1 /* $OpenBSD: kern_clock.c,v 1.115 2023/08/23 01:55:45 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/sysctl.h> 49 #include <sys/sched.h> 50 #include <sys/timetc.h> 51 52 #include "dt.h" 53 #if NDT > 0 54 #include <dev/dt/dtvar.h> 55 #endif 56 57 /* 58 * Clock handling routines. 59 * 60 * This code is written to operate with two timers that run independently of 61 * each other. The main clock, running hz times per second, is used to keep 62 * track of real time. The second timer handles kernel and user profiling, 63 * and does resource use estimation. If the second timer is programmable, 64 * it is randomized to avoid aliasing between the two clocks. For example, 65 * the randomization prevents an adversary from always giving up the cpu 66 * just before its quantum expires. Otherwise, it would never accumulate 67 * cpu ticks. The mean frequency of the second timer is stathz. 68 * 69 * If no second timer exists, stathz will be zero; in this case we drive 70 * profiling and statistics off the main clock. This WILL NOT be accurate; 71 * do not do it unless absolutely necessary. 72 * 73 * The statistics clock may (or may not) be run at a higher rate while 74 * profiling. This profile clock runs at profhz. We require that profhz 75 * be an integral multiple of stathz. 76 * 77 * If the statistics clock is running fast, it must be divided by the ratio 78 * profhz/stathz for statistics. (For profiling, every tick counts.) 79 */ 80 81 int stathz; 82 int schedhz; 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 /* 91 * Initialize clock frequencies and start both clocks running. 92 */ 93 void 94 initclocks(void) 95 { 96 /* 97 * Let the machine-specific code do its bit. 98 */ 99 cpu_initclocks(); 100 101 KASSERT(profhz >= stathz && profhz <= 1000000000); 102 KASSERT(profhz % stathz == 0); 103 profclock_period = 1000000000 / profhz; 104 105 inittimecounter(); 106 107 /* Start dispatching clock interrupts on the primary CPU. */ 108 cpu_startclock(); 109 } 110 111 /* 112 * The real-time timer, interrupting hz times per second. 113 */ 114 void 115 hardclock(struct clockframe *frame) 116 { 117 #if NDT > 0 118 DT_ENTER(profile, NULL); 119 if (CPU_IS_PRIMARY(curcpu())) 120 DT_ENTER(interval, NULL); 121 #endif 122 123 /* 124 * If we are not the primary CPU, we're not allowed to do 125 * any more work. 126 */ 127 if (CPU_IS_PRIMARY(curcpu()) == 0) 128 return; 129 130 tc_ticktock(); 131 ticks++; 132 jiffies++; 133 134 /* 135 * Update the timeout wheel. 136 */ 137 timeout_hardclock_update(); 138 } 139 140 /* 141 * Compute number of hz in the specified amount of time. 142 */ 143 int 144 tvtohz(const struct timeval *tv) 145 { 146 unsigned long nticks; 147 time_t sec; 148 long usec; 149 150 /* 151 * If the number of usecs in the whole seconds part of the time 152 * fits in a long, then the total number of usecs will 153 * fit in an unsigned long. Compute the total and convert it to 154 * ticks, rounding up and adding 1 to allow for the current tick 155 * to expire. Rounding also depends on unsigned long arithmetic 156 * to avoid overflow. 157 * 158 * Otherwise, if the number of ticks in the whole seconds part of 159 * the time fits in a long, then convert the parts to 160 * ticks separately and add, using similar rounding methods and 161 * overflow avoidance. This method would work in the previous 162 * case but it is slightly slower and assumes that hz is integral. 163 * 164 * Otherwise, round the time down to the maximum 165 * representable value. 166 * 167 * If ints have 32 bits, then the maximum value for any timeout in 168 * 10ms ticks is 248 days. 169 */ 170 sec = tv->tv_sec; 171 usec = tv->tv_usec; 172 if (sec < 0 || (sec == 0 && usec <= 0)) 173 nticks = 0; 174 else if (sec <= LONG_MAX / 1000000) 175 nticks = (sec * 1000000 + (unsigned long)usec + (tick - 1)) 176 / tick + 1; 177 else if (sec <= LONG_MAX / hz) 178 nticks = sec * hz 179 + ((unsigned long)usec + (tick - 1)) / tick + 1; 180 else 181 nticks = LONG_MAX; 182 if (nticks > INT_MAX) 183 nticks = INT_MAX; 184 return ((int)nticks); 185 } 186 187 int 188 tstohz(const struct timespec *ts) 189 { 190 struct timeval tv; 191 TIMESPEC_TO_TIMEVAL(&tv, ts); 192 193 /* Round up. */ 194 if ((ts->tv_nsec % 1000) != 0) { 195 tv.tv_usec += 1; 196 if (tv.tv_usec >= 1000000) { 197 tv.tv_usec -= 1000000; 198 tv.tv_sec += 1; 199 } 200 } 201 202 return (tvtohz(&tv)); 203 } 204 205 /* 206 * Start profiling on a process. 207 * 208 * Kernel profiling passes proc0 which never exits and hence 209 * keeps the profile clock running constantly. 210 */ 211 void 212 startprofclock(struct process *pr) 213 { 214 int s; 215 216 if ((pr->ps_flags & PS_PROFIL) == 0) { 217 atomic_setbits_int(&pr->ps_flags, PS_PROFIL); 218 if (++profprocs == 1) { 219 s = splstatclock(); 220 setstatclockrate(profhz); 221 splx(s); 222 } 223 } 224 } 225 226 /* 227 * Stop profiling on a process. 228 */ 229 void 230 stopprofclock(struct process *pr) 231 { 232 int s; 233 234 if (pr->ps_flags & PS_PROFIL) { 235 atomic_clearbits_int(&pr->ps_flags, PS_PROFIL); 236 if (--profprocs == 0) { 237 s = splstatclock(); 238 setstatclockrate(stathz); 239 splx(s); 240 } 241 } 242 } 243 244 /* 245 * Statistics clock. Grab profile sample, and if divider reaches 0, 246 * do process and kernel statistics. 247 */ 248 void 249 statclock(struct clockframe *frame) 250 { 251 struct cpu_info *ci = curcpu(); 252 struct schedstate_percpu *spc = &ci->ci_schedstate; 253 struct proc *p = curproc; 254 struct process *pr; 255 256 if (CLKF_USERMODE(frame)) { 257 pr = p->p_p; 258 /* 259 * Came from user mode; CPU was in user state. 260 * If this process is being profiled record the tick. 261 */ 262 p->p_uticks++; 263 if (pr->ps_nice > NZERO) 264 spc->spc_cp_time[CP_NICE]++; 265 else 266 spc->spc_cp_time[CP_USER]++; 267 } else { 268 /* 269 * Came from kernel mode, so we were: 270 * - spinning on a lock 271 * - handling an interrupt, 272 * - doing syscall or trap work on behalf of the current 273 * user process, or 274 * - spinning in the idle loop. 275 * Whichever it is, charge the time as appropriate. 276 * Note that we charge interrupts to the current process, 277 * regardless of whether they are ``for'' that process, 278 * so that we know how much of its real time was spent 279 * in ``non-process'' (i.e., interrupt) work. 280 */ 281 if (CLKF_INTR(frame)) { 282 if (p != NULL) 283 p->p_iticks++; 284 spc->spc_cp_time[spc->spc_spinning ? 285 CP_SPIN : CP_INTR]++; 286 } else if (p != NULL && p != spc->spc_idleproc) { 287 p->p_sticks++; 288 spc->spc_cp_time[spc->spc_spinning ? 289 CP_SPIN : CP_SYS]++; 290 } else 291 spc->spc_cp_time[spc->spc_spinning ? 292 CP_SPIN : CP_IDLE]++; 293 } 294 295 if (p != NULL) { 296 p->p_cpticks++; 297 /* 298 * If no schedclock is provided, call it here at ~~12-25 Hz; 299 * ~~16 Hz is best 300 */ 301 if (schedhz == 0) { 302 if ((++spc->spc_schedticks & 3) == 0) 303 schedclock(p); 304 } 305 } 306 } 307 308 /* 309 * Return information about system clocks. 310 */ 311 int 312 sysctl_clockrate(char *where, size_t *sizep, void *newp) 313 { 314 struct clockinfo clkinfo; 315 316 /* 317 * Construct clockinfo structure. 318 */ 319 memset(&clkinfo, 0, sizeof clkinfo); 320 clkinfo.tick = tick; 321 clkinfo.hz = hz; 322 clkinfo.profhz = profhz; 323 clkinfo.stathz = stathz; 324 return (sysctl_rdstruct(where, sizep, newp, &clkinfo, sizeof(clkinfo))); 325 } 326