[Cake] overheads or rate calculation changed?

[Jonathan Morton]

> On 23 Dec, 2017, at 11:03 pm, Sebastian Moeller <moeller0 at gmx.de> wrote:
> 
> just had a look for hard_header_len in the linux kernel:
> linux/include/linux/netdevice.h:
> *      @hard_header_len: Maximum hardware header length.
> *      @min_header_len:  Minimum hardware header length
> 
> this seems to corroborate our observation that hard_header_len is not a veridical representation of the actual hardware header length, so I assume the values cake returns are actually true. It also indicates that except for pure ethernet interfaces hard_header_len is _not_ the right parameter to evaluate for what cake is evaluating it for...

I'll keep that in mind for my review pass.

 - Jonathan Morton