processes (3) - COP 4600 Summer 2011 Introduction To...

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COP 4600: Intro To OS (Processes) Page 1 © Dr. Mark Llewellyn COP 4600 – Summer 2011 Introduction To Operating Systems Chapter 3 – Process Description And Control Department of Electrical Engineering and Computer Science Computer Science Division University of Central Florida Instructor : Dr. Mark Llewellyn markl@cs.ucf.edu HEC 236, 407-823-2790 http://www.cs.ucf.edu/courses/cop4600/sum2011
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COP 4600: Intro To OS (Processes) Page 2 © Dr. Mark Llewellyn Scheduling and Resource Management Fairness Give equal and fair access to resources Differential responsiveness Discriminate among different classes of jobs Efficiency Maximize throughput, minimize response time, and accommodate as many uses as possible
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COP 4600: Intro To OS (Processes) Page 3 © Dr. Mark Llewellyn Key Elements of an Operating System
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COP 4600: Intro To OS (Processes) Page 4 © Dr. Mark Llewellyn System Structure Over the years as more and more features have been added to the OS, and the underlying hardware has become more capable and versatile, the size and complexity of operating systems has grown. IBM’s OS/360 (1964) contained just over 10 6 machine instructions. By the mid- 1970s the Multics OS contained more than 20x10 6 machine instructions. Windows 2000 contains more than 32x10 6 lines of code. Windows XP has more than 40x10 6 lines of code. The Linux Fedora 9 kernel contains about 7x10 6 lines of code with the entire distribution just over 204x10 6 lines of code. Modular programming alone is not sufficient to manage the development of such large systems of code. There has been an increasing use of hierarchical layers and information abstraction in the design of modern OS. The hierarchical approach views the OS as a series of levels where each level performs a related subset of functions Each level relies on the next lower level to perform more primitive functions. This decomposes a problem into a number of more manageable subproblems
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COP 4600: Intro To OS (Processes) Page 5 © Dr. Mark Llewellyn System Structure In general, lower layers deal with a far shorter time scale. Some parts of the OS must interact directly with the computer hardware, where events can have a time scale as brief as a few billionths of a second. At the other end of the spectrum, parts of the OS communicate with the user, who issues commands at a much more leisurely pace, perhaps one every few seconds.
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COP 4600: Intro To OS (Processes) Page 6 © Dr. Mark Llewellyn Level Name Objects Example Operations 13 Shell User programming environment Statements in shell language 12 User processes User processes Quit, kill, suspend, resume, … 11 Directories Directories Create, destroy, attach, search, … 10 Devices External devices Open, close, read, write, … 9 File system Files Create, destroy, open, close, read, … 8 Communications Pipes Create, destroy, open, write, … 7 Virtual memory Segments, pages Read, write, fetch, … 6 Local secondary store
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This note was uploaded on 10/03/2011 for the course COP 4600 taught by Professor Montagne during the Summer '08 term at University of Central Florida.

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processes (3) - COP 4600 Summer 2011 Introduction To...

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