@inproceedings{24, author = {{Kenter, Tobias and Plessl, Christian}}, booktitle = {{Proc. Workshop on Heterogeneous High-performance Reconfigurable Computing (H2RC)}}, title = {{{Microdisk Cavity FDTD Simulation on FPGA using OpenCL}}}, year = {{2016}}, } @inproceedings{25, author = {{Lass, Michael and Kühne, Thomas and Plessl, Christian}}, booktitle = {{Workshop on Approximate Computing (AC)}}, title = {{{Using Approximate Computing in Scientific Codes}}}, year = {{2016}}, } @inproceedings{138, abstract = {{Hardware accelerators are becoming popular in academia and industry. To move one step further from the state-of-the-art multicore plus accelerator approaches, we present in this paper our innovative SAVEHSA architecture. It comprises of a heterogeneous hardware platform with three different high-end accelerators attached over PCIe (GPGPU, FPGA and Intel MIC). Such systems can process parallel workloads very efficiently whilst being more energy efficient than regular CPU systems. To leverage the heterogeneity, the workload has to be distributed among the computing units in a way that each unit is well-suited for the assigned task and executable code must be available. To tackle this problem we present two software components; the first can perform resource allocation at runtime while respecting system and application goals (in terms of throughput, energy, latency, etc.) and the second is able to analyze an application and generate executable code for an accelerator at runtime. We demonstrate the first proof-of-concept implementation of our framework on the heterogeneous platform, discuss different runtime policies and measure the introduced overheads.}}, author = {{Riebler, Heinrich and Vaz, Gavin Francis and Plessl, Christian and Trainiti, Ettore M. G. and Durelli, Gianluca C. and Del Sozzo, Emanuele and Santambrogio, Marco D. and Bolchini, Christina}}, booktitle = {{Proceedings of International Forum on Research and Technologies for Society and Industry (RTSI)}}, pages = {{1--5}}, publisher = {{IEEE}}, title = {{{Using Just-in-Time Code Generation for Transparent Resource Management in Heterogeneous Systems}}}, doi = {{10.1109/RTSI.2016.7740545}}, year = {{2016}}, } @inbook{156, abstract = {{Many modern compute nodes are heterogeneous multi-cores that integrate several CPU cores with fixed function or reconfigurable hardware cores. Such systems need to adapt task scheduling and mapping to optimise for performance and energy under varying workloads and, increasingly important, for thermal and fault management and are thus relevant targets for self-aware computing. In this chapter, we take up the generic reference architecture for designing self-aware and self-expressive computing systems and refine it for heterogeneous multi-cores. We present ReconOS, an architecture, programming model and execution environment for heterogeneous multi-cores, and show how the components of the reference architecture can be implemented on top of ReconOS. In particular, the unique feature of dynamic partial reconfiguration supports self-expression through starting and terminating reconfigurable hardware cores. We detail a case study that runs two applications on an architecture with one CPU and 12 reconfigurable hardware cores and present self-expression strategies for adapting under performance, temperature and even conflicting constraints. The case study demonstrates that the reference architecture as a model for self-aware computing is highly useful as it allows us to structure and simplify the design process, which will be essential for designing complex future compute nodes. Furthermore, ReconOS is used as a base technology for flexible protocol stacks in Chapter 10, an approach for self-aware computing at the networking level.}}, author = {{Agne, Andreas and Happe, Markus and Lösch, Achim and Plessl, Christian and Platzner, Marco}}, booktitle = {{Self-aware Computing Systems}}, pages = {{145--165}}, publisher = {{Springer International Publishing}}, title = {{{Self-aware Compute Nodes}}}, doi = {{10.1007/978-3-319-39675-0_8}}, year = {{2016}}, } @article{165, abstract = {{A broad spectrum of applications can be accelerated by offloading computation intensive parts to reconfigurable hardware. However, to achieve speedups, the number of loop it- erations (trip count) needs to be sufficiently large to amortize offloading overheads. Trip counts are frequently not known at compile time, but only at runtime just before entering a loop. Therefore, we propose to generate code for both the CPU and the coprocessor, and defer the offloading decision to the application runtime. We demonstrate how a toolflow, based on the LLVM compiler framework, can automatically embed dynamic offloading de- cisions into the application code. We perform in-depth static and dynamic analysis of pop- ular benchmarks, which confirm the general potential of such an approach. We also pro- pose to optimize the offloading process by decoupling the runtime decision from the loop execution (decision slack). The feasibility of our approach is demonstrated by a toolflow that automatically identifies suitable data-parallel loops and generates code for the FPGA coprocessor of a Convey HC-1. We evaluate the integrated toolflow with representative loops executed for different input data sizes.}}, author = {{Vaz, Gavin Francis and Riebler, Heinrich and Kenter, Tobias and Plessl, Christian}}, issn = {{0045-7906}}, journal = {{Computers and Electrical Engineering}}, pages = {{91--111}}, publisher = {{Elsevier}}, title = {{{Potential and Methods for Embedding Dynamic Offloading Decisions into Application Code}}}, doi = {{10.1016/j.compeleceng.2016.04.021}}, volume = {{55}}, year = {{2016}}, } @inproceedings{168, abstract = {{The use of heterogeneous computing resources, such as Graphic Processing Units or other specialized coprocessors, has become widespread in recent years because of their per- formance and energy efficiency advantages. Approaches for managing and scheduling tasks to heterogeneous resources are still subject to research. Although queuing systems have recently been extended to support accelerator resources, a general solution that manages heterogeneous resources at the operating system- level to exploit a global view of the system state is still missing.In this paper we present a user space scheduler that enables task scheduling and migration on heterogeneous processing resources in Linux. Using run queues for available resources we perform scheduling decisions based on the system state and on task characterization from earlier measurements. With a pro- gramming pattern that supports the integration of checkpoints into applications, we preempt tasks and migrate them between three very different compute resources. Considering static and dynamic workload scenarios, we show that this approach can gain up to 17% performance, on average 7%, by effectively avoiding idle resources. We demonstrate that a work-conserving strategy without migration is no suitable alternative.}}, author = {{Lösch, Achim and Beisel, Tobias and Kenter, Tobias and Plessl, Christian and Platzner, Marco}}, booktitle = {{Proceedings of the 2016 Design, Automation & Test in Europe Conference & Exhibition (DATE)}}, pages = {{912--917}}, publisher = {{EDA Consortium / IEEE}}, title = {{{Performance-centric scheduling with task migration for a heterogeneous compute node in the data center}}}, year = {{2016}}, } @inproceedings{171, author = {{Kenter, Tobias and Vaz, Gavin Francis and Riebler, Heinrich and Plessl, Christian}}, booktitle = {{Workshop on Reconfigurable Computing (WRC)}}, title = {{{Opportunities for deferring application partitioning and accelerator synthesis to runtime (extended abstract)}}}, year = {{2016}}, } @article{10024, abstract = {{The influence of electronic many-body interactions, spin-orbit coupling, and thermal lattice vibrations on the electronic structure of lithium niobate is calculated from first principles. Self-energy calculations in the GW approximation show that the inclusion of self-consistency in the Green function G and the screened Coulomb potential W opens the band gap far stronger than found in previous G0W0 calculations but slightly overestimates its actual value due to the neglect of excitonic effects in W. A realistic frozen-lattice band gap of about 5.9 eV is obtained by combining hybrid density functional theory with the QSGW0 scheme. The renormalization of the band gap due to electron-phonon coupling, derived here using molecular dynamics as well as density functional perturbation theory, reduces this value by about 0.5 eV at room temperature. Spin-orbit coupling does not noticeably modify the fundamental gap but gives rise to a Rashba-like spin texture in the conduction band.}}, author = {{Riefer, Arthur and Friedrich, Michael and Sanna, Simone and Gerstmann, Uwe and Schindlmayr, Arno and Schmidt, Wolf Gero}}, issn = {{2469-9969}}, journal = {{Physical Review B}}, number = {{7}}, publisher = {{American Physical Society}}, title = {{{LiNbO3 electronic structure: Many-body interactions, spin-orbit coupling, and thermal effects}}}, doi = {{10.1103/PhysRevB.93.075205}}, volume = {{93}}, year = {{2016}}, } @article{10025, abstract = {{The phonon dispersions of the ferro‐ and paraelectric phase of LiTaO3 are calculated within density‐functional perturbation theory. The longitudinal optical phonon modes are theoretically derived and compared with available experimental data. Our results confirm the recent phonon assignment proposed by Margueron et al. [J. Appl. Phys. 111, 104105 (2012)] on the basis of spectroscopical studies. A comparison with the phonon band structure of the related material LiNbO3 shows minor differences that can be traced to the atomic‐mass difference between Ta and Nb. The presence of phonons with imaginary frequencies for the paraelectric phase suggests that it does not correspond to a minimum energy structure, and is compatible with an order‐disorder type phase transition.}}, author = {{Friedrich, Michael and Schindlmayr, Arno and Schmidt, Wolf Gero and Sanna, Simone}}, issn = {{1521-3951}}, journal = {{Physica Status Solidi B}}, number = {{4}}, pages = {{683--689}}, publisher = {{Wiley-VCH}}, title = {{{LiTaO3 phonon dispersion and ferroelectric transition calculated from first principles}}}, doi = {{10.1002/pssb.201552576}}, volume = {{253}}, year = {{2016}}, } @article{13492, author = {{Tebi, Stefano and Aldahhak, Hazem and Serrano, Giulia and Schöfberger, Wolfgang and Rauls, Eva and Schmidt, Wolf Gero and Koch, Reinhold and Müllegger, Stefan}}, issn = {{0957-4484}}, journal = {{Nanotechnology}}, title = {{{Manipulation resolves non-trivial structure of corrole monolayer on Ag(111)}}}, doi = {{10.1088/0957-4484/27/2/025704}}, volume = {{27}}, year = {{2016}}, } @article{13476, author = {{Vollmers, Nora Jenny and Müller, Patrick and Hoffmann, Alexander and Herres-Pawlis, Sonja and Rohrmüller, Martin and Schmidt, Wolf Gero and Gerstmann, Uwe and Bauer, Matthias}}, issn = {{0020-1669}}, journal = {{Inorganic Chemistry}}, pages = {{11694--11706}}, title = {{{Experimental and Theoretical High-Energy-Resolution X-ray Absorption Spectroscopy: Implications for the Investigation of the Entatic State}}}, doi = {{10.1021/acs.inorgchem.6b01704}}, volume = {{55}}, year = {{2016}}, } @article{13477, author = {{Witte, Matthias and Grimm-Lebsanft, Benjamin and Goos, Arne and Binder, Stephan and Rübhausen, Michael and Bernard, Martin and Neuba, Adam and Gorelsky, Serge and Gerstmann, Uwe and Henkel, Gerald and Schmidt, Wolf Gero and Herres-Pawlis, Sonja}}, issn = {{0192-8651}}, journal = {{Journal of Computational Chemistry}}, number = {{23-24}}, pages = {{2181--2192}}, title = {{{Optical response of the Cu2S2diamond core in Cu2II(NGuaS)2Cl2}}}, doi = {{10.1002/jcc.24439}}, volume = {{37}}, year = {{2016}}, } @article{13479, author = {{Lücke, Andreas and Ortmann, Frank and Panhans, Michel and Sanna, Simone and Rauls, Eva and Gerstmann, Uwe and Schmidt, Wolf Gero}}, issn = {{1520-6106}}, journal = {{The Journal of Physical Chemistry B}}, pages = {{5572--5580}}, title = {{{Temperature-Dependent Hole Mobility and Its Limit in Crystal-Phase P3HT Calculated from First Principles}}}, doi = {{10.1021/acs.jpcb.6b03598}}, volume = {{120}}, year = {{2016}}, } @article{13480, author = {{Paulheim, A. and Marquardt, C. and Aldahhak, Hazem and Rauls, E. and Schmidt, Wolf Gero and Sokolowski, M.}}, issn = {{1932-7447}}, journal = {{The Journal of Physical Chemistry C}}, pages = {{11926--11937}}, title = {{{Inhomogeneous and Homogeneous Line Broadening of Optical Spectra of PTCDA Molecules Adsorbed at Step Edges of Alkali Halide Surfaces}}}, doi = {{10.1021/acs.jpcc.6b01956}}, volume = {{10}}, year = {{2016}}, } @article{13485, author = {{Sanna, S. and Dues, C. and Schmidt, Wolf Gero and Timmer, F. and Wollschläger, J. and Franz, M. and Appelfeller, S. and Dähne, M.}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, number = {{19}}, title = {{{Rare-earth silicide thin films on the Si(111) surface}}}, doi = {{10.1103/physrevb.93.195407}}, volume = {{93}}, year = {{2016}}, } @article{13487, author = {{Witte, M. and Gerstmann, Uwe and Neuba, Adam and Henkel, G. and Schmidt, Wolf Gero}}, issn = {{0192-8651}}, journal = {{Journal of Computational Chemistry}}, pages = {{1005--1018}}, title = {{{Density functional theory of the CuA-like Cu2S2 diamond core in Cu 2II(NGuaS)2Cl2}}}, doi = {{10.1002/jcc.24289}}, volume = {{37}}, year = {{2016}}, } @article{13481, author = {{Jeckelmann, Eric and Sanna, Simone and Schmidt, Wolf Gero and Speiser, Eugen and Esser, Norbert}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, number = {{24}}, title = {{{Grand canonical Peierls transition in In/Si(111)}}}, doi = {{10.1103/physrevb.93.241407}}, volume = {{93}}, year = {{2016}}, } @article{13478, author = {{Speiser, E. and Esser, N. and Wippermann, S. and Schmidt, Wolf Gero}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, number = {{7}}, title = {{{Surface vibrational Raman modes of In:Si(111)(4×1)and(8×2)nanowires}}}, doi = {{10.1103/physrevb.94.075417}}, volume = {{94}}, year = {{2016}}, } @article{13488, author = {{Miccoli, I. and Edler, F. and Pfnür, H. and Appelfeller, S. and Dähne, M. and Holtgrewe, K. and Sanna, S. and Schmidt, Wolf Gero and Tegenkamp, C.}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, title = {{{Atomic size effects studied by transport in single silicide nanowires}}}, doi = {{10.1103/physrevb.93.125412}}, year = {{2016}}, } @article{13458, author = {{Liebhaber, M. and Halbig, B. and Bass, U. and Geurts, J. and Neufeld, Sergej and Sanna, S. and Schmidt, Wolf Gero and Speiser, E. and Räthel, J. and Chandola, S. and Esser, N.}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, number = {{23}}, title = {{{Vibration eigenmodes of the Au-(5×2)/Si(111) surface studied by Raman spectroscopy and first-principles calculations}}}, doi = {{10.1103/physrevb.94.235304}}, volume = {{94}}, year = {{2016}}, }