Page replacement algorithms have to make decisions about what pages to evict when a system does not have enough free pages to handle the current page fault rate.

1.) Why might we consider a page replacement algorithm to have made a bad decision about an eviction ?

2.) Generally page replacement algorithms do not try and evict pages that have been modified since they were last brought into memory. Explain why this is so.

3.) If the OPT algorithm is so good at figuring out the minimum number of page faults we could have in a system under a certain load, why dont we just implement the OPT algorithm as the page replacement algorithm for an operating system ?

4.) Most systems implement some variation of the LRU algorithm to do page replacement. Briefly explain how the LRU algorithm works, and why it is so successful.