Browsing by Author "Chua, HT"

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A release combined scheduling scheme for non-uniform dependence loops
(2002-03-01)
Pean, DL
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Chua, HT
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Chen, C
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資訊工程學系
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Department of Computer Science
In general, synchronization mechanisms can be used to preserve dependence constraints in any nested loop, and can be combined with a loop scheduling scheme to form a uniform framework to obtain the correct execution order and balance workload distribution. Most current scheduling mechanisms cannot handle non-uniform dependence loops. In this paper, we propose a new combined scheduling scheme called Release Combined Scheduling for Non-uniform Dependence Loops (RCS) to schedule non-uniform dependence doubly-nested loops in multiprocessor systems. It combines both static and dynamic scheduling mechanisms in order to optimize the system performance. In our approach, initialisation of a set of scheduling information is based on the concept of the minimum dependence distance. During runtime, scheduling information is used to adjust the number of parallelizable iterations. Our method is able to discover more parallelism from a given non-uniform dependence doubly-nested loop than is possible with previous approaches. The experimental results show that the RCS method reliably exploits parallelism and outperforms most of the existing non-uniform dependence loop scheduling schemes by 20.29%, on average.
Design of a scalable multiprocessor architecture and its simulation
(2001-09-01)
Pean, DL
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Wu, CC
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Chua, HT
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Chen, C
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資訊工程學系
Performance enhancement and system scalability are two of the most important issues in the design of multiprocessor systems. A scalable cluster-based multiprocessor architecture and its simulation environment called SEECMA are proposed. Several new issues in our architecture, including scalable cache coherence protocols, relaxed memory consistency models, memory optimization techniques and several types of processors are considered. It has been developed to meet current trends in clustering architecture design. Additionally, the SEECMA environment is presented as a helpful investigation tool for both education and research. In addition to many simulation options. it is provided with a user-friendly graphic interface. SEECMA can automatically collect data from several simulation runs and display the results for comparison. So far. we have evaluated several vital issues of cluster-based multiprocessors on SEECMA including effective prefetching and replacement policies, and optimization of migratory sharing using both hardware and software mechanisms. On average, these enhance system performance by up to 8%, 9%, and 7%. respectively. Our cluster-based multiprocessor architecture also scales more readily than the current general, or cluster-based, multiprocessor environments. (C) 2001 Elsevier Science Inc. All rights reserved.
Effective parallelization techniques for non-uniform loops
(1998)
Pean, DL
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Wu, CC
;
Chua, HT
;
Chen, C
;
資訊科學與工程研究所
It is known that the parallelism of non-uniform dependence loops is difficult to extract and is not effectively explored by the existing parallelization methods. In this paper, we propose new techniques to transform non-uniform dependence loops efficiently, based on their irregularity, by which more parallelism can be explored directly and effectively. Several effective mechanisms, including parallelization part splitting, partial parallelization decomposition, irregular loop interchange and growing pattern rt detection are created to exploit more parallelism degree for non-uniform loop structures. Compared with other existing methods, our new approach gives better performance. When the loop bounds is increased from 5 to 50, based on our evaluations, the speedup achieves 3.25 to 19.8 times better than that of the uniformization technique; and from 1.5 to 8.33 times better than that of the minimum dependence distance tiling technique. We evaluate our mechanisms in our simulation environment for various conditions and discuss the performance of them in this paper.