Research On List And Time Cost Constrained Workflow Scheduling Algorithm In Cloud Environment

In recent years,cloud computing technology has made great contributions to the development of global informatization and has been integrated into various fields.Many domestic and foreign enterprises have also begun to develop their cloud services.The large amount of computing resources deployed by the cloud computing center provides convenience for the execution of workflow applications.How to effectively implement workflow scheduling is very important to improve the performance of cloud computing and achieve efficient computing,and it is also a hot research topic in recent years.This thesis takes workflow scheduling in cloud environment as the research object,shortens the length of workflow scheduling and improves service quality as the main research goals,and proposes corresponding scheduling strategies.The main research work of this thesis is as follows:To the problem of minimizing the length of workflow scheduling,this thesis proposes a new table scheduling algorithm based on a virtual scheduling length table,which is called BVSL.The algorithm first constructs the predicted remaining length table based on the prescheduling results,and then constructs a virtual scheduling length table based on the predicted remaining length table,the current task execution cost,and the actual start time of the task,and calculates the task priority based on the virtual scheduling length table to make the overall path the longest task is scheduled first,thus effectively shorten the scheduling length.Finally,the processor is selected for the task based on the predicted remaining length table.The selected processor may not be the processor with the earliest completion time of the current task,but it can make the completion time of subsequent tasks shorter,and achieve the purpose of reducing the scheduling length.To verify the effectiveness of the scheduling method,experiments were carried out from two aspects: randomly generated graphs and real-world application graphs.Experimental results show that the algorithm proposed in this thesis can achieve good results in makespan,scheduling length ratio,speedup,and the number of occurrences of a better quality of schedules.To the Workflow scheduling optimization problem for deadline and budget constraints,this thesis proposes a new scheduling algorithm based on sub-deadline and segment-budget,called BSDSB.The algorithm allocates deadlines and budgets to each task through the proposed deadline allocation strategy and budget allocation strategy,and filters processors according to the current task deadline and budget to control the selection range of processors,thereby effectively controlling the execution time and budget of tasks.At the same time,different selection strategies are provided for the current task according to the filtered processor range,in order to achieve a better balance between time and cost.This thesis verifies the performance of the scheduling algorithm from the randomly generated graph and the real application graph,respectively.The experimental results show that the algorithm in this thesis has a better effect on the success rate.