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_kdtrace.h" 43 #include "opt_sched.h" 44 45 #include <sys/param.h> 46 #include <sys/systm.h> 47 #include <sys/kdb.h> 48 #include <sys/kernel.h> 49 #include <sys/ktr.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 #if defined(__powerpc__) && defined(BOOKE_E500) 81 #error "This architecture is not currently compatible with ULE" 82 #endif 83 84 #define KTR_ULE 0 85 86 #define TS_NAME_LEN (MAXCOMLEN + sizeof(" td ") + sizeof(__XSTRING(UINT_MAX))) 87 #define TDQ_NAME_LEN (sizeof("sched lock ") + sizeof(__XSTRING(MAXCPU))) 88 #define TDQ_LOADNAME_LEN (sizeof("CPU ") + sizeof(__XSTRING(MAXCPU)) - 1 + sizeof(" load")) 89 90 /* 91 * Thread scheduler specific section. All fields are protected 92 * by the thread lock. 93 */ 94 struct td_sched { 95 struct runq *ts_runq; /* Run-queue we're queued on. */ 96 short ts_flags; /* TSF_* flags. */ 97 u_char ts_cpu; /* CPU that we have affinity for. */ 98 int ts_rltick; /* Real last tick, for affinity. */ 99 int ts_slice; /* Ticks of slice remaining. */ 100 u_int ts_slptime; /* Number of ticks we vol. slept */ 101 u_int ts_runtime; /* Number of ticks we were running */ 102 int ts_ltick; /* Last tick that we were running on */ 103 int ts_ftick; /* First tick that we were running on */ 104 int ts_ticks; /* Tick count */ 105 #ifdef KTR 106 char ts_name[TS_NAME_LEN]; 107 #endif 108 }; 109 /* flags kept in ts_flags */ 110 #define TSF_BOUND 0x0001 /* Thread can not migrate. */ 111 #define TSF_XFERABLE 0x0002 /* Thread was added as transferable. */ 112 113 static struct td_sched td_sched0; 114 115 #define THREAD_CAN_MIGRATE(td) ((td)->td_pinned == 0) 116 #define THREAD_CAN_SCHED(td, cpu) \ 117 CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask) 118 119 /* 120 * Priority ranges used for interactive and non-interactive timeshare 121 * threads. The timeshare priorities are split up into four ranges. 122 * The first range handles interactive threads. The last three ranges 123 * (NHALF, x, and NHALF) handle non-interactive threads with the outer 124 * ranges supporting nice values. 125 */ 126 #define PRI_TIMESHARE_RANGE (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE + 1) 127 #define PRI_INTERACT_RANGE ((PRI_TIMESHARE_RANGE - SCHED_PRI_NRESV) / 2) 128 #define PRI_BATCH_RANGE (PRI_TIMESHARE_RANGE - PRI_INTERACT_RANGE) 129 130 #define PRI_MIN_INTERACT PRI_MIN_TIMESHARE 131 #define PRI_MAX_INTERACT (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE - 1) 132 #define PRI_MIN_BATCH (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE) 133 #define PRI_MAX_BATCH PRI_MAX_TIMESHARE 134 135 /* 136 * Cpu percentage computation macros and defines. 137 * 138 * SCHED_TICK_SECS: Number of seconds to average the cpu usage across. 139 * SCHED_TICK_TARG: Number of hz ticks to average the cpu usage across. 140 * SCHED_TICK_MAX: Maximum number of ticks before scaling back. 141 * SCHED_TICK_SHIFT: Shift factor to avoid rounding away results. 142 * SCHED_TICK_HZ: Compute the number of hz ticks for a given ticks count. 143 * SCHED_TICK_TOTAL: Gives the amount of time we've been recording ticks. 144 */ 145 #define SCHED_TICK_SECS 10 146 #define SCHED_TICK_TARG (hz * SCHED_TICK_SECS) 147 #define SCHED_TICK_MAX (SCHED_TICK_TARG + hz) 148 #define SCHED_TICK_SHIFT 10 149 #define SCHED_TICK_HZ(ts) ((ts)->ts_ticks >> SCHED_TICK_SHIFT) 150 #define SCHED_TICK_TOTAL(ts) (max((ts)->ts_ltick - (ts)->ts_ftick, hz)) 151 152 /* 153 * These macros determine priorities for non-interactive threads. They are 154 * assigned a priority based on their recent cpu utilization as expressed 155 * by the ratio of ticks to the tick total. NHALF priorities at the start 156 * and end of the MIN to MAX timeshare range are only reachable with negative 157 * or positive nice respectively. 158 * 159 * PRI_RANGE: Priority range for utilization dependent priorities. 160 * PRI_NRESV: Number of nice values. 161 * PRI_TICKS: Compute a priority in PRI_RANGE from the ticks count and total. 162 * PRI_NICE: Determines the part of the priority inherited from nice. 163 */ 164 #define SCHED_PRI_NRESV (PRIO_MAX - PRIO_MIN) 165 #define SCHED_PRI_NHALF (SCHED_PRI_NRESV / 2) 166 #define SCHED_PRI_MIN (PRI_MIN_BATCH + SCHED_PRI_NHALF) 167 #define SCHED_PRI_MAX (PRI_MAX_BATCH - SCHED_PRI_NHALF) 168 #define SCHED_PRI_RANGE (SCHED_PRI_MAX - SCHED_PRI_MIN + 1) 169 #define SCHED_PRI_TICKS(ts) \ 170 (SCHED_TICK_HZ((ts)) / \ 171 (roundup(SCHED_TICK_TOTAL((ts)), SCHED_PRI_RANGE) / SCHED_PRI_RANGE)) 172 #define SCHED_PRI_NICE(nice) (nice) 173 174 /* 175 * These determine the interactivity of a process. Interactivity differs from 176 * cpu utilization in that it expresses the voluntary time slept vs time ran 177 * while cpu utilization includes all time not running. This more accurately 178 * models the intent of the thread. 179 * 180 * SLP_RUN_MAX: Maximum amount of sleep time + run time we'll accumulate 181 * before throttling back. 182 * SLP_RUN_FORK: Maximum slp+run time to inherit at fork time. 183 * INTERACT_MAX: Maximum interactivity value. Smaller is better. 184 * INTERACT_THRESH: Threshold for placement on the current runq. 185 */ 186 #define SCHED_SLP_RUN_MAX ((hz * 5) << SCHED_TICK_SHIFT) 187 #define SCHED_SLP_RUN_FORK ((hz / 2) << SCHED_TICK_SHIFT) 188 #define SCHED_INTERACT_MAX (100) 189 #define SCHED_INTERACT_HALF (SCHED_INTERACT_MAX / 2) 190 #define SCHED_INTERACT_THRESH (30) 191 192 /* 193 * These parameters determine the slice behavior for batch work. 194 */ 195 #define SCHED_SLICE_DEFAULT_DIVISOR 10 /* ~94 ms, 12 stathz ticks. */ 196 #define SCHED_SLICE_MIN_DIVISOR 6 /* DEFAULT/MIN = ~16 ms. */ 197 198 /* Flags kept in td_flags. */ 199 #define TDF_SLICEEND TDF_SCHED2 /* Thread time slice is over. */ 200 201 /* 202 * tickincr: Converts a stathz tick into a hz domain scaled by 203 * the shift factor. Without the shift the error rate 204 * due to rounding would be unacceptably high. 205 * realstathz: stathz is sometimes 0 and run off of hz. 206 * sched_slice: Runtime of each thread before rescheduling. 207 * preempt_thresh: Priority threshold for preemption and remote IPIs. 208 */ 209 static int sched_interact = SCHED_INTERACT_THRESH; 210 static int tickincr = 8 << SCHED_TICK_SHIFT; 211 static int realstathz = 127; /* reset during boot. */ 212 static int sched_slice = 10; /* reset during boot. */ 213 static int sched_slice_min = 1; /* reset during boot. */ 214 #ifdef PREEMPTION 215 #ifdef FULL_PREEMPTION 216 static int preempt_thresh = PRI_MAX_IDLE; 217 #else 218 static int preempt_thresh = PRI_MIN_KERN; 219 #endif 220 #else 221 static int preempt_thresh = 0; 222 #endif 223 static int static_boost = PRI_MIN_BATCH; 224 static int sched_idlespins = 10000; 225 static int sched_idlespinthresh = -1; 226 227 /* 228 * tdq - per processor runqs and statistics. All fields are protected by the 229 * tdq_lock. The load and lowpri may be accessed without to avoid excess 230 * locking in sched_pickcpu(); 231 */ 232 struct tdq { 233 /* 234 * Ordered to improve efficiency of cpu_search() and switch(). 235 * tdq_lock is padded to avoid false sharing with tdq_load and 236 * tdq_cpu_idle. 237 */ 238 struct mtx_padalign tdq_lock; /* run queue lock. */ 239 struct cpu_group *tdq_cg; /* Pointer to cpu topology. */ 240 volatile int tdq_load; /* Aggregate load. */ 241 volatile int tdq_cpu_idle; /* cpu_idle() is active. */ 242 int tdq_sysload; /* For loadavg, !ITHD load. */ 243 int tdq_transferable; /* Transferable thread count. */ 244 short tdq_switchcnt; /* Switches this tick. */ 245 short tdq_oldswitchcnt; /* Switches last tick. */ 246 u_char tdq_lowpri; /* Lowest priority thread. */ 247 u_char tdq_ipipending; /* IPI pending. */ 248 u_char tdq_idx; /* Current insert index. */ 249 u_char tdq_ridx; /* Current removal index. */ 250 struct runq tdq_realtime; /* real-time run queue. */ 251 struct runq tdq_timeshare; /* timeshare run queue. */ 252 struct runq tdq_idle; /* Queue of IDLE threads. */ 253 char tdq_name[TDQ_NAME_LEN]; 254 #ifdef KTR 255 char tdq_loadname[TDQ_LOADNAME_LEN]; 256 #endif 257 } __aligned(64); 258 259 /* Idle thread states and config. */ 260 #define TDQ_RUNNING 1 261 #define TDQ_IDLE 2 262 263 #ifdef SMP 264 struct cpu_group *cpu_top; /* CPU topology */ 265 266 #define SCHED_AFFINITY_DEFAULT (max(1, hz / 1000)) 267 #define SCHED_AFFINITY(ts, t) ((ts)->ts_rltick > ticks - ((t) * affinity)) 268 269 /* 270 * Run-time tunables. 271 */ 272 static int rebalance = 1; 273 static int balance_interval = 128; /* Default set in sched_initticks(). */ 274 static int affinity; 275 static int steal_idle = 1; 276 static int steal_thresh = 2; 277 278 /* 279 * One thread queue per processor. 280 */ 281 static struct tdq tdq_cpu[MAXCPU]; 282 static struct tdq *balance_tdq; 283 static int balance_ticks; 284 static DPCPU_DEFINE(uint32_t, randomval); 285 286 #define TDQ_SELF() (&tdq_cpu[PCPU_GET(cpuid)]) 287 #define TDQ_CPU(x) (&tdq_cpu[(x)]) 288 #define TDQ_ID(x) ((int)((x) - tdq_cpu)) 289 #else /* !SMP */ 290 static struct tdq tdq_cpu; 291 292 #define TDQ_ID(x) (0) 293 #define TDQ_SELF() (&tdq_cpu) 294 #define TDQ_CPU(x) (&tdq_cpu) 295 #endif 296 297 #define TDQ_LOCK_ASSERT(t, type) mtx_assert(TDQ_LOCKPTR((t)), (type)) 298 #define TDQ_LOCK(t) mtx_lock_spin(TDQ_LOCKPTR((t))) 299 #define TDQ_LOCK_FLAGS(t, f) mtx_lock_spin_flags(TDQ_LOCKPTR((t)), (f)) 300 #define TDQ_UNLOCK(t) mtx_unlock_spin(TDQ_LOCKPTR((t))) 301 #define TDQ_LOCKPTR(t) ((struct mtx *)(&(t)->tdq_lock)) 302 303 static void sched_priority(struct thread *); 304 static void sched_thread_priority(struct thread *, u_char); 305 static int sched_interact_score(struct thread *); 306 static void sched_interact_update(struct thread *); 307 static void sched_interact_fork(struct thread *); 308 static void sched_pctcpu_update(struct td_sched *, int); 309 310 /* Operations on per processor queues */ 311 static struct thread *tdq_choose(struct tdq *); 312 static void tdq_setup(struct tdq *); 313 static void tdq_load_add(struct tdq *, struct thread *); 314 static void tdq_load_rem(struct tdq *, struct thread *); 315 static __inline void tdq_runq_add(struct tdq *, struct thread *, int); 316 static __inline void tdq_runq_rem(struct tdq *, struct thread *); 317 static inline int sched_shouldpreempt(int, int, int); 318 void tdq_print(int cpu); 319 static void runq_print(struct runq *rq); 320 static void tdq_add(struct tdq *, struct thread *, int); 321 #ifdef SMP 322 static int tdq_move(struct tdq *, struct tdq *); 323 static int tdq_idled(struct tdq *); 324 static void tdq_notify(struct tdq *, struct thread *); 325 static struct thread *tdq_steal(struct tdq *, int); 326 static struct thread *runq_steal(struct runq *, int); 327 static int sched_pickcpu(struct thread *, int); 328 static void sched_balance(void); 329 static int sched_balance_pair(struct tdq *, struct tdq *); 330 static inline struct tdq *sched_setcpu(struct thread *, int, int); 331 static inline void thread_unblock_switch(struct thread *, struct mtx *); 332 static struct mtx *sched_switch_migrate(struct tdq *, struct thread *, int); 333 static int sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS); 334 static int sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, 335 struct cpu_group *cg, int indent); 336 #endif 337 338 static void sched_setup(void *dummy); 339 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL); 340 341 static void sched_initticks(void *dummy); 342 SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks, 343 NULL); 344 345 SDT_PROVIDER_DEFINE(sched); 346 347 SDT_PROBE_DEFINE3(sched, , , change_pri, change-pri, "struct thread *", 348 "struct proc *", "uint8_t"); 349 SDT_PROBE_DEFINE3(sched, , , dequeue, dequeue, "struct thread *", 350 "struct proc *", "void *"); 351 SDT_PROBE_DEFINE4(sched, , , enqueue, enqueue, "struct thread *", 352 "struct proc *", "void *", "int"); 353 SDT_PROBE_DEFINE4(sched, , , lend_pri, lend-pri, "struct thread *", 354 "struct proc *", "uint8_t", "struct thread *"); 355 SDT_PROBE_DEFINE2(sched, , , load_change, load-change, "int", "int"); 356 SDT_PROBE_DEFINE2(sched, , , off_cpu, off-cpu, "struct thread *", 357 "struct proc *"); 358 SDT_PROBE_DEFINE(sched, , , on_cpu, on-cpu); 359 SDT_PROBE_DEFINE(sched, , , remain_cpu, remain-cpu); 360 SDT_PROBE_DEFINE2(sched, , , surrender, surrender, "struct thread *", 361 "struct proc *"); 362 363 /* 364 * Print the threads waiting on a run-queue. 365 */ 366 static void 367 runq_print(struct runq *rq) 368 { 369 struct rqhead *rqh; 370 struct thread *td; 371 int pri; 372 int j; 373 int i; 374 375 for (i = 0; i < RQB_LEN; i++) { 376 printf("\t\trunq bits %d 0x%zx\n", 377 i, rq->rq_status.rqb_bits[i]); 378 for (j = 0; j < RQB_BPW; j++) 379 if (rq->rq_status.rqb_bits[i] & (1ul << j)) { 380 pri = j + (i << RQB_L2BPW); 381 rqh = &rq->rq_queues[pri]; 382 TAILQ_FOREACH(td, rqh, td_runq) { 383 printf("\t\t\ttd %p(%s) priority %d rqindex %d pri %d\n", 384 td, td->td_name, td->td_priority, 385 td->td_rqindex, pri); 386 } 387 } 388 } 389 } 390 391 /* 392 * Print the status of a per-cpu thread queue. Should be a ddb show cmd. 393 */ 394 void 395 tdq_print(int cpu) 396 { 397 struct tdq *tdq; 398 399 tdq = TDQ_CPU(cpu); 400 401 printf("tdq %d:\n", TDQ_ID(tdq)); 402 printf("\tlock %p\n", TDQ_LOCKPTR(tdq)); 403 printf("\tLock name: %s\n", tdq->tdq_name); 404 printf("\tload: %d\n", tdq->tdq_load); 405 printf("\tswitch cnt: %d\n", tdq->tdq_switchcnt); 406 printf("\told switch cnt: %d\n", tdq->tdq_oldswitchcnt); 407 printf("\ttimeshare idx: %d\n", tdq->tdq_idx); 408 printf("\ttimeshare ridx: %d\n", tdq->tdq_ridx); 409 printf("\tload transferable: %d\n", tdq->tdq_transferable); 410 printf("\tlowest priority: %d\n", tdq->tdq_lowpri); 411 printf("\trealtime runq:\n"); 412 runq_print(&tdq->tdq_realtime); 413 printf("\ttimeshare runq:\n"); 414 runq_print(&tdq->tdq_timeshare); 415 printf("\tidle runq:\n"); 416 runq_print(&tdq->tdq_idle); 417 } 418 419 static inline int 420 sched_shouldpreempt(int pri, int cpri, int remote) 421 { 422 /* 423 * If the new priority is not better than the current priority there is 424 * nothing to do. 425 */ 426 if (pri >= cpri) 427 return (0); 428 /* 429 * Always preempt idle. 430 */ 431 if (cpri >= PRI_MIN_IDLE) 432 return (1); 433 /* 434 * If preemption is disabled don't preempt others. 435 */ 436 if (preempt_thresh == 0) 437 return (0); 438 /* 439 * Preempt if we exceed the threshold. 440 */ 441 if (pri <= preempt_thresh) 442 return (1); 443 /* 444 * If we're interactive or better and there is non-interactive 445 * or worse running preempt only remote processors. 446 */ 447 if (remote && pri <= PRI_MAX_INTERACT && cpri > PRI_MAX_INTERACT) 448 return (1); 449 return (0); 450 } 451 452 /* 453 * Add a thread to the actual run-queue. Keeps transferable counts up to 454 * date with what is actually on the run-queue. Selects the correct 455 * queue position for timeshare threads. 456 */ 457 static __inline void 458 tdq_runq_add(struct tdq *tdq, struct thread *td, int flags) 459 { 460 struct td_sched *ts; 461 u_char pri; 462 463 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 464 THREAD_LOCK_ASSERT(td, MA_OWNED); 465 466 pri = td->td_priority; 467 ts = td->td_sched; 468 TD_SET_RUNQ(td); 469 if (THREAD_CAN_MIGRATE(td)) { 470 tdq->tdq_transferable++; 471 ts->ts_flags |= TSF_XFERABLE; 472 } 473 if (pri < PRI_MIN_BATCH) { 474 ts->ts_runq = &tdq->tdq_realtime; 475 } else if (pri <= PRI_MAX_BATCH) { 476 ts->ts_runq = &tdq->tdq_timeshare; 477 KASSERT(pri <= PRI_MAX_BATCH && pri >= PRI_MIN_BATCH, 478 ("Invalid priority %d on timeshare runq", pri)); 479 /* 480 * This queue contains only priorities between MIN and MAX 481 * realtime. Use the whole queue to represent these values. 482 */ 483 if ((flags & (SRQ_BORROWING|SRQ_PREEMPTED)) == 0) { 484 pri = RQ_NQS * (pri - PRI_MIN_BATCH) / PRI_BATCH_RANGE; 485 pri = (pri + tdq->tdq_idx) % RQ_NQS; 486 /* 487 * This effectively shortens the queue by one so we 488 * can have a one slot difference between idx and 489 * ridx while we wait for threads to drain. 490 */ 491 if (tdq->tdq_ridx != tdq->tdq_idx && 492 pri == tdq->tdq_ridx) 493 pri = (unsigned char)(pri - 1) % RQ_NQS; 494 } else 495 pri = tdq->tdq_ridx; 496 runq_add_pri(ts->ts_runq, td, pri, flags); 497 return; 498 } else 499 ts->ts_runq = &tdq->tdq_idle; 500 runq_add(ts->ts_runq, td, flags); 501 } 502 503 /* 504 * Remove a thread from a run-queue. This typically happens when a thread 505 * is selected to run. Running threads are not on the queue and the 506 * transferable count does not reflect them. 507 */ 508 static __inline void 509 tdq_runq_rem(struct tdq *tdq, struct thread *td) 510 { 511 struct td_sched *ts; 512 513 ts = td->td_sched; 514 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 515 KASSERT(ts->ts_runq != NULL, 516 ("tdq_runq_remove: thread %p null ts_runq", td)); 517 if (ts->ts_flags & TSF_XFERABLE) { 518 tdq->tdq_transferable--; 519 ts->ts_flags &= ~TSF_XFERABLE; 520 } 521 if (ts->ts_runq == &tdq->tdq_timeshare) { 522 if (tdq->tdq_idx != tdq->tdq_ridx) 523 runq_remove_idx(ts->ts_runq, td, &tdq->tdq_ridx); 524 else 525 runq_remove_idx(ts->ts_runq, td, NULL); 526 } else 527 runq_remove(ts->ts_runq, td); 528 } 529 530 /* 531 * Load is maintained for all threads RUNNING and ON_RUNQ. Add the load 532 * for this thread to the referenced thread queue. 533 */ 534 static void 535 tdq_load_add(struct tdq *tdq, struct thread *td) 536 { 537 538 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 539 THREAD_LOCK_ASSERT(td, MA_OWNED); 540 541 tdq->tdq_load++; 542 if ((td->td_flags & TDF_NOLOAD) == 0) 543 tdq->tdq_sysload++; 544 KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load); 545 SDT_PROBE2(sched, , , load_change, (int)TDQ_ID(tdq), tdq->tdq_load); 546 } 547 548 /* 549 * Remove the load from a thread that is transitioning to a sleep state or 550 * exiting. 551 */ 552 static void 553 tdq_load_rem(struct tdq *tdq, struct thread *td) 554 { 555 556 THREAD_LOCK_ASSERT(td, MA_OWNED); 557 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 558 KASSERT(tdq->tdq_load != 0, 559 ("tdq_load_rem: Removing with 0 load on queue %d", TDQ_ID(tdq))); 560 561 tdq->tdq_load--; 562 if ((td->td_flags & TDF_NOLOAD) == 0) 563 tdq->tdq_sysload--; 564 KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load); 565 SDT_PROBE2(sched, , , load_change, (int)TDQ_ID(tdq), tdq->tdq_load); 566 } 567 568 /* 569 * Bound timeshare latency by decreasing slice size as load increases. We 570 * consider the maximum latency as the sum of the threads waiting to run 571 * aside from curthread and target no more than sched_slice latency but 572 * no less than sched_slice_min runtime. 573 */ 574 static inline int 575 tdq_slice(struct tdq *tdq) 576 { 577 int load; 578 579 /* 580 * It is safe to use sys_load here because this is called from 581 * contexts where timeshare threads are running and so there 582 * cannot be higher priority load in the system. 583 */ 584 load = tdq->tdq_sysload - 1; 585 if (load >= SCHED_SLICE_MIN_DIVISOR) 586 return (sched_slice_min); 587 if (load <= 1) 588 return (sched_slice); 589 return (sched_slice / load); 590 } 591 592 /* 593 * Set lowpri to its exact value by searching the run-queue and 594 * evaluating curthread. curthread may be passed as an optimization. 595 */ 596 static void 597 tdq_setlowpri(struct tdq *tdq, struct thread *ctd) 598 { 599 struct thread *td; 600 601 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 602 if (ctd == NULL) 603 ctd = pcpu_find(TDQ_ID(tdq))->pc_curthread; 604 td = tdq_choose(tdq); 605 if (td == NULL || td->td_priority > ctd->td_priority) 606 tdq->tdq_lowpri = ctd->td_priority; 607 else 608 tdq->tdq_lowpri = td->td_priority; 609 } 610 611 #ifdef SMP 612 struct cpu_search { 613 cpuset_t cs_mask; 614 u_int cs_prefer; 615 int cs_pri; /* Min priority for low. */ 616 int cs_limit; /* Max load for low, min load for high. */ 617 int cs_cpu; 618 int cs_load; 619 }; 620 621 #define CPU_SEARCH_LOWEST 0x1 622 #define CPU_SEARCH_HIGHEST 0x2 623 #define CPU_SEARCH_BOTH (CPU_SEARCH_LOWEST|CPU_SEARCH_HIGHEST) 624 625 #define CPUSET_FOREACH(cpu, mask) \ 626 for ((cpu) = 0; (cpu) <= mp_maxid; (cpu)++) \ 627 if (CPU_ISSET(cpu, &mask)) 628 629 static __inline int cpu_search(const struct cpu_group *cg, struct cpu_search *low, 630 struct cpu_search *high, const int match); 631 int cpu_search_lowest(const struct cpu_group *cg, struct cpu_search *low); 632 int cpu_search_highest(const struct cpu_group *cg, struct cpu_search *high); 633 int cpu_search_both(const struct cpu_group *cg, struct cpu_search *low, 634 struct cpu_search *high); 635 636 /* 637 * Search the tree of cpu_groups for the lowest or highest loaded cpu 638 * according to the match argument. This routine actually compares the 639 * load on all paths through the tree and finds the least loaded cpu on 640 * the least loaded path, which may differ from the least loaded cpu in 641 * the system. This balances work among caches and busses. 642 * 643 * This inline is instantiated in three forms below using constants for the 644 * match argument. It is reduced to the minimum set for each case. It is 645 * also recursive to the depth of the tree. 646 */ 647 static __inline int 648 cpu_search(const struct cpu_group *cg, struct cpu_search *low, 649 struct cpu_search *high, const int match) 650 { 651 struct cpu_search lgroup; 652 struct cpu_search hgroup; 653 cpuset_t cpumask; 654 struct cpu_group *child; 655 struct tdq *tdq; 656 int cpu, i, hload, lload, load, total, rnd, *rndptr; 657 658 total = 0; 659 cpumask = cg->cg_mask; 660 if (match & CPU_SEARCH_LOWEST) { 661 lload = INT_MAX; 662 lgroup = *low; 663 } 664 if (match & CPU_SEARCH_HIGHEST) { 665 hload = INT_MIN; 666 hgroup = *high; 667 } 668 669 /* Iterate through the child CPU groups and then remaining CPUs. */ 670 for (i = cg->cg_children, cpu = mp_maxid; i >= 0; ) { 671 if (i == 0) { 672 while (cpu >= 0 && !CPU_ISSET(cpu, &cpumask)) 673 cpu--; 674 if (cpu < 0) 675 break; 676 child = NULL; 677 } else 678 child = &cg->cg_child[i - 1]; 679 680 if (match & CPU_SEARCH_LOWEST) 681 lgroup.cs_cpu = -1; 682 if (match & CPU_SEARCH_HIGHEST) 683 hgroup.cs_cpu = -1; 684 if (child) { /* Handle child CPU group. */ 685 CPU_NAND(&cpumask, &child->cg_mask); 686 switch (match) { 687 case CPU_SEARCH_LOWEST: 688 load = cpu_search_lowest(child, &lgroup); 689 break; 690 case CPU_SEARCH_HIGHEST: 691 load = cpu_search_highest(child, &hgroup); 692 break; 693 case CPU_SEARCH_BOTH: 694 load = cpu_search_both(child, &lgroup, &hgroup); 695 break; 696 } 697 } else { /* Handle child CPU. */ 698 tdq = TDQ_CPU(cpu); 699 load = tdq->tdq_load * 256; 700 rndptr = DPCPU_PTR(randomval); 701 rnd = (*rndptr = *rndptr * 69069 + 5) >> 26; 702 if (match & CPU_SEARCH_LOWEST) { 703 if (cpu == low->cs_prefer) 704 load -= 64; 705 /* If that CPU is allowed and get data. */ 706 if (tdq->tdq_lowpri > lgroup.cs_pri && 707 tdq->tdq_load <= lgroup.cs_limit && 708 CPU_ISSET(cpu, &lgroup.cs_mask)) { 709 lgroup.cs_cpu = cpu; 710 lgroup.cs_load = load - rnd; 711 } 712 } 713 if (match & CPU_SEARCH_HIGHEST) 714 if (tdq->tdq_load >= hgroup.cs_limit && 715 tdq->tdq_transferable && 716 CPU_ISSET(cpu, &hgroup.cs_mask)) { 717 hgroup.cs_cpu = cpu; 718 hgroup.cs_load = load - rnd; 719 } 720 } 721 total += load; 722 723 /* We have info about child item. Compare it. */ 724 if (match & CPU_SEARCH_LOWEST) { 725 if (lgroup.cs_cpu >= 0 && 726 (load < lload || 727 (load == lload && lgroup.cs_load < low->cs_load))) { 728 lload = load; 729 low->cs_cpu = lgroup.cs_cpu; 730 low->cs_load = lgroup.cs_load; 731 } 732 } 733 if (match & CPU_SEARCH_HIGHEST) 734 if (hgroup.cs_cpu >= 0 && 735 (load > hload || 736 (load == hload && hgroup.cs_load > high->cs_load))) { 737 hload = load; 738 high->cs_cpu = hgroup.cs_cpu; 739 high->cs_load = hgroup.cs_load; 740 } 741 if (child) { 742 i--; 743 if (i == 0 && CPU_EMPTY(&cpumask)) 744 break; 745 } else 746 cpu--; 747 } 748 return (total); 749 } 750 751 /* 752 * cpu_search instantiations must pass constants to maintain the inline 753 * optimization. 754 */ 755 int 756 cpu_search_lowest(const struct cpu_group *cg, struct cpu_search *low) 757 { 758 return cpu_search(cg, low, NULL, CPU_SEARCH_LOWEST); 759 } 760 761 int 762 cpu_search_highest(const struct cpu_group *cg, struct cpu_search *high) 763 { 764 return cpu_search(cg, NULL, high, CPU_SEARCH_HIGHEST); 765 } 766 767 int 768 cpu_search_both(const struct cpu_group *cg, struct cpu_search *low, 769 struct cpu_search *high) 770 { 771 return cpu_search(cg, low, high, CPU_SEARCH_BOTH); 772 } 773 774 /* 775 * Find the cpu with the least load via the least loaded path that has a 776 * lowpri greater than pri pri. A pri of -1 indicates any priority is 777 * acceptable. 778 */ 779 static inline int 780 sched_lowest(const struct cpu_group *cg, cpuset_t mask, int pri, int maxload, 781 int prefer) 782 { 783 struct cpu_search low; 784 785 low.cs_cpu = -1; 786 low.cs_prefer = prefer; 787 low.cs_mask = mask; 788 low.cs_pri = pri; 789 low.cs_limit = maxload; 790 cpu_search_lowest(cg, &low); 791 return low.cs_cpu; 792 } 793 794 /* 795 * Find the cpu with the highest load via the highest loaded path. 796 */ 797 static inline int 798 sched_highest(const struct cpu_group *cg, cpuset_t mask, int minload) 799 { 800 struct cpu_search high; 801 802 high.cs_cpu = -1; 803 high.cs_mask = mask; 804 high.cs_limit = minload; 805 cpu_search_highest(cg, &high); 806 return high.cs_cpu; 807 } 808 809 /* 810 * Simultaneously find the highest and lowest loaded cpu reachable via 811 * cg. 812 */ 813 static inline void 814 sched_both(const struct cpu_group *cg, cpuset_t mask, int *lowcpu, int *highcpu) 815 { 816 struct cpu_search high; 817 struct cpu_search low; 818 819 low.cs_cpu = -1; 820 low.cs_prefer = -1; 821 low.cs_pri = -1; 822 low.cs_limit = INT_MAX; 823 low.cs_mask = mask; 824 high.cs_cpu = -1; 825 high.cs_limit = -1; 826 high.cs_mask = mask; 827 cpu_search_both(cg, &low, &high); 828 *lowcpu = low.cs_cpu; 829 *highcpu = high.cs_cpu; 830 return; 831 } 832 833 static void 834 sched_balance_group(struct cpu_group *cg) 835 { 836 cpuset_t hmask, lmask; 837 int high, low, anylow; 838 839 CPU_FILL(&hmask); 840 for (;;) { 841 high = sched_highest(cg, hmask, 1); 842 /* Stop if there is no more CPU with transferrable threads. */ 843 if (high == -1) 844 break; 845 CPU_CLR(high, &hmask); 846 CPU_COPY(&hmask, &lmask); 847 /* Stop if there is no more CPU left for low. */ 848 if (CPU_EMPTY(&lmask)) 849 break; 850 anylow = 1; 851 nextlow: 852 low = sched_lowest(cg, lmask, -1, 853 TDQ_CPU(high)->tdq_load - 1, high); 854 /* Stop if we looked well and found no less loaded CPU. */ 855 if (anylow && low == -1) 856 break; 857 /* Go to next high if we found no less loaded CPU. */ 858 if (low == -1) 859 continue; 860 /* Transfer thread from high to low. */ 861 if (sched_balance_pair(TDQ_CPU(high), TDQ_CPU(low))) { 862 /* CPU that got thread can no longer be a donor. */ 863 CPU_CLR(low, &hmask); 864 } else { 865 /* 866 * If failed, then there is no threads on high 867 * that can run on this low. Drop low from low 868 * mask and look for different one. 869 */ 870 CPU_CLR(low, &lmask); 871 anylow = 0; 872 goto nextlow; 873 } 874 } 875 } 876 877 static void 878 sched_balance(void) 879 { 880 struct tdq *tdq; 881 882 /* 883 * Select a random time between .5 * balance_interval and 884 * 1.5 * balance_interval. 885 */ 886 balance_ticks = max(balance_interval / 2, 1); 887 balance_ticks += random() % balance_interval; 888 if (smp_started == 0 || rebalance == 0) 889 return; 890 tdq = TDQ_SELF(); 891 TDQ_UNLOCK(tdq); 892 sched_balance_group(cpu_top); 893 TDQ_LOCK(tdq); 894 } 895 896 /* 897 * Lock two thread queues using their address to maintain lock order. 898 */ 899 static void 900 tdq_lock_pair(struct tdq *one, struct tdq *two) 901 { 902 if (one < two) { 903 TDQ_LOCK(one); 904 TDQ_LOCK_FLAGS(two, MTX_DUPOK); 905 } else { 906 TDQ_LOCK(two); 907 TDQ_LOCK_FLAGS(one, MTX_DUPOK); 908 } 909 } 910 911 /* 912 * Unlock two thread queues. Order is not important here. 913 */ 914 static void 915 tdq_unlock_pair(struct tdq *one, struct tdq *two) 916 { 917 TDQ_UNLOCK(one); 918 TDQ_UNLOCK(two); 919 } 920 921 /* 922 * Transfer load between two imbalanced thread queues. 923 */ 924 static int 925 sched_balance_pair(struct tdq *high, struct tdq *low) 926 { 927 int moved; 928 int cpu; 929 930 tdq_lock_pair(high, low); 931 moved = 0; 932 /* 933 * Determine what the imbalance is and then adjust that to how many 934 * threads we actually have to give up (transferable). 935 */ 936 if (high->tdq_transferable != 0 && high->tdq_load > low->tdq_load && 937 (moved = tdq_move(high, low)) > 0) { 938 /* 939 * In case the target isn't the current cpu IPI it to force a 940 * reschedule with the new workload. 941 */ 942 cpu = TDQ_ID(low); 943 if (cpu != PCPU_GET(cpuid)) 944 ipi_cpu(cpu, IPI_PREEMPT); 945 } 946 tdq_unlock_pair(high, low); 947 return (moved); 948 } 949 950 /* 951 * Move a thread from one thread queue to another. 952 */ 953 static int 954 tdq_move(struct tdq *from, struct tdq *to) 955 { 956 struct td_sched *ts; 957 struct thread *td; 958 struct tdq *tdq; 959 int cpu; 960 961 TDQ_LOCK_ASSERT(from, MA_OWNED); 962 TDQ_LOCK_ASSERT(to, MA_OWNED); 963 964 tdq = from; 965 cpu = TDQ_ID(to); 966 td = tdq_steal(tdq, cpu); 967 if (td == NULL) 968 return (0); 969 ts = td->td_sched; 970 /* 971 * Although the run queue is locked the thread may be blocked. Lock 972 * it to clear this and acquire the run-queue lock. 973 */ 974 thread_lock(td); 975 /* Drop recursive lock on from acquired via thread_lock(). */ 976 TDQ_UNLOCK(from); 977 sched_rem(td); 978 ts->ts_cpu = cpu; 979 td->td_lock = TDQ_LOCKPTR(to); 980 tdq_add(to, td, SRQ_YIELDING); 981 return (1); 982 } 983 984 /* 985 * This tdq has idled. Try to steal a thread from another cpu and switch 986 * to it. 987 */ 988 static int 989 tdq_idled(struct tdq *tdq) 990 { 991 struct cpu_group *cg; 992 struct tdq *steal; 993 cpuset_t mask; 994 int thresh; 995 int cpu; 996 997 if (smp_started == 0 || steal_idle == 0) 998 return (1); 999 CPU_FILL(&mask); 1000 CPU_CLR(PCPU_GET(cpuid), &mask); 1001 /* We don't want to be preempted while we're iterating. */ 1002 spinlock_enter(); 1003 for (cg = tdq->tdq_cg; cg != NULL; ) { 1004 if ((cg->cg_flags & CG_FLAG_THREAD) == 0) 1005 thresh = steal_thresh; 1006 else 1007 thresh = 1; 1008 cpu = sched_highest(cg, mask, thresh); 1009 if (cpu == -1) { 1010 cg = cg->cg_parent; 1011 continue; 1012 } 1013 steal = TDQ_CPU(cpu); 1014 CPU_CLR(cpu, &mask); 1015 tdq_lock_pair(tdq, steal); 1016 if (steal->tdq_load < thresh || steal->tdq_transferable == 0) { 1017 tdq_unlock_pair(tdq, steal); 1018 continue; 1019 } 1020 /* 1021 * If a thread was added while interrupts were disabled don't 1022 * steal one here. If we fail to acquire one due to affinity 1023 * restrictions loop again with this cpu removed from the 1024 * set. 1025 */ 1026 if (tdq->tdq_load == 0 && tdq_move(steal, tdq) == 0) { 1027 tdq_unlock_pair(tdq, steal); 1028 continue; 1029 } 1030 spinlock_exit(); 1031 TDQ_UNLOCK(steal); 1032 mi_switch(SW_VOL | SWT_IDLE, NULL); 1033 thread_unlock(curthread); 1034 1035 return (0); 1036 } 1037 spinlock_exit(); 1038 return (1); 1039 } 1040 1041 /* 1042 * Notify a remote cpu of new work. Sends an IPI if criteria are met. 1043 */ 1044 static void 1045 tdq_notify(struct tdq *tdq, struct thread *td) 1046 { 1047 struct thread *ctd; 1048 int pri; 1049 int cpu; 1050 1051 if (tdq->tdq_ipipending) 1052 return; 1053 cpu = td->td_sched->ts_cpu; 1054 pri = td->td_priority; 1055 ctd = pcpu_find(cpu)->pc_curthread; 1056 if (!sched_shouldpreempt(pri, ctd->td_priority, 1)) 1057 return; 1058 if (TD_IS_IDLETHREAD(ctd)) { 1059 /* 1060 * If the MD code has an idle wakeup routine try that before 1061 * falling back to IPI. 1062 */ 1063 if (!tdq->tdq_cpu_idle || cpu_idle_wakeup(cpu)) 1064 return; 1065 } 1066 tdq->tdq_ipipending = 1; 1067 ipi_cpu(cpu, IPI_PREEMPT); 1068 } 1069 1070 /* 1071 * Steals load from a timeshare queue. Honors the rotating queue head 1072 * index. 1073 */ 1074 static struct thread * 1075 runq_steal_from(struct runq *rq, int cpu, u_char start) 1076 { 1077 struct rqbits *rqb; 1078 struct rqhead *rqh; 1079 struct thread *td, *first; 1080 int bit; 1081 int pri; 1082 int i; 1083 1084 rqb = &rq->rq_status; 1085 bit = start & (RQB_BPW -1); 1086 pri = 0; 1087 first = NULL; 1088 again: 1089 for (i = RQB_WORD(start); i < RQB_LEN; bit = 0, i++) { 1090 if (rqb->rqb_bits[i] == 0) 1091 continue; 1092 if (bit != 0) { 1093 for (pri = bit; pri < RQB_BPW; pri++) 1094 if (rqb->rqb_bits[i] & (1ul << pri)) 1095 break; 1096 if (pri >= RQB_BPW) 1097 continue; 1098 } else 1099 pri = RQB_FFS(rqb->rqb_bits[i]); 1100 pri += (i << RQB_L2BPW); 1101 rqh = &rq->rq_queues[pri]; 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 if (start != 0) { 1110 start = 0; 1111 goto again; 1112 } 1113 1114 if (first && THREAD_CAN_MIGRATE(first) && 1115 THREAD_CAN_SCHED(first, cpu)) 1116 return (first); 1117 return (NULL); 1118 } 1119 1120 /* 1121 * Steals load from a standard linear queue. 1122 */ 1123 static struct thread * 1124 runq_steal(struct runq *rq, int cpu) 1125 { 1126 struct rqhead *rqh; 1127 struct rqbits *rqb; 1128 struct thread *td; 1129 int word; 1130 int bit; 1131 1132 rqb = &rq->rq_status; 1133 for (word = 0; word < RQB_LEN; word++) { 1134 if (rqb->rqb_bits[word] == 0) 1135 continue; 1136 for (bit = 0; bit < RQB_BPW; bit++) { 1137 if ((rqb->rqb_bits[word] & (1ul << bit)) == 0) 1138 continue; 1139 rqh = &rq->rq_queues[bit + (word << RQB_L2BPW)]; 1140 TAILQ_FOREACH(td, rqh, td_runq) 1141 if (THREAD_CAN_MIGRATE(td) && 1142 THREAD_CAN_SCHED(td, cpu)) 1143 return (td); 1144 } 1145 } 1146 return (NULL); 1147 } 1148 1149 /* 1150 * Attempt to steal a thread in priority order from a thread queue. 1151 */ 1152 static struct thread * 1153 tdq_steal(struct tdq *tdq, int cpu) 1154 { 1155 struct thread *td; 1156 1157 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1158 if ((td = runq_steal(&tdq->tdq_realtime, cpu)) != NULL) 1159 return (td); 1160 if ((td = runq_steal_from(&tdq->tdq_timeshare, 1161 cpu, tdq->tdq_ridx)) != NULL) 1162 return (td); 1163 return (runq_steal(&tdq->tdq_idle, cpu)); 1164 } 1165 1166 /* 1167 * Sets the thread lock and ts_cpu to match the requested cpu. Unlocks the 1168 * current lock and returns with the assigned queue locked. 1169 */ 1170 static inline struct tdq * 1171 sched_setcpu(struct thread *td, int cpu, int flags) 1172 { 1173 1174 struct tdq *tdq; 1175 1176 THREAD_LOCK_ASSERT(td, MA_OWNED); 1177 tdq = TDQ_CPU(cpu); 1178 td->td_sched->ts_cpu = cpu; 1179 /* 1180 * If the lock matches just return the queue. 1181 */ 1182 if (td->td_lock == TDQ_LOCKPTR(tdq)) 1183 return (tdq); 1184 #ifdef notyet 1185 /* 1186 * If the thread isn't running its lockptr is a 1187 * turnstile or a sleepqueue. We can just lock_set without 1188 * blocking. 1189 */ 1190 if (TD_CAN_RUN(td)) { 1191 TDQ_LOCK(tdq); 1192 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 1193 return (tdq); 1194 } 1195 #endif 1196 /* 1197 * The hard case, migration, we need to block the thread first to 1198 * prevent order reversals with other cpus locks. 1199 */ 1200 spinlock_enter(); 1201 thread_lock_block(td); 1202 TDQ_LOCK(tdq); 1203 thread_lock_unblock(td, TDQ_LOCKPTR(tdq)); 1204 spinlock_exit(); 1205 return (tdq); 1206 } 1207 1208 SCHED_STAT_DEFINE(pickcpu_intrbind, "Soft interrupt binding"); 1209 SCHED_STAT_DEFINE(pickcpu_idle_affinity, "Picked idle cpu based on affinity"); 1210 SCHED_STAT_DEFINE(pickcpu_affinity, "Picked cpu based on affinity"); 1211 SCHED_STAT_DEFINE(pickcpu_lowest, "Selected lowest load"); 1212 SCHED_STAT_DEFINE(pickcpu_local, "Migrated to current cpu"); 1213 SCHED_STAT_DEFINE(pickcpu_migration, "Selection may have caused migration"); 1214 1215 static int 1216 sched_pickcpu(struct thread *td, int flags) 1217 { 1218 struct cpu_group *cg, *ccg; 1219 struct td_sched *ts; 1220 struct tdq *tdq; 1221 cpuset_t mask; 1222 int cpu, pri, self; 1223 1224 self = PCPU_GET(cpuid); 1225 ts = td->td_sched; 1226 if (smp_started == 0) 1227 return (self); 1228 /* 1229 * Don't migrate a running thread from sched_switch(). 1230 */ 1231 if ((flags & SRQ_OURSELF) || !THREAD_CAN_MIGRATE(td)) 1232 return (ts->ts_cpu); 1233 /* 1234 * Prefer to run interrupt threads on the processors that generate 1235 * the interrupt. 1236 */ 1237 pri = td->td_priority; 1238 if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_SCHED(td, self) && 1239 curthread->td_intr_nesting_level && ts->ts_cpu != self) { 1240 SCHED_STAT_INC(pickcpu_intrbind); 1241 ts->ts_cpu = self; 1242 if (TDQ_CPU(self)->tdq_lowpri > pri) { 1243 SCHED_STAT_INC(pickcpu_affinity); 1244 return (ts->ts_cpu); 1245 } 1246 } 1247 /* 1248 * If the thread can run on the last cpu and the affinity has not 1249 * expired or it is idle run it there. 1250 */ 1251 tdq = TDQ_CPU(ts->ts_cpu); 1252 cg = tdq->tdq_cg; 1253 if (THREAD_CAN_SCHED(td, ts->ts_cpu) && 1254 tdq->tdq_lowpri >= PRI_MIN_IDLE && 1255 SCHED_AFFINITY(ts, CG_SHARE_L2)) { 1256 if (cg->cg_flags & CG_FLAG_THREAD) { 1257 CPUSET_FOREACH(cpu, cg->cg_mask) { 1258 if (TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE) 1259 break; 1260 } 1261 } else 1262 cpu = INT_MAX; 1263 if (cpu > mp_maxid) { 1264 SCHED_STAT_INC(pickcpu_idle_affinity); 1265 return (ts->ts_cpu); 1266 } 1267 } 1268 /* 1269 * Search for the last level cache CPU group in the tree. 1270 * Skip caches with expired affinity time and SMT groups. 1271 * Affinity to higher level caches will be handled less aggressively. 1272 */ 1273 for (ccg = NULL; cg != NULL; cg = cg->cg_parent) { 1274 if (cg->cg_flags & CG_FLAG_THREAD) 1275 continue; 1276 if (!SCHED_AFFINITY(ts, cg->cg_level)) 1277 continue; 1278 ccg = cg; 1279 } 1280 if (ccg != NULL) 1281 cg = ccg; 1282 cpu = -1; 1283 /* Search the group for the less loaded idle CPU we can run now. */ 1284 mask = td->td_cpuset->cs_mask; 1285 if (cg != NULL && cg != cpu_top && 1286 CPU_CMP(&cg->cg_mask, &cpu_top->cg_mask) != 0) 1287 cpu = sched_lowest(cg, mask, max(pri, PRI_MAX_TIMESHARE), 1288 INT_MAX, ts->ts_cpu); 1289 /* Search globally for the less loaded CPU we can run now. */ 1290 if (cpu == -1) 1291 cpu = sched_lowest(cpu_top, mask, pri, INT_MAX, ts->ts_cpu); 1292 /* Search globally for the less loaded CPU. */ 1293 if (cpu == -1) 1294 cpu = sched_lowest(cpu_top, mask, -1, INT_MAX, ts->ts_cpu); 1295 KASSERT(cpu != -1, ("sched_pickcpu: Failed to find a cpu.")); 1296 /* 1297 * Compare the lowest loaded cpu to current cpu. 1298 */ 1299 if (THREAD_CAN_SCHED(td, self) && TDQ_CPU(self)->tdq_lowpri > pri && 1300 TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE && 1301 TDQ_CPU(self)->tdq_load <= TDQ_CPU(cpu)->tdq_load + 1) { 1302 SCHED_STAT_INC(pickcpu_local); 1303 cpu = self; 1304 } else 1305 SCHED_STAT_INC(pickcpu_lowest); 1306 if (cpu != ts->ts_cpu) 1307 SCHED_STAT_INC(pickcpu_migration); 1308 return (cpu); 1309 } 1310 #endif 1311 1312 /* 1313 * Pick the highest priority task we have and return it. 1314 */ 1315 static struct thread * 1316 tdq_choose(struct tdq *tdq) 1317 { 1318 struct thread *td; 1319 1320 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1321 td = runq_choose(&tdq->tdq_realtime); 1322 if (td != NULL) 1323 return (td); 1324 td = runq_choose_from(&tdq->tdq_timeshare, tdq->tdq_ridx); 1325 if (td != NULL) { 1326 KASSERT(td->td_priority >= PRI_MIN_BATCH, 1327 ("tdq_choose: Invalid priority on timeshare queue %d", 1328 td->td_priority)); 1329 return (td); 1330 } 1331 td = runq_choose(&tdq->tdq_idle); 1332 if (td != NULL) { 1333 KASSERT(td->td_priority >= PRI_MIN_IDLE, 1334 ("tdq_choose: Invalid priority on idle queue %d", 1335 td->td_priority)); 1336 return (td); 1337 } 1338 1339 return (NULL); 1340 } 1341 1342 /* 1343 * Initialize a thread queue. 1344 */ 1345 static void 1346 tdq_setup(struct tdq *tdq) 1347 { 1348 1349 if (bootverbose) 1350 printf("ULE: setup cpu %d\n", TDQ_ID(tdq)); 1351 runq_init(&tdq->tdq_realtime); 1352 runq_init(&tdq->tdq_timeshare); 1353 runq_init(&tdq->tdq_idle); 1354 snprintf(tdq->tdq_name, sizeof(tdq->tdq_name), 1355 "sched lock %d", (int)TDQ_ID(tdq)); 1356 mtx_init(&tdq->tdq_lock, tdq->tdq_name, "sched lock", 1357 MTX_SPIN | MTX_RECURSE); 1358 #ifdef KTR 1359 snprintf(tdq->tdq_loadname, sizeof(tdq->tdq_loadname), 1360 "CPU %d load", (int)TDQ_ID(tdq)); 1361 #endif 1362 } 1363 1364 #ifdef SMP 1365 static void 1366 sched_setup_smp(void) 1367 { 1368 struct tdq *tdq; 1369 int i; 1370 1371 cpu_top = smp_topo(); 1372 CPU_FOREACH(i) { 1373 tdq = TDQ_CPU(i); 1374 tdq_setup(tdq); 1375 tdq->tdq_cg = smp_topo_find(cpu_top, i); 1376 if (tdq->tdq_cg == NULL) 1377 panic("Can't find cpu group for %d\n", i); 1378 } 1379 balance_tdq = TDQ_SELF(); 1380 sched_balance(); 1381 } 1382 #endif 1383 1384 /* 1385 * Setup the thread queues and initialize the topology based on MD 1386 * information. 1387 */ 1388 static void 1389 sched_setup(void *dummy) 1390 { 1391 struct tdq *tdq; 1392 1393 tdq = TDQ_SELF(); 1394 #ifdef SMP 1395 sched_setup_smp(); 1396 #else 1397 tdq_setup(tdq); 1398 #endif 1399 1400 /* Add thread0's load since it's running. */ 1401 TDQ_LOCK(tdq); 1402 thread0.td_lock = TDQ_LOCKPTR(TDQ_SELF()); 1403 tdq_load_add(tdq, &thread0); 1404 tdq->tdq_lowpri = thread0.td_priority; 1405 TDQ_UNLOCK(tdq); 1406 } 1407 1408 /* 1409 * This routine determines time constants after stathz and hz are setup. 1410 */ 1411 /* ARGSUSED */ 1412 static void 1413 sched_initticks(void *dummy) 1414 { 1415 int incr; 1416 1417 realstathz = stathz ? stathz : hz; 1418 sched_slice = realstathz / SCHED_SLICE_DEFAULT_DIVISOR; 1419 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 1420 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 1421 realstathz); 1422 1423 /* 1424 * tickincr is shifted out by 10 to avoid rounding errors due to 1425 * hz not being evenly divisible by stathz on all platforms. 1426 */ 1427 incr = (hz << SCHED_TICK_SHIFT) / realstathz; 1428 /* 1429 * This does not work for values of stathz that are more than 1430 * 1 << SCHED_TICK_SHIFT * hz. In practice this does not happen. 1431 */ 1432 if (incr == 0) 1433 incr = 1; 1434 tickincr = incr; 1435 #ifdef SMP 1436 /* 1437 * Set the default balance interval now that we know 1438 * what realstathz is. 1439 */ 1440 balance_interval = realstathz; 1441 affinity = SCHED_AFFINITY_DEFAULT; 1442 #endif 1443 if (sched_idlespinthresh < 0) 1444 sched_idlespinthresh = 2 * max(10000, 6 * hz) / realstathz; 1445 } 1446 1447 1448 /* 1449 * This is the core of the interactivity algorithm. Determines a score based 1450 * on past behavior. It is the ratio of sleep time to run time scaled to 1451 * a [0, 100] integer. This is the voluntary sleep time of a process, which 1452 * differs from the cpu usage because it does not account for time spent 1453 * waiting on a run-queue. Would be prettier if we had floating point. 1454 */ 1455 static int 1456 sched_interact_score(struct thread *td) 1457 { 1458 struct td_sched *ts; 1459 int div; 1460 1461 ts = td->td_sched; 1462 /* 1463 * The score is only needed if this is likely to be an interactive 1464 * task. Don't go through the expense of computing it if there's 1465 * no chance. 1466 */ 1467 if (sched_interact <= SCHED_INTERACT_HALF && 1468 ts->ts_runtime >= ts->ts_slptime) 1469 return (SCHED_INTERACT_HALF); 1470 1471 if (ts->ts_runtime > ts->ts_slptime) { 1472 div = max(1, ts->ts_runtime / SCHED_INTERACT_HALF); 1473 return (SCHED_INTERACT_HALF + 1474 (SCHED_INTERACT_HALF - (ts->ts_slptime / div))); 1475 } 1476 if (ts->ts_slptime > ts->ts_runtime) { 1477 div = max(1, ts->ts_slptime / SCHED_INTERACT_HALF); 1478 return (ts->ts_runtime / div); 1479 } 1480 /* runtime == slptime */ 1481 if (ts->ts_runtime) 1482 return (SCHED_INTERACT_HALF); 1483 1484 /* 1485 * This can happen if slptime and runtime are 0. 1486 */ 1487 return (0); 1488 1489 } 1490 1491 /* 1492 * Scale the scheduling priority according to the "interactivity" of this 1493 * process. 1494 */ 1495 static void 1496 sched_priority(struct thread *td) 1497 { 1498 int score; 1499 int pri; 1500 1501 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 1502 return; 1503 /* 1504 * If the score is interactive we place the thread in the realtime 1505 * queue with a priority that is less than kernel and interrupt 1506 * priorities. These threads are not subject to nice restrictions. 1507 * 1508 * Scores greater than this are placed on the normal timeshare queue 1509 * where the priority is partially decided by the most recent cpu 1510 * utilization and the rest is decided by nice value. 1511 * 1512 * The nice value of the process has a linear effect on the calculated 1513 * score. Negative nice values make it easier for a thread to be 1514 * considered interactive. 1515 */ 1516 score = imax(0, sched_interact_score(td) + td->td_proc->p_nice); 1517 if (score < sched_interact) { 1518 pri = PRI_MIN_INTERACT; 1519 pri += ((PRI_MAX_INTERACT - PRI_MIN_INTERACT + 1) / 1520 sched_interact) * score; 1521 KASSERT(pri >= PRI_MIN_INTERACT && pri <= PRI_MAX_INTERACT, 1522 ("sched_priority: invalid interactive priority %d score %d", 1523 pri, score)); 1524 } else { 1525 pri = SCHED_PRI_MIN; 1526 if (td->td_sched->ts_ticks) 1527 pri += min(SCHED_PRI_TICKS(td->td_sched), 1528 SCHED_PRI_RANGE); 1529 pri += SCHED_PRI_NICE(td->td_proc->p_nice); 1530 KASSERT(pri >= PRI_MIN_BATCH && pri <= PRI_MAX_BATCH, 1531 ("sched_priority: invalid priority %d: nice %d, " 1532 "ticks %d ftick %d ltick %d tick pri %d", 1533 pri, td->td_proc->p_nice, td->td_sched->ts_ticks, 1534 td->td_sched->ts_ftick, td->td_sched->ts_ltick, 1535 SCHED_PRI_TICKS(td->td_sched))); 1536 } 1537 sched_user_prio(td, pri); 1538 1539 return; 1540 } 1541 1542 /* 1543 * This routine enforces a maximum limit on the amount of scheduling history 1544 * kept. It is called after either the slptime or runtime is adjusted. This 1545 * function is ugly due to integer math. 1546 */ 1547 static void 1548 sched_interact_update(struct thread *td) 1549 { 1550 struct td_sched *ts; 1551 u_int sum; 1552 1553 ts = td->td_sched; 1554 sum = ts->ts_runtime + ts->ts_slptime; 1555 if (sum < SCHED_SLP_RUN_MAX) 1556 return; 1557 /* 1558 * This only happens from two places: 1559 * 1) We have added an unusual amount of run time from fork_exit. 1560 * 2) We have added an unusual amount of sleep time from sched_sleep(). 1561 */ 1562 if (sum > SCHED_SLP_RUN_MAX * 2) { 1563 if (ts->ts_runtime > ts->ts_slptime) { 1564 ts->ts_runtime = SCHED_SLP_RUN_MAX; 1565 ts->ts_slptime = 1; 1566 } else { 1567 ts->ts_slptime = SCHED_SLP_RUN_MAX; 1568 ts->ts_runtime = 1; 1569 } 1570 return; 1571 } 1572 /* 1573 * If we have exceeded by more than 1/5th then the algorithm below 1574 * will not bring us back into range. Dividing by two here forces 1575 * us into the range of [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX] 1576 */ 1577 if (sum > (SCHED_SLP_RUN_MAX / 5) * 6) { 1578 ts->ts_runtime /= 2; 1579 ts->ts_slptime /= 2; 1580 return; 1581 } 1582 ts->ts_runtime = (ts->ts_runtime / 5) * 4; 1583 ts->ts_slptime = (ts->ts_slptime / 5) * 4; 1584 } 1585 1586 /* 1587 * Scale back the interactivity history when a child thread is created. The 1588 * history is inherited from the parent but the thread may behave totally 1589 * differently. For example, a shell spawning a compiler process. We want 1590 * to learn that the compiler is behaving badly very quickly. 1591 */ 1592 static void 1593 sched_interact_fork(struct thread *td) 1594 { 1595 int ratio; 1596 int sum; 1597 1598 sum = td->td_sched->ts_runtime + td->td_sched->ts_slptime; 1599 if (sum > SCHED_SLP_RUN_FORK) { 1600 ratio = sum / SCHED_SLP_RUN_FORK; 1601 td->td_sched->ts_runtime /= ratio; 1602 td->td_sched->ts_slptime /= ratio; 1603 } 1604 } 1605 1606 /* 1607 * Called from proc0_init() to setup the scheduler fields. 1608 */ 1609 void 1610 schedinit(void) 1611 { 1612 1613 /* 1614 * Set up the scheduler specific parts of proc0. 1615 */ 1616 proc0.p_sched = NULL; /* XXX */ 1617 thread0.td_sched = &td_sched0; 1618 td_sched0.ts_ltick = ticks; 1619 td_sched0.ts_ftick = ticks; 1620 td_sched0.ts_slice = 0; 1621 } 1622 1623 /* 1624 * This is only somewhat accurate since given many processes of the same 1625 * priority they will switch when their slices run out, which will be 1626 * at most sched_slice stathz ticks. 1627 */ 1628 int 1629 sched_rr_interval(void) 1630 { 1631 1632 /* Convert sched_slice from stathz to hz. */ 1633 return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz)); 1634 } 1635 1636 /* 1637 * Update the percent cpu tracking information when it is requested or 1638 * the total history exceeds the maximum. We keep a sliding history of 1639 * tick counts that slowly decays. This is less precise than the 4BSD 1640 * mechanism since it happens with less regular and frequent events. 1641 */ 1642 static void 1643 sched_pctcpu_update(struct td_sched *ts, int run) 1644 { 1645 int t = ticks; 1646 1647 if (t - ts->ts_ltick >= SCHED_TICK_TARG) { 1648 ts->ts_ticks = 0; 1649 ts->ts_ftick = t - SCHED_TICK_TARG; 1650 } else if (t - ts->ts_ftick >= SCHED_TICK_MAX) { 1651 ts->ts_ticks = (ts->ts_ticks / (ts->ts_ltick - ts->ts_ftick)) * 1652 (ts->ts_ltick - (t - SCHED_TICK_TARG)); 1653 ts->ts_ftick = t - SCHED_TICK_TARG; 1654 } 1655 if (run) 1656 ts->ts_ticks += (t - ts->ts_ltick) << SCHED_TICK_SHIFT; 1657 ts->ts_ltick = t; 1658 } 1659 1660 /* 1661 * Adjust the priority of a thread. Move it to the appropriate run-queue 1662 * if necessary. This is the back-end for several priority related 1663 * functions. 1664 */ 1665 static void 1666 sched_thread_priority(struct thread *td, u_char prio) 1667 { 1668 struct td_sched *ts; 1669 struct tdq *tdq; 1670 int oldpri; 1671 1672 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "prio", 1673 "prio:%d", td->td_priority, "new prio:%d", prio, 1674 KTR_ATTR_LINKED, sched_tdname(curthread)); 1675 SDT_PROBE3(sched, , , change_pri, td, td->td_proc, prio); 1676 if (td != curthread && prio < td->td_priority) { 1677 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread), 1678 "lend prio", "prio:%d", td->td_priority, "new prio:%d", 1679 prio, KTR_ATTR_LINKED, sched_tdname(td)); 1680 SDT_PROBE4(sched, , , lend_pri, td, td->td_proc, prio, 1681 curthread); 1682 } 1683 ts = td->td_sched; 1684 THREAD_LOCK_ASSERT(td, MA_OWNED); 1685 if (td->td_priority == prio) 1686 return; 1687 /* 1688 * If the priority has been elevated due to priority 1689 * propagation, we may have to move ourselves to a new 1690 * queue. This could be optimized to not re-add in some 1691 * cases. 1692 */ 1693 if (TD_ON_RUNQ(td) && prio < td->td_priority) { 1694 sched_rem(td); 1695 td->td_priority = prio; 1696 sched_add(td, SRQ_BORROWING); 1697 return; 1698 } 1699 /* 1700 * If the thread is currently running we may have to adjust the lowpri 1701 * information so other cpus are aware of our current priority. 1702 */ 1703 if (TD_IS_RUNNING(td)) { 1704 tdq = TDQ_CPU(ts->ts_cpu); 1705 oldpri = td->td_priority; 1706 td->td_priority = prio; 1707 if (prio < tdq->tdq_lowpri) 1708 tdq->tdq_lowpri = prio; 1709 else if (tdq->tdq_lowpri == oldpri) 1710 tdq_setlowpri(tdq, td); 1711 return; 1712 } 1713 td->td_priority = prio; 1714 } 1715 1716 /* 1717 * Update a thread's priority when it is lent another thread's 1718 * priority. 1719 */ 1720 void 1721 sched_lend_prio(struct thread *td, u_char prio) 1722 { 1723 1724 td->td_flags |= TDF_BORROWING; 1725 sched_thread_priority(td, prio); 1726 } 1727 1728 /* 1729 * Restore a thread's priority when priority propagation is 1730 * over. The prio argument is the minimum priority the thread 1731 * needs to have to satisfy other possible priority lending 1732 * requests. If the thread's regular priority is less 1733 * important than prio, the thread will keep a priority boost 1734 * of prio. 1735 */ 1736 void 1737 sched_unlend_prio(struct thread *td, u_char prio) 1738 { 1739 u_char base_pri; 1740 1741 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 1742 td->td_base_pri <= PRI_MAX_TIMESHARE) 1743 base_pri = td->td_user_pri; 1744 else 1745 base_pri = td->td_base_pri; 1746 if (prio >= base_pri) { 1747 td->td_flags &= ~TDF_BORROWING; 1748 sched_thread_priority(td, base_pri); 1749 } else 1750 sched_lend_prio(td, prio); 1751 } 1752 1753 /* 1754 * Standard entry for setting the priority to an absolute value. 1755 */ 1756 void 1757 sched_prio(struct thread *td, u_char prio) 1758 { 1759 u_char oldprio; 1760 1761 /* First, update the base priority. */ 1762 td->td_base_pri = prio; 1763 1764 /* 1765 * If the thread is borrowing another thread's priority, don't 1766 * ever lower the priority. 1767 */ 1768 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 1769 return; 1770 1771 /* Change the real priority. */ 1772 oldprio = td->td_priority; 1773 sched_thread_priority(td, prio); 1774 1775 /* 1776 * If the thread is on a turnstile, then let the turnstile update 1777 * its state. 1778 */ 1779 if (TD_ON_LOCK(td) && oldprio != prio) 1780 turnstile_adjust(td, oldprio); 1781 } 1782 1783 /* 1784 * Set the base user priority, does not effect current running priority. 1785 */ 1786 void 1787 sched_user_prio(struct thread *td, u_char prio) 1788 { 1789 1790 td->td_base_user_pri = prio; 1791 if (td->td_lend_user_pri <= prio) 1792 return; 1793 td->td_user_pri = prio; 1794 } 1795 1796 void 1797 sched_lend_user_prio(struct thread *td, u_char prio) 1798 { 1799 1800 THREAD_LOCK_ASSERT(td, MA_OWNED); 1801 td->td_lend_user_pri = prio; 1802 td->td_user_pri = min(prio, td->td_base_user_pri); 1803 if (td->td_priority > td->td_user_pri) 1804 sched_prio(td, td->td_user_pri); 1805 else if (td->td_priority != td->td_user_pri) 1806 td->td_flags |= TDF_NEEDRESCHED; 1807 } 1808 1809 /* 1810 * Handle migration from sched_switch(). This happens only for 1811 * cpu binding. 1812 */ 1813 static struct mtx * 1814 sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags) 1815 { 1816 struct tdq *tdn; 1817 1818 tdn = TDQ_CPU(td->td_sched->ts_cpu); 1819 #ifdef SMP 1820 tdq_load_rem(tdq, td); 1821 /* 1822 * Do the lock dance required to avoid LOR. We grab an extra 1823 * spinlock nesting to prevent preemption while we're 1824 * not holding either run-queue lock. 1825 */ 1826 spinlock_enter(); 1827 thread_lock_block(td); /* This releases the lock on tdq. */ 1828 1829 /* 1830 * Acquire both run-queue locks before placing the thread on the new 1831 * run-queue to avoid deadlocks created by placing a thread with a 1832 * blocked lock on the run-queue of a remote processor. The deadlock 1833 * occurs when a third processor attempts to lock the two queues in 1834 * question while the target processor is spinning with its own 1835 * run-queue lock held while waiting for the blocked lock to clear. 1836 */ 1837 tdq_lock_pair(tdn, tdq); 1838 tdq_add(tdn, td, flags); 1839 tdq_notify(tdn, td); 1840 TDQ_UNLOCK(tdn); 1841 spinlock_exit(); 1842 #endif 1843 return (TDQ_LOCKPTR(tdn)); 1844 } 1845 1846 /* 1847 * Variadic version of thread_lock_unblock() that does not assume td_lock 1848 * is blocked. 1849 */ 1850 static inline void 1851 thread_unblock_switch(struct thread *td, struct mtx *mtx) 1852 { 1853 atomic_store_rel_ptr((volatile uintptr_t *)&td->td_lock, 1854 (uintptr_t)mtx); 1855 } 1856 1857 /* 1858 * Switch threads. This function has to handle threads coming in while 1859 * blocked for some reason, running, or idle. It also must deal with 1860 * migrating a thread from one queue to another as running threads may 1861 * be assigned elsewhere via binding. 1862 */ 1863 void 1864 sched_switch(struct thread *td, struct thread *newtd, int flags) 1865 { 1866 struct tdq *tdq; 1867 struct td_sched *ts; 1868 struct mtx *mtx; 1869 int srqflag; 1870 int cpuid, preempted; 1871 1872 THREAD_LOCK_ASSERT(td, MA_OWNED); 1873 KASSERT(newtd == NULL, ("sched_switch: Unsupported newtd argument")); 1874 1875 cpuid = PCPU_GET(cpuid); 1876 tdq = TDQ_CPU(cpuid); 1877 ts = td->td_sched; 1878 mtx = td->td_lock; 1879 sched_pctcpu_update(ts, 1); 1880 ts->ts_rltick = ticks; 1881 td->td_lastcpu = td->td_oncpu; 1882 td->td_oncpu = NOCPU; 1883 preempted = !(td->td_flags & TDF_SLICEEND); 1884 td->td_flags &= ~(TDF_NEEDRESCHED | TDF_SLICEEND); 1885 td->td_owepreempt = 0; 1886 if (!TD_IS_IDLETHREAD(td)) 1887 tdq->tdq_switchcnt++; 1888 /* 1889 * The lock pointer in an idle thread should never change. Reset it 1890 * to CAN_RUN as well. 1891 */ 1892 if (TD_IS_IDLETHREAD(td)) { 1893 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1894 TD_SET_CAN_RUN(td); 1895 } else if (TD_IS_RUNNING(td)) { 1896 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1897 srqflag = preempted ? 1898 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 1899 SRQ_OURSELF|SRQ_YIELDING; 1900 #ifdef SMP 1901 if (THREAD_CAN_MIGRATE(td) && !THREAD_CAN_SCHED(td, ts->ts_cpu)) 1902 ts->ts_cpu = sched_pickcpu(td, 0); 1903 #endif 1904 if (ts->ts_cpu == cpuid) 1905 tdq_runq_add(tdq, td, srqflag); 1906 else { 1907 KASSERT(THREAD_CAN_MIGRATE(td) || 1908 (ts->ts_flags & TSF_BOUND) != 0, 1909 ("Thread %p shouldn't migrate", td)); 1910 mtx = sched_switch_migrate(tdq, td, srqflag); 1911 } 1912 } else { 1913 /* This thread must be going to sleep. */ 1914 TDQ_LOCK(tdq); 1915 mtx = thread_lock_block(td); 1916 tdq_load_rem(tdq, td); 1917 } 1918 /* 1919 * We enter here with the thread blocked and assigned to the 1920 * appropriate cpu run-queue or sleep-queue and with the current 1921 * thread-queue locked. 1922 */ 1923 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 1924 newtd = choosethread(); 1925 /* 1926 * Call the MD code to switch contexts if necessary. 1927 */ 1928 if (td != newtd) { 1929 #ifdef HWPMC_HOOKS 1930 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1931 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 1932 #endif 1933 SDT_PROBE2(sched, , , off_cpu, newtd, newtd->td_proc); 1934 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 1935 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 1936 sched_pctcpu_update(newtd->td_sched, 0); 1937 1938 #ifdef KDTRACE_HOOKS 1939 /* 1940 * If DTrace has set the active vtime enum to anything 1941 * other than INACTIVE (0), then it should have set the 1942 * function to call. 1943 */ 1944 if (dtrace_vtime_active) 1945 (*dtrace_vtime_switch_func)(newtd); 1946 #endif 1947 1948 cpu_switch(td, newtd, mtx); 1949 /* 1950 * We may return from cpu_switch on a different cpu. However, 1951 * we always return with td_lock pointing to the current cpu's 1952 * run queue lock. 1953 */ 1954 cpuid = PCPU_GET(cpuid); 1955 tdq = TDQ_CPU(cpuid); 1956 lock_profile_obtain_lock_success( 1957 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 1958 1959 SDT_PROBE0(sched, , , on_cpu); 1960 #ifdef HWPMC_HOOKS 1961 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1962 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 1963 #endif 1964 } else { 1965 thread_unblock_switch(td, mtx); 1966 SDT_PROBE0(sched, , , remain_cpu); 1967 } 1968 /* 1969 * Assert that all went well and return. 1970 */ 1971 TDQ_LOCK_ASSERT(tdq, MA_OWNED|MA_NOTRECURSED); 1972 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1973 td->td_oncpu = cpuid; 1974 } 1975 1976 /* 1977 * Adjust thread priorities as a result of a nice request. 1978 */ 1979 void 1980 sched_nice(struct proc *p, int nice) 1981 { 1982 struct thread *td; 1983 1984 PROC_LOCK_ASSERT(p, MA_OWNED); 1985 1986 p->p_nice = nice; 1987 FOREACH_THREAD_IN_PROC(p, td) { 1988 thread_lock(td); 1989 sched_priority(td); 1990 sched_prio(td, td->td_base_user_pri); 1991 thread_unlock(td); 1992 } 1993 } 1994 1995 /* 1996 * Record the sleep time for the interactivity scorer. 1997 */ 1998 void 1999 sched_sleep(struct thread *td, int prio) 2000 { 2001 2002 THREAD_LOCK_ASSERT(td, MA_OWNED); 2003 2004 td->td_slptick = ticks; 2005 if (TD_IS_SUSPENDED(td) || prio >= PSOCK) 2006 td->td_flags |= TDF_CANSWAP; 2007 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 2008 return; 2009 if (static_boost == 1 && prio) 2010 sched_prio(td, prio); 2011 else if (static_boost && td->td_priority > static_boost) 2012 sched_prio(td, static_boost); 2013 } 2014 2015 /* 2016 * Schedule a thread to resume execution and record how long it voluntarily 2017 * slept. We also update the pctcpu, interactivity, and priority. 2018 */ 2019 void 2020 sched_wakeup(struct thread *td) 2021 { 2022 struct td_sched *ts; 2023 int slptick; 2024 2025 THREAD_LOCK_ASSERT(td, MA_OWNED); 2026 ts = td->td_sched; 2027 td->td_flags &= ~TDF_CANSWAP; 2028 /* 2029 * If we slept for more than a tick update our interactivity and 2030 * priority. 2031 */ 2032 slptick = td->td_slptick; 2033 td->td_slptick = 0; 2034 if (slptick && slptick != ticks) { 2035 ts->ts_slptime += (ticks - slptick) << SCHED_TICK_SHIFT; 2036 sched_interact_update(td); 2037 sched_pctcpu_update(ts, 0); 2038 } 2039 /* 2040 * Reset the slice value since we slept and advanced the round-robin. 2041 */ 2042 ts->ts_slice = 0; 2043 sched_add(td, SRQ_BORING); 2044 } 2045 2046 /* 2047 * Penalize the parent for creating a new child and initialize the child's 2048 * priority. 2049 */ 2050 void 2051 sched_fork(struct thread *td, struct thread *child) 2052 { 2053 THREAD_LOCK_ASSERT(td, MA_OWNED); 2054 sched_pctcpu_update(td->td_sched, 1); 2055 sched_fork_thread(td, child); 2056 /* 2057 * Penalize the parent and child for forking. 2058 */ 2059 sched_interact_fork(child); 2060 sched_priority(child); 2061 td->td_sched->ts_runtime += tickincr; 2062 sched_interact_update(td); 2063 sched_priority(td); 2064 } 2065 2066 /* 2067 * Fork a new thread, may be within the same process. 2068 */ 2069 void 2070 sched_fork_thread(struct thread *td, struct thread *child) 2071 { 2072 struct td_sched *ts; 2073 struct td_sched *ts2; 2074 struct tdq *tdq; 2075 2076 tdq = TDQ_SELF(); 2077 THREAD_LOCK_ASSERT(td, MA_OWNED); 2078 /* 2079 * Initialize child. 2080 */ 2081 ts = td->td_sched; 2082 ts2 = child->td_sched; 2083 child->td_lock = TDQ_LOCKPTR(tdq); 2084 child->td_cpuset = cpuset_ref(td->td_cpuset); 2085 ts2->ts_cpu = ts->ts_cpu; 2086 ts2->ts_flags = 0; 2087 /* 2088 * Grab our parents cpu estimation information. 2089 */ 2090 ts2->ts_ticks = ts->ts_ticks; 2091 ts2->ts_ltick = ts->ts_ltick; 2092 ts2->ts_ftick = ts->ts_ftick; 2093 /* 2094 * Do not inherit any borrowed priority from the parent. 2095 */ 2096 child->td_priority = child->td_base_pri; 2097 /* 2098 * And update interactivity score. 2099 */ 2100 ts2->ts_slptime = ts->ts_slptime; 2101 ts2->ts_runtime = ts->ts_runtime; 2102 /* Attempt to quickly learn interactivity. */ 2103 ts2->ts_slice = tdq_slice(tdq) - sched_slice_min; 2104 #ifdef KTR 2105 bzero(ts2->ts_name, sizeof(ts2->ts_name)); 2106 #endif 2107 } 2108 2109 /* 2110 * Adjust the priority class of a thread. 2111 */ 2112 void 2113 sched_class(struct thread *td, int class) 2114 { 2115 2116 THREAD_LOCK_ASSERT(td, MA_OWNED); 2117 if (td->td_pri_class == class) 2118 return; 2119 td->td_pri_class = class; 2120 } 2121 2122 /* 2123 * Return some of the child's priority and interactivity to the parent. 2124 */ 2125 void 2126 sched_exit(struct proc *p, struct thread *child) 2127 { 2128 struct thread *td; 2129 2130 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "proc exit", 2131 "prio:%d", child->td_priority); 2132 PROC_LOCK_ASSERT(p, MA_OWNED); 2133 td = FIRST_THREAD_IN_PROC(p); 2134 sched_exit_thread(td, child); 2135 } 2136 2137 /* 2138 * Penalize another thread for the time spent on this one. This helps to 2139 * worsen the priority and interactivity of processes which schedule batch 2140 * jobs such as make. This has little effect on the make process itself but 2141 * causes new processes spawned by it to receive worse scores immediately. 2142 */ 2143 void 2144 sched_exit_thread(struct thread *td, struct thread *child) 2145 { 2146 2147 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "thread exit", 2148 "prio:%d", child->td_priority); 2149 /* 2150 * Give the child's runtime to the parent without returning the 2151 * sleep time as a penalty to the parent. This causes shells that 2152 * launch expensive things to mark their children as expensive. 2153 */ 2154 thread_lock(td); 2155 td->td_sched->ts_runtime += child->td_sched->ts_runtime; 2156 sched_interact_update(td); 2157 sched_priority(td); 2158 thread_unlock(td); 2159 } 2160 2161 void 2162 sched_preempt(struct thread *td) 2163 { 2164 struct tdq *tdq; 2165 2166 SDT_PROBE2(sched, , , surrender, td, td->td_proc); 2167 2168 thread_lock(td); 2169 tdq = TDQ_SELF(); 2170 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2171 tdq->tdq_ipipending = 0; 2172 if (td->td_priority > tdq->tdq_lowpri) { 2173 int flags; 2174 2175 flags = SW_INVOL | SW_PREEMPT; 2176 if (td->td_critnest > 1) 2177 td->td_owepreempt = 1; 2178 else if (TD_IS_IDLETHREAD(td)) 2179 mi_switch(flags | SWT_REMOTEWAKEIDLE, NULL); 2180 else 2181 mi_switch(flags | SWT_REMOTEPREEMPT, NULL); 2182 } 2183 thread_unlock(td); 2184 } 2185 2186 /* 2187 * Fix priorities on return to user-space. Priorities may be elevated due 2188 * to static priorities in msleep() or similar. 2189 */ 2190 void 2191 sched_userret(struct thread *td) 2192 { 2193 /* 2194 * XXX we cheat slightly on the locking here to avoid locking in 2195 * the usual case. Setting td_priority here is essentially an 2196 * incomplete workaround for not setting it properly elsewhere. 2197 * Now that some interrupt handlers are threads, not setting it 2198 * properly elsewhere can clobber it in the window between setting 2199 * it here and returning to user mode, so don't waste time setting 2200 * it perfectly here. 2201 */ 2202 KASSERT((td->td_flags & TDF_BORROWING) == 0, 2203 ("thread with borrowed priority returning to userland")); 2204 if (td->td_priority != td->td_user_pri) { 2205 thread_lock(td); 2206 td->td_priority = td->td_user_pri; 2207 td->td_base_pri = td->td_user_pri; 2208 tdq_setlowpri(TDQ_SELF(), td); 2209 thread_unlock(td); 2210 } 2211 } 2212 2213 /* 2214 * Handle a stathz tick. This is really only relevant for timeshare 2215 * threads. 2216 */ 2217 void 2218 sched_clock(struct thread *td) 2219 { 2220 struct tdq *tdq; 2221 struct td_sched *ts; 2222 2223 THREAD_LOCK_ASSERT(td, MA_OWNED); 2224 tdq = TDQ_SELF(); 2225 #ifdef SMP 2226 /* 2227 * We run the long term load balancer infrequently on the first cpu. 2228 */ 2229 if (balance_tdq == tdq) { 2230 if (balance_ticks && --balance_ticks == 0) 2231 sched_balance(); 2232 } 2233 #endif 2234 /* 2235 * Save the old switch count so we have a record of the last ticks 2236 * activity. Initialize the new switch count based on our load. 2237 * If there is some activity seed it to reflect that. 2238 */ 2239 tdq->tdq_oldswitchcnt = tdq->tdq_switchcnt; 2240 tdq->tdq_switchcnt = tdq->tdq_load; 2241 /* 2242 * Advance the insert index once for each tick to ensure that all 2243 * threads get a chance to run. 2244 */ 2245 if (tdq->tdq_idx == tdq->tdq_ridx) { 2246 tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS; 2247 if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx])) 2248 tdq->tdq_ridx = tdq->tdq_idx; 2249 } 2250 ts = td->td_sched; 2251 sched_pctcpu_update(ts, 1); 2252 if (td->td_pri_class & PRI_FIFO_BIT) 2253 return; 2254 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) { 2255 /* 2256 * We used a tick; charge it to the thread so 2257 * that we can compute our interactivity. 2258 */ 2259 td->td_sched->ts_runtime += tickincr; 2260 sched_interact_update(td); 2261 sched_priority(td); 2262 } 2263 2264 /* 2265 * Force a context switch if the current thread has used up a full 2266 * time slice (default is 100ms). 2267 */ 2268 if (!TD_IS_IDLETHREAD(td) && ++ts->ts_slice >= tdq_slice(tdq)) { 2269 ts->ts_slice = 0; 2270 td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND; 2271 } 2272 } 2273 2274 /* 2275 * Called once per hz tick. 2276 */ 2277 void 2278 sched_tick(int cnt) 2279 { 2280 2281 } 2282 2283 /* 2284 * Return whether the current CPU has runnable tasks. Used for in-kernel 2285 * cooperative idle threads. 2286 */ 2287 int 2288 sched_runnable(void) 2289 { 2290 struct tdq *tdq; 2291 int load; 2292 2293 load = 1; 2294 2295 tdq = TDQ_SELF(); 2296 if ((curthread->td_flags & TDF_IDLETD) != 0) { 2297 if (tdq->tdq_load > 0) 2298 goto out; 2299 } else 2300 if (tdq->tdq_load - 1 > 0) 2301 goto out; 2302 load = 0; 2303 out: 2304 return (load); 2305 } 2306 2307 /* 2308 * Choose the highest priority thread to run. The thread is removed from 2309 * the run-queue while running however the load remains. For SMP we set 2310 * the tdq in the global idle bitmask if it idles here. 2311 */ 2312 struct thread * 2313 sched_choose(void) 2314 { 2315 struct thread *td; 2316 struct tdq *tdq; 2317 2318 tdq = TDQ_SELF(); 2319 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2320 td = tdq_choose(tdq); 2321 if (td) { 2322 tdq_runq_rem(tdq, td); 2323 tdq->tdq_lowpri = td->td_priority; 2324 return (td); 2325 } 2326 tdq->tdq_lowpri = PRI_MAX_IDLE; 2327 return (PCPU_GET(idlethread)); 2328 } 2329 2330 /* 2331 * Set owepreempt if necessary. Preemption never happens directly in ULE, 2332 * we always request it once we exit a critical section. 2333 */ 2334 static inline void 2335 sched_setpreempt(struct thread *td) 2336 { 2337 struct thread *ctd; 2338 int cpri; 2339 int pri; 2340 2341 THREAD_LOCK_ASSERT(curthread, MA_OWNED); 2342 2343 ctd = curthread; 2344 pri = td->td_priority; 2345 cpri = ctd->td_priority; 2346 if (pri < cpri) 2347 ctd->td_flags |= TDF_NEEDRESCHED; 2348 if (panicstr != NULL || pri >= cpri || cold || TD_IS_INHIBITED(ctd)) 2349 return; 2350 if (!sched_shouldpreempt(pri, cpri, 0)) 2351 return; 2352 ctd->td_owepreempt = 1; 2353 } 2354 2355 /* 2356 * Add a thread to a thread queue. Select the appropriate runq and add the 2357 * thread to it. This is the internal function called when the tdq is 2358 * predetermined. 2359 */ 2360 void 2361 tdq_add(struct tdq *tdq, struct thread *td, int flags) 2362 { 2363 2364 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2365 KASSERT((td->td_inhibitors == 0), 2366 ("sched_add: trying to run inhibited thread")); 2367 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 2368 ("sched_add: bad thread state")); 2369 KASSERT(td->td_flags & TDF_INMEM, 2370 ("sched_add: thread swapped out")); 2371 2372 if (td->td_priority < tdq->tdq_lowpri) 2373 tdq->tdq_lowpri = td->td_priority; 2374 tdq_runq_add(tdq, td, flags); 2375 tdq_load_add(tdq, td); 2376 } 2377 2378 /* 2379 * Select the target thread queue and add a thread to it. Request 2380 * preemption or IPI a remote processor if required. 2381 */ 2382 void 2383 sched_add(struct thread *td, int flags) 2384 { 2385 struct tdq *tdq; 2386 #ifdef SMP 2387 int cpu; 2388 #endif 2389 2390 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 2391 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 2392 sched_tdname(curthread)); 2393 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 2394 KTR_ATTR_LINKED, sched_tdname(td)); 2395 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 2396 flags & SRQ_PREEMPTED); 2397 THREAD_LOCK_ASSERT(td, MA_OWNED); 2398 /* 2399 * Recalculate the priority before we select the target cpu or 2400 * run-queue. 2401 */ 2402 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 2403 sched_priority(td); 2404 #ifdef SMP 2405 /* 2406 * Pick the destination cpu and if it isn't ours transfer to the 2407 * target cpu. 2408 */ 2409 cpu = sched_pickcpu(td, flags); 2410 tdq = sched_setcpu(td, cpu, flags); 2411 tdq_add(tdq, td, flags); 2412 if (cpu != PCPU_GET(cpuid)) { 2413 tdq_notify(tdq, td); 2414 return; 2415 } 2416 #else 2417 tdq = TDQ_SELF(); 2418 TDQ_LOCK(tdq); 2419 /* 2420 * Now that the thread is moving to the run-queue, set the lock 2421 * to the scheduler's lock. 2422 */ 2423 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 2424 tdq_add(tdq, td, flags); 2425 #endif 2426 if (!(flags & SRQ_YIELDING)) 2427 sched_setpreempt(td); 2428 } 2429 2430 /* 2431 * Remove a thread from a run-queue without running it. This is used 2432 * when we're stealing a thread from a remote queue. Otherwise all threads 2433 * exit by calling sched_exit_thread() and sched_throw() themselves. 2434 */ 2435 void 2436 sched_rem(struct thread *td) 2437 { 2438 struct tdq *tdq; 2439 2440 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "runq rem", 2441 "prio:%d", td->td_priority); 2442 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL); 2443 tdq = TDQ_CPU(td->td_sched->ts_cpu); 2444 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2445 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2446 KASSERT(TD_ON_RUNQ(td), 2447 ("sched_rem: thread not on run queue")); 2448 tdq_runq_rem(tdq, td); 2449 tdq_load_rem(tdq, td); 2450 TD_SET_CAN_RUN(td); 2451 if (td->td_priority == tdq->tdq_lowpri) 2452 tdq_setlowpri(tdq, NULL); 2453 } 2454 2455 /* 2456 * Fetch cpu utilization information. Updates on demand. 2457 */ 2458 fixpt_t 2459 sched_pctcpu(struct thread *td) 2460 { 2461 fixpt_t pctcpu; 2462 struct td_sched *ts; 2463 2464 pctcpu = 0; 2465 ts = td->td_sched; 2466 if (ts == NULL) 2467 return (0); 2468 2469 THREAD_LOCK_ASSERT(td, MA_OWNED); 2470 sched_pctcpu_update(ts, TD_IS_RUNNING(td)); 2471 if (ts->ts_ticks) { 2472 int rtick; 2473 2474 /* How many rtick per second ? */ 2475 rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz); 2476 pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT; 2477 } 2478 2479 return (pctcpu); 2480 } 2481 2482 /* 2483 * Enforce affinity settings for a thread. Called after adjustments to 2484 * cpumask. 2485 */ 2486 void 2487 sched_affinity(struct thread *td) 2488 { 2489 #ifdef SMP 2490 struct td_sched *ts; 2491 2492 THREAD_LOCK_ASSERT(td, MA_OWNED); 2493 ts = td->td_sched; 2494 if (THREAD_CAN_SCHED(td, ts->ts_cpu)) 2495 return; 2496 if (TD_ON_RUNQ(td)) { 2497 sched_rem(td); 2498 sched_add(td, SRQ_BORING); 2499 return; 2500 } 2501 if (!TD_IS_RUNNING(td)) 2502 return; 2503 /* 2504 * Force a switch before returning to userspace. If the 2505 * target thread is not running locally send an ipi to force 2506 * the issue. 2507 */ 2508 td->td_flags |= TDF_NEEDRESCHED; 2509 if (td != curthread) 2510 ipi_cpu(ts->ts_cpu, IPI_PREEMPT); 2511 #endif 2512 } 2513 2514 /* 2515 * Bind a thread to a target cpu. 2516 */ 2517 void 2518 sched_bind(struct thread *td, int cpu) 2519 { 2520 struct td_sched *ts; 2521 2522 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 2523 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 2524 ts = td->td_sched; 2525 if (ts->ts_flags & TSF_BOUND) 2526 sched_unbind(td); 2527 KASSERT(THREAD_CAN_MIGRATE(td), ("%p must be migratable", td)); 2528 ts->ts_flags |= TSF_BOUND; 2529 sched_pin(); 2530 if (PCPU_GET(cpuid) == cpu) 2531 return; 2532 ts->ts_cpu = cpu; 2533 /* When we return from mi_switch we'll be on the correct cpu. */ 2534 mi_switch(SW_VOL, NULL); 2535 } 2536 2537 /* 2538 * Release a bound thread. 2539 */ 2540 void 2541 sched_unbind(struct thread *td) 2542 { 2543 struct td_sched *ts; 2544 2545 THREAD_LOCK_ASSERT(td, MA_OWNED); 2546 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 2547 ts = td->td_sched; 2548 if ((ts->ts_flags & TSF_BOUND) == 0) 2549 return; 2550 ts->ts_flags &= ~TSF_BOUND; 2551 sched_unpin(); 2552 } 2553 2554 int 2555 sched_is_bound(struct thread *td) 2556 { 2557 THREAD_LOCK_ASSERT(td, MA_OWNED); 2558 return (td->td_sched->ts_flags & TSF_BOUND); 2559 } 2560 2561 /* 2562 * Basic yield call. 2563 */ 2564 void 2565 sched_relinquish(struct thread *td) 2566 { 2567 thread_lock(td); 2568 mi_switch(SW_VOL | SWT_RELINQUISH, NULL); 2569 thread_unlock(td); 2570 } 2571 2572 /* 2573 * Return the total system load. 2574 */ 2575 int 2576 sched_load(void) 2577 { 2578 #ifdef SMP 2579 int total; 2580 int i; 2581 2582 total = 0; 2583 CPU_FOREACH(i) 2584 total += TDQ_CPU(i)->tdq_sysload; 2585 return (total); 2586 #else 2587 return (TDQ_SELF()->tdq_sysload); 2588 #endif 2589 } 2590 2591 int 2592 sched_sizeof_proc(void) 2593 { 2594 return (sizeof(struct proc)); 2595 } 2596 2597 int 2598 sched_sizeof_thread(void) 2599 { 2600 return (sizeof(struct thread) + sizeof(struct td_sched)); 2601 } 2602 2603 #ifdef SMP 2604 #define TDQ_IDLESPIN(tdq) \ 2605 ((tdq)->tdq_cg != NULL && ((tdq)->tdq_cg->cg_flags & CG_FLAG_THREAD) == 0) 2606 #else 2607 #define TDQ_IDLESPIN(tdq) 1 2608 #endif 2609 2610 /* 2611 * The actual idle process. 2612 */ 2613 void 2614 sched_idletd(void *dummy) 2615 { 2616 struct thread *td; 2617 struct tdq *tdq; 2618 int oldswitchcnt, switchcnt; 2619 int i; 2620 2621 mtx_assert(&Giant, MA_NOTOWNED); 2622 td = curthread; 2623 tdq = TDQ_SELF(); 2624 THREAD_NO_SLEEPING(); 2625 oldswitchcnt = -1; 2626 for (;;) { 2627 if (tdq->tdq_load) { 2628 thread_lock(td); 2629 mi_switch(SW_VOL | SWT_IDLE, NULL); 2630 thread_unlock(td); 2631 } 2632 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2633 #ifdef SMP 2634 if (switchcnt != oldswitchcnt) { 2635 oldswitchcnt = switchcnt; 2636 if (tdq_idled(tdq) == 0) 2637 continue; 2638 } 2639 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2640 #else 2641 oldswitchcnt = switchcnt; 2642 #endif 2643 /* 2644 * If we're switching very frequently, spin while checking 2645 * for load rather than entering a low power state that 2646 * may require an IPI. However, don't do any busy 2647 * loops while on SMT machines as this simply steals 2648 * cycles from cores doing useful work. 2649 */ 2650 if (TDQ_IDLESPIN(tdq) && switchcnt > sched_idlespinthresh) { 2651 for (i = 0; i < sched_idlespins; i++) { 2652 if (tdq->tdq_load) 2653 break; 2654 cpu_spinwait(); 2655 } 2656 } 2657 2658 /* If there was context switch during spin, restart it. */ 2659 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2660 if (tdq->tdq_load != 0 || switchcnt != oldswitchcnt) 2661 continue; 2662 2663 /* Run main MD idle handler. */ 2664 tdq->tdq_cpu_idle = 1; 2665 cpu_idle(switchcnt * 4 > sched_idlespinthresh); 2666 tdq->tdq_cpu_idle = 0; 2667 2668 /* 2669 * Account thread-less hardware interrupts and 2670 * other wakeup reasons equal to context switches. 2671 */ 2672 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2673 if (switchcnt != oldswitchcnt) 2674 continue; 2675 tdq->tdq_switchcnt++; 2676 oldswitchcnt++; 2677 } 2678 } 2679 2680 /* 2681 * A CPU is entering for the first time or a thread is exiting. 2682 */ 2683 void 2684 sched_throw(struct thread *td) 2685 { 2686 struct thread *newtd; 2687 struct tdq *tdq; 2688 2689 tdq = TDQ_SELF(); 2690 if (td == NULL) { 2691 /* Correct spinlock nesting and acquire the correct lock. */ 2692 TDQ_LOCK(tdq); 2693 spinlock_exit(); 2694 PCPU_SET(switchtime, cpu_ticks()); 2695 PCPU_SET(switchticks, ticks); 2696 } else { 2697 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2698 tdq_load_rem(tdq, td); 2699 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 2700 } 2701 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 2702 newtd = choosethread(); 2703 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 2704 cpu_throw(td, newtd); /* doesn't return */ 2705 } 2706 2707 /* 2708 * This is called from fork_exit(). Just acquire the correct locks and 2709 * let fork do the rest of the work. 2710 */ 2711 void 2712 sched_fork_exit(struct thread *td) 2713 { 2714 struct td_sched *ts; 2715 struct tdq *tdq; 2716 int cpuid; 2717 2718 /* 2719 * Finish setting up thread glue so that it begins execution in a 2720 * non-nested critical section with the scheduler lock held. 2721 */ 2722 cpuid = PCPU_GET(cpuid); 2723 tdq = TDQ_CPU(cpuid); 2724 ts = td->td_sched; 2725 if (TD_IS_IDLETHREAD(td)) 2726 td->td_lock = TDQ_LOCKPTR(tdq); 2727 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2728 td->td_oncpu = cpuid; 2729 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 2730 lock_profile_obtain_lock_success( 2731 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 2732 } 2733 2734 /* 2735 * Create on first use to catch odd startup conditons. 2736 */ 2737 char * 2738 sched_tdname(struct thread *td) 2739 { 2740 #ifdef KTR 2741 struct td_sched *ts; 2742 2743 ts = td->td_sched; 2744 if (ts->ts_name[0] == '\0') 2745 snprintf(ts->ts_name, sizeof(ts->ts_name), 2746 "%s tid %d", td->td_name, td->td_tid); 2747 return (ts->ts_name); 2748 #else 2749 return (td->td_name); 2750 #endif 2751 } 2752 2753 #ifdef KTR 2754 void 2755 sched_clear_tdname(struct thread *td) 2756 { 2757 struct td_sched *ts; 2758 2759 ts = td->td_sched; 2760 ts->ts_name[0] = '\0'; 2761 } 2762 #endif 2763 2764 #ifdef SMP 2765 2766 /* 2767 * Build the CPU topology dump string. Is recursively called to collect 2768 * the topology tree. 2769 */ 2770 static int 2771 sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, struct cpu_group *cg, 2772 int indent) 2773 { 2774 char cpusetbuf[CPUSETBUFSIZ]; 2775 int i, first; 2776 2777 sbuf_printf(sb, "%*s<group level=\"%d\" cache-level=\"%d\">\n", indent, 2778 "", 1 + indent / 2, cg->cg_level); 2779 sbuf_printf(sb, "%*s <cpu count=\"%d\" mask=\"%s\">", indent, "", 2780 cg->cg_count, cpusetobj_strprint(cpusetbuf, &cg->cg_mask)); 2781 first = TRUE; 2782 for (i = 0; i < MAXCPU; i++) { 2783 if (CPU_ISSET(i, &cg->cg_mask)) { 2784 if (!first) 2785 sbuf_printf(sb, ", "); 2786 else 2787 first = FALSE; 2788 sbuf_printf(sb, "%d", i); 2789 } 2790 } 2791 sbuf_printf(sb, "</cpu>\n"); 2792 2793 if (cg->cg_flags != 0) { 2794 sbuf_printf(sb, "%*s <flags>", indent, ""); 2795 if ((cg->cg_flags & CG_FLAG_HTT) != 0) 2796 sbuf_printf(sb, "<flag name=\"HTT\">HTT group</flag>"); 2797 if ((cg->cg_flags & CG_FLAG_THREAD) != 0) 2798 sbuf_printf(sb, "<flag name=\"THREAD\">THREAD group</flag>"); 2799 if ((cg->cg_flags & CG_FLAG_SMT) != 0) 2800 sbuf_printf(sb, "<flag name=\"SMT\">SMT group</flag>"); 2801 sbuf_printf(sb, "</flags>\n"); 2802 } 2803 2804 if (cg->cg_children > 0) { 2805 sbuf_printf(sb, "%*s <children>\n", indent, ""); 2806 for (i = 0; i < cg->cg_children; i++) 2807 sysctl_kern_sched_topology_spec_internal(sb, 2808 &cg->cg_child[i], indent+2); 2809 sbuf_printf(sb, "%*s </children>\n", indent, ""); 2810 } 2811 sbuf_printf(sb, "%*s</group>\n", indent, ""); 2812 return (0); 2813 } 2814 2815 /* 2816 * Sysctl handler for retrieving topology dump. It's a wrapper for 2817 * the recursive sysctl_kern_smp_topology_spec_internal(). 2818 */ 2819 static int 2820 sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS) 2821 { 2822 struct sbuf *topo; 2823 int err; 2824 2825 KASSERT(cpu_top != NULL, ("cpu_top isn't initialized")); 2826 2827 topo = sbuf_new(NULL, NULL, 500, SBUF_AUTOEXTEND); 2828 if (topo == NULL) 2829 return (ENOMEM); 2830 2831 sbuf_printf(topo, "<groups>\n"); 2832 err = sysctl_kern_sched_topology_spec_internal(topo, cpu_top, 1); 2833 sbuf_printf(topo, "</groups>\n"); 2834 2835 if (err == 0) { 2836 sbuf_finish(topo); 2837 err = SYSCTL_OUT(req, sbuf_data(topo), sbuf_len(topo)); 2838 } 2839 sbuf_delete(topo); 2840 return (err); 2841 } 2842 2843 #endif 2844 2845 static int 2846 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 2847 { 2848 int error, new_val, period; 2849 2850 period = 1000000 / realstathz; 2851 new_val = period * sched_slice; 2852 error = sysctl_handle_int(oidp, &new_val, 0, req); 2853 if (error != 0 || req->newptr == NULL) 2854 return (error); 2855 if (new_val <= 0) 2856 return (EINVAL); 2857 sched_slice = imax(1, (new_val + period / 2) / period); 2858 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 2859 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 2860 realstathz); 2861 return (0); 2862 } 2863 2864 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0, "Scheduler"); 2865 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0, 2866 "Scheduler name"); 2867 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW, 2868 NULL, 0, sysctl_kern_quantum, "I", 2869 "Quantum for timeshare threads in microseconds"); 2870 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, 2871 "Quantum for timeshare threads in stathz ticks"); 2872 SYSCTL_INT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0, 2873 "Interactivity score threshold"); 2874 SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW, 2875 &preempt_thresh, 0, 2876 "Maximal (lowest) priority for preemption"); 2877 SYSCTL_INT(_kern_sched, OID_AUTO, static_boost, CTLFLAG_RW, &static_boost, 0, 2878 "Assign static kernel priorities to sleeping threads"); 2879 SYSCTL_INT(_kern_sched, OID_AUTO, idlespins, CTLFLAG_RW, &sched_idlespins, 0, 2880 "Number of times idle thread will spin waiting for new work"); 2881 SYSCTL_INT(_kern_sched, OID_AUTO, idlespinthresh, CTLFLAG_RW, 2882 &sched_idlespinthresh, 0, 2883 "Threshold before we will permit idle thread spinning"); 2884 #ifdef SMP 2885 SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0, 2886 "Number of hz ticks to keep thread affinity for"); 2887 SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0, 2888 "Enables the long-term load balancer"); 2889 SYSCTL_INT(_kern_sched, OID_AUTO, balance_interval, CTLFLAG_RW, 2890 &balance_interval, 0, 2891 "Average period in stathz ticks to run the long-term balancer"); 2892 SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0, 2893 "Attempts to steal work from other cores before idling"); 2894 SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0, 2895 "Minimum load on remote CPU before we'll steal"); 2896 SYSCTL_PROC(_kern_sched, OID_AUTO, topology_spec, CTLTYPE_STRING | 2897 CTLFLAG_RD, NULL, 0, sysctl_kern_sched_topology_spec, "A", 2898 "XML dump of detected CPU topology"); 2899 #endif 2900 2901 /* ps compat. All cpu percentages from ULE are weighted. */ 2902 static int ccpu = 0; 2903 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 2904