CPU Energy Package - RAPL System

What it does #

This metric provider reads the energy of the CPU Package from the Running Average Power Limit (RAPL) interface via a machine specific register (MSR) that is present on most modern Intel processers. In depth information about RAPL can be found here.

This MSR keeps a running count of the energy used in a specified domain in microJoules. This metric provider specifically reads from the energy-pkg domain, which gives you the energy used by all the domains.

Classname #

• CpuEnergyRaplMsrSystemProvider

Input Parameters #

• Args:
  • i: specifies interval in milliseconds between measurements
    • from RAPL documentation: RAPL can only measure until 1ms resolution

> ./metric-provider-binary -i 100

Output #

This metric provider prints to Stdout a continuous stream of data. The format of the data is as follows:

TIMESTAMP ENERGY_OUTPUT

Where:

• TIMESTAMP: Unix timestamp, in microseconds
• ENERGY_OUTPUT: Energy used during interval, in micro Joules

Example output:

screenshot example

Any errors are printed to Stderr.

How it works #

We use a modified version of the open source code found here: (github)

First we check if the CPU is compatible by reading the cpu info from /proc/cpuinfo and checking against the following list of supported CPUs:

CPU_SANDYBRIDGE, CPU_SANDYBRIDGE_EP, CPU_IVYBRIDGE, CPU_IVYBRIDGE_EP, CPU_HASWELL, CPU_HASWELL_ULT, CPU_HASWELL_GT3E, CPU_HASWELL_EP, CPU_BROADWELL, CPU_BROADWELL_GT3E, CPU_BROADWELL_EP, CPU_BROADWELL_DE, CPU_SKYLAKE, CPU_SKYLAKE_HS, CPU_SKYLAKE_X, CPU_KNIGHTS_LANDING, CPU_KNIGHTS_MILL, CPU_KABYLAKE_MOBILE, CPU_KABYLAKE, CPU_ATOM_SILVERMONT, CPU_ATOM_AIRMONT, CPU_ATOM_MERRIFIELD, CPU_ATOM_MOOREFIELD, CPU_ATOM_GOLDMONT, CPU_ATOM_GEMINI_LAKE, CPU_TIGER_LAKE

It reads the values from /dev/cpu/%d/msr

Note that since it reads the energy used by the entire system, any other load that your system has during a program’s usage run will also be captured in the energy measurement.