申論題

3.In virtual-memory management, demand paging plays an important role.

(c) Suppose that you design demand paging for an operating system. Assume that the memory-access time is 200 nanoseconds and the average page-fault time is 75 microseconds. If you want the effective access time for demand paging no larger than 230 nanoseconds, what will be the expected page-fault rate? You need to give your calculation.