xref: /titanic_52/usr/src/cmd/avs/dsstat/sdbc_stats.c (revision 69112edd987c28fa551d4f8d9362a84a45365f17)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 /*
22  * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
23  * Use is subject to license terms.
24  */
25 
26 #include <stdio.h>
27 #include <stdlib.h>
28 #include <string.h>
29 #include <unistd.h>
30 #include <errno.h>
31 #include <inttypes.h>
32 
33 #include <kstat.h>
34 
35 #include <sys/nsctl/nsctl.h>
36 #include <sys/nsctl/sd_bcache.h>
37 
38 #include "sdbc_stats.h"
39 
40 #include "dsstat.h"
41 #include "common.h"
42 #include "report.h"
43 
44 static sdbcstat_t *sdbc_top;
45 kstat_t *sdbc_global = NULL;
46 
47 void sdbc_header();
48 int sdbc_value_check(sdbcstat_t *);
49 int sdbc_validate(kstat_t *);
50 uint32_t sdbc_getdelta(sdbcstat_t *, char *);
51 
52 void sdbc_addstat(sdbcstat_t *);
53 sdbcstat_t *sdbc_delstat(sdbcstat_t *);
54 void center(int, char *);
55 
56 /*
57  * sdbc_discover() - looks for new statistics to be monitored.
58  * Verifies that any statistics found are now already being
59  * monitored.
60  *
61  */
62 int
63 sdbc_discover(kstat_ctl_t *kc)
64 {
65 	static int validated = 0;
66 
67 	kstat_t *ksp;
68 
69 	for (ksp = kc->kc_chain; ksp; ksp = ksp->ks_next) {
70 		int kinst;
71 		char kname[KSTAT_STRLEN + 1];
72 		sdbcstat_t *cur;
73 		sdbcstat_t *sdbcstat = NULL;
74 		kstat_t *io_ksp;
75 
76 		if (strcmp(ksp->ks_module, SDBC_KSTAT_MODULE) != 0 ||
77 		    strncmp(ksp->ks_name, SDBC_KSTAT_CDSTATS, 2) != 0)
78 			continue;
79 
80 		if (kstat_read(kc, ksp, NULL) == -1)
81 			continue;
82 
83 		/*
84 		 * Validate kstat structure
85 		 */
86 		if (! validated) {
87 			if (sdbc_validate(ksp))
88 				return (EINVAL);
89 
90 			validated++;
91 		}
92 
93 		/*
94 		 * Duplicate check
95 		 */
96 		for (cur = sdbc_top; cur; cur = cur->next) {
97 			char *cur_vname, *tst_vname;
98 
99 			cur_vname = kstat_value(cur->pre_set,
100 			    SDBC_CDKSTAT_VOL_NAME);
101 
102 			tst_vname = kstat_value(ksp,
103 			    SDBC_CDKSTAT_VOL_NAME);
104 
105 			if (strncmp(cur_vname, tst_vname, NAMED_LEN) == 0)
106 				goto next;
107 		}
108 
109 		/*
110 		 * Initialize new record
111 		 */
112 		sdbcstat = (sdbcstat_t *)calloc(1, sizeof (sdbcstat_t));
113 
114 		kinst = ksp->ks_instance;
115 
116 		/*
117 		 * Set kstat
118 		 */
119 		sdbcstat->pre_set = kstat_retrieve(kc, ksp);
120 
121 		if (sdbcstat->pre_set == NULL)
122 			goto next;
123 
124 		sdbcstat->collected |= GOT_SET_KSTAT;
125 
126 		/*
127 		 * I/O kstat
128 		 */
129 		(void) sprintf(kname, "%s%d",  SDBC_IOKSTAT_CDSTATS, kinst);
130 
131 		io_ksp = kstat_lookup(kc, SDBC_KSTAT_MODULE, kinst, kname);
132 		sdbcstat->pre_io = kstat_retrieve(kc, io_ksp);
133 
134 		if (sdbcstat->pre_io == NULL)
135 			goto next;
136 
137 		sdbcstat->collected |= GOT_IO_KSTAT;
138 
139 next:
140 		/*
141 		 * Check if we got a complete set of stats
142 		 */
143 		if (sdbcstat == NULL)
144 			continue;
145 
146 		if (SDBC_COMPLETE(sdbcstat->collected)) {
147 			(void) sdbc_delstat(sdbcstat);
148 			continue;
149 		}
150 
151 		sdbc_addstat(sdbcstat);
152 	}
153 
154 	if (sdbc_top == NULL)
155 		return (EAGAIN);
156 
157 	return (0);
158 }
159 
160 /*
161  * sdbc_update() - updates all of the statistics currently being monitored.
162  *
163  */
164 int
165 sdbc_update(kstat_ctl_t *kc)
166 {
167 	kstat_t *ksp;
168 	sdbcstat_t *cur;
169 
170 	/* Update global kstat information */
171 	ksp = kstat_lookup(kc, SDBC_KSTAT_MODULE, -1, SDBC_KSTAT_GSTATS);
172 
173 	if (ksp == NULL)
174 		return (EAGAIN);
175 
176 	if (sdbc_global)
177 		kstat_free(sdbc_global);
178 
179 	sdbc_global = kstat_retrieve(kc, ksp);
180 
181 	for (cur = sdbc_top; cur != NULL; cur = cur->next) {
182 		int kinst;
183 		char *kname, *cname, *pname;
184 
185 		kstat_t *set_ksp, *io_ksp;
186 
187 		cur->collected = 0;
188 
189 		/*
190 		 * Age off old stats
191 		 */
192 		if (cur->cur_set != NULL) {
193 			kstat_free(cur->pre_set);
194 			kstat_free(cur->pre_io);
195 
196 			cur->pre_set = cur->cur_set;
197 			cur->pre_io = cur->cur_io;
198 		}
199 
200 		/*
201 		 * Update set kstat
202 		 */
203 		kinst = cur->pre_set->ks_instance;
204 		kname = cur->pre_set->ks_name;
205 
206 		set_ksp = kstat_lookup(kc, SDBC_KSTAT_MODULE, kinst, kname);
207 
208 		if ((cur->cur_set = kstat_retrieve(kc, set_ksp)) == NULL)
209 			continue;
210 
211 		cur->collected |= GOT_SET_KSTAT;
212 
213 		/*
214 		 * Validate set
215 		 */
216 		pname = kstat_value(cur->pre_set, SDBC_CDKSTAT_VOL_NAME);
217 		cname = kstat_value(cur->cur_set, SDBC_CDKSTAT_VOL_NAME);
218 
219 		if (strncmp(pname, cname, NAMED_LEN) != 0)
220 			continue;
221 
222 		/*
223 		 * Update I/O kstat
224 		 */
225 		kinst = cur->pre_io->ks_instance;
226 		kname = cur->pre_io->ks_name;
227 
228 		io_ksp = kstat_lookup(kc, SDBC_KSTAT_MODULE, kinst, kname);
229 
230 		if ((cur->cur_io = kstat_retrieve(kc, io_ksp)) == NULL)
231 			continue;
232 
233 		cur->collected |= GOT_IO_KSTAT;
234 	}
235 
236 	return (0);
237 }
238 
239 /*
240  * sdbc_report() - outputs statistics for the statistics currently being
241  * monitored.  Deletes statistics for volumes that have been disabled.
242  *
243  */
244 int
245 sdbc_report()
246 {
247 	vslist_t *vslist = vs_top;
248 	sdbcstat_t *cur, *pre = NULL;
249 
250 	if (sdbc_top == NULL)
251 		return (0);
252 
253 	for (cur = sdbc_top; cur != NULL; ) { /* CSTYLED */
254 		static uint32_t linesout = 0;
255 		uint32_t *offline;
256 
257 		char volname[NAMED_LEN + 1];
258 		char rmode[STAT_HDR_SIZE];
259 		char wmode[STAT_HDR_SIZE];
260 
261 		/* Parse volume name */
262 		(void) strncpy(volname, kstat_value(cur->pre_set,
263 		    SDBC_CDKSTAT_VOL_NAME), NAMED_LEN);
264 		volname[NAMED_LEN] = '\0';
265 
266 		/* Check to see if the user specified this volume */
267 		for (vslist = vs_top; vslist != NULL; vslist = vslist->next)
268 			if (strcmp(volname, vslist->volname) == 0)
269 				break;
270 
271 		if (vs_top != NULL && vslist == NULL)
272 			goto next;
273 
274 		/* Check if volume is offline and zflag applies */
275 		if (zflag && sdbc_value_check(cur) == 0)
276 			goto next;
277 
278 		/* Output volume name */
279 		sdbc_header();
280 
281 		(void) printf(DATA_C16, volname);
282 
283 		if (SDBC_COMPLETE(cur->collected)) {
284 			sdbcstat_t *next = sdbc_delstat(cur);
285 
286 			if (! pre)
287 				cur = sdbc_top = next;
288 			else
289 				cur = pre->next = next;
290 
291 			(void) printf(" <<volume disabled>>\n");
292 			continue;
293 		}
294 
295 		offline = kstat_value(cur->cur_set, SDBC_CDKSTAT_FAILED);
296 		if (*offline) {
297 			(void) printf(" <<volume offline>>\n");
298 			linesout++;
299 			goto next;
300 		}
301 
302 		/* Type/status flags */
303 		if (dflags & FLAGS) {
304 
305 			uint32_t *dhint, *nhint;
306 			uint32_t hints;
307 
308 			dhint = kstat_value(cur->cur_set, SDBC_CDKSTAT_CDHINTS);
309 			nhint = kstat_value(sdbc_global, SDBC_GKSTAT_NODEHINTS);
310 
311 			if (! nhint)
312 				return (EINVAL);
313 
314 			hints = *nhint;
315 			hints &= (NSC_FORCED_WRTHRU | NSC_NO_FORCED_WRTHRU |
316 			    NSC_NOCACHE);
317 			hints |= *dhint;
318 
319 			if (hints & NSC_NOCACHE)
320 				(void) strcpy(rmode, "D");
321 			else
322 				(void) strcpy(rmode, "C");
323 
324 			if ((hints & NSC_FORCED_WRTHRU) || (hints & NSC_WRTHRU))
325 				(void) strcpy(wmode, "D");
326 			else
327 				(void) strcpy(wmode, "C");
328 
329 			(void) printf(DATA_C2, rmode);
330 			(void) printf(DATA_C2, wmode);
331 		}
332 
333 		/* Output set information */
334 		cd_report(cur);
335 
336 next:
337 		pre = cur;
338 		cur = cur->next;
339 	}
340 
341 	return (0);
342 }
343 
344 /*
345  * sdbc_header() - outputs an appropriate header by referencing the
346  * global variables dflsgs
347  *
348  */
349 void
350 sdbc_header()
351 {
352 	int rcount = 0;
353 
354 	if (hflags == HEADERS_EXL)
355 		if ((linesout % DISPLAY_LINES) != 0)
356 			return;
357 
358 	if (hflags == HEADERS_BOR)
359 		if (linesout != 0)
360 			return;
361 
362 	if (hflags & HEADERS_ATT)
363 		if (hflags & HEADERS_OUT)
364 			return;
365 		else
366 			hflags |= HEADERS_OUT;
367 
368 	if (linesout)
369 		(void) printf("\n");
370 
371 	/* first line header */
372 	if (! (dflags & SUMMARY) && dflags != FLAGS) {
373 
374 		(void) printf(VOL_HDR_FMT, " ");
375 
376 		if (dflags & FLAGS) {
377 			(void) printf(STAT_HDR_FMT, " ");
378 			(void) printf(STAT_HDR_FMT, " ");
379 		}
380 
381 		if (dflags & READ) {
382 			int size;
383 
384 			size = KPS_HDR_SIZE * 2 + HIT_HDR_SIZE;
385 			center(size, "- read -");
386 			rcount++;
387 		}
388 
389 		if (dflags & WRITE) {
390 			int size;
391 
392 			size = KPS_HDR_SIZE * 2 + HIT_HDR_SIZE;
393 			center(size, "- write -");
394 			rcount++;
395 		}
396 
397 		if (dflags != FLAGS)
398 			(void) printf("\n");
399 	}
400 
401 	/* second line header */
402 	(void) printf(VOL_HDR_FMT, "volume");
403 
404 	if (dflags & FLAGS) {
405 		(void) printf(STAT_HDR_FMT, "rd");
406 		(void) printf(STAT_HDR_FMT, "wr");
407 	}
408 
409 	if (dflags & SUMMARY) {
410 		(void) printf(KPS_HDR_FMT, "ckps");
411 		(void) printf(KPS_HDR_FMT, "dkps");
412 		(void) printf(HIT_HDR_FMT, HIT_HDR_TXT);
413 
414 		goto out;
415 	}
416 
417 	if (dflags & READ) {
418 		(void) printf(KPS_HDR_FMT, "ckps");
419 		(void) printf(KPS_HDR_FMT, "dkps");
420 		(void) printf(HIT_HDR_FMT, RHIT_HDR_TXT);
421 	}
422 
423 	if (dflags & WRITE) {
424 		(void) printf(KPS_HDR_FMT, "ckps");
425 		(void) printf(KPS_HDR_FMT, "dkps");
426 		(void) printf(HIT_HDR_FMT, WHIT_HDR_TXT);
427 	}
428 
429 	if (dflags & DESTAGED)
430 		(void) printf(KPS_HDR_FMT, "dstg");
431 
432 	if (dflags & WRCANCEL)
433 		(void) printf(KPS_HDR_FMT, "cwrl");
434 
435 out:
436 	(void) printf("\n");
437 }
438 
439 /*
440  * sdbc_getstat() - find cache stat by name matching
441  *
442  * paraemters
443  * 	char *vn - the volume name to match against
444  * returns
445  * 	sdbcstat_t * - the matching strcture, NULL if not found
446  */
447 sdbcstat_t *
448 sdbc_getstat(char *vn)
449 {
450 	sdbcstat_t *cur, *pre = NULL;
451 
452 	for (cur = sdbc_top; cur; ) { /* CSTYLED */
453 		char *volname =
454 		    kstat_value(cur->pre_set, SDBC_CDKSTAT_VOL_NAME);
455 
456 		if (SDBC_COMPLETE(cur->collected)) {
457 			sdbcstat_t *next = sdbc_delstat(cur);
458 
459 			if (! pre)
460 				cur = sdbc_top = next;
461 			else
462 				cur = pre->next = next;
463 
464 			continue;
465 		}
466 
467 		if (strncmp(volname, vn, NAMED_LEN) == 0)
468 			return (cur);
469 
470 		pre = cur;
471 		cur = cur->next;
472 	}
473 
474 	return (NULL);
475 }
476 
477 /*
478  * sdbc_addstat() - adds a fully populated sdbcstat_t structure
479  * to the linked list of currently monitored kstats.  The structure
480  * will be added in alphabetical order, using the volume name as the
481  * key.
482  *
483  * parameters
484  * 	sdbcstat_t *sdbcstat - to be added to the list.
485  *
486  */
487 void
488 sdbc_addstat(sdbcstat_t *sdbcstat)
489 {
490 	sdbcstat_t *cur;
491 
492 	if (sdbc_top == NULL) {
493 		sdbc_top = sdbcstat;
494 		return;
495 	}
496 
497 	for (cur = sdbc_top; cur != NULL; cur = cur->next) {
498 		char *cur_vname, *nxt_vname, *tst_vname;
499 
500 		cur_vname = kstat_value(cur->pre_set,
501 		    SDBC_CDKSTAT_VOL_NAME);
502 		tst_vname = kstat_value(sdbcstat->pre_set,
503 		    SDBC_CDKSTAT_VOL_NAME);
504 
505 		if (strncmp(cur_vname, tst_vname, NAMED_LEN) > 0) {
506 			if (cur == sdbc_top)
507 				sdbc_top = sdbcstat;
508 
509 			sdbcstat->next = cur;
510 
511 			return;
512 		}
513 
514 		/*
515 		 * If we get to the last item in the list, then just
516 		 * add this one to the end
517 		 */
518 		if (cur->next == NULL) {
519 			cur->next = sdbcstat;
520 			return;
521 		}
522 
523 		nxt_vname = kstat_value(cur->next->pre_set,
524 		    SDBC_CDKSTAT_VOL_NAME);
525 
526 		if (strncmp(nxt_vname, tst_vname, NAMED_LEN) > 0) {
527 			sdbcstat->next = cur->next;
528 			cur->next = sdbcstat;
529 			return;
530 		}
531 	}
532 }
533 
534 /*
535  * sdbc_delstat() - deallocate memory for the structure being
536  * passed in.
537  *
538  * parameters
539  * 	sdbcstat_t *sdbcstat - structure to be deallocated
540  *
541  * returns
542  * 	sdbcstat_t * - pointer to the "next" structures in the
543  * 	linked list. May be NULL if we are removing the last
544  * 	structure in the linked list.
545  */
546 sdbcstat_t *
547 sdbc_delstat(sdbcstat_t *sdbcstat)
548 {
549 
550 	sdbcstat_t *next = sdbcstat->next;
551 
552 	kstat_free(sdbcstat->pre_set);
553 	kstat_free(sdbcstat->pre_io);
554 	kstat_free(sdbcstat->cur_set);
555 	kstat_free(sdbcstat->cur_io);
556 
557 	free(sdbcstat);
558 	sdbcstat = NULL;
559 
560 	return (next);
561 }
562 
563 /*
564  * sdbc_value_check() - Checks for activity, supports -z switch
565  *
566  * parameters
567  * 	sdbcstat_t *sdbcstat - structure to be checked
568  *
569  * returns
570  * 	1 - activity
571  * 	0 - no activity
572  */
573 int
574 sdbc_value_check(sdbcstat_t *sdbcstat)
575 {
576 	if (SDBC_COMPLETE(sdbcstat->collected))
577 		return (1);
578 
579 	if (sdbc_getdelta(sdbcstat, SDBC_CDKSTAT_CACHE_READ) != 0)
580 		return (1);
581 
582 	if (sdbc_getdelta(sdbcstat, SDBC_CDKSTAT_DISK_READ) != 0)
583 		return (1);
584 
585 	if (sdbc_getdelta(sdbcstat, SDBC_CDKSTAT_CACHE_WRITE) != 0)
586 		return (1);
587 
588 	if (sdbc_getdelta(sdbcstat, SDBC_CDKSTAT_DISK_WRITE) != 0)
589 		return (1);
590 
591 	if (sdbc_getdelta(sdbcstat, SDBC_CDKSTAT_WRCANCELNS) != 0)
592 		return (1);
593 
594 	if (io_value_check(sdbcstat->pre_io->ks_data,
595 	    sdbcstat->cur_io->ks_data) != 0)
596 		return (1);
597 
598 	return (0);
599 }
600 
601 /*
602  * sdbc_validate() - validates the structure of the kstats by attempting to
603  *                   lookup fields used by this module
604  *
605  * parameters
606  *	kstat_t *ksp - kstat to be examined
607  *
608  * returns
609  * 	1 - one or more fields missing
610  * 	0 - all fields present
611  */
612 int
613 sdbc_validate(kstat_t *ksp)
614 {
615 	if (! kstat_value(ksp, SDBC_CDKSTAT_VOL_NAME) ||
616 	    ! kstat_value(ksp, SDBC_CDKSTAT_FAILED) ||
617 	    ! kstat_value(ksp, SDBC_CDKSTAT_CDHINTS) ||
618 	    ! kstat_value(ksp, SDBC_CDKSTAT_CACHE_READ) ||
619 	    ! kstat_value(ksp, SDBC_CDKSTAT_DISK_READ) ||
620 	    ! kstat_value(ksp, SDBC_CDKSTAT_CACHE_WRITE) ||
621 	    ! kstat_value(ksp, SDBC_CDKSTAT_DISK_WRITE) ||
622 	    ! kstat_value(ksp, SDBC_CDKSTAT_DESTAGED) ||
623 	    ! kstat_value(ksp, SDBC_CDKSTAT_WRCANCELNS))
624 		return (1);
625 
626 	return (0);
627 }
628 
629 /*
630  * sdbc_getvalues() - populates a values structure with data obtained from the
631  *                    kstat
632  *
633  * parameters
634  * 	sdbcstat_t *sdbcstat - pointer to the structure containing the kstats
635  * 	sdbcvals_t *vals - pointer to the structure that will receive the values
636  * 	int flags - flags that describe adjustments made to the values
637  *
638  * returns
639  * 	1 - failure
640  * 	0 - success
641  */
642 int
643 sdbc_getvalues(sdbcstat_t *sdbcstat, sdbcvals_t *vals, int flags)
644 {
645 	int divisor = 0;
646 	int factors;
647 	uint64_t hr_etime;
648 	double etime;
649 
650 	kstat_io_t *cur;
651 	kstat_io_t *pre;
652 
653 	if (sdbcstat == NULL)
654 		return (1);
655 
656 	cur = sdbcstat->cur_io->ks_data;
657 	pre = sdbcstat->pre_io->ks_data;
658 
659 	hr_etime = hrtime_delta(pre->rlastupdate, cur->rlastupdate);
660 	etime = hr_etime / (double)NANOSEC;
661 
662 	/* read data */
663 	vals->cache_read =
664 	    FBA_SIZE(sdbc_getdelta(sdbcstat, SDBC_CDKSTAT_CACHE_READ));
665 	vals->disk_read =
666 	    FBA_SIZE(sdbc_getdelta(sdbcstat, SDBC_CDKSTAT_DISK_READ));
667 
668 
669 	vals->total_reads = vals->cache_read + vals->disk_read;
670 
671 	if (vals->cache_read == 0)
672 		vals->read_hit = 0.0;
673 	else
674 		vals->read_hit =
675 		    ((float)vals->cache_read / vals->total_reads) * 100.0;
676 
677 	/* write data */
678 	vals->cache_write =
679 	    FBA_SIZE(sdbc_getdelta(sdbcstat, SDBC_CDKSTAT_CACHE_WRITE));
680 	vals->disk_write =
681 	    FBA_SIZE(sdbc_getdelta(sdbcstat, SDBC_CDKSTAT_DISK_WRITE));
682 
683 	vals->total_writes = vals->cache_write + vals->disk_write;
684 
685 	vals->destaged =
686 	    FBA_SIZE(sdbc_getdelta(sdbcstat, SDBC_CDKSTAT_DESTAGED));
687 
688 	if (vals->cache_write == 0)
689 		vals->write_hit = 0.0;
690 	else
691 		vals->write_hit = ((float)vals->cache_write /
692 		    (vals->total_writes - vals->destaged)) * 100.0;
693 
694 	/* miscellaneous */
695 	vals->write_cancellations =
696 	    FBA_SIZE(sdbc_getdelta(sdbcstat, SDBC_CDKSTAT_WRCANCELNS));
697 
698 	vals->total_cache = vals->cache_read + vals->cache_write;
699 	vals->total_disk = vals->disk_read + vals->disk_write;
700 
701 	/* total cache hit calculation */
702 	vals->cache_hit = 0;
703 	factors = 0;
704 
705 	if (vals->cache_read != 0) {
706 		vals->cache_hit += vals->read_hit;
707 		factors++;
708 	}
709 
710 	if (vals->cache_write != 0) {
711 		vals->cache_hit += vals->write_hit;
712 		factors++;
713 	}
714 
715 	if (vals->cache_hit)
716 		vals->cache_hit /= (float)factors;
717 
718 	/* adjustments */
719 	divisor = 1;
720 
721 	if (flags & SDBC_KBYTES)
722 		divisor *= KILOBYTE;
723 	if ((flags & SDBC_INTAVG) && (etime > 0))
724 		divisor *= etime;
725 
726 	if (divisor != 1) {
727 		vals->cache_read /= divisor;
728 		vals->disk_read /= divisor;
729 		vals->total_reads /= divisor;
730 
731 		vals->cache_write /= divisor;
732 		vals->disk_write /= divisor;
733 		vals->total_writes /= divisor;
734 
735 		vals->total_cache /= divisor;
736 		vals->total_disk /= divisor;
737 
738 		vals->destaged /= divisor;
739 		vals->write_cancellations /= divisor;
740 	}
741 
742 	return (0);
743 }
744 
745 /*
746  * sdbc_getdelta() - calculates the difference between two kstat fields
747  *
748  * parameters
749  * 	sdbcstat_t *sdbcstat - the SDBC stat strcture containing the two fields
750  * 	char *name - the name of the fields
751  * returns
752  * 	uint32_t value of the differences adjusted for overflow of the data type
753  */
754 uint32_t
755 sdbc_getdelta(sdbcstat_t *sdbcstat, char *name)
756 {
757 	uint32_t *cur_val;
758 	uint32_t *pre_val;
759 
760 	pre_val = kstat_value(sdbcstat->pre_set, name);
761 	cur_val = kstat_value(sdbcstat->cur_set, name);
762 
763 	return (u32_delta(*pre_val, *cur_val));
764 }
765 
766 void
767 center(int size, char *hdr)
768 {
769 	int lpad = 0;
770 	int rpad = 0;
771 	char fmt[10];
772 
773 	if (size == 0)
774 		return;
775 
776 	if (strlen(hdr) < size) {
777 		lpad = (size - strlen(hdr)) / 2;
778 
779 		if (lpad * 2 < size)
780 			lpad++;
781 
782 		rpad = size - (lpad + strlen(hdr));
783 	}
784 
785 output:
786 	(void) sprintf(fmt, "%%%ds%%s%%%ds", lpad, rpad);
787 	(void) printf(fmt, " ", hdr, " ");
788 }
789