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, change-pri, "struct thread *", 347 "struct proc *", "uint8_t"); 348 SDT_PROBE_DEFINE3(sched, , , dequeue, dequeue, "struct thread *", 349 "struct proc *", "void *"); 350 SDT_PROBE_DEFINE4(sched, , , enqueue, enqueue, "struct thread *", 351 "struct proc *", "void *", "int"); 352 SDT_PROBE_DEFINE4(sched, , , lend_pri, lend-pri, "struct thread *", 353 "struct proc *", "uint8_t", "struct thread *"); 354 SDT_PROBE_DEFINE2(sched, , , load_change, load-change, "int", "int"); 355 SDT_PROBE_DEFINE2(sched, , , off_cpu, off-cpu, "struct thread *", 356 "struct proc *"); 357 SDT_PROBE_DEFINE(sched, , , on_cpu, on-cpu); 358 SDT_PROBE_DEFINE(sched, , , remain_cpu, remain-cpu); 359 SDT_PROBE_DEFINE2(sched, , , surrender, 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 /* 817 * Simultaneously find the highest and lowest loaded cpu reachable via 818 * cg. 819 */ 820 static inline void 821 sched_both(const struct cpu_group *cg, cpuset_t mask, int *lowcpu, int *highcpu) 822 { 823 struct cpu_search high; 824 struct cpu_search low; 825 826 low.cs_cpu = -1; 827 low.cs_prefer = -1; 828 low.cs_pri = -1; 829 low.cs_limit = INT_MAX; 830 low.cs_mask = mask; 831 high.cs_cpu = -1; 832 high.cs_limit = -1; 833 high.cs_mask = mask; 834 cpu_search_both(cg, &low, &high); 835 *lowcpu = low.cs_cpu; 836 *highcpu = high.cs_cpu; 837 return; 838 } 839 840 static void 841 sched_balance_group(struct cpu_group *cg) 842 { 843 cpuset_t hmask, lmask; 844 int high, low, anylow; 845 846 CPU_FILL(&hmask); 847 for (;;) { 848 high = sched_highest(cg, hmask, 1); 849 /* Stop if there is no more CPU with transferrable threads. */ 850 if (high == -1) 851 break; 852 CPU_CLR(high, &hmask); 853 CPU_COPY(&hmask, &lmask); 854 /* Stop if there is no more CPU left for low. */ 855 if (CPU_EMPTY(&lmask)) 856 break; 857 anylow = 1; 858 nextlow: 859 low = sched_lowest(cg, lmask, -1, 860 TDQ_CPU(high)->tdq_load - 1, high); 861 /* Stop if we looked well and found no less loaded CPU. */ 862 if (anylow && low == -1) 863 break; 864 /* Go to next high if we found no less loaded CPU. */ 865 if (low == -1) 866 continue; 867 /* Transfer thread from high to low. */ 868 if (sched_balance_pair(TDQ_CPU(high), TDQ_CPU(low))) { 869 /* CPU that got thread can no longer be a donor. */ 870 CPU_CLR(low, &hmask); 871 } else { 872 /* 873 * If failed, then there is no threads on high 874 * that can run on this low. Drop low from low 875 * mask and look for different one. 876 */ 877 CPU_CLR(low, &lmask); 878 anylow = 0; 879 goto nextlow; 880 } 881 } 882 } 883 884 static void 885 sched_balance(void) 886 { 887 struct tdq *tdq; 888 889 /* 890 * Select a random time between .5 * balance_interval and 891 * 1.5 * balance_interval. 892 */ 893 balance_ticks = max(balance_interval / 2, 1); 894 balance_ticks += random() % balance_interval; 895 if (smp_started == 0 || rebalance == 0) 896 return; 897 tdq = TDQ_SELF(); 898 TDQ_UNLOCK(tdq); 899 sched_balance_group(cpu_top); 900 TDQ_LOCK(tdq); 901 } 902 903 /* 904 * Lock two thread queues using their address to maintain lock order. 905 */ 906 static void 907 tdq_lock_pair(struct tdq *one, struct tdq *two) 908 { 909 if (one < two) { 910 TDQ_LOCK(one); 911 TDQ_LOCK_FLAGS(two, MTX_DUPOK); 912 } else { 913 TDQ_LOCK(two); 914 TDQ_LOCK_FLAGS(one, MTX_DUPOK); 915 } 916 } 917 918 /* 919 * Unlock two thread queues. Order is not important here. 920 */ 921 static void 922 tdq_unlock_pair(struct tdq *one, struct tdq *two) 923 { 924 TDQ_UNLOCK(one); 925 TDQ_UNLOCK(two); 926 } 927 928 /* 929 * Transfer load between two imbalanced thread queues. 930 */ 931 static int 932 sched_balance_pair(struct tdq *high, struct tdq *low) 933 { 934 int moved; 935 int cpu; 936 937 tdq_lock_pair(high, low); 938 moved = 0; 939 /* 940 * Determine what the imbalance is and then adjust that to how many 941 * threads we actually have to give up (transferable). 942 */ 943 if (high->tdq_transferable != 0 && high->tdq_load > low->tdq_load && 944 (moved = tdq_move(high, low)) > 0) { 945 /* 946 * In case the target isn't the current cpu IPI it to force a 947 * reschedule with the new workload. 948 */ 949 cpu = TDQ_ID(low); 950 if (cpu != PCPU_GET(cpuid)) 951 ipi_cpu(cpu, IPI_PREEMPT); 952 } 953 tdq_unlock_pair(high, low); 954 return (moved); 955 } 956 957 /* 958 * Move a thread from one thread queue to another. 959 */ 960 static int 961 tdq_move(struct tdq *from, struct tdq *to) 962 { 963 struct td_sched *ts; 964 struct thread *td; 965 struct tdq *tdq; 966 int cpu; 967 968 TDQ_LOCK_ASSERT(from, MA_OWNED); 969 TDQ_LOCK_ASSERT(to, MA_OWNED); 970 971 tdq = from; 972 cpu = TDQ_ID(to); 973 td = tdq_steal(tdq, cpu); 974 if (td == NULL) 975 return (0); 976 ts = td->td_sched; 977 /* 978 * Although the run queue is locked the thread may be blocked. Lock 979 * it to clear this and acquire the run-queue lock. 980 */ 981 thread_lock(td); 982 /* Drop recursive lock on from acquired via thread_lock(). */ 983 TDQ_UNLOCK(from); 984 sched_rem(td); 985 ts->ts_cpu = cpu; 986 td->td_lock = TDQ_LOCKPTR(to); 987 tdq_add(to, td, SRQ_YIELDING); 988 return (1); 989 } 990 991 /* 992 * This tdq has idled. Try to steal a thread from another cpu and switch 993 * to it. 994 */ 995 static int 996 tdq_idled(struct tdq *tdq) 997 { 998 struct cpu_group *cg; 999 struct tdq *steal; 1000 cpuset_t mask; 1001 int thresh; 1002 int cpu; 1003 1004 if (smp_started == 0 || steal_idle == 0) 1005 return (1); 1006 CPU_FILL(&mask); 1007 CPU_CLR(PCPU_GET(cpuid), &mask); 1008 /* We don't want to be preempted while we're iterating. */ 1009 spinlock_enter(); 1010 for (cg = tdq->tdq_cg; cg != NULL; ) { 1011 if ((cg->cg_flags & CG_FLAG_THREAD) == 0) 1012 thresh = steal_thresh; 1013 else 1014 thresh = 1; 1015 cpu = sched_highest(cg, mask, thresh); 1016 if (cpu == -1) { 1017 cg = cg->cg_parent; 1018 continue; 1019 } 1020 steal = TDQ_CPU(cpu); 1021 CPU_CLR(cpu, &mask); 1022 tdq_lock_pair(tdq, steal); 1023 if (steal->tdq_load < thresh || steal->tdq_transferable == 0) { 1024 tdq_unlock_pair(tdq, steal); 1025 continue; 1026 } 1027 /* 1028 * If a thread was added while interrupts were disabled don't 1029 * steal one here. If we fail to acquire one due to affinity 1030 * restrictions loop again with this cpu removed from the 1031 * set. 1032 */ 1033 if (tdq->tdq_load == 0 && tdq_move(steal, tdq) == 0) { 1034 tdq_unlock_pair(tdq, steal); 1035 continue; 1036 } 1037 spinlock_exit(); 1038 TDQ_UNLOCK(steal); 1039 mi_switch(SW_VOL | SWT_IDLE, NULL); 1040 thread_unlock(curthread); 1041 1042 return (0); 1043 } 1044 spinlock_exit(); 1045 return (1); 1046 } 1047 1048 /* 1049 * Notify a remote cpu of new work. Sends an IPI if criteria are met. 1050 */ 1051 static void 1052 tdq_notify(struct tdq *tdq, struct thread *td) 1053 { 1054 struct thread *ctd; 1055 int pri; 1056 int cpu; 1057 1058 if (tdq->tdq_ipipending) 1059 return; 1060 cpu = td->td_sched->ts_cpu; 1061 pri = td->td_priority; 1062 ctd = pcpu_find(cpu)->pc_curthread; 1063 if (!sched_shouldpreempt(pri, ctd->td_priority, 1)) 1064 return; 1065 if (TD_IS_IDLETHREAD(ctd)) { 1066 /* 1067 * If the MD code has an idle wakeup routine try that before 1068 * falling back to IPI. 1069 */ 1070 if (!tdq->tdq_cpu_idle || cpu_idle_wakeup(cpu)) 1071 return; 1072 } 1073 tdq->tdq_ipipending = 1; 1074 ipi_cpu(cpu, IPI_PREEMPT); 1075 } 1076 1077 /* 1078 * Steals load from a timeshare queue. Honors the rotating queue head 1079 * index. 1080 */ 1081 static struct thread * 1082 runq_steal_from(struct runq *rq, int cpu, u_char start) 1083 { 1084 struct rqbits *rqb; 1085 struct rqhead *rqh; 1086 struct thread *td, *first; 1087 int bit; 1088 int pri; 1089 int i; 1090 1091 rqb = &rq->rq_status; 1092 bit = start & (RQB_BPW -1); 1093 pri = 0; 1094 first = NULL; 1095 again: 1096 for (i = RQB_WORD(start); i < RQB_LEN; bit = 0, i++) { 1097 if (rqb->rqb_bits[i] == 0) 1098 continue; 1099 if (bit != 0) { 1100 for (pri = bit; pri < RQB_BPW; pri++) 1101 if (rqb->rqb_bits[i] & (1ul << pri)) 1102 break; 1103 if (pri >= RQB_BPW) 1104 continue; 1105 } else 1106 pri = RQB_FFS(rqb->rqb_bits[i]); 1107 pri += (i << RQB_L2BPW); 1108 rqh = &rq->rq_queues[pri]; 1109 TAILQ_FOREACH(td, rqh, td_runq) { 1110 if (first && THREAD_CAN_MIGRATE(td) && 1111 THREAD_CAN_SCHED(td, cpu)) 1112 return (td); 1113 first = td; 1114 } 1115 } 1116 if (start != 0) { 1117 start = 0; 1118 goto again; 1119 } 1120 1121 if (first && THREAD_CAN_MIGRATE(first) && 1122 THREAD_CAN_SCHED(first, cpu)) 1123 return (first); 1124 return (NULL); 1125 } 1126 1127 /* 1128 * Steals load from a standard linear queue. 1129 */ 1130 static struct thread * 1131 runq_steal(struct runq *rq, int cpu) 1132 { 1133 struct rqhead *rqh; 1134 struct rqbits *rqb; 1135 struct thread *td; 1136 int word; 1137 int bit; 1138 1139 rqb = &rq->rq_status; 1140 for (word = 0; word < RQB_LEN; word++) { 1141 if (rqb->rqb_bits[word] == 0) 1142 continue; 1143 for (bit = 0; bit < RQB_BPW; bit++) { 1144 if ((rqb->rqb_bits[word] & (1ul << bit)) == 0) 1145 continue; 1146 rqh = &rq->rq_queues[bit + (word << RQB_L2BPW)]; 1147 TAILQ_FOREACH(td, rqh, td_runq) 1148 if (THREAD_CAN_MIGRATE(td) && 1149 THREAD_CAN_SCHED(td, cpu)) 1150 return (td); 1151 } 1152 } 1153 return (NULL); 1154 } 1155 1156 /* 1157 * Attempt to steal a thread in priority order from a thread queue. 1158 */ 1159 static struct thread * 1160 tdq_steal(struct tdq *tdq, int cpu) 1161 { 1162 struct thread *td; 1163 1164 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1165 if ((td = runq_steal(&tdq->tdq_realtime, cpu)) != NULL) 1166 return (td); 1167 if ((td = runq_steal_from(&tdq->tdq_timeshare, 1168 cpu, tdq->tdq_ridx)) != NULL) 1169 return (td); 1170 return (runq_steal(&tdq->tdq_idle, cpu)); 1171 } 1172 1173 /* 1174 * Sets the thread lock and ts_cpu to match the requested cpu. Unlocks the 1175 * current lock and returns with the assigned queue locked. 1176 */ 1177 static inline struct tdq * 1178 sched_setcpu(struct thread *td, int cpu, int flags) 1179 { 1180 1181 struct tdq *tdq; 1182 1183 THREAD_LOCK_ASSERT(td, MA_OWNED); 1184 tdq = TDQ_CPU(cpu); 1185 td->td_sched->ts_cpu = cpu; 1186 /* 1187 * If the lock matches just return the queue. 1188 */ 1189 if (td->td_lock == TDQ_LOCKPTR(tdq)) 1190 return (tdq); 1191 #ifdef notyet 1192 /* 1193 * If the thread isn't running its lockptr is a 1194 * turnstile or a sleepqueue. We can just lock_set without 1195 * blocking. 1196 */ 1197 if (TD_CAN_RUN(td)) { 1198 TDQ_LOCK(tdq); 1199 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 1200 return (tdq); 1201 } 1202 #endif 1203 /* 1204 * The hard case, migration, we need to block the thread first to 1205 * prevent order reversals with other cpus locks. 1206 */ 1207 spinlock_enter(); 1208 thread_lock_block(td); 1209 TDQ_LOCK(tdq); 1210 thread_lock_unblock(td, TDQ_LOCKPTR(tdq)); 1211 spinlock_exit(); 1212 return (tdq); 1213 } 1214 1215 SCHED_STAT_DEFINE(pickcpu_intrbind, "Soft interrupt binding"); 1216 SCHED_STAT_DEFINE(pickcpu_idle_affinity, "Picked idle cpu based on affinity"); 1217 SCHED_STAT_DEFINE(pickcpu_affinity, "Picked cpu based on affinity"); 1218 SCHED_STAT_DEFINE(pickcpu_lowest, "Selected lowest load"); 1219 SCHED_STAT_DEFINE(pickcpu_local, "Migrated to current cpu"); 1220 SCHED_STAT_DEFINE(pickcpu_migration, "Selection may have caused migration"); 1221 1222 static int 1223 sched_pickcpu(struct thread *td, int flags) 1224 { 1225 struct cpu_group *cg, *ccg; 1226 struct td_sched *ts; 1227 struct tdq *tdq; 1228 cpuset_t mask; 1229 int cpu, pri, self; 1230 1231 self = PCPU_GET(cpuid); 1232 ts = td->td_sched; 1233 if (smp_started == 0) 1234 return (self); 1235 /* 1236 * Don't migrate a running thread from sched_switch(). 1237 */ 1238 if ((flags & SRQ_OURSELF) || !THREAD_CAN_MIGRATE(td)) 1239 return (ts->ts_cpu); 1240 /* 1241 * Prefer to run interrupt threads on the processors that generate 1242 * the interrupt. 1243 */ 1244 pri = td->td_priority; 1245 if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_SCHED(td, self) && 1246 curthread->td_intr_nesting_level && ts->ts_cpu != self) { 1247 SCHED_STAT_INC(pickcpu_intrbind); 1248 ts->ts_cpu = self; 1249 if (TDQ_CPU(self)->tdq_lowpri > pri) { 1250 SCHED_STAT_INC(pickcpu_affinity); 1251 return (ts->ts_cpu); 1252 } 1253 } 1254 /* 1255 * If the thread can run on the last cpu and the affinity has not 1256 * expired or it is idle run it there. 1257 */ 1258 tdq = TDQ_CPU(ts->ts_cpu); 1259 cg = tdq->tdq_cg; 1260 if (THREAD_CAN_SCHED(td, ts->ts_cpu) && 1261 tdq->tdq_lowpri >= PRI_MIN_IDLE && 1262 SCHED_AFFINITY(ts, CG_SHARE_L2)) { 1263 if (cg->cg_flags & CG_FLAG_THREAD) { 1264 CPUSET_FOREACH(cpu, cg->cg_mask) { 1265 if (TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE) 1266 break; 1267 } 1268 } else 1269 cpu = INT_MAX; 1270 if (cpu > mp_maxid) { 1271 SCHED_STAT_INC(pickcpu_idle_affinity); 1272 return (ts->ts_cpu); 1273 } 1274 } 1275 /* 1276 * Search for the last level cache CPU group in the tree. 1277 * Skip caches with expired affinity time and SMT groups. 1278 * Affinity to higher level caches will be handled less aggressively. 1279 */ 1280 for (ccg = NULL; cg != NULL; cg = cg->cg_parent) { 1281 if (cg->cg_flags & CG_FLAG_THREAD) 1282 continue; 1283 if (!SCHED_AFFINITY(ts, cg->cg_level)) 1284 continue; 1285 ccg = cg; 1286 } 1287 if (ccg != NULL) 1288 cg = ccg; 1289 cpu = -1; 1290 /* Search the group for the less loaded idle CPU we can run now. */ 1291 mask = td->td_cpuset->cs_mask; 1292 if (cg != NULL && cg != cpu_top && 1293 CPU_CMP(&cg->cg_mask, &cpu_top->cg_mask) != 0) 1294 cpu = sched_lowest(cg, mask, max(pri, PRI_MAX_TIMESHARE), 1295 INT_MAX, ts->ts_cpu); 1296 /* Search globally for the less loaded CPU we can run now. */ 1297 if (cpu == -1) 1298 cpu = sched_lowest(cpu_top, mask, pri, INT_MAX, ts->ts_cpu); 1299 /* Search globally for the less loaded CPU. */ 1300 if (cpu == -1) 1301 cpu = sched_lowest(cpu_top, mask, -1, INT_MAX, ts->ts_cpu); 1302 KASSERT(cpu != -1, ("sched_pickcpu: Failed to find a cpu.")); 1303 /* 1304 * Compare the lowest loaded cpu to current cpu. 1305 */ 1306 if (THREAD_CAN_SCHED(td, self) && TDQ_CPU(self)->tdq_lowpri > pri && 1307 TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE && 1308 TDQ_CPU(self)->tdq_load <= TDQ_CPU(cpu)->tdq_load + 1) { 1309 SCHED_STAT_INC(pickcpu_local); 1310 cpu = self; 1311 } else 1312 SCHED_STAT_INC(pickcpu_lowest); 1313 if (cpu != ts->ts_cpu) 1314 SCHED_STAT_INC(pickcpu_migration); 1315 return (cpu); 1316 } 1317 #endif 1318 1319 /* 1320 * Pick the highest priority task we have and return it. 1321 */ 1322 static struct thread * 1323 tdq_choose(struct tdq *tdq) 1324 { 1325 struct thread *td; 1326 1327 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1328 td = runq_choose(&tdq->tdq_realtime); 1329 if (td != NULL) 1330 return (td); 1331 td = runq_choose_from(&tdq->tdq_timeshare, tdq->tdq_ridx); 1332 if (td != NULL) { 1333 KASSERT(td->td_priority >= PRI_MIN_BATCH, 1334 ("tdq_choose: Invalid priority on timeshare queue %d", 1335 td->td_priority)); 1336 return (td); 1337 } 1338 td = runq_choose(&tdq->tdq_idle); 1339 if (td != NULL) { 1340 KASSERT(td->td_priority >= PRI_MIN_IDLE, 1341 ("tdq_choose: Invalid priority on idle queue %d", 1342 td->td_priority)); 1343 return (td); 1344 } 1345 1346 return (NULL); 1347 } 1348 1349 /* 1350 * Initialize a thread queue. 1351 */ 1352 static void 1353 tdq_setup(struct tdq *tdq) 1354 { 1355 1356 if (bootverbose) 1357 printf("ULE: setup cpu %d\n", TDQ_ID(tdq)); 1358 runq_init(&tdq->tdq_realtime); 1359 runq_init(&tdq->tdq_timeshare); 1360 runq_init(&tdq->tdq_idle); 1361 snprintf(tdq->tdq_name, sizeof(tdq->tdq_name), 1362 "sched lock %d", (int)TDQ_ID(tdq)); 1363 mtx_init(&tdq->tdq_lock, tdq->tdq_name, "sched lock", 1364 MTX_SPIN | MTX_RECURSE); 1365 #ifdef KTR 1366 snprintf(tdq->tdq_loadname, sizeof(tdq->tdq_loadname), 1367 "CPU %d load", (int)TDQ_ID(tdq)); 1368 #endif 1369 } 1370 1371 #ifdef SMP 1372 static void 1373 sched_setup_smp(void) 1374 { 1375 struct tdq *tdq; 1376 int i; 1377 1378 cpu_top = smp_topo(); 1379 CPU_FOREACH(i) { 1380 tdq = TDQ_CPU(i); 1381 tdq_setup(tdq); 1382 tdq->tdq_cg = smp_topo_find(cpu_top, i); 1383 if (tdq->tdq_cg == NULL) 1384 panic("Can't find cpu group for %d\n", i); 1385 } 1386 balance_tdq = TDQ_SELF(); 1387 sched_balance(); 1388 } 1389 #endif 1390 1391 /* 1392 * Setup the thread queues and initialize the topology based on MD 1393 * information. 1394 */ 1395 static void 1396 sched_setup(void *dummy) 1397 { 1398 struct tdq *tdq; 1399 1400 tdq = TDQ_SELF(); 1401 #ifdef SMP 1402 sched_setup_smp(); 1403 #else 1404 tdq_setup(tdq); 1405 #endif 1406 1407 /* Add thread0's load since it's running. */ 1408 TDQ_LOCK(tdq); 1409 thread0.td_lock = TDQ_LOCKPTR(TDQ_SELF()); 1410 tdq_load_add(tdq, &thread0); 1411 tdq->tdq_lowpri = thread0.td_priority; 1412 TDQ_UNLOCK(tdq); 1413 } 1414 1415 /* 1416 * This routine determines time constants after stathz and hz are setup. 1417 */ 1418 /* ARGSUSED */ 1419 static void 1420 sched_initticks(void *dummy) 1421 { 1422 int incr; 1423 1424 realstathz = stathz ? stathz : hz; 1425 sched_slice = realstathz / SCHED_SLICE_DEFAULT_DIVISOR; 1426 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 1427 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 1428 realstathz); 1429 1430 /* 1431 * tickincr is shifted out by 10 to avoid rounding errors due to 1432 * hz not being evenly divisible by stathz on all platforms. 1433 */ 1434 incr = (hz << SCHED_TICK_SHIFT) / realstathz; 1435 /* 1436 * This does not work for values of stathz that are more than 1437 * 1 << SCHED_TICK_SHIFT * hz. In practice this does not happen. 1438 */ 1439 if (incr == 0) 1440 incr = 1; 1441 tickincr = incr; 1442 #ifdef SMP 1443 /* 1444 * Set the default balance interval now that we know 1445 * what realstathz is. 1446 */ 1447 balance_interval = realstathz; 1448 affinity = SCHED_AFFINITY_DEFAULT; 1449 #endif 1450 if (sched_idlespinthresh < 0) 1451 sched_idlespinthresh = 2 * max(10000, 6 * hz) / realstathz; 1452 } 1453 1454 1455 /* 1456 * This is the core of the interactivity algorithm. Determines a score based 1457 * on past behavior. It is the ratio of sleep time to run time scaled to 1458 * a [0, 100] integer. This is the voluntary sleep time of a process, which 1459 * differs from the cpu usage because it does not account for time spent 1460 * waiting on a run-queue. Would be prettier if we had floating point. 1461 */ 1462 static int 1463 sched_interact_score(struct thread *td) 1464 { 1465 struct td_sched *ts; 1466 int div; 1467 1468 ts = td->td_sched; 1469 /* 1470 * The score is only needed if this is likely to be an interactive 1471 * task. Don't go through the expense of computing it if there's 1472 * no chance. 1473 */ 1474 if (sched_interact <= SCHED_INTERACT_HALF && 1475 ts->ts_runtime >= ts->ts_slptime) 1476 return (SCHED_INTERACT_HALF); 1477 1478 if (ts->ts_runtime > ts->ts_slptime) { 1479 div = max(1, ts->ts_runtime / SCHED_INTERACT_HALF); 1480 return (SCHED_INTERACT_HALF + 1481 (SCHED_INTERACT_HALF - (ts->ts_slptime / div))); 1482 } 1483 if (ts->ts_slptime > ts->ts_runtime) { 1484 div = max(1, ts->ts_slptime / SCHED_INTERACT_HALF); 1485 return (ts->ts_runtime / div); 1486 } 1487 /* runtime == slptime */ 1488 if (ts->ts_runtime) 1489 return (SCHED_INTERACT_HALF); 1490 1491 /* 1492 * This can happen if slptime and runtime are 0. 1493 */ 1494 return (0); 1495 1496 } 1497 1498 /* 1499 * Scale the scheduling priority according to the "interactivity" of this 1500 * process. 1501 */ 1502 static void 1503 sched_priority(struct thread *td) 1504 { 1505 int score; 1506 int pri; 1507 1508 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 1509 return; 1510 /* 1511 * If the score is interactive we place the thread in the realtime 1512 * queue with a priority that is less than kernel and interrupt 1513 * priorities. These threads are not subject to nice restrictions. 1514 * 1515 * Scores greater than this are placed on the normal timeshare queue 1516 * where the priority is partially decided by the most recent cpu 1517 * utilization and the rest is decided by nice value. 1518 * 1519 * The nice value of the process has a linear effect on the calculated 1520 * score. Negative nice values make it easier for a thread to be 1521 * considered interactive. 1522 */ 1523 score = imax(0, sched_interact_score(td) + td->td_proc->p_nice); 1524 if (score < sched_interact) { 1525 pri = PRI_MIN_INTERACT; 1526 pri += ((PRI_MAX_INTERACT - PRI_MIN_INTERACT + 1) / 1527 sched_interact) * score; 1528 KASSERT(pri >= PRI_MIN_INTERACT && pri <= PRI_MAX_INTERACT, 1529 ("sched_priority: invalid interactive priority %d score %d", 1530 pri, score)); 1531 } else { 1532 pri = SCHED_PRI_MIN; 1533 if (td->td_sched->ts_ticks) 1534 pri += min(SCHED_PRI_TICKS(td->td_sched), 1535 SCHED_PRI_RANGE); 1536 pri += SCHED_PRI_NICE(td->td_proc->p_nice); 1537 KASSERT(pri >= PRI_MIN_BATCH && pri <= PRI_MAX_BATCH, 1538 ("sched_priority: invalid priority %d: nice %d, " 1539 "ticks %d ftick %d ltick %d tick pri %d", 1540 pri, td->td_proc->p_nice, td->td_sched->ts_ticks, 1541 td->td_sched->ts_ftick, td->td_sched->ts_ltick, 1542 SCHED_PRI_TICKS(td->td_sched))); 1543 } 1544 sched_user_prio(td, pri); 1545 1546 return; 1547 } 1548 1549 /* 1550 * This routine enforces a maximum limit on the amount of scheduling history 1551 * kept. It is called after either the slptime or runtime is adjusted. This 1552 * function is ugly due to integer math. 1553 */ 1554 static void 1555 sched_interact_update(struct thread *td) 1556 { 1557 struct td_sched *ts; 1558 u_int sum; 1559 1560 ts = td->td_sched; 1561 sum = ts->ts_runtime + ts->ts_slptime; 1562 if (sum < SCHED_SLP_RUN_MAX) 1563 return; 1564 /* 1565 * This only happens from two places: 1566 * 1) We have added an unusual amount of run time from fork_exit. 1567 * 2) We have added an unusual amount of sleep time from sched_sleep(). 1568 */ 1569 if (sum > SCHED_SLP_RUN_MAX * 2) { 1570 if (ts->ts_runtime > ts->ts_slptime) { 1571 ts->ts_runtime = SCHED_SLP_RUN_MAX; 1572 ts->ts_slptime = 1; 1573 } else { 1574 ts->ts_slptime = SCHED_SLP_RUN_MAX; 1575 ts->ts_runtime = 1; 1576 } 1577 return; 1578 } 1579 /* 1580 * If we have exceeded by more than 1/5th then the algorithm below 1581 * will not bring us back into range. Dividing by two here forces 1582 * us into the range of [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX] 1583 */ 1584 if (sum > (SCHED_SLP_RUN_MAX / 5) * 6) { 1585 ts->ts_runtime /= 2; 1586 ts->ts_slptime /= 2; 1587 return; 1588 } 1589 ts->ts_runtime = (ts->ts_runtime / 5) * 4; 1590 ts->ts_slptime = (ts->ts_slptime / 5) * 4; 1591 } 1592 1593 /* 1594 * Scale back the interactivity history when a child thread is created. The 1595 * history is inherited from the parent but the thread may behave totally 1596 * differently. For example, a shell spawning a compiler process. We want 1597 * to learn that the compiler is behaving badly very quickly. 1598 */ 1599 static void 1600 sched_interact_fork(struct thread *td) 1601 { 1602 int ratio; 1603 int sum; 1604 1605 sum = td->td_sched->ts_runtime + td->td_sched->ts_slptime; 1606 if (sum > SCHED_SLP_RUN_FORK) { 1607 ratio = sum / SCHED_SLP_RUN_FORK; 1608 td->td_sched->ts_runtime /= ratio; 1609 td->td_sched->ts_slptime /= ratio; 1610 } 1611 } 1612 1613 /* 1614 * Called from proc0_init() to setup the scheduler fields. 1615 */ 1616 void 1617 schedinit(void) 1618 { 1619 1620 /* 1621 * Set up the scheduler specific parts of proc0. 1622 */ 1623 proc0.p_sched = NULL; /* XXX */ 1624 thread0.td_sched = &td_sched0; 1625 td_sched0.ts_ltick = ticks; 1626 td_sched0.ts_ftick = ticks; 1627 td_sched0.ts_slice = 0; 1628 } 1629 1630 /* 1631 * This is only somewhat accurate since given many processes of the same 1632 * priority they will switch when their slices run out, which will be 1633 * at most sched_slice stathz ticks. 1634 */ 1635 int 1636 sched_rr_interval(void) 1637 { 1638 1639 /* Convert sched_slice from stathz to hz. */ 1640 return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz)); 1641 } 1642 1643 /* 1644 * Update the percent cpu tracking information when it is requested or 1645 * the total history exceeds the maximum. We keep a sliding history of 1646 * tick counts that slowly decays. This is less precise than the 4BSD 1647 * mechanism since it happens with less regular and frequent events. 1648 */ 1649 static void 1650 sched_pctcpu_update(struct td_sched *ts, int run) 1651 { 1652 int t = ticks; 1653 1654 if (t - ts->ts_ltick >= SCHED_TICK_TARG) { 1655 ts->ts_ticks = 0; 1656 ts->ts_ftick = t - SCHED_TICK_TARG; 1657 } else if (t - ts->ts_ftick >= SCHED_TICK_MAX) { 1658 ts->ts_ticks = (ts->ts_ticks / (ts->ts_ltick - ts->ts_ftick)) * 1659 (ts->ts_ltick - (t - SCHED_TICK_TARG)); 1660 ts->ts_ftick = t - SCHED_TICK_TARG; 1661 } 1662 if (run) 1663 ts->ts_ticks += (t - ts->ts_ltick) << SCHED_TICK_SHIFT; 1664 ts->ts_ltick = t; 1665 } 1666 1667 /* 1668 * Adjust the priority of a thread. Move it to the appropriate run-queue 1669 * if necessary. This is the back-end for several priority related 1670 * functions. 1671 */ 1672 static void 1673 sched_thread_priority(struct thread *td, u_char prio) 1674 { 1675 struct td_sched *ts; 1676 struct tdq *tdq; 1677 int oldpri; 1678 1679 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "prio", 1680 "prio:%d", td->td_priority, "new prio:%d", prio, 1681 KTR_ATTR_LINKED, sched_tdname(curthread)); 1682 SDT_PROBE3(sched, , , change_pri, td, td->td_proc, prio); 1683 if (td != curthread && prio < td->td_priority) { 1684 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread), 1685 "lend prio", "prio:%d", td->td_priority, "new prio:%d", 1686 prio, KTR_ATTR_LINKED, sched_tdname(td)); 1687 SDT_PROBE4(sched, , , lend_pri, td, td->td_proc, prio, 1688 curthread); 1689 } 1690 ts = td->td_sched; 1691 THREAD_LOCK_ASSERT(td, MA_OWNED); 1692 if (td->td_priority == prio) 1693 return; 1694 /* 1695 * If the priority has been elevated due to priority 1696 * propagation, we may have to move ourselves to a new 1697 * queue. This could be optimized to not re-add in some 1698 * cases. 1699 */ 1700 if (TD_ON_RUNQ(td) && prio < td->td_priority) { 1701 sched_rem(td); 1702 td->td_priority = prio; 1703 sched_add(td, SRQ_BORROWING); 1704 return; 1705 } 1706 /* 1707 * If the thread is currently running we may have to adjust the lowpri 1708 * information so other cpus are aware of our current priority. 1709 */ 1710 if (TD_IS_RUNNING(td)) { 1711 tdq = TDQ_CPU(ts->ts_cpu); 1712 oldpri = td->td_priority; 1713 td->td_priority = prio; 1714 if (prio < tdq->tdq_lowpri) 1715 tdq->tdq_lowpri = prio; 1716 else if (tdq->tdq_lowpri == oldpri) 1717 tdq_setlowpri(tdq, td); 1718 return; 1719 } 1720 td->td_priority = prio; 1721 } 1722 1723 /* 1724 * Update a thread's priority when it is lent another thread's 1725 * priority. 1726 */ 1727 void 1728 sched_lend_prio(struct thread *td, u_char prio) 1729 { 1730 1731 td->td_flags |= TDF_BORROWING; 1732 sched_thread_priority(td, prio); 1733 } 1734 1735 /* 1736 * Restore a thread's priority when priority propagation is 1737 * over. The prio argument is the minimum priority the thread 1738 * needs to have to satisfy other possible priority lending 1739 * requests. If the thread's regular priority is less 1740 * important than prio, the thread will keep a priority boost 1741 * of prio. 1742 */ 1743 void 1744 sched_unlend_prio(struct thread *td, u_char prio) 1745 { 1746 u_char base_pri; 1747 1748 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 1749 td->td_base_pri <= PRI_MAX_TIMESHARE) 1750 base_pri = td->td_user_pri; 1751 else 1752 base_pri = td->td_base_pri; 1753 if (prio >= base_pri) { 1754 td->td_flags &= ~TDF_BORROWING; 1755 sched_thread_priority(td, base_pri); 1756 } else 1757 sched_lend_prio(td, prio); 1758 } 1759 1760 /* 1761 * Standard entry for setting the priority to an absolute value. 1762 */ 1763 void 1764 sched_prio(struct thread *td, u_char prio) 1765 { 1766 u_char oldprio; 1767 1768 /* First, update the base priority. */ 1769 td->td_base_pri = prio; 1770 1771 /* 1772 * If the thread is borrowing another thread's priority, don't 1773 * ever lower the priority. 1774 */ 1775 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 1776 return; 1777 1778 /* Change the real priority. */ 1779 oldprio = td->td_priority; 1780 sched_thread_priority(td, prio); 1781 1782 /* 1783 * If the thread is on a turnstile, then let the turnstile update 1784 * its state. 1785 */ 1786 if (TD_ON_LOCK(td) && oldprio != prio) 1787 turnstile_adjust(td, oldprio); 1788 } 1789 1790 /* 1791 * Set the base user priority, does not effect current running priority. 1792 */ 1793 void 1794 sched_user_prio(struct thread *td, u_char prio) 1795 { 1796 1797 td->td_base_user_pri = prio; 1798 if (td->td_lend_user_pri <= prio) 1799 return; 1800 td->td_user_pri = prio; 1801 } 1802 1803 void 1804 sched_lend_user_prio(struct thread *td, u_char prio) 1805 { 1806 1807 THREAD_LOCK_ASSERT(td, MA_OWNED); 1808 td->td_lend_user_pri = prio; 1809 td->td_user_pri = min(prio, td->td_base_user_pri); 1810 if (td->td_priority > td->td_user_pri) 1811 sched_prio(td, td->td_user_pri); 1812 else if (td->td_priority != td->td_user_pri) 1813 td->td_flags |= TDF_NEEDRESCHED; 1814 } 1815 1816 /* 1817 * Handle migration from sched_switch(). This happens only for 1818 * cpu binding. 1819 */ 1820 static struct mtx * 1821 sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags) 1822 { 1823 struct tdq *tdn; 1824 1825 tdn = TDQ_CPU(td->td_sched->ts_cpu); 1826 #ifdef SMP 1827 tdq_load_rem(tdq, td); 1828 /* 1829 * Do the lock dance required to avoid LOR. We grab an extra 1830 * spinlock nesting to prevent preemption while we're 1831 * not holding either run-queue lock. 1832 */ 1833 spinlock_enter(); 1834 thread_lock_block(td); /* This releases the lock on tdq. */ 1835 1836 /* 1837 * Acquire both run-queue locks before placing the thread on the new 1838 * run-queue to avoid deadlocks created by placing a thread with a 1839 * blocked lock on the run-queue of a remote processor. The deadlock 1840 * occurs when a third processor attempts to lock the two queues in 1841 * question while the target processor is spinning with its own 1842 * run-queue lock held while waiting for the blocked lock to clear. 1843 */ 1844 tdq_lock_pair(tdn, tdq); 1845 tdq_add(tdn, td, flags); 1846 tdq_notify(tdn, td); 1847 TDQ_UNLOCK(tdn); 1848 spinlock_exit(); 1849 #endif 1850 return (TDQ_LOCKPTR(tdn)); 1851 } 1852 1853 /* 1854 * Variadic version of thread_lock_unblock() that does not assume td_lock 1855 * is blocked. 1856 */ 1857 static inline void 1858 thread_unblock_switch(struct thread *td, struct mtx *mtx) 1859 { 1860 atomic_store_rel_ptr((volatile uintptr_t *)&td->td_lock, 1861 (uintptr_t)mtx); 1862 } 1863 1864 /* 1865 * Switch threads. This function has to handle threads coming in while 1866 * blocked for some reason, running, or idle. It also must deal with 1867 * migrating a thread from one queue to another as running threads may 1868 * be assigned elsewhere via binding. 1869 */ 1870 void 1871 sched_switch(struct thread *td, struct thread *newtd, int flags) 1872 { 1873 struct tdq *tdq; 1874 struct td_sched *ts; 1875 struct mtx *mtx; 1876 int srqflag; 1877 int cpuid, preempted; 1878 1879 THREAD_LOCK_ASSERT(td, MA_OWNED); 1880 KASSERT(newtd == NULL, ("sched_switch: Unsupported newtd argument")); 1881 1882 cpuid = PCPU_GET(cpuid); 1883 tdq = TDQ_CPU(cpuid); 1884 ts = td->td_sched; 1885 mtx = td->td_lock; 1886 sched_pctcpu_update(ts, 1); 1887 ts->ts_rltick = ticks; 1888 td->td_lastcpu = td->td_oncpu; 1889 td->td_oncpu = NOCPU; 1890 preempted = !(td->td_flags & TDF_SLICEEND); 1891 td->td_flags &= ~(TDF_NEEDRESCHED | TDF_SLICEEND); 1892 td->td_owepreempt = 0; 1893 if (!TD_IS_IDLETHREAD(td)) 1894 tdq->tdq_switchcnt++; 1895 /* 1896 * The lock pointer in an idle thread should never change. Reset it 1897 * to CAN_RUN as well. 1898 */ 1899 if (TD_IS_IDLETHREAD(td)) { 1900 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1901 TD_SET_CAN_RUN(td); 1902 } else if (TD_IS_RUNNING(td)) { 1903 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1904 srqflag = preempted ? 1905 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 1906 SRQ_OURSELF|SRQ_YIELDING; 1907 #ifdef SMP 1908 if (THREAD_CAN_MIGRATE(td) && !THREAD_CAN_SCHED(td, ts->ts_cpu)) 1909 ts->ts_cpu = sched_pickcpu(td, 0); 1910 #endif 1911 if (ts->ts_cpu == cpuid) 1912 tdq_runq_add(tdq, td, srqflag); 1913 else { 1914 KASSERT(THREAD_CAN_MIGRATE(td) || 1915 (ts->ts_flags & TSF_BOUND) != 0, 1916 ("Thread %p shouldn't migrate", td)); 1917 mtx = sched_switch_migrate(tdq, td, srqflag); 1918 } 1919 } else { 1920 /* This thread must be going to sleep. */ 1921 TDQ_LOCK(tdq); 1922 mtx = thread_lock_block(td); 1923 tdq_load_rem(tdq, td); 1924 } 1925 /* 1926 * We enter here with the thread blocked and assigned to the 1927 * appropriate cpu run-queue or sleep-queue and with the current 1928 * thread-queue locked. 1929 */ 1930 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 1931 newtd = choosethread(); 1932 /* 1933 * Call the MD code to switch contexts if necessary. 1934 */ 1935 if (td != newtd) { 1936 #ifdef HWPMC_HOOKS 1937 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1938 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 1939 #endif 1940 SDT_PROBE2(sched, , , off_cpu, newtd, newtd->td_proc); 1941 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 1942 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 1943 sched_pctcpu_update(newtd->td_sched, 0); 1944 1945 #ifdef KDTRACE_HOOKS 1946 /* 1947 * If DTrace has set the active vtime enum to anything 1948 * other than INACTIVE (0), then it should have set the 1949 * function to call. 1950 */ 1951 if (dtrace_vtime_active) 1952 (*dtrace_vtime_switch_func)(newtd); 1953 #endif 1954 1955 cpu_switch(td, newtd, mtx); 1956 /* 1957 * We may return from cpu_switch on a different cpu. However, 1958 * we always return with td_lock pointing to the current cpu's 1959 * run queue lock. 1960 */ 1961 cpuid = PCPU_GET(cpuid); 1962 tdq = TDQ_CPU(cpuid); 1963 lock_profile_obtain_lock_success( 1964 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 1965 1966 SDT_PROBE0(sched, , , on_cpu); 1967 #ifdef HWPMC_HOOKS 1968 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1969 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 1970 #endif 1971 } else { 1972 thread_unblock_switch(td, mtx); 1973 SDT_PROBE0(sched, , , remain_cpu); 1974 } 1975 /* 1976 * Assert that all went well and return. 1977 */ 1978 TDQ_LOCK_ASSERT(tdq, MA_OWNED|MA_NOTRECURSED); 1979 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1980 td->td_oncpu = cpuid; 1981 } 1982 1983 /* 1984 * Adjust thread priorities as a result of a nice request. 1985 */ 1986 void 1987 sched_nice(struct proc *p, int nice) 1988 { 1989 struct thread *td; 1990 1991 PROC_LOCK_ASSERT(p, MA_OWNED); 1992 1993 p->p_nice = nice; 1994 FOREACH_THREAD_IN_PROC(p, td) { 1995 thread_lock(td); 1996 sched_priority(td); 1997 sched_prio(td, td->td_base_user_pri); 1998 thread_unlock(td); 1999 } 2000 } 2001 2002 /* 2003 * Record the sleep time for the interactivity scorer. 2004 */ 2005 void 2006 sched_sleep(struct thread *td, int prio) 2007 { 2008 2009 THREAD_LOCK_ASSERT(td, MA_OWNED); 2010 2011 td->td_slptick = ticks; 2012 if (TD_IS_SUSPENDED(td) || prio >= PSOCK) 2013 td->td_flags |= TDF_CANSWAP; 2014 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 2015 return; 2016 if (static_boost == 1 && prio) 2017 sched_prio(td, prio); 2018 else if (static_boost && td->td_priority > static_boost) 2019 sched_prio(td, static_boost); 2020 } 2021 2022 /* 2023 * Schedule a thread to resume execution and record how long it voluntarily 2024 * slept. We also update the pctcpu, interactivity, and priority. 2025 */ 2026 void 2027 sched_wakeup(struct thread *td) 2028 { 2029 struct td_sched *ts; 2030 int slptick; 2031 2032 THREAD_LOCK_ASSERT(td, MA_OWNED); 2033 ts = td->td_sched; 2034 td->td_flags &= ~TDF_CANSWAP; 2035 /* 2036 * If we slept for more than a tick update our interactivity and 2037 * priority. 2038 */ 2039 slptick = td->td_slptick; 2040 td->td_slptick = 0; 2041 if (slptick && slptick != ticks) { 2042 ts->ts_slptime += (ticks - slptick) << SCHED_TICK_SHIFT; 2043 sched_interact_update(td); 2044 sched_pctcpu_update(ts, 0); 2045 } 2046 /* 2047 * Reset the slice value since we slept and advanced the round-robin. 2048 */ 2049 ts->ts_slice = 0; 2050 sched_add(td, SRQ_BORING); 2051 } 2052 2053 /* 2054 * Penalize the parent for creating a new child and initialize the child's 2055 * priority. 2056 */ 2057 void 2058 sched_fork(struct thread *td, struct thread *child) 2059 { 2060 THREAD_LOCK_ASSERT(td, MA_OWNED); 2061 sched_pctcpu_update(td->td_sched, 1); 2062 sched_fork_thread(td, child); 2063 /* 2064 * Penalize the parent and child for forking. 2065 */ 2066 sched_interact_fork(child); 2067 sched_priority(child); 2068 td->td_sched->ts_runtime += tickincr; 2069 sched_interact_update(td); 2070 sched_priority(td); 2071 } 2072 2073 /* 2074 * Fork a new thread, may be within the same process. 2075 */ 2076 void 2077 sched_fork_thread(struct thread *td, struct thread *child) 2078 { 2079 struct td_sched *ts; 2080 struct td_sched *ts2; 2081 struct tdq *tdq; 2082 2083 tdq = TDQ_SELF(); 2084 THREAD_LOCK_ASSERT(td, MA_OWNED); 2085 /* 2086 * Initialize child. 2087 */ 2088 ts = td->td_sched; 2089 ts2 = child->td_sched; 2090 child->td_lock = TDQ_LOCKPTR(tdq); 2091 child->td_cpuset = cpuset_ref(td->td_cpuset); 2092 ts2->ts_cpu = ts->ts_cpu; 2093 ts2->ts_flags = 0; 2094 /* 2095 * Grab our parents cpu estimation information. 2096 */ 2097 ts2->ts_ticks = ts->ts_ticks; 2098 ts2->ts_ltick = ts->ts_ltick; 2099 ts2->ts_ftick = ts->ts_ftick; 2100 /* 2101 * Do not inherit any borrowed priority from the parent. 2102 */ 2103 child->td_priority = child->td_base_pri; 2104 /* 2105 * And update interactivity score. 2106 */ 2107 ts2->ts_slptime = ts->ts_slptime; 2108 ts2->ts_runtime = ts->ts_runtime; 2109 /* Attempt to quickly learn interactivity. */ 2110 ts2->ts_slice = tdq_slice(tdq) - sched_slice_min; 2111 #ifdef KTR 2112 bzero(ts2->ts_name, sizeof(ts2->ts_name)); 2113 #endif 2114 } 2115 2116 /* 2117 * Adjust the priority class of a thread. 2118 */ 2119 void 2120 sched_class(struct thread *td, int class) 2121 { 2122 2123 THREAD_LOCK_ASSERT(td, MA_OWNED); 2124 if (td->td_pri_class == class) 2125 return; 2126 td->td_pri_class = class; 2127 } 2128 2129 /* 2130 * Return some of the child's priority and interactivity to the parent. 2131 */ 2132 void 2133 sched_exit(struct proc *p, struct thread *child) 2134 { 2135 struct thread *td; 2136 2137 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "proc exit", 2138 "prio:%d", child->td_priority); 2139 PROC_LOCK_ASSERT(p, MA_OWNED); 2140 td = FIRST_THREAD_IN_PROC(p); 2141 sched_exit_thread(td, child); 2142 } 2143 2144 /* 2145 * Penalize another thread for the time spent on this one. This helps to 2146 * worsen the priority and interactivity of processes which schedule batch 2147 * jobs such as make. This has little effect on the make process itself but 2148 * causes new processes spawned by it to receive worse scores immediately. 2149 */ 2150 void 2151 sched_exit_thread(struct thread *td, struct thread *child) 2152 { 2153 2154 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "thread exit", 2155 "prio:%d", child->td_priority); 2156 /* 2157 * Give the child's runtime to the parent without returning the 2158 * sleep time as a penalty to the parent. This causes shells that 2159 * launch expensive things to mark their children as expensive. 2160 */ 2161 thread_lock(td); 2162 td->td_sched->ts_runtime += child->td_sched->ts_runtime; 2163 sched_interact_update(td); 2164 sched_priority(td); 2165 thread_unlock(td); 2166 } 2167 2168 void 2169 sched_preempt(struct thread *td) 2170 { 2171 struct tdq *tdq; 2172 2173 SDT_PROBE2(sched, , , surrender, td, td->td_proc); 2174 2175 thread_lock(td); 2176 tdq = TDQ_SELF(); 2177 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2178 tdq->tdq_ipipending = 0; 2179 if (td->td_priority > tdq->tdq_lowpri) { 2180 int flags; 2181 2182 flags = SW_INVOL | SW_PREEMPT; 2183 if (td->td_critnest > 1) 2184 td->td_owepreempt = 1; 2185 else if (TD_IS_IDLETHREAD(td)) 2186 mi_switch(flags | SWT_REMOTEWAKEIDLE, NULL); 2187 else 2188 mi_switch(flags | SWT_REMOTEPREEMPT, NULL); 2189 } 2190 thread_unlock(td); 2191 } 2192 2193 /* 2194 * Fix priorities on return to user-space. Priorities may be elevated due 2195 * to static priorities in msleep() or similar. 2196 */ 2197 void 2198 sched_userret(struct thread *td) 2199 { 2200 /* 2201 * XXX we cheat slightly on the locking here to avoid locking in 2202 * the usual case. Setting td_priority here is essentially an 2203 * incomplete workaround for not setting it properly elsewhere. 2204 * Now that some interrupt handlers are threads, not setting it 2205 * properly elsewhere can clobber it in the window between setting 2206 * it here and returning to user mode, so don't waste time setting 2207 * it perfectly here. 2208 */ 2209 KASSERT((td->td_flags & TDF_BORROWING) == 0, 2210 ("thread with borrowed priority returning to userland")); 2211 if (td->td_priority != td->td_user_pri) { 2212 thread_lock(td); 2213 td->td_priority = td->td_user_pri; 2214 td->td_base_pri = td->td_user_pri; 2215 tdq_setlowpri(TDQ_SELF(), td); 2216 thread_unlock(td); 2217 } 2218 } 2219 2220 /* 2221 * Handle a stathz tick. This is really only relevant for timeshare 2222 * threads. 2223 */ 2224 void 2225 sched_clock(struct thread *td) 2226 { 2227 struct tdq *tdq; 2228 struct td_sched *ts; 2229 2230 THREAD_LOCK_ASSERT(td, MA_OWNED); 2231 tdq = TDQ_SELF(); 2232 #ifdef SMP 2233 /* 2234 * We run the long term load balancer infrequently on the first cpu. 2235 */ 2236 if (balance_tdq == tdq) { 2237 if (balance_ticks && --balance_ticks == 0) 2238 sched_balance(); 2239 } 2240 #endif 2241 /* 2242 * Save the old switch count so we have a record of the last ticks 2243 * activity. Initialize the new switch count based on our load. 2244 * If there is some activity seed it to reflect that. 2245 */ 2246 tdq->tdq_oldswitchcnt = tdq->tdq_switchcnt; 2247 tdq->tdq_switchcnt = tdq->tdq_load; 2248 /* 2249 * Advance the insert index once for each tick to ensure that all 2250 * threads get a chance to run. 2251 */ 2252 if (tdq->tdq_idx == tdq->tdq_ridx) { 2253 tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS; 2254 if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx])) 2255 tdq->tdq_ridx = tdq->tdq_idx; 2256 } 2257 ts = td->td_sched; 2258 sched_pctcpu_update(ts, 1); 2259 if (td->td_pri_class & PRI_FIFO_BIT) 2260 return; 2261 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) { 2262 /* 2263 * We used a tick; charge it to the thread so 2264 * that we can compute our interactivity. 2265 */ 2266 td->td_sched->ts_runtime += tickincr; 2267 sched_interact_update(td); 2268 sched_priority(td); 2269 } 2270 2271 /* 2272 * Force a context switch if the current thread has used up a full 2273 * time slice (default is 100ms). 2274 */ 2275 if (!TD_IS_IDLETHREAD(td) && ++ts->ts_slice >= tdq_slice(tdq)) { 2276 ts->ts_slice = 0; 2277 td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND; 2278 } 2279 } 2280 2281 /* 2282 * Called once per hz tick. 2283 */ 2284 void 2285 sched_tick(int cnt) 2286 { 2287 2288 } 2289 2290 /* 2291 * Return whether the current CPU has runnable tasks. Used for in-kernel 2292 * cooperative idle threads. 2293 */ 2294 int 2295 sched_runnable(void) 2296 { 2297 struct tdq *tdq; 2298 int load; 2299 2300 load = 1; 2301 2302 tdq = TDQ_SELF(); 2303 if ((curthread->td_flags & TDF_IDLETD) != 0) { 2304 if (tdq->tdq_load > 0) 2305 goto out; 2306 } else 2307 if (tdq->tdq_load - 1 > 0) 2308 goto out; 2309 load = 0; 2310 out: 2311 return (load); 2312 } 2313 2314 /* 2315 * Choose the highest priority thread to run. The thread is removed from 2316 * the run-queue while running however the load remains. For SMP we set 2317 * the tdq in the global idle bitmask if it idles here. 2318 */ 2319 struct thread * 2320 sched_choose(void) 2321 { 2322 struct thread *td; 2323 struct tdq *tdq; 2324 2325 tdq = TDQ_SELF(); 2326 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2327 td = tdq_choose(tdq); 2328 if (td) { 2329 tdq_runq_rem(tdq, td); 2330 tdq->tdq_lowpri = td->td_priority; 2331 return (td); 2332 } 2333 tdq->tdq_lowpri = PRI_MAX_IDLE; 2334 return (PCPU_GET(idlethread)); 2335 } 2336 2337 /* 2338 * Set owepreempt if necessary. Preemption never happens directly in ULE, 2339 * we always request it once we exit a critical section. 2340 */ 2341 static inline void 2342 sched_setpreempt(struct thread *td) 2343 { 2344 struct thread *ctd; 2345 int cpri; 2346 int pri; 2347 2348 THREAD_LOCK_ASSERT(curthread, MA_OWNED); 2349 2350 ctd = curthread; 2351 pri = td->td_priority; 2352 cpri = ctd->td_priority; 2353 if (pri < cpri) 2354 ctd->td_flags |= TDF_NEEDRESCHED; 2355 if (panicstr != NULL || pri >= cpri || cold || TD_IS_INHIBITED(ctd)) 2356 return; 2357 if (!sched_shouldpreempt(pri, cpri, 0)) 2358 return; 2359 ctd->td_owepreempt = 1; 2360 } 2361 2362 /* 2363 * Add a thread to a thread queue. Select the appropriate runq and add the 2364 * thread to it. This is the internal function called when the tdq is 2365 * predetermined. 2366 */ 2367 void 2368 tdq_add(struct tdq *tdq, struct thread *td, int flags) 2369 { 2370 2371 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2372 KASSERT((td->td_inhibitors == 0), 2373 ("sched_add: trying to run inhibited thread")); 2374 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 2375 ("sched_add: bad thread state")); 2376 KASSERT(td->td_flags & TDF_INMEM, 2377 ("sched_add: thread swapped out")); 2378 2379 if (td->td_priority < tdq->tdq_lowpri) 2380 tdq->tdq_lowpri = td->td_priority; 2381 tdq_runq_add(tdq, td, flags); 2382 tdq_load_add(tdq, td); 2383 } 2384 2385 /* 2386 * Select the target thread queue and add a thread to it. Request 2387 * preemption or IPI a remote processor if required. 2388 */ 2389 void 2390 sched_add(struct thread *td, int flags) 2391 { 2392 struct tdq *tdq; 2393 #ifdef SMP 2394 int cpu; 2395 #endif 2396 2397 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 2398 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 2399 sched_tdname(curthread)); 2400 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 2401 KTR_ATTR_LINKED, sched_tdname(td)); 2402 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 2403 flags & SRQ_PREEMPTED); 2404 THREAD_LOCK_ASSERT(td, MA_OWNED); 2405 /* 2406 * Recalculate the priority before we select the target cpu or 2407 * run-queue. 2408 */ 2409 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 2410 sched_priority(td); 2411 #ifdef SMP 2412 /* 2413 * Pick the destination cpu and if it isn't ours transfer to the 2414 * target cpu. 2415 */ 2416 cpu = sched_pickcpu(td, flags); 2417 tdq = sched_setcpu(td, cpu, flags); 2418 tdq_add(tdq, td, flags); 2419 if (cpu != PCPU_GET(cpuid)) { 2420 tdq_notify(tdq, td); 2421 return; 2422 } 2423 #else 2424 tdq = TDQ_SELF(); 2425 TDQ_LOCK(tdq); 2426 /* 2427 * Now that the thread is moving to the run-queue, set the lock 2428 * to the scheduler's lock. 2429 */ 2430 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 2431 tdq_add(tdq, td, flags); 2432 #endif 2433 if (!(flags & SRQ_YIELDING)) 2434 sched_setpreempt(td); 2435 } 2436 2437 /* 2438 * Remove a thread from a run-queue without running it. This is used 2439 * when we're stealing a thread from a remote queue. Otherwise all threads 2440 * exit by calling sched_exit_thread() and sched_throw() themselves. 2441 */ 2442 void 2443 sched_rem(struct thread *td) 2444 { 2445 struct tdq *tdq; 2446 2447 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "runq rem", 2448 "prio:%d", td->td_priority); 2449 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL); 2450 tdq = TDQ_CPU(td->td_sched->ts_cpu); 2451 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2452 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2453 KASSERT(TD_ON_RUNQ(td), 2454 ("sched_rem: thread not on run queue")); 2455 tdq_runq_rem(tdq, td); 2456 tdq_load_rem(tdq, td); 2457 TD_SET_CAN_RUN(td); 2458 if (td->td_priority == tdq->tdq_lowpri) 2459 tdq_setlowpri(tdq, NULL); 2460 } 2461 2462 /* 2463 * Fetch cpu utilization information. Updates on demand. 2464 */ 2465 fixpt_t 2466 sched_pctcpu(struct thread *td) 2467 { 2468 fixpt_t pctcpu; 2469 struct td_sched *ts; 2470 2471 pctcpu = 0; 2472 ts = td->td_sched; 2473 if (ts == NULL) 2474 return (0); 2475 2476 THREAD_LOCK_ASSERT(td, MA_OWNED); 2477 sched_pctcpu_update(ts, TD_IS_RUNNING(td)); 2478 if (ts->ts_ticks) { 2479 int rtick; 2480 2481 /* How many rtick per second ? */ 2482 rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz); 2483 pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT; 2484 } 2485 2486 return (pctcpu); 2487 } 2488 2489 /* 2490 * Enforce affinity settings for a thread. Called after adjustments to 2491 * cpumask. 2492 */ 2493 void 2494 sched_affinity(struct thread *td) 2495 { 2496 #ifdef SMP 2497 struct td_sched *ts; 2498 2499 THREAD_LOCK_ASSERT(td, MA_OWNED); 2500 ts = td->td_sched; 2501 if (THREAD_CAN_SCHED(td, ts->ts_cpu)) 2502 return; 2503 if (TD_ON_RUNQ(td)) { 2504 sched_rem(td); 2505 sched_add(td, SRQ_BORING); 2506 return; 2507 } 2508 if (!TD_IS_RUNNING(td)) 2509 return; 2510 /* 2511 * Force a switch before returning to userspace. If the 2512 * target thread is not running locally send an ipi to force 2513 * the issue. 2514 */ 2515 td->td_flags |= TDF_NEEDRESCHED; 2516 if (td != curthread) 2517 ipi_cpu(ts->ts_cpu, IPI_PREEMPT); 2518 #endif 2519 } 2520 2521 /* 2522 * Bind a thread to a target cpu. 2523 */ 2524 void 2525 sched_bind(struct thread *td, int cpu) 2526 { 2527 struct td_sched *ts; 2528 2529 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 2530 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 2531 ts = td->td_sched; 2532 if (ts->ts_flags & TSF_BOUND) 2533 sched_unbind(td); 2534 KASSERT(THREAD_CAN_MIGRATE(td), ("%p must be migratable", td)); 2535 ts->ts_flags |= TSF_BOUND; 2536 sched_pin(); 2537 if (PCPU_GET(cpuid) == cpu) 2538 return; 2539 ts->ts_cpu = cpu; 2540 /* When we return from mi_switch we'll be on the correct cpu. */ 2541 mi_switch(SW_VOL, NULL); 2542 } 2543 2544 /* 2545 * Release a bound thread. 2546 */ 2547 void 2548 sched_unbind(struct thread *td) 2549 { 2550 struct td_sched *ts; 2551 2552 THREAD_LOCK_ASSERT(td, MA_OWNED); 2553 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 2554 ts = td->td_sched; 2555 if ((ts->ts_flags & TSF_BOUND) == 0) 2556 return; 2557 ts->ts_flags &= ~TSF_BOUND; 2558 sched_unpin(); 2559 } 2560 2561 int 2562 sched_is_bound(struct thread *td) 2563 { 2564 THREAD_LOCK_ASSERT(td, MA_OWNED); 2565 return (td->td_sched->ts_flags & TSF_BOUND); 2566 } 2567 2568 /* 2569 * Basic yield call. 2570 */ 2571 void 2572 sched_relinquish(struct thread *td) 2573 { 2574 thread_lock(td); 2575 mi_switch(SW_VOL | SWT_RELINQUISH, NULL); 2576 thread_unlock(td); 2577 } 2578 2579 /* 2580 * Return the total system load. 2581 */ 2582 int 2583 sched_load(void) 2584 { 2585 #ifdef SMP 2586 int total; 2587 int i; 2588 2589 total = 0; 2590 CPU_FOREACH(i) 2591 total += TDQ_CPU(i)->tdq_sysload; 2592 return (total); 2593 #else 2594 return (TDQ_SELF()->tdq_sysload); 2595 #endif 2596 } 2597 2598 int 2599 sched_sizeof_proc(void) 2600 { 2601 return (sizeof(struct proc)); 2602 } 2603 2604 int 2605 sched_sizeof_thread(void) 2606 { 2607 return (sizeof(struct thread) + sizeof(struct td_sched)); 2608 } 2609 2610 #ifdef SMP 2611 #define TDQ_IDLESPIN(tdq) \ 2612 ((tdq)->tdq_cg != NULL && ((tdq)->tdq_cg->cg_flags & CG_FLAG_THREAD) == 0) 2613 #else 2614 #define TDQ_IDLESPIN(tdq) 1 2615 #endif 2616 2617 /* 2618 * The actual idle process. 2619 */ 2620 void 2621 sched_idletd(void *dummy) 2622 { 2623 struct thread *td; 2624 struct tdq *tdq; 2625 int oldswitchcnt, switchcnt; 2626 int i; 2627 2628 mtx_assert(&Giant, MA_NOTOWNED); 2629 td = curthread; 2630 tdq = TDQ_SELF(); 2631 THREAD_NO_SLEEPING(); 2632 oldswitchcnt = -1; 2633 for (;;) { 2634 if (tdq->tdq_load) { 2635 thread_lock(td); 2636 mi_switch(SW_VOL | SWT_IDLE, NULL); 2637 thread_unlock(td); 2638 } 2639 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2640 #ifdef SMP 2641 if (switchcnt != oldswitchcnt) { 2642 oldswitchcnt = switchcnt; 2643 if (tdq_idled(tdq) == 0) 2644 continue; 2645 } 2646 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2647 #else 2648 oldswitchcnt = switchcnt; 2649 #endif 2650 /* 2651 * If we're switching very frequently, spin while checking 2652 * for load rather than entering a low power state that 2653 * may require an IPI. However, don't do any busy 2654 * loops while on SMT machines as this simply steals 2655 * cycles from cores doing useful work. 2656 */ 2657 if (TDQ_IDLESPIN(tdq) && switchcnt > sched_idlespinthresh) { 2658 for (i = 0; i < sched_idlespins; i++) { 2659 if (tdq->tdq_load) 2660 break; 2661 cpu_spinwait(); 2662 } 2663 } 2664 2665 /* If there was context switch during spin, restart it. */ 2666 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2667 if (tdq->tdq_load != 0 || switchcnt != oldswitchcnt) 2668 continue; 2669 2670 /* Run main MD idle handler. */ 2671 tdq->tdq_cpu_idle = 1; 2672 cpu_idle(switchcnt * 4 > sched_idlespinthresh); 2673 tdq->tdq_cpu_idle = 0; 2674 2675 /* 2676 * Account thread-less hardware interrupts and 2677 * other wakeup reasons equal to context switches. 2678 */ 2679 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2680 if (switchcnt != oldswitchcnt) 2681 continue; 2682 tdq->tdq_switchcnt++; 2683 oldswitchcnt++; 2684 } 2685 } 2686 2687 /* 2688 * A CPU is entering for the first time or a thread is exiting. 2689 */ 2690 void 2691 sched_throw(struct thread *td) 2692 { 2693 struct thread *newtd; 2694 struct tdq *tdq; 2695 2696 tdq = TDQ_SELF(); 2697 if (td == NULL) { 2698 /* Correct spinlock nesting and acquire the correct lock. */ 2699 TDQ_LOCK(tdq); 2700 spinlock_exit(); 2701 PCPU_SET(switchtime, cpu_ticks()); 2702 PCPU_SET(switchticks, ticks); 2703 } else { 2704 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2705 tdq_load_rem(tdq, td); 2706 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 2707 } 2708 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 2709 newtd = choosethread(); 2710 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 2711 cpu_throw(td, newtd); /* doesn't return */ 2712 } 2713 2714 /* 2715 * This is called from fork_exit(). Just acquire the correct locks and 2716 * let fork do the rest of the work. 2717 */ 2718 void 2719 sched_fork_exit(struct thread *td) 2720 { 2721 struct td_sched *ts; 2722 struct tdq *tdq; 2723 int cpuid; 2724 2725 /* 2726 * Finish setting up thread glue so that it begins execution in a 2727 * non-nested critical section with the scheduler lock held. 2728 */ 2729 cpuid = PCPU_GET(cpuid); 2730 tdq = TDQ_CPU(cpuid); 2731 ts = td->td_sched; 2732 if (TD_IS_IDLETHREAD(td)) 2733 td->td_lock = TDQ_LOCKPTR(tdq); 2734 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2735 td->td_oncpu = cpuid; 2736 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 2737 lock_profile_obtain_lock_success( 2738 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 2739 } 2740 2741 /* 2742 * Create on first use to catch odd startup conditons. 2743 */ 2744 char * 2745 sched_tdname(struct thread *td) 2746 { 2747 #ifdef KTR 2748 struct td_sched *ts; 2749 2750 ts = td->td_sched; 2751 if (ts->ts_name[0] == '\0') 2752 snprintf(ts->ts_name, sizeof(ts->ts_name), 2753 "%s tid %d", td->td_name, td->td_tid); 2754 return (ts->ts_name); 2755 #else 2756 return (td->td_name); 2757 #endif 2758 } 2759 2760 #ifdef KTR 2761 void 2762 sched_clear_tdname(struct thread *td) 2763 { 2764 struct td_sched *ts; 2765 2766 ts = td->td_sched; 2767 ts->ts_name[0] = '\0'; 2768 } 2769 #endif 2770 2771 #ifdef SMP 2772 2773 /* 2774 * Build the CPU topology dump string. Is recursively called to collect 2775 * the topology tree. 2776 */ 2777 static int 2778 sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, struct cpu_group *cg, 2779 int indent) 2780 { 2781 char cpusetbuf[CPUSETBUFSIZ]; 2782 int i, first; 2783 2784 sbuf_printf(sb, "%*s<group level=\"%d\" cache-level=\"%d\">\n", indent, 2785 "", 1 + indent / 2, cg->cg_level); 2786 sbuf_printf(sb, "%*s <cpu count=\"%d\" mask=\"%s\">", indent, "", 2787 cg->cg_count, cpusetobj_strprint(cpusetbuf, &cg->cg_mask)); 2788 first = TRUE; 2789 for (i = 0; i < MAXCPU; i++) { 2790 if (CPU_ISSET(i, &cg->cg_mask)) { 2791 if (!first) 2792 sbuf_printf(sb, ", "); 2793 else 2794 first = FALSE; 2795 sbuf_printf(sb, "%d", i); 2796 } 2797 } 2798 sbuf_printf(sb, "</cpu>\n"); 2799 2800 if (cg->cg_flags != 0) { 2801 sbuf_printf(sb, "%*s <flags>", indent, ""); 2802 if ((cg->cg_flags & CG_FLAG_HTT) != 0) 2803 sbuf_printf(sb, "<flag name=\"HTT\">HTT group</flag>"); 2804 if ((cg->cg_flags & CG_FLAG_THREAD) != 0) 2805 sbuf_printf(sb, "<flag name=\"THREAD\">THREAD group</flag>"); 2806 if ((cg->cg_flags & CG_FLAG_SMT) != 0) 2807 sbuf_printf(sb, "<flag name=\"SMT\">SMT group</flag>"); 2808 sbuf_printf(sb, "</flags>\n"); 2809 } 2810 2811 if (cg->cg_children > 0) { 2812 sbuf_printf(sb, "%*s <children>\n", indent, ""); 2813 for (i = 0; i < cg->cg_children; i++) 2814 sysctl_kern_sched_topology_spec_internal(sb, 2815 &cg->cg_child[i], indent+2); 2816 sbuf_printf(sb, "%*s </children>\n", indent, ""); 2817 } 2818 sbuf_printf(sb, "%*s</group>\n", indent, ""); 2819 return (0); 2820 } 2821 2822 /* 2823 * Sysctl handler for retrieving topology dump. It's a wrapper for 2824 * the recursive sysctl_kern_smp_topology_spec_internal(). 2825 */ 2826 static int 2827 sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS) 2828 { 2829 struct sbuf *topo; 2830 int err; 2831 2832 KASSERT(cpu_top != NULL, ("cpu_top isn't initialized")); 2833 2834 topo = sbuf_new(NULL, NULL, 500, SBUF_AUTOEXTEND); 2835 if (topo == NULL) 2836 return (ENOMEM); 2837 2838 sbuf_printf(topo, "<groups>\n"); 2839 err = sysctl_kern_sched_topology_spec_internal(topo, cpu_top, 1); 2840 sbuf_printf(topo, "</groups>\n"); 2841 2842 if (err == 0) { 2843 sbuf_finish(topo); 2844 err = SYSCTL_OUT(req, sbuf_data(topo), sbuf_len(topo)); 2845 } 2846 sbuf_delete(topo); 2847 return (err); 2848 } 2849 2850 #endif 2851 2852 static int 2853 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 2854 { 2855 int error, new_val, period; 2856 2857 period = 1000000 / realstathz; 2858 new_val = period * sched_slice; 2859 error = sysctl_handle_int(oidp, &new_val, 0, req); 2860 if (error != 0 || req->newptr == NULL) 2861 return (error); 2862 if (new_val <= 0) 2863 return (EINVAL); 2864 sched_slice = imax(1, (new_val + period / 2) / period); 2865 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 2866 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 2867 realstathz); 2868 return (0); 2869 } 2870 2871 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0, "Scheduler"); 2872 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0, 2873 "Scheduler name"); 2874 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW, 2875 NULL, 0, sysctl_kern_quantum, "I", 2876 "Quantum for timeshare threads in microseconds"); 2877 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, 2878 "Quantum for timeshare threads in stathz ticks"); 2879 SYSCTL_INT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0, 2880 "Interactivity score threshold"); 2881 SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW, 2882 &preempt_thresh, 0, 2883 "Maximal (lowest) priority for preemption"); 2884 SYSCTL_INT(_kern_sched, OID_AUTO, static_boost, CTLFLAG_RW, &static_boost, 0, 2885 "Assign static kernel priorities to sleeping threads"); 2886 SYSCTL_INT(_kern_sched, OID_AUTO, idlespins, CTLFLAG_RW, &sched_idlespins, 0, 2887 "Number of times idle thread will spin waiting for new work"); 2888 SYSCTL_INT(_kern_sched, OID_AUTO, idlespinthresh, CTLFLAG_RW, 2889 &sched_idlespinthresh, 0, 2890 "Threshold before we will permit idle thread spinning"); 2891 #ifdef SMP 2892 SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0, 2893 "Number of hz ticks to keep thread affinity for"); 2894 SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0, 2895 "Enables the long-term load balancer"); 2896 SYSCTL_INT(_kern_sched, OID_AUTO, balance_interval, CTLFLAG_RW, 2897 &balance_interval, 0, 2898 "Average period in stathz ticks to run the long-term balancer"); 2899 SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0, 2900 "Attempts to steal work from other cores before idling"); 2901 SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0, 2902 "Minimum load on remote CPU before we'll steal"); 2903 SYSCTL_PROC(_kern_sched, OID_AUTO, topology_spec, CTLTYPE_STRING | 2904 CTLFLAG_RD, NULL, 0, sysctl_kern_sched_topology_spec, "A", 2905 "XML dump of detected CPU topology"); 2906 #endif 2907 2908 /* ps compat. All cpu percentages from ULE are weighted. */ 2909 static int ccpu = 0; 2910 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 2911