Performance Evaluation of a QoS-Aware Mechanism for Polling-Based High-Speed Network Interfaces

The explosive growth of the high-speed multimedia networks and the widespread use of web-based related applications place new demands on the network servers. The network end systems such as PC-Router, network server and host connected to high speed links must satisfy QoS requirements for multimedia traffics such as delay and loss ratio. Most works on operating systems support for high-speed network interface have focused in increasing the throughput and decreasing the interrupt handing overhead. However, the problem is that not all traffic streams are equal in terms of QoS requirements. Multimedia applications often depend more on low-latency than on high throughput. This study first compares the performance measures of hard timer and soft timer polling schemes used for high-speed network interface with high traffic load. Then it modifies the polling-based interrupt handling for high-speed network to not just eliminate the interrupt overhead but also to guarantee the QoS requirements for multimedia traffic. Meanly we propose an input network interface mechanism, which combines the advantages of using polling interrupt handling under high traffic load and using multi-priority queues scheduling algorithm to provide the QoS requirements. In addition to the throughput performance metric in which most of the literatures focus on only, other performance metrics such as CPU availability, loss ratio, packet delay are defined and studied. The performance evaluations, which are performed using a discrete event simulation, indicate that under conditions of high traffic load, the proposed system offers increased throughput and reduced latency for real time traffics.