1 /*- 2 * Copyright (c) 2002-2007, Jeffrey Roberson <jeff@freebsd.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice unmodified, this list of conditions, and the following 10 * disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 /* 28 * This file implements the ULE scheduler. ULE supports independent CPU 29 * run queues and fine grain locking. It has superior interactive 30 * performance under load even on uni-processor systems. 31 * 32 * etymology: 33 * ULE is the last three letters in schedule. It owes its name to a 34 * generic user created for a scheduling system by Paul Mikesell at 35 * Isilon Systems and a general lack of creativity on the part of the author. 36 */ 37 38 #include <sys/cdefs.h> 39 __FBSDID("$FreeBSD$"); 40 41 #include "opt_hwpmc_hooks.h" 42 #include "opt_sched.h" 43 44 #include <sys/param.h> 45 #include <sys/systm.h> 46 #include <sys/kdb.h> 47 #include <sys/kernel.h> 48 #include <sys/ktr.h> 49 #include <sys/limits.h> 50 #include <sys/lock.h> 51 #include <sys/mutex.h> 52 #include <sys/proc.h> 53 #include <sys/resource.h> 54 #include <sys/resourcevar.h> 55 #include <sys/sched.h> 56 #include <sys/sdt.h> 57 #include <sys/smp.h> 58 #include <sys/sx.h> 59 #include <sys/sysctl.h> 60 #include <sys/sysproto.h> 61 #include <sys/turnstile.h> 62 #include <sys/umtx.h> 63 #include <sys/vmmeter.h> 64 #include <sys/cpuset.h> 65 #include <sys/sbuf.h> 66 67 #ifdef HWPMC_HOOKS 68 #include <sys/pmckern.h> 69 #endif 70 71 #ifdef KDTRACE_HOOKS 72 #include <sys/dtrace_bsd.h> 73 int dtrace_vtime_active; 74 dtrace_vtime_switch_func_t dtrace_vtime_switch_func; 75 #endif 76 77 #include <machine/cpu.h> 78 #include <machine/smp.h> 79 80 #define KTR_ULE 0 81 82 #define TS_NAME_LEN (MAXCOMLEN + sizeof(" td ") + sizeof(__XSTRING(UINT_MAX))) 83 #define TDQ_NAME_LEN (sizeof("sched lock ") + sizeof(__XSTRING(MAXCPU))) 84 #define TDQ_LOADNAME_LEN (sizeof("CPU ") + sizeof(__XSTRING(MAXCPU)) - 1 + sizeof(" load")) 85 86 /* 87 * Thread scheduler specific section. All fields are protected 88 * by the thread lock. 89 */ 90 struct td_sched { 91 struct runq *ts_runq; /* Run-queue we're queued on. */ 92 short ts_flags; /* TSF_* flags. */ 93 int ts_cpu; /* CPU that we have affinity for. */ 94 int ts_rltick; /* Real last tick, for affinity. */ 95 int ts_slice; /* Ticks of slice remaining. */ 96 u_int ts_slptime; /* Number of ticks we vol. slept */ 97 u_int ts_runtime; /* Number of ticks we were running */ 98 int ts_ltick; /* Last tick that we were running on */ 99 int ts_ftick; /* First tick that we were running on */ 100 int ts_ticks; /* Tick count */ 101 #ifdef KTR 102 char ts_name[TS_NAME_LEN]; 103 #endif 104 }; 105 /* flags kept in ts_flags */ 106 #define TSF_BOUND 0x0001 /* Thread can not migrate. */ 107 #define TSF_XFERABLE 0x0002 /* Thread was added as transferable. */ 108 109 static struct td_sched td_sched0; 110 111 #define THREAD_CAN_MIGRATE(td) ((td)->td_pinned == 0) 112 #define THREAD_CAN_SCHED(td, cpu) \ 113 CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask) 114 115 /* 116 * Priority ranges used for interactive and non-interactive timeshare 117 * threads. The timeshare priorities are split up into four ranges. 118 * The first range handles interactive threads. The last three ranges 119 * (NHALF, x, and NHALF) handle non-interactive threads with the outer 120 * ranges supporting nice values. 121 */ 122 #define PRI_TIMESHARE_RANGE (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE + 1) 123 #define PRI_INTERACT_RANGE ((PRI_TIMESHARE_RANGE - SCHED_PRI_NRESV) / 2) 124 #define PRI_BATCH_RANGE (PRI_TIMESHARE_RANGE - PRI_INTERACT_RANGE) 125 126 #define PRI_MIN_INTERACT PRI_MIN_TIMESHARE 127 #define PRI_MAX_INTERACT (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE - 1) 128 #define PRI_MIN_BATCH (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE) 129 #define PRI_MAX_BATCH PRI_MAX_TIMESHARE 130 131 /* 132 * Cpu percentage computation macros and defines. 133 * 134 * SCHED_TICK_SECS: Number of seconds to average the cpu usage across. 135 * SCHED_TICK_TARG: Number of hz ticks to average the cpu usage across. 136 * SCHED_TICK_MAX: Maximum number of ticks before scaling back. 137 * SCHED_TICK_SHIFT: Shift factor to avoid rounding away results. 138 * SCHED_TICK_HZ: Compute the number of hz ticks for a given ticks count. 139 * SCHED_TICK_TOTAL: Gives the amount of time we've been recording ticks. 140 */ 141 #define SCHED_TICK_SECS 10 142 #define SCHED_TICK_TARG (hz * SCHED_TICK_SECS) 143 #define SCHED_TICK_MAX (SCHED_TICK_TARG + hz) 144 #define SCHED_TICK_SHIFT 10 145 #define SCHED_TICK_HZ(ts) ((ts)->ts_ticks >> SCHED_TICK_SHIFT) 146 #define SCHED_TICK_TOTAL(ts) (max((ts)->ts_ltick - (ts)->ts_ftick, hz)) 147 148 /* 149 * These macros determine priorities for non-interactive threads. They are 150 * assigned a priority based on their recent cpu utilization as expressed 151 * by the ratio of ticks to the tick total. NHALF priorities at the start 152 * and end of the MIN to MAX timeshare range are only reachable with negative 153 * or positive nice respectively. 154 * 155 * PRI_RANGE: Priority range for utilization dependent priorities. 156 * PRI_NRESV: Number of nice values. 157 * PRI_TICKS: Compute a priority in PRI_RANGE from the ticks count and total. 158 * PRI_NICE: Determines the part of the priority inherited from nice. 159 */ 160 #define SCHED_PRI_NRESV (PRIO_MAX - PRIO_MIN) 161 #define SCHED_PRI_NHALF (SCHED_PRI_NRESV / 2) 162 #define SCHED_PRI_MIN (PRI_MIN_BATCH + SCHED_PRI_NHALF) 163 #define SCHED_PRI_MAX (PRI_MAX_BATCH - SCHED_PRI_NHALF) 164 #define SCHED_PRI_RANGE (SCHED_PRI_MAX - SCHED_PRI_MIN + 1) 165 #define SCHED_PRI_TICKS(ts) \ 166 (SCHED_TICK_HZ((ts)) / \ 167 (roundup(SCHED_TICK_TOTAL((ts)), SCHED_PRI_RANGE) / SCHED_PRI_RANGE)) 168 #define SCHED_PRI_NICE(nice) (nice) 169 170 /* 171 * These determine the interactivity of a process. Interactivity differs from 172 * cpu utilization in that it expresses the voluntary time slept vs time ran 173 * while cpu utilization includes all time not running. This more accurately 174 * models the intent of the thread. 175 * 176 * SLP_RUN_MAX: Maximum amount of sleep time + run time we'll accumulate 177 * before throttling back. 178 * SLP_RUN_FORK: Maximum slp+run time to inherit at fork time. 179 * INTERACT_MAX: Maximum interactivity value. Smaller is better. 180 * INTERACT_THRESH: Threshold for placement on the current runq. 181 */ 182 #define SCHED_SLP_RUN_MAX ((hz * 5) << SCHED_TICK_SHIFT) 183 #define SCHED_SLP_RUN_FORK ((hz / 2) << SCHED_TICK_SHIFT) 184 #define SCHED_INTERACT_MAX (100) 185 #define SCHED_INTERACT_HALF (SCHED_INTERACT_MAX / 2) 186 #define SCHED_INTERACT_THRESH (30) 187 188 /* 189 * These parameters determine the slice behavior for batch work. 190 */ 191 #define SCHED_SLICE_DEFAULT_DIVISOR 10 /* ~94 ms, 12 stathz ticks. */ 192 #define SCHED_SLICE_MIN_DIVISOR 6 /* DEFAULT/MIN = ~16 ms. */ 193 194 /* Flags kept in td_flags. */ 195 #define TDF_SLICEEND TDF_SCHED2 /* Thread time slice is over. */ 196 197 /* 198 * tickincr: Converts a stathz tick into a hz domain scaled by 199 * the shift factor. Without the shift the error rate 200 * due to rounding would be unacceptably high. 201 * realstathz: stathz is sometimes 0 and run off of hz. 202 * sched_slice: Runtime of each thread before rescheduling. 203 * preempt_thresh: Priority threshold for preemption and remote IPIs. 204 */ 205 static int sched_interact = SCHED_INTERACT_THRESH; 206 static int tickincr = 8 << SCHED_TICK_SHIFT; 207 static int realstathz = 127; /* reset during boot. */ 208 static int sched_slice = 10; /* reset during boot. */ 209 static int sched_slice_min = 1; /* reset during boot. */ 210 #ifdef PREEMPTION 211 #ifdef FULL_PREEMPTION 212 static int preempt_thresh = PRI_MAX_IDLE; 213 #else 214 static int preempt_thresh = PRI_MIN_KERN; 215 #endif 216 #else 217 static int preempt_thresh = 0; 218 #endif 219 static int static_boost = PRI_MIN_BATCH; 220 static int sched_idlespins = 10000; 221 static int sched_idlespinthresh = -1; 222 223 /* 224 * tdq - per processor runqs and statistics. All fields are protected by the 225 * tdq_lock. The load and lowpri may be accessed without to avoid excess 226 * locking in sched_pickcpu(); 227 */ 228 struct tdq { 229 /* 230 * Ordered to improve efficiency of cpu_search() and switch(). 231 * tdq_lock is padded to avoid false sharing with tdq_load and 232 * tdq_cpu_idle. 233 */ 234 struct mtx_padalign tdq_lock; /* run queue lock. */ 235 struct cpu_group *tdq_cg; /* Pointer to cpu topology. */ 236 volatile int tdq_load; /* Aggregate load. */ 237 volatile int tdq_cpu_idle; /* cpu_idle() is active. */ 238 int tdq_sysload; /* For loadavg, !ITHD load. */ 239 int tdq_transferable; /* Transferable thread count. */ 240 short tdq_switchcnt; /* Switches this tick. */ 241 short tdq_oldswitchcnt; /* Switches last tick. */ 242 u_char tdq_lowpri; /* Lowest priority thread. */ 243 u_char tdq_ipipending; /* IPI pending. */ 244 u_char tdq_idx; /* Current insert index. */ 245 u_char tdq_ridx; /* Current removal index. */ 246 struct runq tdq_realtime; /* real-time run queue. */ 247 struct runq tdq_timeshare; /* timeshare run queue. */ 248 struct runq tdq_idle; /* Queue of IDLE threads. */ 249 char tdq_name[TDQ_NAME_LEN]; 250 #ifdef KTR 251 char tdq_loadname[TDQ_LOADNAME_LEN]; 252 #endif 253 } __aligned(64); 254 255 /* Idle thread states and config. */ 256 #define TDQ_RUNNING 1 257 #define TDQ_IDLE 2 258 259 #ifdef SMP 260 struct cpu_group *cpu_top; /* CPU topology */ 261 262 #define SCHED_AFFINITY_DEFAULT (max(1, hz / 1000)) 263 #define SCHED_AFFINITY(ts, t) ((ts)->ts_rltick > ticks - ((t) * affinity)) 264 265 /* 266 * Run-time tunables. 267 */ 268 static int rebalance = 1; 269 static int balance_interval = 128; /* Default set in sched_initticks(). */ 270 static int affinity; 271 static int steal_idle = 1; 272 static int steal_thresh = 2; 273 274 /* 275 * One thread queue per processor. 276 */ 277 static struct tdq tdq_cpu[MAXCPU]; 278 static struct tdq *balance_tdq; 279 static int balance_ticks; 280 static DPCPU_DEFINE(uint32_t, randomval); 281 282 #define TDQ_SELF() (&tdq_cpu[PCPU_GET(cpuid)]) 283 #define TDQ_CPU(x) (&tdq_cpu[(x)]) 284 #define TDQ_ID(x) ((int)((x) - tdq_cpu)) 285 #else /* !SMP */ 286 static struct tdq tdq_cpu; 287 288 #define TDQ_ID(x) (0) 289 #define TDQ_SELF() (&tdq_cpu) 290 #define TDQ_CPU(x) (&tdq_cpu) 291 #endif 292 293 #define TDQ_LOCK_ASSERT(t, type) mtx_assert(TDQ_LOCKPTR((t)), (type)) 294 #define TDQ_LOCK(t) mtx_lock_spin(TDQ_LOCKPTR((t))) 295 #define TDQ_LOCK_FLAGS(t, f) mtx_lock_spin_flags(TDQ_LOCKPTR((t)), (f)) 296 #define TDQ_UNLOCK(t) mtx_unlock_spin(TDQ_LOCKPTR((t))) 297 #define TDQ_LOCKPTR(t) ((struct mtx *)(&(t)->tdq_lock)) 298 299 static void sched_priority(struct thread *); 300 static void sched_thread_priority(struct thread *, u_char); 301 static int sched_interact_score(struct thread *); 302 static void sched_interact_update(struct thread *); 303 static void sched_interact_fork(struct thread *); 304 static void sched_pctcpu_update(struct td_sched *, int); 305 306 /* Operations on per processor queues */ 307 static struct thread *tdq_choose(struct tdq *); 308 static void tdq_setup(struct tdq *); 309 static void tdq_load_add(struct tdq *, struct thread *); 310 static void tdq_load_rem(struct tdq *, struct thread *); 311 static __inline void tdq_runq_add(struct tdq *, struct thread *, int); 312 static __inline void tdq_runq_rem(struct tdq *, struct thread *); 313 static inline int sched_shouldpreempt(int, int, int); 314 void tdq_print(int cpu); 315 static void runq_print(struct runq *rq); 316 static void tdq_add(struct tdq *, struct thread *, int); 317 #ifdef SMP 318 static int tdq_move(struct tdq *, struct tdq *); 319 static int tdq_idled(struct tdq *); 320 static void tdq_notify(struct tdq *, struct thread *); 321 static struct thread *tdq_steal(struct tdq *, int); 322 static struct thread *runq_steal(struct runq *, int); 323 static int sched_pickcpu(struct thread *, int); 324 static void sched_balance(void); 325 static int sched_balance_pair(struct tdq *, struct tdq *); 326 static inline struct tdq *sched_setcpu(struct thread *, int, int); 327 static inline void thread_unblock_switch(struct thread *, struct mtx *); 328 static struct mtx *sched_switch_migrate(struct tdq *, struct thread *, int); 329 static int sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS); 330 static int sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, 331 struct cpu_group *cg, int indent); 332 #endif 333 334 static void sched_setup(void *dummy); 335 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL); 336 337 static void sched_initticks(void *dummy); 338 SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks, 339 NULL); 340 341 SDT_PROVIDER_DEFINE(sched); 342 343 SDT_PROBE_DEFINE3(sched, , , change__pri, "struct thread *", 344 "struct proc *", "uint8_t"); 345 SDT_PROBE_DEFINE3(sched, , , dequeue, "struct thread *", 346 "struct proc *", "void *"); 347 SDT_PROBE_DEFINE4(sched, , , enqueue, "struct thread *", 348 "struct proc *", "void *", "int"); 349 SDT_PROBE_DEFINE4(sched, , , lend__pri, "struct thread *", 350 "struct proc *", "uint8_t", "struct thread *"); 351 SDT_PROBE_DEFINE2(sched, , , load__change, "int", "int"); 352 SDT_PROBE_DEFINE2(sched, , , off__cpu, "struct thread *", 353 "struct proc *"); 354 SDT_PROBE_DEFINE(sched, , , on__cpu); 355 SDT_PROBE_DEFINE(sched, , , remain__cpu); 356 SDT_PROBE_DEFINE2(sched, , , surrender, "struct thread *", 357 "struct proc *"); 358 359 #ifdef SMP 360 /* 361 * We need some randomness. Implement the classic Linear Congruential 362 * generator X_{n+1}=(aX_n+c) mod m. These values are optimized for 363 * m = 2^32, a = 69069 and c = 5. We only return the upper 16 bits 364 * of the random state (in the low bits of our answer) to return 365 * the maximum randomness. 366 */ 367 static uint32_t 368 sched_random(void) 369 { 370 uint32_t *rndptr; 371 372 rndptr = DPCPU_PTR(randomval); 373 *rndptr = *rndptr * 69069 + 5; 374 375 return (*rndptr >> 16); 376 } 377 #endif 378 379 /* 380 * Print the threads waiting on a run-queue. 381 */ 382 static void 383 runq_print(struct runq *rq) 384 { 385 struct rqhead *rqh; 386 struct thread *td; 387 int pri; 388 int j; 389 int i; 390 391 for (i = 0; i < RQB_LEN; i++) { 392 printf("\t\trunq bits %d 0x%zx\n", 393 i, rq->rq_status.rqb_bits[i]); 394 for (j = 0; j < RQB_BPW; j++) 395 if (rq->rq_status.rqb_bits[i] & (1ul << j)) { 396 pri = j + (i << RQB_L2BPW); 397 rqh = &rq->rq_queues[pri]; 398 TAILQ_FOREACH(td, rqh, td_runq) { 399 printf("\t\t\ttd %p(%s) priority %d rqindex %d pri %d\n", 400 td, td->td_name, td->td_priority, 401 td->td_rqindex, pri); 402 } 403 } 404 } 405 } 406 407 /* 408 * Print the status of a per-cpu thread queue. Should be a ddb show cmd. 409 */ 410 void 411 tdq_print(int cpu) 412 { 413 struct tdq *tdq; 414 415 tdq = TDQ_CPU(cpu); 416 417 printf("tdq %d:\n", TDQ_ID(tdq)); 418 printf("\tlock %p\n", TDQ_LOCKPTR(tdq)); 419 printf("\tLock name: %s\n", tdq->tdq_name); 420 printf("\tload: %d\n", tdq->tdq_load); 421 printf("\tswitch cnt: %d\n", tdq->tdq_switchcnt); 422 printf("\told switch cnt: %d\n", tdq->tdq_oldswitchcnt); 423 printf("\ttimeshare idx: %d\n", tdq->tdq_idx); 424 printf("\ttimeshare ridx: %d\n", tdq->tdq_ridx); 425 printf("\tload transferable: %d\n", tdq->tdq_transferable); 426 printf("\tlowest priority: %d\n", tdq->tdq_lowpri); 427 printf("\trealtime runq:\n"); 428 runq_print(&tdq->tdq_realtime); 429 printf("\ttimeshare runq:\n"); 430 runq_print(&tdq->tdq_timeshare); 431 printf("\tidle runq:\n"); 432 runq_print(&tdq->tdq_idle); 433 } 434 435 static inline int 436 sched_shouldpreempt(int pri, int cpri, int remote) 437 { 438 /* 439 * If the new priority is not better than the current priority there is 440 * nothing to do. 441 */ 442 if (pri >= cpri) 443 return (0); 444 /* 445 * Always preempt idle. 446 */ 447 if (cpri >= PRI_MIN_IDLE) 448 return (1); 449 /* 450 * If preemption is disabled don't preempt others. 451 */ 452 if (preempt_thresh == 0) 453 return (0); 454 /* 455 * Preempt if we exceed the threshold. 456 */ 457 if (pri <= preempt_thresh) 458 return (1); 459 /* 460 * If we're interactive or better and there is non-interactive 461 * or worse running preempt only remote processors. 462 */ 463 if (remote && pri <= PRI_MAX_INTERACT && cpri > PRI_MAX_INTERACT) 464 return (1); 465 return (0); 466 } 467 468 /* 469 * Add a thread to the actual run-queue. Keeps transferable counts up to 470 * date with what is actually on the run-queue. Selects the correct 471 * queue position for timeshare threads. 472 */ 473 static __inline void 474 tdq_runq_add(struct tdq *tdq, struct thread *td, int flags) 475 { 476 struct td_sched *ts; 477 u_char pri; 478 479 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 480 THREAD_LOCK_ASSERT(td, MA_OWNED); 481 482 pri = td->td_priority; 483 ts = td->td_sched; 484 TD_SET_RUNQ(td); 485 if (THREAD_CAN_MIGRATE(td)) { 486 tdq->tdq_transferable++; 487 ts->ts_flags |= TSF_XFERABLE; 488 } 489 if (pri < PRI_MIN_BATCH) { 490 ts->ts_runq = &tdq->tdq_realtime; 491 } else if (pri <= PRI_MAX_BATCH) { 492 ts->ts_runq = &tdq->tdq_timeshare; 493 KASSERT(pri <= PRI_MAX_BATCH && pri >= PRI_MIN_BATCH, 494 ("Invalid priority %d on timeshare runq", pri)); 495 /* 496 * This queue contains only priorities between MIN and MAX 497 * realtime. Use the whole queue to represent these values. 498 */ 499 if ((flags & (SRQ_BORROWING|SRQ_PREEMPTED)) == 0) { 500 pri = RQ_NQS * (pri - PRI_MIN_BATCH) / PRI_BATCH_RANGE; 501 pri = (pri + tdq->tdq_idx) % RQ_NQS; 502 /* 503 * This effectively shortens the queue by one so we 504 * can have a one slot difference between idx and 505 * ridx while we wait for threads to drain. 506 */ 507 if (tdq->tdq_ridx != tdq->tdq_idx && 508 pri == tdq->tdq_ridx) 509 pri = (unsigned char)(pri - 1) % RQ_NQS; 510 } else 511 pri = tdq->tdq_ridx; 512 runq_add_pri(ts->ts_runq, td, pri, flags); 513 return; 514 } else 515 ts->ts_runq = &tdq->tdq_idle; 516 runq_add(ts->ts_runq, td, flags); 517 } 518 519 /* 520 * Remove a thread from a run-queue. This typically happens when a thread 521 * is selected to run. Running threads are not on the queue and the 522 * transferable count does not reflect them. 523 */ 524 static __inline void 525 tdq_runq_rem(struct tdq *tdq, struct thread *td) 526 { 527 struct td_sched *ts; 528 529 ts = td->td_sched; 530 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 531 KASSERT(ts->ts_runq != NULL, 532 ("tdq_runq_remove: thread %p null ts_runq", td)); 533 if (ts->ts_flags & TSF_XFERABLE) { 534 tdq->tdq_transferable--; 535 ts->ts_flags &= ~TSF_XFERABLE; 536 } 537 if (ts->ts_runq == &tdq->tdq_timeshare) { 538 if (tdq->tdq_idx != tdq->tdq_ridx) 539 runq_remove_idx(ts->ts_runq, td, &tdq->tdq_ridx); 540 else 541 runq_remove_idx(ts->ts_runq, td, NULL); 542 } else 543 runq_remove(ts->ts_runq, td); 544 } 545 546 /* 547 * Load is maintained for all threads RUNNING and ON_RUNQ. Add the load 548 * for this thread to the referenced thread queue. 549 */ 550 static void 551 tdq_load_add(struct tdq *tdq, struct thread *td) 552 { 553 554 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 555 THREAD_LOCK_ASSERT(td, MA_OWNED); 556 557 tdq->tdq_load++; 558 if ((td->td_flags & TDF_NOLOAD) == 0) 559 tdq->tdq_sysload++; 560 KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load); 561 SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load); 562 } 563 564 /* 565 * Remove the load from a thread that is transitioning to a sleep state or 566 * exiting. 567 */ 568 static void 569 tdq_load_rem(struct tdq *tdq, struct thread *td) 570 { 571 572 THREAD_LOCK_ASSERT(td, MA_OWNED); 573 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 574 KASSERT(tdq->tdq_load != 0, 575 ("tdq_load_rem: Removing with 0 load on queue %d", TDQ_ID(tdq))); 576 577 tdq->tdq_load--; 578 if ((td->td_flags & TDF_NOLOAD) == 0) 579 tdq->tdq_sysload--; 580 KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load); 581 SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load); 582 } 583 584 /* 585 * Bound timeshare latency by decreasing slice size as load increases. We 586 * consider the maximum latency as the sum of the threads waiting to run 587 * aside from curthread and target no more than sched_slice latency but 588 * no less than sched_slice_min runtime. 589 */ 590 static inline int 591 tdq_slice(struct tdq *tdq) 592 { 593 int load; 594 595 /* 596 * It is safe to use sys_load here because this is called from 597 * contexts where timeshare threads are running and so there 598 * cannot be higher priority load in the system. 599 */ 600 load = tdq->tdq_sysload - 1; 601 if (load >= SCHED_SLICE_MIN_DIVISOR) 602 return (sched_slice_min); 603 if (load <= 1) 604 return (sched_slice); 605 return (sched_slice / load); 606 } 607 608 /* 609 * Set lowpri to its exact value by searching the run-queue and 610 * evaluating curthread. curthread may be passed as an optimization. 611 */ 612 static void 613 tdq_setlowpri(struct tdq *tdq, struct thread *ctd) 614 { 615 struct thread *td; 616 617 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 618 if (ctd == NULL) 619 ctd = pcpu_find(TDQ_ID(tdq))->pc_curthread; 620 td = tdq_choose(tdq); 621 if (td == NULL || td->td_priority > ctd->td_priority) 622 tdq->tdq_lowpri = ctd->td_priority; 623 else 624 tdq->tdq_lowpri = td->td_priority; 625 } 626 627 #ifdef SMP 628 struct cpu_search { 629 cpuset_t cs_mask; 630 u_int cs_prefer; 631 int cs_pri; /* Min priority for low. */ 632 int cs_limit; /* Max load for low, min load for high. */ 633 int cs_cpu; 634 int cs_load; 635 }; 636 637 #define CPU_SEARCH_LOWEST 0x1 638 #define CPU_SEARCH_HIGHEST 0x2 639 #define CPU_SEARCH_BOTH (CPU_SEARCH_LOWEST|CPU_SEARCH_HIGHEST) 640 641 #define CPUSET_FOREACH(cpu, mask) \ 642 for ((cpu) = 0; (cpu) <= mp_maxid; (cpu)++) \ 643 if (CPU_ISSET(cpu, &mask)) 644 645 static __always_inline int cpu_search(const struct cpu_group *cg, 646 struct cpu_search *low, struct cpu_search *high, const int match); 647 int __noinline cpu_search_lowest(const struct cpu_group *cg, 648 struct cpu_search *low); 649 int __noinline cpu_search_highest(const struct cpu_group *cg, 650 struct cpu_search *high); 651 int __noinline cpu_search_both(const struct cpu_group *cg, 652 struct cpu_search *low, struct cpu_search *high); 653 654 /* 655 * Search the tree of cpu_groups for the lowest or highest loaded cpu 656 * according to the match argument. This routine actually compares the 657 * load on all paths through the tree and finds the least loaded cpu on 658 * the least loaded path, which may differ from the least loaded cpu in 659 * the system. This balances work among caches and busses. 660 * 661 * This inline is instantiated in three forms below using constants for the 662 * match argument. It is reduced to the minimum set for each case. It is 663 * also recursive to the depth of the tree. 664 */ 665 static __always_inline int 666 cpu_search(const struct cpu_group *cg, struct cpu_search *low, 667 struct cpu_search *high, const int match) 668 { 669 struct cpu_search lgroup; 670 struct cpu_search hgroup; 671 cpuset_t cpumask; 672 struct cpu_group *child; 673 struct tdq *tdq; 674 int cpu, i, hload, lload, load, total, rnd; 675 676 total = 0; 677 cpumask = cg->cg_mask; 678 if (match & CPU_SEARCH_LOWEST) { 679 lload = INT_MAX; 680 lgroup = *low; 681 } 682 if (match & CPU_SEARCH_HIGHEST) { 683 hload = INT_MIN; 684 hgroup = *high; 685 } 686 687 /* Iterate through the child CPU groups and then remaining CPUs. */ 688 for (i = cg->cg_children, cpu = mp_maxid; ; ) { 689 if (i == 0) { 690 #ifdef HAVE_INLINE_FFSL 691 cpu = CPU_FFS(&cpumask) - 1; 692 #else 693 while (cpu >= 0 && !CPU_ISSET(cpu, &cpumask)) 694 cpu--; 695 #endif 696 if (cpu < 0) 697 break; 698 child = NULL; 699 } else 700 child = &cg->cg_child[i - 1]; 701 702 if (match & CPU_SEARCH_LOWEST) 703 lgroup.cs_cpu = -1; 704 if (match & CPU_SEARCH_HIGHEST) 705 hgroup.cs_cpu = -1; 706 if (child) { /* Handle child CPU group. */ 707 CPU_NAND(&cpumask, &child->cg_mask); 708 switch (match) { 709 case CPU_SEARCH_LOWEST: 710 load = cpu_search_lowest(child, &lgroup); 711 break; 712 case CPU_SEARCH_HIGHEST: 713 load = cpu_search_highest(child, &hgroup); 714 break; 715 case CPU_SEARCH_BOTH: 716 load = cpu_search_both(child, &lgroup, &hgroup); 717 break; 718 } 719 } else { /* Handle child CPU. */ 720 CPU_CLR(cpu, &cpumask); 721 tdq = TDQ_CPU(cpu); 722 load = tdq->tdq_load * 256; 723 rnd = sched_random() % 32; 724 if (match & CPU_SEARCH_LOWEST) { 725 if (cpu == low->cs_prefer) 726 load -= 64; 727 /* If that CPU is allowed and get data. */ 728 if (tdq->tdq_lowpri > lgroup.cs_pri && 729 tdq->tdq_load <= lgroup.cs_limit && 730 CPU_ISSET(cpu, &lgroup.cs_mask)) { 731 lgroup.cs_cpu = cpu; 732 lgroup.cs_load = load - rnd; 733 } 734 } 735 if (match & CPU_SEARCH_HIGHEST) 736 if (tdq->tdq_load >= hgroup.cs_limit && 737 tdq->tdq_transferable && 738 CPU_ISSET(cpu, &hgroup.cs_mask)) { 739 hgroup.cs_cpu = cpu; 740 hgroup.cs_load = load - rnd; 741 } 742 } 743 total += load; 744 745 /* We have info about child item. Compare it. */ 746 if (match & CPU_SEARCH_LOWEST) { 747 if (lgroup.cs_cpu >= 0 && 748 (load < lload || 749 (load == lload && lgroup.cs_load < low->cs_load))) { 750 lload = load; 751 low->cs_cpu = lgroup.cs_cpu; 752 low->cs_load = lgroup.cs_load; 753 } 754 } 755 if (match & CPU_SEARCH_HIGHEST) 756 if (hgroup.cs_cpu >= 0 && 757 (load > hload || 758 (load == hload && hgroup.cs_load > high->cs_load))) { 759 hload = load; 760 high->cs_cpu = hgroup.cs_cpu; 761 high->cs_load = hgroup.cs_load; 762 } 763 if (child) { 764 i--; 765 if (i == 0 && CPU_EMPTY(&cpumask)) 766 break; 767 } 768 #ifndef HAVE_INLINE_FFSL 769 else 770 cpu--; 771 #endif 772 } 773 return (total); 774 } 775 776 /* 777 * cpu_search instantiations must pass constants to maintain the inline 778 * optimization. 779 */ 780 int 781 cpu_search_lowest(const struct cpu_group *cg, struct cpu_search *low) 782 { 783 return cpu_search(cg, low, NULL, CPU_SEARCH_LOWEST); 784 } 785 786 int 787 cpu_search_highest(const struct cpu_group *cg, struct cpu_search *high) 788 { 789 return cpu_search(cg, NULL, high, CPU_SEARCH_HIGHEST); 790 } 791 792 int 793 cpu_search_both(const struct cpu_group *cg, struct cpu_search *low, 794 struct cpu_search *high) 795 { 796 return cpu_search(cg, low, high, CPU_SEARCH_BOTH); 797 } 798 799 /* 800 * Find the cpu with the least load via the least loaded path that has a 801 * lowpri greater than pri pri. A pri of -1 indicates any priority is 802 * acceptable. 803 */ 804 static inline int 805 sched_lowest(const struct cpu_group *cg, cpuset_t mask, int pri, int maxload, 806 int prefer) 807 { 808 struct cpu_search low; 809 810 low.cs_cpu = -1; 811 low.cs_prefer = prefer; 812 low.cs_mask = mask; 813 low.cs_pri = pri; 814 low.cs_limit = maxload; 815 cpu_search_lowest(cg, &low); 816 return low.cs_cpu; 817 } 818 819 /* 820 * Find the cpu with the highest load via the highest loaded path. 821 */ 822 static inline int 823 sched_highest(const struct cpu_group *cg, cpuset_t mask, int minload) 824 { 825 struct cpu_search high; 826 827 high.cs_cpu = -1; 828 high.cs_mask = mask; 829 high.cs_limit = minload; 830 cpu_search_highest(cg, &high); 831 return high.cs_cpu; 832 } 833 834 static void 835 sched_balance_group(struct cpu_group *cg) 836 { 837 cpuset_t hmask, lmask; 838 int high, low, anylow; 839 840 CPU_FILL(&hmask); 841 for (;;) { 842 high = sched_highest(cg, hmask, 1); 843 /* Stop if there is no more CPU with transferrable threads. */ 844 if (high == -1) 845 break; 846 CPU_CLR(high, &hmask); 847 CPU_COPY(&hmask, &lmask); 848 /* Stop if there is no more CPU left for low. */ 849 if (CPU_EMPTY(&lmask)) 850 break; 851 anylow = 1; 852 nextlow: 853 low = sched_lowest(cg, lmask, -1, 854 TDQ_CPU(high)->tdq_load - 1, high); 855 /* Stop if we looked well and found no less loaded CPU. */ 856 if (anylow && low == -1) 857 break; 858 /* Go to next high if we found no less loaded CPU. */ 859 if (low == -1) 860 continue; 861 /* Transfer thread from high to low. */ 862 if (sched_balance_pair(TDQ_CPU(high), TDQ_CPU(low))) { 863 /* CPU that got thread can no longer be a donor. */ 864 CPU_CLR(low, &hmask); 865 } else { 866 /* 867 * If failed, then there is no threads on high 868 * that can run on this low. Drop low from low 869 * mask and look for different one. 870 */ 871 CPU_CLR(low, &lmask); 872 anylow = 0; 873 goto nextlow; 874 } 875 } 876 } 877 878 static void 879 sched_balance(void) 880 { 881 struct tdq *tdq; 882 883 if (smp_started == 0 || rebalance == 0) 884 return; 885 886 balance_ticks = max(balance_interval / 2, 1) + 887 (sched_random() % balance_interval); 888 tdq = TDQ_SELF(); 889 TDQ_UNLOCK(tdq); 890 sched_balance_group(cpu_top); 891 TDQ_LOCK(tdq); 892 } 893 894 /* 895 * Lock two thread queues using their address to maintain lock order. 896 */ 897 static void 898 tdq_lock_pair(struct tdq *one, struct tdq *two) 899 { 900 if (one < two) { 901 TDQ_LOCK(one); 902 TDQ_LOCK_FLAGS(two, MTX_DUPOK); 903 } else { 904 TDQ_LOCK(two); 905 TDQ_LOCK_FLAGS(one, MTX_DUPOK); 906 } 907 } 908 909 /* 910 * Unlock two thread queues. Order is not important here. 911 */ 912 static void 913 tdq_unlock_pair(struct tdq *one, struct tdq *two) 914 { 915 TDQ_UNLOCK(one); 916 TDQ_UNLOCK(two); 917 } 918 919 /* 920 * Transfer load between two imbalanced thread queues. 921 */ 922 static int 923 sched_balance_pair(struct tdq *high, struct tdq *low) 924 { 925 int moved; 926 int cpu; 927 928 tdq_lock_pair(high, low); 929 moved = 0; 930 /* 931 * Determine what the imbalance is and then adjust that to how many 932 * threads we actually have to give up (transferable). 933 */ 934 if (high->tdq_transferable != 0 && high->tdq_load > low->tdq_load && 935 (moved = tdq_move(high, low)) > 0) { 936 /* 937 * In case the target isn't the current cpu IPI it to force a 938 * reschedule with the new workload. 939 */ 940 cpu = TDQ_ID(low); 941 if (cpu != PCPU_GET(cpuid)) 942 ipi_cpu(cpu, IPI_PREEMPT); 943 } 944 tdq_unlock_pair(high, low); 945 return (moved); 946 } 947 948 /* 949 * Move a thread from one thread queue to another. 950 */ 951 static int 952 tdq_move(struct tdq *from, struct tdq *to) 953 { 954 struct td_sched *ts; 955 struct thread *td; 956 struct tdq *tdq; 957 int cpu; 958 959 TDQ_LOCK_ASSERT(from, MA_OWNED); 960 TDQ_LOCK_ASSERT(to, MA_OWNED); 961 962 tdq = from; 963 cpu = TDQ_ID(to); 964 td = tdq_steal(tdq, cpu); 965 if (td == NULL) 966 return (0); 967 ts = td->td_sched; 968 /* 969 * Although the run queue is locked the thread may be blocked. Lock 970 * it to clear this and acquire the run-queue lock. 971 */ 972 thread_lock(td); 973 /* Drop recursive lock on from acquired via thread_lock(). */ 974 TDQ_UNLOCK(from); 975 sched_rem(td); 976 ts->ts_cpu = cpu; 977 td->td_lock = TDQ_LOCKPTR(to); 978 tdq_add(to, td, SRQ_YIELDING); 979 return (1); 980 } 981 982 /* 983 * This tdq has idled. Try to steal a thread from another cpu and switch 984 * to it. 985 */ 986 static int 987 tdq_idled(struct tdq *tdq) 988 { 989 struct cpu_group *cg; 990 struct tdq *steal; 991 cpuset_t mask; 992 int thresh; 993 int cpu; 994 995 if (smp_started == 0 || steal_idle == 0) 996 return (1); 997 CPU_FILL(&mask); 998 CPU_CLR(PCPU_GET(cpuid), &mask); 999 /* We don't want to be preempted while we're iterating. */ 1000 spinlock_enter(); 1001 for (cg = tdq->tdq_cg; cg != NULL; ) { 1002 if ((cg->cg_flags & CG_FLAG_THREAD) == 0) 1003 thresh = steal_thresh; 1004 else 1005 thresh = 1; 1006 cpu = sched_highest(cg, mask, thresh); 1007 if (cpu == -1) { 1008 cg = cg->cg_parent; 1009 continue; 1010 } 1011 steal = TDQ_CPU(cpu); 1012 CPU_CLR(cpu, &mask); 1013 tdq_lock_pair(tdq, steal); 1014 if (steal->tdq_load < thresh || steal->tdq_transferable == 0) { 1015 tdq_unlock_pair(tdq, steal); 1016 continue; 1017 } 1018 /* 1019 * If a thread was added while interrupts were disabled don't 1020 * steal one here. If we fail to acquire one due to affinity 1021 * restrictions loop again with this cpu removed from the 1022 * set. 1023 */ 1024 if (tdq->tdq_load == 0 && tdq_move(steal, tdq) == 0) { 1025 tdq_unlock_pair(tdq, steal); 1026 continue; 1027 } 1028 spinlock_exit(); 1029 TDQ_UNLOCK(steal); 1030 mi_switch(SW_VOL | SWT_IDLE, NULL); 1031 thread_unlock(curthread); 1032 1033 return (0); 1034 } 1035 spinlock_exit(); 1036 return (1); 1037 } 1038 1039 /* 1040 * Notify a remote cpu of new work. Sends an IPI if criteria are met. 1041 */ 1042 static void 1043 tdq_notify(struct tdq *tdq, struct thread *td) 1044 { 1045 struct thread *ctd; 1046 int pri; 1047 int cpu; 1048 1049 if (tdq->tdq_ipipending) 1050 return; 1051 cpu = td->td_sched->ts_cpu; 1052 pri = td->td_priority; 1053 ctd = pcpu_find(cpu)->pc_curthread; 1054 if (!sched_shouldpreempt(pri, ctd->td_priority, 1)) 1055 return; 1056 1057 /* 1058 * Make sure that our caller's earlier update to tdq_load is 1059 * globally visible before we read tdq_cpu_idle. Idle thread 1060 * accesses both of them without locks, and the order is important. 1061 */ 1062 mb(); 1063 1064 if (TD_IS_IDLETHREAD(ctd)) { 1065 /* 1066 * If the MD code has an idle wakeup routine try that before 1067 * falling back to IPI. 1068 */ 1069 if (!tdq->tdq_cpu_idle || cpu_idle_wakeup(cpu)) 1070 return; 1071 } 1072 tdq->tdq_ipipending = 1; 1073 ipi_cpu(cpu, IPI_PREEMPT); 1074 } 1075 1076 /* 1077 * Steals load from a timeshare queue. Honors the rotating queue head 1078 * index. 1079 */ 1080 static struct thread * 1081 runq_steal_from(struct runq *rq, int cpu, u_char start) 1082 { 1083 struct rqbits *rqb; 1084 struct rqhead *rqh; 1085 struct thread *td, *first; 1086 int bit; 1087 int i; 1088 1089 rqb = &rq->rq_status; 1090 bit = start & (RQB_BPW -1); 1091 first = NULL; 1092 again: 1093 for (i = RQB_WORD(start); i < RQB_LEN; bit = 0, i++) { 1094 if (rqb->rqb_bits[i] == 0) 1095 continue; 1096 if (bit == 0) 1097 bit = RQB_FFS(rqb->rqb_bits[i]); 1098 for (; bit < RQB_BPW; bit++) { 1099 if ((rqb->rqb_bits[i] & (1ul << bit)) == 0) 1100 continue; 1101 rqh = &rq->rq_queues[bit + (i << RQB_L2BPW)]; 1102 TAILQ_FOREACH(td, rqh, td_runq) { 1103 if (first && THREAD_CAN_MIGRATE(td) && 1104 THREAD_CAN_SCHED(td, cpu)) 1105 return (td); 1106 first = td; 1107 } 1108 } 1109 } 1110 if (start != 0) { 1111 start = 0; 1112 goto again; 1113 } 1114 1115 if (first && THREAD_CAN_MIGRATE(first) && 1116 THREAD_CAN_SCHED(first, cpu)) 1117 return (first); 1118 return (NULL); 1119 } 1120 1121 /* 1122 * Steals load from a standard linear queue. 1123 */ 1124 static struct thread * 1125 runq_steal(struct runq *rq, int cpu) 1126 { 1127 struct rqhead *rqh; 1128 struct rqbits *rqb; 1129 struct thread *td; 1130 int word; 1131 int bit; 1132 1133 rqb = &rq->rq_status; 1134 for (word = 0; word < RQB_LEN; word++) { 1135 if (rqb->rqb_bits[word] == 0) 1136 continue; 1137 for (bit = 0; bit < RQB_BPW; bit++) { 1138 if ((rqb->rqb_bits[word] & (1ul << bit)) == 0) 1139 continue; 1140 rqh = &rq->rq_queues[bit + (word << RQB_L2BPW)]; 1141 TAILQ_FOREACH(td, rqh, td_runq) 1142 if (THREAD_CAN_MIGRATE(td) && 1143 THREAD_CAN_SCHED(td, cpu)) 1144 return (td); 1145 } 1146 } 1147 return (NULL); 1148 } 1149 1150 /* 1151 * Attempt to steal a thread in priority order from a thread queue. 1152 */ 1153 static struct thread * 1154 tdq_steal(struct tdq *tdq, int cpu) 1155 { 1156 struct thread *td; 1157 1158 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1159 if ((td = runq_steal(&tdq->tdq_realtime, cpu)) != NULL) 1160 return (td); 1161 if ((td = runq_steal_from(&tdq->tdq_timeshare, 1162 cpu, tdq->tdq_ridx)) != NULL) 1163 return (td); 1164 return (runq_steal(&tdq->tdq_idle, cpu)); 1165 } 1166 1167 /* 1168 * Sets the thread lock and ts_cpu to match the requested cpu. Unlocks the 1169 * current lock and returns with the assigned queue locked. 1170 */ 1171 static inline struct tdq * 1172 sched_setcpu(struct thread *td, int cpu, int flags) 1173 { 1174 1175 struct tdq *tdq; 1176 1177 THREAD_LOCK_ASSERT(td, MA_OWNED); 1178 tdq = TDQ_CPU(cpu); 1179 td->td_sched->ts_cpu = cpu; 1180 /* 1181 * If the lock matches just return the queue. 1182 */ 1183 if (td->td_lock == TDQ_LOCKPTR(tdq)) 1184 return (tdq); 1185 #ifdef notyet 1186 /* 1187 * If the thread isn't running its lockptr is a 1188 * turnstile or a sleepqueue. We can just lock_set without 1189 * blocking. 1190 */ 1191 if (TD_CAN_RUN(td)) { 1192 TDQ_LOCK(tdq); 1193 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 1194 return (tdq); 1195 } 1196 #endif 1197 /* 1198 * The hard case, migration, we need to block the thread first to 1199 * prevent order reversals with other cpus locks. 1200 */ 1201 spinlock_enter(); 1202 thread_lock_block(td); 1203 TDQ_LOCK(tdq); 1204 thread_lock_unblock(td, TDQ_LOCKPTR(tdq)); 1205 spinlock_exit(); 1206 return (tdq); 1207 } 1208 1209 SCHED_STAT_DEFINE(pickcpu_intrbind, "Soft interrupt binding"); 1210 SCHED_STAT_DEFINE(pickcpu_idle_affinity, "Picked idle cpu based on affinity"); 1211 SCHED_STAT_DEFINE(pickcpu_affinity, "Picked cpu based on affinity"); 1212 SCHED_STAT_DEFINE(pickcpu_lowest, "Selected lowest load"); 1213 SCHED_STAT_DEFINE(pickcpu_local, "Migrated to current cpu"); 1214 SCHED_STAT_DEFINE(pickcpu_migration, "Selection may have caused migration"); 1215 1216 static int 1217 sched_pickcpu(struct thread *td, int flags) 1218 { 1219 struct cpu_group *cg, *ccg; 1220 struct td_sched *ts; 1221 struct tdq *tdq; 1222 cpuset_t mask; 1223 int cpu, pri, self; 1224 1225 self = PCPU_GET(cpuid); 1226 ts = td->td_sched; 1227 if (smp_started == 0) 1228 return (self); 1229 /* 1230 * Don't migrate a running thread from sched_switch(). 1231 */ 1232 if ((flags & SRQ_OURSELF) || !THREAD_CAN_MIGRATE(td)) 1233 return (ts->ts_cpu); 1234 /* 1235 * Prefer to run interrupt threads on the processors that generate 1236 * the interrupt. 1237 */ 1238 pri = td->td_priority; 1239 if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_SCHED(td, self) && 1240 curthread->td_intr_nesting_level && ts->ts_cpu != self) { 1241 SCHED_STAT_INC(pickcpu_intrbind); 1242 ts->ts_cpu = self; 1243 if (TDQ_CPU(self)->tdq_lowpri > pri) { 1244 SCHED_STAT_INC(pickcpu_affinity); 1245 return (ts->ts_cpu); 1246 } 1247 } 1248 /* 1249 * If the thread can run on the last cpu and the affinity has not 1250 * expired or it is idle run it there. 1251 */ 1252 tdq = TDQ_CPU(ts->ts_cpu); 1253 cg = tdq->tdq_cg; 1254 if (THREAD_CAN_SCHED(td, ts->ts_cpu) && 1255 tdq->tdq_lowpri >= PRI_MIN_IDLE && 1256 SCHED_AFFINITY(ts, CG_SHARE_L2)) { 1257 if (cg->cg_flags & CG_FLAG_THREAD) { 1258 CPUSET_FOREACH(cpu, cg->cg_mask) { 1259 if (TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE) 1260 break; 1261 } 1262 } else 1263 cpu = INT_MAX; 1264 if (cpu > mp_maxid) { 1265 SCHED_STAT_INC(pickcpu_idle_affinity); 1266 return (ts->ts_cpu); 1267 } 1268 } 1269 /* 1270 * Search for the last level cache CPU group in the tree. 1271 * Skip caches with expired affinity time and SMT groups. 1272 * Affinity to higher level caches will be handled less aggressively. 1273 */ 1274 for (ccg = NULL; cg != NULL; cg = cg->cg_parent) { 1275 if (cg->cg_flags & CG_FLAG_THREAD) 1276 continue; 1277 if (!SCHED_AFFINITY(ts, cg->cg_level)) 1278 continue; 1279 ccg = cg; 1280 } 1281 if (ccg != NULL) 1282 cg = ccg; 1283 cpu = -1; 1284 /* Search the group for the less loaded idle CPU we can run now. */ 1285 mask = td->td_cpuset->cs_mask; 1286 if (cg != NULL && cg != cpu_top && 1287 CPU_CMP(&cg->cg_mask, &cpu_top->cg_mask) != 0) 1288 cpu = sched_lowest(cg, mask, max(pri, PRI_MAX_TIMESHARE), 1289 INT_MAX, ts->ts_cpu); 1290 /* Search globally for the less loaded CPU we can run now. */ 1291 if (cpu == -1) 1292 cpu = sched_lowest(cpu_top, mask, pri, INT_MAX, ts->ts_cpu); 1293 /* Search globally for the less loaded CPU. */ 1294 if (cpu == -1) 1295 cpu = sched_lowest(cpu_top, mask, -1, INT_MAX, ts->ts_cpu); 1296 KASSERT(cpu != -1, ("sched_pickcpu: Failed to find a cpu.")); 1297 /* 1298 * Compare the lowest loaded cpu to current cpu. 1299 */ 1300 if (THREAD_CAN_SCHED(td, self) && TDQ_CPU(self)->tdq_lowpri > pri && 1301 TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE && 1302 TDQ_CPU(self)->tdq_load <= TDQ_CPU(cpu)->tdq_load + 1) { 1303 SCHED_STAT_INC(pickcpu_local); 1304 cpu = self; 1305 } else 1306 SCHED_STAT_INC(pickcpu_lowest); 1307 if (cpu != ts->ts_cpu) 1308 SCHED_STAT_INC(pickcpu_migration); 1309 return (cpu); 1310 } 1311 #endif 1312 1313 /* 1314 * Pick the highest priority task we have and return it. 1315 */ 1316 static struct thread * 1317 tdq_choose(struct tdq *tdq) 1318 { 1319 struct thread *td; 1320 1321 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1322 td = runq_choose(&tdq->tdq_realtime); 1323 if (td != NULL) 1324 return (td); 1325 td = runq_choose_from(&tdq->tdq_timeshare, tdq->tdq_ridx); 1326 if (td != NULL) { 1327 KASSERT(td->td_priority >= PRI_MIN_BATCH, 1328 ("tdq_choose: Invalid priority on timeshare queue %d", 1329 td->td_priority)); 1330 return (td); 1331 } 1332 td = runq_choose(&tdq->tdq_idle); 1333 if (td != NULL) { 1334 KASSERT(td->td_priority >= PRI_MIN_IDLE, 1335 ("tdq_choose: Invalid priority on idle queue %d", 1336 td->td_priority)); 1337 return (td); 1338 } 1339 1340 return (NULL); 1341 } 1342 1343 /* 1344 * Initialize a thread queue. 1345 */ 1346 static void 1347 tdq_setup(struct tdq *tdq) 1348 { 1349 1350 if (bootverbose) 1351 printf("ULE: setup cpu %d\n", TDQ_ID(tdq)); 1352 runq_init(&tdq->tdq_realtime); 1353 runq_init(&tdq->tdq_timeshare); 1354 runq_init(&tdq->tdq_idle); 1355 snprintf(tdq->tdq_name, sizeof(tdq->tdq_name), 1356 "sched lock %d", (int)TDQ_ID(tdq)); 1357 mtx_init(&tdq->tdq_lock, tdq->tdq_name, "sched lock", 1358 MTX_SPIN | MTX_RECURSE); 1359 #ifdef KTR 1360 snprintf(tdq->tdq_loadname, sizeof(tdq->tdq_loadname), 1361 "CPU %d load", (int)TDQ_ID(tdq)); 1362 #endif 1363 } 1364 1365 #ifdef SMP 1366 static void 1367 sched_setup_smp(void) 1368 { 1369 struct tdq *tdq; 1370 int i; 1371 1372 cpu_top = smp_topo(); 1373 CPU_FOREACH(i) { 1374 tdq = TDQ_CPU(i); 1375 tdq_setup(tdq); 1376 tdq->tdq_cg = smp_topo_find(cpu_top, i); 1377 if (tdq->tdq_cg == NULL) 1378 panic("Can't find cpu group for %d\n", i); 1379 } 1380 balance_tdq = TDQ_SELF(); 1381 sched_balance(); 1382 } 1383 #endif 1384 1385 /* 1386 * Setup the thread queues and initialize the topology based on MD 1387 * information. 1388 */ 1389 static void 1390 sched_setup(void *dummy) 1391 { 1392 struct tdq *tdq; 1393 1394 tdq = TDQ_SELF(); 1395 #ifdef SMP 1396 sched_setup_smp(); 1397 #else 1398 tdq_setup(tdq); 1399 #endif 1400 1401 /* Add thread0's load since it's running. */ 1402 TDQ_LOCK(tdq); 1403 thread0.td_lock = TDQ_LOCKPTR(TDQ_SELF()); 1404 tdq_load_add(tdq, &thread0); 1405 tdq->tdq_lowpri = thread0.td_priority; 1406 TDQ_UNLOCK(tdq); 1407 } 1408 1409 /* 1410 * This routine determines time constants after stathz and hz are setup. 1411 */ 1412 /* ARGSUSED */ 1413 static void 1414 sched_initticks(void *dummy) 1415 { 1416 int incr; 1417 1418 realstathz = stathz ? stathz : hz; 1419 sched_slice = realstathz / SCHED_SLICE_DEFAULT_DIVISOR; 1420 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 1421 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 1422 realstathz); 1423 1424 /* 1425 * tickincr is shifted out by 10 to avoid rounding errors due to 1426 * hz not being evenly divisible by stathz on all platforms. 1427 */ 1428 incr = (hz << SCHED_TICK_SHIFT) / realstathz; 1429 /* 1430 * This does not work for values of stathz that are more than 1431 * 1 << SCHED_TICK_SHIFT * hz. In practice this does not happen. 1432 */ 1433 if (incr == 0) 1434 incr = 1; 1435 tickincr = incr; 1436 #ifdef SMP 1437 /* 1438 * Set the default balance interval now that we know 1439 * what realstathz is. 1440 */ 1441 balance_interval = realstathz; 1442 affinity = SCHED_AFFINITY_DEFAULT; 1443 #endif 1444 if (sched_idlespinthresh < 0) 1445 sched_idlespinthresh = 2 * max(10000, 6 * hz) / realstathz; 1446 } 1447 1448 1449 /* 1450 * This is the core of the interactivity algorithm. Determines a score based 1451 * on past behavior. It is the ratio of sleep time to run time scaled to 1452 * a [0, 100] integer. This is the voluntary sleep time of a process, which 1453 * differs from the cpu usage because it does not account for time spent 1454 * waiting on a run-queue. Would be prettier if we had floating point. 1455 */ 1456 static int 1457 sched_interact_score(struct thread *td) 1458 { 1459 struct td_sched *ts; 1460 int div; 1461 1462 ts = td->td_sched; 1463 /* 1464 * The score is only needed if this is likely to be an interactive 1465 * task. Don't go through the expense of computing it if there's 1466 * no chance. 1467 */ 1468 if (sched_interact <= SCHED_INTERACT_HALF && 1469 ts->ts_runtime >= ts->ts_slptime) 1470 return (SCHED_INTERACT_HALF); 1471 1472 if (ts->ts_runtime > ts->ts_slptime) { 1473 div = max(1, ts->ts_runtime / SCHED_INTERACT_HALF); 1474 return (SCHED_INTERACT_HALF + 1475 (SCHED_INTERACT_HALF - (ts->ts_slptime / div))); 1476 } 1477 if (ts->ts_slptime > ts->ts_runtime) { 1478 div = max(1, ts->ts_slptime / SCHED_INTERACT_HALF); 1479 return (ts->ts_runtime / div); 1480 } 1481 /* runtime == slptime */ 1482 if (ts->ts_runtime) 1483 return (SCHED_INTERACT_HALF); 1484 1485 /* 1486 * This can happen if slptime and runtime are 0. 1487 */ 1488 return (0); 1489 1490 } 1491 1492 /* 1493 * Scale the scheduling priority according to the "interactivity" of this 1494 * process. 1495 */ 1496 static void 1497 sched_priority(struct thread *td) 1498 { 1499 int score; 1500 int pri; 1501 1502 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 1503 return; 1504 /* 1505 * If the score is interactive we place the thread in the realtime 1506 * queue with a priority that is less than kernel and interrupt 1507 * priorities. These threads are not subject to nice restrictions. 1508 * 1509 * Scores greater than this are placed on the normal timeshare queue 1510 * where the priority is partially decided by the most recent cpu 1511 * utilization and the rest is decided by nice value. 1512 * 1513 * The nice value of the process has a linear effect on the calculated 1514 * score. Negative nice values make it easier for a thread to be 1515 * considered interactive. 1516 */ 1517 score = imax(0, sched_interact_score(td) + td->td_proc->p_nice); 1518 if (score < sched_interact) { 1519 pri = PRI_MIN_INTERACT; 1520 pri += ((PRI_MAX_INTERACT - PRI_MIN_INTERACT + 1) / 1521 sched_interact) * score; 1522 KASSERT(pri >= PRI_MIN_INTERACT && pri <= PRI_MAX_INTERACT, 1523 ("sched_priority: invalid interactive priority %d score %d", 1524 pri, score)); 1525 } else { 1526 pri = SCHED_PRI_MIN; 1527 if (td->td_sched->ts_ticks) 1528 pri += min(SCHED_PRI_TICKS(td->td_sched), 1529 SCHED_PRI_RANGE - 1); 1530 pri += SCHED_PRI_NICE(td->td_proc->p_nice); 1531 KASSERT(pri >= PRI_MIN_BATCH && pri <= PRI_MAX_BATCH, 1532 ("sched_priority: invalid priority %d: nice %d, " 1533 "ticks %d ftick %d ltick %d tick pri %d", 1534 pri, td->td_proc->p_nice, td->td_sched->ts_ticks, 1535 td->td_sched->ts_ftick, td->td_sched->ts_ltick, 1536 SCHED_PRI_TICKS(td->td_sched))); 1537 } 1538 sched_user_prio(td, pri); 1539 1540 return; 1541 } 1542 1543 /* 1544 * This routine enforces a maximum limit on the amount of scheduling history 1545 * kept. It is called after either the slptime or runtime is adjusted. This 1546 * function is ugly due to integer math. 1547 */ 1548 static void 1549 sched_interact_update(struct thread *td) 1550 { 1551 struct td_sched *ts; 1552 u_int sum; 1553 1554 ts = td->td_sched; 1555 sum = ts->ts_runtime + ts->ts_slptime; 1556 if (sum < SCHED_SLP_RUN_MAX) 1557 return; 1558 /* 1559 * This only happens from two places: 1560 * 1) We have added an unusual amount of run time from fork_exit. 1561 * 2) We have added an unusual amount of sleep time from sched_sleep(). 1562 */ 1563 if (sum > SCHED_SLP_RUN_MAX * 2) { 1564 if (ts->ts_runtime > ts->ts_slptime) { 1565 ts->ts_runtime = SCHED_SLP_RUN_MAX; 1566 ts->ts_slptime = 1; 1567 } else { 1568 ts->ts_slptime = SCHED_SLP_RUN_MAX; 1569 ts->ts_runtime = 1; 1570 } 1571 return; 1572 } 1573 /* 1574 * If we have exceeded by more than 1/5th then the algorithm below 1575 * will not bring us back into range. Dividing by two here forces 1576 * us into the range of [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX] 1577 */ 1578 if (sum > (SCHED_SLP_RUN_MAX / 5) * 6) { 1579 ts->ts_runtime /= 2; 1580 ts->ts_slptime /= 2; 1581 return; 1582 } 1583 ts->ts_runtime = (ts->ts_runtime / 5) * 4; 1584 ts->ts_slptime = (ts->ts_slptime / 5) * 4; 1585 } 1586 1587 /* 1588 * Scale back the interactivity history when a child thread is created. The 1589 * history is inherited from the parent but the thread may behave totally 1590 * differently. For example, a shell spawning a compiler process. We want 1591 * to learn that the compiler is behaving badly very quickly. 1592 */ 1593 static void 1594 sched_interact_fork(struct thread *td) 1595 { 1596 int ratio; 1597 int sum; 1598 1599 sum = td->td_sched->ts_runtime + td->td_sched->ts_slptime; 1600 if (sum > SCHED_SLP_RUN_FORK) { 1601 ratio = sum / SCHED_SLP_RUN_FORK; 1602 td->td_sched->ts_runtime /= ratio; 1603 td->td_sched->ts_slptime /= ratio; 1604 } 1605 } 1606 1607 /* 1608 * Called from proc0_init() to setup the scheduler fields. 1609 */ 1610 void 1611 schedinit(void) 1612 { 1613 1614 /* 1615 * Set up the scheduler specific parts of proc0. 1616 */ 1617 proc0.p_sched = NULL; /* XXX */ 1618 thread0.td_sched = &td_sched0; 1619 td_sched0.ts_ltick = ticks; 1620 td_sched0.ts_ftick = ticks; 1621 td_sched0.ts_slice = 0; 1622 } 1623 1624 /* 1625 * This is only somewhat accurate since given many processes of the same 1626 * priority they will switch when their slices run out, which will be 1627 * at most sched_slice stathz ticks. 1628 */ 1629 int 1630 sched_rr_interval(void) 1631 { 1632 1633 /* Convert sched_slice from stathz to hz. */ 1634 return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz)); 1635 } 1636 1637 /* 1638 * Update the percent cpu tracking information when it is requested or 1639 * the total history exceeds the maximum. We keep a sliding history of 1640 * tick counts that slowly decays. This is less precise than the 4BSD 1641 * mechanism since it happens with less regular and frequent events. 1642 */ 1643 static void 1644 sched_pctcpu_update(struct td_sched *ts, int run) 1645 { 1646 int t = ticks; 1647 1648 if (t - ts->ts_ltick >= SCHED_TICK_TARG) { 1649 ts->ts_ticks = 0; 1650 ts->ts_ftick = t - SCHED_TICK_TARG; 1651 } else if (t - ts->ts_ftick >= SCHED_TICK_MAX) { 1652 ts->ts_ticks = (ts->ts_ticks / (ts->ts_ltick - ts->ts_ftick)) * 1653 (ts->ts_ltick - (t - SCHED_TICK_TARG)); 1654 ts->ts_ftick = t - SCHED_TICK_TARG; 1655 } 1656 if (run) 1657 ts->ts_ticks += (t - ts->ts_ltick) << SCHED_TICK_SHIFT; 1658 ts->ts_ltick = t; 1659 } 1660 1661 /* 1662 * Adjust the priority of a thread. Move it to the appropriate run-queue 1663 * if necessary. This is the back-end for several priority related 1664 * functions. 1665 */ 1666 static void 1667 sched_thread_priority(struct thread *td, u_char prio) 1668 { 1669 struct td_sched *ts; 1670 struct tdq *tdq; 1671 int oldpri; 1672 1673 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "prio", 1674 "prio:%d", td->td_priority, "new prio:%d", prio, 1675 KTR_ATTR_LINKED, sched_tdname(curthread)); 1676 SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio); 1677 if (td != curthread && prio < td->td_priority) { 1678 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread), 1679 "lend prio", "prio:%d", td->td_priority, "new prio:%d", 1680 prio, KTR_ATTR_LINKED, sched_tdname(td)); 1681 SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio, 1682 curthread); 1683 } 1684 ts = td->td_sched; 1685 THREAD_LOCK_ASSERT(td, MA_OWNED); 1686 if (td->td_priority == prio) 1687 return; 1688 /* 1689 * If the priority has been elevated due to priority 1690 * propagation, we may have to move ourselves to a new 1691 * queue. This could be optimized to not re-add in some 1692 * cases. 1693 */ 1694 if (TD_ON_RUNQ(td) && prio < td->td_priority) { 1695 sched_rem(td); 1696 td->td_priority = prio; 1697 sched_add(td, SRQ_BORROWING); 1698 return; 1699 } 1700 /* 1701 * If the thread is currently running we may have to adjust the lowpri 1702 * information so other cpus are aware of our current priority. 1703 */ 1704 if (TD_IS_RUNNING(td)) { 1705 tdq = TDQ_CPU(ts->ts_cpu); 1706 oldpri = td->td_priority; 1707 td->td_priority = prio; 1708 if (prio < tdq->tdq_lowpri) 1709 tdq->tdq_lowpri = prio; 1710 else if (tdq->tdq_lowpri == oldpri) 1711 tdq_setlowpri(tdq, td); 1712 return; 1713 } 1714 td->td_priority = prio; 1715 } 1716 1717 /* 1718 * Update a thread's priority when it is lent another thread's 1719 * priority. 1720 */ 1721 void 1722 sched_lend_prio(struct thread *td, u_char prio) 1723 { 1724 1725 td->td_flags |= TDF_BORROWING; 1726 sched_thread_priority(td, prio); 1727 } 1728 1729 /* 1730 * Restore a thread's priority when priority propagation is 1731 * over. The prio argument is the minimum priority the thread 1732 * needs to have to satisfy other possible priority lending 1733 * requests. If the thread's regular priority is less 1734 * important than prio, the thread will keep a priority boost 1735 * of prio. 1736 */ 1737 void 1738 sched_unlend_prio(struct thread *td, u_char prio) 1739 { 1740 u_char base_pri; 1741 1742 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 1743 td->td_base_pri <= PRI_MAX_TIMESHARE) 1744 base_pri = td->td_user_pri; 1745 else 1746 base_pri = td->td_base_pri; 1747 if (prio >= base_pri) { 1748 td->td_flags &= ~TDF_BORROWING; 1749 sched_thread_priority(td, base_pri); 1750 } else 1751 sched_lend_prio(td, prio); 1752 } 1753 1754 /* 1755 * Standard entry for setting the priority to an absolute value. 1756 */ 1757 void 1758 sched_prio(struct thread *td, u_char prio) 1759 { 1760 u_char oldprio; 1761 1762 /* First, update the base priority. */ 1763 td->td_base_pri = prio; 1764 1765 /* 1766 * If the thread is borrowing another thread's priority, don't 1767 * ever lower the priority. 1768 */ 1769 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 1770 return; 1771 1772 /* Change the real priority. */ 1773 oldprio = td->td_priority; 1774 sched_thread_priority(td, prio); 1775 1776 /* 1777 * If the thread is on a turnstile, then let the turnstile update 1778 * its state. 1779 */ 1780 if (TD_ON_LOCK(td) && oldprio != prio) 1781 turnstile_adjust(td, oldprio); 1782 } 1783 1784 /* 1785 * Set the base user priority, does not effect current running priority. 1786 */ 1787 void 1788 sched_user_prio(struct thread *td, u_char prio) 1789 { 1790 1791 td->td_base_user_pri = prio; 1792 if (td->td_lend_user_pri <= prio) 1793 return; 1794 td->td_user_pri = prio; 1795 } 1796 1797 void 1798 sched_lend_user_prio(struct thread *td, u_char prio) 1799 { 1800 1801 THREAD_LOCK_ASSERT(td, MA_OWNED); 1802 td->td_lend_user_pri = prio; 1803 td->td_user_pri = min(prio, td->td_base_user_pri); 1804 if (td->td_priority > td->td_user_pri) 1805 sched_prio(td, td->td_user_pri); 1806 else if (td->td_priority != td->td_user_pri) 1807 td->td_flags |= TDF_NEEDRESCHED; 1808 } 1809 1810 /* 1811 * Handle migration from sched_switch(). This happens only for 1812 * cpu binding. 1813 */ 1814 static struct mtx * 1815 sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags) 1816 { 1817 struct tdq *tdn; 1818 1819 tdn = TDQ_CPU(td->td_sched->ts_cpu); 1820 #ifdef SMP 1821 tdq_load_rem(tdq, td); 1822 /* 1823 * Do the lock dance required to avoid LOR. We grab an extra 1824 * spinlock nesting to prevent preemption while we're 1825 * not holding either run-queue lock. 1826 */ 1827 spinlock_enter(); 1828 thread_lock_block(td); /* This releases the lock on tdq. */ 1829 1830 /* 1831 * Acquire both run-queue locks before placing the thread on the new 1832 * run-queue to avoid deadlocks created by placing a thread with a 1833 * blocked lock on the run-queue of a remote processor. The deadlock 1834 * occurs when a third processor attempts to lock the two queues in 1835 * question while the target processor is spinning with its own 1836 * run-queue lock held while waiting for the blocked lock to clear. 1837 */ 1838 tdq_lock_pair(tdn, tdq); 1839 tdq_add(tdn, td, flags); 1840 tdq_notify(tdn, td); 1841 TDQ_UNLOCK(tdn); 1842 spinlock_exit(); 1843 #endif 1844 return (TDQ_LOCKPTR(tdn)); 1845 } 1846 1847 /* 1848 * Variadic version of thread_lock_unblock() that does not assume td_lock 1849 * is blocked. 1850 */ 1851 static inline void 1852 thread_unblock_switch(struct thread *td, struct mtx *mtx) 1853 { 1854 atomic_store_rel_ptr((volatile uintptr_t *)&td->td_lock, 1855 (uintptr_t)mtx); 1856 } 1857 1858 /* 1859 * Switch threads. This function has to handle threads coming in while 1860 * blocked for some reason, running, or idle. It also must deal with 1861 * migrating a thread from one queue to another as running threads may 1862 * be assigned elsewhere via binding. 1863 */ 1864 void 1865 sched_switch(struct thread *td, struct thread *newtd, int flags) 1866 { 1867 struct tdq *tdq; 1868 struct td_sched *ts; 1869 struct mtx *mtx; 1870 int srqflag; 1871 int cpuid, preempted; 1872 1873 THREAD_LOCK_ASSERT(td, MA_OWNED); 1874 KASSERT(newtd == NULL, ("sched_switch: Unsupported newtd argument")); 1875 1876 cpuid = PCPU_GET(cpuid); 1877 tdq = TDQ_CPU(cpuid); 1878 ts = td->td_sched; 1879 mtx = td->td_lock; 1880 sched_pctcpu_update(ts, 1); 1881 ts->ts_rltick = ticks; 1882 td->td_lastcpu = td->td_oncpu; 1883 td->td_oncpu = NOCPU; 1884 preempted = !((td->td_flags & TDF_SLICEEND) || 1885 (flags & SWT_RELINQUISH)); 1886 td->td_flags &= ~(TDF_NEEDRESCHED | TDF_SLICEEND); 1887 td->td_owepreempt = 0; 1888 if (!TD_IS_IDLETHREAD(td)) 1889 tdq->tdq_switchcnt++; 1890 /* 1891 * The lock pointer in an idle thread should never change. Reset it 1892 * to CAN_RUN as well. 1893 */ 1894 if (TD_IS_IDLETHREAD(td)) { 1895 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1896 TD_SET_CAN_RUN(td); 1897 } else if (TD_IS_RUNNING(td)) { 1898 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1899 srqflag = preempted ? 1900 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 1901 SRQ_OURSELF|SRQ_YIELDING; 1902 #ifdef SMP 1903 if (THREAD_CAN_MIGRATE(td) && !THREAD_CAN_SCHED(td, ts->ts_cpu)) 1904 ts->ts_cpu = sched_pickcpu(td, 0); 1905 #endif 1906 if (ts->ts_cpu == cpuid) 1907 tdq_runq_add(tdq, td, srqflag); 1908 else { 1909 KASSERT(THREAD_CAN_MIGRATE(td) || 1910 (ts->ts_flags & TSF_BOUND) != 0, 1911 ("Thread %p shouldn't migrate", td)); 1912 mtx = sched_switch_migrate(tdq, td, srqflag); 1913 } 1914 } else { 1915 /* This thread must be going to sleep. */ 1916 TDQ_LOCK(tdq); 1917 mtx = thread_lock_block(td); 1918 tdq_load_rem(tdq, td); 1919 } 1920 /* 1921 * We enter here with the thread blocked and assigned to the 1922 * appropriate cpu run-queue or sleep-queue and with the current 1923 * thread-queue locked. 1924 */ 1925 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 1926 newtd = choosethread(); 1927 /* 1928 * Call the MD code to switch contexts if necessary. 1929 */ 1930 if (td != newtd) { 1931 #ifdef HWPMC_HOOKS 1932 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1933 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 1934 #endif 1935 SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc); 1936 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 1937 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 1938 sched_pctcpu_update(newtd->td_sched, 0); 1939 1940 #ifdef KDTRACE_HOOKS 1941 /* 1942 * If DTrace has set the active vtime enum to anything 1943 * other than INACTIVE (0), then it should have set the 1944 * function to call. 1945 */ 1946 if (dtrace_vtime_active) 1947 (*dtrace_vtime_switch_func)(newtd); 1948 #endif 1949 1950 cpu_switch(td, newtd, mtx); 1951 /* 1952 * We may return from cpu_switch on a different cpu. However, 1953 * we always return with td_lock pointing to the current cpu's 1954 * run queue lock. 1955 */ 1956 cpuid = PCPU_GET(cpuid); 1957 tdq = TDQ_CPU(cpuid); 1958 lock_profile_obtain_lock_success( 1959 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 1960 1961 SDT_PROBE0(sched, , , on__cpu); 1962 #ifdef HWPMC_HOOKS 1963 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1964 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 1965 #endif 1966 } else { 1967 thread_unblock_switch(td, mtx); 1968 SDT_PROBE0(sched, , , remain__cpu); 1969 } 1970 /* 1971 * Assert that all went well and return. 1972 */ 1973 TDQ_LOCK_ASSERT(tdq, MA_OWNED|MA_NOTRECURSED); 1974 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1975 td->td_oncpu = cpuid; 1976 } 1977 1978 /* 1979 * Adjust thread priorities as a result of a nice request. 1980 */ 1981 void 1982 sched_nice(struct proc *p, int nice) 1983 { 1984 struct thread *td; 1985 1986 PROC_LOCK_ASSERT(p, MA_OWNED); 1987 1988 p->p_nice = nice; 1989 FOREACH_THREAD_IN_PROC(p, td) { 1990 thread_lock(td); 1991 sched_priority(td); 1992 sched_prio(td, td->td_base_user_pri); 1993 thread_unlock(td); 1994 } 1995 } 1996 1997 /* 1998 * Record the sleep time for the interactivity scorer. 1999 */ 2000 void 2001 sched_sleep(struct thread *td, int prio) 2002 { 2003 2004 THREAD_LOCK_ASSERT(td, MA_OWNED); 2005 2006 td->td_slptick = ticks; 2007 if (TD_IS_SUSPENDED(td) || prio >= PSOCK) 2008 td->td_flags |= TDF_CANSWAP; 2009 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 2010 return; 2011 if (static_boost == 1 && prio) 2012 sched_prio(td, prio); 2013 else if (static_boost && td->td_priority > static_boost) 2014 sched_prio(td, static_boost); 2015 } 2016 2017 /* 2018 * Schedule a thread to resume execution and record how long it voluntarily 2019 * slept. We also update the pctcpu, interactivity, and priority. 2020 */ 2021 void 2022 sched_wakeup(struct thread *td) 2023 { 2024 struct td_sched *ts; 2025 int slptick; 2026 2027 THREAD_LOCK_ASSERT(td, MA_OWNED); 2028 ts = td->td_sched; 2029 td->td_flags &= ~TDF_CANSWAP; 2030 /* 2031 * If we slept for more than a tick update our interactivity and 2032 * priority. 2033 */ 2034 slptick = td->td_slptick; 2035 td->td_slptick = 0; 2036 if (slptick && slptick != ticks) { 2037 ts->ts_slptime += (ticks - slptick) << SCHED_TICK_SHIFT; 2038 sched_interact_update(td); 2039 sched_pctcpu_update(ts, 0); 2040 } 2041 /* 2042 * Reset the slice value since we slept and advanced the round-robin. 2043 */ 2044 ts->ts_slice = 0; 2045 sched_add(td, SRQ_BORING); 2046 } 2047 2048 /* 2049 * Penalize the parent for creating a new child and initialize the child's 2050 * priority. 2051 */ 2052 void 2053 sched_fork(struct thread *td, struct thread *child) 2054 { 2055 THREAD_LOCK_ASSERT(td, MA_OWNED); 2056 sched_pctcpu_update(td->td_sched, 1); 2057 sched_fork_thread(td, child); 2058 /* 2059 * Penalize the parent and child for forking. 2060 */ 2061 sched_interact_fork(child); 2062 sched_priority(child); 2063 td->td_sched->ts_runtime += tickincr; 2064 sched_interact_update(td); 2065 sched_priority(td); 2066 } 2067 2068 /* 2069 * Fork a new thread, may be within the same process. 2070 */ 2071 void 2072 sched_fork_thread(struct thread *td, struct thread *child) 2073 { 2074 struct td_sched *ts; 2075 struct td_sched *ts2; 2076 struct tdq *tdq; 2077 2078 tdq = TDQ_SELF(); 2079 THREAD_LOCK_ASSERT(td, MA_OWNED); 2080 /* 2081 * Initialize child. 2082 */ 2083 ts = td->td_sched; 2084 ts2 = child->td_sched; 2085 child->td_lock = TDQ_LOCKPTR(tdq); 2086 child->td_cpuset = cpuset_ref(td->td_cpuset); 2087 ts2->ts_cpu = ts->ts_cpu; 2088 ts2->ts_flags = 0; 2089 /* 2090 * Grab our parents cpu estimation information. 2091 */ 2092 ts2->ts_ticks = ts->ts_ticks; 2093 ts2->ts_ltick = ts->ts_ltick; 2094 ts2->ts_ftick = ts->ts_ftick; 2095 /* 2096 * Do not inherit any borrowed priority from the parent. 2097 */ 2098 child->td_priority = child->td_base_pri; 2099 /* 2100 * And update interactivity score. 2101 */ 2102 ts2->ts_slptime = ts->ts_slptime; 2103 ts2->ts_runtime = ts->ts_runtime; 2104 /* Attempt to quickly learn interactivity. */ 2105 ts2->ts_slice = tdq_slice(tdq) - sched_slice_min; 2106 #ifdef KTR 2107 bzero(ts2->ts_name, sizeof(ts2->ts_name)); 2108 #endif 2109 } 2110 2111 /* 2112 * Adjust the priority class of a thread. 2113 */ 2114 void 2115 sched_class(struct thread *td, int class) 2116 { 2117 2118 THREAD_LOCK_ASSERT(td, MA_OWNED); 2119 if (td->td_pri_class == class) 2120 return; 2121 td->td_pri_class = class; 2122 } 2123 2124 /* 2125 * Return some of the child's priority and interactivity to the parent. 2126 */ 2127 void 2128 sched_exit(struct proc *p, struct thread *child) 2129 { 2130 struct thread *td; 2131 2132 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "proc exit", 2133 "prio:%d", child->td_priority); 2134 PROC_LOCK_ASSERT(p, MA_OWNED); 2135 td = FIRST_THREAD_IN_PROC(p); 2136 sched_exit_thread(td, child); 2137 } 2138 2139 /* 2140 * Penalize another thread for the time spent on this one. This helps to 2141 * worsen the priority and interactivity of processes which schedule batch 2142 * jobs such as make. This has little effect on the make process itself but 2143 * causes new processes spawned by it to receive worse scores immediately. 2144 */ 2145 void 2146 sched_exit_thread(struct thread *td, struct thread *child) 2147 { 2148 2149 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "thread exit", 2150 "prio:%d", child->td_priority); 2151 /* 2152 * Give the child's runtime to the parent without returning the 2153 * sleep time as a penalty to the parent. This causes shells that 2154 * launch expensive things to mark their children as expensive. 2155 */ 2156 thread_lock(td); 2157 td->td_sched->ts_runtime += child->td_sched->ts_runtime; 2158 sched_interact_update(td); 2159 sched_priority(td); 2160 thread_unlock(td); 2161 } 2162 2163 void 2164 sched_preempt(struct thread *td) 2165 { 2166 struct tdq *tdq; 2167 2168 SDT_PROBE2(sched, , , surrender, td, td->td_proc); 2169 2170 thread_lock(td); 2171 tdq = TDQ_SELF(); 2172 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2173 tdq->tdq_ipipending = 0; 2174 if (td->td_priority > tdq->tdq_lowpri) { 2175 int flags; 2176 2177 flags = SW_INVOL | SW_PREEMPT; 2178 if (td->td_critnest > 1) 2179 td->td_owepreempt = 1; 2180 else if (TD_IS_IDLETHREAD(td)) 2181 mi_switch(flags | SWT_REMOTEWAKEIDLE, NULL); 2182 else 2183 mi_switch(flags | SWT_REMOTEPREEMPT, NULL); 2184 } 2185 thread_unlock(td); 2186 } 2187 2188 /* 2189 * Fix priorities on return to user-space. Priorities may be elevated due 2190 * to static priorities in msleep() or similar. 2191 */ 2192 void 2193 sched_userret(struct thread *td) 2194 { 2195 /* 2196 * XXX we cheat slightly on the locking here to avoid locking in 2197 * the usual case. Setting td_priority here is essentially an 2198 * incomplete workaround for not setting it properly elsewhere. 2199 * Now that some interrupt handlers are threads, not setting it 2200 * properly elsewhere can clobber it in the window between setting 2201 * it here and returning to user mode, so don't waste time setting 2202 * it perfectly here. 2203 */ 2204 KASSERT((td->td_flags & TDF_BORROWING) == 0, 2205 ("thread with borrowed priority returning to userland")); 2206 if (td->td_priority != td->td_user_pri) { 2207 thread_lock(td); 2208 td->td_priority = td->td_user_pri; 2209 td->td_base_pri = td->td_user_pri; 2210 tdq_setlowpri(TDQ_SELF(), td); 2211 thread_unlock(td); 2212 } 2213 } 2214 2215 /* 2216 * Handle a stathz tick. This is really only relevant for timeshare 2217 * threads. 2218 */ 2219 void 2220 sched_clock(struct thread *td) 2221 { 2222 struct tdq *tdq; 2223 struct td_sched *ts; 2224 2225 THREAD_LOCK_ASSERT(td, MA_OWNED); 2226 tdq = TDQ_SELF(); 2227 #ifdef SMP 2228 /* 2229 * We run the long term load balancer infrequently on the first cpu. 2230 */ 2231 if (balance_tdq == tdq) { 2232 if (balance_ticks && --balance_ticks == 0) 2233 sched_balance(); 2234 } 2235 #endif 2236 /* 2237 * Save the old switch count so we have a record of the last ticks 2238 * activity. Initialize the new switch count based on our load. 2239 * If there is some activity seed it to reflect that. 2240 */ 2241 tdq->tdq_oldswitchcnt = tdq->tdq_switchcnt; 2242 tdq->tdq_switchcnt = tdq->tdq_load; 2243 /* 2244 * Advance the insert index once for each tick to ensure that all 2245 * threads get a chance to run. 2246 */ 2247 if (tdq->tdq_idx == tdq->tdq_ridx) { 2248 tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS; 2249 if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx])) 2250 tdq->tdq_ridx = tdq->tdq_idx; 2251 } 2252 ts = td->td_sched; 2253 sched_pctcpu_update(ts, 1); 2254 if (td->td_pri_class & PRI_FIFO_BIT) 2255 return; 2256 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) { 2257 /* 2258 * We used a tick; charge it to the thread so 2259 * that we can compute our interactivity. 2260 */ 2261 td->td_sched->ts_runtime += tickincr; 2262 sched_interact_update(td); 2263 sched_priority(td); 2264 } 2265 2266 /* 2267 * Force a context switch if the current thread has used up a full 2268 * time slice (default is 100ms). 2269 */ 2270 if (!TD_IS_IDLETHREAD(td) && ++ts->ts_slice >= tdq_slice(tdq)) { 2271 ts->ts_slice = 0; 2272 td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND; 2273 } 2274 } 2275 2276 /* 2277 * Called once per hz tick. 2278 */ 2279 void 2280 sched_tick(int cnt) 2281 { 2282 2283 } 2284 2285 /* 2286 * Return whether the current CPU has runnable tasks. Used for in-kernel 2287 * cooperative idle threads. 2288 */ 2289 int 2290 sched_runnable(void) 2291 { 2292 struct tdq *tdq; 2293 int load; 2294 2295 load = 1; 2296 2297 tdq = TDQ_SELF(); 2298 if ((curthread->td_flags & TDF_IDLETD) != 0) { 2299 if (tdq->tdq_load > 0) 2300 goto out; 2301 } else 2302 if (tdq->tdq_load - 1 > 0) 2303 goto out; 2304 load = 0; 2305 out: 2306 return (load); 2307 } 2308 2309 /* 2310 * Choose the highest priority thread to run. The thread is removed from 2311 * the run-queue while running however the load remains. For SMP we set 2312 * the tdq in the global idle bitmask if it idles here. 2313 */ 2314 struct thread * 2315 sched_choose(void) 2316 { 2317 struct thread *td; 2318 struct tdq *tdq; 2319 2320 tdq = TDQ_SELF(); 2321 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2322 td = tdq_choose(tdq); 2323 if (td) { 2324 tdq_runq_rem(tdq, td); 2325 tdq->tdq_lowpri = td->td_priority; 2326 return (td); 2327 } 2328 tdq->tdq_lowpri = PRI_MAX_IDLE; 2329 return (PCPU_GET(idlethread)); 2330 } 2331 2332 /* 2333 * Set owepreempt if necessary. Preemption never happens directly in ULE, 2334 * we always request it once we exit a critical section. 2335 */ 2336 static inline void 2337 sched_setpreempt(struct thread *td) 2338 { 2339 struct thread *ctd; 2340 int cpri; 2341 int pri; 2342 2343 THREAD_LOCK_ASSERT(curthread, MA_OWNED); 2344 2345 ctd = curthread; 2346 pri = td->td_priority; 2347 cpri = ctd->td_priority; 2348 if (pri < cpri) 2349 ctd->td_flags |= TDF_NEEDRESCHED; 2350 if (panicstr != NULL || pri >= cpri || cold || TD_IS_INHIBITED(ctd)) 2351 return; 2352 if (!sched_shouldpreempt(pri, cpri, 0)) 2353 return; 2354 ctd->td_owepreempt = 1; 2355 } 2356 2357 /* 2358 * Add a thread to a thread queue. Select the appropriate runq and add the 2359 * thread to it. This is the internal function called when the tdq is 2360 * predetermined. 2361 */ 2362 void 2363 tdq_add(struct tdq *tdq, struct thread *td, int flags) 2364 { 2365 2366 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2367 KASSERT((td->td_inhibitors == 0), 2368 ("sched_add: trying to run inhibited thread")); 2369 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 2370 ("sched_add: bad thread state")); 2371 KASSERT(td->td_flags & TDF_INMEM, 2372 ("sched_add: thread swapped out")); 2373 2374 if (td->td_priority < tdq->tdq_lowpri) 2375 tdq->tdq_lowpri = td->td_priority; 2376 tdq_runq_add(tdq, td, flags); 2377 tdq_load_add(tdq, td); 2378 } 2379 2380 /* 2381 * Select the target thread queue and add a thread to it. Request 2382 * preemption or IPI a remote processor if required. 2383 */ 2384 void 2385 sched_add(struct thread *td, int flags) 2386 { 2387 struct tdq *tdq; 2388 #ifdef SMP 2389 int cpu; 2390 #endif 2391 2392 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 2393 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 2394 sched_tdname(curthread)); 2395 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 2396 KTR_ATTR_LINKED, sched_tdname(td)); 2397 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 2398 flags & SRQ_PREEMPTED); 2399 THREAD_LOCK_ASSERT(td, MA_OWNED); 2400 /* 2401 * Recalculate the priority before we select the target cpu or 2402 * run-queue. 2403 */ 2404 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 2405 sched_priority(td); 2406 #ifdef SMP 2407 /* 2408 * Pick the destination cpu and if it isn't ours transfer to the 2409 * target cpu. 2410 */ 2411 cpu = sched_pickcpu(td, flags); 2412 tdq = sched_setcpu(td, cpu, flags); 2413 tdq_add(tdq, td, flags); 2414 if (cpu != PCPU_GET(cpuid)) { 2415 tdq_notify(tdq, td); 2416 return; 2417 } 2418 #else 2419 tdq = TDQ_SELF(); 2420 TDQ_LOCK(tdq); 2421 /* 2422 * Now that the thread is moving to the run-queue, set the lock 2423 * to the scheduler's lock. 2424 */ 2425 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 2426 tdq_add(tdq, td, flags); 2427 #endif 2428 if (!(flags & SRQ_YIELDING)) 2429 sched_setpreempt(td); 2430 } 2431 2432 /* 2433 * Remove a thread from a run-queue without running it. This is used 2434 * when we're stealing a thread from a remote queue. Otherwise all threads 2435 * exit by calling sched_exit_thread() and sched_throw() themselves. 2436 */ 2437 void 2438 sched_rem(struct thread *td) 2439 { 2440 struct tdq *tdq; 2441 2442 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "runq rem", 2443 "prio:%d", td->td_priority); 2444 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL); 2445 tdq = TDQ_CPU(td->td_sched->ts_cpu); 2446 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2447 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2448 KASSERT(TD_ON_RUNQ(td), 2449 ("sched_rem: thread not on run queue")); 2450 tdq_runq_rem(tdq, td); 2451 tdq_load_rem(tdq, td); 2452 TD_SET_CAN_RUN(td); 2453 if (td->td_priority == tdq->tdq_lowpri) 2454 tdq_setlowpri(tdq, NULL); 2455 } 2456 2457 /* 2458 * Fetch cpu utilization information. Updates on demand. 2459 */ 2460 fixpt_t 2461 sched_pctcpu(struct thread *td) 2462 { 2463 fixpt_t pctcpu; 2464 struct td_sched *ts; 2465 2466 pctcpu = 0; 2467 ts = td->td_sched; 2468 if (ts == NULL) 2469 return (0); 2470 2471 THREAD_LOCK_ASSERT(td, MA_OWNED); 2472 sched_pctcpu_update(ts, TD_IS_RUNNING(td)); 2473 if (ts->ts_ticks) { 2474 int rtick; 2475 2476 /* How many rtick per second ? */ 2477 rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz); 2478 pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT; 2479 } 2480 2481 return (pctcpu); 2482 } 2483 2484 /* 2485 * Enforce affinity settings for a thread. Called after adjustments to 2486 * cpumask. 2487 */ 2488 void 2489 sched_affinity(struct thread *td) 2490 { 2491 #ifdef SMP 2492 struct td_sched *ts; 2493 2494 THREAD_LOCK_ASSERT(td, MA_OWNED); 2495 ts = td->td_sched; 2496 if (THREAD_CAN_SCHED(td, ts->ts_cpu)) 2497 return; 2498 if (TD_ON_RUNQ(td)) { 2499 sched_rem(td); 2500 sched_add(td, SRQ_BORING); 2501 return; 2502 } 2503 if (!TD_IS_RUNNING(td)) 2504 return; 2505 /* 2506 * Force a switch before returning to userspace. If the 2507 * target thread is not running locally send an ipi to force 2508 * the issue. 2509 */ 2510 td->td_flags |= TDF_NEEDRESCHED; 2511 if (td != curthread) 2512 ipi_cpu(ts->ts_cpu, IPI_PREEMPT); 2513 #endif 2514 } 2515 2516 /* 2517 * Bind a thread to a target cpu. 2518 */ 2519 void 2520 sched_bind(struct thread *td, int cpu) 2521 { 2522 struct td_sched *ts; 2523 2524 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 2525 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 2526 ts = td->td_sched; 2527 if (ts->ts_flags & TSF_BOUND) 2528 sched_unbind(td); 2529 KASSERT(THREAD_CAN_MIGRATE(td), ("%p must be migratable", td)); 2530 ts->ts_flags |= TSF_BOUND; 2531 sched_pin(); 2532 if (PCPU_GET(cpuid) == cpu) 2533 return; 2534 ts->ts_cpu = cpu; 2535 /* When we return from mi_switch we'll be on the correct cpu. */ 2536 mi_switch(SW_VOL, NULL); 2537 } 2538 2539 /* 2540 * Release a bound thread. 2541 */ 2542 void 2543 sched_unbind(struct thread *td) 2544 { 2545 struct td_sched *ts; 2546 2547 THREAD_LOCK_ASSERT(td, MA_OWNED); 2548 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 2549 ts = td->td_sched; 2550 if ((ts->ts_flags & TSF_BOUND) == 0) 2551 return; 2552 ts->ts_flags &= ~TSF_BOUND; 2553 sched_unpin(); 2554 } 2555 2556 int 2557 sched_is_bound(struct thread *td) 2558 { 2559 THREAD_LOCK_ASSERT(td, MA_OWNED); 2560 return (td->td_sched->ts_flags & TSF_BOUND); 2561 } 2562 2563 /* 2564 * Basic yield call. 2565 */ 2566 void 2567 sched_relinquish(struct thread *td) 2568 { 2569 thread_lock(td); 2570 mi_switch(SW_VOL | SWT_RELINQUISH, NULL); 2571 thread_unlock(td); 2572 } 2573 2574 /* 2575 * Return the total system load. 2576 */ 2577 int 2578 sched_load(void) 2579 { 2580 #ifdef SMP 2581 int total; 2582 int i; 2583 2584 total = 0; 2585 CPU_FOREACH(i) 2586 total += TDQ_CPU(i)->tdq_sysload; 2587 return (total); 2588 #else 2589 return (TDQ_SELF()->tdq_sysload); 2590 #endif 2591 } 2592 2593 int 2594 sched_sizeof_proc(void) 2595 { 2596 return (sizeof(struct proc)); 2597 } 2598 2599 int 2600 sched_sizeof_thread(void) 2601 { 2602 return (sizeof(struct thread) + sizeof(struct td_sched)); 2603 } 2604 2605 #ifdef SMP 2606 #define TDQ_IDLESPIN(tdq) \ 2607 ((tdq)->tdq_cg != NULL && ((tdq)->tdq_cg->cg_flags & CG_FLAG_THREAD) == 0) 2608 #else 2609 #define TDQ_IDLESPIN(tdq) 1 2610 #endif 2611 2612 /* 2613 * The actual idle process. 2614 */ 2615 void 2616 sched_idletd(void *dummy) 2617 { 2618 struct thread *td; 2619 struct tdq *tdq; 2620 int oldswitchcnt, switchcnt; 2621 int i; 2622 2623 mtx_assert(&Giant, MA_NOTOWNED); 2624 td = curthread; 2625 tdq = TDQ_SELF(); 2626 THREAD_NO_SLEEPING(); 2627 oldswitchcnt = -1; 2628 for (;;) { 2629 if (tdq->tdq_load) { 2630 thread_lock(td); 2631 mi_switch(SW_VOL | SWT_IDLE, NULL); 2632 thread_unlock(td); 2633 } 2634 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2635 #ifdef SMP 2636 if (switchcnt != oldswitchcnt) { 2637 oldswitchcnt = switchcnt; 2638 if (tdq_idled(tdq) == 0) 2639 continue; 2640 } 2641 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2642 #else 2643 oldswitchcnt = switchcnt; 2644 #endif 2645 /* 2646 * If we're switching very frequently, spin while checking 2647 * for load rather than entering a low power state that 2648 * may require an IPI. However, don't do any busy 2649 * loops while on SMT machines as this simply steals 2650 * cycles from cores doing useful work. 2651 */ 2652 if (TDQ_IDLESPIN(tdq) && switchcnt > sched_idlespinthresh) { 2653 for (i = 0; i < sched_idlespins; i++) { 2654 if (tdq->tdq_load) 2655 break; 2656 cpu_spinwait(); 2657 } 2658 } 2659 2660 /* If there was context switch during spin, restart it. */ 2661 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2662 if (tdq->tdq_load != 0 || switchcnt != oldswitchcnt) 2663 continue; 2664 2665 /* Run main MD idle handler. */ 2666 tdq->tdq_cpu_idle = 1; 2667 /* 2668 * Make sure that tdq_cpu_idle update is globally visible 2669 * before cpu_idle() read tdq_load. The order is important 2670 * to avoid race with tdq_notify. 2671 */ 2672 mb(); 2673 cpu_idle(switchcnt * 4 > sched_idlespinthresh); 2674 tdq->tdq_cpu_idle = 0; 2675 2676 /* 2677 * Account thread-less hardware interrupts and 2678 * other wakeup reasons equal to context switches. 2679 */ 2680 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2681 if (switchcnt != oldswitchcnt) 2682 continue; 2683 tdq->tdq_switchcnt++; 2684 oldswitchcnt++; 2685 } 2686 } 2687 2688 /* 2689 * A CPU is entering for the first time or a thread is exiting. 2690 */ 2691 void 2692 sched_throw(struct thread *td) 2693 { 2694 struct thread *newtd; 2695 struct tdq *tdq; 2696 2697 tdq = TDQ_SELF(); 2698 if (td == NULL) { 2699 /* Correct spinlock nesting and acquire the correct lock. */ 2700 TDQ_LOCK(tdq); 2701 spinlock_exit(); 2702 PCPU_SET(switchtime, cpu_ticks()); 2703 PCPU_SET(switchticks, ticks); 2704 } else { 2705 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2706 tdq_load_rem(tdq, td); 2707 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 2708 } 2709 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 2710 newtd = choosethread(); 2711 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 2712 cpu_throw(td, newtd); /* doesn't return */ 2713 } 2714 2715 /* 2716 * This is called from fork_exit(). Just acquire the correct locks and 2717 * let fork do the rest of the work. 2718 */ 2719 void 2720 sched_fork_exit(struct thread *td) 2721 { 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 if (TD_IS_IDLETHREAD(td)) 2732 td->td_lock = TDQ_LOCKPTR(tdq); 2733 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2734 td->td_oncpu = cpuid; 2735 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 2736 lock_profile_obtain_lock_success( 2737 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 2738 } 2739 2740 /* 2741 * Create on first use to catch odd startup conditons. 2742 */ 2743 char * 2744 sched_tdname(struct thread *td) 2745 { 2746 #ifdef KTR 2747 struct td_sched *ts; 2748 2749 ts = td->td_sched; 2750 if (ts->ts_name[0] == '\0') 2751 snprintf(ts->ts_name, sizeof(ts->ts_name), 2752 "%s tid %d", td->td_name, td->td_tid); 2753 return (ts->ts_name); 2754 #else 2755 return (td->td_name); 2756 #endif 2757 } 2758 2759 #ifdef KTR 2760 void 2761 sched_clear_tdname(struct thread *td) 2762 { 2763 struct td_sched *ts; 2764 2765 ts = td->td_sched; 2766 ts->ts_name[0] = '\0'; 2767 } 2768 #endif 2769 2770 #ifdef SMP 2771 2772 /* 2773 * Build the CPU topology dump string. Is recursively called to collect 2774 * the topology tree. 2775 */ 2776 static int 2777 sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, struct cpu_group *cg, 2778 int indent) 2779 { 2780 char cpusetbuf[CPUSETBUFSIZ]; 2781 int i, first; 2782 2783 sbuf_printf(sb, "%*s<group level=\"%d\" cache-level=\"%d\">\n", indent, 2784 "", 1 + indent / 2, cg->cg_level); 2785 sbuf_printf(sb, "%*s <cpu count=\"%d\" mask=\"%s\">", indent, "", 2786 cg->cg_count, cpusetobj_strprint(cpusetbuf, &cg->cg_mask)); 2787 first = TRUE; 2788 for (i = 0; i < MAXCPU; i++) { 2789 if (CPU_ISSET(i, &cg->cg_mask)) { 2790 if (!first) 2791 sbuf_printf(sb, ", "); 2792 else 2793 first = FALSE; 2794 sbuf_printf(sb, "%d", i); 2795 } 2796 } 2797 sbuf_printf(sb, "</cpu>\n"); 2798 2799 if (cg->cg_flags != 0) { 2800 sbuf_printf(sb, "%*s <flags>", indent, ""); 2801 if ((cg->cg_flags & CG_FLAG_HTT) != 0) 2802 sbuf_printf(sb, "<flag name=\"HTT\">HTT group</flag>"); 2803 if ((cg->cg_flags & CG_FLAG_THREAD) != 0) 2804 sbuf_printf(sb, "<flag name=\"THREAD\">THREAD group</flag>"); 2805 if ((cg->cg_flags & CG_FLAG_SMT) != 0) 2806 sbuf_printf(sb, "<flag name=\"SMT\">SMT group</flag>"); 2807 sbuf_printf(sb, "</flags>\n"); 2808 } 2809 2810 if (cg->cg_children > 0) { 2811 sbuf_printf(sb, "%*s <children>\n", indent, ""); 2812 for (i = 0; i < cg->cg_children; i++) 2813 sysctl_kern_sched_topology_spec_internal(sb, 2814 &cg->cg_child[i], indent+2); 2815 sbuf_printf(sb, "%*s </children>\n", indent, ""); 2816 } 2817 sbuf_printf(sb, "%*s</group>\n", indent, ""); 2818 return (0); 2819 } 2820 2821 /* 2822 * Sysctl handler for retrieving topology dump. It's a wrapper for 2823 * the recursive sysctl_kern_smp_topology_spec_internal(). 2824 */ 2825 static int 2826 sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS) 2827 { 2828 struct sbuf *topo; 2829 int err; 2830 2831 KASSERT(cpu_top != NULL, ("cpu_top isn't initialized")); 2832 2833 topo = sbuf_new_for_sysctl(NULL, NULL, 512, req); 2834 if (topo == NULL) 2835 return (ENOMEM); 2836 2837 sbuf_printf(topo, "<groups>\n"); 2838 err = sysctl_kern_sched_topology_spec_internal(topo, cpu_top, 1); 2839 sbuf_printf(topo, "</groups>\n"); 2840 2841 if (err == 0) { 2842 err = sbuf_finish(topo); 2843 } 2844 sbuf_delete(topo); 2845 return (err); 2846 } 2847 2848 #endif 2849 2850 static int 2851 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 2852 { 2853 int error, new_val, period; 2854 2855 period = 1000000 / realstathz; 2856 new_val = period * sched_slice; 2857 error = sysctl_handle_int(oidp, &new_val, 0, req); 2858 if (error != 0 || req->newptr == NULL) 2859 return (error); 2860 if (new_val <= 0) 2861 return (EINVAL); 2862 sched_slice = imax(1, (new_val + period / 2) / period); 2863 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 2864 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 2865 realstathz); 2866 return (0); 2867 } 2868 2869 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0, "Scheduler"); 2870 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0, 2871 "Scheduler name"); 2872 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW, 2873 NULL, 0, sysctl_kern_quantum, "I", 2874 "Quantum for timeshare threads in microseconds"); 2875 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, 2876 "Quantum for timeshare threads in stathz ticks"); 2877 SYSCTL_INT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0, 2878 "Interactivity score threshold"); 2879 SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW, 2880 &preempt_thresh, 0, 2881 "Maximal (lowest) priority for preemption"); 2882 SYSCTL_INT(_kern_sched, OID_AUTO, static_boost, CTLFLAG_RW, &static_boost, 0, 2883 "Assign static kernel priorities to sleeping threads"); 2884 SYSCTL_INT(_kern_sched, OID_AUTO, idlespins, CTLFLAG_RW, &sched_idlespins, 0, 2885 "Number of times idle thread will spin waiting for new work"); 2886 SYSCTL_INT(_kern_sched, OID_AUTO, idlespinthresh, CTLFLAG_RW, 2887 &sched_idlespinthresh, 0, 2888 "Threshold before we will permit idle thread spinning"); 2889 #ifdef SMP 2890 SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0, 2891 "Number of hz ticks to keep thread affinity for"); 2892 SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0, 2893 "Enables the long-term load balancer"); 2894 SYSCTL_INT(_kern_sched, OID_AUTO, balance_interval, CTLFLAG_RW, 2895 &balance_interval, 0, 2896 "Average period in stathz ticks to run the long-term balancer"); 2897 SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0, 2898 "Attempts to steal work from other cores before idling"); 2899 SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0, 2900 "Minimum load on remote CPU before we'll steal"); 2901 SYSCTL_PROC(_kern_sched, OID_AUTO, topology_spec, CTLTYPE_STRING | 2902 CTLFLAG_RD, NULL, 0, sysctl_kern_sched_topology_spec, "A", 2903 "XML dump of detected CPU topology"); 2904 #endif 2905 2906 /* ps compat. All cpu percentages from ULE are weighted. */ 2907 static int ccpu = 0; 2908 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 2909