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, Version 1.0 only
6 * (the "License").  You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22/*
23 * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
24 * Use is subject to license terms.
25 */
26
27#pragma D option quiet
28
29io:::start
30{
31	start[args[0]->b_edev, args[0]->b_blkno] = timestamp;
32}
33
34io:::done
35/start[args[0]->b_edev, args[0]->b_blkno]/
36{
37	/*
38	 * We want to get an idea of our throughput to this device in KB/sec.
39	 * What we have, however, is nanoseconds and bytes.  That is we want
40	 * to calculate:
41	 *
42	 *                        bytes / 1024
43	 *                  ------------------------
44	 *                  nanoseconds / 1000000000
45	 *
46	 * But we can't calculate this using integer arithmetic without losing
47	 * precision (the denomenator, for one, is between 0 and 1 for nearly
48	 * all I/Os).  So we restate the fraction, and cancel:
49	 *
50	 *     bytes      1000000000         bytes        976562
51	 *   --------- * -------------  =  --------- * -------------
52	 *      1024      nanoseconds          1        nanoseconds
53	 *
54	 * This is easy to calculate using integer arithmetic; this is what
55	 * we do below.
56	 */
57	this->elapsed = timestamp - start[args[0]->b_edev, args[0]->b_blkno];
58	@[args[1]->dev_statname, args[1]->dev_pathname] =
59	    quantize((args[0]->b_bcount * 976562) / this->elapsed);
60	start[args[0]->b_edev, args[0]->b_blkno] = 0;
61}
62
63END
64{
65	printa("  %s (%s)\n%@d\n", @);
66}
67