sys/kern/kern_systimer.c

   1 /*
   2  * Copyright (c) 2003,2004 The DragonFly Project.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Matthew Dillon <dillon@backplane.com>
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in
  15  *    the documentation and/or other materials provided with the
  16  *    distribution.
  17  * 3. Neither the name of The DragonFly Project nor the names of its
  18  *    contributors may be used to endorse or promote products derived
  19  *    from this software without specific, prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  * $DragonFly: src/sys/kern/kern_systimer.c,v 1.12 2007/10/16 11:12:59 sephe Exp $
  35  */
  36
  37 /*
  38  * WARNING!  THE SYSTIMER MODULE DOES NOT OPERATE OR DISPATCH WITH THE
  39  * MP LOCK HELD.  ALL CODE USING THIS MODULE MUST BE MP-SAFE.
  40  *
  41  * This code implements a fine-grained per-cpu system timer which is
  42  * ultimately based on a hardware timer.  The hardware timer abstraction
  43  * is sufficiently disconnected from this code to support both per-cpu
  44  * hardware timers or a single system-wide hardware timer.
  45  *
  46  * WARNING!  During early boot if a new system timer is selected, existing
  47  * timeouts will not be effected and will thus occur slower or faster.
  48  * periodic timers will be adjusted at the next periodic load.
  49  *
  50  * Notes on machine-dependant code (in arch/arch/systimer.c)
  51  *
  52  * cputimer_intr_reload()       Reload the one-shot (per-cpu basis)
  53  */
  54
  55 #include <sys/param.h>
  56 #include <sys/kernel.h>
  57 #include <sys/systm.h>
  58 #include <sys/thread.h>
  59 #include <sys/globaldata.h>
  60 #include <sys/systimer.h>
  61 #include <sys/thread2.h>
  62
  63 /*
  64  * Execute ready systimers.  Called directly from the platform-specific
  65  * one-shot timer clock interrupt (e.g. clkintr()) or via an IPI.  May
  66  * be called simultaniously on multiple cpus and always operations on
  67  * the current cpu's queue.  Systimer functions are responsible for calling
  68  * hardclock, statclock, and other finely-timed routines.
  69  */
  70 void
  71 systimer_intr(sysclock_t *timep, int dummy, struct intrframe *frame)
  72 {
  73     globaldata_t gd = mycpu;
  74     sysclock_t time = *timep;
  75     systimer_t info;
  76
  77     if (gd->gd_syst_nest)
  78         return;
  79
  80     crit_enter();
  81     ++gd->gd_syst_nest;
  82     while ((info = TAILQ_FIRST(&gd->gd_systimerq)) != NULL) {
  83         /*
  84          * If we haven't reached the requested time, tell the cputimer
  85          * how much is left and break out.
  86          */
  87         if ((int)(info->time - time) > 0) {
  88             cputimer_intr_reload(info->time - time);
  89             break;
  90         }
  91
  92         /*
  93          * Dequeue and execute, detect a loss of the systimer.  Note
  94          * that the in-progress systimer pointer can only be used to
  95          * detect a loss of the systimer, it is only useful within
  96          * this code sequence and becomes stale otherwise.
  97          */
  98         info->flags &= ~SYSTF_ONQUEUE;
  99         TAILQ_REMOVE(info->queue, info, node);
 100         gd->gd_systimer_inprog = info;
 101         crit_exit();
 102         info->func(info, frame);
 103         crit_enter();
 104
 105         /*
 106          * The caller may deleted or even re-queue the systimer itself
 107          * with a delete/add sequence.  If the caller does not mess with
 108          * the systimer we will requeue the periodic interval automatically.
 109          *
 110          * If this is a non-queued periodic interrupt, do not allow multiple
 111          * events to build up (used for things like the callout timer to
 112          * prevent premature timeouts due to long interrupt disablements,
 113          * BIOS 8254 glitching, and so forth).  However, we still want to
 114          * keep things synchronized between cpus for efficient handling of
 115          * the timer interrupt so jump in multiples of the periodic rate.
 116          */
 117         if (gd->gd_systimer_inprog == info && info->periodic) {
 118             if (info->which != sys_cputimer) {
 119                 info->periodic = sys_cputimer->fromhz(info->freq);
 120                 info->which = sys_cputimer;
 121             }
 122             info->time += info->periodic;
 123             if ((info->flags & SYSTF_NONQUEUED) &&
 124                 (int)(info->time - time) <= 0
 125             ) {
 126                 info->time += ((time - info->time + info->periodic - 1) /
 127                                 info->periodic) * info->periodic;
 128             }
 129             systimer_add(info);
 130         }
 131         gd->gd_systimer_inprog = NULL;
 132     }
 133     --gd->gd_syst_nest;
 134     crit_exit();
 135 }
 136
 137 void
 138 systimer_intr_enable(void)
 139 {
 140     cputimer_intr_enable();
 141 }
 142
 143 void
 144 systimer_add(systimer_t info)
 145 {
 146     struct globaldata *gd = mycpu;
 147
 148     KKASSERT((info->flags & SYSTF_ONQUEUE) == 0);
 149     crit_enter();
 150     if (info->gd == gd) {
 151         systimer_t scan1;
 152         systimer_t scan2;
 153         scan1 = TAILQ_FIRST(&gd->gd_systimerq);
 154         if (scan1 == NULL || (int)(scan1->time - info->time) > 0) {
 155             cputimer_intr_reload(info->time - sys_cputimer->count());
 156             TAILQ_INSERT_HEAD(&gd->gd_systimerq, info, node);
 157         } else {
 158             scan2 = TAILQ_LAST(&gd->gd_systimerq, systimerq);
 159             for (;;) {
 160                 if (scan1 == NULL) {
 161                     TAILQ_INSERT_TAIL(&gd->gd_systimerq, info, node);
 162                     break;
 163                 }
 164                 if ((int)(scan1->time - info->time) > 0) {
 165                     TAILQ_INSERT_BEFORE(scan1, info, node);
 166                     break;
 167                 }
 168                 if ((int)(scan2->time - info->time) <= 0) {
 169                     TAILQ_INSERT_AFTER(&gd->gd_systimerq, scan2, info, node);
 170                     break;
 171                 }
 172                 scan1 = TAILQ_NEXT(scan1, node);
 173                 scan2 = TAILQ_PREV(scan2, systimerq, node);
 174             }
 175         }
 176         info->flags = (info->flags | SYSTF_ONQUEUE) & ~SYSTF_IPIRUNNING;
 177         info->queue = &gd->gd_systimerq;
 178     } else {
 179 #ifdef SMP
 180         KKASSERT((info->flags & SYSTF_IPIRUNNING) == 0);
 181         info->flags |= SYSTF_IPIRUNNING;
 182         lwkt_send_ipiq(info->gd, (ipifunc1_t)systimer_add, info);
 183 #else
 184         panic("systimer_add: bad gd in info %p", info);
 185 #endif
 186     }
 187     crit_exit();
 188 }
 189
 190 /*
 191  * systimer_del()
 192  *
 193  *      Delete a system timer.  Only the owning cpu can delete a timer.
 194  */
 195 void
 196 systimer_del(systimer_t info)
 197 {
 198     struct globaldata *gd = info->gd;
 199
 200     KKASSERT(gd == mycpu && (info->flags & SYSTF_IPIRUNNING) == 0);
 201
 202     crit_enter();
 203
 204     if (info->flags & SYSTF_ONQUEUE) {
 205         TAILQ_REMOVE(info->queue, info, node);
 206         info->flags &= ~SYSTF_ONQUEUE;
 207     }
 208
 209     /*
 210      * Deal with dispatch races by clearing the in-progress systimer
 211      * pointer.  Only a direct pointer comparison can be used, the
 212      * actual contents of the structure gd_systimer_inprog points to,
 213      * if not equal to info, may be stale.
 214      */
 215     if (gd->gd_systimer_inprog == info)
 216         gd->gd_systimer_inprog = NULL;
 217
 218     crit_exit();
 219 }
 220
 221 /*
 222  * systimer_init_periodic()
 223  *
 224  *      Initialize a periodic timer at the specified frequency and add
 225  *      it to the system.  The frequency is uncompensated and approximate.
 226  *
 227  *      Try to synchronize multi registrations of the same or similar
 228  *      frequencies so the hardware interrupt is able to dispatch several
 229  *      at together by adjusting the phase of the initial interrupt.  This
 230  *      helps SMP.  Note that we are not attempting to synchronize to
 231  *      the realtime clock.
 232  */
 233 void
 234 systimer_init_periodic(systimer_t info, void *func, void *data, int hz)
 235 {
 236     sysclock_t base_count;
 237
 238     bzero(info, sizeof(struct systimer));
 239     info->periodic = sys_cputimer->fromhz(hz);
 240     base_count = sys_cputimer->count();
 241     base_count = base_count - (base_count % info->periodic);
 242     info->time = base_count + info->periodic;
 243     info->func = func;
 244     info->data = data;
 245     info->freq = hz;
 246     info->which = sys_cputimer;
 247     info->gd = mycpu;
 248     systimer_add(info);
 249 }
 250
 251 void
 252 systimer_init_periodic_nq(systimer_t info, void *func, void *data, int hz)
 253 {
 254     sysclock_t base_count;
 255
 256     bzero(info, sizeof(struct systimer));
 257     info->periodic = sys_cputimer->fromhz(hz);
 258     base_count = sys_cputimer->count();
 259     base_count = base_count - (base_count % info->periodic);
 260     info->time = base_count + info->periodic;
 261     info->func = func;
 262     info->data = data;
 263     info->freq = hz;
 264     info->which = sys_cputimer;
 265     info->gd = mycpu;
 266     info->flags |= SYSTF_NONQUEUED;
 267     systimer_add(info);
 268 }
 269
 270 /*
 271  * Adjust the periodic interval for a periodic timer which is already
 272  * running.  The current timeout is not effected.
 273  */
 274 void
 275 systimer_adjust_periodic(systimer_t info, int hz)
 276 {
 277     crit_enter();
 278     info->periodic = sys_cputimer->fromhz(hz);
 279     info->freq = hz;
 280     info->which = sys_cputimer;
 281     crit_exit();
 282 }
 283
 284 /*
 285  * systimer_init_oneshot()
 286  *
 287  *      Initialize a periodic timer at the specified frequency and add
 288  *      it to the system.  The frequency is uncompensated and approximate.
 289  */
 290 void
 291 systimer_init_oneshot(systimer_t info, void *func, void *data, int us)
 292 {
 293     bzero(info, sizeof(struct systimer));
 294     info->time = sys_cputimer->count() + sys_cputimer->fromus(us);
 295     info->func = func;
 296     info->data = data;
 297     info->which = sys_cputimer;
 298     info->gd = mycpu;
 299     systimer_add(info);
 300 }
 301