Journal of KIISE:Information Networking (한국정보과학회논문지:정보통신)

Korean Institute of Information Scientists and Engineers (한국정보과학회)
권호 표지

Prefetching Mechanism using the User's File Access Pattern Profile in Mobile Computing Environment

이동 컴퓨팅 환경에서 사용자의 FAP 프로파일을 이용한 선인출 메커니즘

  • 최창호 (중앙대학교 컴퓨터공학과) ;
  • 김명일 (중앙대학교 컴퓨터공학과) ;
  • 김성조 (중앙대학교 컴퓨터공학과)
  • Published : 2000.06.30
Download PDF
⟨ Previous Next ⟩

Abstract

In the mobile computing environment, in order to make copies of important files available when being disconnected the mobile host(client) must store them in its local cache while the connection is maintained. In this paper, we propose the prefetching mechanism for the client to save files which may be accessed in the near future. Our mechanism utilizes analyzer, prefetch-list producer, and prefetch manager. The analyzer records file access patterns of the user in a FAP(File Access Patterns) profile. Using the profile, the prefetch-list producer creates the prefetch-list. The prefetch manager requests a file server to return this list. We set the parameter TRP(Threshold of Reference Probability) to ensure that only reasonably related files can be prefetched. The prefetch-list producer adds the files to a prefetch-list if their reference probability is greater than the TRP. We also use the parameter TACP(Threshold of Access Counter Probability) to reduce the hoarding size required to store a prefetch-list. Finally, we measure the metrics such as the cache hit ratio, the number of files referenced by the client after disconnection and the hoarding size. The simulation results show that the performance of our mechanism is superior to that of the LRU caching mechanism. Our results also show that prefetching with the TACP can reduce the hoard size while maintaining similar performance of prefetching without TACP.

이동 컴퓨팅 환경에서 이동 호스트(클라이언트)는 네트워크가 연결되어 있는 동안 단절에 대비하여 중요한 파일들을 자신의 로컬 캐쉬에 저장하여야 한다. 본 논문에서는 클라이언트가 네트워크 단절시 가까운 미래에 사용하게 될 파일을 캐쉬에 저장하는 선인출 메커니즘을 제안한다. 이 메커니즘은 분석기, 선인출 목록 생성기, 그리고 선인출 관리기를 활용한다. 분석기는 클라이언트의 파일 참조 기록을 FAP(File Access Pattern) 프로파일에 저장한다. 선인출 목록 생성기는 이 프로파일을 이용하여 선인출 목록을 만들며, 선인출 관리기는 이 선인출 목록을 파일 서버에게 요청한다. 본 논문은 단지 관련성이 깊은 파일들이 선인출되는 것을 보장하기 위해 TRP(Threshold of Reference Probability) 파라미터를 설정하였다. 선인출 목록 생성기는 참조 확률이 TRP 이상인 파일들을 선인출 목록에 추가한다. 또한, 본 논문은 선인출 목록을 저장하는데 필요한 적재 크기를 줄이기 위해 TACP(Threshold of Access Counter Probability) 파라미터를 사용한다. 마지막으로, 우리는 캐쉬 적중률, 단절 후 클라이언트의 참조 파일 수, 적재 크기를 측정하였다. 시뮬레이션 결과, 선인출 메커니즘의 성능이 LRU 캐슁 메커니즘 보다 우수함을 알 수 있었다. 또한, TACP를 이용한 선인출은 적재 크기를 줄일 수 있으면서도, TACP를 사용하지 않는 선인출과 바슷한 성능을 보임을 확인하였다.

Keywords

References

  1. D. Duchamp, 'Issue in Wireless Mobile Computing,' http://www.mcl.cs.columbia.edu/papers.html, April 1992
  2. George H. Forman and John Zahorjan, 'The Challenges of Mobile Computing,' IEEE Computers, 27(4), pp.38-47, April 1994 https://doi.org/10.1109/2.274999
  3. T. Imielinski and S. Viswanathan, 'Adaptive Wireless Information Systems,' In Proceedings of SIGDBS Conference, October 1994
  4. S. Acharya. 'Broadcast Disks : Data Management for Asymetric Communication Environments,' In Proceedings of ACM SIGMOD Conference, pp. 199-210, June 1995 https://doi.org/10.1145/568271.223816
  5. J. Jing, et al., 'Bit-Sequence : A New Cache Invalidation Method in Mobile Environments,' Technical Report, Purdeu University, 1994
  6. D. Barbara and T. Imielinski, 'Sleepers and Workaholics: Caching Strategies in Mobile Environments' In Proceedings of the 1994 ACM SIGMOD International Conference on Management of Data, pages 1-24, 1994 https://doi.org/10.1145/191839.191844
  7. R. Alonso, D. Barbara, and Luis L. Cova, 'Using Stashing to Increase Node Autonomy in Distributed File Systems,' In Proceedings of the Ninth IEEE Symposium on Reliability in Distributed Software and Database Systems, pp. 12-21, October 1990 https://doi.org/10.1109/RELDIS.1990.93947
  8. J. Griffioen and R. Appleton, 'Reducing File System Latency Using a Predictive Approach,' In Proceedings of the Summer USENIX Conference Proceedings, pp. 8-12, June 1994
  9. J. Griffioen and R. Appleton, 'The Design, Implementation, and Evaluation of a Predictive Caching File System,' Technical Report CS-264-96, University of Kentucky, June 1996
  10. J. J. Kistler, Disconnected Operation in a Distributed Operation in a Distributed File System, Ph.D. Dissertation, Carnegie-Mellon University, May 1993
  11. J. J. Kistler and M. Satvanarayanan. 'Disconnected Operation in the Coda File System,' ACM Transactions on Computer Systems, 10(1), pp. 3-25, February 1992 https://doi.org/10.1145/146941.146942
  12. G. H. Kuenning, 'Design of the SEER Predictive Caching System,' In Proceedings of the Workshop on Mobile Computing Systems and Applications, December 1994 https://doi.org/10.1109/MCSA.1994.512732
  13. G. H. Kuenning, Seer: Predictive File Hoarding for Disconnected Mobile Operation, Ph.D. Dissertation, UCLA, May 1997
  14. L. B. Huston and P. Honeyman, 'Disconnected Operations for AFS,' In Proceedings of the USENIX Symposium on Mobile and LocationIndependent Computing, pp. 1-10, 1993
  15. Carl D. Tait, et al., 'Intelligent File Hoarding for Mobile Computers,' In Proceedings of MobiCom'95, pp. 119-125, November 1995 https://doi.org/10.1145/215530.215564
  16. J. Griffioen, Kentucky File Traces, http://www.dcs.uky.edu/~mbfs/traces.html. 1994