Endurance-Aware Allocation of Data Variables on NVM-Based Scratchpad Memory in Real-Time Embedded Systems

Non-Volatile Memory (NVM) has many benefits compared to the traditional SRAM, such as improved reliability and reduced power consumption, but it has long write latency and limited write endurance. Scratchpad Memory (SPM) is software-managed small on-chip memory for improving system performance and predicability. We consider SPM based on STT-RAM, a type of NVM with high performance and good endurance. We present algorithms for allocating data variables to SPM and distribute write activity evenly in the SPM address space, in order to achieve wear-leveling and prolong the lifetime of NVM. We present two optimization algorithms for minimizing system CPU utilization subject to NVM lifetime constraints: one is an optimal algorithm based on ILP, the other is an efficient heuristic algorithm that can obtain close-to-optimal solutions.