1 /** $MirOS: src/sys/kern/kern_clock.c,v 1.8 2010/09/19 18:55:40 tg Exp $ */
2 /* $OpenBSD: kern_clock.c,v 1.42 2003/06/02 23:28:05 millert Exp $ */
3 /* $NetBSD: kern_clock.c,v 1.34 1996/06/09 04:51:03 briggs Exp $ */
4
5 /*-
6 * Copyright (c) 1982, 1986, 1991, 1993
7 * The Regents of the University of California. All rights reserved.
8 * (c) UNIX System Laboratories, Inc.
9 * All or some portions of this file are derived from material licensed
10 * to the University of California by American Telephone and Telegraph
11 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
12 * the permission of UNIX System Laboratories, Inc.
13 *
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
16 * are met:
17 * 1. Redistributions of source code must retain the above copyright
18 * notice, this list of conditions and the following disclaimer.
19 * 2. Redistributions in binary form must reproduce the above copyright
20 * notice, this list of conditions and the following disclaimer in the
21 * documentation and/or other materials provided with the distribution.
22 * 3. Neither the name of the University nor the names of its contributors
23 * may be used to endorse or promote products derived from this software
24 * without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 *
38 * @(#)kern_clock.c 8.5 (Berkeley) 1/21/94
39 */
40
41 #include <sys/param.h>
42 #include <sys/systm.h>
43 #include <sys/dkstat.h>
44 #include <sys/timeout.h>
45 #include <sys/kernel.h>
46 #include <sys/limits.h>
47 #include <sys/proc.h>
48 #include <sys/resourcevar.h>
49 #include <sys/signalvar.h>
50 #include <uvm/uvm_extern.h>
51 #include <sys/sysctl.h>
52 #include <sys/sched.h>
53
54 #include <crypto/randimpl.h>
55 #include <machine/cpu.h>
56
57 #ifdef CPU_HARDCLOCKENT_DECL
58 CPU_HARDCLOCKENT_DECL;
59 static u_quad_t hce_value;
60 #define HARDCLOCKENT_APPLY(newvalue) do { \
61 u_quad_t hce_mask, hce_delta = hce_value; \
62 uint32_t hce_entropy = 0; \
63 \
64 hce_value = (newvalue); \
65 hce_delta = hce_value - hce_delta; \
66 for (hce_mask = 1; hce_mask; hce_mask <<= 1) \
67 if (hce_delta & hce_mask) { \
68 hce_entropy <<= 1; \
69 if (hce_value & hce_mask) \
70 hce_entropy++; \
71 } \
72 rnd_lopool_addvq(hce_entropy); \
73 } while (/* CONSTCOND */ 0)
74 #endif
75
76 /*
77 * Clock handling routines.
78 *
79 * This code is written to operate with two timers that run independently of
80 * each other. The main clock, running hz times per second, is used to keep
81 * track of real time. The second timer handles kernel and user profiling,
82 * and does resource use estimation. If the second timer is programmable,
83 * it is randomized to avoid aliasing between the two clocks. For example,
84 * the randomization prevents an adversary from always giving up the cpu
85 * just before its quantum expires. Otherwise, it would never accumulate
86 * cpu ticks. The mean frequency of the second timer is stathz.
87 *
88 * If no second timer exists, stathz will be zero; in this case we drive
89 * profiling and statistics off the main clock. This WILL NOT be accurate;
90 * do not do it unless absolutely necessary.
91 *
92 * The statistics clock may (or may not) be run at a higher rate while
93 * profiling. This profile clock runs at profhz. We require that profhz
94 * be an integral multiple of stathz.
95 *
96 * If the statistics clock is running fast, it must be divided by the ratio
97 * profhz/stathz for statistics. (For profiling, every tick counts.)
98 */
99
100 /*
101 * Bump a timeval by a small number of usec's.
102 */
103 #define BUMPTIME(t, usec) { \
104 register volatile struct timeval *tp = (t); \
105 register long us; \
106 \
107 tp->tv_usec = us = tp->tv_usec + (usec); \
108 if (us >= 1000000) { \
109 tp->tv_usec = us - 1000000; \
110 tp->tv_sec++; \
111 } \
112 }
113
114 int stathz;
115 int schedhz;
116 int profhz;
117 int profprocs;
118 int ticks;
119 static int psdiv, pscnt; /* prof => stat divider */
120 int psratio; /* ratio: prof / stat */
121 int tickfix, tickfixinterval; /* used if tick not really integral */
122 static int tickfixcnt; /* accumulated fractional error */
123
124 long cp_time[CPUSTATES];
125
126 volatile struct timeval time
127 __attribute__((__aligned__(__alignof__(quad_t))));
128 volatile struct timeval mono_time;
129
130 #ifdef __HAVE_GENERIC_SOFT_INTERRUPTS
131 void *softclock_si;
132 void generic_softclock(void *);
133
134 void
generic_softclock(void * ignore)135 generic_softclock(void *ignore)
136 {
137 /*
138 * XXX - dont' commit, just a dummy wrapper until we learn everyone
139 * deal with a changed proto for softclock().
140 */
141 softclock();
142 }
143 #endif
144
145 /*
146 * Initialize clock frequencies and start both clocks running.
147 */
148 void
initclocks()149 initclocks()
150 {
151 int i;
152
153 #ifdef __HAVE_GENERIC_SOFT_INTERRUPTS
154 softclock_si = softintr_establish(IPL_SOFTCLOCK, generic_softclock, NULL);
155 if (softclock_si == NULL)
156 panic("initclocks: unable to register softclock intr");
157 #endif
158
159 /*
160 * Set divisors to 1 (normal case) and let the machine-specific
161 * code do its bit.
162 */
163 psdiv = pscnt = 1;
164 cpu_initclocks();
165
166 /*
167 * Compute profhz/stathz, and fix profhz if needed.
168 */
169 i = stathz ? stathz : hz;
170 if (profhz == 0)
171 profhz = i;
172 psratio = profhz / i;
173 }
174
175 /*
176 * The real-time timer, interrupting hz times per second.
177 */
178 void
hardclock(frame)179 hardclock(frame)
180 register struct clockframe *frame;
181 {
182 register struct proc *p;
183 register int delta;
184 extern int tickdelta;
185 extern long timedelta;
186
187 #ifdef CPU_HARDCLOCKENT
188 CPU_HARDCLOCKENT();
189 #endif
190
191 p = curproc;
192 if (p) {
193 register struct pstats *pstats;
194
195 /*
196 * Run current process's virtual and profile time, as needed.
197 */
198 pstats = p->p_stats;
199 if (CLKF_USERMODE(frame) &&
200 timerisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value) &&
201 itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL], tick) == 0)
202 psignal(p, SIGVTALRM);
203 if (timerisset(&pstats->p_timer[ITIMER_PROF].it_value) &&
204 itimerdecr(&pstats->p_timer[ITIMER_PROF], tick) == 0)
205 psignal(p, SIGPROF);
206 }
207
208 /*
209 * If no separate statistics clock is available, run it from here.
210 */
211 if (stathz == 0)
212 statclock(frame);
213
214 /*
215 * Increment the time-of-day. The increment is normally just
216 * ``tick''. If the machine is one which has a clock frequency
217 * such that ``hz'' would not divide the second evenly into
218 * milliseconds, a periodic adjustment must be applied. Finally,
219 * if we are still adjusting the time (see adjtime()),
220 * ``tickdelta'' may also be added in.
221 */
222 ticks++;
223 delta = tick;
224
225 if (tickfix) {
226 tickfixcnt += tickfix;
227 if (tickfixcnt >= tickfixinterval) {
228 delta++;
229 tickfixcnt -= tickfixinterval;
230 }
231 }
232 /* Imprecise 4bsd adjtime() handling */
233 if (timedelta != 0) {
234 delta += tickdelta;
235 timedelta -= tickdelta;
236 }
237
238 #ifdef notyet
239 microset();
240 #endif
241
242 BUMPTIME(&time, delta);
243 BUMPTIME(&mono_time, delta);
244
245 #ifdef CPU_CLOCKUPDATE
246 CPU_CLOCKUPDATE();
247 #endif
248
249 /*
250 * Update real-time timeout queue.
251 * Process callouts at a very low cpu priority, so we don't keep the
252 * relatively high clock interrupt priority any longer than necessary.
253 */
254 if (timeout_hardclock_update()) {
255 #ifdef __HAVE_GENERIC_SOFT_INTERRUPTS
256 softintr_schedule(softclock_si);
257 #else
258 setsoftclock();
259 #endif
260 }
261 }
262
263 /*
264 * Compute number of hz until specified time. Used to
265 * compute the second argument to timeout_add() from an absolute time.
266 */
267 int
hzto(struct timeval * tv)268 hzto(struct timeval *tv)
269 {
270 unsigned long ticks;
271 time_t sec;
272 long usec;
273 int s;
274
275 /*
276 * If the number of usecs in the whole seconds part of the time
277 * difference fits in a long, then the total number of usecs will
278 * fit in an unsigned long. Compute the total and convert it to
279 * ticks, rounding up and adding 1 to allow for the current tick
280 * to expire. Rounding also depends on unsigned long arithmetic
281 * to avoid overflow.
282 *
283 * Otherwise, if the number of ticks in the whole seconds part of
284 * the time difference fits in a long, then convert the parts to
285 * ticks separately and add, using similar rounding methods and
286 * overflow avoidance. This method would work in the previous
287 * case but it is slightly slower and assumes that hz is integral.
288 *
289 * Otherwise, round the time difference down to the maximum
290 * representable value.
291 *
292 * If ints have 32 bits, then the maximum value for any timeout in
293 * 10ms ticks is 248 days.
294 */
295 s = splhigh();
296 sec = tv->tv_sec - time.tv_sec;
297 usec = tv->tv_usec - time.tv_usec;
298 splx(s);
299 if (usec < 0) {
300 sec--;
301 usec += 1000000;
302 }
303 if (sec < 0 || (sec == 0 && usec <= 0)) {
304 ticks = 0;
305 } else if (sec <= LONG_MAX / 1000000)
306 ticks = (sec * 1000000 + (unsigned long)usec + (tick - 1))
307 / tick + 1;
308 else if (sec <= LONG_MAX / hz)
309 ticks = sec * hz
310 + ((unsigned long)usec + (tick - 1)) / tick + 1;
311 else
312 ticks = LONG_MAX;
313 if (ticks > INT_MAX)
314 ticks = INT_MAX;
315 return ((int)ticks);
316 }
317
318 /*
319 * Compute number of hz in the specified amount of time.
320 */
321 int
tvtohz(struct timeval * tv)322 tvtohz(struct timeval *tv)
323 {
324 unsigned long ticks;
325 long sec, usec;
326
327 /*
328 * If the number of usecs in the whole seconds part of the time
329 * fits in a long, then the total number of usecs will
330 * fit in an unsigned long. Compute the total and convert it to
331 * ticks, rounding up and adding 1 to allow for the current tick
332 * to expire. Rounding also depends on unsigned long arithmetic
333 * to avoid overflow.
334 *
335 * Otherwise, if the number of ticks in the whole seconds part of
336 * the time fits in a long, then convert the parts to
337 * ticks separately and add, using similar rounding methods and
338 * overflow avoidance. This method would work in the previous
339 * case but it is slightly slower and assumes that hz is integral.
340 *
341 * Otherwise, round the time down to the maximum
342 * representable value.
343 *
344 * If ints have 32 bits, then the maximum value for any timeout in
345 * 10ms ticks is 248 days.
346 */
347 sec = tv->tv_sec;
348 usec = tv->tv_usec;
349 if (sec < 0 || (sec == 0 && usec <= 0))
350 ticks = 0;
351 else if (sec <= LONG_MAX / 1000000)
352 ticks = (sec * 1000000 + (unsigned long)usec + (tick - 1))
353 / tick + 1;
354 else if (sec <= LONG_MAX / hz)
355 ticks = sec * hz
356 + ((unsigned long)usec + (tick - 1)) / tick + 1;
357 else
358 ticks = LONG_MAX;
359 if (ticks > INT_MAX)
360 ticks = INT_MAX;
361 return ((int)ticks);
362 }
363
364 /*
365 * Start profiling on a process.
366 *
367 * Kernel profiling passes proc0 which never exits and hence
368 * keeps the profile clock running constantly.
369 */
370 void
startprofclock(p)371 startprofclock(p)
372 register struct proc *p;
373 {
374 int s;
375
376 if ((p->p_flag & P_PROFIL) == 0) {
377 p->p_flag |= P_PROFIL;
378 if (++profprocs == 1 && stathz != 0) {
379 s = splstatclock();
380 psdiv = pscnt = psratio;
381 setstatclockrate(profhz);
382 splx(s);
383 }
384 }
385 }
386
387 /*
388 * Stop profiling on a process.
389 */
390 void
stopprofclock(p)391 stopprofclock(p)
392 register struct proc *p;
393 {
394 int s;
395
396 if (p->p_flag & P_PROFIL) {
397 p->p_flag &= ~P_PROFIL;
398 if (--profprocs == 0 && stathz != 0) {
399 s = splstatclock();
400 psdiv = pscnt = 1;
401 setstatclockrate(stathz);
402 splx(s);
403 }
404 }
405 }
406
407 /*
408 * Statistics clock. Grab profile sample, and if divider reaches 0,
409 * do process and kernel statistics.
410 */
411 void
statclock(frame)412 statclock(frame)
413 register struct clockframe *frame;
414 {
415 static int schedclk;
416 register struct proc *p;
417
418 if (CLKF_USERMODE(frame)) {
419 p = curproc;
420 if (p->p_flag & P_PROFIL)
421 addupc_intr(p, CLKF_PC(frame));
422 if (--pscnt > 0)
423 return;
424 /*
425 * Came from user mode; CPU was in user state.
426 * If this process is being profiled record the tick.
427 */
428 p->p_uticks++;
429 if (p->p_nice > NZERO)
430 cp_time[CP_NICE]++;
431 else
432 cp_time[CP_USER]++;
433 } else {
434 if (--pscnt > 0)
435 return;
436 /*
437 * Came from kernel mode, so we were:
438 * - handling an interrupt,
439 * - doing syscall or trap work on behalf of the current
440 * user process, or
441 * - spinning in the idle loop.
442 * Whichever it is, charge the time as appropriate.
443 * Note that we charge interrupts to the current process,
444 * regardless of whether they are ``for'' that process,
445 * so that we know how much of its real time was spent
446 * in ``non-process'' (i.e., interrupt) work.
447 */
448 p = curproc;
449 if (CLKF_INTR(frame)) {
450 if (p != NULL)
451 p->p_iticks++;
452 cp_time[CP_INTR]++;
453 } else if (p != NULL) {
454 p->p_sticks++;
455 cp_time[CP_SYS]++;
456 } else
457 cp_time[CP_IDLE]++;
458 }
459 pscnt = psdiv;
460
461 if (p != NULL) {
462 p->p_cpticks++;
463 /*
464 * If no schedclock is provided, call it here at ~~12-25 Hz;
465 * ~~16 Hz is best
466 */
467 if (schedhz == 0)
468 if ((++schedclk & 3) == 0)
469 schedclock(p);
470 }
471 }
472
473 /*
474 * Return information about system clocks.
475 */
476 int
sysctl_clockrate(where,sizep)477 sysctl_clockrate(where, sizep)
478 register char *where;
479 size_t *sizep;
480 {
481 struct clockinfo clkinfo;
482
483 /*
484 * Construct clockinfo structure.
485 */
486 clkinfo.tick = tick;
487 clkinfo.tickadj = tickadj;
488 clkinfo.hz = hz;
489 clkinfo.profhz = profhz;
490 clkinfo.stathz = stathz ? stathz : hz;
491 return (sysctl_rdstruct(where, sizep, NULL, &clkinfo, sizeof(clkinfo)));
492 }
493