Saturday, November 24, 2007

IS215 - Processor Management Exercises - 2

11. Explain what is a fair scheduling algorithm?

12. What are the objectives of CPU scheduling?

Answer

The main objective of CPU scheduling is "to allocate the CPU so as to optimize system performance without sacrificing user convenience... To achieve the objective of CPU scheduling, we need to provide a good performance using the measures outlined above, meet user specified deadlines, and provide good utilization of other system resources."

13.Describe the advantages and disadvantages of two short-term scheduling policies that could be used to select which process next enters the run state.

14. State an undesirable feature associated with each of the following scheduling algorithms:
a) First-come-first-serve
b) Shortest job first
c) Shortest remaining processing

15. Round robin schedulers normally maintain a list of all runnable processes, with each process occurring exactly once in the list. What would happen if a process occurred twice in the list? Can you think of any reason for allowing this?

16. When is the response time of a process different from its waiting time.

17. Most operating systems usually use a two-level scheduler.
a) Give two advantages of this set-up.
b) Give two disadvantages of this set-up.
c) Describe the actions of a two-level scheduler when it is called to select a process to be dispatched.

18. Minimizing mean response time is the same as maximizing throughput. Prove this 'statement.

19. Evaluate the scheduling algorithms
a) First-Come-First-Serve
b) Shortest Job Next
c) Shortest Remaining Processing Time

in terms of the following criteria:
CPU utilization
throughput
turnaround time
waiting time.

20. Short time slices means better response times. Explain why this is so?

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