An integrated autonomous control mechanism to optimize sharing of multiple resources in Simultaneous Multi-Threading processors

Simultaneous Multi-Threading (SMT) processors allow concurrent execution of multiple independent threads with sharing of key datapath components to enhance system performance with more efficient resource utilization. However, due to the nature of SMT processing, imbalanced distribution of critical shared resources may easily clog some pipeline stages by slower threads and lead to unexpected system performance degradation. In this paper, an integrated autonomous control mechanism is proposed to optimize the use of two critical shared resources among multiple threads based on threads' temporal behaviors in real time, by taking into account resource utilization snapshots at various stages of the pipeline. Our simulations based on M-Sim (Sharkey, 2005) [1] show that our proposed mechanism improves IPC (Instruction Per Clock Cycle) by a very significant margin (up to 100.4%) without sacrificing execution fairness among threads. Performance improvement from the proposed integrated approach on the two shared resources easily surpasses the aggregated benefits from two control mechanisms with each considering only one individual resource at a time.