Energy Measurement

RAPL (CPU and DRAM Energy)

The Slurm also includes energy measurements using the RAPL interface.¹ The corresponding energy consumption is reported in the job output as shown on the previous page.

Manual Usage

To obtain the raw RAPL measurements, one can utilize the linux Power Capping Framework through the file system. All relevant attributes are located under /sys/devices/virtual/powercap/intel-rapl/ with the following subdirectories mapping to individual RAPL domains:

For each domain, the name file holds the name of the corresponing RAPL domain, the energy_uj file holds the current value of the counter in μJoules, and the max_energy_range_uj file the maximum value of this counter. Note that these counters will overflow rather quickly, so they must be read more than once per minute and account for this.

pyRAPL

However, manually reading the RAPL measurements is not so trivial. To get the energy consumption for a specific command in your job (running on the CPUs of a single node), proceed as follows:

First, install the required Python packages in a virtual environment.

# (Install Python dependencies)
ml python/3.11
python -m venv .venv
source .venv/bin/activate
pip install pyRAPL pymongo pandas

Then, inside of your job, wrap your command in a measurement to determine the energy it consumed.²

ml python/3.11
python -m venv .venv
source .venv/bin/activate
CMD="..." # TODO: Add with the command to measure
# Run CMD and measure energy consumption
python3 - <<EOF
import pyRAPL, os
pyRAPL.setup()
with pyRAPL.Measurement("rapl-measurement"):
    os.system("""$CMD""")
EOF
# The energy consumption per RAPL domain is printed

Additional Ressources

Additional information about RAPL can be found in the following resources:

• Vincent M. Weaver, “Reading RAPL energy measurements from Linux”
• pyRAPL (a software toolkit to measure the energy footprint of Python code)