We study the linear differential equation (P ): y (x) + f (x)y(x) = 0, on I = (0, 1), where the coefficient f (x) is strictly positive and continuous on I , and satisfies the Hartman-Wintner condition at x = 0. The four main results of the paper are: (i) a criterion for rectifiable oscillations of (P ), characterized by the integrability of 4 √ f (x) on I ; (ii) a stability result for rectifiable and unrectifiable oscillations of (P ), in terms of a perturbation on f (x); (iii) the s-dimensional fractal oscillations (for which we assume also f (x) ∼ cx −α when x → 0, α > 2, and s = max{1, 3/2 − 2/α}); and (iv) the co-existence of rectifiable and unrectifiable oscillations in the absence of the Hartman-Wintner condition on f (x). Explicit examples related to the above results are given.