Your customers are complaining that the system is slow. After doing some research, you have learned that you can upgrade your disks for $8,000 to make them 2.5 times as fast as they are currently. You have also learned that you can upgrade your CPU to make it 1.4 as fast for $5,000.
a. Which would you choose to yield the best performance improvement for the least amount of money?
b. Which option would you choose if you don't care about the money, but want a faster system?
c. What is the break-even point for the upgrades? That is, what price would be charged for both upgrades to make their cost and performance improvement equal?
ASSUMPTION (using reference org and arch, Null & Lobur): Assuming processor load activity: 60% and disk I/O: 40%
For disk upgrade:
k = 2.5
f = 0.4
1-f = 0.6
Speedup, S_disk = 1/(0.6+0.4/2.5) = 1.3158
performance improvement = (1.3158-1)*100 = 31.58%
For CPU upgrade:
To select option of disk or CPU upgrade, calculations are carried out.