Server Network Scalability and TCP Offload

Server network performance is increasingly dominated by poorly scaling operations such as I/O bus crossings, cache misses and interrupts. Their overhead prevents performance from scaling even with increased CPU, link or I/O bus bandwidths. These operations can be reduced by redesigning the host/adapter interface to exploit additional processing on the adapter. Offloading processing to the adapter is beneficial not only because it allows more cycles to be applied but also of the changes it enables in the host/adapter interface. As opposed to other approaches such as RDMA, TCP offload provides benefits without requiring changes to either the transport protocol or API.

We have designed a new host/adapter interface that exploits offloaded processing to reduce poorly scaling operations. We have implemented a prototype of the design including both host and adapter software components. Experimental evaluation with simple network benchmarks indicates our design significantly reduces I/O bus crossings and holds promise to reduce other poorly scaling operations as well.