Suppose we have a multiprogrammed computer in which each job has identical characteristics. In one computation period, T, for a job, two-thirds the time is spent in I/O, and the remaining third in processor activity. Each job runs for a total of N periods. Assume a simple round-robin scheduling is used, and I/O operations can overlap with processor operation. Define the following quantities:
Turnaround time = actual time to complete a job
Throughput = average number of jobs completed per time period T
Processor utilization = percentage of time that the processor is activer (not waiting)
Compute these quantities for one, two, and four simultaneous jobs, assumingr that the period T is distributed in each of the following ways:
What is the purpose of system calls, and how do system calls relate tor the OS and to the concept of dual-mode (kernel-mode and user-mode) operation?