Variorum is an extensible, vendor-neutral library for exposing power and performance capabilities of low-level hardware dials across diverse architectures in a user-friendly manner. It is part of the ECP Argo Project, and is a key component for node-level power management in the HPC PowerStack Initiative. Variorum provides vendor-neutral APIs such that the user can query or control hardware dials without needing to know the underlying vendor’s implementation (for example, model-specific registers or sensor interfaces). These APIs enable application developers to gain a better understanding of power, energy, and performance through various metrics. Additionally, the APIs may enable system software to control hardware dials to optimize for a particular goal. Variorum focuses on ease of use and reduced integration burden in applications, which it accomplishes by providing:

  • Examples which demonstrate how to use Variorum in a stand-alone program.

  • A performance analysis sampler that runs alongside the application.

  • A JSON API to allow integration with higher-level system software, such as job schedulers, distributed monitoring frameworks, or application-level runtime systems.

Variorum Project Resources

Online Documentation

Github Source Repo

Issue Tracker

Lead Developers

  • Stephanie Brink (LLNL)

  • Aniruddha Marathe (LLNL)

  • Tapasya Patki (LLNL)

  • Barry Rountree (LLNL)

  • Kathleen Shoga (LLNL)

Code Of Conduct

See Contributor Covenant Code of Conduct.


This research was supported by the Exascale Computing Project (17-SC-20-SC), a joint project of the U.S. Department of Energy’s Office of Science and National Nuclear Security Administration, responsible for delivering a capable exascale ecosystem, including software, applications, and hardware technology, to support the nation’s exascale computing imperative.

Variorum Documentation

Indices and tables