Dynamic Thermal Management Under Soft Thermal Constraints

In this paper, we investigate dynamic thermal management (DTM) policies under soft thermal constraint that allow the thermal constraint to be violated occasionally for boosting system performance. First, we investigate soft-constraint DTM using lumped radio control (RC) thermal models. We develop analytical expressions for the optimal core frequency policies that maximize overall performance under soft thermal constraint for both single-core and homogeneous multicore processors. We then generalize the problem to heterogeneous multicore processor and use a more accurate distributed RC thermal model to account for the spatial thermal variation. The generalized problem also takes into account the impact of increased temperature on transistor delay and leakage power. The problem is solved by convex optimization. Experimental results indicate that for a two-core processor, a mere 10 °C increase in the core temperature for 100 s results in about 30% performance gain.