A Scientific Workflow Trade-off Scheduling Algorithm in Cloud Environment

For optimizing scientific workflow schedulimg with budget constraint in cloud, a Budget Division Workflow Trade-off Scheduling (BDWTS) algorithm is presented. With synchronous optimization of makespan and cost meeting budget constraint as the objective, the algorithm is divided into four stages during scheduling workflow:workflow leveling, budget division, task selection and instance selection. Workflow leveling partitions the workflow tasks into different levels by the top-down method, budget division allocates the user-defined budget to each defined levels by six strategies, task selection selects the scheduled-priority task by the earliest start time principle, instance selection selects the optimal execution resource by overall considering the time factor and cost factor. It is proved that our algorithm can obtain the trade-off scheduling scheme of the execution time and execution cost under meeting budget constraint by simulation experimental results.