What is vJoule?

vJoule is a tool that can be used to estimate the energy consumption of a set of running processes. Technically, vJoule is built on a plugin system with two different kind of plugins :

  • core, this kind of plugin will define the behavior of vJoule and perform the information gathering from sensor plugins and the effective result computation. In this vJoule version two core plugins are implemented :
    • divider splits the consumption acquired by sensor plugins, and divides them between the running processes based on their relative system usage (%CPU, %GPU, etc.).
    • dumper retreives the consumption acquired by sensor plugins, and system usage of running processes and dump those metrics in csv files for cold analysis.
  • sensor, this kind of plugin are used to retreive system information usefull for the core plugin. There are different kind of sensor plugin, in this vJoule version three plugin types are implemented :
    • cpu plugin that retreives the energy consumption of the CPU of the system, (rapl)
    • ram plugin that retreives the energy consumption of the RAM of the system (rapl)
    • gpu plugin that retreives the energy consumption of the GPUs of the system (rapl, nvidia)

To monitor your processes consumption the divider core plugin will come in handy. This documentation will mainly focus on this core plugin.

You currently have two ways to interact with vJoule :

  • As a command line interface : useful for easy and quick usage
  • As a linux service : useful if you want to interact with vJoule in a program, and monitor more complex applications.

Current limitations

vJoule cannot be used inside a virtual machine as it needs direct access to the hardware.