Hybrid RAM system's development APIs

Hybrid architecture can be more favorable by providing both best of the two types of memory, volatile and persistent types. Since there is no need of power to store the data, it is possible to provide faster booting time from completely off state. However, because of the limited number of writes can be performed on PRAM devices, we need to manage it well in order to get longest lifetime. Our proposed system provides APIs to develop custom wear-level schemes and deploy it easily to the system. We defined APIs specifications which include memory management and protection, to provide further protection to the system from memory attack. We focused on phase-change memory (PCM) as the representation of Persistent RAM (PRAM), since it is the most probable candidate for DRAM replacement. We observed that there are rooms for improvements to elongate PCM lifetime, such as the shared library objects loading to the BPRAM, separation of three memory region in process (i.e. code, data, stack regions), moving rarely modified blocks of RAM to the BPRAM, and also the capability of saving only important states when desired by the application developers.