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Publications

Publications by CRACS

1999

The BEAM: A first EAM Implementation

Authors
Lopes, R; Costa, VS;

Publication
1999 Joint Conference on Declarative Programming, AGP'99, L'Aquila, Italy, September 6-9, 1999

Abstract

1999

Distance: A New Metric for Controlling Granularity for Parallel Execution

Authors
Shen, K; Costa, VS; King, A;

Publication
Journal of Functional and Logic Programming

Abstract

1999

Performance Evaluation of Or-Parallel Logic Programming Systems on Distributed Shared-Memory Architectures

Authors
Calegario, VM; Dutra, IdC;

Publication
Euro-Par '99 Parallel Processing, 5th International Euro-Par Conference, Toulouse, France, August 31 - September 3, 1999, Proceedings

Abstract
In this work we investigate how Distributed Shared Memory (DSM) architectures affect performance of or-parallel logic programming systems and how this performance approaches that of conventional C systems. Our work concentrates on basic performance, scalability, and programmability. We use execution-driven simulation of a hardware DSM (DASH) to investigate the access patterns and caching behaviour exhibited by parallel C programs and by Aurora, a parallel logic programming system capable of exploiting implicit parallelism in Prolog programs. Aurora was originally written to run on bus-based shared-memory platforms. © Springer-Verlag Berlin Heidelberg 1999.

1998

Distribution and Mobility with Lexical Scoping in Process Calculi

Authors
Vasconcelos, VT; Lopes, LMB; Silva, FMA;

Publication
Electr. Notes Theor. Comput. Sci.

Abstract
We propose a simple model of distribution for mobile processes, independent of the underlying calculus. Conventional processes compute within sites; inter-site computation is achieved by message sending and object migration, both obeying a lexical scope. We focus on the semantics of networks, on programming practice, and on physical realization with current technology. ©1998 Published by Elsevier Science B.V.

1998

VisAll: A universal tool to visualise the parallel execution of logic programs

Authors
Fonseca, N; Costa, VS; Dutra, ID;

Publication
LOGIC PROGRAMMING - PROCEEDINGS OF THE 1998 JOINT INTERNATIONAL CONFERENCE AND SYMPOSIUM ON LOGIC PROGRAMMING

Abstract
One of the most important advantages of logic programming systems is that they allow the transparent exploitation of parallelism. The different forms of parallelism available and the complex nature of logic programming applications present interesting problems to both the users and the developers of these systems. Graphical visualisation tools can give a particularly important contribution, as they are easier to understand than text based tools, and allow both for a general overview of an execution and for focusing on its important details. Towards these goals, we propose VisAll, anew tool to visualise the parallel execution of logic programs. VisAll benefits from a modular design centered in a graph that represents a parallel execution. A main graphical shell commands the different modules and presents VisAll as an unified system. Several input components, or translators, support the well-known VisAndor and VACE trace formats, plus a new format designed for independent and-parallel plus or-parallel execution in the SEA. Several output components, or visualisers, allow for different visualisations of the same execution.

1998

Optimising parallel logic programming systems for scalable machines

Authors
Costa, VS; Bianchini, R;

Publication
EURO-PAR '98 PARALLEL PROCESSING

Abstract
Parallel logic programming (PLP) systems have obtained good performance on traditional bus-based shared-memory architectures. However, the scalable multiprocessors being developed today pose new challenges. Our experience with a sophisticated PLP system, Andorra-I, demonstrates that indeed performance suffers greatly on modern architectures. In order to improve performance, we perform a detailed analysis of the cache behaviour of all Andorra-I data structures via execution-driven simulation of a DASH-like multiprocessor. Based on this analysis we optimise the Andorra-I code using 5 different techniques. Our results show that the techniques provide significant performance improvements, leading to the conclusion that PLP systems can and should perform well on modern scalable multiprocessors.

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