Hardware Supported Marking for Common Garbage Collections

Many mobile systems have to achieve both high performance and low memory usage, and the total performance of such the systems can be largely affected by the effectiveness of GC. Hence, the recent popularization of mobile devices makes the GC performance play one of the important roles on the wide range of platforms. The response performance degradation which is caused by suspending all processes for GC has been a well known potential problem. Therefore, GC algorithms have been actively studied and improved, but they still have not reached any fundamental solution. In this paper, we focus on the point that the same objects are redundantly marked during the GC procedure that is implemented on DalvikVM, one of the famous runtime environments for the mobile devices. Then we propose a hardware support technique for improving marking routine of GC. We installed a set of tables to a processor for managing marked objects, and by referring these tables, redundant marking for marked objects can be omitted. The result of the simulation experiment shows that the execution cycles of GC are reduced by 20.7% at a maximum, and 10.2% on average.