1 /* $OpenBSD: kern_clock.c,v 1.79 2013/03/12 09:37:16 mpi 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/user.h> 48 #include <sys/resourcevar.h> 49 #include <sys/signalvar.h> 50 #include <uvm/uvm_extern.h> 51 #include <sys/sysctl.h> 52 #include <sys/sched.h> 53 #include <sys/timetc.h> 54 55 #include <machine/cpu.h> 56 57 #ifdef GPROF 58 #include <sys/gmon.h> 59 #endif 60 61 /* 62 * Clock handling routines. 63 * 64 * This code is written to operate with two timers that run independently of 65 * each other. The main clock, running hz times per second, is used to keep 66 * track of real time. The second timer handles kernel and user profiling, 67 * and does resource use estimation. If the second timer is programmable, 68 * it is randomized to avoid aliasing between the two clocks. For example, 69 * the randomization prevents an adversary from always giving up the cpu 70 * just before its quantum expires. Otherwise, it would never accumulate 71 * cpu ticks. The mean frequency of the second timer is stathz. 72 * 73 * If no second timer exists, stathz will be zero; in this case we drive 74 * profiling and statistics off the main clock. This WILL NOT be accurate; 75 * do not do it unless absolutely necessary. 76 * 77 * The statistics clock may (or may not) be run at a higher rate while 78 * profiling. This profile clock runs at profhz. We require that profhz 79 * be an integral multiple of stathz. 80 * 81 * If the statistics clock is running fast, it must be divided by the ratio 82 * profhz/stathz for statistics. (For profiling, every tick counts.) 83 */ 84 85 /* 86 * Bump a timeval by a small number of usec's. 87 */ 88 #define BUMPTIME(t, usec) { \ 89 volatile struct timeval *tp = (t); \ 90 long us; \ 91 \ 92 tp->tv_usec = us = tp->tv_usec + (usec); \ 93 if (us >= 1000000) { \ 94 tp->tv_usec = us - 1000000; \ 95 tp->tv_sec++; \ 96 } \ 97 } 98 99 int stathz; 100 int schedhz; 101 int profhz; 102 int profprocs; 103 int ticks; 104 static int psdiv, pscnt; /* prof => stat divider */ 105 int psratio; /* ratio: prof / stat */ 106 107 long cp_time[CPUSTATES]; 108 109 void *softclock_si; 110 111 /* 112 * Initialize clock frequencies and start both clocks running. 113 */ 114 void 115 initclocks(void) 116 { 117 int i; 118 119 softclock_si = softintr_establish(IPL_SOFTCLOCK, softclock, NULL); 120 if (softclock_si == NULL) 121 panic("initclocks: unable to register softclock intr"); 122 123 /* 124 * Set divisors to 1 (normal case) and let the machine-specific 125 * code do its bit. 126 */ 127 psdiv = pscnt = 1; 128 cpu_initclocks(); 129 130 /* 131 * Compute profhz/stathz, and fix profhz if needed. 132 */ 133 i = stathz ? stathz : hz; 134 if (profhz == 0) 135 profhz = i; 136 psratio = profhz / i; 137 138 /* For very large HZ, ensure that division by 0 does not occur later */ 139 if (tickadj == 0) 140 tickadj = 1; 141 142 inittimecounter(); 143 } 144 145 /* 146 * hardclock does the accounting needed for ITIMER_PROF and ITIMER_VIRTUAL. 147 * We don't want to send signals with psignal from hardclock because it makes 148 * MULTIPROCESSOR locking very complicated. Instead we use a small trick 149 * to send the signals safely and without blocking too many interrupts 150 * while doing that (signal handling can be heavy). 151 * 152 * hardclock detects that the itimer has expired, and schedules a timeout 153 * to deliver the signal. This works because of the following reasons: 154 * - The timeout can be scheduled with a 1 tick time because we're 155 * doing it before the timeout processing in hardclock. So it will 156 * be scheduled to run as soon as possible. 157 * - The timeout will be run in softclock which will run before we 158 * return to userland and process pending signals. 159 * - If the system is so busy that several VIRTUAL/PROF ticks are 160 * sent before softclock processing, we'll send only one signal. 161 * But if we'd send the signal from hardclock only one signal would 162 * be delivered to the user process. So userland will only see one 163 * signal anyway. 164 */ 165 166 void 167 virttimer_trampoline(void *v) 168 { 169 struct process *pr = v; 170 171 psignal(pr->ps_mainproc, SIGVTALRM); 172 } 173 174 void 175 proftimer_trampoline(void *v) 176 { 177 struct process *pr = v; 178 179 psignal(pr->ps_mainproc, SIGPROF); 180 } 181 182 /* 183 * The real-time timer, interrupting hz times per second. 184 */ 185 void 186 hardclock(struct clockframe *frame) 187 { 188 struct proc *p; 189 struct cpu_info *ci = curcpu(); 190 191 p = curproc; 192 if (p && ((p->p_flag & (P_SYSTEM | P_WEXIT)) == 0)) { 193 struct process *pr = p->p_p; 194 195 /* 196 * Run current process's virtual and profile time, as needed. 197 */ 198 if (CLKF_USERMODE(frame) && 199 timerisset(&pr->ps_timer[ITIMER_VIRTUAL].it_value) && 200 itimerdecr(&pr->ps_timer[ITIMER_VIRTUAL], tick) == 0) 201 timeout_add(&pr->ps_virt_to, 1); 202 if (timerisset(&pr->ps_timer[ITIMER_PROF].it_value) && 203 itimerdecr(&pr->ps_timer[ITIMER_PROF], tick) == 0) 204 timeout_add(&pr->ps_prof_to, 1); 205 } 206 207 /* 208 * If no separate statistics clock is available, run it from here. 209 */ 210 if (stathz == 0) 211 statclock(frame); 212 213 if (--ci->ci_schedstate.spc_rrticks <= 0) 214 roundrobin(ci); 215 216 /* 217 * If we are not the primary CPU, we're not allowed to do 218 * any more work. 219 */ 220 if (CPU_IS_PRIMARY(ci) == 0) 221 return; 222 223 tc_ticktock(); 224 225 /* 226 * Update real-time timeout queue. 227 * Process callouts at a very low cpu priority, so we don't keep the 228 * relatively high clock interrupt priority any longer than necessary. 229 */ 230 if (timeout_hardclock_update()) 231 softintr_schedule(softclock_si); 232 } 233 234 /* 235 * Compute number of hz until specified time. Used to 236 * compute the second argument to timeout_add() from an absolute time. 237 */ 238 int 239 hzto(const struct timeval *tv) 240 { 241 struct timeval now; 242 unsigned long ticks; 243 long sec, usec; 244 245 /* 246 * If the number of usecs in the whole seconds part of the time 247 * difference fits in a long, then the total number of usecs will 248 * fit in an unsigned long. Compute the total and convert it to 249 * ticks, rounding up and adding 1 to allow for the current tick 250 * to expire. Rounding also depends on unsigned long arithmetic 251 * to avoid overflow. 252 * 253 * Otherwise, if the number of ticks in the whole seconds part of 254 * the time difference fits in a long, then convert the parts to 255 * ticks separately and add, using similar rounding methods and 256 * overflow avoidance. This method would work in the previous 257 * case but it is slightly slower and assumes that hz is integral. 258 * 259 * Otherwise, round the time difference down to the maximum 260 * representable value. 261 * 262 * If ints have 32 bits, then the maximum value for any timeout in 263 * 10ms ticks is 248 days. 264 */ 265 getmicrotime(&now); 266 sec = tv->tv_sec - now.tv_sec; 267 usec = tv->tv_usec - now.tv_usec; 268 if (usec < 0) { 269 sec--; 270 usec += 1000000; 271 } 272 if (sec < 0 || (sec == 0 && usec <= 0)) { 273 ticks = 0; 274 } else if (sec <= LONG_MAX / 1000000) 275 ticks = (sec * 1000000 + (unsigned long)usec + (tick - 1)) 276 / tick + 1; 277 else if (sec <= LONG_MAX / hz) 278 ticks = sec * hz 279 + ((unsigned long)usec + (tick - 1)) / tick + 1; 280 else 281 ticks = LONG_MAX; 282 if (ticks > INT_MAX) 283 ticks = INT_MAX; 284 return ((int)ticks); 285 } 286 287 /* 288 * Compute number of hz in the specified amount of time. 289 */ 290 int 291 tvtohz(const struct timeval *tv) 292 { 293 unsigned long ticks; 294 long sec, usec; 295 296 /* 297 * If the number of usecs in the whole seconds part of the time 298 * fits in a long, then the total number of usecs will 299 * fit in an unsigned long. Compute the total and convert it to 300 * ticks, rounding up and adding 1 to allow for the current tick 301 * to expire. Rounding also depends on unsigned long arithmetic 302 * to avoid overflow. 303 * 304 * Otherwise, if the number of ticks in the whole seconds part of 305 * the time fits in a long, then convert the parts to 306 * ticks separately and add, using similar rounding methods and 307 * overflow avoidance. This method would work in the previous 308 * case but it is slightly slower and assumes that hz is integral. 309 * 310 * Otherwise, round the time down to the maximum 311 * representable value. 312 * 313 * If ints have 32 bits, then the maximum value for any timeout in 314 * 10ms ticks is 248 days. 315 */ 316 sec = tv->tv_sec; 317 usec = tv->tv_usec; 318 if (sec < 0 || (sec == 0 && usec <= 0)) 319 ticks = 0; 320 else if (sec <= LONG_MAX / 1000000) 321 ticks = (sec * 1000000 + (unsigned long)usec + (tick - 1)) 322 / tick + 1; 323 else if (sec <= LONG_MAX / hz) 324 ticks = sec * hz 325 + ((unsigned long)usec + (tick - 1)) / tick + 1; 326 else 327 ticks = LONG_MAX; 328 if (ticks > INT_MAX) 329 ticks = INT_MAX; 330 return ((int)ticks); 331 } 332 333 /* 334 * Start profiling on a process. 335 * 336 * Kernel profiling passes proc0 which never exits and hence 337 * keeps the profile clock running constantly. 338 */ 339 void 340 startprofclock(struct process *pr) 341 { 342 int s; 343 344 if ((pr->ps_flags & PS_PROFIL) == 0) { 345 atomic_setbits_int(&pr->ps_flags, PS_PROFIL); 346 if (++profprocs == 1 && stathz != 0) { 347 s = splstatclock(); 348 psdiv = pscnt = psratio; 349 setstatclockrate(profhz); 350 splx(s); 351 } 352 } 353 } 354 355 /* 356 * Stop profiling on a process. 357 */ 358 void 359 stopprofclock(struct process *pr) 360 { 361 int s; 362 363 if (pr->ps_flags & PS_PROFIL) { 364 atomic_clearbits_int(&pr->ps_flags, PS_PROFIL); 365 if (--profprocs == 0 && stathz != 0) { 366 s = splstatclock(); 367 psdiv = pscnt = 1; 368 setstatclockrate(stathz); 369 splx(s); 370 } 371 } 372 } 373 374 /* 375 * Statistics clock. Grab profile sample, and if divider reaches 0, 376 * do process and kernel statistics. 377 */ 378 void 379 statclock(struct clockframe *frame) 380 { 381 #ifdef GPROF 382 struct gmonparam *g; 383 u_long i; 384 #endif 385 struct cpu_info *ci = curcpu(); 386 struct schedstate_percpu *spc = &ci->ci_schedstate; 387 struct proc *p = curproc; 388 struct process *pr; 389 390 /* 391 * Notice changes in divisor frequency, and adjust clock 392 * frequency accordingly. 393 */ 394 if (spc->spc_psdiv != psdiv) { 395 spc->spc_psdiv = psdiv; 396 spc->spc_pscnt = psdiv; 397 if (psdiv == 1) { 398 setstatclockrate(stathz); 399 } else { 400 setstatclockrate(profhz); 401 } 402 } 403 404 if (CLKF_USERMODE(frame)) { 405 pr = p->p_p; 406 if (pr->ps_flags & PS_PROFIL) 407 addupc_intr(p, CLKF_PC(frame)); 408 if (--spc->spc_pscnt > 0) 409 return; 410 /* 411 * Came from user mode; CPU was in user state. 412 * If this process is being profiled record the tick. 413 */ 414 p->p_uticks++; 415 if (pr->ps_nice > NZERO) 416 spc->spc_cp_time[CP_NICE]++; 417 else 418 spc->spc_cp_time[CP_USER]++; 419 } else { 420 #ifdef GPROF 421 /* 422 * Kernel statistics are just like addupc_intr, only easier. 423 */ 424 g = ci->ci_gmon; 425 if (g != NULL && g->state == GMON_PROF_ON) { 426 i = CLKF_PC(frame) - g->lowpc; 427 if (i < g->textsize) { 428 i /= HISTFRACTION * sizeof(*g->kcount); 429 g->kcount[i]++; 430 } 431 } 432 #endif 433 #if defined(PROC_PC) 434 if (p != NULL && p->p_p->ps_flags & PS_PROFIL) 435 addupc_intr(p, PROC_PC(p)); 436 #endif 437 if (--spc->spc_pscnt > 0) 438 return; 439 /* 440 * Came from kernel mode, so we were: 441 * - handling an interrupt, 442 * - doing syscall or trap work on behalf of the current 443 * user process, or 444 * - spinning in the idle loop. 445 * Whichever it is, charge the time as appropriate. 446 * Note that we charge interrupts to the current process, 447 * regardless of whether they are ``for'' that process, 448 * so that we know how much of its real time was spent 449 * in ``non-process'' (i.e., interrupt) work. 450 */ 451 if (CLKF_INTR(frame)) { 452 if (p != NULL) 453 p->p_iticks++; 454 spc->spc_cp_time[CP_INTR]++; 455 } else if (p != NULL && p != spc->spc_idleproc) { 456 p->p_sticks++; 457 spc->spc_cp_time[CP_SYS]++; 458 } else 459 spc->spc_cp_time[CP_IDLE]++; 460 } 461 spc->spc_pscnt = psdiv; 462 463 if (p != NULL) { 464 p->p_cpticks++; 465 /* 466 * If no schedclock is provided, call it here at ~~12-25 Hz; 467 * ~~16 Hz is best 468 */ 469 if (schedhz == 0) { 470 if ((++curcpu()->ci_schedstate.spc_schedticks & 3) == 471 0) 472 schedclock(p); 473 } 474 } 475 } 476 477 /* 478 * Return information about system clocks. 479 */ 480 int 481 sysctl_clockrate(char *where, size_t *sizep, void *newp) 482 { 483 struct clockinfo clkinfo; 484 485 /* 486 * Construct clockinfo structure. 487 */ 488 clkinfo.tick = tick; 489 clkinfo.tickadj = tickadj; 490 clkinfo.hz = hz; 491 clkinfo.profhz = profhz; 492 clkinfo.stathz = stathz ? stathz : hz; 493 return (sysctl_rdstruct(where, sizep, newp, &clkinfo, sizeof(clkinfo))); 494 } 495