Voltage Island-Aware Energy-Efficient Scheduling of Parallel Streaming Tasks on Many-Core CPUs

For multi- and many-core CPUs, dynamic voltage and frequency scaling (DVFS) for individual cores provides an effective way for energy-efficient execution of applications. However, this requires additional hardware within the chip that regulates voltage and frequency for each hardware sub-component that can be scaled separately. Because of the significant cost of this control hardware, it is often not realistic to provide such a regulator for each individual core. Instead, chip manufacturers group cores into islands consisting of multiple cores with a common regulator, and energy optimizing solutions must take this constraint into account when assigning frequencies to jobs and cores. Crown Scheduling is a technique for the combined resource allocation, mapping and discrete DVFS-level selection for actor networks consisting of moldable parallel streaming tasks for energy efficient execution given a throughput constraint. We extend crown scheduling to compute correct schedules also in the presence of DVFS islands constraints. We find that, for most task sets, the crown scheduler computes almost equally good schedules for target architectures with and without island constraints.