Dynamic Data Driven approach to improve theperformance of a river simulation

In this research we incorporate the contributions of the dynamic data driven systems development that is based on the possibility of incorporating data obtained in real time into an executing application, in particular a simulation. This paper reports on the first phase of our research in which we have used this idea to enhance the simulation quality of a river flow simulator by dynamic data inputs during the computational execution. We had presented an optimization methodology of this simulator model in previous works but in this opportunity, we could handle those time periods when a sudden level change takes place inthe river and we could improve the forecasting prediction. These results are the path towards the development of an automatic calibration framework fed with real-time data.Instituto de Investigación en InformáticaInstituto de Investigación en Informátic

Parallel matrix multiplication on heterogeneous networks of workstations

Matrix multiplication is taken as a test bed for parallel processing on heterogeneous networks of workstations (local area networks) used as parallel machines. Two algorithms are proposed taking into account the specific kind of parallel hardware provided by local area networks, and experimentation is used to drive the evaluation and identification of possible performance loss. A specific broadcast communication between processes of a parallel application is also proposed, taking advantage of the Ethernet interconnection network to achieve optimized performance. A special emphasis is place on already installed networks of workstations, which provide a hardware zero cost parallel computer; but a homogeneous Beowulf-class system is used to show how the algorithms are also useful on current classical high performance parallel computing with clusters.Eje: LenguajesRed de Universidades con Carreras en Informática (RedUNCI

Adjustment of a simulator of a complex dynamic system with emphasis on the reduction of computational resources

Scientists and engineers continuously build models to interpret axiomatic theories or explain the reality of the universe of interest to reduce the gap between formal theory and observation in practice. We focus our work on dealing with the uncertainty of the input data of the model to improve the quality of the simulation. To perform this type of process large volumes of data and a lot of computer processing must be handled. This article proposes a methodology for adjusting a simulator of a complex dynamic system that models the wave translation along rivers channels, with emphasis on the reduction of computation resources. We propose a simulator calibration by using a methodology based on successive adjustment steps of the model. We based our process in a parametric simulation. The input scenarios used to run the simulator at every step were obtained in an agile way, achieving a model improvement up to 50% in the reduction of the simulated data error. These results encouraged us to extend the adjustment process over a larger domain region.Facultad de Informátic

Adjustment of a simulator of a complex dynamic system with emphasis on the reduction of computational resources

Scientists and engineers continuously build models to interpret axiomatic theories or explain the reality of the universe of interest to reduce the gap between formal theory and observation in practice. We focus our work on dealing with the uncertainty of the input data of the model to improve the quality of the simulation. To perform this type of process large volumes of data and a lot of computer processing must be handled. This article proposes a methodology for adjusting a simulator of a complex dynamic system that models the wave translation along rivers channels, with emphasis on the reduction of computation resources. We propose a simulator calibration by using a methodology based on successive adjustment steps of the model. We based our process in a parametric simulation. The input scenarios used to run the simulator at every step were obtained in an agile way, achieving a model improvement up to 50% in the reduction of the simulated data error. These results encouraged us to extend the adjustment process over a larger domain region.Facultad de Informátic

Adjustment of a simulator of a complex dynamic system with emphasis on the reduction of computational resources

Scientists and engineers continuously build models to interpret axiomatic theories or explain the reality of the universe of interest to reduce the gap between formal theory and observation in practice. We focus our work on dealing with the uncertainty of the input data of the model to improve the quality of the simulation. To perform this type of process large volumes of data and a lot of computer processing must be handled. This article proposes a methodology for adjusting a simulator of a complex dynamic system that models the wave translation along rivers channels, with emphasis on the reduction of computation resources. We propose a simulator calibration by using a methodology based on successive adjustment steps of the model. We based our process in a parametric simulation. The input scenarios used to run the simulator at every step were obtained in an agile way, achieving a model improvement up to 50% in the reduction of the simulated data error. These results encouraged us to extend the adjustment process over a larger domain region.Facultad de Informátic

Preserving message integrity in dynamic process migration

Processor and network management have a great impact on the performance of Distributed Memory Parallel Computers. Dynamic Process Migration allows load balancing and communication balancing at execution time. Managing the communications involving the migrating process is one of the problems that Dynamic Process Migration implies. To study this problem, which we have called the Message Integrity Problem, six algorithms have been analysed. These algorithms have been studied by sequential simulation, and have also been implemented in a parallel machine for different user process patterns in the presence of dynamic migration. To compare the algorithms, different performance parameters have been considered. The results obtained have given preliminary information about the algorithms behaviour, and have allowed us to perform an initial comparative evaluation among them

Preserving message integrity in dynamic process migration

Processor and network management have a great impact on the performance of Distributed Memory Parallel Computers. Dynamic Process Migration allows load balancing and communication balancing at execution time. Managing the communications involving the migrating process is one of the problems that Dynamic Process Migration implies. To study this problem, which we have called the Message Integrity Problem, six algorithms have been analysed. These algorithms have been studied by sequential simulation, and have also been implemented in a parallel machine for different user process patterns in the presence of dynamic migration. To compare the algorithms, different performance parameters have been considered. The results obtained have given preliminary information about the algorithms behaviour, and have allowed us to perform an initial comparative evaluation among them.Facultad de Informátic

Job scheduling considering best-effort and soft real-time applications on non-dedicated clusters

As Network Of Workstations (NOWs) emerge as a viable platform for a wide range of workloads, new scheduling approaches are needed to allocate the collection of resources from competing applications. New workload types introduce high uncertainty into the predictability of the system, hindering the applicability of the job scheduling strategies. A new kind of parallel applications has appeared in business or scientific domains, namely Soft Real-Time (SRT). They, together with new SRT desktop applications, turn prediction into a more difficult goal by adding inherent complexity to estimation procedures. In previous work, we introduced an estimation engine into our job scheduling system, termed CISNE. In this work, the estimation engine is extended, by adding two new kernels, both SRT aware. Experimental results confirm the better performance of simulated respect to the analytical kernels and show a maximum average prediction error deviation of 20%.Mientras las Redes de Estaciones de Trabajo (NOWs) emergen como una plataforma viable para un amplio espectro de aplicaciones, son necesarios nuevos enfoques para planificar los recursos disponibles entre las aplicaciones que compiten por ellos. Los nuevos tipos de cargas introducen una alta incertidumbre en la predictibilidad del sistema, afectando la aplicabilidad de las estrategias de planificación de tareas. Un nuevo tipo de aplicaciones paralelas, denominado tiempo real débil (SRT), ha aparecido tanto en los ámbitos comerciales como científicos. Las nuevas aplicaciones paralelas SRT, conjuntamente con los nuevos tipos de aplicaciones SRT de escritorio, convierten la predicción en una meta aún más difícil, al agregar complejidad a los procedimientos de estimación. En trabajos anteriores dotamos al sistema CISNE de un motor de estimación. En este trabajo añadimos al sistema de predicción fuera de línea dos nuevos núcleos de estimación con capacidad SRT. Los resultados experimentales muestran un mejor rendimiento del núcleo simulado con respecto a su homólogo analítico, mostrando un promedio de desviación máximo del 20%.VIII Workshop de Procesamiento Distribuido y ParaleloRed de Universidades con Carreras en Informática (RedUNCI

A multipath routing method for tolerating permanent and non-permanent faults

The intensive and continuous use of high-performance computers for executing computationally intensive applications, coupled with the large number of elements that make them up, dramatically increase the likelihood of failures during their operation. The interconnection network is a critical part of such systems, therefore, network faults have an extremely high impact because most routing algorithms are not designed to tolerate faults. In such algorithms, just a single fault may stall messages in the network, preventing the finalization of applications, or may lead to deadlocked confi gurations. This work focuses on the problem of fault tolerance for high-speed interconnection networks by designing a fault-tolerant routing method to solve an unbounded number of dynamic faults (permanent and non- permanent). To accomplish this task we take advantage of the communication path redundancy, by means of a multipath routing approach. Experiments show that our method allows applications to finalize their execution in the presence of several number of faults, with an average performance value of 97% compared to the fault-free scenarios.Presentado en el IX Workshop Procesamiento Distribuido y Paralelo (WPDP)Red de Universidades con Carreras en Informática (RedUNCI

Implementing sub steps in a parallel automata cellular model

Computer simulations using Cellular Automata (CA) have been applied with considerable success in different scientific areas. In this work we use CA in order to specify and implement a simulation model that allows to investigate behavioural dynamics for pedestrians in an emergency evacuation. A CA model is discrete and handled by rules. However several aspects of the crown behaviour should appear as a continuous phenomenon. In this paper we implement the sub steps technique in order to solve an unexpected phenomenon: the formation of holes (empty cells) both around the exit and mixed in the crowd evacuation. The holes occur when individuals of consecutive cells want move towards an exit. Additionally, the methodology allowed us to include, as a new parameter of the model, speeds associated to the pedestrians. Due to the incorporation of new features, the model complexity increases. We apply a parallel technique in order to accelerate the simulation and take advantage of modern computer architectures. We test our approaches to several environment configurations achieving important reduction of simulation time and the total evacuation time.Presentado en el XI Workshop Procesamiento Distribuido y Paralelo (WPDP)Red de Universidades con Carreras en Informática (RedUNCI