Communicating Mobile Processes

Welch, Peter H.; Barnes, Frederick R.M.

doi:10.1007/11423348_10

Cited by 78 publications

(51 citation statements)

References 11 publications

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“…Occam-pi [4] language is known for its simplicity, minimal run-time overhead and power to express parallelism. Occam-pi has built in semantics for concurrency and interprocess communication.…”

Section: Occam-pi Languagementioning

confidence: 99%

“…In contrast, the pi-calculus [3] allows modeling of dynamic constructions of channels and processes, which enables the dynamic connectivity of networks of processes. Thus, occam-pi [4], combining CSP with pi-calculus, seems to be an interesting approach to programming of run-time reconfigurable systems. A program in occam-pi is a composition of processes in which communication between the processes is managed by unbuffered message passing channels.…”

Section: Introductionmentioning

confidence: 99%

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Programming Real-Time Autofocus on a Massively Parallel Reconfigurable Architecture Using Occam-pi

Zain-ul-Abdin

Åhlander²,

Svensson

2011

2011 IEEE 19th Annual International Symposium on Field-Programmable Custom Computing Machines

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Abstract-Recently we proposed occam-pi as a high-level language for programming massively parallel reconfigurable architectures. The design of occam-pi incorporates ideas from CSP and pi-calculus to facilitate expressing parallelism and reconfigurability. The feasability of this approach was illustrated by building three occam-pi implementations of DCT executing on an Ambric. However, because DCT is a simple and wellstudied algorithm it remained uncertain whether occam-pi would also be effective for programming novel, more complex algorithms.In this paper, we demonstrate the applicability of occam-pi for expressing various degrees of parallelism by implementing a significantly large case-study of focus criterion calculation in an autofocus algorithm on the Ambric architecture. Autofocus is a key component of synthetic aperture radar systems. Two implementations of focus criterion calculation were developed and evaluated on the basis of performance. The comparison of the performance results with a single threaded software implementation of the same algorithm show that the throughput of the two implementations are 11x and 23x higher than the sequential implementation despite a much lower (9x) clock frequency. The two designs are, respectively, 29x and 40x more energy efficient. I. INTRODUCTION AND MOTIVATIONEmbedded signal processing systems are facing the challenges of increased computational demands. Massively parallel reconfigurable architectures, which can be configured to form application-specific hardware, offer high degree of parallelism to meet the application requirements. However, the applicability of reconfigurable processor arrays in embedded and high performance computing is constrained by the need for mastering low-level structural description languages and the lack of support in these languages for expressing dynamic reconfiguration. Clearly, all these challenges need to be taken care of by using an appropriate programming model.We proposed to use a concurrent programming model that allows the programmer to express computations in a productive manner by matching it to the target hardware using highlevel constructs, and the language is further supported by a compiler for providing portability across different hardware resources. Occam [2] is a programming language based on the Communicating Sequential Processes (CSP) [1] concurrent model of computation and was developed by Inmos for their microprocessor chip Transputer. However, CSP can only express a static model of the application, where processes synchronize through communication over fixed channels. In contrast, the pi-calculus [3] allows modeling of dynamic construc-

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Section: Occam-pi Languagementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Programming Real-Time Autofocus on a Massively Parallel Reconfigurable Architecture Using Occam-pi

Zain-ul-Abdin

Åhlander²,

Svensson

2011

2011 IEEE 19th Annual International Symposium on Field-Programmable Custom Computing Machines

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“…While the size of components varies with the design style chosen, a typical process-oriented design can have thousands of processes. Furthermore, as processes are created and connections between them made at runtime, truly dynamic systems can be modelled directly as process networks [34,45]. The explicit transfer of state using communication allows unmodified designs to be serialised for a single processor [39], and parallelised across shared-memory and distributed-memory multiprocessor systems [41,43].…”

Section: Introductionmentioning

confidence: 99%

Multicore Scheduling for Lightweight Communicating Processes

Ritson

Sampson

Barnes

2009

Lecture Notes in Computer Science

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Abstract. Process-oriented programming is a design methodology in which software applications are constructed from communicating concurrent processes. A process-oriented design is typically composed of a large number of small isolated concurrent components. These components allow for the scalable parallel execution of the resulting application on both shared-memory and distributed-memory architectures. In this paper we present a runtime designed to support process-oriented programming by providing lightweight processes and communication primitives. Our runtime scheduler, implemented using lock-free algorithms, automatically executes concurrent components in parallel on multicore systems. Runtime heuristics dynamically group processes into cache-affine work units based on communication patterns. Work units are then distributed via wait-free work-stealing. Initial performance analysis shows that, using the algorithms presented in this paper, process-oriented software can execute with an efficiency approaching that of optimised sequential and coarse-grain threaded designs.

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“…In [104,78], the CSP class library for Java, known as JCSP, provides an OCCAM3-like communicating process model for Java. Applications programs can make use of this library to implement necessary communications so as to manage thread execution and synchronization.…”

Section: Methods Integrationmentioning

confidence: 99%

Towards a new extension relation for compositional test case generation for CSP concurrent processes

Chan¹,

陳榮光.²

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Software concurrent systems such as electronic financial services are very popular today. Rigorous testing of such systems is indispensable. Nevertheless, the state-explosion problem, in which the size of a system grows exponentially with the number of concurrent components, is a severe obstacle to the generation of test cases.In this study, we propose a new relationship assuring the conformities of test cases for concurrent systems. We stipulate it in Communicating Sequential Processes (CSP), which is an excellent tool to study concurrent systems. Specification of concurrent systems is expressed as processes that are composed sequentially and concurrently. Our proposal supports both abstraction and process composition.This approach decomposes a given process into sequential compositions of component processes. Each component can be anti-extended into abstract forms. Sequential and concurrent combinations of abstract forms can substitute their corresponding extending components in a process to form aggregated abstract forms. Since the given processes, components and abstract forms are all processes, this approach can be applied recursively and compositionally. We prove that these aggregated abstract processes should be anti-extensions of the corresponding processes under a few necessary and sufficient conditions. Hence, test cases generated from these processes will be conformance test cases for the implementations.We examine three major testing relations (conformance, extension and reduction) from the point of view of their ability to support abstraction. Extension and reduction are special kinds of conformance, which are partially ordered. However, only extension from a specification can provide abstract forms that guarantee to be conformed by an implementation of the specification. Extension is further investigated to support the compositional approach. We identify five weaknesses of extension, which we call problems of preceding, succeeding, prefix, decomposition and paralleling. Each will result in non-conforming abstraction.To resolve the identified weaknesses of extension in a compositional and abstractionoriented approach, we formulate σ-extension and identify the necessary and sufficient conditions. We also discuss a restricted sub-class of process specification so that these conditions can easily be satisfied. In the restricted sub-class, successful terminations of processes are deterministic.Under these conditions, we achieve a few desirable properties. First, both preceding and succeeding components of a given sequential composition can be anti-extended. The given composition should extend the sequential composition of its corresponding anti-extended processes. Secondly, a given parallel composition whose concurrent components are sequential compositions should extend a parallel composition of anti-extensions of preceding components of corresponding sequential compositions, followed by a parallel composition of anti-extensions of corresponding succeeding components. Furthermore, a given sequential co...

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Communicating Mobile Processes

Cited by 78 publications

References 11 publications

Programming Real-Time Autofocus on a Massively Parallel Reconfigurable Architecture Using Occam-pi

Programming Real-Time Autofocus on a Massively Parallel Reconfigurable Architecture Using Occam-pi

Multicore Scheduling for Lightweight Communicating Processes

Towards a new extension relation for compositional test case generation for CSP concurrent processes

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