1 /* $OpenBSD: kern_clock.c,v 1.90 2016/03/24 05:40:56 dlg 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 ticks = INT_MAX - (15 * 60 * hz); 119 120 /* 121 * Set divisors to 1 (normal case) and let the machine-specific 122 * code do its bit. 123 */ 124 psdiv = pscnt = 1; 125 cpu_initclocks(); 126 127 /* 128 * Compute profhz/stathz, and fix profhz if needed. 129 */ 130 i = stathz ? stathz : hz; 131 if (profhz == 0) 132 profhz = i; 133 psratio = profhz / i; 134 135 /* For very large HZ, ensure that division by 0 does not occur later */ 136 if (tickadj == 0) 137 tickadj = 1; 138 139 inittimecounter(); 140 } 141 142 /* 143 * hardclock does the accounting needed for ITIMER_PROF and ITIMER_VIRTUAL. 144 * We don't want to send signals with psignal from hardclock because it makes 145 * MULTIPROCESSOR locking very complicated. Instead, to use an idea from 146 * FreeBSD, we set a flag on the thread and when it goes to return to 147 * userspace it signals itself. 148 */ 149 150 /* 151 * The real-time timer, interrupting hz times per second. 152 */ 153 void 154 hardclock(struct clockframe *frame) 155 { 156 struct proc *p; 157 struct cpu_info *ci = curcpu(); 158 159 p = curproc; 160 if (p && ((p->p_flag & (P_SYSTEM | P_WEXIT)) == 0)) { 161 struct process *pr = p->p_p; 162 163 /* 164 * Run current process's virtual and profile time, as needed. 165 */ 166 if (CLKF_USERMODE(frame) && 167 timerisset(&pr->ps_timer[ITIMER_VIRTUAL].it_value) && 168 itimerdecr(&pr->ps_timer[ITIMER_VIRTUAL], tick) == 0) { 169 atomic_setbits_int(&p->p_flag, P_ALRMPEND); 170 need_proftick(p); 171 } 172 if (timerisset(&pr->ps_timer[ITIMER_PROF].it_value) && 173 itimerdecr(&pr->ps_timer[ITIMER_PROF], tick) == 0) { 174 atomic_setbits_int(&p->p_flag, P_PROFPEND); 175 need_proftick(p); 176 } 177 } 178 179 /* 180 * If no separate statistics clock is available, run it from here. 181 */ 182 if (stathz == 0) 183 statclock(frame); 184 185 if (--ci->ci_schedstate.spc_rrticks <= 0) 186 roundrobin(ci); 187 188 /* 189 * If we are not the primary CPU, we're not allowed to do 190 * any more work. 191 */ 192 if (CPU_IS_PRIMARY(ci) == 0) 193 return; 194 195 tc_ticktock(); 196 ticks++; 197 198 /* 199 * Update real-time timeout queue. 200 * Process callouts at a very low cpu priority, so we don't keep the 201 * relatively high clock interrupt priority any longer than necessary. 202 */ 203 if (timeout_hardclock_update()) 204 softintr_schedule(softclock_si); 205 } 206 207 /* 208 * Compute number of hz in the specified amount of time. 209 */ 210 int 211 tvtohz(const struct timeval *tv) 212 { 213 unsigned long nticks; 214 time_t sec; 215 long usec; 216 217 /* 218 * If the number of usecs in the whole seconds part of the time 219 * fits in a long, then the total number of usecs will 220 * fit in an unsigned long. Compute the total and convert it to 221 * ticks, rounding up and adding 1 to allow for the current tick 222 * to expire. Rounding also depends on unsigned long arithmetic 223 * to avoid overflow. 224 * 225 * Otherwise, if the number of ticks in the whole seconds part of 226 * the time fits in a long, then convert the parts to 227 * ticks separately and add, using similar rounding methods and 228 * overflow avoidance. This method would work in the previous 229 * case but it is slightly slower and assumes that hz is integral. 230 * 231 * Otherwise, round the time down to the maximum 232 * representable value. 233 * 234 * If ints have 32 bits, then the maximum value for any timeout in 235 * 10ms ticks is 248 days. 236 */ 237 sec = tv->tv_sec; 238 usec = tv->tv_usec; 239 if (sec < 0 || (sec == 0 && usec <= 0)) 240 nticks = 0; 241 else if (sec <= LONG_MAX / 1000000) 242 nticks = (sec * 1000000 + (unsigned long)usec + (tick - 1)) 243 / tick + 1; 244 else if (sec <= LONG_MAX / hz) 245 nticks = sec * hz 246 + ((unsigned long)usec + (tick - 1)) / tick + 1; 247 else 248 nticks = LONG_MAX; 249 if (nticks > INT_MAX) 250 nticks = INT_MAX; 251 return ((int)nticks); 252 } 253 254 int 255 tstohz(const struct timespec *ts) 256 { 257 struct timeval tv; 258 TIMESPEC_TO_TIMEVAL(&tv, ts); 259 260 /* Round up. */ 261 if ((ts->tv_nsec % 1000) != 0) { 262 tv.tv_usec += 1; 263 if (tv.tv_usec >= 1000000) { 264 tv.tv_usec -= 1000000; 265 tv.tv_sec += 1; 266 } 267 } 268 269 return (tvtohz(&tv)); 270 } 271 272 /* 273 * Start profiling on a process. 274 * 275 * Kernel profiling passes proc0 which never exits and hence 276 * keeps the profile clock running constantly. 277 */ 278 void 279 startprofclock(struct process *pr) 280 { 281 int s; 282 283 if ((pr->ps_flags & PS_PROFIL) == 0) { 284 atomic_setbits_int(&pr->ps_flags, PS_PROFIL); 285 if (++profprocs == 1 && stathz != 0) { 286 s = splstatclock(); 287 psdiv = pscnt = psratio; 288 setstatclockrate(profhz); 289 splx(s); 290 } 291 } 292 } 293 294 /* 295 * Stop profiling on a process. 296 */ 297 void 298 stopprofclock(struct process *pr) 299 { 300 int s; 301 302 if (pr->ps_flags & PS_PROFIL) { 303 atomic_clearbits_int(&pr->ps_flags, PS_PROFIL); 304 if (--profprocs == 0 && stathz != 0) { 305 s = splstatclock(); 306 psdiv = pscnt = 1; 307 setstatclockrate(stathz); 308 splx(s); 309 } 310 } 311 } 312 313 /* 314 * Statistics clock. Grab profile sample, and if divider reaches 0, 315 * do process and kernel statistics. 316 */ 317 void 318 statclock(struct clockframe *frame) 319 { 320 #ifdef GPROF 321 struct gmonparam *g; 322 u_long i; 323 #endif 324 struct cpu_info *ci = curcpu(); 325 struct schedstate_percpu *spc = &ci->ci_schedstate; 326 struct proc *p = curproc; 327 struct process *pr; 328 329 /* 330 * Notice changes in divisor frequency, and adjust clock 331 * frequency accordingly. 332 */ 333 if (spc->spc_psdiv != psdiv) { 334 spc->spc_psdiv = psdiv; 335 spc->spc_pscnt = psdiv; 336 if (psdiv == 1) { 337 setstatclockrate(stathz); 338 } else { 339 setstatclockrate(profhz); 340 } 341 } 342 343 if (CLKF_USERMODE(frame)) { 344 pr = p->p_p; 345 if (pr->ps_flags & PS_PROFIL) 346 addupc_intr(p, CLKF_PC(frame)); 347 if (--spc->spc_pscnt > 0) 348 return; 349 /* 350 * Came from user mode; CPU was in user state. 351 * If this process is being profiled record the tick. 352 */ 353 p->p_uticks++; 354 if (pr->ps_nice > NZERO) 355 spc->spc_cp_time[CP_NICE]++; 356 else 357 spc->spc_cp_time[CP_USER]++; 358 } else { 359 #ifdef GPROF 360 /* 361 * Kernel statistics are just like addupc_intr, only easier. 362 */ 363 g = ci->ci_gmon; 364 if (g != NULL && g->state == GMON_PROF_ON) { 365 i = CLKF_PC(frame) - g->lowpc; 366 if (i < g->textsize) { 367 i /= HISTFRACTION * sizeof(*g->kcount); 368 g->kcount[i]++; 369 } 370 } 371 #endif 372 #if defined(PROC_PC) 373 if (p != NULL && p->p_p->ps_flags & PS_PROFIL) 374 addupc_intr(p, PROC_PC(p)); 375 #endif 376 if (--spc->spc_pscnt > 0) 377 return; 378 /* 379 * Came from kernel mode, so we were: 380 * - handling an interrupt, 381 * - doing syscall or trap work on behalf of the current 382 * user process, or 383 * - spinning in the idle loop. 384 * Whichever it is, charge the time as appropriate. 385 * Note that we charge interrupts to the current process, 386 * regardless of whether they are ``for'' that process, 387 * so that we know how much of its real time was spent 388 * in ``non-process'' (i.e., interrupt) work. 389 */ 390 if (CLKF_INTR(frame)) { 391 if (p != NULL) 392 p->p_iticks++; 393 spc->spc_cp_time[CP_INTR]++; 394 } else if (p != NULL && p != spc->spc_idleproc) { 395 p->p_sticks++; 396 spc->spc_cp_time[CP_SYS]++; 397 } else 398 spc->spc_cp_time[CP_IDLE]++; 399 } 400 spc->spc_pscnt = psdiv; 401 402 if (p != NULL) { 403 p->p_cpticks++; 404 /* 405 * If no schedclock is provided, call it here at ~~12-25 Hz; 406 * ~~16 Hz is best 407 */ 408 if (schedhz == 0) { 409 if ((++curcpu()->ci_schedstate.spc_schedticks & 3) == 410 0) 411 schedclock(p); 412 } 413 } 414 } 415 416 /* 417 * Return information about system clocks. 418 */ 419 int 420 sysctl_clockrate(char *where, size_t *sizep, void *newp) 421 { 422 struct clockinfo clkinfo; 423 424 /* 425 * Construct clockinfo structure. 426 */ 427 clkinfo.tick = tick; 428 clkinfo.tickadj = tickadj; 429 clkinfo.hz = hz; 430 clkinfo.profhz = profhz; 431 clkinfo.stathz = stathz ? stathz : hz; 432 return (sysctl_rdstruct(where, sizep, newp, &clkinfo, sizeof(clkinfo))); 433 } 434