Presentation an approach for useful rate based on changing many tasks of workflow in distributed systems

Cloud computing refers to a network that distributes processing power, applications, and large systems among many computers With the significant advances in Information and Communications Technology (ICT) over the last half century, there is an increasingly perceived vision that computing will one day be the 5th utility (after water, electricity, gas, and telephony). This computing utility, like all other four existing utilities, will provide the basic level of computing service that is considered essential to meet the everyday needs of the general community. To deliver this vision, a number of computing paradigms have been proposed, of which the latest one is known as Cloud computing. The distributed system consists of a number of data centers that presents different services through internet. In a distributed system Timing and mapping the priority of tasks among processors is one of the issues attracted most of attention to itself. This issue consists of mapping a Direct Acyclic Graph with a set of tasks on a number of parallel processors and its purpose is allocating tasks to the available processors in order to satisfy the needs of priority and decency of tasks, and also to minimize the duration time of execution in total graph. In this article, well represent an algorithm that useful rate based on changing many tasks of workflow. Simulation is showed that the way for me is better about the list schedule algorithm.