Multilevel paging

Question

Doubt

In multi level paging Is it required that  all the pages of the page table should be in main memory like inner page table and outer page table should be in main memory or either by loading only outer page table we can run the process if any inner page table page required it generate a trap(page fault )and that inner page will put into the main memory by os ?

Answer 1

Ultimatly our goal is to maximize CPU utilization but when we have a long process then its page table is too big that if we store entire page table in main memory then it reduces Utilization . So to overcome with this we apply paging on page table also.  

When we have a page reference we index for this on outer page table and then find out the address of inner page table . We then Go and fatch to related pAGE TABLE and addresss translation takes place .

NOTE :  ADDRESS STORED IN OUTER PAGE TABLE ARE OF SIZE OF MAIN MEMORY .ADDRESS.

Ex: if main memory required 16 bit  then each entry requires  to store 16 bit data .

Comments

Thankyou for answering,means outer page table always present in main memory but inner page table may or may not be present in main memory it all depend upon page table size.