Dataflow architectures tolerate long unpredictable com-munication delays and support generation and coordi-nation of parallel activities directly in hardware, rather than assuming that program mapping will cause these issues to disappear. However, the proposed mecha-nisms are complex and introduce new mapping com-plications. This paper presents a greatly simplified ap-proach to dataflow execution, called the explicit token store (ETS) architecture, and its current realization in Monsoon. The essence of dynamic datallow execution is captured by a simple transition on state bits associ-ated with storage local to a processor. Low-level storage management is performed by the compiler in assigning nodes to slots in an activation frame, rather than dy-namically in hardware. The processor is simple, highly pipelined, and quite general. It may be viewed as a generalization of a fairly primitive von Neumann archi-tecture. Although the addressing capability is restric-tive, there is exactly one instruction executed for each action on the dataflow graph. Thus, the machine ori-ented ETS model provides new understanding of the merits and the real cost of direct execution of dataflow graphs. 1

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A Functional Database Phil Trinder D.Phil. Thesis Wolfson College Michaelmas Term, 1989 This thesis explores the use of functional languages to implement, manipulate and query databases. Implementing databases. A functional language is used to construct a database manager that allows efficient and concurrent access to shared data. In contrast to the locking mechanism found in conventional databases, the functional database uses data dependency to provide exclusion. Results obtained from a prototype database demonstrate that data dependency permits an unusual degree of concurrency between operations on the data. The prototype database is used to exhibit some problems that seriously restrict concurrency and also to demonstrate the resolution of these problems using a new primitive. The design of a more realistic database is outlined. Some restrictions on the data structures that can be used in a functional database are also uncovered. Manipulating databases. Functions over the database a...

Programming parallel computers remains a difficult task. An ideal programming environment should enable the user to concentrate on the problem solving activity at a convenient level of abstraction, while managing the intricate low-level details without sacrificing performance. This thesis investigates a model of parallel programming based on the BirdMeertens Formalism (BMF). This is a set of higher-order functions, many of which are implicitly parallel. Programs are expressed in terms of functions borrowed from BMF. A parallel implementation is defined for each of these functions for a particular topology, and the associated execution costs are derived. The topologies which have been considered include the hypercube, 2-D torus, tree and the linear array. An analyser estimates the costs associated with different implementations of a given program and selects a cost-effective one for a given topology. All the analysis is performed at compile-time which has the advantage of reducing run-...

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We have implemented a parallel graph reducer on a commercially available shared memory multiprocessor (a Sequent Symmetry TM ), that achieves real speedup compared to a a fast compiled implementation of the conventional Gmachine. Using 15 processors, this speedup ranges between 5 and 11, depending on the program. Underlying the implementation is an abstract machine called the h; Gi-machine. We describe the sequential and the parallel h; Gi-machine, and our implementation of them. We provide performance and speedup figures and graphs. 1 Introduction Compiled graph reduction, as embodied in the G-machine and the Lazy ML compiler [Aug84, Joh84] has proved to be rather an efficient way to implement lazy functional languages on conventional machines. In this paper we report our results on extending these compilation techniques for parallel computers. We have implemented a parallel graph reduction system, a modified parallel G-machine, in a commercially available shared memory multicomput...

Dataflow architectures tolerate long unpredictable com-munication delays and support generation and coordi-nation of parallel activities directly in hardware, rather than assumiug that program mapping will cause these issues to disappear. However, the proposed mecha-nisms are complex and introduce new mapping com-plications. This paper presents a greatly simplified ag preach to dataflow execution, called the ezplicil ioken store (ETS) architecture, and its current realization in Monsoon. The essence of dynamic dataflow execution is captured by a simple transition on state bits associ-ated with storage local to a processor. Low-level storage management is performed by the compiler in assigning nodes to slots in an acliunfion frame, rather than dy-namically in hardware. The processor is simple, highly pipelined, and quite general. It may be viewed as a generalization of a fairly primitive von Neumann archi-tecture. Although the addressing capability is restric-tive, there is exactly one instruction executed for each action on the dataflow graph. Thus, the machine ori-ented ETS model provides new understanding of the merits and the real cost of direct execution of dataflow graphs. 1