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Unformatted text preview: ll that pass control to the operating system. The operating system saves the shell’s context, creates a new hello process and its context, and then passes control to the new hello process. After hello terminates, the operating system restores the context of the shell process and passes control back to it, where it waits for the next command line input. Implementing the process abstraction requires close cooperation between both the low-level hardware and the operating system software. We will explore how this works, and how applications can create and control their own processes, in Chapter 8. One of the implications of the process abstraction is that by interleaving different processes, it distorts 14 CHAPTER 1. INTRODUCTION the notion of time, making it difﬁcult for programmers to obtain accurate and repeatable measurements of running time. Chapter 9 discusses the various notions of time in a modern system and describes techniques for obtaining accurate measurements. 1.7.2 Threads
Although we normally think of a pr...
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