Now that vJoule is installed on your computer, let's try it. Remember that vJoule is available through two interfaces:

• A command line interface, useful for simple and quick usage
• A linux service, useful if you need to embed vJoule in a program

This section presents just a basic test to make sure vjoule is properly installed. A more thorough tutorial is presented in the section Simple core.

vJoule is available through a linux systemd service.

$ sudo systemctl start vjoule_service

You can verify that the service is up either by checking with systemctl:

$ sudo systemctl status vjoule_service

Or by checking for the log file :

$ cat /etc/vjoule/service.log

The default configuration of vJoule only retreive RAPL information. See section Simple core, for more configuration options.

vJoule CLI is conveniently called vjoule. You can use it to estimate the energy consumption of a given command, like this:

$ # Here, ls is not a subcommand of vjoule
$ # We mesure the energy consummed by the ls command execution
$ vjoule ls

time	21ms856µs
PDU	0.00 J
CPU	0.17 J
RAM	0.03 J
GPU	0.02 J

You can also use vjoule on a command that needs parameters. In this case, we will estimate the energy consumption of the stress command.

$ vjoule stress --cpu 2 --timeout 2s
stress: info: [169371] dispatching hogs: 2 cpu, 0 io, 0 vm, 0 hdd
stress: info: [169371] successful run completed in 2s


time	2s53ms193µs
PDU	79.20 J
CPU	40.61 J
RAM	0.00 J
GPU	0.00 J

Of course, you can use vjoule to run, say, a Python script.

$ vjoule python myscript.py

time	1s670ms197µs
PDU	70.40 J
CPU	35.71 J
RAM	2.25 J
GPU	1.78 J