On 8/6/19 7:05 PM, grarpamp wrote: > On 8/6/19, Roger Dingledine <[email protected]> wrote: >> On Tue, Aug 06, 2019 at 05:31:39PM -0400, Rob Jansen wrote: >>> Today, I started running the speedtest on all relays in the network. > >> There will be another confusing (confounding) factor, which is that the >> ... >> as intended. :) So, call it another thing to keep an eye out for during >> the experiment. > > Someone here posted they were testing with sub-minute > durations... tens of seconds. That's unlikely enough to > allow TCP to adjust over everything in the circuit to really > measure "bandwidth". And is instead likely to be measuring > something between "setup latency" and that, with an > uncharacterized ramp in the middle. >
- That person was Rob, the one who just said they've started their measurements. Rob's original announcement is here[0]. - We've been looking into stuff like this for the last year and have some promising results from sub-minute-duration measurements with measurement hosts spread around the world. This is despite suspected sources of inaccuracy such as TCP slow start and high bandwidth delay products. - What Rob is doing isn't even trying to get an accurate measurement of a relay's capacity. It's solely to test the hypothesis that observed bandwidth is a poor estimate of capacity*. I refer again to [0] for the motivation, design, etc. > You probably want to be scatterplotting a bunch > of different things and durations on metrics.tpo. > > And isolating out path nodes and things from > whichever it is you're trying to measure. > Introducing known inputs. Etc. Thanks for the input. I'm sure our analysis of the collected data will be ... thorough and exciting. Matt * You might argue that an artificial 20 second or even 2 minute burst of traffic is still bad estimate for long term sustained capacity. That may be a good argument. But I'd argue that it's strictly better than the current strategy: keep track of your biggest natural 10 second burst observed in the last 5 days. [0]: https://lists.torproject.org/pipermail/tor-relays/2019-July/017535.html _______________________________________________ tor-relays mailing list [email protected] https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-relays
