Operating System Support for NVM+DRAM Hybrid Main Memory

For several decades, general-purpose CPUs have used DRAM for main memory. DRAM has many good features, and has benefited from Moore's Law, but DRAM is not perfect: it is relatively expensive in power and cost, as a fraction of an entire computer, and it is hard to put enough of it near a CPU. These problems are especially pressing in "scale-out" server farms, where one want both increased server density and reduced heat density.