Performance enhancements to the Active Memory System

The Active Memory System - a garbage collected memory module - was introduced as a way to provide hardware support for garbage collection in embedded systems. The major component in the design was the Active Memory Processor (AMP) that utilized a set of bit-maps and a combinational circuit to perform mark-sweep garbage collection. The design can achieve constant time for both allocation and sweeping. In this paper two enhancements are made to the design of AMP so that it can perform one-bit reference counting that postpones the need to perform garbage collection. Moreover, a caching mechanism is also introduced to reduce the hardware cost of the design. The experimental results show that the proposed modification can reduce the number of garbage collection invocations by 76%. The speed-up in marking time can be as much as 5.81. With the caching mechanism, the hardware cost can be as small as 27 K gates and 6 KB of SRAM.