[Cake] Testing variants of the MTU latency scaling

[Jonathan Morton]

> Based on all this, I propose we change the scaling mechanism so that it
> is only active in egress mode, and change it from 4 MTUs to 2. I'll
> merge Kevin's patch to do this unless someone complains loudly :)

I suppose that makes enough sense.  But let me look over the patch again - there's probably a better way to do it.

 - Jonathan Morton