User Customization of Virtual Network Interfaces with U-Net/SLE David Opp enheimer and Matt Welsh fdavidopp,
[email protected] Decemb er 9, 1997 Abstract We describ e U-Net/SLE Safe Language Extensions, a user-level network interface architecture which enables p er-application customization of communication semantics through downloading of user extension applets, imple- mented as Java class les, into the network interface. This architecture p ermits application s to safely sp ecify co de to b e executed within the NI on message transmission and reception. By leveraging the existing U-Net mo del, applications may implement proto col co de at the user level, within the NI, or using some combination of the two. Our current implementation, using the Myricom Myrinet interface and a small Java Virtual Machine subset, obtains go o d p erformance, allowing host communication overhead to b e reduced and improving the overlap of communication and computation during proto col pro cessing. 1 Intro duction Recentwork in high-sp eed interconnects for distributed and parallel computing architectures, particularly workstation clusters, has fo cused on developmentofnetwork interfaces enabling low-latency and high-bandwidth communication. Often, these systems bypass the op erating system kernel to achieve high p erformance; however the features and functionality provided by these di erent systems vary widely. Several systems, such as U-Net [26] and Active Messages [27], virtualize the network interface to provide multiple applications on the same host with direct, protected network access. Other systems, including Fast Messages [16] and BIP [17], eschew sharing the network in lieu of design simplicity and high p erformance.