Core groups: System abstractions for extending the dynamic range of client devices using heterogeneous cores

Mobile devices and applications exhibit highly diverse behavior in their usage and power/performance requirements. In order to accommodate such diversity, this paper presents ‘HeteroMates’ system that uses heterogeneous processors to extend the dynamic power/performance range of client devices, i.e., offer both high performance and reduced power consumption. It proposes core group 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. Further, the core group abstraction is extended to a multicore group to allow multiple cores within a group to be active concurrently. Also demonstrated is the importance of ‘uncore’ power in total SoC power consumption and the need for uncore-aware operation and uncore power scalability when seeking to extend a platform's dynamic power/performance range using heterogeneity. Experimental evaluations use real-world client applications and a unique experimental testbed comprised of heterogeneous cores and a shared uncore component. Results show that HeteroMates can provide significant performance improvements while also lowering energy consumption for a diverse set of applications when compared to homogeneous processor configurations.