Operating System
Q21.
In a system using single processor, a new process arrives at the rate of six processes per minute and each such process requires seven seconds of service time. What is the CPU utilization?Q22.
Which of the following is not an optimization criterion in the design of a CPU scheduling algorithm?Q23.
A starvation free job scheduling policy guarantees that no job indefinitely waits for a service. Which of the following job scheduling policies is starvation free?Q24.
Three processes A, B and C each execute a loop of 100 iterations. In each iteration of the loop, a process performs a single computation that requires t_{c} CPU milliseconds and then initiates a single I/O operation that lasts for t_{io} milliseconds. It is assumed that the computer where the processes execute has sufficient number of I/O devices and the OS of the computer assigns different I/O devices to each process. Also, the scheduling overhead of the OS is negligible. The processes have the following characteristics: The processes A, B, and C are started at times 0, 5 and 10 milliseconds respectively, in a pure time sharing system (round robin scheduling) that uses a time slice of 50 milliseconds. The time in milliseconds at which process C would complete its first I/O operation is ___________.Q25.
Consider the 3 processes, P1, P2 and P3 shown in the table. The completion order of the 3 processes under the policies FCFS and RR2 (round robin scheduling with CPU quantum of 2 time units) areQ26.
A CPU scheduling algorithm determines an order for the execution of its scheduled processes. Given 'n' processes to be scheduled on one processor, how many possible different schedules are there?Q27.
Consider the following set of processes that need to be scheduled on a single CPU. All the times are given in milliseconds Using the shortest remaining time first scheduling algorithm, the average process turnaround time (in msec) is ________.Q28.
A scheduling algorithm assigns priority proportional to the waiting time of a process. Every process starts with priority zero (the lowest priority). The scheduler re-evaluates the process priorities every T time units and decides the next process to schedule. Which one of the following is TRUE if the processes have no I/O operations and all arrive at time zero?Q29.
Consider the following set of processes, with arrival times and the required CPU-burst times given in milliseconds. \begin{array}{|l|l|l|l|} \hline \textbf{Process} & \textbf{Arrival time} & \textbf{Burst Time} \\\hline \text{$P_1$} & \text{0} & \text{4} \\\hline \text{$P_2$} & \text{2} & \text{2} \\\hline \text{$P_3$}& \text{3} & \text{1} \\\hline \end{array} What is the sequence in which the processes are completed? Assume round robin scheduling with a time quantum of 2 milliseconds?