Getting Started

GEOPM (Global Extensible Open Power Manager) is a software framework that enables users and administrators to safely and securely modify hardware settings for the duration of a process session. This unique capability allows for dynamic, user-driven power and performance tuningβ€”enabling energy efficiency and workload optimization that is not possible with traditional system tools.

GEOPM is deployed in production on large-scale systems (e.g., Aurora) and is used by HPC centers and cloud providers to help users and administrators meet power, performance, and sustainability goals.

Note

For a quick reference on GEOPM commands, see:

⚑ Why Use GEOPM?

GEOPM provides a secure userspace interface for modifying hardware controls (such as CPU power limits and frequencies) for the duration of a user session or job. This means:

  • Users can safely adjust hardware settings (e.g., power limits, frequencies) for their own jobs, without affecting other users or the system as a whole.

  • All changes are automatically reverted at the end of the session, ensuring system integrity and preventing persistent misconfiguration.

  • Administrators retain fine-grained control over which users and groups can access which hardware features, with full auditability.

This capability is especially valuable for:

  • HPC and cloud users who want to optimize performance per watt for their workloads.

  • System administrators who want to enable user-driven tuning while maintaining security and stability.

  • Sustainability initiatives that require power capping or energy-aware scheduling.

Note

For more information on the GEOPM Access Service see User Guide for GEOPM Access Service.

πŸš€ Example: Power Management for Memory-Bound HPC Workloads

GEOPM is particularly effective for memory-bound workloads, where reducing CPU power limits can lower energy consumption with minimal impact on performance.

Key Takeaways:

  • For memory-bound workloads, reducing CPU package power limit via GEOPM can significantly lower system power consumption with minimal impact on performance, up to a certain threshold.

  • The optimal setting (β€œsweet spot”) depends on the workload behavior and user’s preference for balancing energy efficiency and performance.

  • This demonstrates the practical value of exposing user-controllable power management through GEOPM, enabling end users to optimize for performance per watt based on workload characteristics.

πŸ”§ How to Set Power Limits with GEOPM

GEOPM provides command-line tools to read and write hardware settings. The most common use case is to set a power limit or frequency limit for your job or session.

Example: Setting and Reading CPU Power Limit

# Read the default power limit for package 0
geopmread CPU_POWER_LIMIT_DEFAULT package 0

# Reduce the power limit by 100W and apply it
NEW_LIMIT=$(( $(geopmread CPU_POWER_LIMIT_DEFAULT package 0) - 100 ))
geopmwrite CPU_POWER_LIMIT_CONTROL package 0 $NEW_LIMIT

# Verify the new power limit
geopmread CPU_POWER_LIMIT_CONTROL package 0

Example: Measuring Power Consumption During a Job

# Read initial energy
ENERGY_BEGIN=$(geopmread CPU_ENERGY package 0)
sleep 10
ENERGY_END=$(geopmread CPU_ENERGY package 0)
python3 -c "print(f'Package 0 energy: {float($ENERGY_END) - float($ENERGY_BEGIN)} joules')"

Note

For more details, see the geopmread(1) – query platform information.

Example: Detailed Power Monitoring with geopmsession

printf "TIME board 0\nCPU_ENERGY * *" | geopmsession -r- -p 0.01 -- sleep 1

This will output a time series of energy readings for each package during the execution of the sleep 1 command.

Note

For more details, see the job execution section.

πŸ›‘οΈ Security and Safe Access

GEOPM is designed to be secure and robust for multi-user environments:

  • Session-based control: All hardware changes are scoped to the user’s session and reverted at the end.

  • Access control: Administrators can grant or restrict access to specific hardware features per user or group.

  • Auditability: All changes are logged and can be audited.

  • No persistent changes: Hardware is always restored to a safe state after each session.

Note

For more information, see the Security Guide guide.

πŸ’» Install GEOPM

To check if GEOPM is installed on your system you may try querying the command line interfaces for the GEOPM version. For example:

geopmread --version

Note

Follow the Install Guide for details about how to install GEOPM if this command errors with command not found.

πŸ—ƒοΈ Platform Topology

GEOPM provides tools to discover the hardware topology of your system, including domains such as board, package, core, cpu, memory, and more. While this is not unique to GEOPM, it is essential for advanced tuning and control.

Note

For more information on the domain types and topology APIs, see:

πŸ”¬ Reading Telemetry

GEOPM enables users to read a wide variety of hardware telemetry signals (e.g., frequency, power, energy, temperature) at different domains. This is useful for real-time monitoring and analysis, but the unique value of GEOPM is in its safe, session-based control features.

Note

For more information, see:

βš™οΈ Enact Hardware-based Settings

GEOPM enables users to write hardware controls (e.g., set power limits, frequencies) safely and securely. See the section below for examples and the geopmwrite documentation for details.

Note

For more information, see:

πŸ“ Measure Performance

GEOPM provides runtime tools for collecting telemetry and profiling applications, including integration with MPI and OpenMP.

Note

For more information, see the Measure Performance section of the Tutorial for example usage and details.