1 /* $OpenBSD: kern_clock.c,v 1.102 2021/01/13 16:28:49 cheloha 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 #include "dt.h" 59 #if NDT > 0 60 #include <dev/dt/dtvar.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 int stathz; 88 int schedhz; 89 int profhz; 90 int profprocs; 91 int ticks; 92 static int psdiv, pscnt; /* prof => stat divider */ 93 int psratio; /* ratio: prof / stat */ 94 95 volatile unsigned long jiffies; /* XXX Linux API for drm(4) */ 96 97 /* 98 * Initialize clock frequencies and start both clocks running. 99 */ 100 void 101 initclocks(void) 102 { 103 int i; 104 105 ticks = INT_MAX - (15 * 60 * hz); 106 jiffies = ULONG_MAX - (10 * 60 * hz); 107 108 /* 109 * Set divisors to 1 (normal case) and let the machine-specific 110 * code do its bit. 111 */ 112 psdiv = pscnt = 1; 113 cpu_initclocks(); 114 115 /* 116 * Compute profhz/stathz, and fix profhz if needed. 117 */ 118 i = stathz ? stathz : hz; 119 if (profhz == 0) 120 profhz = i; 121 psratio = profhz / i; 122 123 inittimecounter(); 124 } 125 126 /* 127 * hardclock does the accounting needed for ITIMER_PROF and ITIMER_VIRTUAL. 128 * We don't want to send signals with psignal from hardclock because it makes 129 * MULTIPROCESSOR locking very complicated. Instead, to use an idea from 130 * FreeBSD, we set a flag on the thread and when it goes to return to 131 * userspace it signals itself. 132 */ 133 134 /* 135 * The real-time timer, interrupting hz times per second. 136 */ 137 void 138 hardclock(struct clockframe *frame) 139 { 140 struct proc *p; 141 struct cpu_info *ci = curcpu(); 142 143 p = curproc; 144 if (p && ((p->p_flag & (P_SYSTEM | P_WEXIT)) == 0)) { 145 struct process *pr = p->p_p; 146 147 /* 148 * Run current process's virtual and profile time, as needed. 149 */ 150 if (CLKF_USERMODE(frame) && 151 timespecisset(&pr->ps_timer[ITIMER_VIRTUAL].it_value) && 152 itimerdecr(&pr->ps_timer[ITIMER_VIRTUAL], tick_nsec) == 0) { 153 atomic_setbits_int(&p->p_flag, P_ALRMPEND); 154 need_proftick(p); 155 } 156 if (timespecisset(&pr->ps_timer[ITIMER_PROF].it_value) && 157 itimerdecr(&pr->ps_timer[ITIMER_PROF], tick_nsec) == 0) { 158 atomic_setbits_int(&p->p_flag, P_PROFPEND); 159 need_proftick(p); 160 } 161 } 162 163 /* 164 * If no separate statistics clock is available, run it from here. 165 */ 166 if (stathz == 0) 167 statclock(frame); 168 169 if (--ci->ci_schedstate.spc_rrticks <= 0) 170 roundrobin(ci); 171 172 #if NDT > 0 173 DT_ENTER(profile, NULL); 174 if (CPU_IS_PRIMARY(ci)) 175 DT_ENTER(interval, NULL); 176 #endif 177 178 /* 179 * If we are not the primary CPU, we're not allowed to do 180 * any more work. 181 */ 182 if (CPU_IS_PRIMARY(ci) == 0) 183 return; 184 185 tc_ticktock(); 186 ticks++; 187 jiffies++; 188 189 /* 190 * Update the timeout wheel. 191 */ 192 timeout_hardclock_update(); 193 } 194 195 /* 196 * Compute number of hz in the specified amount of time. 197 */ 198 int 199 tvtohz(const struct timeval *tv) 200 { 201 unsigned long nticks; 202 time_t sec; 203 long usec; 204 205 /* 206 * If the number of usecs in the whole seconds part of the time 207 * fits in a long, then the total number of usecs will 208 * fit in an unsigned long. Compute the total and convert it to 209 * ticks, rounding up and adding 1 to allow for the current tick 210 * to expire. Rounding also depends on unsigned long arithmetic 211 * to avoid overflow. 212 * 213 * Otherwise, if the number of ticks in the whole seconds part of 214 * the time fits in a long, then convert the parts to 215 * ticks separately and add, using similar rounding methods and 216 * overflow avoidance. This method would work in the previous 217 * case but it is slightly slower and assumes that hz is integral. 218 * 219 * Otherwise, round the time down to the maximum 220 * representable value. 221 * 222 * If ints have 32 bits, then the maximum value for any timeout in 223 * 10ms ticks is 248 days. 224 */ 225 sec = tv->tv_sec; 226 usec = tv->tv_usec; 227 if (sec < 0 || (sec == 0 && usec <= 0)) 228 nticks = 0; 229 else if (sec <= LONG_MAX / 1000000) 230 nticks = (sec * 1000000 + (unsigned long)usec + (tick - 1)) 231 / tick + 1; 232 else if (sec <= LONG_MAX / hz) 233 nticks = sec * hz 234 + ((unsigned long)usec + (tick - 1)) / tick + 1; 235 else 236 nticks = LONG_MAX; 237 if (nticks > INT_MAX) 238 nticks = INT_MAX; 239 return ((int)nticks); 240 } 241 242 int 243 tstohz(const struct timespec *ts) 244 { 245 struct timeval tv; 246 TIMESPEC_TO_TIMEVAL(&tv, ts); 247 248 /* Round up. */ 249 if ((ts->tv_nsec % 1000) != 0) { 250 tv.tv_usec += 1; 251 if (tv.tv_usec >= 1000000) { 252 tv.tv_usec -= 1000000; 253 tv.tv_sec += 1; 254 } 255 } 256 257 return (tvtohz(&tv)); 258 } 259 260 /* 261 * Start profiling on a process. 262 * 263 * Kernel profiling passes proc0 which never exits and hence 264 * keeps the profile clock running constantly. 265 */ 266 void 267 startprofclock(struct process *pr) 268 { 269 int s; 270 271 if ((pr->ps_flags & PS_PROFIL) == 0) { 272 atomic_setbits_int(&pr->ps_flags, PS_PROFIL); 273 if (++profprocs == 1 && stathz != 0) { 274 s = splstatclock(); 275 psdiv = pscnt = psratio; 276 setstatclockrate(profhz); 277 splx(s); 278 } 279 } 280 } 281 282 /* 283 * Stop profiling on a process. 284 */ 285 void 286 stopprofclock(struct process *pr) 287 { 288 int s; 289 290 if (pr->ps_flags & PS_PROFIL) { 291 atomic_clearbits_int(&pr->ps_flags, PS_PROFIL); 292 if (--profprocs == 0 && stathz != 0) { 293 s = splstatclock(); 294 psdiv = pscnt = 1; 295 setstatclockrate(stathz); 296 splx(s); 297 } 298 } 299 } 300 301 /* 302 * Statistics clock. Grab profile sample, and if divider reaches 0, 303 * do process and kernel statistics. 304 */ 305 void 306 statclock(struct clockframe *frame) 307 { 308 #if defined(GPROF) || defined(DDBPROF) 309 struct gmonparam *g; 310 u_long i; 311 #endif 312 struct cpu_info *ci = curcpu(); 313 struct schedstate_percpu *spc = &ci->ci_schedstate; 314 struct proc *p = curproc; 315 struct process *pr; 316 317 /* 318 * Notice changes in divisor frequency, and adjust clock 319 * frequency accordingly. 320 */ 321 if (spc->spc_psdiv != psdiv) { 322 spc->spc_psdiv = psdiv; 323 spc->spc_pscnt = psdiv; 324 if (psdiv == 1) { 325 setstatclockrate(stathz); 326 } else { 327 setstatclockrate(profhz); 328 } 329 } 330 331 if (CLKF_USERMODE(frame)) { 332 pr = p->p_p; 333 if (pr->ps_flags & PS_PROFIL) 334 addupc_intr(p, CLKF_PC(frame)); 335 if (--spc->spc_pscnt > 0) 336 return; 337 /* 338 * Came from user mode; CPU was in user state. 339 * If this process is being profiled record the tick. 340 */ 341 p->p_uticks++; 342 if (pr->ps_nice > NZERO) 343 spc->spc_cp_time[CP_NICE]++; 344 else 345 spc->spc_cp_time[CP_USER]++; 346 } else { 347 #if defined(GPROF) || defined(DDBPROF) 348 /* 349 * Kernel statistics are just like addupc_intr, only easier. 350 */ 351 g = ci->ci_gmon; 352 if (g != NULL && g->state == GMON_PROF_ON) { 353 i = CLKF_PC(frame) - g->lowpc; 354 if (i < g->textsize) { 355 i /= HISTFRACTION * sizeof(*g->kcount); 356 g->kcount[i]++; 357 } 358 } 359 #endif 360 #if defined(PROC_PC) 361 if (p != NULL && p->p_p->ps_flags & PS_PROFIL) 362 addupc_intr(p, PROC_PC(p)); 363 #endif 364 if (--spc->spc_pscnt > 0) 365 return; 366 /* 367 * Came from kernel mode, so we were: 368 * - spinning on a lock 369 * - handling an interrupt, 370 * - doing syscall or trap work on behalf of the current 371 * user process, or 372 * - spinning in the idle loop. 373 * Whichever it is, charge the time as appropriate. 374 * Note that we charge interrupts to the current process, 375 * regardless of whether they are ``for'' that process, 376 * so that we know how much of its real time was spent 377 * in ``non-process'' (i.e., interrupt) work. 378 */ 379 if (CLKF_INTR(frame)) { 380 if (p != NULL) 381 p->p_iticks++; 382 spc->spc_cp_time[spc->spc_spinning ? 383 CP_SPIN : CP_INTR]++; 384 } else if (p != NULL && p != spc->spc_idleproc) { 385 p->p_sticks++; 386 spc->spc_cp_time[spc->spc_spinning ? 387 CP_SPIN : CP_SYS]++; 388 } else 389 spc->spc_cp_time[spc->spc_spinning ? 390 CP_SPIN : CP_IDLE]++; 391 } 392 spc->spc_pscnt = psdiv; 393 394 if (p != NULL) { 395 p->p_cpticks++; 396 /* 397 * If no schedclock is provided, call it here at ~~12-25 Hz; 398 * ~~16 Hz is best 399 */ 400 if (schedhz == 0) { 401 if ((++spc->spc_schedticks & 3) == 0) 402 schedclock(p); 403 } 404 } 405 } 406 407 /* 408 * Return information about system clocks. 409 */ 410 int 411 sysctl_clockrate(char *where, size_t *sizep, void *newp) 412 { 413 struct clockinfo clkinfo; 414 415 /* 416 * Construct clockinfo structure. 417 */ 418 memset(&clkinfo, 0, sizeof clkinfo); 419 clkinfo.tick = tick; 420 clkinfo.hz = hz; 421 clkinfo.profhz = profhz; 422 clkinfo.stathz = stathz ? stathz : hz; 423 return (sysctl_rdstruct(where, sizep, newp, &clkinfo, sizeof(clkinfo))); 424 } 425