Solution

Data:

TLB hit ratio = p = 0.8

TLB access time = 15 nanoseconds

Memory access time = m = 150 milliseconds

Formula:

EMAT = p × (t + m) + (1 – p) × (t + m + m)

Calculation:

EMAT = 0.8 × (15 + 150) + (1 – 0.8) × (15 + 150 + 150)

EMAT = 195 nanoseconds.

Important points:

During TLB hit

Frame number is fetched from the TLB (15 ms)

and page is fetched from physical memory (150 ms)

During TLB miss

TLB no entry matches (15 ms)

Frame number is fetched from the physical memory (150 ms)

and pages are fetched from physical memory (150 ms)