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The Performance Effect of Multi-core on ScientificApplications

Description: The historical trend of increasing single CPU performancehas given way to roadmap of increasing core count. The challenge ofeffectively utilizing these multi-core chips is just starting to beexplored by vendors and application developers alike. In this study, wepresent some performance measurements of several complete scientificapplications on single and dual core Cray XT3 and XT4 systems with a viewto characterizing the effects of switching to multi-core chips. Weconsider effects within a node by using applications run at lowconcurrencies, and also effects on node-interconnect interaction usinghigher concurrency results. Finally, we construct a simple performancemodel based on the principle on-chip shared resource--memorybandwidth--and use this to predict the performance of the forthcomingquad-core system.
Date: May 14, 2007
Creator: Carter, Jonathan; He, Yun; Shalf, John; Shan, Hongzhang; Strohmaier, Erich & Wasserman, Harvey
Partner: UNT Libraries Government Documents Department

Accepting the T3D

Description: In April, a 128 PE Cray T3D was installed at Los Alamos National Laboratory`s Advanced Computing Laboratory as part of the DOE`s High-Performance Parallel Processor Program (H4P). In conjunction with CRI, the authors implemented a 30 day acceptance test. The test was constructed in part to help them understand the strengths and weaknesses of the T3D. In this paper, they briefly describe the H4P and its goals. They discuss the design and implementation of the T3D acceptance test and detail issues that arose during the test. They conclude with a set of system requirements that must be addressed as the T3D system evolves.
Date: October 1, 1994
Creator: Rich, D. O.; Pope, S. C. & DeLapp, J. G.
Partner: UNT Libraries Government Documents Department

Franklin: User Experiences

Description: The newest workhorse of the National Energy Research Scientific Computing Center is a Cray XT4 with 9,736 dual core nodes. This paper summarizes Franklin user experiences from friendly early user period to production period. Selected successful user stories along with top issues affecting user experiences are presented.
Date: May 7, 2008
Creator: Center, National Energy Research Supercomputing; He, Yun (Helen); Kramer, William T.C.; Carter, Jonathan & Cardo, Nicholas
Partner: UNT Libraries Government Documents Department

Optimizing the Point-In-Box Search Algorithm for the Cray Y-MP(TM) Supercomputer

Description: Determining the subset of points (particles) in a problem domain that are contained within certain spatial regions of interest can be one of the most time-consuming parts of some computer simulations. Examples where this 'point-in-box' search can dominate the computation time include (1) finite element contact problems; (2) molecular dynamics simulations; and (3) interactions between particles in numerical methods, such as discrete particle methods or smooth particle hydrodynamics. This paper describes methods to optimize a point-in-box search algorithm developed by Swegle that make optimal use of the architectural features of the Cray Y-MP Supercomputer.
Date: December 23, 1998
Creator: Attaway, S.W.; Davis, M.E.; Heinstein, M.W. & Swegle, J.S.
Partner: UNT Libraries Government Documents Department

Improved utilization and responsiveness with gang scheduling

Description: Most commercial multicomputers use space-slicing schemes in which each scheduling decision has an unknown impact on the future: should a job be scheduled, risking that it will block other larger jobs later, or should the processors be left idle for now in anticipation of future arrivals? This dilemma is solved by using gang scheduling, because then the impact of each decision is limited to its time slice, and future arrivals can be accommodated in other time slices. This added flexibility is shown to improve overall system utilization and responsiveness. Empirical evidence from using gang scheduling on a Cray T3D installed at Lawrence Livermore National Lab corroborates these results, and shows conclusively that gang scheduling can be very effective with current technology. 29 refs., 10 figs., 6 tabs.
Date: October 1, 1996
Creator: Feitelson, D.G., & Jette, M.A.
Partner: UNT Libraries Government Documents Department

A Cray T3D performance study

Description: We carry out a performance study using the Cray T3D parallel supercomputer to illustrate some important features of this machine. Timing experiments show the speed of various basic operations while more complicated operations give some measure of its parallel performance.
Date: May 1, 1996
Creator: Nallana, A. & Kincaid, D.R.
Partner: UNT Libraries Government Documents Department

Performance of the BLAS-1 and other mathematical kernels on the SGI/Cray Origin 2000 processor

Description: The purpose of this paper is to explore issues related to the computation and communication performance of the Basic Linear Algebra Subroutines (BLAS-1) and related kernels on the SGI/Cray Origin 2000 parallel computer. Experiments are performed both on vendor-supplied mathematical library routines as well as hand-coded loops and array syntax. The goal of this study is to get a better understanding of performance issues pertaining to the Origin 2000 architecture.
Date: August 1, 1997
Creator: Dearholt, W. & Joubert, W.
Partner: UNT Libraries Government Documents Department

Numerical Tokamak Turbulence Calculations on the CRAY T3E

Description: Full cross section calculations of ion-temperature-gradient-driven turbulence with Landau closure are being carried out as part of the Numerical Tokamak Turbulence Project, one of the U.S. Department of Energy`s Phase II Grand Challenges. To include the full cross section of a magnetic fusion device like the tokamak requires more memory and CPU time than is available on the National Energy Research Scientific Computing Center`s (NERSC`s) shared-memory vector machines such as the CRAY C90 and J90. Calculations of cylindrical multi-helicity ion-temperature-gradient-driven turbulence were completed on NERSC`s 160-processor distributed-memory CRAY T3E parallel computer with 256 Mbytes of memory per processor. This augurs well for yet more memory and CPU intensive calculations on the next-generation T3E at NERSC. This paper presents results on benchmarks with the current T3E at NERSC. Physics results pertaining to plasma confinement at the core of tokamaks subject to ion-temperature-gradient-driven-turbulence are also highlighted. Results at this resolution covering this extent of physical time were previously unattainable. Work is in progress to increase the resolution, improve the performance of the parallel code, and include toroidal geometry in these calculations in anticipation of the imminent arrival of a fully configured,512-processor, T3E-900 model.
Date: December 31, 1997
Creator: Lynch, V.E., Leboeuf, J.N., Carreras, B.A.
Partner: UNT Libraries Government Documents Department

Development of a dynamic time sharing scheduled environment. Final report

Description: Massively parallel computers, such as the Cray T3D, have historically supported resource sharing solely with space sharing. In that method, multiple problems are solved by executing them on distinct processors. This project developed a dynamic time- and space-sharing scheduler to achieve greater interactivity and throughput than could be achieved with space-sharing alone. CRI and LLNL worked together on the design, testing, and review aspects of this project. There were separate software deliverables. CRI implemented a general purpose scheduling system as per the design specifications. LLNL ported the local gang scheduler software to the LLNL Cray T3D. In this approach, processes are allocated simultaneously to all components of a parallel program (in a gang). Program execution is preempted as needed to provide for interactivity. Programs are also relocated to different processors as needed to efficiently pack the computer`s torus of processors. In phase one, CRI developed an interface specification after discussions with LLNL for system-level software supporting a time- and space-sharing environment on the LLNL T3D. The two parties also discussed interface specifications for external control tools (such as scheduling policy tools, system administration tools) and applications programs. CRI assumed responsibility for the writing and implementation of all the necessary system software in this phase. In phase two, CRI implemented job-rolling on the Cray T3D, a mechanism for preempting a program, saving its state to disk, and later restoring its state to memory for continued execution. LLNL ported its gang scheduler to the LLNL T3D utilizing the CRI interface implemented in phases one and two. During phase three, the functionality and effectiveness of the LLNL gang scheduler was assessed to provide input to CRI time- and space-sharing efforts. CRI will utilize this information in the development of general schedulers suitable for other sites and future architectures. All phases of this project ...
Date: October 1, 1997
Partner: UNT Libraries Government Documents Department

MPICH on the T3D: A case study of high performance message passing

Description: This paper describes the design, implementation and performance of a port of the Argonne National Laboratory/Mississippi State University MPICH implementation of the Message Passing Interface standard to the Cray T3D massively parallel processing system. A description of the factors influencing the design and the various stages of implementation are presented. Performance results revealing superior bandwidth and comparable latency as compared to other full message passing systems on the T3D are shown. Further planned improvements and optimizations, including an analysis of a port to the T3E, are mentioned.
Date: July 1, 1996
Creator: Brightwell, R. & Skjellum, A.
Partner: UNT Libraries Government Documents Department

Selecting and implementing the PBS scheduler on an SGI Onyx 2/Orgin 2000.

Description: In the Mathematics and Computer Science Division at Argonne, the demand for resources on the Onyx 2 exceeds the resources available for consumption. To distribute these scarce resources effectively, we need a scheduling and resource management package with multiple capabilities. In particular, it must accept standard interactive user logins, allow batch jobs, backfill the system based on available resources, and permit system activities such as accounting to proceed without interruption. The package must include a mechanism to treat the graphic pipes as a schedulable resource. Also required is the ability to create advance reservations, offer dedicated system modes for large resource runs and benchmarking, and track the resources consumed for each job run. Furthermore, our users want to be able to obtain repeatable timing results on job runs. And, of course, package costs must be carefully considered. We explored several options, including NQE and various third-party products, before settling on the PBS scheduler.
Date: June 28, 1999
Creator: Bittner, S.
Partner: UNT Libraries Government Documents Department

New tools using the hardware performance monitor to help users tune programs on the Cray X-MP

Description: The performance of a Cray system is highly dependent on the tuning techniques used by individuals on their codes. Many of our users were not taking advantage of the tuning tools that allow them to monitor their own programs by using the Hardware Performance Monitor (HPM). We therefore modified UNICOS to collect HPM data for all processes and to report Mflop ratings based on users, programs, and time used. Our tuning efforts are now being focused on the users and programs that have the best potential for performance improvements. These modifications and some of the more striking performance improvements are described.
Date: September 25, 1991
Creator: Engert, D.E.; Rudsinski, L. (Argonne National Lab., IL (United States)) & Doak, J. (Cray Research, Inc., Minneapolis, MN (United States))
Partner: UNT Libraries Government Documents Department

Taking scientific visualization to the masses

Description: The paper offers the premise that scientific visualization capabilities are generally available only to a limited subset of scientists. Several reasons for this are presented. The paper describes a collaborative project between scientists of the Defense Nuclear Agency and computer scientists at Los Alamos National Laboratory. This project's goal is to get visualization capabilities into the hands of many more scientists.
Date: January 1, 1991
Creator: Vigil, M. & Bouchier, S.
Partner: UNT Libraries Government Documents Department

Results of the first UNICOS security survey

Description: At the Santa Fe CUG, in September 1991, a brief survey was distributed to attendees in order to begin developing a database of sites interested and active in using UNICOS security protections and features. Forty-two individuals attended a Security BOF session; their responses comprised about three-quarters of the forty-six sites (representing 62 installed machines) who completed and returned the survey questionnaire. Although the sample is clearly biased -- most of those responding had already evidenced interest in security by attending the BOF -- the broad range of sites, industrial and academic as well as government and military, that were represented was surprising. Fully 50% of the 62 installed machines were actively running UNICOS Secure Mode. This talk will provide an overview of the results of the survey, which will be repeated at least annually by the new Security MIG. A tabulation of the sites that have some experience with running Secure Mode UNICOS will be made available to all sites, in keeping with the goal of disseminating such hard-won experience with UNICOS security.
Date: January 1, 1992
Creator: Christoph, G.G.
Partner: UNT Libraries Government Documents Department

Xcl---A family of programming lanquage-based shells

Description: As the three major UNIX shells have emerged, they have shown little inclination to include syntax and semantics from existing programming languages. The first of these shells, sh, contains only a small amount of C-like syntax. Csh provides some C language expression syntax, but includes very little other C syntax. The newest of these shells, ksh, also includes some C-like expression syntax, although they contain some significantly un-C-like syntax in such areas as relational and logical operators. Several much less widely used shells have been written that much more closely resemble particular programming languages. However, each of these shells have the disadvantage of not being based upon a widely used programming language. In addition, interactive commands tend to be difficult to enter because they must frequently be entered using normal programming language constructs such as function calls. Thus, the vast majority of programmers of today's UNIX shells must deal with a shell interface that is not based upon any familiar programming language. This paper describes some of the features of the xcl family of shells. Each of these shells is based closely upon an existing programming language and provides the user with a familiar and highly programmable shell interface. 7 refs.
Date: January 1, 1989
Creator: Roschke, M.A.
Partner: UNT Libraries Government Documents Department

Implementing ASPEN on the CRAY computer

Description: This paper describes our experience in converting the ASPEN program for use on our CRAY computers at the Los Alamos National Laboratory. The CRAY computer is two-to-five times faster than a CDC-7600 for scalar operations, is equipped with up to two million words of high-speed storage, and has vector processing capability. Thus, the CRAY is a natural candidate for programs that are the size and complexity of ASPEN. Our approach to converting ASPEN and the conversion problems are discussed, including our plans for optimizing the program. Comparisons of run times for test problems between the CRAY and IBM 370 computer versions are presented.
Date: January 1, 1981
Creator: Duerre, K.H. & Bumb, A.C.
Partner: UNT Libraries Government Documents Department

Comparative performance evaluation of two supercomputers: CDC Cyber-205 and CRI Cray-1

Description: This report compares the performance of Control Data Corporation's newest supercomputer, the Cyber-205, with the Cray Research, Inc. Cray-1, currently the Laboratory's largest mainframe. The rationale of our benchmarking effort is discussed. Results are presented of tests to determine the speed of basic arithmetic operations, of runs using our standard benchmark programs, and of runs using three codes that have been optimized for both machines: a linear system solver, a model hydrodynamics code, and parts of a plasma simulation code. It is concluded that the speed of the Cyber-205 for memory-to-memory operations on vectors stored in consecutive locations is considerably faster than that of the Cray-1. However, the overall performance of the machine is not quite equal to that of the Cray for tasks of interest to the Laboratory as represented by our benchmark set.
Date: January 1, 1981
Creator: Bucher, I.Y. & Moore, J.W.
Partner: UNT Libraries Government Documents Department

Evaluation of a Cray performance tool using a large hydrodynamics code

Description: This paper will discuss one of these automatic tools that has been developed recently by Cray Research, Inc. for use on its parallel supercomputer. The tool is called ATEXPERT; when used in conjunction with the Cray Fortran compiling system, CF77, it produces a parallelized version of a code based on loop-level parallelism, plus information to enable the programmer to optimize the parallelized code and improve performance. The information obtained through the use of the tool is presented in an easy-to-read graphical format, making the digestion of such a large quantity of data relatively easy and thus, improving programmer productivity. In this paper we address the issues that we found when the took a large Los Alamos hydrodynamics code, PUEBLO, that was highly vectorizable, but not parallelized, and using ATEXPERT proceeded to parallelize it. We show that through the advice of ATEXPERT, bottlenecks in the code can be found, leading to improved performance. We also show the dependence of performance on problem size, and finally, we contrast the speedup predicted by ATEXPERT with that measured on a dedicated eight-processor Y-MP.
Date: June 1, 1992
Creator: Lord, K. M. & Simmons, M. L.
Partner: UNT Libraries Government Documents Department

Results of the first UNICOS security survey

Description: At the Santa Fe CUG, in September 1991, a brief survey was distributed to attendees in order to begin developing a database of sites interested and active in using UNICOS security protections and features. Forty-two individuals attended a Security BOF session; their responses comprised about three-quarters of the forty-six sites (representing 62 installed machines) who completed and returned the survey questionnaire. Although the sample is clearly biased -- most of those responding had already evidenced interest in security by attending the BOF -- the broad range of sites, industrial and academic as well as government and military, that were represented was surprising. Fully 50% of the 62 installed machines were actively running UNICOS Secure Mode. This talk will provide an overview of the results of the survey, which will be repeated at least annually by the new Security MIG. A tabulation of the sites that have some experience with running Secure Mode UNICOS will be made available to all sites, in keeping with the goal of disseminating such hard-won experience with UNICOS security.
Date: June 1, 1992
Creator: Christoph, G. G.
Partner: UNT Libraries Government Documents Department

Benchmarking massively parallel architectures

Description: The purpose of this paper is to summarize some initial experiences related to measuring the performance of massively parallel processors (MPPs) at Los Alamos National Laboratory (LANL). Actually, the range of MPP architectures the authors have used is rather limited, being confined mostly to the Thinking Machines Corporation (TMC) Connection Machine CM-2 and CM-5. Some very preliminary work has been carried out on the Kendall Square KSR-1, and efforts related to other machines, such as the Intel Paragon and the soon-to-be-released CRAY T3D are planned. This paper will concentrate more on methodology rather than discuss specific architectural strengths and weaknesses; the latter is expected to be the subject of future reports. MPP benchmarking is a field in critical need of structure and definition. As the authors have stated previously, such machines have enormous potential, and there is certainly a dire need for orders of magnitude computational power over current supercomputers. However, performance reports for MPPs must emphasize actual sustainable performance from real applications in a careful, responsible manner. Such has not always been the case. A recent paper has described in some detail, the problem of potentially misleading performance reporting in the parallel scientific computing field. Thus, in this paper, the authors briefly offer a few general ideas on MPP performance analysis.
Date: July 1, 1993
Creator: Lubeck, O.; Moore, J.; Simmons, M. & Wasserman, H.
Partner: UNT Libraries Government Documents Department

Modeling the Cray memory scheduler

Description: This report documents the results of a project to evaluate low cost modeling and simulation tools when applied to modeling the Cray memory scheduler. The specific tool used is described and the basics of the memory scheduler are covered. Results of simulations using the model are discussed and a favorable recommendation is made to make more use of this inexpensive technology.
Date: April 1, 1992
Creator: Wickham, K. L. & Litteer, G. L.
Partner: UNT Libraries Government Documents Department

EXCHANGE. Volume 9-92

Description: EXCHANGE is published monthly by the Idaho National Engineering Laboratory (INEL), a multidisciplinary facility operated for the US Department of Energy (DOE). The purpose of EXCHANGE is to inform computer users about about recent changes and innovations in both the mainframe and personal computer environments and how these changes can affect work being performed at DOE facilities.
Date: September 1, 1992
Creator: Boltz, J. C.
Partner: UNT Libraries Government Documents Department