Skeletons for parallel image processing: an overview of the SKiPPER project

International audienceThis paper is a general overview of the SKIPPER project, run at Blaise Pascal University between 1996 and 2002. The main goal of the SKIPPER project was to demonstrate the appli- cability of skeleton-based parallel programming techniques to the fast prototyping of reactive vision applications. This project has produced several versions of a full-fledged integrated pa- rallel programming environment (PPE). These PPEs have been used to implement realistic vi- sion applications, such as road following or vehicle tracking for assisted driving, on embedded parallel platforms embarked on semi-autonomous vehicles. All versions of SKIPPER share a common front-end and repertoire of skeletons--presented in previous papers--but differ in the techniques used for implementing skeletons. This paper focuses on these implementation issues, by making a comparative survey, according to a set of four criteria (efficiency, expres- sivity, portability, predictability), of these implementation techniques. It also gives an account of the lessons we have learned, both when dealing with these implementation issues and when using the resulting tools for prototyping vision applications

Lithium: A Structured Parallel Programming Environment inJa va

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Management in distributed systems: a semi-formal approach

Abstract Formal tools can be used in a "semi-formal" way to support distributed program analysis and tuning. We show how ORC has been used to reverse engineer a skeleton based programming environment and to remove one of the skeleton system's recognized weak points. The semi-formal approach adopted allowed these steps to be performed in a programmer-friendly way

Tools and Models for High Level Parallel and Grid Programming

When algorithmic skeletons were first introduced by Cole in late 1980 the idea had an almost immediate success. The skeletal approach has been proved to be effective when application algorithms can be expressed in terms of skeletons composition. However, despite both their effectiveness and the progress made in skeletal systems design and implementation, algorithmic skeletons remain absent from mainstream practice. Cole and other researchers, focused the problem. They recognized the issues affecting skeletal systems and stated a set of principles that have to be tackled in order to make them more effective and to take skeletal programming into the parallel mainstream. In this thesis we propose tools and models for addressing some among the skeletal programming environments issues. We describe three novel approaches aimed at enhancing skeletons based systems from different angles. First, we present a model we conceived that allows algorithmic skeletons customization exploiting the macro data-flow abstraction. Then we present two results about the exploitation of meta-programming techniques for the run-time generation and optimization of macro data-flow graphs. In particular, we show how to generate and how to optimize macro data-flow graphs accordingly both to programmers provided non-functional requirements and to execution platform features. The last result we present are the Behavioural Skeletons, an approach aimed at addressing the limitations of skeletal programming environments when used for the development of component-based Grid applications. We validated all the approaches conducting several test, performed exploiting a set of tools we developed.Comment: PhD Thesis, 2008, IMT Institute for Advanced Studies, Lucca. arXiv admin note: text overlap with arXiv:1002.2722 by other author

Skeleton data parallel per OCAMLP3L

La tesi si inserisce nell'ambito della programmazione a skeleton: uno skeleton è un particolare struttura di un algoritmo parallelo con la quale possono essere parallelizzate molte classi di problemi sequenziali; uno skeleton è dunque uno schema algoritmico parametrico rispetto alla funzione sequenziale da eseguire in parallelo. Dall'analisi del problema sequenziale è possibile derivare il particolare skeleton, tra alcuni ben conosciuti, che esegue un'applicazione parallela funzionalmente equivalente a quella sequenziale ma in generale caratterizzata da prestazioni migliori. Gli skeleton possono essere suddivisi in due categorie: task parallel, in cui il parallelismo deriva dall'applicazione contemporanea di una funzione su più elementi di una sequenza di input, e data parallel, in cui il parallelismo deriva dall'applicazione contemporanea di una funzione su parti diverse dello stesso elemento, una struttura dati decomponibile, di una sequenza di input. Gli skeleton possono essere utilizzati per raggiungere due principali obiettivi, spesso in antitesi tra loro, e sono da un lato le prestazioni massime dall'altro la facilità con la quale il programmatore può esprimere un'applicazione parallela anche riutilizzando codice preesistente pur ottenendo miglioramenti prestazionali. Negli ultimi vent'anni il concetto di skeleton ha avuto molto successo in ambito accademico e sono stati proposti numerosi sistemi che offrono skeleton sia task che data parallel e che si propongono di raggiungere uno dei due principali obiettivi appena visti. In particolare in letteratura sono stati proposti sia linguaggi per la programmazione parallela strutturata, in cui gli skeleton sono offerti come costrutti nativi di tali linguaggi, sia delle librerie, in cui gli skeleton sono offerti come funzioni o metodi. La nostra tesi verte sul sistema OCamlP3l, una libreria in linguaggio OCaml, che deriva da uno dei primi linguaggi per la programmazione parallela strutturata, P3L, sviluppato presso il Dipartimento di Informatica dell'Università di Pisa. Il lavoro è stato volto principalmente all'introduzione di uno skeleton data parallel che permettesse di parallelizzare computazioni di struttura più complessa rispetto agli skeleton già esistenti nel sistema. Tali computazioni sono denominate stencil e tendono a trovarsi in applicazioni iterative in cui la condizione di terminazione spesso dipende dal risultato ottenuto ad ogni iterazione; lo skeleton introdotto permette di esprimere anche queste applicazioni

Tunneling SSL in Muskel : implementazione e valutazione delle prestazioni

Si discute l'introduzione di tecnologia SSL per le comunicazioni con nodi remoti "non sicuri" nell'interprete distribuito di Muskel, ambiente a skeleton basato su macro data flow.Se ne discutono le implicazioni sulle performance

Tools and models for high level parallel and Grid programming

When algorithmic skeletons were first introduced by Cole in late 1980 (50) the idea had an almost immediate success. The skeletal approach has been proved to be effective when application algorithms can be expressed in terms of skeletons composition. However, despite both their effectiveness and the progress made in skeletal systems design and implementation, algorithmic skeletons remain absent from mainstream practice. Cole and other researchers, respectively in (51) and (19), focused the problem. They recognized the issues affecting skeletal systems and stated a set of principles that have to be tackled in order to make them more effective and to take skeletal programming into the parallel mainstream. In this thesis we propose tools and models for addressing some among the skeletal programming environments issues. We describe three novel approaches aimed at enhancing skeletons based systems from different angles. First, we present a model we conceived that allows algorithmic skeletons customization exploiting the macro data-flow abstraction. Then we present two results about the exploitation of metaprogramming techniques for the run-time generation and optimization of macro data-flow graphs. In particular, we show how to generate and how to optimize macro data-flow graphs accordingly both to programmers provided non-functional requirements and to execution platform features. The last result we present are the Behavioural Skeletons, an approach aimed at addressing the limitations of skeletal programming environments when used for the development of component-based Grid applications. We validated all the approaches conducting several test, performed exploiting a set of tools we developed

Datenparallele algorithmische Skelette:Erweiterungen und Anwendungen der Münster Skelettbibliothek Muesli

Die Arbeit thematisiert den datenparallelen Bestandteil der Münster Skelettbibliothek Muesli und beschreibt neben einer Reihe implementierter Erweiterungen auch mit Muesli parallelisierte Anwendungen. Eine der wichtigsten Neuerungen ist die Unterstützung von Mehrkernprozessoren durch die Verwendung von OpenMP, infolgedessen mit Muesli entwickelte Programme auch auf Parallelrechnern mit hybrider Speicherarchitektur skalieren. Eine zusätzliche Erweiterung stellt die Neuentwicklung einer verteilten Datenstruktur für dünnbesetzte Matrizen dar. Letztere implementiert ein flexibles Designkonzept, was die Verwendung benutzerdefinierter Kompressions- sowie Lastverteilungsmechanismen ermöglicht. Darüber hinaus werden mit dem LM OSEM-Algorithmus und den ART 2-Netzen zwei Anwendungen vorgestellt, die mit Muesli parallelisiert wurden. Neben einer Beschreibung der Funktionsweise sowie der Eigenschaften und Konzepte von MPI und OpenMP wird darüber hinaus der aktuelle Forschungsstand skizziert. <br/

Dynamic Run Time Support for Skeletons

We propose a new implementation model for structured parallel programming models based on skeletons. The model is aimed at overcoming some of the problems observed in traditional, template based implementations of skeleton languages, while preserving all the positive features of structured parallel programming models. The proposed implementation model does not rely on static process networks like the template based implementation model for skeletons. It rather implements skeleton programs by properly scheduling macro data-flow instructions (corresponding to the sequential portions of code appearing in the skeleton code) to a set of macro data-flow interpreters running on the processing elements of the target architecture. We discuss some preliminary experimental results demonstrating the feasibility and effectiveness of our approach