Looks to me like you are really saying that taskset didn't do what you expected - with that cmd line, OMPI didn't do anything to bind your procs. It just launched "taskset".

On Feb 15, 2013, at 11:34 AM, Kranthi Kumar <kranthipls@gmail.com> wrote:

With Open MPI this is the command I used:

mpirun -n 6 taskset -c 0,2,4,6,8,10 ./a.out

With intel library I set environment variable  I_MPI_PIN_MAPPING=6:0 0,1 2,2 4,3 6,4 8,5 10
and ran by saying 

mpirun -n 6 ./a.out
On Fri, Feb 15, 2013 at 10:30 PM, <users-request@open-mpi.org> wrote:
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Today's Topics:

   1. Core ids not coming properly (Kranthi Kumar)
   2. Re: Core ids not coming properly (Brice Goglin)


----------------------------------------------------------------------

Message: 1
Date: Fri, 15 Feb 2013 22:04:11 +0530
From: Kranthi Kumar <kranthipls@gmail.com>
Subject: [OMPI users] Core ids not coming properly
To: users@open-mpi.org
Message-ID:
        <CAL97QqiVvW+GKBBFPJN_bBovhnUgXKvMg0-NTYpd=1rsVsPt=w@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"

Hello Sir

Here below is the code which I wrote using hwloc for getting the bindings
of the processes.
I tested this code on SDSC Gordon Super Computer which has Open MPI 1.4.3
and on TACC Stampede which uses intel's MPI library IMPI.
With Open MPI I get all the core ids for all the processes as 0. Using
Intel MPI library I get different coreids. I tried even binding the
processes
in the command line using taskset. Open MPI gives me core id 0 for all the
processes whereas IMPI gives me correct bindings.
Please look into this


#include <stdio.h>
#include <sched.h>
#include <math.h>
#include "mpi.h"
#include <hwloc.h>
int main(int argc, char* argv[])
{
    int rank, size;
    cpu_set_t mask;
    long num;
    int proc_num(long num);

    hwloc_topology_t topology;
    hwloc_cpuset_t cpuset;
    hwloc_obj_t obj;

    MPI_Init(&argc, &argv);
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
    MPI_Comm_size(MPI_COMM_WORLD, &size);

    hwloc_topology_init ( &topology);
    hwloc_topology_load ( topology);

    hwloc_bitmap_t set = hwloc_bitmap_alloc();
    hwloc_obj_t pu;
    int err;

    err = hwloc_get_proc_cpubind(topology, getpid(), set,
HWLOC_CPUBIND_PROCESS);
    if (err) {
    printf ("Error Cannot find\n"), exit(1);
    }

    pu = hwloc_get_pu_obj_by_os_index(topology, hwloc_bitmap_first(set));
    printf ("Hello World, I am %d and pid: %d
coreid:%d\n",rank,getpid(),hwloc_bitmap_first(set));

    hwloc_bitmap_free(set);
    MPI_Finalize();
    fclose(stdout);
    return 0;
}
Thank You
--
Kranthi
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Message: 2
Date: Fri, 15 Feb 2013 17:46:25 +0100
From: Brice Goglin <Brice.Goglin@inria.fr>
Subject: Re: [OMPI users] Core ids not coming properly
To: Open MPI Users <users@open-mpi.org>
Message-ID: <511E6661.40608@inria.fr>
Content-Type: text/plain; charset="iso-8859-1"

IntelMPI binds processes by default, while OMPI doesn't. What's your
mpiexec/mpirun command-line?

Brice



Le 15/02/2013 17:34, Kranthi Kumar a ?crit :
> Hello Sir
>
> Here below is the code which I wrote using hwloc for getting the
> bindings of the processes.
> I tested this code on SDSC Gordon Super Computer which has Open MPI
> 1.4.3 and on TACC Stampede which uses intel's MPI library IMPI.
> With Open MPI I get all the core ids for all the processes as 0. Using
> Intel MPI library I get different coreids. I tried even binding the
> processes
> in the command line using taskset. Open MPI gives me core id 0 for all
> the processes whereas IMPI gives me correct bindings.
> Please look into this
>
>
> #include <stdio.h>
> #include <sched.h>
> #include <math.h>
> #include "mpi.h"
> #include <hwloc.h>
> int main(int argc, char* argv[])
> {
>     int rank, size;
>     cpu_set_t mask;
>     long num;
>     int proc_num(long num);
>
>     hwloc_topology_t topology;
>     hwloc_cpuset_t cpuset;
>     hwloc_obj_t obj;
>
>     MPI_Init(&argc, &argv);
>     MPI_Comm_rank(MPI_COMM_WORLD, &rank);
>     MPI_Comm_size(MPI_COMM_WORLD, &size);
>
>     hwloc_topology_init ( &topology);
>     hwloc_topology_load ( topology);
>
>     hwloc_bitmap_t set = hwloc_bitmap_alloc();
>     hwloc_obj_t pu;
>     int err;
>
>     err = hwloc_get_proc_cpubind(topology, getpid(), set,
> HWLOC_CPUBIND_PROCESS);
>     if (err) {
>     printf ("Error Cannot find\n"), exit(1);
>     }
>
>     pu = hwloc_get_pu_obj_by_os_index(topology, hwloc_bitmap_first(set));
>     printf ("Hello World, I am %d and pid: %d
> coreid:%d\n",rank,getpid(),hwloc_bitmap_first(set));
>
>     hwloc_bitmap_free(set);
>     MPI_Finalize();
>     fclose(stdout);
>     return 0;
> }
> Thank You
> --
> Kranthi
>
>
> _______________________________________________
> users mailing list
> users@open-mpi.org
> http://www.open-mpi.org/mailman/listinfo.cgi/users

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--
Kranthi
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