atop – Advanced System & Process Monitor

atop is an interactive command which shows system performance (CPU, memory, disk and network). atop command is very similar to top command with lot more output.

How to install atop?

# yum install atop

• The default refresh interval is 10 seconds
• It also shows which processes are responsible for CPU, Memory and Disk loads.
• The output of atop can be controlled using certain keys (just like top command)

Below is a snapshot of atop command. You can see we have some disk and network statistics (which are missing in top command)

• atop uses colors to indicate if critical thresholds are breached like 90% CPU, 70% disk , swap 80% and 80% network utilization are considered critical and will be shown in colored values. These colors and thresholds can be modified in atoprc file (either /etc/atoprc or in your home dir ~/.atoprc)

some useful atop interactive commands (while atop is running press these keys):

• g – default output (when you run just    $ atop)
• m – shows memory stats.
• d – shows disk stats
• n – shows network stats
• y – shows threads of the processes
• c – shows full command of processes running
• z – pause the output (so that you can investigate)
• q – quit the program
• / – you can type regex to search patterns in full running command (very useful if you are looking for processes level information)

most of the above options are not toggle options you might have to press “g” to go back to default mode.

atop has many fields and options and you can either press key “h” during interactive session or do “man atop” to get complete list of options. It’s a very useful utility for performance monitoring.