VirtualWatts is a software-defined power meter based on the PowerAPI toolkit. VirtualWatts is a configurable software that can estimate the power consumption of software inside a Virtual Machine (VM) in real-time.

VirtualWatts use the estimation of energy consumption of the VM, computed by SmartWatts, and the cpu usage of each process inside the VM, computed by Procfs Sensor.


You can use the following script to install VirtualWatts and Procfs Sensor.

From pypi

pip install virtualwatts

From docker

docker pull powerapi/virtualwatts-formula

From deb file

Download the .deb file from the latest release

Install virtualwatts with sudo apt install ./python3-virtualtwatts_0.1.1-1_all.deb


For running the VirtualWatts formula we'll need several things:

  • Smartwatts running on the host machine
  • A file SW_output, shared with the host that will be used as database
  • The Procfs sensor running inside the VM
  • A configuration file for each.

VirtualWatts configuration :

    'verbose': True,
    "input": {
        "puller_filedb": {
            "type": "filedb",
            "model": "PowerReport",
            "filename": "SW_output"
        "puller_tcpdb": {
            "type" : "socket",
            "model": "ProcfsReport",
            "uri": "",
            "port": self.port
    "output": {
        "power_pusher": {
        "type": "influxdb",
        "model": "PowerReport",
        "uri": "",
        "port": 8086,
        "db": "test",
        "collection": "prep"
    "delay-threshold": 500,
    "sensor-reports-sampling-interval": datetime.timedelta(500)

Start by running Smartwatts with a filedb output. Then run virtualwatts using one of the following command line, depending on the installation you used:

  • via pip : python -m virtualwatts --config-file config_file.json
  • via docker docker run -t --net=host -v $(pwd)/config_file.json:/config_file.json powerapi/virtualwatts --config-file /config_file.json
  • via deb file : virtualwatts --config-file config_file.json

After that run the procfs sensor. Your power report will be provided in the influxdb. You can watch them in a grafana using the following tutorial