Operating System MCQ (Multiple Choice Questions) - SchoolingAxis

Operating System MCQ (Multiple Choice Questions)

 Que- The One to One model allows : 

a. increased concurrency 

b. decreased concurrency 

c. increased or decreased concurrency 

d. concurrency equivalent to other models 


Answer- increased concurrency        


Que- In the One to One model when a thread makes a blocking system call : 

a. other threads are strictly prohibited from running 

b. other threads are allowed to run 

c. other threads only from other processes are allowed to run 

d. none of the mentioned 


Answer- other threads are allowed to run        


Que- Which of the following is the drawback of the One to One Model ? 

a. increased concurrency provided by this model 

b. decreased concurrency provided by this model 

c. creating so many threads at once can crash the system 

d. creating a user thread requires creating the corresponding kernel thread 


Answer- creating a user thread requires creating the corresponding kernel thread        


Que- When is the Many to One model at an advantage ? 

a. When the program does not need multithreading 

b. When the program has to be multi-threaded 

c. When there is a single processor 

d. None of the mentioned 


Answer- When the program does not need multithreading        


Que- In the Many to Many model true concurrency cannot be gained because : 

a. the kernel can schedule only one thread at a time 

b. there are too many threads to handle 

c. it is hard to map threads with each other 

d. none of the mentioned 


Answer- the kernel can schedule only one thread at a time        


Que- In the Many to Many model when a thread performs a blocking system call : 

a. other threads are strictly prohibited from running 

b. other threads are allowed to run 

c. other threads only from other processes are allowed to run 

d. none of the mentioned 


Answer- other threads are allowed to run        


Que- Which of the following system calls does not return control to the calling point, on termination ? 

a. fork 

b. exec 

c. ioctl 

d. longjmp  


Answer- exec        


Que- The following program:   main()   {      if(fork()>0)      sleep(100);   }   results in the creation of: 

a. an orphan process 

b. a zombie process 

c. a process that executes forever 

d. none of the mentioned  


Answer- a zombie process        


Que- Which of the following system calls transforms executable binary file into a process ? 

a. fork 

b. exec 

c. ioctl 

d. longjmp  


Answer- exec        


Que- The following C program : main()   {     fork();fork();printf(""yes"");   }   prints yes: 

a. only once 

b. twice 

c. four times 

d. eight times  


Answer- four times        


Que- Which of the following calls never returns an error ? 

a. getpid 

b. fork 

c. ioctl 

d. open  


Answer- getpid        


Que- A fork system call will fail if : 

a. the previously executed statement is also a fork call 

b. the limit on the maximum number of processes in the system would be executed 

c. the limit on the minimum number of processes that can be under execution by a single user would be executed 

d. all of the mentioned  


Answer- the limit on the maximum number of processes in the system would be executed        


Que- If a thread invokes the exec system call, 

a. only the exec executes as a separate process. 

b. the program specified in the parameter to exec will replace the entire process 

c. the exec is ignored as it is invoked by a thread. 

d. none of the mentioned  


Answer- the program specified in the parameter to exec will replace the entire process        


Que- If exec is called immediately after forking, 

a. the program specified in the parameter to exec will replace the entire process 

b. all the threads will be duplicated 

c. all the threads may be duplicated 

d. none of the mentioned  


Answer- the program specified in the parameter to exec will replace the entire process        


Que- If a process does not call exec after forking, 

a. the program specified in the parameter to exec will replace the entire process 

b. all the threads should be duplicated 

c. all the threads should not be duplicated 

d. none of the mentioned  


Answer- all the threads should be duplicated        


Que- Thread cancellation is : 

a. the task of destroying the thread once its work is done 

b. the task of removing a thread once its work is done 

c. the task of terminating a thread before it has completed 

d. none of the mentioned  


Answer- the task of terminating a thread before it has completed        


Que- When a web page is loading, and the user presses a button on the browser to stop loading the page : 

a. the thread loading the page continues with the loading 

b. the thread loading the page does not stop, but continues with another task 

c. the thread loading the page is paused 

d. the thread loading the page is cancelled  


Answer- the thread loading the page is cancelled         


Que- When one thread immediately terminates the target thread, it is called : 

a. Asynchronous cancellation 

b. Systematic cancellation 

c. Sudden Termination 

d. Deferred cancellation  


Answer- Asynchronous cancellation        


Que- When the target thread periodically checks if it should terminate and terminates itself in an orderly manner, it is called : 

a. Asynchronous cancellation 

b. Systematic cancellation 

c. Sudden Termination 

d. Deferred cancellation  


Answer- Deferred cancellation         


Que- Cancelling a thread asynchronously : 

a. frees all the resources properly 

b. may not free each resource 

c. spoils the process execution 

d. none of the mentioned  


Answer- may not free each resource        


Que- Cancellation point is the point where : 

a. the thread can be cancelled - safely or otherwise doesn't matter 

b. the thread can be cancelled safely 

c. the whole process can be cancelled safely 

d. none of the mentioned  


Answer- the thread can be cancelled safely        


Que- If multiple threads are concurrently searching through a database and one thread returns the result then the remaining threads must be : 

a. continued 

b. cancelled 

c. protected 

d. none of the mentioned  


Answer- cancelled        


Que- Signals that occur at the same time, are presented to the process : 

a. one at a time, in a particular order 

b. one at a time, in no particular order 

c. all at a time 

d. none of the mentioned 


Answer- one at a time, in no particular order        


Que- Which of the following is not TRUE : 

a. Processes may send each other signals 

b. Kernel may send signals internally 

c. a field is updated in the signal table when the signal is sent 

d. each signal is maintained by a single bit 


Answer- a field is updated in the signal table when the signal is sent        


Que- Signals of a given type : 

a. are queued 

b. are all sent as one 

c. cannot be queued 

d. none of the mentioned  


Answer- are all sent as one        


Que- The three ways in which a process responds to a signal are : 

a. ignoring the signal 

b. handling the signal 

c. performing some default action 

d. all of the mentioned  


Answer- all of the mentioned         


Que- Signals are identified by : 

a. signal identifiers 

b. signal handlers 

c. signal actions 

d. none of the mentioned  


Answer- signal identifiers        


Que- When a process blocks the receipt of certain signals : 

a. The signals are delivered 

b. The signals are not delivered 

c. The signals are received until they are unblocked 

d. The signals are received by the process once they are delivered  


Answer- The signals are delivered        


Que- The _______ maintains pending and blocked bit vectors in context of each process. 

a. CPU 

b. Memory 

c. Process 

d. Kernel  


Answer- Kernel         


Que- In UNIX, the set of masked signals can be set or cleared using the ________ function. 

a. sigmask 

b. sigmaskproc 

c. sigprocmask 

d. sigproc  


Answer- sigprocmask        


Que- The usefulness of signals as a general inter process communication mechanism is limited because : 

a. they do not work between processes 

b. they are user generated 

c. they cannot carry information directly 

d. none of the mentioned  


Answer- they cannot carry information directly        


Que- The usual effect of abnormal termination of a program is : 

a. core dump file generation 

b. system crash 

c. program switch 

d. signal destruction  


Answer- core dump file generation        


Que- In UNIX, the abort() function sends the ________ signal to the calling process, causing abnormal termination. 

a. SIGTERM 

b. SIGSTOP 

c. SIGABORT 

d. SIGABRT  


Answer- SIGABRT         


Que- In most cases, if a process is sent a signal while it is executing a system call : 

a. the system call will continue execution and the signal will be ignored completely 

b. the system call is interrupted by the signal, and the signal handler comes in 

c. the signal has no effect until the system call completes 

d. none of the mentioned  


Answer- the signal has no effect until the system call completes        


Que- A process can never be sure that a signal it has sent _____________ 

a. has which identifier 

b. has not been lost 

c. has been sent 

d. all of the mentioned  


Answer- has not been lost        


Que- In UNIX, the _____ system call is used to send a signal. 

a. sig 

b. send 

c. kill 

d. sigsend  


Answer- kill        


Que- Thread pools are useful when : 

a. when we need to limit the number of threads running in the application at the same time 

b. when we need to limit the number of threads running in the application as a whole 

c. when we need to arrange the ordering of threads 

d. none of the mentioned  


Answer- when we need to limit the number of threads running in the application at the same time        


Que- Instead of starting a new thread for every task to execute concurrently, the task can be passed to a ___________ 

a. process 

b. thread pool 

c. thread queue 

d. none of the mentioned  


Answer- thread pool        


Que- Each connection arriving at multi threaded servers via network is generally : 

a. is directly put into the blocking queue 

b. is wrapped as a task and passed on to a thread pool 

c. is kept in a normal queue and then sent to the blocking queue from where it is dequeued 

d. none of the mentioned  


Answer- is wrapped as a task and passed on to a thread pool        


Que- The idea behind thread pools is : 

a. a number of threads are created at process startup and placed in a pool where they sit and wait for work 

b. when a process begins, a pool of threads is chosen from the many existing and each thread is allotted equal amount of work 

c. all threads in a pool distribute the task equally among themselves 

d. none of the mentioned  


Answer- a number of threads are created at process startup and placed in a pool where they sit and wait for work        


Que- If the thread pool contains no available thread : 

a. the server runs a new process 

b. the server goes to another thread pool 

c. the server demands for a new pool creation 

d. the server waits until one becomes free  


Answer- the server waits until one becomes free         


Que- Thread pools help in : 

a. servicing multiple requests using one thread 

b. servicing a single request using multiple threads from the pool 

c. faster servicing of requests with an existing thread rather than waiting to create a new thread 

d. none of the mentioned  


Answer- faster servicing of requests with an existing thread rather than waiting to create a new thread        


Que- Thread pools limit the number of threads that exist at any one point, hence : 

a. not letting the system resources like CPU time and memory exhaust 

b. helping a limited number of processes at a time 

c. not serving all requests and ignoring many 

d. none of the mentioned  


Answer- not letting the system resources like CPU time and memory exhaust        


Que- The number of the threads in the pool can be decided on factors such as : 

a. number of CPUs in the system 

b. amount of physical memory 

c. expected number of concurrent client requests 

d. all of the mentioned  


Answer- all of the mentioned         


Que- Because of virtual memory, the memory can be shared among 

a. processes 

b. threads 

c. instructions 

d. none of the mentioned  


Answer- processes        


Que- _____ is the concept in which a process is copied into main memory from the secondary memory according to the requirement. 

a. Paging 

b. Demand paging 

c. Segmentation 

d. Swapping  


Answer- Demand paging        


Que- The pager concerns with the 

a. individual page of a process 

b. entire process 

c. entire thread 

d. first page of a process  


Answer- individual page of a process        


Que- Swap space exists in 

a. primary memory 

b. secondary memory 

c. cpu 

d. none of the mentioned  


Answer- secondary memory        


Que- When a program tries to access a page that is mapped in address space but not loaded in physical memory, then 

a. segmentation fault occurs 

b. fatal error occurs 

c. page fault occurs 

d. no error occurs  


Answer- page fault occurs        


Que- Effective access time is directly proportional to 

a. page-fault rate 

b. hit ratio 

c. memory access time 

d. none of the mentioned  


Answer- page-fault rate        


Que- In FIFO page replacement algorithm, when a page must be replaced 

a. oldest page is chosen 

b. newest page is chosen 

c. random page is chosen 

d. none of the mentioned  


Answer- oldest page is chosen        


Que- Which algorithm chooses the page that has not been used for the longest period of time whenever the page required to be replaced? 

a. first in first out algorithm 

b. additional reference bit algorithm 

c. least recently used algorithm 

d. counting based page replacement algorithm  


Answer- least recently used algorithm        


Que- A process is thrashing if 

a. it is spending more time paging than executing 

b. it is spending less time paging than executing 

c. page fault occurs 

d. swapping can not take place  


Answer- it is spending more time paging than executing        


Que- Working set model for page replacement is based on the assumption of 

a. modularity 

b. locality 

c. globalization 

d. random access  


Answer- locality        


Que- Virtual memory allows : 

a. execution of a process that may not be completely in memory 

b. a program to be smaller than the physical memory 

c. a program to be larger than the secondary storage 

d. execution of a process without being in physical memory 


Answer- execution of a process that may not be completely in memory        


Que- The instruction being executed, must be in : 

a. physical memory 

b. logical memory 

c. physical & logical memory 

d. none of the mentioned 


Answer- physical memory        


Que- Error handler codes, to handle unusual errors are : 

a. almost never executed 

b. executed very often 

c. executed periodically 

d. none of the mentioned 


Answer- almost never executed        


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