[Bloat] Progress with latency-under-load tool

[Otto Solares Cabrera]

On Sun, Mar 20, 2011 at 12:45:10PM +0200, Jonathan Morton wrote:
> Attached is the initial version of the loadlatency tool.  I'm getting some rather interesting results from it already, although it does take a very long time to run.
> 
> It works under Linux, Cygwin and MacOS X on both little- and big-endian machines (and between machines of different byte-sexes), and therefore it should also work under FreeBSD and other UNIXes.  I haven't yet tried compiling it for iOS or Android.
> 
> It produces useful results even when one of the machines is rather old and slow, despite using a proper PRNG for traffic generation.  My ancient Pentium-MMX proved capable of generating at least 4.4 MB/s of traffic steadily, and probably produces spikes of even greater bandwidth.  Anything of Y2K vintage or newer should be able to saturate it's network with this.
> 
> There are four measures produced:  Upload Capacity, Download Capacity, Link Responsiveness and Flow Smoothness.  All of these are reported in "bigger is better" units to help deal with Layers 8 and 9.

Hello Jonathan,

Excellent tool! hopefully with more testing we can validate it's
results and improve it as testing all those scenarios seems the
correct path to understand bufferbloat and latency in our networks.

Sadly it's very difficult for a netadmin like me to follow your "units"
as the world have been standarized on bits per second in base10 or
decimal as opposed to the bytes per second in base2 or binary as
reported by this tool, "smoothness" too is a very radical unit to
measure latency which could be in milliseconds as the tool name implies.

Please don't take it as an offense but I cooked this small patch to
address this problems in the case you want to change it or for others
if they feel the need for more "normal" measuring units which in turn
can lead to more people testing their networks with this tool.

It's a diff against nbd's git repository, it seems to work for me but
honestly I have yet to figure out all the data it reports, hopefully
I didn't b0rk it too much :)
-
 Otto
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