List Of Important OS Interview Questions Part – 2
1.What is cycle stealing?
We encounter cycle stealing in the context of Direct Memory Access (DMA). Either the DMA controller can use the data bus when the CPU does not need it,or it may force the CPU to temporarily suspend operation. The latter technique is called cycle stealing. Note that cycle stealing can be done only at specific break points in an instruction cycle.
2.What is Marshalling?
The process of packaging and sending interface method parameters across thread or process boundaries.
3.What is a daemon?
Daemon is a program that runs in the background without user’s interaction. A daemon runs in a multitasking operating system like UNIX. A daemon is initiated and controlled by special programs known as ‘processes’.
4.What is pre-emptive and non-preemptive scheduling?
Preemptive scheduling:
The preemptive scheduling is prioritized. The highest priority process should always be the process that is currently utilized.
Non-Preemptive scheduling:
When a process enters the state of running,the state of that process is not deleted from the scheduler until it finishes its service time.
5.What is busy waiting?
The repeated execution of a loop of code while waiting for an event to occur is called busy-waiting. The CPU is not engaged in any real productive activity during this period,and the process does not progress toward completion.
6.What is page cannibalizing?
Page swapping or page replacements are called page cannibalizing.
7.What is SMP?
To achieve maximum efficiency and reliability a mode of operation known as symmetric multiprocessing is used. In essence,with SMP any process or threads can be assigned to any processor.
8.What is process migration?
It is the transfer of sufficient amount of the state of process from one machine to the target machine.
9.Difference between Primary storage and secondary storage?
Primary memory is the main memory (Hard disk,RAM) where the operating system resides.
Secondary memory can be external devices like CD,floppy magnetic discs etc. secondary storage cannot be directly accessed by the CPU and is also external memory storage.
10.Define compaction’s.
Compaction is a process in which the free space is collected in a large memory chunk to make some space available for processes.
11.What are residence monitors?
Early operating systems were called residence monitors.
12.What is dual-mode operation?
In order to protect the operating systems and the system programs from the malfunctioning programs the two mode operations were evolved
System mode
User mode.
13.What is a device queue?
A list of processes waiting for a particular I/O device is called device queue.
14.What are the different types of Real-Time Scheduling?
Hard real-time systems required to complete a critical task within a guaranteed amount of time.
Soft real-time computing requires that critical processes receive priority over less fortunate ones.
15.What is relative path and absolute path?
Absolute path– Exact path from root directory.
Relative path– Relative to the current path.
16.What are the disadvantages of context switching?
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.
17.What is a data register and address register?
Data registers –
can be assigned to a variety of functions by the programmer. They can be used with any machine instruction that performs operations on data.
Address registers –
contain main memory addresses of data and instructions or they contain a portion of the address that is used in the calculation of the complete addresses.
18.What is DRAM?
Dynamic Ram stores the data in the form of Capacitance,and Static RAM stores the data in Voltages.
19.What are local and global page replacements?
Local replacement means that an incoming page is brought in only to the relevant process’ address space. Global replacement policy allows any page frame from any process to be replaced. The latter is applicable to variable partitions model only.
20.Explain the concept of the batched operating systems?
In batched operating system the users gives their jobs to the operator who sorts the programs according to their requirements and executes them. This is time consuming but makes the CPU busy all the time.
21.What is SCSI?
SCSI – Small computer systems interface is a type of interface used for computer components such as hard drives,optical drives,scanners and tape drives. It is a competing technology to standard IDE (Integrated Drive Electronics).
22.When is a system in safe state?
The set of dispatchable processes is in a safe state if there exists at least one temporal order in which all processes can be run to completion without resulting in a deadlock.
23.What is cycle stealing?
We encounter cycle stealing in the context of Direct Memory Access (DMA). Either the DMA controller can use the data bus when the CPU does not need it,or it may force the CPU to temporarily suspend operation.
The latter technique is called cycle stealing. Note that cycle stealing can be done only at specific break points in an instruction cycle.
24.What is an idle thread?
The special thread a dispatcher will execute when no ready thread is found.
25.What is FtDisk?
It is a fault tolerance disk driver for Windows NT.
26.What is Dispatcher?
Dispatcher module gives control of the CPU to the process selected by the short-term scheduler; this involves: Switching context,Switching to user mode,Jumping to the proper location in the user program to restart that program,dispatch latency – time it takes for the dispatcher to stop one process and start another running.
27.When does the condition ‘rendezvous’ arise?
In message passing,it is the condition in which,both,the sender and receiver are blocked until the message is delivered.
28.What is process spawning?
When the OS at the explicit request of another process creates a process,this action is called process spawning
29.What are the reasons for process suspension?
1) swapping 2) interactive user request 3) timing 4) parent process request
30.What are the sub-components of I/O manager in Windows NT?
1) Network redirector/ Server 2) Cache manager. 3) File systems 4) Network driver 5) Device driver