Question

Compare First Come First Served Scheduling, and Round Robin Scheduling. In your comparison, include discussions of their potential advantages and disadvantages, and which scheduling scheme performs better under what job load conditions. (You need to give proper reasons.)

Answer 1

ANSWERS :

ANS 1. Comparing First Come First Served and Round Robin Scheduling :

A) First Come First Served :

-- Advantages -

  

* It is very easy to understand and also comparitevly simple.

* It is most efficient for batch system.

-- Disadvantages -

* There is large waiting time for some processes.

* There is lower device and CPU utilization.

* It is problematic for time sharing systems.

* It does not favours Input Output Bound process but favours CPU process.

B) Round Robin Scheduling :

-- Advantages -

* There is no starvation ot aging in this scheduling.

* Each an every process gets equal CPU share.

-- Disadvantages -

* The average waiting time is usually high in this scheduling.

* If quantum number is very short the efficiency of CPU decreases, similarly if the quantum number is very high the response gets bad.

FCFC works best in following load condition:

- In a situation where the process that are coming are short it is most efficient.

This is because when the process are short then no particular process will have to wait for a longer time for execution thus the processes will be executed efficiently.

RR works best in following load condition :

- In a situation when the processes are mixed i.e. both short and long process and the completion of all the process in a particular time is the necessary feature for the success.

This is because in RR there is time quantum , thus all the process gets CPU for a particular time and thus there will be no starvation and all process will be completed within time