1 /*- 2 * Copyright (c) 1982, 1986, 1990, 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * (c) UNIX System Laboratories, Inc. 5 * All or some portions of this file are derived from material licensed 6 * to the University of California by American Telephone and Telegraph 7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 8 * the permission of UNIX System Laboratories, Inc. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 * 38 * @(#)kern_synch.c 8.9 (Berkeley) 5/19/95 39 * $FreeBSD: src/sys/kern/kern_synch.c,v 1.87.2.6 2002/10/13 07:29:53 kbyanc Exp $ 40 * $DragonFly: src/sys/kern/kern_synch.c,v 1.42 2005/06/06 15:02:28 dillon Exp $ 41 */ 42 43 #include "opt_ktrace.h" 44 45 #include <sys/param.h> 46 #include <sys/systm.h> 47 #include <sys/proc.h> 48 #include <sys/kernel.h> 49 #include <sys/signalvar.h> 50 #include <sys/resourcevar.h> 51 #include <sys/vmmeter.h> 52 #include <sys/sysctl.h> 53 #include <sys/thread2.h> 54 #ifdef KTRACE 55 #include <sys/uio.h> 56 #include <sys/ktrace.h> 57 #endif 58 #include <sys/xwait.h> 59 60 #include <machine/cpu.h> 61 #include <machine/ipl.h> 62 #include <machine/smp.h> 63 64 static void sched_setup (void *dummy); 65 SYSINIT(sched_setup, SI_SUB_KICK_SCHEDULER, SI_ORDER_FIRST, sched_setup, NULL) 66 67 int hogticks; 68 int lbolt; 69 int sched_quantum; /* Roundrobin scheduling quantum in ticks. */ 70 int ncpus; 71 int ncpus2, ncpus2_shift, ncpus2_mask; 72 int safepri; 73 74 static struct callout loadav_callout; 75 static struct callout roundrobin_callout; 76 static struct callout schedcpu_callout; 77 78 struct loadavg averunnable = 79 { {0, 0, 0}, FSCALE }; /* load average, of runnable procs */ 80 /* 81 * Constants for averages over 1, 5, and 15 minutes 82 * when sampling at 5 second intervals. 83 */ 84 static fixpt_t cexp[3] = { 85 0.9200444146293232 * FSCALE, /* exp(-1/12) */ 86 0.9834714538216174 * FSCALE, /* exp(-1/60) */ 87 0.9944598480048967 * FSCALE, /* exp(-1/180) */ 88 }; 89 90 static void endtsleep (void *); 91 static void loadav (void *arg); 92 static void roundrobin (void *arg); 93 static void schedcpu (void *arg); 94 static void updatepri (struct proc *p); 95 96 static int 97 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS) 98 { 99 int error, new_val; 100 101 new_val = sched_quantum * tick; 102 error = sysctl_handle_int(oidp, &new_val, 0, req); 103 if (error != 0 || req->newptr == NULL) 104 return (error); 105 if (new_val < tick) 106 return (EINVAL); 107 sched_quantum = new_val / tick; 108 hogticks = 2 * sched_quantum; 109 return (0); 110 } 111 112 SYSCTL_PROC(_kern, OID_AUTO, quantum, CTLTYPE_INT|CTLFLAG_RW, 113 0, sizeof sched_quantum, sysctl_kern_quantum, "I", ""); 114 115 int 116 roundrobin_interval(void) 117 { 118 return (sched_quantum); 119 } 120 121 /* 122 * Force switch among equal priority processes every 100ms. 123 * 124 * WARNING! The MP lock is not held on ipi message remotes. 125 */ 126 #ifdef SMP 127 128 static void 129 roundrobin_remote(void *arg) 130 { 131 struct proc *p = lwkt_preempted_proc(); 132 if (p == NULL || RTP_PRIO_NEED_RR(p->p_rtprio.type)) 133 need_user_resched(); 134 } 135 136 #endif 137 138 static void 139 roundrobin(void *arg) 140 { 141 struct proc *p = lwkt_preempted_proc(); 142 if (p == NULL || RTP_PRIO_NEED_RR(p->p_rtprio.type)) 143 need_user_resched(); 144 #ifdef SMP 145 lwkt_send_ipiq_mask(mycpu->gd_other_cpus, roundrobin_remote, NULL); 146 #endif 147 callout_reset(&roundrobin_callout, sched_quantum, roundrobin, NULL); 148 } 149 150 #ifdef SMP 151 152 void 153 resched_cpus(u_int32_t mask) 154 { 155 lwkt_send_ipiq_mask(mask, roundrobin_remote, NULL); 156 } 157 158 #endif 159 160 /* 161 * The load average is scaled by FSCALE (2048 typ). The estimated cpu is 162 * incremented at a rate of ESTCPUVFREQ per second (40hz typ), but this is 163 * divided up across all cpu bound processes running in the system so an 164 * individual process will get less under load. ESTCPULIM typicaly caps 165 * out at ESTCPUMAX (around 376, or 11 nice levels). 166 * 167 * Generally speaking the decay equation needs to break-even on growth 168 * at the limit at all load levels >= 1.0, so if the estimated cpu for 169 * a process increases by (ESTVCPUFREQ / load) per second, then the decay 170 * should reach this value when estcpu reaches ESTCPUMAX. That calculation 171 * is: 172 * 173 * ESTCPUMAX * decay = ESTCPUVFREQ / load 174 * decay = ESTCPUVFREQ / (load * ESTCPUMAX) 175 * decay = estcpu * 0.053 / load 176 * 177 * If the load is less then 1.0 we assume a load of 1.0. 178 */ 179 180 #define cload(loadav) ((loadav) < FSCALE ? FSCALE : (loadav)) 181 #define decay_cpu(loadav,estcpu) \ 182 ((estcpu) * (FSCALE * ESTCPUVFREQ / ESTCPUMAX) / cload(loadav)) 183 184 /* decay 95% of `p_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */ 185 static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */ 186 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, ""); 187 188 /* kernel uses `FSCALE', userland (SHOULD) use kern.fscale */ 189 static int fscale __unused = FSCALE; 190 SYSCTL_INT(_kern, OID_AUTO, fscale, CTLFLAG_RD, 0, FSCALE, ""); 191 192 /* 193 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the 194 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below 195 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT). 196 * 197 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used: 198 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits). 199 * 200 * If you don't want to bother with the faster/more-accurate formula, you 201 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate 202 * (more general) method of calculating the %age of CPU used by a process. 203 */ 204 #define CCPU_SHIFT 11 205 206 /* 207 * Recompute process priorities, once a second. 208 */ 209 /* ARGSUSED */ 210 static void 211 schedcpu(void *arg) 212 { 213 fixpt_t loadfac = averunnable.ldavg[0]; 214 struct proc *p; 215 unsigned int ndecay; 216 217 FOREACH_PROC_IN_SYSTEM(p) { 218 /* 219 * Increment time in/out of memory and sleep time 220 * (if sleeping). We ignore overflow; with 16-bit int's 221 * (remember them?) overflow takes 45 days. 222 */ 223 p->p_swtime++; 224 if (p->p_stat == SSLEEP || p->p_stat == SSTOP) 225 p->p_slptime++; 226 p->p_pctcpu = (p->p_pctcpu * ccpu) >> FSHIFT; 227 228 /* 229 * If the process has slept the entire second, 230 * stop recalculating its priority until it wakes up. 231 * 232 * Note that interactive calculations do not occur for 233 * long sleeps (because that isn't necessarily indicative 234 * of an interactive process). 235 */ 236 if (p->p_slptime > 1) 237 continue; 238 /* prevent state changes and protect run queue */ 239 crit_enter(); 240 /* 241 * p_cpticks runs at ESTCPUFREQ but must be divided by the 242 * load average for par-100% use. Higher p_interactive 243 * values mean less interactive, lower values mean more 244 * interactive. 245 */ 246 if ((((fixpt_t)p->p_cpticks * cload(loadfac)) >> FSHIFT) > 247 ESTCPUFREQ / 4) { 248 if (p->p_interactive < 127) 249 ++p->p_interactive; 250 } else { 251 if (p->p_interactive > -127) 252 --p->p_interactive; 253 } 254 /* 255 * p_pctcpu is only for ps. 256 */ 257 #if (FSHIFT >= CCPU_SHIFT) 258 p->p_pctcpu += (ESTCPUFREQ == 100)? 259 ((fixpt_t) p->p_cpticks) << (FSHIFT - CCPU_SHIFT): 260 100 * (((fixpt_t) p->p_cpticks) 261 << (FSHIFT - CCPU_SHIFT)) / ESTCPUFREQ; 262 #else 263 p->p_pctcpu += ((FSCALE - ccpu) * 264 (p->p_cpticks * FSCALE / ESTCPUFREQ)) >> FSHIFT; 265 #endif 266 p->p_cpticks = 0; 267 ndecay = decay_cpu(loadfac, p->p_estcpu); 268 if (p->p_estcpu > ndecay) 269 p->p_estcpu -= ndecay; 270 else 271 p->p_estcpu = 0; 272 resetpriority(p); 273 crit_exit(); 274 } 275 wakeup((caddr_t)&lbolt); 276 callout_reset(&schedcpu_callout, hz, schedcpu, NULL); 277 } 278 279 /* 280 * Recalculate the priority of a process after it has slept for a while. 281 * For all load averages >= 1 and max p_estcpu of 255, sleeping for at 282 * least six times the loadfactor will decay p_estcpu to zero. 283 */ 284 static void 285 updatepri(struct proc *p) 286 { 287 unsigned int ndecay; 288 289 ndecay = decay_cpu(averunnable.ldavg[0], p->p_estcpu) * p->p_slptime; 290 if (p->p_estcpu > ndecay) 291 p->p_estcpu -= ndecay; 292 else 293 p->p_estcpu = 0; 294 resetpriority(p); 295 } 296 297 /* 298 * We're only looking at 7 bits of the address; everything is 299 * aligned to 4, lots of things are aligned to greater powers 300 * of 2. Shift right by 8, i.e. drop the bottom 256 worth. 301 */ 302 #define TABLESIZE 128 303 static TAILQ_HEAD(slpquehead, thread) slpque[TABLESIZE]; 304 #define LOOKUP(x) (((intptr_t)(x) >> 8) & (TABLESIZE - 1)) 305 306 /* 307 * During autoconfiguration or after a panic, a sleep will simply 308 * lower the priority briefly to allow interrupts, then return. 309 */ 310 311 void 312 sleepinit(void) 313 { 314 int i; 315 316 sched_quantum = hz/10; 317 hogticks = 2 * sched_quantum; 318 for (i = 0; i < TABLESIZE; i++) 319 TAILQ_INIT(&slpque[i]); 320 } 321 322 /* 323 * General sleep call. Suspends the current process until a wakeup is 324 * performed on the specified identifier. The process will then be made 325 * runnable with the specified priority. Sleeps at most timo/hz seconds 326 * (0 means no timeout). If flags includes PCATCH flag, signals are checked 327 * before and after sleeping, else signals are not checked. Returns 0 if 328 * awakened, EWOULDBLOCK if the timeout expires. If PCATCH is set and a 329 * signal needs to be delivered, ERESTART is returned if the current system 330 * call should be restarted if possible, and EINTR is returned if the system 331 * call should be interrupted by the signal (return EINTR). 332 * 333 * Note that if we are a process, we release_curproc() before messing with 334 * the LWKT scheduler. 335 */ 336 int 337 tsleep(void *ident, int flags, const char *wmesg, int timo) 338 { 339 struct thread *td = curthread; 340 struct proc *p = td->td_proc; /* may be NULL */ 341 int sig = 0, catch = flags & PCATCH; 342 int id = LOOKUP(ident); 343 int oldpri; 344 struct callout thandle; 345 346 /* 347 * NOTE: removed KTRPOINT, it could cause races due to blocking 348 * even in stable. Just scrap it for now. 349 */ 350 if (cold || panicstr) { 351 /* 352 * After a panic, or during autoconfiguration, 353 * just give interrupts a chance, then just return; 354 * don't run any other procs or panic below, 355 * in case this is the idle process and already asleep. 356 */ 357 splz(); 358 oldpri = td->td_pri & TDPRI_MASK; 359 lwkt_setpri_self(safepri); 360 lwkt_switch(); 361 lwkt_setpri_self(oldpri); 362 return (0); 363 } 364 KKASSERT(td != &mycpu->gd_idlethread); /* you must be kidding! */ 365 crit_enter_quick(td); 366 KASSERT(ident != NULL, ("tsleep: no ident")); 367 KASSERT(p == NULL || p->p_stat == SRUN, ("tsleep %p %s %d", 368 ident, wmesg, p->p_stat)); 369 370 td->td_wchan = ident; 371 td->td_wmesg = wmesg; 372 td->td_wdomain = flags & PDOMAIN_MASK; 373 if (p) { 374 if (flags & PNORESCHED) 375 td->td_flags |= TDF_NORESCHED; 376 release_curproc(p); 377 p->p_slptime = 0; 378 } 379 lwkt_deschedule_self(td); 380 TAILQ_INSERT_TAIL(&slpque[id], td, td_threadq); 381 if (timo) { 382 callout_init(&thandle); 383 callout_reset(&thandle, timo, endtsleep, td); 384 } 385 /* 386 * We put ourselves on the sleep queue and start our timeout 387 * before calling CURSIG, as we could stop there, and a wakeup 388 * or a SIGCONT (or both) could occur while we were stopped. 389 * A SIGCONT would cause us to be marked as SSLEEP 390 * without resuming us, thus we must be ready for sleep 391 * when CURSIG is called. If the wakeup happens while we're 392 * stopped, td->td_wchan will be 0 upon return from CURSIG. 393 */ 394 if (p) { 395 if (catch) { 396 p->p_flag |= P_SINTR; 397 if ((sig = CURSIG(p))) { 398 if (td->td_wchan) { 399 unsleep(td); 400 lwkt_schedule_self(td); 401 } 402 p->p_stat = SRUN; 403 goto resume; 404 } 405 if (td->td_wchan == NULL) { 406 catch = 0; 407 goto resume; 408 } 409 } else { 410 sig = 0; 411 } 412 413 /* 414 * If we are not the current process we have to remove ourself 415 * from the run queue. 416 */ 417 KASSERT(p->p_stat == SRUN, ("PSTAT NOT SRUN %d %d", p->p_pid, p->p_stat)); 418 /* 419 * If this is the current 'user' process schedule another one. 420 */ 421 clrrunnable(p, SSLEEP); 422 p->p_stats->p_ru.ru_nvcsw++; 423 mi_switch(p); 424 KASSERT(p->p_stat == SRUN, ("tsleep: stat not srun")); 425 } else { 426 lwkt_switch(); 427 } 428 resume: 429 if (p) 430 p->p_flag &= ~P_SINTR; 431 crit_exit_quick(td); 432 td->td_flags &= ~TDF_NORESCHED; 433 if (td->td_flags & TDF_TIMEOUT) { 434 td->td_flags &= ~TDF_TIMEOUT; 435 if (sig == 0) 436 return (EWOULDBLOCK); 437 } else if (timo) { 438 callout_stop(&thandle); 439 } else if (td->td_wmesg) { 440 /* 441 * This can happen if a thread is woken up directly. Clear 442 * wmesg to avoid debugging confusion. 443 */ 444 td->td_wmesg = NULL; 445 } 446 /* inline of iscaught() */ 447 if (p) { 448 if (catch && (sig != 0 || (sig = CURSIG(p)))) { 449 if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig)) 450 return (EINTR); 451 return (ERESTART); 452 } 453 } 454 return (0); 455 } 456 457 /* 458 * Implement the timeout for tsleep. We interlock against 459 * wchan when setting TDF_TIMEOUT. For processes we remove 460 * the sleep if the process is stopped rather then sleeping, 461 * so it remains stopped. 462 */ 463 static void 464 endtsleep(void *arg) 465 { 466 thread_t td = arg; 467 struct proc *p; 468 469 crit_enter(); 470 if (td->td_wchan) { 471 td->td_flags |= TDF_TIMEOUT; 472 if ((p = td->td_proc) != NULL) { 473 if (p->p_stat == SSLEEP) 474 setrunnable(p); 475 else 476 unsleep(td); 477 } else { 478 unsleep(td); 479 lwkt_schedule(td); 480 } 481 } 482 crit_exit(); 483 } 484 485 /* 486 * Remove a process from its wait queue 487 */ 488 void 489 unsleep(struct thread *td) 490 { 491 crit_enter(); 492 if (td->td_wchan) { 493 #if 0 494 if (p->p_flag & P_XSLEEP) { 495 struct xwait *w = p->p_wchan; 496 TAILQ_REMOVE(&w->waitq, p, p_procq); 497 p->p_flag &= ~P_XSLEEP; 498 } else 499 #endif 500 TAILQ_REMOVE(&slpque[LOOKUP(td->td_wchan)], td, td_threadq); 501 td->td_wchan = NULL; 502 } 503 crit_exit(); 504 } 505 506 #if 0 507 /* 508 * Make all processes sleeping on the explicit lock structure runnable. 509 */ 510 void 511 xwakeup(struct xwait *w) 512 { 513 struct proc *p; 514 515 crit_enter(); 516 ++w->gen; 517 while ((p = TAILQ_FIRST(&w->waitq)) != NULL) { 518 TAILQ_REMOVE(&w->waitq, p, p_procq); 519 KASSERT(p->p_wchan == w && (p->p_flag & P_XSLEEP), 520 ("xwakeup: wchan mismatch for %p (%p/%p) %08x", p, p->p_wchan, w, p->p_flag & P_XSLEEP)); 521 p->p_wchan = NULL; 522 p->p_flag &= ~P_XSLEEP; 523 if (p->p_stat == SSLEEP) { 524 /* OPTIMIZED EXPANSION OF setrunnable(p); */ 525 if (p->p_slptime > 1) 526 updatepri(p); 527 p->p_slptime = 0; 528 p->p_stat = SRUN; 529 if (p->p_flag & P_INMEM) { 530 lwkt_schedule(td); 531 } else { 532 p->p_flag |= P_SWAPINREQ; 533 wakeup((caddr_t)&proc0); 534 } 535 } 536 } 537 crit_exit(); 538 } 539 #endif 540 541 /* 542 * Make all processes sleeping on the specified identifier runnable. 543 */ 544 static void 545 _wakeup(void *ident, int domain, int count) 546 { 547 struct slpquehead *qp; 548 struct thread *td; 549 struct thread *ntd; 550 struct proc *p; 551 int id = LOOKUP(ident); 552 553 crit_enter(); 554 qp = &slpque[id]; 555 restart: 556 for (td = TAILQ_FIRST(qp); td != NULL; td = ntd) { 557 ntd = TAILQ_NEXT(td, td_threadq); 558 if (td->td_wchan == ident && td->td_wdomain == domain) { 559 TAILQ_REMOVE(qp, td, td_threadq); 560 td->td_wchan = NULL; 561 if ((p = td->td_proc) != NULL && p->p_stat == SSLEEP) { 562 /* OPTIMIZED EXPANSION OF setrunnable(p); */ 563 if (p->p_slptime > 1) 564 updatepri(p); 565 p->p_slptime = 0; 566 p->p_stat = SRUN; 567 if (p->p_flag & P_INMEM) { 568 /* 569 * LWKT scheduled now, there is no 570 * userland runq interaction until 571 * the thread tries to return to user 572 * mode. 573 * 574 * setrunqueue(p); 575 */ 576 lwkt_schedule(td); 577 } else { 578 p->p_flag |= P_SWAPINREQ; 579 wakeup((caddr_t)&proc0); 580 } 581 /* END INLINE EXPANSION */ 582 } else if (p == NULL) { 583 lwkt_schedule(td); 584 } 585 if (--count == 0) 586 break; 587 goto restart; 588 } 589 } 590 crit_exit(); 591 } 592 593 void 594 wakeup(void *ident) 595 { 596 _wakeup(ident, 0, 0); 597 } 598 599 void 600 wakeup_one(void *ident) 601 { 602 _wakeup(ident, 0, 1); 603 } 604 605 void 606 wakeup_domain(void *ident, int domain) 607 { 608 _wakeup(ident, domain, 0); 609 } 610 611 void 612 wakeup_domain_one(void *ident, int domain) 613 { 614 _wakeup(ident, domain, 1); 615 } 616 617 /* 618 * The machine independent parts of mi_switch(). 619 * 620 * 'p' must be the current process. 621 */ 622 void 623 mi_switch(struct proc *p) 624 { 625 thread_t td = p->p_thread; 626 struct rlimit *rlim; 627 u_int64_t ttime; 628 629 KKASSERT(td == mycpu->gd_curthread); 630 631 crit_enter_quick(td); 632 633 /* 634 * Check if the process exceeds its cpu resource allocation. 635 * If over max, kill it. Time spent in interrupts is not 636 * included. YYY 64 bit match is expensive. Ick. 637 */ 638 ttime = td->td_sticks + td->td_uticks; 639 if (p->p_stat != SZOMB && p->p_limit->p_cpulimit != RLIM_INFINITY && 640 ttime > p->p_limit->p_cpulimit) { 641 rlim = &p->p_rlimit[RLIMIT_CPU]; 642 if (ttime / (rlim_t)1000000 >= rlim->rlim_max) { 643 killproc(p, "exceeded maximum CPU limit"); 644 } else { 645 psignal(p, SIGXCPU); 646 if (rlim->rlim_cur < rlim->rlim_max) { 647 /* XXX: we should make a private copy */ 648 rlim->rlim_cur += 5; 649 } 650 } 651 } 652 653 /* 654 * If we are in a SSTOPped state we deschedule ourselves. 655 * YYY this needs to be cleaned up, remember that LWKTs stay on 656 * their run queue which works differently then the user scheduler 657 * which removes the process from the runq when it runs it. 658 */ 659 mycpu->gd_cnt.v_swtch++; 660 if (p->p_stat == SSTOP) 661 lwkt_deschedule_self(td); 662 lwkt_switch(); 663 crit_exit_quick(td); 664 } 665 666 /* 667 * Change process state to be runnable, 668 * placing it on the run queue if it is in memory, 669 * and awakening the swapper if it isn't in memory. 670 */ 671 void 672 setrunnable(struct proc *p) 673 { 674 crit_enter(); 675 676 switch (p->p_stat) { 677 case 0: 678 case SRUN: 679 case SZOMB: 680 default: 681 panic("setrunnable"); 682 case SSTOP: 683 case SSLEEP: 684 unsleep(p->p_thread); /* e.g. when sending signals */ 685 break; 686 687 case SIDL: 688 break; 689 } 690 p->p_stat = SRUN; 691 692 /* 693 * The process is controlled by LWKT at this point, we do not mess 694 * around with the userland scheduler until the thread tries to 695 * return to user mode. 696 */ 697 #if 0 698 if (p->p_flag & P_INMEM) 699 setrunqueue(p); 700 #endif 701 if (p->p_flag & P_INMEM) 702 lwkt_schedule(p->p_thread); 703 crit_exit(); 704 if (p->p_slptime > 1) 705 updatepri(p); 706 p->p_slptime = 0; 707 if ((p->p_flag & P_INMEM) == 0) { 708 p->p_flag |= P_SWAPINREQ; 709 wakeup((caddr_t)&proc0); 710 } 711 } 712 713 /* 714 * Change the process state to NOT be runnable, removing it from the run 715 * queue. 716 */ 717 void 718 clrrunnable(struct proc *p, int stat) 719 { 720 crit_enter_quick(p->p_thread); 721 if (p->p_stat == SRUN && (p->p_flag & P_ONRUNQ)) 722 remrunqueue(p); 723 p->p_stat = stat; 724 crit_exit_quick(p->p_thread); 725 } 726 727 /* 728 * Compute the priority of a process when running in user mode. 729 * Arrange to reschedule if the resulting priority is better 730 * than that of the current process. 731 */ 732 void 733 resetpriority(struct proc *p) 734 { 735 int newpriority; 736 int interactive; 737 int opq; 738 int npq; 739 740 /* 741 * Set p_priority for general process comparisons 742 */ 743 switch(p->p_rtprio.type) { 744 case RTP_PRIO_REALTIME: 745 p->p_priority = PRIBASE_REALTIME + p->p_rtprio.prio; 746 return; 747 case RTP_PRIO_NORMAL: 748 break; 749 case RTP_PRIO_IDLE: 750 p->p_priority = PRIBASE_IDLE + p->p_rtprio.prio; 751 return; 752 case RTP_PRIO_THREAD: 753 p->p_priority = PRIBASE_THREAD + p->p_rtprio.prio; 754 return; 755 } 756 757 /* 758 * NORMAL priorities fall through. These are based on niceness 759 * and cpu use. Lower numbers == higher priorities. 760 */ 761 newpriority = (int)(NICE_ADJUST(p->p_nice - PRIO_MIN) + 762 p->p_estcpu / ESTCPURAMP); 763 764 /* 765 * p_interactive is -128 to +127 and represents very long term 766 * interactivity or batch (whereas estcpu is a much faster variable). 767 * Interactivity can modify the priority by up to 8 units either way. 768 * (8 units == approximately 4 nice levels). 769 */ 770 interactive = p->p_interactive / 10; 771 newpriority += interactive; 772 773 newpriority = MIN(newpriority, MAXPRI); 774 newpriority = MAX(newpriority, 0); 775 npq = newpriority / PPQ; 776 crit_enter(); 777 opq = (p->p_priority & PRIMASK) / PPQ; 778 if (p->p_stat == SRUN && (p->p_flag & P_ONRUNQ) && opq != npq) { 779 /* 780 * We have to move the process to another queue 781 */ 782 remrunqueue(p); 783 p->p_priority = PRIBASE_NORMAL + newpriority; 784 setrunqueue(p); 785 } else { 786 /* 787 * We can just adjust the priority and it will be picked 788 * up later. 789 */ 790 KKASSERT(opq == npq || (p->p_flag & P_ONRUNQ) == 0); 791 p->p_priority = PRIBASE_NORMAL + newpriority; 792 } 793 crit_exit(); 794 } 795 796 /* 797 * Compute a tenex style load average of a quantity on 798 * 1, 5 and 15 minute intervals. 799 */ 800 static void 801 loadav(void *arg) 802 { 803 int i, nrun; 804 struct loadavg *avg; 805 struct proc *p; 806 thread_t td; 807 808 avg = &averunnable; 809 nrun = 0; 810 FOREACH_PROC_IN_SYSTEM(p) { 811 switch (p->p_stat) { 812 case SRUN: 813 if ((td = p->p_thread) == NULL) 814 break; 815 if (td->td_flags & TDF_BLOCKED) 816 break; 817 /* fall through */ 818 case SIDL: 819 nrun++; 820 break; 821 default: 822 break; 823 } 824 } 825 for (i = 0; i < 3; i++) 826 avg->ldavg[i] = (cexp[i] * avg->ldavg[i] + 827 nrun * FSCALE * (FSCALE - cexp[i])) >> FSHIFT; 828 829 /* 830 * Schedule the next update to occur after 5 seconds, but add a 831 * random variation to avoid synchronisation with processes that 832 * run at regular intervals. 833 */ 834 callout_reset(&loadav_callout, hz * 4 + (int)(random() % (hz * 2 + 1)), 835 loadav, NULL); 836 } 837 838 /* ARGSUSED */ 839 static void 840 sched_setup(void *dummy) 841 { 842 callout_init(&loadav_callout); 843 callout_init(&roundrobin_callout); 844 callout_init(&schedcpu_callout); 845 846 /* Kick off timeout driven events by calling first time. */ 847 roundrobin(NULL); 848 schedcpu(NULL); 849 loadav(NULL); 850 } 851 852 /* 853 * We adjust the priority of the current process. The priority of 854 * a process gets worse as it accumulates CPU time. The cpu usage 855 * estimator (p_estcpu) is increased here. resetpriority() will 856 * compute a different priority each time p_estcpu increases by 857 * INVERSE_ESTCPU_WEIGHT * (until MAXPRI is reached). 858 * 859 * The cpu usage estimator ramps up quite quickly when the process is 860 * running (linearly), and decays away exponentially, at a rate which 861 * is proportionally slower when the system is busy. The basic principle 862 * is that the system will 90% forget that the process used a lot of CPU 863 * time in 5 * loadav seconds. This causes the system to favor processes 864 * which haven't run much recently, and to round-robin among other processes. 865 * 866 * The actual schedulerclock interrupt rate is ESTCPUFREQ, but we generally 867 * want to ramp-up at a faster rate, ESTCPUVFREQ, so p_estcpu is scaled 868 * by (ESTCPUVFREQ / ESTCPUFREQ). You can control the ramp-up/ramp-down 869 * rate by adjusting ESTCPUVFREQ in sys/proc.h in integer multiples 870 * of ESTCPUFREQ. 871 * 872 * WARNING! called from a fast-int or an IPI, the MP lock MIGHT NOT BE HELD 873 * and we cannot block. 874 */ 875 void 876 schedulerclock(void *dummy) 877 { 878 struct thread *td; 879 struct proc *p; 880 881 td = curthread; 882 if ((p = td->td_proc) != NULL) { 883 p->p_cpticks++; /* cpticks runs at ESTCPUFREQ */ 884 p->p_estcpu = ESTCPULIM(p->p_estcpu + ESTCPUVFREQ / ESTCPUFREQ); 885 if (try_mplock()) { 886 resetpriority(p); 887 rel_mplock(); 888 } 889 } 890 } 891 892