Document threading properties of Ifce

[calder]

Starter questions:

• Can multiple goroutines concurrently Read from the same Ifce?
• Can multiple goroutines concurrently Write to the same Ifce?
• Are there performance bottlenecks that limit Read and Write calls by multiple threads?

[songgao]

Each interface corresponds to a file descriptor, so it probably doesn’t make sense to have multiple threads working on the same interface. If The goal is to have parallel streams to increase throughout, Linux has multiqueue support for TUN/TAP: https://www.kernel.org/doc/Documentation/networking/tuntap.txt

[songgao]

Closing. Feel free to reopen if you have further questions.