• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권6호
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• pp.2078-2094
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• 2015

Now a days, Efficient processing of Broadcast Queries is of critical importance with the ever-increasing deployment and use of mobile technologies. BQs have certain unique characteristics that the traditional spatial query processing in centralized databases does not address. In novel query processing technique, by maintaining high scalability and accuracy, latency is reduced considerably in answering BQs. Novel approach is based on peer-to-peer sharing, which enables us to process queries without delay at a mobile host by using query results cached in its neighboring mobile peers. We design and evaluate cooperative caching techniques to efficiently support data access in ad hoc networks. We first propose two schemes: Cache Data, which caches the data, and Cache Path, which caches the data path. After analyzing the performance of those two schemes, we propose a hybrid approach (Hybrid Cache), which can further improve the performance by taking advantage of Cache Data and Cache Path while avoiding their weaknesses. Cache replacement policies are also studied to further improve the performance. Simulation results show that the proposed schemes can significantly reduce the query delay and message complexity when compared to other caching schemes.

• KIISE Transactions on Computing Practices
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• 제23권9호
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• pp.564-571
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• 2017

The burst loading of a pre-created cache-image is an effective method to reduce the instruction cache misses in the early stage of the program execution. It is useful to alleviate the performance degradation as well as the energy inefficiency, which is induced by the concentrated cold misses at the instruction cache. However, there are some defects, including software overhead on the compiler and installer. Furthermore, there are several mismatches as a result of the dynamic properties for specific applications. This paper addresses these issues and proposes a cache-image maintenance/recreation policy that can conduct dynamic management using a hardware-assisted method. The results of the simulation show that the proposed method can maintain the cache-image with a proper size and validity.

• Journal of KIISE:Computer Systems and Theory
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• 제27권3호
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• pp.324-336
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• 2000

The paper proposes an efficient buffer management scheme to enhance performance of the disk I/O system. Without any user level information, the proposed scheme automatically detects the block reference patterns of applications by associating block attributes with forward distance of a block. Based on the detected patterns, the scheme applies an appropriate replacement policy to each application. We also present a new block allocation scheme to improve the performance of buffer cache when kernel needs to allocate a cache block due to a cache miss. The allocation scheme analyzes the cache hit ratio of each application based on block reference patterns and allocates a cache block to maximize cache hit ratios of system. These all procedures are performed on-line, as well as automatically at system level. We evaluate the scheme by trace-driven simulation. Experimental results show that our scheme leads to significant improvements in hit ratios of cache blocks compared to the traditional schemes and requires low overhead.

• International Journal of Internet, Broadcasting and Communication
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• 제14권1호
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• pp.31-36
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• 2022

Interval caching is one of the representative caching strategies used in multimedia streaming systems. However, there has been no theoretical analysis on interval caching. In this paper, we present an optimality proof of the interval caching policy. Specifically, we propose a caching performance model for multimedia streaming systems and show the optimality of the interval caching policy based on this model.

• Journal of the Institute of Electronics Engineers of Korea SD
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• 제46권1호
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• pp.68-75
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• 2009

As the recent performance of microprocessor is improving quickly, the necessity of cache is growing because of the increase of the access time of main memory. Every block of direct-mapped cache maps to one cache line. Although the mapping rule is simple, if different blocks map to one cache line, the miss ratio will be higher than the set-associative cache due to conflicts. In this paper, for the improvement of the direct-mapped cache of OpenRISC, 4-way set-associative cache is proposed. Four blocks of the main memory of the proposed cache map to one cache line so that the miss ratio is less than the direct-mapped cache. Pseudo-LRU Policy, which is one of the Line Replacement Policies, is used for decreasing the number of bits that store LRU value. The OpenRISC core including the 4-way set-associative cache was verified with FPGA emulation. As the result of performance measurement using test program, the performance of the OpenRISC core including the 4-way set-associative cache is higher than the previous one by 50% and the decrease of miss ratio is more than 15%.

• Journal of the Korea Society of Computer and Information
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• 제25권6호
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• pp.99-107
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• 2020

In this paper, we analyze the characteristics of mobile cache, which is used to improve the data access speed when executing applications on mobile devices, and verify the importance of mobile cache through a cache data access experiment. The mobile device market has grown at a fast pace over the past decade; however, battery limitations and size, price considerations restrict the usage of fast hardware. Thus, their performance are supplemented by using a memory buffer structure such as the cache memory. The analysis mainly focuses on cache size, hierarchical structure of cache, cache replacement policy, and the effect these features has on mobile performance. For the experimental data, we applied a data set from a microprocessor system study, originally used to test the cache performance. In the experimental results, the average data access speed on a mobile device showed a performance improvement of up to 10 times with the presence of cache memory than without. Accordingly, the cache memory was helpful for the performance improvement of a mobile device when the specifications were identical.

• The KIPS Transactions:PartA
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• 제13A권6호
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• pp.511-516
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• 2006

The data grid computing provides geographically distributed storage resources to solve computational problems with large-scale data. Unlike cache replacement policies in virtual memory or web-caching replacement, an optimal file replacement policy for data grids is the one of the important problems by the fact that file size is very large. The traditional file replacement policies such as LRU(Least Recently Used) LCB-K(Least Cost Beneficial based on K), EBR(Economic-based cache replacement), LVCT(Least Value-based on Caching Time) have the problem that they have to predict requests or need additional resources to file replacement. To solve theses problems, this paper propose SBR-k(Sized-based replacement-k) that replaces files based on file size. The results of the simulation show that the proposed policy performs better than traditional policies.

• Journal of KIISE:Computer Systems and Theory
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• 제29권6호
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• pp.346-353
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• 2002

The explosive increase of World Wide Web usage has incurred significant amount of network traffic and server load. To overcome these problems, web proxy caching replicates frequently requested documents in the web proxy closer to the users. Cache utilization depends on the replacement policy which tries to store frequently requested documents in near future. Temporal locality and Zipf frequency distribution, which are commonly observed in web proxy workloads, are considered as the important properties to predict the popularity of documents. In this paper, we propose a novel cache replacement policy, called Adaptive LFU (ALFU), which incorporates 1) Zipf frequency distribution by utilizing LFU and 2) temporal locality adaptively by measuring the amount of the popularity reduction of documents as time passed efficiently. We evaluate the performance of ALFU by comparing it to other policies via trace-driven simulation. Experimental results show that ALFU outperforms other policies.

• The Journal of the Korea institute of electronic communication sciences
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• 제16권6호
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• pp.1121-1132
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• 2021

Nowadays, it is more difficult to find people who do not use mobile devices such as smartphones and tablets. Contents that can be accessed at the touch of a finger is overflowing. However, the existing network has a structure in which it is difficult to efficiently respond to the problems caused by overflowing contents. In particular, the bottleneck problem that occurs when multiple users intensively request content from the server at the same time is a representative problem. To solve this problem, the CCN has emerged as an alternative to future networks. CCN uses the network bandwidth efficiently through the In-Network Cache function of the intermediate node to improve the traffic required for user to request to reach the server, to reduce response time, and to distribute traffic concentration within the network. I propose a cache policy that can improve efficiency in such a CCN environment.

• Proceedings of the IEEK Conference
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(3)
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• pp.153-156
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• 2002

As the use of world wide web is increasing, the number of connections to servers is increasing also. These interactions increase the load of networks and servers. therefore efficient caching strategies for web documents are needed to reduce server load and network traffics by migrating copies of server files closer to the clients that use those files. As One idea of caching policy, we propose a Weighted Disk Cache Replacement Policy(WDCRP) which analyses user's interaction to WWW and adds weight value to each web document. Especially the WDCRP takes account of the history data of cache log, the characteristics of Web requests and the importance of user interactive-actions.