Scheduling

Question 1

What are the different types of scheduling?

Answer 1

Long Term
The decision to add to the pool of processes to be executed

Medium Term
The decision to add to the number of processes that are partially or fully in main memory

Short Term
The decision as to which available process will be executed by the processor

I/O Scheduling
The decision as to which process awaiting i/o request will be sent to an available i/o device

Question 2

What is the aim of processor scheduling ?

Answer 2

The aim is to assign processes to a processor or processes that meet system objectives such as response time, throughput and processor efficiency

Question 3

Differenciate between user oriented criteria and system oriented criteria

Answer 3

User oriented criteria deals with the system behavior as perceived by the user

System oriented criteria deals with efficient and effective utilization of the processor

Question 4

Define Turn around time

Answer 4

The time between the submission of the request and its completion.
actual execution time + time waiting for resources

Question 5

Define response time

Answer 5

The time from the submission of the request until the request begins to be received

Question 6

what is throughput ?

Answer 6

the number of processor executed per unit of time
a measure of how much work is being done

Question 7

Explain the concept of Round Robin

Answer 7

Round Robin also known as time slicing is a process inwhich a clock interrupt interval is generated at specific intervals and when the interrup occurs, the currently running process is placed in the ready queue.

Question 8

Explain the concept of shortest process next (spn)

Answer 8

Nonpreemptive policy in which the process with the shortest expected processing time is selected next

Question 9

State disadvantages of spn

Answer 9

possibility of longer processes starving
need to know an estimated processing time before hand