Impact of Next-Generation I/O Architectures on the Design and Performance of Network Servers

The increasing demand for scalable and highly-available network services has challenged computer architects to develop new I/O architecture for servers. The recently released InfiniBand industry standard, for instance, provides scalable bandwidth and protected I/O communication using the memory-mapped communication model and a channelbased switched fabric technology. Advanced device controllers incorporate processor and memory and can execute sophisticated I/O protocols locally. While accommodating the new I/O architecture within the traditional software framework is straightforward, there is little if any research to explore the server designs that are enabled by the new I/O architecture and their performance impact. This paper uses modeling and simulation to investigate the designperformance space for network servers in the presence of I/O switches, such as InfiniBand, and programmable devices. We propose and analyze a range of scenarios starting from providing conventional servers with high I/O bandwidth, to modifying servers to exploit user-level I/O and direct device-to-device communication, to re-designing the operating system to offload file system and networking functions from the host to programmable devices. I