netmap pipes

[Slawa Olhovchenkov]

On Sat, Jan 03, 2015 at 07:13:04PM +0100, Luigi Rizzo wrote:

> > Can I write to slave and read from master?
> 
> pipes are bidirectional and blocking. So you can write
> on one and read from the other, in any order.

What you mean 'blocking'? Can't be used in select/poll (as blocking
disk IO)?

> This is a 'power user' feature which maybe is not what you need
> (and at the moment I don't have time to explain in more detail
> or update the manpage).
> Pipes share memory with the netmap port (VALE port or NIC) with the
> same basename, and since memory allocation occurs at once, on the
> first open you need to tell the OS how many pipes need to share
> memory with the same port -- that is the role of nr_arg1.

Can you also explain relations between

dev.netmap.ring_size
dev.netmap.buf_num
open interfaces
rings per interfaces
slots per rings

and zerocopy conditions?