An Object-Based Memory Architecture

Ifor Williams and Mario Wolczko

In Implementing Persistent Object Bases: Proceedings of the Fourth International Workshop on Persistent Object Systems, Alan Dearle, Gail M. Shaw, and Stanley B. Zdonik, editors, pages 114-130. Morgan Kaufmann Publishers, Inc., 1991.

Abstract

A typical implementation of an object store upon a conventional architecture sacrifices a good deal of performance in emulation overheads. In this paper we describe the design of a high-performance hardware-based object memory. This work forms a part of the Mushroom Project, which is constructing a high-performance architecture tailored for symbolic processing and especially object-oriented languages.

Alternatives in the design of an object-based memory system are presented. Each alternative is analysed using the results of simulations based on memory reference traces taken from a Smalltalk-80 system. The best of the alternatives is chosen and used as the basis for the Mushroom memory system.

The principal areas described and evaluated are:

Addressing formats suitable for Smalltalk-like object-based systems,
The parameters describing the novel object-based cache used in Mushroom, and
Schemes for object address translation.

The PostScript source is in several pieces: the main body, fig 1, fig 2, and fig 3.