WebTraff: A GUI for Web Proxy Cache Workload Modeling and Analysis

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WebTraffA GUI for Web Proxy Cache Workload
Modeling and Analysis

• Nayden Markatchev
• Carey Williamson
• Department of Computer Science
• University of Calgary

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Introduction

• What is WebTraff?
• - An extended and improved version of ProWGen
  (Proxy Workload Generator), including a GUI
  interface to a useful set of tools for Web
  traffic modeling and analysis
• Purpose To facilitate the easy generation and
  analysis of controllable and representative
  workloads for Web caching simulations

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Talk Overview

• WebTraff General Information
• System Requirements, Data Formats,
  Assumptions, Inputs, Outputs, Usage
• Simple Demo
• Using WebTraff to generate and analyze a
  workload, plus Web proxy cache simulation
• Questions and Discussion

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System Requirements

• Software Requirements
• Unix based environment running X windows
• cc, gcc, g, tcl 8.0 or newer, tk 8.0 or newer,
  wish, perl 5.0 or newer, gnuplot, gs

• Hardware Requirements
• 64 MB or more RAM
• 100 MB hard disk space (for storing long workload
  traces)

Future Work Port to Windows (volunteers?)
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Example of the Web Workload Trace Format Used in
WebTraff
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Overview of WebTraff

• The WebTraff toolkit provides three main
  functions
• Web workload trace generation
• Web workload trace analysis
• Web proxy cache simulation
• Graphs displayed in PostScript format

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WebTraff GUI Interface
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Web Workload Generation
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Web Workload Generation

• This portion of the tool provides a GUI to
  ProWGen Busari/Williamson 2001
• ProWGen models four key characteristics of Web
  proxy workloads.
• Zipf-like document popularity distribution
• High degree of one-time referencing
• Heavy-tailed file and transfer size distributions
• Temporal locality property in references

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Web Workload Generation (contd)

• Name of trace file being generated
• Sliding widgets for
• Number of references (lines) in a workload file
• Number of distinct Web objects in workload
• Percentage of objects that are one-timers
• Slope of Zipf-like document popularity profile
• Slope of Pareto tail for document size
  distribution
• Degree of statistical correlation (if any)
  between size and popularity for Web objects

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Web Workload Generation (contd)

• The notion of temporal locality refers to
  temporal correlation in referencing behaviour
  (e.g., recent past good predictor of near future)
• Four models for referencing behaviour
• Independent Reference Model (IRM)
• Static LRU Stack Model (SLRU)
• Dynamic LRU Stack Model (DLRU)
• New LRU Stack Model (NLRU)

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Web Workload Generation (contd)

• Popularity Bias parameter (hack!)
• This button was added to remedy a problem in
  earlier version of ProWGen, which tended to
  choose one-timers early in the trace and popular
  documents late in the trace
• Can now control this in workload generation
• Can visually check for stationarity of cache hit
  ratio during simulations

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Web Workload Analysis
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Web Workload Analysis

• Two main categories of analysis functions
• Time series analysis (on the left)
• Web workload analysis (on the right)
• Radio buttons, slide bars and text boxes
  available to control plotting characteristics

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Requests per Interval(time series plot)
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Bytes per Interval(time series plot)
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Popularity Distribution plot
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Document Size Distribution (zoomed)
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Log-Log Complementary Distribution (LLCD) plot
(size)
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LRU Stack Depth Analysis(time series plot)
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LRU Stack Depth Analysis(marginal distribution)
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Web Proxy Cache Simulation
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Web Proxy Cache Simulation

• Application-level caching simulation parameters
• Cache size
• Cache replacement policy
• Five replacement policies currently available
• Random replacement (RAND)
• First-In-First-Out (FIFO)
• Least-Recently-Used (LRU) (default setting)
• Least-Frequently-Used (LFU)
• Greedy-Dual-Size (GDS)

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DHR Results from Run Sizes
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DHR Results from Run Policies
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BHR Results from Run Policies
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Assessing Cache Steady State
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For More Information

• WebTraff toolkit
• http//www.cpsc.ucalgary.ca/carey/software.htm
• ProWGen A Synthetic Workload Generation Tool
  for the Simulation Evaluation of Web Proxy
  Caches
• Busari/Williamson, Computer Networks, Vol 38, No
  6, June 2002
• http//www.cpsc.ucalgary.ca/carey/publications.ht
  m
• Contact information
• Email carey,nayden_at_cpsc.ucalgary.ca