The application of distributed virtual machines for enterprise computer management: A two-tier network file system for image provisioning and management

In order to simplify computer management, several system administrators are adopting advanced techniques to manage software configuration of enterprise computer networks, but the tight coupling between hardware and software makes every PC an individual managed entity, lowering the scalability and increasing the costs to manage hundreds or thousands of PCs. Virtualization is an established technology, however its use is been more focused on server consolidation and virtual desktop infrastructure, not for managing distributed computers over a network. This paper discusses the feasibility of the Distributed Virtual Machine Environment, a new approach for enterprise computer management that combines virtualization and distributed system architecture as the basis of the management architecture. © 2008 IEEE.

Tolerância a falha em um ambiente de computação em nuvem open source

Pós-graduação em Ciência da Computação - IBILCE

A novel strategy for building interoperable MPI environment in heterogeneous high performance systems

Breakthrough advances in microprocessor technology and efficient power management have altered the course of development of processors with the emergence of multi-core processor technology, in order to bring higher level of processing. The utilization of many-core technology has boosted computing power provided by cluster of workstations or SMPs, providing large computational power at an affordable cost using solely commodity components. Different implementations of message-passing libraries and system softwares (including Operating Systems) are installed in such cluster and multi-cluster computing systems. In order to guarantee correct execution of message-passing parallel applications in a computing environment other than that originally the parallel application was developed, review of the application code is needed. In this paper, a hybrid communication interfacing strategy is proposed, to execute a parallel application in a group of computing nodes belonging to different clusters or multi-clusters (computing systems may be running different operating systems and MPI implementations), interconnected with public or private IP addresses, and responding interchangeably to user execution requests. Experimental results demonstrate the feasibility of this proposed strategy and its effectiveness, through the execution of benchmarking parallel applications.

Atendimento online em bibliotecas: a experiência da Universidade de São Paulo

Os serviços de informação aliados às tecnologias evoluíram em sua forma de atuação à medida que oferecem, em menor tempo possível, informação segura de alcance maior aos usuários das bibliotecas. São inúmeros os conceitos de Serviço de Referência Virtual (SRV) que compartilham a ideia de que o uso das tecnologias de informação facilitam a comunicação entre bibliotecários e usuários. As Bibliotecas do Sistema Integrado de Bibliotecas da Universidade de São Paulo (SIBi/USP), detectaram a relevância de modernizar o Serviço de Atendimento ao Usuário, utilizando novos meios de comunicação e melhorando a interação com os usuários por meio de recursos que são de domínio e uso cotidiano dos mesmos. A Biblioteca da Faculdade de Medicina Veterinária e Zootecnia (FMVZ) da Universidade de São Paulo (USP) implantou o serviço de Atendimento Online por chat, disponibilizando aos seus usuários um novo canal de comunicação que permite o esclarecimento de dúvidas e solicitações em tempo real com atendentes. A experiência foi extremamente positiva convergindo para a implantação do sistema em outras quatro bibliotecas da USP

Atendimento online em bibliotecas: a experiência da Universidade de São Paulo

Os serviços de informação aliados às tecnologias evoluíram em sua forma de atuação à medida que oferecem, em menor tempo possível, informação segura de alcance maior aos usuários das bibliotecas. São inúmeros os conceitos de Serviço de Referência Virtual (SRV) que compartilham a ideia de que o uso das tecnologias de informação facilitam a comunicação entre bibliotecários e usuários. As Bibliotecas do Sistema Integrado de Bibliotecas da Universidade de São Paulo (SIBi/USP), detectaram a relevância de modernizar o Serviço de Atendimento ao Usuário, utilizando novos meios de comunicação e melhorando a interação com os usuários por meio de recursos que são de domínio e uso cotidiano dos mesmos. A Biblioteca da Faculdade de Medicina Veterinária e Zootecnia (FMVZ) da Universidade de São Paulo (USP) implantou o serviço de Atendimento Online por chat, disponibilizando aos seus usuários um novo canal de comunicação que permite o esclarecimento de dúvidas e solicitações em tempo real com atendentes. A experiência foi extremamente positiva convergindo para a implantação do sistema em outras quatro bibliotecas da USP

Performance evaluation of a parallel algorithm for simultaneous untangling and smoothing of tetrahedral meshes

[EN]A new parallel algorithm for simultaneous untangling and smoothing of tetrahedral meshes is proposed in this paper. We provide a detailed analysis of its performance on shared-memory many-core computer architectures. This performance analysis includes the evaluation of execution time, parallel scalability, load balancing, and parallelism bottlenecks. Additionally, we compare the impact of three previously published graph coloring procedures on the performance of our parallel algorithm. We use six benchmark meshes with a wide range of sizes. Using these experimental data sets, we describe the behavior of the parallel algorithm for different data sizes. We demonstrate that this algorithm is highly scalable when it runs on two different high-performance many-core computers with up to 128 processors...

Applying partial virtualization on ELF binaries through dynamic loaders

The technology of partial virtualization is a revolutionary approach to the world of virtualization. It lies directly in-between full system virtual machines (like QEMU or XEN) and application-related virtual machines (like the JVM or the CLR). The ViewOS project is the flagship of such technique, developed by the Virtual Square laboratory, created to provide an abstract view of the underlying system resources on a per-process basis and work against the principle of the Global View Assumption. Virtual Square provides several different methods to achieve partial virtualization within the ViewOS system, both at user and kernel levels. Each of these approaches have their own advantages and shortcomings. This paper provides an analysis of the different virtualization methods and problems related to both the generic and partial virtualization worlds. This paper is the result of an in-depth study and research for a new technology to be employed to provide partial virtualization based on ELF dynamic binaries. It starts with a mild analysis of currently available virtualization alternatives and then goes on describing the ViewOS system, highlighting its current shortcomings. The vloader project is then proposed as a possible solution to some of these inconveniences with a working proof of concept and examples to outline the potential of such new virtualization technique. By injecting specific code and libraries in the middle of the binary loading mechanism provided by the ELF standard, the vloader project can promote a streamlined and simplified approach to trace system calls. With the advantages outlined in the following paper, this method presents better performance and portability compared to the currently available ViewOS implementations. Furthermore, some of itsdisadvantages are also discussed, along with their possible solutions.

OpenMP task scheduling strategies to mitigate hardware variability in tightly-coupled shared memory clusters

In questa tesi sono stati apportati due importanti contributi nel campo degli acceleratori embedded many-core. Abbiamo implementato un runtime OpenMP ottimizzato per la gestione del tasking model per sistemi a processori strettamente accoppiati in cluster e poi interconnessi attraverso una network on chip. Ci siamo focalizzati sulla loro scalabilità e sul supporto di task di granularità fine, come è tipico nelle applicazioni embedded. Il secondo contributo di questa tesi è stata proporre una estensione del runtime di OpenMP che cerca di prevedere la manifestazione di errori dati da fenomeni di variability tramite una schedulazione efficiente del carico di lavoro.

Flow-Centric, Back-In-Time Debugging

Conventional debugging tools present developers with means to explore the run-time context in which an error has occurred. In many cases this is enough to help the developer discover the faulty source code and correct it. However, rather often errors occur due to code that has executed in the past, leaving certain objects in an inconsistent state. The actual run-time error only occurs when these inconsistent objects are used later in the program. So-called back-in-time debuggers help developers step back through earlier states of the program and explore execution contexts not available to conventional debuggers. Nevertheless, even back-in-time debuggers do not help answer the question, ``Where did this object come from?'' The Object-Flow Virtual Machine, which we have proposed in previous work, tracks the flow of objects to answer precisely such questions, but this VM does not provide dedicated debugging support to explore faulty programs. In this paper we present a novel debugger, called Compass, to navigate between conventional run-time stack-oriented control flow views and object flows. Compass enables a developer to effectively navigate from an object contributing to an error back-in-time through all the code that has touched the object. We present the design and implementation of Compass, and we demonstrate how flow-centric, back-in-time debugging can be used to effectively locate the source of hard-to-find bugs.

Systematic reviews published in higher impact clinical journals were of higher quality.

OBJECTIVES To compare the methodological quality of systematic reviews (SRs) published in high- and low-impact factor (IF) Core Clinical Journals. In addition, we aimed to record the implementation of aspects of reporting, including Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) flow diagram, reasons for study exclusion, and use of recommendations for interventions such as Grading of Recommendations Assessment, Development and Evaluation (GRADE). STUDY DESIGN AND SETTING We searched PubMed for systematic reviews published in Core Clinical Journals between July 1 and December 31, 2012. We evaluated the methodological quality using the Assessment of Multiple Systematic Reviews (AMSTAR) tool. RESULTS Over the 6-month period, 327 interventional systematic reviews were identified with a mean AMSTAR score of 63.3% (standard deviation, 17.1%), when converted to a percentage scale. We identified deficiencies in relation to a number of quality criteria including delineation of excluded studies and assessment of publication bias. We found that SRs published in higher impact journals were undertaken more rigorously with higher percentage AMSTAR scores (per IF unit: β = 0.68%; 95% confidence interval: 0.32, 1.04; P < 0.001), a discrepancy likely to be particularly relevant when differences in IF are large. CONCLUSION Methodological quality of SRs appears to be better in higher impact journals. The overall quality of SRs published in many Core Clinical Journals remains suboptimal.

Using Virtual Reality in the teaching of manufacturing processes with material removal in CNC Machine-Tools

This paper presents a methodology for the incorporation of a Virtual Reality development applied to the teaching of manufacturing processes, namely the group of machining processes in numerical control of machine tools. The paper shows how it is possible to supplement the teaching practice through virtual machine-tools whose operation is similar to the 'real' machines while eliminating the risks of use for both users and the machines.

On real-time partitioned multicore systems

Partitioning is a common approach to developing mixed-criticality systems, where partitions are isolated from each other both in the temporal and the spatial domain in order to prevent low-criticality subsystems from compromising other subsystems with high level of criticality in case of misbehaviour. The advent of many-core processors, on the other hand, opens the way to highly parallel systems in which all partitions can be allocated to dedicated processor cores. This trend will simplify processor scheduling, although other issues such as mutual interference in the temporal domain may arise as a consequence of memory and device sharing. The paper describes an architecture for multi-core partitioned systems including critical subsystems built with the Ada Ravenscar profile. Some implementation issues are discussed, and experience on implementing the ORK kernel on the XtratuM partitioning hypervisor is presented.

Massively parallelizable list-mode reconstruction using a Monte Carlo-based elliptical Gaussian model

Purpose: A fully three-dimensional (3D) massively parallelizable list-mode ordered-subsets expectation-maximization (LM-OSEM) reconstruction algorithm has been developed for high-resolution PET cameras. System response probabilities are calculated online from a set of parameters derived from Monte Carlo simulations. The shape of a system response for a given line of response (LOR) has been shown to be asymmetrical around the LOR. This work has been focused on the development of efficient region-search techniques to sample the system response probabilities, which are suitable for asymmetric kernel models, including elliptical Gaussian models that allow for high accuracy and high parallelization efficiency. The novel region-search scheme using variable kernel models is applied in the proposed PET reconstruction algorithm. Methods: A novel region-search technique has been used to sample the probability density function in correspondence with a small dynamic subset of the field of view that constitutes the region of response (ROR). The ROR is identified around the LOR by searching for any voxel within a dynamically calculated contour. The contour condition is currently defined as a fixed threshold over the posterior probability, and arbitrary kernel models can be applied using a numerical approach. The processing of the LORs is distributed in batches among the available computing devices, then, individual LORs are processed within different processing units. In this way, both multicore and multiple many-core processing units can be efficiently exploited. Tests have been conducted with probability models that take into account the noncolinearity, positron range, and crystal penetration effects, that produced tubes of response with varying elliptical sections whose axes were a function of the crystal's thickness and angle of incidence of the given LOR. The algorithm treats the probability model as a 3D scalar field defined within a reference system aligned with the ideal LOR. Results: This new technique provides superior image quality in terms of signal-to-noise ratio as compared with the histogram-mode method based on precomputed system matrices available for a commercial small animal scanner. Reconstruction times can be kept low with the use of multicore, many-core architectures, including multiple graphic processing units. Conclusions: A highly parallelizable LM reconstruction method has been proposed based on Monte Carlo simulations and new parallelization techniques aimed at improving the reconstruction speed and the image signal-to-noise of a given OSEM algorithm. The method has been validated using simulated and real phantoms. A special advantage of the new method is the possibility of defining dynamically the cut-off threshold over the calculated probabilities thus allowing for a direct control on the trade-off between speed and quality during the reconstruction.

Lecciones prácticas de desarrollo de aplicaciones móviles en Android

Los avances que se han producido en los últimos años en cuanto a potencia y capacidades de los teléfonos móviles que usamos de manera cotidiana, traen de la mano un auge en la demanda de aplicaciones de todo ámbito: desde aplicaciones generales de consumo, pasando por juegos, hasta aplicaciones que ofrecen soluciones internas a empresas. Existen diferentes sistemas operativos para teléfonos móviles como se explicará más adelante en el capítulo introductorio. En dicho capítulo se da la justificación de por qué en el presente Proyecto Fin de Carrera se centra en el estudio del sistema operativo Android. Primeramente se dará una visión global del estado del arte en cuanto al mundo de aplicaciones móviles se refiere. Se explicarán los pros y contras de cada sistema operativo, detallando el lenguaje de programación utilizado en cada uno de ellos y sus principales características. Después, en el capítulo tres se estudiará con más profundidad el sistema operativo Android, desde su historia y orígenes, hasta los componentes básicos para la creación de una aplicación, pasando por la arquitectura interna del sistema o su máquina virtual. Con esto se pretende que el lector tenga un contexto que le permita comprender los siguientes capítulos, que es donde está el núcleo de este Proyecto Fin de Carrera. El cuarto capítulo trata de una serie de prácticas incrementales, que cubren una gran parte de las posibilidades que ofrece el sistema operativo Android para el desarrollo de aplicaciones. Se ha pretendido que la dificultad vaya de menos a más y que las prácticas se vayan apoyando en las anteriores, para tener al final una única solución que englobe todas las lecciones. El último capítulo quiere englobar el uso de todas las lecciones aprendidas en las lecciones anteriores para crear una aplicación que bien podría ser una aplicación real para un cliente. Se trata de una aplicación que muestra en tiempo real información sobre las cámaras de tráfico de la ciudad de Madrid. ABSTRACT. The improvements that have occurred in recent years in terms of power and capabilities of mobile phones that we use on a daily basis, bring an increment in demand for all kind of applications, from general consumer applications, games or even internal applications that offer solutions to companies. There are different operating systems for mobile phones as will be explained later in the introductory chapter. In that chapter the answer for why this Thesis focuses on the study of the Android operating system is given as well. First an overview of the state of the art about the world of mobile applications will be referred. The pros and cons of each operating system will be explained, detailing the programming language used in each of them and their main characteristics. Then in chapter three will be discussed in more depth the Android operating system, from its history and beginnings to the main components for the creation of an application, to the internal architecture of the system or virtual machine. The goal of chapter three is to give the readers a context that allows them to understand the following chapters, where the core of this Thesis is. The fourth chapter contains a series of incremental practices covering a large part of the potential of the Android operating system for application development. Those practices grow in difficulty and are supported by the previous in order to have at the end a single solution that fits all lessons. The last chapter wants to embrace the use of all the lessons learned in previous lessons to create an application that could well be an actual application for a client. It is an application that displays real-time information off traffic cameras of the city of Madrid.

Virtualización de laboratorios

Para empezar, se ha hecho un análisis de las diferentes posibilidades que se podían implementar para poder conseguir el objetivo del trabajo. El resultado final debe ser, disponer de máquinas para que el sistema operativo fuese independiente del hardware que se tiene instalado en él . Para ello, se decide montar un sistema operativo de base en todos los equipos del laboratorio, que tenga las necesidades mínimas que se necesitan, las cuales son una interfaz gráfica y conexión de red. Hay que intentar reducir el consumo de recursos al máximo con este sistema operativo mínimo para que el rendimiento de las máquinas sea lo más fluido posible para los usuarios. El sistema elegido fue Linux con su distribución Ubuntu [ubu, http] con los módulos mínimos que permita funcionar el software necesario. Una vez se instala el sistema operativo anfitrión, se instala el escritorio Xfce [ubu2, http], que es el más ligero de Ubuntu, pero que proporciona buen rendimiento. Después, se procedió a instalar un software de virtualización en cada equipo. En este caso se decidió, por las buenas prestaciones que ofrecía, que fuera VirtualBox [vir2,http] de Oracle. Sobre éste software se crean tantas máquinas virtuales (con sistema operativo Windows) como asignaturas diferentes se cursan en el laboratorio donde se trabaje. Con esto, se consigue que al arrancar el programa los alumnos pudieran escoger qué máquina arrancar y lo que es más importante, se permite realizar cualquier cambio en el hardware (exceptuando el disco duro porque borraría todo lo que se tuviera guardado). Además de no tener que volver a reinstalar el sistema operativo nuevamente, se consigue la abstracción del software y hardware. También se decide que, para tener un respaldo de las máquinas virtuales que se tengan creadas en VirtualBox, se utiliza un servidor NAS. Uno de los motivos de utilizar dicho servidor fue por aprovechar una infraestructura ya creada. Un servidor NAS da la posibilidad de recuperar cualquier archivo (máquina virtual) cuando haga falta porque haya alguna máquina virtual corrupta en algún equipo, o en varios. Este tipo de servidor tiene la gran ventaja de ser multicast, es decir, permite solicitudes simultáneas. ABSTRACT For starters, there has been an analysis of the different possibilities that could be implemented to achieve the objective of the work. This objective was to have machines for the operating system to be independent of the hardware we have installed on it. Therefore, we decided to create an operating system based on all computers in the laboratory, taking the minimum needs we need. This is a graphical interface and network connection. We must try to reduce the consumption of resources to the maximum for the performance of the machines is as fluid as possible for users. The system was chosen with its Ubuntu Linux distribution with minimum modules that allow us to run software that is necessary for us. Once the base is installed, we install the Xfce desktop, which is the lightest of Ubuntu, but which provided good performance. Then we proceeded to install a virtualization software on each computer. In this case we decided, for good performance that gave us, it was Oracle VirtualBox. About this software create many virtual machines (Windows operating system) as different subjects are studied in the laboratory where we are. With that, we got it at program startup students could choose which machine start and what is more important, allowed us to make any changes to the hardware (except the hard drive because it would erase all we have). Besides not having to reinstall the operating system again, we get the software and hardware abstraction. We also decided that in order to have a backup of our virtual machines that we created in VirtualBox, we use a NAS server. One reason to use that server was to leverage their existing network infrastructure. A NAS server gives us the ability to retrieve any file (image) when we do need because there is some corrupt virtual machine in a team, or several. This is possible because this type of server allows multicast connection.