An Apple patent (number 8,332,679) at the U.S. Patent & Trademark Office shows that Apple is working on new methods and apparatuses for managing power by leveraging intermediate power margins.
Per the patent, one or more subsystems of the system are operated at one or more performance points. A power consumed by the one or more subsystems at each of the one or more performance points is measured. An operational power of the one or more subsystems at the one or more performance points is determined. The one or more subsystems are operated at well-known conditions at the one or more performance points.
The operational power may be adjusted based on data associated with the one or more subsystems. The operational power is provided to a power lookup table. The power is distributed among the one or more subsystems based on the operational power.
Here’s Apple’s background on the invention: “Traditionally, computer systems are designed to be able to continuously run a fairly worst-case power load. Design according to such a continuous worst-case power load has never been much of a problem, because traditionally the individual components have had modest operating powers and the computer systems have had large power budgets so that the systems could sustain the load fairly naturally.
As the operating power consumptions of the individual components of computer system creep upwards, the power budgets of the computer systems have become tighter. It is now becoming a challenge to design a computer system to run a continuous worst-case workload while pursuing other high performance goals, such as high computing power, compactness, quietness, better battery performance, etc. For example, portable computer systems, such as laptop computers, have a limited battery output capability; and thus a worst-case workload for a given battery output capability may limit the performance of the system because the worst case workload may rarely occur.
Currently, substantially large additional power margins are thrown away to ensure that the critical thresholds are not exceeded during normal system operation. Typically, a substantially large plurality of sample components, or subsystems, is measured to produce a statistical power distribution curve. A worst-case power margin value for the components or subsystems is calculated from the statistical power distribution curve of a vast number of sample components using, for example, a “six sigma” method. The statistically calculated worst-case power margin is a single fixed substantially conservative number that is valid for all components or subsystems that provides a minimum guaranteed performance and does not value the performance efficiency of the computer system.”
The inventors are David G. Conroy, Michael Culbert and Keith A. Cox.