Prototyping a Hybrid Main Memory Using a Virtual Machine Monitor

We use a novel virtualization-based approach for computer architecture performance analysis. We present a case study analyzing a hypothetical hybrid main memory, which consists of a first-level DRAM augmented by a 10-100x slower second-level memory. This architecture is motivated by the recent emergence of lower-cost, higher-density, and lower-power alternative memory technologies. To model such a system, we customize a virtual machine monitor (VMM) with delay-simulation and instrumentation code. Benchmarks representing server, technical computing, and desktop productivity workloads are evaluated in virtual machines (VMs). Relative to baseline all-DRAM systems, these workloads experience widely varying performance degradation when run on hybrid main memory systems which have significant amounts of second-level memory.