Variability-aware dark silicon management in on-chip many-core systems

Dark Silicon refers to the constraint that only a fraction of on-chip resources (cores) can be simultaneously powered-on (running at full performance) in order to stay within the allowable power budget and safe temperature limits, while others remain `dark'. In this paper, we demonstrate how these `dark cores' can be leveraged to improve the temperature profile at run-time, thus providing opportunities to power-on more cores at the nominal voltage than the number allowed when strictly obeying the conventional Thermal Design Power (TDP) constraint. In this paper, we propose a computationally efficient dark silicon management technique that determines the best set of cores to keep dark and the mapping of threads to cores at run-time, while also accounting for the impact of process variations. We have developed a lightweight temperature prediction mechanism that determines the impact of different candidate solutions on the chip thermal profile. Experimental evaluation of the proposed techniques on a simulated 8×8 many-core processor, and across a range of chips to account for process variations, show that the total instruction throughput is increased by 1.8× on average while keeping the temperature within the safe limits, when compared with state-of-the-art approaches.