What is atop

atop is a real-time system monitoring tool for Linux-based operating systems. It provides detailed information about system performance, including CPU, memory, disk, network interface and other resource usage.

Features of atop

Key features of atop include:

1. Real-time monitoring: allows you to monitor system status in real time, updating information every few seconds.
2. Historical data: can save system performance data to a file for later analysis. This allows the user to view performance information for specific time periods.
3. Detailed information: atop provides detailed information about each process, including CPU, memory, I/O and network resource usage.
4. Multithreading support: can display threading information, which is useful for analyzing multithreaded applications.
5. Graphical interface: although atop is a command-line tool, it can be used with graphical interfaces to visualize data.

The main components of atop's operation are

Data collection

atop collects information about system state, including CPU, memory, disk, network interface, and process usage. It uses system calls and interfaces such as /proc to obtain information about current resource states.

Displaying information

After collecting data, atop displays it in a readable format in the terminal. The data is updated every few seconds (the default is every 10 seconds). The information is presented in the form of tables, where you can see the resource utilization at the system and process level.

Historical data

atop can save collected data to a file for later analysis. This allows users to view performance information for specific time intervals. This is done using a command line flag that points to a file to write the data to.

Analyzing processes

atop provides detailed information about each running process, including CPU, memory, I/O and network resource utilization. Users can sort processes by various criteria (such as CPU or memory utilization) to quickly identify bottlenecks.

Interactive interface

Users can control the display of information through various commands (e.g. filtering processes, changing the refresh interval, etc.). The q key is used to exit the program.

Example of operation

When you run atop, you may see something like this:

ATOP - all-in-one performance monitor
12:00:00 up 1 day, 3:45, 2 users, load average: 0.01, 0.05, 0.10
CPU total 1.50 0.00 0.00 0.00 0.00 0.00
Mem total 800000000 500000 500000 300000 100000
Swap total 200000000 100000 50000 50000 50000
PID USER COMMAND %CPU %MEM VIRT RES
1234 user1 my_process 0.50 1.00 100M 20M
5678 user2 another_process 0.00 0.50 0.50 50M 10M

Installation

In most Linux distributions atop can be installed via the package manager.

For Ubuntu/Debian:

sudo apt install atop

For CentOS/RHEL:

sudo yum install atop

Usage

To start atop, simply type the command in the terminal:

atop

By default, it will update every 10 seconds. You can change this interval by specifying it as an argument:

atop 5

This will update every 5 seconds.

Exit the program

To exit atop, press q.

Conclusion

atop is a powerful tool for system administrators and developers to effectively monitor and analyze system performance in real time and over specific time intervals.