The Processing Telemetry Vector
When an Ubuntu server suddenly experiences a massive spike in latency—causing websites to load slowly or databases to time out—you cannot rely on guesswork. You must instantly interrogate the Linux kernel to determine exactly which specific application or background daemon is monopolizing the physical processor (CPU) cycles or aggressively consuming the RAM. You require a real-time, high-fidelity diagnostic readout.
How to Check CPU Usage
The Linux architecture provides the `top` (Table of Processes) command, a native, deeply integrated utility that acts as a continuous, live-updating task manager directly within the terminal interface.
1. Open your terminal application or connect to the server via SSH.
2. The Initialization Command:
* Type the following exact command: top
* Press Enter.
3. Analyzing the Macro Telemetry (The Header Block):
* The terminal screen will instantly transform into a massive matrix of shifting data, refreshing every 3 seconds.
* Look at the first three lines at the absolute top of the screen.
* Line 1 (Load Average): Displays three numbers (e.g., `0.45, 0.52, 0.49`). These represent the average CPU load over the last 1, 5, and 15 minutes. If these numbers consistently exceed the total number of CPU cores in your server, your machine is critically overloaded.
* Line 3 (%Cpu(s)): Look for the number preceding `id` (idle). If it says `95.0 id`, your CPU is 95% idle (perfectly healthy). If it says `5.0 id`, your processor is operating at 95% maximum capacity.
4. Analyzing the Micro Telemetry (The Process List):
* Below the header block is the actual list of running software, automatically sorted by default so the most CPU-intensive task is always at the top (row 1).
* PID: The Process ID. You need this number if you want to forcefully kill the application.
* USER: The system account running the software (e.g., `root` or `www-data`).
* %CPU: The exact percentage of processor power that specific application is currently demanding.
* COMMAND: The name of the software (e.g., `mysql`, `apache2`, `python3`).
5. The Termination Protocol (Crucial):
* The `top` command runs in an infinite loop. You cannot type new commands while it is active.
* To exit the diagnostic matrix and return to the standard bash prompt, simply press the q key on your keyboard.