Recently, cloud computing is growing fast and helps to realise other high technologies.
In this paper, we propose a hieratical architecture to satisfy both providers’ and
consumers’ requirements in these technologies. We design a new service in the PaaS
layer for scheduling consumer tasks. In the providers’ perspective, incompatibility
between specification of physical machine and user requests in cloud leads to problems
such as energy-performance trade-off and large power consumption so that profits are
decreased. To guarantee Quality of service of users’ tasks, and reduce energy efficiency,
we proposed to modify Particle Swarm Optimisation to reallocate migrated virtual
machines in the overloaded host.Wealso dynamically consolidate the under-loaded host
which provides power saving. Simulation results in CloudSim demonstrated that
whatever simulation condition is near to the real environment, our method is able to save
as much as 14% more energy and the number of migrations and simulation time
(2015)significantly reduces compared with the previous works.