Performance Measurement and Modeling with the Lost Cycles Toolkit

Although there are many situations in which a model of application performance is valuable, performance modeling of parallel programs is not commonplace, largely because of the diiculty of developing accurate models of real applications executing on real multiprocessors. This paper describes a toolkit for performance tuning and prediction based on lost cycles analysis. Lost cycles analysis decomposes parallel overheads into meaningful categories that are amenable to modeling, and uses a priori knowledge of the sources and characteristics of overhead in parallel systems to guide and constrain the modeling process. The Lost Cycles Toolkit automates the process of constructing a performance model for a parallel application by integrating empirical model-building techniques from statistics with measurement and modeling techniques for parallel programs. We present several examples to show how the toolkit facilitates the construction of performance models, and to illustrate the use of the toolkit in solving practical performance problems.