1. The decision to add to the number of processes that are partially or fully

in memory.

Medium-term scheduling

2. The decision as to which process’s pending I/O request shall be handled

by an available I/O device.

3. The decision as to which available process will be executed by the

processor.

4. The decision to add to the pool of processes to be executed.

Long-term scheduling

Medium-term scheduling

Long-term scheduling

Short-term scheduling

Long-term scheduling

Medium-term scheduling

10. The long-term scheduler controls the degree of ...

multiprogramming

11. There are two decisions involved in long term scheduling. First, _____ to take on more processes.

whether

12. Second, _____ processes to take on.

which

13. The short-term scheduler is also known as the _____.

dispatcher

14. The short-term scheduler is invoked whenever an event occurs that may

a.

lead to the suspension of the current process

b.

provide an opportunity to preempt the currently running process

15. Give 4 examples of such events.

clock interrupts

I/O interrupts

operating system calls

signals

16. The time from the submission of a request until the response begins to be

received.

17. The interval of time between the submission of a process and its

completion.

18. A given job should run in about the same amount of time and at about the

same cost regardless of the load on the system.

Predictability

19. The scheduling policy should attempt to maximize the number of processes complete per unit of time.

20. The percentage of time that the processor is busy.

21. Processes should be treated the same and no process should suffer

starvation.

22. The scheduling policy should keep the resources of the system busy.

Balancing resources

23. Which of these criteria are user-oriented?

Response time

Turnaround time

Predictability

24. Which of these criteria are system-oriented?

Throughput

Processor utilization

fairness

Balancing resources

25. Clock interrupts are generated at periodic intervals. When the interrupt

occurs the currently running process is placed in the ready queue and the

next ready job is selected on a first-come first-serve basis.

Round-Robin

26. A non-preemptive policy in which the process with the shortest expected

processing time is selected next.

Shortest process next

27. When the currently running process ceases to execute, the oldest process

in the ready queue is selected for running.

FCFS or FIFO

28. Use levels of FCFS queues (except that the lowest level one is Round

Robin). Each time a process returns to the Ready state, it is placed into

a lower level queue.

Feedback

29. Choose the ready process with the greatest value of RR, where

RR = (w + s)/s, where

w = time spent waiting for the processor

s = expected service time

Highest Response Ratio Next

30. A preemptive version of SPN.

Shortest Remaining time

31. Without preempting the current process, choose that process which has

the shortest expected remaining processing time.

Shortest Process Next

32. The ratio of turnaround time to actual service time is ...

Normalized turnaround time

33. ... are preemptive?

Round Robin

Feedback

SRT

34. ... are non-preemptive?

FCFS

SPN

HRRN

35. ... penalizes short processes?

FCFS

36. ... penalize long processes?

SPN

SRT

37. ... penalizes I/O bound processes?

FCFS

38. ... may favor I/O bound processes?

Feedback

39. ... may starve some processes?

SPN

SRT

Feedback

40. What is time-slicing?

Each process is given a slice of time to run before being preempted.

41. Most scheduling algorithms treat the collection of ready processes as a

single pool from which to select the next running process. Alternatively,

processes could be viewed as being a set belonging to one or another

user. Then each user is assigned a weighting of some sort that defines

the user’s share of the system resources as a fraction of the total usage

of those resources. In particular each user is assigned a share of the

processor. This is known as ...

Fair Share Scheduling