A Closed-Loop Controller to Ensure Performance and Temperature Constraints for Dynamic Applications

To secure correct system operation, a plethora of Reliability, Availability and Serviceability (RAS) techniques have been deployed by circuit designers. RAS mechanisms however, come with the cost of extra clock cycles. In addition, a wide variety of dynamic workloads and different input conditions often constitute preemptive dependability techniques hard to implement. To this end, we focus on a realistic case study of a closed-loop controller that mitigates performance variation with a reactive response. This concept has been discussed but was only illustrated on small benchmarks. In particular, the extension of the approach to manage performance of dynamic workloads on a target platform has not been shown earlier. We compare our scheme against the version of a Linux CPU frequency governor in terms of timing response and energy consumption. Finally, we move forward and suggest a new flavor of our controller to efficiently manage processor temperature. Again, the concept is illustrated with a realistic case study and compared to a modern temperature manager.