The title of this paper is slightly misleading. A better title would be “Memory Coherence in Shared Virtual Memory Systems for a Small Number of Loosely Coupled Multiprocessors.” The alternate title gives a better description of what is to be covered and only withholds the results.

The paper considers two general classes of algorithms with many variations; both centralized manager and distributed manager algorithms manage the coherence of virtual memory on a page basis. In both cases, when a page is updated, all users of the page are notified by means of network messages and each must update its copy of the page in order to maintain coherence.

In addition to theoretical considerations and proofs, which are found in extensive appendices, the paper offers the results of experiments done on a small network of workstations (fewer than nine). This section is most enlightening, showing both problem areas in which the speedup is linear (eight processors produce a speedup of eight) and areas in which speedup is highly nonlinear (eight processors produce a speedup of about three). The authors justify the results of the experiments and quantify the effects of the manager algorithms. An extensive bibliography adds considerable value to the paper for any researcher in the area of distributed multicomputers.