Interfacing Java with the Virtual Interface Architecture

Abstract

User-level network interfaces (UNIs) have reduced the overheads of communication by exposing the buffers used by the network interface DMA engine to the applications. This removes the kernel from the critical path of message transmission and reception, and it reduces the number of data copies performed on that path. Unfortunately, the fact that UNIs require the application to manage buffers explicitly makes it difficult to provide direct access to a UNI from Java, as the language explicitly prevents programs from controlling the location or layout of objects. This paper describes Javia, a Java interface to the Virtual Interface Architecture (VIA), an emerging UNI standard in the industry. Javia implements a special buffer abstraction that allows Java programs to allocate arrays in pinned memory and use them as communication buffers without copy. The location and lifetime of these arrays are controlled through small modifications to the garbage collector. Simple experiments show that Java programs can achieve round-trip times of 21us for small messages and bandwidths of 95Mbytes/sec for 4Kbyte messages.