POF交换机查表预处理性能优化方法

An Optimization Method for POF Switch Table Lookup Pre-processing Performance

协议无感知转发技术的出现使软件定义网络数据面的可编程能力和可扩展性得到了进一步增强,已有的工作聚焦于匹配动作表的查询优化,包括查表算法的优化和整体流程的加速等。但在基于多级匹配动作表设计的数据包转发流水线中,查表前数据包匹配域字段的提取工作会消耗较多的时间,在匹配域复杂的场景下甚至与查表时间相当,这成为了降低交换机转发延迟的瓶颈。为了解决上述问题,我们在POF软件交换机中使用单指令多数据流技术对查表预处理阶段的查表关键字提取流程进行加速。实验结果表明,加速方案使交换机的平均转发延迟降低了12%-38%。

The emergence of protocol-oblivious forwarding has further enhanced the programmability and scalability of SDN data planes.Existing work has focused on match-action table searching,including optimization of searching algorithms and acceleration of the searching process.However,in the packet-forwarding pipeline designed based on multi-level match-action tables,the extraction of packet matching fields consumes much time which is even comparable to the table lookup time when the matching fields are complex,which becomes a bottleneck to reduce the forwarding latency of the switch.To solve the above problem,we use SIMD instructions in the software POF switch to accelerate the keyword extraction in the table lookup pre-processing stage.The experiment results show that the acceleration scheme reduces the average forwarding latency of the switch by 12%-38%.