[mpich-discuss] How does hyday works?

[Dorier, Matthieu]

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 [balaji at anl.gov]
Sent: Tuesday, February 14, 2017 2:04 PM
To: discuss at mpich.org
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 <mdorier at anl.gov> 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     discuss at mpich.org
> To manage subscription options or unsubscribe:
> https://lists.mpich.org/mailman/listinfo/discuss

_______________________________________________
discuss mailing list     discuss at mpich.org
To manage subscription options or unsubscribe:
https://lists.mpich.org/mailman/listinfo/discuss
_______________________________________________
discuss mailing list     discuss at mpich.org
To manage subscription options or unsubscribe:
https://lists.mpich.org/mailman/listinfo/discuss