• Title/Summary/Keyword: 버퍼 캐시 관리

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IT-based Technology An Efficient Global Buffer Management ,algorithm for SAN Environments (SAN 환경을 위한 효율적인 전역버퍼 관리 알고리즘)

  • 이석재;박새미;송석일;유재수;이장선
    • The Journal of the Korea Contents Association
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    • v.4 no.3
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    • pp.71-80
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    • 2004
  • In distributed file-systems, cooperative caching algorithm which owns the data cached at each node jointly is used to reduce an expense of disk access. Cooperative caching algorithm is the method that increases a cache hit-ratio and decrease a disk access as it holds the cache information of distributed systems in common and makes cache larger virtually. Recently, several cooperative caching algorithms decrease the message costs by using approximate information of the cache and increase the cache hit-ratio by using local and global cache fields dynamically. And they have an advantage that increases the whole field hit-ratio by sending a replaced buffer to the idle node on buffers replacement in order to maintain the replaced cache in the cache field. However the wrong approximate information deteriorates the performance, the consistency maintenance goes to great expense to exchange messages and the cost that manages Age-information of each node to choose the idle node increases. In this thesis, we propose a cooperative cache algorithm that maintains correct cache information, minimizes the maintenance cost for consistency and the management cost for buffer Age-information. Also, we show the superiority of our algorithm through the performance evaluation.

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An Efficient Algorithm for Restriction on Duplication Caching between Buffer and Disk Caches (버퍼와 디스크 캐시 사이의 중복 캐싱을 제한하는 효율적인 알고리즘)

  • Jung, Soo-Mok
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.10 no.1
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    • pp.95-105
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    • 2006
  • The speed of hard disk which is based on mechanical operation is more slow than processor. The growth of processor speed is rapid by semiconductor technology, but the growth of disk speed which is based on mechanical operation is not enough. Buffer cache in main memory and disk cache in disk controller have been used in computer system to solve the speed gap between processor and I/O subsystem. In this paper, an efficient buffer cache and disk cache management scheme was proposed to restrict duplicated disk block between buffer cache and disk cache. The performance of the proposed algorithm was evaluated by simulation.

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MLC-LFU : The Multi-Level Buffer Cache Management Policy for Flash Memory (MLC-LFU : 플래시 메모리를 위한 멀티레벨 버퍼 캐시 관리 정책)

  • Ok, Dong-Seok;Lee, Tae-Hoon;Chung, Ki-Dong
    • Journal of KIISE:Computing Practices and Letters
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    • v.15 no.1
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    • pp.14-20
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    • 2009
  • Recently, NAND flash memory is used not only for portable devices, but also for personal computers and server computers. Buffer cache replacement policies for the hard disks such as LRU and LFU are not good for NAND flash memories because they do not consider about the characteristics of NAND flash memory. CFLRU and its variants, CFLRU/C, CFLRU/E and DL-CFLRU/E(CFLRUs) are the buffer cache replacement policies considered about the characteristics of NAND flash memories, but their performances are not better than those of LRD. In this paper, we propose a new buffer cache replacement policy for NAND flash memory. Which is based on LFU and is taking into account the characteristics of NAND flash memory. And we estimate the performance of hit ratio and flush operation numbers. The proposed policy shows better hit ratio and the number of flush operation than any other policies.

An Efficient Buffer Cache Management Scheme for Heterogeneous Storage Environments (이기종 저장 장치 환경을 위한 버퍼 캐시 관리 기법)

  • Lee, Se-Hwan;Koh, Kern;Bahn, Hyo-Kyung
    • Journal of KIISE:Computer Systems and Theory
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    • v.37 no.5
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    • pp.285-291
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    • 2010
  • Flash memory has many good features such as small size, shock-resistance, and low power consumption, but the cost of flash memory is still high to substitute for hard disk entirely. Recently, some mobile devices, such as laptops, attempt to use both flash memory and hard disk together for taking advantages of merits of them. However, existing OSs (Operating Systems) are not optimized to use the heterogeneous storage media. This paper presents a new buffer cache management scheme. First, we allocate buffer cache space according to access patterns of block references and the characteristics of storage media. Second, we prefetch data blocks selectively according to the location of them and access patterns of them. Third, we moves destaged data from buffer cache to hard disk or flash memory considering the access patterns of block references. Trace-driven simulation shows that the proposed schemes enhance the buffer cache hit ratio by up to 29.9% and reduce the total I/O elapsed time by up to 49.5%.

Design of Low-Power Object-based Mobile Storage System by WLAN Power Control (WLAN 전력제어를 통한 저전력 객체기반 모바일 스토리지 시스템의 설계)

  • Jeon, Young-Joon;Choi, Min-Seok;Nam, Young-Jin
    • Proceedings of the Korean Information Science Society Conference
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    • 2007.06b
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    • pp.441-444
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    • 2007
  • 본 논문에서는 객체기반 IP 스토리지를 이용하여 모바일 기기에서 멀티미디어 콘텐츠 재생에 적합한 저전력 객체기반 모바일 스토리지 시스템 구조를 제안한다. 멀티미디어 콘텐츠의 재생 성능을 높이기 위해 모바일 단말 측 OSD 계층에 버퍼 캐시(buffer cache)와 선반입(prefetch) 기능을 추가한다. 그리고 모바일 단말의 WLAN 전력제어를 통하여 WLAN이 가능한 한 오랜 시간 동안 Sleep 상태 또는 Power Off 상태에 있을 수 있도록 하여 전력의 소비를 줄인다. 본 연구에서는 캐시 및 선반입 기능을 위해 버퍼 캐시관리자(buffer cache manager)와 선반입 관리자(prefetch manager)를 설계하였고, WLAN 전력관리 기능을 위해 WLAN 관리자(WLAN manager)를 설계하였다.

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A Local Buffer Allocation Scheme for Multimedia Data on Linux (리눅스 상에서 멀티미디어 데이타를 고려한 지역 버퍼 할당 기법)

  • 신동재;박성용;양지훈
    • Journal of KIISE:Computing Practices and Letters
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    • v.9 no.4
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    • pp.410-419
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    • 2003
  • The buffer cache of general operating systems such as Linux manages file data by using global block replacement policy and read ahead. As a result, multimedia data with a low locality of reference and various consumption rate have low cache hit ratio and consume additional buffers because of read ahead. In this paper we have designed and implemented a new buffer allocation algorithm for multimedia data on Linux. Our approach keeps one read-ahead cache per every opened multimedia file and dynamically changes the read-ahead group size based on the buffer consumption rate of the file. This distributes resources fairly and optimizes the buffer consumption. This paper compares the system performance with that of Linux 2.4.17 in terms of buffer consumption and buffer hit ratio.

Buffer Cache Management for Low Power Consumption (저전력을 위한 버퍼 캐쉬 관리 기법)

  • Lee, Min;Seo, Eui-Seong;Lee, Joon-Won
    • Journal of KIISE:Computer Systems and Theory
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    • v.35 no.6
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    • pp.293-303
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    • 2008
  • As the computing environment moves to the wireless and handheld system, the power efficiency is getting more important. That is the case especially in the embedded hand-held system and the power consumed by the memory system takes the second largest portion in overall. To save energy consumed in the memory system we can utilize low power mode of SDRAM. In the case of RDRAM, nap mode consumes less than 5% of the power consumed in active or standby mode. However hardware controller itself can't use this facility efficiently unless the operating system cooperates. In this paper we focus on how to minimize the number of active units of SDRAM. The operating system allocates its physical pages so that only a few units of SDRAM need to be activated and the unnecessary SDRAM can be put into nap mode. This work can be considered as a generalized and system-wide version of PAVM(Power-Aware Virtual Memory) research. We take all the physical memory into account, especially buffer cache, which takes an half of total memory usage on average. Because of the portion of buffer cache and its importance, PAVM approach cannot be robust without taking the buffer cache into account. In this paper, we analyze the RAM usage and propose power-aware page allocation policy. Especially the pages mapped into the process' address space and the buffer cache pages are considered. The relationship and interactions of these two kinds of pages are analyzed and exploited for energy saving.

Performance Evaluation of Catalog Management Schemes for Distributed Main Memory Database : Compilation Cases (분산 주기억장치 데이타베이스에서 컴파일 시 카탈로그 관리 기법의 성능평가)

  • 정한라;홍의경
    • Proceedings of the Korean Information Science Society Conference
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    • 2001.10a
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    • pp.118-120
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    • 2001
  • 분산 DBMS에 대한 연추는 디스크에 데이타가 저장되어 있는 환경을 가정한 관계 DBMS에서 주로 진행되어 왔다. 디스크에 데이타가 저장되어 있다고 가정하는 시스템은 질의 최적화, 버퍼 관리기, 인덱스관리 기법 등 여러 가지 측면에서 주기억 장치 DBMS와 크게 다르기 때문에 이런 분산 DBMS에서 연구된 결과들을 그대로 주기억장치 상주 DBMS의 분산 시스템에 적용하기에는 어려움이 있다. 본 논문에서는 이러한 주기억장치 상주 중앙 집중형 DBMS를 분산 시스템으로 확장할 때 고려해야 한 여러 문제 중 캐시의 유무에 따른 카탈로그의 구조에 대해 살펴보고 시뮬레이션을 통해 카탈로그 관리기법에 대한 성능을 평가한다. 카탈로그 관리 기법의 성능평가 대상으로는 사이트의 자치성을 고려하여 분할된 카탈로그 방식을 택하였다. 실험의 결과는 캐시를 이용하는 카탈로그가 캐시를 사용하지 않는 카탈로그보다 좋은 성능을 나타냈다.

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Design of Global Buffer Manager in SAN-based Cluster File Systems (SAN 환경의 대용량 클러스터 파일 시스템을 위한 광역 버퍼 관리기의 설계)

  • Lee, Kyu-Woong
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.15 no.11
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    • pp.2404-2410
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    • 2011
  • This paper describes the design overview of cluster file system $SANique^{TM}$ based on SAN(Storage Area Network) environment. The design issues and problems of the conventional global buffer manager are also illustrated under a large set of clustered computing hosts. We propose the efficient global buffer management method that provides the more scalability and availability. In our proposed global buffer management method, we reuse the maintained list of lock information from our cluster lock manager. The global buffer manger can easily find and determine the location of requested data block cache based on that lock information. We present the pseudo code of the global buffer manager and illustration of global cache operation in cluster environment.

A Buffer Replacement Policy using Hot Page Management Scheme for Improving Performance of Flash Memory (플래시 메모리 성능향상을 위한 핫 페이지 관리 기법을 이용한 버퍼교체 정책)

  • Daeyoung Kim;Junghan Kim;Hyun-jin Cho;Young Ik Eom
    • Proceedings of the Korea Information Processing Society Conference
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    • 2008.11a
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    • pp.860-863
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    • 2008
  • 플래시 메모리는 우리 생활에 널리 사용되고 있는 휴대용 저장장치 중의 하나이다. 빠른 입출력 속도와 저전력, 무소음, 작은 크기 등의 장점을 가지나 덮어쓰기가 불가능하고 읽기/쓰기의 속도에 비해 소거 연산의 속도가 매우 느리다는 단점이 있다. 이를 보완하기 위해, 호스트와 플래시 메모리 사이에 버퍼 캐시를 두어 사용하고 있으며, 버퍼 캐시에 사용되는 교체 정책에 따라 플래시 메모리 장치의 성능이 크게 영향을 받는다. 본 논문에서는 블록 단위의 LRU 기법의 단점을 개선한 HPLRU 기법을 제안한다. HPLRU 기법은 최근에 자주 참조되었던 페이지인 핫 페이지 들을 모아 리스트를 만들어 관리하고, 이를 통해 페이지 적중률을 향상시키고 다른 페이지들로 인해 핫 페이지들이 소거되는 현상을 개선하였다. 이 알고리즘은 임의 데이터 패턴에 좋은 성능을 보이며 쓰기 발생 횟수를 많이 감소시키는 결과를 보였다.