Estimation of Execution Time and Delays

International audienceThis chapter explains the usual methodology used to estimate worst case execution time (WCET) by static analysis. It analyzes three questions: (1) how to estimate delays due to interferences caused by another running program in multi-task systems; (2) how to analyze the execution time for more complex architectures in which the tasks share resources and therefore interfere with one another; and (3) what is the influence of the high-level design methods and their compilation on the WCET. The chapter presents the example of delays due to preemptions, and examines several approaches to compute the WCET of a task running on a multi-core architecture. The chapter lists some state-of-the-art tools dedicated to the WCET estimation. It also presents cache analysis techniques, and elements on the analysis of data caches and cache hierarchies. The analysis of the cache assigns a category to each instruction AlwaysHit, AlwaysMiss and NonClassified