1 /* $OpenBSD: kern_clock.c,v 1.87 2014/09/15 19:08:21 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/timeout.h> 43 #include <sys/kernel.h> 44 #include <sys/limits.h> 45 #include <sys/proc.h> 46 #include <sys/user.h> 47 #include <sys/resourcevar.h> 48 #include <sys/signalvar.h> 49 #include <sys/sysctl.h> 50 #include <sys/sched.h> 51 #include <sys/timetc.h> 52 53 54 #ifdef GPROF 55 #include <sys/gmon.h> 56 #endif 57 58 /* 59 * Clock handling routines. 60 * 61 * This code is written to operate with two timers that run independently of 62 * each other. The main clock, running hz times per second, is used to keep 63 * track of real time. The second timer handles kernel and user profiling, 64 * and does resource use estimation. If the second timer is programmable, 65 * it is randomized to avoid aliasing between the two clocks. For example, 66 * the randomization prevents an adversary from always giving up the cpu 67 * just before its quantum expires. Otherwise, it would never accumulate 68 * cpu ticks. The mean frequency of the second timer is stathz. 69 * 70 * If no second timer exists, stathz will be zero; in this case we drive 71 * profiling and statistics off the main clock. This WILL NOT be accurate; 72 * do not do it unless absolutely necessary. 73 * 74 * The statistics clock may (or may not) be run at a higher rate while 75 * profiling. This profile clock runs at profhz. We require that profhz 76 * be an integral multiple of stathz. 77 * 78 * If the statistics clock is running fast, it must be divided by the ratio 79 * profhz/stathz for statistics. (For profiling, every tick counts.) 80 */ 81 82 /* 83 * Bump a timeval by a small number of usec's. 84 */ 85 #define BUMPTIME(t, usec) { \ 86 volatile struct timeval *tp = (t); \ 87 long us; \ 88 \ 89 tp->tv_usec = us = tp->tv_usec + (usec); \ 90 if (us >= 1000000) { \ 91 tp->tv_usec = us - 1000000; \ 92 tp->tv_sec++; \ 93 } \ 94 } 95 96 int stathz; 97 int schedhz; 98 int profhz; 99 int profprocs; 100 int ticks; 101 static int psdiv, pscnt; /* prof => stat divider */ 102 int psratio; /* ratio: prof / stat */ 103 104 void *softclock_si; 105 106 /* 107 * Initialize clock frequencies and start both clocks running. 108 */ 109 void 110 initclocks(void) 111 { 112 int i; 113 114 softclock_si = softintr_establish(IPL_SOFTCLOCK, softclock, NULL); 115 if (softclock_si == NULL) 116 panic("initclocks: unable to register softclock intr"); 117 118 /* 119 * Set divisors to 1 (normal case) and let the machine-specific 120 * code do its bit. 121 */ 122 psdiv = pscnt = 1; 123 cpu_initclocks(); 124 125 /* 126 * Compute profhz/stathz, and fix profhz if needed. 127 */ 128 i = stathz ? stathz : hz; 129 if (profhz == 0) 130 profhz = i; 131 psratio = profhz / i; 132 133 /* For very large HZ, ensure that division by 0 does not occur later */ 134 if (tickadj == 0) 135 tickadj = 1; 136 137 inittimecounter(); 138 } 139 140 /* 141 * hardclock does the accounting needed for ITIMER_PROF and ITIMER_VIRTUAL. 142 * We don't want to send signals with psignal from hardclock because it makes 143 * MULTIPROCESSOR locking very complicated. Instead, to use an idea from 144 * FreeBSD, we set a flag on the thread and when it goes to return to 145 * userspace it signals itself. 146 */ 147 148 /* 149 * The real-time timer, interrupting hz times per second. 150 */ 151 void 152 hardclock(struct clockframe *frame) 153 { 154 struct proc *p; 155 struct cpu_info *ci = curcpu(); 156 157 p = curproc; 158 if (p && ((p->p_flag & (P_SYSTEM | P_WEXIT)) == 0)) { 159 struct process *pr = p->p_p; 160 161 /* 162 * Run current process's virtual and profile time, as needed. 163 */ 164 if (CLKF_USERMODE(frame) && 165 timerisset(&pr->ps_timer[ITIMER_VIRTUAL].it_value) && 166 itimerdecr(&pr->ps_timer[ITIMER_VIRTUAL], tick) == 0) { 167 atomic_setbits_int(&p->p_flag, P_ALRMPEND); 168 need_proftick(p); 169 } 170 if (timerisset(&pr->ps_timer[ITIMER_PROF].it_value) && 171 itimerdecr(&pr->ps_timer[ITIMER_PROF], tick) == 0) { 172 atomic_setbits_int(&p->p_flag, P_PROFPEND); 173 need_proftick(p); 174 } 175 } 176 177 /* 178 * If no separate statistics clock is available, run it from here. 179 */ 180 if (stathz == 0) 181 statclock(frame); 182 183 if (--ci->ci_schedstate.spc_rrticks <= 0) 184 roundrobin(ci); 185 186 /* 187 * If we are not the primary CPU, we're not allowed to do 188 * any more work. 189 */ 190 if (CPU_IS_PRIMARY(ci) == 0) 191 return; 192 193 tc_ticktock(); 194 195 /* 196 * Update real-time timeout queue. 197 * Process callouts at a very low cpu priority, so we don't keep the 198 * relatively high clock interrupt priority any longer than necessary. 199 */ 200 if (timeout_hardclock_update()) 201 softintr_schedule(softclock_si); 202 } 203 204 /* 205 * Compute number of hz until specified time. Used to 206 * compute the second argument to timeout_add() from an absolute time. 207 */ 208 int 209 hzto(const struct timeval *tv) 210 { 211 struct timeval now; 212 unsigned long nticks; 213 long sec, usec; 214 215 /* 216 * If the number of usecs in the whole seconds part of the time 217 * difference fits in a long, then the total number of usecs will 218 * fit in an unsigned long. Compute the total and convert it to 219 * ticks, rounding up and adding 1 to allow for the current tick 220 * to expire. Rounding also depends on unsigned long arithmetic 221 * to avoid overflow. 222 * 223 * Otherwise, if the number of ticks in the whole seconds part of 224 * the time difference fits in a long, then convert the parts to 225 * ticks separately and add, using similar rounding methods and 226 * overflow avoidance. This method would work in the previous 227 * case but it is slightly slower and assumes that hz is integral. 228 * 229 * Otherwise, round the time difference down to the maximum 230 * representable value. 231 * 232 * If ints have 32 bits, then the maximum value for any timeout in 233 * 10ms ticks is 248 days. 234 */ 235 getmicrotime(&now); 236 sec = tv->tv_sec - now.tv_sec; 237 usec = tv->tv_usec - now.tv_usec; 238 if (usec < 0) { 239 sec--; 240 usec += 1000000; 241 } 242 if (sec < 0 || (sec == 0 && usec <= 0)) { 243 nticks = 0; 244 } else if (sec <= LONG_MAX / 1000000) 245 nticks = (sec * 1000000 + (unsigned long)usec + (tick - 1)) 246 / tick + 1; 247 else if (sec <= LONG_MAX / hz) 248 nticks = sec * hz 249 + ((unsigned long)usec + (tick - 1)) / tick + 1; 250 else 251 nticks = LONG_MAX; 252 if (nticks > INT_MAX) 253 nticks = INT_MAX; 254 return ((int)nticks); 255 } 256 257 /* 258 * Compute number of hz in the specified amount of time. 259 */ 260 int 261 tvtohz(const struct timeval *tv) 262 { 263 unsigned long nticks; 264 time_t sec; 265 long usec; 266 267 /* 268 * If the number of usecs in the whole seconds part of the time 269 * fits in a long, then the total number of usecs will 270 * fit in an unsigned long. Compute the total and convert it to 271 * ticks, rounding up and adding 1 to allow for the current tick 272 * to expire. Rounding also depends on unsigned long arithmetic 273 * to avoid overflow. 274 * 275 * Otherwise, if the number of ticks in the whole seconds part of 276 * the time fits in a long, then convert the parts to 277 * ticks separately and add, using similar rounding methods and 278 * overflow avoidance. This method would work in the previous 279 * case but it is slightly slower and assumes that hz is integral. 280 * 281 * Otherwise, round the time down to the maximum 282 * representable value. 283 * 284 * If ints have 32 bits, then the maximum value for any timeout in 285 * 10ms ticks is 248 days. 286 */ 287 sec = tv->tv_sec; 288 usec = tv->tv_usec; 289 if (sec < 0 || (sec == 0 && usec <= 0)) 290 nticks = 0; 291 else if (sec <= LONG_MAX / 1000000) 292 nticks = (sec * 1000000 + (unsigned long)usec + (tick - 1)) 293 / tick + 1; 294 else if (sec <= LONG_MAX / hz) 295 nticks = sec * hz 296 + ((unsigned long)usec + (tick - 1)) / tick + 1; 297 else 298 nticks = LONG_MAX; 299 if (nticks > INT_MAX) 300 nticks = INT_MAX; 301 return ((int)nticks); 302 } 303 304 int 305 tstohz(const struct timespec *ts) 306 { 307 struct timeval tv; 308 TIMESPEC_TO_TIMEVAL(&tv, ts); 309 310 /* Round up. */ 311 if ((ts->tv_nsec % 1000) != 0) { 312 tv.tv_usec += 1; 313 if (tv.tv_usec >= 1000000) { 314 tv.tv_usec -= 1000000; 315 tv.tv_sec += 1; 316 } 317 } 318 319 return (tvtohz(&tv)); 320 } 321 322 /* 323 * Start profiling on a process. 324 * 325 * Kernel profiling passes proc0 which never exits and hence 326 * keeps the profile clock running constantly. 327 */ 328 void 329 startprofclock(struct process *pr) 330 { 331 int s; 332 333 if ((pr->ps_flags & PS_PROFIL) == 0) { 334 atomic_setbits_int(&pr->ps_flags, PS_PROFIL); 335 if (++profprocs == 1 && stathz != 0) { 336 s = splstatclock(); 337 psdiv = pscnt = psratio; 338 setstatclockrate(profhz); 339 splx(s); 340 } 341 } 342 } 343 344 /* 345 * Stop profiling on a process. 346 */ 347 void 348 stopprofclock(struct process *pr) 349 { 350 int s; 351 352 if (pr->ps_flags & PS_PROFIL) { 353 atomic_clearbits_int(&pr->ps_flags, PS_PROFIL); 354 if (--profprocs == 0 && stathz != 0) { 355 s = splstatclock(); 356 psdiv = pscnt = 1; 357 setstatclockrate(stathz); 358 splx(s); 359 } 360 } 361 } 362 363 /* 364 * Statistics clock. Grab profile sample, and if divider reaches 0, 365 * do process and kernel statistics. 366 */ 367 void 368 statclock(struct clockframe *frame) 369 { 370 #ifdef GPROF 371 struct gmonparam *g; 372 u_long i; 373 #endif 374 struct cpu_info *ci = curcpu(); 375 struct schedstate_percpu *spc = &ci->ci_schedstate; 376 struct proc *p = curproc; 377 struct process *pr; 378 379 /* 380 * Notice changes in divisor frequency, and adjust clock 381 * frequency accordingly. 382 */ 383 if (spc->spc_psdiv != psdiv) { 384 spc->spc_psdiv = psdiv; 385 spc->spc_pscnt = psdiv; 386 if (psdiv == 1) { 387 setstatclockrate(stathz); 388 } else { 389 setstatclockrate(profhz); 390 } 391 } 392 393 if (CLKF_USERMODE(frame)) { 394 pr = p->p_p; 395 if (pr->ps_flags & PS_PROFIL) 396 addupc_intr(p, CLKF_PC(frame)); 397 if (--spc->spc_pscnt > 0) 398 return; 399 /* 400 * Came from user mode; CPU was in user state. 401 * If this process is being profiled record the tick. 402 */ 403 p->p_uticks++; 404 if (pr->ps_nice > NZERO) 405 spc->spc_cp_time[CP_NICE]++; 406 else 407 spc->spc_cp_time[CP_USER]++; 408 } else { 409 #ifdef GPROF 410 /* 411 * Kernel statistics are just like addupc_intr, only easier. 412 */ 413 g = ci->ci_gmon; 414 if (g != NULL && g->state == GMON_PROF_ON) { 415 i = CLKF_PC(frame) - g->lowpc; 416 if (i < g->textsize) { 417 i /= HISTFRACTION * sizeof(*g->kcount); 418 g->kcount[i]++; 419 } 420 } 421 #endif 422 #if defined(PROC_PC) 423 if (p != NULL && p->p_p->ps_flags & PS_PROFIL) 424 addupc_intr(p, PROC_PC(p)); 425 #endif 426 if (--spc->spc_pscnt > 0) 427 return; 428 /* 429 * Came from kernel mode, so we were: 430 * - handling an interrupt, 431 * - doing syscall or trap work on behalf of the current 432 * user process, or 433 * - spinning in the idle loop. 434 * Whichever it is, charge the time as appropriate. 435 * Note that we charge interrupts to the current process, 436 * regardless of whether they are ``for'' that process, 437 * so that we know how much of its real time was spent 438 * in ``non-process'' (i.e., interrupt) work. 439 */ 440 if (CLKF_INTR(frame)) { 441 if (p != NULL) 442 p->p_iticks++; 443 spc->spc_cp_time[CP_INTR]++; 444 } else if (p != NULL && p != spc->spc_idleproc) { 445 p->p_sticks++; 446 spc->spc_cp_time[CP_SYS]++; 447 } else 448 spc->spc_cp_time[CP_IDLE]++; 449 } 450 spc->spc_pscnt = psdiv; 451 452 if (p != NULL) { 453 p->p_cpticks++; 454 /* 455 * If no schedclock is provided, call it here at ~~12-25 Hz; 456 * ~~16 Hz is best 457 */ 458 if (schedhz == 0) { 459 if ((++curcpu()->ci_schedstate.spc_schedticks & 3) == 460 0) 461 schedclock(p); 462 } 463 } 464 } 465 466 /* 467 * Return information about system clocks. 468 */ 469 int 470 sysctl_clockrate(char *where, size_t *sizep, void *newp) 471 { 472 struct clockinfo clkinfo; 473 474 /* 475 * Construct clockinfo structure. 476 */ 477 clkinfo.tick = tick; 478 clkinfo.tickadj = tickadj; 479 clkinfo.hz = hz; 480 clkinfo.profhz = profhz; 481 clkinfo.stathz = stathz ? stathz : hz; 482 return (sysctl_rdstruct(where, sizep, newp, &clkinfo, sizeof(clkinfo))); 483 } 484