ETHOM, an Ethernet over SCI and DX Driver for Linux

Nowadays, high computing demands are often tackled by clusters of computers, each of which is basically an assembly of a growing number of CPU cores and main memory; these nodes are connected by some kind of communication network. With the growing speed and number of CPU cores, the network becomes a severe bottleneck limiting overall cluster performance. High-speed interconnects like SCI and Dolphin DX are good for alleviating this communication bottleneck, when the communication software is either based on IP or specifically adapted to the interconnect. Software written to communicate directly via Ethernet frames can not be used this way, though. In this article, we present ETHOM, a driver that implements an Ethernet interface on top of the Dolphin Express software stack. It enables the Dolphin networks SCI and DX to be used as high-speed replacement for Ethernet. Offering an Ethernet and with that an IP interface, it enhances their functionality and allows usage of layer-2 kernel functionality like interface bonding and bridging. This driver is an improvement of ETHOS, the Ethernet over Sockets driver, delivering lower latencies at the cost of higher CPU load. By means of various measurements, we show that ETHOM with SCI or DX offers a twofold increase in communication performance over Gigabit Ethernet.