A trace driven study of the effectiveness of cache mechanism for network processors

Network processor (NP) is a new breed of packet forwarding engine that is designed to meet the simultaneous demands of high speed and great flexibility of today's network equipments. Cache mechanism has attracted more and more attentions in the field of NP design because of its big success in terms of latency hiding. In this paper, we evaluate the effectiveness of cache mechanism for NP under the new context of packet forwarding using real-life packet traces. Our results suggest that caching can reduce the packet loss rate to an extremely low level under reasonable hit rate and packet buffer size. However, the possibility of incurring large queuing delay makes it unsuitable for applications demanding stringent quality of service (QoS) enforcement. Furthermore, we also show that the combination of cache mechanism with multithreading will be a promising way because of the dramatically decreased both queuing and processing delay, in addition to the even lower packet loss rate.