Towards fine-grained DVFS in embedded multi-core CPUs

Dynamic Voltage and Frequency Scaling (DVFS) is the preferred actuator for power-performance policies, and its use is growing also for thermal management. DVFS implementations, especially for embedded platforms, have historically provided only few possible operating points, despite this may impair the optimality of the frequency selection for a given application. Moreover, with multiple policies making use of it, the rate at which frequency and voltage changes will occur in a given system is expected to increase. The work presented in this paper has a two-fold objective: first, to present a methodology to extend a DVFS driver with additional operating points and second, to measure the impact of DVFS transitions from the performance and energy consumption perspective. This contribution can thus help both operating system and run-time manager designers to implement more efficient policies, as well as device driver programmers and hardware designers to optimize the DVFS infrastructure. The proposed approach has been tested on a quad-core ARM Cortex-A9 CPU based development board.