Characterizing temporal locality and its impact on web server performance
Ludmila A. Cherkasova, Gianfranco Ciardo · 2002
The presence of temporal locality in web traces has long been recognized. However, the close proximity of requests for the same file in a trace can be attributed to two orthogonal reasons: long-term popularity and short-term correlation. The former reflects the fact that requests for a popular document appear "frequently" thus they are likely to be "close" in an absolute sense. The latter reflects the fact that requests for a given document might concentrate around particular points in the trace due to a variety of reasons, such as deadlines or surges in user interests, hence it focuses on "relative" closeness. We introduce a new measure of temporal locality, the scaled stack distance, which is insensitive to popularity and captures instead the impact of short-term correlation, and use it to parameterize a synthetic trace generator. Then, we validate the appropriateness of this quantity by comparing the file and byte miss ratios corresponding to either the original or the synthetic traces.