1 /* $OpenBSD: kern_clock.c,v 1.118 2023/09/14 20:58:51 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/clockintr.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/sysctl.h> 50 #include <sys/sched.h> 51 #include <sys/timetc.h> 52 53 #include "dt.h" 54 #if NDT > 0 55 #include <dev/dt/dtvar.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 int stathz; 83 int profhz; 84 int profprocs; 85 int ticks = INT_MAX - (15 * 60 * HZ); 86 87 /* Don't force early wrap around, triggers bug in inteldrm */ 88 volatile unsigned long jiffies; 89 90 uint32_t statclock_avg; /* [I] average statclock period (ns) */ 91 uint32_t statclock_min; /* [I] minimum statclock period (ns) */ 92 uint32_t statclock_mask; /* [I] set of allowed offsets */ 93 int statclock_is_randomized; /* [I] fixed or pseudorandom period? */ 94 95 /* 96 * Initialize clock frequencies and start both clocks running. 97 */ 98 void 99 initclocks(void) 100 { 101 uint32_t half_avg, var; 102 103 /* 104 * Let the machine-specific code do its bit. 105 */ 106 cpu_initclocks(); 107 108 KASSERT(stathz >= 1 && stathz <= 1000000000); 109 110 /* 111 * Compute the average statclock() period. Then find var, the 112 * largest power of two such that var <= statclock_avg / 2. 113 */ 114 statclock_avg = 1000000000 / stathz; 115 half_avg = statclock_avg / 2; 116 for (var = 1U << 31; var > half_avg; var /= 2) 117 continue; 118 119 /* 120 * Set a lower bound for the range using statclock_avg and var. 121 * The mask for that range is just (var - 1). 122 */ 123 statclock_min = statclock_avg - (var / 2); 124 statclock_mask = var - 1; 125 126 KASSERT(profhz >= stathz && profhz <= 1000000000); 127 KASSERT(profhz % stathz == 0); 128 profclock_period = 1000000000 / profhz; 129 130 inittimecounter(); 131 132 /* Start dispatching clock interrupts on the primary CPU. */ 133 cpu_startclock(); 134 } 135 136 /* 137 * The real-time timer, interrupting hz times per second. 138 */ 139 void 140 hardclock(struct clockframe *frame) 141 { 142 #if NDT > 0 143 DT_ENTER(profile, NULL); 144 if (CPU_IS_PRIMARY(curcpu())) 145 DT_ENTER(interval, NULL); 146 #endif 147 148 /* 149 * If we are not the primary CPU, we're not allowed to do 150 * any more work. 151 */ 152 if (CPU_IS_PRIMARY(curcpu()) == 0) 153 return; 154 155 tc_ticktock(); 156 ticks++; 157 jiffies++; 158 159 /* 160 * Update the timeout wheel. 161 */ 162 timeout_hardclock_update(); 163 } 164 165 /* 166 * Compute number of hz in the specified amount of time. 167 */ 168 int 169 tvtohz(const struct timeval *tv) 170 { 171 unsigned long nticks; 172 time_t sec; 173 long usec; 174 175 /* 176 * If the number of usecs in the whole seconds part of the time 177 * fits in a long, then the total number of usecs will 178 * fit in an unsigned long. Compute the total and convert it to 179 * ticks, rounding up and adding 1 to allow for the current tick 180 * to expire. Rounding also depends on unsigned long arithmetic 181 * to avoid overflow. 182 * 183 * Otherwise, if the number of ticks in the whole seconds part of 184 * the time fits in a long, then convert the parts to 185 * ticks separately and add, using similar rounding methods and 186 * overflow avoidance. This method would work in the previous 187 * case but it is slightly slower and assumes that hz is integral. 188 * 189 * Otherwise, round the time down to the maximum 190 * representable value. 191 * 192 * If ints have 32 bits, then the maximum value for any timeout in 193 * 10ms ticks is 248 days. 194 */ 195 sec = tv->tv_sec; 196 usec = tv->tv_usec; 197 if (sec < 0 || (sec == 0 && usec <= 0)) 198 nticks = 0; 199 else if (sec <= LONG_MAX / 1000000) 200 nticks = (sec * 1000000 + (unsigned long)usec + (tick - 1)) 201 / tick + 1; 202 else if (sec <= LONG_MAX / hz) 203 nticks = sec * hz 204 + ((unsigned long)usec + (tick - 1)) / tick + 1; 205 else 206 nticks = LONG_MAX; 207 if (nticks > INT_MAX) 208 nticks = INT_MAX; 209 return ((int)nticks); 210 } 211 212 int 213 tstohz(const struct timespec *ts) 214 { 215 struct timeval tv; 216 TIMESPEC_TO_TIMEVAL(&tv, ts); 217 218 /* Round up. */ 219 if ((ts->tv_nsec % 1000) != 0) { 220 tv.tv_usec += 1; 221 if (tv.tv_usec >= 1000000) { 222 tv.tv_usec -= 1000000; 223 tv.tv_sec += 1; 224 } 225 } 226 227 return (tvtohz(&tv)); 228 } 229 230 /* 231 * Start profiling on a process. 232 * 233 * Kernel profiling passes proc0 which never exits and hence 234 * keeps the profile clock running constantly. 235 */ 236 void 237 startprofclock(struct process *pr) 238 { 239 int s; 240 241 if ((pr->ps_flags & PS_PROFIL) == 0) { 242 atomic_setbits_int(&pr->ps_flags, PS_PROFIL); 243 if (++profprocs == 1) { 244 s = splstatclock(); 245 setstatclockrate(profhz); 246 splx(s); 247 } 248 } 249 } 250 251 /* 252 * Stop profiling on a process. 253 */ 254 void 255 stopprofclock(struct process *pr) 256 { 257 int s; 258 259 if (pr->ps_flags & PS_PROFIL) { 260 atomic_clearbits_int(&pr->ps_flags, PS_PROFIL); 261 if (--profprocs == 0) { 262 s = splstatclock(); 263 setstatclockrate(stathz); 264 splx(s); 265 } 266 } 267 } 268 269 /* 270 * Statistics clock. Grab profile sample, and if divider reaches 0, 271 * do process and kernel statistics. 272 */ 273 void 274 statclock(struct clockintr *cl, void *cf, void *arg) 275 { 276 uint64_t count, i; 277 struct clockframe *frame = cf; 278 struct cpu_info *ci = curcpu(); 279 struct schedstate_percpu *spc = &ci->ci_schedstate; 280 struct proc *p = curproc; 281 struct process *pr; 282 283 if (statclock_is_randomized) { 284 count = clockintr_advance_random(cl, statclock_min, 285 statclock_mask); 286 } else { 287 count = clockintr_advance(cl, statclock_avg); 288 } 289 290 if (CLKF_USERMODE(frame)) { 291 pr = p->p_p; 292 /* 293 * Came from user mode; CPU was in user state. 294 * If this process is being profiled record the tick. 295 */ 296 p->p_uticks += count; 297 if (pr->ps_nice > NZERO) 298 spc->spc_cp_time[CP_NICE] += count; 299 else 300 spc->spc_cp_time[CP_USER] += count; 301 } else { 302 /* 303 * Came from kernel mode, so we were: 304 * - spinning on a lock 305 * - handling an interrupt, 306 * - doing syscall or trap work on behalf of the current 307 * user process, or 308 * - spinning in the idle loop. 309 * Whichever it is, charge the time as appropriate. 310 * Note that we charge interrupts to the current process, 311 * regardless of whether they are ``for'' that process, 312 * so that we know how much of its real time was spent 313 * in ``non-process'' (i.e., interrupt) work. 314 */ 315 if (CLKF_INTR(frame)) { 316 if (p != NULL) 317 p->p_iticks += count; 318 spc->spc_cp_time[spc->spc_spinning ? 319 CP_SPIN : CP_INTR] += count; 320 } else if (p != NULL && p != spc->spc_idleproc) { 321 p->p_sticks += count; 322 spc->spc_cp_time[spc->spc_spinning ? 323 CP_SPIN : CP_SYS] += count; 324 } else 325 spc->spc_cp_time[spc->spc_spinning ? 326 CP_SPIN : CP_IDLE] += count; 327 } 328 329 if (p != NULL) { 330 p->p_cpticks += count; 331 /* 332 * schedclock() runs every fourth statclock(). 333 */ 334 for (i = 0; i < count; i++) { 335 if ((++spc->spc_schedticks & 3) == 0) 336 schedclock(p); 337 } 338 } 339 } 340 341 /* 342 * Return information about system clocks. 343 */ 344 int 345 sysctl_clockrate(char *where, size_t *sizep, void *newp) 346 { 347 struct clockinfo clkinfo; 348 349 /* 350 * Construct clockinfo structure. 351 */ 352 memset(&clkinfo, 0, sizeof clkinfo); 353 clkinfo.tick = tick; 354 clkinfo.hz = hz; 355 clkinfo.profhz = profhz; 356 clkinfo.stathz = stathz; 357 return (sysctl_rdstruct(where, sizep, newp, &clkinfo, sizeof(clkinfo))); 358 } 359