Processos e Threads

O material apresenta processos e threads (tarefas). Destaca a necessidade da criação de um código executável apropriado para a arquitetura (processador) e do sistema operacional do computador onde se deseja executá-lo. Além do código e das áreas de dados, diversas informações de controle precisam ser mantidas pelo Sistema Operacional para um processo em execução. O texto também apresenta processos no sistema operacional UNIX, os processos leves - threads ou linhas de execução, as vantagens do uso de threads, exemplo de programa Java que utiliza threads, e por fim, traz exercícios resolvidos sobre conceitos de processos na literatura técnica e mecanismo.

Gerenciamento de Threads - Slides

O material apresenta o gerenciamento de threads no Windows. Um sistema operacional envolve atividades assíncronas e algumas vezes paralelas, sendo que a noção de processo de software é usada em sistemas operacionais para expressar o gerenciamento e controle de suas atividades. Processo é um dos conceitos fundamentais no projeto de um sistema operacional moderno. Threads podem ser gerenciados pelo sistema operacional ou pela aplicação do usuário. Além desses conceitos, o material destaca a motivação para o uso de threads; o parâmetro CreateThread; e a prioridade e escalonamento.

Sistemas Operacionais

O material apresenta sistemas operacionais, destacando visões do Sistema Operacional (Máquina abstrata / Gerente de recursos), Processos (programas em execução), Thread (linha de execução de um processo), Múltiplos processos (Multitasking), Tipos de processos, Escalonamento e Interrupções. O texto também traz as Chamadas de Sistema (serviços oferecidos pelo Sistema Operacional para os programas), o Gerenciamento de memória, a Memória virtual, os Sistemas de Arquivo e o Sistema Entrada/Saída.

Gerência de Memória

O material apresenta o gerenciamento de memória, realizado por meio do sistema operacional e manipulada por elementos específicos do hardware. Para que os processos sejam executados, é preciso que tanto seus códigos (suas sequências de instruções) quanto os dados que eles manipulam sejam carregados na memória principal. O gerenciamento do uso da memória tem grande influência sobre a quantidade de processos que podem ser executados ao mesmo tempo. As estratégias de gerência de memória realizadas por um Sistema Operacional estão relacionadas à decisões sobre como a memória será ocupada pelos processos, sobre o local onde cada processo deve ser carregado, por quanto tempo um processo deve permanecer carregado na memória, etc. Além desses aspectos, o material também destaca as principais estratégias de gerência de memória, os aspectos fundamentais sobre o funcionamento dos sistemas de memória; os mecanismos de gerenciamento de memória virtual, os sistemas monotarefa e monousuário, a relocação de endereços, o uso de registradores especiais no hardware, denominados registrador base e limite e a técnica de multiprogramação.

Processos e Threads

A videoaula apresenta os principais conceitos sobre processos e threads com destaque para estados de processo e transições, blocos de controle de processos e descritores, chaveamento de processos e troca de contexto, comunicação interprocessos (IPC), processos no Unix, semelhanças e diferenças entre processos e threads, o ciclo de vida de um thread e, por fim, conceitos básicos sobre threads POSIX, Linux, Windows XP e Java.

Acesso a dados em memória secundária [Audiodescrição]

Versão com menu acessível para leitores de tela e vídeo com audiodescrição.

Utilizando a porta paralela para controle remoto de um dispositivo

VALENTIM, R. A. M.; NOGUEIRA, I. A.;ROCHA NETO, A. F. Utilizando a porta paralela para controle remoto de um dispositivo. Revista da FARN, Natal, v. 2, p. 103-114, 2002.

Corpo e saúde: reflexões sobre o quadro "Medida Certa"

The present scenario is permeated by different comprehensions about the body and health. These are the result of a historical process experienced by men in different times and social contexts through which were being built. Faced this scenario, we emphasize the media as a powerful means of information and training ideas regarding the body and health of theses. The media also as a means of mediating information we present characteristics of the social scenario where is inserted. In our research we bring reflects about the comprehensions, knowledge and practices propagated by the way the body and health under "Medida Certa" of the program Fantastico the broadcaster Globo Telecommunications, in order to identify how Physical Education, has contributed the construction of knowledge disseminated. Therefore, we focus our analysis to the table "Medida Certa" exhibited by Fantastico in the months of April, May and June of 2011.The data for analysis were collected through the videos shown live in Fantastic and the information provided in the blog that table. Thus, we had 14 videos shown live, 16 videos posted on the blog, 97 posts in blog. As technique of analysis of the datas used of content analysis of the Bardin (2011). About body obtained as analytical categories: body as operating system; biological body; fragmented body exterior to the subject; body trailer quantified to patterns; subject body. How to health we analyze the categories of health existential: health existential based in biological indices of normality; health existential associated with weight loss and aesthetic patterns; health existential associated with physical activity and nutritional control; and finally we propose a comprehension of health existential. Therefore, from the analysis of the data evidenced a predominance of comprehensions, knowledge and practices about the body and health guided the biological constituents of the body, quantification and classification in medium and normal patterns on pervasive forms of care, in the linear association among physical activity and nutritional control with health, evidenced that Physical Education has contributed to these constructions, through some of his discourses with emphasis on biological aspects. Thus, in our study we advocate an understanding of not only the body as object, but also as a subject clipped by organic, cultural, historical and social elements, a living body, feeling, desire and above all expresses itself, and health viewed as something body, interlaced through the biological, cultural, historical and emotional aspects of this body that coexist in this society

Proposta de integração das redes de comunicação da COSERN como uma solução de contigêncvia em caso de falhas nos enlaces do backbone de automação

T'his dissertation proposes alternative models to allow the interconnectioin of the data communication networks of COSERN Companhia Energética do Rio Grande do Norte. These networks comprise the oorporative data network, based on TCP/IP architecture, and the automation system linking remote electric energy distribution substations to the main Operatin Centre, based on digital radio links and using the IEC 60870-5-101 protoco1s. The envisaged interconnection aims to provide automation data originated from substations with a contingent route to the Operation Center, in moments of failure or maintenance of the digital radio links. Among the presented models, the one chosen for development consists of a computational prototype based on a standard personal computer, working under LINUX operational system and running na application, developesd in C language, wich functions as a Gateway between the protocols of the TCP/IP stack and the IEC 60870-5-101 suite. So, it is described this model analysis, implementation and tests of functionality and performance. During the test phase it was basically verified the delay introduced by the TCP/IP network when transporting automation data, in order to guarantee that it was cionsistent with the time periods present on the automation network. Besides , additional modules are suggested to the prototype, in order to handle other issues such as security and prioriz\ation of the automation system data, whenever they are travesing the TCP/IP network. Finally, a study hás been done aiming to integrate, in more complete way, the two considered networks. It uses IP platform as a solution of convergence to the communication subsystem of na unified network, as the most recente market tendencies for supervisory and other automation systems indicate

Um ambiente integrado para manipulação de tráfego multicast

In the two last decades of the past century, following the consolidation of the Internet as the world-wide computer network, applications generating more robust data flows started to appear. The increasing use of videoconferencing stimulated the creation of a new form of point-to-multipoint transmission called IP Multicast. All companies working in the area of software and the hardware development for network videoconferencing have adjusted their products as well as developed new solutionsfor the use of multicast. However the configuration of such different solutions is not easy done, moreover when changes in the operational system are also requirede. Besides, the existing free tools have limited functions, and the current comercial solutions are heavily dependent on specific platforms. Along with the maturity of IP Multicast technology and with its inclusion in all the current operational systems, the object-oriented programming languages had developed classes able to handle multicast traflic. So, with the help of Java APIs for network, data bases and hipertext, it became possible to the develop an Integrated Environment able to handle multicast traffic, which is the major objective of this work. This document describes the implementation of the above mentioned environment, which provides many functions to use and manage multicast traffic, functions which existed only in a limited way and just in few tools, normally the comercial ones. This environment is useful to different kinds of users, so that it can be used by common users, who want to join multimedia Internet sessions, as well as more advenced users such engineers and network administrators who may need to monitor and handle multicast traffic

Projeto de Sistemas Integrados de Propósito Geral Baseados em Redes em Chip Expandindo as Funcionalidades dos Roteadores para Execução de Operações: A plataforma IPNoSys

It bet on the next generation of computers as architecture with multiple processors and/or multicore processors. In this sense there are challenges related to features interconnection, operating frequency, the area on chip, power dissipation, performance and programmability. The mechanism of interconnection and communication it was considered ideal for this type of architecture are the networks-on-chip, due its scalability, reusability and intrinsic parallelism. The networks-on-chip communication is accomplished by transmitting packets that carry data and instructions that represent requests and responses between the processing elements interconnected by the network. The transmission of packets is accomplished as in a pipeline between the routers in the network, from source to destination of the communication, even allowing simultaneous communications between pairs of different sources and destinations. From this fact, it is proposed to transform the entire infrastructure communication of network-on-chip, using the routing mechanisms, arbitration and storage, in a parallel processing system for high performance. In this proposal, the packages are formed by instructions and data that represent the applications, which are executed on routers as well as they are transmitted, using the pipeline and parallel communication transmissions. In contrast, traditional processors are not used, but only single cores that control the access to memory. An implementation of this idea is called IPNoSys (Integrated Processing NoC System), which has an own programming model and a routing algorithm that guarantees the execution of all instructions in the packets, preventing situations of deadlock, livelock and starvation. This architecture provides mechanisms for input and output, interruption and operating system support. As proof of concept was developed a programming environment and a simulator for this architecture in SystemC, which allows configuration of various parameters and to obtain several results to evaluate it

JFloat: uma biblioteca de ponto flutuante para a linguagem Java com suporte a arredondamento direcionado

This work presents JFLoat, a software implementation of IEEE-754 standard for binary floating point arithmetic. JFloat was built to provide some features not implemented in Java, specifically directed rounding support. That feature is important for Java-XSC, a project developed in this Department. Also, Java programs should have same portability when using floating point operations, mainly because IEEE-754 specifies that programs should have exactly same behavior on every configuration. However, it was noted that programs using Java native floating point types may be machine and operating system dependent. Also, JFloat is a possible solution to that problem

Abordagem dirigida a modelos para redes de sensores sem fio

Research on Wireless Sensor Networks (WSN) has evolved, with potential applications in several domains. However, the building of WSN applications is hampered by the need of programming in low-level abstractions provided by sensor OS and of specific knowledge about each application domain and each sensor platform. We propose a MDA approach do develop WSN applications. This approach allows domain experts to directly contribute in the developing of applications without needing low level knowledge on WSN platforms and, at the same time, it allows network experts to program WSN nodes to met application requirements without specific knowledge on the application domain. Our approach also promotes the reuse of the developed software artifacts, allowing an application model to be reused across different sensor platforms and a platform model to be reused for different applications

Extensões ao Projeto LVWNet: mobilidade, interação com equipamentos reais, comunicação direta, e registro dinâmico de nós

Due to the constantly increasing use of wireless networks in domestic, business and industrial environments, new challenges have emerged. The prototyping of new protocols in these environments is typically restricted to simulation environments, where there is the need of double implementation, one in the simulation environment where an initial proof of concept is performed and the other one in a real environment. Also, if real environments are used, it is not trivial to create a testbed for high density wireless networks given the need to use various real equipment as well as attenuators and power reducers to try to reduce the physical space required to create these laboratories. In this context, LVWNet (Linux Virtual Wireless Network) project was originally designed to create completely virtual testbeds for IEEE 802.11 networks on the Linux operating system. This paper aims to extend the current project LVWNet, adding to it the features like the ability to interact with real wireless hardware, provides a initial mobility ability using the positioning of the nodes in a space coordinates environment based on meters, with loss calculations due to attenuation in free space, enables some scalability increase by creating an own protocol that allows the communication between nodes without an intermediate host and dynamic registration of nodes, allowing new nodes to be inserted into in already in operation network

Sincronismo de dispositivos para o georreferenciamento de imagens digitais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)