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)