Question

Please assist with below: Please label answer with number. Also, please draw diagram as indicated for 3.1

#3:

3.1)   Draw a diagram showing how addresses are translated on a virtual memory system

3.2) Explain temporal locality and how it is used in memory paging systems.

3.3) Explain what a stub is

3.4) Explain external fragmentation

3.5) Explain internal fragmentation

Answer 1

3.1)

3.2)
Temporal locality is a concept of accessing same memory in near future.
When a memory block is accessed, it is more likely that it will be accessed again soon.
This concept is known as temporal locality.

It is used in paging system by keeping the pages in main memory until there is a need to replace that page.
i.e Once a page is accessed, it is kept inside main memory.
so that in near future it can be accessed again from main memory.

3.3)
Stub is a small routine that can substitute long program.
When There is a page fault, stub replaces itself with memory address of routine.
while the page is brought to the main memory, stub is being executed.

3.4)
Externam fragmentation :
When memory is divided into partitions, at runtime it is allocated depending on demands and availability of memory.
External fragmentation is free blocks in memory that can be allocated to other memory but those are too small to be allocated.
This happens when variable size memroy space are allocated to processes dynamically .

3.5)
Internal fragmentation :
When process is too small to fit into a block then there are free space in block.
This free space can not be used by other processes as block is assigned to some process.
This happenes when fixed partitioning is used for memory.