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ABSTRACT: The asynchronous nature of some MPI/PVM programs does not easily fit inside the BSP model. Through the suppression of barriers
and the generalization of the concept of superstep we propose a new model, the BSP Without Barriers (BSPWB) model. The BSPWB
parameters and their quality are evaluated on four standard parallel platforms: the CRAY T3E, the IBM SP2, the Origin 2000
and the Digital Alpha Server 8400. This study proves that the time spent in an h-relation is more independent on the number of processors than on the communication pattern. We illustrate the BSPWB model
using two problem-solving paradigms: the Nested Parallel Recursive Divide and Conquer Paradigm and the Virtual Pipeline Dynamic
Programming Paradigm. The proposed paradigms explain how nested parallelism and processor virtualization may be introduced
in MPI and PVM without having any negative impact in the performance and model accuracy. The prediction of the communication
times is robust even for problems where communication is dominated by small messages.
08/2006: pages 387-394;
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ABSTRACT: This paper studies the validity of the BSP h-relation hypothesis on four current standard parallel platforms. The error introduced by the influence of the number of processors
is measured on five communication patterns. We also measure the influence of the communication patterns on the time invested
in an h-relation. The asynchronous nature of many current standard message passing programs do not easily fits inside the BSP model.
Often this has been criticized as the most serious drawback of BSP. Based in the h-relation hypothesis we propose an extension to BSP model valid for standard message passing parallel programs. The use and
accuracy of h-relation models on standard message passing programs are illustrated using a parallel algorithm to compute the Discrete Fast
Fourier Transform.
07/2006: pages 234-243;
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ABSTRACT: Recent publications prove that runtime systems oriented to the Bulk Synchronous Parallel Model usually achieve remarkable accuracy in their predictions. That accuracy can be seen in the capacity of the software for packing the messages generated during the superstep and their capability to find a rearrangement of the messages sent at the end of the superstep. Unfortunately, barrier synchronisation imposes some limits both in the range of available algorithms and in their performance. The asynchronous nature of many MPI/PVM programs makes their expression difficult or infeasible using a BSP oriented library. Through the generalisation of the concept of superstep we propose two extensions of the BSP model: the BSP Without Barriers (BSPWB) and the Message Passing Machine (MPM) models. These new models are oriented to MPI/PVM parallel programming. The parameters of the models and their quality are evaluated on four standard parallel platforms. The use of these BSP extensions is illustrated using the Fast Fourier Transform and the Parallel Sorting by Regular Sampling algorithms. Copyright © 1999 John Wiley & Sons, Ltd.
Concurrency Practice and Experience 08/1999; 11(9):461 - 477.
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ABSTRACT: It has been argued that message passing systems based on pairwise, rather than barrier, synchronization suffer from having
no simple analytic cost for model prediction. The BSP Without Barriers Model (BSPWB) has been proposed as an alternative to
the Bulk Synchronous Parallel (BSP) model for the analysis, design and prediction of asynchronous MPI programs. This work
compares the prediction accuracy of the BSP and BSPWB models and the performance of their respective software libraries: Oxford
BSPlib and MPI. Three test cases, representing three general problem solving paradigms are considered. These cases cover a
wide range of requirements in communication, synchronisation and computation. The results obtained on the CRAY-T3E show not
only a better scalability of MPI but that the performance of MPI programs can be predicted with the same exactitude than Oxford
BSPlib programs.
12/1998: pages 676-676;
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ABSTRACT: The asynchronous nature of many MPI/PVM programs does not fit the BSP model. The barrier synchronization imposed by the model restricts the range of available algorithms and their performance. Through the suppression of barriers and the generalization of the concept of superstep we propose two new models, the BSP-like and the BSP Without Barriers (BSPWB) models. While the BSP-like extends the BSP* model to programs written using collective operations, the more general BSPWB model admits the MPI/PVM parallel asynchronous programming style. As LogP, the model encourages locality but it is simpler to use. The parameters of the models and their quality are evaluated on a distributed shared memory machine, the Origin 2000 and on a distributed memory machine, the CRAY T3E. The dependence of the time spent in an h-relation is stronger in the communication pattern than in the number of processors. The total variation of the h-relation time in both the patterns and processor numbers is smaller than sixty nanoseconds. To illustrate the proposed models, two different applications are considered: a Parallel Sort using Regular Sampling (PSRS) and a Parallel Dynamic Programming Algorithm solving the Single Resource Allocation Problem (SRAP). The PSRS is a synchronous algorithm with a rich set of collective communication patterns and coarse grain communications. On the opposite extreme, the SRAP is a fine grain communication algorithm using permutation patterns. The computational results prove the accuracy of the models. The prediction of the communication times is robust even for the SRAP, where communication is dominated by small messages
Parallel Architectures and Compilation Techniques, 1998. Proceedings. 1998 International Conference on; 11/1998
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ABSTRACT: BSP oriented runtime systems try to get closer actual machines to the BSP ideal machine by packing individual messages generated during a superstep and optimizing communication time by rearranging the order in which messages are sent at the end of the superstep. These design considerations strongly contribute to the remarkable accuracy of BSP runtime systems. Unfortunately, barrier synchronization imposes some limits both in the range of available algorithms and in their performance. Although BSP programs can be expressed using PVM and MPI, the counterpart is not always true. The asynchronous nature of some MPI/PVM programs does not easily fit inside the BSP model. Through the generalization of the concept of superstep we propose two extensions to the BSP model: the BSP without barriers (BSPWB) and the Message Passing Machine (MPM) models. These new models are oriented to MPI/PVM parallel programming. The parameters of the models and their quality are evaluated on four standard parallel platforms. The use of these BSP extensions is illustrated through a fast Fourier transform algorithm
Euromicro Conference, 1998. Proceedings. 24th; 09/1998
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ABSTRACT: The BSP model barrier synchronization imposes some limits both in the range of available algorithms and also in their performance. Although BSP programs can be translated to MPI/PVM programs, the counterpart is not true. The asynchronous nature of some MPI/PVM programs does not easily fit inside the BSP model. Through the suppression of barriers and the generalization of the concept of superstep we propose two new models, the BSP-like and the BSP without barriers (BSPWB) models. While the BSP-like extends the BSP* model to programs written using collective operations, the more general BSPWB model admits the MPI/PVM parallel asynchronous programming style. The parameters of the models and their quality are evaluated on four standard parallel platforms: the CRAY T3E, the IBM SP2, the Origin 2000 and the Digital Alpha Server 8400. The study shows that the time spent in an h-relation is more independent on the number of processors than on the communication pattern. We illustrate the use of these BSP extensions through two problem-solving paradigms: the Nested Parallel Recursive Divide and Conquer Paradigm and the Virtual Pipeline Dynamic Programming Paradigm. The proposed paradigms explain how nested parallelism and processor virtualization can be introduced in MPI and PVM without having any negative impact in the performance and model accuracy. The prediction of the communication times is robust even for problems, where communication is dominated by small messages.
Parallel Computing.
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ABSTRACT: Resumen Existen diversas propuestas de metodologías para el desarrollo de los sistemas de información. Entre ellas podemos destacar METRICA, que siendo muy extensa para cubrir sistemas de tamaño reducido, es flexible y abierta a la hora de definir los documentos que deben salir de cada fase. En este trabajo presentamos las características de METRICA, ponemos ejemplos de los documentos de análisis y reflejamos las experiencias del alumnado. Esta metodología no sólo facilita la generación de la documentación del proyecto mientras se realiza cada una de las tareas de desarrollo, sino que también ofrece una visión unificada, clara, ampliable y flexible de cada uno de los procesos realizados. Mostramos como el uso de esta metodología no sólo es adecuado en las asignaturas de Ingeniería del Software, sino también en las asignaturas Prácticas en Empresa y Proyecto, donde se realizan proyectos de desarrollo de software.
