PSB From: mpiwg-ft [mailto:[email protected]] On Behalf Of George Bosilca Sent: Wednesday, November 27, 2013 2:48 PM To: MPI WG Fault Tolerance and Dynamic Process Control working Group Subject: Re: [mpiwg-ft] MPI_Comm_revoke behavior On Nov 27, 2013, at 20:33 , Richard Graham <[email protected]<mailto:[email protected]>> wrote: I am thinking about the next step, and have some questions on the semantics of MPI_Comm_revoke() What next step are you referring to? [rich] To the full recovery stage. Post what we are talking about now. - When the routine returns, can the communicator ever be used again ? If I remember correctly, the communicator is available for point-to-point traffic, but not collective traffic - is this correct ? A revoked communicator is unable to support any communication (point-to-point or collective) with the exception of agree and shrink. If this is not clear enough in the current version of the proposal we should definitively address it. [rich] does this mean all current state (aside from who is alive) associated with the communicator is gone ? Can't rely on continuing sending pending messages ? Looking forward, if one wants to restart the failed ranks (let's assume we add support for this), what can be assume about the "repaired" communicator ? What can't I assume about this communicator ? What you can assume depends on what is the meaning of "repaired". Already today one can spawn new processes and reconstruct a communicator identical to the original communicator before any fault. This can be done using MPI dynamics together with the agreement available in the ULFM proposal. [rich] This implies that all outstanding traffic is flushed - is this correct ? George. Rich _______________________________________________ mpiwg-ft mailing list [email protected]<mailto:[email protected]> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-ft