[metrics-bugs] #25774 [Metrics/Ideas]: Record latency measurements using OnionPerf

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#25774: Record latency measurements using OnionPerf
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 Reporter:  irl            |          Owner:  metrics-team
     Type:  project        |         Status:  needs_review
 Priority:  Medium         |      Milestone:
Component:  Metrics/Ideas  |        Version:
 Severity:  Normal         |     Resolution:
 Keywords:                 |  Actual Points:
Parent ID:                 |         Points:
 Reviewer:  irl            |        Sponsor:
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Comment (by irl):

 Replying to [comment:4 karsten]:
 > Indeed, this might be related to us not using guards. And yes, we should
 investigate this more and document it.

 I've made a separate ticket for this: #26597

 > I was thinking of a graph like
 [https://metrics.torproject.org/connbidirect.html our "Fraction of
 connections used uni-/bidirectionally" graph]. There's some overlap in
 that graph, too. Anyway, we can decide later.

 Ah ok, I had not considered that the colours would be transparent. That is
 quite readable and more easily comparable in the time domain too.

 > > For parameters, the current parameters for the existing performance
 graphs are all applicable except that it probably does not make sense to
 have this for the onion measurements.
 >
 > Right, it doesn't make much sense to have this for public vs. onion
 measurements. Nor does it matter whether we're fetching 50 KiB, 1 MiB, or
 5 MiB files. Which basically leaves the source as parameter.

 Agreed.

 > Aha! I'll make another graph for that. Do we want to do the division-
 by-2 step here, which includes the implicit assumption that both
 directions are equally fast, or do we want to use a round-trip metric of
 some kind? Just thinking about what would be more intuitive, that is,
 least confusing for users.

 I think RTT is fine actually. I guess people have heard of "ping" which
 uses RTT not RTT/2. I guess also if there are relays on xDSL lines then
 they definitely will have different latencies for upstream/downstream and
 so dividing by 2 would really just be an average.

 Replying to [comment:5 karsten]:
 > I made a plot with round-trip latencies by onion vs. public server:
 > What do you think?

 This is really cool! I think using the transparent colours as in the
 connbidirect graph would be safe here to allow a more direct comparison
 between public/onion.

 Can you make a couple of graphs, one for circ build times and one for rtt
 using the transparent colours just to see them?

 > And was there another graph we discussed in Aberdeen that we could make
 from existing data? I vaguely recall we discussed three possible graphs,
 but I don't remember whether all three of them would use existing data.

 The third graph was I think scrapping the filesize parameters and instead
 using the percentile values. This is probably a different ticket if we
 choose to do it. (We might wait until I look at OnionPerf on LTE where we
 would want to be more conservative on bandwidth usage).

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/25774#comment:7>
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