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Este trabalho tem como objetivo analisar a influência provocada pelas políticas de substituição de objetos em caches na Web. Isso é feito por meio da investigação das políticas existentes na literatura, considerando um estudo de caracterização de carga, de avaliação de desempenho e de comparação do uso dessas políticas. Para realizar a avaliação das políticas é utilizado um simulador de caches para a Web. Durante a pesquisa, foi desenvolvida uma nova política, denominada MeMoExP. Ela utiliza os conceitos de Média Móvel para otimizar HR e BHR. As simulações realizadas mostraram que a MeMoExP segue a mesma tendência da política FBR, tida como eficiente na literatura. Finalmente, são expostas algumas ponderações sobre as idéias apresentadas nos capítulos componentes desta dissertação, além de serem apresentadas as contribuições provenientes desta pesquisa e alguns trabalhos futuros propostos a partir desta dissertação. / This work aims to analise the influence of the replacement policies on web caches. This is carried out by investigating the policies found at the literature, considering an study of load characterization and performance assessment as well as a comparison between the policies' usage. All the experiments are done using a web cache simulator. During the research, it was developed a new policie, called MeMoExp. It utilizes the concept of Moving Exponencial Average to optimize the HR and BHR metrics. The simulation studies showed that the MeMoExP policie follows the same tendency than the FBR metric, which is considered efficient in the literature. Finally, some considerations about the ideas presented in the dissertation are exposed. The contributions of this research work are presented and some future works are proposed.

Este trabalho tem como objetivo analisar a influência provocada pelas políticas de substituição de objetos em caches na Web. Isso é feito por meio da investigação das políticas existentes na literatura, considerando um estudo de caracterização de carga, de avaliação de desempenho e de comparação do uso dessas políticas. Para realizar a avaliação das políticas é utilizado um simulador de caches para a Web. Durante a pesquisa, foi desenvolvida uma nova política, denominada MeMoExP. Ela utiliza os conceitos de Média Móvel para otimizar HR e BHR. As simulações realizadas mostraram que a MeMoExP segue a mesma tendência da política FBR, tida como eficiente na literatura. Finalmente, são expostas algumas ponderações sobre as idéias apresentadas nos capítulos componentes desta dissertação, além de serem apresentadas as contribuições provenientes desta pesquisa e alguns trabalhos futuros propostos a partir desta dissertação. / This work aims to analise the influence of the replacement policies on web caches. This is carried out by investigating the policies found at the literature, considering an study of load characterization and performance assessment as well as a comparison between the policies' usage. All the experiments are done using a web cache simulator. During the research, it was developed a new policie, called MeMoExp. It utilizes the concept of Moving Exponencial Average to optimize the HR and BHR metrics. The simulation studies showed that the MeMoExP policie follows the same tendency than the FBR metric, which is considered efficient in the literature. Finally, some considerations about the ideas presented in the dissertation are exposed. The contributions of this research work are presented and some future works are proposed.

Cache replacement policies can play a pivotal role in the overall performance of a system by preserving data locality and thus limiting the o -chip accesses. In a shared memory system, a cache coherence protocol is necessary to ensure correctness of data computations by maintaining the state of entries in the cache. In this work we attempt to build and investigate the effect of cache replacement policies using the information provided by cache coherence protocol states. The cache coherence protocol states give us an idea about the state of entry with respect to other cores in the system. State based analysis of SPLASH-2 and PARSEC benchmark suites show that this information hints us towards the locality patterns of cache blocks, which can be used to prioritize the order of replacement of a cache states in a replacement policy. We model ten di erent cache state based replacement policies, three having xed priorities and seven whose priorities vary dynamically over the most recently used state. We compare these policies against the standard replacement policies (LRU, FIFO and Random) in terms of system performance and ease of implementation. We develop our simulation framework using the Multi2Sim simulator, where we model cache state based replacement policies. We simulate SPLASH-2 and PARSEC benchmark suites over a variety of con gurations, where we vary the number of cores, associatively for each level of cache, private/shared L2 cache. We characterize the programs to find out critical components for performance. For an 8-core system we observe that the best case among these state based replacement policies shows marginal improvements in IPC over the Random and FIFO policies, falling slightly short of LRU. We design the state based replacement policies using a smaller cache (CSL-cache), which is used to store the state information of the blocks in the main cache. The CSL cache communicates with the controller to provide the replacement entry. The complexity associated with the system is equal to FIFO and is independent of the associatively of the cache.

Internet est un véritable écosystème. Il se développe, évolue et s’adapte aux besoins des utilisateurs en termes de communication, de connectivité et d’ubiquité. Dans la dernière décennie, les modèles de communication ont changé passant des interactions machine-à-machine à un modèle machine-à-contenu. Cependant, différentes technologies sans-fil et de réseaux (tels que les smartphones et les réseaux 3/4G, streaming en ligne des médias, les réseaux sociaux, réseaux-orientés contenus) sont apparues pour améliorer la distribution de l’information. Ce développement a mis en lumière les problèmes liés au passage à l’échelle et à l’efficacité énergétique; d’où la question: Comment concevoir ou optimiser de tels systèmes distribués qui garantissent un accès haut débit aux contenus tout en (i) réduisant la congestion et la consommation d’énergie dans le réseau et (ii) s’adaptant à la demande des utilisateurs dans un contexte connectivité quasi-permanente? Dans cette thèse, nous nous intéressons à deux solutions proposées pour répondre à cette question: le déploiement des réseaux de caches et l’implantation des protocoles économes en énergie. Précisément, nous proposons des modèles analytiques pour la conception de ces réseaux de stockage et la modélisation de la consommation d’énergie dans les réseaux d’accès sans fil. Nos études montrent que la prédiction de la performance des réseaux de caches réels peut être faite avec des erreurs relatives absolues de l’ordre de 1% à 5% et qu’une proportion importante soit 70% à 90% du coût de l’énergie dans les cellules peut être économisée au niveau des stations de base et des mobiles sous des conditions réelles de trafic. / Internet is a real ecosystem. It grows, evolves and adapts to the needs of users in terms of communication, connectivity and ubiquity of users. In the last decade, the communication paradigm has shifted from traditional host-to-host interactions to the recent host-to-content model; while various wireless and networking technologies (such as 3/4G smartphones and networks, online media streaming, social networks, clouds, Big-Data, information-centric networks) emerged to enhance content distribution. This development shed light on scalability and energy efficiency issues which can be formulated as follows. How can we design or optimize such large scale distributed systems in order to achieve and maintain high-speed access to contents while (i) reducing congestion and energy consumption in the network and (ii) adapting to the temporal locality of users demand in a continuous connectivity paradigm? In this thesis we focus on two solutions proposed to answer this question: In-network caching and Power save protocols for scalability and energy efficiency issues respectively. Precisely, we propose analytic models for designing core cache networks and modeling energy consumption in wireless access networks. Our studies show that the prediction of the performance of general core cache networks in real application cases can be done with absolute relative errors of order of 1%–5%; meanwhile, dramatic energy save can be achieved by mobile devices and base stations, e.g., as much as 70%–90% of the energy cost in cells with realistic traffic load and the considered parameter settings.