SUNMOS

Abstract: As the successor to SUNMOS, the Puma operating system provides a flexible, lightweight, high performance message passing environment for massively parallel computers. Message passing in Puma is accomplished through the use of a new mechanism known as a portal. Puma is currently running on the Intel Paragon and is being developed for the Intel TeraFLOPS machine. We discuss issues regarding the development of the Argonne National Laboratory/Mississippi State University implementation of the Message Passing Interface standard on top of portals. Included is a description of the design and implementation for both MPI point-to-point and collective communications, and MPI-2 one-sided communications.

Abstract: On Paragon, two operating systems are available: (a) OSF/1 AD, and (b) SUNMOS. The chief drawbacks of OSF/1 AD are (a) OSF/1 AD takes about 8 MB of memory on each node of the Paragon, (b) messages can be sent only at a bandwidth of 30-35 MB per second compared to 200 MB per second peak advertised rate, (c) latencies are on the order of 100 microseconds using Intel NX calls under OSF1/ AD. All these drawbacks can be minimized by using SUNMOS. SUNMOS takes only 250 KB of memory on each node and can send messages at bandwidth of 170 MB per second with latencies of 70 microseconds. We have measured the performance of applications under OSF/1 AD and SUNMOS and found that under OSF/1 AD, performance does not scale as the number of nodes increases, whereas under SUNMOS it seems to scale because of higher communication bandwidth.

Abstract: Experiences and performance figures are reported from early tests of the 512-node Intel Paragon XPS35 at Oak Ridge National Laboratory. Computation performance of the 50 MHz i860XP processor as well as communication performance of the 200 megabyte/second mesh are reported and compared with other multiprocessors. Single and multiple hop communication bandwidths and latencies are measured. Concurrent communication speeds and speed under network load are also measured. File I/O performance of the mesh-attached Parallel File System is measured. Early experiences with OSF/Mach and SUNMOS operating systems are reported, as well results from porting various distributed-memory applications. This report also summarizes the second phase of a Cooperative Research and Development Agreement between Oak Ridge National Laboratory and Intel in evaluating a 66-node Intel Paragon XPS5.

Abstract: Presented is a parallel algorithm based on the fast multipole method (FMM) for the Helmholtz equation. This variant of the FMM is useful for computing radar cross sections and antenna radiation patterns. The FMM decomposes the impedance matrix into sparse components, reducing the operation count of the matrix-vector multiplication in iterative solvers to O(N3/2) (where N is the number of unknowns). The parallel algorithm divides the problem into groups and assigns the computation involved with each group to a processor node. Careful consideration is given to the communications costs. A time complexity analysis of the algorithm is presented and compared with empirical results from a Paragon XP/S running the lightweight Sandia/University of New Mexico operating system (SUNMOS). For a 90,000 unknown problem running on 60 nodes, the sparse representation fits in memory and the algorithm computes the matrix-vector product in 1.26 seconds. It sustains an aggregate rate of 1.4 Gflop/s. The corresponding dense matrix would occupy over 100 Gbytes and, assuming that I/O is free, would require on the order of 50 seconds to form the matrix-vector product.