xref: /onnv-gate/usr/src/cmd/dtrace/demo/io/iothrough.d (revision 0:68f95e015346)
1*0Sstevel@tonic-gate /*
2*0Sstevel@tonic-gate  * CDDL HEADER START
3*0Sstevel@tonic-gate  *
4*0Sstevel@tonic-gate  * The contents of this file are subject to the terms of the
5*0Sstevel@tonic-gate  * Common Development and Distribution License, Version 1.0 only
6*0Sstevel@tonic-gate  * (the "License").  You may not use this file except in compliance
7*0Sstevel@tonic-gate  * with the License.
8*0Sstevel@tonic-gate  *
9*0Sstevel@tonic-gate  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10*0Sstevel@tonic-gate  * or http://www.opensolaris.org/os/licensing.
11*0Sstevel@tonic-gate  * See the License for the specific language governing permissions
12*0Sstevel@tonic-gate  * and limitations under the License.
13*0Sstevel@tonic-gate  *
14*0Sstevel@tonic-gate  * When distributing Covered Code, include this CDDL HEADER in each
15*0Sstevel@tonic-gate  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16*0Sstevel@tonic-gate  * If applicable, add the following below this CDDL HEADER, with the
17*0Sstevel@tonic-gate  * fields enclosed by brackets "[]" replaced with your own identifying
18*0Sstevel@tonic-gate  * information: Portions Copyright [yyyy] [name of copyright owner]
19*0Sstevel@tonic-gate  *
20*0Sstevel@tonic-gate  * CDDL HEADER END
21*0Sstevel@tonic-gate  */
22*0Sstevel@tonic-gate /*
23*0Sstevel@tonic-gate  * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
24*0Sstevel@tonic-gate  * Use is subject to license terms.
25*0Sstevel@tonic-gate  */
26*0Sstevel@tonic-gate 
27*0Sstevel@tonic-gate #pragma D option quiet
28*0Sstevel@tonic-gate 
29*0Sstevel@tonic-gate io:::start
30*0Sstevel@tonic-gate {
31*0Sstevel@tonic-gate 	start[args[0]->b_edev, args[0]->b_blkno] = timestamp;
32*0Sstevel@tonic-gate }
33*0Sstevel@tonic-gate 
34*0Sstevel@tonic-gate io:::done
35*0Sstevel@tonic-gate /start[args[0]->b_edev, args[0]->b_blkno]/
36*0Sstevel@tonic-gate {
37*0Sstevel@tonic-gate 	/*
38*0Sstevel@tonic-gate 	 * We want to get an idea of our throughput to this device in KB/sec.
39*0Sstevel@tonic-gate 	 * What we have, however, is nanoseconds and bytes.  That is we want
40*0Sstevel@tonic-gate 	 * to calculate:
41*0Sstevel@tonic-gate 	 *
42*0Sstevel@tonic-gate 	 *                        bytes / 1024
43*0Sstevel@tonic-gate 	 *                  ------------------------
44*0Sstevel@tonic-gate 	 *                  nanoseconds / 1000000000
45*0Sstevel@tonic-gate 	 *
46*0Sstevel@tonic-gate 	 * But we can't calculate this using integer arithmetic without losing
47*0Sstevel@tonic-gate 	 * precision (the denomenator, for one, is between 0 and 1 for nearly
48*0Sstevel@tonic-gate 	 * all I/Os).  So we restate the fraction, and cancel:
49*0Sstevel@tonic-gate 	 *
50*0Sstevel@tonic-gate 	 *     bytes      1000000000         bytes        976562
51*0Sstevel@tonic-gate 	 *   --------- * -------------  =  --------- * -------------
52*0Sstevel@tonic-gate 	 *      1024      nanoseconds          1        nanoseconds
53*0Sstevel@tonic-gate 	 *
54*0Sstevel@tonic-gate 	 * This is easy to calculate using integer arithmetic; this is what
55*0Sstevel@tonic-gate 	 * we do below.
56*0Sstevel@tonic-gate 	 */
57*0Sstevel@tonic-gate 	this->elapsed = timestamp - start[args[0]->b_edev, args[0]->b_blkno];
58*0Sstevel@tonic-gate 	@[args[1]->dev_statname, args[1]->dev_pathname] =
59*0Sstevel@tonic-gate 	    quantize((args[0]->b_bcount * 976562) / this->elapsed);
60*0Sstevel@tonic-gate 	start[args[0]->b_edev, args[0]->b_blkno] = 0;
61*0Sstevel@tonic-gate }
62*0Sstevel@tonic-gate 
63*0Sstevel@tonic-gate END
64*0Sstevel@tonic-gate {
65*0Sstevel@tonic-gate 	printa("  %s (%s)\n%@d\n", @);
66*0Sstevel@tonic-gate }
67