MTL/OFI: Lower priority when all procs are local

So far Vader is faster than OFI MTL for doing shared memory.
Therefore, let it run by default when all procs are local.

Reviewed-by: Spruit, Neil R <neil.r.spruit@intel.com>
Reviewed-by: Gopalakrishnan, Aravind <aravind.gopalakrishnan@intel.com>
Signed-off-by: Matias Cabral <matias.a.cabral@intel.com>

ompi/mca/mtl/ofi/mtl_ofi_component.c

@@ -116,8 +116,21 @@ ompi_mtl_ofi_component_register(void)
     int ret;
     mca_base_var_enum_t *new_enum = NULL;
     char *desc;
+    int num_total_procs = (int)ompi_process_info.num_procs;
+    /* num_local_peers does not include us in
+     * its calculation, so adjust for that */
+    int num_local_procs = (int)(1 + ompi_process_info.num_local_peers);
+
+    /* Lower priority when all porcesses are loal (vader is faster for shm).
+     * However, if running only one process assume it is ompi_info or this
+     * is most likely going to spawn.
+     */
+    if ((num_local_procs == num_total_procs) && (1 < num_total_procs)) {
+        param_priority = 10;
+    } else {
+        param_priority = 25;   /* for now give a lower priority than the psm mtl */
+    }
 
-    param_priority = 25;   /* for now give a lower priority than the psm mtl */
     mca_base_component_var_register(&mca_mtl_ofi_component.super.mtl_version,
                                     "priority", "Priority of the OFI MTL component",
                                     MCA_BASE_VAR_TYPE_INT, NULL, 0, 0,