East West University, Dhaka

CSE 325

1. fork() system call will generate 2n processes where n is number of fork system calls. Identify a situation where fork() will produce 6 processes. How many times you need to call fork() to generate 6 processes. Explain the scenario graphically with proper explanation. 4 2. Assume a uniprocessor system has three processes P1, P2, and P3 and P1 needs four (4), P2 needs six (6), and P3 needs three (3) seconds CPU time. Each of which needs five (5), two (2), three (3) seconds of input waiting time respectively and three (3), four (4), three (3) seconds of output waiting time respectively. How long will it take to complete the processes in: a. Batch processing system? b. Multiprogramming processing system? Also, calculate the time efficiency. 4 3. Consider a program that contains two methods. One method need continuous input from keyboard and another method print some information using printer. Propose a processor-device communication model that adopts best of the both approaches (polling and interrupt) to make I/O communication for above program more efficient. What are the advantages of the approach that you have taken over the other approach?