FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_clock.c
1 /* $NetBSD: kern_clock.c,v 1.94 2005/03/02 11:05:34 mycroft Exp $ */
2
3 /*-
4 * Copyright (c) 2000, 2004 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
9 * NASA Ames Research Center.
10 * This code is derived from software contributed to The NetBSD Foundation
11 * by Charles M. Hannum.
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. All advertising materials mentioning features or use of this software
22 * must display the following acknowledgement:
23 * This product includes software developed by the NetBSD
24 * Foundation, Inc. and its contributors.
25 * 4. Neither the name of The NetBSD Foundation nor the names of its
26 * contributors may be used to endorse or promote products derived
27 * from this software without specific prior written permission.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
30 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
31 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
32 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
33 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
34 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
35 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
36 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
37 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
38 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
39 * POSSIBILITY OF SUCH DAMAGE.
40 */
41
42 /*-
43 * Copyright (c) 1982, 1986, 1991, 1993
44 * The Regents of the University of California. All rights reserved.
45 * (c) UNIX System Laboratories, Inc.
46 * All or some portions of this file are derived from material licensed
47 * to the University of California by American Telephone and Telegraph
48 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
49 * the permission of UNIX System Laboratories, Inc.
50 *
51 * Redistribution and use in source and binary forms, with or without
52 * modification, are permitted provided that the following conditions
53 * are met:
54 * 1. Redistributions of source code must retain the above copyright
55 * notice, this list of conditions and the following disclaimer.
56 * 2. Redistributions in binary form must reproduce the above copyright
57 * notice, this list of conditions and the following disclaimer in the
58 * documentation and/or other materials provided with the distribution.
59 * 3. Neither the name of the University nor the names of its contributors
60 * may be used to endorse or promote products derived from this software
61 * without specific prior written permission.
62 *
63 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
64 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
65 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
66 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
67 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
68 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
69 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
70 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
71 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
72 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
73 * SUCH DAMAGE.
74 *
75 * @(#)kern_clock.c 8.5 (Berkeley) 1/21/94
76 */
77
78 #include <sys/cdefs.h>
79 __KERNEL_RCSID(0, "$NetBSD: kern_clock.c,v 1.94 2005/03/02 11:05:34 mycroft Exp $");
80
81 #include "opt_ntp.h"
82 #include "opt_multiprocessor.h"
83 #include "opt_perfctrs.h"
84
85 #include <sys/param.h>
86 #include <sys/systm.h>
87 #include <sys/callout.h>
88 #include <sys/kernel.h>
89 #include <sys/proc.h>
90 #include <sys/resourcevar.h>
91 #include <sys/signalvar.h>
92 #include <sys/sysctl.h>
93 #include <sys/timex.h>
94 #include <sys/sched.h>
95 #include <sys/time.h>
96
97 #include <machine/cpu.h>
98 #ifdef __HAVE_GENERIC_SOFT_INTERRUPTS
99 #include <machine/intr.h>
100 #endif
101
102 #ifdef GPROF
103 #include <sys/gmon.h>
104 #endif
105
106 /*
107 * Clock handling routines.
108 *
109 * This code is written to operate with two timers that run independently of
110 * each other. The main clock, running hz times per second, is used to keep
111 * track of real time. The second timer handles kernel and user profiling,
112 * and does resource use estimation. If the second timer is programmable,
113 * it is randomized to avoid aliasing between the two clocks. For example,
114 * the randomization prevents an adversary from always giving up the CPU
115 * just before its quantum expires. Otherwise, it would never accumulate
116 * CPU ticks. The mean frequency of the second timer is stathz.
117 *
118 * If no second timer exists, stathz will be zero; in this case we drive
119 * profiling and statistics off the main clock. This WILL NOT be accurate;
120 * do not do it unless absolutely necessary.
121 *
122 * The statistics clock may (or may not) be run at a higher rate while
123 * profiling. This profile clock runs at profhz. We require that profhz
124 * be an integral multiple of stathz.
125 *
126 * If the statistics clock is running fast, it must be divided by the ratio
127 * profhz/stathz for statistics. (For profiling, every tick counts.)
128 */
129
130 #ifdef NTP /* NTP phase-locked loop in kernel */
131 /*
132 * Phase/frequency-lock loop (PLL/FLL) definitions
133 *
134 * The following variables are read and set by the ntp_adjtime() system
135 * call.
136 *
137 * time_state shows the state of the system clock, with values defined
138 * in the timex.h header file.
139 *
140 * time_status shows the status of the system clock, with bits defined
141 * in the timex.h header file.
142 *
143 * time_offset is used by the PLL/FLL to adjust the system time in small
144 * increments.
145 *
146 * time_constant determines the bandwidth or "stiffness" of the PLL.
147 *
148 * time_tolerance determines maximum frequency error or tolerance of the
149 * CPU clock oscillator and is a property of the architecture; however,
150 * in principle it could change as result of the presence of external
151 * discipline signals, for instance.
152 *
153 * time_precision is usually equal to the kernel tick variable; however,
154 * in cases where a precision clock counter or external clock is
155 * available, the resolution can be much less than this and depend on
156 * whether the external clock is working or not.
157 *
158 * time_maxerror is initialized by a ntp_adjtime() call and increased by
159 * the kernel once each second to reflect the maximum error bound
160 * growth.
161 *
162 * time_esterror is set and read by the ntp_adjtime() call, but
163 * otherwise not used by the kernel.
164 */
165 int time_state = TIME_OK; /* clock state */
166 int time_status = STA_UNSYNC; /* clock status bits */
167 long time_offset = 0; /* time offset (us) */
168 long time_constant = 0; /* pll time constant */
169 long time_tolerance = MAXFREQ; /* frequency tolerance (scaled ppm) */
170 long time_precision = 1; /* clock precision (us) */
171 long time_maxerror = MAXPHASE; /* maximum error (us) */
172 long time_esterror = MAXPHASE; /* estimated error (us) */
173
174 /*
175 * The following variables establish the state of the PLL/FLL and the
176 * residual time and frequency offset of the local clock. The scale
177 * factors are defined in the timex.h header file.
178 *
179 * time_phase and time_freq are the phase increment and the frequency
180 * increment, respectively, of the kernel time variable.
181 *
182 * time_freq is set via ntp_adjtime() from a value stored in a file when
183 * the synchronization daemon is first started. Its value is retrieved
184 * via ntp_adjtime() and written to the file about once per hour by the
185 * daemon.
186 *
187 * time_adj is the adjustment added to the value of tick at each timer
188 * interrupt and is recomputed from time_phase and time_freq at each
189 * seconds rollover.
190 *
191 * time_reftime is the second's portion of the system time at the last
192 * call to ntp_adjtime(). It is used to adjust the time_freq variable
193 * and to increase the time_maxerror as the time since last update
194 * increases.
195 */
196 long time_phase = 0; /* phase offset (scaled us) */
197 long time_freq = 0; /* frequency offset (scaled ppm) */
198 long time_adj = 0; /* tick adjust (scaled 1 / hz) */
199 long time_reftime = 0; /* time at last adjustment (s) */
200
201 #ifdef PPS_SYNC
202 /*
203 * The following variables are used only if the kernel PPS discipline
204 * code is configured (PPS_SYNC). The scale factors are defined in the
205 * timex.h header file.
206 *
207 * pps_time contains the time at each calibration interval, as read by
208 * microtime(). pps_count counts the seconds of the calibration
209 * interval, the duration of which is nominally pps_shift in powers of
210 * two.
211 *
212 * pps_offset is the time offset produced by the time median filter
213 * pps_tf[], while pps_jitter is the dispersion (jitter) measured by
214 * this filter.
215 *
216 * pps_freq is the frequency offset produced by the frequency median
217 * filter pps_ff[], while pps_stabil is the dispersion (wander) measured
218 * by this filter.
219 *
220 * pps_usec is latched from a high resolution counter or external clock
221 * at pps_time. Here we want the hardware counter contents only, not the
222 * contents plus the time_tv.usec as usual.
223 *
224 * pps_valid counts the number of seconds since the last PPS update. It
225 * is used as a watchdog timer to disable the PPS discipline should the
226 * PPS signal be lost.
227 *
228 * pps_glitch counts the number of seconds since the beginning of an
229 * offset burst more than tick/2 from current nominal offset. It is used
230 * mainly to suppress error bursts due to priority conflicts between the
231 * PPS interrupt and timer interrupt.
232 *
233 * pps_intcnt counts the calibration intervals for use in the interval-
234 * adaptation algorithm. It's just too complicated for words.
235 *
236 * pps_kc_hardpps_source contains an arbitrary value that uniquely
237 * identifies the currently bound source of the PPS signal, or NULL
238 * if no source is bound.
239 *
240 * pps_kc_hardpps_mode indicates which transitions, if any, of the PPS
241 * signal should be reported.
242 */
243 struct timeval pps_time; /* kernel time at last interval */
244 long pps_tf[] = {0, 0, 0}; /* pps time offset median filter (us) */
245 long pps_offset = 0; /* pps time offset (us) */
246 long pps_jitter = MAXTIME; /* time dispersion (jitter) (us) */
247 long pps_ff[] = {0, 0, 0}; /* pps frequency offset median filter */
248 long pps_freq = 0; /* frequency offset (scaled ppm) */
249 long pps_stabil = MAXFREQ; /* frequency dispersion (scaled ppm) */
250 long pps_usec = 0; /* microsec counter at last interval */
251 long pps_valid = PPS_VALID; /* pps signal watchdog counter */
252 int pps_glitch = 0; /* pps signal glitch counter */
253 int pps_count = 0; /* calibration interval counter (s) */
254 int pps_shift = PPS_SHIFT; /* interval duration (s) (shift) */
255 int pps_intcnt = 0; /* intervals at current duration */
256 void *pps_kc_hardpps_source = NULL; /* current PPS supplier's identifier */
257 int pps_kc_hardpps_mode = 0; /* interesting edges of PPS signal */
258
259 /*
260 * PPS signal quality monitors
261 *
262 * pps_jitcnt counts the seconds that have been discarded because the
263 * jitter measured by the time median filter exceeds the limit MAXTIME
264 * (100 us).
265 *
266 * pps_calcnt counts the frequency calibration intervals, which are
267 * variable from 4 s to 256 s.
268 *
269 * pps_errcnt counts the calibration intervals which have been discarded
270 * because the wander exceeds the limit MAXFREQ (100 ppm) or where the
271 * calibration interval jitter exceeds two ticks.
272 *
273 * pps_stbcnt counts the calibration intervals that have been discarded
274 * because the frequency wander exceeds the limit MAXFREQ / 4 (25 us).
275 */
276 long pps_jitcnt = 0; /* jitter limit exceeded */
277 long pps_calcnt = 0; /* calibration intervals */
278 long pps_errcnt = 0; /* calibration errors */
279 long pps_stbcnt = 0; /* stability limit exceeded */
280 #endif /* PPS_SYNC */
281
282 #ifdef EXT_CLOCK
283 /*
284 * External clock definitions
285 *
286 * The following definitions and declarations are used only if an
287 * external clock is configured on the system.
288 */
289 #define CLOCK_INTERVAL 30 /* CPU clock update interval (s) */
290
291 /*
292 * The clock_count variable is set to CLOCK_INTERVAL at each PPS
293 * interrupt and decremented once each second.
294 */
295 int clock_count = 0; /* CPU clock counter */
296
297 #ifdef HIGHBALL
298 /*
299 * The clock_offset and clock_cpu variables are used by the HIGHBALL
300 * interface. The clock_offset variable defines the offset between
301 * system time and the HIGBALL counters. The clock_cpu variable contains
302 * the offset between the system clock and the HIGHBALL clock for use in
303 * disciplining the kernel time variable.
304 */
305 extern struct timeval clock_offset; /* Highball clock offset */
306 long clock_cpu = 0; /* CPU clock adjust */
307 #endif /* HIGHBALL */
308 #endif /* EXT_CLOCK */
309 #endif /* NTP */
310
311
312 /*
313 * Bump a timeval by a small number of usec's.
314 */
315 #define BUMPTIME(t, usec) { \
316 volatile struct timeval *tp = (t); \
317 long us; \
318 \
319 tp->tv_usec = us = tp->tv_usec + (usec); \
320 if (us >= 1000000) { \
321 tp->tv_usec = us - 1000000; \
322 tp->tv_sec++; \
323 } \
324 }
325
326 int stathz;
327 int profhz;
328 int profsrc;
329 int schedhz;
330 int profprocs;
331 int hardclock_ticks;
332 static int statscheddiv; /* stat => sched divider (used if schedhz == 0) */
333 static int psdiv; /* prof => stat divider */
334 int psratio; /* ratio: prof / stat */
335 int tickfix, tickfixinterval; /* used if tick not really integral */
336 #ifndef NTP
337 static int tickfixcnt; /* accumulated fractional error */
338 #else
339 int fixtick; /* used by NTP for same */
340 int shifthz;
341 #endif
342
343 /*
344 * We might want ldd to load the both words from time at once.
345 * To succeed we need to be quadword aligned.
346 * The sparc already does that, and that it has worked so far is a fluke.
347 */
348 volatile struct timeval time __attribute__((__aligned__(__alignof__(quad_t))));
349 volatile struct timeval mono_time;
350
351 void *softclock_si;
352
353 /*
354 * Initialize clock frequencies and start both clocks running.
355 */
356 void
357 initclocks(void)
358 {
359 int i;
360
361 #ifdef __HAVE_GENERIC_SOFT_INTERRUPTS
362 softclock_si = softintr_establish(IPL_SOFTCLOCK, softclock, NULL);
363 if (softclock_si == NULL)
364 panic("initclocks: unable to register softclock intr");
365 #endif
366
367 /*
368 * Set divisors to 1 (normal case) and let the machine-specific
369 * code do its bit.
370 */
371 psdiv = 1;
372 cpu_initclocks();
373
374 /*
375 * Compute profhz/stathz/rrticks, and fix profhz if needed.
376 */
377 i = stathz ? stathz : hz;
378 if (profhz == 0)
379 profhz = i;
380 psratio = profhz / i;
381 rrticks = hz / 10;
382 if (schedhz == 0) {
383 /* 16Hz is best */
384 statscheddiv = i / 16;
385 if (statscheddiv <= 0)
386 panic("statscheddiv");
387 }
388
389 #ifdef NTP
390 switch (hz) {
391 case 1:
392 shifthz = SHIFT_SCALE - 0;
393 break;
394 case 2:
395 shifthz = SHIFT_SCALE - 1;
396 break;
397 case 4:
398 shifthz = SHIFT_SCALE - 2;
399 break;
400 case 8:
401 shifthz = SHIFT_SCALE - 3;
402 break;
403 case 16:
404 shifthz = SHIFT_SCALE - 4;
405 break;
406 case 32:
407 shifthz = SHIFT_SCALE - 5;
408 break;
409 case 50:
410 case 60:
411 case 64:
412 shifthz = SHIFT_SCALE - 6;
413 break;
414 case 96:
415 case 100:
416 case 128:
417 shifthz = SHIFT_SCALE - 7;
418 break;
419 case 256:
420 shifthz = SHIFT_SCALE - 8;
421 break;
422 case 512:
423 shifthz = SHIFT_SCALE - 9;
424 break;
425 case 1000:
426 case 1024:
427 shifthz = SHIFT_SCALE - 10;
428 break;
429 case 1200:
430 case 2048:
431 shifthz = SHIFT_SCALE - 11;
432 break;
433 case 4096:
434 shifthz = SHIFT_SCALE - 12;
435 break;
436 case 8192:
437 shifthz = SHIFT_SCALE - 13;
438 break;
439 case 16384:
440 shifthz = SHIFT_SCALE - 14;
441 break;
442 case 32768:
443 shifthz = SHIFT_SCALE - 15;
444 break;
445 case 65536:
446 shifthz = SHIFT_SCALE - 16;
447 break;
448 default:
449 panic("weird hz");
450 }
451 if (fixtick == 0) {
452 /*
453 * Give MD code a chance to set this to a better
454 * value; but, if it doesn't, we should.
455 */
456 fixtick = (1000000 - (hz*tick));
457 }
458 #endif
459 }
460
461 /*
462 * The real-time timer, interrupting hz times per second.
463 */
464 void
465 hardclock(struct clockframe *frame)
466 {
467 struct lwp *l;
468 struct proc *p;
469 int delta;
470 extern int tickdelta;
471 extern long timedelta;
472 struct cpu_info *ci = curcpu();
473 struct ptimer *pt;
474 #ifdef NTP
475 int time_update;
476 int ltemp;
477 #endif
478
479 l = curlwp;
480 if (l) {
481 p = l->l_proc;
482 /*
483 * Run current process's virtual and profile time, as needed.
484 */
485 if (CLKF_USERMODE(frame) && p->p_timers &&
486 (pt = LIST_FIRST(&p->p_timers->pts_virtual)) != NULL)
487 if (itimerdecr(pt, tick) == 0)
488 itimerfire(pt);
489 if (p->p_timers &&
490 (pt = LIST_FIRST(&p->p_timers->pts_prof)) != NULL)
491 if (itimerdecr(pt, tick) == 0)
492 itimerfire(pt);
493 }
494
495 /*
496 * If no separate statistics clock is available, run it from here.
497 */
498 if (stathz == 0)
499 statclock(frame);
500 if ((--ci->ci_schedstate.spc_rrticks) <= 0)
501 roundrobin(ci);
502
503 #if defined(MULTIPROCESSOR)
504 /*
505 * If we are not the primary CPU, we're not allowed to do
506 * any more work.
507 */
508 if (CPU_IS_PRIMARY(ci) == 0)
509 return;
510 #endif
511
512 /*
513 * Increment the time-of-day. The increment is normally just
514 * ``tick''. If the machine is one which has a clock frequency
515 * such that ``hz'' would not divide the second evenly into
516 * milliseconds, a periodic adjustment must be applied. Finally,
517 * if we are still adjusting the time (see adjtime()),
518 * ``tickdelta'' may also be added in.
519 */
520 hardclock_ticks++;
521 delta = tick;
522
523 #ifndef NTP
524 if (tickfix) {
525 tickfixcnt += tickfix;
526 if (tickfixcnt >= tickfixinterval) {
527 delta++;
528 tickfixcnt -= tickfixinterval;
529 }
530 }
531 #endif /* !NTP */
532 /* Imprecise 4bsd adjtime() handling */
533 if (timedelta != 0) {
534 delta += tickdelta;
535 timedelta -= tickdelta;
536 }
537
538 #ifdef notyet
539 microset();
540 #endif
541
542 #ifndef NTP
543 BUMPTIME(&time, delta); /* XXX Now done using NTP code below */
544 #endif
545 BUMPTIME(&mono_time, delta);
546
547 #ifdef NTP
548 time_update = delta;
549
550 /*
551 * Compute the phase adjustment. If the low-order bits
552 * (time_phase) of the update overflow, bump the high-order bits
553 * (time_update).
554 */
555 time_phase += time_adj;
556 if (time_phase <= -FINEUSEC) {
557 ltemp = -time_phase >> SHIFT_SCALE;
558 time_phase += ltemp << SHIFT_SCALE;
559 time_update -= ltemp;
560 } else if (time_phase >= FINEUSEC) {
561 ltemp = time_phase >> SHIFT_SCALE;
562 time_phase -= ltemp << SHIFT_SCALE;
563 time_update += ltemp;
564 }
565
566 #ifdef HIGHBALL
567 /*
568 * If the HIGHBALL board is installed, we need to adjust the
569 * external clock offset in order to close the hardware feedback
570 * loop. This will adjust the external clock phase and frequency
571 * in small amounts. The additional phase noise and frequency
572 * wander this causes should be minimal. We also need to
573 * discipline the kernel time variable, since the PLL is used to
574 * discipline the external clock. If the Highball board is not
575 * present, we discipline kernel time with the PLL as usual. We
576 * assume that the external clock phase adjustment (time_update)
577 * and kernel phase adjustment (clock_cpu) are less than the
578 * value of tick.
579 */
580 clock_offset.tv_usec += time_update;
581 if (clock_offset.tv_usec >= 1000000) {
582 clock_offset.tv_sec++;
583 clock_offset.tv_usec -= 1000000;
584 }
585 if (clock_offset.tv_usec < 0) {
586 clock_offset.tv_sec--;
587 clock_offset.tv_usec += 1000000;
588 }
589 time.tv_usec += clock_cpu;
590 clock_cpu = 0;
591 #else
592 time.tv_usec += time_update;
593 #endif /* HIGHBALL */
594
595 /*
596 * On rollover of the second the phase adjustment to be used for
597 * the next second is calculated. Also, the maximum error is
598 * increased by the tolerance. If the PPS frequency discipline
599 * code is present, the phase is increased to compensate for the
600 * CPU clock oscillator frequency error.
601 *
602 * On a 32-bit machine and given parameters in the timex.h
603 * header file, the maximum phase adjustment is +-512 ms and
604 * maximum frequency offset is a tad less than) +-512 ppm. On a
605 * 64-bit machine, you shouldn't need to ask.
606 */
607 if (time.tv_usec >= 1000000) {
608 time.tv_usec -= 1000000;
609 time.tv_sec++;
610 time_maxerror += time_tolerance >> SHIFT_USEC;
611
612 /*
613 * Leap second processing. If in leap-insert state at
614 * the end of the day, the system clock is set back one
615 * second; if in leap-delete state, the system clock is
616 * set ahead one second. The microtime() routine or
617 * external clock driver will insure that reported time
618 * is always monotonic. The ugly divides should be
619 * replaced.
620 */
621 switch (time_state) {
622 case TIME_OK:
623 if (time_status & STA_INS)
624 time_state = TIME_INS;
625 else if (time_status & STA_DEL)
626 time_state = TIME_DEL;
627 break;
628
629 case TIME_INS:
630 if (time.tv_sec % 86400 == 0) {
631 time.tv_sec--;
632 time_state = TIME_OOP;
633 }
634 break;
635
636 case TIME_DEL:
637 if ((time.tv_sec + 1) % 86400 == 0) {
638 time.tv_sec++;
639 time_state = TIME_WAIT;
640 }
641 break;
642
643 case TIME_OOP:
644 time_state = TIME_WAIT;
645 break;
646
647 case TIME_WAIT:
648 if (!(time_status & (STA_INS | STA_DEL)))
649 time_state = TIME_OK;
650 break;
651 }
652
653 /*
654 * Compute the phase adjustment for the next second. In
655 * PLL mode, the offset is reduced by a fixed factor
656 * times the time constant. In FLL mode the offset is
657 * used directly. In either mode, the maximum phase
658 * adjustment for each second is clamped so as to spread
659 * the adjustment over not more than the number of
660 * seconds between updates.
661 */
662 if (time_offset < 0) {
663 ltemp = -time_offset;
664 if (!(time_status & STA_FLL))
665 ltemp >>= SHIFT_KG + time_constant;
666 if (ltemp > (MAXPHASE / MINSEC) << SHIFT_UPDATE)
667 ltemp = (MAXPHASE / MINSEC) <<
668 SHIFT_UPDATE;
669 time_offset += ltemp;
670 time_adj = -ltemp << (shifthz - SHIFT_UPDATE);
671 } else if (time_offset > 0) {
672 ltemp = time_offset;
673 if (!(time_status & STA_FLL))
674 ltemp >>= SHIFT_KG + time_constant;
675 if (ltemp > (MAXPHASE / MINSEC) << SHIFT_UPDATE)
676 ltemp = (MAXPHASE / MINSEC) <<
677 SHIFT_UPDATE;
678 time_offset -= ltemp;
679 time_adj = ltemp << (shifthz - SHIFT_UPDATE);
680 } else
681 time_adj = 0;
682
683 /*
684 * Compute the frequency estimate and additional phase
685 * adjustment due to frequency error for the next
686 * second. When the PPS signal is engaged, gnaw on the
687 * watchdog counter and update the frequency computed by
688 * the pll and the PPS signal.
689 */
690 #ifdef PPS_SYNC
691 pps_valid++;
692 if (pps_valid == PPS_VALID) {
693 pps_jitter = MAXTIME;
694 pps_stabil = MAXFREQ;
695 time_status &= ~(STA_PPSSIGNAL | STA_PPSJITTER |
696 STA_PPSWANDER | STA_PPSERROR);
697 }
698 ltemp = time_freq + pps_freq;
699 #else
700 ltemp = time_freq;
701 #endif /* PPS_SYNC */
702
703 if (ltemp < 0)
704 time_adj -= -ltemp >> (SHIFT_USEC - shifthz);
705 else
706 time_adj += ltemp >> (SHIFT_USEC - shifthz);
707 time_adj += (long)fixtick << shifthz;
708
709 /*
710 * When the CPU clock oscillator frequency is not a
711 * power of 2 in Hz, shifthz is only an approximate
712 * scale factor.
713 *
714 * To determine the adjustment, you can do the following:
715 * bc -q
716 * scale=24
717 * obase=2
718 * idealhz/realhz
719 * where `idealhz' is the next higher power of 2, and `realhz'
720 * is the actual value. You may need to factor this result
721 * into a sequence of 2 multipliers to get better precision.
722 *
723 * Likewise, the error can be calculated with (e.g. for 100Hz):
724 * bc -q
725 * scale=24
726 * ((1+2^-2+2^-5)*(1-2^-10)*realhz-idealhz)/idealhz
727 * (and then multiply by 1000000 to get ppm).
728 */
729 switch (hz) {
730 case 60:
731 /* A factor of 1.000100010001 gives about 15ppm
732 error. */
733 if (time_adj < 0) {
734 time_adj -= (-time_adj >> 4);
735 time_adj -= (-time_adj >> 8);
736 } else {
737 time_adj += (time_adj >> 4);
738 time_adj += (time_adj >> 8);
739 }
740 break;
741
742 case 96:
743 /* A factor of 1.0101010101 gives about 244ppm error. */
744 if (time_adj < 0) {
745 time_adj -= (-time_adj >> 2);
746 time_adj -= (-time_adj >> 4) + (-time_adj >> 8);
747 } else {
748 time_adj += (time_adj >> 2);
749 time_adj += (time_adj >> 4) + (time_adj >> 8);
750 }
751 break;
752
753 case 50:
754 case 100:
755 /* A factor of 1.010001111010111 gives about 1ppm
756 error. */
757 if (time_adj < 0) {
758 time_adj -= (-time_adj >> 2) + (-time_adj >> 5);
759 time_adj += (-time_adj >> 10);
760 } else {
761 time_adj += (time_adj >> 2) + (time_adj >> 5);
762 time_adj -= (time_adj >> 10);
763 }
764 break;
765
766 case 1000:
767 /* A factor of 1.000001100010100001 gives about 50ppm
768 error. */
769 if (time_adj < 0) {
770 time_adj -= (-time_adj >> 6) + (-time_adj >> 11);
771 time_adj -= (-time_adj >> 7);
772 } else {
773 time_adj += (time_adj >> 6) + (time_adj >> 11);
774 time_adj += (time_adj >> 7);
775 }
776 break;
777
778 case 1200:
779 /* A factor of 1.1011010011100001 gives about 64ppm
780 error. */
781 if (time_adj < 0) {
782 time_adj -= (-time_adj >> 1) + (-time_adj >> 6);
783 time_adj -= (-time_adj >> 3) + (-time_adj >> 10);
784 } else {
785 time_adj += (time_adj >> 1) + (time_adj >> 6);
786 time_adj += (time_adj >> 3) + (time_adj >> 10);
787 }
788 break;
789 }
790
791 #ifdef EXT_CLOCK
792 /*
793 * If an external clock is present, it is necessary to
794 * discipline the kernel time variable anyway, since not
795 * all system components use the microtime() interface.
796 * Here, the time offset between the external clock and
797 * kernel time variable is computed every so often.
798 */
799 clock_count++;
800 if (clock_count > CLOCK_INTERVAL) {
801 clock_count = 0;
802 microtime(&clock_ext);
803 delta.tv_sec = clock_ext.tv_sec - time.tv_sec;
804 delta.tv_usec = clock_ext.tv_usec -
805 time.tv_usec;
806 if (delta.tv_usec < 0)
807 delta.tv_sec--;
808 if (delta.tv_usec >= 500000) {
809 delta.tv_usec -= 1000000;
810 delta.tv_sec++;
811 }
812 if (delta.tv_usec < -500000) {
813 delta.tv_usec += 1000000;
814 delta.tv_sec--;
815 }
816 if (delta.tv_sec > 0 || (delta.tv_sec == 0 &&
817 delta.tv_usec > MAXPHASE) ||
818 delta.tv_sec < -1 || (delta.tv_sec == -1 &&
819 delta.tv_usec < -MAXPHASE)) {
820 time = clock_ext;
821 delta.tv_sec = 0;
822 delta.tv_usec = 0;
823 }
824 #ifdef HIGHBALL
825 clock_cpu = delta.tv_usec;
826 #else /* HIGHBALL */
827 hardupdate(delta.tv_usec);
828 #endif /* HIGHBALL */
829 }
830 #endif /* EXT_CLOCK */
831 }
832
833 #endif /* NTP */
834
835 /*
836 * Update real-time timeout queue.
837 * Process callouts at a very low CPU priority, so we don't keep the
838 * relatively high clock interrupt priority any longer than necessary.
839 */
840 if (callout_hardclock()) {
841 if (CLKF_BASEPRI(frame)) {
842 /*
843 * Save the overhead of a software interrupt;
844 * it will happen as soon as we return, so do
845 * it now.
846 */
847 spllowersoftclock();
848 KERNEL_LOCK(LK_CANRECURSE|LK_EXCLUSIVE);
849 softclock(NULL);
850 KERNEL_UNLOCK();
851 } else {
852 #ifdef __HAVE_GENERIC_SOFT_INTERRUPTS
853 softintr_schedule(softclock_si);
854 #else
855 setsoftclock();
856 #endif
857 }
858 }
859 }
860
861 /*
862 * Compute number of hz until specified time. Used to compute second
863 * argument to callout_reset() from an absolute time.
864 */
865 int
866 hzto(struct timeval *tv)
867 {
868 unsigned long ticks;
869 long sec, usec;
870 int s;
871
872 /*
873 * If the number of usecs in the whole seconds part of the time
874 * difference fits in a long, then the total number of usecs will
875 * fit in an unsigned long. Compute the total and convert it to
876 * ticks, rounding up and adding 1 to allow for the current tick
877 * to expire. Rounding also depends on unsigned long arithmetic
878 * to avoid overflow.
879 *
880 * Otherwise, if the number of ticks in the whole seconds part of
881 * the time difference fits in a long, then convert the parts to
882 * ticks separately and add, using similar rounding methods and
883 * overflow avoidance. This method would work in the previous
884 * case, but it is slightly slower and assume that hz is integral.
885 *
886 * Otherwise, round the time difference down to the maximum
887 * representable value.
888 *
889 * If ints are 32-bit, then the maximum value for any timeout in
890 * 10ms ticks is 248 days.
891 */
892 s = splclock();
893 sec = tv->tv_sec - time.tv_sec;
894 usec = tv->tv_usec - time.tv_usec;
895 splx(s);
896
897 if (usec < 0) {
898 sec--;
899 usec += 1000000;
900 }
901
902 if (sec < 0 || (sec == 0 && usec <= 0)) {
903 /*
904 * Would expire now or in the past. Return 0 ticks.
905 * This is different from the legacy hzto() interface,
906 * and callers need to check for it.
907 */
908 ticks = 0;
909 } else if (sec <= (LONG_MAX / 1000000))
910 ticks = (((sec * 1000000) + (unsigned long)usec + (tick - 1))
911 / tick) + 1;
912 else if (sec <= (LONG_MAX / hz))
913 ticks = (sec * hz) +
914 (((unsigned long)usec + (tick - 1)) / tick) + 1;
915 else
916 ticks = LONG_MAX;
917
918 if (ticks > INT_MAX)
919 ticks = INT_MAX;
920
921 return ((int)ticks);
922 }
923
924 /*
925 * Start profiling on a process.
926 *
927 * Kernel profiling passes proc0 which never exits and hence
928 * keeps the profile clock running constantly.
929 */
930 void
931 startprofclock(struct proc *p)
932 {
933
934 if ((p->p_flag & P_PROFIL) == 0) {
935 p->p_flag |= P_PROFIL;
936 /*
937 * This is only necessary if using the clock as the
938 * profiling source.
939 */
940 if (++profprocs == 1 && stathz != 0)
941 psdiv = psratio;
942 }
943 }
944
945 /*
946 * Stop profiling on a process.
947 */
948 void
949 stopprofclock(struct proc *p)
950 {
951
952 if (p->p_flag & P_PROFIL) {
953 p->p_flag &= ~P_PROFIL;
954 /*
955 * This is only necessary if using the clock as the
956 * profiling source.
957 */
958 if (--profprocs == 0 && stathz != 0)
959 psdiv = 1;
960 }
961 }
962
963 #if defined(PERFCTRS)
964 /*
965 * Independent profiling "tick" in case we're using a separate
966 * clock or profiling event source. Currently, that's just
967 * performance counters--hence the wrapper.
968 */
969 void
970 proftick(struct clockframe *frame)
971 {
972 #ifdef GPROF
973 struct gmonparam *g;
974 intptr_t i;
975 #endif
976 struct proc *p;
977
978 p = curproc;
979 if (CLKF_USERMODE(frame)) {
980 if (p->p_flag & P_PROFIL)
981 addupc_intr(p, CLKF_PC(frame));
982 } else {
983 #ifdef GPROF
984 g = &_gmonparam;
985 if (g->state == GMON_PROF_ON) {
986 i = CLKF_PC(frame) - g->lowpc;
987 if (i < g->textsize) {
988 i /= HISTFRACTION * sizeof(*g->kcount);
989 g->kcount[i]++;
990 }
991 }
992 #endif
993 #ifdef PROC_PC
994 if (p && p->p_flag & P_PROFIL)
995 addupc_intr(p, PROC_PC(p));
996 #endif
997 }
998 }
999 #endif
1000
1001 /*
1002 * Statistics clock. Grab profile sample, and if divider reaches 0,
1003 * do process and kernel statistics.
1004 */
1005 void
1006 statclock(struct clockframe *frame)
1007 {
1008 #ifdef GPROF
1009 struct gmonparam *g;
1010 intptr_t i;
1011 #endif
1012 struct cpu_info *ci = curcpu();
1013 struct schedstate_percpu *spc = &ci->ci_schedstate;
1014 struct lwp *l;
1015 struct proc *p;
1016
1017 /*
1018 * Notice changes in divisor frequency, and adjust clock
1019 * frequency accordingly.
1020 */
1021 if (spc->spc_psdiv != psdiv) {
1022 spc->spc_psdiv = psdiv;
1023 spc->spc_pscnt = psdiv;
1024 if (psdiv == 1) {
1025 setstatclockrate(stathz);
1026 } else {
1027 setstatclockrate(profhz);
1028 }
1029 }
1030 l = curlwp;
1031 p = (l ? l->l_proc : 0);
1032 if (CLKF_USERMODE(frame)) {
1033 if (p->p_flag & P_PROFIL && profsrc == PROFSRC_CLOCK)
1034 addupc_intr(p, CLKF_PC(frame));
1035 if (--spc->spc_pscnt > 0)
1036 return;
1037 /*
1038 * Came from user mode; CPU was in user state.
1039 * If this process is being profiled record the tick.
1040 */
1041 p->p_uticks++;
1042 if (p->p_nice > NZERO)
1043 spc->spc_cp_time[CP_NICE]++;
1044 else
1045 spc->spc_cp_time[CP_USER]++;
1046 } else {
1047 #ifdef GPROF
1048 /*
1049 * Kernel statistics are just like addupc_intr, only easier.
1050 */
1051 g = &_gmonparam;
1052 if (profsrc == PROFSRC_CLOCK && g->state == GMON_PROF_ON) {
1053 i = CLKF_PC(frame) - g->lowpc;
1054 if (i < g->textsize) {
1055 i /= HISTFRACTION * sizeof(*g->kcount);
1056 g->kcount[i]++;
1057 }
1058 }
1059 #endif
1060 #ifdef LWP_PC
1061 if (p && profsrc == PROFSRC_CLOCK && p->p_flag & P_PROFIL)
1062 addupc_intr(p, LWP_PC(l));
1063 #endif
1064 if (--spc->spc_pscnt > 0)
1065 return;
1066 /*
1067 * Came from kernel mode, so we were:
1068 * - handling an interrupt,
1069 * - doing syscall or trap work on behalf of the current
1070 * user process, or
1071 * - spinning in the idle loop.
1072 * Whichever it is, charge the time as appropriate.
1073 * Note that we charge interrupts to the current process,
1074 * regardless of whether they are ``for'' that process,
1075 * so that we know how much of its real time was spent
1076 * in ``non-process'' (i.e., interrupt) work.
1077 */
1078 if (CLKF_INTR(frame)) {
1079 if (p != NULL)
1080 p->p_iticks++;
1081 spc->spc_cp_time[CP_INTR]++;
1082 } else if (p != NULL) {
1083 p->p_sticks++;
1084 spc->spc_cp_time[CP_SYS]++;
1085 } else
1086 spc->spc_cp_time[CP_IDLE]++;
1087 }
1088 spc->spc_pscnt = psdiv;
1089
1090 if (l != NULL) {
1091 ++p->p_cpticks;
1092 /*
1093 * If no separate schedclock is provided, call it here
1094 * at about 16 Hz.
1095 */
1096 if (schedhz == 0)
1097 if ((int)(--ci->ci_schedstate.spc_schedticks) <= 0) {
1098 schedclock(l);
1099 ci->ci_schedstate.spc_schedticks = statscheddiv;
1100 }
1101 }
1102 }
1103
1104
1105 #ifdef NTP /* NTP phase-locked loop in kernel */
1106
1107 /*
1108 * hardupdate() - local clock update
1109 *
1110 * This routine is called by ntp_adjtime() to update the local clock
1111 * phase and frequency. The implementation is of an adaptive-parameter,
1112 * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new
1113 * time and frequency offset estimates for each call. If the kernel PPS
1114 * discipline code is configured (PPS_SYNC), the PPS signal itself
1115 * determines the new time offset, instead of the calling argument.
1116 * Presumably, calls to ntp_adjtime() occur only when the caller
1117 * believes the local clock is valid within some bound (+-128 ms with
1118 * NTP). If the caller's time is far different than the PPS time, an
1119 * argument will ensue, and it's not clear who will lose.
1120 *
1121 * For uncompensated quartz crystal oscillatores and nominal update
1122 * intervals less than 1024 s, operation should be in phase-lock mode
1123 * (STA_FLL = 0), where the loop is disciplined to phase. For update
1124 * intervals greater than thiss, operation should be in frequency-lock
1125 * mode (STA_FLL = 1), where the loop is disciplined to frequency.
1126 *
1127 * Note: splclock() is in effect.
1128 */
1129 void
1130 hardupdate(long offset)
1131 {
1132 long ltemp, mtemp;
1133
1134 if (!(time_status & STA_PLL) && !(time_status & STA_PPSTIME))
1135 return;
1136 ltemp = offset;
1137 #ifdef PPS_SYNC
1138 if (time_status & STA_PPSTIME && time_status & STA_PPSSIGNAL)
1139 ltemp = pps_offset;
1140 #endif /* PPS_SYNC */
1141
1142 /*
1143 * Scale the phase adjustment and clamp to the operating range.
1144 */
1145 if (ltemp > MAXPHASE)
1146 time_offset = MAXPHASE << SHIFT_UPDATE;
1147 else if (ltemp < -MAXPHASE)
1148 time_offset = -(MAXPHASE << SHIFT_UPDATE);
1149 else
1150 time_offset = ltemp << SHIFT_UPDATE;
1151
1152 /*
1153 * Select whether the frequency is to be controlled and in which
1154 * mode (PLL or FLL). Clamp to the operating range. Ugly
1155 * multiply/divide should be replaced someday.
1156 */
1157 if (time_status & STA_FREQHOLD || time_reftime == 0)
1158 time_reftime = time.tv_sec;
1159 mtemp = time.tv_sec - time_reftime;
1160 time_reftime = time.tv_sec;
1161 if (time_status & STA_FLL) {
1162 if (mtemp >= MINSEC) {
1163 ltemp = ((time_offset / mtemp) << (SHIFT_USEC -
1164 SHIFT_UPDATE));
1165 if (ltemp < 0)
1166 time_freq -= -ltemp >> SHIFT_KH;
1167 else
1168 time_freq += ltemp >> SHIFT_KH;
1169 }
1170 } else {
1171 if (mtemp < MAXSEC) {
1172 ltemp *= mtemp;
1173 if (ltemp < 0)
1174 time_freq -= -ltemp >> (time_constant +
1175 time_constant + SHIFT_KF -
1176 SHIFT_USEC);
1177 else
1178 time_freq += ltemp >> (time_constant +
1179 time_constant + SHIFT_KF -
1180 SHIFT_USEC);
1181 }
1182 }
1183 if (time_freq > time_tolerance)
1184 time_freq = time_tolerance;
1185 else if (time_freq < -time_tolerance)
1186 time_freq = -time_tolerance;
1187 }
1188
1189 #ifdef PPS_SYNC
1190 /*
1191 * hardpps() - discipline CPU clock oscillator to external PPS signal
1192 *
1193 * This routine is called at each PPS interrupt in order to discipline
1194 * the CPU clock oscillator to the PPS signal. It measures the PPS phase
1195 * and leaves it in a handy spot for the hardclock() routine. It
1196 * integrates successive PPS phase differences and calculates the
1197 * frequency offset. This is used in hardclock() to discipline the CPU
1198 * clock oscillator so that intrinsic frequency error is cancelled out.
1199 * The code requires the caller to capture the time and hardware counter
1200 * value at the on-time PPS signal transition.
1201 *
1202 * Note that, on some Unix systems, this routine runs at an interrupt
1203 * priority level higher than the timer interrupt routine hardclock().
1204 * Therefore, the variables used are distinct from the hardclock()
1205 * variables, except for certain exceptions: The PPS frequency pps_freq
1206 * and phase pps_offset variables are determined by this routine and
1207 * updated atomically. The time_tolerance variable can be considered a
1208 * constant, since it is infrequently changed, and then only when the
1209 * PPS signal is disabled. The watchdog counter pps_valid is updated
1210 * once per second by hardclock() and is atomically cleared in this
1211 * routine.
1212 */
1213 void
1214 hardpps(struct timeval *tvp, /* time at PPS */
1215 long usec /* hardware counter at PPS */)
1216 {
1217 long u_usec, v_usec, bigtick;
1218 long cal_sec, cal_usec;
1219
1220 /*
1221 * An occasional glitch can be produced when the PPS interrupt
1222 * occurs in the hardclock() routine before the time variable is
1223 * updated. Here the offset is discarded when the difference
1224 * between it and the last one is greater than tick/2, but not
1225 * if the interval since the first discard exceeds 30 s.
1226 */
1227 time_status |= STA_PPSSIGNAL;
1228 time_status &= ~(STA_PPSJITTER | STA_PPSWANDER | STA_PPSERROR);
1229 pps_valid = 0;
1230 u_usec = -tvp->tv_usec;
1231 if (u_usec < -500000)
1232 u_usec += 1000000;
1233 v_usec = pps_offset - u_usec;
1234 if (v_usec < 0)
1235 v_usec = -v_usec;
1236 if (v_usec > (tick >> 1)) {
1237 if (pps_glitch > MAXGLITCH) {
1238 pps_glitch = 0;
1239 pps_tf[2] = u_usec;
1240 pps_tf[1] = u_usec;
1241 } else {
1242 pps_glitch++;
1243 u_usec = pps_offset;
1244 }
1245 } else
1246 pps_glitch = 0;
1247
1248 /*
1249 * A three-stage median filter is used to help deglitch the pps
1250 * time. The median sample becomes the time offset estimate; the
1251 * difference between the other two samples becomes the time
1252 * dispersion (jitter) estimate.
1253 */
1254 pps_tf[2] = pps_tf[1];
1255 pps_tf[1] = pps_tf[0];
1256 pps_tf[0] = u_usec;
1257 if (pps_tf[0] > pps_tf[1]) {
1258 if (pps_tf[1] > pps_tf[2]) {
1259 pps_offset = pps_tf[1]; /* 0 1 2 */
1260 v_usec = pps_tf[0] - pps_tf[2];
1261 } else if (pps_tf[2] > pps_tf[0]) {
1262 pps_offset = pps_tf[0]; /* 2 0 1 */
1263 v_usec = pps_tf[2] - pps_tf[1];
1264 } else {
1265 pps_offset = pps_tf[2]; /* 0 2 1 */
1266 v_usec = pps_tf[0] - pps_tf[1];
1267 }
1268 } else {
1269 if (pps_tf[1] < pps_tf[2]) {
1270 pps_offset = pps_tf[1]; /* 2 1 0 */
1271 v_usec = pps_tf[2] - pps_tf[0];
1272 } else if (pps_tf[2] < pps_tf[0]) {
1273 pps_offset = pps_tf[0]; /* 1 0 2 */
1274 v_usec = pps_tf[1] - pps_tf[2];
1275 } else {
1276 pps_offset = pps_tf[2]; /* 1 2 0 */
1277 v_usec = pps_tf[1] - pps_tf[0];
1278 }
1279 }
1280 if (v_usec > MAXTIME)
1281 pps_jitcnt++;
1282 v_usec = (v_usec << PPS_AVG) - pps_jitter;
1283 if (v_usec < 0)
1284 pps_jitter -= -v_usec >> PPS_AVG;
1285 else
1286 pps_jitter += v_usec >> PPS_AVG;
1287 if (pps_jitter > (MAXTIME >> 1))
1288 time_status |= STA_PPSJITTER;
1289
1290 /*
1291 * During the calibration interval adjust the starting time when
1292 * the tick overflows. At the end of the interval compute the
1293 * duration of the interval and the difference of the hardware
1294 * counters at the beginning and end of the interval. This code
1295 * is deliciously complicated by the fact valid differences may
1296 * exceed the value of tick when using long calibration
1297 * intervals and small ticks. Note that the counter can be
1298 * greater than tick if caught at just the wrong instant, but
1299 * the values returned and used here are correct.
1300 */
1301 bigtick = (long)tick << SHIFT_USEC;
1302 pps_usec -= pps_freq;
1303 if (pps_usec >= bigtick)
1304 pps_usec -= bigtick;
1305 if (pps_usec < 0)
1306 pps_usec += bigtick;
1307 pps_time.tv_sec++;
1308 pps_count++;
1309 if (pps_count < (1 << pps_shift))
1310 return;
1311 pps_count = 0;
1312 pps_calcnt++;
1313 u_usec = usec << SHIFT_USEC;
1314 v_usec = pps_usec - u_usec;
1315 if (v_usec >= bigtick >> 1)
1316 v_usec -= bigtick;
1317 if (v_usec < -(bigtick >> 1))
1318 v_usec += bigtick;
1319 if (v_usec < 0)
1320 v_usec = -(-v_usec >> pps_shift);
1321 else
1322 v_usec = v_usec >> pps_shift;
1323 pps_usec = u_usec;
1324 cal_sec = tvp->tv_sec;
1325 cal_usec = tvp->tv_usec;
1326 cal_sec -= pps_time.tv_sec;
1327 cal_usec -= pps_time.tv_usec;
1328 if (cal_usec < 0) {
1329 cal_usec += 1000000;
1330 cal_sec--;
1331 }
1332 pps_time = *tvp;
1333
1334 /*
1335 * Check for lost interrupts, noise, excessive jitter and
1336 * excessive frequency error. The number of timer ticks during
1337 * the interval may vary +-1 tick. Add to this a margin of one
1338 * tick for the PPS signal jitter and maximum frequency
1339 * deviation. If the limits are exceeded, the calibration
1340 * interval is reset to the minimum and we start over.
1341 */
1342 u_usec = (long)tick << 1;
1343 if (!((cal_sec == -1 && cal_usec > (1000000 - u_usec))
1344 || (cal_sec == 0 && cal_usec < u_usec))
1345 || v_usec > time_tolerance || v_usec < -time_tolerance) {
1346 pps_errcnt++;
1347 pps_shift = PPS_SHIFT;
1348 pps_intcnt = 0;
1349 time_status |= STA_PPSERROR;
1350 return;
1351 }
1352
1353 /*
1354 * A three-stage median filter is used to help deglitch the pps
1355 * frequency. The median sample becomes the frequency offset
1356 * estimate; the difference between the other two samples
1357 * becomes the frequency dispersion (stability) estimate.
1358 */
1359 pps_ff[2] = pps_ff[1];
1360 pps_ff[1] = pps_ff[0];
1361 pps_ff[0] = v_usec;
1362 if (pps_ff[0] > pps_ff[1]) {
1363 if (pps_ff[1] > pps_ff[2]) {
1364 u_usec = pps_ff[1]; /* 0 1 2 */
1365 v_usec = pps_ff[0] - pps_ff[2];
1366 } else if (pps_ff[2] > pps_ff[0]) {
1367 u_usec = pps_ff[0]; /* 2 0 1 */
1368 v_usec = pps_ff[2] - pps_ff[1];
1369 } else {
1370 u_usec = pps_ff[2]; /* 0 2 1 */
1371 v_usec = pps_ff[0] - pps_ff[1];
1372 }
1373 } else {
1374 if (pps_ff[1] < pps_ff[2]) {
1375 u_usec = pps_ff[1]; /* 2 1 0 */
1376 v_usec = pps_ff[2] - pps_ff[0];
1377 } else if (pps_ff[2] < pps_ff[0]) {
1378 u_usec = pps_ff[0]; /* 1 0 2 */
1379 v_usec = pps_ff[1] - pps_ff[2];
1380 } else {
1381 u_usec = pps_ff[2]; /* 1 2 0 */
1382 v_usec = pps_ff[1] - pps_ff[0];
1383 }
1384 }
1385
1386 /*
1387 * Here the frequency dispersion (stability) is updated. If it
1388 * is less than one-fourth the maximum (MAXFREQ), the frequency
1389 * offset is updated as well, but clamped to the tolerance. It
1390 * will be processed later by the hardclock() routine.
1391 */
1392 v_usec = (v_usec >> 1) - pps_stabil;
1393 if (v_usec < 0)
1394 pps_stabil -= -v_usec >> PPS_AVG;
1395 else
1396 pps_stabil += v_usec >> PPS_AVG;
1397 if (pps_stabil > MAXFREQ >> 2) {
1398 pps_stbcnt++;
1399 time_status |= STA_PPSWANDER;
1400 return;
1401 }
1402 if (time_status & STA_PPSFREQ) {
1403 if (u_usec < 0) {
1404 pps_freq -= -u_usec >> PPS_AVG;
1405 if (pps_freq < -time_tolerance)
1406 pps_freq = -time_tolerance;
1407 u_usec = -u_usec;
1408 } else {
1409 pps_freq += u_usec >> PPS_AVG;
1410 if (pps_freq > time_tolerance)
1411 pps_freq = time_tolerance;
1412 }
1413 }
1414
1415 /*
1416 * Here the calibration interval is adjusted. If the maximum
1417 * time difference is greater than tick / 4, reduce the interval
1418 * by half. If this is not the case for four consecutive
1419 * intervals, double the interval.
1420 */
1421 if (u_usec << pps_shift > bigtick >> 2) {
1422 pps_intcnt = 0;
1423 if (pps_shift > PPS_SHIFT)
1424 pps_shift--;
1425 } else if (pps_intcnt >= 4) {
1426 pps_intcnt = 0;
1427 if (pps_shift < PPS_SHIFTMAX)
1428 pps_shift++;
1429 } else
1430 pps_intcnt++;
1431 }
1432 #endif /* PPS_SYNC */
1433 #endif /* NTP */
Cache object: b25cbd4ff76b9c93e8701ff0540d5137
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