Thermal influence on the energy efficiency of workload consolidation in many-core architectures

Webserver farms and datacenters currently use workload consolidation to match the dynamic workload with the available resources since switching off unused machines has been shown to save energy. The workload is placed on the active servers until the servers are saturated. The idea of workload consolidation can be brought also to chip level by the OS scheduler to pack as much workload to as few cores as possible in a many-core system. In this case all idle cores in the system are placed in a sleep state, and are woken up on-demand. Due to the relationship between static power dissipation and temperature, this paper investigates the thermal influence on the energy efficiency of chip level workload consolidation and its potential impact on the scheduling decisions. This work lay down the foundation for the development of a model for energy efficient OS scheduling for many-core processors taking into account external factors such as ambient and core level temperatures.