Technology Library

Sep 2005
Profiles In Power: Optimizing Real-time Systems for Power

ABSTRACT

High-performance, timing accurate models of complex systems (called Virtual System Prototypes (VSP)) enable the computation of relatively accurate power in terms of events that occur in the model. VSPs are the integrations of models of electronic hardware, communication and mechanical subsystems into systems that execute software accurately. Software has a first order impact on system performance and has, typically, the major effect on modern system optimization. The computation of relative power, although fundamental, is not useful by itself – doubling the talk time of a mobile phone is not useful if, concomitantly, the speed dwindles so that look-up functions take 20 seconds rather than the 2 seconds that competitors take. Power is an exemplar of the complex, concept-based functions, with many hardware, software and system parameters, that constitute optimization functions and will be treated in detail in this paper. The general form of a power computation function is given in the paper, as well as, a simple example of the implementation of a power calculator. The use of power, along with the other components of objective functions, such as speed (instructions per second), response latency and cost, must drive algorithm choice and software development in mobility and other power-performance sensitive applications. The use of VSPs is mandatory in specifying the hardware and software architectures of, and then building, complex optimal systems.