Workflow scheduling algorithm based on control structure reduction in cloud environment

Recently, cloud computing has emerged as a new model of service provisioning, in this model, one of the most challenging problems is workflow scheduling, i.e., the problem of satisfying users´ QoS while minimizing the execution cost of cloud workflow. This paper propose a workflow scheduling algorithm called Control Structure Reduction algorithm(CSR). In CSR, the workflows represented by DAG (Directed Acyclic Graph) can be converted into an equivalent sequence control structure by such means as mergers and reduction. Then we can easily identify the critical path of the workflow process. By using Time Float Distribution Algorithm, the total time float is allocated to each task based on critical tasks in critical path, eventually to enlarge the cost optimization intervals of all tasks. The simulation results show that CSR has a promising performance in decreasing the execution cost for large workflows.