Define Demand Paging, Page fault interrupt and Trashing?
Demand Paging: Demand paging is the paging policy that a page is not read into memory until it is requested, that is, until there is a page fault on the page.
Page fault interrupt: A page fault interrupt occurs when a memory reference is made to a page that is not in memory. The present bit in the page table entry will be found to be off by the virtual memory hardware and it will signal an interrupt.
Trashing: The problem of many page faults occurring in a short time, called ?page thrashing,?
What is starvation and aging?
Starvation: Starvation is a resource management problem where a process does not get the resources it needs for a long time because the resources are being allocated to other processes.
Aging: Aging is a technique to avoid starvation in a scheduling system. It works by adding an aging factor to the priority of each request. The aging factor must increase the request?s priority as time passes and must ensure that a request will eventually be the highest priority request (after it has waited long enough)
Starvation:
Beb resource scheduling.
E.g:
we have three processes and one resource, p1 and p2 use this resource one by one (contineously)
and p3 wait for this resource (contineously).