IOTOP(8)

NAME
iotop - simple top-like I/O monitor

SYNOPSIS
iotop [OPTIONS]

DESCRIPTION
iotop watches I/O usage information available in the Linux kernel (requires 2.6.20 or later) and displays a table of current I/O usage by processes or threads on the system. At least the CONFIG_TASK_DELAY_ACCT, CONFIG_TASK_IO_ACCOUNTING, CONFIG_TASKSTATS and CONFIG_VM_EVENT_COUNTERS options need to be enabled in your Linux kernel build configuration.

Running iotop as non-root user is possible by adding the NET_ADMIN capability. This can be done by e.g.:
    $ sudo setcap 'cap_net_admin+eip' <path-to>/iotop
Be warned that this will also allow other users to run it and get access to information that normally should not be available to them.

iotop displays columns for the I/O bandwidth read and written by each process/thread during the sampling period. It also displays the percentage of time the thread/process spent while swapping in and while waiting on I/O. For each process, its I/O priority (class/level) is shown.

In addition, the total I/O bandwidth read and written during the sampling period are displayed at the top of the interface. Total DISK READ and Total DISK WRITE values represent total read and write bandwidth between processes and kernel threads on one side and kernel block device subsystem on the other. While Current DISK READ and Current DISK WRITE values represent corresponding bandwidths for current disk I/O between the kernel block device subsystem and the underlying hardware (HDD, SSD, etc.). Thus Total and Current values may not be equal at any given moment of time due to data caching and I/O operations reordering that take place inside the Linux kernel.

Use the left and right arrows to select the sort column, r or space to reverse the sorting order, o to toggle the --only option (this uses the visible values from the GRAPH column or the IO column in case the GRAPH column is hidden), p to toggle the --processes option, a to cycle between the --accumulated, --accum-bw and normal operation, i to change the priority of a thread or a process's thread, f to change filtering by UID/PID (--user and --pid options), 1-9 to toggle the visibility of the respective column, 0 to show all columns, up/down arrows, page-up/page-down/home/end keys to scroll and q to quit. Any unrecognized key will be ignored.

All processes or threads that have exited are displayed grayed for the same time as is visible in the GRAPH column or 3 seconds when it is hidden. The invalid data points in the GRAPHS column are displayed inverse or with letter x (see option --dead-x and x shortcut). When using unicode characters each position contains two datapoints and only the positions with two invalid data points are reversed.

It is possible for threads of a process to have different priority from their main process. This is shown with ! in the PRIO column of the main process as e.g. !be/4.

Threads activity is always aggregated with and shown inside the main process.

When showing threads, they always appear below their main process and are sorted in the same way as the processes.

There are two ways to change the IO priority of a process or thread - press i and use arrows to select the process or thread from the visible ones on screen or press i and type its TID (PID and TID have the same value for the main process). Then use tab and arrows to change the priority value and confirm with enter. Shortcuts esc or q will cancel this mode.

To change the UID and PID filters, press f and use tab to select the UID or PID field, then type the numerical id or n to remove the filter and confirm with enter. Filtering is always done by TID because it is unique. Note that for the main process PID is the same as TID. Shortcuts esc or q will cancel this mode.

Starting with Linux kernel 5.14.x task_delayacct is configurable at runtime and set to off by default. This setting can be changed in interactive mode by the Ctrl-T shortcut. In batch mode a warning is printed when the setting is OFF. From the command line this can be enabled by:
    $ sudo sysctl kernel.task_delayacct=1
and disabled again by:
    $ sudo sysctl kernel.task_delayacct=0
It is advisable to keep this option off when not using this or another monitoring program because when enabled it has some effect on system performance.

OPTIONS

-v, --version
    Show the version number and exit

-h, --help
    Show usage information and exit

-H, --help-type=TYPE
    Set the type of interactive help shown. Accepted values for TYPE are none, win and inline.

-o, --only
    Only show processes or threads actually doing I/O, instead of showing all processes or threads. This can be dynamically toggled by pressing o

--no-only
    Show all processes or threads

-b, --batch
    Turn on non-interactive mode. Useful for logging I/O usage over time

-n NUM, --iter=NUM
    Set the number of iterations before quitting (never quit by default). This is most useful in non-interactive mode

-d SEC, --delay=SEC
    Set the delay between iterations in seconds (1 second by default). Accepts non-integer values such as 1.1 seconds

-p PID, --pid=PID
    A process/thread id to monitor (all by default)

-u USER, --user=USER
    A user id to monitor (all by default). The value will always be resolved first unless it is prefixed by + in which case it is treated as numeric only. Values that do not resolve but appear to be numeric are used as numeric

-P, --processes
    Only show processes. Normally iotop shows processes and all threads

--no-processes
    Show processes and all threads

-a, --accumulated
    Show accumulated I/O instead of bandwidth. In this mode, iotop shows the amount of I/O processes have done since the process or iotop started. Note that this option and --accum-bw are exclusive and they will turn each other off

--no-accumulated
    Show bandwidth (useful when changing config file with --write)

-A, --accum-bw
    Show accumulated I/O as bandwidth for the whole sampling period. In this mode, iotop shows the amount of I/O per second for the whole period since the process or iotop started Note that this option and --accumulated are exclusive and they will turn each other off

--no-accum-bw
    Show bandwidth (useful when changing config file with --write)

-k, --kilobytes
    Use kilobytes instead of a human friendly unit. This mode is useful when scripting the batch mode of iotop. Instead of choosing the most appropriate unit iotop will display all sizes in kilobytes

--no-kilobytes
    Use human friendly units

-t, --time
    Add a timestamp on each line (implies --batch). Each line will be prefixed by the current time

-c, --fullcmdline
    Show processes' full file path and parameters

--no-fullcmdline
    Show processes' names only

-1, --hide-pid
    Hide PID/TID column

--show-pid
    Show PID/TID column

-2, --hide-prio
    Hide PRIO column

--show-prio
    Show PRIO column

-3, --hide-user
    Hide USER column

--show-user
    Show USER column

-4, --hide-read
    Hide DISK READ column

--show-read
    Show DISK READ column

-5, --hide-write
    Hide DISK WRITE column

--show-write
    Show DISK WRITE column

-6, --hide-swapin
    Hide SWAPIN column

--show-swapin
    Show SWAPIN column

-7, --hide-io
    Hide IO column

--show-io
    Show IO column

-8, --hide-graph
    Hide GRAPH column

--show-graph
    Show GRAPH column

-9, --hide-command
    Hide COMMAND column

--show-command
    Show COMMAND column

-g TYPE, --grtype=TYPE
    Set GRAPH column data source. Accepted values for TYPE are io, r, w, rw and sw.

-R, --reverse-graph
    Reverse GRAPH direction - show most recent values on the right side

--no-reverse-graph
    Do not reverse GRAPH direction - show most recent values on the left side

-q, --quiet
    Suppress some lines of header (implies --batch). This option can be specified up to three times to remove header lines
    -q  column names are only printed on the first iteration,
    -qq column names are never printed,
    -qqq
        the I/O summary is never printed

-x, --dead-x
    Show exited processes/threads with letter x instead of inverse background

--no-dead-x
    Show exited processes/threads with inverse background

-e, --hide-exited
    Hide exited processes

--show-exited
    Show exited processes

-l, --no-color
    Do not colorize values

--color
    Colorize values. This will override the effect of the environment variable NO_COLOR when explicitly specified on the command line.

-T, --hide-time
    Do not show time clock in upper right corner

--show-time
    Show time clock in upper right corner

--si
    Use SI units of 1000 when printing values. The default is non-SI 1024

--no-si
    Use non-SI units of 1024 when printing values

--threshold=1..10
    Set the threshold to switch to next unit. The default value is 2

--ascii
    Disable using Unicode

--unicode
    Use Unicode drawing chars

-W, --write
    Merge the preceding options to the current config, save the config and exit. Note that all options after this one will be ignored.

KEYBOARD SHORTCUTS

q, Q
    Exit

W   Save current settings to configuration file in $HOME/.config/iotop/iotoprc

D   Reset all settings to their default values

<space>, r
    Toggle sort order

<home>
    Scroll to the top of the list

<end>
    Scroll to the bottom of the list

<page-up>
    Scroll one screen up

<page-down>
    Scroll one screen down

<up>
    Scroll one line up

<down>
    Scroll one line down

<right>
    Sort by next column

<left>
    Sort by previous column

<esc>
    Cancel ionice or filter selection. In case only the help window is open then close it

o, O
    Toggle showing only processes with IO activity

p, P
    Toggle showing processes/threads

a, A
    Cycle showing accumulated/accum-bw/current values

?   Toggle showing inline help

h, H
    Toggle showing window help

c, C
    Toggle showing full command line

1, 2, 3, 4, 5, 6, 7, 8, 9
    Toggle showing the column (column number corresponds to the shortcut)

0   Show all columns

g, G
    Cycle GRAPH source (IO=IO, R=DISK READ , W=DISK WRITE, R+W=DISK READ+DISK WRITE, SW=SWAPIN). Using g will cycle forward and G will cycle backward.

R   Toggle reverse GRAPH direction

i, I
    IOnice a process/thread (depends on process/thread display mode)

f, F
    Change UID and PID filters

u, U
    Toggle using Unicode/ASCII characters for pseudo graph

l, L
    Toggle colorizing values

x, X
    Toggle the display mode of exited processes/threads between letter x and inverse background

e, E
    Toggle the display of exited processes

T   Toggle the display of time clock in upper right corner

s, S
    Toggle freeze of data collection

Ctrl-B, b
    Toggle SI units

Ctrl-R, t
    Cycle unit threshold

Ctrl-T
    Toggle task_delayacct kernel sysctl

Ctrl-L
    Redraw screen

/   Change search regular expression. While the search regular expression is being edited, there is an indicator next to it that shows if the expression is valid. The search is confirmed by <enter> or cancelled by <esc>. List of shortcuts in the editor:

    <esc>
        Cancel editing and remove the regular expression filter

    <enter>
        Confirm the current regular expression and exit edit mode. In case the regular expression is empty or invalid it will match everything.

    Alt/Meta-<backspace>, Ctrl-W
        Delete one word from cursor to the left

    Alt/Meta-D
        Delete one word from cursor to the right

    Alt/Meta-B, Ctrl-<left>
        Move the cursor to the beginning of the word on the left

    Alt/Meta-F, Ctrl-<right>
        Move the cursor after the end of the word on the right

    Ctrl-A, <home>
        Move the cursor to the leftmost position

    Ctrl-E, <end>
        Move the cursor after the last character

    Ctrl-B, <left>
        Move the cursor to the left

    Ctrl-F, <right>
        Move the cursor to the right

    Ctrl-H, <backspace>
        Delete the character left of cursor

    Ctrl-D, <del>
        Delete the character under the cursor

    Ctrl-K
        Delete from the character under the cursor to the end of the line

    Ctrl-U
        Delete everything

    [anything-else]
        Non-printable characters are ignored. Normal characters are inserted before the character under the cursor. UTF-8 sequences are parsed and treated as a single character. Unicode combining characters will be appended to the character under the cursor.

ENVIRONMENT
As per the recommendation of https://www.no-color.org/ iotop honors the contents of the environment variable NO_COLOR and when it is set to a non empty string, all color output is suppressed.

SEE ALSO
ionice(1), top(1), vmstat(1), atop(1), htop(1)

AUTHOR
The original Python iotop implementation was written by Guillaume Chazarain. This rewrite in C was started in 2014 by Vyacheslav Trushkin and reworked to include all missing features from the original Python code and several new ones from 2020 to 2024 by Boian Bonev.

This manual page was started by Paul Wise for the Debian project and is placed in the public domain.