1. (You may use up to two pages and single-space for this question) Consider a skate rental shop that has two rental agents, a counter, and a waiting area that can accommodate up to four customers on a bench and provides standing room for additional patrons. By law the shop has a maximum customer capacity of 10. The rental agent fills a patrons request to rent a pair of skis.
A customer cannot enter the shop if it is filled to capacity. If the previous condition is false, a customer will either take a seat on the bench or stand if the bench is full. As soon as a server is free, the customer that has been on the bench the longest is served and if any patrons are standing, the one that has been in the shop the longest takes a seat on the bench.
When a pair of skates is rented, the rental agent accepts payment then serves the next patron (if one is present). Your task is to write a program in pseudo-code using semaphores. The rental agent is a task as well as each customer.
2. Given a four level hierarchical storage system consisting of: cache, primary storage, secondary storage, and tertiary storage. Assume the following: programs may be executed on any of the four levels; each level consists of the same amount of real storage and the range of addresses on each level is identical. The speed at which programs are run is grouped from slowest (tertiary storage) to fastest (cache), where each layer is 10 times faster than the previous lower layer. There exists one CPU in this system, which may run one program at a time. Programs may be shuttled from any layer to any layer.
a) Why might the operating system choose to move information from a faster level to a slower level, bypassing an intermediate level, IE. from cache to secondary storage?
b) Why would items move from a slower layer to a faster layer?
e) Should Information be allowed to move from any level to any level or should transfers only occur from adjacent levels? Explain in detail.
3. Determining the time quantum for a job is a critical task. Given the assumptions that the average switching time between processes is s, and the average amount of time an 110 bound process uses before generating an I/O request is t (t » s). Discuss the effect of each of the following quantum settings denoted by q.
a) q = infinity
b) q is slightly greater than zero
c) q = s
d) s
e) q=t
f) q > t
4. Dr. Zeus provided an extensive analysis of the dependability properties of operating systems. Her report included the relative value of the manageability of an operating system and a potential set of metrics that directly relate manageability to the dependability of that operating system. Unfortunately Dr. Zeus won the lottery, took off for parts unknown and in the process did not provide her report- some say she is writing books for children (the word on the street is that the books do not include operating system topics). Your task is to provide your metric for system manageability to substitute for the Zeus on the Loose Report. Be advised that Dr. Zeus produced detailed and supported work prior to her disappearance.
5. A virtual storage system has page size p, block size b, and fixed-length record size r. Discuss the various relationships among p, b, and r that make for the most efficient system. Give a detailed account of your explanation.