| 1. |
- Gidenstam, Anders, et al.
(författare)
-
Scalable group communication supporting configurable levels of consistency
- 2013
-
Ingår i: Concurrency Computation Practice and Experience. - : Wiley. - 1532-0634 .- 1532-0626. ; 25:5, s. 649-671
-
Tidskriftsartikel (refereegranskat)abstract
- Group communication is deployed in many evolving Internet-scale cooperative applications such as multiplayer online games and virtual worlds to efficiently support interaction on information relevant to a potentially very large number of users or objects. Especially peer-to-peer based group communication protocols have evolved as a promising approach to allow intercommunication between many distributed peers. Yet, the delivery semantics of robust and scalable protocols such as gossiping is not sufficient to support consistency semantics beyond eventual consistency because no relationship on the order of events is enforced. On the other hand, traditional consistency models provided by reliable group communication providing causal or even total order are restricted to support only small groups.This article proposes the cluster consistency model which bridges the gap between traditional and current approaches in supporting both scalability and ordered event delivery. We introduce a dynamic and fault tolerant cluster management method that can coordinate concurrent access to resources in a peer-to-peer system and can be used to establish fault-tolerant configurable cluster consistency with predictable reliability, running on top of decentralised probabilistic protocols supporting scalable group communication. This is achieved by a general two-layered architecture that can be applied on top of the standard Internet communication layers and offers a modular, layered set of services to the applications that need them. Further, we present a fault-tolerant method implementing causal cluster consistency with predictable reliability, running on top of decentralised probabilistic protocols supporting group communication.This paper provides analytical and experimental evaluation of the properties regarding the fault tolerance of the approach. Furthermore, our experimental study, conducted by implementing and evaluating the two-layered architecture on top of standard Internet transport services, shows that the approach scales well, imposes an even load on the system, and provides high-probability reliability guarantees.
|
|
| 2. |
- Hashemian, Raoufehsadat, et al.
(författare)
-
Characterizing the Scalability of a Web Application on a Multi-core Server
- 2014
-
Ingår i: Concurrency and Computation: Practice and Experience. - : John Wiley & Sons. - 1532-0626 .- 1532-0634. ; 26:12, s. 2027-2052
-
Tidskriftsartikel (refereegranskat)abstract
- The advent of multi‒core technology motivates new studies to understand how efficiently Web servers utilize such hardware. This paper presents a detailed performance study of a Web server application deployed on a modern eight‒core server. Our study shows that default Web server configurations result in poor scalability with increasing core counts. We study two different types of workloads, namely, a workload with intense TCP/IP related OS activity and the SPECweb2009 Support workload with more application‒level processing. We observe that the scaling behaviour is markedly different for these workloads, mainly because of the difference in the performance of static and dynamic requests. While static requests perform poorly when moving from using one socket to both sockets in the system, the converse is true for dynamic requests. We show that, contrary to what was suggested by previous work, Web server scalability improvement policies need to be adapted based on the type of workload experienced by the server. The results of our experiments reveal that with workload‒specific Web server configuration strategies, a multi‒core server can be utilized up to 80% while still serving requests without significant queuing delays; utilizations beyond 90% are also possible, while still serving requests with ‘acceptable’ response times.
|
|
| 3. |
- Kessler, Christoph, et al.
(författare)
-
Optimized composition of performance-aware parallel components
- 2012
-
Ingår i: Concurrency and Computation. - : John Wiley and Sons. - 1532-0626 .- 1532-0634. ; 24:5, s. 481-498
-
Tidskriftsartikel (refereegranskat)abstract
- We describe the principles of a novel framework for performance-aware composition of sequential and explicitly parallel software components with implementation variants. Automatic composition results in a table-driven implementation that, for each parallel call of a performance-aware component, looks up the expected best implementation variant, processor allocation and schedule given the current problem, and processor group sizes. The dispatch tables are computed off-line at component deployment time by an interleaved dynamic programming algorithm from time-prediction meta-code provided by the component supplier.
|
|
| 4. |
- Podobas, Artur, 1982-, et al.
(författare)
-
A comparative performance study of common and popular task-centric programming frameworks
- 2013
-
Ingår i: Concurrency and Computation. - : Wiley. - 1532-0626 .- 1532-0634.
-
Tidskriftsartikel (refereegranskat)abstract
- SUMMARY: Programmers today face a bewildering array of parallel programming models and tools, making it difficult to choose an appropriate one for each application. An increasingly popular programming model supporting structured parallel programming patterns in a portable and composable manner is the task-centric programming model. In this study, we compare several popular task-centric programming frameworks, including Cilk Plus, Threading Building Blocks, and various implementations of OpenMP 3.0. We have analyzed their performance on the Barcelona OpenMP Tasking Suite benchmark suite both on a 48-core AMD Opteron 6172 server and a 64-core TILEPro64 embedded many-core processor. Our results show that the OpenMP offers the highest flexibility for programmers, and this flexibility comes to a cost. Frameworks supporting only a specific and more restrictive model, such as Cilk Plus and Threading Building Blocks, are generally more efficient both in terms of performance and energy consumption. However, Intel's implementation of OpenMP tasks performs the best and closest to the specialized run-time systems.
|
|
| 5. |
|
|
| 6. |
- Wang, Jiechen, et al.
(författare)
-
A parallel algorithm for constructing Voronoi diagrams based on point-set adaptive grouping
- 2014
-
Ingår i: Concurrency and Computation. - : Wiley. - 1532-0626 .- 1532-0634. ; 26:2, s. 434-446
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a parallel algorithm for constructing Voronoi diagrams based on point-set adaptive grouping. The binary tree splitting method is used to adaptively group the point set in the plane and construct sub-Voronoi diagrams for each group. Given that the construction of Voronoi diagrams in each group consumes the majority of time and that construction within one group does not affect that in other groups, the use of a parallel algorithm is suitable.After constructing the sub-Voronoi diagrams, we extracted the boundary points of the four sides of each sub-group and used to construct boundary site Voronoi diagrams. Finally, the sub-Voronoi diagrams containing each boundary point are merged with the corresponding boundary site Voronoi diagrams. This produces the desired Voronoi diagram. Experiments demonstrate the efficiency of this parallel algorithm, and its time complexity is calculated as a function of the size of the point set, the number of processors, the average number of points in each block, and the number of boundary points.
|
|
| 7. |
- Xhafa, Fatos, et al.
(författare)
-
Grid and P2P middleware for wide-area parallel processing
- 2011
-
Ingår i: Concurrency and Computation. - : John Wiley & Sons. - 1532-0626 .- 1532-0634. ; 23:5, s. 458-476
-
Tidskriftsartikel (refereegranskat)abstract
- Grid computing emerged as a paradigm for high-performance computing and massive parallel processing. Currently, Grid systems have become an important paradigm for efficiently solving large-scale complex problems from many fields. On the other hand, P2P paradigm originated from file-sharing, but each time more is being used for the development of large-scale distributed platforms. Grid and P2P systems have thus followed different trajectories pushed by different motivations, needs and research communities. In fact, both paradigms are evolving in a way that each time they are sharing more common characteristics and are mutually benefiting from their best features. Among these characteristics, we could distinguish the cooperative model for solving complex problems by exploiting their large computing capacity. As such, Grid and P2P systems have achieved notable success, in particular, for e-Science applications, a family of complex applications arising in science and engineering that need considerable computation power. Despite important advances in the design and use of Grid and P2P systems, they remain still difficult to implement and apply to real-life problems. The main difficulties reside in the lack of easy-to-use middleware for Grid and P2P, in the complexities of setting up and in the tedious task of deploying real-world Grid/P2P platforms as well as in experimental studies which are often complex and not easy to repeat. In this paper we survey and analyze the advances in communication libraries and middleware for both Grid and P2P systems as well as their limitations when used in real Grid and P2P infrastructures. We also bring examples of real-life applications of massive data processing that can be efficiently handled through Grid and P2P approaches.
|
|
