Suppose you wish to run a program P with 9.3x109 instructions on a 2.2GHz machin

Question

Suppose you wish to run a program P with 9.3x109 instructions on a 2.2GHz machine with a CPI of 1.2. a) What is the expected CPU time if P could uninterruptedly occupy the processor? b) When you run P, it takes 6 seconds of wall clock time to complete. What is the percentage of the CPU time P received?

Suppose our processor is dual core (each core with a CPI of 1.2) and P was divided equally (in half) on the two cores. P can run uninterrupted on only one of the cores, while it could occupy only 75% of the processing time on the other core. What is the improvement in the overall execution time of P as opposed to the single core scenario in b)?

mainly having trouble with the bold

Explanation / Answer

a. execution time=(ic*cpi)/clock rate

=(9.3*109*1.2)/2.2

=552.92s

b. cpu time= ic*cpi*clock cycle

=9.3*109*1.2*6

=7298s

improvement in dual core with respect to single core

cpu time of x=552.92

cpu time of y i.e dual core=483.7(as another processor takes only 75% of the time)

this is the improvement with respect to single core

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