Organization And Performance Of A Two-level Virtual-real Cache Hierarchy

Abstract

We propose and analyze a two-level carche organization that provides high memory bandwidth. The first-level cache is ac- cessed directly by virtual addresses. It is small, fast, and, with- out the burden of address translation, can easily be optimized to match the processor speed. The virtually-addressed cache is backed up by a large physically-addressed cache; this second- level cache provides a high hit ratio and greatly reduces mem- ory traffic. We show how the second-level cache can be easily extended to solve the synonym problem resulting from the use of a virtually-addressed cache at the first level. Moreover, the second-level cache can be used to shield the virtually-addressed first-level cache from irrelevant cache coherence interference. Finally, simulation results show that this organization has a performance advantage over a hierarchy of physically-addressed caches in a multiprocessor environment.