Question

What are the advantages and Disadvantages of Swapping of memory management in operating system

Answer 1

Advantages :

• Allocating memory is easy and cheap

• Any free page is ok, OS can take first one out of list it keeps

• Eliminates external fragmentation

• Data (page frames) can be scattered all over PM

• Pages are mapped appropriately anyway

• Allows demand paging and prepaging

• More efficient swapping

• No need for considerations about fragmentation

• Just swap out page least likely to be used

Disadvantages :

• Longer memory access times (page table lookup)

• Can be improved using TLB

• Guarded page tables

• Inverted page tables

• Memory requirements (one entry per VM page)

• Improve using Multilevel page tables and variable page sizes (super-pages)

• Guarded page tables

• Page Table Length Register (PTLR) to limit virtual memory size

• Internal fragmentation