1 #!/usr/sbin/dtrace -s 2 /* 3 * seeksize.d - analyse disk head seek distance by process. 4 * Written using DTrace (Solaris 10 3/05). 5 * 6 * Disk I/O events caused by processes will in turn cause the disk heads 7 * to seek. This program analyses those seeks, so that we can determine 8 * if processes are causing the disks to seek in a "random" or "sequential" 9 * manner. 10 * 11 * $Id: seeksize.d,v 1.1.1.1 2015/09/30 22:01:07 christos Exp $ 12 * 13 * USAGE: seeksize.d # wait several seconds, then hit Ctrl-C 14 * 15 * FIELDS: 16 * PID process ID 17 * CMD command and argument list 18 * value distance in disk blocks (sectors) 19 * count number of I/O operations 20 * 21 * SEE ALSO: bitesize.d, iosnoop 22 * 23 * COPYRIGHT: Copyright (c) 2006 Brendan Gregg. 24 * 25 * CDDL HEADER START 26 * 27 * The contents of this file are subject to the terms of the 28 * Common Development and Distribution License, Version 1.0 only 29 * (the "License"). You may not use this file except in compliance 30 * with the License. 31 * 32 * You can obtain a copy of the license at Docs/cddl1.txt 33 * or http://www.opensolaris.org/os/licensing. 34 * See the License for the specific language governing permissions 35 * and limitations under the License. 36 * 37 * CDDL HEADER END 38 * 39 * 11-Sep-2004 Brendan Gregg Created this. 40 * 10-Oct-2004 " " Rewrote to use the io provider. 41 * 20-Apr-2006 " " Last update. 42 */ 43 44 #pragma D option quiet 45 46 /* 47 * Print header 48 */ 49 dtrace:::BEGIN 50 { 51 printf("Tracing... Hit Ctrl-C to end.\n"); 52 } 53 54 self int last[dev_t]; 55 56 /* 57 * Process io start 58 */ 59 io:genunix::start 60 /self->last[args[0]->b_edev] != 0/ 61 { 62 /* calculate seek distance */ 63 this->last = self->last[args[0]->b_edev]; 64 this->dist = (int)(args[0]->b_blkno - this->last) > 0 ? 65 args[0]->b_blkno - this->last : this->last - args[0]->b_blkno; 66 67 /* store details */ 68 @Size[pid, curpsinfo->pr_psargs] = quantize(this->dist); 69 } 70 71 io:genunix::start 72 { 73 /* save last position of disk head */ 74 self->last[args[0]->b_edev] = args[0]->b_blkno + 75 args[0]->b_bcount / 512; 76 } 77 78 /* 79 * Print final report 80 */ 81 dtrace:::END 82 { 83 printf("\n%8s %s\n", "PID", "CMD"); 84 printa("%8d %S\n%@d\n", @Size); 85 } 86