[mpiwg-rma] Atomicity and Pair Types

[Mark Hoemmen]

On Wed, Sep 12, 2018 at 2:55 PM Balaji, Pavan via mpiwg-rma
<mpiwg-rma at lists.mpi-forum.org> wrote:
> Yes, correct.  Although, Nathan had a ticket at some point where he wanted to allow MPI to overwrite the padding bytes in such cases.

This issue of padding bytes in atomic updates to a struct came up in
the past few C++ meetings:

http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0528r3.html

For more explanation, see
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0528r0.html .
The goal is that compare-and-exchange shouldn't always return false if
the padding bits don't participate in the value representation of a
struct.

mfh