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: stable/10/sys/kern/sched_ule.c 316841 2017-04-14 14:44:06Z avg $"); 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> 73int dtrace_vtime_active; 74dtrace_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 */ 90struct td_sched { 91 struct runq *ts_runq; /* Run-queue we're queued on. */ 92 short ts_flags; /* TSF_* flags. */ 93 u_char ts_cpu; /* CPU that we have affinity for. */ 94 int ts_rltick; /* Real last tick, for affinity. */ 95 int ts_slice; /* Ticks of slice remaining. */ 96 u_int ts_slptime; /* Number of ticks we vol. slept */ 97 u_int ts_runtime; /* Number of ticks we were running */ 98 int ts_ltick; /* Last tick that we were running on */ 99 int ts_ftick; /* First tick that we were running on */ 100 int ts_ticks; /* Tick count */ 101#ifdef KTR 102 char ts_name[TS_NAME_LEN]; 103#endif 104}; 105/* flags kept in ts_flags */ 106#define TSF_BOUND 0x0001 /* Thread can not migrate. */ 107#define TSF_XFERABLE 0x0002 /* Thread was added as transferable. */ 108 109static 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 */ 205static int sched_interact = SCHED_INTERACT_THRESH; 206static int tickincr = 8 << SCHED_TICK_SHIFT; 207static int realstathz = 127; /* reset during boot. */ 208static int sched_slice = 10; /* reset during boot. */ 209static int sched_slice_min = 1; /* reset during boot. */ 210#ifdef PREEMPTION 211#ifdef FULL_PREEMPTION 212static int preempt_thresh = PRI_MAX_IDLE; 213#else 214static int preempt_thresh = PRI_MIN_KERN; 215#endif 216#else 217static int preempt_thresh = 0; 218#endif 219static int static_boost = PRI_MIN_BATCH; 220static int sched_idlespins = 10000; 221static 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 */ 228struct 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 260struct 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 */ 268static int rebalance = 1; 269static int balance_interval = 128; /* Default set in sched_initticks(). */ 270static int affinity; 271static int steal_idle = 1; 272static int steal_thresh = 2; 273 274/* 275 * One thread queue per processor. 276 */ 277static struct tdq tdq_cpu[MAXCPU]; 278static struct tdq *balance_tdq; 279static int balance_ticks; 280static 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 */ 286static 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 299static void sched_priority(struct thread *); 300static void sched_thread_priority(struct thread *, u_char); 301static int sched_interact_score(struct thread *); 302static void sched_interact_update(struct thread *); 303static void sched_interact_fork(struct thread *); 304static void sched_pctcpu_update(struct td_sched *, int); 305 306/* Operations on per processor queues */ 307static struct thread *tdq_choose(struct tdq *); 308static void tdq_setup(struct tdq *); 309static void tdq_load_add(struct tdq *, struct thread *); 310static void tdq_load_rem(struct tdq *, struct thread *); 311static __inline void tdq_runq_add(struct tdq *, struct thread *, int); 312static __inline void tdq_runq_rem(struct tdq *, struct thread *); 313static inline int sched_shouldpreempt(int, int, int); 314void tdq_print(int cpu); 315static void runq_print(struct runq *rq); 316static void tdq_add(struct tdq *, struct thread *, int); 317#ifdef SMP 318static int tdq_move(struct tdq *, struct tdq *); 319static int tdq_idled(struct tdq *); 320static void tdq_notify(struct tdq *, struct thread *); 321static struct thread *tdq_steal(struct tdq *, int); 322static struct thread *runq_steal(struct runq *, int); 323static int sched_pickcpu(struct thread *, int); 324static void sched_balance(void); 325static int sched_balance_pair(struct tdq *, struct tdq *); 326static inline struct tdq *sched_setcpu(struct thread *, int, int); 327static inline void thread_unblock_switch(struct thread *, struct mtx *); 328static struct mtx *sched_switch_migrate(struct tdq *, struct thread *, int); 329static int sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS); 330static int sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, 331 struct cpu_group *cg, int indent); 332#endif 333 334static void sched_setup(void *dummy); 335SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL); 336 337static void sched_initticks(void *dummy); 338SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks, 339 NULL); 340 341SDT_PROVIDER_DEFINE(sched); 342 343SDT_PROBE_DEFINE3(sched, , , change__pri, "struct thread *", 344 "struct proc *", "uint8_t"); 345SDT_PROBE_DEFINE3(sched, , , dequeue, "struct thread *", 346 "struct proc *", "void *"); 347SDT_PROBE_DEFINE4(sched, , , enqueue, "struct thread *", 348 "struct proc *", "void *", "int"); 349SDT_PROBE_DEFINE4(sched, , , lend__pri, "struct thread *", 350 "struct proc *", "uint8_t", "struct thread *"); 351SDT_PROBE_DEFINE2(sched, , , load__change, "int", "int"); 352SDT_PROBE_DEFINE2(sched, , , off__cpu, "struct thread *", 353 "struct proc *"); 354SDT_PROBE_DEFINE(sched, , , on__cpu); 355SDT_PROBE_DEFINE(sched, , , remain__cpu); 356SDT_PROBE_DEFINE2(sched, , , surrender, "struct thread *", 357 "struct proc *"); 358 359/* 360 * Print the threads waiting on a run-queue. 361 */ 362static void 363runq_print(struct runq *rq) 364{ 365 struct rqhead *rqh; 366 struct thread *td; 367 int pri; 368 int j; 369 int i; 370 371 for (i = 0; i < RQB_LEN; i++) { 372 printf("\t\trunq bits %d 0x%zx\n", 373 i, rq->rq_status.rqb_bits[i]); 374 for (j = 0; j < RQB_BPW; j++) 375 if (rq->rq_status.rqb_bits[i] & (1ul << j)) { 376 pri = j + (i << RQB_L2BPW); 377 rqh = &rq->rq_queues[pri]; 378 TAILQ_FOREACH(td, rqh, td_runq) { 379 printf("\t\t\ttd %p(%s) priority %d rqindex %d pri %d\n", 380 td, td->td_name, td->td_priority, 381 td->td_rqindex, pri); 382 } 383 } 384 } 385} 386 387/* 388 * Print the status of a per-cpu thread queue. Should be a ddb show cmd. 389 */ 390void 391tdq_print(int cpu) 392{ 393 struct tdq *tdq; 394 395 tdq = TDQ_CPU(cpu); 396 397 printf("tdq %d:\n", TDQ_ID(tdq)); 398 printf("\tlock %p\n", TDQ_LOCKPTR(tdq)); 399 printf("\tLock name: %s\n", tdq->tdq_name); 400 printf("\tload: %d\n", tdq->tdq_load); 401 printf("\tswitch cnt: %d\n", tdq->tdq_switchcnt); 402 printf("\told switch cnt: %d\n", tdq->tdq_oldswitchcnt); 403 printf("\ttimeshare idx: %d\n", tdq->tdq_idx); 404 printf("\ttimeshare ridx: %d\n", tdq->tdq_ridx); 405 printf("\tload transferable: %d\n", tdq->tdq_transferable); 406 printf("\tlowest priority: %d\n", tdq->tdq_lowpri); 407 printf("\trealtime runq:\n"); 408 runq_print(&tdq->tdq_realtime); 409 printf("\ttimeshare runq:\n"); 410 runq_print(&tdq->tdq_timeshare); 411 printf("\tidle runq:\n"); 412 runq_print(&tdq->tdq_idle); 413} 414 415static inline int 416sched_shouldpreempt(int pri, int cpri, int remote) 417{ 418 /* 419 * If the new priority is not better than the current priority there is 420 * nothing to do. 421 */ 422 if (pri >= cpri) 423 return (0); 424 /* 425 * Always preempt idle. 426 */ 427 if (cpri >= PRI_MIN_IDLE) 428 return (1); 429 /* 430 * If preemption is disabled don't preempt others. 431 */ 432 if (preempt_thresh == 0) 433 return (0); 434 /* 435 * Preempt if we exceed the threshold. 436 */ 437 if (pri <= preempt_thresh) 438 return (1); 439 /* 440 * If we're interactive or better and there is non-interactive 441 * or worse running preempt only remote processors. 442 */ 443 if (remote && pri <= PRI_MAX_INTERACT && cpri > PRI_MAX_INTERACT) 444 return (1); 445 return (0); 446} 447 448/* 449 * Add a thread to the actual run-queue. Keeps transferable counts up to 450 * date with what is actually on the run-queue. Selects the correct 451 * queue position for timeshare threads. 452 */ 453static __inline void 454tdq_runq_add(struct tdq *tdq, struct thread *td, int flags) 455{ 456 struct td_sched *ts; 457 u_char pri; 458 459 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 460 THREAD_LOCK_ASSERT(td, MA_OWNED); 461 462 pri = td->td_priority; 463 ts = td->td_sched; 464 TD_SET_RUNQ(td); 465 if (THREAD_CAN_MIGRATE(td)) { 466 tdq->tdq_transferable++; 467 ts->ts_flags |= TSF_XFERABLE; 468 } 469 if (pri < PRI_MIN_BATCH) { 470 ts->ts_runq = &tdq->tdq_realtime; 471 } else if (pri <= PRI_MAX_BATCH) { 472 ts->ts_runq = &tdq->tdq_timeshare; 473 KASSERT(pri <= PRI_MAX_BATCH && pri >= PRI_MIN_BATCH, 474 ("Invalid priority %d on timeshare runq", pri)); 475 /* 476 * This queue contains only priorities between MIN and MAX 477 * realtime. Use the whole queue to represent these values. 478 */ 479 if ((flags & (SRQ_BORROWING|SRQ_PREEMPTED)) == 0) { 480 pri = RQ_NQS * (pri - PRI_MIN_BATCH) / PRI_BATCH_RANGE; 481 pri = (pri + tdq->tdq_idx) % RQ_NQS; 482 /* 483 * This effectively shortens the queue by one so we 484 * can have a one slot difference between idx and 485 * ridx while we wait for threads to drain. 486 */ 487 if (tdq->tdq_ridx != tdq->tdq_idx && 488 pri == tdq->tdq_ridx) 489 pri = (unsigned char)(pri - 1) % RQ_NQS; 490 } else 491 pri = tdq->tdq_ridx; 492 runq_add_pri(ts->ts_runq, td, pri, flags); 493 return; 494 } else 495 ts->ts_runq = &tdq->tdq_idle; 496 runq_add(ts->ts_runq, td, flags); 497} 498 499/* 500 * Remove a thread from a run-queue. This typically happens when a thread 501 * is selected to run. Running threads are not on the queue and the 502 * transferable count does not reflect them. 503 */ 504static __inline void 505tdq_runq_rem(struct tdq *tdq, struct thread *td) 506{ 507 struct td_sched *ts; 508 509 ts = td->td_sched; 510 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 511 KASSERT(ts->ts_runq != NULL, 512 ("tdq_runq_remove: thread %p null ts_runq", td)); 513 if (ts->ts_flags & TSF_XFERABLE) { 514 tdq->tdq_transferable--; 515 ts->ts_flags &= ~TSF_XFERABLE; 516 } 517 if (ts->ts_runq == &tdq->tdq_timeshare) { 518 if (tdq->tdq_idx != tdq->tdq_ridx) 519 runq_remove_idx(ts->ts_runq, td, &tdq->tdq_ridx); 520 else 521 runq_remove_idx(ts->ts_runq, td, NULL); 522 } else 523 runq_remove(ts->ts_runq, td); 524} 525 526/* 527 * Load is maintained for all threads RUNNING and ON_RUNQ. Add the load 528 * for this thread to the referenced thread queue. 529 */ 530static void 531tdq_load_add(struct tdq *tdq, struct thread *td) 532{ 533 534 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 535 THREAD_LOCK_ASSERT(td, MA_OWNED); 536 537 tdq->tdq_load++; 538 if ((td->td_flags & TDF_NOLOAD) == 0) 539 tdq->tdq_sysload++; 540 KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load); 541 SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load); 542} 543 544/* 545 * Remove the load from a thread that is transitioning to a sleep state or 546 * exiting. 547 */ 548static void 549tdq_load_rem(struct tdq *tdq, struct thread *td) 550{ 551 552 THREAD_LOCK_ASSERT(td, MA_OWNED); 553 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 554 KASSERT(tdq->tdq_load != 0, 555 ("tdq_load_rem: Removing with 0 load on queue %d", TDQ_ID(tdq))); 556 557 tdq->tdq_load--; 558 if ((td->td_flags & TDF_NOLOAD) == 0) 559 tdq->tdq_sysload--; 560 KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load); 561 SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load); 562} 563 564/* 565 * Bound timeshare latency by decreasing slice size as load increases. We 566 * consider the maximum latency as the sum of the threads waiting to run 567 * aside from curthread and target no more than sched_slice latency but 568 * no less than sched_slice_min runtime. 569 */ 570static inline int 571tdq_slice(struct tdq *tdq) 572{ 573 int load; 574 575 /* 576 * It is safe to use sys_load here because this is called from 577 * contexts where timeshare threads are running and so there 578 * cannot be higher priority load in the system. 579 */ 580 load = tdq->tdq_sysload - 1; 581 if (load >= SCHED_SLICE_MIN_DIVISOR) 582 return (sched_slice_min); 583 if (load <= 1) 584 return (sched_slice); 585 return (sched_slice / load); 586} 587 588/* 589 * Set lowpri to its exact value by searching the run-queue and 590 * evaluating curthread. curthread may be passed as an optimization. 591 */ 592static void 593tdq_setlowpri(struct tdq *tdq, struct thread *ctd) 594{ 595 struct thread *td; 596 597 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 598 if (ctd == NULL) 599 ctd = pcpu_find(TDQ_ID(tdq))->pc_curthread; 600 td = tdq_choose(tdq); 601 if (td == NULL || td->td_priority > ctd->td_priority) 602 tdq->tdq_lowpri = ctd->td_priority; 603 else 604 tdq->tdq_lowpri = td->td_priority; 605} 606 607#ifdef SMP 608struct cpu_search { 609 cpuset_t cs_mask; 610 u_int cs_prefer; 611 int cs_pri; /* Min priority for low. */ 612 int cs_limit; /* Max load for low, min load for high. */ 613 int cs_cpu; 614 int cs_load; 615}; 616 617#define CPU_SEARCH_LOWEST 0x1 618#define CPU_SEARCH_HIGHEST 0x2 619#define CPU_SEARCH_BOTH (CPU_SEARCH_LOWEST|CPU_SEARCH_HIGHEST) 620 621#define CPUSET_FOREACH(cpu, mask) \ 622 for ((cpu) = 0; (cpu) <= mp_maxid; (cpu)++) \ 623 if (CPU_ISSET(cpu, &mask)) 624 625static __always_inline int cpu_search(const struct cpu_group *cg, 626 struct cpu_search *low, struct cpu_search *high, const int match); 627int __noinline cpu_search_lowest(const struct cpu_group *cg, 628 struct cpu_search *low); 629int __noinline cpu_search_highest(const struct cpu_group *cg, 630 struct cpu_search *high); 631int __noinline cpu_search_both(const struct cpu_group *cg, 632 struct cpu_search *low, struct cpu_search *high); 633 634/* 635 * Search the tree of cpu_groups for the lowest or highest loaded cpu 636 * according to the match argument. This routine actually compares the 637 * load on all paths through the tree and finds the least loaded cpu on 638 * the least loaded path, which may differ from the least loaded cpu in 639 * the system. This balances work among caches and busses. 640 * 641 * This inline is instantiated in three forms below using constants for the 642 * match argument. It is reduced to the minimum set for each case. It is 643 * also recursive to the depth of the tree. 644 */ 645static __always_inline int 646cpu_search(const struct cpu_group *cg, struct cpu_search *low, 647 struct cpu_search *high, const int match) 648{ 649 struct cpu_search lgroup; 650 struct cpu_search hgroup; 651 cpuset_t cpumask; 652 struct cpu_group *child; 653 struct tdq *tdq; 654 int cpu, i, hload, lload, load, total, rnd, *rndptr; 655 656 total = 0; 657 cpumask = cg->cg_mask; 658 if (match & CPU_SEARCH_LOWEST) { 659 lload = INT_MAX; 660 lgroup = *low; 661 } 662 if (match & CPU_SEARCH_HIGHEST) { 663 hload = INT_MIN; 664 hgroup = *high; 665 } 666 667 /* Iterate through the child CPU groups and then remaining CPUs. */ 668 for (i = cg->cg_children, cpu = mp_maxid; ; ) { 669 if (i == 0) { 670#ifdef HAVE_INLINE_FFSL 671 cpu = CPU_FFS(&cpumask) - 1; 672#else 673 while (cpu >= 0 && !CPU_ISSET(cpu, &cpumask)) 674 cpu--; 675#endif 676 if (cpu < 0) 677 break; 678 child = NULL; 679 } else 680 child = &cg->cg_child[i - 1]; 681 682 if (match & CPU_SEARCH_LOWEST) 683 lgroup.cs_cpu = -1; 684 if (match & CPU_SEARCH_HIGHEST) 685 hgroup.cs_cpu = -1; 686 if (child) { /* Handle child CPU group. */ 687 CPU_NAND(&cpumask, &child->cg_mask); 688 switch (match) { 689 case CPU_SEARCH_LOWEST: 690 load = cpu_search_lowest(child, &lgroup); 691 break; 692 case CPU_SEARCH_HIGHEST: 693 load = cpu_search_highest(child, &hgroup); 694 break; 695 case CPU_SEARCH_BOTH: 696 load = cpu_search_both(child, &lgroup, &hgroup); 697 break; 698 } 699 } else { /* Handle child CPU. */ 700 CPU_CLR(cpu, &cpumask); 701 tdq = TDQ_CPU(cpu); 702 load = tdq->tdq_load * 256; 703 rndptr = DPCPU_PTR(randomval); 704 rnd = (*rndptr = *rndptr * 69069 + 5) >> 26; 705 if (match & CPU_SEARCH_LOWEST) { 706 if (cpu == low->cs_prefer) 707 load -= 64; 708 /* If that CPU is allowed and get data. */ 709 if (tdq->tdq_lowpri > lgroup.cs_pri && 710 tdq->tdq_load <= lgroup.cs_limit && 711 CPU_ISSET(cpu, &lgroup.cs_mask)) { 712 lgroup.cs_cpu = cpu; 713 lgroup.cs_load = load - rnd; 714 } 715 } 716 if (match & CPU_SEARCH_HIGHEST) 717 if (tdq->tdq_load >= hgroup.cs_limit && 718 tdq->tdq_transferable && 719 CPU_ISSET(cpu, &hgroup.cs_mask)) { 720 hgroup.cs_cpu = cpu; 721 hgroup.cs_load = load - rnd; 722 } 723 } 724 total += load; 725 726 /* We have info about child item. Compare it. */ 727 if (match & CPU_SEARCH_LOWEST) { 728 if (lgroup.cs_cpu >= 0 && 729 (load < lload || 730 (load == lload && lgroup.cs_load < low->cs_load))) { 731 lload = load; 732 low->cs_cpu = lgroup.cs_cpu; 733 low->cs_load = lgroup.cs_load; 734 } 735 } 736 if (match & CPU_SEARCH_HIGHEST) 737 if (hgroup.cs_cpu >= 0 && 738 (load > hload || 739 (load == hload && hgroup.cs_load > high->cs_load))) { 740 hload = load; 741 high->cs_cpu = hgroup.cs_cpu; 742 high->cs_load = hgroup.cs_load; 743 } 744 if (child) { 745 i--; 746 if (i == 0 && CPU_EMPTY(&cpumask)) 747 break; 748 } 749#ifndef HAVE_INLINE_FFSL 750 else 751 cpu--; 752#endif 753 } 754 return (total); 755} 756 757/* 758 * cpu_search instantiations must pass constants to maintain the inline 759 * optimization. 760 */ 761int 762cpu_search_lowest(const struct cpu_group *cg, struct cpu_search *low) 763{ 764 return cpu_search(cg, low, NULL, CPU_SEARCH_LOWEST); 765} 766 767int 768cpu_search_highest(const struct cpu_group *cg, struct cpu_search *high) 769{ 770 return cpu_search(cg, NULL, high, CPU_SEARCH_HIGHEST); 771} 772 773int 774cpu_search_both(const struct cpu_group *cg, struct cpu_search *low, 775 struct cpu_search *high) 776{ 777 return cpu_search(cg, low, high, CPU_SEARCH_BOTH); 778} 779 780/* 781 * Find the cpu with the least load via the least loaded path that has a 782 * lowpri greater than pri pri. A pri of -1 indicates any priority is 783 * acceptable. 784 */ 785static inline int 786sched_lowest(const struct cpu_group *cg, cpuset_t mask, int pri, int maxload, 787 int prefer) 788{ 789 struct cpu_search low; 790 791 low.cs_cpu = -1; 792 low.cs_prefer = prefer; 793 low.cs_mask = mask; 794 low.cs_pri = pri; 795 low.cs_limit = maxload; 796 cpu_search_lowest(cg, &low); 797 return low.cs_cpu; 798} 799 800/* 801 * Find the cpu with the highest load via the highest loaded path. 802 */ 803static inline int 804sched_highest(const struct cpu_group *cg, cpuset_t mask, int minload) 805{ 806 struct cpu_search high; 807 808 high.cs_cpu = -1; 809 high.cs_mask = mask; 810 high.cs_limit = minload; 811 cpu_search_highest(cg, &high); 812 return high.cs_cpu; 813} 814 815static void 816sched_balance_group(struct cpu_group *cg) 817{ 818 cpuset_t hmask, lmask; 819 int high, low, anylow; 820 821 CPU_FILL(&hmask); 822 for (;;) { 823 high = sched_highest(cg, hmask, 1); 824 /* Stop if there is no more CPU with transferrable threads. */ 825 if (high == -1) 826 break; 827 CPU_CLR(high, &hmask); 828 CPU_COPY(&hmask, &lmask); 829 /* Stop if there is no more CPU left for low. */ 830 if (CPU_EMPTY(&lmask)) 831 break; 832 anylow = 1; 833nextlow: 834 low = sched_lowest(cg, lmask, -1, 835 TDQ_CPU(high)->tdq_load - 1, high); 836 /* Stop if we looked well and found no less loaded CPU. */ 837 if (anylow && low == -1) 838 break; 839 /* Go to next high if we found no less loaded CPU. */ 840 if (low == -1) 841 continue; 842 /* Transfer thread from high to low. */ 843 if (sched_balance_pair(TDQ_CPU(high), TDQ_CPU(low))) { 844 /* CPU that got thread can no longer be a donor. */ 845 CPU_CLR(low, &hmask); 846 } else { 847 /* 848 * If failed, then there is no threads on high 849 * that can run on this low. Drop low from low 850 * mask and look for different one. 851 */ 852 CPU_CLR(low, &lmask); 853 anylow = 0; 854 goto nextlow; 855 } 856 } 857} 858 859static void 860sched_balance(void) 861{ 862 struct tdq *tdq; 863 864 /* 865 * Select a random time between .5 * balance_interval and 866 * 1.5 * balance_interval. 867 */ 868 balance_ticks = max(balance_interval / 2, 1); 869 balance_ticks += random() % balance_interval; 870 if (smp_started == 0 || rebalance == 0) 871 return; 872 tdq = TDQ_SELF(); 873 TDQ_UNLOCK(tdq); 874 sched_balance_group(cpu_top); 875 TDQ_LOCK(tdq); 876} 877 878/* 879 * Lock two thread queues using their address to maintain lock order. 880 */ 881static void 882tdq_lock_pair(struct tdq *one, struct tdq *two) 883{ 884 if (one < two) { 885 TDQ_LOCK(one); 886 TDQ_LOCK_FLAGS(two, MTX_DUPOK); 887 } else { 888 TDQ_LOCK(two); 889 TDQ_LOCK_FLAGS(one, MTX_DUPOK); 890 } 891} 892 893/* 894 * Unlock two thread queues. Order is not important here. 895 */ 896static void 897tdq_unlock_pair(struct tdq *one, struct tdq *two) 898{ 899 TDQ_UNLOCK(one); 900 TDQ_UNLOCK(two); 901} 902 903/* 904 * Transfer load between two imbalanced thread queues. 905 */ 906static int 907sched_balance_pair(struct tdq *high, struct tdq *low) 908{ 909 int moved; 910 int cpu; 911 912 tdq_lock_pair(high, low); 913 moved = 0; 914 /* 915 * Determine what the imbalance is and then adjust that to how many 916 * threads we actually have to give up (transferable). 917 */ 918 if (high->tdq_transferable != 0 && high->tdq_load > low->tdq_load && 919 (moved = tdq_move(high, low)) > 0) { 920 /* 921 * In case the target isn't the current cpu IPI it to force a 922 * reschedule with the new workload. 923 */ 924 cpu = TDQ_ID(low); 925 if (cpu != PCPU_GET(cpuid)) 926 ipi_cpu(cpu, IPI_PREEMPT); 927 } 928 tdq_unlock_pair(high, low); 929 return (moved); 930} 931 932/* 933 * Move a thread from one thread queue to another. 934 */ 935static int 936tdq_move(struct tdq *from, struct tdq *to) 937{ 938 struct td_sched *ts; 939 struct thread *td; 940 struct tdq *tdq; 941 int cpu; 942 943 TDQ_LOCK_ASSERT(from, MA_OWNED); 944 TDQ_LOCK_ASSERT(to, MA_OWNED); 945 946 tdq = from; 947 cpu = TDQ_ID(to); 948 td = tdq_steal(tdq, cpu); 949 if (td == NULL) 950 return (0); 951 ts = td->td_sched; 952 /* 953 * Although the run queue is locked the thread may be blocked. Lock 954 * it to clear this and acquire the run-queue lock. 955 */ 956 thread_lock(td); 957 /* Drop recursive lock on from acquired via thread_lock(). */ 958 TDQ_UNLOCK(from); 959 sched_rem(td); 960 ts->ts_cpu = cpu; 961 td->td_lock = TDQ_LOCKPTR(to); 962 tdq_add(to, td, SRQ_YIELDING); 963 return (1); 964} 965 966/* 967 * This tdq has idled. Try to steal a thread from another cpu and switch 968 * to it. 969 */ 970static int 971tdq_idled(struct tdq *tdq) 972{ 973 struct cpu_group *cg; 974 struct tdq *steal; 975 cpuset_t mask; 976 int thresh; 977 int cpu; 978 979 if (smp_started == 0 || steal_idle == 0) 980 return (1); 981 CPU_FILL(&mask); 982 CPU_CLR(PCPU_GET(cpuid), &mask); 983 /* We don't want to be preempted while we're iterating. */ 984 spinlock_enter(); 985 for (cg = tdq->tdq_cg; cg != NULL; ) { 986 if ((cg->cg_flags & CG_FLAG_THREAD) == 0) 987 thresh = steal_thresh; 988 else 989 thresh = 1; 990 cpu = sched_highest(cg, mask, thresh); 991 if (cpu == -1) { 992 cg = cg->cg_parent; 993 continue; 994 } 995 steal = TDQ_CPU(cpu); 996 CPU_CLR(cpu, &mask); 997 tdq_lock_pair(tdq, steal); 998 if (steal->tdq_load < thresh || steal->tdq_transferable == 0) { 999 tdq_unlock_pair(tdq, steal); 1000 continue; 1001 } 1002 /* 1003 * If a thread was added while interrupts were disabled don't 1004 * steal one here. If we fail to acquire one due to affinity 1005 * restrictions loop again with this cpu removed from the 1006 * set. 1007 */ 1008 if (tdq->tdq_load == 0 && tdq_move(steal, tdq) == 0) { 1009 tdq_unlock_pair(tdq, steal); 1010 continue; 1011 } 1012 spinlock_exit(); 1013 TDQ_UNLOCK(steal); 1014 mi_switch(SW_VOL | SWT_IDLE, NULL); 1015 thread_unlock(curthread); 1016 1017 return (0); 1018 } 1019 spinlock_exit(); 1020 return (1); 1021} 1022 1023/* 1024 * Notify a remote cpu of new work. Sends an IPI if criteria are met. 1025 */ 1026static void 1027tdq_notify(struct tdq *tdq, struct thread *td) 1028{ 1029 struct thread *ctd; 1030 int pri; 1031 int cpu; 1032 1033 if (tdq->tdq_ipipending) 1034 return; 1035 cpu = td->td_sched->ts_cpu; 1036 pri = td->td_priority; 1037 ctd = pcpu_find(cpu)->pc_curthread; 1038 if (!sched_shouldpreempt(pri, ctd->td_priority, 1)) 1039 return; 1040 1041 /* 1042 * Make sure that tdq_load updated before calling this function 1043 * is globally visible before we read tdq_cpu_idle. Idle thread 1044 * accesses both of them without locks, and the order is important. 1045 */ 1046 mb(); 1047 1048 if (TD_IS_IDLETHREAD(ctd)) { 1049 /* 1050 * If the MD code has an idle wakeup routine try that before 1051 * falling back to IPI. 1052 */ 1053 if (!tdq->tdq_cpu_idle || cpu_idle_wakeup(cpu)) 1054 return; 1055 } 1056 tdq->tdq_ipipending = 1; 1057 ipi_cpu(cpu, IPI_PREEMPT); 1058} 1059 1060/* 1061 * Steals load from a timeshare queue. Honors the rotating queue head 1062 * index. 1063 */ 1064static struct thread * 1065runq_steal_from(struct runq *rq, int cpu, u_char start) 1066{ 1067 struct rqbits *rqb; 1068 struct rqhead *rqh; 1069 struct thread *td, *first; 1070 int bit; 1071 int pri; 1072 int i; 1073 1074 rqb = &rq->rq_status; 1075 bit = start & (RQB_BPW -1); 1076 pri = 0; 1077 first = NULL; 1078again: 1079 for (i = RQB_WORD(start); i < RQB_LEN; bit = 0, i++) { 1080 if (rqb->rqb_bits[i] == 0) 1081 continue; 1082 if (bit != 0) { 1083 for (pri = bit; pri < RQB_BPW; pri++) 1084 if (rqb->rqb_bits[i] & (1ul << pri)) 1085 break; 1086 if (pri >= RQB_BPW) 1087 continue; 1088 } else 1089 pri = RQB_FFS(rqb->rqb_bits[i]); 1090 pri += (i << RQB_L2BPW); 1091 rqh = &rq->rq_queues[pri]; 1092 TAILQ_FOREACH(td, rqh, td_runq) { 1093 if (first && THREAD_CAN_MIGRATE(td) && 1094 THREAD_CAN_SCHED(td, cpu)) 1095 return (td); 1096 first = td; 1097 } 1098 } 1099 if (start != 0) { 1100 start = 0; 1101 goto again; 1102 } 1103 1104 if (first && THREAD_CAN_MIGRATE(first) && 1105 THREAD_CAN_SCHED(first, cpu)) 1106 return (first); 1107 return (NULL); 1108} 1109 1110/* 1111 * Steals load from a standard linear queue. 1112 */ 1113static struct thread * 1114runq_steal(struct runq *rq, int cpu) 1115{ 1116 struct rqhead *rqh; 1117 struct rqbits *rqb; 1118 struct thread *td; 1119 int word; 1120 int bit; 1121 1122 rqb = &rq->rq_status; 1123 for (word = 0; word < RQB_LEN; word++) { 1124 if (rqb->rqb_bits[word] == 0) 1125 continue; 1126 for (bit = 0; bit < RQB_BPW; bit++) { 1127 if ((rqb->rqb_bits[word] & (1ul << bit)) == 0) 1128 continue; 1129 rqh = &rq->rq_queues[bit + (word << RQB_L2BPW)]; 1130 TAILQ_FOREACH(td, rqh, td_runq) 1131 if (THREAD_CAN_MIGRATE(td) && 1132 THREAD_CAN_SCHED(td, cpu)) 1133 return (td); 1134 } 1135 } 1136 return (NULL); 1137} 1138 1139/* 1140 * Attempt to steal a thread in priority order from a thread queue. 1141 */ 1142static struct thread * 1143tdq_steal(struct tdq *tdq, int cpu) 1144{ 1145 struct thread *td; 1146 1147 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1148 if ((td = runq_steal(&tdq->tdq_realtime, cpu)) != NULL) 1149 return (td); 1150 if ((td = runq_steal_from(&tdq->tdq_timeshare, 1151 cpu, tdq->tdq_ridx)) != NULL) 1152 return (td); 1153 return (runq_steal(&tdq->tdq_idle, cpu)); 1154} 1155 1156/* 1157 * Sets the thread lock and ts_cpu to match the requested cpu. Unlocks the 1158 * current lock and returns with the assigned queue locked. 1159 */ 1160static inline struct tdq * 1161sched_setcpu(struct thread *td, int cpu, int flags) 1162{ 1163 1164 struct tdq *tdq; 1165 1166 THREAD_LOCK_ASSERT(td, MA_OWNED); 1167 tdq = TDQ_CPU(cpu); 1168 td->td_sched->ts_cpu = cpu; 1169 /* 1170 * If the lock matches just return the queue. 1171 */ 1172 if (td->td_lock == TDQ_LOCKPTR(tdq)) 1173 return (tdq); 1174#ifdef notyet 1175 /* 1176 * If the thread isn't running its lockptr is a 1177 * turnstile or a sleepqueue. We can just lock_set without 1178 * blocking. 1179 */ 1180 if (TD_CAN_RUN(td)) { 1181 TDQ_LOCK(tdq); 1182 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 1183 return (tdq); 1184 } 1185#endif 1186 /* 1187 * The hard case, migration, we need to block the thread first to 1188 * prevent order reversals with other cpus locks. 1189 */ 1190 spinlock_enter(); 1191 thread_lock_block(td); 1192 TDQ_LOCK(tdq); 1193 thread_lock_unblock(td, TDQ_LOCKPTR(tdq)); 1194 spinlock_exit(); 1195 return (tdq); 1196} 1197 1198SCHED_STAT_DEFINE(pickcpu_intrbind, "Soft interrupt binding"); 1199SCHED_STAT_DEFINE(pickcpu_idle_affinity, "Picked idle cpu based on affinity"); 1200SCHED_STAT_DEFINE(pickcpu_affinity, "Picked cpu based on affinity"); 1201SCHED_STAT_DEFINE(pickcpu_lowest, "Selected lowest load"); 1202SCHED_STAT_DEFINE(pickcpu_local, "Migrated to current cpu"); 1203SCHED_STAT_DEFINE(pickcpu_migration, "Selection may have caused migration"); 1204 1205static int 1206sched_pickcpu(struct thread *td, int flags) 1207{ 1208 struct cpu_group *cg, *ccg; 1209 struct td_sched *ts; 1210 struct tdq *tdq; 1211 cpuset_t mask; 1212 int cpu, pri, self; 1213 1214 self = PCPU_GET(cpuid); 1215 ts = td->td_sched; 1216 if (smp_started == 0) 1217 return (self); 1218 /* 1219 * Don't migrate a running thread from sched_switch(). 1220 */ 1221 if ((flags & SRQ_OURSELF) || !THREAD_CAN_MIGRATE(td)) 1222 return (ts->ts_cpu); 1223 /* 1224 * Prefer to run interrupt threads on the processors that generate 1225 * the interrupt. 1226 */ 1227 pri = td->td_priority; 1228 if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_SCHED(td, self) && 1229 curthread->td_intr_nesting_level && ts->ts_cpu != self) { 1230 SCHED_STAT_INC(pickcpu_intrbind); 1231 ts->ts_cpu = self; 1232 if (TDQ_CPU(self)->tdq_lowpri > pri) { 1233 SCHED_STAT_INC(pickcpu_affinity); 1234 return (ts->ts_cpu); 1235 } 1236 } 1237 /* 1238 * If the thread can run on the last cpu and the affinity has not 1239 * expired or it is idle run it there. 1240 */ 1241 tdq = TDQ_CPU(ts->ts_cpu); 1242 cg = tdq->tdq_cg; 1243 if (THREAD_CAN_SCHED(td, ts->ts_cpu) && 1244 tdq->tdq_lowpri >= PRI_MIN_IDLE && 1245 SCHED_AFFINITY(ts, CG_SHARE_L2)) { 1246 if (cg->cg_flags & CG_FLAG_THREAD) { 1247 CPUSET_FOREACH(cpu, cg->cg_mask) { 1248 if (TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE) 1249 break; 1250 } 1251 } else 1252 cpu = INT_MAX; 1253 if (cpu > mp_maxid) { 1254 SCHED_STAT_INC(pickcpu_idle_affinity); 1255 return (ts->ts_cpu); 1256 } 1257 } 1258 /* 1259 * Search for the last level cache CPU group in the tree. 1260 * Skip caches with expired affinity time and SMT groups. 1261 * Affinity to higher level caches will be handled less aggressively. 1262 */ 1263 for (ccg = NULL; cg != NULL; cg = cg->cg_parent) { 1264 if (cg->cg_flags & CG_FLAG_THREAD) 1265 continue; 1266 if (!SCHED_AFFINITY(ts, cg->cg_level)) 1267 continue; 1268 ccg = cg; 1269 } 1270 if (ccg != NULL) 1271 cg = ccg; 1272 cpu = -1; 1273 /* Search the group for the less loaded idle CPU we can run now. */ 1274 mask = td->td_cpuset->cs_mask; 1275 if (cg != NULL && cg != cpu_top && 1276 CPU_CMP(&cg->cg_mask, &cpu_top->cg_mask) != 0) 1277 cpu = sched_lowest(cg, mask, max(pri, PRI_MAX_TIMESHARE), 1278 INT_MAX, ts->ts_cpu); 1279 /* Search globally for the less loaded CPU we can run now. */ 1280 if (cpu == -1) 1281 cpu = sched_lowest(cpu_top, mask, pri, INT_MAX, ts->ts_cpu); 1282 /* Search globally for the less loaded CPU. */ 1283 if (cpu == -1) 1284 cpu = sched_lowest(cpu_top, mask, -1, INT_MAX, ts->ts_cpu); 1285 KASSERT(cpu != -1, ("sched_pickcpu: Failed to find a cpu.")); 1286 /* 1287 * Compare the lowest loaded cpu to current cpu. 1288 */ 1289 if (THREAD_CAN_SCHED(td, self) && TDQ_CPU(self)->tdq_lowpri > pri && 1290 TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE && 1291 TDQ_CPU(self)->tdq_load <= TDQ_CPU(cpu)->tdq_load + 1) { 1292 SCHED_STAT_INC(pickcpu_local); 1293 cpu = self; 1294 } else 1295 SCHED_STAT_INC(pickcpu_lowest); 1296 if (cpu != ts->ts_cpu) 1297 SCHED_STAT_INC(pickcpu_migration); 1298 return (cpu); 1299} 1300#endif 1301 1302/* 1303 * Pick the highest priority task we have and return it. 1304 */ 1305static struct thread * 1306tdq_choose(struct tdq *tdq) 1307{ 1308 struct thread *td; 1309 1310 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1311 td = runq_choose(&tdq->tdq_realtime); 1312 if (td != NULL) 1313 return (td); 1314 td = runq_choose_from(&tdq->tdq_timeshare, tdq->tdq_ridx); 1315 if (td != NULL) { 1316 KASSERT(td->td_priority >= PRI_MIN_BATCH, 1317 ("tdq_choose: Invalid priority on timeshare queue %d", 1318 td->td_priority)); 1319 return (td); 1320 } 1321 td = runq_choose(&tdq->tdq_idle); 1322 if (td != NULL) { 1323 KASSERT(td->td_priority >= PRI_MIN_IDLE, 1324 ("tdq_choose: Invalid priority on idle queue %d", 1325 td->td_priority)); 1326 return (td); 1327 } 1328 1329 return (NULL); 1330} 1331 1332/* 1333 * Initialize a thread queue. 1334 */ 1335static void 1336tdq_setup(struct tdq *tdq) 1337{ 1338 1339 if (bootverbose) 1340 printf("ULE: setup cpu %d\n", TDQ_ID(tdq)); 1341 runq_init(&tdq->tdq_realtime); 1342 runq_init(&tdq->tdq_timeshare); 1343 runq_init(&tdq->tdq_idle); 1344 snprintf(tdq->tdq_name, sizeof(tdq->tdq_name), 1345 "sched lock %d", (int)TDQ_ID(tdq)); 1346 mtx_init(&tdq->tdq_lock, tdq->tdq_name, "sched lock", 1347 MTX_SPIN | MTX_RECURSE); 1348#ifdef KTR 1349 snprintf(tdq->tdq_loadname, sizeof(tdq->tdq_loadname), 1350 "CPU %d load", (int)TDQ_ID(tdq)); 1351#endif 1352} 1353 1354#ifdef SMP 1355static void 1356sched_setup_smp(void) 1357{ 1358 struct tdq *tdq; 1359 int i; 1360 1361 cpu_top = smp_topo(); 1362 CPU_FOREACH(i) { 1363 tdq = TDQ_CPU(i); 1364 tdq_setup(tdq); 1365 tdq->tdq_cg = smp_topo_find(cpu_top, i); 1366 if (tdq->tdq_cg == NULL) 1367 panic("Can't find cpu group for %d\n", i); 1368 } 1369 balance_tdq = TDQ_SELF(); 1370 sched_balance(); 1371} 1372#endif 1373 1374/* 1375 * Setup the thread queues and initialize the topology based on MD 1376 * information. 1377 */ 1378static void 1379sched_setup(void *dummy) 1380{ 1381 struct tdq *tdq; 1382 1383 tdq = TDQ_SELF(); 1384#ifdef SMP 1385 sched_setup_smp(); 1386#else 1387 tdq_setup(tdq); 1388#endif 1389 1390 /* Add thread0's load since it's running. */ 1391 TDQ_LOCK(tdq); 1392 thread0.td_lock = TDQ_LOCKPTR(TDQ_SELF()); 1393 tdq_load_add(tdq, &thread0); 1394 tdq->tdq_lowpri = thread0.td_priority; 1395 TDQ_UNLOCK(tdq); 1396} 1397 1398/* 1399 * This routine determines time constants after stathz and hz are setup. 1400 */ 1401/* ARGSUSED */ 1402static void 1403sched_initticks(void *dummy) 1404{ 1405 int incr; 1406 1407 realstathz = stathz ? stathz : hz; 1408 sched_slice = realstathz / SCHED_SLICE_DEFAULT_DIVISOR; 1409 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 1410 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 1411 realstathz); 1412 1413 /* 1414 * tickincr is shifted out by 10 to avoid rounding errors due to 1415 * hz not being evenly divisible by stathz on all platforms. 1416 */ 1417 incr = (hz << SCHED_TICK_SHIFT) / realstathz; 1418 /* 1419 * This does not work for values of stathz that are more than 1420 * 1 << SCHED_TICK_SHIFT * hz. In practice this does not happen. 1421 */ 1422 if (incr == 0) 1423 incr = 1; 1424 tickincr = incr; 1425#ifdef SMP 1426 /* 1427 * Set the default balance interval now that we know 1428 * what realstathz is. 1429 */ 1430 balance_interval = realstathz; 1431 affinity = SCHED_AFFINITY_DEFAULT; 1432#endif 1433 if (sched_idlespinthresh < 0) 1434 sched_idlespinthresh = 2 * max(10000, 6 * hz) / realstathz; 1435} 1436 1437 1438/* 1439 * This is the core of the interactivity algorithm. Determines a score based 1440 * on past behavior. It is the ratio of sleep time to run time scaled to 1441 * a [0, 100] integer. This is the voluntary sleep time of a process, which 1442 * differs from the cpu usage because it does not account for time spent 1443 * waiting on a run-queue. Would be prettier if we had floating point. 1444 */ 1445static int 1446sched_interact_score(struct thread *td) 1447{ 1448 struct td_sched *ts; 1449 int div; 1450 1451 ts = td->td_sched; 1452 /* 1453 * The score is only needed if this is likely to be an interactive 1454 * task. Don't go through the expense of computing it if there's 1455 * no chance. 1456 */ 1457 if (sched_interact <= SCHED_INTERACT_HALF && 1458 ts->ts_runtime >= ts->ts_slptime) 1459 return (SCHED_INTERACT_HALF); 1460 1461 if (ts->ts_runtime > ts->ts_slptime) { 1462 div = max(1, ts->ts_runtime / SCHED_INTERACT_HALF); 1463 return (SCHED_INTERACT_HALF + 1464 (SCHED_INTERACT_HALF - (ts->ts_slptime / div))); 1465 } 1466 if (ts->ts_slptime > ts->ts_runtime) { 1467 div = max(1, ts->ts_slptime / SCHED_INTERACT_HALF); 1468 return (ts->ts_runtime / div); 1469 } 1470 /* runtime == slptime */ 1471 if (ts->ts_runtime) 1472 return (SCHED_INTERACT_HALF); 1473 1474 /* 1475 * This can happen if slptime and runtime are 0. 1476 */ 1477 return (0); 1478 1479} 1480 1481/* 1482 * Scale the scheduling priority according to the "interactivity" of this 1483 * process. 1484 */ 1485static void 1486sched_priority(struct thread *td) 1487{ 1488 int score; 1489 int pri; 1490 1491 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 1492 return; 1493 /* 1494 * If the score is interactive we place the thread in the realtime 1495 * queue with a priority that is less than kernel and interrupt 1496 * priorities. These threads are not subject to nice restrictions. 1497 * 1498 * Scores greater than this are placed on the normal timeshare queue 1499 * where the priority is partially decided by the most recent cpu 1500 * utilization and the rest is decided by nice value. 1501 * 1502 * The nice value of the process has a linear effect on the calculated 1503 * score. Negative nice values make it easier for a thread to be 1504 * considered interactive. 1505 */ 1506 score = imax(0, sched_interact_score(td) + td->td_proc->p_nice); 1507 if (score < sched_interact) { 1508 pri = PRI_MIN_INTERACT; 1509 pri += ((PRI_MAX_INTERACT - PRI_MIN_INTERACT + 1) / 1510 sched_interact) * score; 1511 KASSERT(pri >= PRI_MIN_INTERACT && pri <= PRI_MAX_INTERACT, 1512 ("sched_priority: invalid interactive priority %d score %d", 1513 pri, score)); 1514 } else { 1515 pri = SCHED_PRI_MIN; 1516 if (td->td_sched->ts_ticks) 1517 pri += min(SCHED_PRI_TICKS(td->td_sched), 1518 SCHED_PRI_RANGE - 1); 1519 pri += SCHED_PRI_NICE(td->td_proc->p_nice); 1520 KASSERT(pri >= PRI_MIN_BATCH && pri <= PRI_MAX_BATCH, 1521 ("sched_priority: invalid priority %d: nice %d, " 1522 "ticks %d ftick %d ltick %d tick pri %d", 1523 pri, td->td_proc->p_nice, td->td_sched->ts_ticks, 1524 td->td_sched->ts_ftick, td->td_sched->ts_ltick, 1525 SCHED_PRI_TICKS(td->td_sched))); 1526 } 1527 sched_user_prio(td, pri); 1528 1529 return; 1530} 1531 1532/* 1533 * This routine enforces a maximum limit on the amount of scheduling history 1534 * kept. It is called after either the slptime or runtime is adjusted. This 1535 * function is ugly due to integer math. 1536 */ 1537static void 1538sched_interact_update(struct thread *td) 1539{ 1540 struct td_sched *ts; 1541 u_int sum; 1542 1543 ts = td->td_sched; 1544 sum = ts->ts_runtime + ts->ts_slptime; 1545 if (sum < SCHED_SLP_RUN_MAX) 1546 return; 1547 /* 1548 * This only happens from two places: 1549 * 1) We have added an unusual amount of run time from fork_exit. 1550 * 2) We have added an unusual amount of sleep time from sched_sleep(). 1551 */ 1552 if (sum > SCHED_SLP_RUN_MAX * 2) { 1553 if (ts->ts_runtime > ts->ts_slptime) { 1554 ts->ts_runtime = SCHED_SLP_RUN_MAX; 1555 ts->ts_slptime = 1; 1556 } else { 1557 ts->ts_slptime = SCHED_SLP_RUN_MAX; 1558 ts->ts_runtime = 1; 1559 } 1560 return; 1561 } 1562 /* 1563 * If we have exceeded by more than 1/5th then the algorithm below 1564 * will not bring us back into range. Dividing by two here forces 1565 * us into the range of [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX] 1566 */ 1567 if (sum > (SCHED_SLP_RUN_MAX / 5) * 6) { 1568 ts->ts_runtime /= 2; 1569 ts->ts_slptime /= 2; 1570 return; 1571 } 1572 ts->ts_runtime = (ts->ts_runtime / 5) * 4; 1573 ts->ts_slptime = (ts->ts_slptime / 5) * 4; 1574} 1575 1576/* 1577 * Scale back the interactivity history when a child thread is created. The 1578 * history is inherited from the parent but the thread may behave totally 1579 * differently. For example, a shell spawning a compiler process. We want 1580 * to learn that the compiler is behaving badly very quickly. 1581 */ 1582static void 1583sched_interact_fork(struct thread *td) 1584{ 1585 int ratio; 1586 int sum; 1587 1588 sum = td->td_sched->ts_runtime + td->td_sched->ts_slptime; 1589 if (sum > SCHED_SLP_RUN_FORK) { 1590 ratio = sum / SCHED_SLP_RUN_FORK; 1591 td->td_sched->ts_runtime /= ratio; 1592 td->td_sched->ts_slptime /= ratio; 1593 } 1594} 1595 1596/* 1597 * Called from proc0_init() to setup the scheduler fields. 1598 */ 1599void 1600schedinit(void) 1601{ 1602 1603 /* 1604 * Set up the scheduler specific parts of proc0. 1605 */ 1606 proc0.p_sched = NULL; /* XXX */ 1607 thread0.td_sched = &td_sched0; 1608 td_sched0.ts_ltick = ticks; 1609 td_sched0.ts_ftick = ticks; 1610 td_sched0.ts_slice = 0; 1611} 1612 1613/* 1614 * This is only somewhat accurate since given many processes of the same 1615 * priority they will switch when their slices run out, which will be 1616 * at most sched_slice stathz ticks. 1617 */ 1618int 1619sched_rr_interval(void) 1620{ 1621 1622 /* Convert sched_slice from stathz to hz. */ 1623 return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz)); 1624} 1625 1626/* 1627 * Update the percent cpu tracking information when it is requested or 1628 * the total history exceeds the maximum. We keep a sliding history of 1629 * tick counts that slowly decays. This is less precise than the 4BSD 1630 * mechanism since it happens with less regular and frequent events. 1631 */ 1632static void 1633sched_pctcpu_update(struct td_sched *ts, int run) 1634{ 1635 int t = ticks; 1636 1637 if (t - ts->ts_ltick >= SCHED_TICK_TARG) { 1638 ts->ts_ticks = 0; 1639 ts->ts_ftick = t - SCHED_TICK_TARG; 1640 } else if (t - ts->ts_ftick >= SCHED_TICK_MAX) { 1641 ts->ts_ticks = (ts->ts_ticks / (ts->ts_ltick - ts->ts_ftick)) * 1642 (ts->ts_ltick - (t - SCHED_TICK_TARG)); 1643 ts->ts_ftick = t - SCHED_TICK_TARG; 1644 } 1645 if (run) 1646 ts->ts_ticks += (t - ts->ts_ltick) << SCHED_TICK_SHIFT; 1647 ts->ts_ltick = t; 1648} 1649 1650/* 1651 * Adjust the priority of a thread. Move it to the appropriate run-queue 1652 * if necessary. This is the back-end for several priority related 1653 * functions. 1654 */ 1655static void 1656sched_thread_priority(struct thread *td, u_char prio) 1657{ 1658 struct td_sched *ts; 1659 struct tdq *tdq; 1660 int oldpri; 1661 1662 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "prio", 1663 "prio:%d", td->td_priority, "new prio:%d", prio, 1664 KTR_ATTR_LINKED, sched_tdname(curthread)); 1665 SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio); 1666 if (td != curthread && prio < td->td_priority) { 1667 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread), 1668 "lend prio", "prio:%d", td->td_priority, "new prio:%d", 1669 prio, KTR_ATTR_LINKED, sched_tdname(td)); 1670 SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio, 1671 curthread); 1672 } 1673 ts = td->td_sched; 1674 THREAD_LOCK_ASSERT(td, MA_OWNED); 1675 if (td->td_priority == prio) 1676 return; 1677 /* 1678 * If the priority has been elevated due to priority 1679 * propagation, we may have to move ourselves to a new 1680 * queue. This could be optimized to not re-add in some 1681 * cases. 1682 */ 1683 if (TD_ON_RUNQ(td) && prio < td->td_priority) { 1684 sched_rem(td); 1685 td->td_priority = prio; 1686 sched_add(td, SRQ_BORROWING); 1687 return; 1688 } 1689 /* 1690 * If the thread is currently running we may have to adjust the lowpri 1691 * information so other cpus are aware of our current priority. 1692 */ 1693 if (TD_IS_RUNNING(td)) { 1694 tdq = TDQ_CPU(ts->ts_cpu); 1695 oldpri = td->td_priority; 1696 td->td_priority = prio; 1697 if (prio < tdq->tdq_lowpri) 1698 tdq->tdq_lowpri = prio; 1699 else if (tdq->tdq_lowpri == oldpri) 1700 tdq_setlowpri(tdq, td); 1701 return; 1702 } 1703 td->td_priority = prio; 1704} 1705 1706/* 1707 * Update a thread's priority when it is lent another thread's 1708 * priority. 1709 */ 1710void 1711sched_lend_prio(struct thread *td, u_char prio) 1712{ 1713 1714 td->td_flags |= TDF_BORROWING; 1715 sched_thread_priority(td, prio); 1716} 1717 1718/* 1719 * Restore a thread's priority when priority propagation is 1720 * over. The prio argument is the minimum priority the thread 1721 * needs to have to satisfy other possible priority lending 1722 * requests. If the thread's regular priority is less 1723 * important than prio, the thread will keep a priority boost 1724 * of prio. 1725 */ 1726void 1727sched_unlend_prio(struct thread *td, u_char prio) 1728{ 1729 u_char base_pri; 1730 1731 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 1732 td->td_base_pri <= PRI_MAX_TIMESHARE) 1733 base_pri = td->td_user_pri; 1734 else 1735 base_pri = td->td_base_pri; 1736 if (prio >= base_pri) { 1737 td->td_flags &= ~TDF_BORROWING; 1738 sched_thread_priority(td, base_pri); 1739 } else 1740 sched_lend_prio(td, prio); 1741} 1742 1743/* 1744 * Standard entry for setting the priority to an absolute value. 1745 */ 1746void 1747sched_prio(struct thread *td, u_char prio) 1748{ 1749 u_char oldprio; 1750 1751 /* First, update the base priority. */ 1752 td->td_base_pri = prio; 1753 1754 /* 1755 * If the thread is borrowing another thread's priority, don't 1756 * ever lower the priority. 1757 */ 1758 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 1759 return; 1760 1761 /* Change the real priority. */ 1762 oldprio = td->td_priority; 1763 sched_thread_priority(td, prio); 1764 1765 /* 1766 * If the thread is on a turnstile, then let the turnstile update 1767 * its state. 1768 */ 1769 if (TD_ON_LOCK(td) && oldprio != prio) 1770 turnstile_adjust(td, oldprio); 1771} 1772 1773/* 1774 * Set the base user priority, does not effect current running priority. 1775 */ 1776void 1777sched_user_prio(struct thread *td, u_char prio) 1778{ 1779 1780 td->td_base_user_pri = prio; 1781 if (td->td_lend_user_pri <= prio) 1782 return; 1783 td->td_user_pri = prio; 1784} 1785 1786void 1787sched_lend_user_prio(struct thread *td, u_char prio) 1788{ 1789 1790 THREAD_LOCK_ASSERT(td, MA_OWNED); 1791 td->td_lend_user_pri = prio; 1792 td->td_user_pri = min(prio, td->td_base_user_pri); 1793 if (td->td_priority > td->td_user_pri) 1794 sched_prio(td, td->td_user_pri); 1795 else if (td->td_priority != td->td_user_pri) 1796 td->td_flags |= TDF_NEEDRESCHED; 1797} 1798 1799/* 1800 * Handle migration from sched_switch(). This happens only for 1801 * cpu binding. 1802 */ 1803static struct mtx * 1804sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags) 1805{ 1806 struct tdq *tdn; 1807 1808 tdn = TDQ_CPU(td->td_sched->ts_cpu); 1809#ifdef SMP 1810 tdq_load_rem(tdq, td); 1811 /* 1812 * Do the lock dance required to avoid LOR. We grab an extra 1813 * spinlock nesting to prevent preemption while we're 1814 * not holding either run-queue lock. 1815 */ 1816 spinlock_enter(); 1817 thread_lock_block(td); /* This releases the lock on tdq. */ 1818 1819 /* 1820 * Acquire both run-queue locks before placing the thread on the new 1821 * run-queue to avoid deadlocks created by placing a thread with a 1822 * blocked lock on the run-queue of a remote processor. The deadlock 1823 * occurs when a third processor attempts to lock the two queues in 1824 * question while the target processor is spinning with its own 1825 * run-queue lock held while waiting for the blocked lock to clear. 1826 */ 1827 tdq_lock_pair(tdn, tdq); 1828 tdq_add(tdn, td, flags); 1829 tdq_notify(tdn, td); 1830 TDQ_UNLOCK(tdn); 1831 spinlock_exit(); 1832#endif 1833 return (TDQ_LOCKPTR(tdn)); 1834} 1835 1836/* 1837 * Variadic version of thread_lock_unblock() that does not assume td_lock 1838 * is blocked. 1839 */ 1840static inline void 1841thread_unblock_switch(struct thread *td, struct mtx *mtx) 1842{ 1843 atomic_store_rel_ptr((volatile uintptr_t *)&td->td_lock, 1844 (uintptr_t)mtx); 1845} 1846 1847/* 1848 * Switch threads. This function has to handle threads coming in while 1849 * blocked for some reason, running, or idle. It also must deal with 1850 * migrating a thread from one queue to another as running threads may 1851 * be assigned elsewhere via binding. 1852 */ 1853void 1854sched_switch(struct thread *td, struct thread *newtd, int flags) 1855{ 1856 struct tdq *tdq; 1857 struct td_sched *ts; 1858 struct mtx *mtx; 1859 int srqflag; 1860 int cpuid, preempted; 1861 1862 THREAD_LOCK_ASSERT(td, MA_OWNED); 1863 KASSERT(newtd == NULL, ("sched_switch: Unsupported newtd argument")); 1864 1865 cpuid = PCPU_GET(cpuid); 1866 tdq = TDQ_CPU(cpuid); 1867 ts = td->td_sched; 1868 mtx = td->td_lock; 1869 sched_pctcpu_update(ts, 1); 1870 ts->ts_rltick = ticks; 1871 td->td_lastcpu = td->td_oncpu; 1872 td->td_oncpu = NOCPU; 1873 preempted = (td->td_flags & TDF_SLICEEND) == 0 && 1874 (flags & SW_PREEMPT) != 0; 1875 td->td_flags &= ~(TDF_NEEDRESCHED | TDF_SLICEEND); 1876 td->td_owepreempt = 0; 1877 if (!TD_IS_IDLETHREAD(td)) 1878 tdq->tdq_switchcnt++; 1879 /* 1880 * The lock pointer in an idle thread should never change. Reset it 1881 * to CAN_RUN as well. 1882 */ 1883 if (TD_IS_IDLETHREAD(td)) { 1884 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1885 TD_SET_CAN_RUN(td); 1886 } else if (TD_IS_RUNNING(td)) { 1887 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1888 srqflag = preempted ? 1889 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 1890 SRQ_OURSELF|SRQ_YIELDING; 1891#ifdef SMP 1892 if (THREAD_CAN_MIGRATE(td) && !THREAD_CAN_SCHED(td, ts->ts_cpu)) 1893 ts->ts_cpu = sched_pickcpu(td, 0); 1894#endif 1895 if (ts->ts_cpu == cpuid) 1896 tdq_runq_add(tdq, td, srqflag); 1897 else { 1898 KASSERT(THREAD_CAN_MIGRATE(td) || 1899 (ts->ts_flags & TSF_BOUND) != 0, 1900 ("Thread %p shouldn't migrate", td)); 1901 mtx = sched_switch_migrate(tdq, td, srqflag); 1902 } 1903 } else { 1904 /* This thread must be going to sleep. */ 1905 TDQ_LOCK(tdq); 1906 mtx = thread_lock_block(td); 1907 tdq_load_rem(tdq, td); 1908 } 1909 1910#if (KTR_COMPILE & KTR_SCHED) != 0 1911 if (TD_IS_IDLETHREAD(td)) 1912 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "idle", 1913 "prio:%d", td->td_priority); 1914 else 1915 KTR_STATE3(KTR_SCHED, "thread", sched_tdname(td), KTDSTATE(td), 1916 "prio:%d", td->td_priority, "wmesg:\"%s\"", td->td_wmesg, 1917 "lockname:\"%s\"", td->td_lockname); 1918#endif 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 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running", 1972 "prio:%d", td->td_priority); 1973 1974 /* 1975 * Assert that all went well and return. 1976 */ 1977 TDQ_LOCK_ASSERT(tdq, MA_OWNED|MA_NOTRECURSED); 1978 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1979 td->td_oncpu = cpuid; 1980} 1981 1982/* 1983 * Adjust thread priorities as a result of a nice request. 1984 */ 1985void 1986sched_nice(struct proc *p, int nice) 1987{ 1988 struct thread *td; 1989 1990 PROC_LOCK_ASSERT(p, MA_OWNED); 1991 1992 p->p_nice = nice; 1993 FOREACH_THREAD_IN_PROC(p, td) { 1994 thread_lock(td); 1995 sched_priority(td); 1996 sched_prio(td, td->td_base_user_pri); 1997 thread_unlock(td); 1998 } 1999} 2000 2001/* 2002 * Record the sleep time for the interactivity scorer. 2003 */ 2004void 2005sched_sleep(struct thread *td, int prio) 2006{ 2007 2008 THREAD_LOCK_ASSERT(td, MA_OWNED); 2009 2010 td->td_slptick = ticks; 2011 if (TD_IS_SUSPENDED(td) || prio >= PSOCK) 2012 td->td_flags |= TDF_CANSWAP; 2013 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 2014 return; 2015 if (static_boost == 1 && prio) 2016 sched_prio(td, prio); 2017 else if (static_boost && td->td_priority > static_boost) 2018 sched_prio(td, static_boost); 2019} 2020 2021/* 2022 * Schedule a thread to resume execution and record how long it voluntarily 2023 * slept. We also update the pctcpu, interactivity, and priority. 2024 */ 2025void 2026sched_wakeup(struct thread *td) 2027{ 2028 struct td_sched *ts; 2029 int slptick; 2030 2031 THREAD_LOCK_ASSERT(td, MA_OWNED); 2032 ts = td->td_sched; 2033 td->td_flags &= ~TDF_CANSWAP; 2034 /* 2035 * If we slept for more than a tick update our interactivity and 2036 * priority. 2037 */ 2038 slptick = td->td_slptick; 2039 td->td_slptick = 0; 2040 if (slptick && slptick != ticks) { 2041 ts->ts_slptime += (ticks - slptick) << SCHED_TICK_SHIFT; 2042 sched_interact_update(td); 2043 sched_pctcpu_update(ts, 0); 2044 } 2045 /* 2046 * Reset the slice value since we slept and advanced the round-robin. 2047 */ 2048 ts->ts_slice = 0; 2049 sched_add(td, SRQ_BORING); 2050} 2051 2052/* 2053 * Penalize the parent for creating a new child and initialize the child's 2054 * priority. 2055 */ 2056void 2057sched_fork(struct thread *td, struct thread *child) 2058{ 2059 THREAD_LOCK_ASSERT(td, MA_OWNED); 2060 sched_pctcpu_update(td->td_sched, 1); 2061 sched_fork_thread(td, child); 2062 /* 2063 * Penalize the parent and child for forking. 2064 */ 2065 sched_interact_fork(child); 2066 sched_priority(child); 2067 td->td_sched->ts_runtime += tickincr; 2068 sched_interact_update(td); 2069 sched_priority(td); 2070} 2071 2072/* 2073 * Fork a new thread, may be within the same process. 2074 */ 2075void 2076sched_fork_thread(struct thread *td, struct thread *child) 2077{ 2078 struct td_sched *ts; 2079 struct td_sched *ts2; 2080 struct tdq *tdq; 2081 2082 tdq = TDQ_SELF(); 2083 THREAD_LOCK_ASSERT(td, MA_OWNED); 2084 /* 2085 * Initialize child. 2086 */ 2087 ts = td->td_sched; 2088 ts2 = child->td_sched; 2089 child->td_oncpu = NOCPU; 2090 child->td_lastcpu = NOCPU; 2091 child->td_lock = TDQ_LOCKPTR(tdq); 2092 child->td_cpuset = cpuset_ref(td->td_cpuset); 2093 ts2->ts_cpu = ts->ts_cpu; 2094 ts2->ts_flags = 0; 2095 /* 2096 * Grab our parents cpu estimation information. 2097 */ 2098 ts2->ts_ticks = ts->ts_ticks; 2099 ts2->ts_ltick = ts->ts_ltick; 2100 ts2->ts_ftick = ts->ts_ftick; 2101 /* 2102 * Do not inherit any borrowed priority from the parent. 2103 */ 2104 child->td_priority = child->td_base_pri; 2105 /* 2106 * And update interactivity score. 2107 */ 2108 ts2->ts_slptime = ts->ts_slptime; 2109 ts2->ts_runtime = ts->ts_runtime; 2110 /* Attempt to quickly learn interactivity. */ 2111 ts2->ts_slice = tdq_slice(tdq) - sched_slice_min; 2112#ifdef KTR 2113 bzero(ts2->ts_name, sizeof(ts2->ts_name)); 2114#endif 2115} 2116 2117/* 2118 * Adjust the priority class of a thread. 2119 */ 2120void 2121sched_class(struct thread *td, int class) 2122{ 2123 2124 THREAD_LOCK_ASSERT(td, MA_OWNED); 2125 if (td->td_pri_class == class) 2126 return; 2127 td->td_pri_class = class; 2128} 2129 2130/* 2131 * Return some of the child's priority and interactivity to the parent. 2132 */ 2133void 2134sched_exit(struct proc *p, struct thread *child) 2135{ 2136 struct thread *td; 2137 2138 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "proc exit", 2139 "prio:%d", child->td_priority); 2140 PROC_LOCK_ASSERT(p, MA_OWNED); 2141 td = FIRST_THREAD_IN_PROC(p); 2142 sched_exit_thread(td, child); 2143} 2144 2145/* 2146 * Penalize another thread for the time spent on this one. This helps to 2147 * worsen the priority and interactivity of processes which schedule batch 2148 * jobs such as make. This has little effect on the make process itself but 2149 * causes new processes spawned by it to receive worse scores immediately. 2150 */ 2151void 2152sched_exit_thread(struct thread *td, struct thread *child) 2153{ 2154 2155 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "thread exit", 2156 "prio:%d", child->td_priority); 2157 /* 2158 * Give the child's runtime to the parent without returning the 2159 * sleep time as a penalty to the parent. This causes shells that 2160 * launch expensive things to mark their children as expensive. 2161 */ 2162 thread_lock(td); 2163 td->td_sched->ts_runtime += child->td_sched->ts_runtime; 2164 sched_interact_update(td); 2165 sched_priority(td); 2166 thread_unlock(td); 2167} 2168 2169void 2170sched_preempt(struct thread *td) 2171{ 2172 struct tdq *tdq; 2173 2174 SDT_PROBE2(sched, , , surrender, td, td->td_proc); 2175 2176 thread_lock(td); 2177 tdq = TDQ_SELF(); 2178 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2179 tdq->tdq_ipipending = 0; 2180 if (td->td_priority > tdq->tdq_lowpri) { 2181 int flags; 2182 2183 flags = SW_INVOL | SW_PREEMPT; 2184 if (td->td_critnest > 1) 2185 td->td_owepreempt = 1; 2186 else if (TD_IS_IDLETHREAD(td)) 2187 mi_switch(flags | SWT_REMOTEWAKEIDLE, NULL); 2188 else 2189 mi_switch(flags | SWT_REMOTEPREEMPT, NULL); 2190 } 2191 thread_unlock(td); 2192} 2193 2194/* 2195 * Fix priorities on return to user-space. Priorities may be elevated due 2196 * to static priorities in msleep() or similar. 2197 */ 2198void 2199sched_userret(struct thread *td) 2200{ 2201 /* 2202 * XXX we cheat slightly on the locking here to avoid locking in 2203 * the usual case. Setting td_priority here is essentially an 2204 * incomplete workaround for not setting it properly elsewhere. 2205 * Now that some interrupt handlers are threads, not setting it 2206 * properly elsewhere can clobber it in the window between setting 2207 * it here and returning to user mode, so don't waste time setting 2208 * it perfectly here. 2209 */ 2210 KASSERT((td->td_flags & TDF_BORROWING) == 0, 2211 ("thread with borrowed priority returning to userland")); 2212 if (td->td_priority != td->td_user_pri) { 2213 thread_lock(td); 2214 td->td_priority = td->td_user_pri; 2215 td->td_base_pri = td->td_user_pri; 2216 tdq_setlowpri(TDQ_SELF(), td); 2217 thread_unlock(td); 2218 } 2219} 2220 2221/* 2222 * Handle a stathz tick. This is really only relevant for timeshare 2223 * threads. 2224 */ 2225void 2226sched_clock(struct thread *td) 2227{ 2228 struct tdq *tdq; 2229 struct td_sched *ts; 2230 2231 THREAD_LOCK_ASSERT(td, MA_OWNED); 2232 tdq = TDQ_SELF(); 2233#ifdef SMP 2234 /* 2235 * We run the long term load balancer infrequently on the first cpu. 2236 */ 2237 if (balance_tdq == tdq) { 2238 if (balance_ticks && --balance_ticks == 0) 2239 sched_balance(); 2240 } 2241#endif 2242 /* 2243 * Save the old switch count so we have a record of the last ticks 2244 * activity. Initialize the new switch count based on our load. 2245 * If there is some activity seed it to reflect that. 2246 */ 2247 tdq->tdq_oldswitchcnt = tdq->tdq_switchcnt; 2248 tdq->tdq_switchcnt = tdq->tdq_load; 2249 /* 2250 * Advance the insert index once for each tick to ensure that all 2251 * threads get a chance to run. 2252 */ 2253 if (tdq->tdq_idx == tdq->tdq_ridx) { 2254 tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS; 2255 if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx])) 2256 tdq->tdq_ridx = tdq->tdq_idx; 2257 } 2258 ts = td->td_sched; 2259 sched_pctcpu_update(ts, 1); 2260 if (td->td_pri_class & PRI_FIFO_BIT) 2261 return; 2262 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) { 2263 /* 2264 * We used a tick; charge it to the thread so 2265 * that we can compute our interactivity. 2266 */ 2267 td->td_sched->ts_runtime += tickincr; 2268 sched_interact_update(td); 2269 sched_priority(td); 2270 } 2271 2272 /* 2273 * Force a context switch if the current thread has used up a full 2274 * time slice (default is 100ms). 2275 */ 2276 if (!TD_IS_IDLETHREAD(td) && ++ts->ts_slice >= tdq_slice(tdq)) { 2277 ts->ts_slice = 0; 2278 td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND; 2279 } 2280} 2281 2282/* 2283 * Called once per hz tick. 2284 */ 2285void 2286sched_tick(int cnt) 2287{ 2288 2289} 2290 2291/* 2292 * Return whether the current CPU has runnable tasks. Used for in-kernel 2293 * cooperative idle threads. 2294 */ 2295int 2296sched_runnable(void) 2297{ 2298 struct tdq *tdq; 2299 int load; 2300 2301 load = 1; 2302 2303 tdq = TDQ_SELF(); 2304 if ((curthread->td_flags & TDF_IDLETD) != 0) { 2305 if (tdq->tdq_load > 0) 2306 goto out; 2307 } else 2308 if (tdq->tdq_load - 1 > 0) 2309 goto out; 2310 load = 0; 2311out: 2312 return (load); 2313} 2314 2315/* 2316 * Choose the highest priority thread to run. The thread is removed from 2317 * the run-queue while running however the load remains. For SMP we set 2318 * the tdq in the global idle bitmask if it idles here. 2319 */ 2320struct thread * 2321sched_choose(void) 2322{ 2323 struct thread *td; 2324 struct tdq *tdq; 2325 2326 tdq = TDQ_SELF(); 2327 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2328 td = tdq_choose(tdq); 2329 if (td) { 2330 tdq_runq_rem(tdq, td); 2331 tdq->tdq_lowpri = td->td_priority; 2332 return (td); 2333 } 2334 tdq->tdq_lowpri = PRI_MAX_IDLE; 2335 return (PCPU_GET(idlethread)); 2336} 2337 2338/* 2339 * Set owepreempt if necessary. Preemption never happens directly in ULE, 2340 * we always request it once we exit a critical section. 2341 */ 2342static inline void 2343sched_setpreempt(struct thread *td) 2344{ 2345 struct thread *ctd; 2346 int cpri; 2347 int pri; 2348 2349 THREAD_LOCK_ASSERT(curthread, MA_OWNED); 2350 2351 ctd = curthread; 2352 pri = td->td_priority; 2353 cpri = ctd->td_priority; 2354 if (pri < cpri) 2355 ctd->td_flags |= TDF_NEEDRESCHED; 2356 if (panicstr != NULL || pri >= cpri || cold || TD_IS_INHIBITED(ctd)) 2357 return; 2358 if (!sched_shouldpreempt(pri, cpri, 0)) 2359 return; 2360 ctd->td_owepreempt = 1; 2361} 2362 2363/* 2364 * Add a thread to a thread queue. Select the appropriate runq and add the 2365 * thread to it. This is the internal function called when the tdq is 2366 * predetermined. 2367 */ 2368void 2369tdq_add(struct tdq *tdq, struct thread *td, int flags) 2370{ 2371 2372 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2373 KASSERT((td->td_inhibitors == 0), 2374 ("sched_add: trying to run inhibited thread")); 2375 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 2376 ("sched_add: bad thread state")); 2377 KASSERT(td->td_flags & TDF_INMEM, 2378 ("sched_add: thread swapped out")); 2379 2380 if (td->td_priority < tdq->tdq_lowpri) 2381 tdq->tdq_lowpri = td->td_priority; 2382 tdq_runq_add(tdq, td, flags); 2383 tdq_load_add(tdq, td); 2384} 2385 2386/* 2387 * Select the target thread queue and add a thread to it. Request 2388 * preemption or IPI a remote processor if required. 2389 */ 2390void 2391sched_add(struct thread *td, int flags) 2392{ 2393 struct tdq *tdq; 2394#ifdef SMP 2395 int cpu; 2396#endif 2397 2398 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 2399 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 2400 sched_tdname(curthread)); 2401 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 2402 KTR_ATTR_LINKED, sched_tdname(td)); 2403 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 2404 flags & SRQ_PREEMPTED); 2405 THREAD_LOCK_ASSERT(td, MA_OWNED); 2406 /* 2407 * Recalculate the priority before we select the target cpu or 2408 * run-queue. 2409 */ 2410 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 2411 sched_priority(td); 2412#ifdef SMP 2413 /* 2414 * Pick the destination cpu and if it isn't ours transfer to the 2415 * target cpu. 2416 */ 2417 cpu = sched_pickcpu(td, flags); 2418 tdq = sched_setcpu(td, cpu, flags); 2419 tdq_add(tdq, td, flags); 2420 if (cpu != PCPU_GET(cpuid)) { 2421 tdq_notify(tdq, td); 2422 return; 2423 } 2424#else 2425 tdq = TDQ_SELF(); 2426 TDQ_LOCK(tdq); 2427 /* 2428 * Now that the thread is moving to the run-queue, set the lock 2429 * to the scheduler's lock. 2430 */ 2431 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 2432 tdq_add(tdq, td, flags); 2433#endif 2434 if (!(flags & SRQ_YIELDING)) 2435 sched_setpreempt(td); 2436} 2437 2438/* 2439 * Remove a thread from a run-queue without running it. This is used 2440 * when we're stealing a thread from a remote queue. Otherwise all threads 2441 * exit by calling sched_exit_thread() and sched_throw() themselves. 2442 */ 2443void 2444sched_rem(struct thread *td) 2445{ 2446 struct tdq *tdq; 2447 2448 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "runq rem", 2449 "prio:%d", td->td_priority); 2450 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL); 2451 tdq = TDQ_CPU(td->td_sched->ts_cpu); 2452 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2453 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2454 KASSERT(TD_ON_RUNQ(td), 2455 ("sched_rem: thread not on run queue")); 2456 tdq_runq_rem(tdq, td); 2457 tdq_load_rem(tdq, td); 2458 TD_SET_CAN_RUN(td); 2459 if (td->td_priority == tdq->tdq_lowpri) 2460 tdq_setlowpri(tdq, NULL); 2461} 2462 2463/* 2464 * Fetch cpu utilization information. Updates on demand. 2465 */ 2466fixpt_t 2467sched_pctcpu(struct thread *td) 2468{ 2469 fixpt_t pctcpu; 2470 struct td_sched *ts; 2471 2472 pctcpu = 0; 2473 ts = td->td_sched; 2474 if (ts == NULL) 2475 return (0); 2476 2477 THREAD_LOCK_ASSERT(td, MA_OWNED); 2478 sched_pctcpu_update(ts, TD_IS_RUNNING(td)); 2479 if (ts->ts_ticks) { 2480 int rtick; 2481 2482 /* How many rtick per second ? */ 2483 rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz); 2484 pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT; 2485 } 2486 2487 return (pctcpu); 2488} 2489 2490/* 2491 * Enforce affinity settings for a thread. Called after adjustments to 2492 * cpumask. 2493 */ 2494void 2495sched_affinity(struct thread *td) 2496{ 2497#ifdef SMP 2498 struct td_sched *ts; 2499 2500 THREAD_LOCK_ASSERT(td, MA_OWNED); 2501 ts = td->td_sched; 2502 if (THREAD_CAN_SCHED(td, ts->ts_cpu)) 2503 return; 2504 if (TD_ON_RUNQ(td)) { 2505 sched_rem(td); 2506 sched_add(td, SRQ_BORING); 2507 return; 2508 } 2509 if (!TD_IS_RUNNING(td)) 2510 return; 2511 /* 2512 * Force a switch before returning to userspace. If the 2513 * target thread is not running locally send an ipi to force 2514 * the issue. 2515 */ 2516 td->td_flags |= TDF_NEEDRESCHED; 2517 if (td != curthread) 2518 ipi_cpu(ts->ts_cpu, IPI_PREEMPT); 2519#endif 2520} 2521 2522/* 2523 * Bind a thread to a target cpu. 2524 */ 2525void 2526sched_bind(struct thread *td, int cpu) 2527{ 2528 struct td_sched *ts; 2529 2530 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 2531 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 2532 ts = td->td_sched; 2533 if (ts->ts_flags & TSF_BOUND) 2534 sched_unbind(td); 2535 KASSERT(THREAD_CAN_MIGRATE(td), ("%p must be migratable", td)); 2536 ts->ts_flags |= TSF_BOUND; 2537 sched_pin(); 2538 if (PCPU_GET(cpuid) == cpu) 2539 return; 2540 ts->ts_cpu = cpu; 2541 /* When we return from mi_switch we'll be on the correct cpu. */ 2542 mi_switch(SW_VOL, NULL); 2543} 2544 2545/* 2546 * Release a bound thread. 2547 */ 2548void 2549sched_unbind(struct thread *td) 2550{ 2551 struct td_sched *ts; 2552 2553 THREAD_LOCK_ASSERT(td, MA_OWNED); 2554 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 2555 ts = td->td_sched; 2556 if ((ts->ts_flags & TSF_BOUND) == 0) 2557 return; 2558 ts->ts_flags &= ~TSF_BOUND; 2559 sched_unpin(); 2560} 2561 2562int 2563sched_is_bound(struct thread *td) 2564{ 2565 THREAD_LOCK_ASSERT(td, MA_OWNED); 2566 return (td->td_sched->ts_flags & TSF_BOUND); 2567} 2568 2569/* 2570 * Basic yield call. 2571 */ 2572void 2573sched_relinquish(struct thread *td) 2574{ 2575 thread_lock(td); 2576 mi_switch(SW_VOL | SWT_RELINQUISH, NULL); 2577 thread_unlock(td); 2578} 2579 2580/* 2581 * Return the total system load. 2582 */ 2583int 2584sched_load(void) 2585{ 2586#ifdef SMP 2587 int total; 2588 int i; 2589 2590 total = 0; 2591 CPU_FOREACH(i) 2592 total += TDQ_CPU(i)->tdq_sysload; 2593 return (total); 2594#else 2595 return (TDQ_SELF()->tdq_sysload); 2596#endif 2597} 2598 2599int 2600sched_sizeof_proc(void) 2601{ 2602 return (sizeof(struct proc)); 2603} 2604 2605int 2606sched_sizeof_thread(void) 2607{ 2608 return (sizeof(struct thread) + sizeof(struct td_sched)); 2609} 2610 2611#ifdef SMP 2612#define TDQ_IDLESPIN(tdq) \ 2613 ((tdq)->tdq_cg != NULL && ((tdq)->tdq_cg->cg_flags & CG_FLAG_THREAD) == 0) 2614#else 2615#define TDQ_IDLESPIN(tdq) 1 2616#endif 2617 2618/* 2619 * The actual idle process. 2620 */ 2621void 2622sched_idletd(void *dummy) 2623{ 2624 struct thread *td; 2625 struct tdq *tdq; 2626 int oldswitchcnt, switchcnt; 2627 int i; 2628 2629 mtx_assert(&Giant, MA_NOTOWNED); 2630 td = curthread; 2631 tdq = TDQ_SELF(); 2632 THREAD_NO_SLEEPING(); 2633 oldswitchcnt = -1; 2634 for (;;) { 2635 if (tdq->tdq_load) { 2636 thread_lock(td); 2637 mi_switch(SW_VOL | SWT_IDLE, NULL); 2638 thread_unlock(td); 2639 } 2640 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2641#ifdef SMP 2642 if (switchcnt != oldswitchcnt) { 2643 oldswitchcnt = switchcnt; 2644 if (tdq_idled(tdq) == 0) 2645 continue; 2646 } 2647 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2648#else 2649 oldswitchcnt = switchcnt; 2650#endif 2651 /* 2652 * If we're switching very frequently, spin while checking 2653 * for load rather than entering a low power state that 2654 * may require an IPI. However, don't do any busy 2655 * loops while on SMT machines as this simply steals 2656 * cycles from cores doing useful work. 2657 */ 2658 if (TDQ_IDLESPIN(tdq) && switchcnt > sched_idlespinthresh) { 2659 for (i = 0; i < sched_idlespins; i++) { 2660 if (tdq->tdq_load) 2661 break; 2662 cpu_spinwait(); 2663 } 2664 } 2665 2666 /* If there was context switch during spin, restart it. */ 2667 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2668 if (tdq->tdq_load != 0 || switchcnt != oldswitchcnt) 2669 continue; 2670 2671 /* Run main MD idle handler. */ 2672 tdq->tdq_cpu_idle = 1; 2673 /* 2674 * Make sure that tdq_cpu_idle update is globally visible 2675 * before cpu_idle() read tdq_load. The order is important 2676 * to avoid race with tdq_notify. 2677 */ 2678 mb(); 2679 cpu_idle(switchcnt * 4 > sched_idlespinthresh); 2680 tdq->tdq_cpu_idle = 0; 2681 2682 /* 2683 * Account thread-less hardware interrupts and 2684 * other wakeup reasons equal to context switches. 2685 */ 2686 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2687 if (switchcnt != oldswitchcnt) 2688 continue; 2689 tdq->tdq_switchcnt++; 2690 oldswitchcnt++; 2691 } 2692} 2693 2694/* 2695 * A CPU is entering for the first time or a thread is exiting. 2696 */ 2697void 2698sched_throw(struct thread *td) 2699{ 2700 struct thread *newtd; 2701 struct tdq *tdq; 2702 2703 tdq = TDQ_SELF(); 2704 if (td == NULL) { 2705 /* Correct spinlock nesting and acquire the correct lock. */ 2706 TDQ_LOCK(tdq); 2707 spinlock_exit(); 2708 PCPU_SET(switchtime, cpu_ticks()); 2709 PCPU_SET(switchticks, ticks); 2710 } else { 2711 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2712 tdq_load_rem(tdq, td); 2713 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 2714 td->td_lastcpu = td->td_oncpu; 2715 td->td_oncpu = NOCPU; 2716 } 2717 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 2718 newtd = choosethread(); 2719 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 2720 cpu_throw(td, newtd); /* doesn't return */ 2721} 2722 2723/* 2724 * This is called from fork_exit(). Just acquire the correct locks and 2725 * let fork do the rest of the work. 2726 */ 2727void 2728sched_fork_exit(struct thread *td) 2729{ 2730 struct tdq *tdq; 2731 int cpuid; 2732 2733 /* 2734 * Finish setting up thread glue so that it begins execution in a 2735 * non-nested critical section with the scheduler lock held. 2736 */ 2737 cpuid = PCPU_GET(cpuid); 2738 tdq = TDQ_CPU(cpuid); 2739 if (TD_IS_IDLETHREAD(td)) 2740 td->td_lock = TDQ_LOCKPTR(tdq); 2741 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2742 td->td_oncpu = cpuid; 2743 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 2744 lock_profile_obtain_lock_success( 2745 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 2746 2747 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running", 2748 "prio:%d", td->td_priority); 2749 SDT_PROBE0(sched, , , on__cpu); 2750} 2751 2752/* 2753 * Create on first use to catch odd startup conditons. 2754 */ 2755char * 2756sched_tdname(struct thread *td) 2757{ 2758#ifdef KTR 2759 struct td_sched *ts; 2760 2761 ts = td->td_sched; 2762 if (ts->ts_name[0] == '\0') 2763 snprintf(ts->ts_name, sizeof(ts->ts_name), 2764 "%s tid %d", td->td_name, td->td_tid); 2765 return (ts->ts_name); 2766#else 2767 return (td->td_name); 2768#endif 2769} 2770 2771#ifdef KTR 2772void 2773sched_clear_tdname(struct thread *td) 2774{ 2775 struct td_sched *ts; 2776 2777 ts = td->td_sched; 2778 ts->ts_name[0] = '\0'; 2779} 2780#endif 2781 2782#ifdef SMP 2783 2784/* 2785 * Build the CPU topology dump string. Is recursively called to collect 2786 * the topology tree. 2787 */ 2788static int 2789sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, struct cpu_group *cg, 2790 int indent) 2791{ 2792 char cpusetbuf[CPUSETBUFSIZ]; 2793 int i, first; 2794 2795 sbuf_printf(sb, "%*s<group level=\"%d\" cache-level=\"%d\">\n", indent, 2796 "", 1 + indent / 2, cg->cg_level); 2797 sbuf_printf(sb, "%*s <cpu count=\"%d\" mask=\"%s\">", indent, "", 2798 cg->cg_count, cpusetobj_strprint(cpusetbuf, &cg->cg_mask)); 2799 first = TRUE; 2800 for (i = 0; i < MAXCPU; i++) { 2801 if (CPU_ISSET(i, &cg->cg_mask)) { 2802 if (!first) 2803 sbuf_printf(sb, ", "); 2804 else 2805 first = FALSE; 2806 sbuf_printf(sb, "%d", i); 2807 } 2808 } 2809 sbuf_printf(sb, "</cpu>\n"); 2810 2811 if (cg->cg_flags != 0) { 2812 sbuf_printf(sb, "%*s <flags>", indent, ""); 2813 if ((cg->cg_flags & CG_FLAG_HTT) != 0) 2814 sbuf_printf(sb, "<flag name=\"HTT\">HTT group</flag>"); 2815 if ((cg->cg_flags & CG_FLAG_THREAD) != 0) 2816 sbuf_printf(sb, "<flag name=\"THREAD\">THREAD group</flag>"); 2817 if ((cg->cg_flags & CG_FLAG_SMT) != 0) 2818 sbuf_printf(sb, "<flag name=\"SMT\">SMT group</flag>"); 2819 sbuf_printf(sb, "</flags>\n"); 2820 } 2821 2822 if (cg->cg_children > 0) { 2823 sbuf_printf(sb, "%*s <children>\n", indent, ""); 2824 for (i = 0; i < cg->cg_children; i++) 2825 sysctl_kern_sched_topology_spec_internal(sb, 2826 &cg->cg_child[i], indent+2); 2827 sbuf_printf(sb, "%*s </children>\n", indent, ""); 2828 } 2829 sbuf_printf(sb, "%*s</group>\n", indent, ""); 2830 return (0); 2831} 2832 2833/* 2834 * Sysctl handler for retrieving topology dump. It's a wrapper for 2835 * the recursive sysctl_kern_smp_topology_spec_internal(). 2836 */ 2837static int 2838sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS) 2839{ 2840 struct sbuf *topo; 2841 int err; 2842 2843 KASSERT(cpu_top != NULL, ("cpu_top isn't initialized")); 2844 2845 topo = sbuf_new(NULL, NULL, 500, SBUF_AUTOEXTEND); 2846 if (topo == NULL) 2847 return (ENOMEM); 2848 2849 sbuf_printf(topo, "<groups>\n"); 2850 err = sysctl_kern_sched_topology_spec_internal(topo, cpu_top, 1); 2851 sbuf_printf(topo, "</groups>\n"); 2852 2853 if (err == 0) { 2854 sbuf_finish(topo); 2855 err = SYSCTL_OUT(req, sbuf_data(topo), sbuf_len(topo)); 2856 } 2857 sbuf_delete(topo); 2858 return (err); 2859} 2860 2861#endif 2862 2863static int 2864sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 2865{ 2866 int error, new_val, period; 2867 2868 period = 1000000 / realstathz; 2869 new_val = period * sched_slice; 2870 error = sysctl_handle_int(oidp, &new_val, 0, req); 2871 if (error != 0 || req->newptr == NULL) 2872 return (error); 2873 if (new_val <= 0) 2874 return (EINVAL); 2875 sched_slice = imax(1, (new_val + period / 2) / period); 2876 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 2877 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 2878 realstathz); 2879 return (0); 2880} 2881 2882SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0, "Scheduler"); 2883SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0, 2884 "Scheduler name"); 2885SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW, 2886 NULL, 0, sysctl_kern_quantum, "I", 2887 "Quantum for timeshare threads in microseconds"); 2888SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, 2889 "Quantum for timeshare threads in stathz ticks"); 2890SYSCTL_INT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0, 2891 "Interactivity score threshold"); 2892SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW, 2893 &preempt_thresh, 0, 2894 "Maximal (lowest) priority for preemption"); 2895SYSCTL_INT(_kern_sched, OID_AUTO, static_boost, CTLFLAG_RW, &static_boost, 0, 2896 "Assign static kernel priorities to sleeping threads"); 2897SYSCTL_INT(_kern_sched, OID_AUTO, idlespins, CTLFLAG_RW, &sched_idlespins, 0, 2898 "Number of times idle thread will spin waiting for new work"); 2899SYSCTL_INT(_kern_sched, OID_AUTO, idlespinthresh, CTLFLAG_RW, 2900 &sched_idlespinthresh, 0, 2901 "Threshold before we will permit idle thread spinning"); 2902#ifdef SMP 2903SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0, 2904 "Number of hz ticks to keep thread affinity for"); 2905SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0, 2906 "Enables the long-term load balancer"); 2907SYSCTL_INT(_kern_sched, OID_AUTO, balance_interval, CTLFLAG_RW, 2908 &balance_interval, 0, 2909 "Average period in stathz ticks to run the long-term balancer"); 2910SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0, 2911 "Attempts to steal work from other cores before idling"); 2912SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0, 2913 "Minimum load on remote CPU before we'll steal"); 2914SYSCTL_PROC(_kern_sched, OID_AUTO, topology_spec, CTLTYPE_STRING | 2915 CTLFLAG_RD, NULL, 0, sysctl_kern_sched_topology_spec, "A", 2916 "XML dump of detected CPU topology"); 2917#endif 2918 2919/* ps compat. All cpu percentages from ULE are weighted. */ 2920static int ccpu = 0; 2921SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 2922