Current advances in processor technology, and the rapid development of high speed networking technology, such as ATM, have made high performance network computing an attractive computing environment for large-scale high performance distributed computing (HPDC) applications. However, due to the communications overhead at the host-network interface, most of the HPDC applications are not getting the full benefit of high speed communication networks. This overhead can be attributed to the high cost of operating system calls, context switching, the use of inefficient communication protocols, and the coupling of data and control paths. We present an architecture and implementation for a low-latency, high-throughput message passing tool, that we refer to as the NYNET (ATM wide area network testbed in New York state) Communication System (NCS), which can support a variety of HPDC applications with different Quality of Services (QOS) requirements. NCS uses multithreading to provide efficient techniques that overlap computation and communication. NCS uses read/write trap routines to bypass traditional operating system calls. This reduces latency and avoids using inefficient communication protocols. By separating data and control paths, NCS eliminates unnecessary control transfers. This optimizes the data path and improves performance. Benchmarking results show that the performance of NCS is at least a factor of two better than the performance of corresponding p4 and PVM primitives.

Large scale High Performance Computing and Communication (HPCC) applications (e.g. Video-on-Demand, and HPDC) would require storage and processing capabilities which are beyond existing single computer systems. The current advances in networking technology (e.g. ATM) have made high performance network computing an attractive computing environment for such applications. However, using only high speed network is not sufficient to achieve high performance distributed computing environment unless some hardware and software problems have been resolved. These problems include the limited communication bandwidth available to the application, high overhead associated with context switching, redundant data copying during protocol processing and lack of support to overlap computation and communication at application level. In this paper, we propose a multithreaded message passing system for parallel/distributed processing that we refer to as NYNET communication system (NCS). NCS, being developed for NYNET (ATM wide area network testbed), is built on top of an ATM application programmer interface (API). The multithreaded environment allows applications to overlap computations and communications and provides a modular approach to support efficiently HPDC applications with different quality of service (QOS) requirements.

The recent development of parallel and distributed computing software has introduced a variety of software tools that support several programming paradigms and languages. This variety of tools makes the selection of the best tool to run a given class of applications on a parallel or distributed system a non-trivial task that requires some investigation. We expect tool evaluation to receive more attention as the deployment and usage of distributed systems increases. In this paper, we present a multi-level evaluation methodology for parallel/distributed tools in which tools are evaluated from different perspectives. We apply our evaluation methodology to three message passing tools viz Express, p4, and PVM. The approach covers several important distributed systems platforms consisting of different computers (e.g., IBM-SP1, Alpha cluster, SUN workstations) interconnected by different types of networks (e.g., Ethernet, FDDI, ATM).

With the current advances in computing and network technology and software, the gap between parallel and distributed computing environment is gradually becoming narrower. Consequently, parallel programs run on parallel as well as distributed systems. However, programming and porting complex applications to such environment is challenging task and not well understood. In this paper, we use a concurrent multi target tracker as a running example to analyze and evaluate performance of two different parallel implementations on parallel and distributed systems. We have benchmarked both these implementations on different architectures that vary from a network of worksta-tions{SUN, IBM RS6000) to parallel computers (CM5, iPSC 860) using different parallel/distributed message passing tools{PVM, p4, EXPRESS).