Mean of an additive arithmetic function ($A_f(x)$)

For an additive arithmetic function, the model mean is $A_f(x)={\sum }_{p^k\le x}f(p^k)(1-1/p)/p^k$. The exact uniform expectation differs by $O(x^{-1}{\sum }_{p^k\le x}|f(p^k)|)$.