An adaptive scheduler for distributed real-time database systems

  • Authors:

  • Hong-Ren Chen;Y. H. Chin

  • Affiliations:

  • Department of Information Management, Overseas Chinese Institute of Technology, Taichung 40721, Taiwan, ROC;Department of Computer Science, National Tsing Hua University, Hsinchu 30013, Taiwan, ROC

  • Venue:
  • Information Sciences: an International Journal
  • Year:
  • 2003

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Abstract

In a distributed real-time database system, a remote transaction usually accesses some data located at remote sites. However, traditional real-time schedulers do not consider the impact of communication delay in transferring remote data, resulting in a high MissRatio for remote transactions. This study proposes a new real-time scheduler called flexible high reward (FHR) to reduce the MissRatio and lessen the unnecessary waiting time due to communication delay for a remote transaction. This scheduler gives a remote transaction a slightly higher priority and adjusts a remote transaction's waiting status such that the resources held by a waiting remote transaction can be released as soon as possible. Through the underlying operating system, local transactions can also be executed while a remote transaction is waiting for remote data. Simulation results demonstrate that the FHR outperforms current real-time schedulers such as earliest deadline, highest value, and highest reward and urgency.