# Effective Access Time

## Suppose:

- TLB lookup takes 5 nano sec.
- Memory access time is 100 nano sec.
- Hit ratio (probability to find page number in TLB) is ?

##

Effective Access Time = (5+100)* ? +( 5+100+100)*(1- ?)

Suppose ? = 80% (for example, TLB size = 16)

## EAT = 105*.8 + 205*.2 = 125 nano sec.

Suppose ? = 98% (for example, TLB size = 64)

## EAT = 105*.98 + 205*.02 = 107 nano sec.