FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_clock.c
1 /* $NetBSD: kern_clock.c,v 1.104 2006/11/01 10:17:58 yamt 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 1.104 2006/11/01 10:17:58 yamt 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 #ifdef __HAVE_TIMECOUNTER
97 #include <sys/timetc.h>
98 #endif
99
100 #include <machine/cpu.h>
101 #ifdef __HAVE_GENERIC_SOFT_INTERRUPTS
102 #include <machine/intr.h>
103 #endif
104
105 #ifdef GPROF
106 #include <sys/gmon.h>
107 #endif
108
109 /*
110 * Clock handling routines.
111 *
112 * This code is written to operate with two timers that run independently of
113 * each other. The main clock, running hz times per second, is used to keep
114 * track of real time. The second timer handles kernel and user profiling,
115 * and does resource use estimation. If the second timer is programmable,
116 * it is randomized to avoid aliasing between the two clocks. For example,
117 * the randomization prevents an adversary from always giving up the CPU
118 * just before its quantum expires. Otherwise, it would never accumulate
119 * CPU ticks. The mean frequency of the second timer is stathz.
120 *
121 * If no second timer exists, stathz will be zero; in this case we drive
122 * profiling and statistics off the main clock. This WILL NOT be accurate;
123 * do not do it unless absolutely necessary.
124 *
125 * The statistics clock may (or may not) be run at a higher rate while
126 * profiling. This profile clock runs at profhz. We require that profhz
127 * be an integral multiple of stathz.
128 *
129 * If the statistics clock is running fast, it must be divided by the ratio
130 * profhz/stathz for statistics. (For profiling, every tick counts.)
131 */
132
133 #ifndef __HAVE_TIMECOUNTER
134 #ifdef NTP /* NTP phase-locked loop in kernel */
135 /*
136 * Phase/frequency-lock loop (PLL/FLL) definitions
137 *
138 * The following variables are read and set by the ntp_adjtime() system
139 * call.
140 *
141 * time_state shows the state of the system clock, with values defined
142 * in the timex.h header file.
143 *
144 * time_status shows the status of the system clock, with bits defined
145 * in the timex.h header file.
146 *
147 * time_offset is used by the PLL/FLL to adjust the system time in small
148 * increments.
149 *
150 * time_constant determines the bandwidth or "stiffness" of the PLL.
151 *
152 * time_tolerance determines maximum frequency error or tolerance of the
153 * CPU clock oscillator and is a property of the architecture; however,
154 * in principle it could change as result of the presence of external
155 * discipline signals, for instance.
156 *
157 * time_precision is usually equal to the kernel tick variable; however,
158 * in cases where a precision clock counter or external clock is
159 * available, the resolution can be much less than this and depend on
160 * whether the external clock is working or not.
161 *
162 * time_maxerror is initialized by a ntp_adjtime() call and increased by
163 * the kernel once each second to reflect the maximum error bound
164 * growth.
165 *
166 * time_esterror is set and read by the ntp_adjtime() call, but
167 * otherwise not used by the kernel.
168 */
169 int time_state = TIME_OK; /* clock state */
170 int time_status = STA_UNSYNC; /* clock status bits */
171 long time_offset = 0; /* time offset (us) */
172 long time_constant = 0; /* pll time constant */
173 long time_tolerance = MAXFREQ; /* frequency tolerance (scaled ppm) */
174 long time_precision = 1; /* clock precision (us) */
175 long time_maxerror = MAXPHASE; /* maximum error (us) */
176 long time_esterror = MAXPHASE; /* estimated error (us) */
177
178 /*
179 * The following variables establish the state of the PLL/FLL and the
180 * residual time and frequency offset of the local clock. The scale
181 * factors are defined in the timex.h header file.
182 *
183 * time_phase and time_freq are the phase increment and the frequency
184 * increment, respectively, of the kernel time variable.
185 *
186 * time_freq is set via ntp_adjtime() from a value stored in a file when
187 * the synchronization daemon is first started. Its value is retrieved
188 * via ntp_adjtime() and written to the file about once per hour by the
189 * daemon.
190 *
191 * time_adj is the adjustment added to the value of tick at each timer
192 * interrupt and is recomputed from time_phase and time_freq at each
193 * seconds rollover.
194 *
195 * time_reftime is the second's portion of the system time at the last
196 * call to ntp_adjtime(). It is used to adjust the time_freq variable
197 * and to increase the time_maxerror as the time since last update
198 * increases.
199 */
200 long time_phase = 0; /* phase offset (scaled us) */
201 long time_freq = 0; /* frequency offset (scaled ppm) */
202 long time_adj = 0; /* tick adjust (scaled 1 / hz) */
203 long time_reftime = 0; /* time at last adjustment (s) */
204
205 #ifdef PPS_SYNC
206 /*
207 * The following variables are used only if the kernel PPS discipline
208 * code is configured (PPS_SYNC). The scale factors are defined in the
209 * timex.h header file.
210 *
211 * pps_time contains the time at each calibration interval, as read by
212 * microtime(). pps_count counts the seconds of the calibration
213 * interval, the duration of which is nominally pps_shift in powers of
214 * two.
215 *
216 * pps_offset is the time offset produced by the time median filter
217 * pps_tf[], while pps_jitter is the dispersion (jitter) measured by
218 * this filter.
219 *
220 * pps_freq is the frequency offset produced by the frequency median
221 * filter pps_ff[], while pps_stabil is the dispersion (wander) measured
222 * by this filter.
223 *
224 * pps_usec is latched from a high resolution counter or external clock
225 * at pps_time. Here we want the hardware counter contents only, not the
226 * contents plus the time_tv.usec as usual.
227 *
228 * pps_valid counts the number of seconds since the last PPS update. It
229 * is used as a watchdog timer to disable the PPS discipline should the
230 * PPS signal be lost.
231 *
232 * pps_glitch counts the number of seconds since the beginning of an
233 * offset burst more than tick/2 from current nominal offset. It is used
234 * mainly to suppress error bursts due to priority conflicts between the
235 * PPS interrupt and timer interrupt.
236 *
237 * pps_intcnt counts the calibration intervals for use in the interval-
238 * adaptation algorithm. It's just too complicated for words.
239 *
240 * pps_kc_hardpps_source contains an arbitrary value that uniquely
241 * identifies the currently bound source of the PPS signal, or NULL
242 * if no source is bound.
243 *
244 * pps_kc_hardpps_mode indicates which transitions, if any, of the PPS
245 * signal should be reported.
246 */
247 struct timeval pps_time; /* kernel time at last interval */
248 long pps_tf[] = {0, 0, 0}; /* pps time offset median filter (us) */
249 long pps_offset = 0; /* pps time offset (us) */
250 long pps_jitter = MAXTIME; /* time dispersion (jitter) (us) */
251 long pps_ff[] = {0, 0, 0}; /* pps frequency offset median filter */
252 long pps_freq = 0; /* frequency offset (scaled ppm) */
253 long pps_stabil = MAXFREQ; /* frequency dispersion (scaled ppm) */
254 long pps_usec = 0; /* microsec counter at last interval */
255 long pps_valid = PPS_VALID; /* pps signal watchdog counter */
256 int pps_glitch = 0; /* pps signal glitch counter */
257 int pps_count = 0; /* calibration interval counter (s) */
258 int pps_shift = PPS_SHIFT; /* interval duration (s) (shift) */
259 int pps_intcnt = 0; /* intervals at current duration */
260 void *pps_kc_hardpps_source = NULL; /* current PPS supplier's identifier */
261 int pps_kc_hardpps_mode = 0; /* interesting edges of PPS signal */
262
263 /*
264 * PPS signal quality monitors
265 *
266 * pps_jitcnt counts the seconds that have been discarded because the
267 * jitter measured by the time median filter exceeds the limit MAXTIME
268 * (100 us).
269 *
270 * pps_calcnt counts the frequency calibration intervals, which are
271 * variable from 4 s to 256 s.
272 *
273 * pps_errcnt counts the calibration intervals which have been discarded
274 * because the wander exceeds the limit MAXFREQ (100 ppm) or where the
275 * calibration interval jitter exceeds two ticks.
276 *
277 * pps_stbcnt counts the calibration intervals that have been discarded
278 * because the frequency wander exceeds the limit MAXFREQ / 4 (25 us).
279 */
280 long pps_jitcnt = 0; /* jitter limit exceeded */
281 long pps_calcnt = 0; /* calibration intervals */
282 long pps_errcnt = 0; /* calibration errors */
283 long pps_stbcnt = 0; /* stability limit exceeded */
284 #endif /* PPS_SYNC */
285
286 #ifdef EXT_CLOCK
287 /*
288 * External clock definitions
289 *
290 * The following definitions and declarations are used only if an
291 * external clock is configured on the system.
292 */
293 #define CLOCK_INTERVAL 30 /* CPU clock update interval (s) */
294
295 /*
296 * The clock_count variable is set to CLOCK_INTERVAL at each PPS
297 * interrupt and decremented once each second.
298 */
299 int clock_count = 0; /* CPU clock counter */
300
301 #ifdef HIGHBALL
302 /*
303 * The clock_offset and clock_cpu variables are used by the HIGHBALL
304 * interface. The clock_offset variable defines the offset between
305 * system time and the HIGBALL counters. The clock_cpu variable contains
306 * the offset between the system clock and the HIGHBALL clock for use in
307 * disciplining the kernel time variable.
308 */
309 extern struct timeval clock_offset; /* Highball clock offset */
310 long clock_cpu = 0; /* CPU clock adjust */
311 #endif /* HIGHBALL */
312 #endif /* EXT_CLOCK */
313 #endif /* NTP */
314
315 /*
316 * Bump a timeval by a small number of usec's.
317 */
318 #define BUMPTIME(t, usec) { \
319 volatile struct timeval *tp = (t); \
320 long us; \
321 \
322 tp->tv_usec = us = tp->tv_usec + (usec); \
323 if (us >= 1000000) { \
324 tp->tv_usec = us - 1000000; \
325 tp->tv_sec++; \
326 } \
327 }
328 #endif /* !__HAVE_TIMECOUNTER */
329
330 int stathz;
331 int profhz;
332 int profsrc;
333 int schedhz;
334 int profprocs;
335 int hardclock_ticks;
336 static int statscheddiv; /* stat => sched divider (used if schedhz == 0) */
337 static int psdiv; /* prof => stat divider */
338 int psratio; /* ratio: prof / stat */
339 #ifndef __HAVE_TIMECOUNTER
340 int tickfix, tickfixinterval; /* used if tick not really integral */
341 #ifndef NTP
342 static int tickfixcnt; /* accumulated fractional error */
343 #else
344 int fixtick; /* used by NTP for same */
345 int shifthz;
346 #endif
347
348 /*
349 * We might want ldd to load the both words from time at once.
350 * To succeed we need to be quadword aligned.
351 * The sparc already does that, and that it has worked so far is a fluke.
352 */
353 volatile struct timeval time __attribute__((__aligned__(__alignof__(quad_t))));
354 volatile struct timeval mono_time;
355 #endif /* !__HAVE_TIMECOUNTER */
356
357 #ifdef __HAVE_GENERIC_SOFT_INTERRUPTS
358 void *softclock_si;
359 #endif
360
361 #ifdef __HAVE_TIMECOUNTER
362 static u_int get_intr_timecount(struct timecounter *);
363
364 static struct timecounter intr_timecounter = {
365 get_intr_timecount, /* get_timecount */
366 0, /* no poll_pps */
367 ~0u, /* counter_mask */
368 0, /* frequency */
369 "clockinterrupt", /* name */
370 0, /* quality - minimum implementation level for a clock */
371 NULL, /* prev */
372 NULL, /* next */
373 };
374
375 static u_int
376 get_intr_timecount(struct timecounter *tc)
377 {
378
379 return (u_int)hardclock_ticks;
380 }
381 #endif
382
383 /*
384 * Initialize clock frequencies and start both clocks running.
385 */
386 void
387 initclocks(void)
388 {
389 int i;
390
391 #ifdef __HAVE_GENERIC_SOFT_INTERRUPTS
392 softclock_si = softintr_establish(IPL_SOFTCLOCK, softclock, NULL);
393 if (softclock_si == NULL)
394 panic("initclocks: unable to register softclock intr");
395 #endif
396
397 /*
398 * Set divisors to 1 (normal case) and let the machine-specific
399 * code do its bit.
400 */
401 psdiv = 1;
402 #ifdef __HAVE_TIMECOUNTER
403 /*
404 * provide minimum default time counter
405 * will only run at interrupt resolution
406 */
407 intr_timecounter.tc_frequency = hz;
408 tc_init(&intr_timecounter);
409 #endif
410 cpu_initclocks();
411
412 /*
413 * Compute profhz/stathz/rrticks, and fix profhz if needed.
414 */
415 i = stathz ? stathz : hz;
416 if (profhz == 0)
417 profhz = i;
418 psratio = profhz / i;
419 rrticks = hz / 10;
420 if (schedhz == 0) {
421 /* 16Hz is best */
422 statscheddiv = i / 16;
423 if (statscheddiv <= 0)
424 panic("statscheddiv");
425 }
426
427 #ifndef __HAVE_TIMECOUNTER
428 #ifdef NTP
429 switch (hz) {
430 case 1:
431 shifthz = SHIFT_SCALE - 0;
432 break;
433 case 2:
434 shifthz = SHIFT_SCALE - 1;
435 break;
436 case 4:
437 shifthz = SHIFT_SCALE - 2;
438 break;
439 case 8:
440 shifthz = SHIFT_SCALE - 3;
441 break;
442 case 16:
443 shifthz = SHIFT_SCALE - 4;
444 break;
445 case 32:
446 shifthz = SHIFT_SCALE - 5;
447 break;
448 case 50:
449 case 60:
450 case 64:
451 shifthz = SHIFT_SCALE - 6;
452 break;
453 case 96:
454 case 100:
455 case 128:
456 shifthz = SHIFT_SCALE - 7;
457 break;
458 case 256:
459 shifthz = SHIFT_SCALE - 8;
460 break;
461 case 512:
462 shifthz = SHIFT_SCALE - 9;
463 break;
464 case 1000:
465 case 1024:
466 shifthz = SHIFT_SCALE - 10;
467 break;
468 case 1200:
469 case 2048:
470 shifthz = SHIFT_SCALE - 11;
471 break;
472 case 4096:
473 shifthz = SHIFT_SCALE - 12;
474 break;
475 case 8192:
476 shifthz = SHIFT_SCALE - 13;
477 break;
478 case 16384:
479 shifthz = SHIFT_SCALE - 14;
480 break;
481 case 32768:
482 shifthz = SHIFT_SCALE - 15;
483 break;
484 case 65536:
485 shifthz = SHIFT_SCALE - 16;
486 break;
487 default:
488 panic("weird hz");
489 }
490 if (fixtick == 0) {
491 /*
492 * Give MD code a chance to set this to a better
493 * value; but, if it doesn't, we should.
494 */
495 fixtick = (1000000 - (hz*tick));
496 }
497 #endif /* NTP */
498 #endif /* !__HAVE_TIMECOUNTER */
499 }
500
501 /*
502 * The real-time timer, interrupting hz times per second.
503 */
504 void
505 hardclock(struct clockframe *frame)
506 {
507 struct lwp *l;
508 struct proc *p;
509 struct cpu_info *ci = curcpu();
510 struct ptimer *pt;
511 #ifndef __HAVE_TIMECOUNTER
512 int delta;
513 extern int tickdelta;
514 extern long timedelta;
515 #ifdef NTP
516 int time_update;
517 int ltemp;
518 #endif /* NTP */
519 #endif /* __HAVE_TIMECOUNTER */
520
521 l = curlwp;
522 if (l) {
523 p = l->l_proc;
524 /*
525 * Run current process's virtual and profile time, as needed.
526 */
527 if (CLKF_USERMODE(frame) && p->p_timers &&
528 (pt = LIST_FIRST(&p->p_timers->pts_virtual)) != NULL)
529 if (itimerdecr(pt, tick) == 0)
530 itimerfire(pt);
531 if (p->p_timers &&
532 (pt = LIST_FIRST(&p->p_timers->pts_prof)) != NULL)
533 if (itimerdecr(pt, tick) == 0)
534 itimerfire(pt);
535 }
536
537 /*
538 * If no separate statistics clock is available, run it from here.
539 */
540 if (stathz == 0)
541 statclock(frame);
542 if ((--ci->ci_schedstate.spc_rrticks) <= 0)
543 roundrobin(ci);
544
545 #if defined(MULTIPROCESSOR)
546 /*
547 * If we are not the primary CPU, we're not allowed to do
548 * any more work.
549 */
550 if (CPU_IS_PRIMARY(ci) == 0)
551 return;
552 #endif
553
554 hardclock_ticks++;
555
556 #ifdef __HAVE_TIMECOUNTER
557 tc_ticktock();
558 #else /* __HAVE_TIMECOUNTER */
559 /*
560 * Increment the time-of-day. The increment is normally just
561 * ``tick''. If the machine is one which has a clock frequency
562 * such that ``hz'' would not divide the second evenly into
563 * milliseconds, a periodic adjustment must be applied. Finally,
564 * if we are still adjusting the time (see adjtime()),
565 * ``tickdelta'' may also be added in.
566 */
567 delta = tick;
568
569 #ifndef NTP
570 if (tickfix) {
571 tickfixcnt += tickfix;
572 if (tickfixcnt >= tickfixinterval) {
573 delta++;
574 tickfixcnt -= tickfixinterval;
575 }
576 }
577 #endif /* !NTP */
578 /* Imprecise 4bsd adjtime() handling */
579 if (timedelta != 0) {
580 delta += tickdelta;
581 timedelta -= tickdelta;
582 }
583
584 #ifdef notyet
585 microset();
586 #endif
587
588 #ifndef NTP
589 BUMPTIME(&time, delta); /* XXX Now done using NTP code below */
590 #endif
591 BUMPTIME(&mono_time, delta);
592
593 #ifdef NTP
594 time_update = delta;
595
596 /*
597 * Compute the phase adjustment. If the low-order bits
598 * (time_phase) of the update overflow, bump the high-order bits
599 * (time_update).
600 */
601 time_phase += time_adj;
602 if (time_phase <= -FINEUSEC) {
603 ltemp = -time_phase >> SHIFT_SCALE;
604 time_phase += ltemp << SHIFT_SCALE;
605 time_update -= ltemp;
606 } else if (time_phase >= FINEUSEC) {
607 ltemp = time_phase >> SHIFT_SCALE;
608 time_phase -= ltemp << SHIFT_SCALE;
609 time_update += ltemp;
610 }
611
612 #ifdef HIGHBALL
613 /*
614 * If the HIGHBALL board is installed, we need to adjust the
615 * external clock offset in order to close the hardware feedback
616 * loop. This will adjust the external clock phase and frequency
617 * in small amounts. The additional phase noise and frequency
618 * wander this causes should be minimal. We also need to
619 * discipline the kernel time variable, since the PLL is used to
620 * discipline the external clock. If the Highball board is not
621 * present, we discipline kernel time with the PLL as usual. We
622 * assume that the external clock phase adjustment (time_update)
623 * and kernel phase adjustment (clock_cpu) are less than the
624 * value of tick.
625 */
626 clock_offset.tv_usec += time_update;
627 if (clock_offset.tv_usec >= 1000000) {
628 clock_offset.tv_sec++;
629 clock_offset.tv_usec -= 1000000;
630 }
631 if (clock_offset.tv_usec < 0) {
632 clock_offset.tv_sec--;
633 clock_offset.tv_usec += 1000000;
634 }
635 time.tv_usec += clock_cpu;
636 clock_cpu = 0;
637 #else
638 time.tv_usec += time_update;
639 #endif /* HIGHBALL */
640
641 /*
642 * On rollover of the second the phase adjustment to be used for
643 * the next second is calculated. Also, the maximum error is
644 * increased by the tolerance. If the PPS frequency discipline
645 * code is present, the phase is increased to compensate for the
646 * CPU clock oscillator frequency error.
647 *
648 * On a 32-bit machine and given parameters in the timex.h
649 * header file, the maximum phase adjustment is +-512 ms and
650 * maximum frequency offset is a tad less than) +-512 ppm. On a
651 * 64-bit machine, you shouldn't need to ask.
652 */
653 if (time.tv_usec >= 1000000) {
654 time.tv_usec -= 1000000;
655 time.tv_sec++;
656 time_maxerror += time_tolerance >> SHIFT_USEC;
657
658 /*
659 * Leap second processing. If in leap-insert state at
660 * the end of the day, the system clock is set back one
661 * second; if in leap-delete state, the system clock is
662 * set ahead one second. The microtime() routine or
663 * external clock driver will insure that reported time
664 * is always monotonic. The ugly divides should be
665 * replaced.
666 */
667 switch (time_state) {
668 case TIME_OK:
669 if (time_status & STA_INS)
670 time_state = TIME_INS;
671 else if (time_status & STA_DEL)
672 time_state = TIME_DEL;
673 break;
674
675 case TIME_INS:
676 if (time.tv_sec % 86400 == 0) {
677 time.tv_sec--;
678 time_state = TIME_OOP;
679 }
680 break;
681
682 case TIME_DEL:
683 if ((time.tv_sec + 1) % 86400 == 0) {
684 time.tv_sec++;
685 time_state = TIME_WAIT;
686 }
687 break;
688
689 case TIME_OOP:
690 time_state = TIME_WAIT;
691 break;
692
693 case TIME_WAIT:
694 if (!(time_status & (STA_INS | STA_DEL)))
695 time_state = TIME_OK;
696 break;
697 }
698
699 /*
700 * Compute the phase adjustment for the next second. In
701 * PLL mode, the offset is reduced by a fixed factor
702 * times the time constant. In FLL mode the offset is
703 * used directly. In either mode, the maximum phase
704 * adjustment for each second is clamped so as to spread
705 * the adjustment over not more than the number of
706 * seconds between updates.
707 */
708 if (time_offset < 0) {
709 ltemp = -time_offset;
710 if (!(time_status & STA_FLL))
711 ltemp >>= SHIFT_KG + time_constant;
712 if (ltemp > (MAXPHASE / MINSEC) << SHIFT_UPDATE)
713 ltemp = (MAXPHASE / MINSEC) <<
714 SHIFT_UPDATE;
715 time_offset += ltemp;
716 time_adj = -ltemp << (shifthz - SHIFT_UPDATE);
717 } else if (time_offset > 0) {
718 ltemp = time_offset;
719 if (!(time_status & STA_FLL))
720 ltemp >>= SHIFT_KG + time_constant;
721 if (ltemp > (MAXPHASE / MINSEC) << SHIFT_UPDATE)
722 ltemp = (MAXPHASE / MINSEC) <<
723 SHIFT_UPDATE;
724 time_offset -= ltemp;
725 time_adj = ltemp << (shifthz - SHIFT_UPDATE);
726 } else
727 time_adj = 0;
728
729 /*
730 * Compute the frequency estimate and additional phase
731 * adjustment due to frequency error for the next
732 * second. When the PPS signal is engaged, gnaw on the
733 * watchdog counter and update the frequency computed by
734 * the pll and the PPS signal.
735 */
736 #ifdef PPS_SYNC
737 pps_valid++;
738 if (pps_valid == PPS_VALID) {
739 pps_jitter = MAXTIME;
740 pps_stabil = MAXFREQ;
741 time_status &= ~(STA_PPSSIGNAL | STA_PPSJITTER |
742 STA_PPSWANDER | STA_PPSERROR);
743 }
744 ltemp = time_freq + pps_freq;
745 #else
746 ltemp = time_freq;
747 #endif /* PPS_SYNC */
748
749 if (ltemp < 0)
750 time_adj -= -ltemp >> (SHIFT_USEC - shifthz);
751 else
752 time_adj += ltemp >> (SHIFT_USEC - shifthz);
753 time_adj += (long)fixtick << shifthz;
754
755 /*
756 * When the CPU clock oscillator frequency is not a
757 * power of 2 in Hz, shifthz is only an approximate
758 * scale factor.
759 *
760 * To determine the adjustment, you can do the following:
761 * bc -q
762 * scale=24
763 * obase=2
764 * idealhz/realhz
765 * where `idealhz' is the next higher power of 2, and `realhz'
766 * is the actual value. You may need to factor this result
767 * into a sequence of 2 multipliers to get better precision.
768 *
769 * Likewise, the error can be calculated with (e.g. for 100Hz):
770 * bc -q
771 * scale=24
772 * ((1+2^-2+2^-5)*(1-2^-10)*realhz-idealhz)/idealhz
773 * (and then multiply by 1000000 to get ppm).
774 */
775 switch (hz) {
776 case 60:
777 /* A factor of 1.000100010001 gives about 15ppm
778 error. */
779 if (time_adj < 0) {
780 time_adj -= (-time_adj >> 4);
781 time_adj -= (-time_adj >> 8);
782 } else {
783 time_adj += (time_adj >> 4);
784 time_adj += (time_adj >> 8);
785 }
786 break;
787
788 case 96:
789 /* A factor of 1.0101010101 gives about 244ppm error. */
790 if (time_adj < 0) {
791 time_adj -= (-time_adj >> 2);
792 time_adj -= (-time_adj >> 4) + (-time_adj >> 8);
793 } else {
794 time_adj += (time_adj >> 2);
795 time_adj += (time_adj >> 4) + (time_adj >> 8);
796 }
797 break;
798
799 case 50:
800 case 100:
801 /* A factor of 1.010001111010111 gives about 1ppm
802 error. */
803 if (time_adj < 0) {
804 time_adj -= (-time_adj >> 2) + (-time_adj >> 5);
805 time_adj += (-time_adj >> 10);
806 } else {
807 time_adj += (time_adj >> 2) + (time_adj >> 5);
808 time_adj -= (time_adj >> 10);
809 }
810 break;
811
812 case 1000:
813 /* A factor of 1.000001100010100001 gives about 50ppm
814 error. */
815 if (time_adj < 0) {
816 time_adj -= (-time_adj >> 6) + (-time_adj >> 11);
817 time_adj -= (-time_adj >> 7);
818 } else {
819 time_adj += (time_adj >> 6) + (time_adj >> 11);
820 time_adj += (time_adj >> 7);
821 }
822 break;
823
824 case 1200:
825 /* A factor of 1.1011010011100001 gives about 64ppm
826 error. */
827 if (time_adj < 0) {
828 time_adj -= (-time_adj >> 1) + (-time_adj >> 6);
829 time_adj -= (-time_adj >> 3) + (-time_adj >> 10);
830 } else {
831 time_adj += (time_adj >> 1) + (time_adj >> 6);
832 time_adj += (time_adj >> 3) + (time_adj >> 10);
833 }
834 break;
835 }
836
837 #ifdef EXT_CLOCK
838 /*
839 * If an external clock is present, it is necessary to
840 * discipline the kernel time variable anyway, since not
841 * all system components use the microtime() interface.
842 * Here, the time offset between the external clock and
843 * kernel time variable is computed every so often.
844 */
845 clock_count++;
846 if (clock_count > CLOCK_INTERVAL) {
847 clock_count = 0;
848 microtime(&clock_ext);
849 delta.tv_sec = clock_ext.tv_sec - time.tv_sec;
850 delta.tv_usec = clock_ext.tv_usec -
851 time.tv_usec;
852 if (delta.tv_usec < 0)
853 delta.tv_sec--;
854 if (delta.tv_usec >= 500000) {
855 delta.tv_usec -= 1000000;
856 delta.tv_sec++;
857 }
858 if (delta.tv_usec < -500000) {
859 delta.tv_usec += 1000000;
860 delta.tv_sec--;
861 }
862 if (delta.tv_sec > 0 || (delta.tv_sec == 0 &&
863 delta.tv_usec > MAXPHASE) ||
864 delta.tv_sec < -1 || (delta.tv_sec == -1 &&
865 delta.tv_usec < -MAXPHASE)) {
866 time = clock_ext;
867 delta.tv_sec = 0;
868 delta.tv_usec = 0;
869 }
870 #ifdef HIGHBALL
871 clock_cpu = delta.tv_usec;
872 #else /* HIGHBALL */
873 hardupdate(delta.tv_usec);
874 #endif /* HIGHBALL */
875 }
876 #endif /* EXT_CLOCK */
877 }
878
879 #endif /* NTP */
880 #endif /* !__HAVE_TIMECOUNTER */
881
882 /*
883 * Update real-time timeout queue.
884 * Process callouts at a very low CPU priority, so we don't keep the
885 * relatively high clock interrupt priority any longer than necessary.
886 */
887 if (callout_hardclock()) {
888 if (CLKF_BASEPRI(frame)) {
889 /*
890 * Save the overhead of a software interrupt;
891 * it will happen as soon as we return, so do
892 * it now.
893 */
894 spllowersoftclock();
895 KERNEL_LOCK(LK_CANRECURSE|LK_EXCLUSIVE);
896 softclock(NULL);
897 KERNEL_UNLOCK();
898 } else {
899 #ifdef __HAVE_GENERIC_SOFT_INTERRUPTS
900 softintr_schedule(softclock_si);
901 #else
902 setsoftclock();
903 #endif
904 }
905 }
906 }
907
908 #ifdef __HAVE_TIMECOUNTER
909 /*
910 * Compute number of hz until specified time. Used to compute second
911 * argument to callout_reset() from an absolute time.
912 */
913 int
914 hzto(struct timeval *tvp)
915 {
916 struct timeval now, tv;
917
918 tv = *tvp; /* Don't modify original tvp. */
919 getmicrotime(&now);
920 timersub(&tv, &now, &tv);
921 return tvtohz(&tv);
922 }
923 #endif /* __HAVE_TIMECOUNTER */
924
925 /*
926 * Compute number of ticks in the specified amount of time.
927 */
928 int
929 tvtohz(struct timeval *tv)
930 {
931 unsigned long ticks;
932 long sec, usec;
933
934 /*
935 * If the number of usecs in the whole seconds part of the time
936 * difference fits in a long, then the total number of usecs will
937 * fit in an unsigned long. Compute the total and convert it to
938 * ticks, rounding up and adding 1 to allow for the current tick
939 * to expire. Rounding also depends on unsigned long arithmetic
940 * to avoid overflow.
941 *
942 * Otherwise, if the number of ticks in the whole seconds part of
943 * the time difference fits in a long, then convert the parts to
944 * ticks separately and add, using similar rounding methods and
945 * overflow avoidance. This method would work in the previous
946 * case, but it is slightly slower and assumes that hz is integral.
947 *
948 * Otherwise, round the time difference down to the maximum
949 * representable value.
950 *
951 * If ints are 32-bit, then the maximum value for any timeout in
952 * 10ms ticks is 248 days.
953 */
954 sec = tv->tv_sec;
955 usec = tv->tv_usec;
956
957 if (usec < 0) {
958 sec--;
959 usec += 1000000;
960 }
961
962 if (sec < 0 || (sec == 0 && usec <= 0)) {
963 /*
964 * Would expire now or in the past. Return 0 ticks.
965 * This is different from the legacy hzto() interface,
966 * and callers need to check for it.
967 */
968 ticks = 0;
969 } else if (sec <= (LONG_MAX / 1000000))
970 ticks = (((sec * 1000000) + (unsigned long)usec + (tick - 1))
971 / tick) + 1;
972 else if (sec <= (LONG_MAX / hz))
973 ticks = (sec * hz) +
974 (((unsigned long)usec + (tick - 1)) / tick) + 1;
975 else
976 ticks = LONG_MAX;
977
978 if (ticks > INT_MAX)
979 ticks = INT_MAX;
980
981 return ((int)ticks);
982 }
983
984 #ifndef __HAVE_TIMECOUNTER
985 /*
986 * Compute number of hz until specified time. Used to compute second
987 * argument to callout_reset() from an absolute time.
988 */
989 int
990 hzto(struct timeval *tv)
991 {
992 unsigned long ticks;
993 long sec, usec;
994 int s;
995
996 /*
997 * If the number of usecs in the whole seconds part of the time
998 * difference fits in a long, then the total number of usecs will
999 * fit in an unsigned long. Compute the total and convert it to
1000 * ticks, rounding up and adding 1 to allow for the current tick
1001 * to expire. Rounding also depends on unsigned long arithmetic
1002 * to avoid overflow.
1003 *
1004 * Otherwise, if the number of ticks in the whole seconds part of
1005 * the time difference fits in a long, then convert the parts to
1006 * ticks separately and add, using similar rounding methods and
1007 * overflow avoidance. This method would work in the previous
1008 * case, but it is slightly slower and assume that hz is integral.
1009 *
1010 * Otherwise, round the time difference down to the maximum
1011 * representable value.
1012 *
1013 * If ints are 32-bit, then the maximum value for any timeout in
1014 * 10ms ticks is 248 days.
1015 */
1016 s = splclock();
1017 sec = tv->tv_sec - time.tv_sec;
1018 usec = tv->tv_usec - time.tv_usec;
1019 splx(s);
1020
1021 if (usec < 0) {
1022 sec--;
1023 usec += 1000000;
1024 }
1025
1026 if (sec < 0 || (sec == 0 && usec <= 0)) {
1027 /*
1028 * Would expire now or in the past. Return 0 ticks.
1029 * This is different from the legacy hzto() interface,
1030 * and callers need to check for it.
1031 */
1032 ticks = 0;
1033 } else if (sec <= (LONG_MAX / 1000000))
1034 ticks = (((sec * 1000000) + (unsigned long)usec + (tick - 1))
1035 / tick) + 1;
1036 else if (sec <= (LONG_MAX / hz))
1037 ticks = (sec * hz) +
1038 (((unsigned long)usec + (tick - 1)) / tick) + 1;
1039 else
1040 ticks = LONG_MAX;
1041
1042 if (ticks > INT_MAX)
1043 ticks = INT_MAX;
1044
1045 return ((int)ticks);
1046 }
1047 #endif /* !__HAVE_TIMECOUNTER */
1048
1049 /*
1050 * Compute number of ticks in the specified amount of time.
1051 */
1052 int
1053 tstohz(struct timespec *ts)
1054 {
1055 struct timeval tv;
1056
1057 /*
1058 * usec has great enough resolution for hz, so convert to a
1059 * timeval and use tvtohz() above.
1060 */
1061 TIMESPEC_TO_TIMEVAL(&tv, ts);
1062 return tvtohz(&tv);
1063 }
1064
1065 /*
1066 * Start profiling on a process.
1067 *
1068 * Kernel profiling passes proc0 which never exits and hence
1069 * keeps the profile clock running constantly.
1070 */
1071 void
1072 startprofclock(struct proc *p)
1073 {
1074
1075 if ((p->p_flag & P_PROFIL) == 0) {
1076 p->p_flag |= P_PROFIL;
1077 /*
1078 * This is only necessary if using the clock as the
1079 * profiling source.
1080 */
1081 if (++profprocs == 1 && stathz != 0)
1082 psdiv = psratio;
1083 }
1084 }
1085
1086 /*
1087 * Stop profiling on a process.
1088 */
1089 void
1090 stopprofclock(struct proc *p)
1091 {
1092
1093 if (p->p_flag & P_PROFIL) {
1094 p->p_flag &= ~P_PROFIL;
1095 /*
1096 * This is only necessary if using the clock as the
1097 * profiling source.
1098 */
1099 if (--profprocs == 0 && stathz != 0)
1100 psdiv = 1;
1101 }
1102 }
1103
1104 #if defined(PERFCTRS)
1105 /*
1106 * Independent profiling "tick" in case we're using a separate
1107 * clock or profiling event source. Currently, that's just
1108 * performance counters--hence the wrapper.
1109 */
1110 void
1111 proftick(struct clockframe *frame)
1112 {
1113 #ifdef GPROF
1114 struct gmonparam *g;
1115 intptr_t i;
1116 #endif
1117 struct proc *p;
1118
1119 p = curproc;
1120 if (CLKF_USERMODE(frame)) {
1121 if (p->p_flag & P_PROFIL)
1122 addupc_intr(p, CLKF_PC(frame));
1123 } else {
1124 #ifdef GPROF
1125 g = &_gmonparam;
1126 if (g->state == GMON_PROF_ON) {
1127 i = CLKF_PC(frame) - g->lowpc;
1128 if (i < g->textsize) {
1129 i /= HISTFRACTION * sizeof(*g->kcount);
1130 g->kcount[i]++;
1131 }
1132 }
1133 #endif
1134 #ifdef PROC_PC
1135 if (p && (p->p_flag & P_PROFIL))
1136 addupc_intr(p, PROC_PC(p));
1137 #endif
1138 }
1139 }
1140 #endif
1141
1142 /*
1143 * Statistics clock. Grab profile sample, and if divider reaches 0,
1144 * do process and kernel statistics.
1145 */
1146 void
1147 statclock(struct clockframe *frame)
1148 {
1149 #ifdef GPROF
1150 struct gmonparam *g;
1151 intptr_t i;
1152 #endif
1153 struct cpu_info *ci = curcpu();
1154 struct schedstate_percpu *spc = &ci->ci_schedstate;
1155 struct proc *p;
1156 struct lwp *l;
1157
1158 /*
1159 * Notice changes in divisor frequency, and adjust clock
1160 * frequency accordingly.
1161 */
1162 if (spc->spc_psdiv != psdiv) {
1163 spc->spc_psdiv = psdiv;
1164 spc->spc_pscnt = psdiv;
1165 if (psdiv == 1) {
1166 setstatclockrate(stathz);
1167 } else {
1168 setstatclockrate(profhz);
1169 }
1170 }
1171 l = curlwp;
1172 p = (l ? l->l_proc : NULL);
1173 if (CLKF_USERMODE(frame)) {
1174 KASSERT(p != NULL);
1175
1176 if ((p->p_flag & P_PROFIL) && profsrc == PROFSRC_CLOCK)
1177 addupc_intr(p, CLKF_PC(frame));
1178 if (--spc->spc_pscnt > 0)
1179 return;
1180 /*
1181 * Came from user mode; CPU was in user state.
1182 * If this process is being profiled record the tick.
1183 */
1184 p->p_uticks++;
1185 if (p->p_nice > NZERO)
1186 spc->spc_cp_time[CP_NICE]++;
1187 else
1188 spc->spc_cp_time[CP_USER]++;
1189 } else {
1190 #ifdef GPROF
1191 /*
1192 * Kernel statistics are just like addupc_intr, only easier.
1193 */
1194 g = &_gmonparam;
1195 if (profsrc == PROFSRC_CLOCK && g->state == GMON_PROF_ON) {
1196 i = CLKF_PC(frame) - g->lowpc;
1197 if (i < g->textsize) {
1198 i /= HISTFRACTION * sizeof(*g->kcount);
1199 g->kcount[i]++;
1200 }
1201 }
1202 #endif
1203 #ifdef LWP_PC
1204 if (p && profsrc == PROFSRC_CLOCK && (p->p_flag & P_PROFIL))
1205 addupc_intr(p, LWP_PC(l));
1206 #endif
1207 if (--spc->spc_pscnt > 0)
1208 return;
1209 /*
1210 * Came from kernel mode, so we were:
1211 * - handling an interrupt,
1212 * - doing syscall or trap work on behalf of the current
1213 * user process, or
1214 * - spinning in the idle loop.
1215 * Whichever it is, charge the time as appropriate.
1216 * Note that we charge interrupts to the current process,
1217 * regardless of whether they are ``for'' that process,
1218 * so that we know how much of its real time was spent
1219 * in ``non-process'' (i.e., interrupt) work.
1220 */
1221 if (CLKF_INTR(frame)) {
1222 if (p != NULL)
1223 p->p_iticks++;
1224 spc->spc_cp_time[CP_INTR]++;
1225 } else if (p != NULL) {
1226 p->p_sticks++;
1227 spc->spc_cp_time[CP_SYS]++;
1228 } else
1229 spc->spc_cp_time[CP_IDLE]++;
1230 }
1231 spc->spc_pscnt = psdiv;
1232
1233 if (p != NULL) {
1234 ++p->p_cpticks;
1235 /*
1236 * If no separate schedclock is provided, call it here
1237 * at about 16 Hz.
1238 */
1239 if (schedhz == 0)
1240 if ((int)(--ci->ci_schedstate.spc_schedticks) <= 0) {
1241 schedclock(l);
1242 ci->ci_schedstate.spc_schedticks = statscheddiv;
1243 }
1244 }
1245 }
1246
1247 #ifndef __HAVE_TIMECOUNTER
1248 #ifdef NTP /* NTP phase-locked loop in kernel */
1249 /*
1250 * hardupdate() - local clock update
1251 *
1252 * This routine is called by ntp_adjtime() to update the local clock
1253 * phase and frequency. The implementation is of an adaptive-parameter,
1254 * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new
1255 * time and frequency offset estimates for each call. If the kernel PPS
1256 * discipline code is configured (PPS_SYNC), the PPS signal itself
1257 * determines the new time offset, instead of the calling argument.
1258 * Presumably, calls to ntp_adjtime() occur only when the caller
1259 * believes the local clock is valid within some bound (+-128 ms with
1260 * NTP). If the caller's time is far different than the PPS time, an
1261 * argument will ensue, and it's not clear who will lose.
1262 *
1263 * For uncompensated quartz crystal oscillatores and nominal update
1264 * intervals less than 1024 s, operation should be in phase-lock mode
1265 * (STA_FLL = 0), where the loop is disciplined to phase. For update
1266 * intervals greater than thiss, operation should be in frequency-lock
1267 * mode (STA_FLL = 1), where the loop is disciplined to frequency.
1268 *
1269 * Note: splclock() is in effect.
1270 */
1271 void
1272 hardupdate(long offset)
1273 {
1274 long ltemp, mtemp;
1275
1276 if (!(time_status & STA_PLL) && !(time_status & STA_PPSTIME))
1277 return;
1278 ltemp = offset;
1279 #ifdef PPS_SYNC
1280 if (time_status & STA_PPSTIME && time_status & STA_PPSSIGNAL)
1281 ltemp = pps_offset;
1282 #endif /* PPS_SYNC */
1283
1284 /*
1285 * Scale the phase adjustment and clamp to the operating range.
1286 */
1287 if (ltemp > MAXPHASE)
1288 time_offset = MAXPHASE << SHIFT_UPDATE;
1289 else if (ltemp < -MAXPHASE)
1290 time_offset = -(MAXPHASE << SHIFT_UPDATE);
1291 else
1292 time_offset = ltemp << SHIFT_UPDATE;
1293
1294 /*
1295 * Select whether the frequency is to be controlled and in which
1296 * mode (PLL or FLL). Clamp to the operating range. Ugly
1297 * multiply/divide should be replaced someday.
1298 */
1299 if (time_status & STA_FREQHOLD || time_reftime == 0)
1300 time_reftime = time.tv_sec;
1301 mtemp = time.tv_sec - time_reftime;
1302 time_reftime = time.tv_sec;
1303 if (time_status & STA_FLL) {
1304 if (mtemp >= MINSEC) {
1305 ltemp = ((time_offset / mtemp) << (SHIFT_USEC -
1306 SHIFT_UPDATE));
1307 if (ltemp < 0)
1308 time_freq -= -ltemp >> SHIFT_KH;
1309 else
1310 time_freq += ltemp >> SHIFT_KH;
1311 }
1312 } else {
1313 if (mtemp < MAXSEC) {
1314 ltemp *= mtemp;
1315 if (ltemp < 0)
1316 time_freq -= -ltemp >> (time_constant +
1317 time_constant + SHIFT_KF -
1318 SHIFT_USEC);
1319 else
1320 time_freq += ltemp >> (time_constant +
1321 time_constant + SHIFT_KF -
1322 SHIFT_USEC);
1323 }
1324 }
1325 if (time_freq > time_tolerance)
1326 time_freq = time_tolerance;
1327 else if (time_freq < -time_tolerance)
1328 time_freq = -time_tolerance;
1329 }
1330
1331 #ifdef PPS_SYNC
1332 /*
1333 * hardpps() - discipline CPU clock oscillator to external PPS signal
1334 *
1335 * This routine is called at each PPS interrupt in order to discipline
1336 * the CPU clock oscillator to the PPS signal. It measures the PPS phase
1337 * and leaves it in a handy spot for the hardclock() routine. It
1338 * integrates successive PPS phase differences and calculates the
1339 * frequency offset. This is used in hardclock() to discipline the CPU
1340 * clock oscillator so that intrinsic frequency error is cancelled out.
1341 * The code requires the caller to capture the time and hardware counter
1342 * value at the on-time PPS signal transition.
1343 *
1344 * Note that, on some Unix systems, this routine runs at an interrupt
1345 * priority level higher than the timer interrupt routine hardclock().
1346 * Therefore, the variables used are distinct from the hardclock()
1347 * variables, except for certain exceptions: The PPS frequency pps_freq
1348 * and phase pps_offset variables are determined by this routine and
1349 * updated atomically. The time_tolerance variable can be considered a
1350 * constant, since it is infrequently changed, and then only when the
1351 * PPS signal is disabled. The watchdog counter pps_valid is updated
1352 * once per second by hardclock() and is atomically cleared in this
1353 * routine.
1354 */
1355 void
1356 hardpps(struct timeval *tvp, /* time at PPS */
1357 long usec /* hardware counter at PPS */)
1358 {
1359 long u_usec, v_usec, bigtick;
1360 long cal_sec, cal_usec;
1361
1362 /*
1363 * An occasional glitch can be produced when the PPS interrupt
1364 * occurs in the hardclock() routine before the time variable is
1365 * updated. Here the offset is discarded when the difference
1366 * between it and the last one is greater than tick/2, but not
1367 * if the interval since the first discard exceeds 30 s.
1368 */
1369 time_status |= STA_PPSSIGNAL;
1370 time_status &= ~(STA_PPSJITTER | STA_PPSWANDER | STA_PPSERROR);
1371 pps_valid = 0;
1372 u_usec = -tvp->tv_usec;
1373 if (u_usec < -500000)
1374 u_usec += 1000000;
1375 v_usec = pps_offset - u_usec;
1376 if (v_usec < 0)
1377 v_usec = -v_usec;
1378 if (v_usec > (tick >> 1)) {
1379 if (pps_glitch > MAXGLITCH) {
1380 pps_glitch = 0;
1381 pps_tf[2] = u_usec;
1382 pps_tf[1] = u_usec;
1383 } else {
1384 pps_glitch++;
1385 u_usec = pps_offset;
1386 }
1387 } else
1388 pps_glitch = 0;
1389
1390 /*
1391 * A three-stage median filter is used to help deglitch the pps
1392 * time. The median sample becomes the time offset estimate; the
1393 * difference between the other two samples becomes the time
1394 * dispersion (jitter) estimate.
1395 */
1396 pps_tf[2] = pps_tf[1];
1397 pps_tf[1] = pps_tf[0];
1398 pps_tf[0] = u_usec;
1399 if (pps_tf[0] > pps_tf[1]) {
1400 if (pps_tf[1] > pps_tf[2]) {
1401 pps_offset = pps_tf[1]; /* 0 1 2 */
1402 v_usec = pps_tf[0] - pps_tf[2];
1403 } else if (pps_tf[2] > pps_tf[0]) {
1404 pps_offset = pps_tf[0]; /* 2 0 1 */
1405 v_usec = pps_tf[2] - pps_tf[1];
1406 } else {
1407 pps_offset = pps_tf[2]; /* 0 2 1 */
1408 v_usec = pps_tf[0] - pps_tf[1];
1409 }
1410 } else {
1411 if (pps_tf[1] < pps_tf[2]) {
1412 pps_offset = pps_tf[1]; /* 2 1 0 */
1413 v_usec = pps_tf[2] - pps_tf[0];
1414 } else if (pps_tf[2] < pps_tf[0]) {
1415 pps_offset = pps_tf[0]; /* 1 0 2 */
1416 v_usec = pps_tf[1] - pps_tf[2];
1417 } else {
1418 pps_offset = pps_tf[2]; /* 1 2 0 */
1419 v_usec = pps_tf[1] - pps_tf[0];
1420 }
1421 }
1422 if (v_usec > MAXTIME)
1423 pps_jitcnt++;
1424 v_usec = (v_usec << PPS_AVG) - pps_jitter;
1425 if (v_usec < 0)
1426 pps_jitter -= -v_usec >> PPS_AVG;
1427 else
1428 pps_jitter += v_usec >> PPS_AVG;
1429 if (pps_jitter > (MAXTIME >> 1))
1430 time_status |= STA_PPSJITTER;
1431
1432 /*
1433 * During the calibration interval adjust the starting time when
1434 * the tick overflows. At the end of the interval compute the
1435 * duration of the interval and the difference of the hardware
1436 * counters at the beginning and end of the interval. This code
1437 * is deliciously complicated by the fact valid differences may
1438 * exceed the value of tick when using long calibration
1439 * intervals and small ticks. Note that the counter can be
1440 * greater than tick if caught at just the wrong instant, but
1441 * the values returned and used here are correct.
1442 */
1443 bigtick = (long)tick << SHIFT_USEC;
1444 pps_usec -= pps_freq;
1445 if (pps_usec >= bigtick)
1446 pps_usec -= bigtick;
1447 if (pps_usec < 0)
1448 pps_usec += bigtick;
1449 pps_time.tv_sec++;
1450 pps_count++;
1451 if (pps_count < (1 << pps_shift))
1452 return;
1453 pps_count = 0;
1454 pps_calcnt++;
1455 u_usec = usec << SHIFT_USEC;
1456 v_usec = pps_usec - u_usec;
1457 if (v_usec >= bigtick >> 1)
1458 v_usec -= bigtick;
1459 if (v_usec < -(bigtick >> 1))
1460 v_usec += bigtick;
1461 if (v_usec < 0)
1462 v_usec = -(-v_usec >> pps_shift);
1463 else
1464 v_usec = v_usec >> pps_shift;
1465 pps_usec = u_usec;
1466 cal_sec = tvp->tv_sec;
1467 cal_usec = tvp->tv_usec;
1468 cal_sec -= pps_time.tv_sec;
1469 cal_usec -= pps_time.tv_usec;
1470 if (cal_usec < 0) {
1471 cal_usec += 1000000;
1472 cal_sec--;
1473 }
1474 pps_time = *tvp;
1475
1476 /*
1477 * Check for lost interrupts, noise, excessive jitter and
1478 * excessive frequency error. The number of timer ticks during
1479 * the interval may vary +-1 tick. Add to this a margin of one
1480 * tick for the PPS signal jitter and maximum frequency
1481 * deviation. If the limits are exceeded, the calibration
1482 * interval is reset to the minimum and we start over.
1483 */
1484 u_usec = (long)tick << 1;
1485 if (!((cal_sec == -1 && cal_usec > (1000000 - u_usec))
1486 || (cal_sec == 0 && cal_usec < u_usec))
1487 || v_usec > time_tolerance || v_usec < -time_tolerance) {
1488 pps_errcnt++;
1489 pps_shift = PPS_SHIFT;
1490 pps_intcnt = 0;
1491 time_status |= STA_PPSERROR;
1492 return;
1493 }
1494
1495 /*
1496 * A three-stage median filter is used to help deglitch the pps
1497 * frequency. The median sample becomes the frequency offset
1498 * estimate; the difference between the other two samples
1499 * becomes the frequency dispersion (stability) estimate.
1500 */
1501 pps_ff[2] = pps_ff[1];
1502 pps_ff[1] = pps_ff[0];
1503 pps_ff[0] = v_usec;
1504 if (pps_ff[0] > pps_ff[1]) {
1505 if (pps_ff[1] > pps_ff[2]) {
1506 u_usec = pps_ff[1]; /* 0 1 2 */
1507 v_usec = pps_ff[0] - pps_ff[2];
1508 } else if (pps_ff[2] > pps_ff[0]) {
1509 u_usec = pps_ff[0]; /* 2 0 1 */
1510 v_usec = pps_ff[2] - pps_ff[1];
1511 } else {
1512 u_usec = pps_ff[2]; /* 0 2 1 */
1513 v_usec = pps_ff[0] - pps_ff[1];
1514 }
1515 } else {
1516 if (pps_ff[1] < pps_ff[2]) {
1517 u_usec = pps_ff[1]; /* 2 1 0 */
1518 v_usec = pps_ff[2] - pps_ff[0];
1519 } else if (pps_ff[2] < pps_ff[0]) {
1520 u_usec = pps_ff[0]; /* 1 0 2 */
1521 v_usec = pps_ff[1] - pps_ff[2];
1522 } else {
1523 u_usec = pps_ff[2]; /* 1 2 0 */
1524 v_usec = pps_ff[1] - pps_ff[0];
1525 }
1526 }
1527
1528 /*
1529 * Here the frequency dispersion (stability) is updated. If it
1530 * is less than one-fourth the maximum (MAXFREQ), the frequency
1531 * offset is updated as well, but clamped to the tolerance. It
1532 * will be processed later by the hardclock() routine.
1533 */
1534 v_usec = (v_usec >> 1) - pps_stabil;
1535 if (v_usec < 0)
1536 pps_stabil -= -v_usec >> PPS_AVG;
1537 else
1538 pps_stabil += v_usec >> PPS_AVG;
1539 if (pps_stabil > MAXFREQ >> 2) {
1540 pps_stbcnt++;
1541 time_status |= STA_PPSWANDER;
1542 return;
1543 }
1544 if (time_status & STA_PPSFREQ) {
1545 if (u_usec < 0) {
1546 pps_freq -= -u_usec >> PPS_AVG;
1547 if (pps_freq < -time_tolerance)
1548 pps_freq = -time_tolerance;
1549 u_usec = -u_usec;
1550 } else {
1551 pps_freq += u_usec >> PPS_AVG;
1552 if (pps_freq > time_tolerance)
1553 pps_freq = time_tolerance;
1554 }
1555 }
1556
1557 /*
1558 * Here the calibration interval is adjusted. If the maximum
1559 * time difference is greater than tick / 4, reduce the interval
1560 * by half. If this is not the case for four consecutive
1561 * intervals, double the interval.
1562 */
1563 if (u_usec << pps_shift > bigtick >> 2) {
1564 pps_intcnt = 0;
1565 if (pps_shift > PPS_SHIFT)
1566 pps_shift--;
1567 } else if (pps_intcnt >= 4) {
1568 pps_intcnt = 0;
1569 if (pps_shift < PPS_SHIFTMAX)
1570 pps_shift++;
1571 } else
1572 pps_intcnt++;
1573 }
1574 #endif /* PPS_SYNC */
1575 #endif /* NTP */
1576
1577 /* timecounter compat functions */
1578 void
1579 nanotime(struct timespec *ts)
1580 {
1581 struct timeval tv;
1582
1583 microtime(&tv);
1584 TIMEVAL_TO_TIMESPEC(&tv, ts);
1585 }
1586
1587 void
1588 getbinuptime(struct bintime *bt)
1589 {
1590 struct timeval tv;
1591
1592 microtime(&tv);
1593 timeval2bintime(&tv, bt);
1594 }
1595
1596 void
1597 nanouptime(struct timespec *tsp)
1598 {
1599 int s;
1600
1601 s = splclock();
1602 TIMEVAL_TO_TIMESPEC(&mono_time, tsp);
1603 splx(s);
1604 }
1605
1606 void
1607 getnanouptime(struct timespec *tsp)
1608 {
1609 int s;
1610
1611 s = splclock();
1612 TIMEVAL_TO_TIMESPEC(&mono_time, tsp);
1613 splx(s);
1614 }
1615
1616 void
1617 getmicrouptime(struct timeval *tvp)
1618 {
1619 int s;
1620
1621 s = splclock();
1622 *tvp = mono_time;
1623 splx(s);
1624 }
1625
1626 void
1627 getnanotime(struct timespec *tsp)
1628 {
1629 int s;
1630
1631 s = splclock();
1632 TIMEVAL_TO_TIMESPEC(&time, tsp);
1633 splx(s);
1634 }
1635
1636 void
1637 getmicrotime(struct timeval *tvp)
1638 {
1639 int s;
1640
1641 s = splclock();
1642 *tvp = time;
1643 splx(s);
1644 }
1645 #endif /* !__HAVE_TIMECOUNTER */
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