Question

1. We have learnt that CPU can run a process only when it is in main memory and not secondary memory. I have 4 process in man memory referred to as 0,1,2,3,4,5. The CPU has to execute process 4 and 5 but these process are in the secondary memory and this can be possible using page replacement algorithm , In your own words what is ? a. page hit b. page miss C. page fault and d. What is the cause page fault?

Answer 1

1 a) Page hit is the event when the page that CPU wants to execute is found in the main memory while execution and does not require any transfer from secondary to main memory. In the given scenario in question when page 0,1,2 and 3 are in main memory. When CPU will look for page 0,1,2 or 3 that will result in page hit.

b) Page miss is the event when the page that CPU wants to execute is not found in the main memory while execution. Those pages are in secondary memory and needs to be brought in main memory by using the page replacement algorithms. In the given scenario in question where 0,1,2 and 3 are in main memory and 4,5 are in secondary memory. When CPU will look for pages 4 or 5 in main memory, it will result in page miss.

c) Page fault is another name for page miss. One can say, Page fault is a result of page miss and vice versa.

d) The cause of page fault is when the CPU tries to access a page which is currently not in the physical memory and is present in the secondary memory. Page fault will occur when CPU will try access page 4 or 5 which is not in the main memory.