Foundations Of Real Time Computing Scheduling And Resource Management

This volume contains a selection of papers that focus on the state-of the-art in real-time scheduling and resource management. Preliminary versions of these papers were presented at a workshop on the foundations of real-time computing sponsored by the Office of Naval Research in October, 1990 in Washington, D.C. A companion volume by the title Foundations of Real-Time Computing: Fonnal Specifications and Methods complements this book by addressing many of the most advanced approaches currently being investigated in the arena of formal specification and verification of real-time systems. Together, these two texts provide a comprehensive snapshot of current insights into the process of designing and building real-time computing systems on a scientific basis. Many of the papers in this book take care to define the notion of real-time system precisely, because it is often easy to misunderstand what is meant by that term. Different communities of researchers variously use the term real-time to refer to either very fast computing, or immediate on-line data acquisition, or deadline-driven computing. This text is concerned with the very difficult problems of scheduling tasks and resource management in computer systems whose performance is inextricably fused with the achievement of deadlines. Such systems have been enabled for a rapidly increasing set of diverse end-uses by the unremitting advances in computing power per constant-dollar cost and per constant-unit-volume of space. End-use applications of deadline-driven real-time computers span a spectrum that includes transportation systems, robotics and manufacturing, aerospace and defense, industrial process control, and telecommunications.

This volume contains a selection of papers that focus on the state-of the-art in formal specification and verification of real-time computing systems. Preliminary versions of these papers were presented at a workshop on the foundations of real-time computing sponsored by the Office of Naval Research in October, 1990 in Washington, D. C. A companion volume by the title Foundations of Real-Time Computing: Scheduling and Resource Management complements this hook by addressing many of the recently devised techniques and approaches for scheduling tasks and managing resources in real-time systems. Together, these two texts provide a comprehensive snapshot of current insights into the process of designing and building real time computing systems on a scientific basis. The notion of real-time system has alternative interpretations, not all of which are intended usages in this collection of papers. Different communities of researchers variously use the term real-time to refer to either very fast computing, or immediate on-line data acquisition, or deadline-driven computing. This text is concerned with the formal specification and verification of computer software and systems whose correct performance is dependent on carefully orchestrated interactions with time, e. g. , meeting deadlines and synchronizing with clocks. Such systems have been enabled for a rapidly increasing set of diverse end-uses by the unremitting advances in computing power per constant-dollar cost and per constant-unit-volume of space. End use applications of real-time computers span a spectrum that includes transportation systems, robotics and manufacturing, aerospace and defense, industrial process control, and telecommunications.

This classroom-tested textbook describes the design and implementation of software for distributed real-time systems, using a bottom-up approach. The text addresses common challenges faced in software projects involving real-time systems, and presents a novel method for simply and effectively performing all of the software engineering steps. Each chapter opens with a discussion of the core concepts, together with a review of the relevant methods and available software. This is then followed with a description of the implementation of the concepts in a sample kernel, complete with executable code. Topics and features: introduces the fundamentals of real-time systems, including real-time architecture and distributed real-time systems; presents a focus on the real-time operating system, covering the concepts of task, memory, and input/output management; provides a detailed step-by-step construction of a real-time operating system kernel, which is then used to test various higher level implementations; describes periodic and aperiodic scheduling, resource management, and distributed scheduling; reviews the process of application design from high-level design methods to low-level details of design and implementation; surveys real-time programming languages and fault tolerance techniques; includes end-of-chapter review questions, extensive C code, numerous examples, and a case study implementing the methods in real-world applications; supplies additional material at an associated website. Requiring only a basic background in computer architecture and operating systems, this practically-oriented work is an invaluable study aid for senior undergraduate and graduate-level students of electrical and computer engineering, and computer science. The text will also serve as a useful general reference for researchers interested in real-time systems.

This book introduces the concepts and state-of-the-art research developments of resource management in real-time systems and networks. Real-time systems and networks are of increasing importance in many applications, including automated factories, telecommunication systems, defense systems, and space systems. This book introduces the concepts and state-of-the-art research developments of resource management in real-time systems and networks. Unlike other texts in the field, it covers the entire spectrum of issues in resource management, including task scheduling in uniprocessor real-time systems; task scheduling, fault-tolerant task scheduling, and resource reclaiming in multiprocessor real-time systems; conventional task scheduling and object-based task scheduling in distributed real-time systems; message scheduling; QoS routing; dependable communication; multicast communication; and medium access protocols in real-time networks. It provides algorithmic treatments for all of the issues addressed, highlighting the intuition behind each algorithm and giving examples. The book also includes two chapters of case studies.

Real-time systems are used in a wide range of applications,including control, sensing, multimedia, etc. Scheduling is acentral problem for these computing/communication systems sinceresponsible of software execution in a timely manner. This bookprovides state of knowledge in this domain with special emphasis onthe key results obtained within the last decade. This book addresses foundations as well as the latest advancesand findings in Real-Time Scheduling, giving all references toimportant papers. But nevertheless the chapters will be short andnot overloaded with confusing details. Coverage includes schedulingapproaches for mono-core as well as multi-core platforms, dependenttasks, networks, and notably very tremendous recent advances inscheduling of energy constrained embedded systems. Othersophisticated issues such as feedback control scheduling and timinganalysis of critical applications are also addressed. This volume can serve as a textbook for courses on the topic inbachelor and in more advanced master programs. It also provides areference for computer scientists and engineers involved in thedesign or the development of Cyber-Physical Systems which requireup-to-date real-time scheduling solutions.

Many real-time systems rely on static scheduling algorithms. This includes cyclic scheduling, rate monotonic scheduling and fixed schedules created by off-line scheduling techniques such as dynamic programming, heuristic search, and simulated annealing. However, for many real-time systems, static scheduling algorithms are quite restrictive and inflexible. For example, highly automated agile manufacturing, command, control and communications, and distributed real-time multimedia applications all operate over long lifetimes and in highly non-deterministic environments. Dynamic real-time scheduling algorithms are more appropriate for these systems and are used in such systems. Many of these algorithms are based on earliest deadline first (EDF) policies. There exists a wealth of literature on EDF-based scheduling with many extensions to deal with sophisticated issues such as precedence constraints, resource requirements, system overload, multi-processors, and distributed systems. Deadline Scheduling for Real-Time Systems: EDF and Related Algorithms aims at collecting a significant body of knowledge on EDF scheduling for real-time systems, but it does not try to be all-inclusive (the literature is too extensive). The book primarily presents the algorithms and associated analysis, but guidelines, rules, and implementation considerations are also discussed, especially for the more complicated situations where mathematical analysis is difficult. In general, it is very difficult to codify and taxonomize scheduling knowledge because there are many performance metrics, task characteristics, and system configurations. Also, adding to the complexity is the fact that a variety of algorithms have been designed for different combinations of these considerations. In spite of the recent advances there are still gaps in the solution space and there is a need to integrate the available solutions. For example, a list of issues to consider includes: preemptive versus non-preemptive tasks, uni-processors versus multi-processors, using EDF at dispatch time versus EDF-based planning, precedence constraints among tasks, resource constraints, periodic versus aperiodic versus sporadic tasks, scheduling during overload, fault tolerance requirements, and providing guarantees and levels of guarantees (meeting quality of service requirements). Deadline Scheduling for Real-Time Systems: EDF and Related Algorithms should be of interest to researchers, real-time system designers, and instructors and students, either as a focussed course on deadline-based scheduling for real-time systems, or, more likely, as part of a more general course on real-time computing. The book serves as an invaluable reference in this fast-moving field.

Real-time computing plays a crucial role in our society since an increasing num ber of complex systems rely, in part or completely, on processor control. Ex amples of applications that require real-time computing include nuclear power plants, railway switching systems, automotive electronics, air traffic control, telecommunications, robotics, and military systems. In spite of this large application domain, most of the current real-time systems are still designed and implemented using low-level programming and empirical techniques, without the support of a scientific methodology. This approach results in a lack of reliability, which in critical applications may cause serious environmental damage or even loss of life. This book is a basic treatise on real-time computing, with particular emphasis on predictable scheduling algorithms. The main objectives of the book are to introduce the basic concepts of real-time computing, illustrate the most sig nificant results in the field, and provide the basic methodologies for designing predictable computing systems useful in supporting critical control applica tions. The book is written for instructional use and is organized to enable readers without a strong knowledge of the subject matter to quickly grasp the material. Technical concepts are clearly defined at the beginning of each chapter, and algorithm descriptions are reinforced through concrete examples, illustrations, and tables.

* Real-time systems are used in a wide range of applications, including command and control systems, flight control, telecommunication systems, and online purchase payment * Provides an accessible yet comprehensive treatment * of real-time computing and communications systems * Outlines the basics of real-time scheduling and scheduling policies designed for real-time applications * Each chapter contains examples and case studies along with test exercises and solutions