iotop


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   CON-
       FIG_TASK_DELAY_ACCT,  CONFIG_TASK_IO_ACCOUNTING,  CONFIG_TASKSTATS  and
       CONFIG_VM_EVENT_COUNTERS  options need to be enabled in your Linux ker-
       nel 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  sam-
       pling 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  tog-
              gled 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.
              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 choos-
              ing  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)
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