Constrained Power and Performance Optimization for Embedded Systems

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Constrained Power and Performance Optimization for Embedded SystemsThe goal of this research is to explore techniques for power management ofembedded systems with provable bounds on power efficiency as well as adverseeffects on latency due to power management. The current state of the art insystem-level power management is limited to shutting parts of a system aftera certain period of idle time, thus ignoring the application timingconstraints, runtime traffic and application usage information. This workwill develop power-performance control "knobs" that will allow us to makeeffective online decisions. Specific applications will include power-awareresource scheduling in RTOS, timing-aware power optimizations and tradeoffsbetween power savings and application quality of service (e.g., misseddeadlines).Our technical focus is on solving two key problems: (a) latency-constrainedpower optimization, i.e., minimization of system-level power consumptionwith constrains on the effect of system latency due to power management; and(b) power-constrained performance optimization, e.g., system-level taskimplementation and scheduling within a given power budget. As a first step,we focus on analytic bounds on the effectiveness of online power managementalgorithms and their efficiency by developing bounds on latency increasesdue to power management. We introduce the notion of a competitive ratio asa quantitative measure of how well a given power management algorithmperforms against an optimum power consumption profile. Next, we incorporatethese analytic bounds in a broader system-level timing and power simulationengine which enables an accurate performance simulation while minimizing thedetails related to actual system functionality. Our experimental evaluationis through RTOS implementation of new power management services throughcoordinated scheduling and resource shutdown.