[Make-wifi-fast] less latency, more filling... for wifi

Bob McMahon bob.mcmahon at broadcom.com
Thu Oct 12 14:51:02 EDT 2017

Thanks Toke.  Let me look into this.  Is there packet loss during your
tests?   Can you share the output of the client and server per the error

With iperf 2 there is no TCP test exchange rather UDP test information is
derived from packets in flight.  The server determines a UDP test is
finished by detecting a negative sequence number in the payload.  In
theory, this should separate UDP tests.   The server detects a new UDP
stream is by receiving a packet from a new source socket.  If  the packet
carrying the negative sequence number is lost then summing across "tests"
would be expected (even though not desired) per the current design and
implementation.  We intentionally left this as is as we didn't want to
change the startup behavior nor require the network support TCP connections
in order to run a UDP test.

Since we know UDP is unreliable, we do control both client and server over
ssh pipes, and perform summing in flight per the interval reporting.
 Operating system signals are used to kill the server.    The iperf sum and
final reports are ignored.   Unfortunately, I can't publish this package
with iperf 2 for both technical and licensing reasons.   There is some skeleton
code in Python 3.5 with asyncio
<https://sourceforge.net/p/iperf2/code/ci/master/tree/flows/flows.py> that
may be of use.   A next step here is to add support for pandas
<http://pandas.pydata.org/index.html>, and possibly some control chart
<https://en.wikipedia.org/wiki/Control_chart> techniques (both single and
<http://www.itl.nist.gov/div898/handbook/pmc/section3/pmc34.htm>) for both
regressions and outlier detection.

On Thu, Oct 12, 2017 at 1:32 AM, Toke Høiland-Jørgensen <toke at toke.dk>

> Jesper Dangaard Brouer <brouer at redhat.com> writes:
> > If I use the --realtime option, I did run into issues where the server
> > thread would busypoll 100% after e.g. a client stopped a test
> > prematurely. And I had to kill it with -9.
> Sort of related (but not specific to the new features), I've had to
> add a restart of the iperf server to my test scripts. If I run more than
> one (UDP) test against the same server instance, it would report back
> the average throughput over all tests, including any idle period
> in-between. Which is obviously not terribly useful... :)
> -Toke
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