kern_tc.c revision 31016
1/*- 2 * Copyright (c) 1982, 1986, 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * (c) UNIX System Laboratories, Inc. 5 * All or some portions of this file are derived from material licensed 6 * to the University of California by American Telephone and Telegraph 7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 8 * the permission of UNIX System Laboratories, Inc. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 * 38 * @(#)kern_clock.c 8.5 (Berkeley) 1/21/94 39 * $Id: kern_clock.c,v 1.42 1997/09/24 16:39:16 gibbs Exp $ 40 */ 41 42/* Portions of this software are covered by the following: */ 43/****************************************************************************** 44 * * 45 * Copyright (c) David L. Mills 1993, 1994 * 46 * * 47 * Permission to use, copy, modify, and distribute this software and its * 48 * documentation for any purpose and without fee is hereby granted, provided * 49 * that the above copyright notice appears in all copies and that both the * 50 * copyright notice and this permission notice appear in supporting * 51 * documentation, and that the name University of Delaware not be used in * 52 * advertising or publicity pertaining to distribution of the software * 53 * without specific, written prior permission. The University of Delaware * 54 * makes no representations about the suitability this software for any * 55 * purpose. It is provided "as is" without express or implied warranty. * 56 * * 57 *****************************************************************************/ 58 59#include "opt_cpu.h" /* XXX */ 60 61#include <sys/param.h> 62#include <sys/systm.h> 63#include <sys/dkstat.h> 64#include <sys/callout.h> 65#include <sys/kernel.h> 66#include <sys/proc.h> 67#include <sys/resourcevar.h> 68#include <sys/signalvar.h> 69#include <sys/timex.h> 70#include <vm/vm.h> 71#include <sys/lock.h> 72#include <vm/pmap.h> 73#include <vm/vm_map.h> 74#include <sys/sysctl.h> 75 76#include <machine/cpu.h> 77#define CLOCK_HAIR /* XXX */ 78#include <machine/clock.h> 79#include <machine/limits.h> 80 81#ifdef GPROF 82#include <sys/gmon.h> 83#endif 84 85static void initclocks __P((void *dummy)); 86SYSINIT(clocks, SI_SUB_CLOCKS, SI_ORDER_FIRST, initclocks, NULL) 87 88/* Exported to machdep.c. */ 89struct callout *callout; 90struct callout_list callfree; 91int callwheelsize, callwheelbits, callwheelmask; 92struct callout_tailq *callwheel; 93 94 95/* Some of these don't belong here, but it's easiest to concentrate them. */ 96static long cp_time[CPUSTATES]; 97long dk_seek[DK_NDRIVE]; 98static long dk_time[DK_NDRIVE]; /* time busy (in statclock ticks) */ 99long dk_wds[DK_NDRIVE]; 100long dk_wpms[DK_NDRIVE]; 101long dk_xfer[DK_NDRIVE]; 102 103int dk_busy; 104int dk_ndrive = 0; 105char dk_names[DK_NDRIVE][DK_NAMELEN]; 106 107long tk_cancc; 108long tk_nin; 109long tk_nout; 110long tk_rawcc; 111 112/* 113 * Clock handling routines. 114 * 115 * This code is written to operate with two timers that run independently of 116 * each other. The main clock, running hz times per second, is used to keep 117 * track of real time. The second timer handles kernel and user profiling, 118 * and does resource use estimation. If the second timer is programmable, 119 * it is randomized to avoid aliasing between the two clocks. For example, 120 * the randomization prevents an adversary from always giving up the cpu 121 * just before its quantum expires. Otherwise, it would never accumulate 122 * cpu ticks. The mean frequency of the second timer is stathz. 123 * 124 * If no second timer exists, stathz will be zero; in this case we drive 125 * profiling and statistics off the main clock. This WILL NOT be accurate; 126 * do not do it unless absolutely necessary. 127 * 128 * The statistics clock may (or may not) be run at a higher rate while 129 * profiling. This profile clock runs at profhz. We require that profhz 130 * be an integral multiple of stathz. 131 * 132 * If the statistics clock is running fast, it must be divided by the ratio 133 * profhz/stathz for statistics. (For profiling, every tick counts.) 134 */ 135 136/* 137 * TODO: 138 * allocate more timeout table slots when table overflows. 139 */ 140 141/* 142 * Bump a timeval by a small number of usec's. 143 */ 144#define BUMPTIME(t, usec) { \ 145 register volatile struct timeval *tp = (t); \ 146 register long us; \ 147 \ 148 tp->tv_usec = us = tp->tv_usec + (usec); \ 149 if (us >= 1000000) { \ 150 tp->tv_usec = us - 1000000; \ 151 tp->tv_sec++; \ 152 } \ 153} 154 155int stathz; 156int profhz; 157static int profprocs; 158int ticks; 159static int softticks; /* Like ticks, but for softclock(). */ 160static struct callout *nextsoftcheck; /* Next callout to be checked. */ 161static int psdiv, pscnt; /* prof => stat divider */ 162int psratio; /* ratio: prof / stat */ 163 164volatile struct timeval time; 165volatile struct timeval mono_time; 166 167/* 168 * Phase/frequency-lock loop (PLL/FLL) definitions 169 * 170 * The following variables are read and set by the ntp_adjtime() system 171 * call. 172 * 173 * time_state shows the state of the system clock, with values defined 174 * in the timex.h header file. 175 * 176 * time_status shows the status of the system clock, with bits defined 177 * in the timex.h header file. 178 * 179 * time_offset is used by the PLL/FLL to adjust the system time in small 180 * increments. 181 * 182 * time_constant determines the bandwidth or "stiffness" of the PLL. 183 * 184 * time_tolerance determines maximum frequency error or tolerance of the 185 * CPU clock oscillator and is a property of the architecture; however, 186 * in principle it could change as result of the presence of external 187 * discipline signals, for instance. 188 * 189 * time_precision is usually equal to the kernel tick variable; however, 190 * in cases where a precision clock counter or external clock is 191 * available, the resolution can be much less than this and depend on 192 * whether the external clock is working or not. 193 * 194 * time_maxerror is initialized by a ntp_adjtime() call and increased by 195 * the kernel once each second to reflect the maximum error 196 * bound growth. 197 * 198 * time_esterror is set and read by the ntp_adjtime() call, but 199 * otherwise not used by the kernel. 200 */ 201int time_status = STA_UNSYNC; /* clock status bits */ 202int time_state = TIME_OK; /* clock state */ 203long time_offset = 0; /* time offset (us) */ 204long time_constant = 0; /* pll time constant */ 205long time_tolerance = MAXFREQ; /* frequency tolerance (scaled ppm) */ 206long time_precision = 1; /* clock precision (us) */ 207long time_maxerror = MAXPHASE; /* maximum error (us) */ 208long time_esterror = MAXPHASE; /* estimated error (us) */ 209 210/* 211 * The following variables establish the state of the PLL/FLL and the 212 * residual time and frequency offset of the local clock. The scale 213 * factors are defined in the timex.h header file. 214 * 215 * time_phase and time_freq are the phase increment and the frequency 216 * increment, respectively, of the kernel time variable at each tick of 217 * the clock. 218 * 219 * time_freq is set via ntp_adjtime() from a value stored in a file when 220 * the synchronization daemon is first started. Its value is retrieved 221 * via ntp_adjtime() and written to the file about once per hour by the 222 * daemon. 223 * 224 * time_adj is the adjustment added to the value of tick at each timer 225 * interrupt and is recomputed from time_phase and time_freq at each 226 * seconds rollover. 227 * 228 * time_reftime is the second's portion of the system time on the last 229 * call to ntp_adjtime(). It is used to adjust the time_freq variable 230 * and to increase the time_maxerror as the time since last update 231 * increases. 232 */ 233static long time_phase = 0; /* phase offset (scaled us) */ 234long time_freq = 0; /* frequency offset (scaled ppm) */ 235static long time_adj = 0; /* tick adjust (scaled 1 / hz) */ 236static long time_reftime = 0; /* time at last adjustment (s) */ 237 238#ifdef PPS_SYNC 239/* 240 * The following variables are used only if the kernel PPS discipline 241 * code is configured (PPS_SYNC). The scale factors are defined in the 242 * timex.h header file. 243 * 244 * pps_time contains the time at each calibration interval, as read by 245 * microtime(). pps_count counts the seconds of the calibration 246 * interval, the duration of which is nominally pps_shift in powers of 247 * two. 248 * 249 * pps_offset is the time offset produced by the time median filter 250 * pps_tf[], while pps_jitter is the dispersion (jitter) measured by 251 * this filter. 252 * 253 * pps_freq is the frequency offset produced by the frequency median 254 * filter pps_ff[], while pps_stabil is the dispersion (wander) measured 255 * by this filter. 256 * 257 * pps_usec is latched from a high resolution counter or external clock 258 * at pps_time. Here we want the hardware counter contents only, not the 259 * contents plus the time_tv.usec as usual. 260 * 261 * pps_valid counts the number of seconds since the last PPS update. It 262 * is used as a watchdog timer to disable the PPS discipline should the 263 * PPS signal be lost. 264 * 265 * pps_glitch counts the number of seconds since the beginning of an 266 * offset burst more than tick/2 from current nominal offset. It is used 267 * mainly to suppress error bursts due to priority conflicts between the 268 * PPS interrupt and timer interrupt. 269 * 270 * pps_intcnt counts the calibration intervals for use in the interval- 271 * adaptation algorithm. It's just too complicated for words. 272 */ 273struct timeval pps_time; /* kernel time at last interval */ 274long pps_offset = 0; /* pps time offset (us) */ 275long pps_jitter = MAXTIME; /* pps time dispersion (jitter) (us) */ 276long pps_tf[] = {0, 0, 0}; /* pps time offset median filter (us) */ 277long pps_freq = 0; /* frequency offset (scaled ppm) */ 278long pps_stabil = MAXFREQ; /* frequency dispersion (scaled ppm) */ 279long pps_ff[] = {0, 0, 0}; /* frequency offset median filter */ 280long pps_usec = 0; /* microsec counter at last interval */ 281long pps_valid = PPS_VALID; /* pps signal watchdog counter */ 282int pps_glitch = 0; /* pps signal glitch counter */ 283int pps_count = 0; /* calibration interval counter (s) */ 284int pps_shift = PPS_SHIFT; /* interval duration (s) (shift) */ 285int pps_intcnt = 0; /* intervals at current duration */ 286 287/* 288 * PPS signal quality monitors 289 * 290 * pps_jitcnt counts the seconds that have been discarded because the 291 * jitter measured by the time median filter exceeds the limit MAXTIME 292 * (100 us). 293 * 294 * pps_calcnt counts the frequency calibration intervals, which are 295 * variable from 4 s to 256 s. 296 * 297 * pps_errcnt counts the calibration intervals which have been discarded 298 * because the wander exceeds the limit MAXFREQ (100 ppm) or where the 299 * calibration interval jitter exceeds two ticks. 300 * 301 * pps_stbcnt counts the calibration intervals that have been discarded 302 * because the frequency wander exceeds the limit MAXFREQ / 4 (25 us). 303 */ 304long pps_jitcnt = 0; /* jitter limit exceeded */ 305long pps_calcnt = 0; /* calibration intervals */ 306long pps_errcnt = 0; /* calibration errors */ 307long pps_stbcnt = 0; /* stability limit exceeded */ 308#endif /* PPS_SYNC */ 309 310/* XXX none of this stuff works under FreeBSD */ 311#ifdef EXT_CLOCK 312/* 313 * External clock definitions 314 * 315 * The following definitions and declarations are used only if an 316 * external clock (HIGHBALL or TPRO) is configured on the system. 317 */ 318#define CLOCK_INTERVAL 30 /* CPU clock update interval (s) */ 319 320/* 321 * The clock_count variable is set to CLOCK_INTERVAL at each PPS 322 * interrupt and decremented once each second. 323 */ 324int clock_count = 0; /* CPU clock counter */ 325 326#ifdef HIGHBALL 327/* 328 * The clock_offset and clock_cpu variables are used by the HIGHBALL 329 * interface. The clock_offset variable defines the offset between 330 * system time and the HIGBALL counters. The clock_cpu variable contains 331 * the offset between the system clock and the HIGHBALL clock for use in 332 * disciplining the kernel time variable. 333 */ 334extern struct timeval clock_offset; /* Highball clock offset */ 335long clock_cpu = 0; /* CPU clock adjust */ 336#endif /* HIGHBALL */ 337#endif /* EXT_CLOCK */ 338 339/* 340 * hardupdate() - local clock update 341 * 342 * This routine is called by ntp_adjtime() to update the local clock 343 * phase and frequency. The implementation is of an adaptive-parameter, 344 * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new 345 * time and frequency offset estimates for each call. If the kernel PPS 346 * discipline code is configured (PPS_SYNC), the PPS signal itself 347 * determines the new time offset, instead of the calling argument. 348 * Presumably, calls to ntp_adjtime() occur only when the caller 349 * believes the local clock is valid within some bound (+-128 ms with 350 * NTP). If the caller's time is far different than the PPS time, an 351 * argument will ensue, and it's not clear who will lose. 352 * 353 * For uncompensated quartz crystal oscillatores and nominal update 354 * intervals less than 1024 s, operation should be in phase-lock mode 355 * (STA_FLL = 0), where the loop is disciplined to phase. For update 356 * intervals greater than thiss, operation should be in frequency-lock 357 * mode (STA_FLL = 1), where the loop is disciplined to frequency. 358 * 359 * Note: splclock() is in effect. 360 */ 361void 362hardupdate(offset) 363 long offset; 364{ 365 long ltemp, mtemp; 366 367 if (!(time_status & STA_PLL) && !(time_status & STA_PPSTIME)) 368 return; 369 ltemp = offset; 370#ifdef PPS_SYNC 371 if (time_status & STA_PPSTIME && time_status & STA_PPSSIGNAL) 372 ltemp = pps_offset; 373#endif /* PPS_SYNC */ 374 375 /* 376 * Scale the phase adjustment and clamp to the operating range. 377 */ 378 if (ltemp > MAXPHASE) 379 time_offset = MAXPHASE << SHIFT_UPDATE; 380 else if (ltemp < -MAXPHASE) 381 time_offset = -(MAXPHASE << SHIFT_UPDATE); 382 else 383 time_offset = ltemp << SHIFT_UPDATE; 384 385 /* 386 * Select whether the frequency is to be controlled and in which 387 * mode (PLL or FLL). Clamp to the operating range. Ugly 388 * multiply/divide should be replaced someday. 389 */ 390 if (time_status & STA_FREQHOLD || time_reftime == 0) 391 time_reftime = time.tv_sec; 392 mtemp = time.tv_sec - time_reftime; 393 time_reftime = time.tv_sec; 394 if (time_status & STA_FLL) { 395 if (mtemp >= MINSEC) { 396 ltemp = ((time_offset / mtemp) << (SHIFT_USEC - 397 SHIFT_UPDATE)); 398 if (ltemp < 0) 399 time_freq -= -ltemp >> SHIFT_KH; 400 else 401 time_freq += ltemp >> SHIFT_KH; 402 } 403 } else { 404 if (mtemp < MAXSEC) { 405 ltemp *= mtemp; 406 if (ltemp < 0) 407 time_freq -= -ltemp >> (time_constant + 408 time_constant + SHIFT_KF - 409 SHIFT_USEC); 410 else 411 time_freq += ltemp >> (time_constant + 412 time_constant + SHIFT_KF - 413 SHIFT_USEC); 414 } 415 } 416 if (time_freq > time_tolerance) 417 time_freq = time_tolerance; 418 else if (time_freq < -time_tolerance) 419 time_freq = -time_tolerance; 420} 421 422 423 424/* 425 * Initialize clock frequencies and start both clocks running. 426 */ 427/* ARGSUSED*/ 428static void 429initclocks(dummy) 430 void *dummy; 431{ 432 register int i; 433 434 /* 435 * Set divisors to 1 (normal case) and let the machine-specific 436 * code do its bit. 437 */ 438 psdiv = pscnt = 1; 439 cpu_initclocks(); 440 441 /* 442 * Compute profhz/stathz, and fix profhz if needed. 443 */ 444 i = stathz ? stathz : hz; 445 if (profhz == 0) 446 profhz = i; 447 psratio = profhz / i; 448} 449 450/* 451 * The real-time timer, interrupting hz times per second. 452 */ 453void 454hardclock(frame) 455 register struct clockframe *frame; 456{ 457 register struct proc *p; 458 459 p = curproc; 460 if (p) { 461 register struct pstats *pstats; 462 463 /* 464 * Run current process's virtual and profile time, as needed. 465 */ 466 pstats = p->p_stats; 467 if (CLKF_USERMODE(frame) && 468 timerisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value) && 469 itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL], tick) == 0) 470 psignal(p, SIGVTALRM); 471 if (timerisset(&pstats->p_timer[ITIMER_PROF].it_value) && 472 itimerdecr(&pstats->p_timer[ITIMER_PROF], tick) == 0) 473 psignal(p, SIGPROF); 474 } 475 476 /* 477 * If no separate statistics clock is available, run it from here. 478 */ 479 if (stathz == 0) 480 statclock(frame); 481 482 /* 483 * Increment the time-of-day. 484 */ 485 ticks++; 486 { 487 int time_update; 488 struct timeval newtime = time; 489 long ltemp; 490 491 if (timedelta == 0) { 492 time_update = CPU_THISTICKLEN(tick); 493 } else { 494 time_update = CPU_THISTICKLEN(tick) + tickdelta; 495 timedelta -= tickdelta; 496 } 497 BUMPTIME(&mono_time, time_update); 498 499 /* 500 * Compute the phase adjustment. If the low-order bits 501 * (time_phase) of the update overflow, bump the high-order bits 502 * (time_update). 503 */ 504 time_phase += time_adj; 505 if (time_phase <= -FINEUSEC) { 506 ltemp = -time_phase >> SHIFT_SCALE; 507 time_phase += ltemp << SHIFT_SCALE; 508 time_update -= ltemp; 509 } 510 else if (time_phase >= FINEUSEC) { 511 ltemp = time_phase >> SHIFT_SCALE; 512 time_phase -= ltemp << SHIFT_SCALE; 513 time_update += ltemp; 514 } 515 516 newtime.tv_usec += time_update; 517 /* 518 * On rollover of the second the phase adjustment to be used for 519 * the next second is calculated. Also, the maximum error is 520 * increased by the tolerance. If the PPS frequency discipline 521 * code is present, the phase is increased to compensate for the 522 * CPU clock oscillator frequency error. 523 * 524 * On a 32-bit machine and given parameters in the timex.h 525 * header file, the maximum phase adjustment is +-512 ms and 526 * maximum frequency offset is a tad less than) +-512 ppm. On a 527 * 64-bit machine, you shouldn't need to ask. 528 */ 529 if (newtime.tv_usec >= 1000000) { 530 newtime.tv_usec -= 1000000; 531 newtime.tv_sec++; 532 time_maxerror += time_tolerance >> SHIFT_USEC; 533 534 /* 535 * Compute the phase adjustment for the next second. In 536 * PLL mode, the offset is reduced by a fixed factor 537 * times the time constant. In FLL mode the offset is 538 * used directly. In either mode, the maximum phase 539 * adjustment for each second is clamped so as to spread 540 * the adjustment over not more than the number of 541 * seconds between updates. 542 */ 543 if (time_offset < 0) { 544 ltemp = -time_offset; 545 if (!(time_status & STA_FLL)) 546 ltemp >>= SHIFT_KG + time_constant; 547 if (ltemp > (MAXPHASE / MINSEC) << SHIFT_UPDATE) 548 ltemp = (MAXPHASE / MINSEC) << 549 SHIFT_UPDATE; 550 time_offset += ltemp; 551 time_adj = -ltemp << (SHIFT_SCALE - SHIFT_HZ - 552 SHIFT_UPDATE); 553 } else { 554 ltemp = time_offset; 555 if (!(time_status & STA_FLL)) 556 ltemp >>= SHIFT_KG + time_constant; 557 if (ltemp > (MAXPHASE / MINSEC) << SHIFT_UPDATE) 558 ltemp = (MAXPHASE / MINSEC) << 559 SHIFT_UPDATE; 560 time_offset -= ltemp; 561 time_adj = ltemp << (SHIFT_SCALE - SHIFT_HZ - 562 SHIFT_UPDATE); 563 } 564 565 /* 566 * Compute the frequency estimate and additional phase 567 * adjustment due to frequency error for the next 568 * second. When the PPS signal is engaged, gnaw on the 569 * watchdog counter and update the frequency computed by 570 * the pll and the PPS signal. 571 */ 572#ifdef PPS_SYNC 573 pps_valid++; 574 if (pps_valid == PPS_VALID) { 575 pps_jitter = MAXTIME; 576 pps_stabil = MAXFREQ; 577 time_status &= ~(STA_PPSSIGNAL | STA_PPSJITTER | 578 STA_PPSWANDER | STA_PPSERROR); 579 } 580 ltemp = time_freq + pps_freq; 581#else 582 ltemp = time_freq; 583#endif /* PPS_SYNC */ 584 if (ltemp < 0) 585 time_adj -= -ltemp >> 586 (SHIFT_USEC + SHIFT_HZ - SHIFT_SCALE); 587 else 588 time_adj += ltemp >> 589 (SHIFT_USEC + SHIFT_HZ - SHIFT_SCALE); 590 591#if SHIFT_HZ == 7 592 /* 593 * When the CPU clock oscillator frequency is not a 594 * power of two in Hz, the SHIFT_HZ is only an 595 * approximate scale factor. In the SunOS kernel, this 596 * results in a PLL gain factor of 1/1.28 = 0.78 what it 597 * should be. In the following code the overall gain is 598 * increased by a factor of 1.25, which results in a 599 * residual error less than 3 percent. 600 */ 601 /* Same thing applies for FreeBSD --GAW */ 602 if (hz == 100) { 603 if (time_adj < 0) 604 time_adj -= -time_adj >> 2; 605 else 606 time_adj += time_adj >> 2; 607 } 608#endif /* SHIFT_HZ */ 609 610 /* XXX - this is really bogus, but can't be fixed until 611 xntpd's idea of the system clock is fixed to know how 612 the user wants leap seconds handled; in the mean time, 613 we assume that users of NTP are running without proper 614 leap second support (this is now the default anyway) */ 615 /* 616 * Leap second processing. If in leap-insert state at 617 * the end of the day, the system clock is set back one 618 * second; if in leap-delete state, the system clock is 619 * set ahead one second. The microtime() routine or 620 * external clock driver will insure that reported time 621 * is always monotonic. The ugly divides should be 622 * replaced. 623 */ 624 switch (time_state) { 625 626 case TIME_OK: 627 if (time_status & STA_INS) 628 time_state = TIME_INS; 629 else if (time_status & STA_DEL) 630 time_state = TIME_DEL; 631 break; 632 633 case TIME_INS: 634 if (newtime.tv_sec % 86400 == 0) { 635 newtime.tv_sec--; 636 time_state = TIME_OOP; 637 } 638 break; 639 640 case TIME_DEL: 641 if ((newtime.tv_sec + 1) % 86400 == 0) { 642 newtime.tv_sec++; 643 time_state = TIME_WAIT; 644 } 645 break; 646 647 case TIME_OOP: 648 time_state = TIME_WAIT; 649 break; 650 651 case TIME_WAIT: 652 if (!(time_status & (STA_INS | STA_DEL))) 653 time_state = TIME_OK; 654 } 655 } 656 CPU_CLOCKUPDATE(&time, &newtime); 657 } 658 659 /* 660 * Process callouts at a very low cpu priority, so we don't keep the 661 * relatively high clock interrupt priority any longer than necessary. 662 */ 663 if (TAILQ_FIRST(&callwheel[ticks & callwheelmask]) != NULL) { 664 if (CLKF_BASEPRI(frame)) { 665 /* 666 * Save the overhead of a software interrupt; 667 * it will happen as soon as we return, so do it now. 668 */ 669 (void)splsoftclock(); 670 softclock(); 671 } else 672 setsoftclock(); 673 } else if (softticks + 1 == ticks) { 674 ++softticks; 675 } 676} 677 678/* 679 * The callout mechanism is based on the work of Adam M. Costello and 680 * George Varghese, published in a technical report entitled "Redesigning 681 * the BSD Callout and Timer Facilities" and modified slightly for inclusion 682 * in FreeBSD by Justin T. Gibbs. The original work on the data structures 683 * used in this implementation was published by G.Varghese and A. Lauck in 684 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for 685 * the Efficient Implementation of a Timer Facility" in the Proceedings of 686 * the 11th ACM Annual Symposium on Operating Systems Principles, 687 * Austin, Texas Nov 1987. 688 */ 689/* 690 * Software (low priority) clock interrupt. 691 * Run periodic events from timeout queue. 692 */ 693/*ARGSUSED*/ 694void 695softclock() 696{ 697 register struct callout *c; 698 register struct callout_tailq *bucket; 699 register int s; 700 register int curticks; 701 register int steps; /* 702 * Number of steps taken since 703 * we last allowed interrupts. 704 */ 705 706 #ifndef MAX_SOFTCLOCK_STEPS 707 #define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */ 708 #endif /* MAX_SOFTCLOCK_STEPS */ 709 710 steps = 0; 711 s = splhigh(); 712 while (softticks != ticks) { 713 softticks++; 714 /* 715 * softticks may be modified by hard clock, so cache 716 * it while we work on a given bucket. 717 */ 718 curticks = softticks; 719 bucket = &callwheel[curticks & callwheelmask]; 720 c = TAILQ_FIRST(bucket); 721 while (c) { 722 if (c->c_time != curticks) { 723 c = TAILQ_NEXT(c, c_links.tqe); 724 ++steps; 725 if (steps >= MAX_SOFTCLOCK_STEPS) { 726 nextsoftcheck = c; 727 /* Give interrupts a chance. */ 728 splx(s); 729 s = splhigh(); 730 c = nextsoftcheck; 731 steps = 0; 732 } 733 } else { 734 void (*c_func)(void *); 735 void *c_arg; 736 737 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); 738 TAILQ_REMOVE(bucket, c, c_links.tqe); 739 c_func = c->c_func; 740 c_arg = c->c_arg; 741 c->c_func = NULL; 742 SLIST_INSERT_HEAD(&callfree, c, c_links.sle); 743 splx(s); 744 c_func(c_arg); 745 s = splhigh(); 746 steps = 0; 747 c = nextsoftcheck; 748 } 749 } 750 } 751 nextsoftcheck = NULL; 752 splx(s); 753} 754 755/* 756 * timeout -- 757 * Execute a function after a specified length of time. 758 * 759 * untimeout -- 760 * Cancel previous timeout function call. 761 * 762 * callout_handle_init -- 763 * Initialize a handle so that using it with untimeout is benign. 764 * 765 * See AT&T BCI Driver Reference Manual for specification. This 766 * implementation differs from that one in that although an 767 * identification value is returned from timeout, the original 768 * arguments to timeout as well as the identifier are used to 769 * identify entries for untimeout. 770 */ 771struct callout_handle 772timeout(ftn, arg, to_ticks) 773 timeout_t ftn; 774 void *arg; 775 register int to_ticks; 776{ 777 int s; 778 struct callout *new; 779 struct callout_handle handle; 780 781 if (to_ticks <= 0) 782 to_ticks = 1; 783 784 /* Lock out the clock. */ 785 s = splhigh(); 786 787 /* Fill in the next free callout structure. */ 788 new = SLIST_FIRST(&callfree); 789 if (new == NULL) 790 /* XXX Attempt to malloc first */ 791 panic("timeout table full"); 792 793 SLIST_REMOVE_HEAD(&callfree, c_links.sle); 794 new->c_arg = arg; 795 new->c_func = ftn; 796 new->c_time = ticks + to_ticks; 797 TAILQ_INSERT_TAIL(&callwheel[new->c_time & callwheelmask], 798 new, c_links.tqe); 799 800 splx(s); 801 handle.callout = new; 802 return (handle); 803} 804 805void 806untimeout(ftn, arg, handle) 807 timeout_t ftn; 808 void *arg; 809 struct callout_handle handle; 810{ 811 register int s; 812 813 /* 814 * Check for a handle that was initialized 815 * by callout_handle_init, but never used 816 * for a real timeout. 817 */ 818 if (handle.callout == NULL) 819 return; 820 821 s = splhigh(); 822 if ((handle.callout->c_func == ftn) 823 && (handle.callout->c_arg == arg)) { 824 if (nextsoftcheck == handle.callout) { 825 nextsoftcheck = TAILQ_NEXT(handle.callout, c_links.tqe); 826 } 827 TAILQ_REMOVE(&callwheel[handle.callout->c_time & callwheelmask], 828 handle.callout, c_links.tqe); 829 handle.callout->c_func = NULL; 830 SLIST_INSERT_HEAD(&callfree, handle.callout, c_links.sle); 831 } 832 splx(s); 833} 834 835void 836callout_handle_init(struct callout_handle *handle) 837{ 838 handle->callout = NULL; 839} 840 841void 842gettime(struct timeval *tvp) 843{ 844 int s; 845 846 s = splclock(); 847 /* XXX should use microtime() iff tv_usec is used. */ 848 *tvp = time; 849 splx(s); 850} 851 852/* 853 * Compute number of hz until specified time. Used to 854 * compute third argument to timeout() from an absolute time. 855 */ 856int 857hzto(tv) 858 struct timeval *tv; 859{ 860 register unsigned long ticks; 861 register long sec, usec; 862 int s; 863 864 /* 865 * If the number of usecs in the whole seconds part of the time 866 * difference fits in a long, then the total number of usecs will 867 * fit in an unsigned long. Compute the total and convert it to 868 * ticks, rounding up and adding 1 to allow for the current tick 869 * to expire. Rounding also depends on unsigned long arithmetic 870 * to avoid overflow. 871 * 872 * Otherwise, if the number of ticks in the whole seconds part of 873 * the time difference fits in a long, then convert the parts to 874 * ticks separately and add, using similar rounding methods and 875 * overflow avoidance. This method would work in the previous 876 * case but it is slightly slower and assumes that hz is integral. 877 * 878 * Otherwise, round the time difference down to the maximum 879 * representable value. 880 * 881 * If ints have 32 bits, then the maximum value for any timeout in 882 * 10ms ticks is 248 days. 883 */ 884 s = splclock(); 885 sec = tv->tv_sec - time.tv_sec; 886 usec = tv->tv_usec - time.tv_usec; 887 splx(s); 888 if (usec < 0) { 889 sec--; 890 usec += 1000000; 891 } 892 if (sec < 0) { 893#ifdef DIAGNOSTIC 894 printf("hzto: negative time difference %ld sec %ld usec\n", 895 sec, usec); 896#endif 897 ticks = 1; 898 } else if (sec <= LONG_MAX / 1000000) 899 ticks = (sec * 1000000 + (unsigned long)usec + (tick - 1)) 900 / tick + 1; 901 else if (sec <= LONG_MAX / hz) 902 ticks = sec * hz 903 + ((unsigned long)usec + (tick - 1)) / tick + 1; 904 else 905 ticks = LONG_MAX; 906 if (ticks > INT_MAX) 907 ticks = INT_MAX; 908 return (ticks); 909} 910 911/* 912 * Start profiling on a process. 913 * 914 * Kernel profiling passes proc0 which never exits and hence 915 * keeps the profile clock running constantly. 916 */ 917void 918startprofclock(p) 919 register struct proc *p; 920{ 921 int s; 922 923 if ((p->p_flag & P_PROFIL) == 0) { 924 p->p_flag |= P_PROFIL; 925 if (++profprocs == 1 && stathz != 0) { 926 s = splstatclock(); 927 psdiv = pscnt = psratio; 928 setstatclockrate(profhz); 929 splx(s); 930 } 931 } 932} 933 934/* 935 * Stop profiling on a process. 936 */ 937void 938stopprofclock(p) 939 register struct proc *p; 940{ 941 int s; 942 943 if (p->p_flag & P_PROFIL) { 944 p->p_flag &= ~P_PROFIL; 945 if (--profprocs == 0 && stathz != 0) { 946 s = splstatclock(); 947 psdiv = pscnt = 1; 948 setstatclockrate(stathz); 949 splx(s); 950 } 951 } 952} 953 954/* 955 * Statistics clock. Grab profile sample, and if divider reaches 0, 956 * do process and kernel statistics. 957 */ 958void 959statclock(frame) 960 register struct clockframe *frame; 961{ 962#ifdef GPROF 963 register struct gmonparam *g; 964#endif 965 register struct proc *p; 966 register int i; 967 struct pstats *pstats; 968 long rss; 969 struct rusage *ru; 970 struct vmspace *vm; 971 972 if (CLKF_USERMODE(frame)) { 973 p = curproc; 974 if (p->p_flag & P_PROFIL) 975 addupc_intr(p, CLKF_PC(frame), 1); 976 if (--pscnt > 0) 977 return; 978 /* 979 * Came from user mode; CPU was in user state. 980 * If this process is being profiled record the tick. 981 */ 982 p->p_uticks++; 983 if (p->p_nice > NZERO) 984 cp_time[CP_NICE]++; 985 else 986 cp_time[CP_USER]++; 987 } else { 988#ifdef GPROF 989 /* 990 * Kernel statistics are just like addupc_intr, only easier. 991 */ 992 g = &_gmonparam; 993 if (g->state == GMON_PROF_ON) { 994 i = CLKF_PC(frame) - g->lowpc; 995 if (i < g->textsize) { 996 i /= HISTFRACTION * sizeof(*g->kcount); 997 g->kcount[i]++; 998 } 999 } 1000#endif 1001 if (--pscnt > 0) 1002 return; 1003 /* 1004 * Came from kernel mode, so we were: 1005 * - handling an interrupt, 1006 * - doing syscall or trap work on behalf of the current 1007 * user process, or 1008 * - spinning in the idle loop. 1009 * Whichever it is, charge the time as appropriate. 1010 * Note that we charge interrupts to the current process, 1011 * regardless of whether they are ``for'' that process, 1012 * so that we know how much of its real time was spent 1013 * in ``non-process'' (i.e., interrupt) work. 1014 */ 1015 p = curproc; 1016 if (CLKF_INTR(frame)) { 1017 if (p != NULL) 1018 p->p_iticks++; 1019 cp_time[CP_INTR]++; 1020 } else if (p != NULL && !(p->p_flag & P_IDLEPROC)) { 1021 p->p_sticks++; 1022 cp_time[CP_SYS]++; 1023 } else 1024 cp_time[CP_IDLE]++; 1025 } 1026 pscnt = psdiv; 1027 1028 /* 1029 * We maintain statistics shown by user-level statistics 1030 * programs: the amount of time in each cpu state, and 1031 * the amount of time each of DK_NDRIVE ``drives'' is busy. 1032 * 1033 * XXX should either run linked list of drives, or (better) 1034 * grab timestamps in the start & done code. 1035 */ 1036 for (i = 0; i < DK_NDRIVE; i++) 1037 if (dk_busy & (1 << i)) 1038 dk_time[i]++; 1039 1040 /* 1041 * We adjust the priority of the current process. The priority of 1042 * a process gets worse as it accumulates CPU time. The cpu usage 1043 * estimator (p_estcpu) is increased here. The formula for computing 1044 * priorities (in kern_synch.c) will compute a different value each 1045 * time p_estcpu increases by 4. The cpu usage estimator ramps up 1046 * quite quickly when the process is running (linearly), and decays 1047 * away exponentially, at a rate which is proportionally slower when 1048 * the system is busy. The basic principal is that the system will 1049 * 90% forget that the process used a lot of CPU time in 5 * loadav 1050 * seconds. This causes the system to favor processes which haven't 1051 * run much recently, and to round-robin among other processes. 1052 */ 1053 if (p != NULL) { 1054 p->p_cpticks++; 1055 if (++p->p_estcpu == 0) 1056 p->p_estcpu--; 1057 if ((p->p_estcpu & 3) == 0) { 1058 resetpriority(p); 1059 if (p->p_priority >= PUSER) 1060 p->p_priority = p->p_usrpri; 1061 } 1062 1063 /* Update resource usage integrals and maximums. */ 1064 if ((pstats = p->p_stats) != NULL && 1065 (ru = &pstats->p_ru) != NULL && 1066 (vm = p->p_vmspace) != NULL) { 1067 ru->ru_ixrss += vm->vm_tsize * PAGE_SIZE / 1024; 1068 ru->ru_idrss += vm->vm_dsize * PAGE_SIZE / 1024; 1069 ru->ru_isrss += vm->vm_ssize * PAGE_SIZE / 1024; 1070 rss = vm->vm_pmap.pm_stats.resident_count * 1071 PAGE_SIZE / 1024; 1072 if (ru->ru_maxrss < rss) 1073 ru->ru_maxrss = rss; 1074 } 1075 } 1076} 1077 1078/* 1079 * Return information about system clocks. 1080 */ 1081static int 1082sysctl_kern_clockrate SYSCTL_HANDLER_ARGS 1083{ 1084 struct clockinfo clkinfo; 1085 /* 1086 * Construct clockinfo structure. 1087 */ 1088 clkinfo.hz = hz; 1089 clkinfo.tick = tick; 1090 clkinfo.tickadj = tickadj; 1091 clkinfo.profhz = profhz; 1092 clkinfo.stathz = stathz ? stathz : hz; 1093 return (sysctl_handle_opaque(oidp, &clkinfo, sizeof clkinfo, req)); 1094} 1095 1096SYSCTL_PROC(_kern, KERN_CLOCKRATE, clockrate, CTLTYPE_STRUCT|CTLFLAG_RD, 1097 0, 0, sysctl_kern_clockrate, "S,clockinfo",""); 1098 1099#ifdef PPS_SYNC 1100/* 1101 * hardpps() - discipline CPU clock oscillator to external PPS signal 1102 * 1103 * This routine is called at each PPS interrupt in order to discipline 1104 * the CPU clock oscillator to the PPS signal. It measures the PPS phase 1105 * and leaves it in a handy spot for the hardclock() routine. It 1106 * integrates successive PPS phase differences and calculates the 1107 * frequency offset. This is used in hardclock() to discipline the CPU 1108 * clock oscillator so that intrinsic frequency error is cancelled out. 1109 * The code requires the caller to capture the time and hardware counter 1110 * value at the on-time PPS signal transition. 1111 * 1112 * Note that, on some Unix systems, this routine runs at an interrupt 1113 * priority level higher than the timer interrupt routine hardclock(). 1114 * Therefore, the variables used are distinct from the hardclock() 1115 * variables, except for certain exceptions: The PPS frequency pps_freq 1116 * and phase pps_offset variables are determined by this routine and 1117 * updated atomically. The time_tolerance variable can be considered a 1118 * constant, since it is infrequently changed, and then only when the 1119 * PPS signal is disabled. The watchdog counter pps_valid is updated 1120 * once per second by hardclock() and is atomically cleared in this 1121 * routine. 1122 */ 1123void 1124hardpps(tvp, usec) 1125 struct timeval *tvp; /* time at PPS */ 1126 long usec; /* hardware counter at PPS */ 1127{ 1128 long u_usec, v_usec, bigtick; 1129 long cal_sec, cal_usec; 1130 1131 /* 1132 * An occasional glitch can be produced when the PPS interrupt 1133 * occurs in the hardclock() routine before the time variable is 1134 * updated. Here the offset is discarded when the difference 1135 * between it and the last one is greater than tick/2, but not 1136 * if the interval since the first discard exceeds 30 s. 1137 */ 1138 time_status |= STA_PPSSIGNAL; 1139 time_status &= ~(STA_PPSJITTER | STA_PPSWANDER | STA_PPSERROR); 1140 pps_valid = 0; 1141 u_usec = -tvp->tv_usec; 1142 if (u_usec < -500000) 1143 u_usec += 1000000; 1144 v_usec = pps_offset - u_usec; 1145 if (v_usec < 0) 1146 v_usec = -v_usec; 1147 if (v_usec > (tick >> 1)) { 1148 if (pps_glitch > MAXGLITCH) { 1149 pps_glitch = 0; 1150 pps_tf[2] = u_usec; 1151 pps_tf[1] = u_usec; 1152 } else { 1153 pps_glitch++; 1154 u_usec = pps_offset; 1155 } 1156 } else 1157 pps_glitch = 0; 1158 1159 /* 1160 * A three-stage median filter is used to help deglitch the pps 1161 * time. The median sample becomes the time offset estimate; the 1162 * difference between the other two samples becomes the time 1163 * dispersion (jitter) estimate. 1164 */ 1165 pps_tf[2] = pps_tf[1]; 1166 pps_tf[1] = pps_tf[0]; 1167 pps_tf[0] = u_usec; 1168 if (pps_tf[0] > pps_tf[1]) { 1169 if (pps_tf[1] > pps_tf[2]) { 1170 pps_offset = pps_tf[1]; /* 0 1 2 */ 1171 v_usec = pps_tf[0] - pps_tf[2]; 1172 } else if (pps_tf[2] > pps_tf[0]) { 1173 pps_offset = pps_tf[0]; /* 2 0 1 */ 1174 v_usec = pps_tf[2] - pps_tf[1]; 1175 } else { 1176 pps_offset = pps_tf[2]; /* 0 2 1 */ 1177 v_usec = pps_tf[0] - pps_tf[1]; 1178 } 1179 } else { 1180 if (pps_tf[1] < pps_tf[2]) { 1181 pps_offset = pps_tf[1]; /* 2 1 0 */ 1182 v_usec = pps_tf[2] - pps_tf[0]; 1183 } else if (pps_tf[2] < pps_tf[0]) { 1184 pps_offset = pps_tf[0]; /* 1 0 2 */ 1185 v_usec = pps_tf[1] - pps_tf[2]; 1186 } else { 1187 pps_offset = pps_tf[2]; /* 1 2 0 */ 1188 v_usec = pps_tf[1] - pps_tf[0]; 1189 } 1190 } 1191 if (v_usec > MAXTIME) 1192 pps_jitcnt++; 1193 v_usec = (v_usec << PPS_AVG) - pps_jitter; 1194 if (v_usec < 0) 1195 pps_jitter -= -v_usec >> PPS_AVG; 1196 else 1197 pps_jitter += v_usec >> PPS_AVG; 1198 if (pps_jitter > (MAXTIME >> 1)) 1199 time_status |= STA_PPSJITTER; 1200 1201 /* 1202 * During the calibration interval adjust the starting time when 1203 * the tick overflows. At the end of the interval compute the 1204 * duration of the interval and the difference of the hardware 1205 * counters at the beginning and end of the interval. This code 1206 * is deliciously complicated by the fact valid differences may 1207 * exceed the value of tick when using long calibration 1208 * intervals and small ticks. Note that the counter can be 1209 * greater than tick if caught at just the wrong instant, but 1210 * the values returned and used here are correct. 1211 */ 1212 bigtick = (long)tick << SHIFT_USEC; 1213 pps_usec -= pps_freq; 1214 if (pps_usec >= bigtick) 1215 pps_usec -= bigtick; 1216 if (pps_usec < 0) 1217 pps_usec += bigtick; 1218 pps_time.tv_sec++; 1219 pps_count++; 1220 if (pps_count < (1 << pps_shift)) 1221 return; 1222 pps_count = 0; 1223 pps_calcnt++; 1224 u_usec = usec << SHIFT_USEC; 1225 v_usec = pps_usec - u_usec; 1226 if (v_usec >= bigtick >> 1) 1227 v_usec -= bigtick; 1228 if (v_usec < -(bigtick >> 1)) 1229 v_usec += bigtick; 1230 if (v_usec < 0) 1231 v_usec = -(-v_usec >> pps_shift); 1232 else 1233 v_usec = v_usec >> pps_shift; 1234 pps_usec = u_usec; 1235 cal_sec = tvp->tv_sec; 1236 cal_usec = tvp->tv_usec; 1237 cal_sec -= pps_time.tv_sec; 1238 cal_usec -= pps_time.tv_usec; 1239 if (cal_usec < 0) { 1240 cal_usec += 1000000; 1241 cal_sec--; 1242 } 1243 pps_time = *tvp; 1244 1245 /* 1246 * Check for lost interrupts, noise, excessive jitter and 1247 * excessive frequency error. The number of timer ticks during 1248 * the interval may vary +-1 tick. Add to this a margin of one 1249 * tick for the PPS signal jitter and maximum frequency 1250 * deviation. If the limits are exceeded, the calibration 1251 * interval is reset to the minimum and we start over. 1252 */ 1253 u_usec = (long)tick << 1; 1254 if (!((cal_sec == -1 && cal_usec > (1000000 - u_usec)) 1255 || (cal_sec == 0 && cal_usec < u_usec)) 1256 || v_usec > time_tolerance || v_usec < -time_tolerance) { 1257 pps_errcnt++; 1258 pps_shift = PPS_SHIFT; 1259 pps_intcnt = 0; 1260 time_status |= STA_PPSERROR; 1261 return; 1262 } 1263 1264 /* 1265 * A three-stage median filter is used to help deglitch the pps 1266 * frequency. The median sample becomes the frequency offset 1267 * estimate; the difference between the other two samples 1268 * becomes the frequency dispersion (stability) estimate. 1269 */ 1270 pps_ff[2] = pps_ff[1]; 1271 pps_ff[1] = pps_ff[0]; 1272 pps_ff[0] = v_usec; 1273 if (pps_ff[0] > pps_ff[1]) { 1274 if (pps_ff[1] > pps_ff[2]) { 1275 u_usec = pps_ff[1]; /* 0 1 2 */ 1276 v_usec = pps_ff[0] - pps_ff[2]; 1277 } else if (pps_ff[2] > pps_ff[0]) { 1278 u_usec = pps_ff[0]; /* 2 0 1 */ 1279 v_usec = pps_ff[2] - pps_ff[1]; 1280 } else { 1281 u_usec = pps_ff[2]; /* 0 2 1 */ 1282 v_usec = pps_ff[0] - pps_ff[1]; 1283 } 1284 } else { 1285 if (pps_ff[1] < pps_ff[2]) { 1286 u_usec = pps_ff[1]; /* 2 1 0 */ 1287 v_usec = pps_ff[2] - pps_ff[0]; 1288 } else if (pps_ff[2] < pps_ff[0]) { 1289 u_usec = pps_ff[0]; /* 1 0 2 */ 1290 v_usec = pps_ff[1] - pps_ff[2]; 1291 } else { 1292 u_usec = pps_ff[2]; /* 1 2 0 */ 1293 v_usec = pps_ff[1] - pps_ff[0]; 1294 } 1295 } 1296 1297 /* 1298 * Here the frequency dispersion (stability) is updated. If it 1299 * is less than one-fourth the maximum (MAXFREQ), the frequency 1300 * offset is updated as well, but clamped to the tolerance. It 1301 * will be processed later by the hardclock() routine. 1302 */ 1303 v_usec = (v_usec >> 1) - pps_stabil; 1304 if (v_usec < 0) 1305 pps_stabil -= -v_usec >> PPS_AVG; 1306 else 1307 pps_stabil += v_usec >> PPS_AVG; 1308 if (pps_stabil > MAXFREQ >> 2) { 1309 pps_stbcnt++; 1310 time_status |= STA_PPSWANDER; 1311 return; 1312 } 1313 if (time_status & STA_PPSFREQ) { 1314 if (u_usec < 0) { 1315 pps_freq -= -u_usec >> PPS_AVG; 1316 if (pps_freq < -time_tolerance) 1317 pps_freq = -time_tolerance; 1318 u_usec = -u_usec; 1319 } else { 1320 pps_freq += u_usec >> PPS_AVG; 1321 if (pps_freq > time_tolerance) 1322 pps_freq = time_tolerance; 1323 } 1324 } 1325 1326 /* 1327 * Here the calibration interval is adjusted. If the maximum 1328 * time difference is greater than tick / 4, reduce the interval 1329 * by half. If this is not the case for four consecutive 1330 * intervals, double the interval. 1331 */ 1332 if (u_usec << pps_shift > bigtick >> 2) { 1333 pps_intcnt = 0; 1334 if (pps_shift > PPS_SHIFT) 1335 pps_shift--; 1336 } else if (pps_intcnt >= 4) { 1337 pps_intcnt = 0; 1338 if (pps_shift < PPS_SHIFTMAX) 1339 pps_shift++; 1340 } else 1341 pps_intcnt++; 1342} 1343#endif /* PPS_SYNC */ 1344