Test: Swap Space - Computer Science Engineering (CSE) MCQ

Swapping
Swapping is a memory management scheme in which a process can be swapped temporarily out of the main memory (or move) to secondary storage (disk) and make that memory available to other processes. At some later time, the system swaps back the process from the secondary storage to the main memory.

• Memory management is the functionality of an operating system which handles or manages primary memory and moves processes back and forth between main memory and disk during execution.
• Swapping is a mechanism in which a process can be swapped temporarily out of main memory (or move) to secondary storage (disk) and make that memory available to other processes.

Concept:
Swapping is a memory management technique used in multi-programming to increase the number of process sharing the CPU. It is a technique of removing a process from main memory and storing it into secondary memory, and then bringing it back into main memory for continued execution. This action of moving a process out from main memory to secondary memory is called Swap Out and the action of moving a process out from secondary memory to main memory is called Swap In.

Swap-Space:
The area on the disk where the swapped out processes are stored is called swap space.

Concept:
Swap space is the area on a hard disk that is part of the Virtual Memory of one's machine, which is a combination of accessible physical memory (RAM) and the swap space.

Swap space is used in various ways by different operating systems, depending on the memory management algorithms in use. Systems that implement swapping may use swap space to hold an entire process image, including the code and data segments.
Swap space can reside in one of two places: it can be carved out of the normal file system or it can be in a separate disk partition.
Swap space is used to save the process data. Operating system that offers virtual memory commonly use the mapping interface for kernel services. For instance, to execute program, the operating system maps the executable into memory and then transfers control to the entry address of the executable. The mapping interface is commonly used for kernel access to swap space on disk.

NOTE:
Option (B) is the best possible answer. 

Disk access is much slower than memory access.

Putting these swap spaces on separate disks reduces the load places on the I/O system.