Degree of parallelism

About: Degree of parallelism is a research topic. Over the lifetime, 1515 publications have been published within this topic receiving 25546 citations.

Developing parallel object-oriented programs in the framework of VDM

Abstract: After surveying the rely-guarantee and some related approaches to extending VDM to develop parallel programs, two main problems are found. One problem is that all explorations of parallelism are done in the stage of operation decomposition or afterwards so that the degree of parallelism is restricted. Another problem is that the atomicity is fixed at one level and the development complexity can not be controlled effectively because there is no natural means to let the level of granularity be under flexible control of the designer. In order to solve these two problems, we introduce a new concept — data decomposition which is based on the ideas of model split, modularisation and operation decomposition, and combine it with VDM to form a more general formal development method DD-VDM, in which some kind of operation decompositions, i.e., operation split can be done before some data reifications. Then a nested parallel object-oriented structure is proposed. Combining these ideas into the unified framework, this paper presents a hierarchical object-oriented design methodology in which two kinds of parallelism, that is, internal parallelism and service parallelism, can be exploited gradually and a kind of virtual atomicity is provided.

RRES: a novel approach to the partitioning problem for a typical subset of system graphs

Abstract: The research field of system partitioning in modern electronic system design started to find strong advertence of scientists about fifteen years ago. Since a multitude of formulations for the partitioning problem exist, the same multitude could be found in the number of strategies that address this problem. Their feasibility is highly dependent on the platform abstraction and the degree of realism that it features. This work originated from the intention to identify the most mature and powerful approaches for system partitioning in order to integrate them into a consistent design framework for wireless embedded systems. Within this publication, a thorough characterisation of graph properties typical for task graphs in the field of wireless embedded system design has been undertaken and has led to the development of an entirely new approach for the system partitioning problem. The restricted range exhaustive search algorithm is introduced and compared to popular and well-reputed heuristic techniques based on tabu search, genetic algorithm, and the global criticality/local phase algorithm. It proves superior performance for a set of system graphs featuring specific properties found in human-made task graphs, since it exploits their typical characteristics such as locality, sparsity, and their degree of parallelism.

The component architecture toolkit

Abstract: Metacomputing is concerned with the exploitation of large-scale distributed computing over the Internet using high-performance networks and computing resources. Metacomputing is important to scientific computing for several reasons. First, many scientific problems exhibit some degree of parallelism, and hence may be solved more efficiently on a network of computers, or “metacomputer”, than on a single computer. Second, problems whose resource requirements exceed the capacity of a single computer can take advantage of the potentially unbounded capacity of a metacomputer. Third, problems which require access to local or specialized resources would benefit from the distributed aspect of a metacomputer. Metacomputing also extends the feasibility range of existing scientific problems. The Grid is a software infrastructure for implementing metacomputing. Grid systems such as Globus and Legion provide sophisticated service layers which allow users to access and manage distributed hardware and software resources. However, building distributed applications by programming directly to low-level Grid APIs is not easy. End users who wish to solve problems using the GrK tend to first think in terms of higher-level, problem-centric concepts, such as determining which software resources are applicable, and then designing and building an application using those resources. Low-level details such as process instantiation, machine or network characteristics, and so forth typically come at a later stage of the application building process. This dissertation presents the Component Architecture Toolkit (CAT), a system enabling end users to build component-based applications in a metacomputing environment. The CAT contributes the following: a model capturing the principles used to build a scalable component system; an extensible framework design that can be retargeted to different Grid systems; a set of framework libraries for developing components and a runtime environment for deploying them; and a set of end user tools for locating and instantiating components, as well as tools for building, controlling and analyzing the performance of component-based applications. Scientific computing issues addressed by the CAT design and implementation are discussed. The application of the CAT to a particular scientific problem domain, as well as the performance analysis of an example component-based application is also presented.