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 Current DISK READ and Current DISK WRITE values represent corresponding bandwidths for current disk
       I/O  between  kernel  block  device  subsystem  and 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 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.

       --no-help
              Suppress the keyboard shortcuts help display.
              -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)