[Bloat] SO_SNDBUF and SO_RCVBUF

[Rick Jones]

> netperf -t TCP_STREAM" uses a default size of 16384 bytes per sendmsg.

Under Linux at least, and only because that is the default initial value 
for SO_SNDBUF for a TCP socket (via tcp_wmem).

More generally, the default send size used by netperf is the value of 
SO_SNDBUF for the data socket immediately after its creation.

rick