• Title/Summary/Keyword: disk scheduling

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High Speed I/O Processing for Shared Memory Multiprocessor Systems (공유 메모리 다중 프로세서 시스템에서 고속 입출력 처리 기법)

  • 윤용호;임인칠
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.30B no.2
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    • pp.19-32
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    • 1993
  • This paper suggests the new high-speed input/output techniques in a shared memory multiprocessor system. The high-speed I/O processor which can connect the different kinds of large sized I/O periperal devices, the communication protocol to the main processing units for I/O operations, and the job scheduling scheme are addressed. This paper also introduces the disk cache technique which supports the slow I/O devices comparing with the main processing units. These techniques were implemented in the TICOM system. The performance evaluation statistics were collected and analyzed for the suggested high-speed I/O processing techniques. These statistics show the superiority of the suggested techniques.

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I/O Scheduling of Multiple Disk Arrays for Reducing Deadline Miss Rate on VOD Servers (VOD 서버에서 마감시간 초과율 감소를 위한 다중 디스크배열 I/O 스케줄링)

  • Jeong, Gyeong-Jin;Kim, Seong-Jo
    • Journal of KIISE:Computer Systems and Theory
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    • v.28 no.5
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    • pp.236-244
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    • 2001
  • 디스크배열 또는 RAID 시스템은 저렴한 비용으로 대용량 저장공간을 제공할 수 있으나, VOD 서비스와 같은 대규모 멀티미디어 서비스에 대해서는 아직 충분한 입출력 속도를 지원하지 못하고 있다. 보다 높은 대역폭을 지원하기 위해 다수의 디스크 컨트롤러를 채용한 다중 디스크배열에서 스트라이프를 전체 디스크에 효과적으로 분산시키기 위한 수직 스트라이핑 모델이 이용되고 있다. VOD 서비스 이용자가 고품질의 동영상을 감상하기 위해서는, 응용프로그램이 요청한 마감시간까지 저장장치에 기록되어 있는 데이터를 읽어와야 한다. 본 논문에서는 효과적이 VOD 서비스 지원을 위해, 다중 디스크배열에서 각 디스크 컨트롤러의 지역 요청큐로 분산된 입출력 요청들을 스케쥴링하여 마감시간 초과율(deadline miss rate)을 줄이기 위한 알고리즘을 제안한다. 이 알고리즘은 VOD 서버와 같이 데이터 읽기 작업이 많은 멀티미디어 서비스에 적합하도록 설계되었다. 시뮬레이션 결과, 제안된 알고리즘이 마감시간 초과율을 평균 41.5% 감소시킴을 알 수 있었다.

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Disk Scheduling with Dynamic Weight Control in Multimedia Storage Servers (멀티미디어 저장 서버에서의 동적 가중 제어를 이용한 디스크 스케줄링)

  • 박은정;박상수;이수형;장래혁;신현식
    • Proceedings of the Korean Information Science Society Conference
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    • 2000.04a
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    • pp.154-156
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    • 2000
  • 멀티미디어 저장 서버에서는 실시간 클래스와 비실시간 클래스의 두가지 상이한 종류의 요청이 존재한다. 비디오 오디오 등의 실시간 클래스는 정해진 시간 안에 추출되어야 하며 종료시한에 대한 만족이 보장되어야 한다. 반면 텍스트 데이터 등의 비실시간 클래스는 공정한 서비스와 빠른 응답 시간을 요구한다. 본 논문에서는 두 클래스의 요구사항을 동시에 만족시키기 위하여 각 클래스에 할당된 가중을 동적으로 제어하는 디스크 스케줄링을 제안하였다. 클래스 가중은 각 클래스의 가중은 각 클래스에 할당된 디스크 대역폭의 비율을 말한다. 또한 수용제어 알고리즘의 결과를 이용하여 각 클래스의 가중을 동적으로 변화시켜 유혹 대역폭이 효율적으로 이용되도록 하였다. 성능 측정 결과 동적 가중을 이용한 디스크 스케줄링은 비실시간 요청의 평균 응답시간 면에서 정적 가중을 이용한 디스크 스케줄링보다 좋은 성능을 나타낸다.

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Two queue disk scheduling for Integrated service (통합 서비스 제공을 위한 이중 큐 디스크 스케줄링)

  • Hyun, Eun-Sil;Rhee, Yoon-Jung;Kim, Tai-Yun
    • Proceedings of the Korea Information Processing Society Conference
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    • 2000.10b
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    • pp.1243-1246
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    • 2000
  • 응용프로그램을 실행시키는 것은 많은 디스크 대역폭을 필요로 하고 있다. 데이터를 조회하는데 걸리는 시간을 최소로 하는 것이 성능을 향상시키는 가장 큰 문제이다. 디스크 기술은 속도와 용량면에서 많은 발전이 있었음에도 불구하고, 프로그램에서 요구하는 요구사항이 증가함하고 있다. 멀티미디어 서버는 여러 종류의 텍스트나 이미지, 비디오 등의 다양한 데이터 타입을 지원한다. 따라서 다른 데이터 타입들은 다른 마감시간의 요구와 우선 순위를 가지고 있다. 연속적인 오디오나 비디오 같은 것들 은 마감시간 제약을 가지고 있다. 이 논문에서 제한한 알고리즘은 모든 요청들을 두 개의 큐로 유지하고 탐색 시간을 최소화함으로써 디스크 대역폭의 처리율을 극대화시킨다. 즉 다양한 우선 순위의 요청들을 해당 클래스로 나누고 주기적인 요청을 위한 큐와 비 주기적인 요청이나 대화형 요청들을 위한 또 하나의 큐로 나누고 요청의 마감시간과 디스크 헤드의 움직임을 고려하여 스케줄링한다.

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A Cache buffer and Read Request-aware Request Scheduling Method for NAND flash-based Solid-state Disks (캐시 버퍼와 읽기 요청을 고려한 낸드 플래시 기반 솔리드 스테이트 디스크의 요청 스케줄링 기법)

  • Bang, Kwanhu;Park, Sang-Hoon;Lee, Hyuk-Jun;Chung, Eui-Young
    • Journal of the Institute of Electronics and Information Engineers
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    • v.50 no.8
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    • pp.143-150
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    • 2013
  • Solid-state disks (SSDs) have been widely used by high-performance personal computers or servers due to its good characteristics and performance. The NAND flash-based SSDs, which take large portion of the whole NAND flash market, are the major type of SSDs. They usually integrate a cache buffer which is built from DRAM and uses the write-back policy for better performance. Unfortunately, the policy makes existing scheduling methods less effective at the I/F level of SSDs Therefore, in this paper, we propose a scheduling method for the I/F with consideration of the cache buffer. The proposed method considers the hit/miss status of cache buffer and gives higher priority to the read requests. As a result, the requests whose data is hit on the cache buffer can be handled in advance and the read requests which have larger effects on the whole system performance than write requests experience shorter latency. The experimental results show that the proposed scheduling method improves read latency by 26%.

An Efficient Range Query Processing of Distributed Moving Object (분산 이동 객체 데이터베이스의 효율적인 범위 질의 처리)

  • Jeon, Se-Gil;Woo, Chan-Il
    • Journal of the Institute of Electronics Engineers of Korea TE
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    • v.42 no.1
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    • pp.35-40
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    • 2005
  • Recently, the location based service for moving customers is becoming one of the most important service in mobile communication area and for moving object applications, there are lots of update operations and such update loads are concentrated on some particular area unevenly. The primary processing of LBS application is spatio-temporal range queries and to improve the throughput of spatio-temporal range queries, the time of disk I/O in query processing should be reduced. In this paper, we adopt non-uniform two-level grid index structure, which are designed to minimize update operations. We propose query scheduling technique using spatial relationship and time relationship and a combined spatio-temporal query processing method using time zone concepts to improve the throughput of query processing. Some experimental results are shown for range queries with different query range to show the performance tradeoffs of the proposed methods.

A Patching-Based VOD System supporting VCR Operations (VCR 동작을 지원하는 패칭 기반의 주문형 비디오 시스템)

  • 조창식;마평수;이기호;강지훈
    • Journal of KIISE:Information Networking
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    • v.30 no.1
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    • pp.9-16
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    • 2003
  • In this paper, we propose a method for supporting VCR operations in a patching based multicast VOD system. Random access, pause and resume operations are supported in our system, and the channel and session scheduling algorithms for the VCR operations are proposed. When it is necessary to join a sharable multicast channel in the admission control for the VCR operations, the patching technique, which shares an on-going regular channel and allocates a new patching channel for the missing data, is used. Therefore, unlike the previous approach that allocates an excessive number of I-channels, service latency is minimized and channel usage is optimized in our system. Moreover buffered data. which is saved in disk during patching, is reused to prevent unnecessary patching channel allocation. For this. the patching management information is extended and a buffed data management scheme is proposed. In our system, the First-Come-First-Served scheduling is used to inform clients the service latency for the VCR operations immediately.

Video Server with Optical Mass Storage (광주크박스 저장장치에 기반한 비디오 서버)

  • Lee, Jong-Min;Cha, Ho-Jung;Oh, Jae-Hak;Park, Byung-Joon
    • Journal of KIISE:Computer Systems and Theory
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    • v.29 no.6
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    • pp.318-330
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    • 2002
  • This paper discusses the design and implementation of a video server which uses tertiary device, such as magneto-optical jukebox or tape library, as a source of media archiving. In order to handle the tertiary device in the framework of disk-based stream service model, a sophisticated streaming model is required for server and it should consider the device-specific performance characteristics of tertiary storage. We have carefully designed the streaming mechanism for server whose key functionalities include stream scheduling, disk caching and admission control. The proposed system has been implemented on Windows 2000 platform which is equipped with a magneto-optical jukebox. The design principles of the server are validated with the experiments and the performance characteristics is analyzed.

Design and Implementation of a Main-memory Storage System for Real-time Retrievals (실시간 검색을 위한 다중 사용자용 주기억장치 자료저장 시스템 개발)

  • Kwon, Oh-Su;Hong, Dong-Kweon
    • The KIPS Transactions:PartD
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    • v.10D no.2
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    • pp.187-194
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    • 2003
  • Main Memory storage system can increase the performance of the system by assigning enough slack time to real-time transactions. Due to its high response time of main memory devices, main memory resident data management systems have been used for location management of personal mobile clients to cope with urgent location related operations. In this paper we have developed a multi-threaded main memory storage system as a core component of real-time retrieval system to handle a huge amount of readers and writers of main memory resident data. The storage system is implemented as an embedded component which is working with the help of a disk resident database system. It uses multi-threaded executions and utilizes latches for its concurrency control rather than complex locking method. It only saves most recent data on main memory and data synchronization is done only when disk resident database asks for update transactions. The system controls the number of read threads and update threads to guarantee the minimum requirements of real-time retrievals.

Efficient Incorporation of Tertiary Storage in a Multimedia DBMS (멀티미디어 DBMS에서 3차 저장장치의 효율적 활용 기법)

  • Mun, Chan-Ho;Gang, Hyeon-Cheol
    • The Transactions of the Korea Information Processing Society
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    • v.6 no.7
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    • pp.1724-1737
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    • 1999
  • Multimedia data service applications have to store and manipulate LOBs(unstructured large objects) composing multimedia data. As such, the tertiary storage devices such as an optical disk jukebox and a tape library that consist of a number of platters (the disks in case of an optical disk jukebox and the cartridge tapes in case of a tape library) have been considered essential for the storage system of a DBMS in order to efficiently support storage and management of vary large volume of data. Since the latency with tertiary storage is too long, the schemes for efficient retrieval of LOBs out of tertiary storage need to be investigated. In this paper, we investigated the tertiary I/O Considering the performance characteristics of the LOBs, we proposed various I/O scheduling heuristic algorithms that reduce latency in query processing with LOB retrieval from tertiary storage, and evaluated their performance through a detailed simulation.

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