Design of a VIA based communication protocol for LAM/MPI suite

The increasing use of System Area Network (SAN) demands efficient communication to benefit SAN features through a direct access to network resources and avoiding kernel intervention in communication path. Recently, a consortium composed by Microsoft, Compaq and Intel authored a new standard, the Virtual Interface Architecture (VIA), designed to reduce software overhead in data transfers. This paper describes the communication protocol proposed in order to allow a complete implementation of MPI based on VIA. This protocol is needed because the plain use of the two VIA data transfer models does not allow the implementation of MPI based on VIA, due to the large number of MPI communication flavors. To validate the goodness of the proposed protocol, a new communication layer based on VIA has been introduced in the LAM/MPI suite. The reported results, referring to a software VIA implementation for fast Ethernet networks, exhibits a significant reduction in latency time of LAM/MPI based on VIA with respect to the same library based on the TCP/IP protocol.