tailieunhanh - Bài giảng Hệ điều hành nâng cao - Chapter 19: Real - Time Systems

Bài giảng Hệ điều hành nâng cao - Chapter 19: Real - Time Systems trình bày về đặc điểm hệ thống, các chức năng của hệ thống, thời gian thực của hệ điều hành, lập kế hoạch CPU,.Mời bạn đọc cùng tham khảo bài giảng đề tìm hiểu rõ hơn về Hệ điều hành nâng cao. | Chapter 19: Real-Time Systems 1 Chapter 19: Real-Time Systems System Characteristics Features of Real-Time Systems Implementing Real-Time Operating Systems Real-Time CPU Scheduling An Example: VxWorks 2 Objectives To explain the timing requirements of real-time systems To distinguish between hard and soft real-time systems To discuss the defining characteristics of real-time systems To describe scheduling algorithms for hard real-time systems 3 Overview of Real-Time Systems A real-time system requires that results be produced within a specified deadline period. An embedded system is a computing device that is part of a larger system (., automobile, airliner). A safety-critical system is a real-time system with catastrophic results in case of failure. A hard real-time system guarantees that real-time tasks be completed within their required deadlines. A soft real-time system provides priority of real-time tasks over non real-time tasks. 4 System Characteristics Single purpose Small size Inexpensively mass-produced Specific timing requirements 5 System-on-a-Chip Many real-time systems are designed using system-on-a-chip (SOC) strategy SOC allows the CPU, memory, memory-management unit, and attached peripheral ports (., USB) to be contained in a single integrated circuit 6 Bus-Oriented System 7 Features of Real-Time Kernels Most real-time systems do not provide the features found in a standard desktop system Reasons include Real-time systems are typically single-purpose Real-time systems often do not require interfacing with a user Features found in a desktop PC require more substantial hardware that what is typically available in a real-time system 8 Virtual Memory in Real-Time Systems Address translation may occur via: 1. Real-addressing mode where programs generate actual addresses 2. Relocation register mode 3. Implementing full virtual memory 9 Address Translation 10 Implementing Real-Time Systems In general, real-time operating systems must . | Chapter 19: Real-Time Systems 1 Chapter 19: Real-Time Systems System Characteristics Features of Real-Time Systems Implementing Real-Time Operating Systems Real-Time CPU Scheduling An Example: VxWorks 2 Objectives To explain the timing requirements of real-time systems To distinguish between hard and soft real-time systems To discuss the defining characteristics of real-time systems To describe scheduling algorithms for hard real-time systems 3 Overview of Real-Time Systems A real-time system requires that results be produced within a specified deadline period. An embedded system is a computing device that is part of a larger system (., automobile, airliner). A safety-critical system is a real-time system with catastrophic results in case of failure. A hard real-time system guarantees that real-time tasks be completed within their required deadlines. A soft real-time system provides priority of real-time tasks over non real-time tasks. 4 System Characteristics Single .