Re: [PATCH 00/12] Add kdbus implementation

Andy Lutomirski wrote:

<snip>

There should be a number measured in, say, nanoseconds in here
somewhere.  The actual extent of the speedup is unmeasurable here.
Also, it's worth reading at least one of Linus' many rants about
zero-copy.  It's not an automatic win.

It's well-understood that it's not an automatic win; significant testing on 
multiple architectures indicated that 512K is a surprisingly universal 
crossover point. The userspace code, therefore, switches from copying 
(normal kdbus parameters) to zero-copy (memfds) right around there.