HeteroMates: Providing high dynamic power range on client devices using heterogeneous core groups

This paper presents HeteroMates, a solution that uses heterogeneous processors to extend the dynamic power/performance range of client devices. By using a mix of different processors, HeteroMates offers both high performance and reduced power consumption. The solution uses core groups as the abstraction that groups a small number of heterogeneous cores to form a single execution unit. Group heterogeneity is exposed as multiple heterogeneity (H) states, an interface similar to the P-state interface already used for frequency scaling. An H-state controller governs H-state transitions based on dynamic policies maximizing performance or minimizing power consumption, while a `core switcher' transparently migrates tasks to the appropriate core, i.e., the one matching the chosen H-state. Experimental evaluations use real-world client applications and a unique experimental testbed comprised of heterogeneous cores and a shared uncore component. Results show that core groups can provide significant performance improvements while also lowering energy consumption for a diverse set of applications when compared to homogeneous processor configurations. Also demonstrated is the importance of `uncore' power in total SoC power consumption and the need for uncore power scalability when seeking to extend a platform's dynamic power range.