PSU Energy - DC - RAPL Machine

What it does#

This metric provider reads the energy of the Platform (PSYS) domain from the Running Average Power Limit (RAPL) interface via a machine specific register (MSR) that is present on some Intel processor based notebook devices. In depth information about RAPL can be found in the Intel Software Developer Manual.

This MSR keeps a running count of the energy used in a specified domain in microJoules. This metric provider specifically reads from the energy-psys domain, which gives you the energy used by potentially the whole machine. The exact implementation what exactly falls under the PSYS domain is up to the manufacturer of the machine and in doubt you should contact the manufacturer.

We have tested this domain on modern Framework notebooks and the domain includes here at least all of the CPU, DRAM as well as the display.

Setup#

Please look at RAPL installation

Technical specs#

• Time resolution: up to 976 micro-seconds (depending on production year of the CPU)
• Energy resolution: up to 15.3 micro-Joules (depending on production year of the CPU)

Classname#

• PsuEnergyDcRaplMsrMachineProvider

Metric Name#

• psu_energy_dc_rapl_msr_machine

Input Parameters#

• Args:
  • i: specifies interval in milliseconds between measurements
  • p: measure the PSYS domain instead of the CPU package

Without -p the binary measures the CPU package. The Green Metrics Tool always adds this switch, so when calling the binary directly you have to supply it yourself:

./metric-provider-binary -i 100 -p

Output#

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

TIMESTAMP ENERGY_OUTPUT PSYS_ID

Where:

• TIMESTAMP: Unix timestamp, in microseconds
• ENERGY_OUTPUT: Energy used during interval, in micro Joules
• PSYS_ID: ID of the PSYS domain. Actually this should always be PSYS_0, since we have never seen a device with more then one domain or more than one CPU chip (which also creates multiple domains in case), so we could not verify. If you experience inconsistencies here contact us please.

Example output:

1712641603443421 8092 PSYS_0
1712641604443831 8047 PSYS_0

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. The check accepts Intel CPUs of family 6 as well as AMD CPUs of family 17h / 19h. Any other vendor or family aborts the provider.

The source knows the following CPU models, which are used to determine which RAPL domains a chip exposes:

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_ATOM_DENVERTON, CPU_TIGER_LAKE, CPU_AMD_FAM17H

Passing the CPU check does not guarantee that the PSYS domain is actually present, as it is read from the Intel MSR_PLATFORM_ENERGY_STATUS register. The provider therefore verifies on startup that the register returns a plausible value and aborts if it does not.

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.