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: releng/5.0/sys/kern/subr_devstat.c 105354 2002-10-17 20:03:38Z robert $
   29  */
   30 
   31 #include <sys/param.h>
   32 #include <sys/kernel.h>
   33 #include <sys/systm.h>
   34 #include <sys/bio.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 struct devstatlist 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                 STAILQ_FOREACH(ds_tmp, devstat_head, dev_links) {
   84                         struct devstat *ds_next;
   85 
   86                         ds_next = STAILQ_NEXT(ds_tmp, dev_links);
   87 
   88                         /*
   89                          * If we find a break between higher and lower
   90                          * priority items, and if this item fits in the
   91                          * break, insert it.  This also applies if the
   92                          * "lower priority item" is the end of the list.
   93                          */
   94                         if ((priority <= ds_tmp->priority)
   95                          && ((ds_next == NULL)
   96                            || (priority > ds_next->priority))) {
   97                                 STAILQ_INSERT_AFTER(devstat_head, ds_tmp, ds,
   98                                                     dev_links);
   99                                 break;
  100                         } else if (priority > ds_tmp->priority) {
  101                                 /*
  102                                  * If this is the case, we should be able
  103                                  * to insert ourselves at the head of the
  104                                  * list.  If we can't, something is wrong.
  105                                  */
  106                                 if (ds_tmp == STAILQ_FIRST(devstat_head)) {
  107                                         STAILQ_INSERT_HEAD(devstat_head,
  108                                                            ds, dev_links);
  109                                         break;
  110                                 } else {
  111                                         STAILQ_INSERT_TAIL(devstat_head,
  112                                                            ds, dev_links);
  113                                         printf("devstat_add_entry: HELP! "
  114                                                "sorting problem detected "
  115                                                "for %s%d\n", dev_name,
  116                                                unit_number);
  117                                         break;
  118                                 }
  119                         }
  120                 }
  121         }
  122 
  123         ds->device_number = devstat_current_devnumber++;
  124         ds->unit_number = unit_number;
  125         strlcpy(ds->device_name, dev_name, DEVSTAT_NAME_LEN);
  126         ds->block_size = block_size;
  127         ds->flags = flags;
  128         ds->device_type = device_type;
  129         ds->priority = priority;
  130         getmicrotime(&ds->dev_creation_time);
  131 }
  132 
  133 /*
  134  * Remove a devstat structure from the list of devices.
  135  */
  136 void
  137 devstat_remove_entry(struct devstat *ds)
  138 {
  139         struct devstatlist *devstat_head;
  140 
  141         if (ds == NULL)
  142                 return;
  143 
  144         devstat_generation++;
  145         devstat_num_devs--;
  146 
  147         devstat_head = &device_statq;
  148 
  149         /* Remove this entry from the devstat queue */
  150         STAILQ_REMOVE(devstat_head, ds, devstat, dev_links);
  151 }
  152 
  153 /*
  154  * Record a transaction start.
  155  */
  156 void
  157 devstat_start_transaction(struct devstat *ds)
  158 {
  159         /* sanity check */
  160         if (ds == NULL)
  161                 return;
  162 
  163         /*
  164          * We only want to set the start time when we are going from idle
  165          * to busy.  The start time is really the start of the latest busy
  166          * period.
  167          */
  168         if (ds->busy_count == 0)
  169                 getmicrouptime(&ds->start_time);
  170         ds->busy_count++;
  171 }
  172 
  173 /*
  174  * Record the ending of a transaction, and incrment the various counters.
  175  */
  176 void
  177 devstat_end_transaction(struct devstat *ds, u_int32_t bytes, 
  178                         devstat_tag_type tag_type, devstat_trans_flags flags)
  179 {
  180         struct timeval busy_time;
  181 
  182         /* sanity check */
  183         if (ds == NULL)
  184                 return;
  185 
  186         getmicrouptime(&ds->last_comp_time);
  187         ds->busy_count--;
  188 
  189         /*
  190          * There might be some transactions (DEVSTAT_NO_DATA) that don't
  191          * transfer any data.
  192          */
  193         if (flags == DEVSTAT_READ) {
  194                 ds->bytes_read += bytes;
  195                 ds->num_reads++;
  196         } else if (flags == DEVSTAT_WRITE) {
  197                 ds->bytes_written += bytes;
  198                 ds->num_writes++;
  199         } else if (flags == DEVSTAT_FREE) {
  200                 ds->bytes_freed += bytes;
  201                 ds->num_frees++;
  202         } else
  203                 ds->num_other++;
  204 
  205         /*
  206          * Keep a count of the various tag types sent.
  207          */
  208         if ((ds->flags & DEVSTAT_NO_ORDERED_TAGS) == 0 &&
  209             tag_type != DEVSTAT_TAG_NONE)
  210                 ds->tag_types[tag_type]++;
  211 
  212         /*
  213          * We only update the busy time when we go idle.  Otherwise, this
  214          * calculation would require many more clock cycles.
  215          */
  216         if (ds->busy_count == 0) {
  217                 /* Calculate how long we were busy */
  218                 busy_time = ds->last_comp_time;
  219                 timevalsub(&busy_time, &ds->start_time);
  220 
  221                 /* Add our busy time to the total busy time. */
  222                 timevaladd(&ds->busy_time, &busy_time);
  223         } else if (ds->busy_count < 0)
  224                 printf("devstat_end_transaction: HELP!! busy_count "
  225                        "for %s%d is < 0 (%d)!\n", ds->device_name,
  226                        ds->unit_number, ds->busy_count);
  227 }
  228 
  229 void
  230 devstat_end_transaction_bio(struct devstat *ds, struct bio *bp)
  231 {
  232         devstat_trans_flags flg;
  233 
  234         if (bp->bio_cmd == BIO_DELETE)
  235                 flg = DEVSTAT_FREE;
  236         else if (bp->bio_cmd == BIO_READ)
  237                 flg = DEVSTAT_READ;
  238         else
  239                 flg = DEVSTAT_WRITE;
  240 
  241         devstat_end_transaction(ds, bp->bio_bcount - bp->bio_resid,
  242                                 DEVSTAT_TAG_SIMPLE, flg);
  243 }
  244 
  245 /*
  246  * This is the sysctl handler for the devstat package.  The data pushed out
  247  * on the kern.devstat.all sysctl variable consists of the current devstat
  248  * generation number, and then an array of devstat structures, one for each
  249  * device in the system.
  250  *
  251  * I'm really not too fond of this method of doing things, but there really
  252  * aren't that many alternatives.  We must have some method of making sure
  253  * that the generation number the user gets corresponds with the data the
  254  * user gets.  If the user makes a separate sysctl call to get the
  255  * generation, and then a sysctl call to get the device statistics, the
  256  * device list could have changed in that brief period of time.  By
  257  * supplying the generation number along with the statistics output, we can
  258  * guarantee that the generation number and the statistics match up.
  259  */
  260 static int
  261 sysctl_devstat(SYSCTL_HANDLER_ARGS)
  262 {
  263         int error, i;
  264         struct devstat *nds;
  265         struct devstatlist *devstat_head;
  266 
  267         if (devstat_num_devs == 0)
  268                 return(EINVAL);
  269 
  270         error = 0;
  271         devstat_head = &device_statq;
  272 
  273         /*
  274          * First push out the generation number.
  275          */
  276         error = SYSCTL_OUT(req, &devstat_generation, sizeof(long));
  277 
  278         /*
  279          * Now push out all the devices.
  280          */
  281         for (i = 0, nds = STAILQ_FIRST(devstat_head); 
  282             (nds != NULL) && (i < devstat_num_devs) && (error == 0); 
  283              nds = STAILQ_NEXT(nds, dev_links), i++)
  284                 error = SYSCTL_OUT(req, nds, sizeof(struct devstat));
  285 
  286         return(error);
  287 }
  288 
  289 /*
  290  * Sysctl entries for devstat.  The first one is a node that all the rest
  291  * hang off of. 
  292  */
  293 SYSCTL_NODE(_kern, OID_AUTO, devstat, CTLFLAG_RD, 0, "Device Statistics");
  294 
  295 SYSCTL_PROC(_kern_devstat, OID_AUTO, all, CTLFLAG_RD|CTLTYPE_OPAQUE,
  296     0, 0, sysctl_devstat, "S,devstat", "All devices in the devstat list");
  297 /*
  298  * Export the number of devices in the system so that userland utilities
  299  * can determine how much memory to allocate to hold all the devices.
  300  */
  301 SYSCTL_INT(_kern_devstat, OID_AUTO, numdevs, CTLFLAG_RD, 
  302     &devstat_num_devs, 0, "Number of devices in the devstat list");
  303 SYSCTL_LONG(_kern_devstat, OID_AUTO, generation, CTLFLAG_RD,
  304     &devstat_generation, 0, "Devstat list generation");
  305 SYSCTL_INT(_kern_devstat, OID_AUTO, version, CTLFLAG_RD, 
  306     &devstat_version, 0, "Devstat list version number");
Cache object: e9355837911f59b90099cd76c265576b
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FreeBSD/Linux Kernel Cross Reference sys/kern/subr_devstat.c

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