Predicting program execution times by analyzing static and dynamic program paths

Abstract

This paper describes a method to predict guaranteed and tight deterministic execution time bounds of a sequential program. The basic prediction technique is a static analysis based on simple timing schema for source-level language constructs, which gives accurate predictions in many cases. Using powerful user-provided information, dynamic path analysis refines looser predictions by eliminating infeasible paths and decomposing the possible execution behaviors in a pathwise manner. Overall prediction cost is scalable with respect to desired precision, controlling the amount of information provided. We introduce a formal path model for dynamic path analysis, where user execution information is represented by a set of program paths. With a well-defined practical high-level interface language, user information can be used in an easy and efficient way. We also introduce a method to verify given user information with known program verification techniques. Initial experiments with a timing tool show that safe and tight predictions are possible for a wide range of programs. The tool can also provide predictions for interesting subsets of program executions.