Up-port of change for 2.x: if user directs oversubscribe, then do not bind as we will otherwise overload resources

orte/mca/rmaps/base/rmaps_base_map_job.c

@@ -258,10 +258,14 @@ void orte_rmaps_base_map_job(int fd, short args, void *cbdata)
         } else {
             orte_mapping_policy_t mpol;
             mpol = ORTE_GET_MAPPING_POLICY(jdata->map->mapping);
-            /* if the user explicitly mapped-by some object, then we default
+            /* if the user specified that we allow oversubscription, then do not bind.
+             * otherwise, if the user explicitly mapped-by some object, then we default
              * to binding to that object */
-            if (ORTE_MAPPING_POLICY_IS_SET(jdata->map->mapping) &&
-                ORTE_MAPPING_BYBOARD < mpol && mpol < ORTE_MAPPING_BYSLOT) {
+            if ((ORTE_MAPPING_SUBSCRIBE_GIVEN & ORTE_GET_MAPPING_DIRECTIVE(orte_rmaps_base.mapping)) &&
+                !(ORTE_MAPPING_NO_OVERSUBSCRIBE & ORTE_GET_MAPPING_DIRECTIVE(orte_rmaps_base.mapping))) {
+                OPAL_SET_BINDING_POLICY(jdata->map->binding, OPAL_BIND_TO_NONE);
+            } else if (ORTE_MAPPING_POLICY_IS_SET(jdata->map->mapping) &&
+                    ORTE_MAPPING_BYBOARD < mpol && mpol < ORTE_MAPPING_BYSLOT) {
                 if (ORTE_MAPPING_BYHWTHREAD == mpol) {
                     opal_output_verbose(5, orte_rmaps_base_framework.framework_output,
                                         "mca:rmaps[%d] binding not given - using byhwthread", __LINE__);