志愿计算系统时延分析  

Delay Analysis of Volunteer Computing Systems

作　　者：张健[1] 李东[1] 叶通[1] 

机构地区：[1]上海交通大学区域光纤通信网与新型光通信系统国家重点实验室,上海200240

出　　处：《电讯技术》2017年第12期1356-1362,共7页Telecommunication Engineering

摘　　要：志愿计算(Volunteer Computing)系统是一种分布式计算系统,它利用全球空闲计算资源实现海量科学计算。随着志愿计算的广泛应用,系统时延性能分析变得日益重要。现有文献主要通过仿真和实验观察其时延特性,并不能深入分析系统参数的影响。为此,提出了一种新的数学模型对志愿计算系统时延特性进行分析。志愿计算系统可以建模为一个变速率服务的单服务台排队系统。理论分析表明,系统的平均队长与服务速率方差之间存在单调递增的关系。因此,系统在服务速率方差趋于0和无穷大两个极端情况下的平均队长分别为系统平均队长的下界和上界,而在这两种极端情况下,可以通过对系统模型的简化求得系统的平均队长。仿真结果验证了该方法所求平均队长上下界的正确性和准确性。Volunteer computing （VC） is a distributed computing system which uses spare computing powerfrom general public to do scientific computing. With the rapid growth of volunteer computing,delay per-formance evaluation becomes more and more important. In existing literatures,delay performance of VCsystem is majorly observed by simulations and experiments,through which the influence of system parame-ters cannot be deeply analyzed. Therefore,a new model is proposed to analyze the delay performance of VCsystem. The VC system can be modeled as a single server queue with variable service rate. Analytical re-sults show that the mean queue length increases with the fluctuation of service rate. Therefore,the meanqueue length under two extreme cases,variance of service rate approaches to 0 and infinity,should be thelower bound and upper bound respectively. And the mean queue length under the two extreme cases can beobtained by the simplified system model. Simulation result validates that the two queue length bounds areboth valid and accurate.

关 键 词：志愿计算 排队网络 时延分析 服务速率方差 马尔科夫链 

分 类 号：TN919[电子电信—通信与信息系统]