The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]

FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_timeout.c

Version: -  FREEBSD  -  FREEBSD-12-STABLE  -  FREEBSD-12-0  -  FREEBSD-11-STABLE  -  FREEBSD-11-2  -  FREEBSD-11-1  -  FREEBSD-11-0  -  FREEBSD-10-STABLE  -  FREEBSD-10-4  -  FREEBSD-10-3  -  FREEBSD-10-2  -  FREEBSD-10-1  -  FREEBSD-10-0  -  FREEBSD-9-STABLE  -  FREEBSD-9-3  -  FREEBSD-9-2  -  FREEBSD-9-1  -  FREEBSD-9-0  -  FREEBSD-8-STABLE  -  FREEBSD-8-4  -  FREEBSD-8-3  -  FREEBSD-8-2  -  FREEBSD-8-1  -  FREEBSD-8-0  -  FREEBSD-7-STABLE  -  FREEBSD-7-4  -  FREEBSD-7-3  -  FREEBSD-7-2  -  FREEBSD-7-1  -  FREEBSD-7-0  -  FREEBSD-6-STABLE  -  FREEBSD-6-4  -  FREEBSD-6-3  -  FREEBSD-6-2  -  FREEBSD-6-1  -  FREEBSD-6-0  -  FREEBSD-5-STABLE  -  FREEBSD-5-5  -  FREEBSD-5-4  -  FREEBSD-5-3  -  FREEBSD-5-2  -  FREEBSD-5-1  -  FREEBSD-5-0  -  FREEBSD-4-STABLE  -  FREEBSD-3-STABLE  -  FREEBSD22  -  linux-2.6  -  linux-2.4.22  -  MK83  -  MK84  -  PLAN9  -  DFBSD  -  NETBSD  -  NETBSD5  -  NETBSD4  -  NETBSD3  -  NETBSD20  -  OPENBSD  -  xnu-517  -  xnu-792  -  xnu-792.6.70  -  xnu-1228  -  xnu-1456.1.26  -  xnu-1699.24.8  -  xnu-2050.18.24  -  OPENSOLARIS  -  minix-3-1-1 
SearchContext: -  none  -  3  -  10 

    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  * $FreeBSD: stable/4/sys/kern/kern_timeout.c 86329 2001-11-13 18:24:52Z archie $
   40  */
   41 
   42 #include <sys/param.h>
   43 #include <sys/systm.h>
   44 #include <sys/callout.h>
   45 #include <sys/kernel.h>
   46 
   47 /*
   48  * TODO:
   49  *      allocate more timeout table slots when table overflows.
   50  */
   51 
   52 /* Exported to machdep.c and/or kern_clock.c.  */
   53 struct callout *callout;
   54 struct callout_list callfree;
   55 int callwheelsize, callwheelbits, callwheelmask;
   56 struct callout_tailq *callwheel;
   57 int softticks;                  /* Like ticks, but for softclock(). */
   58 
   59 static struct callout *nextsoftcheck;   /* Next callout to be checked. */
   60 
   61 /*
   62  * The callout mechanism is based on the work of Adam M. Costello and 
   63  * George Varghese, published in a technical report entitled "Redesigning
   64  * the BSD Callout and Timer Facilities" and modified slightly for inclusion
   65  * in FreeBSD by Justin T. Gibbs.  The original work on the data structures
   66  * used in this implementation was published by G.Varghese and A. Lauck in
   67  * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for
   68  * the Efficient Implementation of a Timer Facility" in the Proceedings of
   69  * the 11th ACM Annual Symposium on Operating Systems Principles,
   70  * Austin, Texas Nov 1987.
   71  */
   72 
   73 /*
   74  * Software (low priority) clock interrupt.
   75  * Run periodic events from timeout queue.
   76  */
   77 void
   78 softclock()
   79 {
   80         register struct callout *c;
   81         register struct callout_tailq *bucket;
   82         register int s;
   83         register int curticks;
   84         register int steps;     /* #steps since we last allowed interrupts */
   85 
   86 #ifndef MAX_SOFTCLOCK_STEPS
   87 #define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */
   88 #endif /* MAX_SOFTCLOCK_STEPS */
   89 
   90         steps = 0;
   91         s = splhigh();
   92         while (softticks != ticks) {
   93                 softticks++;
   94                 /*
   95                  * softticks may be modified by hard clock, so cache
   96                  * it while we work on a given bucket.
   97                  */
   98                 curticks = softticks;
   99                 bucket = &callwheel[curticks & callwheelmask];
  100                 c = TAILQ_FIRST(bucket);
  101                 while (c) {
  102                         if (c->c_time != curticks) {
  103                                 c = TAILQ_NEXT(c, c_links.tqe);
  104                                 ++steps;
  105                                 if (steps >= MAX_SOFTCLOCK_STEPS) {
  106                                         nextsoftcheck = c;
  107                                         /* Give interrupts a chance. */
  108                                         splx(s);
  109                                         s = splhigh();
  110                                         c = nextsoftcheck;
  111                                         steps = 0;
  112                                 }
  113                         } else {
  114                                 void (*c_func)(void *);
  115                                 void *c_arg;
  116 
  117                                 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe);
  118                                 TAILQ_REMOVE(bucket, c, c_links.tqe);
  119                                 c_func = c->c_func;
  120                                 c_arg = c->c_arg;
  121                                 c->c_func = NULL;
  122                                 if (c->c_flags & CALLOUT_LOCAL_ALLOC) {
  123                                         c->c_flags = CALLOUT_LOCAL_ALLOC;
  124                                         SLIST_INSERT_HEAD(&callfree, c,
  125                                                           c_links.sle);
  126                                 } else {
  127                                         c->c_flags =
  128                                             (c->c_flags & ~CALLOUT_PENDING);
  129                                 }
  130                                 splx(s);
  131                                 c_func(c_arg);
  132                                 s = splhigh();
  133                                 steps = 0;
  134                                 c = nextsoftcheck;
  135                         }
  136                 }
  137         }
  138         nextsoftcheck = NULL;
  139         splx(s);
  140 }
  141 
  142 /*
  143  * timeout --
  144  *      Execute a function after a specified length of time.
  145  *
  146  * untimeout --
  147  *      Cancel previous timeout function call.
  148  *
  149  * callout_handle_init --
  150  *      Initialize a handle so that using it with untimeout is benign.
  151  *
  152  *      See AT&T BCI Driver Reference Manual for specification.  This
  153  *      implementation differs from that one in that although an 
  154  *      identification value is returned from timeout, the original
  155  *      arguments to timeout as well as the identifier are used to
  156  *      identify entries for untimeout.
  157  */
  158 struct callout_handle
  159 timeout(ftn, arg, to_ticks)
  160         timeout_t *ftn;
  161         void *arg;
  162         register int to_ticks;
  163 {
  164         int s;
  165         struct callout *new;
  166         struct callout_handle handle;
  167 
  168         s = splhigh();
  169 
  170         /* Fill in the next free callout structure. */
  171         new = SLIST_FIRST(&callfree);
  172         if (new == NULL)
  173                 /* XXX Attempt to malloc first */
  174                 panic("timeout table full");
  175         SLIST_REMOVE_HEAD(&callfree, c_links.sle);
  176         
  177         callout_reset(new, to_ticks, ftn, arg);
  178 
  179         handle.callout = new;
  180         splx(s);
  181         return (handle);
  182 }
  183 
  184 void
  185 untimeout(ftn, arg, handle)
  186         timeout_t *ftn;
  187         void *arg;
  188         struct callout_handle handle;
  189 {
  190         register int s;
  191 
  192         /*
  193          * Check for a handle that was initialized
  194          * by callout_handle_init, but never used
  195          * for a real timeout.
  196          */
  197         if (handle.callout == NULL)
  198                 return;
  199 
  200         s = splhigh();
  201         if (handle.callout->c_func == ftn && handle.callout->c_arg == arg)
  202                 callout_stop(handle.callout);
  203         splx(s);
  204 }
  205 
  206 void
  207 callout_handle_init(struct callout_handle *handle)
  208 {
  209         handle->callout = NULL;
  210 }
  211 
  212 /*
  213  * New interface; clients allocate their own callout structures.
  214  *
  215  * callout_reset() - establish or change a timeout
  216  * callout_stop() - disestablish a timeout
  217  * callout_init() - initialize a callout structure so that it can
  218  *      safely be passed to callout_reset() and callout_stop()
  219  *
  220  * <sys/callout.h> defines three convenience macros:
  221  *
  222  * callout_active() - returns truth if callout has not been serviced
  223  * callout_pending() - returns truth if callout is still waiting for timeout
  224  * callout_deactivate() - marks the callout as having been serviced
  225  */
  226 void
  227 callout_reset(c, to_ticks, ftn, arg)
  228         struct  callout *c;
  229         int     to_ticks;
  230         void    (*ftn) __P((void *));
  231         void    *arg;
  232 {
  233         int     s;
  234 
  235         s = splhigh();
  236         if (c->c_flags & CALLOUT_PENDING)
  237                 callout_stop(c);
  238 
  239         /*
  240          * We could spl down here and back up at the TAILQ_INSERT_TAIL,
  241          * but there's no point since doing this setup doesn't take much
  242          * time.
  243          */
  244         if (to_ticks <= 0)
  245                 to_ticks = 1;
  246 
  247         c->c_arg = arg;
  248         c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING);
  249         c->c_func = ftn;
  250         c->c_time = ticks + to_ticks;
  251         TAILQ_INSERT_TAIL(&callwheel[c->c_time & callwheelmask], 
  252                           c, c_links.tqe);
  253         splx(s);
  254         
  255 }
  256 
  257 int
  258 callout_stop(c)
  259         struct  callout *c;
  260 {
  261         int     s;
  262 
  263         s = splhigh();
  264         /*
  265          * Don't attempt to delete a callout that's not on the queue.
  266          */
  267         if (!(c->c_flags & CALLOUT_PENDING)) {
  268                 c->c_flags &= ~CALLOUT_ACTIVE;
  269                 splx(s);
  270                 return (0);
  271         }
  272         c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING);
  273 
  274         if (nextsoftcheck == c) {
  275                 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe);
  276         }
  277         TAILQ_REMOVE(&callwheel[c->c_time & callwheelmask], c, c_links.tqe);
  278         c->c_func = NULL;
  279 
  280         if (c->c_flags & CALLOUT_LOCAL_ALLOC) {
  281                 SLIST_INSERT_HEAD(&callfree, c, c_links.sle);
  282         }
  283         splx(s);
  284         return (1);
  285 }
  286 
  287 void
  288 callout_init(c)
  289         struct  callout *c;
  290 {
  291         bzero(c, sizeof *c);
  292 }
  293 
  294 #ifdef APM_FIXUP_CALLTODO
  295 /* 
  296  * Adjust the kernel calltodo timeout list.  This routine is used after 
  297  * an APM resume to recalculate the calltodo timer list values with the 
  298  * number of hz's we have been sleeping.  The next hardclock() will detect 
  299  * that there are fired timers and run softclock() to execute them.
  300  *
  301  * Please note, I have not done an exhaustive analysis of what code this
  302  * might break.  I am motivated to have my select()'s and alarm()'s that
  303  * have expired during suspend firing upon resume so that the applications
  304  * which set the timer can do the maintanence the timer was for as close
  305  * as possible to the originally intended time.  Testing this code for a 
  306  * week showed that resuming from a suspend resulted in 22 to 25 timers 
  307  * firing, which seemed independant on whether the suspend was 2 hours or
  308  * 2 days.  Your milage may vary.   - Ken Key <key@cs.utk.edu>
  309  */
  310 void
  311 adjust_timeout_calltodo(time_change)
  312     struct timeval *time_change;
  313 {
  314         register struct callout *p;
  315         unsigned long delta_ticks;
  316         int s;
  317 
  318         /* 
  319          * How many ticks were we asleep?
  320          * (stolen from tvtohz()).
  321          */
  322 
  323         /* Don't do anything */
  324         if (time_change->tv_sec < 0)
  325                 return;
  326         else if (time_change->tv_sec <= LONG_MAX / 1000000)
  327                 delta_ticks = (time_change->tv_sec * 1000000 +
  328                                time_change->tv_usec + (tick - 1)) / tick + 1;
  329         else if (time_change->tv_sec <= LONG_MAX / hz)
  330                 delta_ticks = time_change->tv_sec * hz +
  331                               (time_change->tv_usec + (tick - 1)) / tick + 1;
  332         else
  333                 delta_ticks = LONG_MAX;
  334 
  335         if (delta_ticks > INT_MAX)
  336                 delta_ticks = INT_MAX;
  337 
  338         /* 
  339          * Now rip through the timer calltodo list looking for timers
  340          * to expire.
  341          */
  342 
  343         /* don't collide with softclock() */
  344         s = splhigh(); 
  345         for (p = calltodo.c_next; p != NULL; p = p->c_next) {
  346                 p->c_time -= delta_ticks;
  347 
  348                 /* Break if the timer had more time on it than delta_ticks */
  349                 if (p->c_time > 0)
  350                         break;
  351 
  352                 /* take back the ticks the timer didn't use (p->c_time <= 0) */
  353                 delta_ticks = -p->c_time;
  354         }
  355         splx(s);
  356 
  357         return;
  358 }
  359 #endif /* APM_FIXUP_CALLTODO */

Cache object: fdc52af328e6a4b32fe16ce17a8da1e2


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]


This page is part of the FreeBSD/Linux Linux Kernel Cross-Reference, and was automatically generated using a modified version of the LXR engine.