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 * 4. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * @(#)kern_synch.c 8.9 (Berkeley) 5/19/95 35 */ 36 37 #include <sys/cdefs.h> 38 __FBSDID("$FreeBSD$"); 39 40 #include "opt_ktrace.h" 41 42 #include <sys/param.h> 43 #include <sys/systm.h> 44 #include <sys/condvar.h> 45 #include <sys/kdb.h> 46 #include <sys/kernel.h> 47 #include <sys/ktr.h> 48 #include <sys/lock.h> 49 #include <sys/mutex.h> 50 #include <sys/proc.h> 51 #include <sys/resourcevar.h> 52 #include <sys/sched.h> 53 #include <sys/signalvar.h> 54 #include <sys/sleepqueue.h> 55 #include <sys/smp.h> 56 #include <sys/sx.h> 57 #include <sys/sysctl.h> 58 #include <sys/sysproto.h> 59 #include <sys/vmmeter.h> 60 #ifdef KTRACE 61 #include <sys/uio.h> 62 #include <sys/ktrace.h> 63 #endif 64 65 #include <machine/cpu.h> 66 67 static void synch_setup(void *dummy); 68 SYSINIT(synch_setup, SI_SUB_KICK_SCHEDULER, SI_ORDER_FIRST, synch_setup, NULL) 69 70 int hogticks; 71 int lbolt; 72 73 static struct callout loadav_callout; 74 static struct callout lbolt_callout; 75 76 struct loadavg averunnable = 77 { {0, 0, 0}, FSCALE }; /* load average, of runnable procs */ 78 /* 79 * Constants for averages over 1, 5, and 15 minutes 80 * when sampling at 5 second intervals. 81 */ 82 static fixpt_t cexp[3] = { 83 0.9200444146293232 * FSCALE, /* exp(-1/12) */ 84 0.9834714538216174 * FSCALE, /* exp(-1/60) */ 85 0.9944598480048967 * FSCALE, /* exp(-1/180) */ 86 }; 87 88 /* kernel uses `FSCALE', userland (SHOULD) use kern.fscale */ 89 static int fscale __unused = FSCALE; 90 SYSCTL_INT(_kern, OID_AUTO, fscale, CTLFLAG_RD, 0, FSCALE, ""); 91 92 static void loadav(void *arg); 93 static void lboltcb(void *arg); 94 95 void 96 sleepinit(void) 97 { 98 99 hogticks = (hz / 10) * 2; /* Default only. */ 100 init_sleepqueues(); 101 } 102 103 /* 104 * General sleep call. Suspends the current process until a wakeup is 105 * performed on the specified identifier. The process will then be made 106 * runnable with the specified priority. Sleeps at most timo/hz seconds 107 * (0 means no timeout). If pri includes PCATCH flag, signals are checked 108 * before and after sleeping, else signals are not checked. Returns 0 if 109 * awakened, EWOULDBLOCK if the timeout expires. If PCATCH is set and a 110 * signal needs to be delivered, ERESTART is returned if the current system 111 * call should be restarted if possible, and EINTR is returned if the system 112 * call should be interrupted by the signal (return EINTR). 113 * 114 * The mutex argument is exited before the caller is suspended, and 115 * entered before msleep returns. If priority includes the PDROP 116 * flag the mutex is not entered before returning. 117 */ 118 int 119 msleep(ident, mtx, priority, wmesg, timo) 120 void *ident; 121 struct mtx *mtx; 122 int priority, timo; 123 const char *wmesg; 124 { 125 struct sleepqueue *sq; 126 struct thread *td; 127 struct proc *p; 128 int catch, rval, sig; 129 WITNESS_SAVE_DECL(mtx); 130 131 td = curthread; 132 p = td->td_proc; 133 #ifdef KTRACE 134 if (KTRPOINT(td, KTR_CSW)) 135 ktrcsw(1, 0); 136 #endif 137 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, mtx == NULL ? NULL : 138 &mtx->mtx_object, "Sleeping on \"%s\"", wmesg); 139 KASSERT(timo != 0 || mtx_owned(&Giant) || mtx != NULL, 140 ("sleeping without a mutex")); 141 KASSERT(p != NULL, ("msleep1")); 142 KASSERT(ident != NULL && TD_IS_RUNNING(td), ("msleep")); 143 144 if (cold) { 145 /* 146 * During autoconfiguration, just return; 147 * don't run any other threads or panic below, 148 * in case this is the idle thread and already asleep. 149 * XXX: this used to do "s = splhigh(); splx(safepri); 150 * splx(s);" to give interrupts a chance, but there is 151 * no way to give interrupts a chance now. 152 */ 153 if (mtx != NULL && priority & PDROP) 154 mtx_unlock(mtx); 155 return (0); 156 } 157 catch = priority & PCATCH; 158 rval = 0; 159 160 /* 161 * If we are already on a sleep queue, then remove us from that 162 * sleep queue first. We have to do this to handle recursive 163 * sleeps. 164 */ 165 if (TD_ON_SLEEPQ(td)) 166 sleepq_remove(td, td->td_wchan); 167 168 sq = sleepq_lookup(ident); 169 mtx_lock_spin(&sched_lock); 170 171 if (p->p_flag & P_SA || p->p_numthreads > 1) { 172 /* 173 * Just don't bother if we are exiting 174 * and not the exiting thread or thread was marked as 175 * interrupted. 176 */ 177 if (catch) { 178 if ((p->p_flag & P_WEXIT) && p->p_singlethread != td) { 179 mtx_unlock_spin(&sched_lock); 180 sleepq_release(ident); 181 return (EINTR); 182 } 183 if (td->td_flags & TDF_INTERRUPT) { 184 mtx_unlock_spin(&sched_lock); 185 sleepq_release(ident); 186 return (td->td_intrval); 187 } 188 } 189 } 190 mtx_unlock_spin(&sched_lock); 191 CTR5(KTR_PROC, "msleep: thread %p (pid %ld, %s) on %s (%p)", 192 (void *)td, (long)p->p_pid, p->p_comm, wmesg, ident); 193 194 DROP_GIANT(); 195 if (mtx != NULL) { 196 mtx_assert(mtx, MA_OWNED | MA_NOTRECURSED); 197 WITNESS_SAVE(&mtx->mtx_object, mtx); 198 mtx_unlock(mtx); 199 } 200 201 /* 202 * We put ourselves on the sleep queue and start our timeout 203 * before calling thread_suspend_check, as we could stop there, 204 * and a wakeup or a SIGCONT (or both) could occur while we were 205 * stopped without resuming us. Thus, we must be ready for sleep 206 * when cursig() is called. If the wakeup happens while we're 207 * stopped, then td will no longer be on a sleep queue upon 208 * return from cursig(). 209 */ 210 sleepq_add(sq, ident, mtx, wmesg, 0); 211 if (timo) 212 sleepq_set_timeout(ident, timo); 213 if (catch) { 214 sig = sleepq_catch_signals(ident); 215 if (sig == 0 && !TD_ON_SLEEPQ(td)) { 216 mtx_lock_spin(&sched_lock); 217 td->td_flags &= ~TDF_SINTR; 218 mtx_unlock_spin(&sched_lock); 219 catch = 0; 220 } 221 } else 222 sig = 0; 223 224 /* 225 * Adjust this thread's priority. 226 * 227 * XXX: do we need to save priority in td_base_pri? 228 */ 229 mtx_lock_spin(&sched_lock); 230 sched_prio(td, priority & PRIMASK); 231 mtx_unlock_spin(&sched_lock); 232 233 if (timo && catch) 234 rval = sleepq_timedwait_sig(ident, sig != 0); 235 else if (timo) 236 rval = sleepq_timedwait(ident); 237 else if (catch) 238 rval = sleepq_wait_sig(ident); 239 else { 240 sleepq_wait(ident); 241 rval = 0; 242 } 243 if (rval == 0 && catch) 244 rval = sleepq_calc_signal_retval(sig); 245 #ifdef KTRACE 246 if (KTRPOINT(td, KTR_CSW)) 247 ktrcsw(0, 0); 248 #endif 249 PICKUP_GIANT(); 250 if (mtx != NULL && !(priority & PDROP)) { 251 mtx_lock(mtx); 252 WITNESS_RESTORE(&mtx->mtx_object, mtx); 253 } 254 return (rval); 255 } 256 257 /* 258 * Make all threads sleeping on the specified identifier runnable. 259 */ 260 void 261 wakeup(ident) 262 register void *ident; 263 { 264 265 sleepq_broadcast(ident, 0, -1); 266 } 267 268 /* 269 * Make a thread sleeping on the specified identifier runnable. 270 * May wake more than one thread if a target thread is currently 271 * swapped out. 272 */ 273 void 274 wakeup_one(ident) 275 register void *ident; 276 { 277 278 sleepq_signal(ident, 0, -1); 279 } 280 281 /* 282 * The machine independent parts of context switching. 283 */ 284 void 285 mi_switch(int flags, struct thread *newtd) 286 { 287 struct bintime new_switchtime; 288 struct thread *td; 289 struct proc *p; 290 291 mtx_assert(&sched_lock, MA_OWNED | MA_NOTRECURSED); 292 td = curthread; /* XXX */ 293 p = td->td_proc; /* XXX */ 294 KASSERT(!TD_ON_RUNQ(td), ("mi_switch: called by old code")); 295 #ifdef INVARIANTS 296 if (!TD_ON_LOCK(td) && !TD_IS_RUNNING(td)) 297 mtx_assert(&Giant, MA_NOTOWNED); 298 #endif 299 KASSERT(td->td_critnest == 1 || (td->td_critnest == 2 && 300 (td->td_flags & TDF_OWEPREEMPT) != 0 && (flags & SW_INVOL) != 0 && 301 newtd == NULL), 302 ("mi_switch: switch in a critical section")); 303 KASSERT((flags & (SW_INVOL | SW_VOL)) != 0, 304 ("mi_switch: switch must be voluntary or involuntary")); 305 306 if (flags & SW_VOL) 307 p->p_stats->p_ru.ru_nvcsw++; 308 else 309 p->p_stats->p_ru.ru_nivcsw++; 310 311 /* 312 * Compute the amount of time during which the current 313 * process was running, and add that to its total so far. 314 */ 315 binuptime(&new_switchtime); 316 bintime_add(&p->p_runtime, &new_switchtime); 317 bintime_sub(&p->p_runtime, PCPU_PTR(switchtime)); 318 319 td->td_generation++; /* bump preempt-detect counter */ 320 321 /* 322 * Don't perform context switches from the debugger. 323 */ 324 if (kdb_active) { 325 mtx_unlock_spin(&sched_lock); 326 kdb_backtrace(); 327 kdb_reenter(); 328 panic("%s: did not reenter debugger", __func__); 329 } 330 331 /* 332 * Check if the process exceeds its cpu resource allocation. If 333 * over max, arrange to kill the process in ast(). 334 */ 335 if (p->p_cpulimit != RLIM_INFINITY && 336 p->p_runtime.sec > p->p_cpulimit) { 337 p->p_sflag |= PS_XCPU; 338 td->td_flags |= TDF_ASTPENDING; 339 } 340 341 /* 342 * Finish up stats for outgoing thread. 343 */ 344 cnt.v_swtch++; 345 PCPU_SET(switchtime, new_switchtime); 346 PCPU_SET(switchticks, ticks); 347 CTR3(KTR_PROC, "mi_switch: old thread %p (pid %ld, %s)", 348 (void *)td, (long)p->p_pid, p->p_comm); 349 if (td->td_proc->p_flag & P_SA) 350 thread_switchout(td); 351 sched_switch(td, newtd); 352 353 CTR3(KTR_PROC, "mi_switch: new thread %p (pid %ld, %s)", 354 (void *)td, (long)p->p_pid, p->p_comm); 355 356 /* 357 * If the last thread was exiting, finish cleaning it up. 358 */ 359 if ((td = PCPU_GET(deadthread))) { 360 PCPU_SET(deadthread, NULL); 361 thread_stash(td); 362 } 363 } 364 365 /* 366 * Change process state to be runnable, 367 * placing it on the run queue if it is in memory, 368 * and awakening the swapper if it isn't in memory. 369 */ 370 void 371 setrunnable(struct thread *td) 372 { 373 struct proc *p; 374 375 p = td->td_proc; 376 mtx_assert(&sched_lock, MA_OWNED); 377 switch (p->p_state) { 378 case PRS_ZOMBIE: 379 panic("setrunnable(1)"); 380 default: 381 break; 382 } 383 switch (td->td_state) { 384 case TDS_RUNNING: 385 case TDS_RUNQ: 386 return; 387 case TDS_INHIBITED: 388 /* 389 * If we are only inhibited because we are swapped out 390 * then arange to swap in this process. Otherwise just return. 391 */ 392 if (td->td_inhibitors != TDI_SWAPPED) 393 return; 394 /* XXX: intentional fall-through ? */ 395 case TDS_CAN_RUN: 396 break; 397 default: 398 printf("state is 0x%x", td->td_state); 399 panic("setrunnable(2)"); 400 } 401 if ((p->p_sflag & PS_INMEM) == 0) { 402 if ((p->p_sflag & PS_SWAPPINGIN) == 0) { 403 p->p_sflag |= PS_SWAPINREQ; 404 wakeup(&proc0); 405 } 406 } else 407 sched_wakeup(td); 408 } 409 410 /* 411 * Compute a tenex style load average of a quantity on 412 * 1, 5 and 15 minute intervals. 413 * XXXKSE Needs complete rewrite when correct info is available. 414 * Completely Bogus.. only works with 1:1 (but compiles ok now :-) 415 */ 416 static void 417 loadav(void *arg) 418 { 419 int i, nrun; 420 struct loadavg *avg; 421 422 nrun = sched_load(); 423 avg = &averunnable; 424 425 for (i = 0; i < 3; i++) 426 avg->ldavg[i] = (cexp[i] * avg->ldavg[i] + 427 nrun * FSCALE * (FSCALE - cexp[i])) >> FSHIFT; 428 429 /* 430 * Schedule the next update to occur after 5 seconds, but add a 431 * random variation to avoid synchronisation with processes that 432 * run at regular intervals. 433 */ 434 callout_reset(&loadav_callout, hz * 4 + (int)(random() % (hz * 2 + 1)), 435 loadav, NULL); 436 } 437 438 static void 439 lboltcb(void *arg) 440 { 441 wakeup(&lbolt); 442 callout_reset(&lbolt_callout, hz, lboltcb, NULL); 443 } 444 445 /* ARGSUSED */ 446 static void 447 synch_setup(dummy) 448 void *dummy; 449 { 450 callout_init(&loadav_callout, CALLOUT_MPSAFE); 451 callout_init(&lbolt_callout, CALLOUT_MPSAFE); 452 453 /* Kick off timeout driven events by calling first time. */ 454 loadav(NULL); 455 lboltcb(NULL); 456 } 457 458 /* 459 * General purpose yield system call 460 */ 461 int 462 yield(struct thread *td, struct yield_args *uap) 463 { 464 struct ksegrp *kg; 465 466 kg = td->td_ksegrp; 467 mtx_assert(&Giant, MA_NOTOWNED); 468 mtx_lock_spin(&sched_lock); 469 sched_prio(td, PRI_MAX_TIMESHARE); 470 mi_switch(SW_VOL, NULL); 471 mtx_unlock_spin(&sched_lock); 472 td->td_retval[0] = 0; 473 return (0); 474 } 475