A Portable and Adaptative Multi-protocol Communication Library for Multithreaded Runtime Systems

This paper introduces Madeleine II , an adaptive multiprotocol extension of the Madeleine portable communication interface. Madeleine II provides facilities to use multiple network protocols (VIA, SCI, TCP, MPI) and multiple network adapters (Ethernet, Myrinet, SCI) within the same application. Moreover, it can dynamically select the most appropriate transfer method for a given network protocol according to various parameters such as data size or responsiveness user requirements. We report performance results obtained using Fast-Ethernet and SCI. 1 EÆcient Communication in Multithreaded Environments Due to their ever-growing success in the development of distributed applications on clusters of SMP machines, today's multithreaded environments have to be highly portable and eÆcient on a large variety of architectures. For portability reasons, most of these environments are built on top of widespread messagepassing communication interfaces such as PVM or MPI. However, the implementation of multithreaded environments mainly involvesRPC-like interactions. This is obviously true for environments providing a RPC-based programming model such as Nexus [2] or PM2 [4], but also for others which often provide functionalities that can be eÆciently implemented by RPC operations. We have shown in [1] that message passing interfaces such as MPI, do not meet the needs of RPC-based multithreaded environments with respect to efciency. Therefore, we have proposed a portable and eÆcient communication interface, called Madeleine, which was speci cally designed to provide RPCbased multithreaded environments with both transparent and highly eÆcient communication. However, the internals of this rst implementation were strongly message-passing oriented. Consequently, the support of non message-passing network protocols such as SCI or even VIA was cumbersome and introduced some unnecessary overhead. In addition, no provision was made to use multiple network protocols within the same application. For these reasons, we decided to design Madeleine II , a full multi-protocol version of Madeleine, eÆciently portable on a wider range of network protocols, including non message-passing ones. ? LIP, ENS Lyon, 46, All ee d'Italie, F-69364 Lyon Cedex 07, France. Contact: [email protected]. mad begin packing Initiates a new message mad begin unpacking Initiates a message reception mad end packing Finalize an emission mad end unpacking Finalize a reception mad pack Packs a data block mad unpack Unpacks a data block Table 1. Functional interface of Madeleine II . 2 The Madeleine II Multi-Protocol Communication