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: src/sys/kern/subr_devstat.c,v 1.17.2.2 2000/08/03 00:09:32 ps Exp $
   29  * $DragonFly: src/sys/kern/subr_devstat.c,v 1.4 2006/12/23 00:35:04 swildner Exp $
   30  */
   31 
   32 #include <sys/param.h>
   33 #include <sys/kernel.h>
   34 #include <sys/systm.h>
   35 #include <sys/buf.h>
   36 #include <sys/sysctl.h>
   37 
   38 #include <sys/devicestat.h>
   39 
   40 static int devstat_num_devs;
   41 static long devstat_generation;
   42 static int devstat_version = DEVSTAT_VERSION;
   43 static int devstat_current_devnumber;
   44 
   45 static STAILQ_HEAD(devstatlist, devstat) device_statq;
   46 
   47 /*
   48  * Take a malloced and zeroed devstat structure given to us, fill it in 
   49  * and add it to the queue of devices.  
   50  */
   51 void
   52 devstat_add_entry(struct devstat *ds, const char *dev_name, 
   53                   int unit_number, u_int32_t block_size,
   54                   devstat_support_flags flags,
   55                   devstat_type_flags device_type,
   56                   devstat_priority priority)
   57 {
   58         struct devstatlist *devstat_head;
   59         struct devstat *ds_tmp;
   60 
   61         if (ds == NULL)
   62                 return;
   63 
   64         if (devstat_num_devs == 0)
   65                 STAILQ_INIT(&device_statq);
   66 
   67         devstat_generation++;
   68         devstat_num_devs++;
   69 
   70         devstat_head = &device_statq;
   71 
   72         /*
   73          * Priority sort.  Each driver passes in its priority when it adds
   74          * its devstat entry.  Drivers are sorted first by priority, and
   75          * then by probe order.
   76          * 
   77          * For the first device, we just insert it, since the priority
   78          * doesn't really matter yet.  Subsequent devices are inserted into
   79          * the list using the order outlined above.
   80          */
   81         if (devstat_num_devs == 1)
   82                 STAILQ_INSERT_TAIL(devstat_head, ds, dev_links);
   83         else {
   84                 for (ds_tmp = STAILQ_FIRST(devstat_head); ds_tmp != NULL;
   85                      ds_tmp = STAILQ_NEXT(ds_tmp, dev_links)) {
   86                         struct devstat *ds_next;
   87 
   88                         ds_next = STAILQ_NEXT(ds_tmp, dev_links);
   89 
   90                         /*
   91                          * If we find a break between higher and lower
   92                          * priority items, and if this item fits in the
   93                          * break, insert it.  This also applies if the
   94                          * "lower priority item" is the end of the list.
   95                          */
   96                         if ((priority <= ds_tmp->priority)
   97                          && ((ds_next == NULL)
   98                            || (priority > ds_next->priority))) {
   99                                 STAILQ_INSERT_AFTER(devstat_head, ds_tmp, ds,
  100                                                     dev_links);
  101                                 break;
  102                         } else if (priority > ds_tmp->priority) {
  103                                 /*
  104                                  * If this is the case, we should be able
  105                                  * to insert ourselves at the head of the
  106                                  * list.  If we can't, something is wrong.
  107                                  */
  108                                 if (ds_tmp == STAILQ_FIRST(devstat_head)) {
  109                                         STAILQ_INSERT_HEAD(devstat_head,
  110                                                            ds, dev_links);
  111                                         break;
  112                                 } else {
  113                                         STAILQ_INSERT_TAIL(devstat_head,
  114                                                            ds, dev_links);
  115                                         kprintf("devstat_add_entry: HELP! "
  116                                                "sorting problem detected "
  117                                                "for %s%d\n", dev_name,
  118                                                unit_number);
  119                                         break;
  120                                 }
  121                         }
  122                 }
  123         }
  124 
  125         ds->device_number = devstat_current_devnumber++;
  126         ds->unit_number = unit_number;
  127         strncpy(ds->device_name, dev_name, DEVSTAT_NAME_LEN);
  128         ds->device_name[DEVSTAT_NAME_LEN - 1] = '\0';
  129         ds->block_size = block_size;
  130         ds->flags = flags;
  131         ds->device_type = device_type;
  132         ds->priority = priority;
  133         getmicrotime(&ds->dev_creation_time);
  134 }
  135 
  136 /*
  137  * Remove a devstat structure from the list of devices.
  138  */
  139 void
  140 devstat_remove_entry(struct devstat *ds)
  141 {
  142         struct devstatlist *devstat_head;
  143 
  144         if (ds == NULL)
  145                 return;
  146 
  147         devstat_generation++;
  148         devstat_num_devs--;
  149 
  150         devstat_head = &device_statq;
  151 
  152         /* Remove this entry from the devstat queue */
  153         STAILQ_REMOVE(devstat_head, ds, devstat, dev_links);
  154 }
  155 
  156 /*
  157  * Record a transaction start.
  158  */
  159 void
  160 devstat_start_transaction(struct devstat *ds)
  161 {
  162         /* sanity check */
  163         if (ds == NULL)
  164                 return;
  165 
  166         /*
  167          * We only want to set the start time when we are going from idle
  168          * to busy.  The start time is really the start of the latest busy
  169          * period.
  170          */
  171         if (atomic_fetchadd_int(&ds->busy_count, 1) == 0)
  172                 getmicrouptime(&ds->start_time);
  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         int busy_count;
  184 
  185         /* sanity check */
  186         if (ds == NULL)
  187                 return;
  188 
  189         getmicrouptime(&ds->last_comp_time);
  190         busy_count = atomic_fetchadd_int(&ds->busy_count, -1) - 1;
  191 
  192         /*
  193          * There might be some transactions (DEVSTAT_NO_DATA) that don't
  194          * transfer any data.
  195          */
  196         if (flags == DEVSTAT_READ) {
  197                 ds->bytes_read += bytes;
  198                 ds->num_reads++;
  199         } else if (flags == DEVSTAT_WRITE) {
  200                 ds->bytes_written += bytes;
  201                 ds->num_writes++;
  202         } else if (flags == DEVSTAT_FREE) {
  203                 ds->bytes_freed += bytes;
  204                 ds->num_frees++;
  205         } else
  206                 ds->num_other++;
  207 
  208         /*
  209          * Keep a count of the various tag types sent.
  210          */
  211         if ((ds->flags & DEVSTAT_NO_ORDERED_TAGS) == 0 &&
  212             tag_type != DEVSTAT_TAG_NONE)
  213                 ds->tag_types[tag_type]++;
  214 
  215         /*
  216          * We only update the busy time when we go idle.  Otherwise, this
  217          * calculation would require many more clock cycles.
  218          */
  219         if (busy_count == 0) {
  220                 /* Calculate how long we were busy */
  221                 busy_time = ds->last_comp_time;
  222                 timevalsub(&busy_time, &ds->start_time);
  223 
  224                 /* Add our busy time to the total busy time. */
  225                 timevaladd(&ds->busy_time, &busy_time);
  226         } else if (busy_count < 0) {
  227                 kprintf("devstat_end_transaction: HELP!! busy_count "
  228                        "for %s%d is < 0 (%d)!\n", ds->device_name,
  229                        ds->unit_number, ds->busy_count);
  230         }
  231 }
  232 
  233 void
  234 devstat_end_transaction_buf(struct devstat *ds, struct buf *bp)
  235 {
  236         devstat_trans_flags flg;
  237 
  238         switch(bp->b_cmd) {
  239         case BUF_CMD_FREEBLKS:
  240                 flg = DEVSTAT_FREE;
  241                 break;
  242         case BUF_CMD_READ:
  243                 flg = DEVSTAT_READ;
  244                 break;
  245         default:
  246                 flg = DEVSTAT_WRITE;
  247                 break;
  248         }
  249         devstat_end_transaction(ds, bp->b_bcount - bp->b_resid,
  250                                 (bp->b_flags & B_ORDERED) ?
  251                                 DEVSTAT_TAG_ORDERED : DEVSTAT_TAG_SIMPLE, flg);
  252 }
  253 
  254 /*
  255  * This is the sysctl handler for the devstat package.  The data pushed out
  256  * on the kern.devstat.all sysctl variable consists of the current devstat
  257  * generation number, and then an array of devstat structures, one for each
  258  * device in the system.
  259  *
  260  * I'm really not too fond of this method of doing things, but there really
  261  * aren't that many alternatives.  We must have some method of making sure
  262  * that the generation number the user gets corresponds with the data the
  263  * user gets.  If the user makes a separate sysctl call to get the
  264  * generation, and then a sysctl call to get the device statistics, the
  265  * device list could have changed in that brief period of time.  By
  266  * supplying the generation number along with the statistics output, we can
  267  * guarantee that the generation number and the statistics match up.
  268  */
  269 static int
  270 sysctl_devstat(SYSCTL_HANDLER_ARGS)
  271 {
  272         int error, i;
  273         struct devstat *nds;
  274         struct devstatlist *devstat_head;
  275 
  276         if (devstat_num_devs == 0)
  277                 return(EINVAL);
  278 
  279         error = 0;
  280         devstat_head = &device_statq;
  281 
  282         /*
  283          * First push out the generation number.
  284          */
  285         error = SYSCTL_OUT(req, &devstat_generation, sizeof(long));
  286 
  287         /*
  288          * Now push out all the devices.
  289          */
  290         for (i = 0, nds = STAILQ_FIRST(devstat_head); 
  291             (nds != NULL) && (i < devstat_num_devs) && (error == 0); 
  292              nds = STAILQ_NEXT(nds, dev_links), i++)
  293                 error = SYSCTL_OUT(req, nds, sizeof(struct devstat));
  294 
  295         return(error);
  296 }
  297 
  298 /*
  299  * Sysctl entries for devstat.  The first one is a node that all the rest
  300  * hang off of. 
  301  */
  302 SYSCTL_NODE(_kern, OID_AUTO, devstat, CTLFLAG_RD, 0, "Device Statistics");
  303 
  304 SYSCTL_PROC(_kern_devstat, OID_AUTO, all, CTLFLAG_RD|CTLTYPE_OPAQUE,
  305     0, 0, sysctl_devstat, "S,devstat", "All devices in the devstat list");
  306 /*
  307  * Export the number of devices in the system so that userland utilities
  308  * can determine how much memory to allocate to hold all the devices.
  309  */
  310 SYSCTL_INT(_kern_devstat, OID_AUTO, numdevs, CTLFLAG_RD, 
  311     &devstat_num_devs, 0, "Number of devices in the devstat list");
  312 SYSCTL_LONG(_kern_devstat, OID_AUTO, generation, CTLFLAG_RD,
  313     &devstat_generation, 0, "Devstat list generation");
  314 SYSCTL_INT(_kern_devstat, OID_AUTO, version, CTLFLAG_RD, 
  315     &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
