[Bloat] Updated Bufferbloat Test

Wed Feb 24 18:39:33 EST 2021

Agreed - average jitter is useless, needs to be peak/maximum. Disallowing a 
very small number of exception points is ok.

Simon

On February 24, 2021 2:10:55 PM Dave Taht <dave.taht at gmail.com> wrote:

> So I've taken a tiny amount of time to run a few tests. For starters,
> thank you very much
> for your dedication and time into creating such a usable website, and faq.
>
> I have several issues though I really haven't had time to delve deep
> into the packet captures. (others, please try taking em, and put them
> somewhere?)
>
> 0) "average" jitter is a meaningless number. In the case of a
> videoconferencing application,
> what matters most is max jitter, where the app will choose to ride the
> top edge of that, rather than follow it. I'd prefer using a 98%
> number, rather than 75% number, to weight where the typical delay in a
> videoconfernce might end up.
>
> 1) The worst case scenario of bloat affecting a users experience is
> during a simultaneous up and download, and I'd rather you did that
> rather than test them separately. Also you get
> a more realistic figure for the actual achievable bandwidth under
> contention and can expose problems like strict priority queuing in one
> direction or another locking out further flows.
>
> 2) I get absurdly great results from it with or without sqm on on a
> reasonably modern cablemodem (buffercontrol and pie and a cmts doing
> the right things)
>
> This points to any of number of problems (features!) It's certainly my
> hope that all the cdn makers at this point have installed bufferbloat
> mitigations. Testing a cdn's tcp IS a great idea, but as a
> bufferbloated test, maybe not so much.
>
> The packet capture of the tcp flows DOES show about 60ms jitter... but
> no loss. Your test shows:
>
> https://www.waveform.com/tools/bufferbloat?test-id=6fc7dd95-8bfa-4b76-b141-ed423b6580a9
>
> And is very jittery in the beginning of the test on its estimates. I
> really should be overjoyed at knowing a cdn is doing more of the right
> things, but in terms of a test... and linux also has got a ton of
> mitigations on the client side.
>
> 3) As a side note, ecn actually is negotiated on the upload, if it's
> enabled on your system.
> Are you tracking an ecn statistics at this point (ecnseen)? It is not
> negotiated on the download (which is fine by me).
>
> I regrettable at this precise moment am unable to test a native
> cablemodem at the same speed as a sqm box, hope to get further on this
> tomorrow.
>
> Again, GREAT work so far, and I do think a test tool for all these
> cdns - heck, one that tested all of them at the same time, is very,
> very useful.
>
> On Wed, Feb 24, 2021 at 10:22 AM Sina Khanifar <sina at waveform.com> wrote:
>>
>> Hi all,
>>
>> A couple of months ago my co-founder Sam posted an early beta of the
>> Bufferbloat test that we’ve been working on, and Dave also linked to
>> it a couple of weeks ago.
>>
>> Thank you all so much for your feedback - we almost entirely
>> redesigned the tool and the UI based on the comments we received.
>> We’re almost ready to launch the tool officially today at this URL,
>> but wanted to show it to the list in case anyone finds any last bugs
>> that we might have overlooked:
>>
>> https://www.waveform.com/tools/bufferbloat
>>
>> If you find a bug, please share the "Share Your Results" link with us
>> along with what happened. We capture some debugging information on the
>> backend, and having a share link allows us to diagnose any issues.
>>
>> This is really more of a passion project than anything else for us –
>> we don’t anticipate we’ll try to commercialize it or anything like
>> that. We're very thankful for all the work the folks on this list have
>> done to identify and fix bufferbloat, and hope this is a useful
>> contribution. I’ve personally been very frustrated by bufferbloat on a
>> range of devices, and decided it might be helpful to build another
>> bufferbloat test when the DSLReports test was down at some point last
>> year.
>>
>> Our goals with this project were:
>>   * To build a second solid bufferbloat test in case DSLReports goes down again.
>>   * Build a test where bufferbloat is front and center as the primary
>> purpose of the test, rather than just a feature.
>>   * Try to explain bufferbloat and its effect on a user's connection
>> as clearly as possible for a lay audience.
>>
>> A few notes:
>>   * On the backend, we’re using Cloudflare’s CDN to perform the actual
>> download and upload speed test. I know John Graham-Cunning has posted
>> to this list in the past; if he or anyone from Cloudflare sees this,
>> we’d love some help. Our Cloudflare Workers are being
>> bandwidth-throttled due to having a non-enterprise grade account.
>> We’ve worked around this in a kludgy way, but we’d love to get it
>> resolved.
>>   * We have lots of ideas for improvements, e.g. simultaneous
>> upload/downloads, trying different file size chunks, time-series
>> latency graphs, using WebRTC to test UDP traffic etc, but in the
>> interest of getting things launched we're sticking with the current
>> featureset.
>>   * There are a lot of browser-specific workarounds that we had to
>> implement, and latency itself is measured in different ways on
>> Safari/Webkit vs Chromium/Firefox due to limitations of the
>> PerformanceTiming APIs. You may notice that latency is different on
>> different browsers, however the actual bufferbloat (relative increase
>> in latency) should be pretty consistent.
>>
>> In terms of some of the changes we made based on the feedback we
>> receive on this list:
>>
>> Based on Toke’s feedback:
>> https://lists.bufferbloat.net/pipermail/bloat/2020-November/015960.html
>> https://lists.bufferbloat.net/pipermail/bloat/2020-November/015976.html
>>   * We changed the way the speed tests run to show an instantaneous
>> speed as the test is being run.
>>   * We moved the bufferbloat grade into the main results box.
>>   * We tried really hard to get as close to saturating gigabit
>> connections as possible. We redesigned completely the way we chunk
>> files, added a “warming up” period, and spent quite a bit optimizing
>> our code to minimize CPU usage, as we found that was often the
>> limiting factor to our speed test results.
>>   * We changed the shield grades altogether and went through a few
>> different iterations of how to show the effect of bufferbloat on
>> connectivity, and ended up with a “table view” to try to show the
>> effect that bufferbloat specifically is having on the connection
>> (compared to when the connection is unloaded).
>>   * We now link from the results table view to the FAQ where the
>> conditions for each type of connection are explained.
>>   * We also changed the way we measure latency and now use the faster
>> of either Google’s CDN or Cloudflare at any given location. We’re also
>> using the WebTiming APIs to get a more accurate latency number, though
>> this does not work on some mobile browsers (e.g. iOS Safari) and as a
>> result we show a higher latency on mobile devices. Since our test is
>> less a test of absolute latency and more a test of relative latency
>> with and without load, we felt this was workable.
>>   * Our jitter is now an average (was previously RMS).
>>   * The “before you start” text was rewritten and moved above the start button.
>>   * We now spell out upload and download instead of having arrows.
>>   * We hugely reduced the number of cross-site scripts. I was a bit
>> embarrassed by this if I’m honest - I spent a long time building web
>> tools for the EFF, where we almost never allowed any cross-site
>> scripts. * Our site is hosted on Shopify, and adding any features via
>> their app store ends up adding a whole lot of gunk. But we uninstalled
>> some apps, rewrote our template, and ended up removing a whole lot of
>> the gunk. There’s still plenty of room for improvement, but it should
>> be a lot better than before.
>>
>> Based on Dave Collier-Brown’s feedback:
>> https://lists.bufferbloat.net/pipermail/bloat/2020-November/015966.html
>>   * We replaced the “unloaded” and “loaded” language with “unloaded”
>> and then “download active”  and “upload active.” In the grade box we
>> indicate that, for example, “Your latency increased moderately under
>> load.”
>>   * We tried to generally make it easier for non-techie folks to
>> understand by emphasizing the grade and adding the table showing how
>> bufferbloat affects some commonly-used services.
>>   * We didn’t really change the candle charts too much - they’re
>> mostly just to give a basic visual - we focused more on the actual
>> meat of the results above that.
>>
>> Based on Sebastian Moeller’s feedback:
>> https://lists.bufferbloat.net/pipermail/bloat/2020-November/015963.html
>>   * We considered doing a bidirectional saturating load, but decided
>> to skip on implementing it for now. * It’s definitely something we’d
>> like to experiment with more in the future.
>>   * We added a “warming up” period as well as a “draining” period to
>> help fill and empty the buffer. We haven’t added the option for an
>> extended test, but have this on our list of backlog changes to make in
>> the future.
>>
>> Based on Y’s feedback (link):
>> https://lists.bufferbloat.net/pipermail/bloat/2020-November/015962.html
>>   * We actually ended up removing the grades, but we explained our
>> criteria for the new table in the FAQ.
>>
>> Based on Greg White's feedback (shared privately):
>> * We added an FAQ answer explaining jitter and how we measure it.
>>
>> We’d love for you all to play with the new version of the tool and
>> send over any feedback you might have. We’re going to be in a feature
>> freeze before launch but we'd love to get any bugs sorted out. We'll
>> likely put this project aside after we iron out a last round of bugs
>> and launch, and turn back to working on projects that help us pay the
>> bills, but we definitely hope to revisit and improve the tool over
>> time.
>>
>> Best,
>>
>> Sina, Arshan, and Sam.
>> _______________________________________________
>> Bloat mailing list
>> Bloat at lists.bufferbloat.net
>> https://lists.bufferbloat.net/listinfo/bloat
>
>
>
> --
> "For a successful technology, reality must take precedence over public
> relations, for Mother Nature cannot be fooled" - Richard Feynman
>
> dave at taht.net <Dave Täht> CTO, TekLibre, LLC Tel: 1-831-435-0729
> _______________________________________________
> Bloat mailing list
> Bloat at lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/bloat

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.bufferbloat.net/pipermail/bloat/attachments/20210224/4ccdefa7/attachment-0001.html>