It works in the implementation, so I’m not sure what you mean. I just mean it’s not allowed per the “spec” (or whatever sparse documentation we have that others use for implementing PMI). — Pavan
On Apr 24, 2015, at 7:22 AM, Jeff Hammond <[email protected]> wrote:
Why not implement the equivalent of the ref-counting init proposal or at least the simple things that allows multiple inits but only one finalize? Is it that you don't see the effort being worthwhile or because there is a principled reason (PMI semantics should match MPI)?
Given that e.g. PGAS runtimes may want to use PMI for bootstrapping (I do this with DMAPP code on Cray, for example), it seems to benefit user experience to support this behavior.
Thanks,
Jeff
On Fri, Apr 24, 2015 at 1:12 AM, Balaji, Pavan <[email protected]> wrote:
Multiple PMI Inits are not allowed. It might work in the current implementation within MPICH, but is not safe.
If you are looking for MPICH specific behavior, you can look for the PMI_ID and PMI_RANK environment variables instead to get your rank.
— Pavan
On Apr 21, 2015, at 11:17 PM, Jeff Hammond <[email protected]> wrote:
So MPICH doesn't fail when I try this on my Mac, but it would be good to know if I have a reasonable expectation of doing this in general.
Thanks,
Jeff
jrhammon-mac01:ENDPOINTS jrhammon$ mpiexec -n 4 ./a.out PMI says I am 2 of 4 PMI says I am 0 of 4 PMI says I am 1 of 4 PMI says I am 3 of 4 MPI says I am 0 of 4 (provided=1) MPI says I am 2 of 4 (provided=1) MPI says I am 3 of 4 (provided=3) MPI says I am 1 of 4 (provided=3)
jrhammon-mac01:ENDPOINTS jrhammon$ cat pmi.c #include <stdio.h> #include <stdlib.h>
/*#include <pmi.h>*/ int PMI_Init( int *spawned ); int PMI_Finalize( void ); int PMI_Get_size( int *size ); int PMI_Get_rank( int *rank );
#include <mpi.h>
int main(int argc, char * argv[]) { int has_parent; PMI_Init(&has_parent);
int rank, size; PMI_Get_size(&size); PMI_Get_rank(&rank);
printf("PMI says I am %d of %d \n", rank, size); fflush(stdout);
int requested = (rank%2==0) ? MPI_THREAD_FUNNELED : MPI_THREAD_MULTIPLE; int provided; MPI_Init_thread(&argc, &argv, requested, &provided);
int wsize, wrank; MPI_Comm_size(MPI_COMM_WORLD, &wsize); MPI_Comm_rank(MPI_COMM_WORLD, &wrank);
printf("MPI says I am %d of %d (provided=%d)\n", wrank, wsize, provided); fflush(stdout);
MPI_Finalize(); //PMI_Finalize(); /* required? */
return 0; }
On Tue, Apr 21, 2015 at 9:09 PM, Jeff Hammond <[email protected]> wrote:
Is it valid in _MPICH_ to make calls to PMI before MPI is initialized? I am interested in PMI_Init, PMI_Get_size and PMI_Get_rank.
The motivating use case is to initialize e.g. half my ranks with MPI_THREAD_FUNNELED and the other half with MPI_THREAD_MULTIPLE but not use MPMD launching.
I have two reasons for wanting to do it this way. First, it is otherwise unnecessary to use MPMD since I can branch at the top of my code and meet the requirements of FUNNELED and MULTIPLE. Second, I might be interested in running my code on a supercomputer with an MPICH-based MPI implementation that does not support MPMD launching in an unrestricted manner.
If MPICH can handle this, then I will worry about whether or not the aforementioned supercomputer can. It is my assumption that, if MPICH cannot handle this, then the MPICH derivative in question cannot either.
Thanks,
Jeff
-- Jeff Hammond [email protected] http://jeffhammond.github.io/
-- Jeff Hammond [email protected] http://jeffhammond.github.io/ _______________________________________________ To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/devel
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-- Jeff Hammond [email protected] http://jeffhammond.github.io/ _______________________________________________ To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/devel