Performance Evaluation with Heavy Tailed Distributions

Over the last decade an important new direction has developed in the performance evaluation of computer systems: the study of heavy-tailed distributions. Loosely speaking, these are distributions whose tails follow a power-law with low exponent, in contrast to traditional distributions (e.g., Gaussian, Exponential, Poisson) whose tails decline exponentially (or faster). In the late ’80s and early ’90s experimental evidence began to accumulate that some properties of computer systems and networks showed distributions with very long tails [7,27,28], and attention turned to heavy-tailed distributions in particular in the mid ’90s [3,9,23,34,42].