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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Análise de algoritmos distribuídos para escalonamento em Data Grids / Analysis of distributed algorithms for scheduling in Data Grids

Lourenço, Gustavo Vilaça 18 April 2012 (has links)
É um resultado conhecido que em Data Grids, onde o processamento envolve grandes quantidades de dados, pode ser mais eficaz escalonar os processos para execução nos sites que já dispõem dos dados do que transferir os dados para um site onde o processo que irá necessitar deles foi escalonado. Os estudos existentes se baseiam em pequenas quantidades de sites, com conhecimento centralizado sobre o estado dos diversos sites. Essa opção não é escalável para Grids com grande número de participantes. Este trabalho analisa versões distribuídas com informação local para os algoritmos de escalonamento de processo e replicação de dados, mostrando o efeito das topologias de interconexão de sites no desempenho desses. É observado que, considerando a existência apenas de informações locais devido às restrições topologicas, resultados diferentes quanto aos melhores algoritmos de escalonamento de processos e replicação de dados são encontrados. / It is a known result that in Data Grids, where the processing involves large amounts of data, can be more effective schedule processes to run on sites that already have the data than transfering data to a site where the process that will require them was installed. The existing studies are based on small numbers of sites, with centralized knowledge about the state of the various sites. This option is not scalable for grids with large numbers of participants. This paper will propose distributed versions with local information for process scheduling algorithms and data replication, showing the effect of interconnect topologies on the performance of these sites. It is observed that, considering the existence of only local information due to topological constraints, different results related to the best scheduling algorithms and data replication processes are found.
2

Análise de algoritmos distribuídos para escalonamento em Data Grids / Analysis of distributed algorithms for scheduling in Data Grids

Gustavo Vilaça Lourenço 18 April 2012 (has links)
É um resultado conhecido que em Data Grids, onde o processamento envolve grandes quantidades de dados, pode ser mais eficaz escalonar os processos para execução nos sites que já dispõem dos dados do que transferir os dados para um site onde o processo que irá necessitar deles foi escalonado. Os estudos existentes se baseiam em pequenas quantidades de sites, com conhecimento centralizado sobre o estado dos diversos sites. Essa opção não é escalável para Grids com grande número de participantes. Este trabalho analisa versões distribuídas com informação local para os algoritmos de escalonamento de processo e replicação de dados, mostrando o efeito das topologias de interconexão de sites no desempenho desses. É observado que, considerando a existência apenas de informações locais devido às restrições topologicas, resultados diferentes quanto aos melhores algoritmos de escalonamento de processos e replicação de dados são encontrados. / It is a known result that in Data Grids, where the processing involves large amounts of data, can be more effective schedule processes to run on sites that already have the data than transfering data to a site where the process that will require them was installed. The existing studies are based on small numbers of sites, with centralized knowledge about the state of the various sites. This option is not scalable for grids with large numbers of participants. This paper will propose distributed versions with local information for process scheduling algorithms and data replication, showing the effect of interconnect topologies on the performance of these sites. It is observed that, considering the existence of only local information due to topological constraints, different results related to the best scheduling algorithms and data replication processes are found.
3

Maintenance et simulation de graphes aléatoires dynamiques / Maintenance and simulation of dynamic random graphs

Duvignau, Romaric 16 October 2015 (has links)
Nous étudions le problème de maintenir une distribution donnée de graphes aléatoires après une séquence arbitraire d’insertions et de suppressions de sommets. Dans l’objectif de modéliser l’évolution de réseaux logiques dynamiques,nous travaillons dans un modèle local où l’accès à la liste des sommets est restreint. À la place, nous faisons l’hypothèse d’un accès à une primitive globale qui retourne un sommet aléatoire, choisi uniformément dans l’ensemble total des sommets. Le problème de maintenance a été exploré sur plusieurs modèles simples de graphes aléatoires (graphes d’Erdos–Rényi, graphes basés sur le modèle par paires, graphes k-sortants uniformes). Pour chacun des modèles, un ou plusieurs algorithmes pour la tâche de maintenance ont été décris et analysés ; les plus élaborés de ces algorithmes sont asymptotiquement optimaux. Le problème de maintenance soulève plusieurs problèmes de simulation liés à notre contexte distribué. Nous nous sommes intéressé en particulier à la maintenabilité de distributions de graphes et à la simulabilité de familles de distributions de probabilité sur les entiers, dans le modèle d’aléa présenté.Une attention particulière a été portée sur la simulation efficace de lois spécifiques nous intéressant (certaines lois binomiales). Cette dernière a pu être obtenue en exploitant les propriétés d’un nouvel arbre de génération pour les permutations, que nous avons introduit. / We study the problem of maintaining a given distribution of randomgraphs under an arbitrary sequence of vertex insertions and deletions. Keeping inmind our objective to model the evolution of dynamic logical networks, we work ina local model where we do not have direct access to the list of all vertices. Instead,we assume access to a global primitive that returns a random vertex, chosen uniformlyfrom the whole vertex set. The maintenance problem has been explored onseveral simple random graph models (Erdos–Rényi random graphs, pairing modelbased random graphs, uniform k-out graphs). For each model, one or several updatealgorithms for the maintenance task have been described and analyzed ; the mostelaborate of them are asymptically optimal. The maintenance task rise several simulationissues linked to our distributed context. In particular, we have focused onmaintenability of random graph distributions and simulability of families of probabilitydistributions over integers in our local random model. Special attention hasbeen paid to efficient simulation of particular distributions we were interested in(certain binomial distributions). The latter has been obtained through the use ofproperties of a new generation tree for permutations, which has been introducedalong the way

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