the School of Computing Science Beijing University of Posts and Telecommunications Beijing 100876 Chinathe School of Information Engineering Nanchang Institute of Technology Nanchang 330099 China;
the School of Computing Science Beijing University of Posts and Telecommunications Beijing 100876 Chinathe Key Laboratory of Trustworthy Distributed Computing and Service(BUPT) Ministry of Education Beijing 100876 China;
Cloud computing; idle time slot; particle swarm optimization; task scheduling sequence; workflow scheduling;