Set - 3

Question 1 :

What is the main goal of the Memory Management?

Answer :

It decides which process should reside in the main memory, Manages the parts of the virtual address space of a process which is non-core resident, Monitors the available main memory and periodically write the processes into the swap device to provide more processes fit in the main memory simultaneously.

Question 2 :

What is a Map?

Answer :

A Map is an Array, which contains the addresses of the free space in the swap device that are allocatable resources, and the number of the resource units available there.
This allows First-Fit allocation of contiguous blocks of a resource. Initially the Map contains one entry – address (block offset from the starting of the swap area) and the total number of resources. Kernel treats each unit of Map as a group of disk blocks. On the allocation and freeing of the resources Kernel updates the Map for accurate information.

Question 3 :

What scheme does the Kernel in Unix System V follow while choosing a swap device among the multiple swap devices?

Answer :

Kernel follows Round Robin scheme choosing a swap device among the multiple swap devices in Unix System V.

Question 4 :

What is a Region?

Answer :

A Region is a continuous area of a process's address space (such as text, data and stack). The kernel in a 'Region Table' that is local to the process maintains region. Regions are sharable among the process.

Question 5 :

What are the events done by the Kernel after a process is being swapped out from the main memory?

Answer :

When Kernel swaps the process out of the primary memory, it performs the following:
Kernel decrements the Reference Count of each region of the process. If the reference count becomes zero, swaps the region out of the main memory,
Kernel allocates the space for the swapping process in the swap device,
Kernel locks the other swapping process while the current swapping operation is going on,
The Kernel saves the swap address of the region in the region table.