面向可靠性一费用优化的网格任务调度模型及算法研究

网格资源的异构性、动态性等特征使得网格任务调度仍面临着诸多问题。针对传统可靠性评佑模型仅考虑 资源失效的问题，在考虑本地任务会抢占网格任务执行资源的情况下，引入任务执行延期失效，从而建立了一种新的 网格资源可靠性评估模型。该模型使用随机服务系统理论建模网格资源的动态负载压力，给出了任务在资源上的执 行可靠性的计算方法及证明。基于建立的网格资源可靠性模型，建立了面向可靠性和费用的多目标任务优化调度模 型，以获得最大化任务执行可靠性、最小化任务执行费用的任务调度策略。针对该NP问题，采用化学反应优化算法 对该优化问题进行求解，并给出了算法4种操作的具体实施方法。仿真实验表明，所提出的可靠性评估模型更符合真 实的网格系统，与遗传算法、粒子群算法相比，化学反应优化算法能更好地解决可靠性一费用双目标优化的网格任务调 度问题。

Reliability-Cost Optimization Scheduling Model

Due to the heterogeneity and dynamicity of grid resources,therc arc a lot of problems unsolved in grid task scheduling. To cope with the shortcoming of traditional reliability evaluation model, a new type of failure named dead- line-missing-failure was introduced to support reliability evaluation for tasks with deadline constraint. Considering the impact of local tasks, we used a stochastic service model to describe dynamic workloads of Grid resources. A corre- sponding calculation method and proof for resource reliability were proposed. Based on the proposed grid resource relia- bility evaluation modcl,a mufti objective grid task scheduling model was presented. hhe task scheduling was formulated as an optimization problem to maximize the reliability and minimize the cost. Fer the issue, a chemical reaction optimiza- tion algorithm, called CRO, was developed to solve the NP problem. Experimental results verify the performance of pro- posed reliability model and CRO algorithm is superior to GA and PSO for Grid reliability-cost optimization problem in quality and cffcicncy.