EAR 4.3
Reference Manual
EAR Node Manager

Overview

The node daemon is the component in charge of providing any kind of services that requires privileged capabilities. Current version is conceived as an external process executed with root privileges.

The EARD provides the following services, each one covered by one thread:

  • Provides privileged metrics to EARL such as the average frequency, uncore integrated memory controller counters to compute the memory bandwidth, as well as energy metrics (DC node, DRAM and package energy).
  • Implements a periodic power monitoring service. This service allows EAR package to control the total energy consumed in the system.
  • Offers a remote API used by EARplug, EARGM and EAR commands. This API accepts requests such as get the system status, change policy settings or notify new job/end job events.

Requirements

When executed in production environments, EARD connects with EARDBD service, that has to be up before starting the node daemon, otherwise values reported by EARD to be stored in the database, will be lost.

Configuration

The EAR Daemon uses the $(EAR_ETC)/ear/ear.conf file to be configured. It can be dynamically configured by reloading the service.

Please visit the EAR configuration file page for more information about the options of EARD and other components.

Execution

To execute this component, these systemctl command examples are provided:

  • sudo systemctl start eard to start the EARD service.
  • sudo systemctl stop eard to stop the EARD service.
  • sudo systemctl reload eard to force reloading the configuration of the EARD service.

Log messages are generated during the execution. Use journalctl command to see eard message:

  • sudo journalctl -u eard -f

Reconfiguration

After executing a systemctl reload eard command, not all the EARD options will be dynamically updated. The list of updated variables are:

DefaultPstates
NodeDaemonMaxPstate
NodeDaemonVerbose
NodeDaemonPowermonFreq
SupportedPolicies
MinTimePerformanceAccuracy

To reconfigure other options such as EARD connection port, coefficients, etc., it must be stopped and restarted again.