Achieving 10Gbps network processing: are we there yet?

Scaling TCP/IP receive side processing to 10Gbps speeds on commercialserver platforms has been a major challenge. This led to the development oftwo key techniques: Large Receive Offload (LRO) and Direct Cache Access(DCA). Only recently, systems supporting these two techniques have becomeavailable. So, we want to evaluate these two techniques using 10Gigabit NICs tofind out if we can finally get 10Gbps rates. We evaluate these two techniques indetail to understand performance benefit offered by these two techniques and theremaining major overheads. Our measurements showed that LRO and DCA togetherimprove TCP/IP receive performance by more than 50% over the base case(no LRO and DCA). These two techniques combined with the improvements inthe CPU architecture and the rest of the platform over the last 3-4 years have morethan doubled the TCP/IP receive processing throughput to 7Gbps. Our detailedarchitectural characterization of TCP/IP processing, with these two features enabled,has revealed that buffer management and copy operations still take up significantamount of processing time. We also analyze the scaling behavior ofTCP/IP to figure out how multi-core architectures improve network processing.This part of our analysis has highlighted some limiting factors that need to be addressedto achieve scaling beyond 10Gbps.