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

Abstract

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.

Timescales: the choreography of classical and unconventional computing

“…This requires a control process overhead which is apt to diminish or cancel the efficiency gains of potentially very high processing speeds. New methods are being proposed for ultra-scaled digital microchips (Noltsis, Zambelis, Catthoor, & Soudris, 2019) to remove that overhead and make fuller use of the fast processing available at the physical level while retaining timing guarantees. The timing challenges that are connected with deeply scaled digital microchips have some surprising connections with challenges in non-digital computing.…”