Wyniki wyszukiwania - BazTech

Ograniczanie wyników

2 Computational Methods in Science and Technology

2 2006

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

A scalability Study of SGI Clustered XFS Using HDF Based AMR Application

Saini S., Talcott D., Yeung H., Myers G., Ciotti R.

Computational Methods in Science and Technology

2006

Vol. spec. issue

47-54

Many large-scale parallel scientific and engineering applications, especially climate modeling, often run for lengthy periods and require data checkpointing periodically to save the state of the computation for a program restart. In addition, such applications need to write data to disks for post-processing, e.g., visualization. Both these scenarios involve a write-only pattern using Hierarchal Data Format (HDF) files. In this paper, we study the scalability of CXFS by HDF based Structured Adaptive Mesh Refinement (AMR) application for three different block sizes. The code used is a block-structured AMR hydrodynamics code that solves compressible, reactive hydrodynamic equations and characterizes physics and mathematical algorithms used in studying nuclear flashes on neutron stars and white dwarfs. The computational domain is divided into blocks distributed across the processors. Typically, a block contains 8 zones in each coordinate direction (x, y, and z) and a perimeter of guard cells (in this case, 4 zones deep) to hold information from the neighbors. We used three different block sizes of 8 × 8 × 8, 16 × 16 × 16, and 32 × 32 × 32. Results of parallel I/O bandwidths (checkpoint file and two plot files) are presented for all three-block sizes on a wide range of processor counts, ranging from 1 to 508 processors of the Columbia system.

A scalability Study of Columbia using the NAS Parallel Benchmarks

Saini S., Chang J., Hood R., Jin H.

Computational Methods in Science and Technology

2006

Vol. spec. issue

33-45

The Columbia system at the NASA Advanced Supercomputing (NAS) facility is a cluster of 20 SGI Altix nodes, each with 512 Itanium 2 processors and 1 terabyte (TB) of shared-access memory. Four of the nodes are organized as a 2048-processor capabilitycomputing platform connected by two low-latency interconnects – NUMALink4 (NL4) and InfiniBand (IB). To evaluate the scalability of Columbia with respect to both increased processor counts and increased problem sizes, we used seven of the NAS Parallel Benchmarks and all three of the NAS multi-zone benchmarks. For NPB we ran three Classes B, C, and D of benchmarks. To measure the impact of some architectural features, we compared Columbia results with results obtained on a Cray Opteron Cluster consisting of 64 nodes, each with 2 AMD Opteron processors and 2 gigabytes (GB) of memory, connected with Myrinet 2000. In these experiments, we measured performance degradation due to contention for the memory buses on the SGI Altix BX2 nodes. We also observed the effectiveness of SGI’s NL4 interconnect over Myrinet. Finally, we saw that computations spanning multiple BX2 nodes connected with NL4 performed well. Some computations did almost as well when the IB interconnects was used.