Why does cpupower report different speeds and settings depending on if I'm root?

When using the cpupower command in a Linux system, you may notice that it reports different speeds and settings depending on whether you are running it as a regular user or as the root user. This behavior is expected and is a result of the different privileges and access levels associated with each user.

As an entry-level user, you typically have limited access to system resources and settings. This includes the ability to modify CPU frequencies, which are controlled by the kernel. The cpupower command allows you to view and modify these frequencies, but only if you have the necessary permissions.

When you run cpupower as a regular user, you are only able to view the current CPU speeds and settings. This is useful for monitoring purposes or checking the current status of your CPU. However, you do not have the authority to make any changes to these settings.

On the other hand, when you run cpupower as the root user, also known as the superuser or administrator, you have full control over the system and can modify CPU frequencies and settings. Root privileges grant you unrestricted access to system resources, allowing you to make changes that affect the entire system.

It is important to note that the ability to modify CPU frequencies and settings can have a significant impact on system performance and stability. Therefore, it is generally recommended to exercise caution when making changes as the root user. Modifying these settings without proper knowledge or understanding can lead to unexpected behavior or even system crashes.

By default, most Linux distributions do not provide regular users with the necessary permissions to modify CPU frequencies. This is done to prevent accidental or malicious changes that could disrupt system operations. However, if you require the ability to adjust CPU frequencies as a regular user, you can configure your system to allow it.

To grant regular users the ability to modify CPU frequencies, you can use the sudo command. Sudo allows you to temporarily elevate your privileges to that of the root user for specific commands. By running sudo cpupower, you can access the full functionality of cpupower as if you were the root user.

It is worth mentioning that some Linux distributions may have alternative methods or tools for managing CPU frequencies. These tools might have different behavior and access levels depending on the user's privileges. Therefore, it is always recommended to consult the documentation or support resources specific to your distribution for accurate information.

In conclusion, the difference in speeds and settings reported by cpupower when running as a regular user versus the root user is due to the varying levels of privileges and access associated with each user. Regular users have limited access to modify CPU frequencies, while the root user has full control over system resources. It is important to exercise caution when modifying CPU settings and to consult the documentation or support resources for your specific Linux distribution.