2. Computer Performance (6 marks in total) (a) (2 marks) Consider a system with only two types of instructions, A and B. Type A instructions have a CPI of 3, while type B instructions have a CPI of 1. The CPI for a particular program when executed on this system is 2.5. What must be the fraction fa of instructions executed that are of type A? (b) (2 marks) For a particular program as run on a particular system, 500 million instructions are executed, the clock rate is 2 GHz, and the CPI is 2. What is the CPU execution time? (c) (2 marks) One way to try to decrease the running time of a computationally-intensive program is to run it on a system with multiple processors. The effectiveness of this approach depends on how much of the program can be worked on by multiple processors in parallel. Suppose that a fraction f of the execution time of the program, when just a single processor is used, is spent executing a part of the program that cannot use multiple processors or execute concurrently with any other part of the program. Write an expression for the maximum possible speedup (ratio of execution time when run with a single processor to that when run using multiple processors), as a function off and the number of processors N