In recent years much attention has been given to providing the proportional delay differentiation through the packet scheduling. The issue of the performance of the scheduling algorithms also increases in importance when the line speed increases significantly as a result of the optical technology. In this paper we propose an efficient packet scheduling scheme modified from the dynamic deficit round-robin (DDRR) scheduling algorithm. The new scheme not only provides the network administrator with the tuning knob for adjusting the relative QoS in the packet delay, but also performs scheduling at O(1) complexity and with very small overhead. Simulation results show the effectiveness of the modified algorithm. The new scheme can be an efficient alternative in providing the proportional delay differentiation.