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)