Computer Science: An Overview: Global Edition (12th Edition)

Published by Pearson Higher Education

Chapter 3 - Operating Systems - Section 3.3 - Coordinating the Machine's Activities - Questions & Exercises - Page 155: 5

Answer

A total of $\frac{5000}{5001}$ of the machine’s time would be spent actually performing processes. However, when a process requests an I/O activity, its time slice is terminated while the controller performs the request. Thus if each process made such a request after only one microsecond of its time slice, the efficiency of the machine would drop to 1/2. That is, the machine would spend as much time performing context switches as it would executing processes.

Work Step by Step

A total of $\frac{5000}{5001}$ of the machine’s time would be spent actually performing processes. However, when a process requests an I/O activity, its time slice is terminated while the controller performs the request. Thus if each process made such a request after only one microsecond of its time slice, the efficiency of the machine would drop to 1/2. That is, the machine would spend as much time performing context switches as it would executing processes.

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