Jeff, if the value can change over time, is it thread safe? Tony Anthony Skjellum, PhD Professor of Computer Science and Software Engineering COLSA Professor of Cybersecurity and Information Assurance Director of the Auburn Cyber Research Center and Lead Cyber Scientist for Auburn Samuel Ginn College of Engineering Auburn University [email protected] or [email protected] cell: +1-205-807-4968 ; office: +1-334-844-6360 CONFIDENTIALITY: This e-mail and any attachments are confidential and may be privileged. If you are not a named recipient, please notify the sender immediately and do not disclose the contents to another person, use it for any purpose or store or copy the information in any medium. ________________________________________ From: mpi-forum <[email protected]> on behalf of Jeff Squyres (jsquyres) <[email protected]> Sent: Monday, February 15, 2016 4:34 PM To: MPI list Subject: [Mpi-forum] Question about MPI_Info set on communicators This question has come up in the Open MPI community: ----- MPI_Info_set(myinfo, "use_shared_memory", "yes"); MPI_Comm_set_info(comm, myinfo); MPI_Comm_get_info(comm, myinfo_returned); // Assume here that there was not enough shared memory available to use shared-memory for // communication on this comm, so MPI_Info_get() tells us that use_shared_memory is "no". // ...time passes, and now assume there is more shared-memory available MPI_Comm_dup_with_info(comm, &newcom); MPI_comm_get_info(newcom, myinfo_returned); ----- Should newcom have "use_shared_memory" set to "yes" or "no"? Arguments for "yes": - the user originally asked for "yes" - now there is shared memory available Arguments for "no": - the current value for "used_shared_memory" on the parent communicator is "no" Which should it be? MPI-3.1 6.4.2 p238 says: "...Returns in newcomer a new communicator with the same group or groups, same topology, same info hints, any copied cached information, but a new context (see Section 6.7.1)." So the specific question here is: what exactly does "Same info hints" mean? The user-specific hint, or the current value of the hint? -- Jeff Squyres [email protected] For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/ _______________________________________________ mpi-forum mailing list [email protected] http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi-forum