Date Added: Mar 2012
Numerous data center services exhibit low average utilization leading to poor energy efficiency. Although CPU voltage and frequency scaling historically has been an effective means to scale down power with utilization, transistor scaling trends are limiting its effectiveness and the CPU is accounting for a shrinking fraction of system power. Recent research advocates the use of full-system idle low-power modes to combat energy losses, as such modes provide the deepest power savings with bounded response time impact. However, the trend towards increasing cores per die is undermining the effectiveness of these sleep modes, particularly for request-parallel data center applications, because the independent idle periods across individual cores are unlikely to align by happenstance.