IOTOP(8)						      System Manager's Manual							  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 pro-
       cesses or threads on the system. At least the CONFIG_TASK_DELAY_ACCT, CONFIG_TASK_IO_ACCOUNTING, CONFIG_TASKSTATS and CONFIG_VM_EVENT_COUN-
       TERS 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 per-
       centage 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 --pro-
       cesses 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)