GATE CS : Operating Systems Champion Quiz 4 for GATE & PSU CS Exams

Question 1

Group 1 contains some CPU scheduling algorithms and Group 2 contains some applications. Match entries in Group 1 to entries in Group 2.

Question 2

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?

Question 3

Consider a set of n tasks with known runtimes r₁, r₂, ….r_n to be run on uniprocessor machine. Which of the following processor scheduling algorithms will result in the maximum throughput?

Question 4

The optimal page replacement algorithm will select the page that

Question 5

Comparing the time T1 taken for a single instruction on a pipelined CPU with timeT2 taken on a non-pipelined but identical CPU, we can say that

Question 6

Consider three processes, all arriving at time zero, with total execution time of 10, 20 and 30 units, respectively. Each process spends the first 20% of execution time doing I/O, the next 70% of time doing computation, and the last 10% of time doing I/O again. The operating system uses a shortest remaining compute time first scheduling algorithm and schedules a new process either when the running process gets blocked on I/O or when the running process finishes its compute burst. Assume that all I/O operations can be overlapped as much as possible. For what percentage of time does the CPU remain idle?

Question 7

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?

Question 8

Consider the following set of processes, with the arrival times and the CPU-burst times given in milliseconds.

What is the average turnaround time for these processes with the preemptive shortest remaining processing time first (SRPT) algorithm?

Question 9

Consider the following table of arrival time and burst time for three processes P0, P1 and P2.

The pre-emptive shortest job first scheduling algorithm is used. Scheduling is carried out only at arrival or completion of processes. What is the average waiting time for the three processes?

Question 10

An operating system uses Shortest Remaining Time first (SRTF) process scheduling algorithm. Consider the arrival times and execution times for the following processes:

What is the total waiting time for process P2?