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7 Barriers to Accuracy

In this section, we examine five primary causes of the remaining difference between the current live accuracy and what appears to be achievable based on simulation results. The five barriers are: churn, drift, intrinsic error, corruption, and latency variance. We present techniques that address the first three barriers and non-malicious corruption. However, malicious corruption and latency variance remain unsolved; indeed, the latter requires a fundamentally new approach to latency prediction. Based on our simulation and PlanetLab results and on monitoring Azureus over time, we have added the techniques that address churn, drift, and non-malicious corruption to the Azureus code. While preliminary experiments suggest they function as expected, we have not yet fully quantified their effects and do not include results for them here.

Subsections

• 7.1 Churn
• 7.2 Drift
• 7.3 Intrinsic Error
• 7.4 Corruption and Versioning
• 7.5 Latency Variance