Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnologico / Made available in DSpace on 2016-01-08T19:53:19Z (GMT). No. of bitstreams: 1 99227.pdf: 1448705 bytes, checksum: a068a40fabbc7b22d1abb1d08aac8dd3 (MD5) Previous issue date: 1995 / Projeto e implementação de um sistema operacional para multicomputador, fundamentado no modelo cliente-servidor, com micronúcleo distribuído e interface de programação compatível com a do sistema Unix, objetivando a exploração do paralelismo a nível de aplicações e de sistemas. Construção de um simulador multiprogramado para um multicomputador com rede de interconexão dinâmica, objetivando servir como plataforma para a implementação do sistema operacional proposto.Projeto e implementação de um sistema operacional para multicomputador, fundamentado no modelo cliente-servidor, com micronúcleo distribuído e interface de programação compatível com a do sistema Unix, objetivando a exploração do paralelismo a nível de aplicações e de sistemas. Construção de um simulador multiprogramado para um multicomputador com rede de interconexão dinâmica, objetivando servir como plataforma para a implementação do sistema operacional proposto.

Orientador : Paulo Licio de Geus / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Computação / Made available in DSpace on 2018-07-27T19:46:30Z (GMT). No. of bitstreams: 1 Nakamura_EmilioTissato_M.pdf: 36776274 bytes, checksum: fa38223e86febdb41dd5e61932e54df1 (MD5) Previous issue date: 2000 / Resumo: A principal característica de um ambiente cooperativo é a complexidade das conexões lógicas. Isso traz como conseqüência uma série de implicações de segurança. Diferentes níveis de acesso são agora utilizados para recursos, antes disponíveis apenas internamente, a partir de múltiplas e heterogêneas conexões. Isso faz com que a abordagem clássica dos firewalls, de criar uma separação entre a rede da organização e a rede pública, já não baste. Diversos conceitos e tecnologias têm que ser utilizados para que a segurança seja provida em ambientes cooperativos. Mais do que isso, um modelo de segurança também é necessário. Assim, este trabalho tem como objetivo apresentar tais conceitos e tecnologias de segurança, e propor um modelo para que eles possam proteger de fato um ambiente cooperativo. Política de segurança,firewalls, sistemas de detecção de intrusões, redes privadas virtuais, infra-estrutura de chaves públicas e autenticação são os tópicos abordados neste trabalho. O modelo de segurança proposto é formado por três elementos: i) o firewall cooperativo, que sugere uma arquitetura de segurança para a integração das diferentes tecnologias e conceitos; ii) um modo de minimizar os problemas resultantes da complexidade das regras de filtragem e iii) um modelo de cinco níveis hierárquicos de defesa, que visa facilitar a compreensão dos problemas de segurança existentes, e assim minimizar as possibilidades de erros na definição da estratégia de defesa da organização / Abstract: The main charaeteristic of a cooperative environment is the complexity of logical connections. This brings about a series of security implications. Different access levels are now used for resources, previously available only internally, from multiple and heterogeneous connections. This makes the classical approach to firewalls, that of creating a division between the organization's and the public networks, no longer enough for the task. Diverse conecpts and technologies need to be employed to provide security to cooperative environments. More than that, a security model is also needed. As such, this work has as its main goal to present such security concepts and teehnologies and to propose a framework 50 that they may in fact protect a cooperative environment. Security poliey, firewalls, intrusion detection systems, virtual private networks, public key infrastructure and authentication are the topies discussed in this work. The security model proposed is made of three e!ements: í) the cooperative firewall, which suggests a security architecture for the integration of different concepts and technologies; ii) a way of minimizing the problems resulting from the complexity of filtering rules and iii) a 5-leveI hierarchical defense model, which intends to case the understanding of existing security problems, so that the process of defining the organization's defense strategy is made less error-prone / Mestrado / Mestre em Ciência da Computação

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Diploma thesis is focused on the supporting of Quality of Services in wireless networks, especially in the Linux operation systems. The topic is connected not only with OS, but also with the wireless standard, which supports QoS in wireless networks called IEEE 802.11e. QoS is needed especially for time-consuming data transfers in real time. The theoretical part deals with the theoretical analysis of the issue of the QoS support. There are described parameters, which occurred in quality of services support. This section also deals with the division of services that are used to transmit data across computer networks. It also describes the QoS support in wireless networks according 802.11e, its implementation and methods of accessing a medium with a without possibility of traffic. This part is followed by a description of QoS support in UNIX operating systems. The chapter describes how is the QoS support designed in these operating systems. There are also characterized concrete tools which are used for control the data flow in the operating systems using Linux. At the end the theoretical part deals with different types of queues and methods used in linux OS. In the practical part of the thesis, there are various designed topologies and scenarios to verify the functionality of QoS support in wireless networks using a Unix system. These chapters show the results of different tests at selected transmission data streams that are sensitive to transmission time. There is also verified cooperation of QoS support between devices operating on the network and data link layers. The output of this work is to design a laboratory exercise for the subject Network Architecture. This exercise is focused on familiarization with the QoS support functionality in wireless networks and in Unix-like operating systems. This chapter also describes the devices and programs that are needed to measure this task. The last part of the chapter describes the procedure for the preparation of the measuring station. For this laboratory task, there is an inserted manual in the annex.

Im Unix-Umfeld existieren zahlreiche Kommandointerpreter (Shells) unterschiedlichen Leistungsvermögens. Die Bourne-Again-Shell (bash) vereinigt die Fähigkeiten zahlreicher alternativer Shellimplementierungen und hat sich seit langem im Umfeld der freien Software etabliert. Obwohl erste Implementierungen der Version 2 bereits aus dem Jahr 1996 stammen, löst sie erst in den neueren Linux-Distributionen die Version 1.14 ab. Im Einzelnen geht es um: - Ausgewählte Fähigkeiten der bash - Neuerungen der bash, Version 2 - Die bash aus Sicht der Systemadministration

Modelling is an important technique in the comprehension and management of complex systems. Queueing network models capture most relevant information from computer system and network behaviour. The construction and resolution of these models is constrained by many factors. Approximations contain detail lost for exact solution and/or provide results at lower cost than simulation. Information at the resource and interactive command level is gathered with monitors under ULTRIX'. Validation studies indicate central processor service times are highly variable on the system. More pessimistic predictions assuming this variability are in part verified by observation. The utility of the Generalised Exponential (GE) as a distribution parameterised by mean and variance is explored. Small networks of GE service centres can be solved exactly using methods proposed for Generalised Stochastic Petri Nets. For two centre. systems of GE type a new technique simplifying the balance equations is developed. A very efficient "building bglloocbka"l. is presented for exactly solving two centre systems with service or transfer blocking, Bernoulli feedback and load dependent rate, multiple GE servers. In the tandem finite buffer algorithm the building block illustrates problems encountered modelling high variability in blocking networks. ': . _. A parametric validation study is made of approximations for single class closed networks of First-Come-First-Served (FCFS) centres with general service times. The multiserver extension using the building block is validated. Finally the Maximum Entropy approximation is extended to FCFS centres with multiple chains and implemented with computationally efficient convolution.

<p>The project has been carried out at, and in association with, Micronic Laser Systems AB in Täby, Sweden. Micronic Laser Systems, manufacture laser pattern generators for the semiconductor and display markets. Laser pattern generators are used to create photomasks, which are a key component in the microlithographic process of manufacturing microchips and displays. </p><p>An essential problem to all modern semiconductor manufacturing is the constantly decreasing sizes of features and increasing use of resolution enhancement techniques (RET), leading to ever growing sizes of datasets describing the semiconductors. When sizes of datasets reach magnitudes of hundreds of gigabytes, visualisation, navigation and editing of any such dataset becomes extremely difficult. As of today this problem has no satisfying solution. </p><p>The project aims at the proposal of a geometry engine that effectively can deal with the evergrowing sizes of modern semiconductor lithography. This involves a new approach to handling data, a new format for spatial description of the datasets, hardware accelerated rendering and support for multiprocessor and distributed systems. The project has been executed without implying changes to existing data formats and the resulting application is executable on Micronics currently existing hardware platforms. </p><p>The performance of the new viewer system surpasses any old implementation by a varying factor. If rendering speed is the comparative factor, the new system is about 10-20 times faster than its old counterparts. In some cases, when hard disk access speed is the limiting factor, the new implementation is only slightly faster or as fast. And finally, spatial indexing allow some operations that previously lasted several hours, to complete in a few seconds, by eliminating all unnecessary disk-reading operations.</p>

Selecting the correct inter-process communication method isan important aspect of ensuring effective inter-vm and inter-container process communication. We will conduct a study ofIPC methods which might be useful and fits the Qemu/KVMvirtual machine and Docker container environments, and se-lect those that fit our criteria. After implementing our chosenmethods we will benchmark them in a test suite to find theones with highest performance in terms of speed. Our resultsshow that, at the most common message sizes, Unix DomainSockets work best for containers and Transparent Inter Pro-cess Communication has the best performance between vir-tual machines out of the chosen methods.

Orientador : Paulo Licio de Geus / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Computação / Made available in DSpace on 2018-08-01T14:55:00Z (GMT). No. of bitstreams: 1 Hirata_Renato_M.pdf: 5857741 bytes, checksum: 8e1fa8af7605a4c06b6ef0174dc317a5 (MD5) Previous issue date: 2002 / Resumo: Com o explosivo crescimento da Web, sua popularização e sua grande importância como meio de comunicação global, cada vez mais a atenção se volta para questões de desempenho. Pelo fato de ser um serviço relativamente recente, são poucos os estudos que abordam de modo geral todos os fatores que influenciam no seu desempenho e como tais fatores estão inter-relacionados. Assim, o objetivo deste trabalho é abordar o problema de desempenho na Web como um todo, levantando e analisando todos os componentes relacionados, fornecendo embasamento teórico para o entendimento desses tópicos e apresentando suas possíveis soluções, de forma a cobrir esta lacuna na bibliografia existente. Em especial, se concentra em tópicos de software na porção servidora de sistemas de grande demanda. Como resultado, o leitor encontrará um texto único na otimização servidores de grande porte, que é um trabalho de referência e ao mesmo tempo um guia de otimização / Abstract: With the Web explosive growth, its popularization and its great importance as a way of global communication, more and more attention is devoted to its performance issues. Due to the Web being a relatively new service, very few works approach the issue of performance affecting factors in a broad sense, as well as their inter-relationship. The goal of this work is to fill that gap by enumerating and analyzing every component that affects Web performance. This is done by covering theoretical issues for a clear understanding of all topics involved and by presenting possible solutions and suggestions. The main focus of this work is on the server portion of high performance systems. As a result, the reader will find a unique text on optimizing performance of very large Web sites, that is both a reference work and a tuning guide / Mestrado / Mestre em Ciência da Computação

HBFG-ProjektMONARCH Version 1.2 Unerwuenschte Botschaften: E-Mail-Spams Cross-Zertifizierung DFN -- IN e.V. Campusnetzzugang in Hoersaelen StarOffice fuer Linux Freeware, Shareware und Public Domain (Softwarerecht) Weihnachtswuensche Coverage{10}: 22.12.2017