1 /* $OpenBSD: kern_clock.c,v 1.42 2003/06/02 23:28:05 millert 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/dkstat.h> 43 #include <sys/timeout.h> 44 #include <sys/kernel.h> 45 #include <sys/limits.h> 46 #include <sys/proc.h> 47 #include <sys/resourcevar.h> 48 #include <sys/signalvar.h> 49 #include <uvm/uvm_extern.h> 50 #include <sys/sysctl.h> 51 #include <sys/sched.h> 52 53 #include <machine/cpu.h> 54 55 #ifdef GPROF 56 #include <sys/gmon.h> 57 #endif 58 59 /* 60 * Clock handling routines. 61 * 62 * This code is written to operate with two timers that run independently of 63 * each other. The main clock, running hz times per second, is used to keep 64 * track of real time. The second timer handles kernel and user profiling, 65 * and does resource use estimation. If the second timer is programmable, 66 * it is randomized to avoid aliasing between the two clocks. For example, 67 * the randomization prevents an adversary from always giving up the cpu 68 * just before its quantum expires. Otherwise, it would never accumulate 69 * cpu ticks. The mean frequency of the second timer is stathz. 70 * 71 * If no second timer exists, stathz will be zero; in this case we drive 72 * profiling and statistics off the main clock. This WILL NOT be accurate; 73 * do not do it unless absolutely necessary. 74 * 75 * The statistics clock may (or may not) be run at a higher rate while 76 * profiling. This profile clock runs at profhz. We require that profhz 77 * be an integral multiple of stathz. 78 * 79 * If the statistics clock is running fast, it must be divided by the ratio 80 * profhz/stathz for statistics. (For profiling, every tick counts.) 81 */ 82 83 /* 84 * Bump a timeval by a small number of usec's. 85 */ 86 #define BUMPTIME(t, usec) { \ 87 register volatile struct timeval *tp = (t); \ 88 register long us; \ 89 \ 90 tp->tv_usec = us = tp->tv_usec + (usec); \ 91 if (us >= 1000000) { \ 92 tp->tv_usec = us - 1000000; \ 93 tp->tv_sec++; \ 94 } \ 95 } 96 97 int stathz; 98 int schedhz; 99 int profhz; 100 int profprocs; 101 int ticks; 102 static int psdiv, pscnt; /* prof => stat divider */ 103 int psratio; /* ratio: prof / stat */ 104 int tickfix, tickfixinterval; /* used if tick not really integral */ 105 static int tickfixcnt; /* accumulated fractional error */ 106 107 long cp_time[CPUSTATES]; 108 109 volatile struct timeval time 110 __attribute__((__aligned__(__alignof__(quad_t)))); 111 volatile struct timeval mono_time; 112 113 #ifdef __HAVE_GENERIC_SOFT_INTERRUPTS 114 void *softclock_si; 115 void generic_softclock(void *); 116 117 void 118 generic_softclock(void *ignore) 119 { 120 /* 121 * XXX - dont' commit, just a dummy wrapper until we learn everyone 122 * deal with a changed proto for softclock(). 123 */ 124 softclock(); 125 } 126 #endif 127 128 /* 129 * Initialize clock frequencies and start both clocks running. 130 */ 131 void 132 initclocks() 133 { 134 int i; 135 136 #ifdef __HAVE_GENERIC_SOFT_INTERRUPTS 137 softclock_si = softintr_establish(IPL_SOFTCLOCK, generic_softclock, NULL); 138 if (softclock_si == NULL) 139 panic("initclocks: unable to register softclock intr"); 140 #endif 141 142 /* 143 * Set divisors to 1 (normal case) and let the machine-specific 144 * code do its bit. 145 */ 146 psdiv = pscnt = 1; 147 cpu_initclocks(); 148 149 /* 150 * Compute profhz/stathz, and fix profhz if needed. 151 */ 152 i = stathz ? stathz : hz; 153 if (profhz == 0) 154 profhz = i; 155 psratio = profhz / i; 156 } 157 158 /* 159 * The real-time timer, interrupting hz times per second. 160 */ 161 void 162 hardclock(frame) 163 register struct clockframe *frame; 164 { 165 register struct proc *p; 166 register int delta; 167 extern int tickdelta; 168 extern long timedelta; 169 170 p = curproc; 171 if (p) { 172 register struct pstats *pstats; 173 174 /* 175 * Run current process's virtual and profile time, as needed. 176 */ 177 pstats = p->p_stats; 178 if (CLKF_USERMODE(frame) && 179 timerisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value) && 180 itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL], tick) == 0) 181 psignal(p, SIGVTALRM); 182 if (timerisset(&pstats->p_timer[ITIMER_PROF].it_value) && 183 itimerdecr(&pstats->p_timer[ITIMER_PROF], tick) == 0) 184 psignal(p, SIGPROF); 185 } 186 187 /* 188 * If no separate statistics clock is available, run it from here. 189 */ 190 if (stathz == 0) 191 statclock(frame); 192 193 /* 194 * Increment the time-of-day. The increment is normally just 195 * ``tick''. If the machine is one which has a clock frequency 196 * such that ``hz'' would not divide the second evenly into 197 * milliseconds, a periodic adjustment must be applied. Finally, 198 * if we are still adjusting the time (see adjtime()), 199 * ``tickdelta'' may also be added in. 200 */ 201 ticks++; 202 delta = tick; 203 204 if (tickfix) { 205 tickfixcnt += tickfix; 206 if (tickfixcnt >= tickfixinterval) { 207 delta++; 208 tickfixcnt -= tickfixinterval; 209 } 210 } 211 /* Imprecise 4bsd adjtime() handling */ 212 if (timedelta != 0) { 213 delta += tickdelta; 214 timedelta -= tickdelta; 215 } 216 217 #ifdef notyet 218 microset(); 219 #endif 220 221 BUMPTIME(&time, delta); 222 BUMPTIME(&mono_time, delta); 223 224 #ifdef CPU_CLOCKUPDATE 225 CPU_CLOCKUPDATE(); 226 #endif 227 228 /* 229 * Update real-time timeout queue. 230 * Process callouts at a very low cpu priority, so we don't keep the 231 * relatively high clock interrupt priority any longer than necessary. 232 */ 233 if (timeout_hardclock_update()) { 234 #ifdef __HAVE_GENERIC_SOFT_INTERRUPTS 235 softintr_schedule(softclock_si); 236 #else 237 setsoftclock(); 238 #endif 239 } 240 } 241 242 /* 243 * Compute number of hz until specified time. Used to 244 * compute the second argument to timeout_add() from an absolute time. 245 */ 246 int 247 hzto(tv) 248 struct timeval *tv; 249 { 250 unsigned long ticks; 251 long sec, usec; 252 int s; 253 254 /* 255 * If the number of usecs in the whole seconds part of the time 256 * difference fits in a long, then the total number of usecs will 257 * fit in an unsigned long. Compute the total and convert it to 258 * ticks, rounding up and adding 1 to allow for the current tick 259 * to expire. Rounding also depends on unsigned long arithmetic 260 * to avoid overflow. 261 * 262 * Otherwise, if the number of ticks in the whole seconds part of 263 * the time difference fits in a long, then convert the parts to 264 * ticks separately and add, using similar rounding methods and 265 * overflow avoidance. This method would work in the previous 266 * case but it is slightly slower and assumes that hz is integral. 267 * 268 * Otherwise, round the time difference down to the maximum 269 * representable value. 270 * 271 * If ints have 32 bits, then the maximum value for any timeout in 272 * 10ms ticks is 248 days. 273 */ 274 s = splhigh(); 275 sec = tv->tv_sec - time.tv_sec; 276 usec = tv->tv_usec - time.tv_usec; 277 splx(s); 278 if (usec < 0) { 279 sec--; 280 usec += 1000000; 281 } 282 if (sec < 0 || (sec == 0 && usec <= 0)) { 283 ticks = 0; 284 } else if (sec <= LONG_MAX / 1000000) 285 ticks = (sec * 1000000 + (unsigned long)usec + (tick - 1)) 286 / tick + 1; 287 else if (sec <= LONG_MAX / hz) 288 ticks = sec * hz 289 + ((unsigned long)usec + (tick - 1)) / tick + 1; 290 else 291 ticks = LONG_MAX; 292 if (ticks > INT_MAX) 293 ticks = INT_MAX; 294 return ((int)ticks); 295 } 296 297 /* 298 * Compute number of hz in the specified amount of time. 299 */ 300 int 301 tvtohz(struct timeval *tv) 302 { 303 unsigned long ticks; 304 long sec, usec; 305 306 /* 307 * If the number of usecs in the whole seconds part of the time 308 * fits in a long, then the total number of usecs will 309 * fit in an unsigned long. Compute the total and convert it to 310 * ticks, rounding up and adding 1 to allow for the current tick 311 * to expire. Rounding also depends on unsigned long arithmetic 312 * to avoid overflow. 313 * 314 * Otherwise, if the number of ticks in the whole seconds part of 315 * the time fits in a long, then convert the parts to 316 * ticks separately and add, using similar rounding methods and 317 * overflow avoidance. This method would work in the previous 318 * case but it is slightly slower and assumes that hz is integral. 319 * 320 * Otherwise, round the time down to the maximum 321 * representable value. 322 * 323 * If ints have 32 bits, then the maximum value for any timeout in 324 * 10ms ticks is 248 days. 325 */ 326 sec = tv->tv_sec; 327 usec = tv->tv_usec; 328 if (sec < 0 || (sec == 0 && usec <= 0)) 329 ticks = 0; 330 else if (sec <= LONG_MAX / 1000000) 331 ticks = (sec * 1000000 + (unsigned long)usec + (tick - 1)) 332 / tick + 1; 333 else if (sec <= LONG_MAX / hz) 334 ticks = sec * hz 335 + ((unsigned long)usec + (tick - 1)) / tick + 1; 336 else 337 ticks = LONG_MAX; 338 if (ticks > INT_MAX) 339 ticks = INT_MAX; 340 return ((int)ticks); 341 } 342 343 /* 344 * Start profiling on a process. 345 * 346 * Kernel profiling passes proc0 which never exits and hence 347 * keeps the profile clock running constantly. 348 */ 349 void 350 startprofclock(p) 351 register struct proc *p; 352 { 353 int s; 354 355 if ((p->p_flag & P_PROFIL) == 0) { 356 p->p_flag |= P_PROFIL; 357 if (++profprocs == 1 && stathz != 0) { 358 s = splstatclock(); 359 psdiv = pscnt = psratio; 360 setstatclockrate(profhz); 361 splx(s); 362 } 363 } 364 } 365 366 /* 367 * Stop profiling on a process. 368 */ 369 void 370 stopprofclock(p) 371 register struct proc *p; 372 { 373 int s; 374 375 if (p->p_flag & P_PROFIL) { 376 p->p_flag &= ~P_PROFIL; 377 if (--profprocs == 0 && stathz != 0) { 378 s = splstatclock(); 379 psdiv = pscnt = 1; 380 setstatclockrate(stathz); 381 splx(s); 382 } 383 } 384 } 385 386 /* 387 * Statistics clock. Grab profile sample, and if divider reaches 0, 388 * do process and kernel statistics. 389 */ 390 void 391 statclock(frame) 392 register struct clockframe *frame; 393 { 394 #ifdef GPROF 395 register struct gmonparam *g; 396 register int i; 397 #endif 398 static int schedclk; 399 register struct proc *p; 400 401 if (CLKF_USERMODE(frame)) { 402 p = curproc; 403 if (p->p_flag & P_PROFIL) 404 addupc_intr(p, CLKF_PC(frame)); 405 if (--pscnt > 0) 406 return; 407 /* 408 * Came from user mode; CPU was in user state. 409 * If this process is being profiled record the tick. 410 */ 411 p->p_uticks++; 412 if (p->p_nice > NZERO) 413 cp_time[CP_NICE]++; 414 else 415 cp_time[CP_USER]++; 416 } else { 417 #ifdef GPROF 418 /* 419 * Kernel statistics are just like addupc_intr, only easier. 420 */ 421 g = &_gmonparam; 422 if (g->state == GMON_PROF_ON) { 423 i = CLKF_PC(frame) - g->lowpc; 424 if (i < g->textsize) { 425 i /= HISTFRACTION * sizeof(*g->kcount); 426 g->kcount[i]++; 427 } 428 } 429 #endif 430 if (--pscnt > 0) 431 return; 432 /* 433 * Came from kernel mode, so we were: 434 * - handling an interrupt, 435 * - doing syscall or trap work on behalf of the current 436 * user process, or 437 * - spinning in the idle loop. 438 * Whichever it is, charge the time as appropriate. 439 * Note that we charge interrupts to the current process, 440 * regardless of whether they are ``for'' that process, 441 * so that we know how much of its real time was spent 442 * in ``non-process'' (i.e., interrupt) work. 443 */ 444 p = curproc; 445 if (CLKF_INTR(frame)) { 446 if (p != NULL) 447 p->p_iticks++; 448 cp_time[CP_INTR]++; 449 } else if (p != NULL) { 450 p->p_sticks++; 451 cp_time[CP_SYS]++; 452 } else 453 cp_time[CP_IDLE]++; 454 } 455 pscnt = psdiv; 456 457 if (p != NULL) { 458 p->p_cpticks++; 459 /* 460 * If no schedclock is provided, call it here at ~~12-25 Hz; 461 * ~~16 Hz is best 462 */ 463 if (schedhz == 0) 464 if ((++schedclk & 3) == 0) 465 schedclock(p); 466 } 467 } 468 469 /* 470 * Return information about system clocks. 471 */ 472 int 473 sysctl_clockrate(where, sizep) 474 register char *where; 475 size_t *sizep; 476 { 477 struct clockinfo clkinfo; 478 479 /* 480 * Construct clockinfo structure. 481 */ 482 clkinfo.tick = tick; 483 clkinfo.tickadj = tickadj; 484 clkinfo.hz = hz; 485 clkinfo.profhz = profhz; 486 clkinfo.stathz = stathz ? stathz : hz; 487 return (sysctl_rdstruct(where, sizep, NULL, &clkinfo, sizeof(clkinfo))); 488 } 489