The Problem

In the tutorial sheet NO 2, in Exercise NO 1, in question NO 4 we were asked to calculate the waiting time for one job in the case of the OS evolution period time titled "Overlapping of CPU operations and I/O operations".

When we calculated it, we found that the waiting time of one job is greater than one job in case the previous evolution period time (Automatic sequencing = resident monitor). So a new question has arisen.

The question: How it comes? That in the recent period of OS evolution gives us a waiting time greater than the old period of OS evolution. It's not acceptable.

Logically, it's the opposite.

So how explains that?

The answer is as following:

In our answer in the tutorial session, we assumed that we have only one job or one batch. Thing that not meet the goal of the "Overlapping of CPU operations and I/O operations" evolution period with is the execution of CPU operations in parallel with I/O operations.

So in order to put the things in their correct places, we assume that we have more than one batch (450 jobs = 9 batches). And we have to recalculate the waiting time of one job in this case.

To do that, the students must firstly, draw correctly the chart of executing the 9 batches. And only after drawing the correct chart, they can calculate the new waiting time.

Remark:

To draw the executing chart, you can do that either by

• using a software such as MS Word to draw and write the answer, save it as a file.
• or using pen and paper and after that take picture of it using your phone and write the answer and then save the all in file.

The answer files must be submitted under this section before the deadline.

Good luck...