[mpich-discuss] Hydra issues

[Pavan Balaji]

Yup, you are right. I can reproduce the problem when I use more than one 
node. I'll look into this next week.

  -- Pavan

On 08/28/2009 02:46 PM, Scott Atchley wrote:
> On Aug 28, 2009, at 2:53 PM, Scott Atchley wrote:
> 
>> I tried your test app again and it starts immediately without NO_MPI 
>> set and is delayed when NO-MPI=1; the exact opposite of the above. I 
>> tested IMB 2.3 and it too is delayed.
> 
> 
> I modified your test app (see below). I eliminated the sleep() and 
> replaced it with busy work. I print it out at the end to avoid the 
> compiler removing the code (my gcc did).
> 
> If I run it with -n 4 over two nodes, I see the output from the local 
> host in real time (and interleaved). The other two ranks' output does 
> not appear until the end of the run and the output is serialized.
> 
> Scott
> 
> #include <stdio.h>
> #include <stdlib.h>
> #include "mpi.h"
> 
> int main(int argc, char *argv[])
> {
>    int i, use_mpi = 0, rank = -1;
>    long sum = 0L;
> 
>    use_mpi = (!(getenv("NO_MPI"))) ? 1 : 0;
> 
>    if (use_mpi) {
>        MPI_Init(&argc, &argv);
>        MPI_Comm_rank(MPI_COMM_WORLD, &rank);
>    }
> 
>    for (i = 0; i < 20; i++) {
>        int j;
> 
>        if (use_mpi)
>            MPI_Barrier(MPI_COMM_WORLD);
> 
>        printf("%d: Hello World!\n", rank);
>        for (j = 0; j < 10000000; j++) {
>            sum += j;
>            if (j > 0) sum /= j;
>        }
>    }
> 
>    if (use_mpi) {
>        MPI_Barrier(MPI_COMM_WORLD);
>        MPI_Finalize();
>    }
>    printf("%ld\n", sum);
> 
>    return 0;
> }

-- 
Pavan Balaji
http://www.mcs.anl.gov/~balaji