sched_ule.c revision 260817
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 260817 2014-01-17 10:58:59Z 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#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 */ 94struct 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 113static 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 */ 209static int sched_interact = SCHED_INTERACT_THRESH; 210static int tickincr = 8 << SCHED_TICK_SHIFT; 211static int realstathz = 127; /* reset during boot. */ 212static int sched_slice = 10; /* reset during boot. */ 213static int sched_slice_min = 1; /* reset during boot. */ 214#ifdef PREEMPTION 215#ifdef FULL_PREEMPTION 216static int preempt_thresh = PRI_MAX_IDLE; 217#else 218static int preempt_thresh = PRI_MIN_KERN; 219#endif 220#else 221static int preempt_thresh = 0; 222#endif 223static int static_boost = PRI_MIN_BATCH; 224static int sched_idlespins = 10000; 225static 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 */ 232struct 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 264struct 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 */ 272static int rebalance = 1; 273static int balance_interval = 128; /* Default set in sched_initticks(). */ 274static int affinity; 275static int steal_idle = 1; 276static int steal_thresh = 2; 277 278/* 279 * One thread queue per processor. 280 */ 281static struct tdq tdq_cpu[MAXCPU]; 282static struct tdq *balance_tdq; 283static int balance_ticks; 284static 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 */ 290static 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 303static void sched_priority(struct thread *); 304static void sched_thread_priority(struct thread *, u_char); 305static int sched_interact_score(struct thread *); 306static void sched_interact_update(struct thread *); 307static void sched_interact_fork(struct thread *); 308static void sched_pctcpu_update(struct td_sched *, int); 309 310/* Operations on per processor queues */ 311static struct thread *tdq_choose(struct tdq *); 312static void tdq_setup(struct tdq *); 313static void tdq_load_add(struct tdq *, struct thread *); 314static void tdq_load_rem(struct tdq *, struct thread *); 315static __inline void tdq_runq_add(struct tdq *, struct thread *, int); 316static __inline void tdq_runq_rem(struct tdq *, struct thread *); 317static inline int sched_shouldpreempt(int, int, int); 318void tdq_print(int cpu); 319static void runq_print(struct runq *rq); 320static void tdq_add(struct tdq *, struct thread *, int); 321#ifdef SMP 322static int tdq_move(struct tdq *, struct tdq *); 323static int tdq_idled(struct tdq *); 324static void tdq_notify(struct tdq *, struct thread *); 325static struct thread *tdq_steal(struct tdq *, int); 326static struct thread *runq_steal(struct runq *, int); 327static int sched_pickcpu(struct thread *, int); 328static void sched_balance(void); 329static int sched_balance_pair(struct tdq *, struct tdq *); 330static inline struct tdq *sched_setcpu(struct thread *, int, int); 331static inline void thread_unblock_switch(struct thread *, struct mtx *); 332static struct mtx *sched_switch_migrate(struct tdq *, struct thread *, int); 333static int sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS); 334static int sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, 335 struct cpu_group *cg, int indent); 336#endif 337 338static void sched_setup(void *dummy); 339SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL); 340 341static void sched_initticks(void *dummy); 342SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks, 343 NULL); 344 345SDT_PROVIDER_DEFINE(sched); 346 347SDT_PROBE_DEFINE3(sched, , , change__pri, "struct thread *", 348 "struct proc *", "uint8_t"); 349SDT_PROBE_DEFINE3(sched, , , dequeue, "struct thread *", 350 "struct proc *", "void *"); 351SDT_PROBE_DEFINE4(sched, , , enqueue, "struct thread *", 352 "struct proc *", "void *", "int"); 353SDT_PROBE_DEFINE4(sched, , , lend__pri, "struct thread *", 354 "struct proc *", "uint8_t", "struct thread *"); 355SDT_PROBE_DEFINE2(sched, , , load__change, "int", "int"); 356SDT_PROBE_DEFINE2(sched, , , off__cpu, "struct thread *", 357 "struct proc *"); 358SDT_PROBE_DEFINE(sched, , , on__cpu); 359SDT_PROBE_DEFINE(sched, , , remain__cpu); 360SDT_PROBE_DEFINE2(sched, , , surrender, "struct thread *", 361 "struct proc *"); 362 363/* 364 * Print the threads waiting on a run-queue. 365 */ 366static void 367runq_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 */ 394void 395tdq_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 419static inline int 420sched_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 */ 457static __inline void 458tdq_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 */ 508static __inline void 509tdq_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 */ 534static void 535tdq_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 */ 552static void 553tdq_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 */ 574static inline int 575tdq_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 */ 596static void 597tdq_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 612struct 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 629static __inline int cpu_search(const struct cpu_group *cg, struct cpu_search *low, 630 struct cpu_search *high, const int match); 631int cpu_search_lowest(const struct cpu_group *cg, struct cpu_search *low); 632int cpu_search_highest(const struct cpu_group *cg, struct cpu_search *high); 633int 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 */ 647static __inline int 648cpu_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; ; ) { 671 if (i == 0) { 672#ifdef HAVE_INLINE_FFSL 673 cpu = CPU_FFS(&cpumask) - 1; 674#else 675 while (cpu >= 0 && !CPU_ISSET(cpu, &cpumask)) 676 cpu--; 677#endif 678 if (cpu < 0) 679 break; 680 child = NULL; 681 } else 682 child = &cg->cg_child[i - 1]; 683 684 if (match & CPU_SEARCH_LOWEST) 685 lgroup.cs_cpu = -1; 686 if (match & CPU_SEARCH_HIGHEST) 687 hgroup.cs_cpu = -1; 688 if (child) { /* Handle child CPU group. */ 689 CPU_NAND(&cpumask, &child->cg_mask); 690 switch (match) { 691 case CPU_SEARCH_LOWEST: 692 load = cpu_search_lowest(child, &lgroup); 693 break; 694 case CPU_SEARCH_HIGHEST: 695 load = cpu_search_highest(child, &hgroup); 696 break; 697 case CPU_SEARCH_BOTH: 698 load = cpu_search_both(child, &lgroup, &hgroup); 699 break; 700 } 701 } else { /* Handle child CPU. */ 702 CPU_CLR(cpu, &cpumask); 703 tdq = TDQ_CPU(cpu); 704 load = tdq->tdq_load * 256; 705 rndptr = DPCPU_PTR(randomval); 706 rnd = (*rndptr = *rndptr * 69069 + 5) >> 26; 707 if (match & CPU_SEARCH_LOWEST) { 708 if (cpu == low->cs_prefer) 709 load -= 64; 710 /* If that CPU is allowed and get data. */ 711 if (tdq->tdq_lowpri > lgroup.cs_pri && 712 tdq->tdq_load <= lgroup.cs_limit && 713 CPU_ISSET(cpu, &lgroup.cs_mask)) { 714 lgroup.cs_cpu = cpu; 715 lgroup.cs_load = load - rnd; 716 } 717 } 718 if (match & CPU_SEARCH_HIGHEST) 719 if (tdq->tdq_load >= hgroup.cs_limit && 720 tdq->tdq_transferable && 721 CPU_ISSET(cpu, &hgroup.cs_mask)) { 722 hgroup.cs_cpu = cpu; 723 hgroup.cs_load = load - rnd; 724 } 725 } 726 total += load; 727 728 /* We have info about child item. Compare it. */ 729 if (match & CPU_SEARCH_LOWEST) { 730 if (lgroup.cs_cpu >= 0 && 731 (load < lload || 732 (load == lload && lgroup.cs_load < low->cs_load))) { 733 lload = load; 734 low->cs_cpu = lgroup.cs_cpu; 735 low->cs_load = lgroup.cs_load; 736 } 737 } 738 if (match & CPU_SEARCH_HIGHEST) 739 if (hgroup.cs_cpu >= 0 && 740 (load > hload || 741 (load == hload && hgroup.cs_load > high->cs_load))) { 742 hload = load; 743 high->cs_cpu = hgroup.cs_cpu; 744 high->cs_load = hgroup.cs_load; 745 } 746 if (child) { 747 i--; 748 if (i == 0 && CPU_EMPTY(&cpumask)) 749 break; 750 } 751#ifndef HAVE_INLINE_FFSL 752 else 753 cpu--; 754#endif 755 } 756 return (total); 757} 758 759/* 760 * cpu_search instantiations must pass constants to maintain the inline 761 * optimization. 762 */ 763int 764cpu_search_lowest(const struct cpu_group *cg, struct cpu_search *low) 765{ 766 return cpu_search(cg, low, NULL, CPU_SEARCH_LOWEST); 767} 768 769int 770cpu_search_highest(const struct cpu_group *cg, struct cpu_search *high) 771{ 772 return cpu_search(cg, NULL, high, CPU_SEARCH_HIGHEST); 773} 774 775int 776cpu_search_both(const struct cpu_group *cg, struct cpu_search *low, 777 struct cpu_search *high) 778{ 779 return cpu_search(cg, low, high, CPU_SEARCH_BOTH); 780} 781 782/* 783 * Find the cpu with the least load via the least loaded path that has a 784 * lowpri greater than pri pri. A pri of -1 indicates any priority is 785 * acceptable. 786 */ 787static inline int 788sched_lowest(const struct cpu_group *cg, cpuset_t mask, int pri, int maxload, 789 int prefer) 790{ 791 struct cpu_search low; 792 793 low.cs_cpu = -1; 794 low.cs_prefer = prefer; 795 low.cs_mask = mask; 796 low.cs_pri = pri; 797 low.cs_limit = maxload; 798 cpu_search_lowest(cg, &low); 799 return low.cs_cpu; 800} 801 802/* 803 * Find the cpu with the highest load via the highest loaded path. 804 */ 805static inline int 806sched_highest(const struct cpu_group *cg, cpuset_t mask, int minload) 807{ 808 struct cpu_search high; 809 810 high.cs_cpu = -1; 811 high.cs_mask = mask; 812 high.cs_limit = minload; 813 cpu_search_highest(cg, &high); 814 return high.cs_cpu; 815} 816 817static void 818sched_balance_group(struct cpu_group *cg) 819{ 820 cpuset_t hmask, lmask; 821 int high, low, anylow; 822 823 CPU_FILL(&hmask); 824 for (;;) { 825 high = sched_highest(cg, hmask, 1); 826 /* Stop if there is no more CPU with transferrable threads. */ 827 if (high == -1) 828 break; 829 CPU_CLR(high, &hmask); 830 CPU_COPY(&hmask, &lmask); 831 /* Stop if there is no more CPU left for low. */ 832 if (CPU_EMPTY(&lmask)) 833 break; 834 anylow = 1; 835nextlow: 836 low = sched_lowest(cg, lmask, -1, 837 TDQ_CPU(high)->tdq_load - 1, high); 838 /* Stop if we looked well and found no less loaded CPU. */ 839 if (anylow && low == -1) 840 break; 841 /* Go to next high if we found no less loaded CPU. */ 842 if (low == -1) 843 continue; 844 /* Transfer thread from high to low. */ 845 if (sched_balance_pair(TDQ_CPU(high), TDQ_CPU(low))) { 846 /* CPU that got thread can no longer be a donor. */ 847 CPU_CLR(low, &hmask); 848 } else { 849 /* 850 * If failed, then there is no threads on high 851 * that can run on this low. Drop low from low 852 * mask and look for different one. 853 */ 854 CPU_CLR(low, &lmask); 855 anylow = 0; 856 goto nextlow; 857 } 858 } 859} 860 861static void 862sched_balance(void) 863{ 864 struct tdq *tdq; 865 866 /* 867 * Select a random time between .5 * balance_interval and 868 * 1.5 * balance_interval. 869 */ 870 balance_ticks = max(balance_interval / 2, 1); 871 balance_ticks += random() % balance_interval; 872 if (smp_started == 0 || rebalance == 0) 873 return; 874 tdq = TDQ_SELF(); 875 TDQ_UNLOCK(tdq); 876 sched_balance_group(cpu_top); 877 TDQ_LOCK(tdq); 878} 879 880/* 881 * Lock two thread queues using their address to maintain lock order. 882 */ 883static void 884tdq_lock_pair(struct tdq *one, struct tdq *two) 885{ 886 if (one < two) { 887 TDQ_LOCK(one); 888 TDQ_LOCK_FLAGS(two, MTX_DUPOK); 889 } else { 890 TDQ_LOCK(two); 891 TDQ_LOCK_FLAGS(one, MTX_DUPOK); 892 } 893} 894 895/* 896 * Unlock two thread queues. Order is not important here. 897 */ 898static void 899tdq_unlock_pair(struct tdq *one, struct tdq *two) 900{ 901 TDQ_UNLOCK(one); 902 TDQ_UNLOCK(two); 903} 904 905/* 906 * Transfer load between two imbalanced thread queues. 907 */ 908static int 909sched_balance_pair(struct tdq *high, struct tdq *low) 910{ 911 int moved; 912 int cpu; 913 914 tdq_lock_pair(high, low); 915 moved = 0; 916 /* 917 * Determine what the imbalance is and then adjust that to how many 918 * threads we actually have to give up (transferable). 919 */ 920 if (high->tdq_transferable != 0 && high->tdq_load > low->tdq_load && 921 (moved = tdq_move(high, low)) > 0) { 922 /* 923 * In case the target isn't the current cpu IPI it to force a 924 * reschedule with the new workload. 925 */ 926 cpu = TDQ_ID(low); 927 if (cpu != PCPU_GET(cpuid)) 928 ipi_cpu(cpu, IPI_PREEMPT); 929 } 930 tdq_unlock_pair(high, low); 931 return (moved); 932} 933 934/* 935 * Move a thread from one thread queue to another. 936 */ 937static int 938tdq_move(struct tdq *from, struct tdq *to) 939{ 940 struct td_sched *ts; 941 struct thread *td; 942 struct tdq *tdq; 943 int cpu; 944 945 TDQ_LOCK_ASSERT(from, MA_OWNED); 946 TDQ_LOCK_ASSERT(to, MA_OWNED); 947 948 tdq = from; 949 cpu = TDQ_ID(to); 950 td = tdq_steal(tdq, cpu); 951 if (td == NULL) 952 return (0); 953 ts = td->td_sched; 954 /* 955 * Although the run queue is locked the thread may be blocked. Lock 956 * it to clear this and acquire the run-queue lock. 957 */ 958 thread_lock(td); 959 /* Drop recursive lock on from acquired via thread_lock(). */ 960 TDQ_UNLOCK(from); 961 sched_rem(td); 962 ts->ts_cpu = cpu; 963 td->td_lock = TDQ_LOCKPTR(to); 964 tdq_add(to, td, SRQ_YIELDING); 965 return (1); 966} 967 968/* 969 * This tdq has idled. Try to steal a thread from another cpu and switch 970 * to it. 971 */ 972static int 973tdq_idled(struct tdq *tdq) 974{ 975 struct cpu_group *cg; 976 struct tdq *steal; 977 cpuset_t mask; 978 int thresh; 979 int cpu; 980 981 if (smp_started == 0 || steal_idle == 0) 982 return (1); 983 CPU_FILL(&mask); 984 CPU_CLR(PCPU_GET(cpuid), &mask); 985 /* We don't want to be preempted while we're iterating. */ 986 spinlock_enter(); 987 for (cg = tdq->tdq_cg; cg != NULL; ) { 988 if ((cg->cg_flags & CG_FLAG_THREAD) == 0) 989 thresh = steal_thresh; 990 else 991 thresh = 1; 992 cpu = sched_highest(cg, mask, thresh); 993 if (cpu == -1) { 994 cg = cg->cg_parent; 995 continue; 996 } 997 steal = TDQ_CPU(cpu); 998 CPU_CLR(cpu, &mask); 999 tdq_lock_pair(tdq, steal); 1000 if (steal->tdq_load < thresh || steal->tdq_transferable == 0) { 1001 tdq_unlock_pair(tdq, steal); 1002 continue; 1003 } 1004 /* 1005 * If a thread was added while interrupts were disabled don't 1006 * steal one here. If we fail to acquire one due to affinity 1007 * restrictions loop again with this cpu removed from the 1008 * set. 1009 */ 1010 if (tdq->tdq_load == 0 && tdq_move(steal, tdq) == 0) { 1011 tdq_unlock_pair(tdq, steal); 1012 continue; 1013 } 1014 spinlock_exit(); 1015 TDQ_UNLOCK(steal); 1016 mi_switch(SW_VOL | SWT_IDLE, NULL); 1017 thread_unlock(curthread); 1018 1019 return (0); 1020 } 1021 spinlock_exit(); 1022 return (1); 1023} 1024 1025/* 1026 * Notify a remote cpu of new work. Sends an IPI if criteria are met. 1027 */ 1028static void 1029tdq_notify(struct tdq *tdq, struct thread *td) 1030{ 1031 struct thread *ctd; 1032 int pri; 1033 int cpu; 1034 1035 if (tdq->tdq_ipipending) 1036 return; 1037 cpu = td->td_sched->ts_cpu; 1038 pri = td->td_priority; 1039 ctd = pcpu_find(cpu)->pc_curthread; 1040 if (!sched_shouldpreempt(pri, ctd->td_priority, 1)) 1041 return; 1042 if (TD_IS_IDLETHREAD(ctd)) { 1043 /* 1044 * If the MD code has an idle wakeup routine try that before 1045 * falling back to IPI. 1046 */ 1047 if (!tdq->tdq_cpu_idle || cpu_idle_wakeup(cpu)) 1048 return; 1049 } 1050 tdq->tdq_ipipending = 1; 1051 ipi_cpu(cpu, IPI_PREEMPT); 1052} 1053 1054/* 1055 * Steals load from a timeshare queue. Honors the rotating queue head 1056 * index. 1057 */ 1058static struct thread * 1059runq_steal_from(struct runq *rq, int cpu, u_char start) 1060{ 1061 struct rqbits *rqb; 1062 struct rqhead *rqh; 1063 struct thread *td, *first; 1064 int bit; 1065 int pri; 1066 int i; 1067 1068 rqb = &rq->rq_status; 1069 bit = start & (RQB_BPW -1); 1070 pri = 0; 1071 first = NULL; 1072again: 1073 for (i = RQB_WORD(start); i < RQB_LEN; bit = 0, i++) { 1074 if (rqb->rqb_bits[i] == 0) 1075 continue; 1076 if (bit != 0) { 1077 for (pri = bit; pri < RQB_BPW; pri++) 1078 if (rqb->rqb_bits[i] & (1ul << pri)) 1079 break; 1080 if (pri >= RQB_BPW) 1081 continue; 1082 } else 1083 pri = RQB_FFS(rqb->rqb_bits[i]); 1084 pri += (i << RQB_L2BPW); 1085 rqh = &rq->rq_queues[pri]; 1086 TAILQ_FOREACH(td, rqh, td_runq) { 1087 if (first && THREAD_CAN_MIGRATE(td) && 1088 THREAD_CAN_SCHED(td, cpu)) 1089 return (td); 1090 first = td; 1091 } 1092 } 1093 if (start != 0) { 1094 start = 0; 1095 goto again; 1096 } 1097 1098 if (first && THREAD_CAN_MIGRATE(first) && 1099 THREAD_CAN_SCHED(first, cpu)) 1100 return (first); 1101 return (NULL); 1102} 1103 1104/* 1105 * Steals load from a standard linear queue. 1106 */ 1107static struct thread * 1108runq_steal(struct runq *rq, int cpu) 1109{ 1110 struct rqhead *rqh; 1111 struct rqbits *rqb; 1112 struct thread *td; 1113 int word; 1114 int bit; 1115 1116 rqb = &rq->rq_status; 1117 for (word = 0; word < RQB_LEN; word++) { 1118 if (rqb->rqb_bits[word] == 0) 1119 continue; 1120 for (bit = 0; bit < RQB_BPW; bit++) { 1121 if ((rqb->rqb_bits[word] & (1ul << bit)) == 0) 1122 continue; 1123 rqh = &rq->rq_queues[bit + (word << RQB_L2BPW)]; 1124 TAILQ_FOREACH(td, rqh, td_runq) 1125 if (THREAD_CAN_MIGRATE(td) && 1126 THREAD_CAN_SCHED(td, cpu)) 1127 return (td); 1128 } 1129 } 1130 return (NULL); 1131} 1132 1133/* 1134 * Attempt to steal a thread in priority order from a thread queue. 1135 */ 1136static struct thread * 1137tdq_steal(struct tdq *tdq, int cpu) 1138{ 1139 struct thread *td; 1140 1141 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1142 if ((td = runq_steal(&tdq->tdq_realtime, cpu)) != NULL) 1143 return (td); 1144 if ((td = runq_steal_from(&tdq->tdq_timeshare, 1145 cpu, tdq->tdq_ridx)) != NULL) 1146 return (td); 1147 return (runq_steal(&tdq->tdq_idle, cpu)); 1148} 1149 1150/* 1151 * Sets the thread lock and ts_cpu to match the requested cpu. Unlocks the 1152 * current lock and returns with the assigned queue locked. 1153 */ 1154static inline struct tdq * 1155sched_setcpu(struct thread *td, int cpu, int flags) 1156{ 1157 1158 struct tdq *tdq; 1159 1160 THREAD_LOCK_ASSERT(td, MA_OWNED); 1161 tdq = TDQ_CPU(cpu); 1162 td->td_sched->ts_cpu = cpu; 1163 /* 1164 * If the lock matches just return the queue. 1165 */ 1166 if (td->td_lock == TDQ_LOCKPTR(tdq)) 1167 return (tdq); 1168#ifdef notyet 1169 /* 1170 * If the thread isn't running its lockptr is a 1171 * turnstile or a sleepqueue. We can just lock_set without 1172 * blocking. 1173 */ 1174 if (TD_CAN_RUN(td)) { 1175 TDQ_LOCK(tdq); 1176 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 1177 return (tdq); 1178 } 1179#endif 1180 /* 1181 * The hard case, migration, we need to block the thread first to 1182 * prevent order reversals with other cpus locks. 1183 */ 1184 spinlock_enter(); 1185 thread_lock_block(td); 1186 TDQ_LOCK(tdq); 1187 thread_lock_unblock(td, TDQ_LOCKPTR(tdq)); 1188 spinlock_exit(); 1189 return (tdq); 1190} 1191 1192SCHED_STAT_DEFINE(pickcpu_intrbind, "Soft interrupt binding"); 1193SCHED_STAT_DEFINE(pickcpu_idle_affinity, "Picked idle cpu based on affinity"); 1194SCHED_STAT_DEFINE(pickcpu_affinity, "Picked cpu based on affinity"); 1195SCHED_STAT_DEFINE(pickcpu_lowest, "Selected lowest load"); 1196SCHED_STAT_DEFINE(pickcpu_local, "Migrated to current cpu"); 1197SCHED_STAT_DEFINE(pickcpu_migration, "Selection may have caused migration"); 1198 1199static int 1200sched_pickcpu(struct thread *td, int flags) 1201{ 1202 struct cpu_group *cg, *ccg; 1203 struct td_sched *ts; 1204 struct tdq *tdq; 1205 cpuset_t mask; 1206 int cpu, pri, self; 1207 1208 self = PCPU_GET(cpuid); 1209 ts = td->td_sched; 1210 if (smp_started == 0) 1211 return (self); 1212 /* 1213 * Don't migrate a running thread from sched_switch(). 1214 */ 1215 if ((flags & SRQ_OURSELF) || !THREAD_CAN_MIGRATE(td)) 1216 return (ts->ts_cpu); 1217 /* 1218 * Prefer to run interrupt threads on the processors that generate 1219 * the interrupt. 1220 */ 1221 pri = td->td_priority; 1222 if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_SCHED(td, self) && 1223 curthread->td_intr_nesting_level && ts->ts_cpu != self) { 1224 SCHED_STAT_INC(pickcpu_intrbind); 1225 ts->ts_cpu = self; 1226 if (TDQ_CPU(self)->tdq_lowpri > pri) { 1227 SCHED_STAT_INC(pickcpu_affinity); 1228 return (ts->ts_cpu); 1229 } 1230 } 1231 /* 1232 * If the thread can run on the last cpu and the affinity has not 1233 * expired or it is idle run it there. 1234 */ 1235 tdq = TDQ_CPU(ts->ts_cpu); 1236 cg = tdq->tdq_cg; 1237 if (THREAD_CAN_SCHED(td, ts->ts_cpu) && 1238 tdq->tdq_lowpri >= PRI_MIN_IDLE && 1239 SCHED_AFFINITY(ts, CG_SHARE_L2)) { 1240 if (cg->cg_flags & CG_FLAG_THREAD) { 1241 CPUSET_FOREACH(cpu, cg->cg_mask) { 1242 if (TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE) 1243 break; 1244 } 1245 } else 1246 cpu = INT_MAX; 1247 if (cpu > mp_maxid) { 1248 SCHED_STAT_INC(pickcpu_idle_affinity); 1249 return (ts->ts_cpu); 1250 } 1251 } 1252 /* 1253 * Search for the last level cache CPU group in the tree. 1254 * Skip caches with expired affinity time and SMT groups. 1255 * Affinity to higher level caches will be handled less aggressively. 1256 */ 1257 for (ccg = NULL; cg != NULL; cg = cg->cg_parent) { 1258 if (cg->cg_flags & CG_FLAG_THREAD) 1259 continue; 1260 if (!SCHED_AFFINITY(ts, cg->cg_level)) 1261 continue; 1262 ccg = cg; 1263 } 1264 if (ccg != NULL) 1265 cg = ccg; 1266 cpu = -1; 1267 /* Search the group for the less loaded idle CPU we can run now. */ 1268 mask = td->td_cpuset->cs_mask; 1269 if (cg != NULL && cg != cpu_top && 1270 CPU_CMP(&cg->cg_mask, &cpu_top->cg_mask) != 0) 1271 cpu = sched_lowest(cg, mask, max(pri, PRI_MAX_TIMESHARE), 1272 INT_MAX, ts->ts_cpu); 1273 /* Search globally for the less loaded CPU we can run now. */ 1274 if (cpu == -1) 1275 cpu = sched_lowest(cpu_top, mask, pri, INT_MAX, ts->ts_cpu); 1276 /* Search globally for the less loaded CPU. */ 1277 if (cpu == -1) 1278 cpu = sched_lowest(cpu_top, mask, -1, INT_MAX, ts->ts_cpu); 1279 KASSERT(cpu != -1, ("sched_pickcpu: Failed to find a cpu.")); 1280 /* 1281 * Compare the lowest loaded cpu to current cpu. 1282 */ 1283 if (THREAD_CAN_SCHED(td, self) && TDQ_CPU(self)->tdq_lowpri > pri && 1284 TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE && 1285 TDQ_CPU(self)->tdq_load <= TDQ_CPU(cpu)->tdq_load + 1) { 1286 SCHED_STAT_INC(pickcpu_local); 1287 cpu = self; 1288 } else 1289 SCHED_STAT_INC(pickcpu_lowest); 1290 if (cpu != ts->ts_cpu) 1291 SCHED_STAT_INC(pickcpu_migration); 1292 return (cpu); 1293} 1294#endif 1295 1296/* 1297 * Pick the highest priority task we have and return it. 1298 */ 1299static struct thread * 1300tdq_choose(struct tdq *tdq) 1301{ 1302 struct thread *td; 1303 1304 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 1305 td = runq_choose(&tdq->tdq_realtime); 1306 if (td != NULL) 1307 return (td); 1308 td = runq_choose_from(&tdq->tdq_timeshare, tdq->tdq_ridx); 1309 if (td != NULL) { 1310 KASSERT(td->td_priority >= PRI_MIN_BATCH, 1311 ("tdq_choose: Invalid priority on timeshare queue %d", 1312 td->td_priority)); 1313 return (td); 1314 } 1315 td = runq_choose(&tdq->tdq_idle); 1316 if (td != NULL) { 1317 KASSERT(td->td_priority >= PRI_MIN_IDLE, 1318 ("tdq_choose: Invalid priority on idle queue %d", 1319 td->td_priority)); 1320 return (td); 1321 } 1322 1323 return (NULL); 1324} 1325 1326/* 1327 * Initialize a thread queue. 1328 */ 1329static void 1330tdq_setup(struct tdq *tdq) 1331{ 1332 1333 if (bootverbose) 1334 printf("ULE: setup cpu %d\n", TDQ_ID(tdq)); 1335 runq_init(&tdq->tdq_realtime); 1336 runq_init(&tdq->tdq_timeshare); 1337 runq_init(&tdq->tdq_idle); 1338 snprintf(tdq->tdq_name, sizeof(tdq->tdq_name), 1339 "sched lock %d", (int)TDQ_ID(tdq)); 1340 mtx_init(&tdq->tdq_lock, tdq->tdq_name, "sched lock", 1341 MTX_SPIN | MTX_RECURSE); 1342#ifdef KTR 1343 snprintf(tdq->tdq_loadname, sizeof(tdq->tdq_loadname), 1344 "CPU %d load", (int)TDQ_ID(tdq)); 1345#endif 1346} 1347 1348#ifdef SMP 1349static void 1350sched_setup_smp(void) 1351{ 1352 struct tdq *tdq; 1353 int i; 1354 1355 cpu_top = smp_topo(); 1356 CPU_FOREACH(i) { 1357 tdq = TDQ_CPU(i); 1358 tdq_setup(tdq); 1359 tdq->tdq_cg = smp_topo_find(cpu_top, i); 1360 if (tdq->tdq_cg == NULL) 1361 panic("Can't find cpu group for %d\n", i); 1362 } 1363 balance_tdq = TDQ_SELF(); 1364 sched_balance(); 1365} 1366#endif 1367 1368/* 1369 * Setup the thread queues and initialize the topology based on MD 1370 * information. 1371 */ 1372static void 1373sched_setup(void *dummy) 1374{ 1375 struct tdq *tdq; 1376 1377 tdq = TDQ_SELF(); 1378#ifdef SMP 1379 sched_setup_smp(); 1380#else 1381 tdq_setup(tdq); 1382#endif 1383 1384 /* Add thread0's load since it's running. */ 1385 TDQ_LOCK(tdq); 1386 thread0.td_lock = TDQ_LOCKPTR(TDQ_SELF()); 1387 tdq_load_add(tdq, &thread0); 1388 tdq->tdq_lowpri = thread0.td_priority; 1389 TDQ_UNLOCK(tdq); 1390} 1391 1392/* 1393 * This routine determines time constants after stathz and hz are setup. 1394 */ 1395/* ARGSUSED */ 1396static void 1397sched_initticks(void *dummy) 1398{ 1399 int incr; 1400 1401 realstathz = stathz ? stathz : hz; 1402 sched_slice = realstathz / SCHED_SLICE_DEFAULT_DIVISOR; 1403 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 1404 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 1405 realstathz); 1406 1407 /* 1408 * tickincr is shifted out by 10 to avoid rounding errors due to 1409 * hz not being evenly divisible by stathz on all platforms. 1410 */ 1411 incr = (hz << SCHED_TICK_SHIFT) / realstathz; 1412 /* 1413 * This does not work for values of stathz that are more than 1414 * 1 << SCHED_TICK_SHIFT * hz. In practice this does not happen. 1415 */ 1416 if (incr == 0) 1417 incr = 1; 1418 tickincr = incr; 1419#ifdef SMP 1420 /* 1421 * Set the default balance interval now that we know 1422 * what realstathz is. 1423 */ 1424 balance_interval = realstathz; 1425 affinity = SCHED_AFFINITY_DEFAULT; 1426#endif 1427 if (sched_idlespinthresh < 0) 1428 sched_idlespinthresh = 2 * max(10000, 6 * hz) / realstathz; 1429} 1430 1431 1432/* 1433 * This is the core of the interactivity algorithm. Determines a score based 1434 * on past behavior. It is the ratio of sleep time to run time scaled to 1435 * a [0, 100] integer. This is the voluntary sleep time of a process, which 1436 * differs from the cpu usage because it does not account for time spent 1437 * waiting on a run-queue. Would be prettier if we had floating point. 1438 */ 1439static int 1440sched_interact_score(struct thread *td) 1441{ 1442 struct td_sched *ts; 1443 int div; 1444 1445 ts = td->td_sched; 1446 /* 1447 * The score is only needed if this is likely to be an interactive 1448 * task. Don't go through the expense of computing it if there's 1449 * no chance. 1450 */ 1451 if (sched_interact <= SCHED_INTERACT_HALF && 1452 ts->ts_runtime >= ts->ts_slptime) 1453 return (SCHED_INTERACT_HALF); 1454 1455 if (ts->ts_runtime > ts->ts_slptime) { 1456 div = max(1, ts->ts_runtime / SCHED_INTERACT_HALF); 1457 return (SCHED_INTERACT_HALF + 1458 (SCHED_INTERACT_HALF - (ts->ts_slptime / div))); 1459 } 1460 if (ts->ts_slptime > ts->ts_runtime) { 1461 div = max(1, ts->ts_slptime / SCHED_INTERACT_HALF); 1462 return (ts->ts_runtime / div); 1463 } 1464 /* runtime == slptime */ 1465 if (ts->ts_runtime) 1466 return (SCHED_INTERACT_HALF); 1467 1468 /* 1469 * This can happen if slptime and runtime are 0. 1470 */ 1471 return (0); 1472 1473} 1474 1475/* 1476 * Scale the scheduling priority according to the "interactivity" of this 1477 * process. 1478 */ 1479static void 1480sched_priority(struct thread *td) 1481{ 1482 int score; 1483 int pri; 1484 1485 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 1486 return; 1487 /* 1488 * If the score is interactive we place the thread in the realtime 1489 * queue with a priority that is less than kernel and interrupt 1490 * priorities. These threads are not subject to nice restrictions. 1491 * 1492 * Scores greater than this are placed on the normal timeshare queue 1493 * where the priority is partially decided by the most recent cpu 1494 * utilization and the rest is decided by nice value. 1495 * 1496 * The nice value of the process has a linear effect on the calculated 1497 * score. Negative nice values make it easier for a thread to be 1498 * considered interactive. 1499 */ 1500 score = imax(0, sched_interact_score(td) + td->td_proc->p_nice); 1501 if (score < sched_interact) { 1502 pri = PRI_MIN_INTERACT; 1503 pri += ((PRI_MAX_INTERACT - PRI_MIN_INTERACT + 1) / 1504 sched_interact) * score; 1505 KASSERT(pri >= PRI_MIN_INTERACT && pri <= PRI_MAX_INTERACT, 1506 ("sched_priority: invalid interactive priority %d score %d", 1507 pri, score)); 1508 } else { 1509 pri = SCHED_PRI_MIN; 1510 if (td->td_sched->ts_ticks) 1511 pri += min(SCHED_PRI_TICKS(td->td_sched), 1512 SCHED_PRI_RANGE - 1); 1513 pri += SCHED_PRI_NICE(td->td_proc->p_nice); 1514 KASSERT(pri >= PRI_MIN_BATCH && pri <= PRI_MAX_BATCH, 1515 ("sched_priority: invalid priority %d: nice %d, " 1516 "ticks %d ftick %d ltick %d tick pri %d", 1517 pri, td->td_proc->p_nice, td->td_sched->ts_ticks, 1518 td->td_sched->ts_ftick, td->td_sched->ts_ltick, 1519 SCHED_PRI_TICKS(td->td_sched))); 1520 } 1521 sched_user_prio(td, pri); 1522 1523 return; 1524} 1525 1526/* 1527 * This routine enforces a maximum limit on the amount of scheduling history 1528 * kept. It is called after either the slptime or runtime is adjusted. This 1529 * function is ugly due to integer math. 1530 */ 1531static void 1532sched_interact_update(struct thread *td) 1533{ 1534 struct td_sched *ts; 1535 u_int sum; 1536 1537 ts = td->td_sched; 1538 sum = ts->ts_runtime + ts->ts_slptime; 1539 if (sum < SCHED_SLP_RUN_MAX) 1540 return; 1541 /* 1542 * This only happens from two places: 1543 * 1) We have added an unusual amount of run time from fork_exit. 1544 * 2) We have added an unusual amount of sleep time from sched_sleep(). 1545 */ 1546 if (sum > SCHED_SLP_RUN_MAX * 2) { 1547 if (ts->ts_runtime > ts->ts_slptime) { 1548 ts->ts_runtime = SCHED_SLP_RUN_MAX; 1549 ts->ts_slptime = 1; 1550 } else { 1551 ts->ts_slptime = SCHED_SLP_RUN_MAX; 1552 ts->ts_runtime = 1; 1553 } 1554 return; 1555 } 1556 /* 1557 * If we have exceeded by more than 1/5th then the algorithm below 1558 * will not bring us back into range. Dividing by two here forces 1559 * us into the range of [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX] 1560 */ 1561 if (sum > (SCHED_SLP_RUN_MAX / 5) * 6) { 1562 ts->ts_runtime /= 2; 1563 ts->ts_slptime /= 2; 1564 return; 1565 } 1566 ts->ts_runtime = (ts->ts_runtime / 5) * 4; 1567 ts->ts_slptime = (ts->ts_slptime / 5) * 4; 1568} 1569 1570/* 1571 * Scale back the interactivity history when a child thread is created. The 1572 * history is inherited from the parent but the thread may behave totally 1573 * differently. For example, a shell spawning a compiler process. We want 1574 * to learn that the compiler is behaving badly very quickly. 1575 */ 1576static void 1577sched_interact_fork(struct thread *td) 1578{ 1579 int ratio; 1580 int sum; 1581 1582 sum = td->td_sched->ts_runtime + td->td_sched->ts_slptime; 1583 if (sum > SCHED_SLP_RUN_FORK) { 1584 ratio = sum / SCHED_SLP_RUN_FORK; 1585 td->td_sched->ts_runtime /= ratio; 1586 td->td_sched->ts_slptime /= ratio; 1587 } 1588} 1589 1590/* 1591 * Called from proc0_init() to setup the scheduler fields. 1592 */ 1593void 1594schedinit(void) 1595{ 1596 1597 /* 1598 * Set up the scheduler specific parts of proc0. 1599 */ 1600 proc0.p_sched = NULL; /* XXX */ 1601 thread0.td_sched = &td_sched0; 1602 td_sched0.ts_ltick = ticks; 1603 td_sched0.ts_ftick = ticks; 1604 td_sched0.ts_slice = 0; 1605} 1606 1607/* 1608 * This is only somewhat accurate since given many processes of the same 1609 * priority they will switch when their slices run out, which will be 1610 * at most sched_slice stathz ticks. 1611 */ 1612int 1613sched_rr_interval(void) 1614{ 1615 1616 /* Convert sched_slice from stathz to hz. */ 1617 return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz)); 1618} 1619 1620/* 1621 * Update the percent cpu tracking information when it is requested or 1622 * the total history exceeds the maximum. We keep a sliding history of 1623 * tick counts that slowly decays. This is less precise than the 4BSD 1624 * mechanism since it happens with less regular and frequent events. 1625 */ 1626static void 1627sched_pctcpu_update(struct td_sched *ts, int run) 1628{ 1629 int t = ticks; 1630 1631 if (t - ts->ts_ltick >= SCHED_TICK_TARG) { 1632 ts->ts_ticks = 0; 1633 ts->ts_ftick = t - SCHED_TICK_TARG; 1634 } else if (t - ts->ts_ftick >= SCHED_TICK_MAX) { 1635 ts->ts_ticks = (ts->ts_ticks / (ts->ts_ltick - ts->ts_ftick)) * 1636 (ts->ts_ltick - (t - SCHED_TICK_TARG)); 1637 ts->ts_ftick = t - SCHED_TICK_TARG; 1638 } 1639 if (run) 1640 ts->ts_ticks += (t - ts->ts_ltick) << SCHED_TICK_SHIFT; 1641 ts->ts_ltick = t; 1642} 1643 1644/* 1645 * Adjust the priority of a thread. Move it to the appropriate run-queue 1646 * if necessary. This is the back-end for several priority related 1647 * functions. 1648 */ 1649static void 1650sched_thread_priority(struct thread *td, u_char prio) 1651{ 1652 struct td_sched *ts; 1653 struct tdq *tdq; 1654 int oldpri; 1655 1656 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "prio", 1657 "prio:%d", td->td_priority, "new prio:%d", prio, 1658 KTR_ATTR_LINKED, sched_tdname(curthread)); 1659 SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio); 1660 if (td != curthread && prio < td->td_priority) { 1661 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread), 1662 "lend prio", "prio:%d", td->td_priority, "new prio:%d", 1663 prio, KTR_ATTR_LINKED, sched_tdname(td)); 1664 SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio, 1665 curthread); 1666 } 1667 ts = td->td_sched; 1668 THREAD_LOCK_ASSERT(td, MA_OWNED); 1669 if (td->td_priority == prio) 1670 return; 1671 /* 1672 * If the priority has been elevated due to priority 1673 * propagation, we may have to move ourselves to a new 1674 * queue. This could be optimized to not re-add in some 1675 * cases. 1676 */ 1677 if (TD_ON_RUNQ(td) && prio < td->td_priority) { 1678 sched_rem(td); 1679 td->td_priority = prio; 1680 sched_add(td, SRQ_BORROWING); 1681 return; 1682 } 1683 /* 1684 * If the thread is currently running we may have to adjust the lowpri 1685 * information so other cpus are aware of our current priority. 1686 */ 1687 if (TD_IS_RUNNING(td)) { 1688 tdq = TDQ_CPU(ts->ts_cpu); 1689 oldpri = td->td_priority; 1690 td->td_priority = prio; 1691 if (prio < tdq->tdq_lowpri) 1692 tdq->tdq_lowpri = prio; 1693 else if (tdq->tdq_lowpri == oldpri) 1694 tdq_setlowpri(tdq, td); 1695 return; 1696 } 1697 td->td_priority = prio; 1698} 1699 1700/* 1701 * Update a thread's priority when it is lent another thread's 1702 * priority. 1703 */ 1704void 1705sched_lend_prio(struct thread *td, u_char prio) 1706{ 1707 1708 td->td_flags |= TDF_BORROWING; 1709 sched_thread_priority(td, prio); 1710} 1711 1712/* 1713 * Restore a thread's priority when priority propagation is 1714 * over. The prio argument is the minimum priority the thread 1715 * needs to have to satisfy other possible priority lending 1716 * requests. If the thread's regular priority is less 1717 * important than prio, the thread will keep a priority boost 1718 * of prio. 1719 */ 1720void 1721sched_unlend_prio(struct thread *td, u_char prio) 1722{ 1723 u_char base_pri; 1724 1725 if (td->td_base_pri >= PRI_MIN_TIMESHARE && 1726 td->td_base_pri <= PRI_MAX_TIMESHARE) 1727 base_pri = td->td_user_pri; 1728 else 1729 base_pri = td->td_base_pri; 1730 if (prio >= base_pri) { 1731 td->td_flags &= ~TDF_BORROWING; 1732 sched_thread_priority(td, base_pri); 1733 } else 1734 sched_lend_prio(td, prio); 1735} 1736 1737/* 1738 * Standard entry for setting the priority to an absolute value. 1739 */ 1740void 1741sched_prio(struct thread *td, u_char prio) 1742{ 1743 u_char oldprio; 1744 1745 /* First, update the base priority. */ 1746 td->td_base_pri = prio; 1747 1748 /* 1749 * If the thread is borrowing another thread's priority, don't 1750 * ever lower the priority. 1751 */ 1752 if (td->td_flags & TDF_BORROWING && td->td_priority < prio) 1753 return; 1754 1755 /* Change the real priority. */ 1756 oldprio = td->td_priority; 1757 sched_thread_priority(td, prio); 1758 1759 /* 1760 * If the thread is on a turnstile, then let the turnstile update 1761 * its state. 1762 */ 1763 if (TD_ON_LOCK(td) && oldprio != prio) 1764 turnstile_adjust(td, oldprio); 1765} 1766 1767/* 1768 * Set the base user priority, does not effect current running priority. 1769 */ 1770void 1771sched_user_prio(struct thread *td, u_char prio) 1772{ 1773 1774 td->td_base_user_pri = prio; 1775 if (td->td_lend_user_pri <= prio) 1776 return; 1777 td->td_user_pri = prio; 1778} 1779 1780void 1781sched_lend_user_prio(struct thread *td, u_char prio) 1782{ 1783 1784 THREAD_LOCK_ASSERT(td, MA_OWNED); 1785 td->td_lend_user_pri = prio; 1786 td->td_user_pri = min(prio, td->td_base_user_pri); 1787 if (td->td_priority > td->td_user_pri) 1788 sched_prio(td, td->td_user_pri); 1789 else if (td->td_priority != td->td_user_pri) 1790 td->td_flags |= TDF_NEEDRESCHED; 1791} 1792 1793/* 1794 * Handle migration from sched_switch(). This happens only for 1795 * cpu binding. 1796 */ 1797static struct mtx * 1798sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags) 1799{ 1800 struct tdq *tdn; 1801 1802 tdn = TDQ_CPU(td->td_sched->ts_cpu); 1803#ifdef SMP 1804 tdq_load_rem(tdq, td); 1805 /* 1806 * Do the lock dance required to avoid LOR. We grab an extra 1807 * spinlock nesting to prevent preemption while we're 1808 * not holding either run-queue lock. 1809 */ 1810 spinlock_enter(); 1811 thread_lock_block(td); /* This releases the lock on tdq. */ 1812 1813 /* 1814 * Acquire both run-queue locks before placing the thread on the new 1815 * run-queue to avoid deadlocks created by placing a thread with a 1816 * blocked lock on the run-queue of a remote processor. The deadlock 1817 * occurs when a third processor attempts to lock the two queues in 1818 * question while the target processor is spinning with its own 1819 * run-queue lock held while waiting for the blocked lock to clear. 1820 */ 1821 tdq_lock_pair(tdn, tdq); 1822 tdq_add(tdn, td, flags); 1823 tdq_notify(tdn, td); 1824 TDQ_UNLOCK(tdn); 1825 spinlock_exit(); 1826#endif 1827 return (TDQ_LOCKPTR(tdn)); 1828} 1829 1830/* 1831 * Variadic version of thread_lock_unblock() that does not assume td_lock 1832 * is blocked. 1833 */ 1834static inline void 1835thread_unblock_switch(struct thread *td, struct mtx *mtx) 1836{ 1837 atomic_store_rel_ptr((volatile uintptr_t *)&td->td_lock, 1838 (uintptr_t)mtx); 1839} 1840 1841/* 1842 * Switch threads. This function has to handle threads coming in while 1843 * blocked for some reason, running, or idle. It also must deal with 1844 * migrating a thread from one queue to another as running threads may 1845 * be assigned elsewhere via binding. 1846 */ 1847void 1848sched_switch(struct thread *td, struct thread *newtd, int flags) 1849{ 1850 struct tdq *tdq; 1851 struct td_sched *ts; 1852 struct mtx *mtx; 1853 int srqflag; 1854 int cpuid, preempted; 1855 1856 THREAD_LOCK_ASSERT(td, MA_OWNED); 1857 KASSERT(newtd == NULL, ("sched_switch: Unsupported newtd argument")); 1858 1859 cpuid = PCPU_GET(cpuid); 1860 tdq = TDQ_CPU(cpuid); 1861 ts = td->td_sched; 1862 mtx = td->td_lock; 1863 sched_pctcpu_update(ts, 1); 1864 ts->ts_rltick = ticks; 1865 td->td_lastcpu = td->td_oncpu; 1866 td->td_oncpu = NOCPU; 1867 preempted = !(td->td_flags & TDF_SLICEEND); 1868 td->td_flags &= ~(TDF_NEEDRESCHED | TDF_SLICEEND); 1869 td->td_owepreempt = 0; 1870 if (!TD_IS_IDLETHREAD(td)) 1871 tdq->tdq_switchcnt++; 1872 /* 1873 * The lock pointer in an idle thread should never change. Reset it 1874 * to CAN_RUN as well. 1875 */ 1876 if (TD_IS_IDLETHREAD(td)) { 1877 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1878 TD_SET_CAN_RUN(td); 1879 } else if (TD_IS_RUNNING(td)) { 1880 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1881 srqflag = preempted ? 1882 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED : 1883 SRQ_OURSELF|SRQ_YIELDING; 1884#ifdef SMP 1885 if (THREAD_CAN_MIGRATE(td) && !THREAD_CAN_SCHED(td, ts->ts_cpu)) 1886 ts->ts_cpu = sched_pickcpu(td, 0); 1887#endif 1888 if (ts->ts_cpu == cpuid) 1889 tdq_runq_add(tdq, td, srqflag); 1890 else { 1891 KASSERT(THREAD_CAN_MIGRATE(td) || 1892 (ts->ts_flags & TSF_BOUND) != 0, 1893 ("Thread %p shouldn't migrate", td)); 1894 mtx = sched_switch_migrate(tdq, td, srqflag); 1895 } 1896 } else { 1897 /* This thread must be going to sleep. */ 1898 TDQ_LOCK(tdq); 1899 mtx = thread_lock_block(td); 1900 tdq_load_rem(tdq, td); 1901 } 1902 /* 1903 * We enter here with the thread blocked and assigned to the 1904 * appropriate cpu run-queue or sleep-queue and with the current 1905 * thread-queue locked. 1906 */ 1907 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 1908 newtd = choosethread(); 1909 /* 1910 * Call the MD code to switch contexts if necessary. 1911 */ 1912 if (td != newtd) { 1913#ifdef HWPMC_HOOKS 1914 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1915 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 1916#endif 1917 SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc); 1918 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 1919 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 1920 sched_pctcpu_update(newtd->td_sched, 0); 1921 1922#ifdef KDTRACE_HOOKS 1923 /* 1924 * If DTrace has set the active vtime enum to anything 1925 * other than INACTIVE (0), then it should have set the 1926 * function to call. 1927 */ 1928 if (dtrace_vtime_active) 1929 (*dtrace_vtime_switch_func)(newtd); 1930#endif 1931 1932 cpu_switch(td, newtd, mtx); 1933 /* 1934 * We may return from cpu_switch on a different cpu. However, 1935 * we always return with td_lock pointing to the current cpu's 1936 * run queue lock. 1937 */ 1938 cpuid = PCPU_GET(cpuid); 1939 tdq = TDQ_CPU(cpuid); 1940 lock_profile_obtain_lock_success( 1941 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 1942 1943 SDT_PROBE0(sched, , , on__cpu); 1944#ifdef HWPMC_HOOKS 1945 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 1946 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN); 1947#endif 1948 } else { 1949 thread_unblock_switch(td, mtx); 1950 SDT_PROBE0(sched, , , remain__cpu); 1951 } 1952 /* 1953 * Assert that all went well and return. 1954 */ 1955 TDQ_LOCK_ASSERT(tdq, MA_OWNED|MA_NOTRECURSED); 1956 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 1957 td->td_oncpu = cpuid; 1958} 1959 1960/* 1961 * Adjust thread priorities as a result of a nice request. 1962 */ 1963void 1964sched_nice(struct proc *p, int nice) 1965{ 1966 struct thread *td; 1967 1968 PROC_LOCK_ASSERT(p, MA_OWNED); 1969 1970 p->p_nice = nice; 1971 FOREACH_THREAD_IN_PROC(p, td) { 1972 thread_lock(td); 1973 sched_priority(td); 1974 sched_prio(td, td->td_base_user_pri); 1975 thread_unlock(td); 1976 } 1977} 1978 1979/* 1980 * Record the sleep time for the interactivity scorer. 1981 */ 1982void 1983sched_sleep(struct thread *td, int prio) 1984{ 1985 1986 THREAD_LOCK_ASSERT(td, MA_OWNED); 1987 1988 td->td_slptick = ticks; 1989 if (TD_IS_SUSPENDED(td) || prio >= PSOCK) 1990 td->td_flags |= TDF_CANSWAP; 1991 if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE) 1992 return; 1993 if (static_boost == 1 && prio) 1994 sched_prio(td, prio); 1995 else if (static_boost && td->td_priority > static_boost) 1996 sched_prio(td, static_boost); 1997} 1998 1999/* 2000 * Schedule a thread to resume execution and record how long it voluntarily 2001 * slept. We also update the pctcpu, interactivity, and priority. 2002 */ 2003void 2004sched_wakeup(struct thread *td) 2005{ 2006 struct td_sched *ts; 2007 int slptick; 2008 2009 THREAD_LOCK_ASSERT(td, MA_OWNED); 2010 ts = td->td_sched; 2011 td->td_flags &= ~TDF_CANSWAP; 2012 /* 2013 * If we slept for more than a tick update our interactivity and 2014 * priority. 2015 */ 2016 slptick = td->td_slptick; 2017 td->td_slptick = 0; 2018 if (slptick && slptick != ticks) { 2019 ts->ts_slptime += (ticks - slptick) << SCHED_TICK_SHIFT; 2020 sched_interact_update(td); 2021 sched_pctcpu_update(ts, 0); 2022 } 2023 /* 2024 * Reset the slice value since we slept and advanced the round-robin. 2025 */ 2026 ts->ts_slice = 0; 2027 sched_add(td, SRQ_BORING); 2028} 2029 2030/* 2031 * Penalize the parent for creating a new child and initialize the child's 2032 * priority. 2033 */ 2034void 2035sched_fork(struct thread *td, struct thread *child) 2036{ 2037 THREAD_LOCK_ASSERT(td, MA_OWNED); 2038 sched_pctcpu_update(td->td_sched, 1); 2039 sched_fork_thread(td, child); 2040 /* 2041 * Penalize the parent and child for forking. 2042 */ 2043 sched_interact_fork(child); 2044 sched_priority(child); 2045 td->td_sched->ts_runtime += tickincr; 2046 sched_interact_update(td); 2047 sched_priority(td); 2048} 2049 2050/* 2051 * Fork a new thread, may be within the same process. 2052 */ 2053void 2054sched_fork_thread(struct thread *td, struct thread *child) 2055{ 2056 struct td_sched *ts; 2057 struct td_sched *ts2; 2058 struct tdq *tdq; 2059 2060 tdq = TDQ_SELF(); 2061 THREAD_LOCK_ASSERT(td, MA_OWNED); 2062 /* 2063 * Initialize child. 2064 */ 2065 ts = td->td_sched; 2066 ts2 = child->td_sched; 2067 child->td_lock = TDQ_LOCKPTR(tdq); 2068 child->td_cpuset = cpuset_ref(td->td_cpuset); 2069 ts2->ts_cpu = ts->ts_cpu; 2070 ts2->ts_flags = 0; 2071 /* 2072 * Grab our parents cpu estimation information. 2073 */ 2074 ts2->ts_ticks = ts->ts_ticks; 2075 ts2->ts_ltick = ts->ts_ltick; 2076 ts2->ts_ftick = ts->ts_ftick; 2077 /* 2078 * Do not inherit any borrowed priority from the parent. 2079 */ 2080 child->td_priority = child->td_base_pri; 2081 /* 2082 * And update interactivity score. 2083 */ 2084 ts2->ts_slptime = ts->ts_slptime; 2085 ts2->ts_runtime = ts->ts_runtime; 2086 /* Attempt to quickly learn interactivity. */ 2087 ts2->ts_slice = tdq_slice(tdq) - sched_slice_min; 2088#ifdef KTR 2089 bzero(ts2->ts_name, sizeof(ts2->ts_name)); 2090#endif 2091} 2092 2093/* 2094 * Adjust the priority class of a thread. 2095 */ 2096void 2097sched_class(struct thread *td, int class) 2098{ 2099 2100 THREAD_LOCK_ASSERT(td, MA_OWNED); 2101 if (td->td_pri_class == class) 2102 return; 2103 td->td_pri_class = class; 2104} 2105 2106/* 2107 * Return some of the child's priority and interactivity to the parent. 2108 */ 2109void 2110sched_exit(struct proc *p, struct thread *child) 2111{ 2112 struct thread *td; 2113 2114 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "proc exit", 2115 "prio:%d", child->td_priority); 2116 PROC_LOCK_ASSERT(p, MA_OWNED); 2117 td = FIRST_THREAD_IN_PROC(p); 2118 sched_exit_thread(td, child); 2119} 2120 2121/* 2122 * Penalize another thread for the time spent on this one. This helps to 2123 * worsen the priority and interactivity of processes which schedule batch 2124 * jobs such as make. This has little effect on the make process itself but 2125 * causes new processes spawned by it to receive worse scores immediately. 2126 */ 2127void 2128sched_exit_thread(struct thread *td, struct thread *child) 2129{ 2130 2131 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "thread exit", 2132 "prio:%d", child->td_priority); 2133 /* 2134 * Give the child's runtime to the parent without returning the 2135 * sleep time as a penalty to the parent. This causes shells that 2136 * launch expensive things to mark their children as expensive. 2137 */ 2138 thread_lock(td); 2139 td->td_sched->ts_runtime += child->td_sched->ts_runtime; 2140 sched_interact_update(td); 2141 sched_priority(td); 2142 thread_unlock(td); 2143} 2144 2145void 2146sched_preempt(struct thread *td) 2147{ 2148 struct tdq *tdq; 2149 2150 SDT_PROBE2(sched, , , surrender, td, td->td_proc); 2151 2152 thread_lock(td); 2153 tdq = TDQ_SELF(); 2154 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2155 tdq->tdq_ipipending = 0; 2156 if (td->td_priority > tdq->tdq_lowpri) { 2157 int flags; 2158 2159 flags = SW_INVOL | SW_PREEMPT; 2160 if (td->td_critnest > 1) 2161 td->td_owepreempt = 1; 2162 else if (TD_IS_IDLETHREAD(td)) 2163 mi_switch(flags | SWT_REMOTEWAKEIDLE, NULL); 2164 else 2165 mi_switch(flags | SWT_REMOTEPREEMPT, NULL); 2166 } 2167 thread_unlock(td); 2168} 2169 2170/* 2171 * Fix priorities on return to user-space. Priorities may be elevated due 2172 * to static priorities in msleep() or similar. 2173 */ 2174void 2175sched_userret(struct thread *td) 2176{ 2177 /* 2178 * XXX we cheat slightly on the locking here to avoid locking in 2179 * the usual case. Setting td_priority here is essentially an 2180 * incomplete workaround for not setting it properly elsewhere. 2181 * Now that some interrupt handlers are threads, not setting it 2182 * properly elsewhere can clobber it in the window between setting 2183 * it here and returning to user mode, so don't waste time setting 2184 * it perfectly here. 2185 */ 2186 KASSERT((td->td_flags & TDF_BORROWING) == 0, 2187 ("thread with borrowed priority returning to userland")); 2188 if (td->td_priority != td->td_user_pri) { 2189 thread_lock(td); 2190 td->td_priority = td->td_user_pri; 2191 td->td_base_pri = td->td_user_pri; 2192 tdq_setlowpri(TDQ_SELF(), td); 2193 thread_unlock(td); 2194 } 2195} 2196 2197/* 2198 * Handle a stathz tick. This is really only relevant for timeshare 2199 * threads. 2200 */ 2201void 2202sched_clock(struct thread *td) 2203{ 2204 struct tdq *tdq; 2205 struct td_sched *ts; 2206 2207 THREAD_LOCK_ASSERT(td, MA_OWNED); 2208 tdq = TDQ_SELF(); 2209#ifdef SMP 2210 /* 2211 * We run the long term load balancer infrequently on the first cpu. 2212 */ 2213 if (balance_tdq == tdq) { 2214 if (balance_ticks && --balance_ticks == 0) 2215 sched_balance(); 2216 } 2217#endif 2218 /* 2219 * Save the old switch count so we have a record of the last ticks 2220 * activity. Initialize the new switch count based on our load. 2221 * If there is some activity seed it to reflect that. 2222 */ 2223 tdq->tdq_oldswitchcnt = tdq->tdq_switchcnt; 2224 tdq->tdq_switchcnt = tdq->tdq_load; 2225 /* 2226 * Advance the insert index once for each tick to ensure that all 2227 * threads get a chance to run. 2228 */ 2229 if (tdq->tdq_idx == tdq->tdq_ridx) { 2230 tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS; 2231 if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx])) 2232 tdq->tdq_ridx = tdq->tdq_idx; 2233 } 2234 ts = td->td_sched; 2235 sched_pctcpu_update(ts, 1); 2236 if (td->td_pri_class & PRI_FIFO_BIT) 2237 return; 2238 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) { 2239 /* 2240 * We used a tick; charge it to the thread so 2241 * that we can compute our interactivity. 2242 */ 2243 td->td_sched->ts_runtime += tickincr; 2244 sched_interact_update(td); 2245 sched_priority(td); 2246 } 2247 2248 /* 2249 * Force a context switch if the current thread has used up a full 2250 * time slice (default is 100ms). 2251 */ 2252 if (!TD_IS_IDLETHREAD(td) && ++ts->ts_slice >= tdq_slice(tdq)) { 2253 ts->ts_slice = 0; 2254 td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND; 2255 } 2256} 2257 2258/* 2259 * Called once per hz tick. 2260 */ 2261void 2262sched_tick(int cnt) 2263{ 2264 2265} 2266 2267/* 2268 * Return whether the current CPU has runnable tasks. Used for in-kernel 2269 * cooperative idle threads. 2270 */ 2271int 2272sched_runnable(void) 2273{ 2274 struct tdq *tdq; 2275 int load; 2276 2277 load = 1; 2278 2279 tdq = TDQ_SELF(); 2280 if ((curthread->td_flags & TDF_IDLETD) != 0) { 2281 if (tdq->tdq_load > 0) 2282 goto out; 2283 } else 2284 if (tdq->tdq_load - 1 > 0) 2285 goto out; 2286 load = 0; 2287out: 2288 return (load); 2289} 2290 2291/* 2292 * Choose the highest priority thread to run. The thread is removed from 2293 * the run-queue while running however the load remains. For SMP we set 2294 * the tdq in the global idle bitmask if it idles here. 2295 */ 2296struct thread * 2297sched_choose(void) 2298{ 2299 struct thread *td; 2300 struct tdq *tdq; 2301 2302 tdq = TDQ_SELF(); 2303 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2304 td = tdq_choose(tdq); 2305 if (td) { 2306 tdq_runq_rem(tdq, td); 2307 tdq->tdq_lowpri = td->td_priority; 2308 return (td); 2309 } 2310 tdq->tdq_lowpri = PRI_MAX_IDLE; 2311 return (PCPU_GET(idlethread)); 2312} 2313 2314/* 2315 * Set owepreempt if necessary. Preemption never happens directly in ULE, 2316 * we always request it once we exit a critical section. 2317 */ 2318static inline void 2319sched_setpreempt(struct thread *td) 2320{ 2321 struct thread *ctd; 2322 int cpri; 2323 int pri; 2324 2325 THREAD_LOCK_ASSERT(curthread, MA_OWNED); 2326 2327 ctd = curthread; 2328 pri = td->td_priority; 2329 cpri = ctd->td_priority; 2330 if (pri < cpri) 2331 ctd->td_flags |= TDF_NEEDRESCHED; 2332 if (panicstr != NULL || pri >= cpri || cold || TD_IS_INHIBITED(ctd)) 2333 return; 2334 if (!sched_shouldpreempt(pri, cpri, 0)) 2335 return; 2336 ctd->td_owepreempt = 1; 2337} 2338 2339/* 2340 * Add a thread to a thread queue. Select the appropriate runq and add the 2341 * thread to it. This is the internal function called when the tdq is 2342 * predetermined. 2343 */ 2344void 2345tdq_add(struct tdq *tdq, struct thread *td, int flags) 2346{ 2347 2348 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2349 KASSERT((td->td_inhibitors == 0), 2350 ("sched_add: trying to run inhibited thread")); 2351 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 2352 ("sched_add: bad thread state")); 2353 KASSERT(td->td_flags & TDF_INMEM, 2354 ("sched_add: thread swapped out")); 2355 2356 if (td->td_priority < tdq->tdq_lowpri) 2357 tdq->tdq_lowpri = td->td_priority; 2358 tdq_runq_add(tdq, td, flags); 2359 tdq_load_add(tdq, td); 2360} 2361 2362/* 2363 * Select the target thread queue and add a thread to it. Request 2364 * preemption or IPI a remote processor if required. 2365 */ 2366void 2367sched_add(struct thread *td, int flags) 2368{ 2369 struct tdq *tdq; 2370#ifdef SMP 2371 int cpu; 2372#endif 2373 2374 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add", 2375 "prio:%d", td->td_priority, KTR_ATTR_LINKED, 2376 sched_tdname(curthread)); 2377 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup", 2378 KTR_ATTR_LINKED, sched_tdname(td)); 2379 SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL, 2380 flags & SRQ_PREEMPTED); 2381 THREAD_LOCK_ASSERT(td, MA_OWNED); 2382 /* 2383 * Recalculate the priority before we select the target cpu or 2384 * run-queue. 2385 */ 2386 if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) 2387 sched_priority(td); 2388#ifdef SMP 2389 /* 2390 * Pick the destination cpu and if it isn't ours transfer to the 2391 * target cpu. 2392 */ 2393 cpu = sched_pickcpu(td, flags); 2394 tdq = sched_setcpu(td, cpu, flags); 2395 tdq_add(tdq, td, flags); 2396 if (cpu != PCPU_GET(cpuid)) { 2397 tdq_notify(tdq, td); 2398 return; 2399 } 2400#else 2401 tdq = TDQ_SELF(); 2402 TDQ_LOCK(tdq); 2403 /* 2404 * Now that the thread is moving to the run-queue, set the lock 2405 * to the scheduler's lock. 2406 */ 2407 thread_lock_set(td, TDQ_LOCKPTR(tdq)); 2408 tdq_add(tdq, td, flags); 2409#endif 2410 if (!(flags & SRQ_YIELDING)) 2411 sched_setpreempt(td); 2412} 2413 2414/* 2415 * Remove a thread from a run-queue without running it. This is used 2416 * when we're stealing a thread from a remote queue. Otherwise all threads 2417 * exit by calling sched_exit_thread() and sched_throw() themselves. 2418 */ 2419void 2420sched_rem(struct thread *td) 2421{ 2422 struct tdq *tdq; 2423 2424 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "runq rem", 2425 "prio:%d", td->td_priority); 2426 SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL); 2427 tdq = TDQ_CPU(td->td_sched->ts_cpu); 2428 TDQ_LOCK_ASSERT(tdq, MA_OWNED); 2429 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2430 KASSERT(TD_ON_RUNQ(td), 2431 ("sched_rem: thread not on run queue")); 2432 tdq_runq_rem(tdq, td); 2433 tdq_load_rem(tdq, td); 2434 TD_SET_CAN_RUN(td); 2435 if (td->td_priority == tdq->tdq_lowpri) 2436 tdq_setlowpri(tdq, NULL); 2437} 2438 2439/* 2440 * Fetch cpu utilization information. Updates on demand. 2441 */ 2442fixpt_t 2443sched_pctcpu(struct thread *td) 2444{ 2445 fixpt_t pctcpu; 2446 struct td_sched *ts; 2447 2448 pctcpu = 0; 2449 ts = td->td_sched; 2450 if (ts == NULL) 2451 return (0); 2452 2453 THREAD_LOCK_ASSERT(td, MA_OWNED); 2454 sched_pctcpu_update(ts, TD_IS_RUNNING(td)); 2455 if (ts->ts_ticks) { 2456 int rtick; 2457 2458 /* How many rtick per second ? */ 2459 rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz); 2460 pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT; 2461 } 2462 2463 return (pctcpu); 2464} 2465 2466/* 2467 * Enforce affinity settings for a thread. Called after adjustments to 2468 * cpumask. 2469 */ 2470void 2471sched_affinity(struct thread *td) 2472{ 2473#ifdef SMP 2474 struct td_sched *ts; 2475 2476 THREAD_LOCK_ASSERT(td, MA_OWNED); 2477 ts = td->td_sched; 2478 if (THREAD_CAN_SCHED(td, ts->ts_cpu)) 2479 return; 2480 if (TD_ON_RUNQ(td)) { 2481 sched_rem(td); 2482 sched_add(td, SRQ_BORING); 2483 return; 2484 } 2485 if (!TD_IS_RUNNING(td)) 2486 return; 2487 /* 2488 * Force a switch before returning to userspace. If the 2489 * target thread is not running locally send an ipi to force 2490 * the issue. 2491 */ 2492 td->td_flags |= TDF_NEEDRESCHED; 2493 if (td != curthread) 2494 ipi_cpu(ts->ts_cpu, IPI_PREEMPT); 2495#endif 2496} 2497 2498/* 2499 * Bind a thread to a target cpu. 2500 */ 2501void 2502sched_bind(struct thread *td, int cpu) 2503{ 2504 struct td_sched *ts; 2505 2506 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED); 2507 KASSERT(td == curthread, ("sched_bind: can only bind curthread")); 2508 ts = td->td_sched; 2509 if (ts->ts_flags & TSF_BOUND) 2510 sched_unbind(td); 2511 KASSERT(THREAD_CAN_MIGRATE(td), ("%p must be migratable", td)); 2512 ts->ts_flags |= TSF_BOUND; 2513 sched_pin(); 2514 if (PCPU_GET(cpuid) == cpu) 2515 return; 2516 ts->ts_cpu = cpu; 2517 /* When we return from mi_switch we'll be on the correct cpu. */ 2518 mi_switch(SW_VOL, NULL); 2519} 2520 2521/* 2522 * Release a bound thread. 2523 */ 2524void 2525sched_unbind(struct thread *td) 2526{ 2527 struct td_sched *ts; 2528 2529 THREAD_LOCK_ASSERT(td, MA_OWNED); 2530 KASSERT(td == curthread, ("sched_unbind: can only bind curthread")); 2531 ts = td->td_sched; 2532 if ((ts->ts_flags & TSF_BOUND) == 0) 2533 return; 2534 ts->ts_flags &= ~TSF_BOUND; 2535 sched_unpin(); 2536} 2537 2538int 2539sched_is_bound(struct thread *td) 2540{ 2541 THREAD_LOCK_ASSERT(td, MA_OWNED); 2542 return (td->td_sched->ts_flags & TSF_BOUND); 2543} 2544 2545/* 2546 * Basic yield call. 2547 */ 2548void 2549sched_relinquish(struct thread *td) 2550{ 2551 thread_lock(td); 2552 mi_switch(SW_VOL | SWT_RELINQUISH, NULL); 2553 thread_unlock(td); 2554} 2555 2556/* 2557 * Return the total system load. 2558 */ 2559int 2560sched_load(void) 2561{ 2562#ifdef SMP 2563 int total; 2564 int i; 2565 2566 total = 0; 2567 CPU_FOREACH(i) 2568 total += TDQ_CPU(i)->tdq_sysload; 2569 return (total); 2570#else 2571 return (TDQ_SELF()->tdq_sysload); 2572#endif 2573} 2574 2575int 2576sched_sizeof_proc(void) 2577{ 2578 return (sizeof(struct proc)); 2579} 2580 2581int 2582sched_sizeof_thread(void) 2583{ 2584 return (sizeof(struct thread) + sizeof(struct td_sched)); 2585} 2586 2587#ifdef SMP 2588#define TDQ_IDLESPIN(tdq) \ 2589 ((tdq)->tdq_cg != NULL && ((tdq)->tdq_cg->cg_flags & CG_FLAG_THREAD) == 0) 2590#else 2591#define TDQ_IDLESPIN(tdq) 1 2592#endif 2593 2594/* 2595 * The actual idle process. 2596 */ 2597void 2598sched_idletd(void *dummy) 2599{ 2600 struct thread *td; 2601 struct tdq *tdq; 2602 int oldswitchcnt, switchcnt; 2603 int i; 2604 2605 mtx_assert(&Giant, MA_NOTOWNED); 2606 td = curthread; 2607 tdq = TDQ_SELF(); 2608 THREAD_NO_SLEEPING(); 2609 oldswitchcnt = -1; 2610 for (;;) { 2611 if (tdq->tdq_load) { 2612 thread_lock(td); 2613 mi_switch(SW_VOL | SWT_IDLE, NULL); 2614 thread_unlock(td); 2615 } 2616 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2617#ifdef SMP 2618 if (switchcnt != oldswitchcnt) { 2619 oldswitchcnt = switchcnt; 2620 if (tdq_idled(tdq) == 0) 2621 continue; 2622 } 2623 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2624#else 2625 oldswitchcnt = switchcnt; 2626#endif 2627 /* 2628 * If we're switching very frequently, spin while checking 2629 * for load rather than entering a low power state that 2630 * may require an IPI. However, don't do any busy 2631 * loops while on SMT machines as this simply steals 2632 * cycles from cores doing useful work. 2633 */ 2634 if (TDQ_IDLESPIN(tdq) && switchcnt > sched_idlespinthresh) { 2635 for (i = 0; i < sched_idlespins; i++) { 2636 if (tdq->tdq_load) 2637 break; 2638 cpu_spinwait(); 2639 } 2640 } 2641 2642 /* If there was context switch during spin, restart it. */ 2643 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2644 if (tdq->tdq_load != 0 || switchcnt != oldswitchcnt) 2645 continue; 2646 2647 /* Run main MD idle handler. */ 2648 tdq->tdq_cpu_idle = 1; 2649 cpu_idle(switchcnt * 4 > sched_idlespinthresh); 2650 tdq->tdq_cpu_idle = 0; 2651 2652 /* 2653 * Account thread-less hardware interrupts and 2654 * other wakeup reasons equal to context switches. 2655 */ 2656 switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; 2657 if (switchcnt != oldswitchcnt) 2658 continue; 2659 tdq->tdq_switchcnt++; 2660 oldswitchcnt++; 2661 } 2662} 2663 2664/* 2665 * A CPU is entering for the first time or a thread is exiting. 2666 */ 2667void 2668sched_throw(struct thread *td) 2669{ 2670 struct thread *newtd; 2671 struct tdq *tdq; 2672 2673 tdq = TDQ_SELF(); 2674 if (td == NULL) { 2675 /* Correct spinlock nesting and acquire the correct lock. */ 2676 TDQ_LOCK(tdq); 2677 spinlock_exit(); 2678 PCPU_SET(switchtime, cpu_ticks()); 2679 PCPU_SET(switchticks, ticks); 2680 } else { 2681 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2682 tdq_load_rem(tdq, td); 2683 lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object); 2684 } 2685 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count")); 2686 newtd = choosethread(); 2687 TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd; 2688 cpu_throw(td, newtd); /* doesn't return */ 2689} 2690 2691/* 2692 * This is called from fork_exit(). Just acquire the correct locks and 2693 * let fork do the rest of the work. 2694 */ 2695void 2696sched_fork_exit(struct thread *td) 2697{ 2698 struct td_sched *ts; 2699 struct tdq *tdq; 2700 int cpuid; 2701 2702 /* 2703 * Finish setting up thread glue so that it begins execution in a 2704 * non-nested critical section with the scheduler lock held. 2705 */ 2706 cpuid = PCPU_GET(cpuid); 2707 tdq = TDQ_CPU(cpuid); 2708 ts = td->td_sched; 2709 if (TD_IS_IDLETHREAD(td)) 2710 td->td_lock = TDQ_LOCKPTR(tdq); 2711 MPASS(td->td_lock == TDQ_LOCKPTR(tdq)); 2712 td->td_oncpu = cpuid; 2713 TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED); 2714 lock_profile_obtain_lock_success( 2715 &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__); 2716} 2717 2718/* 2719 * Create on first use to catch odd startup conditons. 2720 */ 2721char * 2722sched_tdname(struct thread *td) 2723{ 2724#ifdef KTR 2725 struct td_sched *ts; 2726 2727 ts = td->td_sched; 2728 if (ts->ts_name[0] == '\0') 2729 snprintf(ts->ts_name, sizeof(ts->ts_name), 2730 "%s tid %d", td->td_name, td->td_tid); 2731 return (ts->ts_name); 2732#else 2733 return (td->td_name); 2734#endif 2735} 2736 2737#ifdef KTR 2738void 2739sched_clear_tdname(struct thread *td) 2740{ 2741 struct td_sched *ts; 2742 2743 ts = td->td_sched; 2744 ts->ts_name[0] = '\0'; 2745} 2746#endif 2747 2748#ifdef SMP 2749 2750/* 2751 * Build the CPU topology dump string. Is recursively called to collect 2752 * the topology tree. 2753 */ 2754static int 2755sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, struct cpu_group *cg, 2756 int indent) 2757{ 2758 char cpusetbuf[CPUSETBUFSIZ]; 2759 int i, first; 2760 2761 sbuf_printf(sb, "%*s<group level=\"%d\" cache-level=\"%d\">\n", indent, 2762 "", 1 + indent / 2, cg->cg_level); 2763 sbuf_printf(sb, "%*s <cpu count=\"%d\" mask=\"%s\">", indent, "", 2764 cg->cg_count, cpusetobj_strprint(cpusetbuf, &cg->cg_mask)); 2765 first = TRUE; 2766 for (i = 0; i < MAXCPU; i++) { 2767 if (CPU_ISSET(i, &cg->cg_mask)) { 2768 if (!first) 2769 sbuf_printf(sb, ", "); 2770 else 2771 first = FALSE; 2772 sbuf_printf(sb, "%d", i); 2773 } 2774 } 2775 sbuf_printf(sb, "</cpu>\n"); 2776 2777 if (cg->cg_flags != 0) { 2778 sbuf_printf(sb, "%*s <flags>", indent, ""); 2779 if ((cg->cg_flags & CG_FLAG_HTT) != 0) 2780 sbuf_printf(sb, "<flag name=\"HTT\">HTT group</flag>"); 2781 if ((cg->cg_flags & CG_FLAG_THREAD) != 0) 2782 sbuf_printf(sb, "<flag name=\"THREAD\">THREAD group</flag>"); 2783 if ((cg->cg_flags & CG_FLAG_SMT) != 0) 2784 sbuf_printf(sb, "<flag name=\"SMT\">SMT group</flag>"); 2785 sbuf_printf(sb, "</flags>\n"); 2786 } 2787 2788 if (cg->cg_children > 0) { 2789 sbuf_printf(sb, "%*s <children>\n", indent, ""); 2790 for (i = 0; i < cg->cg_children; i++) 2791 sysctl_kern_sched_topology_spec_internal(sb, 2792 &cg->cg_child[i], indent+2); 2793 sbuf_printf(sb, "%*s </children>\n", indent, ""); 2794 } 2795 sbuf_printf(sb, "%*s</group>\n", indent, ""); 2796 return (0); 2797} 2798 2799/* 2800 * Sysctl handler for retrieving topology dump. It's a wrapper for 2801 * the recursive sysctl_kern_smp_topology_spec_internal(). 2802 */ 2803static int 2804sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS) 2805{ 2806 struct sbuf *topo; 2807 int err; 2808 2809 KASSERT(cpu_top != NULL, ("cpu_top isn't initialized")); 2810 2811 topo = sbuf_new(NULL, NULL, 500, SBUF_AUTOEXTEND); 2812 if (topo == NULL) 2813 return (ENOMEM); 2814 2815 sbuf_printf(topo, "<groups>\n"); 2816 err = sysctl_kern_sched_topology_spec_internal(topo, cpu_top, 1); 2817 sbuf_printf(topo, "</groups>\n"); 2818 2819 if (err == 0) { 2820 sbuf_finish(topo); 2821 err = SYSCTL_OUT(req, sbuf_data(topo), sbuf_len(topo)); 2822 } 2823 sbuf_delete(topo); 2824 return (err); 2825} 2826 2827#endif 2828 2829static int 2830sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 2831{ 2832 int error, new_val, period; 2833 2834 period = 1000000 / realstathz; 2835 new_val = period * sched_slice; 2836 error = sysctl_handle_int(oidp, &new_val, 0, req); 2837 if (error != 0 || req->newptr == NULL) 2838 return (error); 2839 if (new_val <= 0) 2840 return (EINVAL); 2841 sched_slice = imax(1, (new_val + period / 2) / period); 2842 sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR; 2843 hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) / 2844 realstathz); 2845 return (0); 2846} 2847 2848SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0, "Scheduler"); 2849SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0, 2850 "Scheduler name"); 2851SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW, 2852 NULL, 0, sysctl_kern_quantum, "I", 2853 "Quantum for timeshare threads in microseconds"); 2854SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, 2855 "Quantum for timeshare threads in stathz ticks"); 2856SYSCTL_INT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0, 2857 "Interactivity score threshold"); 2858SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW, 2859 &preempt_thresh, 0, 2860 "Maximal (lowest) priority for preemption"); 2861SYSCTL_INT(_kern_sched, OID_AUTO, static_boost, CTLFLAG_RW, &static_boost, 0, 2862 "Assign static kernel priorities to sleeping threads"); 2863SYSCTL_INT(_kern_sched, OID_AUTO, idlespins, CTLFLAG_RW, &sched_idlespins, 0, 2864 "Number of times idle thread will spin waiting for new work"); 2865SYSCTL_INT(_kern_sched, OID_AUTO, idlespinthresh, CTLFLAG_RW, 2866 &sched_idlespinthresh, 0, 2867 "Threshold before we will permit idle thread spinning"); 2868#ifdef SMP 2869SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0, 2870 "Number of hz ticks to keep thread affinity for"); 2871SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0, 2872 "Enables the long-term load balancer"); 2873SYSCTL_INT(_kern_sched, OID_AUTO, balance_interval, CTLFLAG_RW, 2874 &balance_interval, 0, 2875 "Average period in stathz ticks to run the long-term balancer"); 2876SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0, 2877 "Attempts to steal work from other cores before idling"); 2878SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0, 2879 "Minimum load on remote CPU before we'll steal"); 2880SYSCTL_PROC(_kern_sched, OID_AUTO, topology_spec, CTLTYPE_STRING | 2881 CTLFLAG_RD, NULL, 0, sysctl_kern_sched_topology_spec, "A", 2882 "XML dump of detected CPU topology"); 2883#endif 2884 2885/* ps compat. All cpu percentages from ULE are weighted. */ 2886static int ccpu = 0; 2887SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 2888