Performance Aspects of Data Transfer in a New Networked I/O Architecture

We present performance results of a new distributed I/O software architecture to support remote applications interacting with local I/O devices. The architecture emphasizes network transparency and ease of customization/extensibility in support of the vastly different needs of various applications and devices that can benefit from remote I/O. Networked I/O is achieved via a networked device driver that is split into two parts, one on each side of the network. An I/O stream that is sourced at one end and sinked at the other may be modified by a set of pipelined transformation modules. Each module comes in a pair, one on each side of the network, with one side typically applying some operation and the other side applying a corresponding one, such as encoding and decoding the format of the data or pausing and resuming the sending of messages. Because of the paired nature of transformation modules, the system is capable of supporting the modification of the I/O stream in a variety of ways to compensate for network issues, one of the key problems of remote I/O, while remaining transparent to the application. We show that even with an implementation that operates almost entirely at user level (i.e., outside the operating system), good levels of performance that are adequate for even high intensity I/O, both in terms of efficiency and throughput, can be achieved.