How to monitor power usage in Linux

Last updated on October 26, 2020 by Dan Nanni

It is important to measure power consumption in operating system especially when you try to maximize the battery life of your laptop, or reduce the energy bill of rack-mounted servers in a data center. Power usage monitor can also be helpful to diagnose issues with power management, or even buggy behaviors of applications.

In this post, I will describe how to monitor power usage in Linux operating system.

For Linux-based systems, you can use PowerTop, an ncurses-based command-line tool developed by Intel to monitor process-level power consumption, and to provide suggestions to optimize power management. PowerTop supports Intel, AMD, ARM, and UltraSparc processors while it is the most reliable on Intel processors for the obvious reason.

Install PowerTop on Linux

Install PowerTop on Ubuntu or Debian

$ sudo apt-get install powertop

Install PowerTop on CentOS, Fedora or RHEL

$ sudo yum install powertop

Run PowerTop

To launch PowerTop, simply run:

$ sudo powertop

Once PowerTop is launched, you can press left/right arrow keys to navigate tab-based UI. PowerTop can start reporting power estimates after it has collected enough measurements, which can take a couple of minutes. Previous measurements are stored in /var/cache/powertop, and will be loaded upon subsequent PowerTop launch.

In Tunables menu, you can experiment with various power management settings in case some tunable parameters are not enabled on your Linux distribution.

For offline analysis, PowerTop allows you to export power monitoring results to csv or html format as follows.

$ sudo powertop --csv=output.csv
$ sudo powertop --html=output.html

To get more accurate estimates, you can run PowerTop in calibration mode as follows. The entire calibration process can take a couple of minutes. During calibration, PowerTop can disconnect your system from WiFi, adjust screen brightness, and generate USB device activities.

$ sudo powertop --calibrate
Loaded 27 prior measurements
Starting PowerTOP power estimate calibration 
Calibrating idle
Calibrating: disk usage 
My (0) time 14986258702 is not the same as child (0) time 15395089845
Calibrating backlight
.... device /sys/class/backlight/intel_backlight/brightness 

The screenshots of PowerTop are shown below.

PowerTop Overview

PowerTop Idle Stats

PowerTop Frequency Stats

PowerTop Device Stats

PowerTop Tunables

HTML Report Generated by PowerTop

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