Introducing Agent Evictions to Improve Application Placement in Wireless Distributed Systems

With the development of mobile code frameworks for embedded systems, an application can be structured as a set of cooperating components (agents) that are placed on the nodes of the system in a flexible way. Reducing the network traffic caused by the application components is a crucial issue for the increase in the lifetime of wireless embedded systems, since it is widely known that the communication cost plays the most significant role in the energy consumption of embedded devices. To this end, most placement algorithms place or move an agent towards the center of gravity of the communication workload. However, if the target node does not have enough capacity, the attempt is usually aborted. In this paper, we introduce eviction-enabled algorithms that allow nodes to free capacity by forcing a locally hosted agent to move to another node, even at a loss, to accept a new and potentially more beneficial agent. To the best of our knowledge, this is the first time that agents are evicted by local hosts to enable beneficial agent migrations and eventually improve the total network cost. In this paper, we provide algorithms tackling the aforementioned problem in a fully distributed manner. We also present and discuss the results of extensive simulations, showing that eviction-enabled algorithms can outperform their counterparts by up to 300%.