[mpich-discuss] [EXTERNAL] Re: Modifying ssh calls for MPICH2

[Kekatpure, Rohan Deodatta (-EXP)]

I think I have more basic problems than what you are referring to:

I copy-pasted Reuti's code into a file named mpitest.c and tried to compile with

gcc -Wall mpitest.c

It failed to compile and issued following error(s):
=================================
Undefined symbols:
  "_ompi_mpi_comm_world", referenced from:
      _main in cc8tNiKW.o
  "_MPI_Comm_rank", referenced from:
      _main in cc8tNiKW.o
  "_MPI_Finalize", referenced from:
      _main in cc8tNiKW.o
  "_MPI_Init", referenced from:
      _main in cc8tNiKW.o
ld: symbol(s) not found
collect2: ld returned 1 exit status
==================================


Rohan

On Jan 17, 2012, at 3:09 PM, Jed Brown wrote:

On Tue, Jan 17, 2012 at 16:02, Reuti <reuti at staff.uni-marburg.de<mailto:reuti at staff.uni-marburg.de>> wrote:
main(int argc, char **argv)
{
  int node;

  int i,j;
  float f;

  MPI_Init(NULL,NULL);
  MPI_Comm_rank(MPI_COMM_WORLD, &node);

  printf("Hello World from Node %d.\n", node);
      for(j=0; j <= 100000; j++)
          for(i=0;i <= 100000; i++)
              f=i*2.718281828*i+i+i*3.141592654;

Well this is an odd spin loop because the compiler will happily remove it for you (note that MPICH2's mpicc wrapper very frequently has optimization flags in it). I would suggest sleep(3) instead, or, if you must, force the loop to actually be executed (e.g. seed the loop with the rank and use the result).
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