> I have been able to copy 1 GiB/s to userspace from an nvme device. I should
> think a radio should be no problem.

The problem is when you have multiple decoder blocks implemented
as individual processes (i.e. the GNU radio model).  Once you have
everything debugged, you can put it into a single threaded process
and eliminate the copy overhead.  But it's completely impractical
to prototype or debug real applications this way.  And it's the
prototyping case I'm interested in here.

So I'm *curious* to know if page flipping a 'protocol buffer' like
object between processes provides an optimization over copying
through the kernel.  Not so much for the speed aspect, but to free
up CPU cycles that can be devoted to actual SDR work.

Since when did curiosity become a capital crime?   Oh, wait, that
was January 20, 2017.  My bad.

--lyndon