NAME

       OMPI_Affinity_str - Obtain prettyprint strings of processor affinity information for this process

SYNTAX

C Syntax

       #include <mpi.h>
       #include <mpi-ext.h>

       int OMPI_Affinity_str(ompi_affinity_fmt_type_t fmt_type,
                             char ompi_bound[OMPI_AFFINITY_STRING_MAX],
                             char current_binding[OMPI_AFFINITY_STRING_MAX],
                             char exists[OMPI_AFFINITY_STRING_MAX])

Fortran Syntax

       There is no Fortran binding for this function.

C++ Syntax

       There is no C++ binding for this function.

INPUT PARAMETERS

       fmt_type  An  enum  indicating  how  to  format  the  returned  ompi_bound  and  current_binding strings.
                 OMPI_AFFINITY_RSRC_STRING_FMT returns the string as  human-readable  resource  names,  such  as
                 "socket 0, core 0".

                 OMPI_AFFINITY_LAYOUT_FMT  returns  ASCII  art  representing  where  this  MPI  process is bound
                 relative to the machine resource layout.  For example "[.  B][.  .]"  shows  the  process  that
                 called  the  routine is bound to socket 0, core 1 in a system with 2 sockets, each containing 2
                 cores.

                 See below for more output examples.

OUTPUT PARAMETERS

       ompi_bound
                 A prettyprint string describing what processor(s) Open MPI bound this process to, or  a  string
                 indicating that Open MPI did not bind this process.

       current_binding
                 A  prettyprint  string  describing  what  processor(s) this process is currently bound to, or a
                 string indicating that the process is bound to  all  available  processors  (and  is  therefore
                 considered "unbound").

       exists    A prettyprint string describing the available sockets and sockets on this host.

DESCRIPTION

       Open  MPI  may bind a process to specific sockets and/or cores at process launch time.  This non-standard
       Open MPI function call returns prettyprint information about three things:

       Where Open MPI bound this process.
              The string returned in ompi_bound will either indicate that Open MPI did not bind this process  to
              anything, or it will contain a prettyprint description of the processor(s) to which Open MPI bound
              this process.

       Where this process is currently bound.
              Regardless of whether Open MPI bound this process or not, another entity may have bound  it.   The
              string  returned  in  current_binding  will  indicate what the current binding is of this process,
              regardless of what Open MPI may have done earlier.  The string returned will either indicate  that
              the process is unbound (meaning that it is bound to all available processors) or it will contain a
              prettyprint description of the sockets and cores to which the process is currently bound.

       What processors exist.
              As a convenience to the user, the exists string will contain  a  prettyprint  description  of  the
              sockets and cores that this process can see (which is usually all processors in the system).

Examples

       Example 1:  Print out processes binding using resource string format.

           int rank;
           char ompi_bound[OMPI_AFFINITY_STRING_MAX];
           char current_binding[OMPI_AFFINITY_STRING_MAX];
           char exists[OMPI_AFFINITY_STRING_MAX];

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

           OMPI_Affinity_str(OMPI_AFFINITY_RSRC_STRING_FMT,
                             ompi_bound, current_binding, exists);
           printf("rank %d: \n"
                  "       ompi_bound: %s\n"
                  "  current_binding: %s\n"
                  "           exists: %s\n",
                  rank, ompi_bound, current_binding, exists);
           ...

       Output of mpirun -np 2 -bind-to-core a.out:
       rank 0:
              ompi_bound: socket 0[core 0]
         current_binding: socket 0[core 0]
                  exists: socket 0 has 4 cores
       rank 1:
              ompi_bound: socket 0[core 1]
         current_binding: socket 0[core 1]
                  exists: socket 0 has 4 cores

       Output of mpirun -np 2 -bind-to-socket a.out:
       rank 0:
              ompi_bound: socket 0[core 0-3]
         current_binding: Not bound (or bound to all available processors)
                  exists: socket 0 has 4 cores
       rank 1:
              ompi_bound: socket 0[core 0-3]
         current_binding: Not bound (or bound to all available processors)
                  exists: socket 0 has 4 cores

       Example 2:  Print out processes binding using layout string format.

           int rank;
           char ompi_bound[OMPI_AFFINITY_STRING_MAX];
           char current_binding[OMPI_AFFINITY_STRING_MAX];
           char exists[OMPI_AFFINITY_STRING_MAX];

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

           OMPI_Affinity_str(OMPI_AFFINITY_LAYOUT_FMT,
                             ompi_bound, current_binding, exists);
           printf("rank %d: \n"
                  "       ompi_bound: %s\n"
                  "  current_binding: %s\n"
                  "           exists: %s\n",
                  rank, ompi_bound, current_binding, exists);
           ...

       Output of mpirun -np 2 -bind-to-core a.out:
       rank 0:
              ompi_bound: [B . . .]
         current_binding: [B . . .]
                  exists: [. . . .]
       rank 1:
              ompi_bound: [. B . .]
         current_binding: [. B . .]
                  exists: [. . . .]

       Output of mpirun -np 2 -bind-to-socket a.out:
       rank 0:
              ompi_bound: [B B B B]
         current_binding: [B B B B]
                  exists: [. . . .]
       rank 1:
              ompi_bound: [B B B B]
         current_binding: [B B B B]
                  exists: [. . . .]

See Also

       mpirun(1)