Hi George, sorry, was on leave for the last couple of days due to the "street carnival" (https://en.wikipedia.org/wiki/Carnival_in_Germany,_Switzerland_and_Austria#R...)

Assuming that the usual precautions are taken, aka. tools and libraries create their own communicators, I fail to see how the user hints on it's communicators can have any impact on libraries/tools ?

As Jim already pointed out in his reply, the problem arises when we try to match messages solely on the envelope information. With this assertion active, correct message matching in a replay as done by Scalasca cannot be guaranteed, and neither can the wrong matching be detected. During the course of this discussion we agreed that this is not a concern for the P2P working group, but the tools working group will have to come up with something that mitigates the problem. I don't know, if we need to modify the "Advice to users", though. Because, once we found a way around the problem, we would could drop the addition again. Thus, it would only be a temporary addition to the standard, which I don't like very much. My idea for an interim solution would be that the measurement tool checks for the assertion and then points the user to additional (non-standard) info hints---ignored by the MPI but seen by the tool---that provide further guarantees for the tool. Something along the lines of "scorep_deterministic_matching = true/false". The tool would document this accordingly. What do you think? Cheers, Marc-Andre -- Marc-Andre Hermanns Jülich Aachen Research Alliance, High Performance Computing (JARA-HPC) Jülich Supercomputing Centre (JSC) Schinkelstrasse 2 52062 Aachen Germany Phone: +49 2461 61 2509 | +49 241 80 24381 Fax: +49 2461 80 6 99753 www.jara.org/jara-hpc email: [email protected]