Introduction to Seminar Topic on Virtual Memory:
This is the memory that is illusion to the user. This memory is larger than the system memory or real memory. This memory is used when non-continuous memory allocation is done. This memory has different parts used for different purpose like memory management; it is used to create page information. Different terms are used in the page entry like valid bit for checking page exists in the memory or not. Page frame is used for locating page in the memory. Prot info is used for protecting the page. Modified is used for checking whether the page is modified or not. Ref info is used for referencing the page after loading in the memory.
When the traffic of the page is increased and the CPU efficiency is low then this condition is called thrashing. This happens when the page is operated in the fault zone. Page hardware has three operations. First: it translates the page information and detects the page faults. Secondly: it must provide the security to the pages so that one page should not be able to use the other pages.
Third: it must set the modify bit when we want to perform the operation on the page and must set the reference bit when we doing referencing to the page. If in case one of the memories doesn’t exist in the memory then the chance of the page fault arises. They may in balance the input output operation.
We must load the required page in the memory when the page fault occurs. This operation is done VM handler. It replaces the page when required. In case of page fault kernel of the operating system switches the CPU to do another work or it paused for the next time.
Download Seminar Report on Virtual Memory .