My group (a project called Isis2) is experimenting with RDMA. We're puzzled by the lack of documentation for the atomicity guarantees of one-sided RDMA reads. I've spent the past hour and a half hunting for any kind of information at all on this to no avail. This includes close reading of the blog at rdmamojo.com, famous for having answers to every RDMA question...
In the case we are focused on, we want to have writers doing atomic writes for objects that will always fit within a single cache line. Say this happens on machine A. Then we plan to have a one-sided atomic RDMA reader on machine B, who might read chunks of memory from A, spanning many of these objects (but again, no object would ever be written non-atomically, and all will fit within some single cache line). So B reads X, Y and Z, and each of those objects lives in one cache line on A, and was written with atomic writes.
Thus the atomic writes will be local, but the RDMA reads will arrive from remote machines and are done with no local CPU involvement.
Are our one-sided reads "semantically equivalent" to atomic local reads despite being initiated on the remote machine? (I suspect so: otherwise, one-sided RDMA reads would be useless for data that is ever modified...). And where are the "rules" documented?