaller is better. 183 * INTERACT_THRESH: Threshold for placement on the current runq. 184 */ 185 #define SCHED_SLP_RUN_MAX ((hz * 5) << SCHED_TICK_SHIFT) 186 #define SCHED_SLP_RUN_FORK ((hz / 2) << SCHED_TICK_SHIFT) 187 #define SCHED_INTERACT_MAX (100) 188 #define SCHED_INTERACT_HALF (SCHED_INTERACT_MAX / 2) 189 #define SCHED_INTERACT_THRESH (30) 190 191 /* 192 * These parameters determine the slice behavior for batch work. 193 */ 194 #define SCHED_SLICE_DEFAULT_DIVISOR 10 /* ~94 ms, 12 stathz ticks. */ 195 #define SCHED_SLICE_MIN_DIVISOR 6 /* DEFAULT/MIN = ~16 ms. */ 196 197 /* Flags kept in td_flags. */ 198 #define TDF_SLICEEND TDF_SCHED2 /* Thread time slice is over. */ 199 200 /* 201 * tickincr: Converts a stathz tick into a hz domain scaled by 202 * the shift factor. Without the shift the error rate 203 * due to rounding would be unacceptably high. 204 * realstathz: stathz is sometimes 0 and run off of hz. 205 * sched_slice: Runtime of each thread before rescheduling. 206 * preempt_thresh: Priority threshold for preemption and remote IPIs. 207 */ 208 static int sched_interact = SCHED_INTERACT_THRESH; 209 static int tickincr = 8 << SCHED_TICK_SHIFT; 210 static int realstathz = 127; /* reset during boot. */ 211 static int sched_slice = 10; /* reset during boot. */ 212 static int sched_slice_min = 1; /* reset during boot. */ 213 #ifdef PREEMPTION 214 #ifdef FULL_PREEMPTION 215 static int preempt_thresh = PRI_MAX_IDLE; 216 #else 217 static int preempt_thresh = PRI_MIN_KERN; 218 #endif 219 #else 220 static int preempt_thresh = 0; 221 #endif 222 static int static_boost = PRI_MIN_BATCH; 223 static int sched_idlespins = 10000; 224 static int sched_idlespinthresh = -1; 225 226 /* 227 * tdq - per processor runqs and statistics. All fields are protected by the 228 * tdq_lock. The load and lowpri may be accessed without to avoid excess 229 * locking in sched_pickcpu(); 230 */ 231 struct tdq { 232 /* 233 * Ordered to improve efficiency of cpu_search() and switch(). 234 * tdq_lock is padded to avoid false sharing with tdq_load and 235 * tdq_cpu_idle. 236 */ 237 struct mtx_padalign tdq_lock; /* run queue lock. */ 238 struct cpu_group *tdq_cg; /* Pointer to cpu topology. */ 239 volatile int tdq_load; /* Aggregate load. */ 240 volatile int tdq_cpu_idle; /* cpu_idle() is active. */ 241 int tdq_sysload; /* For loadavg, !ITHD load. */ 242 int tdq_transferable; /* Transferable thread count. */ 243 short tdq_switchcnt; /* Switches this tick. */ 244 short tdq_oldswitchcnt; /* Switches last tick. */ 245 u_char tdq_lowpri; /* Lowest priority thread. */ 246 u_char tdq_ipipending; /* IPI pending. */ 247 u_char tdq_idx; /* Current insert index. */ 248 u_char tdq_ridx; /* Current removal index. */ 249 struct runq tdq_realtime; /* real-time run queue. */ 250 struct runq tdq_timeshare; /* timeshare run queue. */ 251 struct runq tdq_idle; /* Queue of IDLE threads. */ 252 char tdq_name[TDQ_NAME_LEN]; 253 #ifdef KTR 254 char tdq_loadname[TDQ_LOADNAME_LEN]; 255 #endif 256 } __aligned(64); 257 258 /* Idle thread states and config. */ 259 #define TDQ_RUNNING 1 260 #define TDQ_IDLE 2 261 262 #ifdef SMP 263 struct cpu_group *cpu_top; /* CPU topology */ 264 265 #define SCHED_AFFINITY_DEFAULT (max(1, hz / 1000)) 266 #define SCHED_AFFINITY(ts, t) ((ts)->ts_rltick > ticks - ((t) * affinity)) 267 268 /* 269 * Run-time tunables. 270 */ 271 static int rebalance = 1; 272 static int balance_interval = 128; /* Default set in sched_initticks(). */ 273 static int affinity; 274 static int steal_idle = 1; 275 static int steal_thresh = 2; 276 277 /* 278 * One thread queue per processor. 279 */ 280 static struct tdq tdq_cpu[MAXCPU]; 281 static struct tdq *balance_tdq; 282 static int balance_ticks; 283 static DPCPU_DEFINE(uint32_t, randomval); 284 285 #define TDQ_SELF() (&tdq_cpu[PCPU_GET(cpuid)]) 286 #define TDQ_CPU(x) (&tdq_cpu[(x)]) 287 #define TDQ_ID(x) ((int)((x) - tdq_cpu)) 288 #else /* !SMP */ 289 static struct tdq tdq_cpu; 290 291 #define TDQ_ID(x) (0) 292 #define TDQ_SELF() (&tdq_cpu) 293 #define TDQ_CPU(x) (&tdq_cpu) 294 #endif 295 296 #define TDQ_LOCK_ASSERT(t, type) mtx_assert(TDQ_LOCKPTR((t)), (type)) 297 #define TDQ_LOCK(t) mtx_lock_spin(TDQ_LOCKPTR((t))) 298 #define TDQ_LOCK_FLAGS(t, f) mtx_lock_spin_flags(TDQ_LOCKPTR((t)), (f)) 299 #define TDQ_UNLOCK(t) mtx_unlock_spin(TDQ_LOCKPTR((t))) 300 #define TDQ_LOCKPTR(t) ((struct mtx *)(&(t)->tdq_lock)) 301 302 static void sched_priority(struct thread *); 303 static void sched_thread_priority(struct thread *, u_char); 304 static int sched_interact_score(struct thread *); 305 static void sched_interact_update(struct thread *); 306 static void sched_interact_fork(struct thread *); 307 static void sched_pctcpu_update(struct td_sched *, int); 308 309 /* Operations on per processor queues */ 310 static struct thread *tdq_choose(struct tdq *); 311 static void tdq_setup(struct tdq *); 312 static void tdq_load_add(struct tdq *, struct thread *); 313 static void tdq_load_rem(struct tdq *, struct thread *); 314 static __inline void tdq_runq_add(struct tdq *, struct thread *, int); 315 static __inline void tdq_runq_rem(struct tdq *, struct thread *); 316 static inline int sched_shouldpreempt(int, int, int); 317 void tdq_print(int cpu); 318 static void runq_print(struct runq *rq); 319 static void tdq_add(struct tdq *, struct thread *, int); 320 #ifdef SMP 321 static int tdq_move(struct tdq *, struct tdq *); 322 static int tdq_idled(struct tdq *); 323 static void tdq_notify(struct tdq *, struct thread *); 324 static struct thread *tdq_steal(struct tdq *, int); 325 static struct thread *runq_steal(struct runq *, int); 326 static int sched_pickcpu(struct thread *, int); 327 static void sched_balance(void); 328 static int sched_balance_pair(struct tdq *, struct tdq *); 329 static inline struct tdq *sched_setcpu(struct thread *, int, int); 330 static inline void thread_unblock_switch(struct thread *, struct mtx *); 331 static struct mtx *sched_switch_migrate(struct tdq *, struct thread *, int); 332 static int sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS); 333 static int sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, 334 struct cpu_group *cg, int indent); 335 #endif 336 337 static void sched_setup(void *dummy); 338 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL); 339 340 static void sched_initticks(void *dummy); 341 SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks, 342 NULL); 343 344 SDT_PROVIDER_DEFINE(sched); 345 346 SDT_PROBE_DEFINE3(sched, , , change__pri, "struct thread *", 347 "struct proc *", "uint8_t"); 348 SDT_PROBE_DEFINE3(sched, , , dequeue, "struct thread *", 349 "struct proc *", "void *"); 350 SDT_PROBE_DEFINE4(sched, , , enqueue, "struct thread *", 351 "struct proc *", "void *", "int"); 352 SDT_PROBE_DEFINE4(sched, , , lend__pri, "struct thread *", 353 "struct proc *", "uint8_t", "struct thread *"); 354 SDT_PROBE_DEFINE2(sched, , , load__change, "int", "int"); 355 SDT_PROBE_DEFINE2(sched, , , off__cpu, "struct thread *", 356 "struct proc *"); 357 SDT_PROBE_DEFINE(sched, , , on__cpu); 358 SDT_PROBE_DEFINE(sched, , , remain__cpu); 359 SDT_PROBE_DEFINE2(sched, , , surrender, "struct thread *", 360 "struct proc *"); 361 362 /* 363 * Print the threads waiting on a run-queue. 364 */ 365 static void 366 runq_print(struct runq *rq) 367 { 368 struct rqhead *rqh; 369 struct thread *td; 370 int pri; 371 int j; 372 int i; 373 374 for (i = 0; i < RQB_LEN; i++) { 375 printf("\t\trunq bits %d 0x%zx\n", 376 i, rq->rq_status.rqb_bits[i]); 377 for (j = 0; j < RQB_BPW; j++) 378 if (rq->rq_status.rqb_bits[i] & (1ul << j)) { 379 pri = j + (i << RQB_L2BPW); 380 rqh = &rq->rq_queues[pri]; 381 TAILQ_FOREACH(td, rqh, td_runq) { 382 printf("\t\t\ttd %p(%s) priority %d rqindex %d pri %d\n", 383 td, td->td_name, td->td_priority, 384 td->td_rqindex, pri); 385 } 386 } 387 } 388 } 389 390 /* 391 * Print the status of a per-cpu thread queue. Should be a ddb show cmd. 392 */ 393 void 394 tdq_print(int cpu) 395 { 396 struct tdq *tdq; 397 398 tdq = TDQ_CPU(cpu); 399 400 printf("tdq %d:\n", TDQ_ID(tdq)); 401 printf("\tlock %p\n", TDQ_LOCKPTR(tdq)); 402 printf("\tLock name: %s\n", tdq->tdq_name); 403 printf("\tload: %d\n", tdq->tdq_load); 404 printf("\tswitch cnt: %d\n", tdq->tdq_switchcnt); 405 printf("\told switch cnt: %d\n", tdq->tdq_oldswitchcnt); 406 printf("\ttimeshare idx: %d\n", tdq->tdq_idx); 407 printf("\ttimeshare ridx: %d\n", tdq->tdq_ridx); 408 printf("\tload transferable: %d\n", tdq->tdq_transferable); 409 printf("\tlowest priority: %d\n", tdq->tdq_lowpri); 410 printf("\trealtime runq:\n"); 411 runq_print(&tdq->tdq_realtime); 412 printf("\ttimeshare runq:\n"); 413 runq_print(&tdq->tdq_timeshare); 414 printf("\tidle runq:\n"); 415 runq_print(&tdq->tdq_idle); 416 } 417 418 static inline int 419 sched_shouldpreempt(int pri, int cpri, int remote) 420 { 421 /* 422 * If the new priority is not better than the current priority there is 423 * nothing to do. 424 */ 425 if (pri >= cpri) 426 return (0); 427 /* 428 * Always preempt idle. 429 */ 430 if (cpri >= PRI_MIN_IDLE) 431 return (1); 432 /* 433 * If preemption is disabled don't preempt others. 434 */ 435 if (preempt_thresh == 0) 436 return (0); 437 /* 438 * Preempt if we exceed the threshold. 439 */ 440 if (pri <= preempt_thresh) 441 return (1); 442 /* 443 * If we're interactive or better and there is non-interactive 444 * or worse running preempt only remote processors. 445 */ 446 if (remote && pri <= PRI_MAX_INTERACT && cpri > PRI_MAX_INTERACT) 447 return (1); 448 return (0); 449 } 450 451 /* 452 * Add a thread to the actual run-queue. Keeps transferable counts up to 453 * date with what is actually on the run-queue. Selects the correct 454 * queue position for timeshare threads. 455 */ 456 static __inline void 457 tdq_runq_add(struct tdq *tdq, struct thread *td, int flags) 458 { 459 struct td_sched *ts; 460 u_char pri; 461 462 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 463 THREAD_LOCK_ASSERT(td, MA_OWNED); 464 465 pri = td->td_priority; 466 ts = td->td_sched; 467 TD_SET_RUNQ(td); 468 if (THREAD_CAN_MIGRATE(td)) { 469 tdq->tdq_transferable++; 470 ts->ts_flags |= TSF_XFERABLE; 471 } 472 if (pri < PRI_MIN_BATCH) { 473 ts->ts_runq = &tdq->tdq_realtime; 474 } else if (pri <= PRI_MAX_BATCH) { 475 ts->ts_runq = &tdq->tdq_timeshare; 476 KASSERT(pri <= PRI_MAX_BATCH && pri >= PRI_MIN_BATCH, 477 ("Invalid priority %d on timeshare runq", pri)); 478 /* 479 * This queue contains only priorities between MIN and MAX 480 * realtime. Use the whole queue to represent these values. 481 */ 482 if ((flags & (SRQ_BORROWING|SRQ_PREEMPTED)) == 0) { 483 pri = RQ_NQS * (pri - PRI_MIN_BATCH) / PRI_BATCH_RANGE; 484 pri = (pri + tdq->tdq_idx) % RQ_NQS; 485 /* 486 * This effectively shortens the queue by one so we 487 * can have a one slot difference between idx and 488 * ridx while we wait for threads to drain. 489 */ 490 if (tdq->tdq_ridx != tdq->tdq_idx && 491 pri == tdq->tdq_ridx) 492 pri = (unsigned char)(pri - 1) % RQ_NQS; 493 } else 494 pri = tdq->tdq_ridx; 495 runq_add_pri(ts->ts_runq, td, pri, flags); 496 return; 497 } else 498 ts->ts_runq = &tdq->tdq_idle; 499 runq_add(ts->ts_runq, td, flags); 500 } 501 502 /* 503 * Remove a thread from a run-queue. This typically happens when a thread 504 * is selected to run. Running threads are not on the queue and the 505 * transferable count does not reflect them. 506 */ 507 static __inline void 508 tdq_runq_rem(struct tdq *tdq, struct thread *td) 509 { 510 struct td_sched *ts; 511 512 ts = td->td_sched; 513 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 514 KASSERT(ts->ts_runq != NULL, 515 ("tdq_runq_remove: thread %p null ts_runq", td)); 516 if (ts->ts_flags & TSF_XFERABLE) { 517 tdq->tdq_transferable--; 518 ts->ts_flags &= ~TSF_XFERABLE; 519 } 520 if (ts->ts_runq == &tdq->tdq_timeshare) { 521 if (tdq->tdq_idx != tdq->tdq_ridx) 522 runq_remove_idx(ts->ts_runq, td, &tdq->tdq_ridx); 523 else 524 runq_remove_idx(ts->ts_runq, td, NULL); 525 } else 526 runq_remove(ts->ts_runq, td); 527 } 528 529 /* 530 * Load is maintained for all threads RUNNING and ON_RUNQ. Add the load 531 * for this thread to the referenced thread queue. 532 */ 533 static void 534 tdq_load_add(struct tdq *tdq, struct thread *td) 535 { 536 537 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 538 THREAD_LOCK_ASSERT(td, MA_OWNED); 539 540 tdq->tdq_load++; 541 if ((td->td_flags & TDF_NOLOAD) == 0) 542 tdq->tdq_sysload++; 543 KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load); 544 SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load); 545 } 546 547 /* 548 * Remove the load from a thread that is transitioning to a sleep state or 549 * exiting. 550 */ 551 static void 552 tdq_load_rem(struct tdq *tdq, struct thread *td) 553 { 554 555 THREAD_LOCK_ASSERT(td, MA_OWNED); 556 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 557 KASSERT(tdq->tdq_load != 0, 558 ("tdq_load_rem: Removing with 0 load on queue %d", TDQ_ID(tdq))); 559 560 tdq->tdq_load--; 561 if ((td->td_flags & TDF_NOLOAD) == 0) 562 tdq->tdq_sysload--; 563 KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load); 564 SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load); 565 } 566 567 /* 568 * Bound timeshare latency by decreasing slice size as load increases. We 569 * consider the maximum latency as the sum of the threads waiting to run 570 * aside from curthread and target no more than sched_slice latency but 571 * no less than sched_slice_min runtime. 572 */ 573 static inline int 574 tdq_slice(struct tdq *tdq) 575 { 576 int load; 577 578 /* 579 * It is safe to use sys_load here because this is called from 580 * contexts where timeshare threads are running and so there 581 * cannot be higher priority load in the system. 582 */ 583 load = tdq->tdq_sysload - 1; 584 if (load >= SCHED_SLICE_MIN_DIVISOR) 585 return (sched_slice_min); 586 if (load <= 1) 587 return (sched_slice); 588 return (sched_slice / load); 589 } 590 591 /* 592 * Set lowpri to its exact value by searching the run-queue and 593 * evaluating curthread. curthread may be passed as an optimization. 594 */ 595 static void 596 tdq_setlowpri(struct tdq *tdq, struct thread *ctd) 597 { 598 struct thread *td; 599 600 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 601 if (ctd == NULL) 602 ctd = pcpu_find(TDQ_ID(tdq))->pc_curthread; 603 td = tdq_choose(tdq); 604 if (td == NULL || td->td_priority > ctd->td_priority) 605 tdq->tdq_lowpri = ctd->td_priority; 606 else 607 tdq->tdq_lowpri = td->td_priority; 608 } 609 610 #ifdef SMP 611 struct cpu_search { 612 cpuset_t cs_mask; 613 u_int cs_prefer; 614 int cs_pri; /* Min priority for low. */ 615 int cs_limit; /* Max load for low, min load for high. */ 616 int cs_cpu; 617 int cs_load; 618 }; 619 620 #define CPU_SEARCH_LOWEST 0x1 621 #define CPU_SEARCH_HIGHEST 0x2 622 #define CPU_SEARCH_BOTH (CPU_SEARCH_LOWEST|CPU_SEARCH_HIGHEST) 623 624 #define CPUSET_FOREACH(cpu, mask) \ 625 for ((cpu) = 0; (cpu) <= mp_maxid; (cpu)++) \ 626 if (CPU_ISSET(cpu, &mask)) 627 628 static __inline int cpu_search(const struct cpu_group *cg, struct cpu_search *low, 629 struct cpu_search *high, const int match); 630 int cpu_search_lowest(const struct cpu_group *cg, struct cpu_search *low); 631 int cpu_search_highest(const struct cpu_group *cg, struct cpu_search *high); 632 int cpu_search_both(const struct cpu_group *cg, struct cpu_search *low, 633 struct cpu_search *high); 634 635 /* 636 * Search the tree of cpu_groups for the lowest or highest loaded cpu 637 * according to the match argument. This routine actually compares the 638 * load on all paths through the tree and finds the least loaded cpu on 639 * the least loaded path, which may differ from the least loaded cpu in 640 * the system. This balances work among caches and busses. 641 * 642 * This inline is instantiated in three forms below using constants for the 643 * match argument. It is reduced to the minimum set for each case. It is 644 * also recursive to the depth of the tree. 645 */ 646 static __inline int 647 cpu_search(const struct cpu_group *cg, struct cpu_search *low, 648 struct cpu_search *high, const int match) 649 { 650 struct cpu_search lgroup; 651 struct cpu_search hgroup; 652 cpuset_t cpumask; 653 struct cpu_group *child; 654 struct tdq *tdq; 655 int cpu, i, hload, lload, load, total, rnd, *rndptr; 656 657 total = 0; 658 cpumask = cg->cg_mask; 659 if (match & CPU_SEARCH_LOWEST) { 660 lload = INT_MAX; 661 lgroup = *low; 662 } 663 if (match & CPU_SEARCH_HIGHEST) { 664 hload = INT_MIN; 665 hgroup = *high; 666 } 667 668 /* Iterate through the child CPU groups and then remaining CPUs. */ 669 for (i = cg->cg_children, cpu = mp_maxid; ; ) { 670 if (i == 0) { 671 #ifdef HAVE_INLINE_FFSL 672 cpu = CPU_FFS(&cpumask) - 1; 673 #else 674 while (cpu >= 0 && !CPU_ISSET(cpu, &cpumask)) 675 cpu--; 676 #endif 677 if (cpu < 0) 678 break; 679 child = NULL; 680 } else 681 child = &cg->cg_child[i - 1]; 682 683 if (match & CPU_SEARCH_LOWEST) 684 lgroup.cs_cpu = -1; 685 if (match & CPU_SEARCH_HIGHEST) 686 hgroup.cs_cpu = -1; 687 if (child) { /* Handle child CPU group. */ 688 CPU_NAND(&cpumask, &child->cg_mask); 689 switch (match) { 690 case CPU_SEARCH_LOWEST: 691 load = cpu_search_lowest(child, &lgroup); 692 break; 693 case CPU_SEARCH_HIGHEST: 694 load = cpu_search_highest(child, &hgroup); 695 break; 696 case CPU_SEARCH_BOTH: 697 load = cpu_search_both(child, &lgroup, &hgroup); 698 break; 699 } 700 } else { /* Handle child CPU. */ 701 CPU_CLR(cpu, &cpumask); 702 tdq = TDQ_CPU(cpu); 703 load = tdq->tdq_load * 256; 704 rndptr = DPCPU_PTR(randomval); 705 rnd = (*rndptr = *rndptr * 69069 + 5) >> 26; 706 if (match & CPU_SEARCH_LOWEST) { 707 if (cpu == low->cs_prefer) 708 load -= 64; 709 /* If that CPU is allowed and get data. */ 710 if (tdq->tdq_lowpri > lgroup.cs_pri && 711 tdq->tdq_load <= lgroup.cs_limit && 712 CPU_ISSET(cpu, &lgroup.cs_mask)) { 713 lgroup.cs_cpu = cpu; 714 lgroup.cs_load = load - rnd; 715 } 716 } 717 if (match & CPU_SEARCH_HIGHEST) 718 if (tdq->tdq_load >= hgroup.cs_limit && 719 tdq->tdq_transferable && 720 CPU_ISSET(cpu, &hgroup.cs_mask)) { 721 hgroup.cs_cpu = cpu; 722 hgroup.cs_load = load - rnd; 723 } 724 } 725 total += load; 726 727 /* We have info about child item. Compare it. */ 728 if (match & CPU_SEARCH_LOWEST) { 729 if (lgroup.cs_cpu >= 0 && 730 (load < lload || 731 (load == lload && lgroup.cs_load < low->cs_load))) { 732 lload = load; 733 low->cs_cpu = lgroup.cs_cpu; 734 low->cs_load = lgroup.cs_load; 735 } 736 } 737 if (match & CPU_SEARCH_HIGHEST) 738 if (hgroup.cs_cpu >= 0 && 739 (load > hload || 740 (load == hload && hgroup.cs_load > high->cs_load))) { 741 hload = load; 742 high->cs_cpu = hgroup.cs_cpu; 743 high->cs_load = hgroup.cs_load; 744 } 745 if (child) { 746 i--; 747 if (i == 0 && CPU_EMPTY(&cpumask)) 748 break; 749 } 750 #ifndef HAVE_INLINE_FFSL 751 else 752 cpu--; 753 #endif 754 } 755 return (total); 756 } 757 758 /* 759 * cpu_search instantiations must pass constants to maintain the inline 760 * optimization. 761 */ 762 int 763 cpu_search_lowest(const struct cpu_group *cg, struct cpu_search *low) 764 { 765 return cpu_search(cg, low, NULL, CPU_SEARCH_LOWEST); 766 } 767 768 int 769 cpu_search_highest(const struct cpu_group *cg, struct cpu_search *high) 770 { 771 return cpu_search(cg, NULL, high, CPU_SEARCH_HIGHEST); 772 } 773 774 int 775 cpu_search_both(const struct cpu_group *cg, struct cpu_search *low, 776 struct cpu_search *high) 777 { 778 return cpu_search(cg, low, high, CPU_SEARCH_BOTH); 779 } 780 781 /* 782 * Find the cpu with the least load via the least loaded path that has a 783 * lowpri greater than pri pri. A pri of -1 indicates any priority is 784 * acceptable. 785 */ 786 static inline int 787 sched_lowest(const struct cpu_group *cg, cpuset_t mask, int pri, int maxload, 788 int prefer) 789 { 790 struct cpu_search low; 791 792 low.cs_cpu = -1; 793 low.cs_prefer = prefer; 794 low.cs_mask = mask; 795 low.cs_pri = pri; 796 low.cs_limit = maxload; 797 cpu_search_lowest(cg, &low); 798 return low.cs_cpu; 799 } 800 801 /* 802 * Find the cpu with the highest load via the highest loaded path. 803 */ 804 static inline int 805 sched_highest(const struct cpu_group *cg, cpuset_t mask, int minload) 806 { 807 struct cpu_search high; 808 809 high.cs_cpu = -1; 810 high.cs_mask = mask; 811 high.cs_limit = minload; 812 cpu_search_highest(cg, &high); 813 return high.cs_cpu; 814 } 815 816 static void 817 sched_balance_group(struct cpu_group *cg) 818 { 819 cpuset_t hmask, lmask; 820 int high, low, anylow; 821 822 CPU_FILL(&hmask); 823 for (;;) { 824 high = sched_highest(cg, hmask, 1); 825 /* Stop if there is no more CPU with transferrable threads. */ 826 if (high == -1) 827 break; 828 CPU_CLR(high, &hmask); 829 CPU_COPY(&hmask, &lmask); 830 /* Stop if there is no more CPU left for low. */ 831 if (CPU_EMPTY(&lmask)) 832 break; 833 anylow = 1; 834 nextlow: 835 low = sched_lowest(cg, lmask, -1, 836 TDQ_CPU(high)->tdq_load - 1, high); 837 /* Stop if we looked well and found no less loaded CPU. */ 838 if (anylow && low == -1) 839 break; 840 /* Go to next high if we found no less loaded CPU. */ 841 if (low == -1) 842 continue; 843 /* Transfer thread from high to low. */ 844 if (sched_balance_pair(TDQ_CPU(high), TDQ_CPU(low))) { 845 /* CPU that got thread can no longer be a donor. */ 846 CPU_CLR(low, &hmask); 847 } else { 848 /* 849 * If failed, then there is no threads on high 850 * that can run on this low. Drop low from low 851 * mask and look for different one. 852 */ 853 CPU_CLR(low, &lmask); 854 anylow = 0; 855 goto nextlow; 856 } 857 } 858 } 859 860 static void 861 sched_balance(void) 862 { 863 struct tdq *tdq; 864 865 /* 866 * Select a random time between .5 * balance_interval and 867 * 1.5 * balance_interval. 868 */ 869 balance_ticks = max(balance_interval / 2, 1); 870 balance_ticks += random() % balance_interval; 871 if (smp_started == 0 || rebalance == 0) 872 return; 873 tdq = TDQ_SELF(); 874 TDQ_UNLOCK(tdq); 875 sched_balance_group(cpu_top); 876 TDQ_LOCK(tdq); 877 } 878 879 /* 880 * Lock two thread queues using their address to maintain lock order. 881 */ 882 static void 883 tdq_lock_pair(struct tdq *one, struct tdq *two) 884 { 885 if (one < two) { 886 TDQ_LOCK(one); 887 TDQ_LOCK_FLAGS(two, MTX_DUPOK); 888 } else { 889 TDQ_LOCK(two); 890 TDQ_LOCK_FLAGS(one, MTX_DUPOK); 891 } 892 } 893 894 /* 895 * Unlock two thread queues. Order is not important here. 896 */ 897 static void 898 tdq_unlock_pair(struct tdq *one, struct tdq *two) 899 { 900 TDQ_UNLOCK(one); 901 TDQ_UNLOCK(two); 902 } 903 904 /* 905 * Transfer load between two imbalanced thread queues. 906 */ 907 static int 908 sched_balance_pair(struct tdq *high, struct tdq *low) 909 { 910 int moved; 911 int cpu; 912 913 tdq_lock_pair(high, low); 914 moved = 0; 915 /* 916 * Determine what the imbalance is and then adjust that to how many 917 * threads we actually have to give up (transferable). 918 */ 919 if (high->tdq_transferable != 0 && high->tdq_load > low->tdq_load && 920 (moved = tdq_move(high, low)) > 0) { 921 /* 922 * In case the target isn't the current cpu IPI it to force a 923 * reschedule with the new workload. 924 */ 925 cpu = TDQ_ID(low); 926 if (cpu != PCPU_GET(cpuid)) 927 ipi_cpu(cpu, IPI_PREEMPT); 928 } 929 tdq_unlock_pair(high, low); 930 return (moved); 931 } 932 933 /* 934 * Move a thread from one thread queue to another. 935 */ 936 static int 937 tdq_move(struct tdq *from, struct tdq *to) 938 { 939 struct td_sched *ts; 940 struct thread *td; 941 struct tdq *tdq; 942 int cpu; 943 944 TDQ_LOCK_ASSERT(from, MA_OWNED); 945 TDQ_LOCK_ASSERT(to, MA_OWNED); 946 947 tdq = from; 948 cpu = TDQ_ID(to); 949 td = tdq_steal(tdq, cpu); 950 if (td == NULL) 951 return (0); 952 ts = td->td_sched; 953 /* 954 * Although the run queue is locked the thread may be blocked. Lock 955 * it to clear this and acquire the run-queue lock. 956 */ 957 thread_lock(td); 958 /* Drop recursive lock on from acquired via thread_lock(). */ 959 TDQ_UNLOCK(from); 960 sched_rem(td); 961 ts->ts_cpu = cpu; 962 td->td_lock = TDQ_LOCKPTR(to); 963 tdq_add(to, td, SRQ_YIELDING); 964 return (1); 965 } 966 967 /* 968 * This tdq has idled. Try to steal a thread from another cpu and switch 969 * to it. 970 */ 971 static int 972 tdq_idled(struct tdq *tdq) 973 { 974 struct cpu_group *cg; 975 struct tdq *steal; 976 cpuset_t mask; 977 int thresh; 978 int cpu; 979 980 if (smp_started == 0 || steal_idle == 0) 981 return (1); 982 CPU_FILL(&mask); 983 CPU_CLR(PCPU_GET(cpuid), &mask); 984 /* We don't want to be preempted while we're iterating. */ 985 spinlock_enter(); 986 for (cg = tdq->tdq_cg; cg != NULL; ) { 987 if ((cg->cg_flags & CG_FLAG_THREAD) == 0) 988 thresh = steal_thresh; 989 else 990 thresh = 1; 991 cpu = sched_highest(cg, mask, thresh); 992 if (cpu == -1) { 993 cg = cg->cg_parent; 994 continue; 995 } 996 steal = TDQ_CPU(cpu); 997 CPU_CLR(cpu, &mask); 998 tdq_lock_pair(tdq, steal); 999 if (steal->tdq_load < thresh || steal->tdq_transferable == 0) { 1000 tdq_unlock_pair(tdq, steal); 1001 continue; 1002 } 1003 /* 1004 * If a thread was added while interrupts were disabled don't 1005 * steal one here. If we fail to acquire one due to affinity 1006 * restrictions loop again with this cpu removed from the 1007 * set. 1008 */ 1009 if (tdq->tdq_load == 0 && tdq_move(steal, tdq) == 0) { 1010 tdq_unlock_pair(tdq, steal); 1011 continue; 1012 } 1013 spinlock_exit(); 1014 TDQ_UNLOCK(steal); 1015 mi_switch(SW_VOL | SWT_IDLE, NULL); 1016 thread_unlock(curthread); 1017 1018 return (0); 1019 } 1020 spinlock_exit(); 1021 return (1); 1022 } 1023 1024 /* 1025 * Notify a remote cpu of new work. Sends an IPI if criteria are met. 1026 */ 1027 static void 1028 tdq_notify(struct tdq *tdq, struct thread *td) 1029 { 1030 struct thread *ctd; 1031 int pri; 1032 int cpu; 1033 1034 if (tdq->tdq_ipipending) 1035 return; 1036 cpu = td->td_sched->ts_cpu; 1037 pri = td->td_priority; 1038 ctd = pcpu_find(cpu)->pc_curthread; 1039 if (!sched_shouldpreempt(pri, ctd->td_priority, 1)) 1040 return; 1041 if (TD_IS_IDLETHREAD(ctd)) { 1042 /* 1043 * If the MD code has an idle wakeup routine try that before 1044 * falling back to IPI. 1045 */ 1046 if (!tdq->tdq_cpu_idle || cpu_idle_wakeup(cpu)) 1047 return; 1048 } 1049 tdq->tdq_ipipending = 1; 1050 ipi_cpu(cpu, IPI_PREEMPT); 1051 } 1052 1053 /* 1054 * Steals load from a timeshare queue. Honors the rotating queue head 1055 * index. 1056 */ 1057 static struct thread * 1058 runq_steal_from(struct runq *rq, int cpu, u_char start) 1059 { 1060 struct rqbits *rqb; 1061 struct rqhead *rqh; 1062 struct thread *td, *first; 1063 int bit; 1064 int pri; 1065 int i; 1066 1067 rqb = &rq->rq_status; 1068 bit = start & (RQB_BPW -1); 1069 pri = 0; 1070 first = NULL; 1071 again: 1072 for (i = RQB_WORD(start); i < RQB_LEN; bit = 0, i++) { 1073 if (rqb->rqb_bits[i] == 0) 1074 continue; 1075 if (bit != 0) { 1076 for (pri = bit; pri < RQB_BPW; pri++) 1077 if (rqb->rqb_bits[i] & (1ul << pri)) 1078 break; 1079 if (pri >= RQB_BPW) 1080 continue; 1081 } else 1082 pri = RQB_FFS(rqb->rqb_bits[i]); 1083 pri += (i << RQB_L2BPW); 1084 rqh = &rq->rq_queues[pri]; 1085 TAILQ_FOREACH(td, rqh, td_runq) { 1086 if (first && THREAD_CAN_MIGRATE(td) && 1087 THREAD_CAN_SCHED(td, cpu)) 1088 return (td); 1089 first = td; 1090 } 1091 } 1092 if (start != 0) { 1093 start = 0; 1094 goto again; 1095 } 1096 1097 if (first && THREAD_CAN_MIGRATE(first) && 1098 THREAD_CAN_SCHED(first, cpu)) 1099 return (first); 1100 return (NULL); 1101 } 1102 1103 /* 1104 * Steals load from a standard linear queue. 1105 */ 1106 static struct thread * 1107 runq_steal(struct runq *rq, int cpu) 1108 { 1109 struct rqhead *rqh; 1110 struct rqbits *rqb; 1111 struct thread *td; 1112 int word; 1113 int bit; 1114 1115 rqb = &rq->rq_status; 1116 for (word = 0; word < RQB_LEN; word++) { 1117 if (rqb->rqb_bits[word] == 0) 1118 continue; 1119 for (bit = 0; bit < RQB_BPW; bit++) { 1120 if ((rqb->rqb_bits[word] & (1ul << bit)) == 0) 1121 continue; 1122 rqh = &rq->rq_queues[bit + (word << RQB_L2BPW)]; 1123 TAILQ_FOREACH(td, rqh, td_runq) 1124 if (THREAD_CAN_MIGRATE(td) && 1125 THREAD_CAN_SCHED(td, cpu)) 1126 return (td); 1127 } 1128 } 1129 return (NULL); 1130 } 1131 1132 /* 1133 * Attempt to steal a thread in priority order from a thread queue. 1134 */ 1135 static struct thread * 1136 tdq_steal(struct tdq *tdq, int cpu) 1137 { 1138 struct thread *td; 1139 1140 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1141 if ((td = runq_steal(&tdq->tdq_realtime, cpu)) != NULL) 1142 return (td); 1143 if ((td = runq_steal_from(&tdq->tdq_timeshare, 1144 cpu, tdq->tdq_ridx)) != NULL) 1145 return (td); 1146 return (runq_steal(&tdq->tdq_idle, cpu)); 1147 } 1148 1149 /* 1150 * Sets the thread lock and ts_cpu to match the requested cpu. Unlocks the 1151 * current lock and returns with the assigned queue locked. 1152 */ 1153 static inline struct tdq * 1154 sched_setcpu(struct thread *td, int cpu, int flags) 1155 { 1156 1157 struct tdq *tdq; 1158 1159 THREAD_LOCK_ASSERT(td, MA_OWNED); 1160 tdq = TDQ_CPU(cpu); 1161 td->td_sched->ts_cpu = cpu; 1162 /* 1163 * If the lock matches just return the queue. 1164 */ 1165 if (td->td_lock == TDQ_LOCKPTR(tdq)) 1166 return (tdq); 1167 #ifdef notyet 1168 /* 1169 * If the thread isn't running its lockptr is a 1170 * turnstile or a sleepqueue. We can just lock_set without 1171 * blocking. 1172 */ 1173 if (TD_CAN_RUN(td)) { 1174 TDQ_LOCK(tdq); 1175 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 1176 return (tdq); 1177 } 1178 #endif 1179 /* 1180 * The hard case, migration, we need to block the thread first to 1181 * prevent order reversals with other cpus locks. 1182 */ 1183 spinlock_enter(); 1184 thread_lock_block(td); 1185 TDQ_LOCK(tdq); 1186 thread_lock_unblock(td, TDQ_LOCKPTR(tdq)); 1187 spinlock_exit(); 1188 return (tdq); 1189 } 1190 1191 SCHED_STAT_DEFINE(pickcpu_intrbind, "Soft interrupt binding"); 1192 SCHED_STAT_DEFINE(pickcpu_idle_affinity, "Picked idle cpu based on affinity"); 1193 SCHED_STAT_DEFINE(pickcpu_affinity, "Picked cpu based on affinity"); 1194 SCHED_STAT_DEFINE(pickcpu_lowest, "Selected lowest load"); 1195 SCHED_STAT_DEFINE(pickcpu_local, "Migrated to current cpu"); 1196 SCHED_STAT_DEFINE(pickcpu_migration, "Selection may have caused migration"); 1197 1198 static int 1199 sched_pickcpu(struct thread *td, int flags) 1200 { 1201 struct cpu_group *cg, *ccg; 1202 struct td_sched *ts; 1203 struct tdq *tdq; 1204 cpuset_t mask; 1205 int cpu, pri, self; 1206 1207 self = PCPU_GET(cpuid); 1208 ts = td->td_sched; 1209 if (smp_started == 0) 1210 return (self); 1211 /* 1212 * Don't migrate a running thread from sched_switch(). 1213 */ 1214 if ((flags & SRQ_OURSELF) || !THREAD_CAN_MIGRATE(td)) 1215 return (ts->ts_cpu); 1216 /* 1217 * Prefer to run interrupt threads on the processors that generate 1218 * the interrupt. 1219 */ 1220 pri = td->td_priority; 1221 if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_SCHED(td, self) && 1222 curthread->td_intr_nesting_level && ts->ts_cpu != self) { 1223 SCHED_STAT_INC(pickcpu_intrbind); 1224 ts->ts_cpu = self; 1225 if (TDQ_CPU(self)->tdq_lowpri > pri) { 1226 SCHED_STAT_INC(pickcpu_affinity); 1227 return (ts->ts_cpu); 1228 } 1229 } 1230 /* 1231 * If the thread can run on the last cpu and the affinity has not 1232 * expired or it is idle run it there. 1233 */ 1234 tdq = TDQ_CPU(ts->ts_cpu); 1235 cg = tdq->tdq_cg; 1236 if (THREAD_CAN_SCHED(td, ts->ts_cpu) && 1237 tdq->tdq_lowpri >= PRI_MIN_IDLE && 1238 SCHED_AFFINITY(ts, CG_SHARE_L2)) { 1239 if (cg->cg_flags & CG_FLAG_THREAD) { 1240 CPUSET_FOREACH(cpu, cg->cg_mask) { 1241 if (TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE) 1242 break; 1243 } 1244 } else 1245 cpu = INT_MAX; 1246 if (cpu > mp_maxid) { 1247 SCHED_STAT_INC(pickcpu_idle_affinity); 1248 return (ts->ts_cpu); 1249 } 1250 } 1251 /* 1252 * Search for the last level cache CPU group in the tree. 1253 * Skip caches with expired affinity time and SMT groups. 1254 * Affinity to higher level caches will be handled less aggressively. 1255 */ 1256 for (ccg = NULL; cg != NULL; cg = cg->cg_parent) { 1257 if (cg->cg_flags & CG_FLAG_THREAD) 1258 continue; 1259 if (!SCHED_AFFINITY(ts, cg->cg_level)) 1260 continue; 1261 ccg = cg; 1262 } 1263 if (ccg != NULL) 1264 cg = ccg; 1265 cpu = -1; 1266 /* Search the group for the less loaded idle CPU we can run now. */ 1267 mask = td->td_cpuset->cs_mask; 1268 if (cg != NULL && cg != cpu_top && 1269 CPU_CMP(&cg->cg_mask, &cpu_top->cg_mask) != 0) 1270 cpu = sched_lowest(cg, mask, max(pri, PRI_MAX_TIMESHARE), 1271 INT_MAX, ts->ts_cpu); 1272 /* Search globally for the less loaded CPU we can run now. */ 1273 if (cpu == -1) 1274 cpu = sched_lowest(cpu_top, mask, pri, INT_MAX, ts->ts_cpu); 1275 /* Search globally for the less loaded CPU. */ 1276 if (cpu == -1) 1277 cpu = sched_lowest(cpu_top, mask, -1, INT_MAX, ts->ts_cpu); 1278 KASSERT(cpu != -1, ("sched_pickcpu: Failed to find a cpu.")); 1279 /* 1280 * Compare the lowest loaded cpu to current cpu. 1281 */ 1282 if (THREAD_CAN_SCHED(td, self) && TDQ_CPU(self)->tdq_lowpri > pri && 1283 TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE && 1284 TDQ_CPU(self)->tdq_load <= TDQ_CPU(cpu)->tdq_load + 1) { 1285 SCHED_STAT_INC(pickcpu_local); 1286 cpu = self; 1287 } else 1288 SCHED_STAT_INC(pickcpu_lowest); 1289 if (cpu != ts->ts_cpu) 1290 SCHED_STAT_INC(pickcpu_migration); 1291 return (cpu); 1292 } 1293 #endif 1294 1295 /* 1296 * Pick the highest priority task we have and return it. 1297 */ 1298 static struct thread * 1299 tdq_choose(struct tdq *tdq) 1300 { 1301 struct thread *td; 1302 1303 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1304 td = runq_choose(&tdq->tdq_realtime); 1305 if (td != NULL) 1306 return (td); 1307 td = runq_choose_from(&tdq->tdq_timeshare, tdq->tdq_ridx); 1308 if (td != NULL) { 1309 KASSERT(td->td_priority >= PRI_MIN_BATCH, 1310 ("tdq_choose: Invalid priority on timeshare queue %d", 1311 td->td_priority)); 1312 return (td); 1313 } 1314 td = runq_choose(&tdq->tdq_idle); 1315 if (td != NULL) { 1316 KASSERT(td->td_priority >= PRI_MIN_IDLE, 1317 ("tdq_choose: Invalid priority on idle queue %d", 1318 td->td_priority)); 1319 return (td); 1320 } 1321 1322 return (NULL); 1323 } 1324 1325 /* 1326 * Initialize a thread queue. 1327 */ 1328 static void 1329 tdq_setup(struct tdq *tdq) 1330 { 1331 1332 if (bootverbose) 1333 printf("ULE: setup cpu %d\n", TDQ_ID(tdq)); 1334 runq_init(&tdq->tdq_realtime); 1335 runq_init(&tdq->tdq_timeshare); 1336 runq_init(&tdq->tdq_idle); 1337 snprintf(tdq->tdq_name, sizeof(tdq->tdq_name), 1338 "sched lock %d", (int)TDQ_ID(tdq)); 1339 mtx_init(&tdq->tdq_lock, tdq->tdq_name, "sched lock", 1340 MTX_SPIN | MTX_RECURSE); 1341 #ifdef KTR 1342 snprintf(tdq->tdq_loadname, sizeof(tdq->tdq_loadname), 1343 "CPU %d load", (int)TDQ_ID(tdq)); 1344 #endif 1345 } 1346 1347 #ifdef SMP 1348 static void 1349 sched_setup_smp(void) 1350 { 1351 struct tdq *tdq; 1352 int i; 1353 1354 cpu_top = smp_topo(); 1355 CPU_FOREACH(i) { 1356 tdq = TDQ_CPU(i); 1357 tdq_setup(tdq); 1358 tdq->tdq_cg = smp_topo_find(cpu_top, i); 1359 if (tdq->tdq_cg == NULL) 1360 panic("Can't find cpu group for %d\n", i); 1361 } 1362 balance_tdq = TDQ_SELF(); 1363 sched_balance(); 1364 } 1365 #endif 1366 1367 /* 1368 * Setup the thread queues and initialize the topology based on MD 1369 * information. 1370 */ 1371 static void 1372 sched_setup(void *dummy) 1373 { 1374 struct tdq *tdq; 1375 1376 tdq = TDQ_SELF(); 1377 #ifdef SMP 1378 sched_setup_smp(); 1379 #else 1380 tdq_setup(tdq); 1381 #endif 1382 1383 /* Add thread0's load since it's running. */ 1384 TDQ_LOCK(tdq); 1385 thread0.td_lock = TDQ_LOCKPTR(TDQ_SELF()); 1386 tdq_load_add(tdq, &thread0); 1387 tdq->tdq_lowpri = thread0.td_priority; 1388 TDQ_UNLOCK(tdq); 1389 } 1390 1391 /* 1392 * This routine determines time constants after stathz and hz are setup. 1393 */ 1394 /* ARGSUSED */ 1395 static void 1396 sched_initticks(void *dummy) 1397 { 1398 int incr; 1399 1400 realstathz = stathz ? stathz : hz; 1401 sched_slice = realstathz / SCHED_SLICE_DEFAULT_DIVISOR; 1402 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 1403 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 1404 realstathz); 1405 1406 /* 1407 * tickincr is shifted out by 10 to avoid rounding errors due to 1408 * hz not being evenly divisible by stathz on all platforms. 1409 */ 1410 incr = (hz << SCHED_TICK_SHIFT) / realstathz; 1411 /* 1412 * This does not work for values of stathz that are more than 1413 * 1 << SCHED_TICK_SHIFT * hz. In practice this does not happen. 1414 */ 1415 if (incr == 0) 1416 incr = 1; 1417 tickincr = incr; 1418 #ifdef SMP 1419 /* 1420 * Set the default balance interval now that we know 1421 * what realstathz is. 1422 */ 1423 balance_interval = realstathz; 1424 affinity = SCHED_AFFINITY_DEFAULT; 1425 #endif 1426 if (sched_idlespinthresh < 0) 1427 sched_idlespinthresh = 2 * max(10000, 6 * hz) / realstathz; 1428 } 1429 1430 1431 /* 1432 * This is the core of the interactivity algorithm. Determines a score based 1433 * on past behavior. It is the ratio of sleep time to run time scaled to 1434 * a [0, 100] integer. This is the voluntary sleep time of a process, which 1435 * differs from the cpu usage because it does not account for time spent 1436 * waiting on a run-queue. Would be prettier if we had floating point. 1437 */ 1438 static int 1439 sched_interact_score(struct thread *td) 1440 { 1441 struct td_sched *ts; 1442 int div; 1443 1444 ts = td->td_sched; 1445 /* 1446 * The score is only needed if this is likely to be an interactive 1447 * task. Don't go through the expense of computing it if there's 1448 * no chance. 1449 */ 1450 if (sched_interact <= SCHED_INTERACT_HALF && 1451 ts->ts_runtime >= ts->ts_slptime) 1452 return (SCHED_INTERACT_HALF); 1453 1454 if (ts->ts_runtime > ts->ts_slptime) { 1455 div = max(1, ts->ts_runtime / SCHED_INTERACT_HALF); 1456 return (SCHED_INTERACT_HALF + 1457 (SCHED_INTERACT_HALF - (ts->ts_slptime / div))); 1458 } 1459 if (ts->ts_slptime > ts->ts_runtime) { 1460 div = max(1, ts->ts_slptime / SCHED_INTERACT_HALF); 1461 return (ts->ts_runtime / div); 1462 } 1463 /* runtime == slptime */ 1464 if (ts->ts_runtime) 1465 return (SCHED_INTERACT_HALF); 1466 1467 /* 1468 * This can happen if slptime and runtime are 0. 1469 */ 1470 return (0); 1471 1472 } 1473 1474 /* 1475 * Scale the scheduling priority according to the "interactivity" of this 1476 * process. 1477 */ 1478 static void 1479 sched_priority(struct thread *td) 1480 { 1481 int score; 1482 int pri; 1483 1484 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 1485 return; 1486 /* 1487 * If the score is interactive we place the thread in the realtime 1488 * queue with a priority that is less than kernel and interrupt 1489 * priorities. These threads are not subject to nice restrictions. 1490 * 1491 * Scores greater than this are placed on the normal timeshare queue 1492 * where the priority is partially decided by the most recent cpu 1493 * utilization and the rest is decided by nice value. 1494 * 1495 * The nice value of the process has a linear effect on the calculated 1496 * score. Negative nice values make it easier for a thread to be 1497 * considered interactive. 1498 */ 1499 score = imax(0, sched_interact_score(td) + td->td_proc->p_nice); 1500 if (score < sched_interact) { 1501 pri = PRI_MIN_INTERACT; 1502 pri += ((PRI_MAX_INTERACT - PRI_MIN_INTERACT + 1) / 1503 sched_interact) * score; 1504 KASSERT(pri >= PRI_MIN_INTERACT && pri <= PRI_MAX_INTERACT, 1505 ("sched_priority: invalid interactive priority %d score %d", 1506 pri, score)); 1507 } else { 1508 pri = SCHED_PRI_MIN; 1509 if (td->td_sched->ts_ticks) 1510 pri += min(SCHED_PRI_TICKS(td->td_sched), 1511 SCHED_PRI_RANGE - 1); 1512 pri += SCHED_PRI_NICE(td->td_proc->p_nice); 1513 KASSERT(pri >= PRI_MIN_BATCH && pri <= PRI_MAX_BATCH, 1514 ("sched_priority: invalid priority %d: nice %d, " 1515 "ticks %d ftick %d ltick %d tick pri %d", 1516 pri, td->td_proc->p_nice, td->td_sched->ts_ticks, 1517 td->td_sched->ts_ftick, td->td_sched->ts_ltick, 1518 SCHED_PRI_TICKS(td->td_sched))); 1519 } 1520 sched_user_prio(td, pri); 1521 1522 return; 1523 } 1524 1525 /* 1526 * This routine enforces a maximum limit on the amount of scheduling history 1527 * kept. It is called after either the slptime or runtime is adjusted. This 1528 * function is ugly due to integer math. 1529 */ 1530 static void 1531 sched_interact_update(struct thread *td) 1532 { 1533 struct td_sched *ts; 1534 u_int sum; 1535 1536 ts = td->td_sched; 1537 sum = ts->ts_runtime + ts->ts_slptime; 1538 if (sum < SCHED_SLP_RUN_MAX) 1539 return; 1540 /* 1541 * This only happens from two places: 1542 * 1) We have added an unusual amount of run time from fork_exit. 1543 * 2) We have added an unusual amount of sleep time from sched_sleep(). 1544 */ 1545 if (sum > SCHED_SLP_RUN_MAX * 2) { 1546 if (ts->ts_runtime > ts->ts_slptime) { 1547 ts->ts_runtime = SCHED_SLP_RUN_MAX; 1548 ts->ts_slptime = 1; 1549 } else { 1550 ts->ts_slptime = SCHED_SLP_RUN_MAX; 1551 ts->ts_runtime = 1; 1552 } 1553 return; 1554 } 1555 /* 1556 * If we have exceeded by more than 1/5th then the algorithm below 1557 * will not bring us back into range. Dividing by two here forces 1558 * us into the range of [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX] 1559 */ 1560 if (sum > (SCHED_SLP_RUN_MAX / 5) * 6) { 1561 ts->ts_runtime /= 2; 1562 ts->ts_slptime /= 2; 1563 return; 1564 } 1565 ts->ts_runtime = (ts->ts_runtime / 5) * 4; 1566 ts->ts_slptime = (ts->ts_slptime / 5) * 4; 1567 } 1568 1569 /* 1570 * Scale back the interactivity history when a child thread is created. The 1571 * history is inherited from the parent but the thread may behave totally 1572 * differently. For example, a shell spawning a compiler process. We want 1573 * to learn that the compiler is behaving badly very quickly. 1574 */ 1575 static void 1576 sched_interact_fork(struct thread *td) 1577 { 1578 int ratio; 1579 int sum; 1580 1581 sum = td->td_sched->ts_runtime + td->td_sched->ts_slptime; 1582 if (sum > SCHED_SLP_RUN_FORK) { 1583 ratio = sum / SCHED_SLP_RUN_FORK; 1584 td->td_sched->ts_runtime /= ratio; 1585 td->td_sched->ts_slptime /= ratio; 1586 } 1587 } 1588 1589 /* 1590 * Called from proc0_init() to setup the scheduler fields. 1591 */ 1592 void 1593 schedinit(void) 1594 { 1595 1596 /* 1597 * Set up the scheduler specific parts of proc0. 1598 */ 1599 proc0.p_sched = NULL; /* XXX */ 1600 thread0.td_sched = &td_sched0; 1601 td_sched0.ts_ltick = ticks; 1602 td_sched0.ts_ftick = ticks; 1603 td_sched0.ts_slice = 0; 1604 } 1605 1606 /* 1607 * This is only somewhat accurate since given many processes of the same 1608 * priority they will switch when their slices run out, which will be 1609 * at most sched_slice stathz ticks. 1610 */ 1611 int 1612 sched_rr_interval(void) 1613 { 1614 1615 /* Convert sched_slice from stathz to hz. */ 1616 return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz)); 1617 } 1618 1619 /* 1620 * Update the percent cpu tracking information when it is requested or 1621 * the total history exceeds the maximum. We keep a sliding history of 1622 * tick counts that slowly decays. This is less precise than the 4BSD 1623 * mechanism since it happens with less regular and frequent events. 1624 */ 1625 static void 1626 sched_pctcpu_update(struct td_sched *ts, int run) 1627 { 1628 int t = ticks; 1629 1630 if (t - ts->ts_ltick >= SCHED_TICK_TARG) { 1631 ts->ts_ticks = 0; 1632 ts->ts_ftick = t - SCHED_TICK_TARG; 1633 } else if (t - ts->ts_ftick >= SCHED_TICK_MAX) { 1634 ts->ts_ticks = (ts->ts_ticks / (ts->ts_ltick - ts->ts_ftick)) * 1635 (ts->ts_ltick - (t - SCHED_TICK_TARG)); 1636 ts->ts_ftick = t - SCHED_TICK_TARG; 1637 } 1638 if (run) 1639 ts->ts_ticks += (t - ts->ts_ltick) << SCHED_TICK_SHIFT; 1640 ts->ts_ltick = t; 1641 } 1642 1643 /* 1644 * Adjust the priority of a thread. Move it to the appropriate run-queue 1645 * if necessary. This is the back-end for several priority related 1646 * functions. 1647 */ 1648 static void 1649 sched_thread_priority(struct thread *td, u_char prio) 1650 { 1651 struct td_sched *ts; 1652 struct tdq *tdq; 1653 int oldpri; 1654 1655 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "prio", 1656 "prio:%d", td->td_priority, "new prio:%d", prio, 1657 KTR_ATTR_LINKED, sched_tdname(curthread)); 1658 SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio); 1659 if (td != curthread && prio < td->td_priority) { 1660 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread), 1661 "lend prio", "prio:%d", td->td_priority, "new prio:%d", 1662 prio, KTR_ATTR_LINKED, sched_tdname(td)); 1663 SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio, 1664 curthread); 1665 } 1666 ts = td->td_sched; 1667 THREAD_LOCK_ASSERT(td, MA_OWNED); 1668 if (td->td_priority == prio) 1669 return; 1670 /* 1671 * If the priority has been elevated due to priority 1672 * propagation, we may have to move ourselves to a new 1673 * queue. This could be optimized to not re-add in some 1674 * cases. 1675 */ 1676 if (TD_ON_RUNQ(td) && prio < td->td_priority) { 1677 sched_rem(td); 1678 td->td_priority = prio; 1679 sched_add(td, SRQ_BORROWING); 1680 return; 1681 } 1682 /* 1683 * If the thread is currently running we may have to adjust the lowpri 1684 * information so other cpus are aware of our current priority. 1685 */ 1686 if (TD_IS_RUNNING(td)) { 1687 tdq = TDQ_CPU(ts->ts_cpu); 1688 oldpri = td->td_priority; 1689 td->td_priority = prio; 1690 if (prio < tdq->tdq_lowpri) 1691 tdq->tdq_lowpri = prio; 1692 else if (tdq->tdq_lowpri == oldpri) 1693 tdq_setlowpri(tdq, td); 1694 return; 1695 } 1696 td->td_priority = prio; 1697 } 1698 1699 /* 1700 * Update a thread's priority when it is lent another thread's 1701 * priority. 1702 */ 1703 void 1704 sched_lend_prio(struct thread *td, u_char prio) 1705 { 1706 1707 td->td_flags |= TDF_BORROWING; 1708 sched_thread_priority(td, prio); 1709 } 1710 1711 /* 1712 * Restore a thread's priority when priority propagation is 1713 * over. The prio argument is the minimum priority the thread 1714 * needs to have to satisfy other possible priority lending 1715 * requests. If the thread's regular priority is less 1716 * important than prio, the thread will keep a priority boost 1717 * of prio. 1718 */ 1719 void 1720 sched_unlend_prio(struct thread *td, u_char prio) 1721 { 1722 u_char base_pri; 1723 1724 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 1725 td->td_base_pri <= PRI_MAX_TIMESHARE) 1726 base_pri = td->td_user_pri; 1727 else 1728 base_pri = td->td_base_pri; 1729 if (prio >= base_pri) { 1730 td->td_flags &= ~TDF_BORROWING; 1731 sched_thread_priority(td, base_pri); 1732 } else 1733 sched_lend_prio(td, prio); 1734 } 1735 1736 /* 1737 * Standard entry for setting the priority to an absolute value. 1738 */ 1739 void 1740 sched_prio(struct thread *td, u_char prio) 1741 { 1742 u_char oldprio; 1743 1744 /* First, update the base priority. */ 1745 td->td_base_pri = prio; 1746 1747 /* 1748 * If the thread is borrowing another thread's priority, don't 1749 * ever lower the priority. 1750 */ 1751 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 1752 return; 1753 1754 /* Change the real priority. */ 1755 oldprio = td->td_priority; 1756 sched_thread_priority(td, prio); 1757 1758 /* 1759 * If the thread is on a turnstile, then let the turnstile update 1760 * its state. 1761 */ 1762 if (TD_ON_LOCK(td) && oldprio != prio) 1763 turnstile_adjust(td, oldprio); 1764 } 1765 1766 /* 1767 * Set the base user priority, does not effect current running priority. 1768 */ 1769 void 1770 sched_user_prio(struct thread *td, u_char prio) 1771 { 1772 1773 td->td_base_user_pri = prio; 1774 if (td->td_lend_user_pri <= prio) 1775 return; 1776 td->td_user_pri = prio; 1777 } 1778 1779 void 1780 sched_lend_user_prio(struct thread *td, u_char prio) 1781 { 1782 1783 THREAD_LOCK_ASSERT(td, MA_OWNED); 1784 td->td_lend_user_pri = prio; 1785 td->td_user_pri = min(prio, td->td_base_user_pri); 1786 if (td->td_priority > td->td_user_pri) 1787 sched_prio(td, td->td_user_pri); 1788 else if (td->td_priority != td->td_user_pri) 1789 td->td_flags |= TDF_NEEDRESCHED; 1790 } 1791 1792 /* 1793 * Handle migration from sched_switch(). This happens only for 1794 * cpu binding. 1795 */ 1796 static struct mtx * 1797 sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags) 1798 { 1799 struct tdq *tdn; 1800 1801 tdn = TDQ_CPU(td->td_sched->ts_cpu); 1802 #ifdef SMP 1803 tdq_load_rem(tdq, td); 1804 /* 1805 * Do the lock dance required to avoid LOR. We grab an extra 1806 * spinlock nesting to prevent preemption while we're 1807 * not holding either run-queue lock. 1808 */ 1809 spinlock_enter(); 1810 thread_lock_block(td); /* This releases the lock on tdq. */ 1811 1812 /* 1813 * Acquire both run-queue locks before placing the thread on the new 1814 * run-queue to avoid deadlocks created by placing a thread with a 1815 * blocked lock on the run-queue of a remote processor. The deadlock 1816 * occurs when a third processor attempts to lock the two queues in 1817 * question while the target processor is spinning with its own 1818 * run-queue lock held while waiting for the blocked lock to clear. 1819 */ 1820 tdq_lock_pair(tdn, tdq); 1821 tdq_add(tdn, td, flags); 1822 tdq_notify(tdn, td); 1823 TDQ_UNLOCK(tdn); 1824 spinlock_exit(); 1825 #endif 1826 return (TDQ_LOCKPTR(tdn)); 1827 } 1828 1829 /* 1830 * Variadic version of thread_lock_unblock() that does not assume td_lock 1831 * is blocked. 1832 */ 1833 static inline void 1834 thread_unblock_switch(struct thread *td, struct mtx *mtx) 1835 { 1836 atomic_store_rel_ptr((volatile uintptr_t *)&td->td_lock, 1837 (uintptr_t)mtx); 1838 } 1839 1840 /* 1841 * Switch threads. This function has to handle threads coming in while 1842 * blocked for some reason, running, or idle. It also must deal with 1843 * migrating a thread from one queue to another as running threads may 1844 * be assigned elsewhere via binding. 1845 */ 1846 void 1847 sched_switch(struct thread *td, struct thread *newtd, int flags) 1848 { 1849 struct tdq *tdq; 1850 struct td_sched *ts; 1851 struct mtx *mtx; 1852 int srqflag; 1853 int cpuid, preempted; 1854 1855 THREAD_LOCK_ASSERT(td, MA_OWNED); 1856 KASSERT(newtd == NULL, ("sched_switch: Unsupported newtd argument")); 1857 1858 cpuid = PCPU_GET(cpuid); 1859 tdq = TDQ_CPU(cpuid); 1860 ts = td->td_sched; 1861 mtx = td->td_lock; 1862 sched_pctcpu_update(ts, 1); 1863 ts->ts_rltick = ticks; 1864 td->td_lastcpu = td->td_oncpu; 1865 td->td_oncpu = NOCPU; 1866 preempted = !(td->td_flags & TDF_SLICEEND); 1867 td->td_flags &= ~(TDF_NEEDRESCHED | TDF_SLICEEND); 1868 td->td_owepreempt = 0; 1869 if (!TD_IS_IDLETHREAD(td)) 1870 tdq->tdq_switchcnt++; 1871 /* 1872 * The lock pointer in an idle thread should never change. Reset it 1873 * to CAN_RUN as well. 1874 */ 1875 if (TD_IS_IDLETHREAD(td)) { 1876 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1877 TD_SET_CAN_RUN(td); 1878 } else if (TD_IS_RUNNING(td)) { 1879 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1880 srqflag = preempted ? 1881 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 1882 SRQ_OURSELF|SRQ_YIELDING; 1883 #ifdef SMP 1884 if (THREAD_CAN_MIGRATE(td) && !THREAD_CAN_SCHED(td, ts->ts_cpu)) 1885 ts->ts_cpu = sched_pickcpu(td, 0); 1886 #endif 1887 if (ts->ts_cpu == cpuid) 1888 tdq_runq_add(tdq, td, srqflag); 1889 else { 1890 KASSERT(THREAD_CAN_MIGRATE(td) || 1891 (ts->ts_flags & TSF_BOUND) != 0, 1892 ("Thread %p shouldn't migrate", td)); 1893 mtx = sched_switch_migrate(tdq, td, srqflag); 1894 } 1895 } else { 1896 /* This thread must be going to sleep. */ 1897 TDQ_LOCK(tdq); 1898 mtx = thread_lock_block(td); 1899 tdq_load_rem(tdq, td); 1900 } 1901 /* 1902 * We enter here with the thread blocked and assigned to the 1903 * appropriate cpu run-queue or sleep-queue and with the current 1904 * thread-queue locked. 1905 */ 1906 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 1907 newtd = choosethread(); 1908 /* 1909 * Call the MD code to switch contexts if necessary. 1910 */ 1911 if (td != newtd) { 1912 #ifdef HWPMC_HOOKS 1913 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1914 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 1915 #endif 1916 SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc); 1917 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 1918 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 1919 sched_pctcpu_update(newtd->td_sched, 0); 1920 1921 #ifdef KDTRACE_HOOKS 1922 /* 1923 * If DTrace has set the active vtime enum to anything 1924 * other than INACTIVE (0), then it should have set the 1925 * function to call. 1926 */ 1927 if (dtrace_vtime_active) 1928 (*dtrace_vtime_switch_func)(newtd); 1929 #endif 1930 1931 cpu_switch(td, newtd, mtx); 1932 /* 1933 * We may return from cpu_switch on a different cpu. However, 1934 * we always return with td_lock pointing to the current cpu's 1935 * run queue lock. 1936 */ 1937 cpuid = PCPU_GET(cpuid); 1938 tdq = TDQ_CPU(cpuid); 1939 lock_profile_obtain_lock_success( 1940 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 1941 1942 SDT_PROBE0(sched, , , on__cpu); 1943 #ifdef HWPMC_HOOKS 1944 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1945 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 1946 #endif 1947 } else { 1948 thread_unblock_switch(td, mtx); 1949 SDT_PROBE0(sched, , , remain__cpu); 1950 } 1951 /* 1952 * Assert that all went well and return. 1953 */ 1954 TDQ_LOCK_ASSERT(tdq, MA_OWNED|MA_NOTRECURSED); 1955 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1956 td->td_oncpu = cpuid; 1957 } 1958 1959 /* 1960 * Adjust thread priorities as a result of a nice request. 1961 */ 1962 void 1963 sched_nice(struct proc *p, int nice) 1964 { 1965 struct thread *td; 1966 1967 PROC_LOCK_ASSERT(p, MA_OWNED); 1968 1969 p->p_nice = nice; 1970 FOREACH_THREAD_IN_PROC(p, td) { 1971 thread_lock(td); 1972 sched_priority(td); 1973 sched_prio(td, td->td_base_user_pri); 1974 thread_unlock(td); 1975 } 1976 } 1977 1978 /* 1979 * Record the sleep time for the interactivity scorer. 1980 */ 1981 void 1982 sched_sleep(struct thread *td, int prio) 1983 { 1984 1985 THREAD_LOCK_ASSERT(td, MA_OWNED); 1986 1987 td->td_slptick = ticks; 1988 if (TD_IS_SUSPENDED(td) || prio >= PSOCK) 1989 td->td_flags |= TDF_CANSWAP; 1990 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 1991 return; 1992 if (static_boost == 1 && prio) 1993 sched_prio(td, prio); 1994 else if (static_boost && td->td_priority > static_boost) 1995 sched_prio(td, static_boost); 1996 } 1997 1998 /* 1999 * Schedule a thread to resume execution and record how long it voluntarily 2000 * slept. We also update the pctcpu, interactivity, and priority. 2001 */ 2002 void 2003 sched_wakeup(struct thread *td) 2004 { 2005 struct td_sched *ts; 2006 int slptick; 2007 2008 THREAD_LOCK_ASSERT(td, MA_OWNED); 2009 ts = td->td_sched; 2010 td->td_flags &= ~TDF_CANSWAP; 2011 /* 2012 * If we slept for more than a tick update our interactivity and 2013 * priority. 2014 */ 2015 slptick = td->td_slptick; 2016 td->td_slptick = 0; 2017 if (slptick && slptick != ticks) { 2018 ts->ts_slptime += (ticks - slptick) << SCHED_TICK_SHIFT; 2019 sched_interact_update(td); 2020 sched_pctcpu_update(ts, 0); 2021 } 2022 /* 2023 * Reset the slice value since we slept and advanced the round-robin. 2024 */ 2025 ts->ts_slice = 0; 2026 sched_add(td, SRQ_BORING); 2027 } 2028 2029 /* 2030 * Penalize the parent for creating a new child and initialize the child's 2031 * priority. 2032 */ 2033 void 2034 sched_fork(struct thread *td, struct thread *child) 2035 { 2036 THREAD_LOCK_ASSERT(td, MA_OWNED); 2037 sched_pctcpu_update(td->td_sched, 1); 2038 sched_fork_thread(td, child); 2039 /* 2040 * Penalize the parent and child for forking. 2041 */ 2042 sched_interact_fork(child); 2043 sched_priority(child); 2044 td->td_sched->ts_runtime += tickincr; 2045 sched_interact_update(td); 2046 sched_priority(td); 2047 } 2048 2049 /* 2050 * Fork a new thread, may be within the same process. 2051 */ 2052 void 2053 sched_fork_thread(struct thread *td, struct thread *child) 2054 { 2055 struct td_sched *ts; 2056 struct td_sched *ts2; 2057 struct tdq *tdq; 2058 2059 tdq = TDQ_SELF(); 2060 THREAD_LOCK_ASSERT(td, MA_OWNED); 2061 /* 2062 * Initialize child. 2063 */ 2064 ts = td->td_sched; 2065 ts2 = child->td_sched; 2066 child->td_lock = TDQ_LOCKPTR(tdq); 2067 child->td_cpuset = cpuset_ref(td->td_cpuset); 2068 ts2->ts_cpu = ts->ts_cpu; 2069 ts2->ts_flags = 0; 2070 /* 2071 * Grab our parents cpu estimation information. 2072 */ 2073 ts2->ts_ticks = ts->ts_ticks; 2074 ts2->ts_ltick = ts->ts_ltick; 2075 ts2->ts_ftick = ts->ts_ftick; 2076 /* 2077 * Do not inherit any borrowed priority from the parent. 2078 */ 2079 child->td_priority = child->td_base_pri; 2080 /* 2081 * And update interactivity score. 2082 */ 2083 ts2->ts_slptime = ts->ts_slptime; 2084 ts2->ts_runtime = ts->ts_runtime; 2085 /* Attempt to quickly learn interactivity. */ 2086 ts2->ts_slice = tdq_slice(tdq) - sched_slice_min; 2087 #ifdef KTR 2088 bzero(ts2->ts_name, sizeof(ts2->ts_name)); 2089 #endif 2090 } 2091 2092 /* 2093 * Adjust the priority class of a thread. 2094 */ 2095 void 2096 sched_class(struct thread *td, int class) 2097 { 2098 2099 THREAD_LOCK_ASSERT(td, MA_OWNED); 2100 if (td->td_pri_class == class) 2101 return; 2102 td->td_pri_class = class; 2103 } 2104 2105 /* 2106 * Return some of the child's priority and interactivity to the parent. 2107 */ 2108 void 2109 sched_exit(struct proc *p, struct thread *child) 2110 { 2111 struct thread *td; 2112 2113 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "proc exit", 2114 "prio:%d", child->td_priority); 2115 PROC_LOCK_ASSERT(p, MA_OWNED); 2116 td = FIRST_THREAD_IN_PROC(p); 2117 sched_exit_thread(td, child); 2118 } 2119 2120 /* 2121 * Penalize another thread for the time spent on this one. This helps to 2122 * worsen the priority and interactivity of processes which schedule batch 2123 * jobs such as make. This has little effect on the make process itself but 2124 * causes new processes spawned by it to receive worse scores immediately. 2125 */ 2126 void 2127 sched_exit_thread(struct thread *td, struct thread *child) 2128 { 2129 2130 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "thread exit", 2131 "prio:%d", child->td_priority); 2132 /* 2133 * Give the child's runtime to the parent without returning the 2134 * sleep time as a penalty to the parent. This causes shells that 2135 * launch expensive things to mark their children as expensive. 2136 */ 2137 thread_lock(td); 2138 td->td_sched->ts_runtime += child->td_sched->ts_runtime; 2139 sched_interact_update(td); 2140 sched_priority(td); 2141 thread_unlock(td); 2142 } 2143 2144 void 2145 sched_preempt(struct thread *td) 2146 { 2147 struct tdq *tdq; 2148 2149 SDT_PROBE2(sched, , , surrender, td, td->td_proc); 2150 2151 thread_lock(td); 2152 tdq = TDQ_SELF(); 2153 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2154 tdq->tdq_ipipending = 0; 2155 if (td->td_priority > tdq->tdq_lowpri) { 2156 int flags; 2157 2158 flags = SW_INVOL | SW_PREEMPT; 2159 if (td->td_critnest > 1) 2160 td->td_owepreempt = 1; 2161 else if (TD_IS_IDLETHREAD(td)) 2162 mi_switch(flags | SWT_REMOTEWAKEIDLE, NULL); 2163 else 2164 mi_switch(flags | SWT_REMOTEPREEMPT, NULL); 2165 } 2166 thread_unlock(td); 2167 } 2168 2169 /* 2170 * Fix priorities on return to user-space. Priorities may be elevated due 2171 * to static priorities in msleep() or similar. 2172 */ 2173 void 2174 sched_userret(struct thread *td) 2175 { 2176 /* 2177 * XXX we cheat slightly on the locking here to avoid locking in 2178 * the usual case. Setting td_priority here is essentially an 2179 * incomplete workaround for not setting it properly elsewhere. 2180 * Now that some interrupt handlers are threads, not setting it 2181 * properly elsewhere can clobber it in the window between setting 2182 * it here and returning to user mode, so don't waste time setting 2183 * it perfectly here. 2184 */ 2185 KASSERT((td->td_flags & TDF_BORROWING) == 0, 2186 ("thread with borrowed priority returning to userland")); 2187 if (td->td_priority != td->td_user_pri) { 2188 thread_lock(td); 2189 td->td_priority = td->td_user_pri; 2190 td->td_base_pri = td->td_user_pri; 2191 tdq_setlowpri(TDQ_SELF(), td); 2192 thread_unlock(td); 2193 } 2194 } 2195 2196 /* 2197 * Handle a stathz tick. This is really only relevant for timeshare 2198 * threads. 2199 */ 2200 void 2201 sched_clock(struct thread *td) 2202 { 2203 struct tdq *tdq; 2204 struct td_sched *ts; 2205 2206 THREAD_LOCK_ASSERT(td, MA_OWNED); 2207 tdq = TDQ_SELF(); 2208 #ifdef SMP 2209 /* 2210 * We run the long term load balancer infrequently on the first cpu. 2211 */ 2212 if (balance_tdq == tdq) { 2213 if (balance_ticks && --balance_ticks == 0) 2214 sched_balance(); 2215 } 2216 #endif 2217 /* 2218 * Save the old switch count so we have a record of the last ticks 2219 * activity. Initialize the new switch count based on our load. 2220 * If there is some activity seed it to reflect that. 2221 */ 2222 tdq->tdq_oldswitchcnt = tdq->tdq_switchcnt; 2223 tdq->tdq_switchcnt = tdq->tdq_load; 2224 /* 2225 * Advance the insert index once for each tick to ensure that all 2226 * threads get a chance to run. 2227 */ 2228 if (tdq->tdq_idx == tdq->tdq_ridx) { 2229 tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS; 2230 if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx])) 2231 tdq->tdq_ridx = tdq->tdq_idx; 2232 } 2233 ts = td->td_sched; 2234 sched_pctcpu_update(ts, 1); 2235 if (td->td_pri_class & PRI_FIFO_BIT) 2236 return; 2237 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) { 2238 /* 2239 * We used a tick; charge it to the thread so 2240 * that we can compute our interactivity. 2241 */ 2242 td->td_sched->ts_runtime += tickincr; 2243 sched_interact_update(td); 2244 sched_priority(td); 2245 } 2246 2247 /* 2248 * Force a context switch if the current thread has used up a full 2249 * time slice (default is 100ms). 2250 */ 2251 if (!TD_IS_IDLETHREAD(td) && ++ts->ts_slice >= tdq_slice(tdq)) { 2252 ts->ts_slice = 0; 2253 td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND; 2254 } 2255 } 2256 2257 /* 2258 * Called once per hz tick. 2259 */ 2260 void 2261 sched_tick(int cnt) 2262 { 2263 2264 } 2265 2266 /* 2267 * Return whether the current CPU has runnable tasks. Used for in-kernel 2268 * cooperative idle threads. 2269 */ 2270 int 2271 sched_runnable(void) 2272 { 2273 struct tdq *tdq; 2274 int load; 2275 2276 load = 1; 2277 2278 tdq = TDQ_SELF(); 2279 if ((curthread->td_flags & TDF_IDLETD) != 0) { 2280 if (tdq->tdq_load > 0) 2281 goto out; 2282 } else 2283 if (tdq->tdq_load - 1 > 0) 2284 goto out; 2285 load = 0; 2286 out: 2287 return (load); 2288 } 2289 2290 /* 2291 * Choose the highest priority thread to run. The thread is removed from 2292 * the run-queue while running however the load remains. For SMP we set 2293 * the tdq in the global idle bitmask if it idles here. 2294 */ 2295 struct thread * 2296 sched_choose(void) 2297 { 2298 struct thread *td; 2299 struct tdq *tdq; 2300 2301 tdq = TDQ_SELF(); 2302 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2303 td = tdq_choose(tdq); 2304 if (td) { 2305 tdq_runq_rem(tdq, td); 2306 tdq->tdq_lowpri = td->td_priority; 2307 return (td); 2308 } 2309 tdq->tdq_lowpri = PRI_MAX_IDLE; 2310 return (PCPU_GET(idlethread)); 2311 } 2312 2313 /* 2314 * Set owepreempt if necessary. Preemption never happens directly in ULE, 2315 * we always request it once we exit a critical section. 2316 */ 2317 static inline void 2318 sched_setpreempt(struct thread *td) 2319 { 2320 struct thread *ctd; 2321 int cpri; 2322 int pri; 2323 2324 THREAD_LOCK_ASSERT(curthread, MA_OWNED); 2325 2326 ctd = curthread; 2327 pri = td->td_priority; 2328 cpri = ctd->td_priority; 2329 if (pri < cpri) 2330 ctd->td_flags |= TDF_NEEDRESCHED; 2331 if (panicstr != NULL || pri >= cpri || cold || TD_IS_INHIBITED(ctd)) 2332 return; 2333 if (!sched_shouldpreempt(pri, cpri, 0)) 2334 return; 2335 ctd->td_owepreempt = 1; 2336 } 2337 2338 /* 2339 * Add a thread to a thread queue. Select the appropriate runq and add the 2340 * thread to it. This is the internal function called when the tdq is 2341 * predetermined. 2342 */ 2343 void 2344 tdq_add(struct tdq *tdq, struct thread *td, int flags) 2345 { 2346 2347 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2348 KASSERT((td->td_inhibitors == 0), 2349 ("sched_add: trying to run inhibited thread")); 2350 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 2351 ("sched_add: bad thread state")); 2352 KASSERT(td->td_flags & TDF_INMEM, 2353 ("sched_add: thread swapped out")); 2354 2355 if (td->td_priority < tdq->tdq_lowpri) 2356 tdq->tdq_lowpri = td->td_priority; 2357 tdq_runq_add(tdq, td, flags); 2358 tdq_load_add(tdq, td); 2359 } 2360 2361 /* 2362 * Select the target thread queue and add a thread to it. Request 2363 * preemption or IPI a remote processor if required. 2364 */ 2365 void 2366 sched_add(struct thread *td, int flags) 2367 { 2368 struct tdq *tdq; 2369 #ifdef SMP 2370 int cpu; 2371 #endif 2372 2373 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 2374 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 2375 sched_tdname(curthread)); 2376 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 2377 KTR_ATTR_LINKED, sched_tdname(td)); 2378 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 2379 flags & SRQ_PREEMPTED); 2380 THREAD_LOCK_ASSERT(td, MA_OWNED); 2381 /* 2382 * Recalculate the priority before we select the target cpu or 2383 * run-queue. 2384 */ 2385 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 2386 sched_priority(td); 2387 #ifdef SMP 2388 /* 2389 * Pick the destination cpu and if it isn't ours transfer to the 2390 * target cpu. 2391 */ 2392 cpu = sched_pickcpu(td, flags); 2393 tdq = sched_setcpu(td, cpu, flags); 2394 tdq_add(tdq, td, flags); 2395 if (cpu != PCPU_GET(cpuid)) { 2396 tdq_notify(tdq, td); 2397 return; 2398 } 2399 #else 2400 tdq = TDQ_SELF(); 2401 TDQ_LOCK(tdq); 2402 /* 2403 * Now that the thread is moving to the run-queue, set the lock 2404 * to the scheduler's lock. 2405 */ 2406 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 2407 tdq_add(tdq, td, flags); 2408 #endif 2409 if (!(flags & SRQ_YIELDING)) 2410 sched_setpreempt(td); 2411 } 2412 2413 /* 2414 * Remove a thread from a run-queue without running it. This is used 2415 * when we're stealing a thread from a remote queue. Otherwise all threads 2416 * exit by calling sched_exit_thread() and sched_throw() themselves. 2417 */ 2418 void 2419 sched_rem(struct thread *td) 2420 { 2421 struct tdq *tdq; 2422 2423 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "runq rem", 2424 "prio:%d", td->td_priority); 2425 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL); 2426 tdq = TDQ_CPU(td->td_sched->ts_cpu); 2427 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2428 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2429 KASSERT(TD_ON_RUNQ(td), 2430 ("sched_rem: thread not on run queue")); 2431 tdq_runq_rem(tdq, td); 2432 tdq_load_rem(tdq, td); 2433 TD_SET_CAN_RUN(td); 2434 if (td->td_priority == tdq->tdq_lowpri) 2435 tdq_setlowpri(tdq, NULL); 2436 } 2437 2438 /* 2439 * Fetch cpu utilization information. Updates on demand. 2440 */ 2441 fixpt_t 2442 sched_pctcpu(struct thread *td) 2443 { 2444 fixpt_t pctcpu; 2445 struct td_sched *ts; 2446 2447 pctcpu = 0; 2448 ts = td->td_sched; 2449 if (ts == NULL) 2450 return (0); 2451 2452 THREAD_LOCK_ASSERT(td, MA_OWNED); 2453 sched_pctcpu_update(ts, TD_IS_RUNNING(td)); 2454 if (ts->ts_ticks) { 2455 int rtick; 2456 2457 /* How many rtick per second ? */ 2458 rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz); 2459 pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT; 2460 } 2461 2462 return (pctcpu); 2463 } 2464 2465 /* 2466 * Enforce affinity settings for a thread. Called after adjustments to 2467 * cpumask. 2468 */ 2469 void 2470 sched_affinity(struct thread *td) 2471 { 2472 #ifdef SMP 2473 struct td_sched *ts; 2474 2475 THREAD_LOCK_ASSERT(td, MA_OWNED); 2476 ts = td->td_sched; 2477 if (THREAD_CAN_SCHED(td, ts->ts_cpu)) 2478 return; 2479 if (TD_ON_RUNQ(td)) { 2480 sched_rem(td); 2481 sched_add(td, SRQ_BORING); 2482 return; 2483 } 2484 if (!TD_IS_RUNNING(td)) 2485 return; 2486 /* 2487 * Force a switch before returning to userspace. If the 2488 * target thread is not running locally send an ipi to force 2489 * the issue. 2490 */ 2491 td->td_flags |= TDF_NEEDRESCHED; 2492 if (td != curthread) 2493 ipi_cpu(ts->ts_cpu, IPI_PREEMPT); 2494 #endif 2495 } 2496 2497 /* 2498 * Bind a thread to a target cpu. 2499 */ 2500 void 2501 sched_bind(struct thread *td, int cpu) 2502 { 2503 struct td_sched *ts; 2504 2505 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 2506 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 2507 ts = td->td_sched; 2508 if (ts->ts_flags & TSF_BOUND) 2509 sched_unbind(td); 2510 KASSERT(THREAD_CAN_MIGRATE(td), ("%p must be migratable", td)); 2511 ts->ts_flags |= TSF_BOUND; 2512 sched_pin(); 2513 if (PCPU_GET(cpuid) == cpu) 2514 return; 2515 ts->ts_cpu = cpu; 2516 /* When we return from mi_switch we'll be on the correct cpu. */ 2517 mi_switch(SW_VOL, NULL); 2518 } 2519 2520 /* 2521 * Release a bound thread. 2522 */ 2523 void 2524 sched_unbind(struct thread *td) 2525 { 2526 struct td_sched *ts; 2527 2528 THREAD_LOCK_ASSERT(td, MA_OWNED); 2529 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 2530 ts = td->td_sched; 2531 if ((ts->ts_flags & TSF_BOUND) == 0) 2532 return; 2533 ts->ts_flags &= ~TSF_BOUND; 2534 sched_unpin(); 2535 } 2536 2537 int 2538 sched_is_bound(struct thread *td) 2539 { 2540 THREAD_LOCK_ASSERT(td, MA_OWNED); 2541 return (td->td_sched->ts_flags & TSF_BOUND); 2542 } 2543 2544 /* 2545 * Basic yield call. 2546 */ 2547 void 2548 sched_relinquish(struct thread *td) 2549 { 2550 thread_lock(td); 2551 mi_switch(SW_VOL | SWT_RELINQUISH, NULL); 2552 thread_unlock(td); 2553 } 2554 2555 /* 2556 * Return the total system load. 2557 */ 2558 int 2559 sched_load(void) 2560 { 2561 #ifdef SMP 2562 int total; 2563 int i; 2564 2565 total = 0; 2566 CPU_FOREACH(i) 2567 total += TDQ_CPU(i)->tdq_sysload; 2568 return (total); 2569 #else 2570 return (TDQ_SELF()->tdq_sysload); 2571 #endif 2572 } 2573 2574 int 2575 sched_sizeof_proc(void) 2576 { 2577 return (sizeof(struct proc)); 2578 } 2579 2580 int 2581 sched_sizeof_thread(void) 2582 { 2583 return (sizeof(struct thread) + sizeof(struct td_sched)); 2584 } 2585 2586 #ifdef SMP 2587 #define TDQ_IDLESPIN(tdq) \ 2588 ((tdq)->tdq_cg != NULL && ((tdq)->tdq_cg->cg_flags & CG_FLAG_THREAD) == 0) 2589 #else 2590 #define TDQ_IDLESPIN(tdq) 1 2591 #endif 2592 2593 /* 2594 * The actual idle process. 2595 */ 2596 void 2597 sched_idletd(void *dummy) 2598 { 2599 struct thread *td; 2600 struct tdq *tdq; 2601 int oldswitchcnt, switchcnt; 2602 int i; 2603 2604 mtx_assert(&Giant, MA_NOTOWNED); 2605 td = curthread; 2606 tdq = TDQ_SELF(); 2607 THREAD_NO_SLEEPING(); 2608 oldswitchcnt = -1; 2609 for (;;) { 2610 if (tdq->tdq_load) { 2611 thread_lock(td); 2612 mi_switch(SW_VOL | SWT_IDLE, NULL); 2613 thread_unlock(td); 2614 } 2615 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2616 #ifdef SMP 2617 if (switchcnt != oldswitchcnt) { 2618 oldswitchcnt = switchcnt; 2619 if (tdq_idled(tdq) == 0) 2620 continue; 2621 } 2622 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2623 #else 2624 oldswitchcnt = switchcnt; 2625 #endif 2626 /* 2627 * If we're switching very frequently, spin while checking 2628 * for load rather than entering a low power state that 2629 * may require an IPI. However, don't do any busy 2630 * loops while on SMT machines as this simply steals 2631 * cycles from cores doing useful work. 2632 */ 2633 if (TDQ_IDLESPIN(tdq) && switchcnt > sched_idlespinthresh) { 2634 for (i = 0; i < sched_idlespins; i++) { 2635 if (tdq->tdq_load) 2636 break; 2637 cpu_spinwait(); 2638 } 2639 } 2640 2641 /* If there was context switch during spin, restart it. */ 2642 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2643 if (tdq->tdq_load != 0 || switchcnt != oldswitchcnt) 2644 continue; 2645 2646 /* Run main MD idle handler. */ 2647 tdq->tdq_cpu_idle = 1; 2648 cpu_idle(switchcnt * 4 > sched_idlespinthresh); 2649 tdq->tdq_cpu_idle = 0; 2650 2651 /* 2652 * Account thread-less hardware interrupts and 2653 * other wakeup reasons equal to context switches. 2654 */ 2655 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2656 if (switchcnt != oldswitchcnt) 2657 continue; 2658 tdq->tdq_switchcnt++; 2659 oldswitchcnt++; 2660 } 2661 } 2662 2663 /* 2664 * A CPU is entering for the first time or a thread is exiting. 2665 */ 2666 void 2667 sched_throw(struct thread *td) 2668 { 2669 struct thread *newtd; 2670 struct tdq *tdq; 2671 2672 tdq = TDQ_SELF(); 2673 if (td == NULL) { 2674 /* Correct spinlock nesting and acquire the correct lock. */ 2675 TDQ_LOCK(tdq); 2676 spinlock_exit(); 2677 PCPU_SET(switchtime, cpu_ticks()); 2678 PCPU_SET(switchticks, ticks); 2679 } else { 2680 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2681 tdq_load_rem(tdq, td); 2682 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 2683 } 2684 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 2685 newtd = choosethread(); 2686 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 2687 cpu_throw(td, newtd); /* doesn't return */ 2688 } 2689 2690 /* 2691 * This is called from fork_exit(). Just acquire the correct locks and 2692 * let fork do the rest of the work. 2693 */ 2694 void 2695 sched_fork_exit(struct thread *td) 2696 { 2697 struct td_sched *ts; 2698 struct tdq *tdq; 2699 int cpuid; 2700 2701 /* 2702 * Finish setting up thread glue so that it begins execution in a 2703 * non-nested critical section with the scheduler lock held. 2704 */ 2705 cpuid = PCPU_GET(cpuid); 2706 tdq = TDQ_CPU(cpuid); 2707 ts = td->td_sched; 2708 if (TD_IS_IDLETHREAD(td)) 2709 td->td_lock = TDQ_LOCKPTR(tdq); 2710 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2711 td->td_oncpu = cpuid; 2712 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 2713 lock_profile_obtain_lock_success( 2714 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 2715 } 2716 2717 /* 2718 * Create on first use to catch odd startup conditons. 2719 */ 2720 char * 2721 sched_tdname(struct thread *td) 2722 { 2723 #ifdef KTR 2724 struct td_sched *ts; 2725 2726 ts = td->td_sched; 2727 if (ts->ts_name[0] == '\0') 2728 snprintf(ts->ts_name, sizeof(ts->ts_name), 2729 "%s tid %d", td->td_name, td->td_tid); 2730 return (ts->ts_name); 2731 #else 2732 return (td->td_name); 2733 #endif 2734 } 2735 2736 #ifdef KTR 2737 void 2738 sched_clear_tdname(struct thread *td) 2739 { 2740 struct td_sched *ts; 2741 2742 ts = td->td_sched; 2743 ts->ts_name[0] = '\0'; 2744 } 2745 #endif 2746 2747 #ifdef SMP 2748 2749 /* 2750 * Build the CPU topology dump string. Is recursively called to collect 2751 * the topology tree. 2752 */ 2753 static int 2754 sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, struct cpu_group *cg, 2755 int indent) 2756 { 2757 char cpusetbuf[CPUSETBUFSIZ]; 2758 int i, first; 2759 2760 sbuf_printf(sb, "%*s<group level=\"%d\" cache-level=\"%d\">\n", indent, 2761 "", 1 + indent / 2, cg->cg_level); 2762 sbuf_printf(sb, "%*s <cpu count=\"%d\" mask=\"%s\">", indent, "", 2763 cg->cg_count, cpusetobj_strprint(cpusetbuf, &cg->cg_mask)); 2764 first = TRUE; 2765 for (i = 0; i < MAXCPU; i++) { 2766 if (CPU_ISSET(i, &cg->cg_mask)) { 2767 if (!first) 2768 sbuf_printf(sb, ", "); 2769 else 2770 first = FALSE; 2771 sbuf_printf(sb, "%d", i); 2772 } 2773 } 2774 sbuf_printf(sb, "</cpu>\n"); 2775 2776 if (cg->cg_flags != 0) { 2777 sbuf_printf(sb, "%*s <flags>", indent, ""); 2778 if ((cg->cg_flags & CG_FLAG_HTT) != 0) 2779 sbuf_printf(sb, "<flag name=\"HTT\">HTT group</flag>"); 2780 if ((cg->cg_flags & CG_FLAG_THREAD) != 0) 2781 sbuf_printf(sb, "<flag name=\"THREAD\">THREAD group</flag>"); 2782 if ((cg->cg_flags & CG_FLAG_SMT) != 0) 2783 sbuf_printf(sb, "<flag name=\"SMT\">SMT group</flag>"); 2784 sbuf_printf(sb, "</flags>\n"); 2785 } 2786 2787 if (cg->cg_children > 0) { 2788 sbuf_printf(sb, "%*s <children>\n", indent, ""); 2789 for (i = 0; i < cg->cg_children; i++) 2790 sysctl_kern_sched_topology_spec_internal(sb, 2791 &cg->cg_child[i], indent+2); 2792 sbuf_printf(sb, "%*s </children>\n", indent, ""); 2793 } 2794 sbuf_printf(sb, "%*s</group>\n", indent, ""); 2795 return (0); 2796 } 2797 2798 /* 2799 * Sysctl handler for retrieving topology dump. It's a wrapper for 2800 * the recursive sysctl_kern_smp_topology_spec_internal(). 2801 */ 2802 static int 2803 sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS) 2804 { 2805 struct sbuf *topo; 2806 int err; 2807 2808 KASSERT(cpu_top != NULL, ("cpu_top isn't initialized")); 2809 2810 topo = sbuf_new(NULL, NULL, 500, SBUF_AUTOEXTEND); 2811 if (topo == NULL) 2812 return (ENOMEM); 2813 2814 sbuf_printf(topo, "<groups>\n"); 2815 err = sysctl_kern_sched_topology_spec_internal(topo, cpu_top, 1); 2816 sbuf_printf(topo, "</groups>\n"); 2817 2818 if (err == 0) { 2819 sbuf_finish(topo); 2820 err = SYSCTL_OUT(req, sbuf_data(topo), sbuf_len(topo)); 2821 } 2822 sbuf_delete(topo); 2823 return (err); 2824 } 2825 2826 #endif 2827 2828 static int 2829 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 2830 { 2831 int error, new_val, period; 2832 2833 period = 1000000 / realstathz; 2834 new_val = period * sched_slice; 2835 error = sysctl_handle_int(oidp, &new_val, 0, req); 2836 if (error != 0 || req->newptr == NULL) 2837 return (error); 2838 if (new_val <= 0) 2839 return (EINVAL); 2840 sched_slice = imax(1, (new_val + period / 2) / period); 2841 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 2842 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 2843 realstathz); 2844 return (0); 2845 } 2846 2847 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0, "Scheduler"); 2848 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0, 2849 "Scheduler name"); 2850 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW, 2851 NULL, 0, sysctl_kern_quantum, "I", 2852 "Quantum for timeshare threads in microseconds"); 2853 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, 2854 "Quantum for timeshare threads in stathz ticks"); 2855 SYSCTL_INT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0, 2856 "Interactivity score threshold"); 2857 SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW, 2858 &preempt_thresh, 0, 2859 "Maximal (lowest) priority for preemption"); 2860 SYSCTL_INT(_kern_sched, OID_AUTO, static_boost, CTLFLAG_RW, &static_boost, 0, 2861 "Assign static kernel priorities to sleeping threads"); 2862 SYSCTL_INT(_kern_sched, OID_AUTO, idlespins, CTLFLAG_RW, &sched_idlespins, 0, 2863 "Number of times idle thread will spin waiting for new work"); 2864 SYSCTL_INT(_kern_sched, OID_AUTO, idlespinthresh, CTLFLAG_RW, 2865 &sched_idlespinthresh, 0, 2866 "Threshold before we will permit idle thread spinning"); 2867 #ifdef SMP 2868 SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0, 2869 "Number of hz ticks to keep thread affinity for"); 2870 SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0, 2871 "Enables the long-term load balancer"); 2872 SYSCTL_INT(_kern_sched, OID_AUTO, balance_interval, CTLFLAG_RW, 2873 &balance_interval, 0, 2874 "Average period in stathz ticks to run the long-term balancer"); 2875 SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0, 2876 "Attempts to steal work from other cores before idling"); 2877 SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0, 2878 "Minimum load on remote CPU before we'll steal"); 2879 SYSCTL_PROC(_kern_sched, OID_AUTO, topology_spec, CTLTYPE_STRING | 2880 CTLFLAG_RD, NULL, 0, sysctl_kern_sched_topology_spec, "A", 2881 "XML dump of detected CPU topology"); 2882 #endif 2883 2884 /* ps compat. All cpu percentages from ULE are weighted. */ 2885 static int ccpu = 0; 2886 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 2887