Most people agree that charges for computer system usage should be fair, but few can define precisely what “fairness” is.Another attribute of charging schemes, but one which is easier to define, is predictability.We want to know that if a job costs a certain amount to run once, running it again in similar circumstances will cost approximately the same amount. Suppose that in a multiprogramming environment we charge by wall clock time, i.e., the total real time involved in running the job from start to completion.Would such a scheme yield predictable charges?Why?

What will be an ideal response?

Such a scheme would probably not yield predictable charges simply, because
jobs are likely to take longer in a heavily loaded system.