We survey parallel programming models and languages using 6 criteria [:] should be easy to program, have a software development methodology, be architecture-independent, be easy to understand, guranatee performance, and provide info about the cost of programs. ... We consider programming models in 6 categories, depending on the level of abstraction they provide.

Bulk Synchronous Parallelism (BSP) is a parallel programming model that abstracts from low-level program structures in favour of supersteps. A superstep consists of a set of independent local computations, followed by a global communication phase and a barrier synchronisation. Structuring programs in this way enables their costs to be accurately determined from a few simple architectural parameters, namely the permeability of the communication network to uniformly-random traffic and the time to synchronise. Although permutation routing and barrier synchronisations are widely regarded as inherently expensive, this is not the case. As a result, the structure imposed by BSP comes for free in performance terms, while bringing considerable benefits from an application-building perspective. This paper answers the most common questions we are asked about BSP and justifies its claim to be a major step forward in parallel programming. 1 Why is another model needed? In the 1980s a large number ...

The performance of data parallel programs often hinges on two key coordination aspects: the computational costs of the parallel tasks relative to their management overhead | task granularity ; and the communication costs induced by the distance between tasks and their data | data locality . In data parallel programs both granularity and locality can be improved by clustering, i.e. arranging for parallel tasks to operate on related sub-collections of data.

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Document archives contain large amounts of data to which sophisticated queries are applied. The size of archives and the complexity of evaluating queries makes the use of parallelism attractive. The use of semantically-based markup such as SGML makes it possible to represent documents and document archives as data types. We present a theory of trees and tree homomorphisms, modelling structured text archives and operations on them, from which it can be seen that: ffl many apparently-unrelated tree operations are homomorphisms; ffl homomorphisms can be described in a simple parameterised way that gives standard sequential and parallel implementations for them; ffl special classes of homomorphisms have parallel implementations of practical interest. In particular, we develop an implementation for path expression search, a novel powerful query facility for structured text, that takes time logarithmic in the text size. Keywords: structured text, categorical data type, software developme...

Abstract. Today, parallel programming is dominated by message passing libraries such as MPI. Algorithmic skeletons intend to simplify parallel programming by their expressive power. The idea is to offer typical parallel programming patterns as polymorphic higher-order functions which are efficiently implemented in parallel. Skeletons can be understood as a domain-specific language for parallel programming. In this chapter, we describe a set of data parallel skeletons in detail and investigate the potential of optimizing sequences of these skeletons by replacing them by more efficient sequences. Experimental results based on a draft implementation of our skeleton library are shown. 1

Algorithmic skeletons intend to simplify parallel programming by providing a higher level of abstraction compared to the usual message passing. Task and data parallel skeletons can be distinguished. In the present paper, we will consider several approaches to implement one of the most classical task parallel skeletons, namely the farm, and compare them w.r.t. scalability, overhead, potential bottlenecks, and load balancing. We will also investigate several communication modes for the implementation of skeletons. Based on experimental results, the advantages and disadvantages of the different approaches are shown. Moreover, we will show how to terminate the system of processes properly. Keywords: Parallel programming, algorithmic skeletons, farm, MPI. 1.