Correct Answer: Time taken for switching from one process to other is pure over head Because the system does no useful work while switching So one of the solutions is to go for threading when ever possible
Correct Answer: Also called FIFO anomaly Usually, on increasing the number of frames allocated to a process virtual memory, the process execution is faster, because fewer page faults occur Sometimes, the reverse happens, ie, the execution time increases even when more frames are allocated to the process This is Belady's Anomaly This is true for certain page reference patterns
5. What is the cause of thrashing? How does the system detect thrashing? Once it detects thrashing, what can the system do to eliminate this problem?
Correct Answer: Thrashing is caused by under allocation of the minimum number of pages required by a process, forcing it to continuously page fault The system can detect thrashing by evaluating the level of CPU utilization as compared to the level of multiprogramming It can be eliminated by reducing the level of multiprogramming
6. What resources are used when a thread is created? How do they differ from those when a process is created?
Correct Answer: When a thread is created the threads does not require any new resources to execute the thread shares the resources like memory of the process to which they belong to The benefit of code sharing is that it allows an application to have several different threads of activity all within the same address space Whereas if a new process creation is very heavyweight because it always requires new address space to be created and even if they share the memory then the inter process communication is expensive when compared to the communication between the threads
7. When designing the file structure for an operating system, what attributes are considered ?
Correct Answer: Commonly, the different attributes for a file structure are naming,size, identifier, a level of protection, supported file types and location for the files
8. The main interface in Windows and OS X is __________ interface.
Correct Answer: User data: Modifiable part of user space May include program data, user stack area, and programs that may be modified User program: The instructions to be executed System Stack: Each process has one or more LIFO stacks associated with it Used to store parameters and calling addresses for procedure and system calls Process control Block (PCB): Info needed by the OS to control processes