a) (5) A certain program executes in 320 seconds on a single-core system. A proposal is made to switch to a system that uses 16 of these cores. If the program can be evenly divided among the 16 cores, the potential speedup of 16 would provide an execution time of only 20 seconds for the program. However, the actual observed running time for the program on the 16 -core system is 120 seconds. Some fraction (
f)
of the original execution time on the single-core system is due to a parallel part of the program that can be evenly divided among the 16 cores and the remaining part of the program can only be executed on one core. On the 16-core system, what fraction of the total execution time is due to the parallel part of the program? b) (5) Suppose that it is desired to achieve a speedup of 80 for some other computation by switching from a single-core system to a 100 -core system. What is the maximum percentage of the computation that can be sequential? Maximum
