申論題

3. A computer whose proces esses have 2048 pages in their acldress spaces keeps its page tables in memory. The overhead required for reuding a w word from the pige table is 600 nsec. To reduce this overhead, the computer has a TLB, which holds 64 (page. frame) pairs and can do a lookup in 100 nsee. What hil rate is needed to reduce the mean overhead to 200 nsee or less