| It is well known that out of order cores are over provisioned for exploiting ILP. This thesis proposes a dynamic technique for adapting datapath resources and the core issue width to maximize the energy efficiency of the core, while attempting to minimize any performance loss that results from the reconfiguration. The proposed technique tracks various performance metrics to switch the configurations as required. The thesis also proposes and evaluates a number of heuristics to drive the reconfigurations and avoid unnecessary mode changes and their associated performance overhead. Our evaluations using an updated Wattch-like parameterized power models on a detailed X86 microarchitectural simulator shows that we achieve a significant improvement in energy efficiency without any undue penalty on the overall CPU performance. |
