PALS: An Or-Parallel Implementation of Prolog on Beowulf Architectures

Villaverde, Karen; Pontelli, Enrico; Guo, Hai-Feng; Gupta, Gopal

doi:10.1007/3-540-45635-x_10

Cited by 8 publications

(5 citation statements)

References 11 publications

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“…PALS [39] é um sistema publicado em 2001 que explora o paralelismo-OU em arquiteturas de memória distribuída, construído com base no ambiente de cópia presente em sistemas como Muse [1] e YapOr [30].…”

Section: Palsunclassified

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Paralelismo em Prolog: Conceitos e Sistemas

Filho

Silva²

2016

RITA

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Resumo: Paralelismo é uma área de estudo que cresce a cada dia, devido à redução do custo e popularização de máquinas com arquiteturas paralelas. Nesse contexto, as linguagens lógicas, sobretudo o PROLOG, apresenta uma alternativa viável e prá-tica de paralelismo. A exploração desse paralelismo pode ser realizada de diferentes formas, e há inúmeros desafios nessa tarefa. Este tutorial visa apresentar os principais conceitos de paralelismo em PROLOG, os desafios enfrentados quando se busca a paralelização nessa linguagem e o estado-da-arte do desenvolvimento de sistemas que dão suporte à paralelização em linguagens lógicas. São apresentados sistemas baseados em paralelismo implícito implementados em diferentes plataformas. Ao final é realizada uma comparação entre os sistemas apresentados e os modelos neles implementados.Palavras-chave: prolog, paralelismo, paralelismo-E, paralelismo-OU, parale- lismo implícitoAbstract: Parallelism is a study area that grows up each day, caused by the cost reduction and popularizing of machines with parallels architecture. In this context, the logical languages, especially PROLOG, show a feasible and practical alternative of parallelism. This exploitation can be accomplished of different ways, and are there several challenges on this task. This survey aims to show the main concepts of parallelism in PROLOG, the faced challenges when aims to do parallelism in this language and the state-of-art of systems development to give parallelism support in logical languages. Systems with basis on implicit parallelism developed in different platforms are presented. At the end, is accomplished a comparison between the presented systems and the implemented models by they.

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Section: Palsunclassified

“…A maximização da exploração do paralelismo ocorre somente quando explorados ambos os tipos de paralelismo, mas apesar disso, diversos sistemas [30,1,29,39] apresentam bons resultados explorando apenas um tipo de paralelismo.…”

Section: Uma Comparaçãounclassified

Paralelismo em Prolog: Conceitos e Sistemas

Filho

Silva²

2016

RITA

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“…Stack splitting (Gupta and Pontelli 1999;Pontelli et al 2006) is an alternative scheduling strategy for environment copying that provides a simple and clean method to accomplish work splitting among workers in which the available work is statically divided beforehand in complementary sets between the sharing workers. Due to its static nature, stack splitting was first introduced aiming at distributed memory architectures (Villaverde et al 2001) but, recent work, also showed good results for shared memory architectures (Vieira et al 2012).…”

Section: Introductionmentioning

confidence: 99%

“…However, practice has shown that a main difficulty is how to efficiently represent the multiple bindings for the same variable produced by the or-parallel execution of alternative matching clauses. One of the most successful or-parallel models that solves the multiple bindings problem is environment copying, which has been efficiently used in the implementation of or-parallel Prolog systems both on shared memory (Ali and Karlsson 1990;Rocha et al 1999) and distributed memory (Villaverde et al 2001;Rocha et al 2003) architectures.…”

Section: Introductionmentioning

confidence: 99%

On the Implementation of an Or-Parallel Prolog System for Clusters of Multicores

Santos¹,

Rocha²

2016

Theory and Practice of Logic Programming

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Nowadays, clusters of multicores are becoming the norm and, although, many or-parallel Prolog systems have been developed in the past, to the best of our knowledge, none of them was specially designed to explore the combination of shared and distributed memory architectures. In recent work, we have proposed a novel computational model specially designed for such combination which introduces a layered model with two scheduling levels, one for workers sharing memory resources, which we named a team of workers, and another for teams of workers (not sharing memory resources). In this work, we present a first implementation of such model and for that we revive and extend the YapOr system to exploit or-parallelism between teams of workers. We also propose a new set of built-in predicates that constitute the syntax to interact with an or-parallel engine in our platform. Experimental results show that our implementation is able to increase speedups as we increase the number of workers per team, thus taking advantage of the maximum number of cores in a machine, and to increase speedups as we increase the number of teams, thus taking advantage of adding more computer nodes to a cluster.

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“…Stack splitting [4,5] is an extension to the environment copying model that provides a simple, clean and efficient method to accomplish work splitting among workers. It successfully splits the computation task of one worker in two complementary sets, and was thus first introduced aiming at distributed memory architectures [6,7].…”

Section: Introductionmentioning

confidence: 99%

On Comparing Alternative Splitting Strategies for Or-Parallel Prolog Execution on Multicores

Vieira¹,

Rocha²,

Silva³

2013

Preprint

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Many or-parallel Prolog models exploiting implicit parallelism have been proposed in the past. Arguably, one of the most successful models is environment copying for shared memory architectures. With the increasing availability and popularity of multicore architectures, it makes sense to recover the body of knowledge there is in this area and re-engineer prior computational models to evaluate their performance on newer architectures. In this work, we focus on the implementation of splitting strategies for or-parallel Prolog execution on multicores and, for that, we develop a framework, on top of the YapOr system, that integrates and supports five alternative splitting strategies. Our implementation shares the underlying execution environment and most of the data structures used to implement or-parallelism in YapOr. In particular, we took advantage of YapOr's infrastructure for incremental copying and scheduling support, which we used with minimal modifications. We thus argue that all these common support features allow us to make a first and fair comparison between these five alternative splitting strategies and, therefore, better understand their advantages and weaknesses.

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PALS: An Or-Parallel Implementation of Prolog on Beowulf Architectures

Cited by 8 publications

References 11 publications

Paralelismo em Prolog: Conceitos e Sistemas

Paralelismo em Prolog: Conceitos e Sistemas

On the Implementation of an Or-Parallel Prolog System for Clusters of Multicores

On Comparing Alternative Splitting Strategies for Or-Parallel Prolog Execution on Multicores

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