We will now examine cost-performance issues in sorting. After all, it is easy to buy a high-performing machine; it is much harder to buy a costeffective one.
One place where this issue arises is with the PennySort competition (research.microsoft.com/barc/SortBenchmark/). PennySort asks that you sort as many records as you can for a single penny. To compute this, you should assume that a system you buy will last for 3 years (94,608,000 seconds), and divide this by the total cost in pennies of the machine. The result is your time budget per penny.
Our task here will be a little simpler. Assume you have a fixed budget of $2000 (or less). What is the fastest sorting machine you can build? Use the same hardware table as in Exercise 6.28 to configure the winning machine.
(You might want to write a little computer program to generate all the possible configurations.)
a. What is the total cost of your machine? (Break this down by part, including the cost of the CPU, amount of memory, number of disks, and I/O bus.)
b. How does the reading, writing, and sorting time break down with this configuration?
c. What is the bottleneck in your system?