operating system 12 – www.savvyessaywriters.net
operating system 12 – www.savvyessaywriters.net
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1- In Fig. 2-2, three process states are shown. In theory, with three states, there could be six transitions, two out of each state. However, only four transitions are shown. Are there any circumstances in which either or both of the missing transitions might occur?
5. A computer system has enough room to hold fiv e programs in its main memory. These programs are idle waiting for I/O half the time. What fraction of the CPU time is wasted?
9. Assume that you are trying to download a large 2-GB file from the Internet. The file is available from a set of mirror servers, each of which can deliver a subset of the file’s bytes; assume that a given request specifies the starting and ending bytes of the file. Explain how you might use threads to improve the download time.
13. In the text, we described a multithreaded Web server, showing why it is better than a single-threaded server and a finite-state machine server. Are there any circumstances in which a single-threaded server might be better? Give an example.
22. Suppose that an operating system does not have anything like the select system call to see in advance if it is safe to read from a file, pipe, or device, but it does allow alarm clocks to be set that interrupt blocked system calls. Is it possible to implement a threads package in user space under these conditions? Discuss.
36. A fast-food restaurant has four kinds of employees: (1) order takers, who take customers’ orders; (2) cooks, who prepare the food; (3) packaging specialists, who stuff the food into bags; and (4) cashiers, who give the bags to customers and take their money. Each employee can be regarded as a communicating sequential process. What form of interprocess communication do they use? Relate this model to processes in UNIX.
44. Five jobs are waiting to be run. Their expected run times are 9, 6, 3, 5, and X. In what order should they be run to minimize average response time? (Your answer will depend on X.)
48. For the above problem, can another video stream be added and have the system still be schedulable?
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