1 /* $OpenBSD: kern_clock.c,v 1.68 2009/01/21 21:02:39 miod Exp $ */ 2 /* $NetBSD: kern_clock.c,v 1.34 1996/06/09 04:51:03 briggs Exp $ */ 3 4 /*- 5 * Copyright (c) 1982, 1986, 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_clock.c 8.5 (Berkeley) 1/21/94 38 */ 39 40 #include <sys/param.h> 41 #include <sys/systm.h> 42 #include <sys/dkstat.h> 43 #include <sys/timeout.h> 44 #include <sys/kernel.h> 45 #include <sys/limits.h> 46 #include <sys/proc.h> 47 #include <sys/user.h> 48 #include <sys/resourcevar.h> 49 #include <sys/signalvar.h> 50 #include <uvm/uvm_extern.h> 51 #include <sys/sysctl.h> 52 #include <sys/sched.h> 53 #ifdef __HAVE_TIMECOUNTER 54 #include <sys/timetc.h> 55 #endif 56 57 #include <machine/cpu.h> 58 59 #ifdef GPROF 60 #include <sys/gmon.h> 61 #endif 62 63 /* 64 * Clock handling routines. 65 * 66 * This code is written to operate with two timers that run independently of 67 * each other. The main clock, running hz times per second, is used to keep 68 * track of real time. The second timer handles kernel and user profiling, 69 * and does resource use estimation. If the second timer is programmable, 70 * it is randomized to avoid aliasing between the two clocks. For example, 71 * the randomization prevents an adversary from always giving up the cpu 72 * just before its quantum expires. Otherwise, it would never accumulate 73 * cpu ticks. The mean frequency of the second timer is stathz. 74 * 75 * If no second timer exists, stathz will be zero; in this case we drive 76 * profiling and statistics off the main clock. This WILL NOT be accurate; 77 * do not do it unless absolutely necessary. 78 * 79 * The statistics clock may (or may not) be run at a higher rate while 80 * profiling. This profile clock runs at profhz. We require that profhz 81 * be an integral multiple of stathz. 82 * 83 * If the statistics clock is running fast, it must be divided by the ratio 84 * profhz/stathz for statistics. (For profiling, every tick counts.) 85 */ 86 87 /* 88 * Bump a timeval by a small number of usec's. 89 */ 90 #define BUMPTIME(t, usec) { \ 91 volatile struct timeval *tp = (t); \ 92 long us; \ 93 \ 94 tp->tv_usec = us = tp->tv_usec + (usec); \ 95 if (us >= 1000000) { \ 96 tp->tv_usec = us - 1000000; \ 97 tp->tv_sec++; \ 98 } \ 99 } 100 101 int stathz; 102 int schedhz; 103 int profhz; 104 int profprocs; 105 int ticks; 106 static int psdiv, pscnt; /* prof => stat divider */ 107 int psratio; /* ratio: prof / stat */ 108 109 long cp_time[CPUSTATES]; 110 111 #ifndef __HAVE_TIMECOUNTER 112 int tickfix, tickfixinterval; /* used if tick not really integral */ 113 static int tickfixcnt; /* accumulated fractional error */ 114 115 volatile time_t time_second; 116 volatile time_t time_uptime; 117 118 volatile struct timeval time 119 __attribute__((__aligned__(__alignof__(quad_t)))); 120 volatile struct timeval mono_time; 121 #endif 122 123 #ifdef __HAVE_GENERIC_SOFT_INTERRUPTS 124 void *softclock_si; 125 void generic_softclock(void *); 126 127 void 128 generic_softclock(void *ignore) 129 { 130 /* 131 * XXX - don't commit, just a dummy wrapper until we learn everyone 132 * deal with a changed proto for softclock(). 133 */ 134 softclock(); 135 } 136 #endif 137 138 /* 139 * Initialize clock frequencies and start both clocks running. 140 */ 141 void 142 initclocks(void) 143 { 144 int i; 145 #ifdef __HAVE_TIMECOUNTER 146 extern void inittimecounter(void); 147 #endif 148 149 #ifdef __HAVE_GENERIC_SOFT_INTERRUPTS 150 softclock_si = softintr_establish(IPL_SOFTCLOCK, generic_softclock, NULL); 151 if (softclock_si == NULL) 152 panic("initclocks: unable to register softclock intr"); 153 #endif 154 155 /* 156 * Set divisors to 1 (normal case) and let the machine-specific 157 * code do its bit. 158 */ 159 psdiv = pscnt = 1; 160 cpu_initclocks(); 161 162 /* 163 * Compute profhz/stathz, and fix profhz if needed. 164 */ 165 i = stathz ? stathz : hz; 166 if (profhz == 0) 167 profhz = i; 168 psratio = profhz / i; 169 170 /* For very large HZ, ensure that division by 0 does not occur later */ 171 if (tickadj == 0) 172 tickadj = 1; 173 174 #ifdef __HAVE_TIMECOUNTER 175 inittimecounter(); 176 #endif 177 } 178 179 /* 180 * hardclock does the accounting needed for ITIMER_PROF and ITIMER_VIRTUAL. 181 * We don't want to send signals with psignal from hardclock because it makes 182 * MULTIPROCESSOR locking very complicated. Instead we use a small trick 183 * to send the signals safely and without blocking too many interrupts 184 * while doing that (signal handling can be heavy). 185 * 186 * hardclock detects that the itimer has expired, and schedules a timeout 187 * to deliver the signal. This works because of the following reasons: 188 * - The timeout structures can be in struct pstats because the timers 189 * can be only activated on curproc (never swapped). Swapout can 190 * only happen from a kernel thread and softclock runs before threads 191 * are scheduled. 192 * - The timeout can be scheduled with a 1 tick time because we're 193 * doing it before the timeout processing in hardclock. So it will 194 * be scheduled to run as soon as possible. 195 * - The timeout will be run in softclock which will run before we 196 * return to userland and process pending signals. 197 * - If the system is so busy that several VIRTUAL/PROF ticks are 198 * sent before softclock processing, we'll send only one signal. 199 * But if we'd send the signal from hardclock only one signal would 200 * be delivered to the user process. So userland will only see one 201 * signal anyway. 202 */ 203 204 void 205 virttimer_trampoline(void *v) 206 { 207 struct proc *p = v; 208 209 psignal(p, SIGVTALRM); 210 } 211 212 void 213 proftimer_trampoline(void *v) 214 { 215 struct proc *p = v; 216 217 psignal(p, SIGPROF); 218 } 219 220 /* 221 * The real-time timer, interrupting hz times per second. 222 */ 223 void 224 hardclock(struct clockframe *frame) 225 { 226 struct proc *p; 227 #ifndef __HAVE_TIMECOUNTER 228 int delta; 229 extern int tickdelta; 230 extern long timedelta; 231 extern int64_t ntp_tick_permanent; 232 extern int64_t ntp_tick_acc; 233 #endif 234 struct cpu_info *ci = curcpu(); 235 236 p = curproc; 237 if (p && ((p->p_flag & (P_SYSTEM | P_WEXIT)) == 0)) { 238 struct pstats *pstats; 239 240 /* 241 * Run current process's virtual and profile time, as needed. 242 */ 243 pstats = p->p_stats; 244 if (CLKF_USERMODE(frame) && 245 timerisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value) && 246 itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL], tick) == 0) 247 timeout_add(&pstats->p_virt_to, 1); 248 if (timerisset(&pstats->p_timer[ITIMER_PROF].it_value) && 249 itimerdecr(&pstats->p_timer[ITIMER_PROF], tick) == 0) 250 timeout_add(&pstats->p_prof_to, 1); 251 } 252 253 /* 254 * If no separate statistics clock is available, run it from here. 255 */ 256 if (stathz == 0) 257 statclock(frame); 258 259 if (--ci->ci_schedstate.spc_rrticks <= 0) 260 roundrobin(ci); 261 262 /* 263 * If we are not the primary CPU, we're not allowed to do 264 * any more work. 265 */ 266 if (CPU_IS_PRIMARY(ci) == 0) 267 return; 268 269 #ifndef __HAVE_TIMECOUNTER 270 /* 271 * Increment the time-of-day. The increment is normally just 272 * ``tick''. If the machine is one which has a clock frequency 273 * such that ``hz'' would not divide the second evenly into 274 * milliseconds, a periodic adjustment must be applied. Finally, 275 * if we are still adjusting the time (see adjtime()), 276 * ``tickdelta'' may also be added in. 277 */ 278 279 delta = tick; 280 281 if (tickfix) { 282 tickfixcnt += tickfix; 283 if (tickfixcnt >= tickfixinterval) { 284 delta++; 285 tickfixcnt -= tickfixinterval; 286 } 287 } 288 /* Imprecise 4bsd adjtime() handling */ 289 if (timedelta != 0) { 290 delta += tickdelta; 291 timedelta -= tickdelta; 292 } 293 294 /* 295 * ntp_tick_permanent accumulates the clock correction each 296 * tick. The unit is ns per tick shifted left 32 bits. If we have 297 * accumulated more than 1us, we bump delta in the right 298 * direction. Use a loop to avoid long long div; typicallly 299 * the loops will be executed 0 or 1 iteration. 300 */ 301 if (ntp_tick_permanent != 0) { 302 ntp_tick_acc += ntp_tick_permanent; 303 while (ntp_tick_acc >= (1000LL << 32)) { 304 delta++; 305 ntp_tick_acc -= (1000LL << 32); 306 } 307 while (ntp_tick_acc <= -(1000LL << 32)) { 308 delta--; 309 ntp_tick_acc += (1000LL << 32); 310 } 311 } 312 313 BUMPTIME(&time, delta); 314 BUMPTIME(&mono_time, delta); 315 time_second = time.tv_sec; 316 time_uptime = mono_time.tv_sec; 317 #else 318 tc_ticktock(); 319 #endif 320 321 /* 322 * Update real-time timeout queue. 323 * Process callouts at a very low cpu priority, so we don't keep the 324 * relatively high clock interrupt priority any longer than necessary. 325 */ 326 if (timeout_hardclock_update()) { 327 #ifdef __HAVE_GENERIC_SOFT_INTERRUPTS 328 softintr_schedule(softclock_si); 329 #else 330 setsoftclock(); 331 #endif 332 } 333 } 334 335 /* 336 * Compute number of hz until specified time. Used to 337 * compute the second argument to timeout_add() from an absolute time. 338 */ 339 int 340 hzto(struct timeval *tv) 341 { 342 struct timeval now; 343 unsigned long ticks; 344 long sec, usec; 345 346 /* 347 * If the number of usecs in the whole seconds part of the time 348 * difference fits in a long, then the total number of usecs will 349 * fit in an unsigned long. Compute the total and convert it to 350 * ticks, rounding up and adding 1 to allow for the current tick 351 * to expire. Rounding also depends on unsigned long arithmetic 352 * to avoid overflow. 353 * 354 * Otherwise, if the number of ticks in the whole seconds part of 355 * the time difference fits in a long, then convert the parts to 356 * ticks separately and add, using similar rounding methods and 357 * overflow avoidance. This method would work in the previous 358 * case but it is slightly slower and assumes that hz is integral. 359 * 360 * Otherwise, round the time difference down to the maximum 361 * representable value. 362 * 363 * If ints have 32 bits, then the maximum value for any timeout in 364 * 10ms ticks is 248 days. 365 */ 366 getmicrotime(&now); 367 sec = tv->tv_sec - now.tv_sec; 368 usec = tv->tv_usec - now.tv_usec; 369 if (usec < 0) { 370 sec--; 371 usec += 1000000; 372 } 373 if (sec < 0 || (sec == 0 && usec <= 0)) { 374 ticks = 0; 375 } else if (sec <= LONG_MAX / 1000000) 376 ticks = (sec * 1000000 + (unsigned long)usec + (tick - 1)) 377 / tick + 1; 378 else if (sec <= LONG_MAX / hz) 379 ticks = sec * hz 380 + ((unsigned long)usec + (tick - 1)) / tick + 1; 381 else 382 ticks = LONG_MAX; 383 if (ticks > INT_MAX) 384 ticks = INT_MAX; 385 return ((int)ticks); 386 } 387 388 /* 389 * Compute number of hz in the specified amount of time. 390 */ 391 int 392 tvtohz(struct timeval *tv) 393 { 394 unsigned long ticks; 395 long sec, usec; 396 397 /* 398 * If the number of usecs in the whole seconds part of the time 399 * fits in a long, then the total number of usecs will 400 * fit in an unsigned long. Compute the total and convert it to 401 * ticks, rounding up and adding 1 to allow for the current tick 402 * to expire. Rounding also depends on unsigned long arithmetic 403 * to avoid overflow. 404 * 405 * Otherwise, if the number of ticks in the whole seconds part of 406 * the time fits in a long, then convert the parts to 407 * ticks separately and add, using similar rounding methods and 408 * overflow avoidance. This method would work in the previous 409 * case but it is slightly slower and assumes that hz is integral. 410 * 411 * Otherwise, round the time down to the maximum 412 * representable value. 413 * 414 * If ints have 32 bits, then the maximum value for any timeout in 415 * 10ms ticks is 248 days. 416 */ 417 sec = tv->tv_sec; 418 usec = tv->tv_usec; 419 if (sec < 0 || (sec == 0 && usec <= 0)) 420 ticks = 0; 421 else if (sec <= LONG_MAX / 1000000) 422 ticks = (sec * 1000000 + (unsigned long)usec + (tick - 1)) 423 / tick + 1; 424 else if (sec <= LONG_MAX / hz) 425 ticks = sec * hz 426 + ((unsigned long)usec + (tick - 1)) / tick + 1; 427 else 428 ticks = LONG_MAX; 429 if (ticks > INT_MAX) 430 ticks = INT_MAX; 431 return ((int)ticks); 432 } 433 434 /* 435 * Start profiling on a process. 436 * 437 * Kernel profiling passes proc0 which never exits and hence 438 * keeps the profile clock running constantly. 439 */ 440 void 441 startprofclock(struct proc *p) 442 { 443 int s; 444 445 if ((p->p_flag & P_PROFIL) == 0) { 446 atomic_setbits_int(&p->p_flag, P_PROFIL); 447 if (++profprocs == 1 && stathz != 0) { 448 s = splstatclock(); 449 psdiv = pscnt = psratio; 450 setstatclockrate(profhz); 451 splx(s); 452 } 453 } 454 } 455 456 /* 457 * Stop profiling on a process. 458 */ 459 void 460 stopprofclock(struct proc *p) 461 { 462 int s; 463 464 if (p->p_flag & P_PROFIL) { 465 atomic_clearbits_int(&p->p_flag, P_PROFIL); 466 if (--profprocs == 0 && stathz != 0) { 467 s = splstatclock(); 468 psdiv = pscnt = 1; 469 setstatclockrate(stathz); 470 splx(s); 471 } 472 } 473 } 474 475 /* 476 * Statistics clock. Grab profile sample, and if divider reaches 0, 477 * do process and kernel statistics. 478 */ 479 void 480 statclock(struct clockframe *frame) 481 { 482 #ifdef GPROF 483 struct gmonparam *g; 484 u_long i; 485 #endif 486 struct cpu_info *ci = curcpu(); 487 struct schedstate_percpu *spc = &ci->ci_schedstate; 488 struct proc *p = curproc; 489 490 /* 491 * Notice changes in divisor frequency, and adjust clock 492 * frequency accordingly. 493 */ 494 if (spc->spc_psdiv != psdiv) { 495 spc->spc_psdiv = psdiv; 496 spc->spc_pscnt = psdiv; 497 if (psdiv == 1) { 498 setstatclockrate(stathz); 499 } else { 500 setstatclockrate(profhz); 501 } 502 } 503 504 if (CLKF_USERMODE(frame)) { 505 if (p->p_flag & P_PROFIL) 506 addupc_intr(p, CLKF_PC(frame)); 507 if (--spc->spc_pscnt > 0) 508 return; 509 /* 510 * Came from user mode; CPU was in user state. 511 * If this process is being profiled record the tick. 512 */ 513 p->p_uticks++; 514 if (p->p_nice > NZERO) 515 spc->spc_cp_time[CP_NICE]++; 516 else 517 spc->spc_cp_time[CP_USER]++; 518 } else { 519 #ifdef GPROF 520 /* 521 * Kernel statistics are just like addupc_intr, only easier. 522 */ 523 g = &_gmonparam; 524 if (g->state == GMON_PROF_ON) { 525 i = CLKF_PC(frame) - g->lowpc; 526 if (i < g->textsize) { 527 i /= HISTFRACTION * sizeof(*g->kcount); 528 g->kcount[i]++; 529 } 530 } 531 #endif 532 #if defined(PROC_PC) 533 if (p != NULL && p->p_flag & P_PROFIL) 534 addupc_intr(p, PROC_PC(p)); 535 #endif 536 if (--spc->spc_pscnt > 0) 537 return; 538 /* 539 * Came from kernel mode, so we were: 540 * - handling an interrupt, 541 * - doing syscall or trap work on behalf of the current 542 * user process, or 543 * - spinning in the idle loop. 544 * Whichever it is, charge the time as appropriate. 545 * Note that we charge interrupts to the current process, 546 * regardless of whether they are ``for'' that process, 547 * so that we know how much of its real time was spent 548 * in ``non-process'' (i.e., interrupt) work. 549 */ 550 if (CLKF_INTR(frame)) { 551 if (p != NULL) 552 p->p_iticks++; 553 spc->spc_cp_time[CP_INTR]++; 554 } else if (p != NULL && p != spc->spc_idleproc) { 555 p->p_sticks++; 556 spc->spc_cp_time[CP_SYS]++; 557 } else 558 spc->spc_cp_time[CP_IDLE]++; 559 } 560 spc->spc_pscnt = psdiv; 561 562 if (p != NULL) { 563 p->p_cpticks++; 564 /* 565 * If no schedclock is provided, call it here at ~~12-25 Hz; 566 * ~~16 Hz is best 567 */ 568 if (schedhz == 0) { 569 if ((++curcpu()->ci_schedstate.spc_schedticks & 3) == 570 0) 571 schedclock(p); 572 } 573 } 574 } 575 576 /* 577 * Return information about system clocks. 578 */ 579 int 580 sysctl_clockrate(char *where, size_t *sizep, void *newp) 581 { 582 struct clockinfo clkinfo; 583 584 /* 585 * Construct clockinfo structure. 586 */ 587 clkinfo.tick = tick; 588 clkinfo.tickadj = tickadj; 589 clkinfo.hz = hz; 590 clkinfo.profhz = profhz; 591 clkinfo.stathz = stathz ? stathz : hz; 592 return (sysctl_rdstruct(where, sizep, newp, &clkinfo, sizeof(clkinfo))); 593 } 594 595 #ifndef __HAVE_TIMECOUNTER 596 /* 597 * Placeholders until everyone uses the timecounters code. 598 * Won't improve anything except maybe removing a bunch of bugs in fixed code. 599 */ 600 601 void 602 getmicrotime(struct timeval *tvp) 603 { 604 int s; 605 606 s = splhigh(); 607 *tvp = time; 608 splx(s); 609 } 610 611 void 612 nanotime(struct timespec *tsp) 613 { 614 struct timeval tv; 615 616 microtime(&tv); 617 TIMEVAL_TO_TIMESPEC(&tv, tsp); 618 } 619 620 void 621 getnanotime(struct timespec *tsp) 622 { 623 struct timeval tv; 624 625 getmicrotime(&tv); 626 TIMEVAL_TO_TIMESPEC(&tv, tsp); 627 } 628 629 void 630 nanouptime(struct timespec *tsp) 631 { 632 struct timeval tv; 633 634 microuptime(&tv); 635 TIMEVAL_TO_TIMESPEC(&tv, tsp); 636 } 637 638 639 void 640 getnanouptime(struct timespec *tsp) 641 { 642 struct timeval tv; 643 644 getmicrouptime(&tv); 645 TIMEVAL_TO_TIMESPEC(&tv, tsp); 646 } 647 648 void 649 microuptime(struct timeval *tvp) 650 { 651 struct timeval tv; 652 653 microtime(&tv); 654 timersub(&tv, &boottime, tvp); 655 } 656 657 void 658 getmicrouptime(struct timeval *tvp) 659 { 660 int s; 661 662 s = splhigh(); 663 *tvp = mono_time; 664 splx(s); 665 } 666 #endif /* __HAVE_TIMECOUNTER */ 667