Distributed real-time operating system (DRTOS) modeling in SpecC

System level design of an embedded computing system involves a multi-step process to refine the system from an abstract specification to an actual implementation by defining and modeling the system at various levels of abstraction. System level design supports evaluating and optimizing the system early in design exploration.;Embedded computing systems may consist of multiple processing elements, memories, I/O devices, sensors, and actors. The selection of processing elements includes instruction-set processors and custom hardware units, such as application specific integrated circuit (ASIC) and field programmable gate array (FPGA). Real-time operating systems (RTOS) have been used in embedded systems as an industry standard for years and can offer embedded systems the characteristics such as concurrency and time constraints. Some of the existing system level design languages, such as SpecC, provide the capability to model an embedded system including an RTOS for a single processor. However, there is a need to develop a distributed RTOS modeling mechanism as part of the system level design methodology due to the increasing number of processing elements in systems and to embedded platforms having multiple processors. A distributed RTOS (DRTOS) provides services such as multiprocessor tasks scheduling, interprocess communication, synchronization, and distributed mutual exclusion, etc.;In this thesis, we develop a DRTOS model as the extension of the existing SpecC single RTOS model to provide basic functionalities of a DRTOS implementation, and present the refinement methodology for using our DRTOS model during system level synthesis. The DRTOS model and refinement process are demonstrated in the SpecC SCE environment. The capabilities and limitations of the DRTOS modeling approach are presented

A Survey of Techniques For Improving Energy Efficiency in Embedded Computing Systems

Recent technological advances have greatly improved the performance and features of embedded systems. With the number of just mobile devices now reaching nearly equal to the population of earth, embedded systems have truly become ubiquitous. These trends, however, have also made the task of managing their power consumption extremely challenging. In recent years, several techniques have been proposed to address this issue. In this paper, we survey the techniques for managing power consumption of embedded systems. We discuss the need of power management and provide a classification of the techniques on several important parameters to highlight their similarities and differences. This paper is intended to help the researchers and application-developers in gaining insights into the working of power management techniques and designing even more efficient high-performance embedded systems of tomorrow

An Approach to Manage Reconfigurations and Reduce Area Cost in Hard Real-Time Reconfigurable Systems

This article presents a methodology to build real-time reconfigurable systems that ensure that all the temporal constraints of a set of applications are met, while optimizing the utilization of the available reconfigurable resources. Starting from a static platform that meets all the real-time deadlines, our approach takes advantage of run-time reconfiguration in order to reduce the area needed while guaranteeing that all the deadlines are still met. This goal is achieved by identifying which tasks must be always ready for execution in order to meet the deadlines, and by means of a methodology that also allows reducing the area requirements

Software development of reconfigurable real-time systems : from specification to implementation

This thesis deals with reconfigurable real-time systems solving real-time tasks scheduling problems in a mono-core and multi-core architectures. The main focus in this thesis is on providing guidelines, methods, and tools for the synthesis of feasible reconfigurable real-time systems in a mono-processor and multi-processor architectures. The development of these systems faces various challenges particularly in terms of stability, energy consumption, response and blocking time. To address this problem, we propose in this work a new strategy of i) placement and scheduling of tasks to execute real-time applications on mono-core and multi-core architectures, ii) optimization step based on Mixed integer linear programming (MILP), and iii) guidance tool that assists designers to implement a feasible multi-core reconfigurable real-time from specification level to implementation level. We apply and simulate the contribution to a case study, and compare the proposed results with related works in order to show the originality of this methodology.Echtzeitsysteme laufen unter harten Bedingungen an ihre Ausführungszeit. Die Einhaltung der Echtzeit-Bedingungen bestimmt die Zuverlässigkeit und Genauigkeit dieser Systeme. Neben den Echtzeit-Bedingungen müssen rekonfigurierbare Echtzeitsysteme zusätzliche Rekonfigurations-Bedingungen erfüllen. Diese Arbeit beschäftigt sich mit rekonfigurierbaren Echtzeitsystemen in Mono- und Multicore-Architekturen. An die Entwicklung dieser Systeme sind verschiedene Anforderungen gestellt. Insbesondere muss die Rekonfigurierbarkeit beachtet werden. Dabei sind aber Echtzeit-Bedingungen und Ressourcenbeschränkungen weiterhin zu beachten. Darüber hinaus werden die Kosten für die Entwicklung dieser Systeme insbesondere durch falsche Designentscheidungen in den frühen Phasen der Entwicklung stark beeinträchtigt. Das Hauptziel in dieser Arbeit liegt deshalb auf der Bereitstellung von Handlungsempfehlungen, Methoden und Werkzeugen für die zielgerichtete Entwicklung von realisierbaren rekonfigurierbaren Echtzeitsystemen in Mono- und Multicore-Architekturen. Um diese Herausforderungen zu adressieren wird eine neue Strategie vorgeschlagen, die 1) die Funktionsallokation, 2) die Platzierung und das Scheduling von Tasks, 3) einen Optimierungsschritt auf der Basis von Mixed Integer Linear Programming (MILP) und 4) eine entscheidungsunterstützende Lösung umfasst, die den Designern hilft, eine realisierbare rekonfigurierbare Echtzeitlösung von der Spezifikationsebene bis zur Implementierungsebene zu entwickeln. Die vorgeschlagene Methodik wird auf eine Fallstudie angewendet und mit verwandten Arbeiten vergliche

A Survey of Research into Mixed Criticality Systems

This survey covers research into mixed criticality systems that has been published since Vestal’s seminal paper in 2007, up until the end of 2016. The survey is organised along the lines of the major research areas within this topic. These include single processor analysis (including fixed priority and EDF scheduling, shared resources and static and synchronous scheduling), multiprocessor analysis, realistic models, and systems issues. The survey also explores the relationship between research into mixed criticality systems and other topics such as hard and soft time constraints, fault tolerant scheduling, hierarchical scheduling, cyber physical systems, probabilistic real-time systems, and industrial safety standards

Design and development of deadline based scheduling mechanisms for multiprocessor systems

Multiprocessor systems are nowadays de facto standard for both personal computers and server workstations. Benefits of multicore technology will be used in the next few years for embedded devices and cellular phones as well. Linux, as a General Purpose Operating System (GPOS), must support many different hardware platform, from workstations to mobile devices. Unfortu- nately, Linux has not been designed to be a Real-Time Operating System (RTOS). As a consequence, time-sensitive (e.g. audio/video players) or sim- ply real-time interactive applications, may suffer degradations in their QoS. In this thesis we extend the implementation of the “Earliest Deadline First” algorithm in the Linux kernel from single processor to multicore systems, allowing processes migration among the CPUs. We also discuss the design choices and present the experimental results that show the potential of our work

From Java to real-time Java : A model-driven methodology with automated toolchain

Real-time systems are receiving increasing attention with the emerging application scenarios that are safety-critical, complex in functionality, high on timing-related performance requirements, and cost-sensitive, such as autonomous vehicles. Development of real-time systems is error-prone and highly dependent on the sophisticated domain expertise, making it a costly process. There is a trend of the existing software without the real-time notion being re-developed to realise real-time features, e.g., in the big data technology. This paper utilises the principles of model-driven engineering (MDE) and proposes the first methodology that automatically converts standard time-sharing Java applications to real-time Java applications. It opens up a new research direction on development automation of real-time programming languages and inspires many research questions that can be jointly investigated by the embedded systems, programming languages as well as MDE communities

Real-Time Systems: An Introduction and the State-of-the-Art

This encyclopedia article gives an overview of the broad area of real-time systems. This task is daunting because real-time systems are everywhere, and yet no generally accepted definition differentiates real-time systems from non-real-time systems