Real Time System by Jane W. Liu (Pearson), the book builds on the student's background in Operating System, Embedded System. It covers techniques for scheduling, resource access control, and validation that are, or are likely to be, widely used in real time computing and communication systems.

Liu, RealTime Systems. Real-Time Systems. Liu, University of Ilinois at Urbana-Champaign. Hard Versus Soft Real-Time Systems.

Each algorithm, protocol, or mechanism is defined by pseudo code or simple rules that can serve as a starting point of implementation. With few exceptions, each scheduling algorithm is accompanied that your application will meet its real time requirement when scheduling according to the algorithm. Like the course, the book builds on the student's background in operating systems. It covers techniques for scheduling, resource access control, and validation that are, or are likely to be, widely used in real-time computing and communication systems. Each algorithm, protocol, or mechanism is defined by pseudocode or simple rules that can serve as a starting point of implementation. With few exceptions, each scheduling algorithm is accompanied by one or more validation techniques.

You can use the techniques to ascertain that your application will meet its real-time requirements when scheduled according to the algorithm. In addition to information on existing techniques, the book emphasizes basic principles of realtime systems.

The foundations of these techniques are presented as theorems and corollaries. (I would like to have avoided this style, but feared that they might be buried in the narratives and details if not thus highlighted. I tried to keep them and their proofs informal.) I cover many of the theorems and proofs in my course in order to give students insight into why and how well the techniques work, and teach them the skills they will need to extend the existing techniques and develop new ones. Comments on Contents. The focus of the book is real-time operating systems and networks.

It starts with a small part (Chapters 1, 2 and 3) on real-time applications and systems in general. It ends with a part (Chapters 11 and 12) on specific attributes and implementations of network protocols and operating systems. The large part (Chapters 4-10) in the middle covers uniprocessor scheduling, resource access control, and multiprocessor and distributed scheduling. Sections and subsections marked by * are included for the sake of completeness. You can skip over them without loss of continuity.

Chapters 1 and 2. Chapter 1 gives an overview of several sample real-time applica dons for which the techniques described in the book were developed.

I find most computer science and engineering students in my classes are unfamiliar with these applications. The chapter tries to explain for them the characteristics of workloads generated by the applications and the reasons for their timing requirements. Chapter 2 follows by giving the definitions of hard and soft real-time systems and the rationales for this classification. Chapter 3 describes a reference model of real-time systems. Subsequent chapters (e.g., 4-10) characterize the systems we study according to special variants of the model.

The reference model has a rich set of features. We can describe a wide spectrum of real-time applications and underlying platforms in a sufficiently faithful manner in terms of the model so that we can analyze, simulate, and even emulate the system based on the description; indeed, some scheduling and validation tools use this kind of description as input. However, many features of the model are not used in later chapters. Sections describing them are marked by *.

Chapters 6, 7, and 8 are devoted to algorithms for scheduling and resource access control on one processor (i.e., a CPU, or a network link, I/O bus, a disk, and so on). Most of these algorithms are priority-driven; all of them can be implement easily on modern real-time operating systems and communication networks. The chapters adopt increasingly more complex variants of the periodic-task model: Chapter 6 starts from workloads consisting solely of independent periodic tasks that do not require any resource other than a processor. Chapter 7 adds aperiodic and sporadic tasks, and Chapter 8 adds resource contentions.

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Together, Chapters 6-9 give a comprehensive treatment of the RMA approach, which in essence is synonymous to fixed-priority scheduling. Most algorithms based on this approach allow application components to be added and deleted at run-time and can handle nondeterministic resource demands. The timing behavior of applications scheduled according to the algorithms are nondeterministic. However, the adverse effects of scheduling anomalies are bounded when fluctuations in resource demands are bounded. For most real-time applications, such as those described in Chapter 1, the accompanied validation techniques make it possible for us to predict fairly accurately the worstcase real-time performance of applications thus scheduled. The chapters also describe ways to schedule applications with widely varying resource demands within the deadline-driven framework.