1 /* $OpenBSD: kern_clock.c,v 1.93 2017/07/22 14:33:45 kettenis 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 #if defined(GPROF) || defined(DDBPROF) 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 volatile unsigned long jiffies; /* XXX Linux API for drm(4) */ 107 108 /* 109 * Initialize clock frequencies and start both clocks running. 110 */ 111 void 112 initclocks(void) 113 { 114 int i; 115 116 softclock_si = softintr_establish(IPL_SOFTCLOCK, softclock, NULL); 117 if (softclock_si == NULL) 118 panic("initclocks: unable to register softclock intr"); 119 120 ticks = INT_MAX - (15 * 60 * hz); 121 jiffies = ULONG_MAX - (10 * 60 * hz); 122 123 /* 124 * Set divisors to 1 (normal case) and let the machine-specific 125 * code do its bit. 126 */ 127 psdiv = pscnt = 1; 128 cpu_initclocks(); 129 130 /* 131 * Compute profhz/stathz, and fix profhz if needed. 132 */ 133 i = stathz ? stathz : hz; 134 if (profhz == 0) 135 profhz = i; 136 psratio = profhz / i; 137 138 /* For very large HZ, ensure that division by 0 does not occur later */ 139 if (tickadj == 0) 140 tickadj = 1; 141 142 inittimecounter(); 143 } 144 145 /* 146 * hardclock does the accounting needed for ITIMER_PROF and ITIMER_VIRTUAL. 147 * We don't want to send signals with psignal from hardclock because it makes 148 * MULTIPROCESSOR locking very complicated. Instead, to use an idea from 149 * FreeBSD, we set a flag on the thread and when it goes to return to 150 * userspace it signals itself. 151 */ 152 153 /* 154 * The real-time timer, interrupting hz times per second. 155 */ 156 void 157 hardclock(struct clockframe *frame) 158 { 159 struct proc *p; 160 struct cpu_info *ci = curcpu(); 161 162 p = curproc; 163 if (p && ((p->p_flag & (P_SYSTEM | P_WEXIT)) == 0)) { 164 struct process *pr = p->p_p; 165 166 /* 167 * Run current process's virtual and profile time, as needed. 168 */ 169 if (CLKF_USERMODE(frame) && 170 timerisset(&pr->ps_timer[ITIMER_VIRTUAL].it_value) && 171 itimerdecr(&pr->ps_timer[ITIMER_VIRTUAL], tick) == 0) { 172 atomic_setbits_int(&p->p_flag, P_ALRMPEND); 173 need_proftick(p); 174 } 175 if (timerisset(&pr->ps_timer[ITIMER_PROF].it_value) && 176 itimerdecr(&pr->ps_timer[ITIMER_PROF], tick) == 0) { 177 atomic_setbits_int(&p->p_flag, P_PROFPEND); 178 need_proftick(p); 179 } 180 } 181 182 /* 183 * If no separate statistics clock is available, run it from here. 184 */ 185 if (stathz == 0) 186 statclock(frame); 187 188 if (--ci->ci_schedstate.spc_rrticks <= 0) 189 roundrobin(ci); 190 191 /* 192 * If we are not the primary CPU, we're not allowed to do 193 * any more work. 194 */ 195 if (CPU_IS_PRIMARY(ci) == 0) 196 return; 197 198 tc_ticktock(); 199 ticks++; 200 jiffies++; 201 202 /* 203 * Update real-time timeout queue. 204 * Process callouts at a very low cpu priority, so we don't keep the 205 * relatively high clock interrupt priority any longer than necessary. 206 */ 207 if (timeout_hardclock_update()) 208 softintr_schedule(softclock_si); 209 } 210 211 /* 212 * Compute number of hz in the specified amount of time. 213 */ 214 int 215 tvtohz(const struct timeval *tv) 216 { 217 unsigned long nticks; 218 time_t sec; 219 long usec; 220 221 /* 222 * If the number of usecs in the whole seconds part of the time 223 * fits in a long, then the total number of usecs will 224 * fit in an unsigned long. Compute the total and convert it to 225 * ticks, rounding up and adding 1 to allow for the current tick 226 * to expire. Rounding also depends on unsigned long arithmetic 227 * to avoid overflow. 228 * 229 * Otherwise, if the number of ticks in the whole seconds part of 230 * the time fits in a long, then convert the parts to 231 * ticks separately and add, using similar rounding methods and 232 * overflow avoidance. This method would work in the previous 233 * case but it is slightly slower and assumes that hz is integral. 234 * 235 * Otherwise, round the time down to the maximum 236 * representable value. 237 * 238 * If ints have 32 bits, then the maximum value for any timeout in 239 * 10ms ticks is 248 days. 240 */ 241 sec = tv->tv_sec; 242 usec = tv->tv_usec; 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 int 259 tstohz(const struct timespec *ts) 260 { 261 struct timeval tv; 262 TIMESPEC_TO_TIMEVAL(&tv, ts); 263 264 /* Round up. */ 265 if ((ts->tv_nsec % 1000) != 0) { 266 tv.tv_usec += 1; 267 if (tv.tv_usec >= 1000000) { 268 tv.tv_usec -= 1000000; 269 tv.tv_sec += 1; 270 } 271 } 272 273 return (tvtohz(&tv)); 274 } 275 276 /* 277 * Start profiling on a process. 278 * 279 * Kernel profiling passes proc0 which never exits and hence 280 * keeps the profile clock running constantly. 281 */ 282 void 283 startprofclock(struct process *pr) 284 { 285 int s; 286 287 if ((pr->ps_flags & PS_PROFIL) == 0) { 288 atomic_setbits_int(&pr->ps_flags, PS_PROFIL); 289 if (++profprocs == 1 && stathz != 0) { 290 s = splstatclock(); 291 psdiv = pscnt = psratio; 292 setstatclockrate(profhz); 293 splx(s); 294 } 295 } 296 } 297 298 /* 299 * Stop profiling on a process. 300 */ 301 void 302 stopprofclock(struct process *pr) 303 { 304 int s; 305 306 if (pr->ps_flags & PS_PROFIL) { 307 atomic_clearbits_int(&pr->ps_flags, PS_PROFIL); 308 if (--profprocs == 0 && stathz != 0) { 309 s = splstatclock(); 310 psdiv = pscnt = 1; 311 setstatclockrate(stathz); 312 splx(s); 313 } 314 } 315 } 316 317 /* 318 * Statistics clock. Grab profile sample, and if divider reaches 0, 319 * do process and kernel statistics. 320 */ 321 void 322 statclock(struct clockframe *frame) 323 { 324 #if defined(GPROF) || defined(DDBPROF) 325 struct gmonparam *g; 326 u_long i; 327 #endif 328 struct cpu_info *ci = curcpu(); 329 struct schedstate_percpu *spc = &ci->ci_schedstate; 330 struct proc *p = curproc; 331 struct process *pr; 332 333 /* 334 * Notice changes in divisor frequency, and adjust clock 335 * frequency accordingly. 336 */ 337 if (spc->spc_psdiv != psdiv) { 338 spc->spc_psdiv = psdiv; 339 spc->spc_pscnt = psdiv; 340 if (psdiv == 1) { 341 setstatclockrate(stathz); 342 } else { 343 setstatclockrate(profhz); 344 } 345 } 346 347 if (CLKF_USERMODE(frame)) { 348 pr = p->p_p; 349 if (pr->ps_flags & PS_PROFIL) 350 addupc_intr(p, CLKF_PC(frame)); 351 if (--spc->spc_pscnt > 0) 352 return; 353 /* 354 * Came from user mode; CPU was in user state. 355 * If this process is being profiled record the tick. 356 */ 357 p->p_uticks++; 358 if (pr->ps_nice > NZERO) 359 spc->spc_cp_time[CP_NICE]++; 360 else 361 spc->spc_cp_time[CP_USER]++; 362 } else { 363 #if defined(GPROF) || defined(DDBPROF) 364 /* 365 * Kernel statistics are just like addupc_intr, only easier. 366 */ 367 g = ci->ci_gmon; 368 if (g != NULL && g->state == GMON_PROF_ON) { 369 i = CLKF_PC(frame) - g->lowpc; 370 if (i < g->textsize) { 371 i /= HISTFRACTION * sizeof(*g->kcount); 372 g->kcount[i]++; 373 } 374 } 375 #endif 376 #if defined(PROC_PC) 377 if (p != NULL && p->p_p->ps_flags & PS_PROFIL) 378 addupc_intr(p, PROC_PC(p)); 379 #endif 380 if (--spc->spc_pscnt > 0) 381 return; 382 /* 383 * Came from kernel mode, so we were: 384 * - handling an interrupt, 385 * - doing syscall or trap work on behalf of the current 386 * user process, or 387 * - spinning in the idle loop. 388 * Whichever it is, charge the time as appropriate. 389 * Note that we charge interrupts to the current process, 390 * regardless of whether they are ``for'' that process, 391 * so that we know how much of its real time was spent 392 * in ``non-process'' (i.e., interrupt) work. 393 */ 394 if (CLKF_INTR(frame)) { 395 if (p != NULL) 396 p->p_iticks++; 397 spc->spc_cp_time[CP_INTR]++; 398 } else if (p != NULL && p != spc->spc_idleproc) { 399 p->p_sticks++; 400 spc->spc_cp_time[CP_SYS]++; 401 } else 402 spc->spc_cp_time[CP_IDLE]++; 403 } 404 spc->spc_pscnt = psdiv; 405 406 if (p != NULL) { 407 p->p_cpticks++; 408 /* 409 * If no schedclock is provided, call it here at ~~12-25 Hz; 410 * ~~16 Hz is best 411 */ 412 if (schedhz == 0) { 413 if ((++curcpu()->ci_schedstate.spc_schedticks & 3) == 414 0) 415 schedclock(p); 416 } 417 } 418 } 419 420 /* 421 * Return information about system clocks. 422 */ 423 int 424 sysctl_clockrate(char *where, size_t *sizep, void *newp) 425 { 426 struct clockinfo clkinfo; 427 428 /* 429 * Construct clockinfo structure. 430 */ 431 memset(&clkinfo, 0, sizeof clkinfo); 432 clkinfo.tick = tick; 433 clkinfo.tickadj = tickadj; 434 clkinfo.hz = hz; 435 clkinfo.profhz = profhz; 436 clkinfo.stathz = stathz ? stathz : hz; 437 return (sysctl_rdstruct(where, sizep, newp, &clkinfo, sizeof(clkinfo))); 438 } 439