iotop(8)
NAME
iotop - simple top-like I/O monitor
SYNOPSIS
iotop [OPTIONS]
DESCRIPTION
iotop watches I/O usage information output by 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. 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 is 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 the one side and kernel block device subsystem on the other. While Actual DISK READ and Actual DISK WRITE values represent corresponding bandwidths for actual disk I/O between kernel block device subsystem and underlying hardware (HDD, SSD, etc.). Thus Total and Actual values may not be equal at any given moment of time due to data caching and I/O operations reordering that take place inside Linux kernel. Use the left and right arrows to change the sorting, r to reverse the sorting order, o to toggle the --only option, p to toggle the --processes option, a to toggle the --accumulated option, q to quit or i to change the priority of a thread or a process' thread(s). Any other key will force a refresh.
OPTIONS
--version
Show the version number and exit
-h, --help
Show usage information and exit
-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.
-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 list of processes/threads to monitor (all by default).
-u USER, --user=USER
A list of users to monitor (all by default)
-P, --processes
Only show processes. Normally iotop shows 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 iotop started.
-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.
-t, --time
Add a timestamp on each line (implies --batch). Each line will
be prefixed by the current time.
-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.
SEE ALSO
ionice(1), top(1), vmstat(1), atop(1), htop(1)
AUTHOR
iotop was written by Guillaume Chazarain.
This manual page was started by Paul Wise for the Debian project and is
placed in the public domain.
April 2009 IOTOP(8)
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