TY - GEN A1 - Allalen, Mohammed A1 - Brehm, Matthias A1 - Stüben, Hinnerk T1 - Performance of Quantum Chromodynamics (QCD) Simulations on the SGI Altix N2 - We study performance and scaling of the Berlin Quantum Chromodynamics Program (BQCD) on the SGI Altix 4700 at Leibniz Supercomputing Centre (LRZ). We employ different communication methods (MPI, MPI with two OpenMP threads per process, as well as the shmem library) and run the MPI version on the two types of nodes of that machine. For comparison with other machines we made performance measurements on an IBM p690 cluster and a Cray XT4. T3 - ZIB-Report - 08-54 Y1 - 2008 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-11086 SN - 1438-0064 ER - TY - GEN A1 - Streuer, Thomas A1 - Stüben, Hinnerk T1 - Simulations of QCD in the Era of Sustained Tflop/s Computing N2 - The latest machine generation installed at supercomputer centres in Germany offers a peak performance in the tens of Tflop/s range. We study performance and scaling of our quantum chromodynamics simulation programme BQCD that we obtained on two of these machines, an IBM Blue Gene/L and an SGI Altix 4700. We compare the performance of Fortran/MPI code with assembler code. The latter allows to exploit concurrency at more levels, in particular in overlapping communication and computation as well as prefetching data from main memory. T3 - ZIB-Report - 07-48 Y1 - 2008 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-10623 SN - 1438-0064 ER - TY - GEN A1 - Ilgenfritz, Ernst-Michael A1 - Kerler, Werner A1 - Müller-Preussker, Michael A1 - Sternbeck, Andre A1 - Stüben, Hinnerk T1 - Probing the Aoki phase with N_f=2 Wilson fermions at finite temperature N2 - In this letter we report on a numerical investigation of the Aoki phase in the case of finite temperature which continues our former study at zero temperature. We have performed simulations with Wilson fermions at $\beta=4.6$ using lattices with temporal extension $N_{\tau}=4$. In contrast to the zero temperature case, the existence of an Aoki phase can be confirmed for a small range in $\kappa$ at $\beta=4.6$, however, shifted slightly to lower $\kappa$. Despite fine-tuning $\kappa$ we could not separate the thermal transition line from the Aoki phase. T3 - ZIB-Report - 05-48 KW - Wilson fermions KW - phase diagram KW - parity-flavor symmetry KW - Aoki phase KW - finite temperature Y1 - 2005 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-8812 ER - TY - JOUR A1 - Hege, Hans-Christian A1 - Stüben, Hinnerk T1 - Daten "sehen" - Wissenschaftliche Visualisierung im RTB Berlin JF - DFN Mitteilungen Y1 - 1995 VL - 38 SP - 10 EP - 12target ER - TY - CHAP A1 - Hege, Hans-Christian A1 - Stüben, Hinnerk T1 - Vectorization and Parallelization of Irregular Problems via Graph Coloring T2 - Proc. of the ACM Int. Conf. on Supercomputing Y1 - 1991 U6 - https://doi.org/10.1145/109025.109042 SP - 47 EP - 56 CY - Cologne ER - TY - GEN A1 - Göckeler, Meinulf A1 - Horsley, Roger A1 - Linke, Volkard A1 - Rakow, Paul A1 - Schierholz, Gerrit A1 - Stüben, Hinnerk T1 - Seeking the Equation of State of Non-Compact Lattice QED N2 - We perform a high statistics calculation of the equation of state for non-compact QED on large lattices. The calculation extends to fermionic correlation lengths of $\approx 8$, and it is combined with a finite size scaling analysis of the lattice data. T3 - ZIB-Report - SC-96-15 Y1 - 1996 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-2263 ER - TY - GEN A1 - Hege, Hans-Christian A1 - Stüben, Hinnerk T1 - Vectorization and Parallelization of Irregular Problems via Graph coloring. N2 - Efficient implementations of irregular problems on vector and parallel architectures are generally hard to realize. An important class of problems are Gauß-Seidel iteration schemes applied to irregular data sets. The unstructured data dependences arising there prevent restructuring compilers from generating efficient code for vector or parallel machines. It is shown, how to structure the data dependences by decomposing the underlying data set using graph coloring techniques and by specifying a particular execution order already on the algorithm level. Methods to master the irregularities originating from different types of tasks are proposed. An application is given and some open issues and future developments are discussed. T3 - ZIB-Report - SC-90-16 Y1 - 1990 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-443 ER - TY - GEN A1 - Göckeler, Meinulf A1 - Horsley, Roger A1 - Linke, Volkard A1 - Rakow, Paul A1 - Schierholz, Gerrit A1 - Stüben, Hinnerk T1 - Probing the Continuum Limit in Non-Compact QED: New Results on Large Lattices N2 - We present new Monte Carlo results in non-compact lattice QED with staggered fermions down to $m_0 = 0.005$. This extends our previous investigations on the nature of the continuum limit of QED. T3 - ZIB-Report - SC-94-31 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-1593 ER - TY - GEN A1 - Khan, Arifa Ali A1 - Bakeyev, Timur A1 - Göckeler, Meinulf A1 - Horsley, Roger A1 - Pleiter, Dirk A1 - Rakow, Paul A1 - Schäfer, Andreas A1 - Schierholz, Gerrit A1 - Stüben, Hinnerk T1 - Accelerating Hasenbusch's Acceleration of Hybrid Monte Carlo N2 - Hasenbusch has proposed splitting the pseudo-fermionic action into two parts, in order to speed-up Hybrid Monte Carlo simulations of QCD. We have tested a different splitting, also using clover-improved Wilson fermions. An additional speed-up between 5 and 20\% over the original proposal was achieved in production runs. T3 - ZIB-Report - 03-30 Y1 - 2003 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-7520 ER - TY - GEN A1 - Fleuren, Maria A1 - Stüben, Hinnerk A1 - Zegwaard, Gideon T1 - MoDySim - A parallel dynamical UMTS simulator N2 - UMTS is a 3rd generation mobile telecommunication system which enables multi-service and multi-bit rate communication going beyond the possibilities of previous systems. The simulator MoDySim models UMTS in great detail. Characteristics of UMTS such as soft hand-over and the interdependency of load and capacity among neighbouring cells are challenges for the parallelisation of such a system. In this paper we explain how the software was parallelised and present performance results of a UMTS simulation for the city of Berlin. T3 - ZIB-Report - 03-26 Y1 - 2003 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-7489 ER -