Is the key-value server located on the machine that ran mpiexec, or on one of the machine in the hostfile? Thanks, Matthieu ________________________________________ From: Balaji, Pavan [[email protected]] Sent: Tuesday, February 14, 2017 2:04 PM To: [email protected] Subject: Re: [mpich-discuss] How does hyday works? Well, not exactly. The environment variables tell MPICH how to connect to a key-value server. Then each process puts its business card (e.g., IP address and port) into the key-value server and all processes can query this information for the target process they want to communicate with. -- Pavan
On Feb 14, 2017, at 11:19 AM, Dorier, Matthieu <[email protected]> wrote:
Hi,
I'd like to have a better understanding of how Hydra works and how MPI processes "discover" how to connect to one another. I'm guessing something roughly like this happens:
- mpiexec launches and ssh connection to each node, and sets some environment variables that will indicate to the created processes how to connect to one another; - MPI processes are created, and when calling MPI_Init they read the right environment variables to build MPI_COMM_WORLD.
Is this correct? If so, where could I find information about the environment variables at play?
Thanks,
Matthieu _______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss
_______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss _______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss