iotop command 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.
Type the following command to run iotop (must run as root):
However, I recommend that you start
–only option to see only processes or threads actually doing I/O, instead of showing all processes or threads (you can set this mode dynamically too see keyboard shortcut o for more info):
Other supported options by iotop command:
Only show processes or threads actually doing I/O, instead of showing all processes or threads. This can be dynamically toggled by pressing o.
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)
Only show processes. Normally iotop shows all threads.
Show accumulated I/O instead of bandwidth. In this mode, iotop shows the amount of I/O processes have done since iotop started.
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.
Add a timestamp on each line (implies –batch). Each line will be prefixed by the current time.
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.
Important keyboard shortcuts for iotop command
- Hit the left and right arrow keys to change the sorting.
- Hit r to reverse the sorting order.
- Hit o only to see processes or threads actually doing I/O, instead of showing all processes or threads.
- Hit p only show processes. Normally iotop shows all threads.
- Hit a display accumulated I/O instead of bandwidth. In this mode, iotop shows the amount of I/O processes have done since iotop started.
- Hit i to change the priority of a thread or a process’ thread(s) i.e. ionice.
- Hit q to quit iotop.