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 thread *td; 126 struct proc *p; 127 int catch, rval, sig, flags; 128 WITNESS_SAVE_DECL(mtx); 129 130 td = curthread; 131 p = td->td_proc; 132 #ifdef KTRACE 133 if (KTRPOINT(td, KTR_CSW)) 134 ktrcsw(1, 0); 135 #endif 136 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, mtx == NULL ? NULL : 137 &mtx->mtx_object, "Sleeping on \"%s\"", wmesg); 138 KASSERT(timo != 0 || mtx_owned(&Giant) || mtx != NULL, 139 ("sleeping without a mutex")); 140 KASSERT(p != NULL, ("msleep1")); 141 KASSERT(ident != NULL && TD_IS_RUNNING(td), ("msleep")); 142 143 if (cold) { 144 /* 145 * During autoconfiguration, just return; 146 * don't run any other threads or panic below, 147 * in case this is the idle thread and already asleep. 148 * XXX: this used to do "s = splhigh(); splx(safepri); 149 * splx(s);" to give interrupts a chance, but there is 150 * no way to give interrupts a chance now. 151 */ 152 if (mtx != NULL && priority & PDROP) 153 mtx_unlock(mtx); 154 return (0); 155 } 156 catch = priority & PCATCH; 157 rval = 0; 158 159 /* 160 * If we are already on a sleep queue, then remove us from that 161 * sleep queue first. We have to do this to handle recursive 162 * sleeps. 163 */ 164 if (TD_ON_SLEEPQ(td)) 165 sleepq_remove(td, td->td_wchan); 166 167 sleepq_lock(ident); 168 if (catch) { 169 /* 170 * Don't bother sleeping if we are exiting and not the exiting 171 * thread or if our thread is marked as interrupted. 172 */ 173 mtx_lock_spin(&sched_lock); 174 rval = thread_sleep_check(td); 175 mtx_unlock_spin(&sched_lock); 176 if (rval != 0) { 177 sleepq_release(ident); 178 return (rval); 179 } 180 } 181 CTR5(KTR_PROC, "msleep: thread %p (pid %ld, %s) on %s (%p)", 182 (void *)td, (long)p->p_pid, p->p_comm, wmesg, ident); 183 184 DROP_GIANT(); 185 if (mtx != NULL) { 186 mtx_assert(mtx, MA_OWNED | MA_NOTRECURSED); 187 WITNESS_SAVE(&mtx->mtx_object, mtx); 188 mtx_unlock(mtx); 189 } 190 191 /* 192 * We put ourselves on the sleep queue and start our timeout 193 * before calling thread_suspend_check, as we could stop there, 194 * and a wakeup or a SIGCONT (or both) could occur while we were 195 * stopped without resuming us. Thus, we must be ready for sleep 196 * when cursig() is called. If the wakeup happens while we're 197 * stopped, then td will no longer be on a sleep queue upon 198 * return from cursig(). 199 */ 200 flags = SLEEPQ_MSLEEP; 201 if (catch) 202 flags |= SLEEPQ_INTERRUPTIBLE; 203 sleepq_add(ident, mtx, wmesg, flags); 204 if (timo) 205 sleepq_set_timeout(ident, timo); 206 if (catch) { 207 sig = sleepq_catch_signals(ident); 208 } else 209 sig = 0; 210 211 /* 212 * Adjust this thread's priority. 213 * 214 * XXX: do we need to save priority in td_base_pri? 215 */ 216 mtx_lock_spin(&sched_lock); 217 sched_prio(td, priority & PRIMASK); 218 mtx_unlock_spin(&sched_lock); 219 220 if (timo && catch) 221 rval = sleepq_timedwait_sig(ident, sig != 0); 222 else if (timo) 223 rval = sleepq_timedwait(ident); 224 else if (catch) 225 rval = sleepq_wait_sig(ident); 226 else { 227 sleepq_wait(ident); 228 rval = 0; 229 } 230 if (rval == 0 && catch) 231 rval = sleepq_calc_signal_retval(sig); 232 #ifdef KTRACE 233 if (KTRPOINT(td, KTR_CSW)) 234 ktrcsw(0, 0); 235 #endif 236 PICKUP_GIANT(); 237 if (mtx != NULL && !(priority & PDROP)) { 238 mtx_lock(mtx); 239 WITNESS_RESTORE(&mtx->mtx_object, mtx); 240 } 241 return (rval); 242 } 243 244 /* 245 * Make all threads sleeping on the specified identifier runnable. 246 */ 247 void 248 wakeup(ident) 249 register void *ident; 250 { 251 252 sleepq_lock(ident); 253 sleepq_broadcast(ident, SLEEPQ_MSLEEP, -1); 254 } 255 256 /* 257 * Make a thread sleeping on the specified identifier runnable. 258 * May wake more than one thread if a target thread is currently 259 * swapped out. 260 */ 261 void 262 wakeup_one(ident) 263 register void *ident; 264 { 265 266 sleepq_lock(ident); 267 sleepq_signal(ident, SLEEPQ_MSLEEP, -1); 268 } 269 270 /* 271 * The machine independent parts of context switching. 272 */ 273 void 274 mi_switch(int flags, struct thread *newtd) 275 { 276 struct bintime new_switchtime; 277 struct thread *td; 278 struct proc *p; 279 280 mtx_assert(&sched_lock, MA_OWNED | MA_NOTRECURSED); 281 td = curthread; /* XXX */ 282 p = td->td_proc; /* XXX */ 283 KASSERT(!TD_ON_RUNQ(td), ("mi_switch: called by old code")); 284 #ifdef INVARIANTS 285 if (!TD_ON_LOCK(td) && !TD_IS_RUNNING(td)) 286 mtx_assert(&Giant, MA_NOTOWNED); 287 #endif 288 KASSERT(td->td_critnest == 1 || (td->td_critnest == 2 && 289 (td->td_pflags & TDP_OWEPREEMPT) != 0 && (flags & SW_INVOL) != 0 && 290 newtd == NULL), 291 ("mi_switch: switch in a critical section")); 292 KASSERT((flags & (SW_INVOL | SW_VOL)) != 0, 293 ("mi_switch: switch must be voluntary or involuntary")); 294 KASSERT(newtd != curthread, ("mi_switch: preempting back to ourself")); 295 296 if (flags & SW_VOL) 297 p->p_stats->p_ru.ru_nvcsw++; 298 else 299 p->p_stats->p_ru.ru_nivcsw++; 300 301 /* 302 * Compute the amount of time during which the current 303 * process was running, and add that to its total so far. 304 */ 305 binuptime(&new_switchtime); 306 bintime_add(&p->p_rux.rux_runtime, &new_switchtime); 307 bintime_sub(&p->p_rux.rux_runtime, PCPU_PTR(switchtime)); 308 309 td->td_generation++; /* bump preempt-detect counter */ 310 311 /* 312 * Don't perform context switches from the debugger. 313 */ 314 if (kdb_active) { 315 mtx_unlock_spin(&sched_lock); 316 kdb_backtrace(); 317 kdb_reenter(); 318 panic("%s: did not reenter debugger", __func__); 319 } 320 321 /* 322 * Check if the process exceeds its cpu resource allocation. If 323 * over max, arrange to kill the process in ast(). 324 */ 325 if (p->p_cpulimit != RLIM_INFINITY && 326 p->p_rux.rux_runtime.sec > p->p_cpulimit) { 327 p->p_sflag |= PS_XCPU; 328 td->td_flags |= TDF_ASTPENDING; 329 } 330 331 /* 332 * Finish up stats for outgoing thread. 333 */ 334 cnt.v_swtch++; 335 PCPU_SET(switchtime, new_switchtime); 336 PCPU_SET(switchticks, ticks); 337 CTR4(KTR_PROC, "mi_switch: old thread %p (kse %p, pid %ld, %s)", 338 (void *)td, td->td_sched, (long)p->p_pid, p->p_comm); 339 if ((flags & SW_VOL) && (td->td_proc->p_flag & P_SA)) 340 newtd = thread_switchout(td, flags, newtd); 341 sched_switch(td, newtd, flags); 342 343 CTR4(KTR_PROC, "mi_switch: new thread %p (kse %p, pid %ld, %s)", 344 (void *)td, td->td_sched, (long)p->p_pid, p->p_comm); 345 346 /* 347 * If the last thread was exiting, finish cleaning it up. 348 */ 349 if ((td = PCPU_GET(deadthread))) { 350 PCPU_SET(deadthread, NULL); 351 thread_stash(td); 352 } 353 } 354 355 /* 356 * Change process state to be runnable, 357 * placing it on the run queue if it is in memory, 358 * and awakening the swapper if it isn't in memory. 359 */ 360 void 361 setrunnable(struct thread *td) 362 { 363 struct proc *p; 364 365 p = td->td_proc; 366 mtx_assert(&sched_lock, MA_OWNED); 367 switch (p->p_state) { 368 case PRS_ZOMBIE: 369 panic("setrunnable(1)"); 370 default: 371 break; 372 } 373 switch (td->td_state) { 374 case TDS_RUNNING: 375 case TDS_RUNQ: 376 return; 377 case TDS_INHIBITED: 378 /* 379 * If we are only inhibited because we are swapped out 380 * then arange to swap in this process. Otherwise just return. 381 */ 382 if (td->td_inhibitors != TDI_SWAPPED) 383 return; 384 /* XXX: intentional fall-through ? */ 385 case TDS_CAN_RUN: 386 break; 387 default: 388 printf("state is 0x%x", td->td_state); 389 panic("setrunnable(2)"); 390 } 391 if ((p->p_sflag & PS_INMEM) == 0) { 392 if ((p->p_sflag & PS_SWAPPINGIN) == 0) { 393 p->p_sflag |= PS_SWAPINREQ; 394 /* 395 * due to a LOR between sched_lock and 396 * the sleepqueue chain locks, delay 397 * wakeup proc0 until thread leaves 398 * critical region. 399 */ 400 curthread->td_pflags |= TDP_WAKEPROC0; 401 } 402 } else 403 sched_wakeup(td); 404 } 405 406 /* 407 * Compute a tenex style load average of a quantity on 408 * 1, 5 and 15 minute intervals. 409 * XXXKSE Needs complete rewrite when correct info is available. 410 * Completely Bogus.. only works with 1:1 (but compiles ok now :-) 411 */ 412 static void 413 loadav(void *arg) 414 { 415 int i, nrun; 416 struct loadavg *avg; 417 418 nrun = sched_load(); 419 avg = &averunnable; 420 421 for (i = 0; i < 3; i++) 422 avg->ldavg[i] = (cexp[i] * avg->ldavg[i] + 423 nrun * FSCALE * (FSCALE - cexp[i])) >> FSHIFT; 424 425 /* 426 * Schedule the next update to occur after 5 seconds, but add a 427 * random variation to avoid synchronisation with processes that 428 * run at regular intervals. 429 */ 430 callout_reset(&loadav_callout, hz * 4 + (int)(random() % (hz * 2 + 1)), 431 loadav, NULL); 432 } 433 434 static void 435 lboltcb(void *arg) 436 { 437 wakeup(&lbolt); 438 callout_reset(&lbolt_callout, hz, lboltcb, NULL); 439 } 440 441 /* ARGSUSED */ 442 static void 443 synch_setup(dummy) 444 void *dummy; 445 { 446 callout_init(&loadav_callout, CALLOUT_MPSAFE); 447 callout_init(&lbolt_callout, CALLOUT_MPSAFE); 448 449 /* Kick off timeout driven events by calling first time. */ 450 loadav(NULL); 451 lboltcb(NULL); 452 } 453 454 /* 455 * General purpose yield system call 456 */ 457 int 458 yield(struct thread *td, struct yield_args *uap) 459 { 460 struct ksegrp *kg; 461 462 kg = td->td_ksegrp; 463 mtx_assert(&Giant, MA_NOTOWNED); 464 mtx_lock_spin(&sched_lock); 465 sched_prio(td, PRI_MAX_TIMESHARE); 466 mi_switch(SW_VOL, NULL); 467 mtx_unlock_spin(&sched_lock); 468 td->td_retval[0] = 0; 469 return (0); 470 } 471