Control-theoretic techniques and thermal-RC modeling for accurate and localized dynamic thermal management

TLDR

Localized heating on chips creates hot spots that arise faster than chip‑wide temperature changes. The study aims to apply formal feedback control theory to adaptive dynamic thermal management in processors and to develop a lumped RC thermal model for accurate testing. The authors implement PID‑based dynamic thermal management and evaluate it using a lumped RC thermal model. The efficient RC model accurately tracks block‑level temperatures, enabling a thermal trigger threshold within 0.2 °C of peak that avoids emergencies and reduces DTM performance loss by 65 % versus fixed‑magnitude fetch toggling.

Abstract

This paper proposes the use of formal feedback control theory as a way to implement adaptive techniques in the processor architecture. Dynamic thermal management (DTM) is used as a test vehicle, and variations of a PID controller (Proportional-Integral-Differential) are developed and tested for adaptive control of fetch "toggling." To accurately test the DTM mechanism being proposed, this paper also develops a thermal model based on lumped thermal resistances and thermal capacitances. This model is computationally efficient and tracks temperature at the granularity of individual functional blocks within the processor. Because localized heating occurs much faster than chip-wide heating, some parts of the processor are more likely, to be "hot spots" than others. Experiments using Wattch and the SPEC2000 benchmarks show that the thermal trigger threshold can be set within 0.2/spl deg/ of the maximum temperature and yet never enter thermal emergency. This cuts the performance loss of DTM by 65% compared to the previously described fetch toggling technique that uses a response of fixed magnitude.