Page MenuHomeFreeBSD

tcp: Address goodput and TLP edge cases.

Authored by rrs on Jul 6 2021, 2:20 PM.



There are several cases where we make a goodput measurement and we are running
out of data when we decide to make the measurement. In reality we should not make
such a measurement if there is no chance we can have "enough" data. There is also
some corner case TLP's that end up not registering as a TLP like they should, we
fix this by pushing the doing_tlp setup to the actual timeout that knows it did
a TLP. This makes it so we always have the appropriate flag on the sendmap
indicating a TLP being done as well as count correctly so we make no more
that two TLP's.

In addressing the goodput lets also add a "quality" metric that can be viewed via
blackbox logs so that a casual observer does not have to figure out how good
of a measurement it is. This is needed due to the fact that we may still make
a measurement that is of a poorer quality as we run out of data but still have
a minimal amount of data to make a measurement.

Test Plan

Inside the NF lab run various test scenarios that create the edge cases
and validate that the quality metric is correct or we discard the measurements
all together. Also validate no cases where we TLP more than twice.

Diff Detail

rG FreeBSD src repository
Automatic diff as part of commit; lint not applicable.
Automatic diff as part of commit; unit tests not applicable.