A scalable, low-latency, high-speed, and energy-efficient datacenter network represents a key element in the deployment of cloud-oriented large-scale datacenters. Photonic switch (PS) architectures can be a solution due to the inherent benefits of optical technology. In this study, we numerically investigate the performance of a packet-switched optical network (PSON) architecture with centralized control for datacenter interconnection. To achieve high performance of PSON, an intelligent yet low-complexity scheduling algorithm is critical. It is also beneficial to take traffic flow features into consideration. Thus, we propose and investigate the characteristics of a priority-aware scheduling algorithm for PSON, considering both architecture features and traffic-flow characteristics in datacenter. Numerical simulations show the advantages of the priority-aware algorithm.