Collectd plugin "intel_cpu_energy"

This collectd plugin measures and reports the power usage of 2nd Generation (or later) Intel® Core™ processors.

It will report up to four values for each physical processor: the accumulated energy usage (in Joules) for the "package", "core", "uncore", and "dram" domains, as reported by the CPU. Not all domains are supported by all CPU models, so some of them might be missing on your system.

The code for these measurements is based on Intel's Power Gadget 2.5 for Linux.

Requirements

To read the CPU's internal energy measurements, the plugin requires write access to the CPU's model-specific registers (MSRs). For this, the msr kernel module has to be loaded. In addition, write access to /dev/cpu/*/msr, along with the SYS_RAWIO capability, is required, but since collectd runs its plugins with root privileges anyway, those permissions should be available by default.

To build the module, you will need to have the collectd-dev package installed (the package name might differ on non-Debian-based distributions).

The module has been successfully tested with version 5.8-3ubuntu2 of collectd-dev (on Ubuntu 18.04), but collectd's plugin API can be highly unstable, even between minor versions, so it might not work out of the box with other versions.

Building and installing

Collectd's plugin API was moved to a different directory in commit 216c624 and changed to use a different time representation in commit cce1369. These changes will be included in Collectd versions 5.5.0 and higher.

Collectd version >= 5.5.0

For those new version, simply run the following:

make clean all
sudo make install
service collectd restart

Usage

The plugin will produce data sets named according to the pattern

${host}/intel_cpu_energy-cpu{0..}/energy-{package,core,uncore,dram}

Each data point will contain the accumulated energy consumption in Joules (= Watt seconds) since the last (re-)start of collectd.

The value is internally processed as a double-precision floating point number, so you shouldn't encounter any problems with overflows. Because of potential overflow issues the update interval should not be longer than 60 seconds.