The Decision Model of Task Allocation for Constrained Stochastic Distributed Systems

• Main Authors: Wan-Ting Huang, 黃婉婷
• Other Authors: Chi-Chang Jou
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/40591639088047160000

碩士 === 淡江大學 === 資訊管理學系碩士班 === 93 === With the advantages of high speed and high reliability, distributed systems, like power control system or ATM, have already been widely applied in daily lives. In a distributed system, a software application could be called a task and software is composed of a set of cooperating modules. Each module of a task will be executed on one of the processors of the distributed system. Then the system reliability of a distributed system could be defined as the probability that the system can run an entire task successfully. In designing a distributed system, if its hardware configuration is fixed, then its system reliability will depend mainly on the software design. Task allocation is an important step in distributed software design. This thesis aims to build a decision model of task allocation that is suitable for the stochastic distributed systems. Based on the Markov model proposed by Cheung, the objective function of the model is to maximize the system reliability, which is composed of module reliability, hardware reliability of processing nodes, transition probability between modules, and module allocation strategy. The model includes constraints about storage and load limitations at each processor and constraints about bounds of system cost, and solves the task allocation problem by Constraint Programming. Finally, we apply the decision model in an extended case, and perform sensitivity analysis for module reliability and hardware reliability.