Design of a bitmap-based QoS-aware memory controller for a packet memory

A packet memory controller in routers accesses the packet memory according to the QoS requirements of packets. The previous QoS-aware controller using a feedback control loop degenerates into round robin scheduling under temporary overload and suffers from slow response. We propose a new packet memory controller that estimates input load accurately and rapidly and schedules different classes using a flexible bitmap scheduler. The results show that under temporary overload or rapidly changing input loads, it can successfully meet the latency requirements by showing only less than 2% difference from the requirement of the high priority class.