To speak to the original question, I'd say bufferbloat
* is undesirable latency
* was discovered when adding buffers counter-intuitively /slowed
/packet flow.
That's so as to catch the reader's attention and immediately cast light
on the (memorable but mysterious) name.
--dave
On 2021-04-05 11:24 a.m., David Lang wrote:
On Mon, 5 Apr 2021, Stephen Hemminger wrote:
On Mon, 5 Apr 2021 08:46:15 -0400
Rich Brown <[email protected]> wrote:
Dave Täht has put me up to revising the current Bufferbloat article
on Wikipedia (https://en.wikipedia.org/wiki/Bufferbloat)
Before I get into it, I want to ask real experts for some
guidance... Here goes:
1) What is *our* definition of Bufferbloat? (We invented the term,
so I think we get to define it.)
a) Are we content with the definition from the bufferbloat.net site,
"Bufferbloat is the undesirable latency that comes from a router or
other network equipment buffering too much data." (This suggests
bufferbloat is latency, and could be measured in seconds/msec.)
b) Or should we use something like Jim Gettys' definition from the
Dark Buffers article (https://ieeexplore.ieee.org/document/5755608),
"Bufferbloat is the existence of excessively large (bloated) buffers
in systems, particularly network communication systems." (This
suggests bufferbloat is an unfortunate state of nature, measured in
units of "unhappiness" :-)
c) Or some other definition?
2) All network equipment can be bloated. I have seen (but not really
followed) controversy regarding the amount of buffering needed in
the Data Center. Is it worth having the Wikipedia article
distinguish between Data Center equipment and CPE/home/last mile
equipment? Similarly, is the "bloat condition" and its mitigation
qualitatively different between those applications? Finally, do any
of us know how frequently data centers/backbone ISPs experience
buffer-induced latencies? What's the magnitude of the impact?
3) The Wikipedia article mentions guidance that network gear should
accommodate buffering 250 msec of traffic(!) Is this a real "rule of
thumb" or just an often-repeated but unscientific suggestion? Can
someone give pointers to best practices?
4) Meta question: Can anyone offer any advice on making a wholesale
change to a Wikipedia article? Before I offer a fork-lift
replacement I would a) solicit advice on the new text from this
list, and b) try to make contact with some of the reviewers and
editors who've been maintaining the page to establish some bona
fides and rapport...
Many thanks!
Rich
I like to think of Bufferbloat as a combination of large buffers and
how algorithms react to those buffers.
I think there are two things
1. what bufferbloat is
bufferbloat is the result of memory getting cheaper faster than
bandwidth increased, combined with throughput benchmarking that
drastically penalized end-to-end retries.
I think this definition is pretty academic and not something to worry
about using.
2. why it's a problem
the problems show up when the buffer represents too much time worth of
data to transmit (the time between when the last byte in the buffer
gets inserted into the buffer and when it gets transmitted)
So in a high bandwidth environment (like a datacenter) you can use
much larger buffers than when you are on a low bandwidth line
David Lang
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David Collier-Brown, | Always do right. This will gratify
System Programmer and Author | some people and astonish the rest
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