Consider a demand-paging system in which processes are performing sequential data accesses with the following time-measured utilizations:

CPU utilization 20%

Paging disk 98%

Other I/O devices 10%

For each of the following, indicate yes or no to say whether or not it will (or is likely to) improve CPU utilization:

a. Install a faster CPU

b. Install a bigger paging disk

c. Increase the degree of multiprogramming

d. Decrease the degree of multiprogramming

e. Install more main memory

f. Install a faster hard disk

g. Increase the page size

a. Install a faster CPU - No

b. Install a bigger paging disk - No

c. Increase the degree of multiprogramming - No

d. Decrease the degree of multiprogramming - Yes

e. Install more main memory - Yes

f. Install a faster hard disk - Yes

g. Increase the page size - Yes

Explanation:

a. Install a faster CPU No.

Installing a faster CPU will not improve CPU utilization too much because the CPU utilization is low (20%) and the utilization of the paging disk is very high (98%), we can see that the system has lack of free memory.

b. Install a bigger paging disk No.

Installing a bigger paging disk doesn't improve the CPU utilization because the system has lack of free memory.

c. Increase the degree of multiprogramming No.

If the level of multiprogramming is increased more processes would have to be swapped in and out of the memory with a higher chance of page fault much frequently and the CPU utilization would reduce.

d. Decrease the degree of multiprogramming Yes.

If the level of multiprogramming is reduced less processes would have to be swapped in and out of memory, reducing the chance of page fault and the CPU utilization would improve.

e. Install more main memory

This is likely to improve CPU utilization as more pages can remain resident and not require paging to or from the disks.

f. Install a faster hard disk

With a faster hard disk, the CPU will get more data more quickly and this will lead to faster response and more throughput to the disks. With a faster hard disk, the disk is not a bottleneck to utilization.

g. Increase the page size

Increase the page size will likely degrade the performance, because the internal fragmentation will be worse, the utilization of main memory will be low, more processes will not be able to fit into main memory, and the system will have to spend more time in swapping. So this is as likely to decrease utilization as it is to increase it.