Stephen Hemminger wrote:
On Thu, 28 Sep 2006 11:07:18 +0100
Douglas Leith <[EMAIL PROTECTED]> wrote:
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Steve,
I think we're all conscious of the fact that recent history contains
quite a number of proposals for changes to tcp's congestion control
algorithm for high bandwidth-delay product paths that on closer
inspection have proved problematic in one way or another. It seems to
be a hard problem to solve, so maybe that's fair enough and hopefully
we'll end up with a workable solution soon.
Where I'm coming from here though is that bic was made the linux default
a year or so ago at a time when there were essentially no tests
available on its performance other than the infocom paper by Injong.
Subsequent tests have since highlighted a bunch of issues with bic. To
my knowledge, we're currently in a similar situation with cubic as we
were with bic back then i.e. essentially no independent tests
investigating its behaviour.
Of course I know Injong has posted some test results, but these are
hardly independent as he's the author of both bic and cubic. Have there
perhaps been private tests carried out (e.g. by osdl) ? If so, would it
be possible to make them public ? If not, well that would be good to
know too.
My tests have been limited and showed no difference. It is worthy
of more discussion as to what is best. Could you rerun your tests?
Unfortunately we haven't really looked at cubic at all to date as I
didn't appreciate it was being seriously considered for the new default
until Ian's post a few days ago. It'll take a little time to free up
some bandwidth in people's time here, but we'd be happy to rerun the
previous tests with cubic as a priority and generally try to have an
initial poke around.
Doug
Hamilton Institute
www.hamilton.ie
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