subr_devstat.c

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    1 /*
    2  * Copyright (c) 1997, 1998, 1999 Kenneth D. Merry.
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  * 3. The name of the author may not be used to endorse or promote products
   14  *    derived from this software without specific prior written permission.
   15  *
   16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   26  * SUCH DAMAGE.
   27  *
   28  * $FreeBSD$
   29  */
   30 
   31 #include <sys/param.h>
   32 #include <sys/kernel.h>
   33 #include <sys/systm.h>
   34 #include <sys/buf.h>
   35 #include <sys/sysctl.h>
   36 
   37 #include <sys/devicestat.h>
   38 
   39 static int devstat_num_devs;
   40 static long devstat_generation;
   41 static int devstat_version = DEVSTAT_VERSION;
   42 static int devstat_current_devnumber;
   43 
   44 static STAILQ_HEAD(devstatlist, devstat) device_statq;
   45 
   46 /*
   47  * Take a malloced and zeroed devstat structure given to us, fill it in 
   48  * and add it to the queue of devices.  
   49  */
   50 void
   51 devstat_add_entry(struct devstat *ds, const char *dev_name, 
   52                   int unit_number, u_int32_t block_size,
   53                   devstat_support_flags flags,
   54                   devstat_type_flags device_type,
   55                   devstat_priority priority)
   56 {
   57         struct devstatlist *devstat_head;
   58         struct devstat *ds_tmp;
   59 
   60         if (ds == NULL)
   61                 return;
   62 
   63         if (devstat_num_devs == 0)
   64                 STAILQ_INIT(&device_statq);
   65 
   66         devstat_generation++;
   67         devstat_num_devs++;
   68 
   69         devstat_head = &device_statq;
   70 
   71         /*
   72          * Priority sort.  Each driver passes in its priority when it adds
   73          * its devstat entry.  Drivers are sorted first by priority, and
   74          * then by probe order.
   75          * 
   76          * For the first device, we just insert it, since the priority
   77          * doesn't really matter yet.  Subsequent devices are inserted into
   78          * the list using the order outlined above.
   79          */
   80         if (devstat_num_devs == 1)
   81                 STAILQ_INSERT_TAIL(devstat_head, ds, dev_links);
   82         else {
   83                 for (ds_tmp = STAILQ_FIRST(devstat_head); ds_tmp != NULL;
   84                      ds_tmp = STAILQ_NEXT(ds_tmp, dev_links)) {
   85                         struct devstat *ds_next;
   86 
   87                         ds_next = STAILQ_NEXT(ds_tmp, dev_links);
   88 
   89                         /*
   90                          * If we find a break between higher and lower
   91                          * priority items, and if this item fits in the
   92                          * break, insert it.  This also applies if the
   93                          * "lower priority item" is the end of the list.
   94                          */
   95                         if ((priority <= ds_tmp->priority)
   96                          && ((ds_next == NULL)
   97                            || (priority > ds_next->priority))) {
   98                                 STAILQ_INSERT_AFTER(devstat_head, ds_tmp, ds,
   99                                                     dev_links);
  100                                 break;
  101                         } else if (priority > ds_tmp->priority) {
  102                                 /*
  103                                  * If this is the case, we should be able
  104                                  * to insert ourselves at the head of the
  105                                  * list.  If we can't, something is wrong.
  106                                  */
  107                                 if (ds_tmp == STAILQ_FIRST(devstat_head)) {
  108                                         STAILQ_INSERT_HEAD(devstat_head,
  109                                                            ds, dev_links);
  110                                         break;
  111                                 } else {
  112                                         STAILQ_INSERT_TAIL(devstat_head,
  113                                                            ds, dev_links);
  114                                         printf("devstat_add_entry: HELP! "
  115                                                "sorting problem detected "
  116                                                "for %s%d\n", dev_name,
  117                                                unit_number);
  118                                         break;
  119                                 }
  120                         }
  121                 }
  122         }
  123 
  124         ds->device_number = devstat_current_devnumber++;
  125         ds->unit_number = unit_number;
  126         strncpy(ds->device_name, dev_name, DEVSTAT_NAME_LEN);
  127         ds->device_name[DEVSTAT_NAME_LEN - 1] = '\0';
  128         ds->block_size = block_size;
  129         ds->flags = flags;
  130         ds->device_type = device_type;
  131         ds->priority = priority;
  132         getmicrotime(&ds->dev_creation_time);
  133 }
  134 
  135 /*
  136  * Remove a devstat structure from the list of devices.
  137  */
  138 void
  139 devstat_remove_entry(struct devstat *ds)
  140 {
  141         struct devstatlist *devstat_head;
  142 
  143         if (ds == NULL)
  144                 return;
  145 
  146         devstat_generation++;
  147         devstat_num_devs--;
  148 
  149         devstat_head = &device_statq;
  150 
  151         /* Remove this entry from the devstat queue */
  152         STAILQ_REMOVE(devstat_head, ds, devstat, dev_links);
  153 }
  154 
  155 /*
  156  * Record a transaction start.
  157  */
  158 void
  159 devstat_start_transaction(struct devstat *ds)
  160 {
  161         /* sanity check */
  162         if (ds == NULL)
  163                 return;
  164 
  165         /*
  166          * We only want to set the start time when we are going from idle
  167          * to busy.  The start time is really the start of the latest busy
  168          * period.
  169          */
  170         if (ds->busy_count == 0)
  171                 getmicrouptime(&ds->start_time);
  172         ds->busy_count++;
  173 }
  174 
  175 /*
  176  * Record the ending of a transaction, and incrment the various counters.
  177  */
  178 void
  179 devstat_end_transaction(struct devstat *ds, u_int32_t bytes, 
  180                         devstat_tag_type tag_type, devstat_trans_flags flags)
  181 {
  182         struct timeval busy_time;
  183 
  184         /* sanity check */
  185         if (ds == NULL)
  186                 return;
  187 
  188         getmicrouptime(&ds->last_comp_time);
  189         ds->busy_count--;
  190 
  191         /*
  192          * There might be some transactions (DEVSTAT_NO_DATA) that don't
  193          * transfer any data.
  194          */
  195         if (flags == DEVSTAT_READ) {
  196                 ds->bytes_read += bytes;
  197                 ds->num_reads++;
  198         } else if (flags == DEVSTAT_WRITE) {
  199                 ds->bytes_written += bytes;
  200                 ds->num_writes++;
  201         } else if (flags == DEVSTAT_FREE) {
  202                 ds->bytes_freed += bytes;
  203                 ds->num_frees++;
  204         } else
  205                 ds->num_other++;
  206 
  207         /*
  208          * Keep a count of the various tag types sent.
  209          */
  210         if ((ds->flags & DEVSTAT_NO_ORDERED_TAGS) == 0 &&
  211             tag_type != DEVSTAT_TAG_NONE)
  212                 ds->tag_types[tag_type]++;
  213 
  214         /*
  215          * We only update the busy time when we go idle.  Otherwise, this
  216          * calculation would require many more clock cycles.
  217          */
  218         if (ds->busy_count == 0) {
  219                 /* Calculate how long we were busy */
  220                 busy_time = ds->last_comp_time;
  221                 timevalsub(&busy_time, &ds->start_time);
  222 
  223                 /* Add our busy time to the total busy time. */
  224                 timevaladd(&ds->busy_time, &busy_time);
  225         } else if (ds->busy_count < 0)
  226                 printf("devstat_end_transaction: HELP!! busy_count "
  227                        "for %s%d is < 0 (%d)!\n", ds->device_name,
  228                        ds->unit_number, ds->busy_count);
  229 }
  230 
  231 void
  232 devstat_end_transaction_buf(struct devstat *ds, struct buf *bp)
  233 {
  234         devstat_trans_flags flg;
  235 
  236         if (bp->b_flags & B_FREEBUF)
  237                 flg = DEVSTAT_FREE;
  238         else if (bp->b_flags & B_READ)
  239                 flg = DEVSTAT_READ;
  240         else
  241                 flg = DEVSTAT_WRITE;
  242 
  243         devstat_end_transaction(ds, bp->b_bcount - bp->b_resid,
  244                                 (bp->b_flags & B_ORDERED) ?
  245                                 DEVSTAT_TAG_ORDERED : DEVSTAT_TAG_SIMPLE, flg);
  246 }
  247 
  248 /*
  249  * This is the sysctl handler for the devstat package.  The data pushed out
  250  * on the kern.devstat.all sysctl variable consists of the current devstat
  251  * generation number, and then an array of devstat structures, one for each
  252  * device in the system.
  253  *
  254  * I'm really not too fond of this method of doing things, but there really
  255  * aren't that many alternatives.  We must have some method of making sure
  256  * that the generation number the user gets corresponds with the data the
  257  * user gets.  If the user makes a separate sysctl call to get the
  258  * generation, and then a sysctl call to get the device statistics, the
  259  * device list could have changed in that brief period of time.  By
  260  * supplying the generation number along with the statistics output, we can
  261  * guarantee that the generation number and the statistics match up.
  262  */
  263 static int
  264 sysctl_devstat(SYSCTL_HANDLER_ARGS)
  265 {
  266         int error, i;
  267         struct devstat *nds;
  268         struct devstatlist *devstat_head;
  269 
  270         if (devstat_num_devs == 0)
  271                 return(EINVAL);
  272 
  273         error = 0;
  274         devstat_head = &device_statq;
  275 
  276         /*
  277          * First push out the generation number.
  278          */
  279         error = SYSCTL_OUT(req, &devstat_generation, sizeof(long));
  280 
  281         /*
  282          * Now push out all the devices.
  283          */
  284         for (i = 0, nds = STAILQ_FIRST(devstat_head); 
  285             (nds != NULL) && (i < devstat_num_devs) && (error == 0); 
  286              nds = STAILQ_NEXT(nds, dev_links), i++)
  287                 error = SYSCTL_OUT(req, nds, sizeof(struct devstat));
  288 
  289         return(error);
  290 }
  291 
  292 /*
  293  * Sysctl entries for devstat.  The first one is a node that all the rest
  294  * hang off of. 
  295  */
  296 SYSCTL_NODE(_kern, OID_AUTO, devstat, CTLFLAG_RD, 0, "Device Statistics");
  297 
  298 SYSCTL_PROC(_kern_devstat, OID_AUTO, all, CTLFLAG_RD|CTLTYPE_OPAQUE,
  299     0, 0, sysctl_devstat, "S,devstat", "All devices in the devstat list");
  300 /*
  301  * Export the number of devices in the system so that userland utilities
  302  * can determine how much memory to allocate to hold all the devices.
  303  */
  304 SYSCTL_INT(_kern_devstat, OID_AUTO, numdevs, CTLFLAG_RD, 
  305     &devstat_num_devs, 0, "Number of devices in the devstat list");
  306 SYSCTL_LONG(_kern_devstat, OID_AUTO, generation, CTLFLAG_RD,
  307     &devstat_generation, 0, "Devstat list generation");
  308 SYSCTL_INT(_kern_devstat, OID_AUTO, version, CTLFLAG_RD, 
  309     &devstat_version, 0, "Devstat list version number");
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FreeBSD/Linux Kernel Cross Reference sys/kern/subr_devstat.c

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