#33076: Graph onionperf and consensus information from Rob's experiments -------------------------------------------------+------------------------- Reporter: mikeperry | Owner: | metrics-team Type: task | Status: | needs_review Priority: Medium | Milestone: Component: Metrics/Analysis | Version: Severity: Normal | Resolution: Keywords: metrics-team-roadmap-2020Q1, sbws- | Actual Points: 3 roadmap | Parent ID: #33121 | Points: 6 Reviewer: | Sponsor: -------------------------------------------------+-------------------------
Comment (by dennis.jackson): Using Karsten's code and dataset, I took another look at the onionperf measurements from over the course of Rob's experiment. == Time to First Byte This graph shows TTFB measurements over non-onion circuits from op-ab. The period in which the experiment was active is highlighted in red and the period in which the bandwidth values remained in the consensus is in orange. The lines show the 5th percentile, 50th percentile (median), the mean and the 95th percentile. [[Image(https://dennisjj.co.uk/tor-bandwidth-experiment/ttfb_public_op- ab.png,680px)]] The increase in congestion over the experimental window appears to be substantial, with the 95 percentile ttfb rising from under 2 seconds to over 10 seconds. The trend is much flatter for onion circuits. If we look at the raw data: [[Image(https://dennisjj.co.uk/tor-bandwidth-experiment/raw/exit_op- ab.png,680px)]] We see a band at the 10 second line. Karsten has already noted this in #31521 and his investigation suggests it happens when streams timeout from one circuit and get reattached to another. I wonder if some exit nodes could not keep up with the additional bandwidth leading to timeouts? == Bandwidth Measurements I have concerns about the reliability of the current dataset for the DL graphs. It contains only 2000 measurements over the month and none of the DL measurements appear to have finished successfully (have a non-null value for `getDataPercentiles().get(100)`). However, I might be misunderstanding onionperfs output format. == Further Thoughts * op-nl and op-usa reported no measurements between the 14th and the 16th of August, which makes it hard to use their data for this experiment. * There are a total of 10k ttfb measurements for the month of August. When you consider how many guard/middle/exit combinations there are, this really isn't that much data to work with. For example, it would have been interesting to drill down to how TTFB changed on the exit nodes whose weighting changed the most during this experiment, but there just aren't enough samples. * A full set of graphs, Jupyter Notebook with Python code and csv of the raw data: https://drive.google.com/open?id=1q1JRP5RdPEhQcDddh7KEST1aADMoiyt_ -- Ticket URL: <https://trac.torproject.org/projects/tor/ticket/33076#comment:23> Tor Bug Tracker & Wiki <https://trac.torproject.org/> The Tor Project: anonymity online
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