Optimizated Allocation of Data Variables to PCM/DRAM-based Hybrid Main Memory for Real-Time Embedded Systems

Phase-change memory (PCM) has many advantages compared to conventional DRAM, including nonvolatility, low static energy consumption, and high reliability. Its drawbacks include limited write-endurance and higher energy consumption for write operations. We consider a hybrid main memory consisting of PCM and DRAM at the same level of the memory hierarchy, and address the problem of partitioning and allocating data variables in a multitasking system to either memory type to minimize the energy consumption in the hyper-period while respecting the user-specified upper bounds on CPU utilization. We present an optimal integer linear programming (ILP) formulation and a heuristic algorithm with polynomial time complexity.