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Publication : ParaScale: Exploiting Parametric Timing Analysis for Real-Time Schedulers and Dynamic Voltage Scaling

Authors : Sibin Mohan, Frank Mueller, William Hawkins, Michael Root, Christopher Healy and David Whalley.

Abstract :
Static timing analysis safely bounds worst-case execution times to determine if tasks can meet their deadlines in hard real-time systems. However, conventional timing analysis requires that the upper bound of loops be known statically, which limits its applicability. Parametric timing analysis methods remove this constraint by providing the WCET as a formula parameterized on loop bounds.

This paper contributes a novel technique to allow parametric timing analysis to interact with dynamic real-time schedulers. By dynamically detecting actual loop bounds, a lower WCET bound can be calculated, on-the-fly, for the remaining execution of a task. We analyze thebenefits from parametric analysis in terms of dynamically discovered slack in a schedule. We then assess the potential for dynamic power conservation by exploiting parametric loop bounds for ParaScale, our intra-task dynamic voltage scaling (DVS) approach. Our results demonstrate that the parametric approach to timing analysis provides significant savings, close to 66 \%, in terms of slack as well as power. We further show that using this approach combined with online intra-task DVS to exploit parametric execution times results in much lower power consumption. Hence, even in the absence of dynamic scheduling, significant savings in power can be obtained,
e.g.,in the case of cyclic executives.

Here is a link to the full paper and the slides to the talk at RTSS 2005.

This was published in the IEEE Real-Time Systems Symposium (RTSS), December, 2005.
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