1 /* $OpenBSD: kern_clock.c,v 1.45 2004/06/21 23:50:35 tholo 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 time_t time_second; 110 volatile time_t time_uptime; 111 112 volatile struct timeval time 113 __attribute__((__aligned__(__alignof__(quad_t)))); 114 volatile struct timeval mono_time; 115 116 #ifdef __HAVE_GENERIC_SOFT_INTERRUPTS 117 void *softclock_si; 118 void generic_softclock(void *); 119 120 void 121 generic_softclock(void *ignore) 122 { 123 /* 124 * XXX - dont' commit, just a dummy wrapper until we learn everyone 125 * deal with a changed proto for softclock(). 126 */ 127 softclock(); 128 } 129 #endif 130 131 /* 132 * Initialize clock frequencies and start both clocks running. 133 */ 134 void 135 initclocks() 136 { 137 int i; 138 139 #ifdef __HAVE_GENERIC_SOFT_INTERRUPTS 140 softclock_si = softintr_establish(IPL_SOFTCLOCK, generic_softclock, NULL); 141 if (softclock_si == NULL) 142 panic("initclocks: unable to register softclock intr"); 143 #endif 144 145 /* 146 * Set divisors to 1 (normal case) and let the machine-specific 147 * code do its bit. 148 */ 149 psdiv = pscnt = 1; 150 cpu_initclocks(); 151 152 /* 153 * Compute profhz/stathz, and fix profhz if needed. 154 */ 155 i = stathz ? stathz : hz; 156 if (profhz == 0) 157 profhz = i; 158 psratio = profhz / i; 159 } 160 161 /* 162 * The real-time timer, interrupting hz times per second. 163 */ 164 void 165 hardclock(struct clockframe *frame) 166 { 167 struct proc *p; 168 int delta; 169 extern int tickdelta; 170 extern long timedelta; 171 #ifdef __HAVE_CPUINFO 172 struct cpu_info *ci = curcpu(); 173 #endif 174 175 p = curproc; 176 if (p) { 177 register struct pstats *pstats; 178 179 /* 180 * Run current process's virtual and profile time, as needed. 181 */ 182 pstats = p->p_stats; 183 if (CLKF_USERMODE(frame) && 184 timerisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value) && 185 itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL], tick) == 0) 186 psignal(p, SIGVTALRM); 187 if (timerisset(&pstats->p_timer[ITIMER_PROF].it_value) && 188 itimerdecr(&pstats->p_timer[ITIMER_PROF], tick) == 0) 189 psignal(p, SIGPROF); 190 } 191 192 /* 193 * If no separate statistics clock is available, run it from here. 194 */ 195 if (stathz == 0) 196 statclock(frame); 197 198 #if defined(__HAVE_CPUINFO) 199 if (--ci->ci_schedstate.spc_rrticks <= 0) 200 roundrobin(ci); 201 202 /* 203 * If we are not the primary CPU, we're not allowed to do 204 * any more work. 205 */ 206 if (CPU_IS_PRIMARY(ci) == 0) 207 return; 208 #endif 209 210 /* 211 * Increment the time-of-day. The increment is normally just 212 * ``tick''. If the machine is one which has a clock frequency 213 * such that ``hz'' would not divide the second evenly into 214 * milliseconds, a periodic adjustment must be applied. Finally, 215 * if we are still adjusting the time (see adjtime()), 216 * ``tickdelta'' may also be added in. 217 */ 218 ticks++; 219 delta = tick; 220 221 if (tickfix) { 222 tickfixcnt += tickfix; 223 if (tickfixcnt >= tickfixinterval) { 224 delta++; 225 tickfixcnt -= tickfixinterval; 226 } 227 } 228 /* Imprecise 4bsd adjtime() handling */ 229 if (timedelta != 0) { 230 delta += tickdelta; 231 timedelta -= tickdelta; 232 } 233 234 #ifdef notyet 235 microset(); 236 #endif 237 238 BUMPTIME(&time, delta); 239 BUMPTIME(&mono_time, delta); 240 time_second = time.tv_sec; 241 time_uptime = mono_time.tv_sec; 242 243 #ifdef CPU_CLOCKUPDATE 244 CPU_CLOCKUPDATE(); 245 #endif 246 247 /* 248 * Update real-time timeout queue. 249 * Process callouts at a very low cpu priority, so we don't keep the 250 * relatively high clock interrupt priority any longer than necessary. 251 */ 252 if (timeout_hardclock_update()) { 253 #ifdef __HAVE_GENERIC_SOFT_INTERRUPTS 254 softintr_schedule(softclock_si); 255 #else 256 setsoftclock(); 257 #endif 258 } 259 } 260 261 /* 262 * Compute number of hz until specified time. Used to 263 * compute the second argument to timeout_add() from an absolute time. 264 */ 265 int 266 hzto(tv) 267 struct timeval *tv; 268 { 269 unsigned long ticks; 270 long sec, usec; 271 int s; 272 273 /* 274 * If the number of usecs in the whole seconds part of the time 275 * difference fits in a long, then the total number of usecs will 276 * fit in an unsigned long. Compute the total and convert it to 277 * ticks, rounding up and adding 1 to allow for the current tick 278 * to expire. Rounding also depends on unsigned long arithmetic 279 * to avoid overflow. 280 * 281 * Otherwise, if the number of ticks in the whole seconds part of 282 * the time difference fits in a long, then convert the parts to 283 * ticks separately and add, using similar rounding methods and 284 * overflow avoidance. This method would work in the previous 285 * case but it is slightly slower and assumes that hz is integral. 286 * 287 * Otherwise, round the time difference down to the maximum 288 * representable value. 289 * 290 * If ints have 32 bits, then the maximum value for any timeout in 291 * 10ms ticks is 248 days. 292 */ 293 s = splhigh(); 294 sec = tv->tv_sec - time.tv_sec; 295 usec = tv->tv_usec - time.tv_usec; 296 splx(s); 297 if (usec < 0) { 298 sec--; 299 usec += 1000000; 300 } 301 if (sec < 0 || (sec == 0 && usec <= 0)) { 302 ticks = 0; 303 } else if (sec <= LONG_MAX / 1000000) 304 ticks = (sec * 1000000 + (unsigned long)usec + (tick - 1)) 305 / tick + 1; 306 else if (sec <= LONG_MAX / hz) 307 ticks = sec * hz 308 + ((unsigned long)usec + (tick - 1)) / tick + 1; 309 else 310 ticks = LONG_MAX; 311 if (ticks > INT_MAX) 312 ticks = INT_MAX; 313 return ((int)ticks); 314 } 315 316 /* 317 * Compute number of hz in the specified amount of time. 318 */ 319 int 320 tvtohz(struct timeval *tv) 321 { 322 unsigned long ticks; 323 long sec, usec; 324 325 /* 326 * If the number of usecs in the whole seconds part of the time 327 * fits in a long, then the total number of usecs will 328 * fit in an unsigned long. Compute the total and convert it to 329 * ticks, rounding up and adding 1 to allow for the current tick 330 * to expire. Rounding also depends on unsigned long arithmetic 331 * to avoid overflow. 332 * 333 * Otherwise, if the number of ticks in the whole seconds part of 334 * the time fits in a long, then convert the parts to 335 * ticks separately and add, using similar rounding methods and 336 * overflow avoidance. This method would work in the previous 337 * case but it is slightly slower and assumes that hz is integral. 338 * 339 * Otherwise, round the time down to the maximum 340 * representable value. 341 * 342 * If ints have 32 bits, then the maximum value for any timeout in 343 * 10ms ticks is 248 days. 344 */ 345 sec = tv->tv_sec; 346 usec = tv->tv_usec; 347 if (sec < 0 || (sec == 0 && usec <= 0)) 348 ticks = 0; 349 else if (sec <= LONG_MAX / 1000000) 350 ticks = (sec * 1000000 + (unsigned long)usec + (tick - 1)) 351 / tick + 1; 352 else if (sec <= LONG_MAX / hz) 353 ticks = sec * hz 354 + ((unsigned long)usec + (tick - 1)) / tick + 1; 355 else 356 ticks = LONG_MAX; 357 if (ticks > INT_MAX) 358 ticks = INT_MAX; 359 return ((int)ticks); 360 } 361 362 /* 363 * Start profiling on a process. 364 * 365 * Kernel profiling passes proc0 which never exits and hence 366 * keeps the profile clock running constantly. 367 */ 368 void 369 startprofclock(p) 370 register struct proc *p; 371 { 372 int s; 373 374 if ((p->p_flag & P_PROFIL) == 0) { 375 p->p_flag |= P_PROFIL; 376 if (++profprocs == 1 && stathz != 0) { 377 s = splstatclock(); 378 psdiv = pscnt = psratio; 379 setstatclockrate(profhz); 380 splx(s); 381 } 382 } 383 } 384 385 /* 386 * Stop profiling on a process. 387 */ 388 void 389 stopprofclock(p) 390 register struct proc *p; 391 { 392 int s; 393 394 if (p->p_flag & P_PROFIL) { 395 p->p_flag &= ~P_PROFIL; 396 if (--profprocs == 0 && stathz != 0) { 397 s = splstatclock(); 398 psdiv = pscnt = 1; 399 setstatclockrate(stathz); 400 splx(s); 401 } 402 } 403 } 404 405 /* 406 * Statistics clock. Grab profile sample, and if divider reaches 0, 407 * do process and kernel statistics. 408 */ 409 void 410 statclock(struct clockframe *frame) 411 { 412 #ifdef GPROF 413 struct gmonparam *g; 414 int i; 415 #endif 416 #ifdef __HAVE_CPUINFO 417 struct cpu_info *ci = curcpu(); 418 struct schedstate_percpu *spc = &ci->ci_schedstate; 419 #else 420 static int schedclk; 421 #endif 422 struct proc *p = curproc; 423 424 #ifdef __HAVE_CPUINFO 425 /* 426 * Notice changes in divisor frequency, and adjust clock 427 * frequency accordingly. 428 */ 429 if (spc->spc_psdiv != psdiv) { 430 spc->spc_psdiv = psdiv; 431 spc->spc_pscnt = psdiv; 432 if (psdiv == 1) { 433 setstatclockrate(stathz); 434 } else { 435 setstatclockrate(profhz); 436 } 437 } 438 439 /* XXX Kludgey */ 440 #define pscnt spc->spc_pscnt 441 #define cp_time spc->spc_cp_time 442 #endif 443 444 if (CLKF_USERMODE(frame)) { 445 if (p->p_flag & P_PROFIL) 446 addupc_intr(p, CLKF_PC(frame)); 447 if (--pscnt > 0) 448 return; 449 /* 450 * Came from user mode; CPU was in user state. 451 * If this process is being profiled record the tick. 452 */ 453 p->p_uticks++; 454 if (p->p_nice > NZERO) 455 cp_time[CP_NICE]++; 456 else 457 cp_time[CP_USER]++; 458 } else { 459 #ifdef GPROF 460 /* 461 * Kernel statistics are just like addupc_intr, only easier. 462 */ 463 g = &_gmonparam; 464 if (g->state == GMON_PROF_ON) { 465 i = CLKF_PC(frame) - g->lowpc; 466 if (i < g->textsize) { 467 i /= HISTFRACTION * sizeof(*g->kcount); 468 g->kcount[i]++; 469 } 470 } 471 #endif 472 if (--pscnt > 0) 473 return; 474 /* 475 * Came from kernel mode, so we were: 476 * - handling an interrupt, 477 * - doing syscall or trap work on behalf of the current 478 * user process, or 479 * - spinning in the idle loop. 480 * Whichever it is, charge the time as appropriate. 481 * Note that we charge interrupts to the current process, 482 * regardless of whether they are ``for'' that process, 483 * so that we know how much of its real time was spent 484 * in ``non-process'' (i.e., interrupt) work. 485 */ 486 if (CLKF_INTR(frame)) { 487 if (p != NULL) 488 p->p_iticks++; 489 cp_time[CP_INTR]++; 490 } else if (p != NULL) { 491 p->p_sticks++; 492 cp_time[CP_SYS]++; 493 } else 494 cp_time[CP_IDLE]++; 495 } 496 pscnt = psdiv; 497 498 #ifdef __HAVE_CPUINFO 499 #undef psdiv 500 #undef cp_time 501 #endif 502 503 if (p != NULL) { 504 p->p_cpticks++; 505 /* 506 * If no schedclock is provided, call it here at ~~12-25 Hz; 507 * ~~16 Hz is best 508 */ 509 if (schedhz == 0) { 510 #ifdef __HAVE_CPUINFO 511 if ((++curcpu()->ci_schedstate.spc_schedticks & 3) == 512 0) 513 schedclock(p); 514 #else 515 if ((++schedclk & 3) == 0) 516 schedclock(p); 517 #endif 518 } 519 } 520 } 521 522 /* 523 * Return information about system clocks. 524 */ 525 int 526 sysctl_clockrate(where, sizep) 527 register char *where; 528 size_t *sizep; 529 { 530 struct clockinfo clkinfo; 531 532 /* 533 * Construct clockinfo structure. 534 */ 535 clkinfo.tick = tick; 536 clkinfo.tickadj = tickadj; 537 clkinfo.hz = hz; 538 clkinfo.profhz = profhz; 539 clkinfo.stathz = stathz ? stathz : hz; 540 return (sysctl_rdstruct(where, sizep, NULL, &clkinfo, sizeof(clkinfo))); 541 } 542