Suppose the daytime processing load consists of 65% CPU activity and 35% disk ac

Question

Suppose the daytime processing load consists of 65% CPU activity and 35% disk activity. 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 1.7 as fast for $10,000.

1) Which would you choose to yield the best performance improvement for the least amount of money?

2) What is the speedup by device in question 19, if f=.5 for each resource?

Explanation / Answer

Given information is, Fraction of work: 65% CPU,
35% disk.
SCPU = 1/((1-f)+(f/k))
= 1/((1-0.65)+(0.65/1.7))
= 3.24

SDISK= 1/((1-f)+(f/k))
= 1/((1-0.35)+(0.35/2.5))
=1.68
a. Choose the CPU upgrade:
$10000/3.24
$8000/1.68

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