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IEEE International Conference on Cluster Computing (Cluster)

作者： Neuwirth, Sarah Goethe Univ Frankfurt Inst Comp Sci Frankfurt Germany

ISBN: (纸本)9781728196664

With the forthcoming age of exascale computing, the efficient support of different programming models has become a crucial performance factor for high-performance computing systems. When adopting novel programming paradigms, the performance assessment through standardized and comparable benchmarks plays an essential role in both the effective use of the heterogeneous system hardware and the application performance tuning. Alternatives to MPI such as the partitioned global address space (PGAS) model have become increasingly popular. One such PGAS API is the Global Address Space programming Interface (GASPI). This paper introduces the GASPI Benchmark Suite (GBS), which combines a comprehensive, standardized set of microbenchmarks with application kernels. The microbenchmarks target common GASPI communication patterns, including one-sided, collective, passive, and global atomics, while the application kernels stress communication schemes commonly found in real HPC applications. The effectiveness of GBS is demonstrated by evaluating the GASPI communication performance for the two networking communication standards Ethernet and InfiniBand.

关键词： PGAS programming models Performance Characterization GASPI Benchmark Suite HPC

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Worksharing Tasks: an Efficient Way to Exploit Irregular and Fine-Grained Loop Parallelism 26

Worksharing Tasks: an Efficient Way to Exploit Irregular and...

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26th International Conference on High Performance Computing, Data and Analytics (HiPCW)

作者： Maronas, Marcos Sala, Kevin Mateo, Sergi Ayguade, Eduard Beltran, Vicenc Barcelona Supercomp Ctr BSC Barcelona Spain Univ Politecn Catalunya UPC Barcelona Supercomp Ctr BSC Barcelona Spain

ISBN: (纸本)9781728145358

Shared memory programming models usually provide worksharing and task constructs. The former relies on the efficient fork-join execution model to exploit structured parallelism;while the latter relies on fine-grained synchronization among tasks and a flexible data-flow execution model to exploit dynamic, irregular, and nested parallelism. On applications that show both structured and unstructured parallelism, both worksharing and task constructs can be combined. However, it is difficult to mix both execution models without penalizing the data-flow execution model. Hence, on many applications structured parallelism is also exploited using tasks to leverage the full benefits of a pure data-flow execution model. However, task creation and management might introduce a non-negligible overhead that prevents the efficient exploitation of fine-grained structured parallelism, especially on many-core processors. In this work, we propose worksharing tasks. These are tasks that internally leverage worksharing techniques to exploit fine-grained structured loop-based parallelism. The evaluation shows promising results on several benchmarks and platforms.

关键词： fine grained loop parallelism programming models runtime systems

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Automated rapid prototyping of regular grid-based numerical applications using generalized elemental subroutines

Automated rapid prototyping of regular grid-based numerical ...

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IEEE 27th International Parallel and Distributed Processing Symposium (IPDPS)

作者： Situ, Yingchong Wang, Ye Li, Zhiyuan Purdue Univ Dept Comp Sci W Lafayette IN 47907 USA

ISBN: (纸本)9780769549712

Computational scientists and engineers commonly rely on established software libraries to achieve high performance and reliability in their numerical applications. Unfortunately, this approach does not work well if the desired functionality is absent in existing libraries or if the integration is difficult. In such scenarios, one is often forced to explore alternative algorithms and in-house implementations. Such exploration can be a challenging task for computational scientists and engineers without sufficient computer science background. To address this issue, we design and build an automated rapid prototyping tool for regular grid-based numerical applications. This new tool allows programmers to specify algorithms as composition of familiar computation patterns such as those easily found in open literature expressed as generalized elemental subroutines. The tool then automatically transforms such subroutines into code which adapts to the prescribed data structures and delivers performance expected from the underlying algorithms. We demonstrate the tool in use cases including a production-grade computational fluid dynamic application.

关键词： compiler analysis and optimization program transformation programming models

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Evaluation of the Global Address Space programming Interface (GASPI) 28

Evaluation of the Global Address Space Programming Interface...

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28th IEEE International Parallel & Distributed Processing Symposium Workshops (IPDPSW)

作者： Breitbart, Jens Schmidtobreick, Mareike Heuveline, Vincent Tech Univ Munich Lehrstuhl Rechnertech & Rechnerorg Parallelrechne Munich Germany Heidelberg Univ Engn Math & Comp Lab Heidelberg Germany

ISBN: (纸本)9781479941162

The first exascale supercomputers are expected by the end of this decade and will presumably feature an increase in core count, but a decrease in the amount of memory available per core. As of now, it is still unclear if the current programming models will provide high performance on exascale systems. One programming model considered to be an alternative to MPI is the so-called partitioned global address space (PGAS) model. Within this paper we evaluate a relatively new PGAS API: the Global Address Space programming Interface (GASPI) and compare it to MPI on the basis of microbenchmarks. These benchmarks show that GASPI provides about the same level of performance for single-threaded communication, but is up to an order of magnitude faster than both Intel and IBM MPI for multi-threaded communication. Hereafter, we discuss the different features of GASPI in comparison to two main PGAS languages, namely UPC and CAF. In addition, we present a basic numerical algorithm, a dense matrix-matrix multiplication, as an example on how an implementation can make efficient use of GASPI's features, especially the asynchronous and one-sided communication mechanisms.

关键词： PGAS one-sided communication programming models GASPI

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Towards High Performance Resilience Using Performance Portable Abstractions 27th

Towards High Performance Resilience Using Performance Portab...

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27th International European Conference on Parallel and Distributed Computing (Euro-Par)

作者： Morales, Nicolas Teranishi, Keita Nicolae, Bogdan Trott, Christian Cappello, Franck Sandia Natl Labs Livermore CA 94550 USA Sandia Natl Labs POB 5800 Albuquerque NM 87185 USA Argonne Natl Lab Chicago IL USA

ISBN: (纸本)9783030856656;9783030856649

In the drive towards Exascale, the extreme heterogeneity of supercomputers at all levels places a major development burden on HPC applications. To this end, performance portable abstractions such as those advocated by Kokkos, RAJA and HPX are becoming increasingly popular. At the same time, the unprecedented scalability requirements of such heterogeneous components means higher failure rates, motivating the need for resilience in systems and applications. Unfortunately, state-of-art resilience techniques based on checkpoint/restart are lagging behind performance portability efforts: users still need to capture consistent states manually, which introduces the need for fine-tuning and customization. In this paper we aim to close this gap by introducing a set of abstractions that make it easier for the application developers to reason about resilience. To this end, we extend the existing abstractions proposed by performance portability efforts towards resilience. By marking critical data structures that need to be checkpointed, one can enable an optimized runtime to automate checkpoint-restart using high performance and scalable asynchronously techniques. We illustrate the feasibility of our proposal using a prototype that combines the Kokkos runtime (HPC performance portability), with the VELOC runtime (large-scale low overhead checkpoint-restart). Our experimental results show negligible performance overhead compared with a manually tuned implementation of checkpoint-restart while requiring minimal changes in the application code.

关键词： Performance portability Resilience Fault tolerance Checkpointing programming models

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Synthesis of Approximate Parametric Circuits for Variational Quantum Algorithms 5

Synthesis of Approximate Parametric Circuits for Variational...

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2024 International Conference on Quantum Computing and Engineering

作者： Burgstahler, Blake Wilson, Ellis Pakin, Scott Mueller, Frank North Carolina State Univ Raleigh NC 27695 USA Los Alamos Natl Lab Los Alamos NM USA

ISBN: (纸本)9798331541378

This work presents a novel approach to synthesize approximate circuits for the ansatze of variational quantum algorithms (VQA) and demonstrates its effectiveness in the context of solving integer linear programming (ILP) problems. Synthesis is generalized to produce parametric circuits in close approximation of the original circuit and to do so offline. This removes synthesis from the (online) critical path between repeated quantum circuit executions of VQA. We hypothesize that this approach will yield novel high fidelity results beyond those discovered by the baseline without synthesis. Simulation and real device experiments complement the baseline in finding correct results in many cases where the baseline fails to find any and do so with on average 32% fewer CNOTs in circuits.

关键词： circuit synthesis circuit-model quantum computing programming models QAOA VQA

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Cutty: Aggregate Sharing for User-Defined Windows 16

Cutty: Aggregate Sharing for User-Defined Windows

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25th ACM International Conference on Information and Knowledge Management (CIKM)

作者： Carbone, Paris Traub, Jonas Katsifodimos, Asterios Haridi, Seif Markl, Volker KTH Royal Inst Technol Stockholm Sweden Tech Univ Berlin Berlin Germany DFKI Saarbrucken Germany

ISBN: (纸本)9781450340731

Aggregation queries on data streams are evaluated over evolving and often overlapping logical views called windows. While the aggregation of periodic windows were extensively studied in the past through the use of aggregate sharing techniques such as Panes and Pairs, little to no work has been put in optimizing the aggregation of very common, non-periodic windows. Typical examples of non-periodic windows are punctuations and sessions which can implement complex business logic and are often expressed as user-defined operators on platforms such as Google Dataflow or Apache Storm. The aggregation of such non-periodic or user-defined windows either falls back to expensive, best-effort aggregate sharing methods, or is not optimized at all. In this paper we present a technique to perform efficient aggregate sharing for data stream windows, which are declared as user-defined functions (UDFs) and can contain arbitrary business logic. To this end, we first introduce the concept of User-Defined Windows (UDWs), a simple, UDF-based programming abstraction that allows users to programmatically define custom windows. We then define semantics for UDWs, based on which we design Cutty, a low-cost aggregate sharing technique. Cutty improves and outperforms the state of the art for aggregate sharing on single and multiple queries. Moreover, it enables aggregate sharing for a broad class of non-periodic UDWs. We implemented our techniques on Apache Flink, an open source stream processing system, and performed experiments demonstrating orders of magnitude of reduction in aggregation costs compared to the state of the art.

关键词： data structures data stream aggregation programming models operator sharing data stream processing data streams data stream optimisation data stream windows functional programming user-defined functions databases

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Addressing Global Data Dependencies in Heterogeneous Asynchronous Runtime Systems on GPUs 3

Addressing Global Data Dependencies in Heterogeneous Asynchr...

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3rd IEEE International Workshop on Extreme Scale programming models and Middleware (ESPM2)

作者： Peterson, Brad Humphrey, Alan Schmidt, John Berzins, Martin Univ Utah Sci Comp & Imaging Inst Salt Lake City UT 84112 USA

ISBN: (纸本)9781450351331

Large-scale parallel applications with complex global data dependencies beyond those of reductions pose significant scalability challenges in an asynchronous runtime system. Internodal challenges include identifying the all-to-all communication of data dependencies among the nodes. Intranodal challenges include gathering together these data dependencies into usable data objects while avoiding data duplication. This paper addresses these challenges within the context of a large-scale, industrial coal boiler simulation using the Uintah asynchronous many-task runtime system on GPU architectures. We show significant reduction in time spent analyzing data dependencies through refinements in our dependency search algorithm. Multiple task graphs are used to eliminate subsequent analysis when task graphs change in predictable and repeatable ways. Using a combined data store and task scheduler redesign reduces data dependency duplication ensuring that problems fit within host and GPU memory. These modifications did not require any changes to application code or sweeping changes to the Uintah runtime system. We report results running on the DOE Titan system on 119K CPU cores and 7.5K GPUs simultaneously. Our solutions can be generalized to other task dependency problems with global dependencies among thousands of nodes which must be processed efficiently at large scale.

关键词： Data dependencies Asynchronous Many-Task programming models Runtime Systems Scalability GPU Uintah Coal Boiler Radiative Heat Transfer

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THE EXACT LIKELIHOOD FUNCTION FOR AN EMPIRICAL JOB SEARCH MODEL

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ECONOMETRIC THEORY 1991年第4期7卷 464-486页

作者： CHRISTENSEN, BJ KIEFER, NM CORNELL UNIV ITHACANY 14853

The exact likelihood function for a prototypal job search model is analyzed. The optimality condition implied by the dynamic programming framework is fully imposed. Using the optimality condition allows identification of an offer arrival probability separately from an offer acceptance probability. The estimation problem is nonstandard. The geometry of the likelihood function in finite samples is considered, along with asymptotic properties of the maximum likelihood estimator.

关键词： Economic models Maximum likelihood estimation Mathematical theorems Dynamic programming Job hunting programming models Dynamic modeling Wages Unemployment

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WCSim: A Cloud Computing Simulator with Support for Bag of Tasks Workflows 35

WCSim: A Cloud Computing Simulator with Support for Bag of T...

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35th IEEE International Symposium on Computer Architecture and High Performance Computing (SBAC-PAD)

作者： dos Santos, Maicon Anca Grabher, Gabriel J. A. Kovaleski, Matheus F. Geyer, Claudio F. R. Cavalheiro, Gerson Geraldo H. Univ Fed Pelotas PPGC Pelotas RS Brazil Univ Grenoble Alpes LIG Grenoble France Univ Fed Rio Grande do Sul II Porto Alegre RS Brazil

ISBN: (纸本)9798350305487

In this paper, we present WCSim, Workflow Cloud Simulator. Firstly, we argue that this cloud simulation tool offers a high level of accessibility by allowing the description of various components, such as users, infrastructures, and workload, of a given scenario simply by providing parameters at launch time, without requiring the extension of the simulator code. Then, we explain how we conceived the components for the simulation models and provide a detailed description of the implemented software. Additionally, we compare the results of a small scenario obtained from two other simulation tools with those provided by WCSim. Finally, we present a case study that illustrates the usage of WCSim. The paper also introduces the a abstraction to model workflows as a Direct Acyclic Graph of Bag of Tasks.

关键词： Cloud Simulators Simulation Cloud Computing programming models Performance Evaluation

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