[mpiwg-rma] same_op_no_op

[Jeff Hammond]

Given the following, how do I use MPI_NO_OP, MPI_REPLACE and MPI_SUM
in accumulate/atomic operations in a standard-compliant way?

accumulate_ops — if set to same_op, the implementation will assume
that all concurrent accumulate calls to the same target address will
use the same operation. If set to same_op_no_op, then the
implementation will assume that all concurrent accumulate calls to the
same target address will use the same operation or MPI_NO_OP. This can
eliminate the need to protect access for certain operation types where
the hardware can guarantee atomicity. The default is same_op_no_op.

We discuss this before and the resolution was not satisfying to me.

Thanks,

Jeff

-- 
Jeff Hammond
jeff.science at gmail.com