[Bloat] an observation from the field

[Jonathan Morton]

> 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.

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.  Draw your own conclusions.

 - Jonathan Morton