SAN(System Area Network)within cluster brings high bandwidths and low latencies to IPC(Inter-Process Communication). However,the communication performance has not been able to makefull use of these hardware improvements due to many software overheads. To address this problem,In-tel Corporation,Compaq Computer Corporation, and Microsoft Corporation jointly authored the VIA (Virtual Interface Architecture)specification.As an industrial standard of ULN(User-Level Networking),Ⅵ Architecture defines a set of data operations for message passing, to achieve high-bandwidth, low-latency communication between any couple nodes within cluster ,as well as minimize CPU cycles. VIA gives direct access to network inter-face,bypasses operating system in memory region protected mode ,avoid copies of data during message passing ,and avoid interrupts and context switches if possible.This article describes the principles and mechanism of the Ⅵ Architecture and THVIA.
In this article,we have given a elaborate introduction about MVICH implementation underlying MPICH,and illustrated its structure ,working principle and performance. MVICH is an implementation of MPICH ADI2 base ofVIA protocol, using VIA descriptors queue for transferring data in its low layer. It has some characters such as userlevel communications, without kernel trapping, memory binding and registering and so on. MVICH uses buffer(region)management,four transfer protocol,converting dynamically at runtime,and special flow control etc. For highspeed LAN,the combination of VIA and MPI can give a greater improvement for the performance of MPI applica-tions ,and exert those applications' potential ability. It will become the main project of research and development in future.
