Evaluation of Memory System Extensions

Abstract:

A traditional memory system for a uniprocessor consists of one or two
levels of cashe, a main memory and a backing store. One can extend
such a memory system by adding inexpensive but slower memories into the
memory hierarchy. This paper uses an experimental approach to evaluate
two methods of extending a memory system: direct and caching. The
direct method adds the slower memory into the memory hierarchy by
putting it at the same level as the main memory, allowing the CPU to
access the slower memories directly; whereas the caching method puts
the slower memory between the main memory and the backing store, using
the main memory as a cache for the slower memory. We have implemented
both approaches and our experiments indicate that applications with
very large data structures can benefit significantly using an extended
memory system, and that the direct approach outperforms the caching
approach in memory-bound applications.