In a paging system, it takes 30 ns to search translation Look-a-side Buffer…

Solution:

• Given: TLB search time = 30 ns, main memory access time = 90 ns, TLB hit ratio = 70% (0.7).

• If TLB hit: time = TLB search + memory access = 30 ns + 90 ns = 120 ns.

• If TLB miss: need to access page table in memory and then the data in memory, so time = TLB search + page-table memory access + data memory access = 30 ns + 90 ns + 90 ns = 210 ns.

• Effective memory access time (EAT) = (hit ratio) * (hit time) + (miss ratio) * (miss time) = 0.7 * 120 ns + 0.3 * 210 ns = 84 ns + 63 ns = 147 ns.

Effective memory access time = 147 ns.