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 processes or  threads  on
       the system. At least the CONFIG_TASK_DELAY_ACCT, CONFIG_TASK_IO_ACCOUNTING, CON‐
       FIG_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 hard‐
       ware (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 appropri‐
              ate unit iotop will display all sizes in kilobytes.

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

       -q, --quiet
              suppress some lines of header (implies --batch). This option can be spec‐
              ified 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)

Usage: /usr/sbin/iotop [OPTIONS]

DISK READ and DISK WRITE are the block I/O bandwidth used during the sampling
period. SWAPIN and IO are the percentages of time the thread spent respectively
while swapping in and waiting on I/O more generally. PRIO is the I/O priority at
which the thread is running (set using the ionice command).

Controls: left and right arrows to change the sorting column, r to invert the
sorting order, o to toggle the --only option, p to toggle the --processes
option, a to toggle the --accumulated option, i to change I/O priority, q to
quit, any other key to force a refresh.

Options:
  --version             show program's version number and exit
  -h, --help            show this help message and exit
  -o, --only            only show processes or threads actually doing I/O
  -b, --batch           non-interactive mode
  -n NUM, --iter=NUM    number of iterations before ending [infinite]
  -d SEC, --delay=SEC   delay between iterations [1 second]
  -p PID, --pid=PID     processes/threads to monitor [all]
  -u USER, --user=USER  users to monitor [all]
  -P, --processes       only show processes, not all threads
  -a, --accumulated     show accumulated I/O instead of bandwidth
  -k, --kilobytes       use kilobytes instead of a human friendly unit
  -t, --time            add a timestamp on each line (implies --batch)
  -q, --quiet           suppress some lines of header (implies --batch)