Replacement Policies for Heterogeneous Memories

Abstract

As non-volatile memory is introduced alongside traditional memory, new mechanisms for managing memory are becoming necessary. In this paper, we propose the two variable-space heterogeneous VMIN (H-VMIN) and heterogeneous WS (H-WS) policies for flat DRAM-PCM heterogeneous architectures, which derive from the earlier VMIN and WS policies. After a page reference, H-VMIN keeps the page in DRAM/PCM/disk based on the time until its next access. It is optimal, but requires future information. H-WS keeps the page in DRAM for a certain time and then in PCM for a longer time if it has still not been reused, and finally evicts it to disk.