[Bloat] an observation from the field

[Jonas Mårtensson]

Hi Jonathan,

On Wed, Aug 29, 2018 at 2:16 AM Jonathan Morton <chromatix99 at gmail.com>
wrote:

> > On 29 Aug, 2018, at 2:53 am, David Collier-Brown <davec-b at rogers.com>
> wrote:
> >
> > Humans experience delays directly, and so perceive systems with high
> latency as "slow". The proverbial "man on the Clapham omnibus" therefor
> responds to high-latency systems with disgust.
> >
> > A trained scientist, however, runs the risk of choosing something that
> requires complicated measurement schemes, and might well choose to optimize
> for throughput, as that sounds like a desirable measure, one matching their
> intuitions of what "fast" means.
>
> The correct approach, for scientists, is to observe that for many
> applications, response time (a form of latency) is the *only* relevant
> metric.  In some cases, higher bandwidth correlates with reduced response
> time, such as for software updates.  In other cases, bandwidth is
> essentially irrelevant, except as it pertains to serialisation delay of
> single packets.
>

Yes, exactly, thank you for bringing some actual scientific reasoning into
the discussion. It would actually be nice to have a tool for measuring
"response time" for different applications


>
> Conversely, there are some applications for which sufficient bandwidth is
> not a matter of response time, but a threshold prerequisite for correct
> operation.  We can refer to these as isochronous applications, or choose
> another term if you prefer.  Video streaming is an example of this; given
> an a-priori chosen video codec setting, if the data it produces cannot be
> transferred as fast as it is produced, the receiver will not be able to
> play it back in synchrony.
>
> YouTube can reliably stream Full-HD (1080p60) video down a 10Mbps
> debloated pipe.  The broadband standard in the US claims that 25Mbps is
> necessary for this precise application.


No, it doesn't. It claims the opposite, i.e. that 10Mbps is sufficient for
streaming one HD video but with 25Mbps you can stream two HD videos or one
4K video, see Table 1 in the FCC report:

https://docs.fcc.gov/public/attachments/FCC-15-10A1.pdf

/Jonas


> Draw your own conclusions.
>
>  - Jonathan Morton
>
> _______________________________________________
> 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/20180829/a39ef174/attachment-0002.html>