1 /* $OpenBSD: kern_clock.c,v 1.121 2023/10/17 00:04:02 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 uint64_t hardclock_period; /* [I] hardclock period (ns) */ 91 uint64_t statclock_avg; /* [I] average statclock period (ns) */ 92 uint64_t statclock_min; /* [I] minimum statclock period (ns) */ 93 uint32_t statclock_mask; /* [I] set of allowed offsets */ 94 int statclock_is_randomized; /* [I] fixed or pseudorandom period? */ 95 96 /* 97 * Initialize clock frequencies and start both clocks running. 98 */ 99 void 100 initclocks(void) 101 { 102 uint64_t half_avg; 103 uint32_t var; 104 105 /* 106 * Let the machine-specific code do its bit. 107 */ 108 cpu_initclocks(); 109 110 KASSERT(hz > 0 && hz <= 1000000000); 111 hardclock_period = 1000000000 / hz; 112 roundrobin_period = hardclock_period * 10; 113 114 KASSERT(stathz >= 1 && stathz <= 1000000000); 115 116 /* 117 * Compute the average statclock() period. Then find var, the 118 * largest 32-bit power of two such that var <= statclock_avg / 2. 119 */ 120 statclock_avg = 1000000000 / stathz; 121 half_avg = statclock_avg / 2; 122 for (var = 1U << 31; var > half_avg; var /= 2) 123 continue; 124 125 /* 126 * Set a lower bound for the range using statclock_avg and var. 127 * The mask for that range is just (var - 1). 128 */ 129 statclock_min = statclock_avg - (var / 2); 130 statclock_mask = var - 1; 131 132 KASSERT(profhz >= stathz && profhz <= 1000000000); 133 KASSERT(profhz % stathz == 0); 134 profclock_period = 1000000000 / profhz; 135 136 inittimecounter(); 137 138 /* Start dispatching clock interrupts on the primary CPU. */ 139 cpu_startclock(); 140 } 141 142 /* 143 * The real-time timer, interrupting hz times per second. 144 */ 145 void 146 hardclock(struct clockframe *frame) 147 { 148 #if NDT > 0 149 DT_ENTER(profile, NULL); 150 if (CPU_IS_PRIMARY(curcpu())) 151 DT_ENTER(interval, NULL); 152 #endif 153 154 /* 155 * If we are not the primary CPU, we're not allowed to do 156 * any more work. 157 */ 158 if (CPU_IS_PRIMARY(curcpu()) == 0) 159 return; 160 161 tc_ticktock(); 162 ticks++; 163 jiffies++; 164 165 /* 166 * Update the timeout wheel. 167 */ 168 timeout_hardclock_update(); 169 } 170 171 /* 172 * Compute number of hz in the specified amount of time. 173 */ 174 int 175 tvtohz(const struct timeval *tv) 176 { 177 unsigned long nticks; 178 time_t sec; 179 long usec; 180 181 /* 182 * If the number of usecs in the whole seconds part of the time 183 * fits in a long, then the total number of usecs will 184 * fit in an unsigned long. Compute the total and convert it to 185 * ticks, rounding up and adding 1 to allow for the current tick 186 * to expire. Rounding also depends on unsigned long arithmetic 187 * to avoid overflow. 188 * 189 * Otherwise, if the number of ticks in the whole seconds part of 190 * the time fits in a long, then convert the parts to 191 * ticks separately and add, using similar rounding methods and 192 * overflow avoidance. This method would work in the previous 193 * case but it is slightly slower and assumes that hz is integral. 194 * 195 * Otherwise, round the time down to the maximum 196 * representable value. 197 * 198 * If ints have 32 bits, then the maximum value for any timeout in 199 * 10ms ticks is 248 days. 200 */ 201 sec = tv->tv_sec; 202 usec = tv->tv_usec; 203 if (sec < 0 || (sec == 0 && usec <= 0)) 204 nticks = 0; 205 else if (sec <= LONG_MAX / 1000000) 206 nticks = (sec * 1000000 + (unsigned long)usec + (tick - 1)) 207 / tick + 1; 208 else if (sec <= LONG_MAX / hz) 209 nticks = sec * hz 210 + ((unsigned long)usec + (tick - 1)) / tick + 1; 211 else 212 nticks = LONG_MAX; 213 if (nticks > INT_MAX) 214 nticks = INT_MAX; 215 return ((int)nticks); 216 } 217 218 int 219 tstohz(const struct timespec *ts) 220 { 221 struct timeval tv; 222 TIMESPEC_TO_TIMEVAL(&tv, ts); 223 224 /* Round up. */ 225 if ((ts->tv_nsec % 1000) != 0) { 226 tv.tv_usec += 1; 227 if (tv.tv_usec >= 1000000) { 228 tv.tv_usec -= 1000000; 229 tv.tv_sec += 1; 230 } 231 } 232 233 return (tvtohz(&tv)); 234 } 235 236 /* 237 * Start profiling on a process. 238 * 239 * Kernel profiling passes proc0 which never exits and hence 240 * keeps the profile clock running constantly. 241 */ 242 void 243 startprofclock(struct process *pr) 244 { 245 int s; 246 247 if ((pr->ps_flags & PS_PROFIL) == 0) { 248 atomic_setbits_int(&pr->ps_flags, PS_PROFIL); 249 if (++profprocs == 1) { 250 s = splstatclock(); 251 setstatclockrate(profhz); 252 splx(s); 253 } 254 } 255 } 256 257 /* 258 * Stop profiling on a process. 259 */ 260 void 261 stopprofclock(struct process *pr) 262 { 263 int s; 264 265 if (pr->ps_flags & PS_PROFIL) { 266 atomic_clearbits_int(&pr->ps_flags, PS_PROFIL); 267 if (--profprocs == 0) { 268 s = splstatclock(); 269 setstatclockrate(stathz); 270 splx(s); 271 } 272 } 273 } 274 275 /* 276 * Statistics clock. Grab profile sample, and if divider reaches 0, 277 * do process and kernel statistics. 278 */ 279 void 280 statclock(struct clockrequest *cr, void *cf, void *arg) 281 { 282 uint64_t count, i; 283 struct clockframe *frame = cf; 284 struct cpu_info *ci = curcpu(); 285 struct schedstate_percpu *spc = &ci->ci_schedstate; 286 struct proc *p = curproc; 287 struct process *pr; 288 289 if (statclock_is_randomized) { 290 count = clockrequest_advance_random(cr, statclock_min, 291 statclock_mask); 292 } else { 293 count = clockrequest_advance(cr, statclock_avg); 294 } 295 296 if (CLKF_USERMODE(frame)) { 297 pr = p->p_p; 298 /* 299 * Came from user mode; CPU was in user state. 300 * If this process is being profiled record the tick. 301 */ 302 p->p_uticks += count; 303 if (pr->ps_nice > NZERO) 304 spc->spc_cp_time[CP_NICE] += count; 305 else 306 spc->spc_cp_time[CP_USER] += count; 307 } else { 308 /* 309 * Came from kernel mode, so we were: 310 * - spinning on a lock 311 * - handling an interrupt, 312 * - doing syscall or trap work on behalf of the current 313 * user process, or 314 * - spinning in the idle loop. 315 * Whichever it is, charge the time as appropriate. 316 * Note that we charge interrupts to the current process, 317 * regardless of whether they are ``for'' that process, 318 * so that we know how much of its real time was spent 319 * in ``non-process'' (i.e., interrupt) work. 320 */ 321 if (CLKF_INTR(frame)) { 322 if (p != NULL) 323 p->p_iticks += count; 324 spc->spc_cp_time[spc->spc_spinning ? 325 CP_SPIN : CP_INTR] += count; 326 } else if (p != NULL && p != spc->spc_idleproc) { 327 p->p_sticks += count; 328 spc->spc_cp_time[spc->spc_spinning ? 329 CP_SPIN : CP_SYS] += count; 330 } else 331 spc->spc_cp_time[spc->spc_spinning ? 332 CP_SPIN : CP_IDLE] += count; 333 } 334 335 if (p != NULL) { 336 p->p_cpticks += count; 337 /* 338 * schedclock() runs every fourth statclock(). 339 */ 340 for (i = 0; i < count; i++) { 341 if ((++spc->spc_schedticks & 3) == 0) 342 schedclock(p); 343 } 344 } 345 } 346 347 /* 348 * Return information about system clocks. 349 */ 350 int 351 sysctl_clockrate(char *where, size_t *sizep, void *newp) 352 { 353 struct clockinfo clkinfo; 354 355 /* 356 * Construct clockinfo structure. 357 */ 358 memset(&clkinfo, 0, sizeof clkinfo); 359 clkinfo.tick = tick; 360 clkinfo.hz = hz; 361 clkinfo.profhz = profhz; 362 clkinfo.stathz = stathz; 363 return (sysctl_rdstruct(where, sizep, newp, &clkinfo, sizeof(clkinfo))); 364 } 365