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/cdefs.h>
32 #include <sys/param.h>
34 #include <sys/kernel.h>
35 #include <sys/systm.h>
37 #include <sys/devicestat.h>
39 #include <sys/sysctl.h>
40 #include <sys/malloc.h>
42 #include <sys/mutex.h>
47 #include <machine/atomic.h>
49 SDT_PROVIDER_DEFINE(io);
51 SDT_PROBE_DEFINE2(io, , , start, "struct bio *", "struct devstat *");
52 SDT_PROBE_DEFINE2(io, , , done, "struct bio *", "struct devstat *");
54 #define DTRACE_DEVSTAT_BIO_START() SDT_PROBE2(io, , , start, bp, ds)
55 #define DTRACE_DEVSTAT_BIO_DONE() SDT_PROBE2(io, , , done, bp, ds)
57 static int devstat_num_devs;
58 static long devstat_generation = 1;
59 static int devstat_version = DEVSTAT_VERSION;
60 static int devstat_current_devnumber;
61 static struct mtx devstat_mutex;
62 MTX_SYSINIT(devstat_mutex, &devstat_mutex, "devstat", MTX_DEF);
64 static struct devstatlist device_statq = STAILQ_HEAD_INITIALIZER(device_statq);
65 static struct devstat *devstat_alloc(void);
66 static void devstat_free(struct devstat *);
67 static void devstat_add_entry(struct devstat *ds, const void *dev_name,
68 int unit_number, uint32_t block_size,
69 devstat_support_flags flags,
70 devstat_type_flags device_type,
71 devstat_priority priority);
74 * Allocate a devstat and initialize it
77 devstat_new_entry(const void *dev_name,
78 int unit_number, uint32_t block_size,
79 devstat_support_flags flags,
80 devstat_type_flags device_type,
81 devstat_priority priority)
85 mtx_assert(&devstat_mutex, MA_NOTOWNED);
88 mtx_lock(&devstat_mutex);
89 if (unit_number == -1) {
90 ds->unit_number = unit_number;
92 binuptime(&ds->creation_time);
95 devstat_add_entry(ds, dev_name, unit_number, block_size,
96 flags, device_type, priority);
98 mtx_unlock(&devstat_mutex);
103 * Take a malloced and zeroed devstat structure given to us, fill it in
104 * and add it to the queue of devices.
107 devstat_add_entry(struct devstat *ds, const void *dev_name,
108 int unit_number, uint32_t block_size,
109 devstat_support_flags flags,
110 devstat_type_flags device_type,
111 devstat_priority priority)
113 struct devstatlist *devstat_head;
114 struct devstat *ds_tmp;
116 mtx_assert(&devstat_mutex, MA_OWNED);
119 devstat_head = &device_statq;
122 * Priority sort. Each driver passes in its priority when it adds
123 * its devstat entry. Drivers are sorted first by priority, and
124 * then by probe order.
126 * For the first device, we just insert it, since the priority
127 * doesn't really matter yet. Subsequent devices are inserted into
128 * the list using the order outlined above.
130 if (devstat_num_devs == 1)
131 STAILQ_INSERT_TAIL(devstat_head, ds, dev_links);
133 STAILQ_FOREACH(ds_tmp, devstat_head, dev_links) {
134 struct devstat *ds_next;
136 ds_next = STAILQ_NEXT(ds_tmp, dev_links);
139 * If we find a break between higher and lower
140 * priority items, and if this item fits in the
141 * break, insert it. This also applies if the
142 * "lower priority item" is the end of the list.
144 if ((priority <= ds_tmp->priority)
145 && ((ds_next == NULL)
146 || (priority > ds_next->priority))) {
147 STAILQ_INSERT_AFTER(devstat_head, ds_tmp, ds,
150 } else if (priority > ds_tmp->priority) {
152 * If this is the case, we should be able
153 * to insert ourselves at the head of the
154 * list. If we can't, something is wrong.
156 if (ds_tmp == STAILQ_FIRST(devstat_head)) {
157 STAILQ_INSERT_HEAD(devstat_head,
161 STAILQ_INSERT_TAIL(devstat_head,
163 printf("devstat_add_entry: HELP! "
164 "sorting problem detected "
165 "for name %p unit %d\n",
166 dev_name, unit_number);
173 ds->device_number = devstat_current_devnumber++;
174 ds->unit_number = unit_number;
175 strlcpy(ds->device_name, dev_name, DEVSTAT_NAME_LEN);
176 ds->block_size = block_size;
178 ds->device_type = device_type;
179 ds->priority = priority;
180 binuptime(&ds->creation_time);
181 devstat_generation++;
185 * Remove a devstat structure from the list of devices.
188 devstat_remove_entry(struct devstat *ds)
190 struct devstatlist *devstat_head;
192 mtx_assert(&devstat_mutex, MA_NOTOWNED);
196 mtx_lock(&devstat_mutex);
198 devstat_head = &device_statq;
200 /* Remove this entry from the devstat queue */
201 atomic_add_acq_int(&ds->sequence1, 1);
202 if (ds->unit_number != -1) {
204 STAILQ_REMOVE(devstat_head, ds, devstat, dev_links);
207 devstat_generation++;
208 mtx_unlock(&devstat_mutex);
212 * Record a transaction start.
214 * See comments for devstat_end_transaction(). Ordering is very important
218 devstat_start_transaction(struct devstat *ds, const struct bintime *now)
225 atomic_add_acq_int(&ds->sequence1, 1);
227 * We only want to set the start time when we are going from idle
228 * to busy. The start time is really the start of the latest busy
231 if (atomic_fetchadd_int(&ds->start_count, 1) == ds->end_count) {
233 ds->busy_from = *now;
235 binuptime(&ds->busy_from);
237 atomic_add_rel_int(&ds->sequence0, 1);
241 devstat_start_transaction_bio(struct devstat *ds, struct bio *bp)
248 binuptime(&bp->bio_t0);
249 devstat_start_transaction_bio_t0(ds, bp);
253 devstat_start_transaction_bio_t0(struct devstat *ds, struct bio *bp)
260 devstat_start_transaction(ds, &bp->bio_t0);
261 DTRACE_DEVSTAT_BIO_START();
265 * Record the ending of a transaction, and incrment the various counters.
267 * Ordering in this function, and in devstat_start_transaction() is VERY
268 * important. The idea here is to run without locks, so we are very
269 * careful to only modify some fields on the way "down" (i.e. at
270 * transaction start) and some fields on the way "up" (i.e. at transaction
271 * completion). One exception is busy_from, which we only modify in
272 * devstat_start_transaction() when there are no outstanding transactions,
273 * and thus it can't be modified in devstat_end_transaction()
276 * The sequence0 and sequence1 fields are provided to enable an application
277 * spying on the structures with mmap(2) to tell when a structure is in a
278 * consistent state or not.
280 * For this to work 100% reliably, it is important that the two fields
281 * are at opposite ends of the structure and that they are incremented
282 * in the opposite order of how a memcpy(3) in userland would copy them.
283 * We assume that the copying happens front to back, but there is actually
284 * no way short of writing your own memcpy(3) replacement to guarantee
285 * this will be the case.
287 * In addition to this, being a kind of locks, they must be updated with
288 * atomic instructions using appropriate memory barriers.
291 devstat_end_transaction(struct devstat *ds, uint32_t bytes,
292 devstat_tag_type tag_type, devstat_trans_flags flags,
293 const struct bintime *now, const struct bintime *then)
295 struct bintime dt, lnow;
306 atomic_add_acq_int(&ds->sequence1, 1);
307 /* Update byte and operations counts */
308 ds->bytes[flags] += bytes;
309 ds->operations[flags]++;
312 * Keep a count of the various tag types sent.
314 if ((ds->flags & DEVSTAT_NO_ORDERED_TAGS) == 0 &&
315 tag_type != DEVSTAT_TAG_NONE)
316 ds->tag_types[tag_type]++;
319 /* Update duration of operations */
321 bintime_sub(&dt, then);
322 bintime_add(&ds->duration[flags], &dt);
325 /* Accumulate busy time */
327 bintime_sub(&dt, &ds->busy_from);
328 bintime_add(&ds->busy_time, &dt);
329 ds->busy_from = *now;
332 atomic_add_rel_int(&ds->sequence0, 1);
336 devstat_end_transaction_bio(struct devstat *ds, const struct bio *bp)
339 devstat_end_transaction_bio_bt(ds, bp, NULL);
343 devstat_end_transaction_bio_bt(struct devstat *ds, const struct bio *bp,
344 const struct bintime *now)
346 devstat_trans_flags flg;
347 devstat_tag_type tag;
353 if (bp->bio_flags & BIO_ORDERED)
354 tag = DEVSTAT_TAG_ORDERED;
356 tag = DEVSTAT_TAG_SIMPLE;
357 if (bp->bio_cmd == BIO_DELETE)
359 else if ((bp->bio_cmd == BIO_READ)
360 || ((bp->bio_cmd == BIO_ZONE)
361 && (bp->bio_zone.zone_cmd == DISK_ZONE_REPORT_ZONES)))
363 else if (bp->bio_cmd == BIO_WRITE)
366 flg = DEVSTAT_NO_DATA;
368 devstat_end_transaction(ds, bp->bio_bcount - bp->bio_resid,
369 tag, flg, now, &bp->bio_t0);
370 DTRACE_DEVSTAT_BIO_DONE();
374 * This is the sysctl handler for the devstat package. The data pushed out
375 * on the kern.devstat.all sysctl variable consists of the current devstat
376 * generation number, and then an array of devstat structures, one for each
377 * device in the system.
379 * This is more cryptic that obvious, but basically we neither can nor
380 * want to hold the devstat_mutex for any amount of time, so we grab it
381 * only when we need to and keep an eye on devstat_generation all the time.
384 sysctl_devstat(SYSCTL_HANDLER_ARGS)
390 mtx_assert(&devstat_mutex, MA_NOTOWNED);
393 * XXX devstat_generation should really be "volatile" but that
394 * XXX freaks out the sysctl macro below. The places where we
395 * XXX change it and inspect it are bracketed in the mutex which
396 * XXX guarantees us proper write barriers. I don't believe the
397 * XXX compiler is allowed to optimize mygen away across calls
398 * XXX to other functions, so the following is belived to be safe.
400 mygen = devstat_generation;
402 error = SYSCTL_OUT(req, &mygen, sizeof(mygen));
404 if (devstat_num_devs == 0)
410 mtx_lock(&devstat_mutex);
411 nds = STAILQ_FIRST(&device_statq);
412 if (mygen != devstat_generation)
414 mtx_unlock(&devstat_mutex);
419 for (;nds != NULL;) {
420 error = SYSCTL_OUT(req, nds, sizeof(struct devstat));
423 mtx_lock(&devstat_mutex);
424 if (mygen != devstat_generation)
427 nds = STAILQ_NEXT(nds, dev_links);
428 mtx_unlock(&devstat_mutex);
436 * Sysctl entries for devstat. The first one is a node that all the rest
439 static SYSCTL_NODE(_kern, OID_AUTO, devstat, CTLFLAG_RD | CTLFLAG_MPSAFE, NULL,
440 "Device Statistics");
442 SYSCTL_PROC(_kern_devstat, OID_AUTO, all,
443 CTLFLAG_RD | CTLTYPE_OPAQUE | CTLFLAG_MPSAFE, NULL, 0,
444 sysctl_devstat, "S,devstat",
445 "All devices in the devstat list");
447 * Export the number of devices in the system so that userland utilities
448 * can determine how much memory to allocate to hold all the devices.
450 SYSCTL_INT(_kern_devstat, OID_AUTO, numdevs, CTLFLAG_RD,
451 &devstat_num_devs, 0, "Number of devices in the devstat list");
452 SYSCTL_LONG(_kern_devstat, OID_AUTO, generation, CTLFLAG_RD,
453 &devstat_generation, 0, "Devstat list generation");
454 SYSCTL_INT(_kern_devstat, OID_AUTO, version, CTLFLAG_RD,
455 &devstat_version, 0, "Devstat list version number");
458 * Allocator for struct devstat structures. We sub-allocate these from pages
459 * which we get from malloc. These pages are exported for mmap(2)'ing through
460 * a miniature device driver
463 #define statsperpage (PAGE_SIZE / sizeof(struct devstat))
465 static d_ioctl_t devstat_ioctl;
466 static d_mmap_t devstat_mmap;
468 static struct cdevsw devstat_cdevsw = {
469 .d_version = D_VERSION,
470 .d_ioctl = devstat_ioctl,
471 .d_mmap = devstat_mmap,
476 TAILQ_ENTRY(statspage) list;
477 struct devstat *stat;
481 static size_t pagelist_pages = 0;
482 static TAILQ_HEAD(, statspage) pagelist = TAILQ_HEAD_INITIALIZER(pagelist);
483 static MALLOC_DEFINE(M_DEVSTAT, "devstat", "Device statistics");
486 devstat_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int fflag,
494 *(off_t *)data = pagelist_pages * PAGE_SIZE;
502 devstat_mmap(struct cdev *dev, vm_ooffset_t offset, vm_paddr_t *paddr,
503 int nprot, vm_memattr_t *memattr)
505 struct statspage *spp;
507 if (nprot != VM_PROT_READ)
509 mtx_lock(&devstat_mutex);
510 TAILQ_FOREACH(spp, &pagelist, list) {
512 *paddr = vtophys(spp->stat);
513 mtx_unlock(&devstat_mutex);
518 mtx_unlock(&devstat_mutex);
522 static struct devstat *
526 struct statspage *spp, *spp2;
530 mtx_assert(&devstat_mutex, MA_NOTOWNED);
532 make_dev_credf(MAKEDEV_ETERNAL | MAKEDEV_CHECKNAME,
533 &devstat_cdevsw, 0, NULL, UID_ROOT, GID_WHEEL, 0444,
534 DEVSTAT_DEVICE_NAME);
538 mtx_lock(&devstat_mutex);
540 TAILQ_FOREACH(spp, &pagelist, list) {
546 mtx_unlock(&devstat_mutex);
547 spp2 = malloc(sizeof *spp, M_DEVSTAT, M_ZERO | M_WAITOK);
548 spp2->stat = malloc(PAGE_SIZE, M_DEVSTAT, M_ZERO | M_WAITOK);
549 spp2->nfree = statsperpage;
552 * If free statspages were added while the lock was released
555 mtx_lock(&devstat_mutex);
556 TAILQ_FOREACH(spp, &pagelist, list)
563 * It would make more sense to add the new page at the
564 * head but the order on the list determine the
565 * sequence of the mapping so we can't do that.
568 TAILQ_INSERT_TAIL(&pagelist, spp, list);
573 for (u = 0; u < statsperpage; u++) {
574 if (dsp->allocated == 0)
580 mtx_unlock(&devstat_mutex);
581 if (spp2 != NULL && spp2 != spp) {
582 free(spp2->stat, M_DEVSTAT);
583 free(spp2, M_DEVSTAT);
589 devstat_free(struct devstat *dsp)
591 struct statspage *spp;
593 mtx_assert(&devstat_mutex, MA_OWNED);
594 bzero(dsp, sizeof *dsp);
595 TAILQ_FOREACH(spp, &pagelist, list) {
596 if (dsp >= spp->stat && dsp < (spp->stat + statsperpage)) {
603 SYSCTL_INT(_debug_sizeof, OID_AUTO, devstat, CTLFLAG_RD,
604 SYSCTL_NULL_INT_PTR, sizeof(struct devstat), "sizeof(struct devstat)");