Abstract: In cloud computing, computing infrastructure is viewed as cloud, where all the individuals and business firms keep their data and access it from anywhere in the world on demand. It is the latest distributed computer paradigm after grid, utilities where everything is based on pay- per use. Workflow and task scheduling are the recent research topics in cloud. Many scheduling policies have been defined to maximise the amount of work, but however, many of them are not optimal. In this paper a meta-heuristic optimization technique, HDPSO is used to minimize the execution cost simultaneously meeting the deadline.

Keywords: Cloud Computing, HDPSO, Scheduling, Workflow.