System Simulation (CAP 4800) May 30, of xx Notes on Barford SURGE paper Ken Christensen Department of Computer Science and Engineering College of Engineering University of South Florida Tampa, FL

System Simulation (CAP 4800) May 30, of xx The Paper SIGMETRICS = Performance evaluation community

System Simulation (CAP 4800) May 30, of xx The abstract – first half Continued on next slide… Abstract == paper summary Abstract != paper introduction

System Simulation (CAP 4800) May 30, of xx The abstract – second half

System Simulation (CAP 4800) May 30, of xx Goal of the work Our goal is to imitate closely a stream of HTTP requests originating from a fixed population of Web users. For doing this better than anyone else Paul Barford earned a PhD.

System Simulation (CAP 4800) May 30, of xx On-Off model of web workload The key picture that “tells the story”

System Simulation (CAP 4800) May 30, of xx Key properties of web reference streams Six key properties 1)File size 2)Request size 3)Popularity 4)Embedded references 5)Temporal locality 6)Off times (inactive and active) Need to understand distribution and distribution parameters of each of the above.

System Simulation (CAP 4800) May 30, of xx Finding distributions and parameters More-or-less did curve fitting Matched measurements from traces to distributions Used statistical tests to gauge goodness of fit An eyeball test for matching curves (histograms) is sometimes the best statistical test!

System Simulation (CAP 4800) May 30, of xx Fitting continued Some fits (eyeballing)…

System Simulation (CAP 4800) May 30, of xx Fitting continued And finally…

System Simulation (CAP 4800) May 30, of xx Testing against SPECWeb And finally… SURGE SPECWeb

System Simulation (CAP 4800) May 30, of xx In conclusion…