Memory Power Management for Java Processors Using Heap Partitioning and Power Gating

Power consumption is an important design parameter for battery operated devices, and an especially sensitive issue in embedded Java systems. This paper presents a solution to reduce leakage power consumption of the heap memory characteristic of Java processors. By partitioning the heap into several memory banks and taking advantage of a compacting garbage collector, our method dynamically powers off inactive regions. The technique has been designed and evaluated for JOP, a Java Optimized Processor [14], and further implemented and verified in a 65nm CMOS technology using STM low-power high Vt (LPHVT) [16] standard cell libraries. Experiments show that our method accurately follows the memory utilization profile in powering on and off banks, achieving at least 50% leakage power reduction. The performance, area and power penalty introduced by the additional hardware are negligible.