IOTOP(8) - man - phpman

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, CONFIG_TASKSTATS and CONFIG_VM_EVENT_COUN‐
       TERS 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-inte‐
              ger 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 cur‐
              rent 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)