• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.1B
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• pp.59-66
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• 2012

The use of MPSoC has been increasing because of a rise of use of mobile devices and complex applications. For improving the performance of MPSoC, number of processor has been increasing. Standard MPI is used for efficiently sending data in distributed memory architecture that has advantage in multi processor. Standard In this paper, we propose a scalable distributed memory system with a low cost hardware message passing interface(MPI). The proposed architecture improves transfer rate with buffered send for small size packet. Three queues, Ready Queue, Request Queue, and Reservation Queue, work as previous architecture, and two queues, Small Ready Queue and Small Request Queue, are added to send small size packet. When the critical point is set 8 bytes, the proposed architecture takes more than 2 times the performance improvement in the data that below the critical point.

• Journal of Korean Institute of Industrial Engineers
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• v.6 no.1
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• pp.1-7
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• 1980

An exact solution technique for M/M/s multi-server demanding queue is introduced, and a general form of the curves representing service rates of the system is presented. As the number of customers in the system increases, the service rate is shown to increase initially, then decrease, and finally converge to a certain value. It is also shown that this phenomenon persists regardless of the numbers of servers and customer types.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.7
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• pp.63-73
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• 2004

This paper proposes an efficient centralized sin91e buffer management algorithm to arbitrate access contention mon processors on the multi-processor system for high-speed Packet filtering and proves that the algorithm provides reasonable performance by implementing it and applying it to a real multi-processor system. The multi-processor system for parallel packet filtering is modeled based on a network processor to distribute the packet filtering rules throughout the processors to speed up the filtering. In this paper we changed the number of processors and the processing time of the filtering rules as variables and measured the packet transfer rates to investigate the performance of the proposed algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.4
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• pp.1035-1044
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• 1998

A new multi-channel access scheme and the associated network architecture for a single-hop WDM local area network is proposed in this paper. The proposed architecture has Central Scheduling Node (CSN) for the transmission coordination among many users, which is one of the key issues in single-hop WDM networks. The data channels, source nodes, and destination nodes are selected at CSN in very simple menner. Our scheme can relive the control processing overhead at all nodes in the network which is caused in existing distributed scheduling algorithms. CSN is simple in the architecture can be implemented easily. in respect to the network performance, the maximum obtainable throughput is up to that of the ideal output queuing because of collision free scheduling. We use the MQMS (multi-queue multi-server) model for performance analaysis.

• Journal of the Korea Society of Computer and Information
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• v.16 no.1
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• pp.133-142
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• 2011

When TCP operates in multi-hop wireless networks, it suffers from severe performance degradation due to the different characteristics of wireless networks and wired networks. This is because TCP reacts to wireless packet losses by unnecessarily decreasing its sending rate assuming the losses as congestion losses. Although several loss differentiation algorithms (LDAs) have been proposed to avoid such performance degradation, their detection accuracies are not high as much as we expect. In addition the schemes have a tendency to sacrifice the detection accuracy of congestion losses while they improve the detection accuracy of wireless losses. In this paper, we suggest a new sender-based loss differentiation scheme which enhances the detection accuracy of wireless losses while minimizing the sacrifice of the detection accuracy of congestion losses. Our scheme estimates the rate of queue usage which is highly correlated with the congestion in the network path between a TCP sender and a receiver, and it distinguishes congestion losses from wireless losses by comparing the estimated queue usage with a certain threshold. In the extensive experiments based on a network simulator, QualNet, we measure and compare each detection accuracy of wireless losses and congestion losses, and evaluate the performance enhancement in each scheme. The results show that our scheme has the highest accuracy among the LDAs and it improves the most highly TCP performance in multi-hop wireless networks.

• Proceedings of the Korean Information Science Society Conference
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• 2001.04a
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• pp.316-318
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• 2001

통합 서비스 망은 다양한 트래픽 소스의 다양한 지원을 필요로 한다. 본 논문은 패킷 스케줄링 알고리즘 중 WFQ와 SFQ를 비교 분석하여 성능을 비교한 후 다양한 트래픽 소스를 전송하기 위해 제안된 방법을 WFQ와 SFQ 스케줄링 알고리즘에 적용하여 비교 분석 할 것이다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.1B
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• pp.86-92
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• 2011

In this paper, we propose a novel hardware MPI(Message Passing Interface) unit which supports message passing in multiprocessor system which use distributed memory architecture. MPI Hardware unit processes data synchronization, transmission and completion, and it supports processor non-blocking operation so it reduces overhead according to synchronization. Additionally, MPI hardware unit combines ready entry, request entry, reserve entry which save and manage the synchronized messages and performs the multiple outstanding issue and out of order completion. According to BFM(Bus Functional Model) simulation result, the performance is increased by 25% on many to many communication. After we designed MPI unit using HDL, with synopsys design compiler we synthesized, and for synthesis library we used MagnaChip $0.18{\mu}m$. And then we making prototype chip. The proposed message transmission interface hardware shows high performance for its increase in size. Thus, as we consider low-cost design and scalability, MPI hardware unit is useful in increasing overall performance of embedded MPSoC(Multi-Processor System-on-Chip).

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.135-138
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• 2008

The existing protocol which processes sequentially synchronization has the problem where synchronization tasks which are requested subsequently from multiple client. Should be waited for a long time. In this paper, we propose a implementation of concurrent synchronization protocol that is capable of reducing the waiting time. If there are no update conflicts among different synchronization tasks, the proposed protocol synchronizes using the multi-queue based on the round-robin scheme, in order to reduce the waiting time.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.08a
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• pp.91-94
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• 2008

As the mobile devices and the wireless networks have high-performance capabilities, it is possible to synchronize the spatio-temporal data of a server with the spatio-temporal data of a mobile device which are collected at a field. However, since the server process the synchronization which the model device requests, the whole synchronizations of mass mobile devices take long time. In this paper, we propose the scheme to process concurrently the synchronizations of mobile devices which does not conflict with others using the scheme of a multi-queue.

• Journal of KIISE:Databases
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• v.28 no.3
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• pp.373-383
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• 2001

The distance join is a spatial join which finds data pairs in the order of distance when associating two spatial data sets. This paper proposes several methods to optimize the adaptive multi-stage distance join, presented in [1]. First, we optimize the sweeping index formula which is used for selecting sweeping axis during plane sweeping. Second, to improve the performance of a priority queue used for maintaining node pairs, we propose to use the maximum distance of a node pair as the second priority of the queue. Moreover, we compare trade-offs in estimating the cut-off distance between under uniformity assumption of data distribution and non-uniformity assumption. The experiments show that the proposed methods greatly improve the performance of the algorithm in CPU cost as well as in I/O cost.