Towards Memory Specialization: A Case for Long-Term and Short-Term RAM

Both SRAM and DRAM have stopped scaling: there is no technical roadmap to reduce their cost (per byte/GB). As a result, memory now dominates system cost. This paper argues for a paradigm shift from today's simple memory hierarchy toward specialized memory architectures that exploit application-specific access patterns. Rather than relying solely on traditional off-chip DRAM and on-chip SRAM, we envisage memory systems equipped with additional types of memory whose performance trade-offs benefit workloads through non-hierarchical optimization. We propose two new memory classes deserving explicit OS support: long-term RAM (LtRAM) optimized for read-intensive data with long lifetimes, and short-term RAM (StRAM) designed for transient, frequently-accessed data with short lifetimes. We explore underlying device technologies that could implement these classes, including their evolution and their potential integration into current system designs given emerging workload requirements. We identify critical research challenges to realize what we believe is a necessary evolution toward more efficient and scalable computing systems capable of meeting future demands.