gkrellm-cpufreq software package provides CPU frequency plugin for GKrellM, you can install in your Ubuntu 16.04 LTS (Xenial Xerus) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install gkrellm-cpufreq
gkrellm-cpufreq is installed in your system.
Make ensure the gkrellm-cpufreq package were installed using the commands given below,
$ sudo dpkg-query -l | grep gkrellm-cpufreq *
You will get with gkrellm-cpufreq package name, version, architecture and description in a table
| Distro | Ubuntu 16 04 lts xenial xerus |
| Section | X Window System software |
| Package | gkrellm-cpufreq |
| Version | 0.6.4-4 |
| Description | CPU frequency plugin for GKrellM |
| Sub Section | X223 |