1 /* $OpenBSD: kern_clock.c,v 1.86 2014/09/04 19:14:47 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 <sys/sysctl.h> 51 #include <sys/sched.h> 52 #include <sys/timetc.h> 53 54 55 #ifdef GPROF 56 #include <sys/gmon.h> 57 #endif 58 59 /* 60 * Clock handling routines. 61 * 62 * This code is written to operate with two timers that run independently of 63 * each other. The main clock, running hz times per second, is used to keep 64 * track of real time. The second timer handles kernel and user profiling, 65 * and does resource use estimation. If the second timer is programmable, 66 * it is randomized to avoid aliasing between the two clocks. For example, 67 * the randomization prevents an adversary from always giving up the cpu 68 * just before its quantum expires. Otherwise, it would never accumulate 69 * cpu ticks. The mean frequency of the second timer is stathz. 70 * 71 * If no second timer exists, stathz will be zero; in this case we drive 72 * profiling and statistics off the main clock. This WILL NOT be accurate; 73 * do not do it unless absolutely necessary. 74 * 75 * The statistics clock may (or may not) be run at a higher rate while 76 * profiling. This profile clock runs at profhz. We require that profhz 77 * be an integral multiple of stathz. 78 * 79 * If the statistics clock is running fast, it must be divided by the ratio 80 * profhz/stathz for statistics. (For profiling, every tick counts.) 81 */ 82 83 /* 84 * Bump a timeval by a small number of usec's. 85 */ 86 #define BUMPTIME(t, usec) { \ 87 volatile struct timeval *tp = (t); \ 88 long us; \ 89 \ 90 tp->tv_usec = us = tp->tv_usec + (usec); \ 91 if (us >= 1000000) { \ 92 tp->tv_usec = us - 1000000; \ 93 tp->tv_sec++; \ 94 } \ 95 } 96 97 int stathz; 98 int schedhz; 99 int profhz; 100 int profprocs; 101 int ticks; 102 static int psdiv, pscnt; /* prof => stat divider */ 103 int psratio; /* ratio: prof / stat */ 104 105 void *softclock_si; 106 107 /* 108 * Initialize clock frequencies and start both clocks running. 109 */ 110 void 111 initclocks(void) 112 { 113 int i; 114 115 softclock_si = softintr_establish(IPL_SOFTCLOCK, softclock, NULL); 116 if (softclock_si == NULL) 117 panic("initclocks: unable to register softclock intr"); 118 119 /* 120 * Set divisors to 1 (normal case) and let the machine-specific 121 * code do its bit. 122 */ 123 psdiv = pscnt = 1; 124 cpu_initclocks(); 125 126 /* 127 * Compute profhz/stathz, and fix profhz if needed. 128 */ 129 i = stathz ? stathz : hz; 130 if (profhz == 0) 131 profhz = i; 132 psratio = profhz / i; 133 134 /* For very large HZ, ensure that division by 0 does not occur later */ 135 if (tickadj == 0) 136 tickadj = 1; 137 138 inittimecounter(); 139 } 140 141 /* 142 * hardclock does the accounting needed for ITIMER_PROF and ITIMER_VIRTUAL. 143 * We don't want to send signals with psignal from hardclock because it makes 144 * MULTIPROCESSOR locking very complicated. Instead, to use an idea from 145 * FreeBSD, we set a flag on the thread and when it goes to return to 146 * userspace it signals itself. 147 */ 148 149 /* 150 * The real-time timer, interrupting hz times per second. 151 */ 152 void 153 hardclock(struct clockframe *frame) 154 { 155 struct proc *p; 156 struct cpu_info *ci = curcpu(); 157 158 p = curproc; 159 if (p && ((p->p_flag & (P_SYSTEM | P_WEXIT)) == 0)) { 160 struct process *pr = p->p_p; 161 162 /* 163 * Run current process's virtual and profile time, as needed. 164 */ 165 if (CLKF_USERMODE(frame) && 166 timerisset(&pr->ps_timer[ITIMER_VIRTUAL].it_value) && 167 itimerdecr(&pr->ps_timer[ITIMER_VIRTUAL], tick) == 0) { 168 atomic_setbits_int(&p->p_flag, P_ALRMPEND); 169 need_proftick(p); 170 } 171 if (timerisset(&pr->ps_timer[ITIMER_PROF].it_value) && 172 itimerdecr(&pr->ps_timer[ITIMER_PROF], tick) == 0) { 173 atomic_setbits_int(&p->p_flag, P_PROFPEND); 174 need_proftick(p); 175 } 176 } 177 178 /* 179 * If no separate statistics clock is available, run it from here. 180 */ 181 if (stathz == 0) 182 statclock(frame); 183 184 if (--ci->ci_schedstate.spc_rrticks <= 0) 185 roundrobin(ci); 186 187 /* 188 * If we are not the primary CPU, we're not allowed to do 189 * any more work. 190 */ 191 if (CPU_IS_PRIMARY(ci) == 0) 192 return; 193 194 tc_ticktock(); 195 196 /* 197 * Update real-time timeout queue. 198 * Process callouts at a very low cpu priority, so we don't keep the 199 * relatively high clock interrupt priority any longer than necessary. 200 */ 201 if (timeout_hardclock_update()) 202 softintr_schedule(softclock_si); 203 } 204 205 /* 206 * Compute number of hz until specified time. Used to 207 * compute the second argument to timeout_add() from an absolute time. 208 */ 209 int 210 hzto(const struct timeval *tv) 211 { 212 struct timeval now; 213 unsigned long nticks; 214 long sec, usec; 215 216 /* 217 * If the number of usecs in the whole seconds part of the time 218 * difference fits in a long, then the total number of usecs will 219 * fit in an unsigned long. Compute the total and convert it to 220 * ticks, rounding up and adding 1 to allow for the current tick 221 * to expire. Rounding also depends on unsigned long arithmetic 222 * to avoid overflow. 223 * 224 * Otherwise, if the number of ticks in the whole seconds part of 225 * the time difference fits in a long, then convert the parts to 226 * ticks separately and add, using similar rounding methods and 227 * overflow avoidance. This method would work in the previous 228 * case but it is slightly slower and assumes that hz is integral. 229 * 230 * Otherwise, round the time difference down to the maximum 231 * representable value. 232 * 233 * If ints have 32 bits, then the maximum value for any timeout in 234 * 10ms ticks is 248 days. 235 */ 236 getmicrotime(&now); 237 sec = tv->tv_sec - now.tv_sec; 238 usec = tv->tv_usec - now.tv_usec; 239 if (usec < 0) { 240 sec--; 241 usec += 1000000; 242 } 243 if (sec < 0 || (sec == 0 && usec <= 0)) { 244 nticks = 0; 245 } else if (sec <= LONG_MAX / 1000000) 246 nticks = (sec * 1000000 + (unsigned long)usec + (tick - 1)) 247 / tick + 1; 248 else if (sec <= LONG_MAX / hz) 249 nticks = sec * hz 250 + ((unsigned long)usec + (tick - 1)) / tick + 1; 251 else 252 nticks = LONG_MAX; 253 if (nticks > INT_MAX) 254 nticks = INT_MAX; 255 return ((int)nticks); 256 } 257 258 /* 259 * Compute number of hz in the specified amount of time. 260 */ 261 int 262 tvtohz(const struct timeval *tv) 263 { 264 unsigned long nticks; 265 time_t sec; 266 long usec; 267 268 /* 269 * If the number of usecs in the whole seconds part of the time 270 * fits in a long, then the total number of usecs will 271 * fit in an unsigned long. Compute the total and convert it to 272 * ticks, rounding up and adding 1 to allow for the current tick 273 * to expire. Rounding also depends on unsigned long arithmetic 274 * to avoid overflow. 275 * 276 * Otherwise, if the number of ticks in the whole seconds part of 277 * the time fits in a long, then convert the parts to 278 * ticks separately and add, using similar rounding methods and 279 * overflow avoidance. This method would work in the previous 280 * case but it is slightly slower and assumes that hz is integral. 281 * 282 * Otherwise, round the time down to the maximum 283 * representable value. 284 * 285 * If ints have 32 bits, then the maximum value for any timeout in 286 * 10ms ticks is 248 days. 287 */ 288 sec = tv->tv_sec; 289 usec = tv->tv_usec; 290 if (sec < 0 || (sec == 0 && usec <= 0)) 291 nticks = 0; 292 else if (sec <= LONG_MAX / 1000000) 293 nticks = (sec * 1000000 + (unsigned long)usec + (tick - 1)) 294 / tick + 1; 295 else if (sec <= LONG_MAX / hz) 296 nticks = sec * hz 297 + ((unsigned long)usec + (tick - 1)) / tick + 1; 298 else 299 nticks = LONG_MAX; 300 if (nticks > INT_MAX) 301 nticks = INT_MAX; 302 return ((int)nticks); 303 } 304 305 int 306 tstohz(const struct timespec *ts) 307 { 308 struct timeval tv; 309 TIMESPEC_TO_TIMEVAL(&tv, ts); 310 311 /* Round up. */ 312 if ((ts->tv_nsec % 1000) != 0) { 313 tv.tv_usec += 1; 314 if (tv.tv_usec >= 1000000) { 315 tv.tv_usec -= 1000000; 316 tv.tv_sec += 1; 317 } 318 } 319 320 return (tvtohz(&tv)); 321 } 322 323 /* 324 * Start profiling on a process. 325 * 326 * Kernel profiling passes proc0 which never exits and hence 327 * keeps the profile clock running constantly. 328 */ 329 void 330 startprofclock(struct process *pr) 331 { 332 int s; 333 334 if ((pr->ps_flags & PS_PROFIL) == 0) { 335 atomic_setbits_int(&pr->ps_flags, PS_PROFIL); 336 if (++profprocs == 1 && stathz != 0) { 337 s = splstatclock(); 338 psdiv = pscnt = psratio; 339 setstatclockrate(profhz); 340 splx(s); 341 } 342 } 343 } 344 345 /* 346 * Stop profiling on a process. 347 */ 348 void 349 stopprofclock(struct process *pr) 350 { 351 int s; 352 353 if (pr->ps_flags & PS_PROFIL) { 354 atomic_clearbits_int(&pr->ps_flags, PS_PROFIL); 355 if (--profprocs == 0 && stathz != 0) { 356 s = splstatclock(); 357 psdiv = pscnt = 1; 358 setstatclockrate(stathz); 359 splx(s); 360 } 361 } 362 } 363 364 /* 365 * Statistics clock. Grab profile sample, and if divider reaches 0, 366 * do process and kernel statistics. 367 */ 368 void 369 statclock(struct clockframe *frame) 370 { 371 #ifdef GPROF 372 struct gmonparam *g; 373 u_long i; 374 #endif 375 struct cpu_info *ci = curcpu(); 376 struct schedstate_percpu *spc = &ci->ci_schedstate; 377 struct proc *p = curproc; 378 struct process *pr; 379 380 /* 381 * Notice changes in divisor frequency, and adjust clock 382 * frequency accordingly. 383 */ 384 if (spc->spc_psdiv != psdiv) { 385 spc->spc_psdiv = psdiv; 386 spc->spc_pscnt = psdiv; 387 if (psdiv == 1) { 388 setstatclockrate(stathz); 389 } else { 390 setstatclockrate(profhz); 391 } 392 } 393 394 if (CLKF_USERMODE(frame)) { 395 pr = p->p_p; 396 if (pr->ps_flags & PS_PROFIL) 397 addupc_intr(p, CLKF_PC(frame)); 398 if (--spc->spc_pscnt > 0) 399 return; 400 /* 401 * Came from user mode; CPU was in user state. 402 * If this process is being profiled record the tick. 403 */ 404 p->p_uticks++; 405 if (pr->ps_nice > NZERO) 406 spc->spc_cp_time[CP_NICE]++; 407 else 408 spc->spc_cp_time[CP_USER]++; 409 } else { 410 #ifdef GPROF 411 /* 412 * Kernel statistics are just like addupc_intr, only easier. 413 */ 414 g = ci->ci_gmon; 415 if (g != NULL && g->state == GMON_PROF_ON) { 416 i = CLKF_PC(frame) - g->lowpc; 417 if (i < g->textsize) { 418 i /= HISTFRACTION * sizeof(*g->kcount); 419 g->kcount[i]++; 420 } 421 } 422 #endif 423 #if defined(PROC_PC) 424 if (p != NULL && p->p_p->ps_flags & PS_PROFIL) 425 addupc_intr(p, PROC_PC(p)); 426 #endif 427 if (--spc->spc_pscnt > 0) 428 return; 429 /* 430 * Came from kernel mode, so we were: 431 * - handling an interrupt, 432 * - doing syscall or trap work on behalf of the current 433 * user process, or 434 * - spinning in the idle loop. 435 * Whichever it is, charge the time as appropriate. 436 * Note that we charge interrupts to the current process, 437 * regardless of whether they are ``for'' that process, 438 * so that we know how much of its real time was spent 439 * in ``non-process'' (i.e., interrupt) work. 440 */ 441 if (CLKF_INTR(frame)) { 442 if (p != NULL) 443 p->p_iticks++; 444 spc->spc_cp_time[CP_INTR]++; 445 } else if (p != NULL && p != spc->spc_idleproc) { 446 p->p_sticks++; 447 spc->spc_cp_time[CP_SYS]++; 448 } else 449 spc->spc_cp_time[CP_IDLE]++; 450 } 451 spc->spc_pscnt = psdiv; 452 453 if (p != NULL) { 454 p->p_cpticks++; 455 /* 456 * If no schedclock is provided, call it here at ~~12-25 Hz; 457 * ~~16 Hz is best 458 */ 459 if (schedhz == 0) { 460 if ((++curcpu()->ci_schedstate.spc_schedticks & 3) == 461 0) 462 schedclock(p); 463 } 464 } 465 } 466 467 /* 468 * Return information about system clocks. 469 */ 470 int 471 sysctl_clockrate(char *where, size_t *sizep, void *newp) 472 { 473 struct clockinfo clkinfo; 474 475 /* 476 * Construct clockinfo structure. 477 */ 478 clkinfo.tick = tick; 479 clkinfo.tickadj = tickadj; 480 clkinfo.hz = hz; 481 clkinfo.profhz = profhz; 482 clkinfo.stathz = stathz ? stathz : hz; 483 return (sysctl_rdstruct(where, sizep, newp, &clkinfo, sizeof(clkinfo))); 484 } 485