sys/kern/kern_cputimer.c

   1 /*
   2  * Copyright (c) 2005 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_cputimer.c,v 1.5 2008/06/05 18:06:32 swildner Exp $
  35  */
  36 /*
  37  * Generic cputimer - access to a reliable, free-running counter.
  38  */
  39
  40 #include <sys/param.h>
  41 #include <sys/kernel.h>
  42 #include <sys/systm.h>
  43 #include <sys/thread.h>
  44 #include <sys/globaldata.h>
  45 #include <sys/systimer.h>
  46 #include <sys/sysctl.h>
  47 #include <sys/thread2.h>
  48
  49 static sysclock_t dummy_cputimer_count(void);
  50
  51 static struct cputimer dummy_cputimer = {
  52     SLIST_ENTRY_INITIALIZER,
  53     "dummy",
  54     CPUTIMER_PRI_DUMMY,
  55     CPUTIMER_DUMMY,
  56     dummy_cputimer_count,
  57     cputimer_default_fromhz,
  58     cputimer_default_fromus,
  59     cputimer_default_construct,
  60     cputimer_default_destruct,
  61     1000000,
  62     (1000000LL << 32) / 1000000,
  63     (1000000000LL << 32) / 1000000,
  64     0
  65 };
  66
  67 struct cputimer *sys_cputimer = &dummy_cputimer;
  68 SLIST_HEAD(, cputimer) cputimerhead = SLIST_HEAD_INITIALIZER(&cputimerhead);
  69
  70 /*
  71  * Generic cputimer API
  72  */
  73 void
  74 cputimer_select(struct cputimer *timer, int pri)
  75 {
  76     sysclock_t oldclock;
  77
  78     /*
  79      * Calculate helper fields
  80      */
  81     cputimer_set_frequency(timer, timer->freq);
  82
  83     /*
  84      * Install a new cputimer if its priority allows it.  If timer is
  85      * passed as NULL we deinstall the current timer and revert to our
  86      * dummy.
  87      */
  88     if (pri == 0)
  89         pri = timer->pri;
  90     if (timer == NULL || pri >= sys_cputimer->pri) {
  91         oldclock = sys_cputimer->count();
  92         sys_cputimer->destruct(sys_cputimer);
  93         sys_cputimer = &dummy_cputimer;
  94         if (timer) {
  95             sys_cputimer = timer;
  96             timer->construct(timer, oldclock);
  97             cputimer_intr_config(timer);
  98         }
  99     }
 100 }
 101
 102 /*
 103  * Register a timer.  If the timer has already been registered, do nothing.
 104  */
 105 void
 106 cputimer_register(struct cputimer *timer)
 107 {
 108     struct cputimer *scan;
 109
 110     /*
 111      * Initialize dummy_cputimer if the slist is empty, it does not get
 112      * registered the normal way.
 113      */
 114     if (SLIST_EMPTY(&cputimerhead))
 115         SLIST_FIRST(&cputimerhead) = &dummy_cputimer;
 116     SLIST_FOREACH(scan, &cputimerhead, next) {
 117         if (scan == timer)
 118             return;
 119     }
 120     SLIST_INSERT_HEAD(&cputimerhead, timer, next);
 121 }
 122
 123 /*
 124  * Deregister a timer.  If the timer has already been deregistered, do nothing.
 125  */
 126 void
 127 cputimer_deregister(struct cputimer *timer)
 128 {
 129     struct cputimer *scan;
 130     struct cputimer *best;
 131
 132     /*
 133      * Locate and remove the timer.  If the timer is our currently active
 134      * timer, revert to the dummy timer.
 135      */
 136     SLIST_FOREACH(scan, &cputimerhead, next) {
 137             if (timer == scan) {
 138                 if (timer == sys_cputimer)
 139                     cputimer_select(&dummy_cputimer, 0x7FFFFFFF);
 140                 SLIST_REMOVE(&cputimerhead, timer, cputimer, next);
 141                 break;
 142             }
 143     }
 144
 145     /*
 146      * If sys_cputimer reverted to the dummy, select the best one
 147      */
 148     if (sys_cputimer == &dummy_cputimer) {
 149         best = NULL;
 150         SLIST_FOREACH(scan, &cputimerhead, next) {
 151             if (best == NULL || scan->pri > best->pri)
 152                 best = scan;
 153         }
 154         if (best)
 155             cputimer_select(best, 0x7FFFFFFF);
 156     }
 157 }
 158
 159 /*
 160  * Calculate usec / tick and nsec / tick, scaled by (1 << 32).
 161  *
 162  * so e.g. a 3 mhz timer would be 3 usec / tick x (1 << 32),
 163  * or 3000 nsec / tick x (1 << 32)
 164  */
 165 void
 166 cputimer_set_frequency(struct cputimer *timer, int freq)
 167 {
 168     timer->freq = freq;
 169     timer->freq64_usec = (1000000LL << 32) / freq;
 170     timer->freq64_nsec = (1000000000LL << 32) / freq;
 171     if (timer == sys_cputimer)
 172         cputimer_intr_config(timer);
 173 }
 174
 175 sysclock_t
 176 cputimer_default_fromhz(int freq)
 177 {
 178     return(sys_cputimer->freq / freq + 1);
 179 }
 180
 181 sysclock_t
 182 cputimer_default_fromus(int us)
 183 {
 184     return((int64_t)sys_cputimer->freq * us / 1000000);
 185 }
 186
 187 /*
 188  * Dummy counter implementation
 189  */
 190 static
 191 sysclock_t
 192 dummy_cputimer_count(void)
 193 {
 194     return(++dummy_cputimer.base);
 195 }
 196
 197 void
 198 cputimer_default_construct(struct cputimer *cputimer, sysclock_t oldclock)
 199 {
 200     cputimer->base = oldclock;
 201 }
 202
 203 void
 204 cputimer_default_destruct(struct cputimer *cputimer)
 205 {
 206 }
 207
 208 /************************************************************************
 209  *                              SYSCTL SUPPORT                          *
 210  ************************************************************************
 211  *
 212  * Note: the ability to change the systimer is not currently enabled
 213  * because it will mess up systimer calculations.  You have to live
 214  * with what is configured at boot.
 215  */
 216 static int
 217 sysctl_cputimer_reglist(SYSCTL_HANDLER_ARGS)
 218 {
 219     struct cputimer *scan;
 220     int error = 0;
 221     int loop = 0;
 222
 223     /*
 224      * Build a list of available timers
 225      */
 226     SLIST_FOREACH(scan, &cputimerhead, next) {
 227         if (error == 0 && loop)
 228             error = SYSCTL_OUT(req, " ", 1);
 229         if (error == 0)
 230             error = SYSCTL_OUT(req, scan->name, strlen(scan->name));
 231         ++loop;
 232     }
 233     return (error);
 234 }
 235
 236 static int
 237 sysctl_cputimer_name(SYSCTL_HANDLER_ARGS)
 238 {
 239     int error;
 240
 241     error = SYSCTL_OUT(req, sys_cputimer->name, strlen(sys_cputimer->name));
 242     return (error);
 243 }
 244
 245 static int
 246 sysctl_cputimer_clock(SYSCTL_HANDLER_ARGS)
 247 {
 248     sysclock_t clock;
 249     int error;
 250
 251     clock = sys_cputimer->count();
 252     error = SYSCTL_OUT(req, &clock, sizeof(clock));
 253     return (error);
 254 }
 255
 256 static int
 257 sysctl_cputimer_freq(SYSCTL_HANDLER_ARGS)
 258 {
 259     int error;
 260
 261     error = SYSCTL_OUT(req, &sys_cputimer->freq, sizeof(sys_cputimer->freq));
 262     return (error);
 263 }
 264
 265 SYSCTL_DECL(_kern_cputimer);
 266 SYSCTL_NODE(_kern, OID_AUTO, cputimer, CTLFLAG_RW, NULL, "cputimer");
 267
 268 SYSCTL_PROC(_kern_cputimer, OID_AUTO, select, CTLTYPE_STRING|CTLFLAG_RD,
 269             NULL, 0, sysctl_cputimer_reglist, "A", "");
 270 SYSCTL_PROC(_kern_cputimer, OID_AUTO, name, CTLTYPE_STRING|CTLFLAG_RD,
 271             NULL, 0, sysctl_cputimer_name, "A", "");
 272 SYSCTL_PROC(_kern_cputimer, OID_AUTO, clock, CTLTYPE_UINT|CTLFLAG_RD,
 273             NULL, 0, sysctl_cputimer_clock, "IU", "");
 274 SYSCTL_PROC(_kern_cputimer, OID_AUTO, freq, CTLTYPE_INT|CTLFLAG_RD,
 275             NULL, 0, sysctl_cputimer_freq, "I", "");
 276
 277