Abstract not found

Mapping applications onto parallel platforms is a challenging problem, even for simple application patterns such as pipeline or fork graphs. Several antagonist criteria should be optimized for workflow applications, such as throughput and latency (or a combination). In this paper, we consider a simplified model with no communication cost, and we provide an exhaustive list of complexity results for different problem instances. Pipeline or fork stages can be replicated in order to increase the throughput by sending consecutive data sets onto different processors. In some cases, stages can also be data-parallelized, i.e. the computation of one single data set is shared between several processors. This leads to a decrease of the latency and an increase of the throughput. Some instances of this simple model are shown to be NP-hard, thereby exposing the inherent complexity of the mapping problem. We provide polynomial algorithms for other problem instances. Altogether, we provide solid theoretical foundations for the study of mono-criterion or bi-criteria mapping optimization problems.

Abstract. The reverse engineering of a skeleton based programming environment and redesign to distribute management activities of the system and thereby remove a potential single point of failure is considered. The Orc notation is used to facilitate abstraction of the design and analysis of its properties. It is argued that Orc is particularly suited to this role as this type of management is essentially an orchestration activity. The Orc specification of the original version of the system is modified via a series of semi-formally justified derivation steps to obtain a specification of the decentralized management version which is then used as a basis for its implementation. Analysis of the two specifications allows qualitative prediction of the expected performance of the derived version with respect to the original, and this prediction is borne out in practice.

The design, implementation and deployment of efficient high performance applications on Grids is usually a quite hard task, even in the case that modern and efficient grid middleware systems are used. We claim that most of the difficulties involved in such process can be moved away from programmer responsibility by following a structured programming model approach. The proposed approach relies on the development of a layered, component based execution environment. Each layer deals with distinct features and problems related to the implementation of GRID applications, exploiting the more appropriate techniques. Static optimizations are introduced in the compile layer, dynamic optimization are introduced in the run time layer, whereas modern grid middleware features are simply exploited using standard middleware systems as the final target architecture. We first discuss the general idea, then we discuss the peculiarities of the approach and eventually we discuss the preliminary results achieved in the GRID.it project, where a prototype high performance, component based, GRID programming environment is being developed using this approach.

Current Grid-aware applications are developed on existing software infrastructures, such as Globus, by developers who are experts on Grid software implementation. Although many useful applications have been produced this way, this approach may hardly support the additional complexity to Quality of Service (QoS) control in real application. We describe the ASSIST programming environment, the prototype of parallel programming environment currently under development at our group, as a suitable basis to capture all the desired features for QoS control for the Grid. Grid applications, built as compositions of ASSIST components, are supported by an innovative Grid Abstract Machine, which includes essential abstractions of standard middleware services and a hierarchical Application Manager, which may be considered as an early prototype of Autonomic Manager.

We show in this paper how to evaluate the performance of skeleton-based high level parallel programs. Since many applications follow some commonly used algorithmic skeletons, we identify such skeletons and model them with process algebra in order to get relevant information about the performance of the application, and be able to take some "good" scheduling decisions. This concept is illustrated through the case study of the Pipeline skeleton, and a tool which generates automatically a set of models and solves them is presented. Some numerical results are provided, proving the efficiency of this approach.

Abstract We present behavioural skeletons for the CoreGRID Component Model, which are an abstraction aimed at simplifying the development of GCM-based selfmanagement applications. Behavioural skeletons abstract component self-managent in component-based design as design patterns abstract class design in classic OO development. As here we just wish to introduce the behavioural skeleton framework, emphasis is placed on general skeleton structure rather than on their autonomic management policies.

With the increasing popularity of parallel programming environments such as PC clusters, more and more sequential programmers, with little knowledge about parallel architectures and parallel programming, are hoping to write parallel programs. Numerous attempts have been made to develop high-level parallel programming libraries that use abstraction to hide low-level concerns and reduce difficulties in parallel programming. Among them, libraries of parallel skeletons have emerged as a promising way towards this direction. Unfortunately, these libraries are not well accepted by sequential programmers, because of incomplete elimination of lower-level details, ad-hoc selection of library functions, unsatisfactory performance, or lack of convincing application examples. This paper addresses principle of designing skeleton libraries of parallel programming and reports implementation details and practical applications of a skeleton library SkeTo. The SkeTo library is unique in its feature that it has a solid theoretical foundation based on the theory of Constructive Algorithmics, and is practical to be used to describe various parallel computations in a sequential manner. 1.

Abstract. Skeletons are common patterns of parallelism like, e.g., farm, pipeline that can be abstracted and offered to the application programmer as programming primitives. We describe the use and implementation of skeletons in a distributed grid environment, with the Java-based system Lithium as our reference implementation. Our main contribution are optimization techniques based on an asynchronous, optimized RMI interaction mechanism, which we integrated into the macro data flow (MDF) implementation technology of Lithium. We report initial experimental results that demonstrate the achieved improvements through the proposed optimizations on a simple grid testbed. 1

apport de recherche ISSN 0249-6399 ISRN INRIA/RR--6232--FR+ENGMulti-criteria scheduling of pipeline workflows