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computer science operating systemcomputer science operating system
Typology: Summaries
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Each multiple-choice question has only one correct answer. Question 1 ( 1 point) โ What is operating system? a) OS is a collection of programs that manages hardware resources b) OS is a system service provider to the application programs c) OS is a link to interface the hardware and application programs d) OS is all of the mentioned e) OS is none of the mentioned Question 2 ( 1 point) โ To access the services of operating system, the interface is provided by: a) System calls b) API c) Library d) Assembly instructions e) None of the above Question 3 (1 point) โ Which one of the following is not true? a) kernel is the program that constitutes the central core of the operating system b) kernel is the first part of operating system to load into memory during booting c) kernel is made of various modules which cannot be loaded in running operating system d) kernel remains in the memory during the entire computer session Question 4 (1 point) โ In operating system, each process has its own: a) address space and global variables b) open files c) pending alarms, signals and signal handlers d) all of the above mentioned e) None of the above mentioned Question 5 ( 1 point) โ A process can be terminated due to: a) normal exit b) fatal error c) killed by another process d) all of the mentioned e) None of the above
Question 11 ( 1 point) โ The degree of multi-programming is: a) the number of processes executed per unit time b) the number of processes in the ready queue c) the number of processes in the I/O queue d) the number of processes in memory e) None of the above Question 12 (1 point) โ The parent process completes execution, but the child keeps executing, then the child process is known as: a) Orphan b) Zombie c) Body d) Dead e) None of the above Question 13 (1 point) โ When several processes access the same data concurrently and the outcome of the execution depends on the particular order in which the access takes place, is called: a) dynamic condition b) race condition c) essential condition d) critical condition e) None of the above Question 14 (1 point) โ In Java, you can create a thread by: a) Extending the Object class or using the intrinsic lock b) Creating a class called Thread or creating an interface called Runnable c) Implementing the Runnable interface or extending the Thread class d) Creating immutable objects out of the Task class e) Extending the Runnable class or implementing the Thread interface Question 15 (1 point) โ A monitor is a module that encapsulates: a) shared data structures b) procedures that operate on shared data structure c) synchronization between concurrent procedure invocation d) all of the mentioned e) None of the above
Question 16 (1 point) โ If all processes I/O bound, the ready queue will almost always be ______ and the Short term Scheduler will have a ______ to do. a) full, little b) full, lot c) empty, little d) empty, lot Question 17 (1 point) โ What is a medium-term scheduler? a) It selects which process has to be brought into the ready queue b) It selects which process has to be executed next and allocates CPU c) It selects which process to remove from memory by swapping d) None of the mentioned Question 18 (1 point) โ In a time-sharing operating system, when the time slot given to a process is completed, the process goes from the running state to the: a) Blocked state b) Ready state c) Suspended state d) Terminated state e) New state Question 19 (1 point) โ Suppose that a process is in โBlockedโ state waiting for some I/O service. When the service is completed, it goes to the: a) Running state b) Ready state c) Suspended state d) Terminated state e) none of the mentioned Question 20 (1 point) โ What is a short-term scheduler? a) It selects which process has to be brought into the ready queue b) It selects which process has to be executed next and allocates CPU c) It selects which process to remove from memory by swapping d) All of the mentioned e) none of the mentioned
Question 26 (1 point) โ Which one of the following cannot be scheduled by the kernel? a) kernel level thread b) user level thread c) process d) interrupt service routine e) none of the mentioned Question 27 (1 point) โ An I/O bound program will typically have: a) a few very short CPU bursts b) many very short I/O bursts c) many very short CPU bursts d) a few very short I/O bursts e) a few very long CPU bursts Question 28 (1 point) โ Bounded waiting implies that there exists a bound on the number of times a process is allowed to enter its critical section: a) before a process has made a request to enter its critical section b) when another process is in its critical section c) after a process has made a request to enter its critical section and before the request is granted d) all of the mentioned e) none of the mentioned Question 29 (1 point) โ A minimum of _____ variable(s) is/are required to be shared between processes to properly solve the critical section problem. a) zero b) one c) two d) three e) four Question 30 (1 point) โ To ensure data integrity in the readers โ writers problem, _______ are given exclusive access to the shared object. a) readers b) writers c) readers and writers d) not readers nor writers e) none of the mentioned
Question 31 (1 point) โ All processes share a semaphore variable mutex , initialized to 1. Each process must execute wait(mutex) before entering the critical section and signal(mutex) afterward. Suppose a process executes in the following manner: signal(mutex); ..... critical section ..... wait(mutex); In this situation: a) a deadlock will occur b) processes will starve to enter critical section c) several processes maybe executing in their critical section d) all of the mentioned e) none of the mentioned Question 32 (1 point) โ All processes share a semaphore variable mutex , initialized to 1. Each process must execute wait(mutex) before entering the critical section and signal(mutex) afterward. Suppose a process executes in the following manner: wait(mutex); ..... critical section ..... wait(mutex); In this situation: a) a deadlock will occur b) processes will starve to enter critical section c) several processes maybe executing in their critical section d) all of the mentioned e) none of the mentioned Question 33 (1 point) โ Consider the methods used by processes P1 and P2 for accessing their critical sections whenever needed, as given below. The initial values of shared Boolean variables S1 and S2 are randomly assigned. //Method used by P1 : while(S1==S2); Critical section S1 = S2; //Method used by P2 : while(S1!=S2); Critical section S2 = not(S1); In this situation, the following statements describes properties achieved:
Question 39 ( 3 point) โ The following program consists of 3 concurrent processes and 3 binary semaphores. The semaphores are initialized as S0 = 1, S1 = 0, S2 = 0. //Process P0 : while(true) { wait(S0); print '0'; release(S1); release(S2); } //Process P1 : wait(S1); release(S0); //Process P2 : wait(S2); release(S0); In this situation, P0 print โ0โ: a) At least twice b) Exactly twice c) Exactly three times d) At least three times e) none of the mentioned Question 40 ( 3 point) โ Each process Pi, I = 0,1,2,3,โฆโฆ,9 is coded as follows: While (true) { wait(mutex) {Critical Section} signal(mutex) } The code for P10 is coded as follows: While (true) { signal(mutex) {Critical Section} wait(mutex) } What is the largest number of processes that can be inside the critical section at any moment (the mutex being initialized to 1)? a) 1 b) 2 c) 3 d) 4 e) none of the mentioned
Question 41 (1 point) โ Two processes, P1 and P2, need to access a critical section of code. Consider the following synchronization construct used by the processes: //Process P1 : while(true) { w1 = true; while(w2 == true); Critical section w1 = false; } Remainder Section //Process P2 : while(true) { w2 = true; while(w1 == true); Critical section w2 = false; } Remainder Section Here, w1 and w2 are shared variables, which are initialized to false. Which one of the following statements is TRUE about the above construct? a) It does not ensure mutual exclusion b) It does not ensure bounded waiting c) It requires that processes enter the critical section in strict alternation d) It does not prevent deadlocks, but ensures mutual exclusion e) none of the mentioned Question 42 (1 point) โ Deadlock prevention is a set of methods: a) to ensure that at least one of the necessary conditions cannot hold b) to ensure that all of the necessary conditions do not hold c) to decide if the requested resources for a process have to be given or not d) to recover from a deadlock e) none of the mentioned Question 43 (1 point) โ To ensure that the hold and wait condition never occurs in the system, it must be ensured that: a) whenever a resource is requested by a process, it is not holding any other resources b) each process must request and be allocated all its resources before it begins its execution c) a process can request resources only when one is available d) any of the mentioned e) all of the mentioned
Question 47 (3 points) โ Consider the following table of arrival time and burst time for three processes P0, P1 and P2. Process Arrival time Burst Time P0 0 ms 9 ms P1 1 ms 4 ms P2 2 ms 9 ms 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? a) 4.0 ms b) 4.33 ms c) 5.0 ms d) 5 .33 ms e) 6. 33 ms Question 48 (3 points) โ The enter_CS() and leave_CS() functions to implement critical section of a process are realized using test-and-set instruction as follows: void enter_CS (X){ while (test-and-set(&X)==false) ; } void leave_CS (X){ X = 0; } bool test-and-set (int var){ if (var==0) { *var=1; return true; } else { return false; } } In the above solution, X is a memory location associated with the CS and is initialized to 0. Now consider the following statements: ID Statement S1 The above solution to CS problem is deadlock-free S2 The solution is starvation free S3 The processes enter CS in FIFO order S4 More than one process can enter CS at the same time Which of the above statements is TRUE? a) S1 only b) S1 and S c) S1 and S d) S 2 and S e) S4 only
Question 49 (3 points) โ In the following process state transition diagram for a uniprocessor system, assume that there are always some processes in the ready state: Now consider the following statements: ID Statement S1 If a process makes a transition D, it would result in another process making transition A immediately S2 A process P2 in blocked state can make transition E while another process P1 is in running state S3 The OS uses pre-emptive scheduling S4 The OS uses non-pre-emptive scheduling Which of the above statements are TRUE? a) S1 only b) S1 and S c) S1 and S d) S2 and S e) S2 and S Question 50 (1 point) โ Given a priori information about the ________ number of resources of each type that maybe requested for each process, it is possible to construct an algorithm that ensures that the system will never enter a deadlock state. a) minimum b) average c) maximum d) approximate e) None of the mentioned Question 51 (1 point) โ A state is safe, if: a) the system does not crash due to deadlock occurrence b) the system can allocate resources to each process in some order and still avoid a deadlock c) the state keeps the system protected and safe d) all of the mentioned e) None of the mentioned
