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_add(systimer_t info)
 139 {
 140     struct globaldata *gd = mycpu;
 141
 142     KKASSERT((info->flags & SYSTF_ONQUEUE) == 0);
 143     crit_enter();
 144     if (info->gd == gd) {
 145         systimer_t scan1;
 146         systimer_t scan2;
 147         scan1 = TAILQ_FIRST(&gd->gd_systimerq);
 148         if (scan1 == NULL || (int)(scan1->time - info->time) > 0) {
 149             cputimer_intr_reload(info->time - sys_cputimer->count());
 150             TAILQ_INSERT_HEAD(&gd->gd_systimerq, info, node);
 151         } else {
 152             scan2 = TAILQ_LAST(&gd->gd_systimerq, systimerq);
 153             for (;;) {
 154                 if (scan1 == NULL) {
 155                     TAILQ_INSERT_TAIL(&gd->gd_systimerq, info, node);
 156                     break;
 157                 }
 158                 if ((int)(scan1->time - info->time) > 0) {
 159                     TAILQ_INSERT_BEFORE(scan1, info, node);
 160                     break;
 161                 }
 162                 if ((int)(scan2->time - info->time) <= 0) {
 163                     TAILQ_INSERT_AFTER(&gd->gd_systimerq, scan2, info, node);
 164                     break;
 165                 }
 166                 scan1 = TAILQ_NEXT(scan1, node);
 167                 scan2 = TAILQ_PREV(scan2, systimerq, node);
 168             }
 169         }
 170         info->flags = (info->flags | SYSTF_ONQUEUE) & ~SYSTF_IPIRUNNING;
 171         info->queue = &gd->gd_systimerq;
 172     } else {
 173 #ifdef SMP
 174         KKASSERT((info->flags & SYSTF_IPIRUNNING) == 0);
 175         info->flags |= SYSTF_IPIRUNNING;
 176         lwkt_send_ipiq(info->gd, (ipifunc1_t)systimer_add, info);
 177 #else
 178         panic("systimer_add: bad gd in info %p", info);
 179 #endif
 180     }
 181     crit_exit();
 182 }
 183
 184 /*
 185  * systimer_del()
 186  *
 187  *      Delete a system timer.  Only the owning cpu can delete a timer.
 188  */
 189 void
 190 systimer_del(systimer_t info)
 191 {
 192     struct globaldata *gd = info->gd;
 193
 194     KKASSERT(gd == mycpu && (info->flags & SYSTF_IPIRUNNING) == 0);
 195
 196     crit_enter();
 197
 198     if (info->flags & SYSTF_ONQUEUE) {
 199         TAILQ_REMOVE(info->queue, info, node);
 200         info->flags &= ~SYSTF_ONQUEUE;
 201     }
 202
 203     /*
 204      * Deal with dispatch races by clearing the in-progress systimer
 205      * pointer.  Only a direct pointer comparison can be used, the
 206      * actual contents of the structure gd_systimer_inprog points to,
 207      * if not equal to info, may be stale.
 208      */
 209     if (gd->gd_systimer_inprog == info)
 210         gd->gd_systimer_inprog = NULL;
 211
 212     crit_exit();
 213 }
 214
 215 /*
 216  * systimer_init_periodic()
 217  *
 218  *      Initialize a periodic timer at the specified frequency and add
 219  *      it to the system.  The frequency is uncompensated and approximate.
 220  *
 221  *      Try to synchronize multi registrations of the same or similar
 222  *      frequencies so the hardware interrupt is able to dispatch several
 223  *      at together by adjusting the phase of the initial interrupt.  This
 224  *      helps SMP.  Note that we are not attempting to synchronize to
 225  *      the realtime clock.
 226  */
 227 void
 228 systimer_init_periodic(systimer_t info, void *func, void *data, int hz)
 229 {
 230     sysclock_t base_count;
 231
 232     bzero(info, sizeof(struct systimer));
 233     info->periodic = sys_cputimer->fromhz(hz);
 234     base_count = sys_cputimer->count();
 235     base_count = base_count - (base_count % info->periodic);
 236     info->time = base_count + info->periodic;
 237     info->func = func;
 238     info->data = data;
 239     info->freq = hz;
 240     info->which = sys_cputimer;
 241     info->gd = mycpu;
 242     systimer_add(info);
 243 }
 244
 245 void
 246 systimer_init_periodic_nq(systimer_t info, void *func, void *data, int hz)
 247 {
 248     sysclock_t base_count;
 249
 250     bzero(info, sizeof(struct systimer));
 251     info->periodic = sys_cputimer->fromhz(hz);
 252     base_count = sys_cputimer->count();
 253     base_count = base_count - (base_count % info->periodic);
 254     info->time = base_count + info->periodic;
 255     info->func = func;
 256     info->data = data;
 257     info->freq = hz;
 258     info->which = sys_cputimer;
 259     info->gd = mycpu;
 260     info->flags |= SYSTF_NONQUEUED;
 261     systimer_add(info);
 262 }
 263
 264 /*
 265  * Adjust the periodic interval for a periodic timer which is already
 266  * running.  The current timeout is not effected.
 267  */
 268 void
 269 systimer_adjust_periodic(systimer_t info, int hz)
 270 {
 271     crit_enter();
 272     info->periodic = sys_cputimer->fromhz(hz);
 273     info->freq = hz;
 274     info->which = sys_cputimer;
 275     crit_exit();
 276 }
 277
 278 /*
 279  * systimer_init_oneshot()
 280  *
 281  *      Initialize a periodic timer at the specified frequency and add
 282  *      it to the system.  The frequency is uncompensated and approximate.
 283  */
 284 void
 285 systimer_init_oneshot(systimer_t info, void *func, void *data, int us)
 286 {
 287     bzero(info, sizeof(struct systimer));
 288     info->time = sys_cputimer->count() + sys_cputimer->fromus(us);
 289     info->func = func;
 290     info->data = data;
 291     info->which = sys_cputimer;
 292     info->gd = mycpu;
 293     systimer_add(info);
 294 }
 295