• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.5
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• pp.2319-2337
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• 2019

In this paper, we study the distributed cooperative caching for Internet content providers in a small cell of heterogeneous network (HetNet). A general framework based on bankruptcy game model is put forth for finding the optimal caching policy. In this framework, the small cell and different content providers are modeled as bankrupt company and players, respectively. By introducing strategic decisions into the bankruptcy game, we propose a caching value assessment algorithm based on analytic hierarchy process in the framework of bankruptcy game theory to optimize the caching strategy and increase cache hit ratio. Our analysis shows that resource utilization can be improved through cooperative sharing while considering content providers' satisfaction. When the cache value is measured by multiple factors, not just popularity, the cache hit rate for user access is also increased. Simulation results show that our approach can improve the cache hit rate while ensuring the fairness of the distribution.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.11a
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• pp.1127-1128
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• 2023

캐시는 현대 컴퓨터 시스템에서 중요한 성능 개선 요소 중 하나로, 효율적인 데이터 저장 및 액세스를 보장한다. 교체 정책은 캐시의 한정된 용량 내에서 어떤 데이터를 보관하고 어떤 데이터를 대체할지 결정하는 데 중요한 역할을 한다. 이 논문은 Pseudo LRU 와 LRU 교체 정책을 대상으로 cache 에서의 throughput 과 gate count 를 각각 비교한다. LRU 방식을 적용한 cache 와 Pseudo LRU 방식을 적용한 cache 는 Locality 0 과 100 에서 0.001GB/s 미만의 차이를 보이며 각각 0.095GB/s, 0.211GB/s 로 동일했으며 Gate Count 는 각각 134,516 과 130,016 으로 4500 의 감소 효과가 있었다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.1
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• pp.71-76
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• 2022

Buffer cache bridges the performance gap between memory and storage, but its effectiveness is limited due to periodic flush, performed to prevent data loss in smartphones. This paper shows that selective flushing technique with small persistent memory can reduce the flushing overhead of smartphone buffer cache significantly. This is due to our I/O analysis of smartphone applications in that a certain hot data account for most of file writes, while a large proportion of file data incurs single-writes. The proposed selective flushing policy performs flushing to persistent memory for frequently updated data, and storage flushing is performed only for single-write data. This eliminates storage write traffic and also improves the space efficiency of persistent memory. Simulations with popular smartphone application I/O traces show that the proposed policy reduces write traffic to storage by 24.8% on average and up to 37.8%.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.777-778
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• 2006

In this thesis, we design and implement a Flash Cache Core Module (FCCM) which operates on the YAFFS NAND flash memory. The FCCM applies memory replacement policy and prefetching policy based on the page reference pattern of applications. Also, implement the Clean-First memory replacement technique considering the characteristics of flash memory. In this method the decision is made according to page hit to apply prefetched waiting area. The FCCM decrease I/O hit frequency up to 37%, Compared with the linux cache and prefetching policy. Also, it operated using less memory for prefetching(maximum 24% and average 16%) compared with the linux kernel.

• The Transactions of the Korea Information Processing Society
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• v.7 no.12
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• pp.3964-3975
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• 2000

There are two policies for maintaining consistency among the multiple processor caches in a multiprocessor system: Write invalidate and Write update. In the write invalidate policy, whenever a processor attempt to write its cached block, it has to invalidate all the same copies of the updated block in the system. As a results of this frequent invalidations, this policy results in high cache miss ratio. On the other hand, the write update policy renew them, instead of invalidating all the same copies. This policy has to transfer the updated contents through interconnection network, whether the updated block is ptivate or not. Therefore the network suffer from heavy transaction traffic. In this paper we present an efficient cache coherence protocol for shared memory multiprocessor system connected by slotted ring. This protocol is based on the write update policy, but the updated contents are transferred only in case of updating the shared block. Otherwise, if the updated block is private, the updated contents are not transferred. We analyze the proposed protocol and enforce simulation to compare it with previous version.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.6
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• pp.1095-1102
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• 2023

Content Centric Network (CCN) is a network that emerged to improve the existing network structure and communicates based on content names instead of addresses. It utilises caches to distribute traffic and reduce response time by delivering content from intermediate nodes. In this paper, we propose a popularity-based caching policy to efficiently utilise the limited CS space in CCN environment. The performance of CCNs can vary significantly depending on which content is prioritised to be stored and released. To achieve the most efficient cache replacement, we propose a real-time content popularity-based efficient cache replacement policy that calculates and prioritises content popularity based on constructor popularity, constructor distance, and content hits, and demonstrate the effectiveness of the new policy through experiments.

• Journal of KIISE:Databases
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• v.29 no.2
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• pp.148-157
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• 2002

Caching in meta-search engines can improve the response time of users' request. We describe the cache scheme in our meta-search engine in terms of its architecture and operational flow. In particular, we propose a popularity-driven cache algorithm that utilizes popularities of queries to determine cached data to be purged. The popularity is a value that represents the normalized occurrence frequency of user queries. This paper presents how to collect popular queries and how to calculate query popularities. An empirical performance evaluation of the popularity-driven caching with the traditional schemes (i.e., least recently used (LRU) and least frequently used (LFU)) has been carried out on a collection of real data. In almost all cases, the proposed replacement policy outperforms LRU and LFU.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.11
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• pp.643-657
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• 2004

The chordal ring based CC-NUMA system contains many links to transmit transactions between a local node and a remote node because of its structural characteristics. However, the inclination that the transactions concentrate on the ring link increases both the traffic of the ring link and the response time, which degrades the overall performance of the chordal ring based CC-NUMA system. In this paper we suggest a new remote cache replacement policy that considers both the number of total links and the number of ring links to traverse for the transactions. Our proposed replacement policy can balance data between the ring link and the chordal link properly because it reflects the characteristics of chordal ring based CC-NUMA system well.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10c
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• pp.346-348
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• 2000

전통적일 파일 캐쉬나 가상 메모리 시스템과 웹 캐쉬는 다르다. 웹 캐쉬는 WWW상에서 작게는 수백 바이트에서 크게는 수십 메가바이트에 이르는 다양한 크기의 개체를 다루어야 한다. 다양한 크기의 개체를 다루는데 따른 문제점은 캐쉬 성능을 판단하는 매트릭스가 단순한 hit rate가 아니라는 것이다. 기본적인 웹 캐쉬의 성능 매트릭스로는 HR(cache hit rate)와 BHR(byte cache hit rate)가 있으며, 기존에 제시된 캐쉬 정책들은 두 가지 중 하나만을 만족하거나 아니면 어느 것도 만족하지 않는 경우가 대부분이다. 트레이스 드리븐 방식을 이용한 시뮬레이션을 통하여, 기존에 우수성이 입증된 캐쉬 대체 정책과 우리가 제시한 TYPE 대체 정책을 HR과 BHR을 기준으로 비교한다. 우리가 제시한, 파일 타입에 대해 동적으로 할당된 캐쉬 공간을 갖는 캐쉬 대체기법은 각각의 두 성능 매트릭스에 대해서 골고루 우수한 성능을 보였다.

• Proceedings of the IEEK Conference
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• 2000.11c
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• pp.51-54
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• 2000

Due to the emerging of high-speed network, lots of interests of access to remote data have increased. Those interests motivate using of Cooperative Caching that uses remote cache like local cache by sharing other clients' cache. The conventional algorithm like GMS(Global Memory Service) has some disadvantages that occurred bottleneck and decreasing performance because of exchanges of many messages to server or manager. On the other hand, Hint-based algorithm resolves a GMS's server bottleneck as each client has hint information of all blocks. But Hint-based algorithm also causes some problems such as inaccurate information in it, if it has too old hint information. In this paper, we offer the policy that supplement bottleneck and inaccuracy； by using file identifier that can search for the lookup table and by exchanging oldest block information between each client periodically.