[MPICH] Initializing MPICH2

[William Gropp]

At 12:00 PM 7/20/2006, Steve Angelovich wrote:
>All,
>
>Is it possible to initialize mpich2 if the application has not been 
>started via mpiexec? I know the size of the group and the rank of each exec.
>
>I thought I read something about how to do this to help with debugging but 
>I can't find the document anymore.

You may be thinking of the ch_p4 device in MPICH-1, where there are 
instructions for doing this.  In MPICH2, there is a "process management 
interface" that separates the MPI executable from the process manager.  It 
is possible to mimic the process of starting up an MPI program, but it is 
more complex than in the MPICH-1 case.  One possibility would be to take 
the gforker implementation of mpiexec, and use it (by editing the source 
code for mpiexec.c to not fork the processes but instead register existing 
processes) to provide the required service (used to find the other MPI 
processes).

Bill


>Thanks,
>Steve
>
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William Gropp
http://www.mcs.anl.gov/~gropp