This paper discusses an efficient approach to statically compute a WCET that is "soft" rather than "hard". The goal of most timing analysis is to determine a guaranteed WCET; however this execution time may be far above the actual distribution of observed execution times. A WCET estimate that bounds the execution time 99% of the time may be more useful for a designer in a soft real-time environment. This paper discusses an approach to measure the execution time distribution by a hardware simulator, and a path-based timing analysis approach to derive a static estimation of this same distribution. The technique can find a soft WCET for loops having any number of paths.
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