1 /*-
2 * Copyright (c) 1982, 1986, 1991, 1993
3 * The Regents of the University of California. All rights reserved.
4 * (c) UNIX System Laboratories, Inc.
5 * All or some portions of this file are derived from material licensed
6 * to the University of California by American Telephone and Telegraph
7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
8 * the permission of UNIX System Laboratories, Inc.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. All advertising materials mentioning features or use of this software
19 * must display the following acknowledgement:
20 * This product includes software developed by the University of
21 * California, Berkeley and its contributors.
22 * 4. Neither the name of the University nor the names of its contributors
23 * may be used to endorse or promote products derived from this software
24 * without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 *
38 * From: @(#)kern_clock.c 8.5 (Berkeley) 1/21/94
39 */
40
41 #include <sys/cdefs.h>
42 __FBSDID("$FreeBSD: releng/5.2/sys/kern/kern_timeout.c 122761 2003-11-15 18:33:54Z phk $");
43
44 #include <sys/param.h>
45 #include <sys/systm.h>
46 #include <sys/callout.h>
47 #include <sys/kernel.h>
48 #include <sys/lock.h>
49 #include <sys/mutex.h>
50 #include <sys/sysctl.h>
51
52 static int avg_depth;
53 SYSCTL_INT(_debug, OID_AUTO, to_avg_depth, CTLFLAG_RD, &avg_depth, 0,
54 "Average number of items examined per softclock call. Units = 1/1000");
55 static int avg_gcalls;
56 SYSCTL_INT(_debug, OID_AUTO, to_avg_gcalls, CTLFLAG_RD, &avg_gcalls, 0,
57 "Average number of Giant callouts made per softclock call. Units = 1/1000");
58 static int avg_mpcalls;
59 SYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls, CTLFLAG_RD, &avg_mpcalls, 0,
60 "Average number of MP callouts made per softclock call. Units = 1/1000");
61 /*
62 * TODO:
63 * allocate more timeout table slots when table overflows.
64 */
65
66 /* Exported to machdep.c and/or kern_clock.c. */
67 struct callout *callout;
68 struct callout_list callfree;
69 int callwheelsize, callwheelbits, callwheelmask;
70 struct callout_tailq *callwheel;
71 int softticks; /* Like ticks, but for softclock(). */
72 struct mtx callout_lock;
73 #ifdef DIAGNOSTIC
74 struct mtx dont_sleep_in_callout;
75 #endif
76
77 static struct callout *nextsoftcheck; /* Next callout to be checked. */
78
79 /*
80 * kern_timeout_callwheel_alloc() - kernel low level callwheel initialization
81 *
82 * This code is called very early in the kernel initialization sequence,
83 * and may be called more then once.
84 */
85 caddr_t
86 kern_timeout_callwheel_alloc(caddr_t v)
87 {
88 /*
89 * Calculate callout wheel size
90 */
91 for (callwheelsize = 1, callwheelbits = 0;
92 callwheelsize < ncallout;
93 callwheelsize <<= 1, ++callwheelbits)
94 ;
95 callwheelmask = callwheelsize - 1;
96
97 callout = (struct callout *)v;
98 v = (caddr_t)(callout + ncallout);
99 callwheel = (struct callout_tailq *)v;
100 v = (caddr_t)(callwheel + callwheelsize);
101 return(v);
102 }
103
104 /*
105 * kern_timeout_callwheel_init() - initialize previously reserved callwheel
106 * space.
107 *
108 * This code is called just once, after the space reserved for the
109 * callout wheel has been finalized.
110 */
111 void
112 kern_timeout_callwheel_init(void)
113 {
114 int i;
115
116 SLIST_INIT(&callfree);
117 for (i = 0; i < ncallout; i++) {
118 callout_init(&callout[i], 0);
119 callout[i].c_flags = CALLOUT_LOCAL_ALLOC;
120 SLIST_INSERT_HEAD(&callfree, &callout[i], c_links.sle);
121 }
122 for (i = 0; i < callwheelsize; i++) {
123 TAILQ_INIT(&callwheel[i]);
124 }
125 mtx_init(&callout_lock, "callout", NULL, MTX_SPIN | MTX_RECURSE);
126 #ifdef DIAGNOSTIC
127 mtx_init(&dont_sleep_in_callout, "dont_sleep_in_callout", NULL, MTX_DEF);
128 #endif
129 }
130
131 /*
132 * The callout mechanism is based on the work of Adam M. Costello and
133 * George Varghese, published in a technical report entitled "Redesigning
134 * the BSD Callout and Timer Facilities" and modified slightly for inclusion
135 * in FreeBSD by Justin T. Gibbs. The original work on the data structures
136 * used in this implementation was published by G.Varghese and A. Lauck in
137 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for
138 * the Efficient Implementation of a Timer Facility" in the Proceedings of
139 * the 11th ACM Annual Symposium on Operating Systems Principles,
140 * Austin, Texas Nov 1987.
141 */
142
143 /*
144 * Software (low priority) clock interrupt.
145 * Run periodic events from timeout queue.
146 */
147 void
148 softclock(void *dummy)
149 {
150 struct callout *c;
151 struct callout_tailq *bucket;
152 int curticks;
153 int steps; /* #steps since we last allowed interrupts */
154 int depth;
155 int mpcalls;
156 int gcalls;
157 #ifdef DIAGNOSTIC
158 struct bintime bt1, bt2;
159 struct timespec ts2;
160 static uint64_t maxdt = 36893488147419102LL; /* 2 msec */
161 #endif
162
163 #ifndef MAX_SOFTCLOCK_STEPS
164 #define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */
165 #endif /* MAX_SOFTCLOCK_STEPS */
166
167 mpcalls = 0;
168 gcalls = 0;
169 depth = 0;
170 steps = 0;
171 mtx_lock_spin(&callout_lock);
172 while (softticks != ticks) {
173 softticks++;
174 /*
175 * softticks may be modified by hard clock, so cache
176 * it while we work on a given bucket.
177 */
178 curticks = softticks;
179 bucket = &callwheel[curticks & callwheelmask];
180 c = TAILQ_FIRST(bucket);
181 while (c) {
182 depth++;
183 if (c->c_time != curticks) {
184 c = TAILQ_NEXT(c, c_links.tqe);
185 ++steps;
186 if (steps >= MAX_SOFTCLOCK_STEPS) {
187 nextsoftcheck = c;
188 /* Give interrupts a chance. */
189 mtx_unlock_spin(&callout_lock);
190 ; /* nothing */
191 mtx_lock_spin(&callout_lock);
192 c = nextsoftcheck;
193 steps = 0;
194 }
195 } else {
196 void (*c_func)(void *);
197 void *c_arg;
198 int c_flags;
199
200 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe);
201 TAILQ_REMOVE(bucket, c, c_links.tqe);
202 c_func = c->c_func;
203 c_arg = c->c_arg;
204 c_flags = c->c_flags;
205 c->c_func = NULL;
206 if (c->c_flags & CALLOUT_LOCAL_ALLOC) {
207 c->c_flags = CALLOUT_LOCAL_ALLOC;
208 SLIST_INSERT_HEAD(&callfree, c,
209 c_links.sle);
210 } else {
211 c->c_flags =
212 (c->c_flags & ~CALLOUT_PENDING);
213 }
214 mtx_unlock_spin(&callout_lock);
215 if (!(c_flags & CALLOUT_MPSAFE)) {
216 mtx_lock(&Giant);
217 gcalls++;
218 } else {
219 mpcalls++;
220 }
221 #ifdef DIAGNOSTIC
222 binuptime(&bt1);
223 mtx_lock(&dont_sleep_in_callout);
224 #endif
225 c_func(c_arg);
226 #ifdef DIAGNOSTIC
227 mtx_unlock(&dont_sleep_in_callout);
228 binuptime(&bt2);
229 bintime_sub(&bt2, &bt1);
230 if (bt2.frac > maxdt) {
231 maxdt = bt2.frac;
232 bintime2timespec(&bt2, &ts2);
233 printf(
234 "Expensive timeout(9) function: %p(%p) %ld.%09ld s\n",
235 c_func, c_arg,
236 (long)ts2.tv_sec, ts2.tv_nsec);
237 }
238 #endif
239 if (!(c_flags & CALLOUT_MPSAFE))
240 mtx_unlock(&Giant);
241 mtx_lock_spin(&callout_lock);
242 steps = 0;
243 c = nextsoftcheck;
244 }
245 }
246 }
247 avg_depth += (depth * 1000 - avg_depth) >> 8;
248 avg_mpcalls += (mpcalls * 1000 - avg_mpcalls) >> 8;
249 avg_gcalls += (gcalls * 1000 - avg_gcalls) >> 8;
250 nextsoftcheck = NULL;
251 mtx_unlock_spin(&callout_lock);
252 }
253
254 /*
255 * timeout --
256 * Execute a function after a specified length of time.
257 *
258 * untimeout --
259 * Cancel previous timeout function call.
260 *
261 * callout_handle_init --
262 * Initialize a handle so that using it with untimeout is benign.
263 *
264 * See AT&T BCI Driver Reference Manual for specification. This
265 * implementation differs from that one in that although an
266 * identification value is returned from timeout, the original
267 * arguments to timeout as well as the identifier are used to
268 * identify entries for untimeout.
269 */
270 struct callout_handle
271 timeout(ftn, arg, to_ticks)
272 timeout_t *ftn;
273 void *arg;
274 int to_ticks;
275 {
276 struct callout *new;
277 struct callout_handle handle;
278
279 mtx_lock_spin(&callout_lock);
280
281 /* Fill in the next free callout structure. */
282 new = SLIST_FIRST(&callfree);
283 if (new == NULL)
284 /* XXX Attempt to malloc first */
285 panic("timeout table full");
286 SLIST_REMOVE_HEAD(&callfree, c_links.sle);
287
288 callout_reset(new, to_ticks, ftn, arg);
289
290 handle.callout = new;
291 mtx_unlock_spin(&callout_lock);
292 return (handle);
293 }
294
295 void
296 untimeout(ftn, arg, handle)
297 timeout_t *ftn;
298 void *arg;
299 struct callout_handle handle;
300 {
301
302 /*
303 * Check for a handle that was initialized
304 * by callout_handle_init, but never used
305 * for a real timeout.
306 */
307 if (handle.callout == NULL)
308 return;
309
310 mtx_lock_spin(&callout_lock);
311 if (handle.callout->c_func == ftn && handle.callout->c_arg == arg)
312 callout_stop(handle.callout);
313 mtx_unlock_spin(&callout_lock);
314 }
315
316 void
317 callout_handle_init(struct callout_handle *handle)
318 {
319 handle->callout = NULL;
320 }
321
322 /*
323 * New interface; clients allocate their own callout structures.
324 *
325 * callout_reset() - establish or change a timeout
326 * callout_stop() - disestablish a timeout
327 * callout_init() - initialize a callout structure so that it can
328 * safely be passed to callout_reset() and callout_stop()
329 *
330 * <sys/callout.h> defines three convenience macros:
331 *
332 * callout_active() - returns truth if callout has not been serviced
333 * callout_pending() - returns truth if callout is still waiting for timeout
334 * callout_deactivate() - marks the callout as having been serviced
335 */
336 void
337 callout_reset(c, to_ticks, ftn, arg)
338 struct callout *c;
339 int to_ticks;
340 void (*ftn)(void *);
341 void *arg;
342 {
343
344 mtx_lock_spin(&callout_lock);
345 if (c->c_flags & CALLOUT_PENDING)
346 callout_stop(c);
347
348 /*
349 * We could unlock callout_lock here and lock it again before the
350 * TAILQ_INSERT_TAIL, but there's no point since doing this setup
351 * doesn't take much time.
352 */
353 if (to_ticks <= 0)
354 to_ticks = 1;
355
356 c->c_arg = arg;
357 c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING);
358 c->c_func = ftn;
359 c->c_time = ticks + to_ticks;
360 TAILQ_INSERT_TAIL(&callwheel[c->c_time & callwheelmask],
361 c, c_links.tqe);
362 mtx_unlock_spin(&callout_lock);
363 }
364
365 int
366 callout_stop(c)
367 struct callout *c;
368 {
369
370 mtx_lock_spin(&callout_lock);
371 /*
372 * Don't attempt to delete a callout that's not on the queue.
373 */
374 if (!(c->c_flags & CALLOUT_PENDING)) {
375 c->c_flags &= ~CALLOUT_ACTIVE;
376 mtx_unlock_spin(&callout_lock);
377 return (0);
378 }
379 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING);
380
381 if (nextsoftcheck == c) {
382 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe);
383 }
384 TAILQ_REMOVE(&callwheel[c->c_time & callwheelmask], c, c_links.tqe);
385 c->c_func = NULL;
386
387 if (c->c_flags & CALLOUT_LOCAL_ALLOC) {
388 SLIST_INSERT_HEAD(&callfree, c, c_links.sle);
389 }
390 mtx_unlock_spin(&callout_lock);
391 return (1);
392 }
393
394 void
395 callout_init(c, mpsafe)
396 struct callout *c;
397 int mpsafe;
398 {
399 bzero(c, sizeof *c);
400 if (mpsafe)
401 c->c_flags |= CALLOUT_MPSAFE;
402 }
403
404 #ifdef APM_FIXUP_CALLTODO
405 /*
406 * Adjust the kernel calltodo timeout list. This routine is used after
407 * an APM resume to recalculate the calltodo timer list values with the
408 * number of hz's we have been sleeping. The next hardclock() will detect
409 * that there are fired timers and run softclock() to execute them.
410 *
411 * Please note, I have not done an exhaustive analysis of what code this
412 * might break. I am motivated to have my select()'s and alarm()'s that
413 * have expired during suspend firing upon resume so that the applications
414 * which set the timer can do the maintanence the timer was for as close
415 * as possible to the originally intended time. Testing this code for a
416 * week showed that resuming from a suspend resulted in 22 to 25 timers
417 * firing, which seemed independant on whether the suspend was 2 hours or
418 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu>
419 */
420 void
421 adjust_timeout_calltodo(time_change)
422 struct timeval *time_change;
423 {
424 register struct callout *p;
425 unsigned long delta_ticks;
426
427 /*
428 * How many ticks were we asleep?
429 * (stolen from tvtohz()).
430 */
431
432 /* Don't do anything */
433 if (time_change->tv_sec < 0)
434 return;
435 else if (time_change->tv_sec <= LONG_MAX / 1000000)
436 delta_ticks = (time_change->tv_sec * 1000000 +
437 time_change->tv_usec + (tick - 1)) / tick + 1;
438 else if (time_change->tv_sec <= LONG_MAX / hz)
439 delta_ticks = time_change->tv_sec * hz +
440 (time_change->tv_usec + (tick - 1)) / tick + 1;
441 else
442 delta_ticks = LONG_MAX;
443
444 if (delta_ticks > INT_MAX)
445 delta_ticks = INT_MAX;
446
447 /*
448 * Now rip through the timer calltodo list looking for timers
449 * to expire.
450 */
451
452 /* don't collide with softclock() */
453 mtx_lock_spin(&callout_lock);
454 for (p = calltodo.c_next; p != NULL; p = p->c_next) {
455 p->c_time -= delta_ticks;
456
457 /* Break if the timer had more time on it than delta_ticks */
458 if (p->c_time > 0)
459 break;
460
461 /* take back the ticks the timer didn't use (p->c_time <= 0) */
462 delta_ticks = -p->c_time;
463 }
464 mtx_unlock_spin(&callout_lock);
465
466 return;
467 }
468 #endif /* APM_FIXUP_CALLTODO */
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