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CPU Energy Meter

CPU Energy Meter is a Linux tool that allows to monitor power consumption of Intel CPUs at fine time granularities (few tens of milliseconds). Power monitoring is available for the following power domains:

• per package domain (CPU socket)
• per core domain (all the CPU cores on a package)
• per uncore domain (uncore components, e.g., integrated graphics on client CPUs)
• per memory node (memory local to a package, server CPUs only)
• per platform (all devices in the platform that receive power from integrated power delivery mechanism, e.g., processor cores, SOC, memory, add-on or peripheral devices)

To do this, the tool uses a feature of Intel CPUs that is called RAPL (Running Average Power Limit), which is documented in the Intel Software Developers Manual, Volume 3B Chapter 14.9. RAPL is available on CPUs from the generation Sandy Bridge and later. Because CPU Energy Meter uses the maximal possible measurement interval (depending on the hardware this is between a few minutes and an hour), it causes negligible overhead.

CPU Energy Meter is a fork of the Intel Power Gadget and developed at the Software Systems Lab of the Ludwig-Maximilians-Universität München (LMU Munich) under the BSD-3-Clause License.

Installation

For Debian or Ubuntu the easiest way is to install from our PPA:

sudo add-apt-repository ppa:sosy-lab/benchmarking
sudo apt install cpu-energy-meter

Alternatively, you can download our .deb package from GitHub and install it with apt install ./cpu-energy-meter*.deb.

Dependencies of CPU Energy Meter are libcap, which is available on most Linux distributions in package libcap (e.g., Fedora) or libcap2 (e.g, Debian and Ubuntu: sudo apt install libcap2), and a Linux kernel with the MSR module (available by default)

Alternatively, for running CPU Energy Meter from source (quick and dirty):

sudo apt install libcap-dev
sudo modprobe msr
make
sudo ./cpu-energy-meter

It is also possible (and recommended) to run CPU Energy Meter without root. To do so, the following needs to be done:

• Load kernel modules msr and cpuid.
• Add a group msr.
• Add a Udev rule that grants access to /dev/cpu/*/msr to group msr (example).
• Run chgrp msr, chmod 2711, and setcap cap_sys_rawio=ep on the binary (make setup is a shortcut for this).

The provided Debian package in our PPA and on GitHub does these steps automatically and lets all users execute CPU Energy Meter.

How to use it

cpu-energy-meter [-d] [-e sampling_delay_ms] [-r]

The tool will continue counting the cumulative energy use of all supported CPUs in the background and will report a key-value list of its measurements when it receives SIGINT (Ctrl+C):

+--------------------------------------+
| CPU-Energy-Meter            Socket 0 |
+--------------------------------------+
Duration                  2.504502 sec
Package                   3.769287 Joule
Core                      0.317749 Joule
Uncore                    0.010132 Joule
DRAM                      0.727783 Joule
PSYS                     29.792603 Joule

To get intermediate measurements, send signal USR1 to the process.

Optionally, the tool can be executed with parameter -r to print the output as a raw (easily parsable) list:

cpu_count=1
duration_seconds=3.241504
cpu0_package_joules=4.971924
cpu0_core_joules=0.461182
cpu0_uncore_joules=0.053406
cpu0_dram_joules=0.953979
cpu0_psys_joules=38.904785

The parameter -d adds debug output. By default, CPU Energy Meter computes the necessary measurement interval automatically, this can be overridden with the parameter -e.