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1 | .\" Copyright (c) 1980 Regents of the University of California. |
2 | .\" All rights reserved. The Berkeley software License Agreement | |
3 | .\" specifies the terms and conditions for redistribution. | |
4 | .\" | |
df667069 | 5 | .\" @(#)iostat.8 5.1 (Berkeley) %G% |
3a672b8e | 6 | .\" |
df667069 | 7 | .TH IOSTAT 1 "18 January 1983" |
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8 | .UC 4 |
9 | .SH NAME | |
10 | iostat \- report I/O statistics | |
11 | .SH SYNOPSIS | |
12 | .B iostat | |
13 | [ interval [ count ] ] | |
14 | .SH DESCRIPTION | |
15 | .I Iostat | |
16 | iteratively reports the number of characters read and written to terminals, | |
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17 | and, for each disk, the number of seeks transfers per second, kilobytes |
18 | transfered per second, | |
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19 | and the milliseconds per average seek. |
20 | It also gives the percentage of time the system has | |
21 | spent in user mode, in user mode running low priority (niced) processes, | |
22 | in system mode, and idling. | |
23 | .PP | |
24 | To compute this information, for each disk, seeks and data transfer completions | |
25 | and number of words transferred are counted; | |
26 | for terminals collectively, the number | |
27 | of input and output characters are counted. | |
28 | Also, each sixtieth of a second, | |
29 | the state of each disk is examined | |
30 | and a tally is made if the disk is active. | |
31 | From these numbers and given the transfer rates | |
32 | of the devices it is possible to determine | |
33 | average seek times for each device. | |
34 | .PP | |
35 | The optional | |
36 | .I interval | |
37 | argument causes | |
38 | .I iostat | |
39 | to report once each | |
40 | .I interval | |
41 | seconds. | |
42 | The first report is for all time since a reboot and each | |
43 | subsequent report is for the last interval only. | |
44 | .PP | |
45 | The optional | |
46 | .I count | |
47 | argument restricts the number of reports. | |
48 | .SH FILES | |
49 | /dev/kmem | |
df667069 | 50 | .br |
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51 | /vmunix |
52 | .SH SEE ALSO | |
53 | vmstat(1) |