| 171. |
- Nikolakopoulos, Ioannis, 1986, et al.
(författare)
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Enhancing Concurrent Data Structures with Concurrent Iteration Operations: Consistency and Algorithms
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Concurrent data structures provide the means to multi-threaded applications to share data.Data structures come with a set of predefined operations, specified by the semantics of the data structure.In the literature and in several contemporary commonly used programming environments,the notion of iterations has been introduced for collection data structures,as a bulk operation enhancing the native set of their operations.Iterations in several of these contexts are treated as sequential in nature and may freeze the data structure while operatingor provide a variety of consistency guarantees when running concurrently with the native operations of the data structures.In this work we study iterations in concurrent data structures with respect to their coexistence with the native operations of the latter and the guarantees that they provide under concurrency.Besides linearizability, we propose a set of consistency specifications for such bulk operations, including also concurrency-aware properties by building on Lamport's systematic definitions for registers.By using queues, fixed-domain sets and composite registers as case-studies of underlying objects, we show a set of constructions of iteration operations, satisfying these properties.Besides the trade-off between consistency and throughput, we demonstrate the trade-off between the overhead of the bulk operation and possible support (helping) by the native operations of the data structure. We show a set of algorithms that demonstrate these and study the implications on the efficiency of the implementations.
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| 172. |
- Nikolakopoulos, Ioannis, 1986, et al.
(författare)
-
Highly concurrent stream synchronization in many-core embedded systems
- 2016
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Ingår i: 4th ACM International Workshop on Many-Core Embedded Systems, MES 2016; Seoul; South Korea; (ACM International Conference Proceeding Series, vol 18). - New York, NY, USA : ACM. - 9781450342629 ; 18-22-June-2016, s. 2-9
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Konferensbidrag (refereegranskat)abstract
- Embedded many-core architectures are expected to serve as significant components in the infrastructure of upcoming technologies like networks for the Internet of Things (IoT), facing real-time and stream processing challenges. In this work we explore the applicability of ScaleGate, a synchronization object from the massive data stream processing domain, on many-core embedded systems. We propose a new implementation of ScaleGate on the Epiphany architecture, a scalable embedded many-core co-processor, and study communication patterns that appear in the context of a baseband signal processing application. Our experimental evaluation shows significant improvements over standard barrier-based approaches, due to the asynchrony exploited by the use of ScaleGate.
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| 173. |
- Nikolakopoulos, Ioannis, 1986, et al.
(författare)
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Of concurrent data structures and iterations
- 2015
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Ingår i: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics). - Cham : Springer International Publishing. - 1611-3349 .- 0302-9743. - 9783319240237 ; 9295, s. 358-369, s. 358-369
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Konferensbidrag (refereegranskat)abstract
- Bulk operations on data structures are widely used both on user-level but also on programming language level. Iterations are a good example of such bulk operations. In the sequential setting iterations are easy to design on top of an algorithmic construction of a data structure and is not considered as a challenge. In a concurrent environment, such as a multicore system, the situation is completely different and the issue of extending concurrent data structure designs to support iteration operations opens new research challenges in concurrent algorithmic data structure implementations, with respect to consistency and efficiency. In this paper we take a journey through this young and evolving research topic. More precisely we describe recent advances in the area together with an overview of iteration implementations that have appeared in the research literature as well as in widely-used programming environments and we outline a range of application targets and challenging future directions.
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| 174. |
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| 175. |
- Papadopoulos, L., et al.
(författare)
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A Systematic Methodology for Optimization of Applications Utilizing Concurrent Data Structures
- 2016
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Ingår i: IEEE Transactions on Computers. - 0018-9340. ; 65:7, s. 2019-2031
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Tidskriftsartikel (refereegranskat)abstract
- Modern multicore embedded systems often execute applications that rely heavily on concurrent data structures. The selection of efficient concurrent data structure implementations for a specific application is usually a complex and time consuming task, because each design decision often affects the performance and the energy consumption of the embedded system in various and occasionally unpredictable ways. The complexity is normally addressed by developers by adopting ad-hoc design solutions, which are often suboptimal and yield poor results. To face this problem, we propose a semi-automated methodology for the optimization of applications that utilize concurrent data structures that is based on design space exploration. The proposed approach is evaluated by using both microbenchmarks and real-world applications that are executed on multicore embedded systems with different architectural specifications. Our results show that we can identify various trade-offs between different data structure implementations that can be used to optimize applications that rely on concurrent data structures.
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| 176. |
- Papadopoulos, L., et al.
(författare)
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Customization methodology for implementation of streaming aggregation in embedded systems
- 2016
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Ingår i: Journal of Systems Architecture. - : Elsevier BV. - 1383-7621. ; 66-67, s. 48-60
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Tidskriftsartikel (refereegranskat)abstract
- Streaming aggregation is a fundamental operation in the area of stream processing and its implementation provides various challenges. Data flow management is traditionally performed by high performance computing systems. However, nowadays there is a trend of implementing streaming operators in low power embedded devices, due to the fact that they often provide increased performance per watt in comparison with traditional high performance systems. In this work, we present a methodology for the customization of streaming aggregation implemented in modern low power embedded devices. The methodology is based on design space exploration and provides a set of customized implementations that can be used by developers to perform trade-offs between throughput, latency, memory and energy consumption. We compare the proposed embedded system implementations of the streaming aggregation operator with the corresponding HPC and GPGPU implementations in terms of performance per watt. Our results show that the implementations based on low power embedded systems provide up to 54 and 14 times higher performance per watt than the corresponding Intel Xeon and Radeon HD 6450 implementations, respectively. (C) 2016 Elsevier B.V. All rights reserved.
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| 177. |
- Papadopoulos, L., et al.
(författare)
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Evaluation of message passing synchronization algorithms in embedded systems
- 2014
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Ingår i: 14th International Conference on Embedded Computer Systems: Architectures, Modeling and Simulation, SAMOS 2014. - 9781479937707 ; , s. 282-289
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Konferensbidrag (refereegranskat)abstract
- The constantly increasing computational power of the embedded systems is based on the integration of a large number of cores on a single chip. In such complex platforms, the synchronization of the accesses of the shared memory data is becoming a major issue, since it affects the performance of the whole system. This problem, which is currently a challenge in the embedded systems, has been studied in the High Performance Computing domain, where several message passing algorithms have been designed to efficiently avoid the limitations coming from locking. In this work, inspired from the work on message passing synchronization algorithms in the High Performance Computing domain we design and evaluate a set of synchronization algorithms for multi-core embedded platforms. We compare them with the corresponding lock-based implementations and prove that message passing synchronization algorithms can be efficiently utilized in multi-core embedded systems. By using message passing synchronization instead of lock-based, we managed to reduce the execution time of our benchmark up to 29.6%.
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| 178. |
- Papadopoulos, L., et al.
(författare)
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Performance and power consumption evaluation of concurrent queue implementations in embedded systems
- 2015
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Ingår i: Computer Science - Research and Development. - : Springer Science and Business Media LLC. - 1865-2034 .- 1865-2042. ; 30:2, s. 165-175
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Tidskriftsartikel (refereegranskat)abstract
- Embedded and high performance computing (HPC) systems face many common challenges. One of them is the synchronization of the memory accesses in shared data. Concurrent queues have been extensively studied in the HPC domain and they are used in a wide variety of HPC applications. In this work, we evaluate a set of concurrent queue implementations in an embedded platform, in terms of execution time and power consumption. Our results show that by taking advantage of the embedded platform specifications, we achieve up to 28.2 % lower execution time and 6.8 % less power dissipation in comparison with the conventional lock-based queue implementation. We show that HPC applications utilizing concurrent queues can be efficiently implemented in embedded systems and that synchronization algorithms from the HPC domain can lead to optimal resource utilization of embedded platforms.
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| 179. |
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| 180. |
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