Date Awarded


Document Type


Degree Name

Doctor of Philosophy (Ph.D.)


Computer Science


Phil Kearns


Distributed shared memory (DSM) provides the illusion of shared memory processing to programs running on physically distributed systems. Many of these systems are connected by a broadcast medium network such as Ethernet. In this thesis, we develop a weakly coherent model for DSM that takes advantage of hardware-level broadcast. We define the broadcast DSM model (BDSM) to provide fine-grained sharing of user-defined locations. Additionally, since extremely weak DSM models are difficult to program, BDSM provides effective synchronization operations that allow it to function as a stronger memory. We show speedup results for a test suite of parallel programs and compare them to MPI versions.;To overcome the potential for message loss using broadcast on an Ethernet segment we have developed a reliable broadcast protocol, called Pipelined Broadcast Protocol (PBP). This protocol provides the illusion of a series of FIFO pipes among member process, on top of Ethernet broadcast operations. We discuss two versions of the PBP protocol and their implementations. Comparisons to TCP show the predicted benefits of using broadcast. PBP also shows strong throughput results, nearing the maximum of our 10Base-T hardware.;By combining weak DSM and hardware broadcast we developed a system that provides comparable performance to a common message-passing system, MPI. For our test programs that have all-to-all communication patterns, we actually see better performance than MPI. We show that using broadcast to perform DSM updates can be a viable alternative to message passing for parallel and distributed computation on a single Ethernet segment.



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