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 "opt_kdtrace.h"
34 #include <sys/param.h>
35 #include <sys/kernel.h>
36 #include <sys/systm.h>
38 #include <sys/devicestat.h>
40 #include <sys/sysctl.h>
41 #include <sys/malloc.h>
43 #include <sys/mutex.h>
48 #include <machine/atomic.h>
50 SDT_PROVIDER_DEFINE(io);
52 SDT_PROBE_DEFINE2(io, , , start, "struct bio *", "struct devstat *");
53 SDT_PROBE_DEFINE2(io, , , done, "struct bio *", "struct devstat *");
54 SDT_PROBE_DEFINE2(io, , , wait__start, "struct bio *",
56 SDT_PROBE_DEFINE2(io, , , wait__done, "struct bio *",
59 #define DTRACE_DEVSTAT_START() SDT_PROBE2(io, , , start, NULL, ds)
60 #define DTRACE_DEVSTAT_BIO_START() SDT_PROBE2(io, , , start, bp, ds)
61 #define DTRACE_DEVSTAT_DONE() SDT_PROBE2(io, , , done, NULL, ds)
62 #define DTRACE_DEVSTAT_BIO_DONE() SDT_PROBE2(io, , , done, bp, ds)
63 #define DTRACE_DEVSTAT_WAIT_START() SDT_PROBE2(io, , , wait__start, NULL, ds)
64 #define DTRACE_DEVSTAT_WAIT_DONE() SDT_PROBE2(io, , , wait__done, NULL, ds)
66 static int devstat_num_devs;
67 static long devstat_generation = 1;
68 static int devstat_version = DEVSTAT_VERSION;
69 static int devstat_current_devnumber;
70 static struct mtx devstat_mutex;
71 MTX_SYSINIT(devstat_mutex, &devstat_mutex, "devstat", MTX_DEF);
73 static struct devstatlist device_statq = STAILQ_HEAD_INITIALIZER(device_statq);
74 static struct devstat *devstat_alloc(void);
75 static void devstat_free(struct devstat *);
76 static void devstat_add_entry(struct devstat *ds, 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);
83 * Allocate a devstat and initialize it
86 devstat_new_entry(const void *dev_name,
87 int unit_number, uint32_t block_size,
88 devstat_support_flags flags,
89 devstat_type_flags device_type,
90 devstat_priority priority)
94 mtx_assert(&devstat_mutex, MA_NOTOWNED);
97 mtx_lock(&devstat_mutex);
98 if (unit_number == -1) {
100 binuptime(&ds->creation_time);
101 devstat_generation++;
103 devstat_add_entry(ds, dev_name, unit_number, block_size,
104 flags, device_type, priority);
106 mtx_unlock(&devstat_mutex);
111 * Take a malloced and zeroed devstat structure given to us, fill it in
112 * and add it to the queue of devices.
115 devstat_add_entry(struct devstat *ds, const void *dev_name,
116 int unit_number, uint32_t block_size,
117 devstat_support_flags flags,
118 devstat_type_flags device_type,
119 devstat_priority priority)
121 struct devstatlist *devstat_head;
122 struct devstat *ds_tmp;
124 mtx_assert(&devstat_mutex, MA_OWNED);
127 devstat_head = &device_statq;
130 * Priority sort. Each driver passes in its priority when it adds
131 * its devstat entry. Drivers are sorted first by priority, and
132 * then by probe order.
134 * For the first device, we just insert it, since the priority
135 * doesn't really matter yet. Subsequent devices are inserted into
136 * the list using the order outlined above.
138 if (devstat_num_devs == 1)
139 STAILQ_INSERT_TAIL(devstat_head, ds, dev_links);
141 STAILQ_FOREACH(ds_tmp, devstat_head, dev_links) {
142 struct devstat *ds_next;
144 ds_next = STAILQ_NEXT(ds_tmp, dev_links);
147 * If we find a break between higher and lower
148 * priority items, and if this item fits in the
149 * break, insert it. This also applies if the
150 * "lower priority item" is the end of the list.
152 if ((priority <= ds_tmp->priority)
153 && ((ds_next == NULL)
154 || (priority > ds_next->priority))) {
155 STAILQ_INSERT_AFTER(devstat_head, ds_tmp, ds,
158 } else if (priority > ds_tmp->priority) {
160 * If this is the case, we should be able
161 * to insert ourselves at the head of the
162 * list. If we can't, something is wrong.
164 if (ds_tmp == STAILQ_FIRST(devstat_head)) {
165 STAILQ_INSERT_HEAD(devstat_head,
169 STAILQ_INSERT_TAIL(devstat_head,
171 printf("devstat_add_entry: HELP! "
172 "sorting problem detected "
173 "for name %p unit %d\n",
174 dev_name, unit_number);
181 ds->device_number = devstat_current_devnumber++;
182 ds->unit_number = unit_number;
183 strlcpy(ds->device_name, dev_name, DEVSTAT_NAME_LEN);
184 ds->block_size = block_size;
186 ds->device_type = device_type;
187 ds->priority = priority;
188 binuptime(&ds->creation_time);
189 devstat_generation++;
193 * Remove a devstat structure from the list of devices.
196 devstat_remove_entry(struct devstat *ds)
198 struct devstatlist *devstat_head;
200 mtx_assert(&devstat_mutex, MA_NOTOWNED);
204 mtx_lock(&devstat_mutex);
206 devstat_head = &device_statq;
208 /* Remove this entry from the devstat queue */
209 atomic_add_acq_int(&ds->sequence1, 1);
210 if (ds->id == NULL) {
212 STAILQ_REMOVE(devstat_head, ds, devstat, dev_links);
215 devstat_generation++;
216 mtx_unlock(&devstat_mutex);
220 * Record a transaction start.
222 * See comments for devstat_end_transaction(). Ordering is very important
226 devstat_start_transaction(struct devstat *ds, struct bintime *now)
229 mtx_assert(&devstat_mutex, MA_NOTOWNED);
235 atomic_add_acq_int(&ds->sequence1, 1);
237 * We only want to set the start time when we are going from idle
238 * to busy. The start time is really the start of the latest busy
241 if (ds->start_count == ds->end_count) {
243 ds->busy_from = *now;
245 binuptime(&ds->busy_from);
248 atomic_add_rel_int(&ds->sequence0, 1);
249 DTRACE_DEVSTAT_START();
253 devstat_start_transaction_bio(struct devstat *ds, struct bio *bp)
256 mtx_assert(&devstat_mutex, MA_NOTOWNED);
262 binuptime(&bp->bio_t0);
263 devstat_start_transaction(ds, &bp->bio_t0);
264 DTRACE_DEVSTAT_BIO_START();
268 * Record the ending of a transaction, and incrment the various counters.
270 * Ordering in this function, and in devstat_start_transaction() is VERY
271 * important. The idea here is to run without locks, so we are very
272 * careful to only modify some fields on the way "down" (i.e. at
273 * transaction start) and some fields on the way "up" (i.e. at transaction
274 * completion). One exception is busy_from, which we only modify in
275 * devstat_start_transaction() when there are no outstanding transactions,
276 * and thus it can't be modified in devstat_end_transaction()
279 * The sequence0 and sequence1 fields are provided to enable an application
280 * spying on the structures with mmap(2) to tell when a structure is in a
281 * consistent state or not.
283 * For this to work 100% reliably, it is important that the two fields
284 * are at opposite ends of the structure and that they are incremented
285 * in the opposite order of how a memcpy(3) in userland would copy them.
286 * We assume that the copying happens front to back, but there is actually
287 * no way short of writing your own memcpy(3) replacement to guarantee
288 * this will be the case.
290 * In addition to this, being a kind of locks, they must be updated with
291 * atomic instructions using appropriate memory barriers.
294 devstat_end_transaction(struct devstat *ds, uint32_t bytes,
295 devstat_tag_type tag_type, devstat_trans_flags flags,
296 struct bintime *now, struct bintime *then)
298 struct bintime dt, lnow;
309 atomic_add_acq_int(&ds->sequence1, 1);
310 /* Update byte and operations counts */
311 ds->bytes[flags] += bytes;
312 ds->operations[flags]++;
315 * Keep a count of the various tag types sent.
317 if ((ds->flags & DEVSTAT_NO_ORDERED_TAGS) == 0 &&
318 tag_type != DEVSTAT_TAG_NONE)
319 ds->tag_types[tag_type]++;
322 /* Update duration of operations */
324 bintime_sub(&dt, then);
325 bintime_add(&ds->duration[flags], &dt);
328 /* Accumulate busy time */
330 bintime_sub(&dt, &ds->busy_from);
331 bintime_add(&ds->busy_time, &dt);
332 ds->busy_from = *now;
335 atomic_add_rel_int(&ds->sequence0, 1);
336 DTRACE_DEVSTAT_DONE();
340 devstat_end_transaction_bio(struct devstat *ds, struct bio *bp)
343 devstat_end_transaction_bio_bt(ds, bp, NULL);
347 devstat_end_transaction_bio_bt(struct devstat *ds, struct bio *bp,
350 devstat_trans_flags flg;
356 if (bp->bio_cmd == BIO_DELETE)
358 else if (bp->bio_cmd == BIO_READ)
360 else if (bp->bio_cmd == BIO_WRITE)
363 flg = DEVSTAT_NO_DATA;
365 devstat_end_transaction(ds, bp->bio_bcount - bp->bio_resid,
366 DEVSTAT_TAG_SIMPLE, flg, now, &bp->bio_t0);
367 DTRACE_DEVSTAT_BIO_DONE();
371 * This is the sysctl handler for the devstat package. The data pushed out
372 * on the kern.devstat.all sysctl variable consists of the current devstat
373 * generation number, and then an array of devstat structures, one for each
374 * device in the system.
376 * This is more cryptic that obvious, but basically we neither can nor
377 * want to hold the devstat_mutex for any amount of time, so we grab it
378 * only when we need to and keep an eye on devstat_generation all the time.
381 sysctl_devstat(SYSCTL_HANDLER_ARGS)
387 mtx_assert(&devstat_mutex, MA_NOTOWNED);
390 * XXX devstat_generation should really be "volatile" but that
391 * XXX freaks out the sysctl macro below. The places where we
392 * XXX change it and inspect it are bracketed in the mutex which
393 * XXX guarantees us proper write barriers. I don't belive the
394 * XXX compiler is allowed to optimize mygen away across calls
395 * XXX to other functions, so the following is belived to be safe.
397 mygen = devstat_generation;
399 error = SYSCTL_OUT(req, &mygen, sizeof(mygen));
401 if (devstat_num_devs == 0)
407 mtx_lock(&devstat_mutex);
408 nds = STAILQ_FIRST(&device_statq);
409 if (mygen != devstat_generation)
411 mtx_unlock(&devstat_mutex);
416 for (;nds != NULL;) {
417 error = SYSCTL_OUT(req, nds, sizeof(struct devstat));
420 mtx_lock(&devstat_mutex);
421 if (mygen != devstat_generation)
424 nds = STAILQ_NEXT(nds, dev_links);
425 mtx_unlock(&devstat_mutex);
433 * Sysctl entries for devstat. The first one is a node that all the rest
436 static SYSCTL_NODE(_kern, OID_AUTO, devstat, CTLFLAG_RD, NULL,
437 "Device Statistics");
439 SYSCTL_PROC(_kern_devstat, OID_AUTO, all, CTLFLAG_RD|CTLTYPE_OPAQUE,
440 NULL, 0, sysctl_devstat, "S,devstat", "All devices in the devstat list");
442 * Export the number of devices in the system so that userland utilities
443 * can determine how much memory to allocate to hold all the devices.
445 SYSCTL_INT(_kern_devstat, OID_AUTO, numdevs, CTLFLAG_RD,
446 &devstat_num_devs, 0, "Number of devices in the devstat list");
447 SYSCTL_LONG(_kern_devstat, OID_AUTO, generation, CTLFLAG_RD,
448 &devstat_generation, 0, "Devstat list generation");
449 SYSCTL_INT(_kern_devstat, OID_AUTO, version, CTLFLAG_RD,
450 &devstat_version, 0, "Devstat list version number");
453 * Allocator for struct devstat structures. We sub-allocate these from pages
454 * which we get from malloc. These pages are exported for mmap(2)'ing through
455 * a miniature device driver
458 #define statsperpage (PAGE_SIZE / sizeof(struct devstat))
460 static d_mmap_t devstat_mmap;
462 static struct cdevsw devstat_cdevsw = {
463 .d_version = D_VERSION,
464 .d_flags = D_NEEDGIANT,
465 .d_mmap = devstat_mmap,
470 TAILQ_ENTRY(statspage) list;
471 struct devstat *stat;
475 static TAILQ_HEAD(, statspage) pagelist = TAILQ_HEAD_INITIALIZER(pagelist);
476 static MALLOC_DEFINE(M_DEVSTAT, "devstat", "Device statistics");
479 devstat_mmap(struct cdev *dev, vm_ooffset_t offset, vm_paddr_t *paddr,
480 int nprot, vm_memattr_t *memattr)
482 struct statspage *spp;
484 if (nprot != VM_PROT_READ)
486 TAILQ_FOREACH(spp, &pagelist, list) {
488 *paddr = vtophys(spp->stat);
496 static struct devstat *
500 struct statspage *spp, *spp2;
504 mtx_assert(&devstat_mutex, MA_NOTOWNED);
506 make_dev_credf(MAKEDEV_ETERNAL | MAKEDEV_CHECKNAME,
507 &devstat_cdevsw, 0, NULL, UID_ROOT, GID_WHEEL, 0400,
508 DEVSTAT_DEVICE_NAME);
512 mtx_lock(&devstat_mutex);
514 TAILQ_FOREACH(spp, &pagelist, list) {
520 mtx_unlock(&devstat_mutex);
521 spp2 = malloc(sizeof *spp, M_DEVSTAT, M_ZERO | M_WAITOK);
522 spp2->stat = malloc(PAGE_SIZE, M_DEVSTAT, M_ZERO | M_WAITOK);
523 spp2->nfree = statsperpage;
526 * If free statspages were added while the lock was released
529 mtx_lock(&devstat_mutex);
530 TAILQ_FOREACH(spp, &pagelist, list)
537 * It would make more sense to add the new page at the
538 * head but the order on the list determine the
539 * sequence of the mapping so we can't do that.
541 TAILQ_INSERT_TAIL(&pagelist, spp, list);
546 for (u = 0; u < statsperpage; u++) {
547 if (dsp->allocated == 0)
553 mtx_unlock(&devstat_mutex);
554 if (spp2 != NULL && spp2 != spp) {
555 free(spp2->stat, M_DEVSTAT);
556 free(spp2, M_DEVSTAT);
562 devstat_free(struct devstat *dsp)
564 struct statspage *spp;
566 mtx_assert(&devstat_mutex, MA_OWNED);
567 bzero(dsp, sizeof *dsp);
568 TAILQ_FOREACH(spp, &pagelist, list) {
569 if (dsp >= spp->stat && dsp < (spp->stat + statsperpage)) {
576 SYSCTL_INT(_debug_sizeof, OID_AUTO, devstat, CTLFLAG_RD,
577 SYSCTL_NULL_INT_PTR, sizeof(struct devstat), "sizeof(struct devstat)");