Energy-Efficient Power Delivery System Paradigms for Many-Core Processors.

The design of power delivery system plays a crucial role in guaranteeing the proper functionality of many-core processor systems. The power loss suffered on power delivery has become a salient part of total power consumption, and the energy efficiency of a highly dynamic system has been significantly challenged. Being able to achieve a fast response time and multiple voltage domain control, on-chip voltage regulators (VRs) have become popular choices to enable fine-grain power management, which also enlarge the design space of power delivery systems. This paper analytically studies different power delivery system paradigms and power management schemes in terms of energy efficiency, area overhead, and power pin occupation. The analysis shows that compared to the conventional paradigm with off-chip VRs, hybrid paradigms with both on-chip and off-chip VRs are able to maintain high efficiency in a larger range of workloads, though they suffer from low efficiency at light workload. Employed with the quantized power management scheme, the hybrid paradigm can improve the system energy efficiency at light workload by a maximum of 136% compared to the traditional load balanced scheme. Besides this, the in-package (iP) hybrid paradigm further shows its advantage in reducing the physical overheads. The results reveal that at 120 W workload, it occupies only a 10.94% total footprint area or 39.07% power pins of that of the off-chip paradigm. We conclude that the iP hybrid paradigm achieves the best tradeoffs between efficiency, physical overhead, and realization of fine-grain power management.