Copyright by William Lloyd Bircher 2010 - The Laboratory for ...

execution, portions of pipelines or functional units can be effectively resized through
clock gating and power gating when not needed. The challenge is to apply these power
saving adaptations only when the transition cost can be amortized by long idle phases.
By defining prediction metrics for each functional unit, it is possible to detect and predict
the critical long-duration idle phases.
Process-Level Power Accounting
The entirety of this dissertation and other performance-counter power modeling research
focuses on attributing power to a particular hardware thread or core. The limitation of
this approach is that process scheduling and migration can impact the ability to discern
unique program phases. It is likely that tracking power and phase history at the process-
level will reduce aliasing thus improving predictability.
Scheduling using On-line Power and Performance Models
Another application of power accounting is for the direction of scheduling decisions. By
introducing performance models that are power-aware, optimal scheduling and power
management decisions can be made. The current state-of-the-art architectural power
adaptations provide a range of throughput and latency at the processor core-level.
Expressing those impacts as run-time power and performance models would allow major
improvements in energy efficiency and performance.
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