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High Performance Stencil Code Algorithms for GPGPUs

Procedia computer science 2011年 4卷 2027-2036页

作者： Andreas Schäfer Dietmar Fey Chair for Computer Science 3–Computer Architecture Friedrich-Alexander-Universität Erlangen-Nürnberg Erlangen Germany

In this paper we investigate how stencil computations can be implemented on state-of-the-art general purpose graphics processing units (GPGPUs). Stencil codes can be found at the core of many numerical solvers and physical simulation codes and are therefore of particular interest to scientific computing research. GPGPUs have gained a lot of attention recently because of their superior floating point performance and memory bandwidth. Nevertheless, especially memory bound stencil codes have proven to be challenging for GPGPUs, yielding lower than to be expected speedups. We chose the Jacobi method as a standard benchmark to evaluate a set of algorithms on NVIDIA's latest Fermi chipset. One of our fastest algorithms is a parallel wavefront update. It exploits the enlarged on-chip shared memory to perform two time step updates per sweep. To the best of our knowledge, it represents the first successful applicationof temporal blocking for 3D stencils on GPGPUs and thereby exceeds previous results by a considerable margin. It is also the first paper to study stencil codes on Fermi.

关键词： Stencil codes GPU High performance computing Temporal blocking Jacobi solver CUDA

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B2-Tree: Page-Based String Indexing in Concurrent Environments

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Datenbank-Spektrum 2022年第1期22卷 11-22页

作者： Schmeißer, Josef Schüle, Maximilian E. Leis, Viktor Neumann, Thomas Kemper, Alfons Chair for Database Systems TU Munich Boltzmannstraße 3 Garching85748 Germany Chair of Computer Science 6 Friedrich–Alexander University Erlangen–Nürnberg Martensstraße 3 Erlangen91058 Germany

Recently proposed index structures, that combine trie-based and comparison-based search mechanisms, considerably improve retrieval throughput for in-memory database systems. However, most of these index structures allocate small memory chunks when required. This stands in contrast to block-based index structures, that are necessary for disk-accesses of beyond main-memory database systems such as Umbra. We therefore present the B2-tree. The outer structure is identical to that of an ordinary B+-tree. It still stores elements in a dense array in sorted order, enabling efficient range scan operations. However, B2-tree is composed of multiple trees, each page integrates another trie-based search tree, which is used to determine a small memory region where a sought entry may be found. An embedded tree thereby consists of decision nodes, which operate on a single byte at a time, and span nodes, which are used to store common prefixes. This architecture usually accesses fewer cache lines than a vanilla B+-tree as shown in our performance evaluation. As a result, the B2-tree answers point queries considerably faster. Concurrent access to B2-tree pages are managed by an optimistic locking protocol which results in high utilization of the available hardware resources. Our evaluation of read-write workloads attests more than competitive performance for the B2-tree compared to a traditional B+-tree. © 2022, The Author(s).

关键词： Database systems

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Dynamically programmable image processor for compact vision systems

Dynamically programmable image processor for compact vision ...

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10th IEEE International Conference on computer and Information Technology, CIT-2010, 7th IEEE International Conference on Embedded Software and Systems, ICESS-2010, 10th IEEE Int. Conf. Scalable Computing and Communications, ScalCom-2010

作者： Loos, Andreas Schmidt, Michael Fey, Dietmar Gröbel, Jens Department of Computer Science University of Erlangen-Nurnberg Chair of Computer Science 3 D-91058 Erlangen Germany Vision and Control GmbH D-98527 Suhl Germany

ISBN: (纸本)9780769541082

We present a fine-grain parallel processor chip which can be embedded in very compact machine vision systems, e. g. in 3d stacked die assemblies. Smart and fast vision systems are frequently required in industrial environments to automatically detect and inspect objects, e. g. on an assembly line. The chip die has a size of 25mm2and is manufactured using a 0.18 μmCMOS technology. The chip processes binary images with a maximum resolution of 320×240 pixels (QVGA) supplied by a separate closely-linked image sensor array. It is possible to process an image in multiple cycles where a set of morphological operations can be subsequently combined depending on the image processing problem. In addition the chip is able to compute more complex user-defined programs, e. g. to skeletonize images. The output data can be a preprocessed image or projection representations in horizontal, vertical and diagonal direction, which re- duces the data amount. Therefore a faster image post- processing is supported, e. g. to calculate object's momenta. The chip is driven by a 40 MHz clock. As result a base morphological operation including image in/output needs only 250 μs. For even faster data in/output a ROI (region of interest) can be defined. Two standardized interfaces (JTAG, SPI) allow to parameterize as well as to program the circuit. © 2010 IEEE.

关键词： Binary images

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DAGMA: Mining directed acyclic graphs

DAGMA: Mining directed acyclic graphs

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Informatics 2008 and Data Mining 2008, MCCSIS'08 - IADIS Multi Conference on computer science and Information Systems

作者： Werth, T. Dreweke, A.I. Wörlein, M. Fischer, I. Philippsen, M. University of Erlangen-Nuremberg Chair 2 in Computer Science Martensstr. 3 91058 Erlangen Germany Nycomed Chair for Applied Computer Science University of Konstanz BOX M712 78457 Konstanz Germany

ISBN: (纸本)9789728924638

We present how to efficiently mine a set of directed acyclic graphs (DAGs) for unconnected, both multi- or single-rooted, and induced fragments. With a new canonical form that is based on the nodes' topological levels, our miner is faster and uses less storage than general purpose gSpan (Yan, X. and Han, J., 2002). Moreover, it can base support resp. frequency either on the number of embeddings of a fragment in the database or on the number of graphs a fragment appears in. This is crucial for finding frequent fragments in data flow graphs generated from assembly code. Extracting them into new procedures reduces the total code size. The paper shows that our miner outperforms general purpose mining and demonstrates the quantitative effects of DAG mining in program size reduction. © 2008 IADIS.

关键词： Miners

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Meta-Service Organization for a Pervasive University

Meta-Service Organization for a Pervasive University

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IEEE International Conference on Pervasive Computing and Communications (PerCom)

作者： Raphael Zender Enrico Dressler Ulrike Lucke Djamshid Tavangarian Department of Computer Science Chair of Computer Architecture University of Rostock Rostock Germany Department of Computer Science Chair of Computer Architecture Rostock Germany

SOA services afford a uniform and transparent use of different devices with similar functionalities. In the last years a number of mostly incompatible, SOA technologies have been established. Therefore, this advantage is no longer true. Indeed it is not required to support the specific device, but the concrete SOA technology. Furthermore, a transparent service discovery is prevented by device interconnections because many SOA technologies use IP multicasts for a service discovery. The discovery range is limited on the consumer's subnet as the most routers don't route multi-casts. This article describes a service discovery approach, that is independent from concrete SOA technologies and device interconnections. That results in an increase of available services and the service discovery range.

关键词： Service oriented architecture Concrete Pervasive computing Web services computer science computer architecture Humans Electronic equipment Home automation Plugs

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Leveraging Hybrid Classical-Quantum Methods for Efficient Load Rebalancing in HPC

Leveraging Hybrid Classical-Quantum Methods for Efficient Lo...

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2024 Workshops of the International Conference for High Performance Computing, Networking, Storage and Analysis, SC Workshops 2024

作者： Zawalska, Justyna Chung, Minh Rycerz, Katarzyna Schulz, Laura Schulz, Martin Kranzlmuller, Dieter AGH University of Krakow Institute of Computer Science Krakow Poland CYFRONET AGH Academic Computer Center Krakow Poland Garching bei München Germany Chair for Computer Architecture and Parallel Systems Germany MNM-Team Germany

ISBN: (纸本)9798350355543

Load imbalance is a challenge for parallel applications in High Performance Computing (HPC). It is caused by processes having different execution times or load values, leading to idle or wait times at synchronization points, where faster processes must wait for the slowest process to catch up. To mitigate this issue, applications can employ load balancing (LB) strategies, which migrate load between processes to even out load. This is often referred to as the Load Rebalancing Problem (LRP). While many approaches solving the LRP exist, they can only be heuristics and hence further optimization potential exists. In our work, we turn to a novel approach by using hybrid classical-quantum approaches and present two versions of the constrained quadratic model for solving the LRP;the two differ in how they balance the number of qubits required with the types of applied constraints. We compare the quantum-based methods with classical methods using heuristic algorithms Greedy, Karmarkar-Karp, and ProactLB. We evaluate our approaches using imbalance ratio and speedup as metrics, as well as the number of migrated tasks to indicate overhead caused by migrations. Our results show that the quantum-based methods outperform the classic methods. For example, we need only 1/4 of the number of migrated tasks in a realistic use case compared with classical methods, particularly Greedy and KK, to balance the load. © 2024 IEEE.

关键词： CQM HPC HPCQC integration Load Rebalancing Quantum Computing task migration

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A speed-up study for a parallelized white light interferometry preprocessing algorithm on a virtual embedded multiprocessor system

A speed-up study for a parallelized white light interferomet...

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International Conference on architecture of Computing Systems (ARCS)

作者： Dominik Schoenwetter Max Schneider Dietmar Fey Chair of Computer Science 3 (Computer Architecture) Friedrich-Alexander-University of Erlangen-Nuremberg Erlangen Germany

Parallel computing has been a niche for scientific research in academia for decades. However, as common industrial applications become more and more performance demanding and raising the clock frequency of conventional single-core systems is hardly an option due to reaching technological limitations, efficient use of (embedded) multi-core CPUs and many-core platforms has become imperative. 3D surface analysis of objects using the white light interferometry presents one of such challenging applications. The goal in this article is to get an impression which speed-up for an established and parallelized white light interferometry preprocessing algorithm, called Contrast Method, is possible on an embedded system that works without any operating system. Therefore, we decided to use a virtual environment that is able to simulate embedded multi-core as well as many-core systems and that enables running real application code on the designed system. The results show, that a significant speedup is possible when using a many-core platform, instead of a design that only implements one single core, if the algorithm is parallelized for getting full advantage of the many-core design. Furthermore, an acceptable absolute run time is achievable.

关键词： Program processors Optical interferometry Interference Hardware Algorithm design and analysis Synchronization Multicore processing

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Wireless Self-Organizing Backbone Mesh Network (WiSoNet)

Wireless Self-Organizing Backbone Mesh Network (WiSoNet)

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IEEE Annual Conference on Pervasive Computing and Communications Workshops (PerCom)

作者： Heiko Kopp Martin Krohn Robil Daher Djamshid Tavangarian Institute of Computer Science Chair of Computer Architecture University of Rostock Germany

Despite significant advances in parts of the physical layer, available WLAN systems still cannot offer wired equivalent bandwidth. In this paper we propose a novel concept, called wireless self-organizing backbone mesh network (WiSoNet), for a wireless network infrastructure as a backbone and describe its long-term potential. WiSoNet combines two major IEEE standards - IEEE 802.11 (WLAN) and IEEE 802.16 (WiMAX) to build a heterogeneous wireless network topology. To aggregate bandwidth of multiple WLAN connections we introduce a hybrid network solution that uses ad-hoc mechanisms. Further, to decrease the amount of administration and resource management, we use specific algorithms for the self-organization of routing and channels assignment. Since the WiMAX-based supply network already supports quality of service, we propose mechanisms to extend the QoS to end users. Accordingly, we present our prototypical system implementation and discuss the issues we will focus on in the future

关键词： Spine Mesh networks Wireless LAN Bandwidth Wireless mesh networks WiMAX Quality of service Physical layer Network topology Aggregates

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Novel handoff concepts for roadside networks using mechanisms of IEEE 802.11k & IEEE 802.11v

Novel handoff concepts for roadside networks using mechanism...

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International Conference on Ultra Modern Telecommunications and Workshops (ICUMT)

作者： Robert Meschke Martin Krohn Robil Daher Alexander Gladisch Djamshid Tavangarian Chair of Computer Architecture Institute of Computer Science University of Rostock Germany

The employment of real-time capable handoff mechanisms for high-speed mobile stations represents one of the key challenges for adopting IEEE 802.11 technology as a basic communication technology for roadside networks in vehicular communication networks (VCNs), especially for real-time value added services such as VoIP. To enable real-time capable handoff mechanism in such environments, the mobility awareness of associated stations (STAs) can be used to significantly reduce the scanning delays within handoff process. Although IEEE 802.11k and 802.11v define several mechanisms that could be used to enhance the handoff process with location awareness functionality, none of the known handoff solutions combine those mechanisms in a unified standard-conform handoff solution. This paper introduces a set of three novel handoff concepts that combine mechanisms of 802.11k,r,v in order to provide real-time capable handoff mechanisms that can be used for VCNs' applications, especially in combination with value added services. All the proposed handoff mechanisms in this paper are vender-independent from STAs perspective, i.e., for all STAs supporting 802.11k,r,v standards.

关键词： Manuals Irrigation Global Positioning System

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A wireless architecture for telemedicine

A wireless architecture for telemedicine

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Workshop on Positioning, Navigation and Communication, WPNC

作者： Martin Krohn Heiko Kopp Djamshid Tavangarian Institute of Computer Science Chair of Computer Architecture University of Rostock Germany

In respect to the demographic change, currently taking place in Germany, especially in the federal state of Mecklenburg-Vorpommern, the project "AGnES" was started by the University of Greifswald (Faculty of Medicine) and the University of Rostock (Faculty computer science and Electrical Engineering). The project aims to develop an infrastructure helping to assist physicians. The essential of the project is the Community Medicine Nurse (CMN), performing home visits, physical examinations and monitoring of patients. During the examinations the CMN is in contact with the supervising family doctor. Therefore, a data connection transmitting telemedical, audio and video data has to be established. Our work handles an automatical antenna positioning system designed for the mobile WiMAX subscriber stations, which are part of the communication architecture.

关键词： Telemedicine computer architecture Demography computer science Patient monitoring computerized monitoring Contacts Mobile antennas WiMAX Mobile communication

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