Thanks. How will you let the MPI know the checkpoint is coming, to give it a fair chance to prepare to this and then recover after the checkpoint? This is akin to the MPI_Finalize/MPI_Init in some sense, midway thru the job, hence the analogy. -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Greg Bronevetsky Sent: Tuesday, February 17, 2009 6:21 PM To: MPI 3.0 Fault Tolerance and Dynamic Process Control working Group; MPI 3.0 Fault Tolerance and Dynamic Process Control working Group Subject: Re: [Mpi3-ft] Communicator Virtualization as a step forward
Consider interaction of the MPI_Init/MPI_Finalize with the underlying OS and job managers. It's about as undefined as that of the mentioned calls with the checkpointer. Nevertheless, many usable implementations can cope with that quite nicely. By the way, this is how the checkpoint/restarting could work as well, providing the checkpointer at hand with the MPI ready to be checkpointed/restarted at a well defined point of the MPI program. After all, this is how it is done now: a configuration flag tells the MPI what checkpointer to expect. This could be refined, turned into dynamic recognition of the active checkpointer, etc. This is all trivial.
Because this is a separate argument, I decided to answer it separately. I fully support this approach to providing checkpointing to MPI applications and I don't see any extensions to the MPI specification needed to support it. The only extensions that we've developed so far have poor semantics and thus boil down to having a single name for a bunch of semantically different operations that MPI may perform. At this point we might as well not standardize this name and let applications use multiple names for what is really a different operation on each combination of checkpointer and system. Greg Bronevetsky Post-Doctoral Researcher 1028 Building 451 Lawrence Livermore National Lab (925) 424-5756 [email protected] http://greg.bronevetsky.com _______________________________________________ mpi3-ft mailing list [email protected] http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-ft --------------------------------------------------------------------- Intel GmbH Dornacher Strasse 1 85622 Feldkirchen/Muenchen Germany Sitz der Gesellschaft: Feldkirchen bei Muenchen Geschaeftsfuehrer: Douglas Lusk, Peter Gleissner, Hannes Schwaderer Registergericht: Muenchen HRB 47456 Ust.-IdNr. VAT Registration No.: DE129385895 Citibank Frankfurt (BLZ 502 109 00) 600119052 This e-mail and any attachments may contain confidential material for the sole use of the intended recipient(s). Any review or distribution by others is strictly prohibited. If you are not the intended recipient, please contact the sender and delete all copies.