Exploration of Memory Hierarchy Configurations for Efficient Garbage Collection on High-Performance Embedded Systems

Modern embedded devices (e.g., PDAs, mobile phones) are now incorporating Java as a very popular implementation language in their designs. These new embedded systems include multiple applications that are dynamically launched by the user, which can produce very energy-hungry systems if the interactions between the applications and the garbage collectors (GCs) are not properly understood. In this paper we present a complete exploration, from an energy viewpoint, of the different possibilities of memory hierarchies for high-performance embedded systems when used by state-of-the-art GCs. Moreover, we explore the potential peformance improvement and energy reductions of using a scratchpad memory directed by the virtual machine to store critical code and data structures of the GCs; thus, enabling up to 40% performance improvements and 41% leakage reduction with respect to classical cache-based memory architectures. Our experimental results show that the key for an efficient low-power implementation of Java Virtual Machines (JVM) for high-performance embedded systems is the synergy between the GC choice, the memory architecture tuning, and the inclusion of power management schemes controlled by the JVM, exploiting knowledge of the used GC.