Event-based performance perturbation: a case study

Determining the performance behavior of parallel com-putations requires some form of intrusive tracing mea-surement. The greater the need for detailed perfor-mance data, the more intrusion the measurement will cause. Recovering actual execution performance jfrom perturbed performance measurements using event-based perturbation analysis is the topic of this paper. We show that the measurement and subsequent anal-ysis of synchronization operations (particularly, ad-vance and await) can produce, in practice, accurate approximations to actual performance behavior. We use as testcases three Lawrence Livermore loops that execute as parallel DOACROSS loops on an Alliant FX/80. The results of our experiments suggest that a systematic application of performance perturbation analysis techniques will allow more detailed, accurate instrumentation than traditionally believed possible.