CasCon: Cascaded Thermal and Electrical Current Throttling for Mobile Devices

As technology scales down, power density considerably increases, raising critical power and thermal challenges. This is even more challenging for mobile devices due to their form factor and the multiple sources of thermal emergencies, as well as the limited electric current delivery, arising from battery specifications. In this letter, we propose a cascaded thermal and electrical current throttling controller inspired from the physical relations that exist among the different current and thermal measures. The proposed controller achieves better results by coordinating between the different sources of current and thermal emergencies, and dynamically adjusting their caps. Testing on a state-of-the-art smartphone, the proposed technique achieves 6.5% better performance and 18% power savings as compared to the existing techniques, while avoiding current and thermal violations using
$40\times $
less DVFS transitions.