Greg Kroah-Hartman started off the 188.8.131.52
in the usual way: a posting of all patches proposed for
inclusion in that kernel release. The development community was invited to
complain about any patches which do not appear to meet the criteria
for the extra-stable 2.6
kernels. This time around, somebody complained.
The patch in question is a fix to the BIC
TCP congestion control algorithm (congestion avoidance, including BIC, was
covered here two weeks ago). BIC is
supposed to perform a binary search to quickly find the optimal congestion
window size. Due to a mistake in the TCP dropped packet code, however,
that search was not being performed, and BIC was not working as expected.
The (very small) patch makes BIC work the way its designers intended, and
would seem to be a useful addition.
As Ted Ts'o pointed out, however, the rules
for these kernels include:
It must fix a real bug that bothers people (not a, "This could be a
problem..." type thing.)
It is safe to say that the kernel mailing lists have not been overwhelmed
by users complaining that BIC was not converging properly on the best
congestion window size. In fact, no users have complained. So, it could
be argued, the BIC fix, while worthy, should be merged for 2.6.12 and left
out of the 2.6.11.x series.
An answer came from David Miller:
An incorrect implementation of any congestion control algorithm has
ramifications not considered when the congestion control author
verified the design of his algorithm. This has a large impact on
every user on the internet, not just Linux machines.
David concluded that, since BIC is enabled by default in the 2.6 kernel,
this sort of implementation fix should take a high priority. This view
seems likely to prevail for this particular patch. Expect more debates,
however, as the kernel developers figure out just where the line should be
drawn for patches being considered for inclusion into the stable 2.6
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