Re: [Bloat] DSLReports Speed Test has latency measurement built-in

["Toke Høiland-Jørgensen" <toke@toke.dk>]

jb <justin@dslr.net> writes:

> Ok I think I talked myself around in a complete circle: a buffer is
> only bad IF it increases latency under load. Not because of its size.

Exactly! :)

Some buffering is actually needed to absorb transient bursts. This is
also the reason why smart queue management is needed instead of just
adjusting the size of the buffer (setting aside that you don't always
know which speed to size it for).

> It might explain why these fiber connection tests don't show much
> latency change, because their buffers are really inconsequential at
> those higher speeds?

Well, bufferbloat certainly tends to be *worse* at lower speeds. But it
can occur at gigabit speeds as well. For instance, running two ports
into one on a gigabit switch can add quite a bit of latency.

For some devices, *driving* a fast link can be challenging, though. So
for fibre connections you may not actually bottleneck on the bloated
link, but on the CPU, some other link that's not as bloated as the
access link, etc...

-Toke