Investigate use of SO_TIMESTAMPING to get timestamps for sent packets

[brendonj]

Investigate whether SO_TIMESTAMPING will work for AMP, and if so, what is required to implement it.

Is SO_TIMESTAMPING available in popular kernels? Do we need particular hardware to make it work? Will it work with a variety of socket types (raw, tcp, udp)?

Can we replace the current packet timestamping calls that use gettimeofday() with this and retrieve actual sending times from the socket? Should we replace the receive timestamp code using SO_TIMESTAMP with this also?

See: https://www.kernel.org/doc/Documentation/networking/timestamping.txt

[brendonj]

Looks like udpstream and tcpping use gettimefoday() and sendto() instead of delay_send_packet(), if possible they should use the same approach as the other similar tests.