Importance of Coherence Protocols with Network Applications on Multicore Processors

As Internet and information technology have continued developing, the necessity for fast packet processing in computer networks has also grown in importance. All emerging network applications require deep packet classification as well as security-related processing and they should be run at line rates. Hence, network speed and the complexity of network applications will continue increasing and future network processors should simultaneously meet two requirements: high performance and high programmability. We will show that the performance of single processors will not be sufficient to support future demands. Instead, we will have to turn to multicore processors, which can exploit the parallelism in network workloads. In this paper, we focus on the cache coherence protocols which are central to the design of multicore-based network processors. We investigate the effects of two main categories of various cache coherence protocols with several network workloads on multicore processors. Our simulation results show that token protocols have a significantly higher performance than directory protocols. With an 8-core configuration, token protocols improves the performance compared to directory protocols by a factor of nearly 4 on average.