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

[Reuti]

Am 17.01.2012 um 23:19 schrieb 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:

ompi - do you have Open MPI installed too?

-- Reuti


>       _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> 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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