[Cake] Long-RTT broken again

Toke Høiland-Jørgensen toke at toke.dk
Mon Nov 2 11:53:48 EST 2015

Hi Jonathan

I see you reverted the in-kernel target scaling and reinstated the limit
on max queue length. Well, TCP now once again can't fill the pipe at
long RTTs when running through cake; see attached plot. And yes, the
userspace code did set target to 62.5ms here.

Since you obviously didn't like my previous fix, could you please do
something else about it? The current state is quite obviously broken.



P.S. I still think the scaling of the target should be in the kernel,
and that target should not be exposed to userspace at all.

P.P.S. If the above seems a bit blunt, it's because I'm somewhat annoyed
at you arbitrarily reverting a commit without (a) saying anything about
it and (b) adding another fix for the issue it was supposed to address.
Was going to start a long series of tests today and ended up having to
debug this instead. Grump.

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