SPX64: A Scratchpad Memory for General-purpose Microprocessors

General-purpose computing systems employ memory hierarchies to provide the appearance of a single large, fast, coherent memory. In special-purpose CPUs, programmers manually manage distinct, non-coherent scratchpad memories. In this article, we combine these mechanisms by adding a virtually addressed, set-associative scratchpad to a general purpose CPU. Our scratchpad exists alongside a traditional cache and is able to avoid many of the programming challenges associated with traditional scratchpads without sacrificing generality (e.g., virtualization). Furthermore, our design delivers increased security and improves performance, especially for workloads with high locality or that interact with nonvolatile memory.