1 /* $OpenBSD: sched_bsd.c,v 1.70 2021/10/30 23:24:48 deraadt Exp $ */ 2 /* $NetBSD: kern_synch.c,v 1.37 1996/04/22 01:38:37 christos Exp $ */ 3 4 /*- 5 * Copyright (c) 1982, 1986, 1990, 1991, 1993 6 * The Regents of the University of California. All rights reserved. 7 * (c) UNIX System Laboratories, Inc. 8 * All or some portions of this file are derived from material licensed 9 * to the University of California by American Telephone and Telegraph 10 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 11 * the permission of UNIX System Laboratories, Inc. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 3. Neither the name of the University nor the names of its contributors 22 * may be used to endorse or promote products derived from this software 23 * without specific prior written permission. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 * 37 * @(#)kern_synch.c 8.6 (Berkeley) 1/21/94 38 */ 39 40 #include <sys/param.h> 41 #include <sys/systm.h> 42 #include <sys/proc.h> 43 #include <sys/kernel.h> 44 #include <sys/malloc.h> 45 #include <sys/signalvar.h> 46 #include <sys/resourcevar.h> 47 #include <uvm/uvm_extern.h> 48 #include <sys/sched.h> 49 #include <sys/timeout.h> 50 #include <sys/smr.h> 51 #include <sys/tracepoint.h> 52 53 #ifdef KTRACE 54 #include <sys/ktrace.h> 55 #endif 56 57 58 int lbolt; /* once a second sleep address */ 59 int rrticks_init; /* # of hardclock ticks per roundrobin() */ 60 61 #ifdef MULTIPROCESSOR 62 struct __mp_lock sched_lock; 63 #endif 64 65 void schedcpu(void *); 66 uint32_t decay_aftersleep(uint32_t, uint32_t); 67 68 /* 69 * Force switch among equal priority processes every 100ms. 70 */ 71 void 72 roundrobin(struct cpu_info *ci) 73 { 74 struct schedstate_percpu *spc = &ci->ci_schedstate; 75 76 spc->spc_rrticks = rrticks_init; 77 78 if (ci->ci_curproc != NULL) { 79 if (spc->spc_schedflags & SPCF_SEENRR) { 80 /* 81 * The process has already been through a roundrobin 82 * without switching and may be hogging the CPU. 83 * Indicate that the process should yield. 84 */ 85 atomic_setbits_int(&spc->spc_schedflags, 86 SPCF_SHOULDYIELD); 87 } else { 88 atomic_setbits_int(&spc->spc_schedflags, 89 SPCF_SEENRR); 90 } 91 } 92 93 if (spc->spc_nrun) 94 need_resched(ci); 95 } 96 97 /* 98 * Constants for digital decay and forget: 99 * 90% of (p_estcpu) usage in 5 * loadav time 100 * 95% of (p_pctcpu) usage in 60 seconds (load insensitive) 101 * Note that, as ps(1) mentions, this can let percentages 102 * total over 100% (I've seen 137.9% for 3 processes). 103 * 104 * Note that hardclock updates p_estcpu and p_cpticks independently. 105 * 106 * We wish to decay away 90% of p_estcpu in (5 * loadavg) seconds. 107 * That is, the system wants to compute a value of decay such 108 * that the following for loop: 109 * for (i = 0; i < (5 * loadavg); i++) 110 * p_estcpu *= decay; 111 * will compute 112 * p_estcpu *= 0.1; 113 * for all values of loadavg: 114 * 115 * Mathematically this loop can be expressed by saying: 116 * decay ** (5 * loadavg) ~= .1 117 * 118 * The system computes decay as: 119 * decay = (2 * loadavg) / (2 * loadavg + 1) 120 * 121 * We wish to prove that the system's computation of decay 122 * will always fulfill the equation: 123 * decay ** (5 * loadavg) ~= .1 124 * 125 * If we compute b as: 126 * b = 2 * loadavg 127 * then 128 * decay = b / (b + 1) 129 * 130 * We now need to prove two things: 131 * 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1) 132 * 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg) 133 * 134 * Facts: 135 * For x close to zero, exp(x) =~ 1 + x, since 136 * exp(x) = 0! + x**1/1! + x**2/2! + ... . 137 * therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b. 138 * For x close to zero, ln(1+x) =~ x, since 139 * ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1 140 * therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1). 141 * ln(.1) =~ -2.30 142 * 143 * Proof of (1): 144 * Solve (factor)**(power) =~ .1 given power (5*loadav): 145 * solving for factor, 146 * ln(factor) =~ (-2.30/5*loadav), or 147 * factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) = 148 * exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED 149 * 150 * Proof of (2): 151 * Solve (factor)**(power) =~ .1 given factor == (b/(b+1)): 152 * solving for power, 153 * power*ln(b/(b+1)) =~ -2.30, or 154 * power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED 155 * 156 * Actual power values for the implemented algorithm are as follows: 157 * loadav: 1 2 3 4 158 * power: 5.68 10.32 14.94 19.55 159 */ 160 161 /* calculations for digital decay to forget 90% of usage in 5*loadav sec */ 162 #define loadfactor(loadav) (2 * (loadav)) 163 #define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE)) 164 165 /* decay 95% of `p_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */ 166 fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */ 167 168 /* 169 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the 170 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below 171 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT). 172 * 173 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used: 174 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits). 175 * 176 * If you don't want to bother with the faster/more-accurate formula, you 177 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate 178 * (more general) method of calculating the %age of CPU used by a process. 179 */ 180 #define CCPU_SHIFT 11 181 182 /* 183 * Recompute process priorities, every second. 184 */ 185 void 186 schedcpu(void *arg) 187 { 188 struct timeout *to = (struct timeout *)arg; 189 fixpt_t loadfac = loadfactor(averunnable.ldavg[0]); 190 struct proc *p; 191 int s; 192 unsigned int newcpu; 193 int phz; 194 195 /* 196 * If we have a statistics clock, use that to calculate CPU 197 * time, otherwise revert to using the profiling clock (which, 198 * in turn, defaults to hz if there is no separate profiling 199 * clock available) 200 */ 201 phz = stathz ? stathz : profhz; 202 KASSERT(phz); 203 204 LIST_FOREACH(p, &allproc, p_list) { 205 /* 206 * Idle threads are never placed on the runqueue, 207 * therefore computing their priority is pointless. 208 */ 209 if (p->p_cpu != NULL && 210 p->p_cpu->ci_schedstate.spc_idleproc == p) 211 continue; 212 /* 213 * Increment sleep time (if sleeping). We ignore overflow. 214 */ 215 if (p->p_stat == SSLEEP || p->p_stat == SSTOP) 216 p->p_slptime++; 217 p->p_pctcpu = (p->p_pctcpu * ccpu) >> FSHIFT; 218 /* 219 * If the process has slept the entire second, 220 * stop recalculating its priority until it wakes up. 221 */ 222 if (p->p_slptime > 1) 223 continue; 224 SCHED_LOCK(s); 225 /* 226 * p_pctcpu is only for diagnostic tools such as ps. 227 */ 228 #if (FSHIFT >= CCPU_SHIFT) 229 p->p_pctcpu += (phz == 100)? 230 ((fixpt_t) p->p_cpticks) << (FSHIFT - CCPU_SHIFT): 231 100 * (((fixpt_t) p->p_cpticks) 232 << (FSHIFT - CCPU_SHIFT)) / phz; 233 #else 234 p->p_pctcpu += ((FSCALE - ccpu) * 235 (p->p_cpticks * FSCALE / phz)) >> FSHIFT; 236 #endif 237 p->p_cpticks = 0; 238 newcpu = (u_int) decay_cpu(loadfac, p->p_estcpu); 239 setpriority(p, newcpu, p->p_p->ps_nice); 240 241 if (p->p_stat == SRUN && 242 (p->p_runpri / SCHED_PPQ) != (p->p_usrpri / SCHED_PPQ)) { 243 remrunqueue(p); 244 setrunqueue(p->p_cpu, p, p->p_usrpri); 245 } 246 SCHED_UNLOCK(s); 247 } 248 uvm_meter(); 249 wakeup(&lbolt); 250 timeout_add_sec(to, 1); 251 } 252 253 /* 254 * Recalculate the priority of a process after it has slept for a while. 255 * For all load averages >= 1 and max p_estcpu of 255, sleeping for at 256 * least six times the loadfactor will decay p_estcpu to zero. 257 */ 258 uint32_t 259 decay_aftersleep(uint32_t estcpu, uint32_t slptime) 260 { 261 fixpt_t loadfac = loadfactor(averunnable.ldavg[0]); 262 uint32_t newcpu; 263 264 if (slptime > 5 * loadfac) 265 newcpu = 0; 266 else { 267 newcpu = estcpu; 268 slptime--; /* the first time was done in schedcpu */ 269 while (newcpu && --slptime) 270 newcpu = decay_cpu(loadfac, newcpu); 271 272 } 273 274 return (newcpu); 275 } 276 277 /* 278 * General yield call. Puts the current process back on its run queue and 279 * performs a voluntary context switch. 280 */ 281 void 282 yield(void) 283 { 284 struct proc *p = curproc; 285 int s; 286 287 SCHED_LOCK(s); 288 setrunqueue(p->p_cpu, p, p->p_usrpri); 289 p->p_ru.ru_nvcsw++; 290 mi_switch(); 291 SCHED_UNLOCK(s); 292 } 293 294 /* 295 * General preemption call. Puts the current process back on its run queue 296 * and performs an involuntary context switch. If a process is supplied, 297 * we switch to that process. Otherwise, we use the normal process selection 298 * criteria. 299 */ 300 void 301 preempt(void) 302 { 303 struct proc *p = curproc; 304 int s; 305 306 SCHED_LOCK(s); 307 setrunqueue(p->p_cpu, p, p->p_usrpri); 308 p->p_ru.ru_nivcsw++; 309 mi_switch(); 310 SCHED_UNLOCK(s); 311 } 312 313 void 314 mi_switch(void) 315 { 316 struct schedstate_percpu *spc = &curcpu()->ci_schedstate; 317 struct proc *p = curproc; 318 struct proc *nextproc; 319 struct process *pr = p->p_p; 320 struct timespec ts; 321 #ifdef MULTIPROCESSOR 322 int hold_count; 323 int sched_count; 324 #endif 325 326 assertwaitok(); 327 KASSERT(p->p_stat != SONPROC); 328 329 SCHED_ASSERT_LOCKED(); 330 331 #ifdef MULTIPROCESSOR 332 /* 333 * Release the kernel_lock, as we are about to yield the CPU. 334 */ 335 sched_count = __mp_release_all_but_one(&sched_lock); 336 if (_kernel_lock_held()) 337 hold_count = __mp_release_all(&kernel_lock); 338 else 339 hold_count = 0; 340 #endif 341 342 /* 343 * Compute the amount of time during which the current 344 * process was running, and add that to its total so far. 345 */ 346 nanouptime(&ts); 347 if (timespeccmp(&ts, &spc->spc_runtime, <)) { 348 #if 0 349 printf("uptime is not monotonic! " 350 "ts=%lld.%09lu, runtime=%lld.%09lu\n", 351 (long long)tv.tv_sec, tv.tv_nsec, 352 (long long)spc->spc_runtime.tv_sec, 353 spc->spc_runtime.tv_nsec); 354 #endif 355 } else { 356 timespecsub(&ts, &spc->spc_runtime, &ts); 357 timespecadd(&p->p_rtime, &ts, &p->p_rtime); 358 } 359 360 /* add the time counts for this thread to the process's total */ 361 tuagg_unlocked(pr, p); 362 363 /* 364 * Process is about to yield the CPU; clear the appropriate 365 * scheduling flags. 366 */ 367 atomic_clearbits_int(&spc->spc_schedflags, SPCF_SWITCHCLEAR); 368 369 nextproc = sched_chooseproc(); 370 371 if (p != nextproc) { 372 uvmexp.swtch++; 373 TRACEPOINT(sched, off__cpu, nextproc->p_tid + THREAD_PID_OFFSET, 374 nextproc->p_p->ps_pid); 375 cpu_switchto(p, nextproc); 376 TRACEPOINT(sched, on__cpu, NULL); 377 } else { 378 TRACEPOINT(sched, remain__cpu, NULL); 379 p->p_stat = SONPROC; 380 } 381 382 clear_resched(curcpu()); 383 384 SCHED_ASSERT_LOCKED(); 385 386 /* 387 * To preserve lock ordering, we need to release the sched lock 388 * and grab it after we grab the big lock. 389 * In the future, when the sched lock isn't recursive, we'll 390 * just release it here. 391 */ 392 #ifdef MULTIPROCESSOR 393 __mp_unlock(&sched_lock); 394 #endif 395 396 SCHED_ASSERT_UNLOCKED(); 397 398 smr_idle(); 399 400 /* 401 * We're running again; record our new start time. We might 402 * be running on a new CPU now, so don't use the cache'd 403 * schedstate_percpu pointer. 404 */ 405 KASSERT(p->p_cpu == curcpu()); 406 407 nanouptime(&p->p_cpu->ci_schedstate.spc_runtime); 408 409 #ifdef MULTIPROCESSOR 410 /* 411 * Reacquire the kernel_lock now. We do this after we've 412 * released the scheduler lock to avoid deadlock, and before 413 * we reacquire the interlock and the scheduler lock. 414 */ 415 if (hold_count) 416 __mp_acquire_count(&kernel_lock, hold_count); 417 __mp_acquire_count(&sched_lock, sched_count + 1); 418 #endif 419 } 420 421 /* 422 * Change process state to be runnable, 423 * placing it on the run queue. 424 */ 425 void 426 setrunnable(struct proc *p) 427 { 428 struct process *pr = p->p_p; 429 u_char prio; 430 431 SCHED_ASSERT_LOCKED(); 432 433 switch (p->p_stat) { 434 case 0: 435 case SRUN: 436 case SONPROC: 437 case SDEAD: 438 case SIDL: 439 default: 440 panic("setrunnable"); 441 case SSTOP: 442 /* 443 * If we're being traced (possibly because someone attached us 444 * while we were stopped), check for a signal from the debugger. 445 */ 446 if ((pr->ps_flags & PS_TRACED) != 0 && pr->ps_xsig != 0) 447 atomic_setbits_int(&p->p_siglist, sigmask(pr->ps_xsig)); 448 prio = p->p_usrpri; 449 unsleep(p); 450 break; 451 case SSLEEP: 452 prio = p->p_slppri; 453 unsleep(p); /* e.g. when sending signals */ 454 break; 455 } 456 setrunqueue(NULL, p, prio); 457 if (p->p_slptime > 1) { 458 uint32_t newcpu; 459 460 newcpu = decay_aftersleep(p->p_estcpu, p->p_slptime); 461 setpriority(p, newcpu, pr->ps_nice); 462 } 463 p->p_slptime = 0; 464 } 465 466 /* 467 * Compute the priority of a process. 468 */ 469 void 470 setpriority(struct proc *p, uint32_t newcpu, uint8_t nice) 471 { 472 unsigned int newprio; 473 474 newprio = min((PUSER + newcpu + NICE_WEIGHT * (nice - NZERO)), MAXPRI); 475 476 SCHED_ASSERT_LOCKED(); 477 p->p_estcpu = newcpu; 478 p->p_usrpri = newprio; 479 } 480 481 /* 482 * We adjust the priority of the current process. The priority of a process 483 * gets worse as it accumulates CPU time. The cpu usage estimator (p_estcpu) 484 * is increased here. The formula for computing priorities (in kern_synch.c) 485 * will compute a different value each time p_estcpu increases. This can 486 * cause a switch, but unless the priority crosses a PPQ boundary the actual 487 * queue will not change. The cpu usage estimator ramps up quite quickly 488 * when the process is running (linearly), and decays away exponentially, at 489 * a rate which is proportionally slower when the system is busy. The basic 490 * principle is that the system will 90% forget that the process used a lot 491 * of CPU time in 5 * loadav seconds. This causes the system to favor 492 * processes which haven't run much recently, and to round-robin among other 493 * processes. 494 */ 495 void 496 schedclock(struct proc *p) 497 { 498 struct cpu_info *ci = curcpu(); 499 struct schedstate_percpu *spc = &ci->ci_schedstate; 500 uint32_t newcpu; 501 int s; 502 503 if (p == spc->spc_idleproc || spc->spc_spinning) 504 return; 505 506 SCHED_LOCK(s); 507 newcpu = ESTCPULIM(p->p_estcpu + 1); 508 setpriority(p, newcpu, p->p_p->ps_nice); 509 SCHED_UNLOCK(s); 510 } 511 512 void (*cpu_setperf)(int); 513 514 #define PERFPOL_MANUAL 0 515 #define PERFPOL_AUTO 1 516 #define PERFPOL_HIGH 2 517 int perflevel = 100; 518 int perfpolicy = PERFPOL_AUTO; 519 520 #ifndef SMALL_KERNEL 521 /* 522 * The code below handles CPU throttling. 523 */ 524 #include <sys/sysctl.h> 525 526 void setperf_auto(void *); 527 struct timeout setperf_to = TIMEOUT_INITIALIZER(setperf_auto, NULL); 528 extern int hw_power; 529 530 void 531 setperf_auto(void *v) 532 { 533 static uint64_t *idleticks, *totalticks; 534 static int downbeats; 535 int i, j = 0; 536 int speedup = 0; 537 CPU_INFO_ITERATOR cii; 538 struct cpu_info *ci; 539 uint64_t idle, total, allidle = 0, alltotal = 0; 540 541 if (perfpolicy != PERFPOL_AUTO) 542 return; 543 544 if (cpu_setperf == NULL) 545 return; 546 547 if (hw_power) { 548 speedup = 1; 549 goto faster; 550 } 551 552 if (!idleticks) 553 if (!(idleticks = mallocarray(ncpusfound, sizeof(*idleticks), 554 M_DEVBUF, M_NOWAIT | M_ZERO))) 555 return; 556 if (!totalticks) 557 if (!(totalticks = mallocarray(ncpusfound, sizeof(*totalticks), 558 M_DEVBUF, M_NOWAIT | M_ZERO))) { 559 free(idleticks, M_DEVBUF, 560 sizeof(*idleticks) * ncpusfound); 561 return; 562 } 563 CPU_INFO_FOREACH(cii, ci) { 564 if (!cpu_is_online(ci)) 565 continue; 566 total = 0; 567 for (i = 0; i < CPUSTATES; i++) { 568 total += ci->ci_schedstate.spc_cp_time[i]; 569 } 570 total -= totalticks[j]; 571 idle = ci->ci_schedstate.spc_cp_time[CP_IDLE] - idleticks[j]; 572 if (idle < total / 3) 573 speedup = 1; 574 alltotal += total; 575 allidle += idle; 576 idleticks[j] += idle; 577 totalticks[j] += total; 578 j++; 579 } 580 if (allidle < alltotal / 2) 581 speedup = 1; 582 if (speedup) 583 downbeats = 5; 584 585 if (speedup && perflevel != 100) { 586 faster: 587 perflevel = 100; 588 cpu_setperf(perflevel); 589 } else if (!speedup && perflevel != 0 && --downbeats <= 0) { 590 perflevel = 0; 591 cpu_setperf(perflevel); 592 } 593 594 timeout_add_msec(&setperf_to, 100); 595 } 596 597 int 598 sysctl_hwsetperf(void *oldp, size_t *oldlenp, void *newp, size_t newlen) 599 { 600 int err; 601 602 if (!cpu_setperf) 603 return EOPNOTSUPP; 604 605 if (perfpolicy != PERFPOL_MANUAL) 606 return sysctl_rdint(oldp, oldlenp, newp, perflevel); 607 608 err = sysctl_int_bounded(oldp, oldlenp, newp, newlen, 609 &perflevel, 0, 100); 610 if (err) 611 return err; 612 613 if (newp != NULL) 614 cpu_setperf(perflevel); 615 616 return 0; 617 } 618 619 int 620 sysctl_hwperfpolicy(void *oldp, size_t *oldlenp, void *newp, size_t newlen) 621 { 622 char policy[32]; 623 int err; 624 625 if (!cpu_setperf) 626 return EOPNOTSUPP; 627 628 switch (perfpolicy) { 629 case PERFPOL_MANUAL: 630 strlcpy(policy, "manual", sizeof(policy)); 631 break; 632 case PERFPOL_AUTO: 633 strlcpy(policy, "auto", sizeof(policy)); 634 break; 635 case PERFPOL_HIGH: 636 strlcpy(policy, "high", sizeof(policy)); 637 break; 638 default: 639 strlcpy(policy, "unknown", sizeof(policy)); 640 break; 641 } 642 643 if (newp == NULL) 644 return sysctl_rdstring(oldp, oldlenp, newp, policy); 645 646 err = sysctl_string(oldp, oldlenp, newp, newlen, policy, sizeof(policy)); 647 if (err) 648 return err; 649 if (strcmp(policy, "manual") == 0) 650 perfpolicy = PERFPOL_MANUAL; 651 else if (strcmp(policy, "auto") == 0) 652 perfpolicy = PERFPOL_AUTO; 653 else if (strcmp(policy, "high") == 0) 654 perfpolicy = PERFPOL_HIGH; 655 else 656 return EINVAL; 657 658 if (perfpolicy == PERFPOL_AUTO) { 659 timeout_add_msec(&setperf_to, 200); 660 } else if (perfpolicy == PERFPOL_HIGH) { 661 perflevel = 100; 662 cpu_setperf(perflevel); 663 } 664 return 0; 665 } 666 #endif 667 668 void 669 scheduler_start(void) 670 { 671 static struct timeout schedcpu_to; 672 673 /* 674 * We avoid polluting the global namespace by keeping the scheduler 675 * timeouts static in this function. 676 * We setup the timeout here and kick schedcpu once to make it do 677 * its job. 678 */ 679 timeout_set(&schedcpu_to, schedcpu, &schedcpu_to); 680 681 rrticks_init = hz / 10; 682 schedcpu(&schedcpu_to); 683 684 #ifndef SMALL_KERNEL 685 if (perfpolicy == PERFPOL_AUTO) 686 timeout_add_msec(&setperf_to, 200); 687 #endif 688 } 689 690