Questions about measurement

[danglotb]

Hello.
I read this in the official documentation of pyJoules:

Here are some basic usages of pyRAPL. Please note that the reported energy consumption is not only the energy consumption of the code you are running. This includes the global energy consumption of all the process running on the machine during this period, thus including the operating system and other applications.

That is why we recommend to eliminate any extra programs that may alter the energy consumption of the machine hosting experiments and to keep only the code under measurement (i.e., no extra applications, such as graphical interface, background running task…). This will give the closest measure to the real energy consumption of the measured code.

Is it also true for the other measurement tools such as PowerAPI and Jjoules?

Thank you very much.

[rouvoy]

Hi,

This is true for pyJoules and Jjoules, which are using the RAPL sensor to acquire energy measurements (in Joules).
However, PowerAPI builds on RAPL to isolate the power consumption (in Watts) of every single process running on a machine.

[danglotb]

Hi @rouvoy

Thank you very much for this clarification.

While all the tools are built/use RAPL, they measure something different but related (W = J / T).

Could it be possible to isolate the energy measurements for pyJoules and Jjoules?

What is the difference between "use" RAPL and "build" on RAPL?

I guess some of the explanation is in

SmartWatts: Self-Calibrating Software-Defined Power Meter for Containers: G. Fieni, R. Rouvoy, L. Seinturier. IEEE/ACM International Symposium on Cluster, Cloud and Grid Computing (CCGrid). May 2020, Melbourne, Australia
imma right?

Thank you very much!

[rouvoy]

Energy and Power are indeed related. RAPL reports raw energy measurements that we directly use in pyJoules/Jjoules to sample the energy consumption of code snippets. In PowerAPI, we process the raw energy measurements to infer power models and therefore report on the power consumption in real-time (the paper explains that in-depth indeed :) ).

[danglotb]

Okay, thank you very much for the clarification, that helps a lot!

[danglotb]

Hello,

I'm running PowerAPI/Smartwatts/Grafana/InfluxDB and I would like to know what it is the measurement unit on the y-axis of Grafana? A priori, it is in Watt(W) since we measure the Power, but I prefer to check with you.

Thank you very much.

[altor]

Yes, the unit is Watt