4. [3 + 4 = 7 points] When a program is adapted to run on multiple processors in a multiprocessor system, the execution time on each processor is comprised of computing time and the overhead time required for locked critical sections and/or to send data from one processor to another. Assume a program requires t = 100 s of execution time on one processor. When run on p processors, each processor requires t/p s, as well as an additional 4 s of overhead, irrespective of the number of processors. Compute the per-processor execution time for 2, 4 processors. List the ideal speedup has no overhead) for 2 processors, and 4 processors