Dynamic thermal management for single and multicore processors under soft thermal constraints

In this paper, we investigate Dynamic Thermal Management (DTM) policies under soft thermal constraint that allows the thermal constraint to be violated for a user specified period. For single core processor, we develop analytical expression for the optimal frequency policy under the soft constraint such that maximal performance can be extracted. We extend this problem to multi-core processor and provide optimal frequency policy when all cores run at same frequency. We also present LP based approximated formulation that generates frequency policies where each core has separate frequency control and considers leakage power. We use frequency legalization to approximate the frequency into discrete values. Experimental results indicate that 10°C increase in core temperature for 100sec results in 13% performance gain for single core processor, and 30% performance gain for two-core processor. Without Tmax constraint, the performance improves almost 100% for two-core processor.