Dont pring "using TCP window size of 64MB" on auto-tuning kernels. This is confusing.
I think the right way to do this is the following:
if -w is specified: print something like: N MB buffer requested: X MB buffer used (for cases the user requests a buffer bigger than the system max)
if no -w is specified, say "using system default for buffer setting", but dont print an actual value, as there isnt one with auto-tuning