Re: [Rpm] [Make-wifi-fast] [Cake] [Bloat] The most wonderful video ever about bufferbloat

[Bob McMahon <bob.mcmahon@broadcom.com>]

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I think conflating bufferbloat with latency misses the subtle point in that
bufferbloat is a measurement in memory units more than a measurement in
time units. The first design flaw is a queue that is too big. This youtube
video analogy doesn't help one understand this important point.

Another subtle point is that the video assumes AQM as the only solution and
ignores others, i.e. pacing at the source(s) and/or faster service rates. A
restaurant that let's one call ahead to put their name on the waitlist
doesn't change the wait time. Just because a transport layer slowed down
and hasn't congested a downstream queue doesn't mean the e2e latency
performance will meet the gaming needs as an example. The delay is still
there it's just not manifesting itself in a shared queue that may or may
not negatively impact others using that shared queue.

Bob



On Mon, Oct 10, 2022 at 2:40 AM Sebastian Moeller via Make-wifi-fast <
make-wifi-fast@lists.bufferbloat.net> wrote:

> Hi Erik,
>
>
> > On Oct 10, 2022, at 11:32, Taraldsen Erik <erik.taraldsen@telenor.no>
> wrote:
> >
> > On 10/10/2022, 11:09, "Sebastian Moeller" <moeller0@gmx.de> wrote:
> >
> >    Nice!
> >
> >> On Oct 10, 2022, at 07:52, Taraldsen Erik via Cake <
> cake@lists.bufferbloat.net> wrote:
> >>
> >> It took about 3 hours from the video was release before we got the
> first request to have SQM on the CPE's  we manage as a ISP.  Finally
> getting some customer response on the issue.
> >
> >       [SM] Will you be able to bump these requests to higher-ups and at
> least change some perception of customer demand for tighter latency
> performance?
> >
> > That would be the hope.
>
>         [SM} Excellent, hope this plays out as we wish for.
>
>
> >  We actually have fq_codel implemented on the two latest generations of
> DSL routers.  Use sync rate as input to set the rate.  Works quite well.
>
>         [SM] Cool, if I might ask what fraction of the sync are you
> setting the traffic shaper for and are you doing fine grained overhead
> accounting (or simply fold that into a grand "de-rating"-factor)?
>
>
> > There is also a bit of traction around speedtest.net's inclusion of
> latency under load internally.
>
>         [SM] Yes, although IIUC they are reporting the interquartile mean
> for the two loaded latency estimates, which is pretty conservative and only
> really "triggers" for massive consistently elevated latency; so I expect
> this to be great for detecting really bad cases, but I fear it is too
> conservative and will make a number of problematic links look OK. But hey,
> even that is leaps and bounds better than the old only idle latency report.
>
>
> > My hope is that some publication in Norway will pick up on that score
> and do a test and get some mainstream publicity with the results.
>
>         [SM] Inside the EU the challenge is to get national regulators and
> the BEREC to start bothering about latency-under-load at all, "some
> mainstream publicity" would probably help here as well.
>
> Regards
>         Sebastian
>
>
> >
> > -Erik
> >
> >
> >
>
> _______________________________________________
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> Make-wifi-fast@lists.bufferbloat.net
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