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

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 the
benefits 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 66\%-80\% additional savings in power consumption.
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, {\em e.g.},
in the case of cyclic executives.