Re: [RFC PATCH v4 net-next 1/4] tcp: replace cnt & rtt with struct in pkts_acked()

On Mon, Jul 27, 2015 at 07:30:39PM +0000, Lawrence Brakmo wrote:

I prefer the cleanliness of passing a structure and don¹t think the
overhead will be significant enough to worry about it.
Will the compiler pass struct values in registers if the struct is
passed by value?

In passing struct by value it's not a matter of optimization but C abi.
On sparc even 4-byte structs are passed by reference which creates
an extra copy of the same struct on stack.
Struct returns are even worse. I would always pass structs by reference
in C. C++ is different matter.