Aplicabilidad de sistemas de tiempo real con requerimientos heterogéneos

El presente proyecto de investigación busca mejorar las técnicas de planificación de tareas heterogéneas en un Sistema de Tiempo Real. La planificación de las mismas adquiere cada vez una mayor importancia dentro de las diversas sub-disciplinas que poseen los Sistemas de Tiempo Real y los Sistemas de Propósito Dedicado (Embedded Systems). El desarrollo experimental se centra en la implementación y evaluación de técnicas y métodos sobre un simulador, en un ambiente simulado y en un ambiente real como lo es un Sistema Operativo. Algunos de estos métodos son desarrollados o perfeccionados por las personas pertenecientes al grupo. El proyecto, además de las metas de desarrollo, persigue objetivos académicos de formación de recursos humanos y de vinculación con otras universidades y con el medio productivo. Sus integrantes son alumnos (de grado y de posgrado) y docentes de la carrera de Licenciatura en Informática de la Facultad de Ingeniería de la Universidad Nacional de la Patagonia San Juan Bosco. Colabora como asesor un investigador de la Universidad Nacional del Sur.Eje: Procesamiento de señales y sistemas en tiempo realRed de Universidades con Carreras en Informática (RedUNCI

Using speed diagrams for symbolic quality management

We present a quality management method for multimedia applications. The method takes as input an application software composed of actions. The execution times of actions are unknown increasing functions of quality level parameters. The method allows the construction of a Quality Manager which computes adequate action quality levels so as to meet QoS requirements for a given platform. These include deadlines for the actions as well as quality maximization and smoothness. We extend and improve results of a previous paper by focusing on the reduction of overhead due to quality management. We propose a symbolic quality management method using speed diagrams, a representation of the system's dynamics. Instead of numerically computing a quality level for each action, the Quality Manager changes action quality levels based on the knowledge of constraints characterizing control relaxation regions. These are sets of states in which quality management for a given number of steps can be relaxed without degrading quality. We provide experimental results for quality management of an MPEG encoder, in particular performance benchmarks for both numeric and symbolic quality management. © 2007 IEEE

Implementación de Slack Stealing y una tarea planificadora en nxtOSEK sobre Lego Mindstorms NXT 2.0

Este trabajo presenta una implementación, utilizando el Sistema Operativo de Tiempo Real nxtOSEK y el kit de robótica educativa Lego Mindstorms NXT 2.0, en configuración segway, de un método de Slack Stealing para la administración del tiempo ocioso en un Sistema de Tiempo Real, junto con una Tarea Planificadora que aprovecha el mismo para la ejecución concurrente de tareas periódicas y esporádicas, sin que las primeras pierdan sus vencimientos. Mediante este desarrollo, se pueden ejecutar tareas no críticas de manera concurrente, sin afectar las tareas críticas que mantienen el segway en equilibrio.Sociedad Argentina de Informática e Investigación Operativ

Implementación de Slack Stealing y una tarea planificadora en nxtOSEK sobre Lego Mindstorms NXT 2.0

Este trabajo presenta una implementación, utilizando el Sistema Operativo de Tiempo Real nxtOSEK y el kit de robótica educativa Lego Mindstorms NXT 2.0, en configuración segway, de un método de Slack Stealing para la administración del tiempo ocioso en un Sistema de Tiempo Real, junto con una Tarea Planificadora que aprovecha el mismo para la ejecución concurrente de tareas periódicas y esporádicas, sin que las primeras pierdan sus vencimientos. Mediante este desarrollo, se pueden ejecutar tareas no críticas de manera concurrente, sin afectar las tareas críticas que mantienen el segway en equilibrio.Sociedad Argentina de Informática e Investigación Operativ

Implementación de Slack Stealing y una tarea planificadora en nxtOSEK sobre Lego Mindstorms NXT 2.0

Este trabajo presenta una implementación, utilizando el Sistema Operativo de Tiempo Real nxtOSEK y el kit de robótica educativa Lego Mindstorms NXT 2.0, en configuración segway, de un método de Slack Stealing para la administración del tiempo ocioso en un Sistema de Tiempo Real, junto con una Tarea Planificadora que aprovecha el mismo para la ejecución concurrente de tareas periódicas y esporádicas, sin que las primeras pierdan sus vencimientos. Mediante este desarrollo, se pueden ejecutar tareas no críticas de manera concurrente, sin afectar las tareas críticas que mantienen el segway en equilibrio.Sociedad Argentina de Informática e Investigación Operativ

Customizing Component Middleware for Distributed Real-Time Systems with Aperiodic and Periodic Tasks

Many distributed real-time applications must handle mixed aperiodic and periodic tasks with diverse requirements. However, existing middleware lacks flexible configuration mechanisms needed to manage end-to-end timing easily for a wide range of different applications with both aperiodic and periodic tasks. The primary contribution of this work is the design, implementation and performance evaluation of the first configurable component middleware services for admission control and load balancing of aperiodic and periodic tasks in distributed real-time systems. Empirical results demonstrate the need for, and the effectiveness of, our configurable component middleware approach in supporting different applications with aperiodic and periodic tasks

Roadmap Analysis of Protein-Protein Interactions. Master\u27s Thesis, August 2007

The ability to effectively model the interaction between proteins is an important and open problem. In molecular biology it is well accepted that from sequence arises form and from form arises function but relating structure to function remains a challenge. The function of a given protein is defined by its interactions. Likewise a malfunction or a change in protein-protein interactions is a hallmark of many diseases. Many researchers are studying the mechanisms of protein-protein interactions and one of the overarching goals of the community is to predict whether two proteins will bind, and if so what the final conformation will be. Attention is seldom paid to the association pathways that allow two proteins to bind. Evidence has shown that the information in the association pathways can play a vital role in understanding the interaction itself. This thesis presents a novel and scalable approach to computing association pathways between two proteins using the Probabilistic Roadmap (PRM) framework. We will discuss the challenges in extending PRM to the domain of protein-protein interactions such as performing structural mappings in a reduced space of flexibility, and sampling high dimensional conformation spaces. We will present analysis of individual association pathways as well as methods for estimating collective properties of the energy landscape. Our results indicate that these methods can discriminate between true and false protein binding interfaces. Finally, we will present condensing methods such as pathway clustering and visualization using dimensionality reduction that can be be applied to create compact representations of the interaction space

QoS control for optimality and safety

We propose a method for fine grain QoS control of real-time applications. The method allows adapting the overall system behavior by adequately setting the quality level parameters of its actions. The objective of the control policy is to meet QoS requirements including three types of properties: 1) safety that is, no deadline is missed; 2) optimality that is, maximization of the available time budget; 3) smoothness of quality levels. The method takes as input a model of the application software, QoS requirements and platform-dependent timing information, and produces a controlled application software meeting the QoS requirements on the target platform. This paper provides a complete formalization of the quality control problem. It proposes a new control management policy ensuring safety, near-optimality and smoothness. It also describes a prototype tool implementing the quality control algorithm and experimental results about its application to a video encoder. Copyright 2005 ACM

Analyzing the effect of gain time on soft task scheduling policies in real-time systems

In hard real-time systems, gain time is defined as the difference between the Worst Case Execution Time (WCET) of a hard task and its actual processor consumption at runtime. This paper presents the results of an empirical study about how the presence of a significant amount of gain time in a hard real-time system questions the advantages of using the most representative scheduling algorithms or policies for aperiodic or soft tasks in fixed-priority preemptive systems. The work presented here refines and complements many other studies in this research area in which such policies have been introduced and compared. This work has been performed by using the authors' testing framework for soft scheduling policies, which produces actual, synthetic, randomly generated applications, executes them in an instrumented Real-Time Operating System (RTOS), and finally processes this information to obtain several statistical outcomes. The results show that, in general, the presence of a significant amount of gain time reduces the performance benefit of the scheduling policies under study when compared to serving the soft tasks in background, which is considered the theoretical worst case. In some cases, this performance benefit is so small that the use of a specific scheduling policy for soft tasks is questionable. © 2012 IEEE.This work is partially funded by research projects PROMETEO/2008/051, CSD2007-022, and TIN2008-04446.Búrdalo Rapa, LA.; Terrasa Barrena, AM.; Espinosa Minguet, AR.; García Fornes, AM. (2012). Analyzing the effect of gain time on soft task scheduling policies in real-time systems. IEEE Transactions on Software Engineering. 38(6):1305-1318. https://doi.org/10.1109/TSE.2011.95S1305131838