2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1997, 1998, 1999 Kenneth D. Merry.
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. The name of the author may not be used to endorse or promote products
16 * derived from this software without specific prior written permission.
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 #include <sys/param.h>
33 #include <sys/kernel.h>
34 #include <sys/systm.h>
36 #include <sys/devicestat.h>
38 #include <sys/sysctl.h>
39 #include <sys/malloc.h>
41 #include <sys/mutex.h>
46 #include <machine/atomic.h>
48 SDT_PROVIDER_DEFINE(io);
50 SDT_PROBE_DEFINE2(io, , , start, "struct bio *", "struct devstat *");
51 SDT_PROBE_DEFINE2(io, , , done, "struct bio *", "struct devstat *");
53 #define DTRACE_DEVSTAT_BIO_START() SDT_PROBE2(io, , , start, bp, ds)
54 #define DTRACE_DEVSTAT_BIO_DONE() SDT_PROBE2(io, , , done, bp, ds)
56 static int devstat_num_devs;
57 static long devstat_generation = 1;
58 static int devstat_version = DEVSTAT_VERSION;
59 static int devstat_current_devnumber;
60 static struct mtx devstat_mutex;
61 MTX_SYSINIT(devstat_mutex, &devstat_mutex, "devstat", MTX_DEF);
63 static struct devstatlist device_statq = STAILQ_HEAD_INITIALIZER(device_statq);
64 static struct devstat *devstat_alloc(void);
65 static void devstat_free(struct devstat *);
66 static void devstat_add_entry(struct devstat *ds, const void *dev_name,
67 int unit_number, uint32_t block_size,
68 devstat_support_flags flags,
69 devstat_type_flags device_type,
70 devstat_priority priority);
73 * Allocate a devstat and initialize it
76 devstat_new_entry(const void *dev_name,
77 int unit_number, uint32_t block_size,
78 devstat_support_flags flags,
79 devstat_type_flags device_type,
80 devstat_priority priority)
84 mtx_assert(&devstat_mutex, MA_NOTOWNED);
87 mtx_lock(&devstat_mutex);
88 if (unit_number == -1) {
89 ds->unit_number = unit_number;
91 binuptime(&ds->creation_time);
94 devstat_add_entry(ds, dev_name, unit_number, block_size,
95 flags, device_type, priority);
97 mtx_unlock(&devstat_mutex);
102 * Take a malloced and zeroed devstat structure given to us, fill it in
103 * and add it to the queue of devices.
106 devstat_add_entry(struct devstat *ds, const void *dev_name,
107 int unit_number, uint32_t block_size,
108 devstat_support_flags flags,
109 devstat_type_flags device_type,
110 devstat_priority priority)
112 struct devstatlist *devstat_head;
113 struct devstat *ds_tmp;
115 mtx_assert(&devstat_mutex, MA_OWNED);
118 devstat_head = &device_statq;
121 * Priority sort. Each driver passes in its priority when it adds
122 * its devstat entry. Drivers are sorted first by priority, and
123 * then by probe order.
125 * For the first device, we just insert it, since the priority
126 * doesn't really matter yet. Subsequent devices are inserted into
127 * the list using the order outlined above.
129 if (devstat_num_devs == 1)
130 STAILQ_INSERT_TAIL(devstat_head, ds, dev_links);
132 STAILQ_FOREACH(ds_tmp, devstat_head, dev_links) {
133 struct devstat *ds_next;
135 ds_next = STAILQ_NEXT(ds_tmp, dev_links);
138 * If we find a break between higher and lower
139 * priority items, and if this item fits in the
140 * break, insert it. This also applies if the
141 * "lower priority item" is the end of the list.
143 if ((priority <= ds_tmp->priority)
144 && ((ds_next == NULL)
145 || (priority > ds_next->priority))) {
146 STAILQ_INSERT_AFTER(devstat_head, ds_tmp, ds,
149 } else if (priority > ds_tmp->priority) {
151 * If this is the case, we should be able
152 * to insert ourselves at the head of the
153 * list. If we can't, something is wrong.
155 if (ds_tmp == STAILQ_FIRST(devstat_head)) {
156 STAILQ_INSERT_HEAD(devstat_head,
160 STAILQ_INSERT_TAIL(devstat_head,
162 printf("devstat_add_entry: HELP! "
163 "sorting problem detected "
164 "for name %p unit %d\n",
165 dev_name, unit_number);
172 ds->device_number = devstat_current_devnumber++;
173 ds->unit_number = unit_number;
174 strlcpy(ds->device_name, dev_name, DEVSTAT_NAME_LEN);
175 ds->block_size = block_size;
177 ds->device_type = device_type;
178 ds->priority = priority;
179 binuptime(&ds->creation_time);
180 devstat_generation++;
184 * Remove a devstat structure from the list of devices.
187 devstat_remove_entry(struct devstat *ds)
189 struct devstatlist *devstat_head;
191 mtx_assert(&devstat_mutex, MA_NOTOWNED);
195 mtx_lock(&devstat_mutex);
197 devstat_head = &device_statq;
199 /* Remove this entry from the devstat queue */
200 atomic_add_acq_int(&ds->sequence1, 1);
201 if (ds->unit_number != -1) {
203 STAILQ_REMOVE(devstat_head, ds, devstat, dev_links);
206 devstat_generation++;
207 mtx_unlock(&devstat_mutex);
211 * Record a transaction start.
213 * See comments for devstat_end_transaction(). Ordering is very important
217 devstat_start_transaction(struct devstat *ds, const struct bintime *now)
224 atomic_add_acq_int(&ds->sequence1, 1);
226 * We only want to set the start time when we are going from idle
227 * to busy. The start time is really the start of the latest busy
230 if (atomic_fetchadd_int(&ds->start_count, 1) == ds->end_count) {
232 ds->busy_from = *now;
234 binuptime(&ds->busy_from);
236 atomic_add_rel_int(&ds->sequence0, 1);
240 devstat_start_transaction_bio(struct devstat *ds, struct bio *bp)
247 binuptime(&bp->bio_t0);
248 devstat_start_transaction_bio_t0(ds, bp);
252 devstat_start_transaction_bio_t0(struct devstat *ds, struct bio *bp)
259 devstat_start_transaction(ds, &bp->bio_t0);
260 DTRACE_DEVSTAT_BIO_START();
264 * Record the ending of a transaction, and incrment the various counters.
266 * Ordering in this function, and in devstat_start_transaction() is VERY
267 * important. The idea here is to run without locks, so we are very
268 * careful to only modify some fields on the way "down" (i.e. at
269 * transaction start) and some fields on the way "up" (i.e. at transaction
270 * completion). One exception is busy_from, which we only modify in
271 * devstat_start_transaction() when there are no outstanding transactions,
272 * and thus it can't be modified in devstat_end_transaction()
275 * The sequence0 and sequence1 fields are provided to enable an application
276 * spying on the structures with mmap(2) to tell when a structure is in a
277 * consistent state or not.
279 * For this to work 100% reliably, it is important that the two fields
280 * are at opposite ends of the structure and that they are incremented
281 * in the opposite order of how a memcpy(3) in userland would copy them.
282 * We assume that the copying happens front to back, but there is actually
283 * no way short of writing your own memcpy(3) replacement to guarantee
284 * this will be the case.
286 * In addition to this, being a kind of locks, they must be updated with
287 * atomic instructions using appropriate memory barriers.
290 devstat_end_transaction(struct devstat *ds, uint32_t bytes,
291 devstat_tag_type tag_type, devstat_trans_flags flags,
292 const struct bintime *now, const struct bintime *then)
294 struct bintime dt, lnow;
305 atomic_add_acq_int(&ds->sequence1, 1);
306 /* Update byte and operations counts */
307 ds->bytes[flags] += bytes;
308 ds->operations[flags]++;
311 * Keep a count of the various tag types sent.
313 if ((ds->flags & DEVSTAT_NO_ORDERED_TAGS) == 0 &&
314 tag_type != DEVSTAT_TAG_NONE)
315 ds->tag_types[tag_type]++;
318 /* Update duration of operations */
320 bintime_sub(&dt, then);
321 bintime_add(&ds->duration[flags], &dt);
324 /* Accumulate busy time */
326 bintime_sub(&dt, &ds->busy_from);
327 bintime_add(&ds->busy_time, &dt);
328 ds->busy_from = *now;
331 atomic_add_rel_int(&ds->sequence0, 1);
335 devstat_end_transaction_bio(struct devstat *ds, const struct bio *bp)
338 devstat_end_transaction_bio_bt(ds, bp, NULL);
342 devstat_end_transaction_bio_bt(struct devstat *ds, const struct bio *bp,
343 const struct bintime *now)
345 devstat_trans_flags flg;
346 devstat_tag_type tag;
352 if (bp->bio_flags & BIO_ORDERED)
353 tag = DEVSTAT_TAG_ORDERED;
355 tag = DEVSTAT_TAG_SIMPLE;
356 if (bp->bio_cmd == BIO_DELETE)
358 else if ((bp->bio_cmd == BIO_READ)
359 || ((bp->bio_cmd == BIO_ZONE)
360 && (bp->bio_zone.zone_cmd == DISK_ZONE_REPORT_ZONES)))
362 else if (bp->bio_cmd == BIO_WRITE)
365 flg = DEVSTAT_NO_DATA;
367 devstat_end_transaction(ds, bp->bio_bcount - bp->bio_resid,
368 tag, flg, now, &bp->bio_t0);
369 DTRACE_DEVSTAT_BIO_DONE();
373 * This is the sysctl handler for the devstat package. The data pushed out
374 * on the kern.devstat.all sysctl variable consists of the current devstat
375 * generation number, and then an array of devstat structures, one for each
376 * device in the system.
378 * This is more cryptic that obvious, but basically we neither can nor
379 * want to hold the devstat_mutex for any amount of time, so we grab it
380 * only when we need to and keep an eye on devstat_generation all the time.
383 sysctl_devstat(SYSCTL_HANDLER_ARGS)
389 mtx_assert(&devstat_mutex, MA_NOTOWNED);
392 * XXX devstat_generation should really be "volatile" but that
393 * XXX freaks out the sysctl macro below. The places where we
394 * XXX change it and inspect it are bracketed in the mutex which
395 * XXX guarantees us proper write barriers. I don't believe the
396 * XXX compiler is allowed to optimize mygen away across calls
397 * XXX to other functions, so the following is belived to be safe.
399 mygen = devstat_generation;
401 error = SYSCTL_OUT(req, &mygen, sizeof(mygen));
403 if (devstat_num_devs == 0)
409 mtx_lock(&devstat_mutex);
410 nds = STAILQ_FIRST(&device_statq);
411 if (mygen != devstat_generation)
413 mtx_unlock(&devstat_mutex);
418 for (;nds != NULL;) {
419 error = SYSCTL_OUT(req, nds, sizeof(struct devstat));
422 mtx_lock(&devstat_mutex);
423 if (mygen != devstat_generation)
426 nds = STAILQ_NEXT(nds, dev_links);
427 mtx_unlock(&devstat_mutex);
435 * Sysctl entries for devstat. The first one is a node that all the rest
438 static SYSCTL_NODE(_kern, OID_AUTO, devstat, CTLFLAG_RD | CTLFLAG_MPSAFE, NULL,
439 "Device Statistics");
441 SYSCTL_PROC(_kern_devstat, OID_AUTO, all,
442 CTLFLAG_RD | CTLTYPE_OPAQUE | CTLFLAG_MPSAFE, NULL, 0,
443 sysctl_devstat, "S,devstat",
444 "All devices in the devstat list");
446 * Export the number of devices in the system so that userland utilities
447 * can determine how much memory to allocate to hold all the devices.
449 SYSCTL_INT(_kern_devstat, OID_AUTO, numdevs, CTLFLAG_RD,
450 &devstat_num_devs, 0, "Number of devices in the devstat list");
451 SYSCTL_LONG(_kern_devstat, OID_AUTO, generation, CTLFLAG_RD,
452 &devstat_generation, 0, "Devstat list generation");
453 SYSCTL_INT(_kern_devstat, OID_AUTO, version, CTLFLAG_RD,
454 &devstat_version, 0, "Devstat list version number");
457 * Allocator for struct devstat structures. We sub-allocate these from pages
458 * which we get from malloc. These pages are exported for mmap(2)'ing through
459 * a miniature device driver
462 #define statsperpage (PAGE_SIZE / sizeof(struct devstat))
464 static d_ioctl_t devstat_ioctl;
465 static d_mmap_t devstat_mmap;
467 static struct cdevsw devstat_cdevsw = {
468 .d_version = D_VERSION,
469 .d_ioctl = devstat_ioctl,
470 .d_mmap = devstat_mmap,
475 TAILQ_ENTRY(statspage) list;
476 struct devstat *stat;
480 static size_t pagelist_pages = 0;
481 static TAILQ_HEAD(, statspage) pagelist = TAILQ_HEAD_INITIALIZER(pagelist);
482 static MALLOC_DEFINE(M_DEVSTAT, "devstat", "Device statistics");
485 devstat_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int fflag,
493 *(off_t *)data = pagelist_pages * PAGE_SIZE;
501 devstat_mmap(struct cdev *dev, vm_ooffset_t offset, vm_paddr_t *paddr,
502 int nprot, vm_memattr_t *memattr)
504 struct statspage *spp;
506 if (nprot != VM_PROT_READ)
508 mtx_lock(&devstat_mutex);
509 TAILQ_FOREACH(spp, &pagelist, list) {
511 *paddr = vtophys(spp->stat);
512 mtx_unlock(&devstat_mutex);
517 mtx_unlock(&devstat_mutex);
521 static struct devstat *
525 struct statspage *spp, *spp2;
529 mtx_assert(&devstat_mutex, MA_NOTOWNED);
531 make_dev_credf(MAKEDEV_ETERNAL | MAKEDEV_CHECKNAME,
532 &devstat_cdevsw, 0, NULL, UID_ROOT, GID_WHEEL, 0444,
533 DEVSTAT_DEVICE_NAME);
537 mtx_lock(&devstat_mutex);
539 TAILQ_FOREACH(spp, &pagelist, list) {
545 mtx_unlock(&devstat_mutex);
546 spp2 = malloc(sizeof *spp, M_DEVSTAT, M_ZERO | M_WAITOK);
547 spp2->stat = malloc(PAGE_SIZE, M_DEVSTAT, M_ZERO | M_WAITOK);
548 spp2->nfree = statsperpage;
551 * If free statspages were added while the lock was released
554 mtx_lock(&devstat_mutex);
555 TAILQ_FOREACH(spp, &pagelist, list)
562 * It would make more sense to add the new page at the
563 * head but the order on the list determine the
564 * sequence of the mapping so we can't do that.
567 TAILQ_INSERT_TAIL(&pagelist, spp, list);
572 for (u = 0; u < statsperpage; u++) {
573 if (dsp->allocated == 0)
579 mtx_unlock(&devstat_mutex);
580 if (spp2 != NULL && spp2 != spp) {
581 free(spp2->stat, M_DEVSTAT);
582 free(spp2, M_DEVSTAT);
588 devstat_free(struct devstat *dsp)
590 struct statspage *spp;
592 mtx_assert(&devstat_mutex, MA_OWNED);
593 bzero(dsp, sizeof *dsp);
594 TAILQ_FOREACH(spp, &pagelist, list) {
595 if (dsp >= spp->stat && dsp < (spp->stat + statsperpage)) {
602 SYSCTL_INT(_debug_sizeof, OID_AUTO, devstat, CTLFLAG_RD,
603 SYSCTL_NULL_INT_PTR, sizeof(struct devstat), "sizeof(struct devstat)");