Real-Time UNIX® Systems

1 Introduction to Real-Time Computing.- 1.1 Definition and Classification of Real-Time Computer Systems.- 1.2 Computer Requirements for Real-Time Applications.- 1.3 Systems Issues.- 1.4 Real-Time Measures.- 1.4.1 Rhealstone Metric.- 1.4.2 Process Dispatch Latency Time.- 1.4.3 Tri-Dimensional Measure.- 1.4.4 The Real/Stone Benchmark.- 1.5 Model of an Open Real-Time System.- 2 Real-Time Operating Systems.- 2.1 Requirements for Real-Time Operating Systems.- 2.2 Real-Time UNIX Operating Systems.- 2.2.1 The UNIX System and Real-Time.- 2.2.2 Real-Time UNIX Standards.- 2.2.3 Real-Time UNIX Implementations.- 3 Concept of a Fully Preemptive UNIX Operating System.- 3.1 System Concept.- 3.2 Process Subsystem.- 3.2.1 Process Concept.- 3.2.2 Process Creation and Termination.- 3.2.3 Forking Child Processes.- 3.2.4 Waiting for a Child Process to Terminate.- 3.2.5 Process States.- 3.3 Memory Management.- 3.3.1 Data Structures.- 3.3.2 Paging.- 3.3.3 Allocating Memory.- 3.3.4 Locking Pages in Memory.- 3.4 Process Scheduling.- 3.4.1 Data Structure Integrity.- 3.4.2 Timers.- 3.5 Interprocess Communication.- 3.5.1 Signal Mechanism.- 3.5.2 Common Event Notification.- 3.5.3 Shared Memory.- 3.5.4 User-Level Semaphores.- 3.6 File Subsystem.- 3.6.1 File Types.- 3.6.2 File Listings.- 3.6.3 File Permissions.- 3.6.4 User View of a File System.- 3.6.5 Accessing Files in Programs.- 3.6.6 File System Structure.- 3.6.7 Accessing Data Storage Blocks.- 3.6.8 Accessing Free Inodes and Data Blocks.- 3.6.9 File System Access Tables.- 3.6.10 Using the File Access Tables.- 3.7 I/O Subsystem.- 3.7.1 Device I/O.- 3.7.2 I/O Transfer Methods.- 3.7.3 Initiating I/O Operations.- 3.7.4 Device Interrupts.- 3.7.5 Drivers for Real-Time Applications.- 4 Designing Real-Time Applications.- 4.1 Programming Guidelines.- 4.1.1 Real-Time Program Structure.- 4.1.2 Development Procedure.- 4.1.3 Using System Calls.- 4.1.4 Performance Hints.- 4.2 Scheduling Processes.- 4.2.1 Selecting Process Priorities.- 4.2.2 Setting Real-Time Privileges.- 4.2.3 Changing Process Priority.- 4.2.4 Monitoring the Run Queue.- 4.2.5 Real-Time Timers.- 4.3 Real-Time Memory Allocation.- 4.3.1 Controlling Memory Allocation.- 4.3.2 Locking Pages into Memory.- 4.3.3 Example Program: Preallocating Memory for a Process.- 4.3.4 Example Program: Handling Real-Time Memory Violations.- 4.4 Interprocess Communications: Pipes, Signals and Events.- 4.4.1 Pipes and Named Pipes.- 4.4.2 Signals.- 4.4.3 Common Event Notification Mechanism.- 4.5 Interprocess Communications Using Shared Memory.- 4.5.1 Using Shared Memory.- 4.5.2 Creating a Shared Memory Segment.- 4.5.3 Allocating a Physical Shared Memory Segment.- 4.5.4 Controlling Shared Memory.- 4.5.5 Attaching and Detaching a Shared Memory Segment..- 4.5.6 Getting Physical Shared Memory Segment.- 4.5.7 Checking the Status of a Shared Memory Segment.- 4.6 Interprocess Communications Using Semaphores.- 4.6.1 Creating a Semaphore Structure and Array.- 4.6.2 Controlling Semaphores.- 4.6.3 Operations on Semaphores.- 4.6.4 Using Binary Semaphores.- 4.7 Interprocess Communications Using Messages.- 4.7.1 Creating Message Queues.- 4.7.2 Controlling Message Queues.- 4.7.3 Message Operations.- 4.8 Using Files.- 4.8.1 Fast File System.- 4.8.2 Creating Files and File Systems.- 4.8.3 Preallocating File Space.- 4.8.4 Bypassing the Buffer Cache.- 4.8.5 Asynchronous File I/O.- 4.8.6 Using Both Synchronous and Asynchronous I/O on a File.- 4.8.7 Synchronizing Disk Access.- 4.9 Interfacing Devices.- 4.9.1 Asynchronous I/O Operations.- 4.9.2 Traditional UNIX System Interrupts.- 4.9.3 Connected Interrupts.- 4.9.4 Direct I/O.- 4.10 Writing System Calls.- 4.10.1 Overview of System Calls.- 4.10.2 Guidelines for Writing System Calls.- 4.10.3 Installing System Calls in the Kernel.- 4.10.4 Accessing User-Defined System Calls.- 4.11 Porting Applications.- 4.11.1 Porting SVID-Compatible Applications.- 4.11.2 Porting from Proprietary Operating Systems.- 4.12 Performance Management.- 4.12.1 Creating an Efficient Environment.- 4.12.2 Maintaining System Efficiency.- 4.12.3 Solving Performance Problems.- 4.12.4 Measuring Performance.- 4.12.5 Performance Evaluation of the REAL/IX System.- 5 Case Studies.- 5.1 The Data Acquisition and Space Shuttle Launch Control System at NASA Kennedy Space Center.- 5.1.1 The Data Acquisition System.- 5.1.2 The Application Processing System.- 5.2 The Communication Processor at Jet Propulsion Laboratory.