Demand-Aware NVM Capacity Management Policy for Hybrid Cache Architecture

摘要

Existing hybrid cache architecture (HCA) studies have concentrated on managing write-intensive blocks to relieve the write pressure on Non-volatile memory (NVM). However, they have overlooked that the capacity of NVM is also one of important factors affecting the number of write accesses to NVM. This research investigates the relationship between the size of NVM and the write counts of NVM to efficiently design a new algorithm to reduce the write counts of NVM in HCA. Based on the analysis, it is revealed that adjusting the capacity of NVM can decrease write requests to NVM if the miss rate does not grow. This discovery leads to the necessity of NVM capacity management policy such that the size of NVM is dynamically adjusted according to the demand of applications. To implement the policy, we propose a dynamic way adjusting algorithm which dynamically monitors the optimal number of NVM ways using the stack property and disabling the unnecessary NVM ways. The experiments are conducted for two HCAs with STT-RAM and PCM. The results show that proposed management policy reduces the write accesses to STT-RAM by 77.6% and PCM by 79.6%.