申論題

3. You are going to enhance a computer, and there are two possible improvements: either make multiply instructions run four times faster than before, or make memory access instructions run two times faster than before. You repeatedly run a program that takes 100 seconds to execute. Of this time, 20% is used for multiplication, 50% for memory access instructions, and 30% for other tasks.

3.2 You are going to change the program described in Problem 3 so that the percentages are not 20%, 50%, and 30% anymore. Assuming that none of the new percentages is O, what sort of program would result in a tie with regard to speedup (i.e., the same speedup) between the two individual improvements? Provide both a formula and some examples.