Multi‐level simultaneous multithreading scheduling to reduce the temperature of register files

Abstract

SUMMARYSimultaneous multithreading (SMT) processors can exploit thread‐level parallelism and at the same time exploit instruction‐level parallelism for multiple‐issue, dynamically scheduled processors. As they have been widely used in embedded systems, reducing their highest temperature has become very important. According to our observation, the register file is always one of the hottest parts of an embedded system. Thus, we present a smart scheduling that can cool an SMT processor effectively by controlling the temperatures of its register files without causing significant performance loss. The proposed approach is fourfold, thus allowing an operating system to dynamically adjust the running workloads based on the temperature threshold and the real‐time constraint. Our experiment was performed on the M‐Sim and HotSpot simulators to evaluate the power of functional units and the temperature impact for SMT processors. In contrast with the round‐robin scheduling, the proposed approach can reduce thermal emergency time by 16.1 and 9.38% of the integer register file and the floating point register file, respectively. Moreover, the proposed approach only degrades performance by 8.8%, which is better than the 22.1% of the throttling approach. Copyright © 2011 John Wiley & Sons, Ltd.