2 * Copyright (c) 1997, 1998, 1999 Kenneth D. Merry.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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.
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
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
32 #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 *");
52 SDT_PROBE_DEFINE2(io, , , wait__start, "struct bio *",
54 SDT_PROBE_DEFINE2(io, , , wait__done, "struct bio *",
57 #define DTRACE_DEVSTAT_START() SDT_PROBE2(io, , , start, NULL, ds)
58 #define DTRACE_DEVSTAT_BIO_START() SDT_PROBE2(io, , , start, bp, ds)
59 #define DTRACE_DEVSTAT_DONE() SDT_PROBE2(io, , , done, NULL, ds)
60 #define DTRACE_DEVSTAT_BIO_DONE() SDT_PROBE2(io, , , done, bp, ds)
61 #define DTRACE_DEVSTAT_WAIT_START() SDT_PROBE2(io, , , wait__start, NULL, ds)
62 #define DTRACE_DEVSTAT_WAIT_DONE() SDT_PROBE2(io, , , wait__done, NULL, ds)
64 static int devstat_num_devs;
65 static long devstat_generation = 1;
66 static int devstat_version = DEVSTAT_VERSION;
67 static int devstat_current_devnumber;
68 static struct mtx devstat_mutex;
69 MTX_SYSINIT(devstat_mutex, &devstat_mutex, "devstat", MTX_DEF);
71 static struct devstatlist device_statq = STAILQ_HEAD_INITIALIZER(device_statq);
72 static struct devstat *devstat_alloc(void);
73 static void devstat_free(struct devstat *);
74 static void devstat_add_entry(struct devstat *ds, const void *dev_name,
75 int unit_number, uint32_t block_size,
76 devstat_support_flags flags,
77 devstat_type_flags device_type,
78 devstat_priority priority);
81 * Allocate a devstat and initialize it
84 devstat_new_entry(const void *dev_name,
85 int unit_number, uint32_t block_size,
86 devstat_support_flags flags,
87 devstat_type_flags device_type,
88 devstat_priority priority)
92 mtx_assert(&devstat_mutex, MA_NOTOWNED);
95 mtx_lock(&devstat_mutex);
96 if (unit_number == -1) {
97 ds->unit_number = unit_number;
99 binuptime(&ds->creation_time);
100 devstat_generation++;
102 devstat_add_entry(ds, dev_name, unit_number, block_size,
103 flags, device_type, priority);
105 mtx_unlock(&devstat_mutex);
110 * Take a malloced and zeroed devstat structure given to us, fill it in
111 * and add it to the queue of devices.
114 devstat_add_entry(struct devstat *ds, const void *dev_name,
115 int unit_number, uint32_t block_size,
116 devstat_support_flags flags,
117 devstat_type_flags device_type,
118 devstat_priority priority)
120 struct devstatlist *devstat_head;
121 struct devstat *ds_tmp;
123 mtx_assert(&devstat_mutex, MA_OWNED);
126 devstat_head = &device_statq;
129 * Priority sort. Each driver passes in its priority when it adds
130 * its devstat entry. Drivers are sorted first by priority, and
131 * then by probe order.
133 * For the first device, we just insert it, since the priority
134 * doesn't really matter yet. Subsequent devices are inserted into
135 * the list using the order outlined above.
137 if (devstat_num_devs == 1)
138 STAILQ_INSERT_TAIL(devstat_head, ds, dev_links);
140 STAILQ_FOREACH(ds_tmp, devstat_head, dev_links) {
141 struct devstat *ds_next;
143 ds_next = STAILQ_NEXT(ds_tmp, dev_links);
146 * If we find a break between higher and lower
147 * priority items, and if this item fits in the
148 * break, insert it. This also applies if the
149 * "lower priority item" is the end of the list.
151 if ((priority <= ds_tmp->priority)
152 && ((ds_next == NULL)
153 || (priority > ds_next->priority))) {
154 STAILQ_INSERT_AFTER(devstat_head, ds_tmp, ds,
157 } else if (priority > ds_tmp->priority) {
159 * If this is the case, we should be able
160 * to insert ourselves at the head of the
161 * list. If we can't, something is wrong.
163 if (ds_tmp == STAILQ_FIRST(devstat_head)) {
164 STAILQ_INSERT_HEAD(devstat_head,
168 STAILQ_INSERT_TAIL(devstat_head,
170 printf("devstat_add_entry: HELP! "
171 "sorting problem detected "
172 "for name %p unit %d\n",
173 dev_name, unit_number);
180 ds->device_number = devstat_current_devnumber++;
181 ds->unit_number = unit_number;
182 strlcpy(ds->device_name, dev_name, DEVSTAT_NAME_LEN);
183 ds->block_size = block_size;
185 ds->device_type = device_type;
186 ds->priority = priority;
187 binuptime(&ds->creation_time);
188 devstat_generation++;
192 * Remove a devstat structure from the list of devices.
195 devstat_remove_entry(struct devstat *ds)
197 struct devstatlist *devstat_head;
199 mtx_assert(&devstat_mutex, MA_NOTOWNED);
203 mtx_lock(&devstat_mutex);
205 devstat_head = &device_statq;
207 /* Remove this entry from the devstat queue */
208 atomic_add_acq_int(&ds->sequence1, 1);
209 if (ds->unit_number != -1) {
211 STAILQ_REMOVE(devstat_head, ds, devstat, dev_links);
214 devstat_generation++;
215 mtx_unlock(&devstat_mutex);
219 * Record a transaction start.
221 * See comments for devstat_end_transaction(). Ordering is very important
225 devstat_start_transaction(struct devstat *ds, struct bintime *now)
228 mtx_assert(&devstat_mutex, MA_NOTOWNED);
234 atomic_add_acq_int(&ds->sequence1, 1);
236 * We only want to set the start time when we are going from idle
237 * to busy. The start time is really the start of the latest busy
240 if (ds->start_count == ds->end_count) {
242 ds->busy_from = *now;
244 binuptime(&ds->busy_from);
247 atomic_add_rel_int(&ds->sequence0, 1);
248 DTRACE_DEVSTAT_START();
252 devstat_start_transaction_bio(struct devstat *ds, struct bio *bp)
255 mtx_assert(&devstat_mutex, MA_NOTOWNED);
261 binuptime(&bp->bio_t0);
262 devstat_start_transaction(ds, &bp->bio_t0);
263 DTRACE_DEVSTAT_BIO_START();
267 * Record the ending of a transaction, and incrment the various counters.
269 * Ordering in this function, and in devstat_start_transaction() is VERY
270 * important. The idea here is to run without locks, so we are very
271 * careful to only modify some fields on the way "down" (i.e. at
272 * transaction start) and some fields on the way "up" (i.e. at transaction
273 * completion). One exception is busy_from, which we only modify in
274 * devstat_start_transaction() when there are no outstanding transactions,
275 * and thus it can't be modified in devstat_end_transaction()
278 * The sequence0 and sequence1 fields are provided to enable an application
279 * spying on the structures with mmap(2) to tell when a structure is in a
280 * consistent state or not.
282 * For this to work 100% reliably, it is important that the two fields
283 * are at opposite ends of the structure and that they are incremented
284 * in the opposite order of how a memcpy(3) in userland would copy them.
285 * We assume that the copying happens front to back, but there is actually
286 * no way short of writing your own memcpy(3) replacement to guarantee
287 * this will be the case.
289 * In addition to this, being a kind of locks, they must be updated with
290 * atomic instructions using appropriate memory barriers.
293 devstat_end_transaction(struct devstat *ds, uint32_t bytes,
294 devstat_tag_type tag_type, devstat_trans_flags flags,
295 struct bintime *now, struct bintime *then)
297 struct bintime dt, lnow;
308 atomic_add_acq_int(&ds->sequence1, 1);
309 /* Update byte and operations counts */
310 ds->bytes[flags] += bytes;
311 ds->operations[flags]++;
314 * Keep a count of the various tag types sent.
316 if ((ds->flags & DEVSTAT_NO_ORDERED_TAGS) == 0 &&
317 tag_type != DEVSTAT_TAG_NONE)
318 ds->tag_types[tag_type]++;
321 /* Update duration of operations */
323 bintime_sub(&dt, then);
324 bintime_add(&ds->duration[flags], &dt);
327 /* Accumulate busy time */
329 bintime_sub(&dt, &ds->busy_from);
330 bintime_add(&ds->busy_time, &dt);
331 ds->busy_from = *now;
334 atomic_add_rel_int(&ds->sequence0, 1);
335 DTRACE_DEVSTAT_DONE();
339 devstat_end_transaction_bio(struct devstat *ds, struct bio *bp)
342 devstat_end_transaction_bio_bt(ds, bp, NULL);
346 devstat_end_transaction_bio_bt(struct devstat *ds, struct bio *bp,
349 devstat_trans_flags flg;
355 if (bp->bio_cmd == BIO_DELETE)
357 else if (bp->bio_cmd == BIO_READ)
359 else if (bp->bio_cmd == BIO_WRITE)
362 flg = DEVSTAT_NO_DATA;
364 devstat_end_transaction(ds, bp->bio_bcount - bp->bio_resid,
365 DEVSTAT_TAG_SIMPLE, flg, now, &bp->bio_t0);
366 DTRACE_DEVSTAT_BIO_DONE();
370 * This is the sysctl handler for the devstat package. The data pushed out
371 * on the kern.devstat.all sysctl variable consists of the current devstat
372 * generation number, and then an array of devstat structures, one for each
373 * device in the system.
375 * This is more cryptic that obvious, but basically we neither can nor
376 * want to hold the devstat_mutex for any amount of time, so we grab it
377 * only when we need to and keep an eye on devstat_generation all the time.
380 sysctl_devstat(SYSCTL_HANDLER_ARGS)
386 mtx_assert(&devstat_mutex, MA_NOTOWNED);
389 * XXX devstat_generation should really be "volatile" but that
390 * XXX freaks out the sysctl macro below. The places where we
391 * XXX change it and inspect it are bracketed in the mutex which
392 * XXX guarantees us proper write barriers. I don't belive the
393 * XXX compiler is allowed to optimize mygen away across calls
394 * XXX to other functions, so the following is belived to be safe.
396 mygen = devstat_generation;
398 error = SYSCTL_OUT(req, &mygen, sizeof(mygen));
400 if (devstat_num_devs == 0)
406 mtx_lock(&devstat_mutex);
407 nds = STAILQ_FIRST(&device_statq);
408 if (mygen != devstat_generation)
410 mtx_unlock(&devstat_mutex);
415 for (;nds != NULL;) {
416 error = SYSCTL_OUT(req, nds, sizeof(struct devstat));
419 mtx_lock(&devstat_mutex);
420 if (mygen != devstat_generation)
423 nds = STAILQ_NEXT(nds, dev_links);
424 mtx_unlock(&devstat_mutex);
432 * Sysctl entries for devstat. The first one is a node that all the rest
435 static SYSCTL_NODE(_kern, OID_AUTO, devstat, CTLFLAG_RD, NULL,
436 "Device Statistics");
438 SYSCTL_PROC(_kern_devstat, OID_AUTO, all, CTLFLAG_RD|CTLTYPE_OPAQUE,
439 NULL, 0, sysctl_devstat, "S,devstat", "All devices in the devstat list");
441 * Export the number of devices in the system so that userland utilities
442 * can determine how much memory to allocate to hold all the devices.
444 SYSCTL_INT(_kern_devstat, OID_AUTO, numdevs, CTLFLAG_RD,
445 &devstat_num_devs, 0, "Number of devices in the devstat list");
446 SYSCTL_LONG(_kern_devstat, OID_AUTO, generation, CTLFLAG_RD,
447 &devstat_generation, 0, "Devstat list generation");
448 SYSCTL_INT(_kern_devstat, OID_AUTO, version, CTLFLAG_RD,
449 &devstat_version, 0, "Devstat list version number");
452 * Allocator for struct devstat structures. We sub-allocate these from pages
453 * which we get from malloc. These pages are exported for mmap(2)'ing through
454 * a miniature device driver
457 #define statsperpage (PAGE_SIZE / sizeof(struct devstat))
459 static d_mmap_t devstat_mmap;
461 static struct cdevsw devstat_cdevsw = {
462 .d_version = D_VERSION,
463 .d_mmap = devstat_mmap,
468 TAILQ_ENTRY(statspage) list;
469 struct devstat *stat;
473 static TAILQ_HEAD(, statspage) pagelist = TAILQ_HEAD_INITIALIZER(pagelist);
474 static MALLOC_DEFINE(M_DEVSTAT, "devstat", "Device statistics");
477 devstat_mmap(struct cdev *dev, vm_ooffset_t offset, vm_paddr_t *paddr,
478 int nprot, vm_memattr_t *memattr)
480 struct statspage *spp;
482 if (nprot != VM_PROT_READ)
484 mtx_lock(&devstat_mutex);
485 TAILQ_FOREACH(spp, &pagelist, list) {
487 *paddr = vtophys(spp->stat);
488 mtx_unlock(&devstat_mutex);
493 mtx_unlock(&devstat_mutex);
497 static struct devstat *
501 struct statspage *spp, *spp2;
505 mtx_assert(&devstat_mutex, MA_NOTOWNED);
507 make_dev_credf(MAKEDEV_ETERNAL | MAKEDEV_CHECKNAME,
508 &devstat_cdevsw, 0, NULL, UID_ROOT, GID_WHEEL, 0444,
509 DEVSTAT_DEVICE_NAME);
513 mtx_lock(&devstat_mutex);
515 TAILQ_FOREACH(spp, &pagelist, list) {
521 mtx_unlock(&devstat_mutex);
522 spp2 = malloc(sizeof *spp, M_DEVSTAT, M_ZERO | M_WAITOK);
523 spp2->stat = malloc(PAGE_SIZE, M_DEVSTAT, M_ZERO | M_WAITOK);
524 spp2->nfree = statsperpage;
527 * If free statspages were added while the lock was released
530 mtx_lock(&devstat_mutex);
531 TAILQ_FOREACH(spp, &pagelist, list)
538 * It would make more sense to add the new page at the
539 * head but the order on the list determine the
540 * sequence of the mapping so we can't do that.
542 TAILQ_INSERT_TAIL(&pagelist, spp, list);
547 for (u = 0; u < statsperpage; u++) {
548 if (dsp->allocated == 0)
554 mtx_unlock(&devstat_mutex);
555 if (spp2 != NULL && spp2 != spp) {
556 free(spp2->stat, M_DEVSTAT);
557 free(spp2, M_DEVSTAT);
563 devstat_free(struct devstat *dsp)
565 struct statspage *spp;
567 mtx_assert(&devstat_mutex, MA_OWNED);
568 bzero(dsp, sizeof *dsp);
569 TAILQ_FOREACH(spp, &pagelist, list) {
570 if (dsp >= spp->stat && dsp < (spp->stat + statsperpage)) {
577 SYSCTL_INT(_debug_sizeof, OID_AUTO, devstat, CTLFLAG_RD,
578 SYSCTL_NULL_INT_PTR, sizeof(struct devstat), "sizeof(struct devstat)");