1IOTOP(8)                    System Manager's Manual                   IOTOP(8)
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NAME

6       iotop - simple top-like I/O monitor
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SYNOPSIS

9       iotop [OPTIONS]
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DESCRIPTION

12       iotop  watches  I/O  usage  information  output  by  the  Linux  kernel
13       (requires 2.6.20 or later) and displays a table of current I/O usage by
14       processes   or   threads   on   the   system.   At   least   the   CON‐
15       FIG_TASK_DELAY_ACCT,  CONFIG_TASK_IO_ACCOUNTING,  CONFIG_TASKSTATS  and
16       CONFIG_VM_EVENT_COUNTERS  options need to be enabled in your Linux ker‐
17       nel build configuration.
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19       iotop displays columns for the I/O bandwidth read and written  by  each
20       process/thread  during  the  sampling period. It also displays the per‐
21       centage of time the thread/process spent while swapping  in  and  while
22       waiting  on  I/O.  For  each process, its I/O priority (class/level) is
23       shown.
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25       In addition, the total I/O bandwidth read and written during  the  sam‐
26       pling period is displayed at the top of the interface.  Total DISK READ
27       and Total DISK WRITE values represent total read  and  write  bandwidth
28       between  processes  and kernel threads on the one side and kernel block
29       device subsystem on the other. While Actual DISK READ and  Actual  DISK
30       WRITE  values  represent  corresponding  bandwidths for actual disk I/O
31       between kernel block device subsystem  and  underlying  hardware  (HDD,
32       SSD, etc.).  Thus Total and Actual values may not be equal at any given
33       moment of time due to data caching and I/O operations  reordering  that
34       take place inside Linux kernel.
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36       Use  the  left and right arrows to change the sorting, r to reverse the
37       sorting order, o to toggle the --only option, p to  toggle  the  --pro‐
38       cesses  option, a to toggle the --accumulated option, q to quit or i to
39       change the priority of a thread or a process' thread(s). Any other  key
40       will force a refresh.
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OPTIONS

43       --version
44              Show the version number and exit
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46       -h, --help
47              Show usage information and exit
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49       -o, --only
50              Only  show  processes  or threads actually doing I/O, instead of
51              showing all processes or threads. This can be  dynamically  tog‐
52              gled by pressing o.
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54       -b, --batch
55              Turn on non-interactive mode.  Useful for logging I/O usage over
56              time.
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58       -n NUM, --iter=NUM
59              Set the number of iterations  before  quitting  (never  quit  by
60              default).  This is most useful in non-interactive mode.
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62       -d SEC, --delay=SEC
63              Set  the  delay  between  iterations  in  seconds  (1  second by
64              default).  Accepts non-integer values such as 1.1 seconds.
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66       -p PID, --pid=PID
67              A list of processes/threads to monitor (all by default).
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69       -u USER, --user=USER
70              A list of users to monitor (all by default)
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72       -P, --processes
73              Only show processes. Normally iotop shows all threads.
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75       -a, --accumulated
76              Show accumulated I/O instead of bandwidth. In this  mode,  iotop
77              shows the amount of I/O processes have done since iotop started.
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79       -k, --kilobytes
80              Use  kilobytes  instead  of  a human friendly unit. This mode is
81              useful when scripting the batch mode of iotop. Instead of choos‐
82              ing  the  most  appropriate unit iotop will display all sizes in
83              kilobytes.
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85       -t, --time
86              Add a timestamp on each line (implies --batch). Each  line  will
87              be prefixed by the current time.
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89       -q, --quiet
90              suppress some lines of header (implies --batch). This option can
91              be specified up to three times to remove header lines.
92              -q     column names are only printed on the first iteration,
93              -qq    column names are never printed,
94              -qqq   the I/O summary is never printed.
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SEE ALSO

97       ionice(1), top(1), vmstat(1), atop(1), htop(1)
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AUTHOR

100       iotop was written by Guillaume Chazarain.
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102       This manual page was started by Paul Wise for the Debian project and is
103       placed in the public domain.
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107                                  April 2009                          IOTOP(8)
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