With the increasing popularity of small to large-scale symmetric multiprocessor (SMP) systems, there has been a dire need to have sophisticated, and flexible development and runtime environments for efficient and rapid development of parallel applications. To this end, OpenMP has emerged as the standard for parallel programming on shared-memory systems. It is very important to evaluate the performance of OpenMP constructs, kernels, and application benchmarks on large-scale SMP systems. We present the performance of the basic OpenMP constructs, class B of NAS OpenMP 3.0 benchmarks, and the SPEC OMPL2001 application benchmarks (large data set) on a contemporary 72-node Sun Fire 15K SMP node. We report the basic timings, scalability, and runtime profiles of different parallel regions within each benchmark in the NAS OpenMP 3.0, and the SPEC OMPL-2001 suites. We elaborate on the performance differences between the medium and large classes of the SPEC OMP2001 suites on our system, as well as a comparison among a number of large-scale symmetric multiprocessors for the SPEC OMPL2001.

As symmetric multiprocessors become commonplace, the interconnection networks and the communication system software in clusters of multiprocessors become critical to achieving high performance. Recently, Sun Microsystems has introduced a new system area network, Sun Fire Link interconnect, for its Sun Fire cluster systems. Sun Fire Link is a memory-based interconnect, where Sun MPI uses the Remote Shared Memory (RSM) model for its user-level internode messaging protocol. In this paper, we present the overall architecture of the Sun Fire Link interconnect, explain how communication is done under the RSM, and describe the Sun MPI implementation. We provide an in-depth performance evaluation of the Sun Fire Link interconnect cluster of four Sun Fire 6800s at the RSM layer, MPI microbenchmark layer, and the application layer. Our results include the performance of the Remote Shared Memory API primitives, MPI overhead on top of the RSM, latency and bandwidth under different communication modes, parameters of the LogP model, collective communications, permutation communications, and two applications (Sphot and SMG2000) from the ASCI Purple suite under the MPI, OpenMP, and MPI-OpenMP programming paradigms. Our results indicate that put has a better performance than get on this interconnect. The Sun MPI implementation achieves an off-node latency of up to 5 microseconds. This is comparable to the Quadrics (QsNet II), and Myrinet (E-card), and better than the InfiniBand. The unidirectional and bidirectional bandwidths are 695 MB/s, and 660 MB/s, respectively. The QsNet II, and InfiniBand achieve higher bandwidths. The LogP parameters indicate the network interface is less capable of offloading the host CPU when the message size increases. The performance of our applications under MPI is better than the OpenMP version, and equal or slightly better than the mixedmode. In general, the Sun Fire Link cluster performs relatively well in most cases. I. INTRODUCTION Clusters of Symmetric Multiprocessors (SMP) have been regarded as viable scalable architectures to achieve supercomputing performance and to meet the ever-increasing demand for high-performance computing. There are two main components in such systems: the SMP node, and the communication subsystem including the interconnect, and the communication system software. Considerable work has gone into the design of SMP systems, and several vendors such as IBM, Sun, Compaq, SGI, and HP offer small to large scale shared memory systems. Sun Microsystems has introduced its Sun Fire systems in three categories of small, midsize, and large SMPs, supporting two to 106 processors, backed up with its Sun Fireplane interconnect [1] used inside the Sun UltraSPARC III Cu. The Sun Fireplane interconnect uses one to four levels of interconnect ASICs to provide better sharedmemory performance. All Sun Fire systems use point-to-point signals with a crossbar rather than a data bus. The interconnection network hardware and the communication system software are the keys to the performance of cl...

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