DescriptionThe power scaling challenges associated with exascale systems is a well-known issue. In this work, we introduce the Global Extensible Open Power Manager (GEOPM): a tree-hierarchical, open source runtime framework we are contributing to the HPC community to foster increased collaboration and accelerated progress toward software-hardware co-designed energy management solutions that address exascale power challenges and improve performance and energy efficiency in current systems. Through its plugin extensible architecture, GEOPM enables rapid prototyping of new energy management strategies. Different plugins can be tailored to the specific performance or energy efficiency priorities of each HPC center. To demonstrate the potential of the framework, this work develops an example plugin for GEOPM. This power rebalancing plugin targets power-capped systems and improves efficiency by minimizing job time-to-solution within a power budget. Our results demonstrate up to 30% improvements in the time-to-solution of CORAL system procurement benchmarks on a Xeon Phi cluster.