OS_CPU Scheduling Quiz01

Which one or more of the following CPU scheduling algorithms can potentially cause starvation?

• Round Robin

• First Come First Serve

• Priority Scheduling

• Shortest Job First

Consider four processes P, Q, R and S scheduled on a CPU as per round robin algorithm with a time quantum of 4 units. The processes arrive in the order P, Q, R, S, all at time t = 0. There is exactly one context switch from S to Q, exactly one context switch from R to Q, and exactly two context switches from Q to R. There is no context switch from S to P. Switching to a ready process after the termination of another process is also considered a context switch. Which one of the following is NOT possible as CPU burst time (in time units) of these processes?

• P = 4, Q = 10, R = 6, S = 2 

• P = 2, Q = 9, R = 5, S = 1

• P = 4, Q = 12, R = 5, S = 4

• P = 3, Q = 7, R = 7, S = 3 

Consider the following statements about process state transitions for a system using preemptive scheduling. A running process can move to ready state when:

• It is interrupted by an I/O request

• It is preempted by a higher priority process

• It completes its CPU burst

• It is blocked by a semaphore

Consider an arbitrary set of CPU-bound processes with unequal CPU burst lengths submitted at the same time to a computer system. Which one of the following scheduling algorithms is most suitable?

• First Come First Serve

• Round Robin

• Shortest Job First

• Priority Scheduling

The maximum number of processes that can be in Ready state for a computer system with n CPUs is:

• n

• n²

• 2n

• Independent of n

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?

• This algorithm is equivalent to the first-come-first-serve algorithm

• This algorithm is equivalent to the round-robin algorithm.
  

• This algorithm is equivalent to the shortest-job-first algorithm

• This algorithm is equivalent to the shortest-remaining-time-first algorithm

Which of the following statements are true?

I. Shortest remaining time first scheduling may cause starvation

II. Preemptive scheduling may cause starvation

III. Round robin is better than FCFS in terms of response time

• I, II and III

• I only

• I and III only

• II and III only

Which of the following scheduling algorithms is non-preemptive?

• Shortest Job First

• First Come First Serve

• Priority Scheduling

• Round Robin

Consider a set of n tasks with known runtimes to be run on a uniprocessor machine. Which of the following processes is most suitable for minimizing average turnaround time?

• Shortest Job First

• Round Robin

• Priority Scheduling

• First Come First Serve

Consider the following statements about process state transitions for a system using preemptive scheduling.

I. A running process can move to ready state.
II. A ready process can move to ready state.
III. A blocked process can move to running state.
IV. A blocked process can move to ready state.

Which of the above statements are TRUE?

• I, II, and III only

• II and III only

• I, II, and IV only

• I, II, III and IV only